Citrate Synthase

Skeletal muscle buffering capacity (βm), enzyme activities and exercise performance were measured before and after 4 weeks of high-intensity, sub maximal␣interval training (HIT) undertaken by six well-trained competitive cyclists [mean maximal oxygen consumption ( O2max) = 66.2 ml · kg−1 · min−1]. HIT replaced a portion of habitual endurance training and consisted of six sessions, each of six to eight repetitions of 5 min duration at 80% of peak sustained power output (PPO) separated by 1 min of recovery. βm increased from 206.6 (17.9) to 240.4 (34.1) μmol H+ · g muscle dw−1 · pH−1 after HIT (P = 0.05). PPO, time to fatigue at 150% PPO (TF150) and 40-km cycle time trial performance (TT40) all significantly improved after HIT (P < 0.05). In contrast, there was no change in the activity of either phosphofructokinase or citrate synthase. In addition, βm correlated significantly with TT40 performance before HIT (r = −0.82, P < 0.05) and the relationship between change in βm and change in TT40 was close to significance (r = −0.74). βm did not correlate with TF150. These results indicate that βm may be an important determinant of relatively short-duration (< 60 min) endurance cycling activity and responds positively to just six sessions of high-intensity, submaximal interval training.

The aim of this study was to evaluate the changes in aerobic and anaerobic metabolism produced by a newly devised short training programme. Five young male volunteers trained daily for 2 weeks on a cycle ergometer. Sessions consisted of 15-s all-out repetitions with 45-s rest periods, plus 30-s all-out repetitions with 12-min rest periods. The number of repetitions was gradually increased up to a maximum of seven. Biopsy samples of the vastus lateralis muscle were taken before and after training. Performance changes were evaluated by two tests, a 30-s all-out test and a maximal progressive test. Signi®cant increases in phosphocreatine (31%) and glycogen (32%) were found at the end of training. In addition, a signi®cant increase was observed in the muscle activity of creatine kinase (44%), phosphofructokinase (106%), lactate dehydrogenase (45%), 3-hydroxy-acyl-CoA dehydrogenase (60%) and citrate synthase (38%). After training, performance of the 30-s all-out test did not increase signi®cantly, while in the maximal progressive test, the maximum oxygen consumption increased from mean (SD) 57.3 (2.6) ml á min )1 á kg )1 to 63.8 (3.0) ml á min )1 á kg )1 , and the maximum load from 300 (11) W to 330 (21) W; all changes were signi®cant. In conclusion, this new protocol, which utilises short durations, high loads and long recovery periods, seems to be an eective programme for improving the enzymatic activities of the energetic pathways in a short period of time.

Skeletal muscle buffering capacity ( m), enzyme activities and exercise performance were measured before and after 4 weeks of high-intensity, submaximal interval training (HIT) undertaken by six welltrained competitive cyclists [mean maximal oxygen consumption (V O 2max ) = 66.2 ml · kg -1 · min -1 ]. HIT replaced a portion of habitual endurance training and consisted of six sessions, each of six to eight repetitions of 5 min duration at 80% of peak sustained power output (PPO) separated by 1 min of recovery. m increased from 206.6 (17.9) to 240.4 (34.1) mol H + · g muscle dw )1 · pH -1 after HIT (P = 0.05). PPO, time to fatigue at 150% PPO (TF 150 ) and 40-km cycle time trial performance (TT 40 ) all significantly improved after HIT (P < 0.05). In contrast, there was no change in the activity of either phosphofructokinase or citrate synthase. In addition, m correlated significantly with TT 40 performance before HIT (r = )0.82, P < 0.05) and the relationship between change in m and change in TT 40 was close to significance (r = )0.74). m did not correlate with TF 150 . These results indicate that m may be an important determinant of relatively short-duration (< 60 min) endurance cycling activity and responds positively to just six sessions of high-intensity, submaximal interval training.

The present investigation deals with citric acid production by some selected mutant strains of Aspergillus niger from cane molasses in 250 ml Erlenmeyer flasks. For this purpose, a conidial suspension of A. niger GCB-75, which produced 31.1 g/l citric acid from 15% (w/v) molasses sugar, was subjected to UV-induced mutagenesis. Among the 3 variants, GCM-45 was found to be a better producer of citric acid (50.0 ± 2a) and it was further improved by chemical mutagenesis using N-methyl, N-nitro-N-nitrosoguanidine (MNNG). Out of 3,2-deoxy-D D -glucose resistant variants, GCMC-7 was selected as the best mutant, which produced 96.1 ± 1.5 g/l citric acid 168 h after fermentation of potassium ferrocyanide and H 2 SO 4 pre-treated blackstrap molasses in Vogel's medium. On the basis of kinetic parameters such as volumetric substrate uptake rate (Q s ), and specific substrate uptake rate (q s ), the volumetric productivity, theoretical yield and specific product formation rate, it was observed that the mutants were faster growing organisms and produced more citric acid. The mutant GCMC-7 has greater commercial potential than the parental strain with regard to citrate synthase activity. The addition of 2.0 · 10 À5 M MgSO 4 AE 5H 2 O into the fermentation medium reduced the Fe 2þ ion concentration by counter-acting its deleterious effect on mycelial growth. The magnesium ions also induced a loose-pelleted form of growth (0.6 mm, diameter), reduced the biomass concentration (12.5 g/l) and increased the volumetric productivity of citric acid monohydrate (113.6 ± 5 g/l).

A highly specific real-time polymerase chain reaction (PCR) assay was developed to detect spotted fever and typhus group rickettsiae using the citrate synthase gene as the target. The assay amplified rickettsial members of the spotted fever and typhus group including Rickettsia akari, R. australis, R. conorii, R. honei, &quot;R. marmionii,&quot; R. sibirica, R. rickettsii, R. typhi, and R. prowazekii. The ancestral group rickettsia, R. bellii, did not produce a positive reaction, nor did other members of the order Rickettsiales or any non-rickettsial bacteria. The assay had a sensitivity of one target copy number per reaction as determined by serial dilutions of a plasmid containing a spotted fever group target sequence. This quantitative assay is useful for the enumeration of rickettsiae in clinical specimens and the diagnosis of rickettsial illnesses, when rickettsial numbers are very low.

Forty-one autumn-born Friesian bull calves were allocated to two production systems (Extensive=`E' and Intensive=`I'). In the E-system, animals were loose-housed and fed a roughage-based diet from October to May, followed by a grazing period from May to October. Ten animals were slaughtered directly from pasture (360 kg BW) and 11 after a 10-week ®nishing feeding in tie-stalls (460 kg). E-bulls were compared with intensively fed tie-stall housed young bulls (I) slaughtered at comparable weights (360 kg, n=11 and 460 kg, n=9). Semitendinosus (ST), longissimus dorsi (LD), and supraspinatus (SU) muscles were analysed histochemically, and the meat analysed for colour and pigmentation. In LD and SU, Type I % was higher in E-compared with I-bulls (P<0.05±0.006). In ST and LD, Type IIA % was higher in E-compared with I-bulls (P<0.01±0.009). As a result, Type IIB % was lower in all three muscles in E-compared with I-bulls (P<0.05±0.001). In E-compared with I-bulls, Type IIA and IIB ®bre areas were larger in ST (P<0.05±0.03) and capillarization was higher in both ST and LD (P<0.001). In all three muscles, the activity of citrate synthase was higher (P<0.07±0.001) and that of lactate dehydrogenase lower (P<0.003±0.001) in E-compared with I-bulls. E-bulls had lower glycogen content than I-bulls in ST and LD at 360 kg, but higher at 460 kg following ®nishing feeding (P<0.008± 0.001). Meat colour (lightness) was darker (P<0.001) and pigmentation was higher (P<0.001) in ST and LD of E-compared with I-bulls, with no eects in SU. In conclusion, histochemically dierent muscles respond dierently to changes in the production system, and dierences between the extensive and the intensive production system were narrowed after the ®nishing feeding. #

LM. Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling. We determined the effects of varying daily carbohydrate intake by providing or withholding carbohydrate during daily training on endurance performance, whole body rates of substrate oxidation, and selected mitochondrial enzymes. Sixteen endurance-trained cyclists or triathletes were pair matched and randomly allocated to either a high-carbohydrate group (High group; n ϭ 8) or an energy-matched low-carbohydrate group (Low group; n ϭ 8) for 28 days. Immediately before study commencement and during the final 5 days, subjects undertook a 5-day test block in which they completed an exercise trial consisting of a 100 min of steady-state cycling (100SS) followed by a 7-kJ/kg time trial on two occasions separated by 72 h. In a counterbalanced design, subjects consumed either water (water trial) or a 10% glucose solution (glucose trial) throughout the exercise trial. A muscle biopsy was taken from the vastus lateralis muscle on day 1 of the first test block, and rates of substrate oxidation were determined throughout 100SS. Training induced a marked increase in maximal citrate synthase activity after the intervention in the High group (27 vs. 34 mol·g Ϫ1 ·min Ϫ1 , P Ͻ 0.001). Tracer-derived estimates of exogenous glucose oxidation during 100SS in the glucose trial increased from 54.6 to 63.6 g (P Ͻ 0.01) in the High group with no change in the Low group. Cycling performance improved by ϳ6% after training. We conclude that altering total daily carbohydrate intake by providing or withholding carbohydrate during daily training in trained athletes results in differences in selected metabolic adaptations to exercise, including the oxidation of exogenous carbohydrate. However, these metabolic changes do not alter the training-induced magnitude of increase in exercise performance. citrate synthase; exogenous glucose oxidation; fat oxidation CURRENT SPORTS NUTRITION GUIDELINES recommend that endurance-trained athletes undertake their daily training sessions with high-carbohydrate availability (34). This is based on clear evidence that strategies such as elevating preexercise muscle glycogen stores, consuming a preexercise carbohydrate meal, or eating carbohydrate during exercise increase endurance (4, 28, 36) and performance (17, 33, 38) of a single bout of prolonged exercise. However, the results of several recent studies have challenged the idea that this is the best approach to maximize the outcomes of chronic adap-

Tick-transmitted diseases like tick-borne encephalitis and Lyme borreliosis have been well known in Germany for decades. Ongoing research now gives an additional focus to a broad range of other bacteria and parasites in ticks like Anaplasma phagocytophilum, former Ehrlichia sp., Rickettsia sp. and Babesia sp. Knowledge about the prevalence of these infectious agents in ticks is an important prerequisite for risk assessment of human diseases. Therefore nymphs and adult Ixodes ricinus ticks were collected and examined for Anaplasma phagocytophilum (n = 5424 ticks), Rickettsia sp. (n = 1187), and Babesia sp. (n = 3113). For the detection of Anaplasma phagocytophilum, DNA from the 16S rDNA gene was amplified by nested PCR and hybridized with a DIG-labeled oligonucleotide probe. The examination of Rickettsia sp. was performed by single PCR. A partial sequence of the citrate synthase gene was amplified. As a target for the detection of Babesia sp., DNA from the 18S rDNA gene was amplified...

A highly specific real-time polymerase chain reaction (PCR) assay was developed to detect spotted fever and typhus group rickettsiae using the citrate synthase gene as the target. The assay amplified rickettsial members of the spotted fever and typhus group including Rickettsia akari, R. australis, R. conorii, R. honei, "R. marmionii," R. sibirica, R. rickettsii, R. typhi, and R. prowazekii. The ancestral group rickettsia, R. bellii, did not produce a positive reaction, nor did other members of the order Rickettsiales or any non-rickettsial bacteria. The assay had a sensitivity of one target copy number per reaction as determined by serial dilutions of a plasmid containing a spotted fever group target sequence. This quantitative assay is useful for the enumeration of rickettsiae in clinical specimens and the diagnosis of rickettsial illnesses, when rickettsial numbers are very low.

Ecologic and bacteriologic observations of small mammals captured in Yunnan Province in the People's Republic of China indicated that Bartonella infections occurred at a high prevalence among some rodent species. Sequence analyses of the citrate synthase genes of these Bartonella demonstrated that rodents in this region harbored a diverse assemblage of strains. The Bartonella isolates obtained from Apodemus, Eothenomys, and Rattus typically clustered separately by genus of rodent host. Cultures obtained from Rattus rats were genetically related to Bartonella elizabethae, a recognized human pathogen. The finding of Bartonella species in a high proportion of the rodent samples from Yunnan suggests the need to investigate whether these agents might be responsible for cases of febrile illnesses of unknown etiology in southern China and elsewhere in southeastern Asia.

Background: In the last ten years, deficiencies in tricarboxylic acid cycle (TCAC) enzymes have been shown to cause a wide spectrum of human diseases, including malignancies and neurological and cardiac diseases. A prerequisite to the identification of disease-causing TCAC enzyme deficiencies is the availability of effective enzyme assays.

The aim of this study was to compare metabolic and digestive enzyme activities in fish with different growth capacities using growth hormone transgenic and nontransgenic coho salmon (Oncorhynchus kisutch) as a model system. The following enzyme activities were measured: trypsin and chymotrypsin in pyloric caeca, alkaline phosphatase in intestine, pyruvate kinase (PK), lactate dehydrogenase (LDH) and citrate synthase (CS) in gills and white muscle. Transgenic salmon showed higher LDH activity in muscle and PK activities in muscle and gills, whereas chymotrypsin activity in pyloric caeca was higher in the control group. No significant differences were observed between transgenic and control groups for CS, trypsin and alkaline phosphatase activities. The small or no differences observed in this study suggests that the enzyme activities measured were not related to the high growth rate of the transgenic coho salmon. D

Temperature has a major impact on the physiological processes of freshwater invertebrates. Despite the endangered status of many freshwater mussel species and the potential effect of global warming on North America's northern aquatic habitats, thermal sensitivity of the metabolic apparatus of freshwater bivalves has received little attention. By examining the thermal sensitivity of 10 key metabolic enzymes and in situ growth rates of latitudinally separated populations (temperate and subarctic) of two closelyrelated Pyganodon species from northeastern North America, we provide the first insights into thermal sensitivity of key enzymes of energy and reactive oxygen species metabolism in relation to habitat localization and growth performance. The subarctic population of Pyganodon grandis displayed higher in situ growth rates than the temperate population of Pyganodon fragilis. The subarctic population of P. grandis had a lower mitochondrial capacity as expressed by citrate synthase and cytochrome c oxidase but displayed similar electron transport system (ETS) and higher isocitrate dehydrogenase capacities. Our results suggest that higher growth performance of the subarctic population of P. grandis is not associated with higher aerobic capacity. The high thermal sensitivity of mitochondrial enzymes in subarctic population of P. grandis might rather reflect enhanced stenothermy. The higher electron transport system/cytochrome c oxidase ratio for the subarctic P. grandis species than P. fragilis might affect mitochondrial regulation or reactive oxygen species production. Antioxidant enzymes displayed lower Q 10 s suggesting thermal independence of antioxidant capacity.

Diurnal activity is characteristic of many toad species, including Bufo granulosus from the Brazilian semi-arid biome called the Caatinga. Because of their patterns of activity, juvenile toads are exposed to hot and dehydrating conditions. Our investigation focuses on temperature and water relationships, and is based on the prediction that anuran diurnal activity in a semi-arid environment must be associated with morphological, physiological and behavioral traits enhancing thermal tolerances, capacity for performance at high temperatures and water balance. To test specific hypothesis related with this prediction, we investigated postmetamorphic B. granulosus and collected data on thermal tolerances and preferences, thermal safety margins, thermal dependence of locomotor behavior, thermal and kinetic properties of citrate synthase (CS), and skin morphophysiology. This information was compared with additional data from adult conspecifics and adult toads from sympatric species or from species from more moderate environments. We found that juvenile B. granulosus exhibit the highest critical maximum temperature reported for toads (44.2°C) and are well suited to move at high temperatures. However, and in contrast with juveniles of other Bufo species, they do not show thermal preferences in a gradient and appear to hydroregulate more than thermoregulate. The CS of adult and juvenile toads shows typical patterns of thermal sensibility, but the thermal stability of this enzyme is much higher in juveniles than in adult Bufo of any other species studied. The inguinal skin exhibits a complex folding pattern and seems highly specialized for capillary water uptake. Diurnal activity in juvenile B. granulosus is possible given high thermal tolerances, keen ability to detect and uptake water, and avoidance behaviors. Comparative Biochemistry and Physiology, Part A 147 (2007) 647 -657 www.elsevier.com/locate/cbpa ☆ This paper is part of the 3rd special issue of CBP dedicated to The Face of Latin American Comparative Biochemistry and Physiology organized by Marcelo Hermes-Lima (Brazil) and co-edited by Carlos Navas (Brazil), Rene Beleboni (Brazil), Rodrigo Stabeli (Brazil), Tania Zenteno-Savín (Mexico) and the editors of CBP. This issue is dedicated to the memory of two exceptional men, Peter L. Lutz, one of the pioneers of comparative and integrative physiology, and Cicero Lima, journalist, science lover and Hermes-Lima's dad.

A B S T R A C T Sperm are often stored, for a long time after mating, in females of various animal species. In case of the queen honeybee (Apis mellifera), sperm remain fertile for several years in the spermatheca. Little information is available regarding the effect of long-term storage of sperm on its fertility. To evaluate this, enzymes and/or sperm have been analysed from the spermatheca of 75 queens of various ages (0 year Y0, n = 14; one year Y1, n = 14; two years Y2, n = 7; virgin queen VQ, n = 40) and semen samples have been taken from 46 drones. The sperm from the spermatheca of older queens move more slowly (F = 11.45, P < 0.0001) and show different movement patterns (Chi 2 = 90.0, P < 0.0001) from those of the other groups. The spermatheca content of differently aged mated queens differ significantly with respect to the activities of lactate dehydrogenase (F = 3.37, P < 0.05), citrate synthase (F = 6.24, P < 0.005) and arginine kinase (F = 9.44, P < 0.0006). Glyceraldehyde 3-phosphate dehydrogenase (F = 0.10, P = 0.91) does not differ significantly. The results suggest considerable changes in the energy metabolic profile of the spermatheca tissue, of the sperm or of both during sperm storage. ß

The extant global Ephemeroptera fauna is represented by over 3,000 described species in 42 families and more than 400 genera. The highest generic diversity occurs in the Neotropics, with a correspondingly high species diversity, while the Palaearctic has the lowest generic diversity, but a high species diversity. Such distribution patterns may relate to how long evolutionary processes have been carrying on in isolation in a bioregion. Over an extended period, there may be extinction of species, but evolution of more genera. Dramatic extinction events such as the K-T mass extinction have affected current mayfly diversity and distribution. Climatic history plays an important role in the rate of speciation in an area, with regions which have been climatically stable over long periods having fewer species per genus, when compared to regions subjected to climatic stresses, such as glaciation. A total of 13 families are endemic to specific bioregions, with eight among them being monospecific. Most of these have restricted distributions which may be the result of them being the relict of a previously more diverse, but presently almost completely extinct family, or may be the consequence of vicariance events, resulting from evolution due to long-term isolation.

Skeletal muscle buffering capacity (βm), enzyme activities and exercise performance were measured before and after 4 weeks of high-intensity, sub maximal␣interval training (HIT) undertaken by six well-trained competitive cyclists [mean maximal oxygen consumption ( O2max) = 66.2 ml · kg−1 · min−1]. HIT replaced a portion of habitual endurance training and consisted of six sessions, each of six to eight repetitions of 5 min duration at 80% of peak sustained power output (PPO) separated by 1 min of recovery. βm increased from 206.6 (17.9) to 240.4 (34.1) μmol H+ · g muscle dw−1 · pH−1 after HIT (P = 0.05). PPO, time to fatigue at 150% PPO (TF150) and 40-km cycle time trial performance (TT40) all significantly improved after HIT (P < 0.05). In contrast, there was no change in the activity of either phosphofructokinase or citrate synthase. In addition, βm correlated significantly with TT40 performance before HIT (r = −0.82, P < 0.05) and the relationship between change in βm and change in TT40 was close to significance (r = −0.74). βm did not correlate with TF150. These results indicate that βm may be an important determinant of relatively short-duration (< 60 min) endurance cycling activity and responds positively to just six sessions of high-intensity, submaximal interval training.

OBJECTIVE: To investigate interrelationships between muscle ®bre type, respiratory exchange ratio (RER) during exercise at a ®xed workload and adiposity. DESIGN: Cross-sectional study. SUBJECTS: 21 untrained, healthy male subjects. MEASUREMENTS: Body fat composition by dual-energy X-ray absorptiometry (DEXA). Exercise test at 55% of V Á O 2max , muscle ®bre type composition, muscle NADH and citrate synthase enzyme activity levels; serum insulin, glucose and cortisol concentrations. RESULTS: Percent body fat was inversely correlated to the proportion of type I muscle ®bres (r 7 0.55, P`0.02). In addition percent trunk fat was negatively correlated with percent type I ®bres (r 7 0.58, P`0.01) while this relationship was not present for percent leg fat. There was no relation between RER at rest or during exercise and muscle ®bre type composition or percent body fat. CONCLUSION: Body fat and percent type I muscle ®bres were correlated, supporting skeletal muscle ®bre type as a potential etiological factor in obesity. No correlation was observed between percent body fat and substrate oxidation at rest or during moderate exercise, indicating that muscle fuel substrate mix does not appear to provide a mechanism for this relation under either condition.

The nereidid Nereis (Neanthes) virens undergoes drastic behavioural, morphological and physiological changes during its sexual maturation (epitoky). This metamorphosis prepares benthic worms for a brief pelagic existence devoted to mating although in N. virens only mature males leave their burrows to swarm. After spawning, individuals of both sexes die. Specific adjustments of energy metabolism pathway allowing higher muscular activity and swimming capacity remain to be eluded. This study compared atokous worms (immature) and epitokous (mature) swimming males and benthic females of N. virens to detect metabolic changes that could occur during epitoky. Epitokous males showed significantly higher electron transport system, citrate synthase and aspartate aminotransferase activities (p b 0.01) and significantly lower lactate dehydrogenase activity (p b 0.01) compared to atokous worms and epitokous females. There was no difference in antioxidant enzyme capacities between epitokes and atokes. Lipase and trypsin activities were significantly lower (p b 0.01) in epitokous males. The enzymatic changes observed are likely related to the metabolic adjustments required to support higher swimming abilities. Maintenance of antioxidant capacities could be related to protection of germinal tissues more than long term survival, since N. virens die after spawning.

Gene sequences of small portions of the genome are often used for premature detailed taxonomic changes, neglecting polyphasic taxonomy, which should also consider phenotypical characteristics. Three examples are given: (i) Recently, members of the genera Eperythrozoon and Haemobartonella have been moved, correctly so, from the Rickettsiales to the Mycoplasmatales, but were assigned to the genus Mycoplasma, mostly on the basis of 16S rRNA sequence analysis. Not only is the 16S rRNA sequence similarity between 'classical' Mycoplasma and these species of Eperythrozoon and Haemobartonella less than that between some other well-recognised bacterial genera, but their biological differences amply justify their classification in different genera of the Mycoplasmatales. Furthermore, the move creates considerable confusion, as it necessitates new names for some species, with more confusion likely to come when the 16S rRNA sequences of the type species of Eperythrozoon, a name which has priority over Mycoplasma, will be analysed. (ii) In the Rickettsiales, members of the genera Anaplasma, Ehrlichia, Cowdria, Neorickettsia and Wolbachia are so closely related phylogenetically on the basis of 16S rRNA sequences, and for some also of groESL operon sequences, that they have recently been fused, correctly so, into one family, the Anaplasmataceae, while the tribes Ehrlichieae and Wolbachieae have been abolished. Sequence diversity within the 'classical' genus Ehrlichia has led to classifying E. phagocytophila (including E. equi and the agent of human granulocytic ehrlichiosis), E. platys and E. bovis in the genus Anaplasma, while others have been retained in Ehrlichia, which also includes Cowdria ruminantium. E. sennetsu and E. risticii have been transferred to the genus Neorickettsia. 16S rRNA and GroEL sequences of 'classical' Anaplasma and some members of 'classical' Ehrlichia do show a close relationship, but differences in citrate synthase gene sequences, the GC content of this gene, and sequences of the gene encoding the b-subunit of RNA polymerase, not to speak of the phenotypical differences, do not justify the fusion into one genus. Because of the phylogenetical diversity in Ehrlichia it is recommended that a new genus name be created for the E. phagocytophila genogroup (and E. platys and E. bovis). (iii) One of the conclusions of studies on the phylogeny of ticks of the subfamilies Rhipicephalinae and Hyalomminae, based on nucleotide sequences from 12S rRNA, cytochrome c oxidase I, the internal transcribed spacer 2, 18S rRNA, as well as morphological characters, is that Boophilus should be considered as a subgenus of Rhipicephalus. While Boophilus and Rhipicephalus are undoubtedly close, the obviously important morphological and biological differences between the genera Rhipicephalus and Boophilus are thus overruled by similarities in the sequences of a number of genes and this leads to considerable confusion. Polyphasic taxonomy amply justifies maintaining Boophilus as a separate genus, phylogenetically near to Rhipicephalus. This note is a plea for a cautious and balanced approach to taxonomy, taking into account molecular genotypical information, as far as is possible from different genes, as well as phenotypical characteristics.

Rickettsia africae was identified in seven (6%) of 118 patients with acute fevers of unknown etiology proven not to be malaria or typhoid fever from clinics along the coastal region of Cameroon by polymerase chain reaction (PCR) amplification and sequencing of the citrate synthase (gltA) and outer membrane protein A (ompA) genes of Rickettsia. The majority (71%) of the patients were female. Clinical manifestations included fever (100%), headache (71%), myalgia (71%), arthralgia (43%), pulmonary involvement (29%), and diffuse rash (14%). Moreover, R. africae was detected by PCR amplification and sequence analysis of the gltA and ompA genes in 62 (75%) of 83 adult Amblyomma variegatum ticks collected from cattle in the same region. These results confirm the presence of a previously unrecognized infectious disease in the indigenous Cameroonian population, as well as extend the established range of R. africae.

Feed management is an important factor for successful aquaculture, especially when it affects gonad maturation. In this context, the present study evaluates the effects of long term starvation (1F-3S: one-month feedingthree-month starvation) and starvation/re-feeding (2S-2F: two-month starvationtwo-month refeeding) on gonad maturation, hematological/biochemical indices and proximate composition of liver and muscle of vitelogenic sea bass. In males, all the fish in the control group (4F-0S: four-month feedingzeromonth starvation) reached the maturity stage S2 (Mature), while only 33% and 75% reached that stage in the 1F-3S and 2S-2F groups, respectively. In females, the percentages of immature gonads were 80%, 25% and 50% for the groups 1F-3S, 2S-2F and 4F-0S respectively, while the percentages of the fish which reached the stage of vitellogenesis were 20%, 75% and 50% for the same groups. The concentration of glucose and lactate in plasma was not affected by starvation or re-feeding. On the contrary, triglycerides, phospholipids and total lipids of group 1F-3S decreased significantly, whereas cholesterol did not differ compared to the control group. In the 2S-2F group, total lipids and cholesterol were also significantly decreased while triglycerides and phospholipids were not altered. Proximate composition analysis in the liver showed that long term starvation (1F-3S) led to a significant reduction of crude lipid and ash, compared to the 4F-0S and 2S-2F groups. In contrast, crude protein concentration in the liver was significantly increased in 1F-3S group compared to 4F-0S and 2S-2F groups. In white muscle a significant reduction of crude lipids was detected in the 1F-3S and 2S-2F groups, while no significant changes were observed in crude protein, ash and moisture concentrations. The enzymatic activities of lactate dehydrogenase (L-LDH), citrate synthase (CS) and 3hydroxyacyl CoA dehydrogenase (HOAD) were significantly increased in the liver of 1F-3S fish, whereas in red muscle both HOAD and CS were significantly decreased in both 1F-3S and 2S-2F groups. Overall our results indicate that a 2 month starvation and 2 month re-feeding period during vitellogenesis reduces GSI and maturity stage in male sea bass and affect the levels of biochemical blood indices and the activities of certain enzymes of the intermediary metabolism.

The extant global Ephemeroptera fauna is represented by over 3,000 described species in 42 families and more than 400 genera. The highest generic diversity occurs in the Neotropics, with a correspondingly high species diversity, while the Palaearctic has the lowest generic diversity, but a high species diversity. Such distribution patterns may relate to how long evolutionary processes have been carrying on in isolation in a bioregion. Over an extended period, there may be extinction of species, but evolution of more genera. Dramatic extinction events such as the K-T mass extinction have affected current mayfly diversity and distribution. Climatic history plays an important role in the rate of speciation in an area, with regions which have been climatically stable over long periods having fewer species per genus, when compared to regions subjected to climatic stresses, such as glaciation. A total of 13 families are endemic to specific bioregions, with eight among them being monospecific. Most of these have restricted distributions which may be the result of them being the relict of a previously more diverse, but presently almost completely extinct family, or may be the consequence of vicariance events, resulting from evolution due to long-term isolation.

We examined the time course of metabolic adaptations to 15 days of a high-fat diet (HFD). Sixteen endurance-trained cyclists were assigned randomly to a control (CON) group, who consumed their habitual diet (30% ± 8% mJ fat), or a HFD group, who consumed a high-fat isocaloric diet (69% ± 1% mJ fat). At 5-day intervals, the subjects underwent an oral glucose tolerance test (OGTT); on the next day, they performed a 2.5-hour constant-load ride at 70% peak oxygen consumption (VO2peak), followed by a simulated 40-km cycling time-trial while ingesting a 10% 14C-glucose + 3.44% medium-chain triglyceride (MCT) emulsion at a rate of 600 mL/h. In the OGTT, plasma glucose concentrations at 30 minutes increased significantly after 5 days of the HFD and remained elevated at days 10 and 15 versus the levels measured prior to the HFD (P < .05). The activity of carnitine acyltransferase (CAT) in biopsies of the vastus lateralis muscle also increased from 0.45 to 0.54 μmol/g/min over days 0 to 10 of the HFD (P < .01) without any change in citrate synthase (CS) or 3-hydroxyacyl-coenzyme A dehydrogenase (3-HAD) activities. Changes in glucose tolerance and CAT activity were associated with a shift from carbohydrate (CHO) to fat oxidation during exercise (P < .001), which occurred within 5 to 10 days of the HFD. During the constant-load ride, the calculated oxidation of muscle glycogen was reduced from 1.5 to 1.0 g/min (P < .001) after 15 days of the HFD. Ingestion of a HFD for as little as 5 to 10 days significantly altered substrate utilization during submaximal exercise but did not attenuate the 40-km time-trial performance.

Aging affects the metabolic capacity of skeletal muscle, in particular the glycolytic and respiratory capacities. The purpose of this study was to quantify biochemical alterations due to aging in muscular metabolic capacity in human skeletal muscles in sedentary subjects. The activities of various marker enzymes and metabolites related to glycolysis, Krebs' cycle and the electron transfer chain and high energy phosphate compounds were measured in muscle biopsies from the rectus abdominis, vastus lateralis, and gluteus maximus muscles of 76 sedentary subjects (32 males and 44 females) between 15 and 91 yr. No significant differences between males and females were found, but changes related to age were: a decrease in hexokinase and lactate dehydrogenase activities in the rectus abdominis; a decrease in citrate synthase activity and citrate in the vastus lateralis; an increase in pyruvate kinase activity and a decrease in ATP and creatine phosphate concentrations in the gluteus maximus. These data suggest that distinct muscles may respond differently to aging regardless of sex in sedentary subjects.

The nereidid Nereis (Neanthes) virens undergoes drastic behavioural, morphological and physiological changes during its sexual maturation (epitoky). This metamorphosis prepares benthic worms for a brief pelagic existence devoted to mating although in N. virens only mature males leave their burrows to swarm. After spawning, individuals of both sexes die. Specific adjustments of energy metabolism pathway allowing higher muscular activity and swimming capacity remain to be eluded. This study compared atokous worms (immature) and epitokous (mature) swimming males and benthic females of N. virens to detect metabolic changes that could occur during epitoky. Epitokous males showed significantly higher electron transport system, citrate synthase and aspartate aminotransferase activities (p b 0.01) and significantly lower lactate dehydrogenase activity (p b 0.01) compared to atokous worms and epitokous females. There was no difference in antioxidant enzyme capacities between epitokes and atokes. Lipase and trypsin activities were significantly lower (p b 0.01) in epitokous males. The enzymatic changes observed are likely related to the metabolic adjustments required to support higher swimming abilities. Maintenance of antioxidant capacities could be related to protection of germinal tissues more than long term survival, since N. virens die after spawning.

During May 1998, we conducted a case-control study of 357 participants from 60 households during an outbreak of acute bartonellosis in the Urubamba Valley, Peru, a region not previously considered endemic for this disease. Blood and insect specimens were collected and environmental assessments were done. Case-patients (n ϭ 22) were defined by fever, anemia, and intra-erythrocytic coccobacilli seen in thin smears. Most case-patients were children (median age ϭ 6.5 years). Case-patients more frequently reported sand fly bites than individuals of neighboring households (odds ratio [OR] ϭ 5.8, 95% confidence interval [CI] ϭ 1.2-39.2), or members from randomly selected households Ն 5 km away (OR ϭ 8.5, 95% CI ϭ 1.7-57.9). Bartonella bacilliformis isolated from blood was confirmed by nucleotide sequencing (citrate synthase [gltA], 338 basepairs). Using bacterial isolation (n ϭ 141) as the standard, sensitivity, specificity, and positive predictive value of thin smears were 36%, 96%, and 44%, respectively. Patients with clinical syndromes compatible with bartonellosis should be treated with appropriate antibiotics regardless of thin-smear results.

Proanthocyanidin consumption might reduce the risk of developing several pathologies, such as inflammation, oxidative stress and cardiovascular diseases. The beneficial effects of proanthocyanidins are attributed to their antioxidant properties, although they also can modulate gene expression at the transcriptional level. Little is known about the effect of proanthocyanidins on mitochondrial function and energy metabolism. In this context, the objective of this study was to determine the effect of an acute administration of grape seed proanthocyanidin extract (GSPE) on mitochondrial function and energy metabolism. To examine this effect, male Wistar rats fasted for fourteen hours, and then they were orally administered lard oil containing GSPE or were administered lard oil only. Liver, muscle and brown adipose tissue (BAT) were used to study enzymatic activity and gene expression of proteins related to energetic metabolism. Moreover, the gastrocnemius muscle and BAT mitochondria wer...

Feed management is an important factor for successful aquaculture, especially when it affects gonad maturation. In this context, the present study evaluates the effects of long term starvation (1F-3S: one-month feedingthree-month starvation) and starvation/re-feeding (2S-2F: two-month starvationtwo-month refeeding) on gonad maturation, hematological/biochemical indices and proximate composition of liver and muscle of vitelogenic sea bass. In males, all the fish in the control group (4F-0S: four-month feedingzeromonth starvation) reached the maturity stage S2 (Mature), while only 33% and 75% reached that stage in the 1F-3S and 2S-2F groups, respectively. In females, the percentages of immature gonads were 80%, 25% and 50% for the groups 1F-3S, 2S-2F and 4F-0S respectively, while the percentages of the fish which reached the stage of vitellogenesis were 20%, 75% and 50% for the same groups. The concentration of glucose and lactate in plasma was not affected by starvation or re-feeding. On the contrary, triglycerides, phospholipids and total lipids of group 1F-3S decreased significantly, whereas cholesterol did not differ compared to the control group. In the 2S-2F group, total lipids and cholesterol were also significantly decreased while triglycerides and phospholipids were not altered. Proximate composition analysis in the liver showed that long term starvation (1F-3S) led to a significant reduction of crude lipid and ash, compared to the 4F-0S and 2S-2F groups. In contrast, crude protein concentration in the liver was significantly increased in 1F-3S group compared to 4F-0S and 2S-2F groups. In white muscle a significant reduction of crude lipids was detected in the 1F-3S and 2S-2F groups, while no significant changes were observed in crude protein, ash and moisture concentrations. The enzymatic activities of lactate dehydrogenase (L-LDH), citrate synthase (CS) and 3hydroxyacyl CoA dehydrogenase (HOAD) were significantly increased in the liver of 1F-3S fish, whereas in red muscle both HOAD and CS were significantly decreased in both 1F-3S and 2S-2F groups. Overall our results indicate that a 2 month starvation and 2 month re-feeding period during vitellogenesis reduces GSI and maturity stage in male sea bass and affect the levels of biochemical blood indices and the activities of certain enzymes of the intermediary metabolism.

Heat shock protein (HSP) expression is an adaptive mechanism against the disruption of cell homeostasis during exercise. Several antioxidant supplementation strategies have been used to enhance tissue protection. In this study, we examined the effects of a redox modulator, alpha-lipoic acid (LA) on HSP responses in six standardbred trotters following intense aerobic exercise. DL-LA supplementation (25 mg kg(-1) d(-1)) for five weeks increased the resting levels of HSP90 (1.02+/-0.155 in control and 1.26+/-0.090 after supplementation in arbitrary units) and the recovery levels of inducible HSP70 (0.89+/-0.056 in control and 1.05+/-0.089 after supplementation in arbitrary units) in skeletal muscle. Furthermore, LA increased skeletal muscle citrate synthase activity at rest and lowered the blood lactate concentration during exercise without any changes in the heart rate. LA had no effect on concentrations of HSP60, HSP25 or GRP75 in skeletal muscle. LA decreased the exercise-induced in...

The mitochondrial theory of aging was tested with optimised preparation techniques. Mitochondria were isolated from , 90 mg quadriceps muscle from healthy humans at age 70þ and 20þ . The content of mitochondrial protein was , 10 mg g 21 muscle and the yields were ,40%. The mitochondrial integrity was high as judged from the respiratory control and P/O ratios. No general membrane alterations or changes in the cytochrome contents were observed. BSA decreased the non-phosphorylating rates of respiration equally in both age groups. Thirteen different enzyme activities were assayed and normalised to protein content and citrate synthase activity. Most of the critical levels for detection of declines were , 10%. In the 70þ group, the activity for fatty acid oxidation was decreased by ,20%. Two inherently low activities associated with oxidation of sarcoplasmic NADH were also decreased, probably related to the age change of fibre types. The remaining activities measured, e.g. those of pyruvate dehydrogenase, tricarboxylic acid cycle, respiratory chain, and ATP synthesis, were not observed to be lowered. Thus, the central bioenergetic systems appeared unaltered with age. The obvious discord with reported age declines of human skeletal muscle mitochondrial function is discussed. It is concluded that the present results are incompatible with the mitochondrial theory of aging. q

Cadmium distribution was studied in different subcellular fractions of gill and hepatopancreas tissues of eastern oysters Crassostrea virginica. Oysters were exposed for up to 21 days to low sublethal Cd concentrations (25 g L −1 ). Gill and hepatopancreas tissues were sampled and divided into organelle fractions and cytosol by differential centrifugation. Organelle content of different fractions was verified by activities of marker enzymes, citrate synthase and acid phosphatase for mitochondria and lysosomes, respectively. In both tissue types, there was a significant accumulation of cadmium in cytosol reaching 230-350 ng mg −1 protein. Among organelles, mitochondria were the main target for Cd bioaccumulation in gills (250-300 ng mg −1 protein), whereas in hepatopancreas tissues, the highest cadmium accumulation occurred in lysosomes (90-94 ng mg −1 protein). Although 75-83% of total cadmium burden was associated with the cytosol reflecting high volume fraction of this compartment, Cd concentrations in organelle fractions reached levels that could cause dysfunction of mitochondria and lysosomes. Organ-and organelle-specific patterns of cadmium bioaccumulation support our previous in vivo studies, which showed adverse effects of cadmium exposures on mitochondrial oxidation in gills and on the lysosomal system of hepatopancreas. This may have important implications for the development of biomarkers of effect for heavy metals and for understanding the mechanisms of toxic effects of metals.

The phylogeny of a previously unidentified, obligate laticifer-inhabiting bacterium associated with the papaya bunchy top disease was investigated. Portions of genes corresponding to those for 16S rRNA, the flavoprotein subunit of succinate dehydrogenase (SdhA), citrate synthase (GltA), and the 17-kDa rickettsial common antigen were isolated and sequenced from the non-cultivable bacterium from diseased plants. Comparative sequence analyses consistently indicated that the bacterium is a member of the ␣-subdivision of the Proteobacteria and of the genus Rickettsia. The rickettsia was detected by polymerase chain reaction in diseased, but not healthy, papaya tissues and in the leafhopper vector, Empoasca papayae, providing further evidence of the possible etiological role of the bacterium in the disease. Although Rickettsia have been found naturally in arthropods and can be pathogenic to humans and other vertebrates, this is the first evidence of its kind implicating a Rickettsia as a plant pathogen.

Exercise increases mRNA for genes involved in mitochondrial biogenesis and oxidative enzyme capacity. However, little is known about how these genes respond to consecutive bouts of prolonged exercise. We examined the eVects of 3 h of intensive cycling performed on three consecutive days on the mRNA associated with mitochondrial biogenesis in trained human subjects. Forty trained cyclists were tested for VO 2max (54.7 § 1.1 ml kg ¡1 min ¡1 ). The subjects cycled at 57% watts max for 3 h using their own bicycles on CompuTrainer™ Pro Model trainers (Racer-Mate, Seattle, WA) on three consecutive days. Muscle biopsies were obtained from the vastus lateralis pre-and post-exercise on days one and three. Muscle samples were analyzed for mRNA content of peroxisome proliferator receptor gamma coactivator-1 alpha (PGC-1 ), sirtuin 1 (Sirt-1), cytochrome c, and citrate synthase. Data were analyzed using a 2 (time) £ 2 (day) repeated measures ANOVA. Of the mRNA analyzed, the following increased from pre to post 3 h rides: cytochrome c (P = 0.006), citrate synthase (P = 0.03), PGC-1 (P < 0.001), and Sirt-1 (P = 0.005). The following mRNA showed signiWcant eVects from days one to three: cytochrome c (P < 0.001) and citrate synthase (P = 0.01). These data show that exhaustive cycling performed on three consecutive days resulted in both acute and chronic stimuli for mRNA associated with mitochondrial biogenesis in already trained subjects. This is the Wrst study to illustrate an increase in sirtuin-1 mRNA with acute and chronic exercise. These data contribute to the understanding of mRNA expression during both acute and successive bouts of prolonged exercise.

The winter syndrome in the gilthead sea bream Sparus aurata indicates that the species is exposed to critically low temperatures in Mediterranean aquaculture in winter. The present study of metabolic patterns and molecular stress responses during cold exposure was carried out to investigate this ''disease'', in light of the recent concept of oxygen and capacity limited thermal tolerance. The metabolic profile of fuel oxidation was examined by determining the activities of the enzymes hexokinase (HK), aldolase (Ald), pyruvate kinase (PK), L-lactate dehydrogenase (L-LDH), citrate synthase (CS), malate dehydrogenase (MDH) and 3-hydroxyacyl CoA dehydrogenase (HOAD) in heart, red and white muscle after exposure to temperatures of 10, 14 and 18°C. Especially, the increase in LDH activity combined with the accumulation of L-lactate in tissues indicates that temperatures below 14°C are critical for Sparus aurata and stimulate the anaerobic component of metabolism. Increase in the activity of HOAD suggests that oxidation of free fatty acids might contribute to ATP turnover at low temperatures. The expression of Hsp70 and Hsp90 in all tissues examined revealed a cellular stress response during cooling below 18°C. In the light of winter temperatures in S. aurata cultures around 10°C, our data suggest that the fish are exposed to stressful conditions at the low end of their thermal tolerance window. These conditions likely impair the aerobic capacity of the fish, compromise the rates of growth and reproduction and may contribute to elicit pathological conditions.

Due to the higher energy requirements of birds during winter, it is predicted that the activities of metabolic enzymes (e.g., citrate synthase, CS and cytochrome C oxidase, COX) should increase in tandem with increases in rates of energy expenditure (e.g., basal metabolic rate, BMR). However, there is mixed support for the hypothesis of enzymatic acclimatization. Furthermore, there is little information about the effect of ambient temperature on energetics and tissue enzyme activity levels in passerines inhabiting seasonal Mediterranean environments. In this study we evaluated the interplay between BMR and enzyme activities of freshly caught individuals of the passerine Zonotrichia capensis in winter and summer in a Mediterranean environment from central Chile, and also in warm (30°C) and cold (15°C) lab-acclimated birds. The results revealed a lack of seasonal variation in BMR, thermal conductance and in the activity of CS and COX. However, we found higher BMR and lower thermal conductance in cold-acclimated than in warm- cclimated birds. Also, total CS activity was higher in the flight muscles of cold-acclimated than in warm-acclimated birds. We found also a significant correlation between BMR and total CS activity in pectoral muscle. Although some authors have suggested that BMR mainly depends on the metabolic intensity and mass of internal organs, our results revealed that skeletal muscles such as the flight muscles may also  ffect BMR. Finally, differences in the acclimation and acclimatization responses in Rufous-collared sparrows suggest that large-scale oscillations in the physical environment might maintain the capacity for  flexibility in thermogenic traits through generations.

This study examined whether sucrose-rich diet (SRD)-induced hyperglycaemia, dyslipidemia and oxidative stress may be inhibited by N-acetylcysteine (C5H9–NO3S), an organosulfur from Allium plants. Male Wistar 40 rats were divided into four groups (n = 10): (C) given standard chow and water; (N) receiving standard chow and 2 mg/l N-acetylcysteine in its drinking water; (SRD) given standard chow and 30% sucrose in its drinking water; and (SRD-N) receiving standard chow, 30% sucrose and N-acetylcysteine in its drinking water. After 30 days of treatment, SRD rats had obesity with increased abdominal circumference, hyperglycaemia, dyslipidemia and hepatic triacylglycerol accumulation. These adverse effects were associated with oxidative stress and depressed lipid degradation in hepatic tissue. The SRD adverse effects were not observed in SDR-N rats. N-Acetylcysteine reduced the oxidative stress, enhancing glutathione-peroxidase activity, and normalizing lipid hydroperoxyde, reduced glutathione and superoxide dismutase in hepatic tissue of SRD-N rats. The β-hydroxyacyl coenzyme-A dehydrogenase and citrate-synthase activities were increased in SRD-N rats, indicating enhanced lipid degradation in hepatic tissue as compared to SRD. SRD-N rats had reduced serum oxidative stress and diminished glucose, triacylglycerol, very-low-density lipoprotein (VLDL), oxidized low-density lipoprotein (ox-LDL) and cholesterol/high-density lipoprotein (HDL) ratio in relation to SRD. In conclusion, NAC offers promising therapeutic values in prevention of dyslipidemic profile and alleviation of hyperglycaemia in high-sucrose intake condition by improving antioxidant defences. N-Acetylcysteine had also effects preventing metabolic shifting in hepatic tissue, thus enhancing fat degradation and reducing body weight gain in conditions of excess sucrose intake. The application of this agent in food system via exogenous addition may be feasible and beneficial for antioxidant protection.

Honeybees, Apis mellifera, who show temporal polyethism, begin their adult life performing tasks inside the hive (hive bees) and then switch to foraging when they are about 2-3 weeks old (foragers). Usually hive tasks require little or no flying, whereas foraging involves flying for several hours a day and carrying heavy loads of nectar and pollen. Flight muscles are particularly plastic organs that can respond to use and disuse, and accordingly it would be expected that adjustments in flight muscle metabolism occur throughout a bee's life. We thus investigated changes in lifetime flight metabolic rate and flight muscle biochemistry of differently aged hive bees and of foragers with varying foraging experience. Rapid increases in flight metabolic rates early in life coincided with a switch in troponin T isoforms and increases in flight muscle maximal activities (V max ) of the enzymes citrate synthase, cytochrome c oxidase, hexokinase, phosphofructokinase, and pyruvate kinase. However, further increases in flight metabolic rate in experienced foragers occurred without additional changes in the in vitro V max of these flight muscle metabolic enzymes. Estimates of in vivo flux (v) compared to maximum flux of each enzyme in vitro (fractional velocity, v/V max ) suggest that most enzymes operate at a higher fraction of V max in mature foragers compared to young hive bees. Our results indicate that honeybees develop most of their flight muscle metabolic machinery early in life. Any further increases in flight metabolism with age or foraging experience are most likely achieved by operating metabolic enzymes closer to their maximal flux capacity.

1. Physiological factors relating to activity metabolism were measured in two species of African lacertid lizards that differ greatly in natural foraging patterns: Eremias lineoocellnta, a sitand-wait predator, and E. lugubris, a widely foraging animal.

Reduced oxidative capacity of skeletal muscle has been proposed to lead to accumulation of intramyocellular triglyceride (IMTG) and insulin resistance. We have measured mitochondrial respiration before and after a 10% low-calorie-induced weight loss in young obese women to examine the relationship between mitochondrial function, IMTG, and insulin resistance. Nine obese women (age, 32.3 years [SD, 3.0]; body mass index, 33.4 kg/m 2 [SD, 2.6]) completed a 53-day (SE, 3.8) very low calorie diet (VLCD) of 500 to 600 kcal/d without altering physical activity. The target of the intervention was a 10% weight loss; and measurements of mitochondrial respiration, IMTG, respiratory exchange ratio, citrate synthase activity, mitochondrial DNA copy number, plasma insulin, 2-hour oral glucose tolerance test, and free fatty acids were performed before and after weight loss. Mitochondrial respiration was measured in permeabilized muscle fibers using high-resolution respirometry. Average weight loss was 11.5% (P b .05), but the levels of IMTG remained unchanged. Fasting plasma glucose, plasma insulin homeostasis model assessment of insulin resistance, and insulin sensitivity index (composite) obtained during 2-hour oral glucose tolerance test improved significantly. Mitochondrial respiration per milligram tissue decreased by approximately 25% (P b .05), but citrate synthase activity and mitochondrial DNA copy number remained unchanged. Respiratory exchange ratio decreased from 0.87 (SE, 0.01) to 0.79 (SE, 0.02) (P b .05) as a sign of increased whole-body fat oxidation. Markers of insulin sensitivity improved after the very low calorie diet; but mitochondrial function decreased, and IMTG remained unchanged. Our results do not support a direct relationship between mitochondrial function and insulin resistance in young obese women and do not support a direct relationship between IMTG and insulin sensitivity in young obese women during weight loss.

Canine DNA samples from South Africa were found to contain 16S rRNA gene nucleotide and citrate synthase gene nucleotide and deduced amino acid sequences that were most similar to Anaplasma phagocytophilum: 98%, 66%, and 69% similarity, respectively. This suggests that a new Anaplasma species closely related to A. phagocytophilum occurs in Africa.

Metabolic cold adaptation (MCA), the hypothesis that species from cold climates have relatively higher metabolic rates than those from warm climates, was first proposed nearly 100 years ago and remains one of the most controversial hypotheses in physiological ecology. In the present study, we test the MCA hypothesis in fishes at the level of whole animal, mitochondria and enzyme. In support of the MCA hypothesis, we find that when normalized to a common temperature, species with ranges that extend to high latitude (cooler climates) have high aerobic enzyme (citrate synthase) activity, high rates of mitochondrial respiration and high standard metabolic rates. Metabolic compensation for the global temperature gradient is not complete however, so when measured at their habitat temperature species from high latitude have lower absolute rates of metabolism than species from low latitudes. Evolutionary adaptation and thermal plasticity are therefore insufficient to completely overcome the acute thermodynamic effects of temperature, at least in fishes.

The effect of episodic acidification on Atlantic salmon (Salmo salar) smolt physiology and survival in fresh water (FW) and seawater (SW) was investigated. Smolts were held in either ambient (control, pH 6.0-6.6), acidified (chronic, pH 4.4-6.1), or episodically acidified (episodic, pH reduction from control levels to pH -5.2 for 48 h once weekly) river water for 31 days and then transferred to 34‰ SW. Smolts fed little while in acidified conditions and chronic smolts did not grow in length or weight. In FW, chronic smolts experienced increases in hematocrit and plasma potassium and reductions in plasma sodium and chloride. Upon transfer to SW, chronic and episodic smolts experienced reductions in hematocrit, increases in plasma sodium, chloride, and potassium levels, and suffered mortalities. Gill Na + ,K + -ATPase and citrate synthase activities were reduced by exposure to acid. For most parameters, the effect of episodic acid exposure was less than that of chronic acidification. Exposure to acidic conditions, even when short in duration and followed by a 30-h recovery period in suitable water (pH 6.5), led to a 35% mortality of smolts upon transfer to SW. This study highlights the importance of measuring and assessing sublethal stresses in FW and their ultimate effects in marine ecosystems.

The purpose of this study was to assess the physiological adaptations in physically fit individuals to a period of intensified training. Ten trained males cycled outdoors *170 km day -1 on 19 out of 21 days. Expired gas was collected on days 1 and 21 during maximal graded exercise and used for the determination of gross efficiency and whole body substrate use. Muscle biopsies were obtained before and after exercise on days 2 and 22 for the determination of mtDNA/gDNA ratio, gene expression, metabolic enzyme activity and glycogen use. Muscle glycogen before and after exercise, fat oxidation, and gross efficiency increased, carbohydrate oxidation decreased (p \ 0.05), and VO 2max did not change over the 21 days of training. Citrate synthase (CS), b-hydroxyacyl CoA dehydrogenase (b-HAD) and cytochrome c oxidase (COX) enzyme activity did not change with training. CS and b-HAD mRNA did not change with acute exercise or training. COX (subunit IV) mRNA increased with acute exercise (p \ 0.05) but did not change over the 21 days. PGC-1a mRNA increased with acute exercise, but did not increase to the same degree on day 22 as it did on day 2 (p \ 0.05). UCP3 mRNA decreased with training (p \ 0.05). Acute exercise caused an increase in mitofu-sin2 (MFN2) mRNA (p \ 0.05) and a trend for an increase in mtDNA/gDNA ratio (p = 0.057). However, training did not affect MFN2 mRNA or mtDNA/gDNA ratio. In response to 3,211 km of cycling, changes in substrate use and gross efficiency appear to be more profound than mitochondrial adaptations in trained individuals.

To investigate energy metabolism in migraine, we determined platelet mitochondrial enzyme activities in 40 patients with migraine with aura and in 40 patients with migraine without aura during attack-free intervals and in 24 healthy control subjects. NADH-dehydrogenase, citrate synthase and cytochrome-c-oxidase activities in both patient groups were significantly lower than in controls (p < 0.01), while NADH-cytochrome-c-reductase activity was reduced only in migraine with aura (p <0.01). No alteration in succinate-dehydrogenase was observed. Monoamine-oxidase activity differed between sexes (p < 0.05) but within each sex group no difference was observed between patients and controls. We hypothesize that the defect in mitochondrial enzymes observed indicates a systemic impairment of mitochondrial function in migraine patients. • Energy production, migraine, mitochondria, platelets