Historic occurrence of parthenogenetic Artemia in Great Salt Lake, USA, as demonstrated by molecular analysis of field samples
Journal of Great Lakes Research, 2013
ABSTRACT Great Salt Lake (GSL), USA is the main source of the commercially important Artemia fran... more ABSTRACT Great Salt Lake (GSL), USA is the main source of the commercially important Artemia franciscanaKellogg (1906) cysts used in larviculture. Our objective was to document the presence of parthenogenetic Artemia in GSL analysing a series of non-commercial samples harvested over the period 1997–2005. Laboratory cultures suggested that sex ratios were skewed in some years. Species-specific restriction fragment length polymorphisms in the exon-7 of the Na/K-ATPase α-1 subunit nuclear gene and of a fragment of exon-2 of the heat shock protein HSP26 gene were used to identify samples of individual adults and pooled cysts. Additionally, denaturing gradient gel electrophoresis using the Na/K-ATPase marker and individual adults was used because of its greater power for detecting different alleles. Finally, the exon of the Na/K-ATPase α-1 subunit was sequenced in selected individuals to validate the results. All results indicated that there were parthenogenetic Artemia in the samples from the period 2000 to 2002. Our data do not provide evidence on the autochthonous or allochthonous nature of this population, although an anthropogenic origin seems most likely. The transitory character of the incidence of parthenogenetic Artemia can be linked to unusual environmental conditions in the lake around the turn of the century. The subsequent disappearance of the parthenogenetic population would then be due to the competition with the more productive A. franciscana population as conditions returned back to normal. A systematic genetic study of the GSL Artemia population is recommended as it may provide valuable complementary information about population changes undetected in traditional monitoring programmes.
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Papers by Peter Bossier
from environmental experiences are heritable remains
under debate. However, the recent report of
nonmendelian transgenerational epigenetic inheritance, i.e.,
the inheritance of traits not determined by the DNA
sequence, might make such a phenomenon plausible.
In our study, by carrying out common garden experiments,
we could provide clear evidences that, on exposure
to nonlethal heat shocks, a parental population of
parthenogenetic (all female) Artemia (originating from
one single female) experiences an increase in levels of
Hsp70 production, tolerance toward lethal heat stress,
and resistance against pathogenic Vibrio campbellii. Interestingly, these acquired phenotypic traits were transmitted
to three successive generations, none of which
were exposed to the parental stressor. This transgenerational
inheritance of the acquired traits was associated
with altered levels of global DNA methylation and
acetylated histones H3 and H4 in the heat-shocked
group compared to the control group, where both the
parental and successive generations were reared at
standard temperature. These results indicated that epigenetic
mechanisms, such as global DNA methylation
and histones H3 and H4 acetylation, have particular
dynamics that are crucial in the heritability of the
acquired adaptive phenotypic traits across generations.