Unusual response of <i>Artemia franciscana</i> embryos to prolonged anoxia

Clegg, James S.

doi:10.1002/jez.1402700312

Cited by 24 publications

(11 citation statements)

References 12 publications

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“…Although impressive, these rates are considerably lower than those reported by Clegg for San Francisco Bay cysts, which maintained almost full hatchability for two years (Clegg, 1997). However, the cysts were not dried before hatching, which may improve the hatch by helping to break the anoxia-induced diapause, so the unhatched cysts may not be dead but still locked in diapause (Abatzopolous et al, 1994;Clegg, 1994). To find evidence that accumulated DNA damage is repaired before hatching, the number of AP sites was measured in samples of cysts and in larvae hatched from cysts stored under N 2 for 30 weeks at 28°C followed by incubation in oxygenated seawater for up to 72 h. A marked reduction in AP sites per 10 4 bp from 21.1±4.0 to 9.8±2.0 was observed in cysts 12 h after reoxygenation, with a further reduction to 6.2±2.1 by 24 h, when 4% of the cysts had hatched (Fig.…”

Section: Resultsmentioning

confidence: 99%

Ametabolic embryos of Artemia franciscana accumulate DNA damage during prolonged anoxia

McLennan

2009

Journal of Experimental Biology

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SUMMARYEncysted embryos of the brine shrimp Artemia franciscana are able to survive prolonged periods of anoxia even when fully hydrated. During this time there is no metabolism, raising the question of how embryos tolerate spontaneous, hydrolytic DNA damage such as depurination. When incubated at 28°C and 40°C for several weeks, hydrated anoxic embryos were found to accumulate abasic sites in their DNA with k=5.8ϫ10 -11 s -1 and 2.8ϫ10 -10 s -1 , respectively. In both cases this is about 3-fold slower than expected from published observations on purified DNA. However, purified calf thymus DNA incubated under similar anoxic conditions at pH 6.3, the intracellular pH of anoxic cysts, also depurinated more slowly than predicted (about 1.7-fold), suggesting that cysts may in fact accumulate abasic sites only slightly more slowly than purified DNA. Upon reoxygenation of cysts stored under N 2 for 30 weeks at 28°C, the number of abasic sites per 10 4 bp DNA fell from 21.1±4.0 to 9.8±2.0 by 12 h and to 6.2±2.1 by 24 h. Larvae hatched after 48 h and 72 h had only 0.59±0.17 and 0.48±0.07 abasic sites per 10 4 bp, respectively, suggesting that repair of these lesions had largely taken place before hatching commenced. Thus, unlike bacterial spores, Artemia cysts appear to have no specific protective mechanism beyond what might be afforded by chromatin structure to limit spontaneous depurination, and rely on the repair of accumulated lesions during the period between reoxygenation and hatching.

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Section: Resultsmentioning

confidence: 99%

Ametabolic embryos of Artemia franciscana accumulate DNA damage during prolonged anoxia

McLennan

2009

Journal of Experimental Biology

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“…Upon exiting females, cysts enter diapause, a physiological state characterized by the cessation of growth and profound dormancy (Jackson and Clegg 1996;Clegg et al 2000;MacRae 2003MacRae , 2005MacRae , 2010. Cysts are exceptionally resistant to physiological stress even when hydrated, and as one extraordinary example of this capability, they survive years of anoxia (Clegg 1994(Clegg , 1997Clegg et al 1999Clegg et al , 2000van Breukelen et al 2000;Viner and Clegg 2001). Diapause continues, even under conditions favorable for growth, until terminated by environmental stimuli such as desiccation, light, and/or cold (Drinkwater and Crowe 1987;Van Der Linden et al 1988;Drinkwater and Clegg 1991;Clegg et al 2000;Robbins et al 2010).…”

Section: Introductionmentioning

confidence: 96%

The structural stability and chaperone activity of artemin, a ferritin homologue from diapause-destined Artemia embryos, depend on different cysteine residues

Bojikova-Fournier

King

et al. 2011

Cell Stress and Chaperones

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Diapause-destined embryos of the crustacean, Artemia franciscana, accumulate large amounts of an oligomeric, heat-stable, molecular chaperone termed artemin, a cysteine-enriched ferritin homologue. In this study, cysteines 22, 61, 166, and 172 of artemin were substituted with alanines, respectively yielding ArtC22A, ArtC61A, ArtC166A, and ArtC172A. Wild-type and modified artemins were synthesized in transformed bacteria and purified. As measured by heat-induced denaturation of citrate synthase in vitro, each substitution reduced chaperone activity, with ArtC172A the least active. Protein modeling indicated that C172 is close to a region of surface hydrophobicity, also present in ferritin, suggesting that this site contributes to chaperone activity. Only slight differences in oligomer molecular mass were apparent between artemin variants, but ArtC22A and ArtC61A displayed significantly reduced thermostability, perhaps due to the disruption of an inter-subunit disulphide bridge. In contrast, ArtC172A was thermostable, reflecting the location of C172 on the oligomer surface and that it contributes minimally to artemin stabilization. To our knowledge, this is the initial study of structure/function relationships within a ferritin homologue of importance in diapause and the first to indicate that a defined region of hydrophobicity contributes to artemin and ferritin chaperoning.

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“…The great stability of DNA in encysted embryos (Hagelberg, et al, 1989;Eglinton & Curry, 1991;DeSalle et al, 1992) suggests that the present DNA study can be extended to cysts from older levels. In view of the stability of encysted embryos to environmental insults (Clegg & Conte, 1980;Sorgeloos et al, 1987;Browne et al, 1991), such as prolonged anoxia (Clegg, 1994) and severe desiccation (Clegg, 1974;Clegg et al, 1978), higher levels can be expected to contain Artemia cysts that are still viable. …”

Section: Discussionmentioning

confidence: 97%

Sediment cores from Lake Urmia (Iran) suggest the inhabitation by parthenogenetic Artemia around 5,000 years ago

et al. 2011

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In Lake Urmia area, northwestern Iran, parthenogenetic Artemia and the bisexual Artemia urmiana Günther 1890 are found to occupy different ecological niches determined by salinity. Given the fluctuations of the lake over geological times, we thus hypothesized that species identification of Artemia cysts, buried in the sediments, can provide information on lake conditions in the past. Therefore, encysted embryos of Artemia were recovered from lake sediments by augering at a site near the present shoreline. Cysts and associated plant remains from two studied levels yielded radiocarbon ages in the range 5,000-6,700 YBP. For determination of the type of Artemia, the constant synonym mutation in exon-7 of the Na/K ATPase gene was verified, and the diameter of the recovered cysts was compared with that of modern cysts from the Lake Urmia region. The results show that the cysts represent a parthenogenetic type of Artemia, whose cyst diameter is somewhat different from that of present-day local parthenogenetic Artemia. The present study firstly confirms the stability of DNA in ancient Artemia cysts for molecular analysis. Moreover, it suggests variation in Lake Urmia's conditions over time, and based on comparison with salinity preferences of contemporary Artemia populations, it more specifically suggests that Lake Urmia was a brackish lake dominated by a parthenogenetic Artemia population in the geological period sampled. It finally illustrates how, like in the study of freshwater propagule banks, paleogenetic analysis of Artemia DNA recovered from sediment cores can be used as a tool in the paleoecological study of generally highly fluctuating saline habitats.

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Unusual response of Artemia franciscana embryos to prolonged anoxia

Cited by 24 publications

References 12 publications

Ametabolic embryos of Artemia franciscana accumulate DNA damage during prolonged anoxia

Ametabolic embryos of Artemia franciscana accumulate DNA damage during prolonged anoxia

The structural stability and chaperone activity of artemin, a ferritin homologue from diapause-destined Artemia embryos, depend on different cysteine residues

Sediment cores from Lake Urmia (Iran) suggest the inhabitation by parthenogenetic Artemia around 5,000 years ago

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