Gilbert Van Stappen

Environmental heat stress induces epigenetic transgenerational inheritance of robustness in parthenogenetic Artemia model

The notion that phenotypic traits emerging 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.—Norouzitallab, P., Baruah, K., Vandegehuchte, M., Van Stappen, G., Catania, F., Vanden Bussche, J., Vanhaecke, L., Sorgeloos, P., Bossier, P. Environmental heat stress induces epigenetic transgenerational inheritance of robustness in parthenogenetic Artemia model. FASEB J. 28, 3552–3563 (2014). www.fasebj.org

Nutritional value of brine shrimp cysts as a factitious food for Orius laevigatus (Heteroptera: Anthocoridae)

Abstract Decapsulated cysts of the brine shrimp Artemia franciscana were assessed as a factitious food for rearing the anthocorid predator Orius laevigatus. Developmental and reproductive traits of O. laevigatus reared for a single generation on A. franciscana from three geographical locations or on gamma-irradiated eggs of the Mediterranean flour moth Ephestia kuehniella were compared. There was no effect of diet on nymphal survival but nymphal period on E. kuehniella eggs (12.2 days) was 0.7–1.6 days shorter than on the Artemia diets. The predator developed 0.5–1 day faster on cysts from San Francisco Bay (USA) than on cysts from Great Salt Lake (USA) or Macau (Brazil). Fecundity on brine shrimp cysts from different locations was similar to that on flour moth eggs (142–187 eggs/female). The biochemical composition of decapsulated cysts from San Francisco Bay was compared with that of E. kuehniella eggs. Depending on the type of analysis, Artemia cysts contained higher or similar amounts of protein as compared with E. kuehniella eggs, but amino acid patterns were generally similar. Flour moth eggs were almost three times richer in fatty acids than brine shrimp cysts, with some marked differences in fatty acid profiles. Because nutrient imbalances in a diet may be expressed only after several generations of rearing, the predator was cultured for three consecutive generations on A. franciscana cysts from San Francisco Bay. In the third generation on brine shrimp cysts, nymphs took 18% longer to develop, and adults were shorted-lived and about 60% less fecund than those maintained on E. kuehniella eggs. Brine shrimp cysts may be used as a supplement in the mass production of O. laevigatus but may not be a suitable food for long-term culturing of the predator.

International study on Artemia LXIII. Field study of the Artemia urmiana (Gunther, 1890) population in lake Urmiah, Iran.

Lake Urmiah is a large (total surface 4750–6100 km2 in recent times) thalassohaline hypersaline lake (150–180 g l−1 in the period 1994–1996), located in northwestern Iran. It is the habitat of the endemic Artemia urmiana. Over the period July 1994–January 1996 a sampling campaign was organized: 36 fixed sampling stations, distributed over the entire lakes area, were sampled weekly to determine water temperature, salinity and transparency. At each occasion a filter net was dragged over a distance of 400 m in the superficial water layer to assess the density and composition of the Artemia population. A more limited sampling campaign focused on the annual fluctuations in chlorophyll concentration and on the reproductive behaviour of the brine shrimp population. Several stages of brine shrimp survived during winter months (water temperature 3°C) at low densities. Compared to available data for the Great Salt Lake, USA, Lake Urmiah shows a low algal biomass and overall low Artemia density. The increasing grazing pressure of the developing brine shrimp population in spring seems to prevent the phytoplankton from reaching high blooming concentrations, and oviparity is the dominant reproductive mode throughout the reproductive season.

Diapause termination and development of encysted Artemia embryos: roles for nitric oxide and hydrogen peroxide

SUMMARY Encysted embryos (cysts) of the brine shrimp Artemia undergo diapause, a state of profound dormancy and enhanced stress tolerance. Upon exposure to the appropriate physical stimulus diapause terminates and embryos resume development. The regulation of diapause termination and post-diapause development is poorly understood at the molecular level, prompting this study on the capacity of hydrogen peroxide (H2O2) and nitric oxide (NO) to control these processes. Exposure to H2O2 and NO, the latter generated by the use of three NO generators, promoted cyst development, emergence and hatching, effects nullified by catalase and the NO scavenger 2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl 3-oxide (PTIO). The maximal effect of NO and H2O2 on cyst development was achieved by 4 h of exposure to either chemical. NO was effective at a lower concentration than H2O2 but more cysts developed in response to H2O2. Promotion of development varied with incubation conditions, indicating for the first time a population of Artemia cysts potentially arrested in post-diapause and whose development was activated by either H2O2 or NO. A second cyst sub-population, refractory to hatching after prolonged incubation, was considered to be in diapause, a condition broken by H2O2 but not NO. These observations provide clues to the molecular mechanisms of diapause termination and development in Artemia, while enhancing the organisms value in aquaculture by affording a greater understanding of its growth and physiology.

Salinity effects on survival, growth and morphometry of four Egyptian Artemia populations (International Study on Artemia. LXVII)

Four Artemia populations from northern Egypt, a bisexual one from Wadi El-Natrun Lake, two coastal parthenogenetic ones from Borg El-Arab and El-Max saltworks and an inland parthenogenetic form from Qarun Lake, were assayed for their survival, growth and morphometric responses measured in laboratory experiments at salinities of 35, 80, 120, 150 and 200 g l−1. The survival rate was determined using regression analysis and analysis of covariance. The bisexual population (Wadi El-Natrun: WN) exhibited its best survival at 80 g l−1. All parthenogenetic strains studied performed similarly (in terms of survival) at all salinities investigated. The population growth rates were based on Von Bertalannfy’s equation. In all salinities, WN population had the lowest growth rate (based on K values) among all Artemia populations tested. It is obvious that parthenogenetic populations tolerate a broader range of salinities compared to the bisexual one. The two coastal asexual strains had similar survival, growth and morphometric characters at all salinities. Discriminant function analysis based on specific morphometric parameters permitted the assignment of adult Artemia individuals to their population of origin with a score as high as 84.6%. Furthermore, specific morphometric parameters (such as the furcal length and the number of setae in each furcal branch) are suitable discriminating characters among the populations studied.

Characterisation of high-altitude Artemia populations from the Qinghai-Tibet Plateau, PR China

The brine shrimp Artemia was discovered in a number of saline lakes on the Qinghai-Tibet Plateau, widely diverging in chemical composition. Several lakes were athalassohaline, with relatively high amounts of trace elements. Common environmental factors are their high altitude (exceeding 4500 m) and the low average annual temperatures. A number of Artemia populations in this area were analysed to assess their preference for low temperatures and an athalassohaline medium. Furthermore, their characteristics were compared with Artemia tibetiana, the species recently described for one lake in this area. All samples contained a variable mixture of parthenogenetic and bisexual individuals. A cross-breeding test of the sample from Jingyu Lake showed cross-fertility both with A. tibetiana and A. sinica. All populations showed similarities to A. tibetiana: a large cyst diameter and naupliar length, high HUFA content and a high tolerance to low temperatures, as compared to the control A. franciscana samples. These can thus be considered as recurrent characteristics of the populations from the high-altitude low-temperature environment on the Qinghai-Tibet Plateau, although further research is needed to identify their exact species status.

Occurrence of allochthonous Artemia species in the Bohai Bay area, PR China, as confirmed by RFLP analysis and laboratory culture tests

Nauplii of the brine shrimp Artemia, predominantly Artemia franciscana Kellogg 1906, are the most common live food used in marine larviculture. Through aquaculture activities, this species may get dispersed into nearby saltworks, resulting in competition with, and sometimes extinction of the local Artemia populations. This work assesses, how the Artemia species composition in the Bohai Bay, China, an area with intensive aquaculture activities, has changed over recent years. Seventeen Artemia cyst samples, harvested in Bohai Bay saftworks from 1989 onwards, were used for HpaII analysis of a 1500 bp mitochondrial rDNA fragment in the individual cysts. The results were compared with a database consisting of 133 different populations belonging to all known Artemia species. The sex ratio of the populations was determined through laboratory culture tests. Four different genotypes represented by RFLP patterns typical for parthenogenetic populations, Artemia sinica Cai 1989 and A. franciscana, and one new pattern, very similar to the A. franciscana pattern, were observed. Nearly all samples consisted of varying mixtures of parthenogenetic and A. franciscana and/or A. sinica individuals. The results of the laboratory culture tests were less conclusive due to limited hatching and/or survival in several samples. The fact that the HpaII franciscana genotype shows up in II out of 17 samples, demonstrates that A. franciscana has become a competitor - and in view of its competitive advantage, probably a threat - for the autochthonous parthenogenetic Bohai Bay populations. The presence of A. sinica in a coastal environment is a new observation. This expansion of the exotic A. franciscana is discussed in the light of similar observations elsewhere in the world.

A first AFLP-based genetic linkage map for brine shrimp Artemia franciscana and its application in mapping the sex locus.

We report on the construction of sex-specific linkage maps, the identification of sex-linked markers and the genome size estimation for the brine shrimp Artemia franciscana. Overall, from the analysis of 433 AFLP markers segregating in a 112 full-sib family we identified 21 male and 22 female linkage groups (2n = 42), covering 1,041 and 1,313 cM respectively. Fifteen putatively homologous linkage groups, including the sex linkage groups, were identified between the female and male linkage map. Eight sex-linked AFLP marker alleles were inherited from the female parent, supporting the hypothesis of a WZ–ZZ sex-determining system. The haploid Artemia genome size was estimated to 0.93 Gb by flow cytometry. The produced Artemia linkage maps provide the basis for further fine mapping and exploring of the sex-determining region and are a possible marker resource for mapping genomic loci underlying phenotypic differences among Artemia species.

International study onArtemia. LI. New survey ofArtemia resources in the People's Republic of China

We have surveyed 7 inland salt lakes and 14 coastal saltworks in the Peoples Republic of China (P. R. China) which are natural habitats for the brine shrimpArtemia. We report here on the location of the lakes, the mode of reproduction of theArtemia and the opportunities for achieving self sufficiency in cyst production for use in the local aquaculture industry. Because of frequent misunderstandings regarding the identification of a specific habitat, a new identification system for each population is proposed, using a numerical code which identifies the province, the habitat and the date of collection. Information of newArtemia populations is included as well as data on their reproduction mode.

A Survey of Artemia Resources of Southwest Siberia (Russian Federation)

This article reports on a field survey conducted in salt lakes in southwest Siberia in the period 2000–2003. A total of 46 lakes were sampled; the highest sampling effort was made in the Kurgan region. Data were collected on general topography, salinity, ion composition, and temperature regime. Primary production was assessed by measuring water transparency and by determining phytoplankton species composition and density. The survey focused on the local Artemia populations: cyst and naupliar biometrics and adult morphometrics, and study of population dynamics. Based on these field data, an estimation was made of the available standing crop of cysts. Generally, the Artemia salt lakes in southwest Siberia are relatively small and shallow, and thus subject to major seasonal and annual fluctuations. In extreme conditions, they may temporarily turn into brackish water bodies or nearly entirely desiccate. Production (both primary and secondary) is generally low or moderate, except for relatively deep Bolshoye Yarovoye lake (Altay area). However, because of the high number of lakes, the area has commercial importance to cover a portion of the domestic need for Artemia cysts. Parthenogenetic populations dominate in the area; the species status of the few bisexual populations still needs to be established.