Pacific white shrimp (Litopenaeus vannamei) is the leading species farmed in the Western Hemisphere and an economically important aquaculture species in China. In this project, a genetic linkage map was constructed using amplified fragment length polymorphism (AFLP) and microsatellite markers. One hundred and eight select AFLP primer combinations and 30 polymorphic microsatellite markers produced 2071 markers that were polymorphic in either of the parents and segregated in the progeny. Of these segregating markers, 319 were mapped to 45 linkage groups of the female framework map, covering a total of 4134.4 cM; and 267 markers were assigned to 45 linkage groups of the male map, covering a total of 3220.9 cM. High recombination rates were found in both parental maps. A sex-linked microsatellite marker was mapped on the female map with 6.6 cM to sex and a LOD of 17.8, two other microsatellite markers were also linked with both 8.6 cM to sex and LOD score of 14.3 and 16.4. The genetic maps presented here will serve as a basis for the construction of a high-resolution genetic map, quantitative trait loci (QTLs) detection, marker-assisted selection (MAS) and comparative genome mapping.

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Although diet affects growth and behaviour, the adaptive mechanisms that coordinate these processes in non-optimal food sources are unclear. Here we show that the C. elegans tmc-1 channel, which is homologous to the mammalian tmc deafness genes, attenuates development and inhibits sexual behaviour in non-optimal food, the synthetic CeMM medium. In CeMM medium, signalling from the pharyngeal MC neurons and body wall muscles slows larval development. However, in the non-standard diet, mutation in tmc-1 accelerates development, by impairing the excitability of these cells. The tmc-1 larva can immediately generate ATP when fed CeMM, and their fast development requires insulin signalling. Our findings suggest that the tmc-1 channel indirectly affects metabolism in wild-type animals. In addition to regulating the development, we show that mutating tmc-1 can relax diet-induced inhibition of male sexual behaviour, thus indicating that a single regulator can be genetically modified to promote growth rate and reproductive success in new environments.

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Nematodes play key roles in marine ecosystem. Although oceans cover 71% of the Earth's surface, none of marine model nematode has been reported. Here, we constructed the first inbred line of free-living marine nematode Litoditis marina, sequenced and assembled its genome. Furthermore, we successfully applied CRISPR/Cas9 genome editing in L. marina.Comparative genomics revealed that immunity and oxygen regulation genes are expanded, which is probably central to its sediment adaptation. While L. marina exhibits massive gene contractions in NHRs, chemoreceptors, xenobiotics detoxification and core histones, which could explain the more defined marine environment. Our experiments showed that dozens of H4 genes in Caenorhabditis elegans might contribute to its adaptation to the complex terrestrial environments, while two H4 genes in L. marina are involved in salinity stress adaptation. Additionally, ninety-two conserved genes appear to be positively selected in L. marina, which may underpin its osmotic, neuronal and epigenetic changes in the sea. With short generation time, highly inbred lines, and genomic resources, our report brings L. marina a promising marine animal model, and a unique satellite marine model to the wellknown biomedical model nematode C. elegans. This study will underpin ongoing work on animal functional genomics, environmental adaptation and developmental evolution. 4 marine nematodes have had their genomes sequenced and analysed (International Helminth Genomes Consortium 2019; Smythe et al. 2019; Weinstein et al. 2019). Oceans cover 71% of the Earth's surface, and represents almost 99% of available habitat, which are a key element for the existence and evolution of life (Robert 1999; Peng et al. 2020). In marine sediments, free-living nematodes abound both in numbers and in local species diversity, comprising about 80% of the abundance of meiofauna (Heip et al. 1985; Danovaro et al. 2010; Nascimento et al. 2012), they play a key role in the benthic food web and ecosystem. However, the study of marine nematodes is largely limited to taxonomy and ecology (De Meester et al. 2016; Derycke et al. 2016). Molecular mechanisms underlying their evolution, development regulation and adaptation mechanisms are rarely reported, and none of marine model nematode has been reported. The bacterivorous marine nematode Litoditis marina (Bastian, 1865) Sudhaus, 2011, formerly known as Rhabditis marina or Pellioditis marina, is found widely distributed in the littoral zone of coasts and estuaries of European, American, African and Asian countries, and play an important role in these marine ecosystems (Tietjen et al. 1970; Kito 1981; Houthoofd et al. 2003; Derycke et al. 2016). In addition, the embryonic cell lineage of L. marina has been reported by Houthoofd et al. (2003). In comparison with C. elegans, the overall L. marina lineage homology is 95.5%, whereas the fate homology is only 76.4%, and most of the differences in fate homology concern nervous, epidermal, and pharyngeal tissues, suggesting that L. marina wil...

Evolutionary developmental biology, or Evo-Devo for short, has become an established field that, broadly speaking, seeks to understand how changes in development drive major transitions and innovation in organismal evolution. It does so via integrating the principles and methods of many subdisciplines of biology. Although we have gained unprecedented knowledge from the studies on model organisms in the past decades, many fundamental and crucially essential processes remain a mystery. Considering the tremendous biodiversity of our planet, the current model organisms seem insufficient for us to understand the evolutionary and physiological processes of life and its adaptation to exterior environments. The currently increasing genomic data and the recently available gene-editing tools make it possible to extend our studies to non-model organisms. In this review, we review the recent work on the regulatory signaling of developmental and regeneration processes, environmental adaptation, and evolutionary mechanisms using both the existing model animals such as zebrafish and Drosophila, and the emerging nonstandard model organisms including amphioxus, ascidian, ciliates, single-celled phytoplankton, and marine nematode. In addition, the challenging questions and new directions in these systems are outlined as well.

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Dysregulated metabolism accelerates reduced decision-making and locomotor ability during aging. To identify mechanisms for delaying behavioral decline, we investigated how C. elegans males sustain their copulatory behavior during early to mid-adulthood. We found that in mid-aged males, gluco-/glyceroneogenesis, promoted by phosphoenolpyruvate carboxykinase (PEPCK), sustains competitive reproductive behavior. C. elegans' PEPCK paralogs, pck-1 and pck-2, increase in expression during the first 2 days of adulthood. Insufficient PEPCK expression correlates with reduced egl-2-encoded ether-a-go-go K+ channel expression and premature hyper-excitability of copulatory circuits. For copulation, pck-1 is required in neurons, whereas pck-2 is required in the epidermis. However, PCK-2 is more essential, because we found that epidermal PCK-2 likely supplements the copulation circuitry with fuel. We identified the subunit A of succinate dehydrogenase SDHA-1 as a potent modulator of PEPCK expression. We postulate that during mid-adulthood, reduction in mitochondrial physiology signals the upregulation of cytosolic PEPCK to sustain the male's energy demands.