Early dolichyl sugar synthesis during differentiation of non-growing brine-shrimp (Artemia salina) embryos.
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ABSTRACT:
SUBMITTER: Quesada-Allue LA
PROVIDER: S-EPMC1163269 | biostudies-other | 1981 Aug
REPOSITORIES: biostudies-other
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Project description:During the early development of Artemia there is an increase in mitochondrial enzyme activities of about one order of magnitude, whereas the activities of two cytoplasmic enzymes tested as controls remain unaltered. The mitochondrial enzyme activation correlates with (i) large changes in mitochondrial morphology, (ii) a 5-fold increase in the amount of the H+-ATP synthase beta-subunit and (iii) a dramatic increase in the steady-state level of mitochondrial mRNAs, whereas mitochondrial rRNA concentrations remain mostly unchanged. In contrast, the level of mitochondrial DNA does not change significantly during the first 20 h after resumption of development. After hatching, the mitochondrial DNA content increases twice in parallel with one round of cellular division, thus indicating that mitochondrial and nuclear replication are coupled in Artemia postgastrular development. The data presented strongly suggest that mitochondrial maturation in the absence of significant mitochondrial proliferation is responsible for the dramatic increase in mitochondrial function that takes place after resumption of development in Artemia.
| S-EPMC1217079 | biostudies-other
Project description:Harmful algae may differently affect their primary grazers, causing sub-lethal effects and/or leading to their death. The present study aim to compare the effects of three toxic benthic dinoflagellates on clearance and grazing rates, behavioral changes, and survival of Artemia salina. Feeding assays consisted in 1-h incubations of brine shrimps with the toxic Prorocentrum lima, Gambierdiscus excentricus and Ostreopsis cf. ovata and the non-toxic Tetraselmis sp. Brine shrimps fed unselectively on all toxic and non-toxic algal preys, without significant differences in clearance and ingestion rates. Acute toxicity assays were performed with dinoflagellate cells in two growth phases during 7-h to assess differences in cell toxicity to A. salina. Additionally, exposure to cell-free medium was performed to evaluate its effects on A. salina survival. The behavior of brine shrimps significantly changed during exposure to the toxic dinoflagellates, becoming immobile at the bottom by the end of the trials. Dinoflagellates significantly affected A. salina survival with 100% mortality after 7-h exposure to cells in exponential phase (all treatments) and to P. lima in stationary phase. Mortality rates of brine shrimps exposed to O. cf. ovata and G. excentricus in stationary phase were 91% and 75%, respectively. However, incubations of the brine shrimps with cell-free medium did not affect A. salina survivorship. Significant differences in toxic effects between cell growth phases were only found in the survival rates of A. salina exposed to G. excentricus. Acute exposure to benthic toxic dinoflagellates induced harmful effects on behavior and survival of A. salina. Negative effects related to the toxicity of benthic dinoflagellates are thus expected on their primary grazers making them more vulnerable to predation and vectors of toxins through the marine food webs.
| S-EPMC5384755 | biostudies-literature
Project description:The P1P4-bis(5'-nucleosidyl) tetraphosphate asymmetrical-pyrophosphohydrolase from encysted embryos of the brine shrimp Artemia has been purified over 11,000-fold to homogeneity. Anion-exchange chromatography resolves two major species with very similar properties. The enzyme is a single polypeptide of Mr 17,600 and is maximally active at pH 8.4 and 2 mM-Mg2+. It is inhibited by Ca2+ (IC50 = 0.9 mM with 2 mM-Mg2+) but not by Zn2+ ions. It preferentially hydrolyses P1P4-bis(5'-nucleosidyl) tetraphosphates, e.g. P1P4-bis(5'-adenosyl) tetraphosphate (Ap4A) (kcat. = 12.7 s-1; Km = 33 microM) and P1P4-bis(5'-guanosyl) tetraphosphate (Gp4G) (kcat. = 6.2 s-1; Km = 5 microM). With adenosine 5'-P1-tetraphospho-P4-5"'-guanosine (Ap4G) as substrate, there is a 4.5-fold preference for AMP and GTP as products and biphasic reaction kinetics are observed giving Km values of 4.7 microM and 34 microM, and corresponding rate constants of 6.5 s-1 and 11.9 s-1. The net rate constant for Ap4G hydrolysis is 7.6 s-1. The enzyme will also hydrolyse nucleotides with more than four phosphate groups, e.g. Ap5G, Ap6A and Gp5G are hydrolysed at 25%, 18% and 10% of the rate of Ap4A respectively. An NTP is always one of the products. Ap2A and Gp2G are not hydrolysed, while Ap3A and Gp3G are very poor substrates. When the enzyme is partially purified from embryos and larvae at different stages of development by sedimentation through a sucrose density gradient, its activity increases 3-fold during the first 12 h of pre-emergence development. This is followed by a slow decline during subsequent larval development. The similarity of this enzyme to other asymmetrical-pyrophosphohydrolases suggests that it did not evolve specifically to degrade the large yolk platelet store of Gp4G which is found in Artemia embryos, but that it probably serves the same general function in bis(5'-nucleosidyl) oligophosphate metabolism as in other cells.
| S-EPMC1138592 | biostudies-other
Project description:DNA barcoding is a powerful approach for characterizing species of organisms, especially those with almost identical morphological features, thereby helping to to establish phylogenetic relationships and reveal evolutionary histories. In this study, we chose a 648-bp segment of the mitochondrial gene, cytochrome c oxidase subunit 1 (COI), as a standard barcode region to establish phylogenetic relationships among brine shrimp (Artemia) species from major habitats around the world and further focused on the biodiversity of Artemia species in China, especially in the Tibetan Plateau. Samples from five major salt lakes of the Tibetan Plateau located at altitudes over 4,000 m showed clear differences from other Artemia populations in China. We also observed two consistent amino acid changes, 153A/V and 183L/F, in the COI gene between the high and low altitude species in China. Moreover, indels in the COI sequence were identified in cyst and adult samples unique to the Co Qen population from the Tibetan Plateau, demonstrating the need for additional investigations of the mitochondrial genome among Tibetan Artemia populations.
| S-EPMC5054130 | biostudies-literature
Project description:BackgroundPrior research on the microorganisms associated with the brine shrimp, Artemia franciscana, has mainly been limited to culture-based identification techniques or feeding studies for aquaculture. Our objective was to identify bacteria and archaea associated with Artemia adults and encysted embryos to understand the role of microbes in the Artemia life cycle and, therefore, their importance in a hypersaline food chain.ResultsWe used small subunit (SSU) 16S ribosomal RNA gene sequencing to identify bacteria and archaea associated with adults and encysted Artemia embryos from one of their natural environments - Great Salt Lake (GSL), Utah, USA. We found that bacterial sequences most closely related to the genera Halomonas and Vibrio were commonly extracted from GSL adult Artemia, while bacterial sequences most similar to the genera Halomonas, Psychroflexus and Alkalilimnicola dominate in GSL water. Encysted embryos (cysts) yielded bacterial sequences from the genera Idiomarina and Salinivibrio, which were absent from adults and water. Common archaeal sequences in adults were most closely related to the genera Haloterrigena and Haloarcula, while all of the archaeal sequences from GSL water were most similar to the genus Halogeometricum. Cyst derived archaeal sequences were most closely related to the genera Halorubrum and Haloarcula.ConclusionsIn addition to identifying microbial rRNA sequences that are specific to different stages of the Artemia life cycle, we observed striking differences in the sequences associated with the adult Artemia population in samples collected from GSL at different times and locations. While our study was limited in scope and the sample was small, our findings provide a foundation for future research into how the bacteria and archaea associated with Artemia influence the Artemia life cycle, and GSL food web.
| S-EPMC3599907 | biostudies-literature
Project description:Eurasian brine shrimp (genus Artemia) have closely related sexual and asexual lineages of parthenogenetic females, which produce rare males at low frequencies. Although they are known to have ZW chromosomes, these are not well characterized, and it is unclear whether they are shared across the clade. Furthermore, the underlying genetic architecture of the transmission of asexuality, which can occur when rare males mate with closely related sexual females, is not well understood. We produced a chromosome-level assembly for the sexual Eurasian species Artemia sinica and characterized in detail the pair of sex chromosomes of this species. We combined this new assembly with short-read genomic data for the sexual species Artemia sp. Kazakhstan and several asexual lineages of Artemia parthenogenetica, allowing us to perform an in-depth characterization of sex-chromosome evolution across the genus. We identified a small differentiated region of the ZW pair that is shared by all sexual and asexual lineages, supporting the shared ancestry of the sex chromosomes. We also inferred that recombination suppression has spread to larger sections of the chromosome independently in the American and Eurasian lineages. Finally, we took advantage of a rare male, which we backcrossed to sexual females, to explore the genetic basis of asexuality. Our results suggest that parthenogenesis is likely partly controlled by a locus on the Z chromosome, highlighting the interplay between sex determination and asexuality.
| S-EPMC9526061 | biostudies-literature
Project description:Bacterial infectious diseases produced by Vibrio are the main cause of economic losses in aquaculture. During recent years it has been shown that the expression of virulence genes in some Vibrio species is controlled by a population-density dependent gene-expression mechanism known as quorum sensing (QS), which is mediated by the diffusion of signal molecules such as N-acylhomoserine lactones (AHLs). QS disruption, especially the enzymatic degradation of signalling molecules, known as quorum quenching (QQ), is one of the novel therapeutic strategies for the treatment of bacterial infections. In this study, we present the detection of AHLs in 34 marine Vibrionaceae strains. Three aquaculture-related pathogenic Vibrio strains, V. mediterranei VibC-Oc-097, V. owensii VibC-Oc-106 and V. coralliilyticus VibC-Oc-193 were selected for further studies based on their virulence and high production of AHLs. This is the first report where the signal molecules have been characterized in these emerging marine pathogens and correlated to the expression of virulence factors. Moreover, the results of AHL inactivation in the three selected strains have been confirmed in vivo against brine shrimps (Artemia salina) and Manila clams (Venerupis philippinarum). This research contributes to the development of future therapies based on AHL disruption, the most promising alternatives for fighting infectious diseases in aquaculture.
| S-EPMC5903640 | biostudies-literature
Project description:The understanding of sex determination and differentiation in animals has recently made remarkable strides through the use of advanced research tools. At the gene level, the Mab-3-related transcription factor (Dmrt) gene family, which encodes for the typical DNA-binding doublesex/Mab-3 (DM) domain in their protein, is known for its contribution to sex determination and differentiation in insects. In this study, DNA-binding DM domain screening has identified eight transcripts from Artemia franciscana transcriptomic that encode proteins containing one conserved DNA-binding DM domain. The genome mapping confirmed that these eight transcripts are transcribed from six different loci on the A. franciscana genome assembly. One of those loci, the Af.dsx-4 locus, is closely related to Doublesex, a gene belonging to the Dmrt gene family. This locus could be transcribed into three alternative transcripts, namely Af.dsx4, Af.dsxF and Af.dsxM. While Af.dsx4 and Af.dsxF could putatively be translated to form an identical Af.dsxF protein of 186 aa long, Af.dsxM translates for an Af.dsxM protein of 289 aa long but shares a DNA-binding DM domain. Interestingly, Af.dsxF and Af.dsxM are confirmed as sex-specific transcripts, Af.dsxF is only present in females, and Af.dsxM is only present in male individuals. The results suggest that the sex-specific splicing mechanism of the doublesex described in insects is also present in A. franciscana. Af.dxs-4 locus can be used in further studies to clarify the sex determination pathways in A. fracnciscana.
| S-EPMC9690683 | biostudies-literature
Project description:Genealogical concordance is a critical overlay of all phylogenetic analyses, irrespective of taxonomic level. To assess such patterns of congruence we have compiled and derived sequence data for two mitochondrial (16S rRNA, COI) and two nuclear (ITS1, p26) markers in 14 American populations of the hypersaline branchiopod Artemia franciscana. Cladistic analysis revealed three reciprocally monophyletic mitochondrial clades. For nuclear DNA, incomplete lineage sorting was evident presumably as a result of slower coalescence or male-mediated dispersal. Our findings capture the genealogical interval between gene splitting and population divergence. In this sense, strong indications are provided in favour of a superspecies status and ongoing speciation in A. franciscana.
| S-EPMC2802004 | biostudies-literature
Project description:While sexual reproduction is widespread among many taxa, asexual lineages have repeatedly evolved from sexual ancestors. Despite extensive research on the evolution of sex, it is still unclear whether this switch represents a major transition requiring major molecular reorganization, and how convergent the changes involved are. In this study, we investigated the phylogenetic relationship and patterns of gene expression of sexual and asexual lineages of Eurasian Artemia brine shrimp, to assess how gene expression patterns are affected by the transition to asexuality. We find only a few genes that are consistently associated with the evolution of asexuality, suggesting that this shift may not require an extensive overhauling of the meiotic machinery. While genes with sex-biased expression have high rates of expression divergence within Eurasian Artemia, neither female- nor male-biased genes appear to show unusual evolutionary patterns after sexuality is lost, contrary to theoretical expectations.
| S-EPMC8456138 | biostudies-literature