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Useful Model Organism (useful + model_organism)
Selected AbstractsCalcium and magnesium competitively influence the growth of a PMR1 deficient Saccharomyces cerevisiae strainFEMS MICROBIOLOGY LETTERS, Issue 2 2005Réka Szigeti Abstract PMR1, the Ca2+/Mn2+ ATPase of the secretory pathway in Saccharomyces cerevisiae was the first member of the secretory pathway Ca2+ ATPases (SPCA) to be characterized. In the past few years, pmr1, yeast have received more attention due to the recognition that the human homologue of this protein, hSPCA1 is defective in chronic benign pemphigus or Hailey,Hailey disease (HHD). Recent publications have described pmr1, S. cerevisiae as a useful model organism for studying the molecular pathology of HHD. Some observations indicated that the high Ca2+ sensitive phenotype of PMR1 defective yeast strains may be the most relevant in this respect. Here we show that the total cellular calcium response of a pmr1, S. cerevisiae upon extracellular Ca2+ challenge is decreased compared to the wild type strain similarly as observed in keratinocytes. Additionally, the novel magnesium sensitivity of PMR1 defective yeast is revealed, which appears to be a result of competition for uptake between Ca2+ and Mg2+ at the plasma membrane level. Our findings indicate that extracellular Ca2+ and Mg2+ competitively influence the intracellular Ca2+ homeostasis of S. cerevisiae. These observations may further our understanding of HHD. [source] Selenium metabolism in zebrafish: multiplicity of selenoprotein genes and expression of a protein containing 17 selenocysteine residuesGENES TO CELLS, Issue 12 2000Gregory V. Kryukov Fish are an important source of selenium in human nutrition and the zebrafish is a potentially useful model organism for the study of selenium metabolism and its role in biology and medicine. Selenium is present in vertebrate proteins in the form of selenocysteine (Sec), the 21st natural amino acid in protein which is encoded by UGA. We report here the detection of 18 zebrafish genes for Sec-containing proteins. We found two zebrafish orthologs of human SelT, glutathione peroxidase 1 and glutathione peroxidase 4, and single orthologs of several other selenoproteins. In addition, new zebrafish selenoproteins were identified that were distant homologues of SelP, SelT and SelW, but their direct orthologs in other species are not known. This multiplicity of selenoprotein genes appeared to result from gene and genome duplications, followed by the retention of new selenoprotein genes. We found a zebrafish selenoprotein P gene (designated zSelPa) that contained two Sec insertion sequence (SECIS) elements and encoded a protein containing 17 Sec residues, the largest number of Sec residues found in any known protein. In contrast, a second SelP gene (designated zSelPb) was also identified that contained one SECIS element and encoded a protein with a single Sec. We found that zSelPa could be expressed and secreted by mammalian cells. The occurrence of zSelPa and zSelPb suggested that the function of the N-terminal domain of mammalian SelP proteins may be separated from that of the C-terminal Sec-rich sequence: the N-terminal domain containing the UxxC motif is likely involved in oxidoreduction, whereas the C-terminal portion of the protein may function in selenium transport or storage. Our data also suggest that the utilization of Sec is more common in zebrafish than in previously characterized species, including mammals. [source] Ethanol preference in C. elegansGENES, BRAIN AND BEHAVIOR, Issue 6 2009J. Lee Caenorhabditis elegans senses multiple environmental stimuli through sensory systems and rapidly changes its behaviors for survival. With a simple and well-characterized nervous system, C. elegans is a suitable animal model for studying behavioral plasticity. Previous studies have shown acute neurodepressive effects of ethanol on multiple behaviors of C. elegans similar to the effect of ethanol on other organisms. Caenorhabditis elegans also develops ethanol tolerance during continuous exposure to ethanol. In mammals, chronic ethanol exposure leads to ethanol tolerance as well as increased ethanol consumption. Ethanol preference is associated with the development of tolerance and may lead to the development of ethanol dependence. In this study, we show that C. elegans is a useful model organism for studying chronic effects of ethanol, including the development of ethanol preference. We designed a behavioral assay for testing ethanol preference after prolonged ethanol exposure. Despite baseline aversive responses to ethanol, animals show ethanol preference after 4 h of pre-exposure to ethanol and exhibit significantly enhanced preference for ethanol after a lifetime of ethanol exposure. The cat-2 and tph-1 mutant animals have defects in the synthetic enzymes for dopamine and serotonin, respectively. These mutants are deficient in the development of ethanol preference, indicating that dopamine and serotonin are required for this form of behavioral plasticity. [source] Differentiation of morphology, genetics and electric signals in a region of sympatry between sister species of African electric fish (Mormyridae)JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2008S. LAVOUÉ Abstract Mormyrid fishes produce and sense weak electric organ discharges (EODs) for object detection and communication, and they have been increasingly recognized as useful model organisms for studying signal evolution and speciation. EOD waveform variation can provide important clues to sympatric species boundaries between otherwise similar or morphologically cryptic forms. Endemic to the watersheds of Gabon (Central Africa), Ivindomyrus marchei and Ivindomyrus opdenboschi are morphologically similar to one another. Using morphometric, electrophysiological and molecular characters [cytochrome b sequences and amplified fragment length polymorphism (AFLP) genotypes], we investigated to what extent these nominal mormyrid species have diverged into biological species. Our sampling covered the known distribution of each species with a focus on the Ivindo River, where the two taxa co-occur. An overall pattern of congruence among datasets suggests that I. opdenboschi and I. marchei are mostly distinct. Electric signal analysis showed that EODs of I. opdenboschi tend to have a smaller initial head-positive peak than those of I. marchei, and they often possess a small third waveform peak that is typically absent in EODs of I. marchei. Analysis of sympatric I. opdenboschi and I. marchei populations revealed slight, but significant, genetic partitioning between populations based on AFLP data (FST , 0.04). Taken separately, however, none of the characters we evaluated allowed us to discriminate two completely distinct or monophyletic groups. Lack of robust separation on the basis of any single character set may be a consequence of incomplete lineage sorting due to recent ancestry and/or introgressive hybridization. Incongruence between genetic datasets in one individual, which exhibited a mitochondrial haplotype characteristic of I. marchei but nevertheless fell within a genetic cluster of I. opdenboschi based on AFLP genotypes, suggests that a low level of recent hybridization may also be contributing to patterns of character variation in sympatry. Nevertheless, despite less than perfect separability based on any one dataset and inconclusive evidence for complete reproductive isolation between them in the Ivindo River, we find sufficient evidence to support the existence of two distinctive species, I. opdenboschi and I. marchei, even if not ,biological species' in the Mayrian sense. [source] | ||||||||||