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  • 1
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    Identification of a juvenile hormone-like compound in a crustacean (1987)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1987-01-09
    Description: Juvenile hormone (JH) has central roles in the regulation of insect development and reproduction but has not previously been identified in other arthropod classes. The hemolymph of a crustacean, Libinia emarginata (Leach), has now been analyzed for JH-like compounds. Samples contained 0.003 to 0.030 nanogram of JH III per milliliter and 10 to 50 nanograms of methyl farnesoate per milliliter; methyl farnesoate is a compound structurally related to JH III that has JH bioactivity. Several tissues were examined for synthesis and secretion of JH-like compounds. Of these tissues, only the mandibular organs produced and secreted JH III and methyl farnesoate. However, microchemical analysis revealed that this JH III was racemic, and thus likely an artifactual oxidation product of methyl farnesoate. Secretion of methyl farnesoate was related to reproduction in females, with the highest rates observed in Libinia near the end of the ovarian cycle when oocyte growth and vitellogenesis are greatest. These results indicate that JH-like compounds such as methyl farnesoate have regulatory roles in crustaceans.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Laufer, H -- Borst, D -- Baker, F C -- Reuter, C C -- Tsai, L W -- Schooley, D A -- Carrasco, C -- Sinkus, M -- New York, N.Y. -- Science. 1987 Jan 9;235(4785):202-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17778635" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Programmed gene rearrangements altering gene expression (1987)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1987-02-06
    Description: Programmed gene rearrangements are used in nature to to alter gene copy number (gene amplification and deletion), to create diversity by reassorting gene segments (as in the formation of mammalian immunoglobulin genes), or to control the expression of a set of genes that code for the same function (such as surface antigens). Two major mechanisms for expression control are DNA inversion and DNA transposition. In DNA inversion a DNA segment flips around and is rejoined by site-specific recombination, disconnecting or connecting a gene to sequences required for its expression. In DNA transposition a gene moves into an expression site where it displaces its predecessor by gene conversion. Gene rearrangements altering gene expression have mainly been found in some unicellular organisms. They allow a fraction of the organisms to preadapt to sudden changes in environment, that is, to alter properties such as surface antigens in the absence of an inducing stimulus. The antigenic variation that helps the causative agents of African trypanosomiasis, gonorrhea, and relapsing fever to elude host defense is controlled in this way.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Borst, P -- Greaves, D R -- New York, N.Y. -- Science. 1987 Feb 6;235(4789):658-67.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3544215" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens/genetics ; B-Lymphocytes/physiology ; Borrelia/immunology ; Chromosome Deletion ; *Gene Amplification ; *Gene Expression Regulation ; Glycoproteins/genetics ; Humans ; Immunoglobulins/genetics ; Neisseria/immunology ; Peptides/genetics ; *Recombination, Genetic ; Saccharomyces cerevisiae/genetics ; T-Lymphocytes/physiology ; Trypanosoma/genetics ; Variant Surface Glycoproteins, Trypanosoma ; Zea mays/genetics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
    Location Call Number Expected Availability
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