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Oreochromis mossambicus (tilapia) Corticotropin-Releasing Hormone: cDNA Sequence and Bioactivity (2000)

Van Enckevort, F. H. J. ; Pepels, P. P. L. M. ; Leunissen, J. A. M. ; [et al.]

Oxford, UK : Blackwell Science Ltd

Journal of neuroendocrinology 12 (2000), S. 0

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ISSN: 1365-2826

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Medicine

Notes: Although hypothalamic corticotropin-releasing hormone (CRH) is involved in the stress response in all vertebrate groups, only a limited number of studies on this neuroendocrine peptide deals with non-mammalian neuroendocrine systems. We determined the cDNA sequence of the CRH precursor of the teleost Oreochromis mossambicus (tilapia) and studied the biological potency of the CRH peptide in a homologous teleost bioassay. Polymerase chain reaction (PCR) with degenerate and specific primers yielded fragments of tilapia CRH cDNA. Full-length CRH cDNA (988 nucleotides) was obtained by screening a tilapia hypothalamus cDNA library with the tilapia CRH PCR products. The precursor sequence (167 amino acids) contains a signal peptide, the CRH peptide and a motif conserved among all vertebrate CRH precursors. Tilapia CRH (41 aa) displays between 63% and 80% amino acid sequence identity to CRH from other vertebrates, whereas the degree of identity to members of the urotensin I/urocortin lineage is considerably lower. In a phylogenetic tree, based on alignment of all full CRH peptide precursors presently known, the three teleost CRH precursors (tilapia; sockeye salmon, Oncorhynchus nerka; white sucker, Catostomus commersoni) form a monophyletic group distinct from amphibian and mammalian precursors. Despite the differences between the primary structures of tilapia and rat CRH, maximally effective concentrations of tilapia and rat CRH were equally potent in stimulating adrenocorticotropic hormone (ACTH) and α-MSH release by tilapia pituitaries in vitro. The tilapia and salmon CRH sequences show that more variation exists between orthologous vertebrate CRH structures, and teleost CRHs in particular than previously recognized. Whether the structural differences reflect different mechanisms of action of this peptide in the stress response remains to be investigated.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2826.2000.00434.x

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Comparison ofGiardia isolates from different laboratories by isoenzyme analysis and recombinant DNA probes (1992)

Homan, W. L. ; Enckevort, F. H. J. ; Limper, L. ; [et al.]

Springer

Parasitology research 78 (1992), S. 316-323

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ISSN: 1432-1955

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract A total of 13 newGiardia isolates were established in axenic culture. All of the new isolates were obtained by excystation ofGiardia cysts from the feces of patients in Dutch hospitals. These isolates were subjected to isoenzyme and DNA analysis together with isolates from Poland, Belgium, and various other parts of the world. Isoenzyme analysis revealed that nearly all of the newly established isolates exhibited unique zymodemes. Isolates obtained from individuals from Belgium and Poland, on the other hand, displayed single zymodemes. Genomic DNA libraries were constructed from isolates belonging to the latter two zymodemes; specific and common recombinant DNA clones were selected from these libraries. Differential screening revealed that the two isolates had only 80% of the clones in common. Restriction-fragment-length polymorphism analysis using three different probes together with two synthetic probes that are complementary toGiardia structural protein genes led to the separation of all isolates into two major groups; within these groups, a further division could be made by application of other techniques or probes. The results of DNA analysis and zymodeme classification were in general agreement; in the present report they are compared with the data in the literature and discussed.