Biology of the leech Actinobdella inequiannulata Moore, 1901 (Annelida: Hirudinea: Rhynchobdellida: Glossiphoniidae), parasitic on the white sucker, Catostomus commersoni Lacepede, 1803, and the longnose sucker, Catostomus catostomus Forster, 1773, in Algonquin Provincial Park, Ontario, Canada

Actinobdella inequiannulata was found on the white sucker. Catostomus commersoni, and less frequently on the longnose sucker, Catostomus catostomus, in Algonquin Provincial Park, Ontario, Canada. Catostomus commersoni parasitized with Act. inequiannulata was collected from July to October 1973 and May to October 1974. In May and October, less than 3% of the fish carried leeches. In July, 80% of the fish were parasitized with an average of 1.5 leeches/fish. Observations on leech weight suggest that young leeches attach to fish from May to September, some mature in July, and a second generation of leeches reparasitize the fish in August and September. The mean size of leeches on suckers increased from May until July, after which the size remained relatively constant. Leeches produced characteristic lesions on the opercula of suckers. Fully developed lesions on fish opercula produced by aggregated leeches had varying amounts of central erosion, extravasation, dermal and epidermal hyperplasia, and necrosis.

葛洲坝下游胭脂鱼的繁殖生物学和人工繁殖初报

<正> 胭脂鱼(Myxocyprinus asiaticus)属鲤形目,胭脂鱼科,是我国的一种珍稀鱼类。胭脂鱼科约有65种,几乎都分布于北美洲。在亚洲只有两种,而见于西伯利亚东部的亚口鱼(Catostomus catostomus)是与北美共有的一个种。唯有胭脂鱼是亚洲特有的物种,因此,它在鱼类学和动物地理学上占有特殊的地位,具有重要的科学价值。胭脂鱼主要分布在长江,其体型大,摄食水生无脊椎动物。胭脂鱼产卵场主要在长江上游,繁殖的仔鱼大量漂流到中下游,生长数年成熟后,溯游到上游参加繁殖。长江干流兴建葛洲坝

A PEPTIDE FROM THE CAUDAL NEUROSECRETORY-SYSTEM OF THE DOGFISH SCYLIORHINUS-CANICULA THAT IS STRUCTURALLY RELATED TO UROTENSIN-I

Using reversed-phase HPLC in combination with a radioimmunoassay for ovine corticotropin-releasing hormone (CRH), a peptide with CRH-like immunoreactivity was isolated in pure form from an extract of the caudal spinal cord region of the spotted dogfish, Scyliorhinus canicula. The primary structure of the peptide was established as Pro-Ala-Glu-Thr-Pro-Asn-Ser-Leu-Asp-Leu(10)-Thr-Phe-His-Leu-Leu-Arg-Glu-Met-Ile-Glu(20)-Ile-Ala-Lys-His-Glu-Asn-Gln-Gln-Met-Gln(30)-Ala-Asp-Ser-Asn-Arg-Arg-Ile-Met-Asp-Thr(40)-Ile . NH2. This amino acid sequence shows moderate structural similarity to Catostomus urotensin I (51%) and to human CRH (56%). The data provide, therefore, chemical evidence to support the conclusions of earlier immunohistochemical studies that the diffuse caudal neurosecretory system of elasmobranchs produces a peptide that is immunochemically related to teleost urotensin I peptides. However, the primary structure of urotensin I has been poorly conserved during evolution. (C) 1995 Academic Press, Inc.

Mutational analysis and molecular modeling of the nonapeptide hormone binding domains of the [Arg8]vasotocin receptor.

To identify determinants that form nonapeptide hormone binding domains of the white sucker Catostomus commersoni [Arg8]vasotocin receptor, chimeric constructs encoding parts of the vasotocin receptor and parts of the isotocin receptor have been analyzed by [(3,5-3H)Tyr2, Arg8]vasotocin binding to membranes of human embryonic kidney cells previously transfected with the different cDNA constructs and by functional expression studies in Xenopus laevis oocytes injected with mutant cRNAs. The results indicate that the N terminus and a region spanning the second extracellular loop and its flanking transmembrane segments, which contains a number of amino acid residues that are conserved throughout the nonapeptide receptor family, contribute to the affinity of the receptor for its ligand. Nonapeptide selectivity, however, is mainly defined by transmembrane region VI and the third extracellular loop. These results are complemented by a molecular model of the vasotocin receptor obtained by aligning its sequence with those of other G-protein coupled receptors as well as that of bacteriorhodopsin. The model indicates that amino acid residues of transmembrane regions II-VII that are located close to the extracellular surface also contribute to the binding of vasotocin.