Alternative life-history styles of Japanese freshwater sculpins revisited

Synopsis Japanese freshwater sculpins consist of 6Cottus and 1Trachidermus species, with various types of life-cycles, namely, catadromous, amphidromous, lacustrine land-locked and fluvial land-locked. Among them,C. amblystomopsis andC. nozawae have been regarded as sibling species. Because of very similar morphological and ecological adult characteristics they were formerly classified as a single species.C. amblystomopsis mainly inhabits the lower courses of rivers and produces many small eggs from which pelagic larvae are formed. In contrast,C. nozawae lives in the middle or upper courses of rivers and deposits few, large eggs, from which well-developed benthic young emerge, well on the way to the definitive phenotype as fully formed juveniles. These two species have distinctly different life-cycles: amphidromous forC. amblystomopsis and fluvial forC. nozawae. A comparison of the early ontogeny shows that, amongCottus species, the small-egg, amphidromousC. amblystomopsis is altricial, while the large-egg, fluvialC. nozawae is precocial. Assuming thatC. nozawae has been derived phylogenetically fromC. amblystomopsis or its ancestral relatives, it is reasonable to consider that the fluvial land-locked life-history style ofC. nozawae has evolved from the ancestral arnphidromous one through adapting to the upstream habitat by an increase in egg size and consequent truncation of the larval period.     

Structure and function of hemoglobin in antarctic fishes and evolutionary implications

Summary The hematological features of cold-adapted, red-blooded Antarctic teleosts has prompted this study on the relationship between hemoglobin molecular structure and oxygen-binding properties. The hemolysates from 21 species of 5 families contained one component (Hb 1), often accompanied by an additional, minor one (Hb 2, 5%–10% of total). On the other hand, 3 species of Zoarcidae, a non-endemic family, had 4–5 components. All purified hemoglobins from the former group, but only 1–2 of the 4–5 hemoglobins of Zoarcidae, showed a strong Root effect (pH regulation of oxygen binding). Globins from each hemoglobin have been purified and characterised with respect to molecular structure in several species. The similarity between the complete amino acid sequence of one -chain and those of non-Antarctic -chains is lower than that among the latter sequences, suggesting independent pathways of evolution.Presented at the 5th SCAR Symposium on Antarctic Biology, Hobart, Australia (August 29th-September 3rd, 1988)     

Analysis of rice (Oryza sativa L.) genome using pulsed-field gel electrophoresis and rare-cutting restriction endonucleases

TheOryza sativa (rice) genome is small (600 to 900 megabase pairs) when compared to that of other monocotyledonous plants. Rice was the first of the major cereals to be successfully transformed and regenerated. An RFLP map with approximately 300 markers is readily available, and the DNA content per map unit is only two to three times that ofArabidopsis thaliana. Rice is also the main staple food for the majority of peoples in the world. We developed techniques for the preparation of intact genomic DNA from Indica and Japonica subspecies of rice, used statistical methods to determine which restriction endonucleases are rare-cutting, and used pulsed-field gel electrophoresis (PFE) to separate large fragments of rice DNA. Southern hybridization to blotted rice PFE gels was used to show that the digests were complete. The long-term goal of our work is to generate an integrated genetic/physical map for the rice genome, as well as helping to establish rice as a model for map-based gene cloning and genome analysis.     

Angiotensin converting enzyme inhibitor potentiated the vasorelaxant response of atrial natriuretic peptide in toad aortic rings

1. The vasorelaxant effect of synthetic atrial natriuretic peptide (ANP) on the vascular response to angiotensin II (A II) and norepinephrine (NE) in aortic rings from Bufo arenarum toad was studied. 2. Pretreatment with ANP partially inhibited the vascular response to A II and NE. 3. Angiotensin converting enzyme inhibitor (ACEI) treatment partially inhibited the contractile response of angiotensin I (A I) and did not affect the A II response. 4. The inhibitory effect of ANP on vascular response to A II and NE were potentiated by pretreatment with ACEI. 5. Results suggest that the angiotensin converting enzyme present in the vascular wall from Bufo arenarum toad may be involved in the metabolism of ANP.     

Deletion 2q31.3→2q33.3: gene dosage effect of ribulose 5-phosphate 3-epimerase

In a new case of interstitial del(2q), measurements of ribulose 5-phosphate 3-epimerase activity suggested that the locus for this enzyme might be localized to the subregion 2q32q33.3.     

Behaviour of Nif− mutants of Rhodobacter capsulatus in photosynthetic, ammonia-limited chemostat cultures

Abstract Nif⁻ mutants of Rhodobacter capsulatus carrying mutations either in the nifR4 regulatory gene or in the nifH structural gene both outgrew the wild-type strain B10 in mixed chemostat cultures under conditions favouring nitrogenase-mediated H₂ production by the wild-type (ammonia as limiting nutrient, inert argon atmosphere, light as energy source), whereas under aerobic conditions in the dark, or in batch culture, the growth of Nif⁻ mutants was not favoured. Nitrogenase-mediated H₂ production therefore appears to be detrimental to the growth of R. capsulatus in nitrogen-limited continuous culture, as may also be the case for other nitrogen fixers.     

The relationship between auto-agglutination, cell surface hydrophobicity and virulence of the fish pathogen Renibacterium salmoninarum

Abstract The cell surface hydrophobicity of Renibacterium salmoninarum strains was examined using a salt aggregation method. Those strains which were virulent in the test animal were sticky, auto-agglutinating and possessed a hydrophobic cell surface. Those strains with a low virulence were non-sticky, non-agglutinating and failed to aggregate in a high molar salt. Strains could not be distinguished using biochemical tests. There was no change in hydrophobicity following re-isolation of the bacteria from experimentally infected rainbow trout, Salmo gairdneri .     

Two-dimensional flow cytometric analysis of T cell subsets maintained in IL-2 medium after autologous mixed leukocyte reaction activation

Human T cells are stimulated with an autologous mixed leukocyte reaction (AMLR) and can be propagated in interleukin-2. Staining of the cultured cells with the combination of two monoclonal antibodies was evaluated by two-dimensional flow cytometry at weekly intervals. AMLR activation resulted in an initial preservation of the CD4+ (helper/inducer T) subset predominance over the CD8+ (suppressor/cytotoxic T) cells, noted on normal circulating blood lymphocytes. However, during culture in interleukin-2, there was a progressive increase in the percentages of CD8+ Leu 15- cytotoxic T, CD4+ Leu 8- helper T, and CD3+ HLA-DR+ activated T cells, and a concomitant decrease in those of CD4+ Leu 8+ suppressor inducer T and CD8+ Leu 15+ suppressor T cells if the responder sheep red blood cell (SRBC)-rosetting T cells were made up by tris ammonium chloride, but not by hypotonic shock treatment to lyse SRBC. The significant difference between hypotonic shock-T cells and ammonium chloride-T cells in the phenotypic changes of T cell subsets after long-term culture in an interleukin-2 medium may suggest a regulatory role of the ammonium chloride-sensitive T cells in the AMLR.     

Possible regulation of autologous mixed lymphocyte reaction by OKM1+ NK cells

T cells are stimulated by autologous non-T cells and interleukin 2 (IL-2) is produced in the conventional autologous mixed lymphocyte reaction (AMLR) in young healthy controls. The role of cells with natural killer (NK) cell markers (OKM1+ cells or Leu 7+ cells) in the AMLR was studied. There were significant inverse correlations between the percentage of input OKM1+ cells minus monocyte (OKM1+ NK cells) and either AMLR proliferation (gamma = -0.9, P less than 0.001) or IL-2 production (gamma = -0.75, P less than 0.01) in the AMLR cultures after 7 days measured at 7 days. A statistically significant correlation was observed between the percentage of input Leu 7+ cells and AMLR proliferation (gamma = -0.64, P less than 0.05), but not IL-2 production. These results suggest that the AMLR is controlled by OKM1+ NK, perhaps acting through IL-2 regulation.     

Proteolytic specificity of chicken cathepsin L on bovineβ-casein

The proteolytic specificity of chicken cathepsin L was studied using bovine -casein as substrate. The peptide mixtures obtained after various times of hydrolysis were separated by RP-HPLC and ten peptides were identified. Chicken cathepsin L accepts proline residues in all positions except P ₁ . Looking at the amino acid residues on the amino side of the scissile bond we found three times the Tyr-Pro pair at P ₁ –P ₂ positions and that the S ₁ subsite can interact with modified amino acids such as phosphoserine.Abbreviations RP-HPLC reverse phase high performance liquid chromatography - NMec N-methyl coumarylamide - TEA triethylamine - TFA trifluoroacetic acid