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141.
Mating system of the rockfish, <Emphasis Type="Italic">Sebastiscus marmoratus</Emphasis> as revealed by DNA fingerprinting 总被引:1,自引:0,他引:1
Wai-Chuen?NgEmail author Yvonne?Sadovy Frederick C.C.?Leung 《Ichthyological Research》2003,50(4):339-348
The mating system of the viviparous rockfish, Sebastiscus marmoratus was studied using aquarium mating experiments and paternity testing by DNA fingerprinting. Individually specific DNA fingerprints were produced and the paternal relationships determined with the use of the restriction enzyme HinfI and the DNA probe (CAC)5. Two types of mating experiments, multiple-male and single-male, were set up to investigate the effect of male sizes on their mating success, as determined by number of females fertilized. Male size was positively and significantly related to mating success in the multiple-male situation in which male–male interaction was present, but not in the single-male situation in which no male–male interaction was involved. Females produced one to seven batches of larvae, and all batches from individual females had identical paternity. Most females were fertilized by a single male but one case of multiple paternity was detected. The laboratory study suggested the principal mating system of S. marmoratus to be promiscuity, although multiple mating by females was uncommon. 相似文献
142.
Volff JN Körting C Froschauer A Zhou Q Wilde B Schultheis C Selz Y Sweeney K Duschl J Wichert K Altschmied J Schartl M 《Genomics》2003,82(4):470-479
The Xmrk oncogene involved in melanoma formation in the fish Xiphophorus was formed relatively recently by duplication of the epidermal growth factor co-orthologue egfrb. In the platyfish X. maculatus, Xmrk is located close to the major sex-determining locus in a subtelomeric region of the X and Y sex chromosomes that frequently undergoes duplications and other rearrangements. This region accumulates repetitive sequences: more than 80% of the 33-kb region 3' of Xmrk is constituted by retrotransposable elements. The high degree of nucleotide identity between X- and Y-linked sequences and the rarity of gonosome-specific rearrangements indicated that the instability observed was not a manifestation of gonosome-specific degeneration. Seven other duplicated genes were found, all corresponding, in contrast to Xmrk, to pseudogenes (nonfunctionalization). Functional persistence of Xmrk in a highly unstable region in divergent Xiphophorus species suggests a beneficial function under certain conditions for this dispensable and potentially injurious gene. 相似文献
143.
Biosynthesis of calystegines: 15N NMR and kinetics of formation in root cultures of Calystegia sepium 总被引:1,自引:0,他引:1
Calystegines are nortropane alkaloids bearing between three and five hydroxyl groups in various positions. [15N]Tropinone was administered to root cultures of Calystegia sepium and the incorporation into calystegines was followed. Increase of label in calystegines was measured by one-dimensional 15N NMR and inverse-detected 2D NMR techniques. The results show that tropinone and pseudotropine are metabolites in the biosynthetic pathway of calystegines. The velocity of calystegine accumulation was followed kinetically by transfer of root cultures from 15N-enriched medium to 14N-medium and analysis by GC-MS. A constant calystegine formation with no interference by excretion or degradation was observed. A biosynthetic rate for individual calystegines at each time point was calculated, the maximum was 0.4 mg/day/g of biomass. This allowed the velocity of individual biosynthetic steps to be estimated. 相似文献
144.
Dennis?M?Maddox Anna?Manlapat Penny?Roon Puttur?Prasad Vadivel?Ganapathy Sylvia?B?SmithEmail author 《BMC developmental biology》2003,3(1):6
Background
Folate is essential for cellular proliferation and tissue regeneration. As mammalian cells cannot synthesize folates de novo, tightly regulated cellular uptake processes have evolved to sustain sufficient levels of intracellular tetrahydrofolate cofactors to support biosynthesis of purines, pyrimidines, and some amino acids (serine, methionine). Though reduced-folate carrier (RFC) is one of the major proteins mediating folate transport, knowledge of the developmental expression of RFC is lacking. We utilized in situ hybridization and immunolocalization to determine the developmental distribution of RFC message and protein, respectively. 相似文献145.
Richard?IvellEmail author Marga?Balvers Yvonne?Pohnke Ralph?Telgmann Olaf?Bartsch Karin?Milde-Langosch Ana-maria?Bamberger Almuth?Einspanier 《Reproductive biology and endocrinology : RB&E》2003,1(1):114
Background
The receptor for the peptide hormone relaxin has recently been identified as the heptahelical G-protein coupled receptor, LGR7. In order to generate molecular tools with which to characterize both in vivo and in vitro expression of this receptor in human and primate tissues, specific monotypic antibodies have been generated and applied to a preliminary analysis of human and primate female reproductive tissues. 相似文献146.
147.
148.
Extended Survival and Persistence of Campylobacter spp. in Water and Aquatic Biofilms and Their Detection by Immunofluorescent-Antibody and -rRNA Staining 总被引:4,自引:0,他引:4 下载免费PDF全文
Clive M. Buswell Yvonne M. Herlihy Lorna M. Lawrence James T. M. McGuiggan Philip D. Marsh C. William Keevil Steve A. Leach 《Applied microbiology》1998,64(2):733-741
In water microcosm experiments, the survival times of Campylobacter isolates differed by up to twofold, as determined by culturing; this difference increased to fourfold when particular combinations of temperature and oxygenation were used. The mean survival times were much longer at 4 and 10°C (202 and 176 h, respectively) than at 22 and 37°C (43 and 22 h, respectively). The influence of anaerobiosis on survival time was less dramatic and differed considerably between isolates. In a two-stage water distribution model preparation containing a biofilm consisting of standardized autochthonous water microflora, Campylobacter isolates continued to differ in survival time. However, the survival times of cultures were considerably longer in the presence of the autochthonous water microflora (strains CH1 and 9752 survived 700 and 360 h, respectively, at 4°C) than in the sterile microcosms (strains CH1 and 9752 survived 230 and 157 h, respectively). Although increased temperature and oxygenation were generally detrimental to culturability, the interaction of these two factors influenced the two strains examined differently. When the organisms were grown aerobically at 30°C, the survival of the two strains was reversed; aerobiosis decreased the survival time of strain CH1 by 30%, but unexpectedly improved the persistence time of strain 9752 by more than threefold. Persistence times within biofilms were much longer when they were determined by detection methods not involving culturing. Immunofluorescent-antibody staining demonstrated that the pathogen persisted up to the termination of the experiments after 28 and 42 days of incubation at 30 and 4°C, respectively. The specificity of detection within intact biofilms was reduced because of high background fluorescence. However, preliminary studies with a Campylobacter-specific rRNA probe revealed the same extended persistence of the pathogen within the biofilms. 相似文献
149.
Molecular Analysis of Hypervirulent Somatic Hybrids of the Entomopathogenic Fungi Beauveria bassiana and Beauveria sulfurescens 总被引:3,自引:0,他引:3 下载免费PDF全文
Protoplast fusion of diauxotrophic mutants of a Beauveria bassiana entomopathogenic strain (Bb28) and a Beauveria sulfurescens toxinogenic strain (Bs2) produced hybrids which were significantly different from the parents in pathogenicity. Some of the hybrids were hypervirulent and killed insects more quickly than the Bb28 strain, probably because these hybrids had acquired the toxic activity of the Bs2 strain. By using six nuclear genes and a telomeric fingerprint probe, the molecular structures of the hybrids were studied. The results demonstrated the occurrence of parasexual events. Hybrids appeared to be diploid or aneuploid, with portions of the genome being heterozygous. A mitochondrial molecular marker indicated homoplasmy of the hybrids and inheritance of mitochondria from strain Bs2 or Bb28. The pathogenicities and the ploidies of the hybrids remained stable after passage through the host insect, showing that somatic hybridization provides an attractive method for the genetic improvement of biocontrol efficiency in the genus Beauveria. 相似文献
150.
Yvonne Widmer 《Biotropica》1998,30(3):400-415
The effect of canopy closure on spatial and morphological patterns of three understory Chusquea species was studied in pristine upper montane oak forests. Plots with either Chusquea talamancenis Widmer & L.G. Clark or C. tomentosa Widmer & L.G. Clark were set out in gaps, under intermediate tree canopy and under closed canopy. The third species Chusquea foliosa L.G. Clark was only found in gap and intermediate canopy sites in the study area. Clumps of all bamboo species tend to be few and large under open conditions and numerous and small under more shady conditions. The larger size of clumps in gaps is reflected in the number of culms per clump, the diameter of the culms and, as a consequence, clump basal area, clump crown area, and biomass (index of plant volume) compared to intermediate and closed canopy. The smaller clump density in gaps compared to closed canopy implies that there is more intraspecific competition and density dependent mortality (self-thinning effect) when a bamboo species is dominant under favourable light conditions. Parameters of performance like culm length, number of nodes per culm, number and length of primary branches, and number of branch nodes seem not to be affected by the light regime, unlike total number of branches, total branch length, and the branching pattern. Species differ in their response to the light environment: C. tomentosa and C. foliosa have a higher degree of morphological plasticity than C. talamancensis, which in turn, appears to be more shade tolerant. No difference between species has been found regarding their contribution to vegetation, parameters reflecting abundance per unit area (site clump area, site crown area and site index of clump volume) were similar for all three species. 相似文献