Life-history variations of the Lesser Sheathbill Chionis minor in contrasting habitats

From 1987 until 1995, life-history traits of the Lesser Sheathbill Chionis minor in the Kerguelen Archipelago were compared with those at other localities, where this species breeds in seabird colonies. At Kerguelen Island only, some pairs breed on shores free of penguin and cormorant colonies. Moreover, pairs, including nonbreeders, and solitary individuals maintain territories all the year round. Site and mate changes were not linked, and all divorces were permanent. Fidelity rates were similar in all localities and so were the annual survival rates of adults. The survival rate of immature individuals was highest at Kerguelen Island, where sheathbills laid smaller clutches, produced fewer fledglings and had lower breeding success than in the other islands. At Kerguelen Island, pairs breeding on shores had similar clutch sizes but fledged fewer offspring than those breeding in seabird colonies. Further, the proportion of vacant territories and nonbreeders was higher on shores. Kerguelen sheathbills devoted less time to food acquisition than those on Marion Island, being exceptionally kleptoparasitic, and spent a smaller part of their foraging time exploiting seabird colonies. Their diet was mainly algae. The differences on Kerguelen Island as compared with other localities were caused by the presence of an extensive intertidal zone on the former, which reduced competition, making many more sites suitable and the environment more predictable. These life-history and behavioural traits are discussed in relation to life-history theory. As differences were also found, although less extensive, within the Kerguelen Archipelago, we suggest that some traits represent an adaptive response to external constraints and that the life-history strategy of the Lesser Sheathbill is particularly opportunistic.     

Isozyme analysis of Galaxias species (Teleostei: Galaxiidae) from the Taieri River, South Island, New Zealand: a species complex revealed

We examined genetic differentiation among 23 samples of non-migratory river galaxias from 17 streams in the Taieri River system, South Island, New Zealand. Four major genetic types were found, two of which occur in narrow sympatry in one location. These were compared with topotypical material representing Galaxias anomalus from the Clutha system (Otago) and G. vulgaris from the Waimakariri system (Canterbury) in order to establish identity. Morphological examination of these four major genetic types revealed consistent concomitant differences. The results suggest that there are at least three species of river galaxias in the Taieri system: G. anomalus, G. vulgaris and at least one previously undescribed species. We propose that the genetic structuring and subsequent speciation of this group has been promoted by the absence of the marine juvenile phase that is found in five other members of the genus native to New Zealand. This structuring may be exacerbated by population fragmentation over the last century owing to the negative influence of introduced trout. The phylogenetic diversity within the river system mirrors the diverse flora and invertebrate fauna of the region, and has conservation implications that parallel those resulting from our improved knowledge of the New Zealand herpetofauna through the application of genetic analysis.     

Linkage disequilibrium and extended haplotypes in the HLA-A to D6S105 region: implications for mapping the hemochromatosis gene (HFE)

The hemochromatosis gene (HFE) maps to 6p21.3, in close linkage with the HLA Class I genes. Linkage disequilibrium (LD) studies were designed to narrow down the most likely candidate region for HFE, as an alternative to traditional linkage analysis. However, both the HLA-A and D6S105 subregions, which are situated 2–3 cM and approximately 3 Mb apart, have been suggested to contain HFE. The present report extends our previous study based upon the analysis of a large number of HFE and normal chromosomes from 66families of Breton ancestry. In addition to the previously used RFLP markers spanning the 400-kb surrounding HLA-A, we examined three microsatellites: D6S510, HLA-F, and D6S105. Our combined data not only confirm a peak of LD at D6S105, but also reveal a complex pattern of LD over the i82 to D6S105 interval. Within our ethnically well-defined population of Brittany, the association of HFE with D6S105 is as great as that with HLA-A, while the internal markers display a lower LD. Fine haplotype analysis enabled us to identify two categories of haplotypes segregating with HFE. In contrast to the vast majority of normal haplotypes, 50% of HFE haplotypes are completely conserved over the HLA-A to D6S105 interval. These haplotypes could have been conserved through recombination suppression, selective forces and/or other evolutionary factors. This particular haplotypic configuration might account for the apparent inconsistencies between genetic linkage and LD data, and additionally greatly complicates positional cloning of HFE through disequilibrium mapping.The authors contributed equally to this work     

Cartographic study: Breakpoints in 1574 families carrying human reciprocal translocations

Reciprocal translocations (rcp) are among the most common constitutional chromosomal aberrations in man. Using a European database of 1574 families carrying autosomal rcp, a cartographic study was done on the breakpoints involved. The breakpoints are non-randomly distributed along the different chromosomes, indicating “hot spots”. Breakpoints of rcp that result in descendants that are unbalanced chromosomally at birth are more frequent in a distal position on chromosomal arms, and 65% of them are localised in R-bands. Among the R-bands, bands rich in GC islands and poor in Alu repetitive sequences are more frequently the site of breakpoints, as well as bands that include a fragile site. This result suggests that the variation in degree of methylation in GC islands could be involved in chromosomal breakage and hence in chromosomal rearrangements. Received: 10 April 1995 / Revised: 1 July 1995     

Identification and characterization of three genes and two pseudogenes on chromosome 13

A study was conducted on the feasibility of isolating genes and pseudogenes that map to chromosome 13 by a hybridization-based approach using a 13-specific library and pools of repeat-free cDNA clones. Five pairs of cDNA and chromosome 13 genomic clones were identified and characterized. Partial or full-length sequence was derived from all cDNAs, and database searches were performed for putative gene identification. Partial sequence was also obtained from the chromosome 13 genomic clones for comparison with those of the hybridizing cDNAs. As a result of these analyses we identified three genes, a putative homologue of a porcine mRNA encoding an unidentified hepatic protein, a putative homologue of a yeast integral membrane protein, and a gene for a translationally controlled tumor protein, and two processed pseudogenes, ribosomal proteins L23a and S3a. The latter was formerly identified as the v-fos transformation effector gene, Fte-1, and recently cited as a possible candidate for the BRCA2 gene on chromosome 13. All genes and pseudogenes were localized to cytogenetic bands by in situ hybridization of metaphase chromosomes with probes derived from the chromosome 13 genomic clones.     

Origin of cholesterol in myelin

We review some of the older literature concerning metabolic turnover of cholesterol in the nervous system. The overall picture is that incorporation of radioactive precursors into brain cholesterol is roughly proportional to the rate of myelination and that, once incorporated, radioactive cholesterol is relatively stable metabolically. We outline a strategy for demonstrating the source (local synthesis or uptake from the circulation) of cholesterol in brain. The experimental design involves determining the rate of accumulation of cholesterol this is calculated as the increasing amounts of sterol in brain at successive time intervals during development. The rate of appearance of newly synthesized cholesterol is determined from incorporation of radioactivity from³H₂O (injected i.p. several hours prior to sacrifice) into cholesterol. The radioactivity associated with the sterol fractions and the specific activity of body water determined from the serum can be used to calculate the absolute amount of sterol newly synthesized during the time when³H₂O was present. The results obtained demonstrated that all of the bulk cholesterol accumulating in brain can be accounted for by newly synthesized cholesterol. None of the radioactive cholesterol came from the circulation, since cholesterol feeding suppressed cholesterol biosynthesis in the liver and specific radioactivity of circulating cholesterol was negligible. Thus, almost all cholesterol accumulating in brain during development is locally synthesized. Special issue dedicated to Dr. Marion R. Smith.     

A proenkephalin A-derived peptide analogous to bovine adrenal peptide E from frog brain: Purification, synthesis, and behavioral effects

A peptide derived from the posttranslational processing of proenkephalin A was isolated from an extract of the brain of the European green frog Rana ridibunda and its primary structure established as: Tyr-Gly-Gly-Phe-Met-Arg-Arg-Val-Gly-Arg¹⁰-Pro-Glu-Trp-Trp-Gln-Asp-Tyr-Gln-Lys-Arg²⁰-Tyr-Gly-Gly-Phe-Met. The structure was confirmed by chemical synthesis. The peptide represents an amphibian equivalent of bovine adrenal peptide E [preproenkephalin A (206–230)-peptide] but the sequence contains two amino acid substitutions (Met¹⁵ → Gln and Leu²⁵ → Met) compared with the mammalian peptide. The data support previous hypotheses that the Leu-enkephalin sequence is not present in preproenkephalin A of amphibians. Intracerebroventricular injections of frog peptide E (10 and 100 ng) in mice had no significant effect on horizontal locomotor activity. The peptide, in doses up to 1 μg, had no effect on latency of escape jumping in the hot plate test and the peptide (100 ng) did not modify responses (paw licking, rearing, and escape jumping) in morphine-treated mice.     

Gluconate production by spores of Aspergillus niger

Spores of Aspergillus niger obtained by solid state fermentation on buckwheat seeds produced gluconic acid from glucose with a high yield, near 1.06 g gluconic acid/g glucose, close to the stoichiometric value. The reaction itself could be carried out either with purified biocatalyst or with the whole buckwheat medium resulting from spore production process. 200 g gluconic acid/L were obtained in 200 h with sequential feedings of glucose up to 190 g/L.     

Plasma and erythrocyte manganese concentrations

This study was carried out to assess manganese (Mn) status after an acute episode of myocardial infarction. Plasma and erythrocyte Mn concentrations were measured from admission to hospital to day 15 postadmission in 21 patients suffering from acute myocardial infarction and in three control groups. The determination of Mn in these biological fluids was performed by electrothermal atomic absorption spectrometry. Plasma Mn was higher (p<0.01) and erythrocyte Mn was similar in the acute myocardial infarction group compared to healthy age-matched control group. Plasma and erythrocyte Mn remained unchanged during the 2 wk after acute myocardial infarction and were not correlated to enzyme activities. A decrease of erythrocyte Mn with age, expressed in nmol/L, was noted (p<0.02). These results suggest that plasma and erythrocyte Mn do not provide an indication of myocardial damage. Nonetheless, Mn status in elderly merits further attention.     

A redescription ofLepidauchen stenostoma Nicoll, 1913 (Digenea), and a reassessment of the status of the genusLepidauchen Nicoll, 1913

The genusLepidauchen is discussed and defined. It is removed from the family Lepocreadiidae and placed in the family Acanthocolpidae based mainly on its possession of a uterine seminal receptacle. The type, and only valid species,L. stenostoma, is redescribed using material fromLabrus merula from Corsica. Material fromCoris julis andSymphodus tinca from the western Mediterranean off Marseille,L. merula from the western Mediterranean off Valencia,Diplodus annularis andLithognathus mormyrus from the Adriatic Sea off Montenegro, andArchosargus unimaculatus from Venezuela was also examined. Other nominal species are discussed, but none are considered valid within this genus.