Externally attached radio transmitters do not affect the parental care behaviour of rock bass

Turning, pectoral fin and caudal fin rates and time spent on the nest of male rock bass Ambloplites rupestris , engaged in parental care, were not affected after the attachment of external radio transmitters. Reproductive success was similar between treatment and control fish. Micro external radio transmitters can be used on small fishes for studying parental care duration and post-care movement without altering their behaviour.     

Marine incursions,cryptic species and ecological diversification in Amazonia: the biogeographic history of the croaker genus Plagioscion (Sciaenidae)

Aim We propose a phylogenetic hypothesis for the marine‐derived sciaenid genus Plagioscion in the context of geomorphology and adaptation to freshwaters of South America, and assess the extent to which contemporary freshwater hydrochemical gradients influence diversification within a widely distributed Plagioscion species, Plagioscion squamosissimus. Location Amazon Basin and South America. Methods Using nuclear and mitochondrial DNA sequence data, phylogenetic analyses were conducted on the five nominal Plagioscion species, together with representatives from Pachyurus and Pachypops, using character and model‐based methods. Genealogical relationships and population genetic structure of 152 P. squamosissimus specimens sampled from the five major rivers and three hydrochemical settings/‘colours’ (i.e. white, black and clear water) of the Amazon Basin were assessed. Results Phylogenetic analyses support the monophyly of Plagioscion in South America and identify two putative cryptic species of Plagioscion. Divergence estimates suggest that the Plagioscion ancestor invaded South America via a northern route during the late Oligocene to early Miocene. Within P. squamosissimus a strong association of haplotype and water colour was observed, together with significant population structure detected between water colours. Main conclusions Our analyses of Plagioscion are consistent with a biogeographic scenario of early Miocene marine incursions into South America. Based on our phylogenetic results, the fossil record, geomorphological history and distributional data of extant Plagioscion species, we propose that marine incursions into western Venezuela between the late Oligocene and early Miocene were responsible for the adaptation to freshwaters in Plagioscion species. Following the termination of the marine incursions during the late Miocene and the establishment of the modern Amazon River, Plagioscion experienced a rapid diversification. Plagioscion squamosissimus arose during that time. The formation of the Amazon River probably facilitated population and range expansions for this species. Further, the large‐scale hydrochemical gradients within the Amazon Basin appear to be acting as ecological barriers maintaining population discontinuities in P. squamosissimus even in the face of gene flow. Our results highlight the importance of divergent natural selection through time in the generation and maintenance of sciaenid diversity in Amazonia.     

The effects of diethyl-4-methyl-3-oxo-4-aza-5 alpha-androstane-17 beta-carboxamide (4-MA) and (4R)-5,10-SECO-19-norpregna-4,5-diene-3,10,20-trione (SECO) on androgen biosynthesis in the rat testis and epididymis

We have investigated the effects of two 4-ene-steroid 5 alpha-reductase inhibitors, diethyl-4-methyl-3-oxo-4-aza-5 alpha-androstane-17 beta-carboxamide (4-MA) and (4R)-5,10-seco-19-norpregna-4, 5-diene-3,10,20-trione (SECO), on testicular and epididymal androgen biosynthesis. Kinetic analyses revealed that both compounds inhibited epididymal DHT biosynthesis. 4-MA was a competitive inhibitor of epididymal nuclear and microsomal 4-ene-steroid 5 alpha-reductases (3-oxo-5 alpha-steroid: NADP 4-ene-oxidoreductase EC 1.3.1.22) with Kiapp values of 12.8 and 15.1 nmol/l compared to the respective Kmapp values of 185 and 240 nmol/l. Values for the Vmaxapp were always within 70-130% of the control. SECO at 1.0 mumol/l, also inhibited epididymal nuclear and microsomal 4-ene-steroid-5 alpha-reductases, causing respectively 2.9 and 5.2-fold increases in Kmapp. The Vmaxapp values were unchanged. However, SECO concentrations of 5 and 25 mumol/l abolished 4-ene-steroid 5 alpha-reductase activity at all testosterone concentrations. To examine the specificity of these compounds, we investigated their effects on the enzymes that convert pregnenolone to testosterone. Rat testis microsomes converted pregnenolone to testosterone via the 4-ene-3-oxo pathway, with the major metabolites being progesterone, 17-hydroxyprogesterone, 4-androstenedione and testosterone; some 17-hydroxypregnenolone was also formed. Very small amounts of dehydroepiandrosterone (DHA) and 5-androstenediol were detected. SECO, at a concentration that completely inhibited epididymal 4-ene-steroid 5 alpha-reductase activity, did not alter the metabolic profile of pregnenolone metabolism. However, 4-MA prevented the appearance of 4-ene steroids, and large quantities of 17-hydroxypregnenolone and DHA accumulated, suggesting that inhibition of the 3 beta-hydroxysteroid: NAD(P)+ oxidoreductase (EC 1.1.1.51) and 3-oxosteroid 5-ene-4-ene-isomerase (EC 5.3.3.1) [3 beta-hydroxysteroid dehydrogenase-isomerase] was occurring. Optimal conditions for the microsomal conversion of DHA to 4-androstenedione were determined; kinetic analyses of the 3 beta-hydroxysteroid dehydrogenase-isomerase activity revealed that 4-MA inhibited this reaction non-competitively, reducing Vmaxapp values to 25% of the control. The Kiapp determined from the intercept replot, was 121 nmol/l, and the Kmapp was always between 90 and 130% of the control value. It is concluded that SECO is more specific than 4-MA in its effects on androgen biosynthesis in the testis and epididymis and that both these drugs should provide useful tools in assessments of the relative contributions of 5 alpha-reduced androgens to androgen dependent processes.     

Proteins of the inner and outer centromere of mitotic chromosomes

We have used immunocytochemistry and molecular cloning methods to identify and characterize structural polypeptides of the centromere. These studies permit us to resolve two distinct regions: the inner and outer centromere. (i) Components of the outer centromere: autoantibodies from certain patients with rheumatic disease identify a family of three immunologically related polypeptides that we have designated CENP-A (17 kDa), CENP-B (80 kDa), and CENP-C (140 kDa). CENP-B has been cloned and sequenced. DNA sequence analysis indicates that this polypeptide possesses two large regions with extraordinary concentrations of acidic residues (region I: 61 residues with 79% glu + asp; region II: 31 residues with 87% glu + asp). Despite this concentration of negative charge, immunocytochemical experiments suggest that CENP-B may be a DNA binding protein. In these experiments, the levels of CENP-B are seen to vary reproducibly from chromosome to chromosome. The role of CENP-B in vivo is unknown. However, it is unlikely to bind directly to the spindle microtubules since it is found at an inactive centromere that apparently does not attach to the spindle. (ii) Components of the inner centromere: we have injected mice with the whole chromosome scaffold fraction to elicit production of monoclonal antibodies. One such antibody identifies two structurally related polypeptides (the INCENP antigens, 135 and 155 kDa) that are preferentially located between the sister chromatids at the centromere. The INCENP antigens undergo dramatic movements from the chromosomes to the central spindle during mitosis. They are ultimately sequestered in the midbody and discarded. Several lines of evidence suggest that the INCENP polypeptides may be involved in the regulation of sister chromatid separation at the metaphase-anaphase transition.     

Structure-function analysis of epidermal growth factor: site directed mutagenesis and nuclear magnetic resonance

The role of leucine-47 in determining the structure and activity of human epidermal growth factor was examined using site-directed mutagenesis. Wild type protein and four variants in which Leu47 was replaced by valine, glutamate, aspartate and alanine were produced from yeast. 1H NMR experiments demonstrated that substitution of Leu47 had little effect on the protein structure. The observed reduction in receptor binding affinity caused by the substitutions could thus be attributed to perturbation of a residue directly involved in receptor interactions.     

Control of infection in general practice: a survey and recommendations.

Twenty general practices in four areas in Britain were surveyed to establish their needs for and practices of sterilising and disinfecting equipment. Of the 327 items of equipment and instruments examined in the survey, 190 were satisfactorily decontaminated, 100 were treated in a way judged to result in doubtful decontamination, and in 37 cases treatment was considered unsatisfactory. Decontamination apparatuses (autoclaves, hot air ovens, and hot water disinfectors) were generally in good working order, but the use of chemical disinfectants was often inappropriate. Recommendations were made on appropriate methods of decontamination for various items in common use in general practice. By virtue of the large numbers of patients treated by general practitioners there is a substantial possibility of transmitting infection; having appropriate methods for decontaminating instruments and equipment is therefore imperative.     

Characteristics of newt breeding sites

Breeding site characteristics have been studied for the three species of newt that occur in Britain, the Palmate ( Triturus helveticus (Razoumowski)), Smooth ( T. vulgaris (L.)) and Warty ( T. cristatus (Laurenti)). The Warty newt was seldom found in the absence of the much commoner Smooth newt, but seemed to prefer sites that were relatively large and deep and that had a high proportion of open water surface. All three species tended to breed in ponds having abundant aquatic vegetation. Smooth newts, unlike Palmate newts, were rarely encountered in water with pH <6. The Smooth newt tended to be found in water with relatively high concentrations of metals, while the reverse was true for the Palmate newt. Over Britain, Smooth and Warty newts are relatively less common in soft water areas, while the Palmate is less common in hard water areas. Possible reasons for these associations are discussed.