Widespread Translocation from Autosomes to Sex Chromosomes Preserves Genetic Variability in an Endangered Lark

Species that pass repeatedly through narrow population bottlenecks (<100 individuals) are likely to have lost a large proportion of their genetic variation. Having genotyped 92 Raso larks Alauda razae, a Critically Endangered single-island endemic whose world population in the Cape Verdes over the last 100 years has fluctuated between about 15 and 130 pairs, we found variation at 7 of 21 microsatellite loci that successfully amplified, the remaining loci being monomorphic. At 6 of the polymorphic loci variation was sex-linked, despite the fact that these microsatellites were not sex-linked in the other passerine birds where they were developed. Comparative analysis strongly suggests that material from several different autosomes has been recently transferred to the sex chromosomes in larks. Sex-linkage might plausibly allow some level of heterozygosity to be maintained, even in the face of persistently small population sizes.     

The control of the form and function of the ribosomes in androgen-dependent tissues by testosterone

1. The ribosome content of the rat ventral prostate gland is controlled by the concentrations of circulating androgens and the polyribosomal complement of the total population of ribosomes is acutely dependent on androgenic stimulation. After the administration of testosterone to castrated rats in vivo, there is a pronounced increase in the amounts of heavy (150-240S) polyribosomes. 2. These results are consistent with a pronounced increase in the mRNA and rRNA content of the prostate gland after the administration of testosterone in vivo. 3. From studies conducted both in vitro, the heavy prostate polyribosomes formed after androgenic stimulation are particularly active in protein synthesis. 4. The androgen-stimulated increase in the formation of prostate polyribosomes has a mandatory requirement for sustained RNA and protein synthesis. 5. Since the androgen-mediated increase in prostate polyribosomes may also be suppressed by the concomitant administration of certain anti-androgenic steroids in vivo, the response in polyribosome formation is probably initiated by the binding of a metabolite of testosterone, 5alpha-dihydrotestosterone, in the prostate gland. 6. The relevance of these findings to the pronounced increase in protein synthesis in androgen-dependent tissues after hormonal stimulation is discussed.     

Bacterial patterning at the three-phase line of contact with microtextured alkanes

Aliphatic crystallites, characteristic of the eicosane and docosane components of naturally occurring lipids, were found to form microtextures that were structured by specific interactions with ordered graphite (HOPG) used as the underlying substratum, as confirmed by scanning electron microscopy (SEM) and fast Fourier transform (FFT) analysis. Confocal scanning laser microscopy (CLSM) showed highly directed bacterial alignment for two bacterial species (spherical and rod-shaped), reflecting the preferential orientation of the crystallite–air–water interfaces to give linear and triangular bacterial patterning. The mechanisms of bacterial attachment are demonstrated in terms of the balance between effective radial adhesional forces and the capillary forces resulting from the water contact angle of the bacteria at the three-phase line (TPL) of the lipid surface. It is suggested that these microtextured surfaces, which exhibit the ability to limit bacterial adhesion to a precise patterning at the lipid TPL, could be used as a means of controlling bacterial colonization.     

Adaptive latitudinal variation in Common Blackbird Turdus merula nest characteristics

Nest construction is taxonomically widespread, yet our understanding of adaptive intraspecific variation in nest design remains poor. Nest characteristics are expected to vary adaptively in response to predictable variation in spring temperatures over large spatial scales, yet such variation in nest design remains largely overlooked, particularly amongst open‐cup‐nesting birds. Here, we systematically examined the effects of latitudinal variation in spring temperatures and precipitation on the morphology, volume, composition, and insulatory properties of open‐cup‐nesting Common Blackbirds’ Turdus merula nests to test the hypothesis that birds living in cooler environments at more northerly latitudes would build better insulated nests than conspecifics living in warmer environments at more southerly latitudes. As spring temperatures increased with decreasing latitude, the external diameter of nests decreased. However, as nest wall thickness also decreased, there was no variation in the diameter of the internal nest cups. Only the mass of dry grasses within nests decreased with warmer temperatures at lower latitudes. The insulatory properties of nests declined with warmer temperatures at lower latitudes and nests containing greater amounts of dry grasses had higher insulatory properties. The insulatory properties of nests decreased with warmer temperatures at lower latitudes, via changes in morphology (wall thickness) and composition (dry grasses). Meanwhile, spring precipitation did not vary with latitude, and none of the nest characteristics varied with spring precipitation. This suggests that Common Blackbirds nesting at higher latitudes were building nests with thicker walls in order to counteract the cooler temperatures. We have provided evidence that the nest construction behavior of open‐cup‐nesting birds systematically varies in response to large‐scale spatial variation in spring temperatures.     

Further studies on the stimulation of protein synthesis in androgen-dependent tissues by testosterone

1. By using centrifugation through a discontinuous sucrose gradient, four microsomal fractions are obtained from the prostate gland. 2. Administration of androgens to castrated rats stimulates protein synthesis in all fractions, particularly in the heavy rough fraction. 3. Androgens also increase the content of protein, RNA and phospholipid in the heavy rough fraction. 4. Time-course experiments in vivo show that androgens induce a rapid increase in the synthesis of ribosomal precursor RNA preceding the synthesis of new microsomal fraction and the increase in protein synthesis.     

Life history correlates of fecal bacterial species richness in a wild population of the blue tit Cyanistes caeruleus

Very little is known about the normal gastrointestinal flora of wild birds, or how it might affect or reflect the host's life‐history traits. The aim of this study was to survey the species richness of bacteria in the feces of a wild population of blue tits Cyanistes caeruleus and to explore the relationships between bacterial species richness and various life‐history traits, such as age, sex, and reproductive success. Using PCR‐TGGE, 55 operational taxonomic units (OTUs) were identified in blue tit feces. DNA sequencing revealed that the 16S rRNA gene was amplified from a diverse range of bacteria, including those that shared closest homology with Bacillus licheniformis, Campylobacter lari, Pseudomonas spp., and Salmonella spp. For adults, there was a significant negative relationship between bacterial species richness and the likelihood of being detected alive the following breeding season; bacterial richness was consistent across years but declined through the breeding season; and breeding pairs had significantly more similar bacterial richness than expected by chance alone. Reduced adult survival was correlated with the presence of an OTU most closely resembling C. lari; enhanced adult survival was associated with an OTU most similar to Arthrobacter spp. For nestlings, there was no significant change in bacterial species richness between the first and second week after hatching, and nestlings sharing the same nest had significantly more similar bacterial richness. Collectively, these results provide compelling evidence that bacterial species richness was associated with several aspects of the life history of their hosts.     

The dissociation of the extracellular hemoglobin of Lumbricus terrestris at acid pH and its reassociation at neutral pH. A new model of its quaternary structure

Lumbricus terrestris HbO2 and HbCO dissociated below pH 5.0; a time-dependent alteration to the met form occurred at pH less than 5 and pH less than 4.5, respectively. The extent of dissociation was unaffected by alkaline earth cations but was decreased by an increase in ionic strength. HbO2 and HbCO exposed to pH 4.0-4.8 were centrifuged to obtain the undissociated pellet (P1) and dissociated supernatant (S1) fractions. S1 was reassociated at pH 7.0 by dialysis against various buffers and then centrifuged to obtain the reassociated pellet (P2) and unreassociated supernatant (S2) fractions. Reassociation was possible only if S1 was dialyzed against water prior to return to neutral pH; otherwise precipitation occurred starting at about pH 5.3. The extent of reassociation varied from about 40 to 80%, was usually higher for HbCO than HbO2, and was unaffected by an increase in ionic strength or by Ca(II). Gel filtration of P2 on Sephacryl S-300 at neutral pH gave one peak IaR, eluting at a slightly greater volume than the native Hb; S1 and S2 gave in addition, three peaks, Ib (200 kDa), II (65 kDa), and III (18 kDa). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that P2 was slightly deficient in subunit M relative to the Hb, that Ib was deficient in subunits D1 and D2 and that II and III consisted of subunits D1 + D2 + T and subunit M, respectively. Scanning transmission electron microscopy of P2 showed that it was smaller than the native hemoglobin: 25 nm in diameter and 16 nm in height, instead of 30 X 20 nm. Comparison of the results of the dissociations of Lumbricus Hb at alkaline pH (Kapp, O. H., Polidori, G., Mainwaring, M., Crewe, A. V., Vinogradov, S. N. (1984) J. Biol. Chem. 259, 628-639) with those obtained in this study suggested that the Hb quaternary structure was not multimeric and that an alternative model had to be considered. In the proposed model it is assumed that subunits D1 and D2 form a scaffolding or "bracelet," decorated with 12 complexes of M and T subunits.     

The carboxylic acid reduction pathway in Nocardia. Purification and characterization of the aldehyde reductase

Whole cultures of Nocardia sp. NRRL 5646 reduce carboxylic acids, first to aldehydes, then to alcohols and subsequently to the corresponding acetyl esters. This work describes an NADPH-dependent reductase responsible for catalyzing the reduction of aldehyde intermediates, which was purified 3240-fold by a combination of Mono-Q, hydroxyapatite, and ADP-agarose chromatographies. By sodium dodecyl sulfate–polyacrylamide gel electrophoresis, the purified enzyme ran as a single band of 47 kDa. A native molecular mass estimated at 101 kDa indicated that the enzyme was a homodimer in the native, active state. Edman degradation indicated a unique N-terminal sequence as NH₂-X-X-Ala-Ala-Ala-Tyr-Ala-Val-Pro-Ala-Pro-Asp-Gly-Cys-Phe-Glu-Lys-Val-Thr-Ile-Glu-Arg-Arg-Glu-Leu-Gly. The enzyme catalyzed reductions of many aryl- and alkyl-aldehyde substrates. Reactions were most favorable in the direction of aldehyde reduction to alcohols. Journal of Industrial Microbiology & Biotechnology (2000) 25, 328–332. Received 08 May 2000/ Accepted in revised form 20 October 2000     

Health status in COPD cannot be measured by the St George's Respiratory Questionnaire alone: an evaluation of the underlying concepts of this questionnaire

Background

The definition of "clinical asthma remission" is based on absence of symptoms and use of medication. However, in the majority of these subjects airway inflammation is still present when measured. In the present study we investigated whether "complete asthma remission", additionally defined by the absence of bronchial hyperresponsiveness (BHR) and the presence of a normal lung function, is associated with the absence of airway inflammation.

Methods

Patients with a former diagnosis of asthma and a positive histamine provocation test were re-examined to identify subjects with complete asthma remission (no asthma symptoms or medication, PC₂₀ histamine > 32 mg/ml, FEV₁ > 90% predicted). Patients with PC₂₀ histamine ≤ 32 mg/ml were defined as current asthmatics and were divided in two groups, i.e. asthmatics with and without BHR to adenosine 5'monophoshate (AMP). Sputum induction was performed 1 week before and 1 hour after AMP provocation. Sputum induction and AMP provocation were previously shown to be sensitive markers of airway inflammation.

Results

Seven patients met criteria for complete asthma remission. Twenty-three were current asthmatics, including twelve without hyperresponsiveness to AMP. Subjects with complete asthma remission showed no AMP-induced sputum eosinophilia (median (range) 0.2 (0 - 4.6)% at baseline and 0.2 (0 - 2.6)% after AMP). After AMP, current asthmatics had a significant increase in sputum eosinophils (0.5 (0 - 26.0)% at baseline and 2.6 (0 - 32.0) % after AMP), as had the subgroup of current asthmatics without hyperresponsiveness to AMP (0.2 (0 - 1.8)% at baseline and 1.3 (0 - 6.3)% after AMP).

Conclusions

Subjects with complete asthma remission, in contrast to subjects with current asthma, do not respond with eosinophilic inflammation in sputum after AMP provocations. These data lend support to the usefulness of the definition of complete asthma remission.     

Gene selection algorithms for microarray data based on least squares support vector machine

Background  

In discriminant analysis of microarray data, usually a small number of samples are expressed by a large number of genes. It is not only difficult but also unnecessary to conduct the discriminant analysis with all the genes. Hence, gene selection is usually performed to select important genes.