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PubMed1999

Characterization of the bacterial community of a zinc-polluted soil.

The bacterial community of a zinc-contaminated soil (Maatheide soil in Lommel, Belgium) was studied using cultivation as well as cultivation-independent techniques. Colony-forming units (CFU) were determined by plating on media with or without metals. Dominant isolates were characterized by fatty acid methyl ester analysis (FAME analysis) and PCR fingerprinting using repetitive extragenic palindromic sequences as primers. DNA was directly extracted from soil samples and used as a template for the PCR amplification of the 16S rDNA (8-1511) or a 16S rDNA fragment (968-1401). Clones resulting from cloning the 16S rDNA from soil DNA were sequenced. Temperature gradient gel electrophoresis (TGGE analysis) was performed for 16S rDNA fragments (968-1401) amplified from the dominant isolates, the clones, and the total soil DNA extracted according to two protocols differing in strength of lysis. Total CFU ranged from 10(4) to 10(5)/g soil. The majority of the isolates were identified by FAME analysis as Arthrobacter spp. (18 out of 23). None of the isolates were identified as a Ralstonia eutropha like strain (formerly Alcaligenes eutrophus). Metalloresistant Rastomia eutropha like strains were previously shown to be dominant in the analyzed biotope. Most of the isolates were zinc tolerant but only seven could be considered zinc resistant. Sequences of the 16S rDNA clones obtained from total soil DNA were affiliated with genes of different bacteria such as alpha-proteobacteria, beta-proteobacteria, and the Cytophaga-Flexibacter-Bacteroides group. None of the sequenced clones aligned with the Ralstonia eutropha 16S rRNA gene. TGGE analysis of the 16S rDNA fragments (968-1401) amplified from the dominant strains, the clones, and the total soil DNA showed that isolates and clones represented only a part of the bands present in the TGGE pattern from total DNA. The 968-1401 fragment amplified from all Arthrobacter strains had a similar electrophoretic mobility. This band was seen as a major band in the pattern of DNA extracted from soil using a harsh cell lysis, whereas it did not appear, or appeared only as a weak band, in patterns obtained from soil DNA extracted using gentle lysis. The previously reported predominance of a Ralstonia eutropha like strain in this soil was no longer observed. This may suggest a population replacement by less resistant bacteria, concomitant with a progressive decrease of the zinc toxicity in the Maatheide soil.

Arthrobacter↗

PubMedDate not supplied

Differences in platelet count and size between marrow and peripheral blood.

Automatized platelet parameters were evaluated in 23 unselected patients undergoing a bone marrow examination for diagnostic purposes, both in medullary and in peripheral blood, with the aim of investigating the biological significance of platelet volume heterogeneity. In the marrow blood the platelet count was 10.07 +/- 21.25% (p < 0.05) lower and the platelet volume 7.93 +/- 6.88% (p < 0.001) higher compared to peripheral venous blood: 275,173 +/- 108,079 versus 296,652 +/- 104,814/mm3 (p < 0.05) and 8.93 +/- 1.46 versus 8.23 +/- 1.57 fl (p < 0.001), respectively. The same behavior was observed between the marrow and the arterial blood collected from 12 out of the 23 patients, while no significant difference was observed between arterial and venous blood. The differences observed might be attributable to a platelet population replacement under homeostatical regulation and seem to support the concept that the large platelets are younger elements.

Aged↗

PubMed1983

Meiosis-inhibiting effects in vivo of antiserum to progesterone on follicular ova in immature rats treated with gonadotropins.

Effects of the neutralization of endogenous progesterone with rabbit antiserum to progesterone (anti-progesterone) on germinal vesicle breakdown of ova in follicles of small (less than 125 micrometers), intermediate (125-250 micrometers) and large (greater than 250 micrometers) diameter were examined by a quantitative histological technique. Immature rats were treated with 5 IU pregnant mare's serum gonadotropin (PMS) then with 10 IU human chorionic gonadotropin (hCG). Administration of anti-progesterone together with hCG 6 h later significantly decreased the incidence of germinal vesicle breakdown of ova in the large follicles, but not in the intermediate ones. This treatment did not affect the proportion of intermediate to large follicles in the population. Replacement with progesterone 1 h after the simultaneous injection of hCG and anti-progesterone partly reversed the reduced incidence of meiosis. An injection of rabbit antiserum to estrone, in addition to the replacement with progesterone 1 h after the simultaneous injections of hCG and anti-progesterone, restored the incidence of meiosis to a value comparable to the values found for control rats treated sequentially with PMS and hCG. We concluded that the hCG-induced preovulatory rise in progesterone has a limited but definite stimulatory effect on the resumption of meiosis in the ova of large follicles and that it mediates the meiosis-inducing action of hCG.

Animals↗

PubMed2006

Wolbachia effects on Aedes albopictus (Diptera: Culicidae) immature survivorship and development.

Wolbachia bacteria manipulate the reproduction of mosquito hosts via a form of sterility known as cytoplasmic incompatibility (CI), promoting the spread of infections into host populations. The rate at which an infection invades is affected by host fitness costs associated with the Wolbachia infection. Here, we examine for an effect of Wolbachia infection on the immature fitness of the Asian tiger mosquito Aedes albopictus (Skuse) (Diptera: Culicidae). In two experiments, we examine for a Wolbachia effect on immature survivorship and developmental rate, adult size, and an effect of larval nutrition on CI level. The highest survivorship can be observed in uninfected larvae, primarily because of reduced survivorship of Wolbachia-infected males. Although differences in the developmental rates are observed between the examined strains, the differences cannot be readily attributed to Wolbachia. An effect of Wolbachia on adult size is not observed. Poor male nutrition is associated with reduced fecundity and egg hatch of mates. The latter is hypothesized to explain the reduced egg hatch observed in CI crosses of malnourished males relative to well fed males. We discuss the results in relation to previously identified differences in adult fitness, naturally occurring invasions of Wolbachia, applied strategies of population replacement, and the need for additional modeling effort.

Aedes↗

PubMed1999

Can molecular biology contribute usefully to vector control?

It is argued that further work in molecular entomology should be driven by the practical problems that vector controllers have, not by what molecular biologists can and would like to do. The usefulness is discussed of molecular approaches to (1) insecticide resistance, (2) identification of sibling species, sporozoites and the origin of infections, vector populations and blood meals, (3) genetic control by sterile males or population replacement.

Animals↗

PubMedDate not supplied

Activity, climate, and postcranial robusticity: implications for modern human origins and scenarios of adaptive change.

Postcranial robusticity--the massiveness of the skeleton--figures prominently in the debate over the origin of modern humans. Anthropologists use postcranial robusticity to infer the activity levels of prehistoric populations, and changes in robusticity are often used to support scenarios of adaptive change. These scenarios explain differences in morphology as the result of a change in lifestyle (habitual activity). One common scenario posits that early modern humans were more gracile than Neandertals because the modern humans' complex culture required less physical exertion. However, lifestyle is only one of many influences on morphology. Climate has clear correlations with physique and skeletal proportions. Analysis of recent humans that differ in terms of lifestyle and climatic adaptations reveals that limb bone robusticity varies with climate as much as or more than with lifestyle. Many of the differences in robusticity between Neandertals and early modern humans appear to be related to climatic adaptations. The results support the single-recent origin model of modern human origins. The differences in robusticity between Neandertals and early modern humans suggest that population replacement rather than local evolution best explains the emergence of modern humans in Europe. Both climatic adaptations (primarily body proportions) and lifestyle should be considered in analyses of robusticity.

Activities of Daily Living↗

PubMed1987