Genetic distinction between contiguous urban and rural multimammate mice in Tanzania despite gene flow.

Special conditions are required for genetic differentiation to arise at a local geographical scale in the face of gene flow. The Natal multimammate mouse, Mastomys natalensis, is the most widely distributed and abundant rodent in sub-Saharan Africa. A notorious agricultural pest and a natural host for many zoonotic diseases, it can live in close proximity to humans and appears to compete with other rodents for the synanthropic niche. We surveyed its population genetic structure across a 180-km transect in central Tanzania along which the landscape varied between agricultural land in a rural setting and natural woody vegetation, rivers, roads and a city (Morogoro). We sampled M. natalensis across 10 localities and genotyped 15 microsatellite loci from 515 individuals. Hierarchical STRUCTURE analyses show a K-invariant pattern distinguishing Morogoro suburbs (located in the centre of the transect) from nine surrounding rural localities. Landscape connectivity analyses in Circuitscape and comparison of rainfall patterns suggest that neither geographical isolation nor natural breeding asynchrony could explain the genetic differentiation of the urban population. Using the isolation-with-migration model implemented in IMa2, we inferred that a split between suburban and rural populations would have occurred recently (<150 years ago) with higher urban effective population density consistent with an urban source to rural sink of effective migration. The observed genetic differentiation of urban multimammate mice is striking given the uninterrupted distribution of the animal throughout the landscape and the high estimates of effective migration (2Ne M = 3.0 and 29.7), suggesting a strong selection gradient across the urban boundary.

The homogenous alternative to biomineralization: Zn- and Mn-rich materials enable sharp organismal "tools" that reduce force requirements.

We measured hardness, modulus of elasticity, and, for the first time, loss tangent, energy of fracture, abrasion resistance, and impact resistance of zinc- and manganese-enriched materials from fangs, stings and other "tools" of an ant, spider, scorpion and nereid worm. The mechanical properties of the Zn- and Mn-materials tended to cluster together between plain and biomineralized "tool" materials, with the hardness reaching, and most abrasion resistance values exceeding, those of calcified salmon teeth and crab claws. Atom probe tomography indicated that Zn was distributed homogeneously on a nanometer scale and likely bound as individual atoms to more than » of the protein residues in ant mandibular teeth. This homogeneity appears to enable sharper, more precisely sculpted "tools" than materials with biomineral inclusions do, and also eliminates interfaces with the inclusions that could be susceptible to fracture. Based on contact mechanics and simplified models, we hypothesize that, relative to plain materials, the higher elastic modulus, hardness and abrasion resistance minimize temporary or permanent tool blunting, resulting in a roughly 2/3 reduction in the force, energy, and muscle mass required to initiate puncture of stiff materials, and even greater force reductions when the cumulative effects of abrasion are considered. We suggest that the sharpness-related force reductions lead to significant energy savings, and can also enable organisms, especially smaller ones, to puncture, cut, and grasp objects that would not be accessible with plain or biomineralized "tools".

Human dietary exposure to chemicals in sub-Saharan Africa: safety assessment through a total diet study.

BACKGROUND: Human dietary exposure to chemicals can result in a wide range of adverse health effects. Some substances might cause non-communicable diseases, including cancer and coronary heart diseases, and could be nephrotoxic. Food is the main human exposure route for many chemicals. We aimed to assess human dietary exposure to a wide range of food chemicals. METHODS: We did a total diet study in Benin, Cameroon, Mali, and Nigeria. We assessed 4020 representative samples of foods, prepared as consumed, which covered more than 90% of the diet of 7291 households from eight study centres. By combining representative dietary surveys of countries with findings for concentrations of 872 chemicals in foods, we characterised human dietary exposure. FINDINGS: Exposure to lead could result in increases in adult blood pressure up to 2·0 mm Hg, whereas children might lose 8·8-13·3 IQ points (95th percentile in Kano, Nigeria). Morbidity factors caused by coexposure to aflatoxin B1 and hepatitis B virus, and sterigmatocystin and fumonisins, suggest several thousands of additional liver cancer cases per year, and a substantial contribution to the burden of chronic malnutrition in childhood. Exposure to 13 polycyclic aromatic hydrocarbons from consumption of smoked fish and edible oils exceeded levels associated with possible carcinogenicity and genotoxicity health concerns in all study centres. Exposure to aluminium, ochratoxin A, and citrinin indicated a public health concern about nephropathies. From 470 pesticides tested across the four countries, only high concentrations of chlorpyrifos in smoked fish (unauthorised practice identified in Mali) could pose a human health risk. INTERPRETATION: Risks characterised by this total diet study underscore specific priorities in terms of food safety management in sub-Saharan Africa. Similar investigations specifically targeting children are crucially needed. FUNDING: Standards and Trade Development Facility.

Methodology design of the regional Sub-Saharan Africa Total Diet Study in Benin, Cameroon, Mali and Nigeria.

The core food model was described more than three decades ago, and has been used ever since to identify main food contributors to dietary intakes for both nutrients and other food chemicals. The Sub-Saharan Africa Total Diet Study (SSA-TDS) uses this model to describe the food consumption habits of some selected populations of Benin, Cameroon, Mali, and Nigeria, prior to use in the completion of quantitative risk assessments with regard to food chemicals. Food consumption data were derived from food expenditure data contained in national household budget surveys that were provided by the national institutes of statistics in each country. A classification of African foods was established for the purpose of the study and core foods were selected, so as to reflect 96 ± 1% of the average national total diet expressed in weight. Populations from eight study centers were selected by national stakeholders. This approach involves the purchase of 4020 individual foods, prepared as consumed and pooled into 335 food composite samples, for analysis of mycotoxins, PAHs, PCBs and dioxins, pesticides, metals and trace elements, PFAs, and BFRs. This sampling plan aims to provide a representative, cost effective, and replicable approach for deterministic dietary exposure assessments in developing countries.

Pepsin immobilized by covalent fixation to hydroxyalkyl methacrylate gels: preparation and characterization.

Insoluble active derivatives of pepsin (EC 3.4.23.1) were prepared by covalent binding of this enzyme to hydroxyalkyl methacrylate gels modified with 1,6-diaminohexane or epsilon-aminocaproic acid in an acid medium by means of water-soluble carbodiimide. The amount of attached enzyme, its proteolytic activity, pH activity curves of the preparations obtained and the time and pH dependence of their stability were determined.

Association interaction and voltammetric determination of 1-aminopyrene and 1-hydroxypyrene at cyclodextrin and DNA based electrochemical sensors.

The aim of this work was voltammetric determination of 1-aminopyrene and 1-hydroxypyrene using carbon paste electrodes modified with cyclodextrin derivatives and double stranded deoxyribonucleic acid (dsDNA). The detection schemes based on a preconcentration and differential pulse voltammetric (DPV) determination at beta-cyclodextrin and gamma-cyclodextrin modified carbon paste electrode (beta-CD/CPE, gamma-CD/CPE), neutral beta-cyclodextrin polymer and carboxymethyl-beta-cyclodextrin polymer modified screen-printed electrode (beta-CDP/SPE, beta-CDPA/SPE) and dsDNA modified screen-printed electrode (DNA/SPE) are proposed for the trace determination of studied analytes within the concentration range from 2 x 10(-8) to 4 x 10(-7) mol dm(-3) and from 2 x 10(-7) to 4 x 10(-6) mol dm(-3) with the limits of quantification down to 10(-8) mol dm(-3). Depending on pH, 1-aminopyrene interacts with both surface attached CD and DNA by electrostatic bonds and supramolecular complexation while 1-hydroxypyrene associates with the CD hosts via complexation. The 1-aminopyrene interaction with dsDNA was confirmed by fluorimetric measurements in the solution phase using a competing DNA-TO-PRO-3 dye complex. In addition, the effect of temperature on this association was investigated using an electrically heated DNA-modified carbon paste electrode (DNA/CPE).

The mammalian model for population studies of B chromosomes: the wood mouse (Apodemus).

The presence of B chromosomes was reported in six species of the genus Apodemus (A. peninsulae, A. agrarius, A. sylvaticus, A. flavicollis, A. mystacinus, A. argenteus). High frequencies of Bs were recorded particularly in A. peninsulae and A. flavicollis. The origin of Bs in Apodemus seems to be rather ancient, and it is possible that the supernumerary elements, and/or a tendency for their appearance, were inherited from the common ancestor of the extant species. We have not found any correlated changes between frequencies of Bs and the level of protein polymorphism and/or heterozygosity assessed in electrophoretic studies. No measurable effect of Bs on overall genetic variability was thus revealed in studied populations. The pattern of evolutionary dynamics of Bs can be distinctly different between geographical populations, and both the parasitic and the heterotic models can be applied to explain the maintenance of Bs in different populations. Further studies are desirable to improve our understanding of the complicated evolutionary dynamics of Bs in the Apodemus species. An essential condition for success in this respect is much more detailed information on inheritance and the molecular structure of Bs.

Mediterranean Europe as an area of endemism for small mammals rather than a source for northwards postglacial colonization.

There is a general perception that central and northern Europe were colonized by range expansion from Mediterranean refugia at the end of the last glaciation. Data from various species support this scenario, but we question its universality. Our mitochondrial DNA studies on three widespread species of small mammal suggest that colonization may have occurred from glacial refugia in central Europe-western Asia. The haplotypes on the Mediterranean peninsulae are distinctive from those found elsewhere. Rather than contributing to the postglacial colonization of Europe, Mediterranean populations of widespread small mammals may represent long-term isolates undergoing allopatric speciation. This could explain the high endemism of small mammals associated with the Mediterranean peninsulae.

Spectrophotometric, differential pulse polarographic and differential pulse voltammetric monitoring of the chemical destruction of the anti-tumour pharmaceuticals 6-mercaptopurine, 6-thioguanine and melphalane.

A new method has been developed for the destruction of 6-mercaptopurine, 6-thioguanine and melphalane in laboratory waste, based on oxidation of these substances by potassium permanganate in sulphuric acid medium. To study the effectiveness of the decontamination, spectrophotometric and differential-pulse polarographic methods have been developed for the determination of 6-mercaptopurine and 6-thioguanine and spectrophotometric and differential-pulse voltammetric methods for melphalane. These techniques have been employed to demonstrate that the effectiveness of the proposed method is around 99.8%. Its usefulness for the destruction of various types of expired pharmaceuticals has been demonstrated.

Determination of chlorpromazine and thioridazine by differential pulse voltammetry in acetonitrile medium.

This work describes optimal conditions for the determination of chlorpromazine and thioridazine by DPV, with a detection limit of 4.0 x 10(-7)M (0.16 microg/ml). The well-defined peaks indicate that direct measurement in a medium of 0.03 M perchloric acid in acetonitrile is possible and the use of DPV is advantageous when small amounts are to be determined. The sample procedure for pharmaceutical tablets is simple and fast. The method is useful for control of the quality and purity of phenothiazine drugs. The possibility of using numerical analysis to resolve composite signals of the compounds studied has also been demonstrated.

Monitoring of aromatic amines by HPLC with electrochemical detection: comparison of methods for destruction of carcinogenic aromatic amines in laboratory wastes.

A new chemical method for destruction of carcinogenic aromatic amines in laboratory wastes has been developed. The method is based on enzymatic oxidation of the amines in solution (with hydrogen peroxide and horseradish peroxidase), followed by oxidation of the solid residues with permanganate in sulphuric acid medium. To monitor the efficiency of destruction, a reversed-phase HPLC system has been developed, with voltammetric detection with a carbon-fibre detector, which is substantially more sensitive (detection limits from a few ng down to a few pg of amine) than the commonly used ultraviolet photometric detection. It has been demonstrated that the proposed method of destruction is highly efficient (99.8% destruction).

Voltammetric determination of benzidine and its derivatives, at a glassy-carbon electrode.

Conditions have been found for the determination of benzidine, o-tolidine, o-dianisidine, 3,3'-diaminobenzidine and 3,3'-dichlorobenzidine by classical and differential pulse voltammetry at a glassy-carbon stationary or rotating electrode, in the concentration range 10(-5)-10(-3)M. The mechanism of the oxidation is discussed and applications are presented for the determination of these chemical carcinogens and their mixtures either directly, or after preliminary separation by extraction or thin-layer chromatography.

Faecal progesterone metabolite analysis for non-invasive monitoring of reproductive function in the white rhinoceros (Ceratotherium simum).

The two subspecies of white rhinoceros, southern (Ceratotherium simum simum) and northern (Ceratotherium simum cottoni), breed poorly in captivity, and estimates of oestrous cycle length vary considerably (range, 25-90 days). To characterise reproductive patterns, faecal samples were collected 2-3 times/week for up to 56 months from non-pregnant animals (n=21) of both subspecies. Immununoreactive pregnanes containing a 20-oxo-group (20-oxo-P) were analysed in a group-specific enzyme immunoassay using an antibody against 5alpha-pregnane-3beta-ol-20-one 3HS:BSA. Reproductive patterns were highly variable among and within individual animals. However, rhinoceroses could be classified into four major categories on the basis of oestrous cycle length and luteal phase 20-oxo-P concentrations: (1) regular oestrous cycles of 10 weeks duration and > 800 ng/g (n=2 animals); (2) oestrous cycles between 4-10 weeks and 250-750 ng/g (n=6); (3) no apparent cycle regularity, but luteal activity indicated by 20-oxo-P concentrations of 100-200 ng/g (n=6); (4) no apparent luteal activity as indicated by 20-oxo-P of < 100 ng/g (n=7). In two attempts to induce ovarian activity, chlormadinone acetate was fed daily to one animal for 35 and 45 days, respectively. Each treatment was followed by a subsequent hCG injection which resulted in luteal phases of 17 and 18 days, respectively, beginning about 10 days after hCG. Concentration of faecal 20-oxo-P in one pregnant animal during the 4th and 5th month of gestation were markedly higher than those observed during the luteal phase of the cycle. In conclusion, two thirds of white rhinoceroses in this study had erratic or missing luteal activity, whereas variable cycles of 4-10 weeks in length were evident in six females, and regular oestrous cycles of 10 weeks in length were found in two animals.

Macrotetrolide antibiotics produced by Streptomyces globisporus.

Macrotetrolides isolated from a new producer, Streptomyces globisporus, were identified as nonactin, monactin, dinactin and trinactin. Spectroscopic characterization of these compounds was extended by 13NMR spectra. Chemical ionization with ammonia as reactive gas was proposed for mass-spectroscopic characterization of their mixtures. Their biological activity was confirmed by using larvae of the Colorado potato beetle (Leptinotarsa decemlineata) as a new test model.

Preparative high-performance liquid chromatography of minor products of Streptomyces cinnamonensis.

Analytical and preparative high-performance liquid chromatography of 3 phenazines and furonaphthoquinone derivative on reversed-phase column are described. The mobile phase was methanol and water. The injected amount of the mixture was about 30 mg for a preparative chromatographic run requiring 80 min. Substances were detected directly in the column effluent by UV detection.

[The character of chromosome banding in the karyotype of the roebuck]. / Charakter prouzkování chromozómu v karyotypu srnce obecného.

We examined the karyotype in five individuals of roe-deer (Capreolus capreolus), coming from Southern Moravia. We subjected to examination the cells of bone marrow, lymphocytes of peripheral blood and germ sexual cells of roebuck. In all examined animals and in all examined tissues we found out a diploid number of seventy chromosomes. All autosomes were acrocentric, sex chromosomes had two arms. During the C-banding the centromere regions of all autosomes stained deep--dark; this demonstrated a great amount of constitutive heterochromatin. Chromosome X stained negatively during the C-banding. The pattern of G-banding was used to establish homologous pairs of chromosomes.

[The karyotype and character of chromosome bands in mountain sheep in Czechoslovakia]. / Karyotyp a charakter prouzkování chromozómu muflona v CSR.

Thirty-one moufflon (Ovis musimon) coming from eight localities in Bohemia and Moravia were examined. All animals had a diploid number of chromosomes without any numerical or structural aberrations from the standard set. On the basis of G-banding, all chromosomes were arranged into homologous pairs. C-banding was used to prove the localization of constitutive heterochromatin in the centromeric regions of the majority of chromosomes. Nucleolus organizers, demonstrated by means of A-staining, were located telometrically on the chromosomes in three big two-arm pairs and two acrocentric pairs. The number of active nucleolus organizers in individual cells ranged from 2 to 7. When these results were compared with the published data on the karyotype of sheep, the two forms were found to have much in common. It can be supposed that the karyotypes of moufflon and domestic sheep differ in the frequency of the occurrence of Ag-positive sections with nucleolus organizers.

One-year measurements of chloroethenes in tree cores and groundwater at the SAP Mimon Site, Northern Bohemia.

Chlorinated ethenes (CE) are among the most frequent contaminants of soil and groundwater in the Czech Republic. Because conventional methods of subsurface contamination investigation are costly and technically complicated, attention is directed on alternative and innovative field sampling methods. One promising method is sampling of tree cores (plugs of woody tissue extracted from a host tree). Volatile organic compounds can enter into the trunks and other tissues of trees through their root systems. An analysis of the tree core can thus serve as an indicator of the subsurface contamination. Four areas of interest were chosen at the experimental site with CE groundwater contamination and observed fluctuations in groundwater concentrations. CE concentrations in groundwater and tree cores were observed for a 1-year period. The aim was to determine how the CE concentrations in obtained tree core samples correlate with the level of contamination of groundwater. Other factors which can affect the transfer of contaminants from groundwater to wood were also monitored and evaluated (e.g., tree species and age, level of groundwater table, river flow in the nearby Ploucnice River, seasonal effects, and the effect of the remediation technology operation). Factors that may affect the concentration of CE in wood were identified. The groundwater table level, tree species, and the intensity of transpiration appeared to be the main factors within the framework of the experiment. Obtained values documented that the results of tree core analyses can be used to indicate the presence of CE in the subsurface. The results may also be helpful to identify the best sampling period for tree coring and to learn about the time it takes until tree core concentrations react to changes in groundwater conditions. Interval sampling of tree cores revealed possible preservation of the contaminant in the wood of trees.

Comprehensive cross-amplification of microsatellite multiplex sets across the rodent genus Microtus.

We developed four multiplex panels comprising 19 microsatellite loci and tested their amplification in 21 rodent species important for agricultural and conservation management (Microtus, Arvicola, Chionomys). On average, 17.6 loci amplified per species. Number of alleles ranged from 1 to 19 per locus. We report an additional locus polymorphic in 15 vole species.