Dynamics of extinction and the selection of nature reserves

Familiar quantitative reserve-selection techniques are tailored to simple decision problems, where the representation of species is sought at minimum cost. However, conservationists have begun to ask whether representing species in reserve networks is sufficient to avoid local extinctions within selected areas. An attractive, but previously untested idea is to model current species' probabilities of occurrence as an estimate of local persistence in the near future. Using distribution data for passerine birds in Great Britain, we show that (i) species' probabilities of occurrence are negatively related to local probabilities of extinction, at least when a particular 20-year period is considered, and (ii) local extinctions can be reduced if areas are selected to maximize current species' probabilities of occurrence We suggest that more extinctions could be avoided if even a simple treatment of persistence were to be incorporated within reserve selection methods.

Using probability of persistence to identify important areas for biodiversity conservation

Most attempts to identify important areas for biodiversity have sought to represent valued features from what is known of their current distribution, and have treated all included records as equivalent. We develop the idea that a more direct way of planning for conservation success is to consider the probability of persistence for the valued features. Probabilities also provide a consistent basis for integrating the many pattern and process factors affecting conservation success. To apply the approach, we describe a method for seeking networks of conservation areas that maximize probabilities of persistence across species. With data for European trees, this method requires less than half as many areas as an earlier method to represent all species with a probability of at least 0.95 (where possible). Alternatively, for trials choosing any number of areas between one and 50, the method increases the mean probability among species by more than 10%. This improvement benefits the least-widespread species the most and results in greater connectivity among selected areas. The proposed method can accommodate local differences in viability, vulnerability, threats, costs, or other social and political constraints, and is applicable in principle to any surrogate measure for biodiversity value.

Possible role of an adrenal parasite reservoir in the pathogenesis of chronic Trypanosoma cruzi myocarditis

The possible contribution of parasitism of the central vein of the adrenal gland (CVAG) to chronic Trypanosoma cruzi myocarditis was assayed by comparing the occurrence of nests of amastigotes in the left ventricular myocardium (LVM) and determining the number and extent of areas of focal leucocyte exudate (FLE) in Chagas disease patients with and without CVAG parasitism. The frequency of occurrence of T. cruzi nests in the LVM, as well as the FLE number and area, were greater among patients with CVAG parasitism. We therefore suggest that CVAG parasitism plays a role in the onset and intensity of chronic T. cruzi myocarditis.

[Comparison of parasitology of the central vein of the adrenal gland and the other tissues in chronic chagas disease]

By morphological and morphometric analyses of serial sections the occurrence of T. cruzi nests in the central vein and in the parenchyma of adrenal glands, in the left ventricular wall and in the inferior vena cava wall in chronic Chagasic patients was studied. Of 36 cases 50% showed parasites in the adrenal central vein wall (total 29 nests), 3.1% showed parasites in the vena caval wall (only I nest) and 16.8% we found parasites in the myocardiocytes (total 23 nests). The density of parasites measured in the nests for each 100mm2 of the tissue examined, was 0.585 for the adrenal vein, 0.001 for the vena cava and 0.01 for the myocardium. No nest was found in 269103.1mm2 of adrenal parenchyma. Although the central vein area examined was smaller, it showed the largest frequency of T. cruzi nests. Since a basic difference between these tissues is the great quantity of corticoids in the blood of the adrenal central vein, this prevalence may be because of this hormonal ambient, which with its immunosuppressor and anti-inflammatory effects could help T. cruzi survival.

[Prevalence of intestinal parasitosis in feces collected during necropsies]

With the intention to verify the frequency of intestinal parasites, we have taken the inside digestive system material from three different parts of the intestinal tract while we were doing 135 complete necropsies. The stools were kept in MIF (Formol, iodine and merthiolate mixture) being studied in slides by the direct method. We have found intestinal parasites in 40 cases (29.6%), 11 (27.5%) with two or more kinds of parasites and 29 cases (72.5%) with only one kind of parasite. The most frequent parasites were: S. stercoralis (31,9%), E. hystolytica (23.4%), hook worm (19.1%) and A. lumbricoides (17%). The results are in according with epidemiological research made in this area. Thus, they prove that the parasitological exam made in feces taken during the necroscopy provides further evidence to enrich the anatomo-pathological diagnosis.

Application of a simple method to the characterization and differentiation of protein foods

A screening method for the characterization and differentiation of proteinaceous samples and amino acid mixtures was applied to protein foods (4 protein-rich mixtures, one product sold as dietary supplement, and 3 raw materials of frequent use in the preparation of these products). Graphic profiles which describe the relative amounts of amino acid groups in the samples were obtained and subjected to statistical analysis. According to a previously established criterion of identity or difference, the correlation coefficients showed that at least 90% of the comparisons dealt with different samples. The method is proposed as a valuable tool for the quality control of protein-rich foods and their raw materials.