Gastrin and somatostatin levels in patients with gastric cancer

Gastrin and somatostatin-like immunoreactivity (SLI) levels were studied by means of radioimmunoassay in peripheral venous blood of healthy volunteers and patients suffering from gastric adenocarcinoma or duodenal and gastric ulcers. Gastrin and SLI levels were also evaluated in patients in blood drawn from gastric veins during surgery. The elevations of gastrin and SLI levels were found in patients with gastric cancer as compared with healthy people and patients suffering from ulcers. The impairment of the negative feedback between gastrin and somatostatin secretions in patients with gastric cancer was suggested.     

Trophic ecology and persistence of invasive silver carp Hypophthalmichthys molitrix in an oligotrophic South African impoundment

The alien invasive silver carp Hypophthalmichthys molitrix established a self-sustaining feral population in an oligotrophic impoundment, Flag Boshielo Dam, in South Africa. The ability of this population to persist in a dam with low algal biomass (median annual suspended chlorophyll a = 0.08 µg l^?1), and limited access to rivers considered large enough for successful spawning, has implications for their invasive potential in other systems. Stomach content and stable isotope analysis were used to assess the trophic ecology of H. molitrix, which was then compared with indigenous Mozambique tilapia Oreochromis mossambicus, on a seasonal basis during 2011. Hypophthalmichthys molitrix are generalist filter feeders, with a diet consisting primarily of sediment, vegetative detritus, dinoflagellates and diatoms. The dominance of sediments in their stomachs suggests occasional benthic scavenging. However, H. molitrix occupied a higher trophic level (TL = 2.8) than expected, suggesting that this population subsidised their diet with an unidentified dietary constituent, characterised by enriched nitrogen values. Although the stomach contents indicated dietary overlap between H. molitrix and O. mossambicus, stable isotopes revealed fine-scale resource partitioning, despite both species occupying the same trophic level. Nonetheless, the persistence of this feral H. molitrix population in an oligotrophic impoundment highlights their phenotypic plasticity.     

Extracting information from imaging cytometry: a review

The extraction of statistically meaningful quantitative information from microscopy images is increasingly important for modern biological research. Obtaining accurate, quantitative information from biological specimens, however, is a complex process that requires optimization of several parameters. One must consider the number of probes, fluorescent channels required, type of plate to be used, number of fields to be acquired and optimal resolution for image acquisition. The extraction of information from images is dependent on and can be aided greatly by careful consideration of the factors involved in the image acquisition process. I summarize here the general principles behind the imaging and software technology that is used to quantify images and highlight particular issues of concern for critically applying image quantitation techniques for research.     

Trade up polygyny and breeding synchrony in avian populations

The advent of the molecular techniques used to assign paternity has focused attention on the differences between the social and the genetic mating systems of sexual species. In particular, the interrelations between breeding synchrony-the degree to which the fertility periods of individual females in a population overlap and the degree of extra pair paternity (EPP) in that population, has became a subject of a lively debate. Investigation of the subject can be facilitated by examining the criteria that females use in choosing extra pair partners. These preferences constitute a continuum ranging between two extremes. At one end, there are situations wherein all the females in a population exhibit a preference for males with particular phenotypic markers, and females mated to males lacking such "quality" markers seek extra pair fertilizations from males that do -trade up polygyny. At the other extreme, there are situations wherein females seek to maximize the total number of male partners, rather than secure fertilization by males of particular type -indiscriminate polygyny. Previously, we used game theoretical methods to model the interrelations between breeding synchrony and EPP in the context of indiscriminate polygyny. Here we present an analogous investigation in the context of trade up polygyny. Our results for the two cases, which delimit the range of the possible behavior, are similar. That is, we see that it is the pursuit of extra pair fertilizations opportunities that determines breeding synchrony of populations, rather than the vice versa as has been previously suggested.