Negative density‐dependent dispersal in tsetse (Glossina spp): red flag or red herring?

A deterministic model of the distribution of tsetse flies (Glossina spp) was used to assess the extent to which the efficacy of control operations would be affected by three different modes of density dependence in per capita adult dispersal: (i) density‐independent dispersal which has been commonly adopted in previous models, (ii) positive density‐dependent dispersal which has occasionally been discussed in the tsetse literature, (iii) negative density‐dependent dispersal (NDDD). The last has recently been suggested, from genetic studies, to change the dispersal rate of tsetse by up to 200‐fold, thereby posing a severe risk for the success of tsetse control operations. Modelling outputs showed that NDDD poses no such risk, provided the mean daily dispersal of tsetse is below about 1 km, which is greater than any rate actually recorded in the field or indicated by the genetic studies. NDDD can be problematic only if tsetse disperse at rates that appear highly unlikely, or even impossible, on energetic grounds. Under some circumstances these high rates would help rather than hinder the control officer. NDDD is not necessary to explain the results of control operations, and not sufficient to explain the results of successful control programmes.     

Neurobiological actions of cysteamine

Somatostatin (SS)-related peptides act within discrete brain regions to inhibit adrenal epinephrine (E) secretion, to prevent hypothermia, and to produce hyperthermia. Depletion of brain concentrations of these SS-related peptides using cysteamine (CSH) or central administration of an SS receptor antagonist increases adrenal E secretion and impairs thermoregulation. These actions of CSH and the SS receptor antagonist are reversed by administration of SS into the central nervous system. These results support the hypothesis that endogenous brain SS-related peptides are involved in the regulation of adrenal E secretion and thermoregulation.     

Anaerobiosis revisited: growth of Saccharomyces cerevisiae under extremely low oxygen availability

Applied Microbiology and Biotechnology - The budding yeast Saccharomyces cerevisiae plays an important role in biotechnological applications, ranging from fuel ethanol to recombinant protein...     

The importance of runoff to DDT and PCB inputs to the Sado estuary and Ria Formosa

PCB congeners, DDT and metabolites were determined in suspended sediments and in the oysterCrassostrea angulata from the upper Sado estuary over two years (1987/88 and 1990) and from Ria Formosa during 1990. Levels of DDT concentrations in suspended sediments collected in both estuarine areas, either in 1988 or 1990, increased in winter. Otherwise, PCB concentrations varied in an erratic way. A DDT enrichment was also recorded inC. angulata in winter and an increase of only PCB concentration levels in oysters of the upper Sado estuary was registered at the same period. These results suggest that, in the absence of important direct sources of PCB and DDT, runoff appears to be the major source of those compounds in both the study areas. Levels of concentrations of these pollutants in oysters reflect either their increase in the environment or changes in particle dynamics in the two estuarine areas.