Studies on parturient paresis in dairy cows. V. On the composition and calcium binding capacity of two bovine serum protein fractions, with special regard to parturient paresis

In healthy cows unaffected by imminent or recent calving the protein in serum can directly bind the overwhelming proportion of the bound calcium. In recent calvers this capacity is considerably less. When adding ammonium sulphate to blood serum to 62 % of total saturation a protein fraction precipitates which is mainly albumin. This fraction has a far greater calcium binding capacity than the soluble fraction, which contains most of the serum globulin, and the lowering of this capacity after calving is entirely referable to the former fraction. No difference has been found in these respects between normal cows after calving and cows with parturient paresis.An analysis of 10 amino acids in the two protein fractions described above showed that the amino acid composition of both exhibits differences between recent calvers and cows outside the calving period, and likewise that each of the two fractions differs in composition between healthy cows after calving and cows with parturient paresis.     

Physiological and genetic characterisation of some new Aphanomyces strains isolated from freshwater crayfish

Five Aphanomyces strains were isolated during suspected outbreaks of crayfish disease in Spain and Italy. Genetic and physiological evidence show that the strains isolated from the freshwater crayfish Procambarus clarkii and Pacifastacus leniusculus, do not fit into any previously identified group of Aphanomyces astaci and are not capable of killing crayfish following standardised experimental infection. RAPD-PCR and ITS sequencing analysis show a high degree of similarity between the new isolates, while they are clearly different from the A. astaci reference strains. They do, however, possess some properties, which are commonly associated with parasitic species such as repeated zoospore emergence and the lack of sexual reproduction. The five isolates share some physiological properties i.e. a high growth rate, and germination in response to nutrients and, in contrast to A. astaci, they do not express chitinase constitutively during growth or sporulation. Until their taxonomic status is fully elucidated we suggest that the new isolates be given the tentative species name Aphanomyces repetans.     

Recent breeding history of dog breeds in Sweden: modest rates of inbreeding,extensive loss of genetic diversity and lack of correlation between inbreeding and health

One problem in modern dogs is a high occurrence of physical diseases, defects and disorders. Many breeds exhibit physical problems that affect individual dogs throughout life. A potential cause of these problems is inbreeding that is known to reduce the viability of individuals. We investigated the possible correlation between recent inbreeding and health problems in dogs and used studbook data from 26 breeds provided by the Swedish Kennel Club for this purpose. The pedigrees date back to the mid‐20th century and comprise 5–10 generations and 1 000–50 000 individuals per pedigree over our study period of 1980–2010. We compared levels of inbreeding and loss of genetic variation measured in relation to the number of founding animals during this period in the investigated dog breeds that we classified as ‘healthy’ (11 breeds) or ‘unhealthy’ (15) based on statistics on the extent of veterinary care obtained from Sweden's four largest insurance companies for pets. We found extensive loss of genetic variation and moderate levels of recent inbreeding in all breeds examined, but no strong indication of a difference in these parameters between healthy versus unhealthy breeds over this period. Thus, recent breeding history with respect to rate of inbreeding does not appear to be a main cause of poor health in the investigated dog breeds in Sweden. We identified both strengths and weaknesses of the dog pedigree data important to consider in future work of monitoring and conserving genetic diversity of dog breeds.     

Emulating membrane protein evolution by rational design

How do integral membrane proteins evolve in size and complexity? Using the small multidrug-resistance protein EmrE from Escherichia coli as a model, we experimentally demonstrated that the evolution of membrane proteins composed of two homologous but oppositely oriented domains can occur in a small number of steps: An original dual-topology protein evolves, through a gene-duplication event, to a heterodimer formed by two oppositely oriented monomers. This simple evolutionary pathway can explain the frequent occurrence of membrane proteins with an internal pseudo-two-fold symmetry axis in the plane of the membrane.     

Membrane insertion of a potassium-channel voltage sensor

The mechanism of voltage gating in K+ channels is controversial. The paddle model posits that highly charged voltage-sensor domains move relatively freely across the lipid bilayer in response to membrane depolarization; competing models picture the charged S4 voltage-sensor helix as being shielded from lipid contact by other parts of the protein. We measured the apparent free energy of membrane insertion of a K+-channel S4 helix into the endoplasmic reticulum membrane and conclude that S4 is poised very near the threshold of efficient bilayer insertion. Our results suggest that the paddle model is not inconsistent with the high charge content of S4.     

Global warming, elevational range shifts, and lowland biotic attrition in the wet tropics

Many studies suggest that global warming is driving species ranges poleward and toward higher elevations at temperate latitudes, but evidence for range shifts is scarce for the tropics, where the shallow latitudinal temperature gradient makes upslope shifts more likely than poleward shifts. Based on new data for plants and insects on an elevational transect in Costa Rica, we assess the potential for lowland biotic attrition, range-shift gaps, and mountaintop extinctions under projected warming. We conclude that tropical lowland biotas may face a level of net lowland biotic attrition without parallel at higher latitudes (where range shifts may be compensated for by species from lower latitudes) and that a high proportion of tropical species soon faces gaps between current and projected elevational ranges.     

Interaction between simulated rain and barren rock surface

During the latter decades extensive fish kills have been observed in the mountainous areas of southernmost Norway. These kills have been attributed to the increased acidity of the river-water. The increased acidity is generally assumed to be caused by acid precipitation. However, the relationship between precipitation and runoff quality is very complex. The present paper is concerned with the relationship between chemical composition of simulated rain and that of runoff from bare granitic rock, partly covered by lichens. When supplying simulated rain with a pH value of approximately 5 the very first runoff had pH values between 4.1 and 4.3. However, the pH in the runoff increased rapidly and leveled out at values between 4.6 and 4.7. When supplying simulated rain with pH approximately 3.5, the pH in the first runoff varied between 3.8 and 3.6. The pH then gradually decreased to the same values as those in the simulated rain. Runoff from ‘rain’ with pH 4.3, obtained the same pH value as that of the ‘rain’. The pH of the runoff was dependent not only on the rain acidity, but also on its content of neutral salts.