Intrinsic vs. extrinsic influences on life history expression: metabolism and parentally induced temperature influences on embryo development rate

Intrinsic processes are assumed to underlie life history expression and trade‐offs, but extrinsic inputs are theorised to shift trait expression and mask trade‐offs within species. Here, we explore application of this theory across species. We do this based on parentally induced embryo temperature as an extrinsic input, and mass‐specific embryo metabolism as an intrinsic process, underlying embryonic development rate. We found that embryonic metabolism followed intrinsic allometry rules among 49 songbird species from temperate and tropical sites. Extrinsic inputs via parentally induced temperatures explained the majority of variation in development rates and masked a relationship with metabolism; metabolism explained a minor proportion of the variation in development rates among species, and only after accounting for temperature effects. We discuss evidence that temperature further obscures the expected interspecific trade‐off between development rate and offspring quality. These results demonstrate the importance of considering extrinsic inputs to trait expression and trade‐offs across species.     

What is the role of cytokines in human colostrum?

No one has ever doubted that maternal milk, in comparison to formula milk, has a far superior nutritional value. Colostrum has a well acknowledge crucial value for the survival of the animal species that cannot receive immunoglobulins through the placenta. Until recently the presence of cytokines in colostrum was unsuspected but it has been now clarified that normally there are at least four cytokines, namely interleukin 1 and 6, tumor necrosis factor and interferon gamma, that may exert an important immunostimulatory role particularly on the oropharyngeal-associated lymphoid tissue. As a corollary, physiological concentration of cytokines administered per os may exert a useful adjuvant activity in aged or immunodeficient people.     

Protein kinase A inhibitors enhance radiation-induced apoptosis

In addition to a role for de novo protein synthesis in apoptosis we have previously shown that activation of a protein phosphatase or loss of activity of a kinase is also important in radiation-induced apoptosis in human cells [Baxter, and Lavin (1992): J Immunol 148:149–1954]. We show here that some inhibitors of protein kinases exacerbate radiation-induced apoptosis in the human cell line BM13674. The specific protein kinase A inhibitor isoquinoline sulfonamide (20 μM) gave rise to significantly increased levels of apoptosis at 2–6 h postirradiation compared to values after radiation exposure only. The same concentration of isoquinolinesulfonamide, which was effective in increasing apoptosis, reduced activity markedly. A 66% inhibition of cyclic AMP-dependent protein kinase A activity occurred in unirradiated cells at this concentration of H89 and activity was reduced to 58% in irradiated cells. Calphostin C, a specific inhibitor of protein kinase C, at a concentration of 0.1 μM, which caused 68% inhibition of enzyme activity in irradiated cells, failed to enhance the level of radiation-induced apoptosis. Other kinase inhibitors did not lead to an additional increase in apoptosis over and above that observed after irradiation. The results obtained here provide further support for an important role for modification of existing proteins during radiation-induced apoptosis.     

Outer membrane proteins of Pseudomonas

In this review, we describe the outer membrane proteins of Pseudomonas aeruginosa and related strains from the Pseudomonas fluorescens rRNA homology group of the Pseudomonadaceae, with emphasis on the physiological function and biochemical characteristics of these proteins. The use of opr (for outer membrane protein) is proposed as the genetic designation for the P. aeruginosa outer membrane proteins and letters are assigned, in conjunction with this designation, to known outer membrane proteins. Proteins whose primary functions involve pore formation, transport of specific substrates, cell structure determination and membrane stabilization are discussed. The conservation of selected proteins in the above Pseudomonas species is also examined.     

Stronger dung removal in forests compared with grassland is driven by trait composition and biomass of dung beetles

1. Ecosystem processes depend on the biomass of the involved organisms, but their functional diversity may play an additional role. In particular, the exclusion of key functional groups through habitat disturbance may lead to the breakdown of ecosystem functions. Dung removal is an important process contributing to nutrient cycling and thus productivity in grazed ecosystems. 2. This study investigated the role of different functional groups of dung beetles in dung removal in different habitats within a wood-pasture in two different seasons. An experimental setting with 12 blocks and 108 dung pads was used to investigate short-term dung removal over 1 week of exposure. 3. Dung removal was most strongly affected by habitat type, with almost 40% lower levels in grassland than in adjacent forest and forest gaps. Of all assemblage characteristics, total biomass of tunneller species was the strongest predictor of dung removal, whereas functional diversity showed no significant effect. In accordance with the dung removal pattern at habitat type level, densities of large tunnellers were suppressed in grassland compared with forest. 4. It is concluded that dung removal is habitat-specific and large tunnellers play a disproportionate role in this important ecosystem function in temperate forests.