Sources and significance of variation in basal,summit and maximal metabolic rates in birds

The rates at which birds use energy may have profound effects on fitness, thereby influencing physiology, behavior, ecology and evolution. Comparisons of standardized metabolic rates (e.g., lower and upper limits of metabolic power output) present a method for elucidating the effects of ecological and evolutionary factors on the interface between physiology and life history in birds. In this paper we review variation in avian metabolic rates [basal metabolic rate (BMR; minimum normothermic metabolic rate), ...     

Defensin promoters as potential tools for engineering disease resistance in cereal grains

Engineering of plant protection in cereals requires well characterized tissue-specific and wounding/pathogen-inducible promoters for targeted expression of pathogen responsive and resistance genes. We describe the isolation of seven wheat and rice defensin genes expressed in early developing grain and during grain germination, two developmental stages that are particularly vulnerable to pathogens and insects. Comparison of three-dimensional (3D) models of these rice and wheat PRPI defensins indicated variations in spatial architectures that could reflect their functional diversities. Wheat and rice were stably transformed with promoter–GUS fusion constructs and the spatial and temporal activities of four promoters were studied using whole-mount and histological assays. PRPI promoters were active before and at anthesis in both transgenic wheat and rice with activity mainly in the ovary. In rice, GUS activity was also observed in vascular tissue of the lemma, palea and anthers. After fertilization, GUS was strongly expressed in the outer cell layers of the pericarp and in the main vascular bundle of the grain. During, and a short time after, seed germination, wheat promoters were active in transgenic rice embryos, roots and/or coleoptiles. All wheat and rice promoters were strongly induced by wounding in leaf, stem and grain of transgenic rice plants. These results suggest that PRPI promoters will be useful for specific targeting and accumulation of proteins conferring resistance to pathogens in vulnerable tissues of developing and germinating grain.     

New aspects of the role of MR/P fimbriae in Proteus mirabilis urinary tract infection

Proteus mirabilis, a common cause of urinary tract infection (UTI), produces a number of different fimbriae including mannose-resistant Proteus-like fimbriae (MR/P). The precise role of different P. mirabilis fimbriae in ascending UTI has not yet been elucidated. In this study, a clinical isolate of P. mirabilis and an isogenic mutant unable to express MR/P were tested using different experimental approaches. They were tested for their ability to cause infection in an ascending co-infection model of UTI and in a haematogenous model in the mouse. In both models, the mutant was less able than the wild-type strain to colonise the lower and upper urinary tracts although infectivity was not abolished. In vitro adherence to uroepithelial cells was also assessed. Significant differences in adherence between both strains were observed at 1 h but not at 15 min post infection. We have also shown that a wild-type strain carries two copies of the mrpA gene. These data reinforce the importance of MR/P fimbriae in P. mirabilis UTI although other virulence factors may be necessary for efficient colonisation and development of infection.     

Immune investment and sperm competition in a beetle

Individuals that invest more in immunity may not be able to invest as much in o\ther life history traits. The overall effects on fitness depend on the balance of investment in life history traits and unnecessary investment in immunity may lower fitness. Adult mealworm beetles (Tenebrio molitor L.) modulate their investment according to the perceived risk of infection as larvae; the amount of investment can be assessed by body coloration. This prophylactic investment in immunity can be used to assess the costs of investment when no immune challenge is present. Whether investment in immunity is traded off against sperm competitive ability, another important fitness trait in insects, was investigated. Males that had invested more in immunity (dark males) competed against males that had invested less (light males) for fertilization of offspring. Dark males did lose sperm precedence over time, whereas light males did not. However, this decrease in sperm offensive ability may not result in decreased fitness for darker males under normal female mating frequencies; the decrease in offspring did not occur for 1 week, but females that have constant access to males mate once a day, which would negate any long‐term effects of male mating order. Thus, prophylactic investment in immunity does not produce immediate reductions in a male's ability to gain fertilizations. The costs to immune investment may be born by other fitness traits in T. molitor.     

Refugia within refugia: the case study of a canopy tree (Eurycorymbus cavaleriei) in subtropical China

Aim Eurycorymbus cavaleriei (Lévl.) Rehd. et Hand.‐Mazz. (Sapindaceae) is a Tertiary relict tree endemic to subtropical China. This area is a centre for speciation and evolution within the East Asia biome and one of its most important refugial locations. In this study we aim to elucidate the phylogeographical patterning in E. cavaleriei, in order to identify the locations of the species’ main refugia and the predominant patterns of migration that have led to the contemporary spatial genetic structure of chloroplast variation. Location Subtropical China. Methods We sampled 18 populations of E. cavaleriei throughout its geographical range. Chloroplast DNA (cpDNA) sequence data from two non‐coding regions ((trnS/trnG and pl20/5′‐rps12) were obtained from 170 individuals for phylogeographical analyses. Relationships among cpDNA haplotypes were determined using median‐joining networks. Genetic structure was examined by spatial analysis of molecular variance (SAMOVA). Population differentiation was estimated by G_ST and N_ST statistics. Results Ten distinct haplotypes were identified. The level of differentiation among populations was relatively high (G_ST = 0.817), and N_ST was significantly higher than G_ST (P < 0.05), indicating that strong phylogeographical structure is exhibited by this species. The SAMOVA revealed five diverging groups of related haplotypes, which coincide with major landscape features in this region. Main conclusions The high differentiation among populations of E. cavaleriei may be a combined effect of historical and contemporary processes, such as the low effective population size for the chloroplast genome of a dioecious species, long‐term range fragmentation and limited seed dispersal for the species. Clear‐cut geographical distributions of ancestral haplotypes of the species suggest multiple potential refugia across subtropical China. The identified refugial regions have long been recognized as centres of plant diversity and endemism for China and have also been suggested as glacial refugia for many other plant species. The combination of these factors means that these locations should be considered as the highest priority for inclusion in conservation policies and sustainable forest management strategies for subtropical China.     

Toll-like receptor 2-dependent inhibition of macrophage class II MHC expression and antigen processing by 19-kDa lipoprotein of Mycobacterium tuberculosis.

Mycobacterium tuberculosis (MTB) induces vigorous immune responses, yet persists inside macrophages, evading host immunity. MTB bacilli or lysate was found to inhibit macrophage expression of class II MHC (MHC-II) molecules and MHC-II Ag processing. This report characterizes and identifies a specific component of MTB that mediates these inhibitory effects. The inhibitor was extracted from MTB lysate with Triton X-114, isolated by gel electroelution, and identified with Abs to be MTB 19-kDa lipoprotein. Electroelution- or immunoaffinity-purified MTB 19-kDa lipoprotein inhibited MHC-II expression and processing of both soluble Ags and Ag 85B from intact MTB bacilli. Inhibition of MHC-II Ag processing by either MTB bacilli or purified MTB 19-kDa lipoprotein was dependent on Toll-like receptor (TLR) 2 and independent of TLR 4. Synthetic analogs of lipopeptides from Treponema pallidum also inhibited Ag processing. Despite the ability of MTB 19-kDa lipoprotein to activate microbicidal and innate immune functions early in infection, TLR 2-dependent inhibition of MHC-II expression and Ag processing by MTB 19-kDa lipoprotein during later phases of macrophage infection may prevent presentation of MTB Ags and decrease recognition by T cells. This mechanism may allow intracellular MTB to evade immune surveillance and maintain chronic infection.