Variation in helper effort among cooperatively breeding bird species is consistent with Hamilton's Rule.

Investment by helpers in cooperative breeding systems is extremely variable among species, but this variation is currently unexplained. Inclusive fitness theory predicts that, all else being equal, cooperative investment should correlate positively with the relatedness of helpers to the recipients of their care. We test this prediction in a comparative analysis of helper investment in 36 cooperatively breeding bird species. We show that species-specific helper contributions to cooperative brood care increase as the mean relatedness between helpers and recipients increases. Helper contributions are also related to the sex ratio of helpers, but neither group size nor the proportion of nests with helpers influence helper effort. Our findings support the hypothesis that variation in helping behaviour among cooperatively breeding birds is consistent with Hamilton's rule, indicating a key role for kin selection in the evolution of cooperative investment in social birds

Natural and Vaccine-Mediated Immunity to Salmonella Typhimurium is Impaired by the Helminth Nippostrongylus brasiliensis

The impact of exposure to multiple pathogens concurrently or consecutively on immune function is unclear. Here, immune responses induced by combinations of the bacterium Salmonella Typhimurium (STm) and the helminth Nippostrongylus brasiliensis (Nb), which causes a murine hookworm infection and an experimental porin protein vaccine against STm, were examined. Mice infected with both STm and Nb induced similar numbers of Th1 and Th2 lymphocytes compared with singly infected mice, as determined by flow cytometry, although lower levels of secreted Th2, but not Th1 cytokines were detected by ELISA after re-stimulation of splenocytes. Furthermore, the density of FoxP3+ T cells in the T zone of co-infected mice was lower compared to mice that only received Nb, but was greater than those that received STm. This reflected the intermediate levels of IL-10 detected from splenocytes. Co-infection compromised clearance of both pathogens, with worms still detectable in mice weeks after they were cleared in the control group. Despite altered control of bacterial and helminth colonization in co-infected mice, robust extrafollicular Th1 and Th2-reflecting immunoglobulin-switching profiles were detected, with IgG2a, IgG1 and IgE plasma cells all detected in parallel. Whilst extrafollicular antibody responses were maintained in the first weeks after co-infection, the GC response was less than that in mice infected with Nb only. Nb infection resulted in some abrogation of the longer-term development of anti-STm IgG responses. This suggested that prior Nb infection may modulate the induction of protective antibody responses to vaccination. To assess this we immunized mice with porins, which confer protection in an antibody-dependent manner, before challenging with STm. Mice that had resolved a Nb infection prior to immunization induced less anti-porin IgG and had compromised protection against infection. These findings demonstrate that co-infection can radically alter the development of protective immunity during natural infection and in response to immunization

Improving metabolic health in obese male mice via diet and exercise restores embryo development and fetal growth

Paternal obesity is now clearly associated with or causal of impaired embryo and fetal development and reduced pregnancy rates in humans and rodents. This appears to be a result of reduced blastocyst potential. Whether these adverse embryo and fetal outcomes can be ameliorated by interventions to reduce paternal obesity has not been established. Here, male mice fed a high fat diet (HFD) to induce obesity were used, to determine if early embryo and fetal development is improved by interventions of diet (CD) and/or exercise to reduce adiposity and improve metabolism. Exercise and to a lesser extent CD in obese males improved embryo development rates, with increased cell to cell contacts in the compacting embryo measured by E-cadherin in exercise interventions and subsequently, increased blastocyst trophectoderm (TE), inner cell mass (ICM) and epiblast cell numbers. Implantation rates and fetal development from resulting blastocysts were also improved by exercise in obese males. Additionally, all interventions to obese males increased fetal weight, with CD alone and exercise alone, also increasing fetal crown-rump length. Measures of embryo and fetal development correlated with paternal measures of glycaemia, insulin action and serum lipids regardless of paternal adiposity or intervention, suggesting a link between paternal metabolic health and subsequent embryo and fetal development. This is the first study to show that improvements to metabolic health of obese males through diet and exercise can improve embryo and fetal development, suggesting such interventions are likely to improve offspring health.Nicole O. McPherson, Hassan W. Bakos, Julie A. Owens, Brian P. Setchell, Michelle Lan

SecA, a remarkable nanomachine

Biological cells harbor a variety of molecular machines that carry out mechanical work at the nanoscale. One of these nanomachines is the bacterial motor protein SecA which translocates secretory proteins through the protein-conducting membrane channel SecYEG. SecA converts chemically stored energy in the form of ATP into a mechanical force to drive polypeptide transport through SecYEG and across the cytoplasmic membrane. In order to accommodate a translocating polypeptide chain and to release transmembrane segments of membrane proteins into the lipid bilayer, SecYEG needs to open its central channel and the lateral gate. Recent crystal structures provide a detailed insight into the rearrangements required for channel opening. Here, we review our current understanding of the mode of operation of the SecA motor protein in concert with the dynamic SecYEG channel. We conclude with a new model for SecA-mediated protein translocation that unifies previous conflicting data

Identification of lactic acid bacteria isolated from South African brandy base wines.

AgriwetenskappeInstituut Vir WynbiotegnologiePlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]

Biopreservatives from yeasts with antimicrobial activity against common food, agricultural produce and beverage spoilage organisms

There are safety concerns regarding the use of chemical food preservatives for reducing microbial contamination in processed foods and post-harvest agricultural produce, and these concerns require a bioprospecting approach. Non-Saccharomyces yeasts produce antimicrobial compounds, but these compounds are not being produced nor used on a large scale due to inadequate development and understanding of process engineering systems that are required for their production. This chapter focuses on bioprospecting biopreservative potential of yeasts. A mini review on the current potential of yeasts and their extracellular compounds as biopreservatives was conducted. In an attempt to address the gaps found in current literature, and to open windows for future research on biopreservatives, a model study of growth and antimicrobial compound production kinetics from Candida pyralidae KU736785 was carried out. Results showed the potential of C. pyralidae as post-harvest biocontrol agent and as producers of biopreservation compounds. There was a broad-spectrum antimicrobial activity shown against Botrytis cinerae, Brettanomyces bruxellensis and Candida guilliermondii by the strain of C. pyralidae studied. Furthermore, a new concept for quantification of biopreservation activity was also developed to describe the efficacy of the crude biopreservative

Kinetic modelling and optimisation of antimicrobial compound production by candida pyralidae KU736785 for control of candida guilliermondii

Biological antimicrobial compounds from yeast can be used to address the critical need for safer preservatives in food, fruit and beverages. The inhibition of Candida guilliermondii, a common fermented beverage spoilage organism, was achieved using antimicrobial compounds produced by Candida pyralidae KU736785. The antimicrobial production system was modelled and optimised using response surface methodology, with 22.5 C and pH of 5.0 being the optimum conditions. A new concept for quantifying spoilage organism inhibition was developed. The inhibition activity of the antimicrobial compounds was observed to be at a maximum after 17–23 h of fermentation, with C. pyralidae concentration being between 0.40 and 1.25 109 CFU ml 1, while its maximum specific growth rate was 0.31–0.54 h 1. The maximum inhibitory activity was between 0.19 and 1.08 l contaminated solidified media per millilitre of antimicrobial compound used. Furthermore, the antimicrobial compound formation rate was 0.037–0.086 l VZI ml 1 ACU h 1, respectively. The response surface methodology analysis showed that the model developed sufficiently described theantimicrobial compound formation rate 1.08 l VZI ml 1 ACU, as 1.17 l VZI ml 1 ACU, predicted under the optimum production conditions

Cell immobilization by Gel Entrapment in Ca-alginate Beads for Balsamic-styled Vinegar Production

Conference ProceedingThe production of a high concentration of acetic acid during vinegar fermentation is a desirable occurrence for Balsamic vinegar. However, acetic acid, high osmotic pressure and low water activity resulting from the cooked grape must, can negatively affect microbial growth during fermentation. To counteract these effects, cell immobilization can improve microbial activity by protecting the cells against harsh environmental conditions. The immobilization of the microbial consortia (non-Saccharomyces yeast and acetic acid bacteria) was carried out using the calcium alginate gel beads entrapment technique. A comparative analysis of the freely suspended and gel entrapped cells was done to further evaluate the effects of surface area or bead size on acetification rates under agitated and non-agitated fermentations. Gel entrapped cell fermentations showed higher acetification rates compared to freely suspended cell fermentations. Static fermentations achieved the anticipated acetic acid production levels (60 g.L -1 ). Under these conditions, smaller beads resulted in higher acetification rates. Surface area of the beads had a significant impact on the acetification rates. Agitation promoted cell shear stress and insufficient acetification during fermentations. Gel entrapped cells using small beads under non-agitated fermentation conditions were effective for balsamic-styled vinegar production.The Agricultural Research Council (ARC), colleagues, ARC work integrated learning students are acknowledged for the infrastructural resources, financial support and technical assistance