Associations of myostatin gene polymorphisms with performance and mortality traits in broiler chickens

Myostatin is a negative regulator of skeletal muscle growth. We evaluated effects of myostatin polymorphisms in three elite commercial broiler chicken lines on mortality, growth, feed conversion efficiency, ultrasound breast depth, breast percentage, eviscerated carcass weight, leg defects, blood oxygen level, and hen antibody titer to infectious bursal disease virus vaccine. Progeny mean data adjusted for fixed and mate effects and DNA from 100 sires per line were used. Single nucleotide polymorphisms (SNPs) of the myostatin gene segregating in these lines were identified by designing specific primers, amplifying individual DNA in each line by polymerase chain reaction, cloning, sequencing and aligning the corresponding products. Individual sires were genotyped for five identified SNPs which contributed to eight haplotypes. Frequencies of SNP alleles and haplotypes differed between lines. Using the allele substitution effect model, the myostatin SNPs were found to have significant (P < 0.031) associations with growth, mortality, blood oxygen and hen antibody titer to infectious bursal disease virus vaccine, although the associations were not often consistent across lines. These results suggest that the myostatin gene has pleiotropic effects on broiler performance.     

Functional implications of the microbial community structure of undefined mesophilic starter cultures

This review describes the recent advances made in the studies of the microbial community of complex and undefined cheese starter cultures. We report on work related to the composition of the cultures at the level of genetic lineages, on the presence and activity of bacteriophages and on the population dynamics during cheese making and during starter culture propagation. Furthermore, the link between starter composition and starter functionality will be discussed. Finally, recent advances in predictive metabolic modelling of the multi-strain cultures will be discussed in the context of microbe-microbe interactions.     

An in vitro assessment of several enzymes for the supplementation of rabbit diets

In order to evaluate the effectiveness of several enzymes for use as feed supplements, the stabilities of these enzymes in relation to rabbit gastrointestinal content and feed processing conditions were investigated. Results showed that in glycine-HCl buffer pH 3.2, cellulase, papain and bromelain were acid tolerant while bacillus -amylase and protease were acid labile. When the buffer pH was 2.0, cellulase and papain still showed some pH resistance while bromelain was completely inactivated. With pepsin added to these buffer systems, similar results were obtained. In the gastric content system of pH 2.0, all the enzymes tested were unstable, but when the pH was 3.2 cellulase was fairly stable. Therefore, some factors in the gastric content other than pepsin might inactivate enzymes such as papain and bromelain. These factors might be the components of mineral premix in feed. On the other hand, preincubation of the enzymes with rabbit intestinal content would not affect the activities of these enzymes significantly. For the thermal stability study, it was found that, except for papain, thermal stabilities of all the enzymes tested could be significantly enhanced by mixing with the feed. Since mineral premix has an inhibitory effect on both bromelain and papain, the enzyme stabilization effect from feed could be caused by components other than mineral premix. Therefore, factors affecting the stabilities of each enzyme vary significantly and care must be taken when using these enzymes as feed supplements.     

New clinically relevant,orthotopic mouse models of human chondrosarcoma with spontaneous metastasis

Background  

Chondrosarcoma responds poorly to adjuvant therapy and new, clinically relevant animal models are required to test targeted therapy.     

Structures of the human pyruvate dehydrogenase complex cores: a highly conserved catalytic center with flexible N-terminal domains

Dihydrolipoyl acetyltransferase (E2) is the central component of pyruvate dehydrogenase complex (PDC), which converts pyruvate to acetyl-CoA. Structural comparison by cryo-electron microscopy (cryo-EM) of the human full-length and truncated E2 (tE2) cores revealed flexible linkers emanating from the edges of trimers of the internal catalytic domains. Using the secondary structure constraints revealed in our 8 A cryo-EM reconstruction and the prokaryotic tE2 atomic structure as a template, we derived a pseudo atomic model of human tE2. The active sites are conserved between prokaryotic tE2 and human tE2. However, marked structural differences are apparent in the hairpin domain and in the N-terminal helix connected to the flexible linker. These permutations away from the catalytic center likely impart structures needed to integrate a second component into the inner core and provide a sturdy base for the linker that holds the pyruvate dehydrogenase for access by the E2-bound regulatory kinase/phosphatase components in humans.