Gene expression changes associated with the airway wall response to injury.

BACKGROUND: Understanding the way in which the airway heals in response to injury is fundamental to dissecting the mechanisms underlying airway disease pathology. As only limited data is available in relation to the in vivo characterisation of the molecular features of repair in the airway we sought to characterise the dynamic changes in gene expression that are associated with the early response to physical injury in the airway wall. METHODOLOGY/PRINCIPAL FINDINGS: We profiled gene expression changes in the airway wall using a large animal model of physical injury comprising bronchial brush biopsy in anaesthetised sheep. The experimental design featured sequential studies in the same animals over the course of a week and yielded data relating to the response at 6 hours, and 1, 3 and 7 days after injury. Notable features of the transcriptional response included the early and sustained preponderance of down-regulated genes associated with angiogenesis and immune cell activation, selection and differentiation. Later features of the response included the up-regulation of cell cycle genes at d1 and d3, and the latter pronounced up-regulation of extracellular matrix-related genes at d3 and d7. CONCLUSIONS/SIGNIFICANCE: It is possible to follow the airway wall response to physical injury in the same animal over the course of time. Transcriptional changes featured coordinate expression of functionally related genes in a reproducible manner both within and between animals. This characterisation will provide a foundation against which to assess the perturbations that accompany airway disease pathologies of comparative relevance.

Associations between single nucleotide polymorphisms in multiple candidate genes and carcass and meat quality traits in a commercial Angus-cross population.

The aim of this study was to evaluate the effects of 28 single nucleotide polymorphisms (SNP) in 10 candidate genes previously shown to be associated with quality traits in pigs and cattle. The data set comprised 28 traits recorded on a commercial population of 536 Aberdeen Angus-cross beef cattle. Among the traits, 20 were carcass and sirloin quality related, one mechanical measure of tenderness, and the remaining seven were taste panel assessed sensory traits. The candidate genes studied included growth hormone (GH) and pro-opiomelanocortin (POMC). Association analysis showed that 13 of the 28 SNPs were significantly associated with at least one of the traits. Some of these were novel (POMC and mechanical tenderness), whilst others confirmed previous results (GH and eye muscle length). Following validation in other populations and breeds, these markers could be incorporated into breeding programs to increase the rate of improvement in carcass and meat quality traits.

Dramatic reduction of PrP C level and glycosylation in peripheral nerves following PrP knock-out from Schwann cells does not prevent transmissible spongiform encephalopathy neuroinvasion.

Expression of the prion protein (PrP(C)) is a requirement for host susceptibility to the transmissible spongiform encephalopathies (TSEs) and thought to be necessary for the replication and transport of the infectious agent. The mechanism of TSE neuroinvasion is not fully understood, although the routing of infection has been mapped through the peripheral nervous system (PNS) and Schwann cells have been implicated as a potential conduit for transport of the TSE infectious agent. To address whether Schwann cells are a requirement for spread of the TSE agent from the site of infection to the CNS, PrP(C) expression was selectively removed from Schwann cells in vivo. This dramatically reduced total PrP(C) within peripheral nerves by 90%, resulting in the selective loss of glycosylated PrP(C) species. Despite this, 139A and ME7 mouse-passaged scrapie agent strains were efficiently replicated and transported to the CNS following oral and intraperitoneal exposure. Thus, the myelinating glial cells within the PNS do not appear to play a significant role in TSE neuroinvasion.

Association of selected SNP with carcass and taste panel assessed meat quality traits in a commercial population of Aberdeen Angus-sired beef cattle.

BACKGROUND: The purpose of this study was to evaluate the effects of eight single nucleotide polymorphisms (SNP), previously associated with meat and milk quality traits in cattle, in a population of 443 commercial Aberdeen Angus-cross beef cattle. The eight SNP, which were located within five genes: mu-calpain (CAPN1), calpastatin (CAST), leptin (LEP), growth hormone receptor (GHR) and acylCoA:diacylglycerol acyltransferase 1 (DGAT1), are included in various commercial tests for tenderness, fatness, carcass composition and milk yield/quality. METHODS: A total of 27 traits were examined, 19 relating to carcass quality, such as carcass weight and fatness, one mechanical measure of tenderness, and the remaining seven were sensory traits, such as flavour and tenderness, assessed by a taste panel. RESULTS: An SNP in the CAPN1 gene, CAPN316, was significantly associated with tenderness measured by both the tenderometer and the taste panel as well as the weight of the hindquarter, where animals inheriting the CC genotype had more tender meat and heavier hindquarters. An SNP in the leptin gene, UASMS2, significantly affected overall liking, where animals with the TT genotype were assigned higher scores by the panellists. The SNP in the GHR gene was significantly associated with odour, where animals inheriting the AA genotype produced steaks with an intense odour when compared with the other genotypes. Finally, the SNP in the DGAT1 gene was associated with sirloin weight after maturation and fat depth surrounding the sirloin, with animals inheriting the AA genotype having heavier sirloins and more fat. CONCLUSION: The results of this study confirm some previously documented associations. Furthermore, novel associations have been identified which, following validation in other populations, could be incorporated into breeding programmes to improve meat quality.

A force plate study of avian gait.

OBJECTIVE: To test the force plate as a gait analysis system for broilers and to determine how the ground reaction force (GRF) patterns change in these birds with growth and administration of analgesia. MATERIALS AND METHODS: Thirty-three male Ross 308 chicks were raised on either an ad libitum or restricted-feeding regime, and subsequently treated with carprofen or a placebo. Vertical, craniocaudal and mediolateral GRFs were measured as the birds walked across a standard force plate. RESULTS: The data were easy to collect, and peak vertical forces of an equivalent percentage of bodyweight as seen in human walking were identified. Mediolateral forces were 2-3 times greater than those demonstrated in other species. GRF patterns showed significant changes during growth, but analgesia did not have a significant effect on the speed of walking, or GRF patterns. CONCLUSIONS AND CLINICAL RELEVANCE: The force plate is a suitable research tool for recording GRFs from avian bipeds. The large mediolateral forces identify a particularly inefficient aspect of avian gait; however, the role of pain remains to be determined.

Effect of zona pellucida removal on DNA methylation in early mouse embryos.

Removal of the zona pellucida is known to affect mouse development to term. Zygotes were recovered immediately after fertilization and their zona pellucida removed by exposure to pronase before culture and comparison with zona-intact embryos. The effect of removing the zona pellucida was assessed in terms of embryo development to blastocyst, DNA methylation, histone acetylation, and expression of three developmentally regulated genes. No significant differences were seen in percentage of embryos that developed to the blastocyst stage. However, zona-free embryos showed a significant reduction in the DNA methylation level at two-cell and four-cell stages, but no differences at pronuclear, morula, and blastocyst stages, as observed by immunofluorescence. Mechanical or enzymatic removal of the zona pellucida showed similar DNA methylation staining patterns at the two-cell stage. The time when the zona pellucida was removed appears to influence the levels of DNA methylation. When zona removal was delayed for 8 h, there was no difference in DNA methylation levels between zona-free and zona-intact two-cell embryos, indicating that the critical time is early on, between 1 and 8 h postfertilization. In contrast, when immunofluorescence analysis of histone acetylation was performed, no significant differences were seen between zona-free and zona-intact embryos at any of the developmental stage. Similarly, no differences were found regarding the onset of transcription of Dnmt1s, Nanog, and Fgf4 genes.

Evaluation of ground reaction forces produced by chickens walking on a force plate.

OBJECTIVE: To evaluate the use of a force plate as a method for objective gait analysis in adult poultry, to characterize ground reaction forces (GRFs) produced in adult chickens during normal walking, and to assess the variability of GRFs. ANIMALS: 18 clinically normal 5-month-old Brown Leghorn hens. PROCEDURE: Vertical, craniocaudal, and mediolateral GRFs were measured as hens walked across a standard force plate embedded in the middle of a runway. RESULTS: All GRFs were significantly affected by speed, and variability was high. With increasing speed, overall stance time decreased, but the percentage of stance time spent in braking or propulsion remained approximately equal. There was an overall increase in maximum propulsion force, which was produced at a greater rate over a shorter time; thus, propulsion integral decreased. Maximum braking forces and braking integrals were variable, but the rate at which the forces were generated increased. Mediolateral forces were 2 to 3 times greater in hens than values that have been reported for other species. CONCLUSIONS AND CLINICAL RELEVANCE: A standard force plate can be used to objectively measure GRFs in walking adult hens; however, the large variation in the data suggests that the technique in its current form would be of limited clinical use. Overall, vertical and craniocaudal forces had similar characteristics to those of other species, whereas mediolateral forces were found to be much greater in chickens than for other species.