Effects of high-sulphur water on hepatic gene expression of steers fed fibre-based diets.

Sulphur-induced polioencephalomalacia (sPEM), a neurological disorder affecting ruminants, is frequently associated with the consumption of high-sulphur (S) water and subsequent poor performance. Currently, there is no economical method for S removal from surface water sources, and alternative water sources are typically neither readily available nor cost-effective. Determination of genes differentially expressed in response to high-S water consumption may provide a better understanding of the physiology corresponding to high dietary S and ultimately lead to the development of treatment and prevention strategies. The objective of this study was to determine changes in gene expression in the liver, an organ important for S metabolism, of fibre-fed steers consuming high-S water. For this study, liver tissues were collected on the final day of a trial from yearling steers randomly assigned to low-S water control (566 mg/kg SO4 ; n = 24), high-S water (3651 mg/kg SO4 ; n = 24) or high-S water plus clinoptilolite supplemented at either 2.5% (n = 24) or 5.0% (n = 24) of diet dry matter (DM). Microarray analyses on randomly selected healthy low-S control (n = 4) and high-S (n = 4; no clinoptilolite) steers using the Affymetrix GeneChip Bovine Genome Array revealed 488 genes upregulated (p < 0.05) and 154 genes downregulated (p < 0.05) in response to the high- vs. low-S water consumption. Real-time RT-PCR confirmed the upregulation (p < 0.10) of seven genes involved in inflammatory response and immune functions. Changes in such genes suggest that ruminant animals administered high-S water may be undergoing an inflammation or immune response, even if signs of sPEM or compromised health are not readily observed. Further study of these, and other affected genes, may deliver new insights into the physiology underlying the response to high dietary S, ultimately leading to the development of treatments for high S-affected ruminant livestock.

Renin mRNA is upregulated in testes and testicular cells in response to treatment with aflatoxin B1.

Aflatoxin B(1) (AFB(1)) has been shown to affect fertility in many species; however, the exact molecular mechanisms associated with the disruption are not known. Our objectives were to determine changes in testicular gene expression due to exposure to AFB(1) and to investigate which cell types were affected by treatment with AFB(1). Male mice 4 wk of age were administered a daily placebo (control; N = 9) or 50 µg/kg AFB(1) (AFB(1) treated; N = 10) daily for 45 days. Males were then mated to four females each for 8 days. Male mice were characterized as being "Tolerant" (N = 3) or "Intolerant" (N = 3) to the effects of AFB(1) based on positive terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining in the testes and the number of pups sired. Tolerant males produced a similar average number of fetuses (mean ± SEM) (12.5 ± 1.2) per male as selected control males (13.4 ± 1.2), but more fetuses (P = 0.01) than Intolerant males (7.6 ± 1.2). The number of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells in Intolerant males tended to be (P = 0.10) greater (136.5 ± 27.2) than in Tolerant (55.0 ± 22.2) and selected control (54.3 ± 22.2) males. Affymetrix microarray (Sunnyvale, CA, USA) analysis revealed differential expression (P < 0.05) of 193 extra cellular space and signaling genes, 49 signal transduction genes, 45 immune regulation genes, and 230 cell differentiation genes in the testis. Renin was commonly represented amongst many clusters and was chosen for further analyses. Upregulation (P < 0.001) of Renin in Tolerant mice (N = 3) compared with Intolerant mice (N = 3) was confirmed by real-time reverse transcription polymerase chain reaction (RT-PCR) (P = 0.05). This upregulation (P = 0.01) was also observed in representative AFB(1) treated males (N = 8) compared with control males (N = 8) selected for real-time reverse transcription polymerase chain reaction analysis. Spermatogonia cultured in vitro and treated with 0, 5, 10, or 20 µg/mL AFB(1) (N = 6 per treatment) resulted in a 10-fold upregulation (P = 0.01) of Renin message at the 20 µg/mL level, whereas Leydig tumor cells showed similar differences (P = 0.03) in message for Renin in treated (10 and 20 µg/mL) versus control cell cultures. Based on these results, we inferred a role for Renin at the molecular level in the response to the adverse effects of AFB(1) in male mice.