Rowett Research Institute

About: Rowett Research Institute is a based out in . It is known for research contribution in the topics: Rumen & Population. The organization has 2986 authors who have published 4459 publications receiving 239472 citations.

Microbial amino acid synthesis and utilization in rats: incorporation of 15N from 15NH4Cl into lysine in the tissues of germ-free and conventional rats.

Abstract: The absorption of lysine synthesised by the gastrointestinal microflora was estimated by comparing the 15N incorporated into body lysine in four germ-free (15N-GF) and four conventional (15N-CV) rats. They were fed for 10 d on a protein-free diet containing fermentable carbohydrates and 15NH4Cl; another four conventional rats (control), fed on the same diet but with unlabelled NH4Cl, were used to estimate the natural abundance of 15N. The eviscerated carcass of each rat was homogenized and a sample hydrolysed. Lysine was isolated by ion-exchange chromatography and its 15N enrichment was measured by isotoperatio mass spectrometry. The 15N-CV rats significantly incorporated 15N into their body lysine. The 15N-GF rats had a statistically significant, although small, incorporation of 15N into their body lysine, probably arising from a measurement artifact. It was concluded, therefore, that all [15N]lysine was of microbial origin. The total lysine content in the body and the 15N enrichment of lysine in the microbial fraction of the faeces of the 15N-CV rats were also determined. The amount of microbial lysine absorbed by the 15N-CV rats was estimated by dividing the total amount of [15N]lysine in the body by the enrichment of microbial lysine. It was estimated that the daily absorption of microbial lysine by the conventional rats was 21.3 (SE 2.04) mg/kg body weight0.75.

The fatty acids present in the rumen of lambs fed on a flaked maize ration.

Abstract: The cobalt-deficient diet introduced by Stewart (1947) contains flaked maize as t..is foodstuff contains very little cobalt. Experiments in which this ration was used have already been described (Phillipson & Mitchell, 1952), and examination of the rumen contents of some of the lambs involved revealed an unusual bacteriological picture (Masson, 1950, 1951), for the protozoa had disappeared from the rumen and the usual population of iodophilic cocci seen in sheep fed on diets containing starch had been largely displaced by rod-like sporulating organisms later identified as Cbstridium butyrzkum. In addition, lactic acid-producing bacteria (lactobacilli) were isolated. These observations were most marked in those lambs receiving cobalt, for they ate more of the flaked maize mixture. Lambs receiving no supplementary cobalt did not show this picture to such a marked extent. Masson’s observations suggested that the acids formed as a result of fermentation would not be present in their usual proportions, and for this reason chromatographic separation of the steam-volatile acids was undertaken and the results are presented in this paper.

Effect of chronic food restriction on pulsatile luteinizing hormone secretion and hypothalamic neuropeptide Y gene expression in castrate male sheep.

Abstract: Castrate male sheep (wethers, average liveweight 38 +/- 0.6 kg) were given one of the following diets for 10 weeks followed by euthanasia (n = 8/group): high-energy high-protein providing 1-5 times the energy required to maintain liveweight (maintenance) (group 1.5 M), low-energy low-protein at 0.5 maintenance (0.5 M), or low-energy high-protein at 0.5 maintenance (0.5 M + P). 1.5 M wethers gained 22% liveweight whereas 0.5 M and 0.5 M + P wethers lost 18 and 13% liveweight respectively. Relative to the 1.5 M group, the 0.5 M and 0.5 M + P groups had similar plasma concentrations of glucose and cortisol throughout, but elevated non-esterified fatty acids (P < 0.001) and reduced IGF-I and insulin (P < 0.05, 0.01 or 0.001) from 1 week onwards. Each week blood samples were taken every 12 min for 4 h and plasma assayed for LH. Mean concentration over 4 h, LH pulse frequency and LH pulse amplitude showed no progressive change in 1.5 M sheep. However, in both 0.5 M and 0.5 M + P groups mean LH increased (P < 0.001 and P < 0.01 respectively), pulse frequency decreased (P < 0.01 and P < 0.01) and pulse amplitude increased (P < 0.001 and P < 0.01) over the 10-week period. Anterior pituitary. LH content was greater in 0.5 M (P < 0.01) and 0.5 M + P (P < 0.05) than in 1.5 M sheep. Coronal sections (20 microns) of hypothalamic brain tissue were subjected to in situ hybridisation to determine gene expression for neuropeptide Y (NPY). NPY mRNA was concentrated in the arcuate nucleus and median eminence, with total amounts greater in both 0.5 M (310%, P < 0.001) and 0.5 M + P (333%, P < 0.01) groups than in 1.5 M sheep (100%). These data reveal that chronic low dietary energy intake by long-term castrates, with high or low protein intake, reduces LH pulse frequency but increases the circulating levels of LH by virtue of an increase in pulse amplitude, and concomitantly increases hypothalamic NPY gene expression.

Role of the 3' untranslated region in the regulation of cytosolic glutathione peroxidase and phospholipid-hydroperoxide glutathione peroxidase gene expression by selenium supply.

Abstract: Selenium is an essential nutrient and synthesis of selenoproteins is affected by limited selenium supply. During selenium deficiency there is a differential regulation of selenoprotein synthesis and gene expression; for example, there is a decrease in abundance of mRNA for cytosolic glutathione peroxidase (cGSH-Px) and a preservation of mRNA for phospholipid-hydroperoxide glutathione peroxidase (PHGSH-Px). This difference is not due to an alteration in the rate of transcription but might reflect differences in translation. The aim of the present work was to assess the role of cGSH-Px and PHGSH-Px 3' untranslated regions (UTRs) in the regulation of selenoprotein mRNA stability and translation by using H4-II-E-C3 cells transfected with different constructs containing a type I iodothyronine deiodinase-coding region linked to different selenoprotein mRNA 3' UTRs. Translational efficiency results showed that the efficiency of the 3' UTRs in permitting selenocysteine incorporation is similar in selenium-replete conditions but, when selenium is limiting, the 3' UTR of cGSH-Px is less efficient than the 3' UTR of PHGSH-Px. The results suggest that the 3' UTR of these selenoprotein mRNA species influences their extent of translation when selenium levels are low. The different sensitivity of the 3' UTRs to selenium deficiency can explain the differential effect that selenium deficiency has on cGSH-Px and PHGSH-Px activity and mRNA levels, stability and translation. This might be partly responsible for channelling selenium for synthesis of PHGSH-Px rather than cGSH-Px.

Plasmid-associated transfer of tetracycline resistance in Bacteroides ruminicola.

Abstract: Tetracycline resistance was transferred at frequencies between 10(-7) and 10(-6) per recipient cell in anaerobic matings between two strains of the strictly anaerobic rumen bacterium Bacteroides ruminicola. The donor strain, 223/M2/7, was a multiple-plasmid-bearing tetracycline-resistant strain from the ovine rumen, and the recipient, F101, was a rifampin-resistant mutant of B14, a bovine strain belonging to B. ruminicola subsp. brevis. Resistance transfer could occur in the presence of DNase, but not in dummy mating mixtures in which filtrate from a donor culture replaced donor cells. Acquisition of tetracycline resistance by the recipient was accompanied by the appearance of a 19.5-kilobase pair plasmid (designated pRRI4) which was homologous with a plasmid of similar size and restriction pattern present in the donor strain. A transconjugant (F115) carrying pRRI4 was also able to act as a donor of tetracycline resistance and plasmid DNA in matings with another recipient. Derivatives of F115 that had spontaneously lost tetracycline resistance lacked detectable plasmid DNA. It is concluded that pRRI4 mediated the transfer of tetracycline resistance. Transfer of resistance was not detectably enhanced by pregrowth of the donor in medium containing tetracycline. Transfer of tetracycline resistance was not detected from 223/M2/7 to a strain, 23 belonging to B. ruminicola subsp. ruminicola.