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.

Melatonin Receptor Sites in the Syrian Hamster Brain and Pituitary. Localization and Characterization Using [125|]lodomelatonin*

Abstract: A high-affinity, discretely localized melatonin receptor has been characterized and mapped within the brain and pituitary of the Syrian hamster using the high specific activity ligand [(125)|]iodomelatonin and a combination of in vitro autoradiography and membrane homogenate receptor assays. Specific binding of radioligand was found in regions of the epithalamus and hypothalamus in the brain and the pars tuberalis of the pituitary. Excitatory amino-acid lesions destroyed [(125)|]iodomelatonin binding within the brain, demonstrating that binding sites are located on neurons. Analysis of [(125)|]iodomelatonin binding to membrane homogenates of the pars tuberalis revealed a linear relationship between specific ligand binding and the amount of tissue. The time-course of specific binding at 37 degrees C reached equilibrium after 30 min and remained stable thereafter. The addition of increasing concentrations of [(125)|]iodomelatonin alone and in the presence of 1 muM melatonin showed that specific binding reached equilibrium at 80 to 100 pM. Analysis of the saturation isotherm using a one-site binding model was consistent with a single receptor site with a K(d) of 29.3 (+/-5.9 SEM) pM and B(max) of 2.54 (+/-0.19 SEM) fmol/mg protein.

Digging deep--structure-function relationships in the melatonin receptor family.

Abstract: The melatonin receptor family is a small group of receptors within the G protein-coupled receptor (GPCR) superfamily. The group comprises of three subtypes which bind melatonin and one member, the melatonin related receptor (MRR), that shares >40% sequence identity with the other melatonin receptors but does not bind melatonin. Identification of two subtypes expressed in the mouse suprachiasmatic nucleus, one of which (MT1) inhibits neuronal firing and the other (MT2) mediating the phase advancing properties of melatonin has given renewed interest to the development of subtype specific compounds for each of the mammalian melatonin receptors. Towards this goal site-directed and chimaeric receptor mutagenesis studies have been performed which have provided some insight into the structure-function relationships of the melatonin receptors. Furthermore, these studies may lead to the identification of the ligand for the orphan MRR.

Application of the comet assay for monitoring DNA damage in workers exposed to chronic low-dose irradiation: I. Strand breakage

Abstract: We examined a group of people professionally at risk of exposure to low doses of ionizing radiation (altogether 49 individuals). Age, use of therapeutic drugs, work-related exposure to hazardous agents, previous exposures to diagnostic X-rays, such as patient and nuclear medical examination, were registered. For each individual, the occupational radiation burden received over the past period of 5 years was taken from the official personal records based on film dosimetry controlled every month. A matched group of controls was chosen among the administrative employees (40 individuals). The mean age of the studied population at the time of blood sampling was 49 years (range 24-69). The individuals were divided into groups according to risk of exposure and sex. The alkaline comet assay was used to measure DNA breaks and alkali-labile sites. We compared the mean tail moments, tail length and percentage of DNA in the tail. There was a significant difference between the control and hazard groups in DNA damage. Higher DNA damage was also found for men than for women in the control group. There was no relation of DNA damage to age either in control or hazard group. Additionally, analysis of distributions of tail moment values pointed to a considerable individual diversity even in the control group. Therefore, further investigations were necessary into the suitability of the comet assay as a biological dosimetry method; the results obtained so far warrant such investigations.

Influence of fish oil on ruminal biohydrogenation of C18 unsaturated fatty acids

Abstract: Dietary cis-9, trans-11-conjugated linoleic acid (CLA) is generally thought to be beneficial for human health. Fish oil added to ruminant diets increases the CLA concentration of milk and meat, an increase thought to arise from alterations in ruminal biohydrogenation of unsaturated fatty acids. To investigate the mechanism for this effect, in vitro incubations were carried out with ruminal digesta and the main biohydrogenating ruminal bacterium, Butyrivibrio fibrisolvens. Linoleic acid (LA) or alpha-linolenic acid (LNA) was incubated (1.67 g/l) with strained ruminal digesta from sheep receiving a 50:50 grass hay-concentrate ration. Adding fish oil (up to 4.17 g/l) tended to decrease the initial rate of LA (P=0.025) and LNA (P=0.137) disappearance, decreased (P<0.05) the transient accumulation of conjugated isomers of both fatty acids, and increased (P<0.05) the accumulation of trans-11-18:1. Concentrations of EPA (20:5n-3) or DHA (22:6n-3), the major fatty acids in fish oil, were low (100 mg/l or less) after incubation of fish oil with ruminal digesta. Addition of EPA or DHA (50 mg/l) to pure cultures inhibited the growth and isomerase activity of B. fibrisolvens, while fish oil had no effect. In contrast, similar concentrations of EPA and DHA had no effect on biohydrogenation of LA by mixed digesta, while the addition of LA prevented metabolism of EPA and DHA. Neither EPA nor DHA was metabolised by B. fibrisolvens in pure culture. Thus, fish oil inhibits ruminal biohydrogenation by a mechanism which can be interpreted partly, but not entirely, in terms of its effects on B. fibrisolvens.

Prediction of apparent digestibility and voluntary intake of hays fed to sheep: comparison between using fibre components, in vitro digestibility or characteristics of gas production or nylon bag degradation

Abstract: The study compared using chemical components (i.e. crude protein (CP), neutral- and acid-detergent fibre or lignin (NDF, ADF and ADL) g/kg dry matter (DM), the in vitro digestibility (Tilley and Terry, 1963), the in situ (nylon bag) DM degradation (g/100 g DM) and gas production (ml/200 mg DM) techniques to predict voluntary daily intake (g DM per kg M0.75) and in vivo apparent DM digestibility (DMD) of 10 graminaceous hays individually offered ad libitum to four Merino male sheep. Gas production or DM degradation were determined after 6, 12, 24, 48, 72 or 96 h incubation and their characteristics described using the equation p = a + b (1 – e-ct). Intake and in vivo DMD of the hays were variable and poorly related (r = 0·52; P > 0·05). The in situ DM degradation was significantly (Y < 0·05) related to in vivo apparent DMD at 48 to 96 h incubation (i = 0·76 to 0·75) and to intake at 24 to 96 h (r = 0·71 to 0·75) incubation. However, fibre components, the in vitro digestibility or gas production were either related to daily intake or in vivo apparent DMD, but not to both on the same occasion. Accurate prediction of intake (r = 0·90; P < 0·05) and in vivo apparent DMD (r = 0·88; P < 0·069) were achieved using NDF, ADF, ADL and CP in a multiple regression. Using the (a + b) and the rate (c) of in situ DM degradation, both in vivo apparent DMD (r = 0·77; P < 0·05) and intake (r = 0·83; P < 0·05) were predicted with accuracy. However, using the (a + b) and (c) of gas production, only intake was predicted accurately (r = 0·87; P < 0·01). The lower performance of the gas test was attributed to the small contribution to gas production and higher buffering capacity resulting from protein fermentation. When data of the graminaceous and other data from leguminous hays were combined, the most accurate prediction of both intake and apparent digestibility was by using characteristics of in situ DM degradation followed by those of gas production. The latter was more accurate than using chemical components or the in vitro digestibility. Addition of CP in the multiple regression improved the prediction of intake and in vivo apparent DMD from characteristics of gas production. It was concluded that despite the need to overcome the problem of protein fermentation in the gas test, accurate prediction of both intake and apparent digestibility can be achieved simply from the degradation characteristics of foods.