2 results
Gene expression during testis development in Duroc boars
- S. Lervik, A. B. Kristoffersen, L. N. Conley, I. C. Oskam, J. Hedegaard, E. Ropstad, I. Olsaker
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Androstenone is a steroid pheromone occurring in the pubertal Leydig cells. Breeding against androstenone can decrease pheromone odour in swine meat but appears to cause unwanted side effects such as delayed onset of puberty. To study causality, global gene expression in developing boar testes at 12, 16, 20 and 27 weeks was investigated using a porcine cDNA microarray. The morphological status and androgenic levels of the same individuals have been described in a previous publication. In the present paper, expression of genes and pathways has been analysed with reference to these findings. Nine clusters of genes with significant differential expression over time and 49 functional charts were found in the analysed testis samples. Prominent pathways in the prepubertal testis were associated with tissue renewal, cell respiration and increased endocytocis. E-cadherines may be associated with the onset of pubertal development. With elevated steroidogenesis (weeks 16 to 27), there was an increase in the expression of genes in the MAPK pathway, STAR and its analogue STARD6. A pubertal shift in genes coding for cellular cholesterol transport was observed. Increased expression of meiotic pathways coincided with the morphological onset of puberty. Puberty-related change in Ca(2+) pathway transcripts, neurosteroids, neuronal changes and signalling in redox pathways suggested a developmental-specific period of neuromorphogenesis. Several growth factors were found to increase differentially over time as the testis matured. There may be interactions between MAPK, STAR and growth factors during specific periods. In conclusion, pathways for neurogenesis, morphological pathways and several transcripts for growth factors, which have known modulating effects on steroidogenesis and gonadotropins in humans and rodents, act at specific ages and developmental stages in the boar testis. The age dependency and complexity shown for development-specific testis transcripts must be considered when selecting phenotypic parameters for genetic selection for low androstenone. The results of selection based on measurement of phenotypic maturation and androstenone (or other steroid) levels at one specific age may differ depending on the age used. More research is necessary to find the optimal phenotype to use in order to reduce the unwanted side effects.
Adrenal responsiveness of reindeer (Rangifer tarandus tarandus) to intravenously administered ACTH
- H. Säkkinen, J. Tornberg, P. J. Goddard, E. Eloranta, E. Dahl, E. Ropstad, S. Saarela
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- Journal:
- Animal Science / Volume 81 / Issue 3 / December 2005
- Published online by Cambridge University Press:
- 09 March 2007, pp. 399-402
- Print publication:
- December 2005
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Plasma cortisol concentrations were determined from the blood of eight mature female reindeer (Rangifer tarandus tarandus) after an intravenous injection of either saline (control) or 100, 250 or 500 μg of synthetic ACTH. Blood samples were collected at 0, 2, 4, 6, 8, 10, 15, 20, 25, 30, 45, 60, 75, 90, 120, 150, and 180 min after the injections. The aims were to determine the appropriate dose of ACTH for adrenal stimulation tests, to define the dose level of ACTH which elicited a maximal cortisol response and to describe the range of blood cortisol concentrations for reference when evaluating the stress responses of reindeer.
The mean plasma cortisol concentrations (s.e.) at the zero sample times (t0) of the control and the ACTH treatments varied between 93·4 (11·8) and 132·5 (18·1) nmol/l. The total plasma cortisol response (area under curve, AUC, nmol/l × min) increased with increasing dose of ACTH (P < 0·001). The AUC of the control treatment was significantly smaller than of the ACTH treatments (P < 0·001). The highest dose of ACTH (500 μg) gave a significantly bigger AUC than the lowest dose (100 μg) (P = 0·008). The maximal plasma cortisol concentrations (CMAX) were achieved within 60 min of the ACTH injections. The ranges of individual CMAX were 59·0 to 136·8 nmol/l for the control treatment, and 110·0 to 252·0, 152·0 to 247·5 and 135·1 to 257·1 nmol/l for 100, 250 and 500 μg ACTH, respectively. The difference in CMAX was significant between the control treatment and the ACTH treatments (P < 0·001) but not between the different doses of ACTH. The plasma cortisol concentrations at the end of the observation period at t180 were not significantly affected by the ACTH treatment (P > 0·05).
In conclusion, the 100-μg dose of ACTH was sufficient to produce a significant cortisol response compared with the control treatment. Increasing the dose did not increase the maximal response, but tended to elongate the response profile. The blood sampling frequency used in the study was found suitable for detection of the cortisol response in reindeer.