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.

Mitochondrial DNA turnover occurs during preimplantation development and can be modulated by environmental factors.

Abstract: There is increasing evidence in humans that abnormal mitochondrial DNA (mtDNA) is associated with common degenerative disorders of the twenty-first century. MtDNA is exclusively female in origin and abnormalities in mtDNA can either be inherited, or generated de novo by adverse environmental factors that disturb mitochondrial DNA synthesis or destabilize mtDNA. The preimplantation period of development in mammals was thought to be relatively immune from environmentally induced changes to mtDNA, since no replication of mtDNA was thought to occur at this stage. This study demonstrates that there is a very short period of mtDNA synthesis immediately after fertilization, which can be affected by environmental stress. Adverse culture conditions during this phase of development could therefore alter the mitochondrial genome, with possible long-term consequences for the health of the offspring. The findings have relevance for all assisted reproduction programmes and for the rapidly emerging field of stem cell technologies.

Suppression of leptin during lactation: contribution of the suckling stimulus versus milk production.

Abstract: Lactation in the rat is characterized by the suppression of pulsatile LH secretion, a large increase in food intake, and changes in energy balance due to the metabolic drain of milk production The change in energy balance may be a major component in altering reproductive function A number of factors may contribute to changing energy balance of a lactating animal; one is leptin, the product of adipose tissue, which is known to act partly as a satiety factor to decrease food intake The aims of the present study were to determine whether there are changes in leptin levels during lactation, a state of high energy demand, and during periods of acute suckling in the presence or absence of changes in energy demand Our goals were to determine whether lactation and the suckling stimulus influenced serum leptin levels and whether there was a potential role for leptin in the suppression of LH secretion during lactation The first experiment was performed during diestrus of the estrous cycle, and chronic lactation, (day 9 post partum) in animals suckling 8 pups The results showed that leptin levels were significantly decreased in both ovarian intact or ovariectomized lactators; this decrease parallels the suppression of pulsatile LH secretion Serum insulin levels were not altered in the lactating animals The second experiment was performed in ovariectomized lactators whose 8 pup litters were removed for 48 h, starting on day 9 On day 11, mothers received no pups or pups that were either nonfostered (resulting in no milk production) or fostered (resulting in milk production) The pups were allowed to suckle for 24 h Following 24 h of acute suckling, serum leptin, and insulin levels correlated with the energy drain on the mother The levels of leptin were normal and of insulin were elevated in mothers producing no milk Conversely, leptin levels were suppressed and insulin levels normal in mothers producing milk The third experiment used the same groups as described for the second experiment except that serial blood samples were collected for measurement of pulsatile LH secretion following 24 h of acute suckling The results showed that regardless of whether leptin levels remained normal or were suppressed in response to acute suckling, pulsatile LH secretion was significantly inhibited compared with the nonsuckled control animals In summary, these data suggest that the metabolic drain of milk production, and not the suckling stimulus itself, is the most likely factor responsible for the suppression of leptin secretion during lactation Furthermore, although the decreased levels of leptin may be causally related to the inhibition of pulsatile LH secretion during chronic lactation, changes in leptin are not a prerequisite for the suppression of LH secretion in response to suckling

Lytic and lysogenic infection of diverse Escherichia coli and Shigella strains with a verocytotoxigenic bacteriophage.

Abstract: A verocytotoxigenic bacteriophage isolated from a strain of enterohemorrhagic Escherichia coli O157, into which a kanamycin resistance gene (aph3) had been inserted to inactivate the verocytotoxin gene (vt2), was used to infect Enterobacteriaceae strains. A number of Shigella and E. coli strains were susceptible to lysogenic infection, and a smooth E. coli isolate (O107) was also susceptible to lytic infection. The lysogenized strains included different smooth E. coli serotypes of both human and animal origin, indicating that this bacteriophage has a substantial capacity to disseminate verocytotoxin genes. A novel indirect plaque assay utilizing an E. coli recA441 mutant in which phage-infected cells can enter only the lytic cycle, enabling detection of all infective phage, was developed.