Does Xmrk an interesting spot?
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Biomedical subjects
Publications and source records attributed to J J Sohn.
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Maturation in Xiphophorus maculatus (Pisces; Poeciliidae) is under control of the sex-linked P gene. However, when two individuals are reared together the socially dominant individual delays the maturation of the subordinate. Nevertheless, it is not a requirement that a fish be socially dominant to become mature. The data suggest that inhibition of maturity takes place when an individual is not dominant at a time near the genetically determined age of maturation. Two hypotheses are offered to explain these results.
A single sex-lined gene that controls the maturation process had previously been identified in Xiphophorus maculatus. It was presumed that this gene controls the age of onset of maturation. We demonstrate that the gene is either activated or not inhibited from activity by the attainment of a critical weight rather than age.
The effect of thiopentone 0.5 and 1.0 mg/kg on the enflurane-induced cortical spike discharge has been examined. Seven cats were anaesthetized with enflurane in oxygen and ventilation was controlled to maintain eucapnia during e.e.g. recording. End-tidal enflurane concentrations of between 1.2 and 2.2% provoked dose-dependent spontaneous spike discharges reproducibly. It was found that, during light enflurane anaesthesia, intravenous thiopentone could exacerbate e.e.g. signs of seizure activity. However, at a greater depth of anaesthesia spike activity was suppressed. The e.e.g. changes following thiopentone resembled the effects of still greater concentrations of enflurane.