Development of the Early Axon Scaffold in the Rostral Brain of the Small Spotted Cat Shark (Scyliorhinus canicula) Embryo.

The cat shark is increasingly used as a model for Chondrichthyes, an evolutionarily important sister group of the bony vertebrates that include teleosts and tetrapods. In the bony vertebrates, the first axon tracts form a highly conserved early axon scaffold. The corresponding structure has not been well characterised in cat shark and will prove a useful model for comparative studies.

Sexual dimorphisms in the dermal denticles of the lesser-spotted catshark, Scyliorhinus canicula (Linnaeus, 1758).

The dermal layers of several elasmobranch species have been shown to be sexually dimorphic. Generally, when this occurs the females have thicker dermal layers compared to those of males. This sexual dimorphism has been suggested to occur as a response to male biting during mating.

The reproductive cycle of the male house gecko, Hemidactylus flaviviridis, in relation to plasma steroid concentrations, progesterone receptors, and steroidogenic ultrastructural features, in Oman.

The annual testicular cycle of the house gecko Hemidactylus flaviviridis in Oman was studied. Plasma testosterone (T), estradiol (E2) and progesterone (P) concentrations were measured using a sensitive HPLC-MS/MS detection technique. The ultrastructural steroidogenic features in Sertoli and Leydig cells, which were the major source of steriodogenesis, were examined, using transmission electron microscopy (TEM).

The effect of atrazine on Atlantic salmon (Salmo salar) smolts in fresh water and after sea water transfer.

Groups of Atlantic salmon smolts were exposed to low levels of the pesticide atrazine (2-chloro-4-ethylamino-6-isopropylamino-S-triazine) (0-22.7microgl(-1)) in fresh water and the physiological effects of exposure were measured. Further experiments exposed salmon smolts to similar levels of atrazine in fresh water, and then exposed them to full strength sea water.