Glutamine-dependent carbamoyl-phosphate synthetase and control of pyrimidine biosynthesis in the parasitic helminth Schistosoma mansoni.

1. Carbomoyl-phosphate synthetase in Schistosoma mansoni utilizes L-glutamine as well as ammonia as nitrogen donor but does not require N-acetyl-L-glutamate for the activity. 2. The enzyme activity was inhibited by UDP, UTP, ADP and AMP, among which UDP was the most effective. 3. Aspartate carbamoyltransferase and dihydroorotase were also found and copurified with the synthetase. 4. Relative activities among these three enzymes were 1:30-60:3-8 throughout the purification. 5. These results suggest that the synthetase plays a key role in the control of pyrimidine biosynthesis de novo.     

The ontogeny of appendages of Heterocypris salina (Brady, 1868) Ostracoda (Crustacea)

The post-embryonic development of the appendages of the Cyprididae ostracod Heterocypris salina (Brady, 1868) are described in detail and compared with those of other podocope species documented in previous studies. Generally, the appearence of limbs during onotgeny of H. salina is similar to that of other species, but small differences in limb morphologies were identified between H. salina and other Cyprididae species, including other Heterocypris species. Some features appear either earlier or later in the development of H. salina compared with other species, even species of the same genus. These features may be useful characters for phylogenetic analyses at the genus and family levels.