Experimental analysis of some factors affecting parental expenditure and investment in Gasterosteus aculeatus (Gasterosteidae)

Parental investment is the cost of providing parental care. Parental investment was measured in the paternal stickleback, Gasterosteus aculeatus, by comparing future survival (measured indirectly as energy content of the body) and growth of parental and non-parental males. The time taken by parental males to renest was also measured. Male energy content was unaffected after a single parental cycle and no difference in growth rate was detected. Re-nesting was delayed. The effect of stressing parental males by exposing them to potential predators of their offspring and reducing their ration level, was also investigated. Stressed males had reduced energy contents in comparison with unstressed parental males. The time taken by stressed males to re-nest was unaffected. Males on low rations did not fan significantly less than well-fed males. Males exposed to brood predators did fan significantly less than parental males not exposed to brood predators, but the former did spend nearly 60% of their time attacking the predators when present.</p

Clinical and haematological evaluation of beta thalassaemia intermedia with increased Hb F and Hb A2 in heterozygotes: beta thalassaemia intermedia I.

Family studies were performed in 10 patients from seven different families with homozygous beta zero thalassaemia intermedia and in three patients with homozygous beta+ or compound heterozygous beta+ and beta zero thalassaemia intermedia. In nine of the 10 families at least one of the parents was found to have raised Hb A2 and Hb F. In the heterozygotes with increased Hb A2 and Hb F, the means of Hb F and MCV were significantly higher than those observed in regular Hb A2 thalassaemia heterozygotes. However, the severity of imbalance in in vitro haemoglobin synthesis was similar in these two groups. The imbalance in the alpha/non-alpha synthetic ratio was heterogeneous in the patients, being 2.1 and 4.0. Segregation of the raised Hb F from the Hb A2 beta thalassaemia determinant was found to be possible in only one of the 36 heterozygotes. This may exclude the possibility of the presence of an additional determinant responsible for the activation of the gamma chain. The G gamma/A gamma ratio of Hb F was that of the fetal type (G gamma was between 50 and 71% of the total gamma chain). The A gamma T variant of gamma chain was not detected in cis of the beta zero thalassaemia determinant characterised by increased Hb F and Hb A2. A retrospective study of 180 patients with beta thalassaemia and their parents indicated that the combined rise in Hb A2 and Hb F was more common in the heterozygous parents (11 out of 30 parents) of the patients with beta zero thalassaemia than it was in the parents of patients with beta+ thalassaemia (three out of 140 parents). The presence of increased Hb A2 and Hb F in the heterozygote may in some cases determine the relative mildness of the disease