Gonadal reproductive status of P. alba from two locations within Port Phillip Bay (38�S.,145�E.) was studied for 25 months from March 1983. Samples were collected monthly by divers and analysed for reproductive status. Although the scallops were spent of gametes during summer and showed development of gonads throughout autumn, phases of winter spawning were observed before a major late spring release. Spawning of P. alba and other scallop species in the Southern Hemisphere is a winter-spring phenomenon, rather than the summer-autumn phenomenon common among scallops of the Northern Hemisphere.
Leafy shoots of Acacia georginae were subjected to different combinations of pruning and defoliation, and their subsequent growth patterns recorded over two and a half years. Rainfall and soil moisture records were also kept. Rainfall, soil moisture, new growth and old leaf loss showed variable patterns from year to year and generally were not strongly related to each other. Light pruning was followed by increased leaf growth, with apparent stimulation, whereas heavy pruning and defoliation appeared to be detrimental to growth, mainly in that removed growth was not replaced. Actual inhibition could not be established.
Trimethylphosphate (TMP) causes aspermia in D. melanogaster males. If larvae are allowed to develop on standard maize-meal medium containing 0·002 M TMP or greater, the eclosing adult males, when placed on uncontaminated medium, exhibit a period of temporary sterility. Between test groups the period of sterility is most variable at the doses of 0·002--0·004 M, but at 0·005 M or greater is approximately 11-12 days. Near-lethal doses of about 20 g/kg by abdominal injection produces a temporary sterility in adults, whereas oral doses up to 0·02 M are ineffective. Oogenesis in females is not affected by doses which cause temporary sterility in males.In adult male D. meianogaster, which were treated as larvae with 0·01 M TMP in the food medium, the basal region of testes and seminal vesicles do not contain spermatozoa. Cytological examinations of the spermatids reveal ultrastructural changes which are characteristic of those seen in X/O and sterile-mutant males; they contain incomplete axial fibre complexes, abnormal development of the mitochondrial derivatives, and nuclei which fail to elongate and condense.Evidence from cytological studies of larval testes suggests that the chemosterilizing effect of TMP is upon early primary spermatocytes. This is also supported by mating data.
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