Effects of supplemental dietary vitamin C on quality of semen from Nile tilapia (Oreochromis niloticus) breeders

The objective of this study was to evaluate the effects of vitamin C on growth and quality of semen from Oreochromis niloticus breeders. One hundred and sixty males were fed with different levels of vitamin C (0, 261, 599 and 942 mg/kg diet). The higher weight values were recorded for 599 (166 g) and 942 (175 g) mg of vitamin C/kg diet. Sperm motility, vigour and concentration were higher with 599 and 942 mg of vitamin C/kg diet. The semen volume, gonadosomatic index and plasma protein data from the last week showed a direct relationship with increasing levels of vitamin C. No changes were observed in the hepatosomatic index and blood glucose. The haematocrit and erythrocyte showed higher values estimated by equations derived at 850 and 638 mg vitamin C/kg diet, respectively. The leucocytes were inversely proportional to the increasing levels of vitamin C. After 100 days of feeding, animals fed the diet containing 942 mg vitamin C/kg diet had higher sperm motility, linearity, curvilinear velocity, straight line velocity and average path velocity (p < .05). Higher values of beat cross‐frequency were observed in broodfish fed diets containing 942 and 599 mg vitamin C/kg. The different vitamin C levels did not cause differences in straightness, lateral head displacement and sperm morphology. For Nile tilapia males on intensive rearing and handling conditions, vitamin C levels between 599 and 942 mg/kg may be used for a better performance and quality of semen.     

Changes in the morphology and functions of vacuoles during the death of ray parenchyma cells in <Emphasis Type="Italic">Cryptomeria japonica</Emphasis>

Changes in the morphology and functions of vacuoles provide useful information about the mechanism of cell death. In the present study, we monitored the morphology and contents of vacuoles during the death of ray parenchyma cells in the conifer Cryptomeria japonica. In differentiating xylem, ray parenchyma cells had large central vacuoles. In sapwood, vacuoles in ray parenchyma cells contained proteins, an indication that one of the main functions of these vacuoles might be protein storage. A dramatic decrease in the protein content of some vacuoles was detected in the intermediate wood before the initiation of vacuole rupture. Although vacuole rupture was detected from the intermediate wood to the outermost heartwood, some vacuoles were obviously enlarged in the inner intermediate wood. Condensed nuclei were first observed after the rupture of these large vacuoles in ray parenchyma cells. It seems plausible that the autolysis of the contents of ray parenchyma cells might be caused by the rupture of the enlarged vacuoles in the inner intermediate wood.