Effects of temperature on incubation times and mortality rates of eggs of Dytiscus alaskanus (Coleoptera: Dytiscidae)

Eggs of the predaceous water beetle Dytiscus alaskanus were incubated in the laboratory at 10, 15, 20, 25 and 30°C. All measures of rate of development showed a significant linear regression with temperature. Mortality rates showed no significant regression with temperature. Data for this species were compared with similar data for D. marginalis and results discussed with reference to the climate each experiences.     

Measurement of intracellular Ca2+ in young and old human erythrocytes using 19F-NMR spectroscopy.

Elevated cell calcium has been implicated in functional changes with human erythrocyte aging. However, until recently it has been difficult to measure free ionic intracellular calcium in red cells. We have made use of a fluorinated calcium chelator probe (5,5'-difluoroBAPTA) and fluorine nuclear magnetic resonance (19F-NMR) techniques to measure changes of intracellular Ca2+ concentrations ([Ca2+]i) with cell aging. We have demonstrated in these studies that human erythrocyte [Ca2+]i is significantly elevated as a function of in-vivo aging. Young cells, the least dense fraction of density-separated erythrocytes, contained an average of 62 (+/- 4) nM Ca2+ (+/- S.E.), whereas the oldest, most dense cell fraction contained 221 nM Ca2+ (+/- 25). Mechanisms by which intracellular [Ca2+] increases with in-vivo aging are currently under investigation.