We present results of Raman spectroscopic studies carried out on optically trapped red blood cells with Raman excitation wavelength in Q‐band region of the hemoglobin (Hb) absorption spectrum. The results obtained suggest that when exposed to the Raman excitation laser the RBCs get deoxygenated due to photo‐dissociation of oxygen from hemoglobin. For smaller exposure durations (5 s) the level of deoxygenation increases with an increase in power. However, for longer exposure durations the deoxygenated hemoglobin in the cells gets irreversibly oxidized to form a low spin ferric derivative of hemoglobin. The rate of oxidation depends upon the initial level of deoxygenation; higher the initial level of deoxygenation, higher is the rate of oxidation. However, the RBCs deoxygenated via oxygen deprivation (i.e. N2 purging) were found to be very stable against any laser induced effect. These observations suggests that in case of laser induced deoxygenation of RBCs the free oxygen generated by photo‐dissociation acts as the oxidizing agent and leads to oxidative damage of the RBCs.
Sperm displacement behavior of cuttlefish (Sepia esculenta) was observed in a tank. Before ejaculation, male cuttlefish used their arms III to scrape out sperm masses attached to the buccal membranes of females. The removed sperm mass debris was directly visible and countable. Active sperm were present within the removed sperm debris, implying that the aim of this behavior is to remove competing male sperm. However, many sperm masses remained on the female buccal membrane even after the removal behavior, showing that sperm removal in S. esculenta is incomplete. The duration of sperm removal (an indicator of male investment in that process) was unaffected by the body sizes of mated pair, the duration of spermatangia placement at the current mating (for the hypothesis that the sperm removal serves to creat attachment space of spermatophores), or the estimated amount of sperm masses deposited from previous matings. Moreover, male S. esculenta performed sperm removal regardless of whether the last male to mate with the partner was himself, suggesting males remove not only the sperm of rivals but also their own. Although the number of removed sperm masses increased with the time spent on removal of sperm, male cuttlefish may shorten the duration of sperm removal to avoid the risk of mating interruption. We conclude that this time restriction would likely influence the degree of partial sperm removal in S. esculenta. A digital video image relating to the article is available at .This revised version was published online in April 2005 with corrections in the abstract. 相似文献