Diurnal activity in the Samoan flying fox,Pteropus samoensis

Speakman and co-workers suggested the diurnal Samoan flying fox, Pteropus samoensis, may be at risk of hyperthermia when flying during the day, particularly at high levels of insolation. We monitored activity of this bat and climate simultaneously at two different sites and four times of year in American Samoa. Flight activity varied significantly with time of day, between days, study sites and seasons. Out of the six data sets collected, the four with the highest mean levels of insolation showed a significant decrease in bat numbers with increasing temperature and sunlight. When each individual activity count was directly compared to the predictions of Speakman and co-workers'' biophysical model, 85 to 95% of bat flight activity was found to be in conditions the model suggested would not pose a risk of hyperthermia. This supports the suggestion that in extreme conditions the animals would not fly as they risked overheating. The 5 to 15% of counts in which animals were seen to fly in conditions the model predicted they should not may be explained by erroneous assumptions underlying the model predictions.     

Effects of two-vessel forebrain ischemia and of administration of indomethacin and quinacrine on Na<Superscript>+</Superscript>, K<Superscript>+</Superscript>-ATPase activity in various rat brain areas

The effect of a two-vessel forebrain ischemia (induced by occlusion of carotid arteries and hypotension), subsequent reperfusion, and administration of indomethacin and quinacrine on the Na⁺,K⁺-ATPase activity and diene conjugate content was studied in various rat forebrain fields. The most pronounced metabolic alterations were observed during ischemia and reperfusion. Under these effects, there was a statistically significant reduction of the Na⁺,K⁺-ATPase activity in the brain cortex and striatum and an increase of the diene conjugate content in the rat brain cortex in comparison with sham-operated animals. Injection of indomethacin, a cyclooxygenase inhibitor, to rats subjected to ischemia and reperfusion, resulted to a statistically significant increase of the Na⁺,K⁺-ATPase activity in the brain cortex, hippocampus, and striatum (p < 0.02) as compared with control animals. The diene conjugate content in the rat brain cortex during brain ischemia and reperfusion was statistically significantly lower in the rats injected with indomethacin. The effect of quinacrine (a blocker of phospholipase A₂) was similar to that of indomethacin in the rat cortex, whereas in the rat striatum and hippocampus, the quinacrine effect during ischemia and reperfusion was less marked than that of indomethacin. The obtained data indicate the ability of inhibitors of the arachidonic pathway of free radical formation to normalize the Na⁺, K⁺-ATPase activity during brain ischemia. There also revealed local peculiarities of metabolic disturbances in different regions of the rat forebrain during ischemia and reperfusion.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 1, 2005, pp. 33–38.Original Russian Text Copyright © 2005 by Molchanova, Moskvin, Zakharova, Yurlova, Nosova, Avrova.     

Cardiolipin biosynthesis and remodeling enzymes are altered during development of heart failure

Cardiolipin (CL) is responsible for modulation of activities of various enzymes involved in oxidative phosphorylation. Although energy production decreases in heart failure (HF), regulation of cardiolipin during HF development is unknown. Enzymes involved in cardiac cardiolipin synthesis and remodeling were studied in spontaneously hypertensive HF (SHHF) rats, explanted hearts from human HF patients, and nonfailing Sprague Dawley (SD) rats. The biosynthetic enzymes cytidinediphosphatediacylglycerol synthetase (CDS), phosphatidylglycerolphosphate synthase (PGPS) and cardiolipin synthase (CLS) were investigated. Mitochondrial CDS activity and CDS-1 mRNA increased in HF whereas CDS-2 mRNA in SHHF and humans, not in SD rats, decreased. PGPS activity, but not mRNA, increased in SHHF. CLS activity and mRNA decreased in SHHF, but mRNA was not significantly altered in humans. Cardiolipin remodeling enzymes, monolysocardiolipin acyltransferase (MLCL AT) and tafazzin, showed variable changes during HF. MLCL AT activity increased in SHHF. Tafazzin mRNA decreased in SHHF and human HF, but not in SD rats. The gene expression of acyl-CoA: lysocardiolipin acyltransferase-1, an endoplasmic reticulum MLCL AT, remained unaltered in SHHF rats. The results provide mechanisms whereby both cardiolipin biosynthesis and remodeling are altered during HF. Increases in CDS-1, PGPS, and MLCL AT suggest compensatory mechanisms during the development of HF. Human and SD data imply that similar trends may occur in human HF, but not during nonpathological aging, consistent with previous cardiolipin studies.     

Comparison of different methods of census of juvenile salmonids (Salmonidae) in the small river Mikocheva (Western Kamchatka)

Seinings of the lowland bed of a typical small river of Western Kamchatka demonstrated that of several methods for the census of juveniles of salmonids (Salmonidae) the most accurate result in comparison with complete removal is obtained by three-fold seining with calculation of abundance by the Zippin method. In comparison with a seine, a drive-in trap and electrofishing possess a lower average catching efficiency and a higher selectivity. The average density of fish estimated by the results of seining at the investigated stretch was 0.55–0.57 specimens/m².