Biomedical subjects

C Korine

Publications and source records attributed to C Korine.

4 recordsLinked to original sources

PubMed1999

Diurnal and seasonal changes in blood composition of the free-living Egyptian fruit bat (Rousettus aegyptiacus).

We studied the blood profile of the free-living fruit bat (Rousettus aegyptiacus) during the beginning of the activity period (around various feeding trees) and upon return to the day roost during 1994-1995. Results of the present study suggest that during winter and early spring bats are characterized by a poor physical and physiological state as reflected in the blood profile, revealing elevated urea and uric acid concentrations. It was found that at the end of the resting phase, R. aegyptiacus was in a mild state of dehydration (increased hematocrit and hemoglobin levels). At the end of activity, upon return to the day roost, both hematocrit and hemoglobin levels decreased but bats still maintained a high plasma osmolality. Several components in the blood are effected by the feeding time and show a cyclic change in concentration. The reverse relationship between glucose and triglyceride levels may indicate that glucose is the energy source during the active phase and that fat is the energy source during the resting period. The low cholesterol level in the blood reflects its absence in the fruit diet.

Animals↗

PubMed1993

Effect of water restriction on energy and water balance and osmoregulation of the fruit bat Rousettus aegyptiacus.

The energy budget, water balance and osmoregulation of the fruit bat, Rousettus aegyptiacus, were studied during normal hydration and during water restriction (oven-dried apple diet). The water input and output were balanced during both normal hydration and water restriction. The kidney of the fruit bat is well adapted to handle the water load from its fruit diet by excreting large volumes (14% of the body mass per day) of dilute urine (113 +/- 25 mosmol.kg H2O-1) as well as reducing urine volume (-95%) and increasing urine osmotic concentration (555 +/- 280 mosmol.kg H2O-1) during water restriction. The haematocrit, plasma haemoglobin and total protein concentrations did not increase during water restriction and heat exposure, suggesting the conservation of plasma volume. Gross energy intake was not affected by water restriction. However, digested energy intake and digestibility were significantly reduced. The effective regulation of energy and water budgets during water restriction suggests that the fruit bat can cope with seasonal climatic changes and with variable fruit supply during various seasons.

Animals↗

PubMedDate not supplied

Changes in the composition of the urine of yellow-vented bulbuls (Pycnonotus xanthopygos): the effects of ambient temperature, nitrogen, and water intake.

Uricotely (uric acid >50% of urinary nitrogen) in birds was once considered ubiquitous. However, Anna's hummingbirds (Calypte anna) have been shown to be an exception to this rule; under conditions of low ambient temperature (T(a)) and on a nitrogen-free diet, they increased their water intake and often became ammonotelic (ammonia >50% of urinary nitrogen). Our aim was to identify the effects of nitrogen intake, water intake, and T(a) on the ammonia excretion of yellow-vented bulbuls (Pycnonotus xanthopygos). We chose this predominantly frugivorous species because many of the characteristics of nectarivores that were used to explain increased ammonia excretion by C. anna are also characteristics of frugivorous birds. We assayed ureteral urine composition in eight yellow-vented bulbuls (P. xanthopygos), each randomly allocated a diet of 20% (0.6 M) sucrose solution supplemented by either 1.03 g/L or 7.23 g/L soy protein and held at a T(a) of either 28 degrees C or 10 degrees C. Food, and therefore water, intake rates varied with nitrogen intake but not with T(a). Food intake increased significantly with decreased nitrogen intake, while concentrations of all the excretory compounds in the urine (P<0.05) decreased; yet their proportions in the urine did not change significantly. The lower T(a) had no significant effect on food intake or on the concentration of uric acid. However, at 10 degrees C, the ammonia and urea concentrations increased (P<0.05), and this led to a significant increase in the proportion of ammonia in the urine. Our results demonstrate that, when bulbuls are exposed to low T(a), they are able to save energy by increasing the proportion of the ammonia in their urine.

Adaptation, Physiological↗

PubMedDate not supplied

Toward a global bat-signal database.

We propose a scheme for a new database using standardized protocol for recording and analysis of bat calls. The proposed database will describe and archive echolocation signals to create a reference library of bat calls. This information should be accessible to the public, thus encouraging continuous feedback from a broad audience. Because it is essential to evaluate the quality and reliability of such data, detailed information of recording and analysis procedures as well as the resulting species identification is required. A standardized and growing database on bat calls would be a potentially invaluable tool for global species identification, comparison, and distribution of microchiropterans. Currently, apart from a few websites with local call libraries, there is no "global" database established yet. We hope that researchers, amateurs, and wildlife and management authorities will adopt and further modify our suggestions for a standardized database for bat calls. We also hope that this database will stimulate new directions in bat research.

Animals↗