Hemoglobins from bats (Myotis myotis and Rousettus aegyptiacus): a possible example of molecular adaptation to different physiological requirements

The functional properties of the hemoglobin systems from two different species of bat i.e. Rousettus aegyptiacus and Myotis myotis have been studied as a function of chloride, polyphosphates, pH and temperature. Apart from overall similarities shared with most mammalian hemoglobins, the two systems show significant differences with respect to the effect of chloride and temperature sensitivity. These findings have been related to the different physiological needs of the two species.     

The destruction and conservation of the Egyptian Fruit bat Rousettus aegyptiacus in Cyprus: a historic review

In Cyprus, there are 16 species of bats most of which are threatened with extinction. With the exception of the megachiropteran Egyptian Fruit bat Rousettus aegyptiacus that feeds on fruit, the rest of them are insectivorous microchiropterans. The Fruit bat was declared as a pest by the Department of Agriculture of the Ministry of Agriculture, Natural Resources and Environment of Cyprus since the early 1900s. To reduce the number of this “pest”, the above-mentioned Department, since 1927, used fumigation, shooting, and the purchase of dead bats. Fumigating and closing caves not only destroyed Fruit bats by direct poisoning, but the entire cave ecosystems, including highly beneficial and protected insectivorous species. The first attempt to protect bats on the island was in 1988 with law No. 24 of 1988, ratifying the Convention on the Conservation of European Wildlife and Natural Habitats, 82/72/EEC. This convention protects all microchiroptera species except Pipistrellus pipistrellus that is strictly protected. R. aegyptiacus is rare, with small populations that are not at present endangered or vulnerable but at risk. Cyprus recently became a member state of the European Union. This provided the opportunity to include R. aegyptiacus in the Annexes II and IV of the council directive 92/42/EEC of May 21, 1993 on the conservation of natural habitats and of wild fauna and flora, which will guarantee the long-range protection and survival of this species.     

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. Accepted: 5 February 1999     

Mating system of wild Phaseolus lunatus L. and its relationship to population size

Using isozyme variation in a naturally pollinated seed family for 10 wild Phaseolus lunatus L. (Lima bean) populations, ranging in sizes from 10 to 60 reproductive individuals, we estimated levels of outcrossing (t) and parental inbreeding coefficient (F). We also examined the relationship between outcrossing rate and population size. Average estimates of the single-locus outcrossing rate (ts) ranged from 0.024 to 0.246 (mean=0.091+/-0.065). Estimates of the multilocus outcrossing rate (tm) ranged from 0.027 to 0.268, and averaged 0.096+/-0.071. Inbreeding coefficients based on genotypic frequencies of maternal plants were positive and significantly greater than zero (F=0.504), suggesting an excess of homozygotes in all the populations studied. There was indirect evidence of nonrandom mating for outcrosses and this was mainly attributed to self-fertilisation since the averaged difference between tm and ts, which provides a measure of biparental inbreeding, represents only 1% of the autogamy rate. No significant correlation was observed between outcrossing rate and population size. Estimates of t showed significant heterogeneity among populations and factors explaining this tendency are suggested.     

Virological and Serological Findings in Rousettus aegyptiacus Experimentally Inoculated with Vero Cells-Adapted Hogan Strain of Marburg Virus

The Egyptian fruit bat, Rousettus aegyptiacus, is currently regarded as a potential reservoir host for Marburg virus (MARV). However, the modes of transmission, the level of viral replication, tissue tropism and viral shedding pattern remains to be described. Captive-bred R. aegyptiacus, including adult males, females and pups were exposed to MARV by different inoculation routes. Blood, tissues, feces and urine from 9 bats inoculated by combination of nasal and oral routes were all negative for the virus and ELISA IgG antibody could not be demonstrated for up to 21 days post inoculation (p.i.). In 21 bats inoculated by a combination of intraperitoneal/subcutaneous route, viremia and the presence of MARV in different tissues was detected on days 2–9 p.i., and IgG antibody on days 9–21 p.i. In 3 bats inoculated subcutaneously, viremia was detected on days 5 and 8 (termination of experiment), with virus isolation from different organs. MARV could not be detected in urine, feces or oral swabs in any of the 3 experimental groups. However, it was detected in tissues which might contribute to horizontal or vertical transmission, e.g. lung, intestines, kidney, bladder, salivary glands, and female reproductive tract. Viremia lasting at least 5 days could also facilitate MARV mechanical transmission by blood sucking arthropods and infections of susceptible vertebrate hosts by direct contact with infected blood. All bats were clinically normal and no gross pathology was identified on post mortem examination. This work confirms the susceptibility of R. aegyptiacus to infection with MARV irrespective of sex and age and contributes to establishing a bat-filovirus experimental model. Further studies are required to uncover the mode of MARV transmission, and to investigate the putative role of R. aegyptiacus as a reservoir host.     

On the presence of chromaffin cells in the adrenal cortex: their possible role in adrenocortical function

Using light and electron microscopy, we have observed the presence of rays containing medullary tissue extending across the cortex of rat adrenal glands. Within these rays chromaffin cells, as well as collagen and nerve fibers, were present. It is suggested that these endocrine cells may have a paracrine function within the cortex, possibly via their secretory product.     

Effects of ethanol on food consumption and skin temperature in the Egyptian fruit bat (Rousettus aegyptiacus)

Since mammalian frugivores generally choose to eat ripe fruit in which ethanol concentration ([EtOH]) increases as the fruit ripens, we asked whether ethanol acts as an appetitive stimulant in the Egyptian fruit bat, Rousettus aegyptiacus, and also studied the effects of ethanol on their skin temperature (T(s)). We hypothesized that the responses of fruit bats to dietary ethanol are concentration dependent and tested the predictions that the bats' response is positive, i.e., they eat more when [EtOH] in the food is in the range found in naturally ripe fruit, while it negatively affects them at higher concentrations. We also tested the prediction that in winter, even when availability of fruit is low and thermoregulatory costs are high, ingestion of ethanol by fruit bats is low because assimilated ethanol reduces shivering thermogenesis and peripheral vasodilation; these, alone or together, are detrimental to the maintenance of body temperature (T(b)). In summer, captive bats offered food containing 0.1% ethanol significantly increased consumption over food with no ethanol; they did not change consumption when food contained 0.01, 0.3, or 0.5% ethanol; but significantly decreased consumption at higher levels of ethanol [EtOH], i.e., 1 and 2%. In winter, captive bats ate significantly less when their food contained 0.1% ethanol than when it contained 0, 0.3, or 0.5%. During summer, freshly caught bats ate significantly more ethanol-containing food than freshly caught bats in winter. Skin temperature (T(s)) in Egyptian fruit bats decreased significantly at an ambient temperature (T(a)) of 12 °C (winter conditions) after gavage with liquid food containing 1% ethanol. The effect was clearly temperature-dependent, since ethanol did not have the same effect on bats gavaged with food containing 1% or no ethanol at a T(a) of 25 °C (summer conditions). In conclusion, ethanol may act as an appetitive stimulant for Egyptian fruit bats at low concentrations, but only in summer. Bats are deterred by food containing [EtOH] corresponding to that in overripe, unpalatable fruit (1 and 2%). Furthermore, during winter, Egyptian fruit bats are deterred by ethanol-rich fruit, possibly due to the potential thermoregulatory consequences of ethanol consumption.     

Mobile dispersed genetic elements in eukaryotes and their possible relationship to carcinogenesis

During last three years, the mobile dispersed genetic elements (mdg) were isolated from the genome of Drosophila melanogaster, yeasts and mammals. According to a number of their properties, mdg elements are quite similar to endogenous pro-retroviruses. It is known that in many cases oncogeneity of retroviruses depends on the incorporation of the certain host genes (potential oncogenes) into the viral genome. We suggest that in some cases mdg elements could entrap the potential oncogenes in the course of transposition. As a result, oncogenes become uncontrollable by host regulatory systems and may induce cell transformation. Another possible mechanism underlying switch off of the gene responsible for differentiation control may be mdg transposition to a region in close vicinity of the gene. As transposition of mdg elements seems to occur rather often, they may be regarded as one of the most important factors of genome rearrangements leading to cell transformation.     

Endogenous oligonucleotides of human milk and their possible biological function.

Oligonucleotides (ON) 4 to 60 nucleotides in length were isolated by ion-exchange chromatography on a column with Fractogel TSK DEAE-650 (M) from human milk which was hydrolyzed with proteinase K. ON from 60 to 16 nucleotides were degraded by RNase A but were resistant to DNase I, and, thus, they were ribooligonucleotides. In the presence of [gamma-32P]ATP, ON and heparin inhibited the phosphorylation of 38- and 20-kD milk proteins and failed to affect the phosphorylation of a 76-kD protein. Human milk is believed to contain polyanion-dependent and polyanion-independent protein kinases. The influence of the ON on the activity of the cytotoxic fraction of human milk alpha-lactalbumin towards human mammary gland carcinoma MCF-7 cells was studied. The ON inhibited the cytostatic and cytotoxic effects of alpha-lactalbumin. Synthetic oligonucleotides and heparin had similar effects. The endogenous ON are suggested to be involved in the regulation of cytotoxic activity of human milk.     

The relationship between organ weights and body weights, facial dimensions, and dental dimensions in a population of olive baboons (Papio cynocephalus anubis)

Questions concerned with the relationship between organ weights and body weight on an intraspecific level are best answered by using a sample of animals collected in the wild from a single locale during a single season. The organ weights and body weights for this study were obtained from the necropsy reports prepared in the field (Athi Plain, Kenya) by H. C. McGill, Jr. on 36 adult animals (18 males and 18 females). Dental and facial measurements were taken by M.I. Siegel. In order to avoid erroneous results produced by statistical treatment of combined sex samples of sexually dimorphic species, data on the sexes were analyzed separately. Means and standard deviations are reported for selected organ weights and body dimensions (heart, lung, liver, spleen, kidney, adrenal, brain, and pancreas weights, crown–rump length, crown–heel length, head circumference, chest circumference, and body weight). All of the above measures were significantly (p<0.05) different between the sexes. Logarithms of these measures were significantly correlated with the logarithm of body weight in males for heart, lung, liver, spleen, kidney, and adrenal weights, crown–heel length, and head and chest circumference, and in females for crown–heel length, heart, liver, and kidney weights. Partial correlational analysis, removing the effects of body size (weight), showed mostly negative correlational relationships between dental and visceral dimensions. Most of the correlations between facial and visceral dimensions were negative. Allometric equations were calculated for the dental, facial, and visceral dimensions versus body weight, and are compared with prior published results.     

Unique behavioral effects of beta endorphin and their relationship to thermoregulation and hypothalamic function.

Intraventricular (ivt) injections of sub-cataleptic doses of β endorphin in rats were observed to result in wet-dog shakes. Subsequent to the wet-dog shakes, copious salivation accompanied by a clonic, seizure-like state was occasionally observed to occur. This sialogogic effect of β endorphin was blocked by naloxone and diminished by injections of thyrotropin releasing hormone. None of these behaviors were observed following ivt injection of morphine in equi-antinociceptive doses. Furthermore, hypophysectomy was observed to attenuate or block these behaviors. Both the wet-dog shakes and “sialogogic seizures” were demonstrated to be dependent upon dose as well as ambient temperature. It appears possible that the occurrence of initial wet-dog shakes may result in the elevated body temperature which then precipitates excess salivation. Since both β endorphin induced wet-dog shakes and salivation were shown to be correlated with alterations in temperature, it is possible that these effects of β endorphin indicate a physiological role for that peptide in thermoregulation.     

Sex differences in adrenocortical structure and function. XI

Summary Adrenal glands from orchectomized and ovariectomized rats, with and without replacement therapy, and also from intact controls of both sexes, were examined by autoradiography with ³H-thymidine. The labelling index after 1 or 2 nucleoside injections was higher in the zona glomerulosa of females than in male rats, while no differences were found in the fascicular and reticular zones. Orchiectomy increased the labelling index in the fascicular and reticular zones, an effect prevented by testosterone. Ovariectomy did not change the labelling index, while estradiol lowered it in the zona glomerulosa. Duration of the S phase was longer in the zona fasciculata cells of males than in females. Both orchiectomy and testosterone shortened this phase in cells of the zona fasciculata and zona reticularis. Ovariectomy prolonged the S phase in the zona fasciculata and shortened this time in the reticular zone, an effect reversed by estradiol.In the glomerular and fascicular zones, cell cycle time was longer in males than in females. Orchiectomy shortened this time in all adrenocortical zones, an effect reversed by testosterone. Ovariectomy shortened cell cycle time in the glomerular and reticular zones and prolonged it in the zona fasciculata; these effects were reversed by estradiol. Turnover rate in adrenocortical cells was markedly higher in females than in males, a difference due to testosterone which markedly decreased turnover rate.     

Puberty and dispersal in a wild primate population

This article is part of a Special Issue “Puberty and Adolescence”.     

The relationship between adrenocortical function and Hsp70 expression in socially isolated Japanese quail

Physiological responses to social isolation stress were compared in 56-day-old male Japanese quail. Birds were fed pretreated diets for 3 days as follows: (i) Basal diet (control); (ii) Basal diet + 1500 mg/kg metyrapone (BM); (iii) Basal diet + 30 mg/kg corticosterone (BCO); (iv) Basal diet + 250 mg/kg ascorbic acid (BC); (v) Basal diet + 250 mg/kg α-tocopherol (BE); (vi) Basal diet + 250 mg/kg ascorbic acid and 250 mg/kg α-tocopherol (BCE). The birds were subsequently socially isolated in individual opaque brown paper box for 2 hours. Plasma corticosterone (CORT) concentration and heart and brain heat shock protein 70 (Hsp 70) expressions were determined before stress and immediately after stress. Two hours of isolation stress elevated CORT concentration significantly in the control and BE birds but not in the BC, BCE and BM birds. There was a significant reduction in CORT concentration after isolation stress in the BCO group. Isolation stress increased Hsp 70 expression in the brain and heart of control and BM birds. However, brain and heart Hsp 70 expressions were not significantly altered in the isolated BC, BCE and BE birds. Although, the CORT concentration of BM birds was not affected by isolation stress, Hsp70 expression in both brain and heart were significantly increased. Moreover, exogenous corticosterone supplementation did not result in elevation of Hsp 70 expression. It can be concluded that, although Hsp 70 induction had not been directly affected by CORT concentration, it may be modulated by the HPA axis function via activation of ACTH.     

The relationship between tooth wear, habitat quality and late-life reproduction in a wild red deer population

1. Molar tooth wear is considered an important proximate mechanism driving patterns of senescence in ungulates but few studies have investigated the causes of variation in molar wear or their consequences for reproductive success. 2. In this study, we assessed molar tooth wear at death among red deer Cervus elaphus of known age on the Isle of Rum, Scotland. 3. First molar height showed a decelerating decline with age. In females, the rates of molar wear with age varied with location of home range and individuals experiencing low resource competition showed reduced molar wear. We suggest that this spatial variation in molar wear is related to differences in the availability of high-quality grazing habitat and levels of resource competition. 4. There was no evidence that females with more heavily worn molars had reduced reproductive performance late in life or that first molar height was associated with reproductive senescence.     

Chaunocephalosis in a wild population of Asian open-billed storks in Thailand.

The most common trematode collected from Asian open-billed storks (Anastomus oscitans) was Chaunocephalus ferox (80% prevalence). The trematode was paired in granulomas in the intestinal wall. Based on histological examination of these capsules, there was degeneration and necrosis of muscle cells in the tunica muscularis. Granulation tissue with hetrophil and lymphocyte infiltration appeared in the granulomas. Intestinal villi were shorter and wider in infected areas than in non-infected areas. Some intestinal glands were dilated. Storks with high intensity of C. ferox appeared ill. The death of storks infected with C. ferox may result from malnutrition due to the loss of absorptive function of the intestine and from the effect of granuloma formation which might interfere with the intestinal peristalsis.     

The influence of ambient temperature and the energy and protein content of food on nitrogenous excretion in the Egyptian fruit bat (Rousettus aegyptiacus)

The diets of frugivorous and nectarivorous vertebrates contain much water and generally have high energy but low protein contents. Therefore, we tested the prediction that to save energy under conditions of high energy demands and high water intake, frugivorous Egyptian fruit bats (Rousettus aegyptiacus) will increase both the absolute quantity and the proportion of ammonia in their urine. We also examined whether such changes occur when protein intake is low and water intake is high. We did three feeding trials. In trials 1 and 2, bats were fed one of four liquid diets containing constant soy protein concentrations but varying in sucrose concentration and were kept at ambient temperatures (T(a)) of 30 degrees Celsius and 12 degrees Celsius, respectively. In trial 3, bats were kept at Ta=12 degrees Celsius and fed one of four liquid diets with equal sucrose concentrations but varying protein concentrations. In trial 1, food intake at a sucrose concentration of 256 mmol/kg H(2)O was initially high but decreased to a constant rate with further increases in sucrose concentration, while in trial 2, food intake decreased exponentially with increasing sucrose concentration. As predicted, at 12 degrees Celsius with varying sucrose concentration, both the absolute quantity and the fraction of ammonia in the bats' urine increased significantly with food intake (P<0.02), while the absolute quantity of urea and the fraction of urea nitrogen excreted decreased significantly with food intake (P<0.03). Varying sucrose concentration had no significant effect on nitrogen excretion at Ta=30 degrees Celsius. Varying protein concentration had no significant effect on nitrogen excretion at Ta=12 degrees Celsius. We suggest that Egyptian fruit bats can increase ammonia excretion in response to increased energetic demands, and we calculate that they can save energy equal to approximately 2% of their daily metabolic rate by doing so.