Urinary concentrating capacity of Rattus rattus and other mammals from the lower florida keys

• 1.1. There is considerable variation in the renal medullary thickness (3.4–7.7) of six mammals from islands in the Lower Florida Keys. This appears to be correlated with differences in their abilities to survive without fresh or brackish drinking water.
• 2.2. The black rat (Rattus rattus) had the highest predicted urine osmotic pressure and the highest measured urine concentration (4300 mOsm). This species was a common inhabitant of remote mangrove islets lacking brackish water ponds and often even dry land.
• 3.3. In captivity R. rattus maintained its body mass on a diet of rodent pellets (8% water) while drinking 26%. (75% seawater). However a process of 10 days acclimation was required. On 35%. (100% seawater), mass losses considerably surpassed gains and death occurred in seven to nine days.
• 4.4. Thus even the most salt tolerant mammal (R. ruttus) from islands in the Florida Keys probably can not utilize seawater for drinking. It must rely on preformed and metabolic water in its food, and possibly on a temporary lens of fresh water formed during rains for water intake.

     

Food deprivation induces differential changes in contents and microstructures of digestive tract and appendages in bluegill fish,Lepomis macrochirus

• 1.1. The digestive tract was compared with the tract appendages (caeca) in bluegill fish, Lepomis macrochirus in their response to short and long term food deprivation.
• 2.2. Fasting for 7 days resulted in 80% reduction of food content in the main tract, but only 40% reduction in appendages (caeca).
• 3.3. The intestine exhibited two different patterns of food distribution under fed and food deprived conditions.
• 4.4. The histopathological impact of starvation was more prominent on the intestine than on caeca.
• 5.5. These results suggest that digestive tract and appendages concommitantly conserve food during food scarcity, but appendages may offer advantages in retaining food longer, and in their greater resistance to starvation-induced effects.

     

Effects of long-term food restriction on energy expenditure and thermoregulation in broiler-breeder fowls (Gallus domesticus)

• 1.1. From 2 to 21 weeks of age, 150 female broiler-breeder chicks received one of three dietary treatments. Fifty received an ad libitum supply of food (treatment AL). The remaining 100 were given weighed (restricted) rations once a day, 50 receiving the amount per bird recommended in the Ross 1 Parent Stock Management Manual (treatment R) and the other 50 receiving twice this recommended amount (treatment 2R). Water was provided ad libitum for all treatment groups.
• 2.2. The daily allowance for R birds increased from 26 g per bird at 2 weeks of age to 94 g at 21 weeks. The intake of AL birds meanwhile increased from 65 g at 2 weeks to 240 g at 19 weeks, before decreasing to about 200 g at 21 weeks.
• 3.3. Median heat productions (H) per bird in the R and 2R treatment groups were, respectively, 65 and 40% lower than in the AL when adjustment was made for the reduced food intake of AL birds in the calorimeter chambers. The effects of dietary treatment on fasting H were proportionally similar.
• 4.4. Because the increasing divergence in body weights would have made a large contribution to differences in H per bird, the results were adjusted to the median weight of 2.03 kg and to unit weight (1.00kg). Adjusted fasting heat production was 18 and 11% less in 2R and R birds than in those fed ad libitum.
• 5.5. If age was included as a variate in the logarithmic multiple regression, H was proportional to body weight (W, kg) raised to the power 0.73; if age was not included, H was proportional to W^0.55.
• 6.6. Rectal temperature was 0.7°C higher in AL birds at ambient temperatures of both 23 and 28°C. All treatment groups had a higher rectal temperature at 28°C than at 23°C, with the AL birds most affected.
• 7.7. Foot surface temperature of R birds at an ambient temperature of 23°C was 8°C lower than that of the 2R and AL groups, indicating peripheral vasoconstriction.
• 8.8. Polypnea (panting) and wing-extension occurred frequently in the AL birds, which also had a greater water intake. It was also observed that the restricted birds tended to aggregate, while the AL groups tended to space themselves evenly about the pen.
• 9.9. It was concluded that broiler breeder fowl responded to restricted food intake by a reduction in heat production over and above that resulting directly from reduced metabolism of food and reduced body weight. The reduced metabolic rate per unit of weight conferred a thermoregulatory advantage at high ambient temperature.

     

Interrelationship between metabolism of tritiated water, 22sodium and dry matter intake by beef cattle consuming wheat straw and poultry litter in free choice

• 1.1. Metabolism of tritiated water and ²²sodium was studied in six beef cows under Mediterranean summer conditions in order to find whether the turnover of these tracers can be used to evaluate pasture intake.
• 2.2. The diet of the cows included ad libitum access to two components which were given separately in different troughs: one was poultry litter and the other was wheat straw, to simulate the dry pasture.
• 3.3. Voluntary daily dry matter intake (111 g/kg^0.75) was unexpectedly high considering the low digestibility of the feed.
• 4.4. The assumptions of constant ratios of water intake to water turnover and of dry matter intake to water intake were confirmed. Consequently, dry matter intake was determined accurately from water turnover measurements.
• 5.5. Sodium intake was practically equal to sodium turnover and most of the sodium secreted in feces was of endogenous origin.
• 6.6. Pasture intake can be predicted from sodium turnover once the concentration in feed and water consumed is known.

     

Food metabolizability and water balance in intact and cecectomized great-horned owls

• 1.1. In great-horned owls food metabolizability, food intake and body weight were not significantly affected by cecectomy.
• 2.2. Following cecectomy, water ingestion increased.

     

Metabolism in malleefowl (Leipoa ocellata)

• 1.1. Malleefowl Leipoa ocellata have a lower than predicted metabolic rate, a finding common to many arid adapted avian species.
• 2.2. Evaporative water loss was as expected by allometric analysis. However, in the wild this species probably reduces its evaporative water loss because their water turnover rate is extremely low.
• 3.3. Malleefowl coped with temperatures up to 40°C well, but above this temperature they become highly agitated.

     

A comparison of the effects of saline imbibition and water deprivation on the composition of the blood,urine and pituitary neural lobe of the gerbil (Meriones unguiculatus)

• 1.1. The effects of 2% saline imbibition and water deprivation on the water balance of the gerbil were compared.
• 2.2. The unchanged fluid intake and losses, body weight and several blood indices suggested little alteration in the state of hydration after saline imbibition.
• 3.3. After 5 days water deprivation the animals lost weight and evidence of haemoconcentration was observed. These changes took place despite reductions in water loss (via the urine and faeces) and evidence of secretion of vasopressin and the two principal acidic neural lobe proteins.
• 4.4. The gerbil appeared to be better adapted to water stress induced by saline imbibition than by water deprivation and this may be related to its habitat in Northern Asia.

     

Breast,hips, and buttocks revisited: Honest fatness for honest fitness

This paper comments on: Low, B. S., Alexander, R. D., and Noonan, K.M. Human hips, breast, and buttocks: Is fat deceptive? Ethology and Sociobiology 8: 249-247, 1987. In it I argue that:

• 1.1. Sexual selection has probably not been the most important selection pressure on
• 2.female human body shape.
• 3.2. Male humans in different cultures find different aspects of the female body attractive
• 4.and therefore are unlikely to have exerted consistent directional sexual selection on
• 5.the female body.
• 6.3. Breast size is not correlated with lactation success.
• 7.4. Visible hip width is not correlated with parturition success.
• 8.5. Women would lower their fitness if they tried to deceive men about their internal
• 9.pelvic dimensions.
• 10.6. There are many alternative hypothesis to explain the existence of fat onwomen's
• 11.breast, hips, and buttocks.

     

Effects of feeding on water balance and cutaneous drinking in the toad (Bufo bufo L.)

• 1.1. Toads fed mealworms ad libitum for 24-hr periods once a week retained water in the body in amounts that varied with meal size, as well as temporally.
• 2.2. The ratio between masses of water retained and mealworms eaten increased from about 0.5 in May to about 1.3 by mid-July, and declined again at the end of the seasonal feeding period. li[3. It is argued that this pattern reflects seasonal variation in the secretion of digestive (gastric) juice in response to meal size.
• 3.4. The cutaneous drinking response, reflected in number of visits to the water source, increased in strength with successive feedings.
• 4.5. It is suggested that the drinking response to feeding included a secondary, behavioural component, superimposed upon a primary response to feeding.

     

Changes in plasma corticosterone concentrations in the water-deprived fowl,Callus domesticus

• 1.1. Immature birds were deprived of water either by removing the source or denying them access.
• 2.2. Birds tended to become hypocorticosteronaemic when the water source was removed and hypercorticosteronaemic when access to the water was denied.
• 3.3. It is concluded that psychological factors are important in determining the response to putative Stressors.

     

Evaporative water loss and uptake in juvenile and adult Salamandra salamandra (L.) (Amphibia: Urodela)

• 1.1. Both juveniles and adults of this rare salamander were studied.
• 2.2. The rate of evaporative water loss increased with temperature and at lower humidities.
• 3.3. At all four temperatures and three humidities studied, adults lost water at a lower rate than juveniles.
• 4.4. Aggregating juveniles reduced water loss especially at lower moisture.
• 5.5. The rate of water uptake was greater in juveniles than in adults.
• 6.6. Juveniles were capable of absorbing moisture from moist soil even at 40% saturated soil.

     

Seasonal variation in the rate of evaporative water loss in the kangaroo rat,Dipodomys panamintinus

• 1.1. Evaporative water loss was measured as a function of temperature, season and grouping in the kangaroo rat, Dipodomys panamintinus for a one year period.
• 2.2. Three groups of Panamint kangaroo rats were set up and studied during the various changes in season. The three groups were designated as field, exposed and control. These groups revealed the effects of acclimatization, captive acclimatization and laboratory acclimatization respectively.
• 3.3. There is a highly significant difference in the rate of evaporative water loss in the Field Panamint kangaroo rats during the Fall, Winter and Spring.
• 4.4. In general, the quantity of water loss via evaporation was higher in the female Panamint kangaroo rats.
• 5.5. Water loss via evaporation in the control and exposed groups was least affected by seasonal change.
• 6.6. In comparison to the other two groups, the field male and female Panimint kangaroo rats possessed the highest slope (rate) and mean (quantity) for all seasons.
• 7.7. The combined effect of both grouping and season affects both the rate and quantity of evaporative water loss in the Panamint kangaroo rat.

     

Proteolysis post mortem in North Atlantic krill

• 1.1. The autoproteolytic processes in selected species of North Atlantic krill, Meganyctiphanes norvegica (M. Sars), Thysanoessa inermis (Krøyer) and T. raschii (M. Sars) have been examined at 0°C by following the release of peptides and free amino acids.
• 2.2. The krill contains high levels of peptide hydrolases, and autoproteolysis seems to be due mainly to digestive enzymes localized in the hepatopancreas and the intestinal tract of the animals.
• 3.3. During autoproteolysis the individual amino acids were generally released at rates corresponding to their proportion in the bulk protein of the krill. The major exceptions were alanine which accumulated in amounts larger than was to be expected from the composition of the krill protein, and glutamic acid/glutamine, aspartic acid/asparagine, arginine, and to some extent glycine, proline and serine, which accumulated to a lesser extent than was to be expected.
• 4.4. Storage of krill for 1 week resulted in only minor changes in the total content of amino acids as determined after acid hydrolysis, with the exception of alanine which increased in concentration.
• 5.5. The results suggest that the formation of free alanine is partly due to reactions other than proteolysis.
• 6.6. The release of free amino acids was accompanied by a considerable increase in the amount of small peptides, and glutamic acid/glutamine, aspartic acid/asparagine, glycine and proline tended to accumulate in these peptides.
• 7.7. The autoproteolytic activity of the Thysanoessa species showed seasonal variations, probably in response to food availability. In the case M. norvegica, the results suggest that there are smaller fluctuations in the level of proteolytic enzymes, probably indicating less pronounced variations in the food intake over the year.

     

Cardiac responses of larval and adult tiger salamanders to submergence and emergence

• 1.1. The ECG of aquatic Amhystoma tigrinum from the Colorado Rocky Mountains was recorded while the animals submerged and emerged in water. Older larvae and metamorphosed adults were compared.
• 2.2. Free-swimming animals of both types showed slight emergence tachycardia when taking a “gulp” of air.
• 3.3. Preventing access to air for 30 min or more resulted in a slight bradycardia in larvae. Some adults responded with increased, others with decreased, heart rate depending on their level of excitement.
• 4.4. Restraining the animals before forced submergence caused a greater bradycardia than when unrestrained.
• 5.5. Low dissolved oxygen accentuated the cardiac responses of larvae to submergence but not in adults.
• 6.6. Atropine only partially blocked the diving responses of both forms.
• 7.7. The degree of submergence bradycardia seems to be a function of the ability to extract oxygen from water. It probably is not an adaptation to diving in these forms. Instead the submerged heart rate in these predominantly aquatic salamanders may be the “normal” rate with emergence tachycardias for breaths of air.

     

Sea water drinking as a homeostatic response to dehydration in hatchling loggerhead turtles Caretta caretta

• 1.1. Hatching Caretta caretta may lose up to 12% of their initial hatched weight from water loss during emergence from the nest.
• 2.2. After subsequent osmotic and excretory water loss in sea water, hatchlings will drink sea water (166 μl 100 g⁻¹ hr⁻¹) and return to their initial weight within 10–15 days, without feeding.
• 3.3. There were no significant changes in plasma osmolarity or sodium levels over this period.
• 4.4. This osmoregulatory strategy is in marked contrast to that seen in the estuarine crocodile, Crocodylus porosus.

     

Comparative water balance in two species of Liomys (Rodentia: Heteromyidae)

• 1.1. Water metabolism in Liomys irroratus and L. pictus was studied by measuring water loss and gain by several routes.
• 2.2. Urine concentrations and fecal water contents were similar in the two species; L. pictus experiences significantly higher evaporative water loss than does L. irroratus.
• 3.3. Observed differences in water loss between the two species are largely a function of parameters related to weight-specific metabolic rate; the differential water losses are offset by differences in metabolic water production and ease of obtaining free water, so that the two species appear equally capable of attaining water balance.
• 4.4. The physiological characteristics of these two species are discussed relative to their respective ecological distributions and to a current hypothesis about the evolution of Liomys.

     

Role of the visceral nerve in heart rate variations during different behavioral patterns in Megalobulimus sanctipauli (mollusca,gastropoda, pulmonata)

• 1.1. The role of the visceral nerve in mediating the changes in heart rate associated with different behavioral patterns was investigated in Megalobulimus sanctipauli.
• 2.2. The results of acute and chronic denervation experiments indicate that the visceral nerve has no excitatory or inhibitory tonic action on the heart of snails retracted into the shell, nor does it account for the increase in heart rate associated with the locomotion and feeding behaviors.
• 3.3. These changes in heart rate are, probably, indirect effects of increased activity such as an increase in venous return.
• 4.4. The visceral nerve is responsible for approximately 3/4 of the increase in heart rate associated with the first minute of extrusion.
• 5.5. The small increase in heart rate observed in denervated animals is probably caused by an increase in venous return generated by muscle activity that forces the head and food out of the shell.

     

Protein,fatty acids,calcium and phosphate absorption along the gastrointestinal tract of the young turkey

• 1.1. The net absorption of protein, fatty acids, calcium and phosphate along the small intestine of the turkey (Meleagris gallopovo) was evaluated with the aid of ⁹¹Y as a reference substance.
• 2.2. About 85% of the ingested protein was absorbed, with most of the absorption occurring in the duodenum and upper jejunum.
• 3.3. The overall lipid absorption coefficient was around 90%, and was inversely related to the fatty acid chain length and saturation.
• 4.4. Most of the lipid absorption occurred in the duodenum and jejunum.
• 5.5. Calcium absorption also occurred in the duodenum and jejunum: its fractional rate decreased with calcium intake.
• 6.6. Phosphate absorption occurred mostly in the duodenum and jejunum and its efficacy was only slightly affected by dietary phosphate intake.
• 7.7. The high nutrient absorption in the turkey duodenum, relative to that of the chick (Gallus domesticus), was discussed.

     

Biochemical and physiological aspects of anhydrobiosis

• 1.1. The biochemical and physiological mechanisms which are involved in anhydrobiotic survival have been reviewed.
• 2.2. The physical state of water within hydrated and dehydrated organisms is discussed in relation to the concepts of “free” and “bound” water and to the “vicinal water network model” of Clegg (1979) Cell Associated Water. Academic Press, New York.
• 3.3. Evidence is presented for the replacement of “bound” water by glycerol in dried embryos of Artemia salina, but the role of high glycerol content in the free-living nematode Aphelenchus avenae has yet to be evaluated.
• 4.4. The adaptive significance of trehalose is shown to lie in the fact that because it is a non-reducing sugar, it will not participate in a “browing” reaction between reduced groups of sugars and free amino groups of dry proteins. Trehalose also inhibits “browning” reactions between reducing sugars and dry proteins.
• 5.5. The effect of dehydration on membrane permeability suggests that dried organisms suffer mostly if placed directly into a revival medium due to leakage through structurally deformed membrane systems.
• 6.6. Glycerol and trehalose may interact with lipid membranes and reduce the amount of leakage.
• 7.7. Damage to membranes caused by lipid peroxidation is discussed.
• 8.8. Results suggest that the role of high lipid contents in nematode anhydrobiotes is essentially that of a food reserve, although the morphological distribution of such lipid may be important in maintaining the spatial distribution of body tissues in the absence of bulk water.

     

Water loss in Anolis lizards: evidence for acclimation and intraspecific differences along a habitat gradieNT

• 1.1. Rates of evaporative water loss (EWL) were measured in Anolis roquet and A. marmoratus each from three localities which varied in conditions of aridity.
• 2.2. There were significant interpopulational differences in rates of EWL for both species which correlated with habitat aridity.
• 3.3. Rates of EWL were significantly lower in A. roquet after 6 weeks acclimation to more xeric conditions, populational differences were still evident.
• 4.4. Acclimational effects on rates of EWL were 2 to 3 times greater than populational differences.