Rates Of Cutaneous Water Loss Research Articles

Nature or Nurture: Can Prey-Based Diets Influence Species-Specific Physiological Performance Traits of Epidermal Lipid Content and Cutaneous Water Loss?

Epidermal lipids serve as the primary barrier to cutaneous water loss (CWL) and play a significant role in water conservation and homeostasis. Previous studies have shown the correlation between increased aridity of habitats and the amount of epidermal lipids among species. Generally, increased amounts of epidermal lipids lower skin permeability. Species-specific differences in CWL and prey preferences between two sympatric snake species, the Northern Cottonmouth (Agkistrodon piscivorus) and the Eastern Copperhead (Agkistrodon contortrix), motivated us to question if prey-base can result in these observed species-specific differences in CWL. We experimentally controlled the diets for a captive colony of Northern Cottonmouths (A. piscivorus) by feeding either fish (Notemigonus crysoleucas) or mice (Mus musculus) to investigate if diet can affect the quantity and quality of epidermal lipids and the rates of CWL. Snakes fed mice gained consistently more mass, but diet treatments did not affect growth rate. We found no significant differences in quantitative lipid content or rates of CWL between diet treatments. An analysis for qualitative lipid content using infrared spectrophotometry also showed no diet effect, thus suggesting that lipid content and CWL are strong species-specific physiological performance traits not influenced by recent dietary history. While there is some evidence that epidermal permeability may be variable under certain environmental conditions (e.g., humidity), our findings show that diet has no effect and that a shift in prey preference may not influence or enhance physiological performance for decreasing CWL.

Variation and repeatability of cutaneous water loss and skin resistance in relation to temperature and diel variation in the lizard Sceloporus consobrinus.

Variation in rates of water loss has been proposed to be an important mechanism in the survival of terrestrial organisms, as high rates of water loss in desiccating environments may lead to hydric stress and death. Vapor density deficit, the driving force for evaporative water loss, increases exponentially as temperature increases. Acute temperature changes may be the result of daily behavioral thermoregulation of ectotherms, which may influence the among individual variation rates of water loss. The goals of this study were to determine (1) how rates of cutaneous water loss (CWL) and skin resistance (Rs) are affected by acute temperature acclimation, (2) how rates of CWL and Rs vary throughout the day allowing behavioral thermoregulation and (3) the repeatability of CWL and Rs within and among sampling periods. We measured CWL and calculated skin resistance (Rs) of 30 male Sceloporus consobrinus lizards across three summers. We measured CWL on the dorsal and ventral surface of each lizard at 23°C followed by measurements at 35°C, and three separate times throughout the day. We found a significant increase in Rs and decrease in CWL at increased acclimation temperatures (35°C), a significant difference in CWL and Rs throughout the day allowing behavioral thermoregulation, and support for the repeatability of CWL and Rs. Our results demonstrate variability in CWL and Rs in relation to temperature acclimation and thermoregulation, but mixed evidence for repeatability across treatments. Our results suggest other factors, such as peripheral blood flow, may be influencing the inter-individual variation in CWL and Rs.

Interfacial properties of avian stratum corneum monolayers investigated by Brewster angle microscopy and vibrational sum frequency generation

The outermost layer of skin, the stratum corneum (SC), contains a complex mixture of lipids, which controls the rate of cutaneous water loss (CWL) in reptiles, mammals, and birds. However, the molecular structure of SC lipids and how molecular configurations influence CWL is poorly understood. Here, the organization and structure of SC lipids extracted from birds were investigated by means of Langmuir films. Properties of lipids from the SC of arid and semi-arid adapted larks, known to have a low CWL, were compared with lipids extracted from the SC of mesic lark species with higher CWL to gain insight into how structure impacts CWL. Film properties were probed with surface pressure-area isotherms, Brewster angle microscopy (BAM), and vibrational sum frequency generation (VSFG). Results indicate organization and ordering of SC lipids in the arid-adapted hoopoe lark was vastly different from all other species, forming a miscible, rigid monolayer, whereas monolayers from semi-arid and mesic species were immiscible and disordered. Probing of interfacial water structure reveals that film morphology determines organization of water molecules near the monolayer; monolayers with a porous morphology had an increased population of water molecules that are weakly hydrogen-bonded. In general, CWL appears related to the miscibility and ordering of lipid components within the SC, as well as the ability of these lipids to interact with water molecules. From a broader perspective, CWL in larks appears linked to both the SC lipid composition and the aridity of the species’ environment.

Cutaneous Water Loss and Epidermal Lipids in Two Sympatric and Congeneric Pitvipers

We examined comparative skin permeability by measuring cutaneous water loss and epidermal lipid content of two sympatric snake congeners, the Southern Copperhead (Agkistrodon contortrix) and the Western Cottonmouth (A. piscivorus). Samples of shed epidermis from each snake species were taken to first investigate species-specific differences. Shed samples from multiple regions along the dorsal and ventral integument were then used to examine potential variation in skin permeability and lipid content among different regions along the body for each species. Rates of cutaneous water loss were significantly higher for A. piscivorus. In addition, cutaneous water loss rates of A. piscivorus differed among region (i.e., anterior, mid, and posterior) and surface (i.e., dorsal and ventral) with the highest rates of cutaneous water loss from the mid-dorsum. Lipid content did not differ between species. However, lipid content varied between the dorsal and ventral surfaces of both species, with greater lipid content on the dorsal surface. Our results support a species-specific difference in cutaneous water loss between A. contortrix and A. piscivorus and may reflect species-specific adaptations to their differences in microhabitat preference.

Cutaneous water loss and covalently bound lipids of the stratum corneum in nestling house sparrows (Passer domesticus L.) from desert and mesic habitats

Lipids of the stratum corneum (SC), the outer layer of the epidermis of birds and mammals, provide a barrier to water vapor diffusion through the skin. The SC of birds consists of flat dead cells, called corneocytes, and two lipid compartments: an intercellular matrix and a monolayer of covalently bound lipids (CBLs) attached to the outer surface of the corneocytes. We previously found two classes of sphingolipids, ceramides and cerebrosides, covalently bound to corneocytes in the SC of house sparrows (Passer domesticus L.); these lipids were associated with cutaneous water loss (CWL). In this study, we collected adult and nestling house sparrows from Ohio and nestlings from Saudi Arabia, acclimated them to either high or low humidity, and measured their rates of CWL. We also measured CWL for natural populations of nestlings from Ohio and Saudi Arabia, beginning when chicks were 2 days old until they fledged. We then evaluated the composition of the CBLs of the SC of sparrows using thin layer chromatography. We found that adult house sparrows had a greater diversity of CBLs in their SC than previously described. During ontogeny, nestling sparrows increased the amount of CBLs and developed their CBLs differently, depending on their habitat. Acclimating nestlings to different humidity regimes did not alter the ontogeny of the CBLs, suggesting that these lipids represent a fundamental component of SC organization that does not respond to short-term environmental change.

Cutaneous Water Loss and the Development of the Stratum Corneum of Nestling House Sparrows (Passer domesticus) from Desert and Mesic Environments

Evaporation through the skin contributes to more than half of the total water loss in birds. Therefore, we expect the regulation of cutaneous water loss (CWL) to be crucial for birds, especially those that live in deserts, to maintain a normal state of hydration. Previous studies in adult birds showed that modifications of the lipid composition of the stratum corneum (SC), the outer layer of the epidermis, were associated with changes in rates of CWL. However, few studies have examined the ontogeny of CWL and the lipids of the SC in nestling birds. In this study, we measured CWL and the lipid composition of the SC during development of nestlings from two populations of house sparrows, one from the deserts of Saudi Arabia and the other from mesic Ohio. We found that desert and mesic nestlings followed different developmental trajectories for CWL. Desert nestlings seemed to make a more frugal use of water than did mesic nestlings. To regulate CWL, nestlings appeared to modify the lipid composition of the SC during ontogeny. Our results also suggest a tighter regulation of CWL in desert nestlings, presumably as a result of the stronger selection pressures to which nestlings are exposed in deserts.

Cutaneous Water Loss and Lipids of the Stratum Corneum in Dusky Antbirds, a Lowland Tropical Bird

AbstractAbstractThe stratum corneum, the outer layer of the epidermis, consists of flattened cells embedded in a matrix of lipids, primarily cholesterol, free fatty acids, ceramides, and cerebrosides. The stratum corneum forms a barrier to water vapor diffusion through the skin. In birds, the skin limits excessive water loss at thermoneutral temperatures, but also serves as a vehicle for thermoregulation during episodes of heat stress. We measured total evaporative water loss, cutaneous water loss, and lipids in the stratum corneum in Dusky Antbirds (Cercomacra tyrannina), the first such measurements ever made for birds living in tropical rain forests. We predicted that these birds would have high rates of cutaneous water loss because of their need to thermoregulate rather than to conserve water. We found that Dusky Antbirds lose twice as much water through their skin as birds from temperate environments. We also hypothesized that the proportion of cerebrosides in the stratum corneum would increase relative to that of ceramides if Dusky Antbirds use their skin as a thermoregulatory organ. However, we found that Dusky Antbirds did not show different proportions of ceramides and cerebrosides in the stratum corneum than other species of birds. We also found that Dusky Antbirds had low amounts of free fatty acids in their stratum corneum. Overall, our data support the idea that the interactions of the lipids in the stratum corneum may play an important role in determining rates of water vapor diffusion through the skin.

CUTANEOUS WATER LOSS AND LIPIDS OF THE STRATUM CORNEUM IN DUSKY ANTBIRDS, A LOWLAND TROPICAL BIRD

Abstract ABSTRACT The stratum corneum, the outer layer of the epidermis, consists of flattened cells embedded in a matrix of lipids, primarily cholesterol, free fatty acids, ceramides, and cerebrosides. The stratum corneum forms a barrier to water vapor diffusion through the skin. In birds, the skin limits excessive water loss at thermoneutral temperatures, but also serves as a vehicle for thermoregulation during episodes of heat stress. We measured total evaporative water loss, cutaneous water loss, and lipids in the stratum corneum in Dusky Antbirds (Cercomacra tyrannina), the first such measurements ever made for birds living in tropical rain forests. We predicted that these birds would have high rates of cutaneous water loss because of their need to thermoregulate rather than to conserve water. We found that Dusky Antbirds lose twice as much water through their skin as birds from temperate environments. We also hypothesized that the proportion of cerebrosides in the stratum corneum would increase rela...

SKIN RESISTANCE TO EVAPORATIVE WATER LOSS IN REPTILES:A PHYSIOLOGICAL ADAPTIVE MECHANISM TO ENVIRONMENTAL STRESS OR A PHYLETICALLY DICTATED TRAIT?

Rates of cutaneous water loss, Ec, in terrestrial reptiles may be affected by the temperature and humidity prevailing in the habitat, by the activity pattern of the reptile, and by the taxonomic position of the species. To find out whether variations in Ec are due mainly to the physical conditions characterizing a particular habitat, or whether they are better attributed to taxonomic position, Ec and skin resistance to water loss (Rs) were compared among eight snake species of the families Colubridae and Viperidae, and among five lizard species of the genus Agama (family Agamidae). These species inhabit different climatic regions (from mesic-Mediterranean to dry and hot desert) and habitats (semi-aquatic and terrestrial) in Israel, and have different daily activity (diurnal and crepuscular-nocturnal). In addition, intraspecific Ec and Rswere measured in nine insular populations of the arboreal lizard Anoliscristatellus (family Polychridae) in the British Virgin Islands. This species is found in habitats r...

Skin resistance to water loss in colubrid snakes: Ecological and taxonomical correlations

:Rates of cutaneous water loss (CWL) in terrestrial snakes may be affected by the temperature and humidity prevailing in the habitat, the activity pattern of the snake, and the taxonomic position of the species. To find out whether variation in snake CWL is mainly due to the physical conditions characterizing a particular habitat, or whether it is better attributed to taxonomic position, we measured CWL and skin resistance to water loss (Rs) in four species of colubrid snakes. These species inhabit different climatic regions (from mesic Mediterranean to dry and hot desert) and habitats (semi-aquatic and terrestrial), and have different daily activities (diurnal and crepuscular-nocturnal). CWL and Rs were correlated more with aridity of habitat rather than with taxonomy. CWL rates of the non-desert species were higher, and their Rs lower than those obtained from desert species. The highest rates of CWL (0.98 mg cm−2 h−1) and the lowest Rs (117 s cm−1) were found in the water snake Natrix tessellata, whereas the lowest CWL (0.13 mg cm−2 h−1) and the highest Rs (1088 s cm−1) were found in the stripeless form of Psammophis schokari, which inhabits desert biotopes. Intermediate values were found in Coluber rubriceps and the striped form of Psammophis, both inhabiting mesic Mediterranean areas. CWL and Rs of Spalerosophis diadema,a species inhabiting arid desert biotopes, were not significantly different from those of the semi-aquatic Natrix. The apparent discrepancy between the low Rs found in Spalerosophis and the high aridity of its habitat can be attributed to the crepuscular-nocturnal activity of this species. The environmental conditions to which Spalerosophis is exposed during its activity in the desert nights are milder and much more moderate than those encountered by diurnal snakes. CWL and Rs reflect, therefore, not the apparent aridity of the habitat but the real ecological niche of the species, i.e.,the actual climatic conditions prevailing during the activity time of the species.

Skin resistance to water loss in agamid lizards.

Many desert lizards show reduced rates of cutaneous water loss (CWL) compared to their counterparts from more humid environments. It is not clear yet whether reduced CWL is connected to the taxonomic position of the lizard studied, or is affected more by environmental or experimental conditions. To investigate this, we measured the skin resistance to water transfer, R s, in five closely related lizard taxa of the genus Agama. These diurnal lizards are distributed in Israel from mesic-Mediterranean to extreme desert biotopes. The highest R s (738 s cm-1) and the lowest CWL (0.160 mg cm-2 h-1) were found in Agama sinaita, which lives in the most arid habitat. The lowest R s (234 s cm-1) and the highest CWL (0.548 mg cm-2 h-1) were found in A. stellio ssp., which occupies mesic habitats. In addition, only the desert species were able to change their R s in accordance with the changing experimental conditions. These R s changes, which probably reflect vasomotor responses, were more pronounced in A. sinaita and presumably enable the desert species to control their CWL in a hot and dry environment.

Zonulae occludentes in the epidermis of the snake Natrix natrix L.

Zonulae occludentes of a very tight type were identified between the uppermost stratum germinativum cells of the grass snake Natrix natrix L. by means of the lanthanum tracer technique. Since zonulae occludentes alone are not capable of preventing transepithelial water flow, an additional barrier mechanism is postulated, responsible for the low rates of cutaneous water loss measured in squamate reptiles. It is suggested that the observed zonulae occludentes are involved in the sloughing process.

Water loss and oxygen consumption in tropical Sphaerodactylus.

Rates of evaporative water loss and oxygen consumption were measured for the 0.37 g gekkonid lizard, Sphaerodactylus beattyi, and the results compared with those reported previously for a 0.45 g form, S. macrolepis, (Snyder, 1975). Water loss for S. beattyi was 37% lower than for S. macrolepis and the difference was accounted for by a lower rate of cutaneous water loss. Rates of respiratory water loss and oxygen consumption were comparable for the two species. The two species are parapatric on the island of St. Croix and the differences in rates of water loss are reflected in their ecologic distribution on the island.

Adaptations to ambient temperature in growing pigs.

1. Pigs were weaned at 8--10 dyas of age and littermate pairs were raised in individual cages at ambient temperatures of 25 degrees C or 35 degrees C to 8 weeks of age. 2. Pigs reared at the higher temperature had longer extremities and less hair than controls even though body weights were similar. 3. On exposure to an ambient temperature of 45 degrees C, thce as quickly as their littermates. 4. When the scrotum was heated locally to 42 degrees C animals reared in the warmer environment began to pant at a lower ambient temperature than the controls. 5. Heating the hypothalamus by means of an implanted thermode at an ambient temperature of 35 degrees C was accompanied by an increase in respiratory frequency in pigs reared at 25 degrees C. The pigs reared at 35 degrees C already had a slightly elevated rate of breathing and heating the hypothalamus caused no change. 6. The rate of blood flow in the tail was higher in pigs reared at 25 degrees C than those kept at 35 degrees C when measured at ambient temperatures between 20 degrees C and 35 degrees C. When the hypothalamus was cooled the slope of the line relating blood flow to the temperature of the thermode was similar in both groups. 7. The critical temperature as determined from measurements of oxygen consumption was higher in the pigs reared at 35 degrees C than in controls. But the effect of cooling the hypothalamus on metabolism was similar in both groups. 8. There was no difference between the two groups in the rate of cutaneous water loss.

The effect of antidiuretic hormone on human sweating

1. Changes in insensible perspiration and sweating were followed in normal subjects by continuously monitoring total body weight loss in environmental temperatures of 18, 29 and 37 degrees C.2. Pharmacological doses of ADH had no effect on cutaneous water loss at 18 degrees C.3. Pharmacological doses of ADH are capable of increasing the rate of cutaneous water loss in human subjects who are close to or above the thermal sweating threshold.4. Physiological doses of ADH had no effect on cutaneous water loss in either cool or hot environments.5. At normal rates of secretion in the body, ADH probably does not influence human sweat secretion.

Stimulation of cutaneous glands in the pig

Summary The ability of the apocrine-like glands in the pig's skin to respond to thermal stimulation has been tested using the sweat capsule and the starch iodine techniques. No evidence of thermal sweating was obtained. The glands responded to adrenaline, noradrenaline, histamine and 5-hydroxy-tryptamine as well as to electrical stimulation of the sympathetic chain, although the response was very variable. No response was obtained with acetylcholine. Histological investigation revealed that the opening of the duct to the glands was always partly blocked by a plug of keratin, but this plug was still present after the glands had been made to discharge in response to adrenaline. Acclimatization to 15¼C and 35¼C. had no effect on the rate of cutaneous water loss in a hot environment, but the response to adrenaline was more marked in the pigs which had been kept at the lower temperature.