Cutaneous water loss and lipids of the stratum corneum in house sparrowsPasser domesticusfrom arid and mesic environments

Abstract

·SC·dry·mass in Ohio), and a lower percentage of cholesterol (4.1±3.6% in Saudi Arabia; 5.4±2.5% in Ohio) in their SC.Although CWL was lower in sparrows from Arabia, and lipid composition of their SC differed, we could not detect differences between rates of water loss through non-living skin attached to glass vials (46.0±15.7·mg·H 2 O·cm -2 ·day -1 for sparrows in Saudi Arabia; 45.8±27.2·mg·H 2 O·cm -2 ·day -1 for sparrows in Ohio). These results suggest that biological control mechanisms interact with layers of lipids in the stratum corneum to adjust CWL to the environment.

Physiological regulation of evaporative water loss in endotherms: is the little red kaluta (Dasykaluta rosamondae) an exception or the rule?

“…Potential mechanisms for decreasing EWL at high Dwvp will depend on the relative partitioning of cutaneous and respiratory avenues of EWL, and may include decreased cutaneous EWL, e.g. by modification of skin lipids [30][31][32], and/or reduced respiratory EWL, e.g. by lowered expired air temperature by nasal counter-current heat and water exchange [25,[33][34][35][36].…”

Developmental plasticity of cutaneous water loss and lipid composition in stratum corneum of desert and mesic nestling house sparrows

“…Desert individuals had a lower CWL, a lower proportion of FFA, and a higher proportion of ceramides and cerebrosides in the SC than birds from Ohio (13). These changes could be the result of genetic differences between populations, of phenotypic flexibility of adults, of developmental plasticity of young, or a combination of these.…”

“…The SC is formed by flattened dead cells, called corneocytes, embedded in an extracellular lipid matrix consisting of cholesterol, free fatty acids (FFA), ceramides (a sphingosine molecule ester bonded to a fatty acid) and cerebrosides (a ceramide molecule attached to a hexose). Studies on the SC of larks, house sparrows, and several species of tropical birds suggest that changes in the proportions of FFA and ceramides in the extracellular matrix of the SC influence rates of CWL (11,13,14). Desert birds have a lower percentage of FFA and a higher percentage of ceramides in the SC than birds from mesic environments, a relationship observed across and within species (11,13).…”

“…Variation in CWL is thought to be primarily mediated by alteration in lipid composition of SC (11)(12)(13)(14). The SC is formed by flattened dead cells, called corneocytes, embedded in an extracellular lipid matrix consisting of cholesterol, free fatty acids (FFA), ceramides (a sphingosine molecule ester bonded to a fatty acid) and cerebrosides (a ceramide molecule attached to a hexose).…”

“…Studies on the SC of larks, house sparrows, and several species of tropical birds suggest that changes in the proportions of FFA and ceramides in the extracellular matrix of the SC influence rates of CWL (11,13,14). Desert birds have a lower percentage of FFA and a higher percentage of ceramides in the SC than birds from mesic environments, a relationship observed across and within species (11,13). Changes in the ratios of lipid classes in the SC might influence CWL in birds (14).…”