Surface sculpturing and water retention of elephant skin

LlLLYWHITE, H. B.; Stein, Barbara R.

doi:10.1111/j.1469-7998.1987.tb04483.x

Cited by 49 publications

(46 citation statements)

References 21 publications

(26 reference statements)

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“…All of these behaviors would reduce the intake of evaporated relative to unevaporated waters. The proximity to water sources, large body size, skin that adsorbs water and mud, and wallowing behaviors of many EI animals may provide additional explanations for the isotopic buffering of EI animals from increased aridity (23,25). A combination of variables that affect the 18 (Figs.…”

Section: Discussionmentioning

confidence: 99%

A stable isotope aridity index for terrestrial environments

Levin

Cerling

Passey

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

376

308

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We use the oxygen isotopic composition of tooth enamel from multiple mammalian taxa across eastern Africa to present a proxy for aridity. Here we report tooth enamel ␦ 18 O values of 14 species from 18 locations and classify them according to their isotopic sensitivity to environmental aridity. The species are placed into two groups, evaporation sensitive (ES) and evaporation insensitive (EI bioapatite ͉ East Africa ͉ oxygen-18 ͉ mammals ͉ water use T errestrial responses to major climate changes, such as glaciations, orogenic events, and shifts in ocean circulation, are often characterized in terms of water availability or aridity (1-3). Although aridity proxies exist for different terrestrial settings (4-6), they are not applicable in every circumstance and additional proxies must be developed for further study of terrestrial environmental change. The 18 O composition of bioapatite has been used as a proxy for rainfall ␦ 18 O and seasonality of past environments (7, 8), but its utility in paleoenvironmental problems is limited by the complexity of climatic, environmental, physiological, and behavioral variables that influence bioapatite ␦ 18 O values. The correlation between bioapatite ␦ 18 O values and both meteoric water ␦18 O values and relative humidity demonstrate that animals have different isotopic responses to environmental change (7,9,10). In this study, we present tooth enamel ␦ 18 O data of 14 mammal species sampled from 18 locations in eastern Africa, which represent a gradient in environmental aridity. This data set shows that the tooth enamel ␦18 O values of some species vary with aridity whereas those of other species track the 18 O composition of meteoric water. We use the different isotopic responses of the sampled species as the empirical basis for an aridity proxy. ResultsThere is a marked increase in water deficit (WD) from the closed canopy Ituri Forest in the Democratic Republic of Congo to the arid shrublands of Lake Turkana in northern Kenya (Table 1, which is published as supporting information on the PNAS web site). WD in these regions negatively correlates to mean annual relative humidity (RH) (P Ͻ 0.01) and is used as a measure of aridity. Although previous studies compare bioapatite ␦18 O values with RH (6, 9, 10), RH data are not used here because they are not available for all study locations. (Fig. 1). Baboons from Mpala are the only mixed (C 3 -C 4 ) feeding baboons (otherwise C 3 browsers), and when not considered the baboon regression has a P value Ͻ0.001 instead of 0.14. enamel-mw of a second group, giraffids (Giraffa camelopardalis and Okapia johnstoni), oryx (Oryx beisa), dikdik (Madoqua kirkii), Grant's gazelle (Gazella granti), and buffalo (Syncerus caffer), increases with WD (P values range from Ͻ0.001 to 0.08) (Fig. 2 a-e). The regression coefficients (slopes) of the second group do not vary significantly from each other (P Ͼ 0.1, F test). DiscussionThe Evaporation Sensitive (ES)-Evaporation Insensitive (EI) Distinction. The regressions between WD and enamel-mw show t...

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Section: Discussionmentioning

confidence: 99%

A stable isotope aridity index for terrestrial environments

Levin

Cerling

Passey

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

376

308

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“…Grooves at the surface of materials retain water [33,34], and the trapping of moisture and dirt in the grooves of profiled wooden deckboards concerned Morris and Ingram [20] who mentioned its potential to affect the durability of boards. Morris and Ingram tested this hypothesis by assigning decay ratings to unprofiled and profiled subalpine fir decking that had been exposed to the weather in Vancouver for 10 years [20].…”

Section: Discussionmentioning

confidence: 99%

Manufacture of Profiled Amabilis Fir Deckboards with Reduced Susceptibility to Surface Checking

Cheng

Evans

2018

JMMP

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Machining grooves and ridges (peaks) into the surface of wooden deckboards reduces undesirable checking that develops when "profiled" boards are exposed to the weather. We aim to develop improved profiles for amabilis fir decking to reduce its susceptibility to checking, and also to examine whether profiling influences distortion (cupping) of deckboards. We systematically varied radii of grooves and peaks, and the heights and widths of peaks in profiled deckboards, exposed them to the weather, and measured checking and cupping of boards. Profiling significantly reduced the numbers and sizes of checks in amabilis fir deckboards, but increased cupping. Profiles with narrow grooves and tall peaks were generally better at restricting checking than profiles with wide grooves and shorter peaks. Our results suggest that one of the profiles we tested would be better at restricting checking than profiles used previously to manufacture profiled decking from amabilis fir. We conclude that the surface checking of profiled amabilis fir decking can be significantly reduced by altering the geometry of surface profiles. In principal, the same approach could be used with other softwood species that have potential to capture a share of the large and important market for wood decking.

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“…In this context, the production of glycolipids, independent of a dry and hot climate, likewise seems to proceed slowly, and our results corroborate the view of a constant disposability of glycolipid amounts in all cells of the vital epidermis as general protection against water loss. Such effect may be supported by a specific surface sculpturing of the integument in elephants, particularly in the African species, which helps to enhance retention of surface moisture, thereby impeding strong dehydration (Lillywhite and Stein 1987). In the two semiaquatic or aquatic species, respectively, the conditions against water loss are completely different, realising also that the stratum corneum is not as loosely structured as in the elephant.…”

Section: Discussionmentioning

confidence: 99%

Basic structural and functional characteristics of the epidermal barrier in wild mammals living in different habitats and climates

et al. 2011

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Based on the combination of standard light and transmission electron microscopy, cryo-SEM, immunohistochemistry and a new sensitive glycolipid histochemical technique (5-hexadecanoylaminofluorescein staining, laser scanning microscopy), including densitometrical evaluation, our approach gives for the first time an overview of the specific biology of the epidermal permeability barrier in wild mammals (20 species from five orders), living under varying (aquatic or moist to dry) habitat conditions. The results obtained emphasised that the barrier region in most of the species studied is a continuous zone (thickness, 0.1 and 3 μm) between the upper cells of the stratum granulosum and the inner cells of the stratum corneum conjunctum, normally present as a homogeneous glycolipid layer originating from fusion of lamellar body contents after exocytotic activities of the granular cells. However, this finding did not apply to all of the species studied, i.e., the Wild boar, the Common seal and the three large species with a very thick vital epidermis, the African elephant, the hippopotamus and the common dolphin, exhibited variations from the basic scheme. Densitometric evaluation of the 5-hexadecanoylaminofluorescein staining revealed that reaction intensity was not only generally related to the habitat conditions but also to vital epidermis thickness and hair density. The immunohistochemical demonstration of Na + /H + exchanger 1 corroborated for all wild mammals studied that this important regulator of pH conditions during barrier formation is continuously produced in the epidermis. The variations in barrier biology observed for some species obviously had to be developed in relation to animal size (or body size area) and hair coat density, but, particularly, by the specific adaptation of certain mammalian groups to the aquatic environment. In the latter case, the typical barrier zone system was lost, as in the hippopotamus or the cetaceans.

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Surface sculpturing and water retention of elephant skin

Cited by 49 publications

References 21 publications

A stable isotope aridity index for terrestrial environments

A stable isotope aridity index for terrestrial environments

Manufacture of Profiled Amabilis Fir Deckboards with Reduced Susceptibility to Surface Checking

Basic structural and functional characteristics of the epidermal barrier in wild mammals living in different habitats and climates

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