[TIPE]l'imperméabilité des poils et des plumes

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Voila mon sujet de TIPE pour cette année. Mes problèmes du moment sont :
- comment déterminer ce que contient une glande uropygienne? (on sait déja qu'il y a des cérides (lipides) et de la vitamine A)
- où est-ce que je peux récupérer des poils en grande quantité avec la racine de préférence (a part en piquant un vison a une vieille)? Il me faudrait notamment des poils d'un animal aquatique (type loutre, ragondin, castor...) pour comparer avec ceux d'un chien par exemple.
- comment mesurer précisément un angle entre une plume et une goutte d'eau?
- vous avez des idées d'expériences a faire avec des poils pour les rendre imperméable ou perméables?

Merci a ceux qui répondront
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http://elibrary.unm.edu/sora/Auk/v10...0140-p0142.pdf

http://elibrary.unm.edu/sora/Auk/v10...0371-p0383.pdf

Avian Epidermal Lipids: Functional Considerations and Relationship to Feathering1
Issn: 0003-1569 Journal: American Zoologist Volume: 40 Issue: 4 Pages: 540-552
Authors: Menon, Gopinathan K., Menon, Jaishri
DOI: 10.1043/0003-1569(2000)040<0540:AELFCA>2.0. CO;2


ABSTRACT

The avian epidermis is composed of unique sebokeratinocytes that elaborate and secrete sebum-like lipids as they cornify. In addition to the lipid droplets, the avian epidermis elaborates, but rarely secretes, lipid—enriched organelles, the multigranular bodies. The multigranular bodies are analogous to the lamellar bodies of mammals (Menon et al., 1991), the secretion of which results in formation of occlusive lipid bilayers characteristic of mammalian stratum corneum and providing the permeability barrier. However, in contrast to mammals, the avian multigranular bodies form the reserve barrier mechanism. In the basal state, when multigranular bodies are not secreted, the avian cutaneous barrier is deficient, but allows evaporative cooling for thermoregulation. However, under conditions of water deficit, multigranular body secretion allows for rapid facultative waterproofing, as shown in zebra finches (Taenyopygia guttata). In certain glabrous regions of the skin, such as the maxillary rictus, interdigital web, and combs and wattles in the domestic fowl, there is a high degree of epidermal lipid secretion. Also specialized feathers such as powder downs elaborate lipid rich material, which can be classified as secretion. Additionally, an inverse relation between epidermal lipogenesis and the degree of feathering has been demonstrated, as in temporarily bare areas (e.g., brood patches) and following permanent feather loss from the head accompanying attainment of maturity in certain ibises and storks. In the latter, the neo-apteria often hold large reserves of carotenoids dissolved in the lipid droplets, possibly related to an altered gradient of retinoids influencing feather morphogenesis. Unusual secondary functions of epidermal lipids include cosmetic coloration (e.g., in the Japanese Crested Ibis) and chemical defense (e.g., in the Pitohui).


http://www3.interscience.wiley.com/c...90873/ABSTRACT

voilà ce qu'une rechercher rapide donne.

bonne lecture...