Changes in the Matrix Proteins of Wool and Mouse Hair Following the Administration of Depilatory Compounds

Abstract

After sheep were defieeced with mimosine, cyclophosphamide or N-[5-(4-aminophenoxy)pentyl]-phthalimide, the first samples of the new growth of wool differed markedly in composition from the pretreatment samples, there being substantial reductions in the high-tyrosine proteins and increases in the high-sulfur proteins. Similar results were obtained with mice dehaired with mimosine and with sheep treated with low levels of mimosine which resulted in weakened wool rather than depilation. The composition of later samples of the regrowth wool showed progressive changes with time. The high-tyrosine proteins tended to approach the pretreatment levels, although this may take up to 12 weeks to occur, whereas the levels of high-sulfur proteins, after the initial increase, often fell below normal. In experiments involving defieecing with cyclophosphamide, the level of the latter proteins was still below normal after 3 months.The possibility that this altered protein composition of keratin fibres is characteristic of that portion of fibre first produced by a new or regenerating follicle was investigated in sheep and mice. It was found that wool follicles regenerating after plucking, and newly operating follicles in young sheep and mice, also produced wool and hair with a reduced content of high-tyrosine proteins. It is suggested, therefore, that the apparent long-term inhibition of the high-tyrosine proteins may not be the direct consequence of the administration of the chemical but rather be characteristic of normal wool and hair regrowth.Infusion of an amino acid mixture lacking methionine into the abomasum of sheep caused the growth of weak wool but did not suppress the synthesis of the high-tyrosine proteins. This is in contrast with previous findings that treatments which weaken wool also suppress high-tyrosine proteins.

Protein and amino acid composition of hair from mice carrying the naked (N) gene

“…Only the HT proteins were consistently reduced in N/ + , and perhaps N/N, hair compared with + / + hair. However, the HT proteins are known to be sensitive to environmental factors such as diet and depilatory agents (Frenkel, Gillespie & Reis, 1974, 1975Gillespie, Frenkel & Reis, 1980), so a reduction in HT protein content cannot necessarily be attributed to a direct involvement of the N gene in HT protein synthesis. Although an additional protein, HT 9, was present in some N/N samples it was not represented in all samples.…”

The structure of hair and follicles of mice carrying the naked (N) gene

“…Weakness has been reported in wool with reduced amounts of these proteins following the treatment of sheep with certain dietary supplements or various depilating agents (Frenkel, Gillespie & Reis, 1974;1975). By contrast, the early regrowth of wool fibres regenerating after plucking and the tips of fibres of lambs and young mice, which are stated without measurement to have normal strengths, also have reduced contents of high-tyrosine proteins (Gillespie, Frenkel & Reis, 1980).…”

Changes in Wool Low-Sulfur and High-Sulfur Protein Components Following Chemical Defleecing

“…The first wool grown after chemical defleecing has a lower content of high-tyrosine proteins and increased amount of high-sulfur proteins relative to pretreatment grown wool. In later regrowth wool, the hightyrosine proteins progressively return to normal, but the content of the high-sulfur proteins may decrease before returning to normal [7]. There may also be changes in the amount of low-sulfur proteins.…”

“…Many of the changes following chemical defleecing may be long-term, with the wool not returning to normal composition for some months [7]. Because of possible consequences in terms of altered wool properties, it is important to establish the full extent of the changes, including variations in the relative proportions of components within the major protein fractions.…”

“…This variability has recently been discussed [6] and results largely from changes in the ratio of microfibrils (composed essentially of low-sulfur proteins) to matrix, and in the relative proportions of the two matrix protein fractions (high-'sulfur and high-tyrosine). Apart from genetic and nutritional control over wool composition [6], various chemical treatments applied to sheep are known to affect the rate of synthesis of keratin proteins [3,4,7]. Depending on the nature and dose level of the chemical, a treatment may not stop wool growth completely, in which case there is a partial suppression of the high-tyrosine proteins, and this is usually accompanied by an increase in the content of the high-sulfur proteins.…”