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PubMed1996

Targeting gene expression to the wool follicle in transgenic sheep.

To establish the feasibility of overexpressing foreign genes in the wool follicle, transgenic sheep were produced by pronuclear microinjection of a DNA construct consisting of a mouse ultrahigh-sulfur keratin promoter linked to the bacterial chloramphenicol acetyl transferase (CAT) gene. Four of 31 lambs born were transgenic. The overall efficiency of transgenesis was 1.1% of zygotes injected and transferred. Two transgenic rams were mated to nontransgenic ewes, and both transmitted the gene to their offspring in Mendelian fashion. CAT expression was found in the skin of one G0 ram and in 9 out of 26 transgenic G1 progeny. Two G1 lambs were sacrificed to study tissue specificity. Both had high levels of expression in skin but One had high expression in spleen and kidney with lower levels of expression in lung; the other had low expression in spleen, lung, and muscle. In situ hybridization demonstrated that transgene expression in the skin was confined to the keratogenous zone of the wool follicle cortex. Expression of CAT activity in skin was correlated with diet-induced or seasonal changes in the rate of wool growth. This keratin promoter appears useful for overexpressing factors in the wool follicle that might influence wool production or properties.

Animals↗
PubMed2006

Characterisation of photo-oxidation products within photoyellowed wool proteins: tryptophan and tyrosine derived chromophores.

Understanding the photodegradation of complex protein systems represents a significant goal in protein science. The photo-oxidation and resultant photoyellowing of wool in sunlight is a severe impediment to its marketability. However, although some photomodifications have been found in irradiated model amino acid systems, direct identification of the chromophoric photoproducts responsible for photoyellowing in irradiated wool itself has proved elusive. We here describe the direct characterisation and location of yellow chromophores and related photomodifications within the proteins of photoyellowed wool fabric, utilising a quasi-proteomic approach. In total, eight distinct photoproducts were characterised. Of these, five were derived from tryptophan; namely hydroxytryptophan, N-formylkynurenine, kynurenine, residues consistent with the dehydration of kynurenine, and hydroxykynurenine, while three were derived from tyrosine; namely dihydroxyphenylalanine, dityrosine, and a cross-linked residue consistent with a hydroxylated dityrosine residue. Fourteen modified peptide sequences were identified and the positions of modification for thirteen of these were located within the primary structure of known wool proteins. The nature of the photoproducts characterised offer valuable insight into the reaction pathways followed in the UV-induced photoyellowing of wool proteins.

Animals↗
PubMed1966

The dietary-regulated biosynthesis of high-sulphur wool proteins.

1. When the diet of sheep is supplemented by the abomasal infusion of sulphur-containing amino acids or casein, a special group of proteins, with a very high content of sulphur (about 8.3%), is incorporated into the high-sulphur proteins of wool. These special proteins cannot be detected in control wool from the same sheep. 2. This is a naturally occurring process, as these special proteins are found in wool from sheep on a high level of nutrition under ordinary conditions of feeding, and in wool of an inherently high sulphur content. 3. This represents a control mechanism in protein synthesis that has not previously been observed, and may be further evidence that the high-sulphur proteins of wool are produced by an unusual synthetic route.

Amino Acids↗
PubMed1975

Effects of intravenous infusion of mimosine on wool growth of Merino sheep.

Merino sheep were given continuous intravenous infusions of L-mimosine for periods of 1 1/2, 2 or 21 days; efficacy as a defleecing procedure and effects on subsequent wool growth were measured. In addition, the amino acids tyrosine, phenylalanine and cystine were investigates as antagonists to the effects of mimosine. Infusions for 1 1/2 or 2 days at the daily rate of 80-120 mg/kg caused a cessation of wool growth by 1 1/2-2 days from the start of infusion, and all sheep were subsequently defleeced. It was estimated that, on average, fibre growth stopped for 10 1/2-13 days in four sheep after a 2-day infusion, and for 5 1/2 and 9 1/2 days in two sheep after an infusion for 1 1/2 days. There was considerable variation in the time taken for new fibres to recommence growth. During the period 3-5 weeks after infusion of mimosine, length growth rate was consistently greater than the pretreatment rate. Likewise, fibre diameter was greater in three out of the four sheep. As a result, the volume growth rate of fibres was greater post-treatment than it was pretreatment. Infusion for 3 weeks at the daily rate of 21-24 mg/kg did not stop wool growth. However, both length growth rate and fibre diameter were considerably depressed, and after 12 days' infusion, fibre diameter and volume growth rate were reduced to less than half the pretreatment values, and wool fibres were very weak. After the mimosine infusion stopped, fibre diameter increased to above pretreatment values and remained ther for the period of 2-3 weeks studied. The concurrent infusion of tyrosine, phenylalanine or cystine with mimosine failed to prevent any of the effects of mimosine on wool growth.

Animals↗
PubMed1979

Studies on the in vitro metabolism of [3H]cortisol and [3H]oestradiol by sheep skin and wool roots.

The in vitro metabolism of [3H]cortisol, [3H]cortisone and [3H]estradiol-17 beta by adult sheep skin and wool follicle tissue (wool roots) was examined. The main metabolic product of the incubation of [3H]cortisol with sheep skin was [3H]cortisone, and the conversion was reversible. Wool roots were unable to carry out detectable interconversion, nor did this tissue give rise to other significant metabolites. Sheep skin and wool roots both rapidly converted [3H]oestradiol-17 beta to [3H]oestrone and the conversion could be carried out by follicle and non-follicle skin structures. It is suggested that sheep skin contains both 11 beta- and 17 beta-hydroxysteroid dehydrogenases, but that wool follicles contain only the latter enzyme.

Animals↗
PubMed1994

Transgenic sheep and wool growth: possibilities and current status.

Merino wool is the result of generations of selection, yet improvements in wool quality and performance are still being sought. Through gene manipulation, sheep transgenesis offers possibilities of understanding the relationship between wool keratin protein composition and fibre structure and properties and of introducing novel changes to fibre properties and growth rates. We have established an efficient sheep transgenesis programme with an overall transgenic rate of 2.1% of zygotes injected. However, by incorporating in vitro culture and assessment of injected zygotes, this equates to a transgenic rate of 13% from 516 lambs born. With the first keratin gene construct, a wool keratin type II intermediate filament gene, four live F0 transgenic sheep have been produced and all express the transgene. In one of them, the highest expressor, phenotypic and ultrastructural changes were evident in the fleece. To improve wool growth rate by increasing the supply of cysteine to the follicle, transgenic sheep are being produced carrying the two genes necessary for endogenous cysteine synthesis. Three promoters have been tested driving the cysteine synthesis genes: two general promoters, the Rous sarcoma virus long terminal repeat and mouse phosphoglycerate kinase promoter, and a rumen-specific promoter from the sheep small proline-rich protein gene. To date, one transgenic sheep (bearing the small proline-rich protein promoter constructs) has produced cysteine in the rumen, although the amount was low at 3 months of age and not detectable at 6 months.

Animals↗
PubMed2003

Volatile fatty acids as malodorous compounds in wool scouring water and lanolin. Origin and characterisation.

Volatile fatty acids (C2-C7) analysis in wool scouring water and lanolin is presented. These substances are of major interest as malodorous compounds in urban and industrial wastewaters. In this work, they have been analysed in wool scouring water by headspace solid-phase microextraction followed by gas chromatography negative chemical ionisation mass spectrometry. Most of the volatile fatty acids have been identified at microg g(-1) levels. In addition, since lanolin is a major impurity of raw wool, volatile fatty acid patterns of wool scouring water and lanolin have been compared in order to establish the origin of these compounds in the wastewater. Finally, the efficiency of the deodorization step, mandatory to obtain commercial lanolin, has been assessed taking into account the decrease in volatile fatty acid content from the raw wool to the lanolin.

Animals↗
PubMed1994

Dietary cysteine regulates the levels of mRNAs encoding a family of cysteine-rich proteins of wool.

The abomasal or intravenous infusion of sulphur-containing amino acids such as cysteine or methionine into sheep on low-quality diets increases the sulphur content of the wool by increasing the synthesis of proteins containing a cysteine content of approximately 30 mol %. To investigate the molecular and cellular basis of this nutritional effect, quantitative analyses of wool keratin mRNA and protein levels, and follicle cortical cell type, were undertaken in sheep intravenously infused with cysteine. Northern blot analyses revealed that the mRNA levels of one gene family encoding cysteine-rich keratin-associated proteins (KAP4 family) expressed in the wool follicle cortex, increased approximately 5-6 times. Furthermore, the response was rapid as the mRNA levels increased approximately 3.5 times after 1 d of the cysteine infusion and, by 1 d post-infusion, they had fallen, approaching their basal level. No changes in the mRNA levels encoding the intermediate filament or the other keratin-associated protein families of lower cysteine content were observed. Concomitantly, two-dimensional polyacrylamide gel electrophoresis analysis of wool proteins showed a striking increase in the abundance of a group of cysteine-rich keratin-associated proteins in the wool by the end of the infusion period, returning to basal levels by 3 weeks later. At the cellular level, KAP4 expression was localized to the follicle paracortical cells, and the proportion of paracortical cells and the extent of KAP4 expression paralleled the changes in the cysteine infusion status of the sheep.

Amino Acid Sequence↗
PubMed1996

Microbiological contamination of ovine carcasses associated with the presence of wool and faecal material.

The microbiological contamination of ovine hind legs at sites which were visibly clean (control carcasses), sites immediately adjacent to and below visually contaminated sites, and sites contaminated with visible faecal material or wool were determined by excision sampling immediately after pelting and immediately after a pre-evisceration wash. The mean aerobic plate count (APC) and Escherichia coli count (EC) at clean sites immediately after pelting ranged from log10 cm-2 3.98 to 4.44 and log10 cm-2 0.96 to 1.51, respectively. These levels of contamination were significantly lower than those on sites contaminated with faecal material (log10 cm-2 6.00 and 3.00, respectively) or wool (log10 cm-2 5.44 and 2.45, respectively). The presence of faecal material or wool on the carcass was not associated with increased bacterial numbers on visually clean areas of the carcass. This indicates that the presence of faecal material or wool alone cannot be used as an indicator of the hygienic status of the carcass as a whole, particularly in the role of on-line monitoring parameters for HACCP systems. Pre-evisceration washing of carcasses had very little effect on the uncontaminated areas of the carcasses, but reduced the mean APC and EC at the site of visible contaminants. There was little evidence of redistribution of bacteria to immediately adjacent but visually clean sites. However, the residual levels of both APCs and ECs directly at sites of faecal contamination after washing were still significantly higher than at visually clean sites. Application of HACCP principles to ovine slaughter and dressing suggests that visible faecal material should be removed by trimming, whereas pre-evisceration washes can have a practical and microbiologically validated role in the removal of wool. There was generally a good correlation between APCs and ECs at the uncontaminated sites prior to pre-evisceration washing, suggesting that in some situations APCs can act as a useful indicator of both general carcass hygiene and the presence of faecal indicators.

Abattoirs↗
PubMed2004

The dissemination of anthrax from imported wool: Kidderminster 1900-14.

BACKGROUND: A century ago anthrax was a continuing health risk in the town of Kidderminster. The distribution of cases in people and in animals provides an indication of the routes by which spores were disseminated. The response to these cases provides an insight into attitudes to an occupational and environmental risk at the time and can be compared with responses in more recent times. AIMS: To assess the distribution of anthrax cases associated with the use of contaminated wool and to review the response to them. METHODS: The area studied was Kidderminster, Worcestershire, England, from 1900 to 1914. Data sources were national records of the Factory Inspectorate and local records from the infirmary, Medical Officer of Health and inquest reports, and county agricultural records, supplemented by contemporary and later review articles. Case reports and summary data were analysed, and discussions and actions taken to improve precautions reviewed. RESULTS: There were 36 cases of anthrax, with five deaths, one of which was the sole case of the internal form of the disease. Cases of cutaneous anthrax were most frequently found in those handling raw wool, but they also occurred in workers at later stages of the spinning process and in people with little or no recorded exposure to contaminated wool. Limited precautionary measures were in place at the start of the study period. Some improvements were made, especially in the treatment of infections, but wool with a high risk of anthrax contamination continued to be used and cases continued to arise. Major changes were made to the disposal of waste and to agricultural practice in contaminated areas to curtail outbreaks in farm animals. CONCLUSIONS: The introduction of anthrax as a contaminant of imported wool led not only to cases in the highly exposed groups of workers but also to cases in other members of the population and in farm animals. The measures taken during the study period reduced fatalities from cutaneous anthrax but did not eliminate the disease. Public concern about the cases was muted.

Animals↗
PubMed1976

Effect of wool dust on respiratory function.

A group of 252 workers (176 women and 76 men) employed in two wool mills was studied. The mean age of 36 years; mean exposure, 11 years. All women were nonsmokers, and 47 per cent of the men were regular smokers. Ventilatory function was measured by recording maximal expiratory flow-volume curves and forced expiratory volume in 1 sec on the first working day of the week (Monday) before and after the work shift. On maximal expiratory flow-volume curves the flow rates at 50 per cent of the control vital capacity were read. Workers exposed to wool dust for more than 10 years had a higher prevalence of chronic respiratory symptoms than did those with less than 10 years' exposure, but the difference was not significant. Significant reductions during the work shift were found in maximal expiratory flow rates at 50 per cent of the control vital capapity and 1-sec forced expiratory volume, the first test being considerably more sensitive. Workers exposed to wool dust for more than 10 years had signficantly lower than predicted pre-shift values for maximal expiratory flow rates at 50 per cent of the control vital capapcity. Inhalation of wool dust extract caused a significant decrease of maximal expiratory flow rates at 40 per cent of the control vital capacity on partial expiratory flow-volume curves during the 100 min after exposure. Comparison with the same concentration of cotton dust extract revealed a similar effect during the first 40 min after exposure but a significantly larger effect of the cotton dust extract after 40 min. The data suggest that preventive measures, especially medical supervision, are necessary in wool-processing mills to protect workers sensitive to dust.

Adult↗
PubMed1980

Photoperiodic control of thyroid function and wool and horn growth in rams and the effect of cranial sympathectomy.

Eight adult Soay rams (four control and four superior cervical ganglionectomized) were housed in an artificial lighting regimen of alternating 16-week periods of long days [16 h of light, 8 h of darkness (16 L:8D)] and short days (8L:16D) for nearly 3 yr, and the long term variations in growth of the wool and horns were recorded along with measurements of the plasma concentration of T4, T3, and testosterone. In the control rams all of the parameters varied in relation to the imposed lighting regimen. An increase in the growth of the wool and horns occurred during each period of long days at a time when the circulating concentrations of T4 and T3 were high; at this time the animals were reproductively quiescent, with low plasma levels of testosterone. During each period of short days the rate of wool and horn growth declined, as did the plasma concentrations of T4 and T3, while the rams became sexually active with high plasma levels of testosterone. Moulting of the old coat occurred during the periods of long days, coinciding with the phase of increasing wool growth. The variations in the ganglionectomized rams were quite different from those in the controls, bearing no clear relationship to the imposed lighting regimen. In these operated animals there were long term changes in all of the parameters, but these were generally less pronounced than those in the controls. The unusual pattern in the growth of horns and wool was correlated with long term changes in the plasma levels of T4, T3, and testosterone. Moulting of the old coat did not occur in the normal manner in the animals after the first year.

Animals↗
PubMed1987

Seasonal reproduction in ewes selected on seasonal changes in wool growth.

Romney and Perendale ewes were selected on the amplitude of seasonal wool growth. The ewes were fed a constant plane of nutrition and run with vasectomized rams. Ovarian activity was recorded by laparoscopy during 11 months. Ewes with a low amplitude of seasonal wool growth (Group L) had a 68% higher wool growth rate in winter and a 17% lower wool growth rate in summer compared with ewes with a high amplitude (Group H). There was no difference between the groups in the date of the first mating mark. Ewes in Group L entered anoestrus significantly later than did ewes in Group H; the difference was 11 days in the mean date of the last mating mark and 17 days in the mean date of the last ovulation. A significantly higher proportion of ewes in Group L ovulated during July to November. In addition, ewes in Group L had a significantly higher proportion of multiple ovulations throughout the experiment: on average the difference between the groups was 0.21. These results show that phenotypic selection for a low amplitude of seasonal wool growth resulted in a delay in the end of the breeding season associated with an increase in ovulation rate, suggesting independent effects on the beginning and end of the breeding season.

Anestrus↗
PubMedDate not supplied

Determination of photo-oxidation products within photoyellowed bleached wool proteins.

Photo-oxidative processes occurring in wool can lead to significant photoyellowing of the fiber. In particular, wool that has been chemically bleached photoyellows more rapidly and to a greater degree than untreated wool. Direct identification of the chromophores responsible for such yellow discoloration in irradiated wool has proven to be elusive for many years. This article describes the characterization and location of yellow photo-oxidation products within the proteins of photoyellowed bleached wool fabric, using advanced protein chemistry techniques. The discolored fabric was enzymatically digested and chromatographed by high-pressure liquid chromatography, with monitoring at 400 nm, to select out fractions containing yellow chromophoric species. Thorough tandem mass spectrometric analysis was then used to sequence peptides and, in turn, to characterize modifications to key amino acid residues that had resulted in yellow chromophore formation. In total, 11 separate yellow chromophoric species were identified, ten derived from tryptophan residues and one from tyrosine. The tryptophan-derived modifications characterized included hydroxytryptophan, N-formylkynurenine, hydroxyformylkynurenine, kynurenine, hydroxykynurenine, carbolines, tryptophandiones and nitrotryptophan. The tyrosine-derived modification of tyrosine to dopa was also identified. The range of photomodifications we observed provides insight into the photo-oxidation pathways occurring within irradiated fibrous proteins leading to the formation of yellow chromophores.

Animals↗
PubMed1993

Wool production and blood supply to skin and other tissues in sheep.

Quantitative measurements of blood flow (BF) to skin and several other tissues were made using radioactive microspheres in conscious sheep. The sheep were from established flocks that had been selectively bred for greater (Fleece plus) or lesser (Fleece minus) wool production. The BF rate per unit area of wool-bearing skin was significantly greater in the Fleece plus (n = 9) than in the Fleece minus (n = 6) group, but the correlation between skin BF and the wool growth rate in individual animals was modest (r = .581). There was a strong, positive correlation (r = .813) between wool production and pineal BF. Other tissues that exhibited significant BF differences between the two groups included adrenal glands and fat, which were greater in Fleece plus sheep, and thyroid glands, reticulum, rumen, and extremity skin (non-wool-bearing), which were lesser in Fleece plus sheep.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1994

The nutritional control of the growth and properties of mohair and wool fibers: a comparative review.

The effect of nutrient status on the growth and properties of wool and mohair fibers is reviewed: the aim is to compare effects on sheep and Angora goats and emphasize differences between the species. Wool growth is markedly influenced by nutrition; the requirement for energy-yielding nutrients is low and the major nutrients limiting wool growth are essential AA, sulfur-containing AA being especially important. An adequate supply of Cu, Zn, folic acid, and pyridoxine is required to maintain wool growth. Both length growth (L) and diameter (D) of wool fibers respond to changes in nutrient supply such that the ratio of L:D remains approximately constant. Mohair production is influenced by nutrient supply. However, the importance of specific nutrients has not been established, apart from one study showing that mohair growth responded to parenteral supplementation with methionine. In contrast to sheep, some studies indicate that length growth of mohair fibers may not be very responsive to changes in nutrient status. The responsiveness of mohair growth (both length and diameter) to nutrient supply at different times of the year has not been reported. The energy requirement for fiber growth may be greater in goats than in sheep, but more studies are needed.

Amino Acids↗
PubMed2000

Genetic parameters among weight, prolificacy, and wool traits of Columbia, Polypay, Rambouillet, and Targhee sheep.

Genetic parameters for Columbia, Polypay, Rambouillet, and Targhee sheep were estimated using REML with animal models for prolificacy, weight, and wool traits. All bivariate analyses included a covariance between additive genetic effects for the two traits plus appropriate additional covariances. Number of observations by breed ranged from 5,140 to 7,095 for prolificacy traits, from 7,750 to 9,530 for weight traits, and from 4,603 to 34,746 for wool traits. Heritability estimates ranged from .03 to .11 for prolificacy traits (litter size at birth and litter size at weaning), from .09 to .26 for weight traits (birth weight and average daily gain), and from .25 to .53 for wool traits (fleece weight, fleece grade and staple length). Estimates of direct genetic correlations among prolificacy and among weight traits were positive and ranged from .58 to 1.00 and .18 to 1.00, respectively. Estimates of direct genetic correlation between fleece weight and staple length were positive (.50 to .70) but were negative between fleece weight and fleece grade (-.60 to -.34) and between staple length and fleece grade (-.72 and -.40). Prolificacy and wool traits were essentially uncorrelated. Weight and prolificacy traits were slightly positively correlated. Weight traits had a moderate positive direct genetic correlation with fleece weight and staple length, but were uncorrelated with fleece grade. These estimates of genetic parameters between prolificacy, weight, and wool traits can be used to construct multiple-trait selection indexes for dual-purpose sheep.

Age Factors↗
PubMedDate not supplied

An investigation into the aetiology of 'wool slip': alopecia in ewes which are housed and shorn in winter.

Alopecia in housed ewes which are shorn in winter, 'wool slip', was investigated by taking wool and blood samples, skin scrapings and biopsies from affected and unaffected animals. Epidemiological information was also obtained from farm records, and reports from a local weather station. No pathological lesions were seen and no ectoparasites or forage mites were seen in wool samples or skin scrapings. The plasma zinc and copper concentrations of both groups were within the normal range but the copper concentrations were significantly lower in the unaffected animals. There was no difference between the prevalence of the disease in ewes of different breeds or between those producing single or twin lambs. A comparison of the mean temperatures during years of summer and winter shearing suggested that cold stress alone was not involved. Skin biopsies revealed that the wool follicles of affected animals were in an early growth phase (anagen) whereas those of unaffected animals were in the inactive phase (telogen). The clinical and histological signs of the disease were similar to those seen experimentally when corticosteroids are used as chemical depilatory agents. It is suggested that wool slip is due to the high levels of corticosteroids which occur as a result of the combination of housing and shearing and on this basis methods of control are proposed.

Alopecia↗