Characterization of the structural and molecular defects in fibres and follicles of the Merino felting lustre mutant

Effects of KRTAP20-1 Gene Variation on Wool Traits in Chinese Tan Sheep

Chinese Tan sheep lambs are recognised for having tight 'spring-like' curly wool when young, but this phenotype disappears with age. This wool consists of shorter, fine wool fibres (which are usually unmedullated) and heterotypic hair fibres (which are frequently medullated), which are referred to as 'halo hair'. Both the wool and hair fibres consist of α-keratin proteins embedded in a keratin-associated protein (KAP) matrix. Of these KAPs, the KAP20-1 gene (designated KRTAP20-1) and its effect on four fibre traits (mean fibre curvature, mean fibre diameter, fibre diameter standard deviation, and coefficient of variation of fibre diameter) of Tan lambs was studied. Seven previously identified KRTAP20-1 variants (A, B, D, E, F, G, and H) of KRTAP20-1 were revealed, but the previously identified variant C was not present. Of the seven variants detected, only two (A and G) were common and present at frequencies greater than 5%, and the effect of these on the fibre traits of the finer wool fibres was assessed. It was found that variant G was associated with an increased mean fibre curvature in these wool fibres. This suggests that KRTAP20-1 might possibly be expressed differentially in the two fibre types, which may be of future value in breeding.

Exploring Variation in Ovine KRTAP19-5 and Its Effect on Fine Wool Fibre Curvature in Chinese Tan Sheep

Sheep's wool is known to have unique biological, physical and chemical properties. The fibre primarily consists of proteins, but these have amino acid sequence variation, and at the phenotypic level wool fibre varies considerably. This can affect its utility and value. Unravelling the genetic factors that underpin the protein and phenotypic variability is crucial if we are to contemplate improving wool quality. Accordingly, this study investigates the high glycine and tyrosine content keratin-associated protein 19-5 gene (KRTAP19-5) in sheep. PCR-single strand confirmation polymorphism analysis, coupled with DNA sequencing of a region spanning whole coding sequence, revealed six sequence variants containing seven single nucleotide polymorphisms (SNPs). Five of the SNPs were located within the coding region, with four leading to amino acid changes if expressed. In 247 Chinese Tan sheep derived from 10 sire-lines, and renowned for their distinct 'spring-like' crimped wool at up to approximately 35 days after birth, one of the variants was found to be associated with decreased curvature of the fine wool fibres in the fleece. No associations were detected with other fibre traits or with variation in the heterotypic hair fibres of the Tan sheep. While these findings may be useful for developing gene markers to alter mean wool fibre curvature and improve sheep breeding, many other genes and environmental factors are known to contribute to variation in fibre traits.

Ovine KRTAP36-2: A New Keratin-Associated Protein Gene Related to Variation in Wool Yield

Keratin-associated proteins (KAPs) are structural components of wool fibres. High-glycine/tyrosine (HGT)-KAPs are a subset of the KAP family, and their abundance in fibres varies. In this study, we report the discovery of an ovine HGT-KAP gene to which we assigned the name KRTAP36-2. Polymerase chain reaction and single-strand conformation polymorphism (PCR-SSCP) analyses revealed four variants of this gene in a screening population of 170 sheep from a variety of breeds. The DNA sequencing of the variants revealed four single-nucleotide polymorphisms (SNPs) and a dinucleotide deletion. Three of these SNPs were in the coding region, and one of these was non-synonymous and potentially led to the amino acid substitution p.Cys27Gly near the middle of the protein. The remaining SNP was located near the putative TATA box, and the di-nucleotide deletion was near the putative transcription initiation site. The effect of this variation in KRTAP36-2 was investigated in 274 Southdown × Merino lambs that were the progeny of five sires. Variation was only found to be associated with wool yield, that is, the proportion of the greasy fleece that remained as clean fleece upon scouring (expressed as a percentage). This may have some value in increasing wool production.

Wool fiber curvature is correlated with abundance of K38 and specific keratin-associated proteins

Curvature in mammalian fibers, such as wool and human hair, is an important feature of the functional trait of coat structure-it affects mechanical resilience and thermo-insulation. However, to examine the relationship between fiber curvature, ultrastructure and protein composition fiber diameter variability has to be minimal. To achieve this we utilised the progeny of straight-wool domestic sheep mutant rams (crimp mutants) and wild-type ewes. Proteomic and structural results of the resulting mutant/wild-type twin pairs confirmed that straight crimp mutant wool had a normal cuticle and the same cortical protein and ultrastructural building blocks as wild-type (crimpy) fibers but differed in the layout of its cortical cells and in the relative proportions of keratin (K) and keratin-associated proteins (KAPs). In the case of the crimp mutants (straight fibers), the orthocortex was distributed in a fragmented, annular ring, with some orthocortical cells near the central medulla, a pattern similar to that of straight hairs from humans and other mammals. Crimp mutant fibers were noted for the reduced abundance of some proteins in the high glycine-tyrosine class normally associated with the orthocortex, specifically the KAP6, KAP7, and KAP8 families, while proteins from the KAP16 and KAP19 were found in increased abundance. In addition to this, the type I keratin, K38, which is also associated with the orthocortex, was also found at lower abundance in the mutant fibers. Conversely, proteins from the ultra-high sulfur class normally associated with the paracortex, specifically the KAP4 and KAP9 families, were found in higher abundance.

The Complexity of the Ovine and Caprine Keratin-Associated Protein Genes

Sheep (Ovis aries) and goats (Capra hircus) have, for more than a millennia, been a source of fibres for human use, be it for use in clothing and furnishings, for insulation, for decorative and ceremonial purposes, or for combinations thereof. While use of these natural fibres has in some respects been superseded by the use of synthetic and plant-based fibres, increased accounting for the carbon and water footprint of these fibres is creating a re-emergence of interest in fibres derived from sheep and goats. The keratin-associated proteins (KAPs) are structural components of wool and hair fibres, where they form a matrix that cross-links with the keratin intermediate filaments (KIFs), the other main structural component of the fibres. Since the first report of a complete KAP protein sequence in the late 1960s, considerable effort has been made to identify the KAP proteins and their genes in mammals, and to ascertain how these genes and proteins control fibre growth and characteristics. This effort is ongoing, with more and more being understood about the structure and function of the genes. This review consolidates that knowledge and suggests future directions for research to further our understanding.

Deletions in the KAP6-1 gene are associated with fiber traits in cashmere-producing goats

Keratin-associated proteins (KAPs) are important structural components of fibers that predominantly present in the ortho-cortex. These proteins form a cross-linked network with keratin intermediate filaments (KIFs), thus producing a strong hair shaft. The keratin-associated protein 6-1 gene (KAP6-1) is a member of the KAPs family that has a potential correlation with fiber traits. In this study, we investigated the influence of KAP6-1 sequence polymorphisms on the fiber characteristics of a Chinese cashmere-producing goat breed (n = 844). Two main variants were found, including a three base pair (bp) deletion (namely B) and a 36-bp deletion (namely C), while the reference genotype of KAP6-1 was named A. Among them, the B variant was first reported on cashmere goats. This study then correlated these genotypes with the collected fiber data to investigate the potential association of these variants. The results showed that variant A is associated with decreased fiber diameter (p < 0.01), while variant C is associated with deceased fiber length (p < 0.01). These two related variants of the KAP6-1 gene have potential applications as gene-makers to improve the fiber diameter and length in cashmere-producing goats.

Wanted, dead and alive: Why a multidisciplinary approach is needed to unlock hair treatment potential

Human recorded history is littered with attempts to improve the perceived appearance of scalp hair. Throughout history, treatments have included both biological and chemical interventions. Hair "quality" or "perceived appearance" is regulated by multiple biological intervention opportunities: adding more hairs by flipping follicles from telogen to anagen, or delaying anagen follicles transiting into catagen; altering hair "apparent amount" by modulating shaft diameter or shape; or, in principle, altering shaft physical properties changing its synthesis. By far the most common biological intervention strategy today is to increase the number of hairs, but to date this has proven difficult and has yielded minimal benefits. Chemical intervention primarily consists of active material surface deposition to improve shaft shine, fibre-fibre interactions and strength. Real, perceptible benefits will best be achieved by combining opportunity areas across the three primary sciences: biology, chemistry and physics. Shaft biogenesis begins with biology: proliferation in the germinative matrix, then crossing "Auber's Critical Line" and ceasing proliferation to synthesize shaft components. Biogenesis then shifts to oxidative chemistry, where previously synthesized components are organized and cross-linked into a shaft. We herein term the crossing point from biology to chemistry as "The Orwin Threshold." Historically, hair biology and chemistry have been conducted in different fields, with biological manipulation residing in biomedical communities and hair shaft chemistry and physics within the consumer care industry, with minimal cross-fertilization. Detailed understanding of hair shaft biogenesis should enable identification of factors necessary for optimum hair shaft production and new intervention opportunities.

Comparative proteomics reveals genetic mechanisms underlying secondary hair follicle development in fine wool sheep during the fetal stage

The aim of this study was to investigate the genetic mechanisms underlying wool production by characterizing the skin protein profile and determining the proteomic changes that occur as a consequence of development in wool-producing sheep using a label-free proteomics approach. Samples were collected at four stages during gestation (87, 96, 102, and 138 days), and every two consecutive stages were statistically compared (87 versus 96, 96 versus 102, and 102 versus 138 days). We identified 227 specific proteins in the sheep proteome that were present in all four stages, and 123 differentially abundant proteins (DAPs). We also observed that the microstructure of the secondary follicles changed significantly during the development of the fetal skin hair follicle. The screened DAPs were strictly related to metabolic and skin development pathways, and were associated with pathways such as the glycolysis/gluconeogenesis. These analyses indicated that the wool production of fine wool sheep is regulated via a variety of pathways. These findings provide an important resource that can be used in future studies of the genetic mechanisms underlying wool traits in fine wool sheep, and the identified DAPs should be further investigated as candidate markers for predicting wool traits in sheep. SIGNIFICANCE: Wool quality (fiber diameter, length, etc.) is an important economic trait of fine wool sheep that is determined by secondary follicle differentiation and re-differentiation. Secondary follicles of fine wool sheep developed from a bud (87 days), and underwent differentiation (96 days) and rapid growth (102 days) until maturity (138 days) during gestation. Comparative analysis based on differential proteomics of these four periods could provide a better understanding of the wool growth mechanism of fine wool sheep and offer novel strategies for improving fine wool quality by breeding.

The Mean Staple Length of Wool Fibre Is Associated with Variation in the Ovine Keratin-Associated Protein 21-2 Gene

Wool and hair fibres consist of a variety of proteins, including the keratin-associated proteins (KAPs). In this study, a putative ovine homologue of the human KAP21-2 gene (KRTAP21-2) was identified. It was located on chromosome 1 as a 201-bp open reading frame (ORF) in the ovine genome assembly from a Texel sheep (v.4 NC_019458.2: nt122932727 to 122932927). A polymerase chain reaction- single strand conformation polymorphism (PCR-SSCP) analysis of this ORF, and subsequent DNA sequencing, identified five sequences (named A-E). The putative amino acid sequences that would be produced, shared some identity with each other and with other KAPs, but they were most similar to ovine KAP21-1, and phylogenetically related to human KAP21-2. The location of the ovine KRTAP21-2 sequence was consistent with the location of human KRTAP21-2, and this suggests they represent different variant forms of ovine KRTAP21-2. Variation in this gene was investigated in 389 Merino (sire) × Southdown-cross (ewe) lambs. These were derived from four independent sire-lines. The sequence variation was found to be associated with variation in five wool traits: including mean staple length (MSL), mean fibre diameter (MFD), fibre diameter standard deviation (FDSD), prickle factor (PF), and greasy fleece weight (GFW). The most persistent effect of KRTAP21-2 variation was with variation in MSL; with the MSL of sheep of genotype AC being 12.5% greater than those of genotype CE. A similar effect was observed from individual variant absence/presence models. This suggests that KRTAP21-2 should be further investigated as a possible gene-marker for improving MSL.

Identification of the Ovine Keratin-Associated Protein 21-1 Gene and Its Association with Variation in Wool Traits

Keratin-associated proteins (KAPs) are key constituents of wool and hair fibers. In this study, an ovine KAP gene encoding a HGT-KAP protein was identified. The gene was different from all of the HGT-KAP genes identified in sheep, but was closely related to the human KAP21-1 gene, suggesting that it represented the unidentified ovine KRTAP21-1. Four variants (named A to D) of ovine KRTAP21-1 were found in 360 Merino × Southdown-cross lambs from four sire lines. Three sequence variations were detected among these variants. Two of the sequence variations were located upstream of the coding region and the remaining one was a synonymous variation in the coding sequence. Six genotypes were found in the Merino-cross lambs, with only two of the genotypes (AA and AC) occurring at a frequency of over 5%. Wool from sheep of genotype AA had a higher yield than that from AC sheep (p = 0.014), but tended to have a lower greasy fleece weight (GFW) than that of genotype AC (P = 0.078). This suggests that variation in KRTAP21-1 affects wool yield and the gene may have potential for use as a genetic maker for improving wool yield.

Stiffness of Human Hair Correlates with the Fractions of Cortical Cell Types

(1) Background: The objective of this work was to elucidate the hair microstructure which correlates with the stiffness of human hair fibers. (2) Methods: Bending moduli of hair fibers were evaluated for the hair samples from 156 Japanese female subjects. Hair transverse sections were dual-stained with fluorescent dyes which can stain para- and ortho-like cortical cells separately, and observed under a fluorescence light microscope. Atomic force microscopy nanoindentation measurements were performed to examine the modulus inside macrofibrils. (3) Results: The difference in bending moduli between the maximum and the minimum values was more than double. The hair of high bending modulus was rich in para-like cortical cells and the bending modulus significantly correlated with the fraction of para-like cortical cells to the whole cortex. On the other hand, the elastic moduli inside macrofibrils were almost same for the para- and ortho-like cortical cells. (4) Conclusions: Hair bending modulus depends on the fractions of the constitutional cortical cell types. The contribution of the intermacrofibrillar materials, which differed in their morphologies and amounts of para- and ortho-like cortical cells, is plausible as a cause of the difference in the modulus of the cortical cell types.

Polymorphism of keratin-associated protein (KAP) 7 gene and its association with wool traits in Rambouillet sheep

In the present study, association of polymorphic variants of KAP 7 gene with wool traits in Rambouillet sheep was investigated by using SSCP-PCR. Genomic DNA was isolated from blood samples of 100 Rambouillet sheep. A 388 bp segment was amplified by PCR using ovine specific primers for KAP 7 gene. The results identified 3 genotypes, viz. AA, AB and BB with genotype frequencies of 0.340 (34), 0.270 (27) and 0.390 (39) respectively and allele frequencies of 0.475 for allele A and 0.525 for allele B. The χ²-test showed that the genotype distribution was not in agreement with Hardy-Weinberg equilibrium (HWE). KAP 7 gene has significantly higher clean wool yield and greasy fleece weight in males whereas females have significantly superior fibre diameter, higher staple length and wool count. BB genotype has significantly higher staple length followed by AA and AB genotype. BB genotype has significantly higher greasy fleece weight production followed by AB and least by AA genotype. From the study, it may be concluded that KAP 7 gene might be a potential molecular marker for genetic selection for higher staple length and greasy fleece weight in Rambouillet sheep.

Evolution of Trichocyte Keratin Associated Proteins

The major components of hair are keratins and keratin associated proteins (KRTAPs). KRTAPs form the interfilamentous matrix between intermediate filament bundles through extensive disulfide bond cross-linking with the numerous cysteine residues in hair keratins. A variable number of approximately100-180 genes compose the KRTAP gene family in mammals. KRTAP gene family members present a typical pattern of concerted evolution, and its evolutionary features are consistent with the evolution of mammalian hair. KRATP genes might be more important in determining the structure of cashmere fibers in domestic mammals like sheep and goats. KRTAP gene variants thus should provide information for improved wool by sheep and goat breeding.

Genome-Wide Identification of the Mutation Underlying Fleece Variation and Discriminating Ancestral Hairy Species from Modern Woolly Sheep

The composition and structure of fleece variation observed in mammals is a consequence of a strong selective pressure for fiber production after domestication. In sheep, fleece variation discriminates ancestral species carrying a long and hairy fleece from modern domestic sheep (Ovis aries) owning a short and woolly fleece. Here, we report that the “woolly” allele results from the insertion of an antisense EIF2S2 retrogene (called asEIF2S2) into the 3′ UTR of the IRF2BP2 gene leading to an abnormal IRF2BP2 transcript. We provide evidence that this chimeric IRF2BP2/asEIF2S2 messenger 1) targets the genuine sense EIF2S2 RNA and 2) creates a long endogenous double-stranded RNA which alters the expression of both EIF2S2 and IRF2BP2 mRNA. This represents a unique example of a phenotype arising via a RNA-RNA hybrid, itself generated through a retroposition mechanism. Our results bring new insights on the sheep population history thanks to the identification of the molecular origin of an evolutionary phenotypic variation.

A comparison of transcriptomic patterns measured in the skin of Chinese fine and coarse wool sheep breeds

We characterised wool traits, and skin gene expression profiles of fine wool Super Merino (SM) and coarse wool Small Tail Han (STH) sheep. SM sheep had a significantly higher total density of wool follicles, heavier fleeces, finer fibre diameter, and increased crimp frequency, staple length and wool grease (lanolin) production. We found 435 genes were expressed at significantly different levels in the skin of the two breeds (127 genes more highly in SM and 308 genes more highly in STH sheep). Classification of the genes more highly expressed in SM sheep revealed numerous lipid metabolic genes as well as genes encoding keratins, keratin-associated proteins, and wool follicle stem cell markers. In contrast, mammalian epidermal development complex genes and other genes associated with skin cornification and muscle function were more highly expressed in STH sheep. Genes identified in this study may be further evaluated for inclusion in breeding programs, or as targets for therapeutic or genetic interventions, aimed at altering wool quality or yield. Expression of the lipid metabolic genes in the skin of sheep may be used as a novel trait with the potential to alter the content or properties of lanolin or the fleece.

Variation in the Ovine KAP6-3 Gene (KRTAP6-3) Is Associated with Variation in Mean Fibre Diameter-Associated Wool Traits

Polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP) analysis was used to investigate variation in the ovine KAP6-3 gene (KRTAP6-3) in 383 Merino × Southdown-cross lambs from four sire-lines, and to determine whether this variation affects wool traits. Five PCR-SSCP banding patterns, representing five different nucleotide sequences, were detected, including four previously identified (named A, B, C, and F) variants and one newly identified (named G) variant. A new non-synonymous single nucleotide polymorphism (SNP) and a 45-bp deletion were detected in variant G. Of the three common genotypes (AA, AB, and AG) identified in these sheep, wool from sheep that were AG, on average, had a lower mean fibre diameter (MFD), fibre diameter standard deviation (FDSD), and prickle factor (PF) than wool from AA sheep, whereas wool from AB sheep, on average, had a higher MFD, FDSD, and PF than wool from AA sheep. This suggests that variation in ovine KRTAP6-3 affect MFD, FDSD, and PF, and that this gene may have potential for use as a gene-maker for improving fibre diameter-associated wool traits.

A Screen for Key Genes and Pathways Involved in High-Quality Brush Hair in the Yangtze River Delta White Goat

The Yangtze River Delta White Goat is the only goat breed that produces high-quality brush hair, or type III hair, which is specialized for use in top-grade writing brushes. There has been little research, especially molecular research, on the traits that result in high-quality brush hair in the Yangtze River Delta White Goat. To explore the molecular mechanisms of the formation of high-quality brush hair, High-throughput RNA-Seq technology was used to compare skin samples from Yangtze River Delta White Goats that produce high-quality hair and non high-quality hair for identification of the important genes and related pathways that might influence the hair quality traits. The results showed that 295 genes were expressed differentially between the goats with higher and lower hair quality, respectively. Of those genes, 132 were up-regulated, 62 were down-regulated, and 101 were expressed exclusively in the goats with high-quality brush hair. Gene Ontology and Metabolic Pathway Significant Enrichment analyses of the differentially expressed genes indicated that the MAP3K1, DUSP1, DUSP6 and the MAPK signaling pathway might play important roles in the traits important for high-quality brush hair.

Identification of the Ovine Keratin-Associated Protein 22-1 (KAP22-1) Gene and Its Effect on Wool Traits

Keratin-associated proteins (KAPs) are structural components of wool and hair fibers. To date, eight high glycine/tyrosine KAP (HGT-KAP) families have been identified in humans, but only three have been identified in sheep. In this study, the putative ovine homolog of the human KAP22-1 gene (KRTAP22-1) was amplified using primers designed based on a human KRTAP22-1 sequence. Polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP) was used to screen for variation in KRTAP22-1 in 390 Merino × Southdown-cross lambs and 75 New Zealand (NZ) Romney sheep. Three PCR-SSCP banding patterns were detected and DNA sequencing revealed that the banding patterns represented three different nucleotide sequences (A-C). Two single nucleotide polymorphisms (SNPs) were identified in these sequences. Variant B was most common with a frequency of 81.3% in NZ Romney sheep, while in the Merino × Southdown-cross lambs, A was more common with a frequency of 51.8%. The presence of B was found to be associated with increased wool yield and decreased mean fiber curvature (MFC). Sheep of genotype BB or AB had a higher wool yield than those of genotype AA. These results suggest that ovine KRTAP22-1 variation may be useful when developing breeding programs based on increasing wool yield, or decreasing wool curvature.

Wool Keratin-Associated Protein Genes in Sheep-A Review

The importance of sheep's wool in making textiles has inspired extensive research into its structure and the underlying genetics since the 1960s. Wool keratin-associated proteins (KAPs) are a key structural component of the wool fibre. The characterisation of the genes encoding these proteins has progressed rapidly with advances in the nucleotide and protein sequencing. This review describes our knowledge of ovine KAPs, their categorisation into families, polymorphism in the proteins and genes, the clustering and chromosomal location of the genes, some characteristics of gene expression and some potential effects of the KAPs on wool traits. The extent and nature of genetic variation in wool KAP genes and its association with fibre characteristics, provides an opportunity for the development of gene-markers for selective breeding of sheep to produce better wool with properties highly matched to specific end-uses.

Identification of four new gene members of the KAP6 gene family in sheep

KAP6 is a high glycine-tyrosine keratin-associated protein (HGT-KAP) family. This family is thought to contain multiple genes. In this study, we used a KRTAP6 coding sequence to search the Ovine Genome (v3.1) and identified five homologous regions (R1–R5). All these regions contained an open reading frame, and they were either identical to, or highly similar to, sheep skin Expressed Sequence Tags (ESTs). Phylogenetic analysis revealed that R1–R5 were clustered with KAP6 sequences from different species and formed a group distinct to other HGT-KAPs. R1 was very similar to the characterised KRTAP6-1 sequence, but the remaining genes appeared to be new. PCR primers were designed to amplify and confirm the presence of these new genes. Amplicons were obtained for all of the 96 sheep investigated. Six, five, three and six PCR-SSCP patterns representing six, five, three and six DNA sequences were observed for KRTAP6-2 to KRTAP6-5 respectively. KRTAP6-2 and KRTAP6-4 had five and three SNPs respectively. Three SNPs and a 45-bp insertion/deletion were detected for KRTAP6-3, and five SNPs and an 18-bp insertion/deletion were identified for KRTAP6-5. Allele frequencies for these KAP6 genes differed between Merino and Romney sheep.

A Microarray-Based Analysis Reveals that a Short Photoperiod Promotes Hair Growth in the Arbas Cashmere Goat

Many animals exhibit different behaviors in different seasons. The photoperiod can have effects on migration, breeding, fur growth, and other processes. The cyclic growth of the fur and feathers of some species of mammals and birds, respectively, is stimulated by the photoperiod as a result of hormone-dependent regulation of the nervous system. To further examine this phenomenon, we evaluated the Arbas Cashmere goat (Capra hircus), a species that is often used in this type of research. The goats were exposed to an experimentally controlled short photoperiod to study the regulation of cyclic cashmere growth. Exposure to a short photoperiod extended the anagen phase of the Cashmere goat hair follicle to increase cashmere production. Assessments of tissue sections indicated that the short photoperiod significantly induced cashmere growth. This conclusion was supported by a comparison of the differences in gene expression between the short photoperiod and natural conditions using gene chip technology. Using the gene chip data, we identified genes that showed altered expression under the short photoperiod compared to natural conditions, and these genes were found to be involved in the biological processes of hair follicle growth, structural composition of the hair follicle, and the morphogenesis of the surrounding skin appendages. Knowledge about differences in the expression of these genes as well as their functions and periodic regulation patterns increases our understanding of Cashmere goat hair follicle growth. This study also provides preliminary data that may be useful for the development of an artificial method to improve cashmere production by controlling the light cycle, which has practical significance for livestock breeding.

Fabric and greasy wool handle, their importance to the Australian wool industry: a review

Handle-related properties of woollen fabrics have been demonstrated to be major factors affecting consumer buying attitudes. Handle is the combination of both textural and compressional attributes. Compressional handle has demonstrated processing advantages in woven and knitted fabrics. The handle of processing lots can be manipulated using a variety of technologies but direct manipulation of textural greasy wool handle pre-processing is still crude. On-farm, there is documented evidence that including handle assessment in a selection index provides additional improvements in genetic gain. However, the assessment of greasy wool handle is based on a tactile evaluation of the wool staple by sheep and wool classers, and its application is affected by a lack of framework that instructs assessors on a standard method of assessment. Once a reliable and repeatable protocol is developed, further understanding of the effect greasy wool handle has on final garment quality will be possible.

The sheep KAP8-2 gene, a new KAP8 family member that is absent in humans

The keratin-associated proteins (KAPs) are fundamental components of hair and wool fibres, and are believed to in part be responsible for some of the properties of these fibres. KAPs can be divided into three groups: the high sulphur (HS) KAPs, the ultra-high sulphur (UHS) KAPs and the high glycine-tyrosine (HGT) KAPs. KAP8 is a HGT-KAP family and was believed to be coded for by a single gene in both humans and sheep. However, the recent identification of a KAP8-2 gene in goats led us to investigate whether a KAP8-2 gene exists in sheep. A BLAST search of the Ovine Genome Assembly v2.0 using the coding sequence of caprine KRTAP8-2 identified a homologous region on sheep chromosome 1 (OAR1:123005473_123005664; E = e(-101)). This region was clustered with a number of previously identified KAP genes including (in order from the centromere) KRTAP11-1, KRTAP7-1, KRTAP8-1, KRTAP6-2, KRTAP6-1, KRTAP13-3 and KRTAP24-1. PCR-SSCP analysis of the notional gene revealed two dissimilar PCR-SSCP banding patterns, representing two DNA sequences. A single nucleotide difference 21 bp upstream of the TATA box was identified. The two sequences did not have great homology with known ovine KRTAP sequences, but high sequence identity was found with KRTAP8-2 from goats and reindeer. These results suggest that sheep possess a KAP8-2 gene and that this gene is polymorphic. The notional KAP8-2 protein is comprised of 63 amino acid residues and is rich in glycine and tyrosine, but has a low cysteine content. In contrast to other HGT-KAPs, ovine KAP8-2 contains more acidic amino acid residues, and this would likely result in a lower isoelectric point (pI) of 6.3.

Bidirectional binding property of high glycine-tyrosine keratin-associated protein contributes to the mechanical strength and shape of hair

Since their first finding in wool 50years ago, keratin-associated proteins (KAPs), which are classified into three groups; high sulfur (HS) KAPs, ultra high sulfur (UHS) KAPs, and high glycine-tyrosine (HGT) KAPs, have been the target of curiosity for scientists due to their characteristic amino acid sequences. While HS and UHS KAPs are known to function in disulfide bond crosslinking, the function of HGT KAPs remains unknown. To clarify the function as well as the binding partners of HGT KAPs, we prepared KAP8.1 and other KAP family proteins, the trichocyte intermediate filament proteins (IFP) K85 and K35, the head domain of K85, and the C subdomain of desmoplakin C-terminus (DPCT-C) and investigated the interactions between them in vitro. Western blot analysis and isothermal titration calorimetry (ITC) indicate that KAP8.1 binds to the head domain of K85, which is helically aligned around the axis of the intermediate filament (IF). From these results and transmission electron microscopy (TEM) observations of bundled filament complex in vitro, we propose that the helical arrangement of IFs found in the orthocortex, which is uniquely distributed on the convex fiber side of the hair, is regulated by KAP8.1. Structure-dependent binding of DPCT-C to trichocyte IFP was confirmed by Western blotting, ITC, and circular dichroism. Moreover, DPCT-C also binds to some HGT KAPs. It is probable that such bidirectional binding property of HGT KAPs contribute to the mechanical robustness of hair.

Identification of the ovine keratin-associated protein KAP1-2 gene (KRTAP1-2)

Keratin-associated proteins (KAPs) are a major component of wool and other keratin-containing tissues. While four KAP1-n proteins have been identified in sheep, only three genes have been described encoding KAP1-1, KAP1-3 and KAP1-4. Here, we used a sequence conserved across the known KAP1-n genes to search the inaugural Ovine Genome Sequence (v1.0) and identified a new KAP1-n sequence on chromosome 11. PCR amplification of this sequence revealed an open reading frame of 474-bp that putatively encodes a polypeptide sequence very similar to the previously described ovine KAP1-2 protein and suggests that the newly identified sequence represents the previously unidentified KAP1-2 gene (KRTAP1-2). Its expression in skin was confirmed by PCR, and the mRNA was localized to the cortex of the mid-keratinization zone of a growing wool fibre using a gene-specific probe and in situ hybridization. PCR-SSCP analysis of KRTAP1-2 revealed nine unique banding patterns representing nine different DNA sequences. One sequence was identical to, and the other eight were homologous to, the sequence identified above, suggesting that they were allelic variants of ovine KRTAP1-2. There were ten single nucleotide substitutions identified, although only three of these were non-synonymous and would potentially result in amino acid changes. The variation identified here may influence the expression or protein structure of KAP1-2 and consequently wool structure and wool traits.

Annotation of sheep keratin intermediate filament genes and their patterns of expression

Keratin IF (KRT) and keratin-associated protein genes encode the majority of wool and hair proteins. We have identified cDNA sequences representing nine novel sheep KRT genes, increasing the known active genes from eight to 17, a number comparable to that in the human. However, the absence of KRT37 in the type I family and the discovery of type II KRT87 in sheep exemplify species-specific compositional differences in hair KRT genes. Phylogenetic analysis of hair KRT genes within type I and type II families in the sheep, cattle and human genomes revealed a high degree of consistency in their sequence conservation and grouping. However, there were differences in the fibre compartmentalisation and keratinisation zones for the expression of six ovine KRT genes compared with their human orthologs. Transcripts of three genes (KRT40, KRT82 and KRT84) were only present in the fibre cuticle. KRT32, KRT35 and KRT85 were expressed in both the cuticle and the fibre cortex. The remaining 11 genes (KRT31, KRT33A, KRT33B, KRT34, KRT36, KRT38-39, KRT81, KRT83 and KRT86-87) were expressed only in the cortex. Species-specific differences in the expressed keratin gene sets, their relative expression levels and compartmentalisation are discussed in the context of their underlying roles in wool and hair developmental programmes and the distinctive characteristics of the fibres produced.

Characterization and expression analysis of KAP7.1, KAP8.2 gene in Liaoning new-breeding cashmere goat hair follicle

Keratin-associated protein is one of the major structural proteins of the hair, whose content in hair has important effect on the quality of cashmere. In order to study the relationship between HGTKAP gene expression and cashmere fineness, the quantitative real-time RT-PCR (qRT-PCR) was firstly used to detect the levels of KAP7.1, KAP8.2 gene expression in the primary and secondary hair follicles; semi-quantitative RT-PCR was used to detect whether KAP7.1, KAP8.2 gene are expressed in heart, liver, spleen, lung, kidney tissues; and in situ hybridization(ISH) to detect KAP7.1 gene expression location. qRT-PCR result showed that the expression of both KAP7.1 and KAP8.2 gene in the secondary hair follicles are significantly higher than that in the primary follicles, relative quantitative analysis obtained that KAP7.1 was 2.28 times, while KAP8.2 was 2.71 times. Semi-quantitative RT-PCR results revealed that KAP 7.1 and KAP8.2 mRNA were not detected in the heart, liver, spleen, lung and kidney tissues, demonstrating that KAP7.1 and KAP8.2 were specially expressed in hair follicles, participating in hair formation. Moreover, KAP7.1 gene has a strong expression in the cortical layer, inner root sheath of the primary follicles and the cortical layer, inner root sheath and hair matrix of the secondary hair follicles by ISH analysis. Taken together, the evidence presented here indicated that in the formation of cashmere and wool, differential expression of these two genes in the primary and secondary hair follicles may have an important role in regulating the fiber diameter.

Gene expression profiles of BMP4, FGF10 and cognate inhibitors, in the skin of foetal Merino sheep, at the time of secondary follicle branching

The high concentration of secondary branched follicles is a distinctive feature of the Merino sheep. These follicles initiate from 100 days of gestation. Here, we report a transition in abundance of the BMP4 and FGF10 morphogens occurring at this time. At 103 days of gestation, FGF10 gene expression dropped steadily from maximal levels, in a trend that continued until day 143. Conversely, from day 105, BMP4 transcript levels rapidly increased to maximal levels that were maintained until 131 days, before declining. This profile closely matches reported changes in branched follicle numbers, which peak in density at day 134. SPRY4, a known regulator of FGF10, increased to maximal levels concomitant with the fall in FGF10, suggesting a relationship. Levels of the BMP4 inhibitor NOG matched the initial rise of BMP4, with a fivefold spike at 108 days; but consistent with the rise in BMP4, this high level was not sustained.