Expression of a wool intermediate filament keratin transgene in sheep fibre alters structure

Genetic Engineering of Livestock: The Opportunity Cost of Regulatory Delay

Genetically engineered (GE) livestock were first reported in 1985, and yet only a single GE food animal, the fast-growing AquAdvantage salmon, has been commercialized. There are myriad interconnected reasons for the slow progress in this once-promising field, including technical issues, the structure of livestock industries, lack of public research funding and investment, regulatory obstacles, and concern about public opinion. This review focuses on GE livestock that have been produced and documents the difficulties that researchers and developers have encountered en route. Additionally, the costs associated with delayed commercialization of GE livestock were modeled using three case studies: GE mastitis-resistant dairy cattle, genome-edited porcine reproductive and respiratory syndrome virus-resistant pigs, and the AquAdvantage salmon. Delays of 5 or 10 years in the commercialization of GE livestock beyond the normative 10-year GE product evaluation period were associated with billions of dollars in opportunity costs and reduced global food security.

Animal science Down Under: a history of research, development and extension in support of Australia’s livestock industries

This account of the development and achievements of the animal sciences in Australia is prefaced by a brief history of the livestock industries from 1788 to the present. During the 19th century, progress in industry development was due more to the experience and ingenuity of producers than to the application of scientific principles; the end of the century also saw the establishment of departments of agriculture and agricultural colleges in all Australian colonies (later states). Between the two world wars, the Council for Scientific and Industrial Research was established, including well supported Divisions of Animal Nutrition and Animal Health, and there was significant growth in research and extension capability in the state departments. However, the research capacity of the recently established university Faculties of Agriculture and Veterinary Science was limited by lack of funding and opportunity to offer postgraduate research training. The three decades after 1945 were marked by strong political support for agricultural research, development and extension, visionary scientific leadership, and major growth in research institutions and achievements, partly driven by increased university funding and enrolment of postgraduate students. State-supported extension services for livestock producers peaked during the 1970s. The final decades of the 20th century featured uncertain commodity markets and changing public attitudes to livestock production. There were also important Federal Government initiatives to stabilise industry and government funding of agricultural research, development and extension via the Research and Development Corporations, and to promote efficient use of these resources through creation of the Cooperative Research Centres program. These initiatives led to some outstanding research outcomes for most of the livestock sectors, which continued during the early decades of the 21st century, including the advent of genomic selection for genetic improvement of production and health traits, and greatly increased attention to public interest issues, particularly animal welfare and environmental protection. The new century has also seen development and application of the ‘One Health’ concept to protect livestock, humans and the environment from exotic infectious diseases, and an accelerating trend towards privatisation of extension services. Finally, industry challenges and opportunities are briefly discussed, emphasising those amenable to research, development and extension solutions.

Long noncoding RNA and gene expression analysis of melatonin-exposed Liaoning cashmere goat fibroblasts indicating cashmere growth

Cashmere produced from Liaoning cashmere goat is highly valuable. Melatonin is an important factor affecting cashmere growth and can regulate the growth cycle via effects on gene expression. Long noncoding RNAs (lncRNAs) regulate gene expression, but detailed studies of their effect on hair growth are lacking. To explore how lncRNA mediates the effects of melatonin on cashmere growth, we used RNA-Seq including a control condition (C) and three melatonin treatments (1.0 g/L 24 h (M1_24H), 0.2 g/L 24 h (M2_24H), 0.2 g/L 72 h (M2_72H)). M1_24H, M2_24H, and M2_72H had 32, 10, and 113 differentially expressed lncRNAs, respectively. Gene ontology (GO) and pathway analyses results showed that melatonin was most beneficial to cashmere growth at 0.2 g/L 72 h, and nuclear factor (NF)-κB signaling corresponding to an effect of LncRNA MTC was involved in hair follicle development. We found that melatonin upregulated XLOC_005914 lncRNA (LncRNA MTC). Proliferation increased in the 0.2 g/L 72 h condition and cells with high LncRNA MTC expression, but it was reduced in fibroblasts with knocked down LncRNA MTC expression. This is the first report that LncRNA MTC promotes fibroblast proliferation and regulates hair follicle development and cashmere growth by activating NF-κB signaling.

Modification of Animal Products for Fat and Other Characteristics

This chapter includes information about modification of animal products using biotechnology and the importance of different modifications on the natural composition. The species considered for modified products include beef and dairy cattle, sheep, goats, poultry, and a wide variety of fishes. Moreover, the discussion includes the importance of animal food, nongenetically engineered animal modified food products, genetically engineered animal modified food items primarily for meat, milk, or egg and genetically engineered animal food along the transgenic approach for animal welfare. Modern biotechnology can improve productivity, consistency, and quality of alter animal food, fiber, and medical products. The transgenic technology is potentially valuable to alter characters of economic importance in a rapid and precise way. The food safety issue related to genetic engineering is also included in this chapter. The harm of such modified food and transgenic strategy should also be understood by the reader along with its advantages. In this context, transgenic approaches in animal biotechnology are under discussion that ranges from animal food production to their adverse effects.

Wool fibre crimp is determined by mitotic asymmetry and position of final keratinisation and not ortho- and para-cortical cell segmentation

Crimp, a distinguishing feature of sheep fibres, significantly affects wool value, processing and final fabric attributes. Several explanations for fibre bending have been proposed. Most concentrate on relative differences in the physicochemical properties of the cortical cells, which comprise the bulk of the fibre. However, the associations between cortical properties and fibre crimp are not consistent and may not reflect the underlying causation of fibre curvature (FC). We have formulated a mechanistic model in which fibre shape is dictated primarily by the degree of asymmetry in cell supply from the follicle bulb, and the point at which keratinisation is completed within the follicle. If this hypothesis is correct, one would anticipate that most variations in fibre crimp would be accounted for by quantitative differences in both the degree of mitotic asymmetry in follicle bulbs and the distance from the bulb to the point at which keratinisation is completed. To test this hypothesis, we took skin biopsies from Merino sheep from sites producing wool differing widely in fibre crimp frequency and FC. Mitotic asymmetry in follicle bulbs was measured using a DNA-labelling technique and the site of final keratinisation was defined by picric acid staining of the fibre. The proportion of para- to ortho-cortical cell area was determined in the cross-sections of fibres within biopsy samples. Mitotic asymmetry in the follicle bulb accounted for 0.64 (P < 0.0001) of the total variance in objectively measured FC, while the point of final keratinisation of the fibre accounted for an additional 0.05 (P < 0.05) of the variance. There was no association between ortho- to para-cortical cell ratio and FC. FC was positively associated with a subjective follicle curvature score (P < 0.01). We conclude that fibre crimp is caused predominantly by asymmetric cell division in follicles that are highly curved. Differential pressures exerted by the subsequent asymmetric cell supply and cell hardening in the lower follicle cause fibre bending. The extent of bending is then modulated by the point at which keratinisation is completed; later hardening means the fibre remains pliable for longer, thereby reducing the pressure differential and reducing fibre bending. This means that even highly asymmetric follicles may produce a straight fibre if keratinisation is sufficiently delayed, as is the case in deficiencies of zinc and copper, or when keratinisation is perturbed by transgenesis. The model presented here can account for the many variations in fibre shape found in mammals.

High-level expression of bioactive recombinant human lysozyme in the milk of transgenic mice using a modified human lactoferrin BAC

Transgenesis has been used for expressing human lysozyme (hLZ) in the milk of livestock to improve their disease resistance. Here we describe a human lactoferrin (hLF) BAC as a candidate vector for high-level expression of hLZ in the milk of transgenic mice. Using recombineering, hLF genomic DNA in the hLF BAC was replaced by the hLZ gene (from the ATG start codon to the TAA stop codon), and flanking regions of the hLF gene (a 90-kb 5' and a 30-kb 3') were used as transcriptional control elements for hLZ expression. When this construct was used to generate transgenic mice, rhLZ was highly expressed in the milk of four transgenic mouse lines (1.20-1.76 g/L), was expressed at a lower level in one additional line (0.21 g/L). rhLZ from the milk of these transgenic mice exhibited the same antibacterial activity as native hLZ. Our results suggest a potential approach for producing large amounts of hLZ in the milk of livestock.

[Advances of transgenic breeding in livestock]

Transgenic technology represents a revolutionary way to produce elite livestock breeds, allowing introduction of alien gene into livestock genome. Currently, pronuclear microinjection of DNA and somatic cell nuclear transfer are two popular methods used to make transgenic farm animals. Transgenic technology can be used in livestock breeding for improving disease resistance, carcass composition, lactational performance, wool production, growth rate, and reproductive performance, as well as reducing negative environmental impact. In addition to introduction of animal transgenic technologies, this review described the status and the future perspective of transgenic breeding in livestock.

Location of Keratin-associated Proteins in Developing Fiber Cuticle Cells using Immunoelectron Microscopy

AIMS

To investigate the location of keratin-associated proteins (KAPs) in developing hair fiber cuticle cells using transmission electron microscopy with immunogold techniques and specific antibodies. Other studies were aimed at detecting the presence of cornified envelope proteins including involucrin and loricrin. MATEIALS AND METHODS: Polyclonal antibodies were produced in rabbits against peptides from KAPS 5.1, KAPS 10.1 ultra high-sulfur proteins.

RESULTS

The KAP proteins were found to form part of the developing exocuticle and a- layer. Cornified envelope proteins (involucrin and loricrin) were absent consistent with recent findings.

CONCLUSIONS

The results have been discussed in terms of a revised model for fiber cuticle surface barriers including their role in fiber cuticle surface function.

An ovine transgenic Huntington's disease model

Huntington's disease (HD) is an inherited autosomal dominant neurodegenerative disorder caused by an expansion of a CAG trinucleotide repeat in the huntingtin (HTT) gene [Huntington's Disease Collaborative Research Group (1993) A novel gene containing a trinucleotide repeat that is expanded and unstable on Huntington's disease chromosomes. The Huntington's Disease Collaborative Research Group. Cell, 72, 971-983]. Despite identification of the gene in 1993, the underlying life-long disease process and effective treatments to prevent or delay it remain elusive. In an effort to fast-track treatment strategies for HD into clinical trials, we have developed a new large-animal HD transgenic ovine model. Sheep, Ovis aries L., were selected because the developmental pattern of the ovine basal ganglia and cortex (the regions primarily affected in HD) is similar to the analogous regions of the human brain. Microinjection of a full-length human HTT cDNA containing 73 polyglutamine repeats under the control of the human promotor resulted in six transgenic founders varying in copy number of the transgene. Analysis of offspring (at 1 and 7 months of age) from one of the founders showed robust expression of the full-length human HTT protein in both CNS and non-CNS tissue. Further, preliminary immunohistochemical analysis demonstrated the organization of the caudate nucleus and putamen and revealed decreased expression of medium size spiny neuron marker DARPP-32 at 7 months of age. It is anticipated that this novel transgenic animal will represent a practical model for drug/clinical trials and surgical interventions especially aimed at delaying or preventing HD initiation. New sequence accession number for ovine HTT mRNA: FJ457100.

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.

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

The felting lustre (FL) mutation found in Merino sheep results in a fleece that has a lustrous appearance and readily felts. This phenotype was described 50 years ago to result from the mutation of a single gene, but the molecular and cellular changes in the wool are not well understood. In this study, follicle and fibre material of FL mutant (n = 3) and normal control (n = 5) Merino ewes was compared using histological analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), real-time polymerase chain reaction (qPCR) and electron microscopy [scanning electron microscopy (SEM) and transmission electron microscopy (TEM)]. Histological examination suggested that follicle structure in FL mutants is essentially normal, while SDS-PAGE analysis found that some low molecular weight keratin-associated proteins (KAP) were present at much lower levels in FL wool. Examination of transcript prevalence revealed that the KAP6.1, KAP7 and KAP8 genes in FL mutant follicles are downregulated, while the KAP2.12 and KAP4.2 genes are upregulated. TEM analysis indicated that there is only one type of cortical cell, the paracortical cell, in the fibre of FL mutants, while there are paracortical and orthocortical cells in fibres of normal Merino sheep. In contrast, SEM suggested the surface topography of FL wool fibres is normal. The evidence presented here strongly suggests that the properties of FL wool can be ascribed, at least in part, to the lower content of high glycine/tyrosine proteins and the reduction in orthocortical cells in mutant wool fibres.

Agricultural applications for transgenic livestock

Transgenic animals are produced by introducing 'foreign' DNA into the genetic material of pre-implantation embryos. This DNA is present in all tissues of the resulting individual. This technique is of great importance to many aspects of biomedical science, including gene regulation, the immune system, cancer research, developmental biology, biomedicine, manufacturing and agriculture. The production of transgenic animals is one of several new and developing technologies that will have a profound impact on the genetic improvement of livestock. The rate at which these technologies are incorporated into production schemes will determine the speed at which we will be able to achieve our goal of more efficiently producing livestock that meets consumer and market demand.

Biology of the wool follicle: an excursion into a unique tissue interaction system waiting to be re-discovered

Wool fibres are hairs and the term 'wool' is usually restricted to describe the fine curly hairs that constitute the fleece produced by sheep. In a broader sense, it can be used to describe the fleeces produced by related species such as goat or yak. Research into the biology of wool growth and the structure of the wool fibre has been driven by the demands of the wool industry to improve both the efficiency of growing wool and the quality of the product. Well beyond this very applied perspective however, the wool follicle is a unique basic research model for the life sciences in general. These unique features include, to name just a few selected examples, accessibility for studying the molecular controls involved in branching of secondary epithelial-mesenchymal structures, the photoperiod-dependence of regenerating tissue interaction systems, the origin of fibre curliness and follicle wave pattern formation, and the effect of alterations in nutrient supply on epithelial growth and fibre structure. In this review, investigation of growth processes in the formation of the wool fibre is broadly surveyed. The relevance and potential for practical outcomes through characterization of wool follicle genes are discussed and particular features of the wool follicle contributing to our knowledge of the biology of hair growth are highlighted. The practical potential of gene discovery in wool research is the provision of molecular markers for selective breeding and for altering wool growth and wool structure by other biological pathways such as sheep transgenesis that could lead to novel wool properties. In this background, the current review attempts to revive general interest in the fascinating biology of the wool follicle which is not only of profound economic and practical importance but offers an exquisite, highly instructive research model for addressing key questions of modern biology.

Gene expression profiling of ovine skin and wool follicle development using a combined ovine - bovine skin cDNA microarray

Low fibre diameter and high fleece weight are important determinants of the economic value of the Merino fleece. The combination of these traits is found in Merino sheep with high follicle densities resulting from a high secondary to primary follicle ratio. Morphological stages in the development of primary and secondary follicles of fetal sheep skin have been well described. We have used gene expression profiling of fetal skin to identify genes that may be important in controlling these follicle developmental processes. A combined ovine (2.3 K) and bovine (6.14 K) cDNA microarray of 2 fetal and 1 adult stage skin tissues was constructed to compare gene expression levels between fetal day 82, day 105, day 120 and adult sheep skin developmental stages. The transcript profile resulted in 238 differentially expressed array elements relative to the adult expression, which represented 132 unique genes. These clustered into 50 up- and 82 down-regulated genes and distinct gene ontologies including structural constituents, phosphate transport, signal transduction and organogenesis. Northern blot analysis of 2 selected genes, S100A7LI and TAGLN, validated the microarray results. This list of genes contains candidates of interest for further investigation into the molecular control of wool follicle development.

Transgenic animals in biomedicine and agriculture: outlook for the future

Transgenic animals are produced by introduction of 'foreign' deoxyribonucleic acid (DNA) into preimplantation embryos. The foreign DNA is inserted into the genetic material and may be expressed in tissues of the resulting individual. This technique is of great importance to many aspects of biomedical science including gene regulation, the immune system, cancer research, developmental biology, biomedicine, manufacturing and agriculture. The production of transgenic animals is one of a number of new and developing technologies that will have a profound impact on the genetic improvement of livestock. The rate at which these technologies are incorporated into production schemes will determine the speed at which we will be able to achieve our goal of more efficiently producing livestock, which meets consumer and market demand.

A unique type I keratin intermediate filament gene family is abundantly expressed in the inner root sheaths of sheep and human hair follicles

A unique type I keratin intermediate filament group, comprising three highly related proteins and expressed in the inner root sheath of hair follicles, has been identified in both sheep and human. The first members from these species are named oIRSa1 and hIRSa1 and each encodes a protein of 450 amino acids, with compositional characteristics intermediate between those of previously described hair keratin and epidermal cytokeratin type I intermediate filaments. Detection of abundant mRNA transcripts derived from the sheep and human genes by cRNA in situ hybridization only in the inner root sheath and not in the medulla concurs with the findings of earlier ultrastructural analyses that have reported intermediate filaments only in the inner root sheath. Clustering of the IRSa keratin genes is apparent in the genomes of both species. The three hIRSa genes, known to reside on human chromosome 17, are closely linked to three further type I keratin intermediate filament genes of unknown function. This new gene complex, contained almost entirely within a 156 kb BAC (hRPK.142_H_19), is likely to lie near the type I intermediate filament cytokeratin and hair keratin gene loci at 17q12-q21. A phylogenetic analysis including all known human type I intermediate filament cytokeratins, hHa keratins, hIRSa, and hIRSa-linked keratins suggests that origin of the IRSa keratin intermediate filament linkage group preceded origin of most of the epidermal cytokeratins and all hair keratins during emergence of the keratin intermediate filament genes.

Regulation of a hair follicle keratin intermediate filament gene promoter

During hair growth, cortical cells emerging from the proliferative follicle bulb rapidly undergo a differentiation program and synthesise large amounts of hair keratin proteins. To identify some of the controls that specify expression of hair genes we have defined the minimal promoter of the wool keratin intermediate filament gene K2.10. The region of this gene spanning nucleotides −350 to +53 was sufficient to direct expression of the lacZ gene to the follicle cortex of transgenic mice but deletion of nucleotides −350 to −150 led to a complete loss of promoter activity. When a four base substitution mutation was introduced into the minimal functional promoter at the binding site for lymphoid enhancer factor 1 (LEF-1), promoter activity in transgenic mice was decreased but specificity was not affected. To investigate the interaction of trans-acting factors within the minimal K2.10 promoter we performed DNase I footprinting analyses and electrophoretic mobility shift assays. In addition to LEF-1, Sp1, AP2-like and NF1-like proteins bound to the promoter. The Sp1 and AP2-like proteins bound sequences flanking the LEF-1 binding site whereas the NF1-like proteins bound closer to the transcription start site. We conclude that the LEF-1 binding site is an enhancer element of the K2.10 promoter in the hair follicle cortex and that factors other than LEF-1 regulate promoter tissue- and differentiation-specificity.