Duplication of chicken defensin7 gene generated by gene conversion and homologous recombination (original) (raw)
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Expression and polymorphism of defensins in farm animals
Acta biochimica Polonica, 2010
Due to their activity against bacteria, viruses, and fungi, antimicrobial peptides are important factors in the innate resistance system of humans and animals. They are called "new generation antibiotics" for their potential use in preventive and therapeutic medicine. The most numerous group of antimicrobial peptides is a family of cationic peptides which include defensins and cathelicidins. Among them the most common are peptides with a beta-sheet structure containing three intra-molecular disulphide bonds, called defensins, comprising three classes: alpha, beta, and theta. The class of beta-defensins is the largest one. Their transcripts have been found in many tissues of humans and animals. The aim of this paper is to present the current knowledge about antimicrobial peptides from the defensin family in farm animals, their expression, polymorphism, as well as the potential of their use as genetic markers of health and production traits.
Avian Beta Defensin 2 (AvBD2) Gene Polymorphism Identification in IPB-D1 Chicken
Jurnal Ilmu Ternak dan Veteriner, 2021
Avian Beta Defensin 2 (AvBD2) gene, which is located in chromosome 3, plays an important role in the immune system of the chicken by inhibiting the development of microorganisms such as bacteria that infect body tissues. Defensins are produced through epithelial cells immediately after tissue injury or infection, which then processes the maturation of dendritic cells to initiate an immune response in the lymph nodes. The purpose of this study was to discover the polymorphism of the AvBD2 gene in IPB-D1 chickens. PCR and direct-DNA sequencing methods were used to identify the diversity of intron 1, exon 2, and intron 2 AvDB2 genes in 47 chickens. Genotype and allele frequency, and heterozygosity calculations were carried out to obtain information of the AvBD2 gene polymorphism. A total of 10 single nucleotide polymorphisms were found in the AvBD2 gene located in intron 1 (g.4843T>A, g.4853G>A, and g.4859T>C), exon 2 (g.4881A>G, g.4889G>A, and g.5002C>T), and intron ...
Asian-Australasian journal of animal sciences, 2018
Defensins are a large family of antimicrobial peptides and components of the innate immune system that invoke an immediate immune response against harmful pathogens. Defensins are classified into alpha-, beta-, and theta-defensins. Avian species only possess beta-defensins (AvBDs), and approximately 14 AvBDs (AvBD1-AvBD14) have been identified in chickens to date. Although substantial information is available on the conservation and phylogenetics, limited information is available on the expression and regulation of AvBD8 in chicken immune tissues and cells. We examined AvBD8 protein expression in immune tissues of White Leghorn chickens (WL) by immunohistochemistry and quantitative reverse transcription-PCR (RT-qPCR). In addition, we examined AvBD8 expression in chicken T-, B-, macrophage-, and fibroblast-cell lines and its regulation in these cells after lipopolysaccharide (LPS) treatment by immunocytochemistry and RT-qPCR. Our results showed that chicken AvBD8 protein was strongly...
Immunogenetics, 2005
Antimicrobial peptides are essential components of innate immunity and are generally thought to act by disrupting the membrane integrity of microbes. Here we report the discovery of two novel chicken β-defensins, gallinacin (Gal)-11 and Gal-12, found by hidden Markov model profile searching of the chicken genome. We have sequenced the genes and elucidated the 3′UTR of Gal-11. Differential mRNA expression of these novel genes has been shown across a panel of chicken tissues. Gal-11 mRNAwas highly expressed in the small intestine, the liver, the gall bladder and the spleen and also showed moderate expression in several other areas of the chicken anatomy, whilst Gal-12 mRNAwas found only in the liver and the gall bladder. Antimicrobial activity of synthetic Gal-11 has been demonstrated against a range of bacteria and is predominantly active against the intestinal pathogens Salmonella typhimurium and Listeria monocytogenes.
Frontiers in Immunology, 2015
Defensins represent an evolutionary ancient family of antimicrobial peptides that play diverse roles in human health and disease. Defensins are cationic cysteine-containing multifunctional peptides predominantly expressed by epithelial cells or neutrophils. Defensins play a key role in host innate immune responses to infection and, in addition to their classically described role as antimicrobial peptides, have also been implicated in immune modulation, fertility, development, and wound healing. Aberrant expression of defensins is important in a number of inflammatory diseases as well as modulating host immune responses to bacteria, unicellular pathogens, and viruses. In parallel with their role in immunity, in other species, defensins have evolved alternative functions, including the control of coat color in dogs. Defensin genes reside in complex genomic regions that are prone to structural variations and some defensin family members exhibit copy number variation (CNV). Structural variations have mediated, and continue to influence, the diversification and expression of defensin family members.This review highlights the work currently being done to better understand the genomic architecture of the β-defensin locus. It evaluates current evidence linking defensin CNV to autoimmune disease (i.e., Crohn's disease and psoriasis) as well as the contribution CNV has in influencing immune responses to HIV infection.
Immunome Research, 2010
Background: Avian β-defensins (AvBDs) represent a group of innate immune genes with broad antimicrobial activity. Within the chicken genome, previous work identified 14 AvBDs in a cluster on chromosome three. The release of a second bird genome, the zebra finch, allows us to study the comparative evolutionary history of these gene clusters between from two species that shared a common ancestor about 100 million years ago. Results: A phylogenetic analysis of the β-defensin gene clusters in the chicken and the zebra finch identified several cases of gene duplication and gene loss along their ancestral lines. In the zebra finch genome a cluster of 22 AvBD genes were identified, all located within 125 Kbp on chromosome three. Ten of the 22 genes were found to be highly conserved with orthologous genes in the chicken genome. The remaining 12 genes were all located within a cluster of 58 Kbp and are suggested to be a result of recent gene duplication events that occurred after the galliformes-passeriformes split (G-P split). Within the chicken genome, AvBD6 was found to be a duplication of AvBD7, whereas the gene AvDB14 seems to have been lost along the ancestral line of the zebra finch. The duplicated β-defensin genes have had a significantly higher accumulation of non-synonymous over synonymous substitutions compared to the genes that have not undergone duplication since the G-P split. The expression patterns of avian β-defensin genes seem to be well conserved between chicken and zebra finch.
Applied Microbiology and Biotechnology, 2010
In this study, a newly identified avian β-defensin (AvBD) orthologue was isolated from Chinese painted quail (Coturnix chinensis) lung and bone marrow tissues. The complete nucleotide sequence of the gene contained a 204-bp open-reading frame encoding 67 amino acids. Homology, characterization, and comparison of the gene with AvBD from other avian species confirmed that it was quail AvBD9. To analyze and compare the expression pattern of AvBD9 in tissues from young and adult quails, layer hens, and broilers, reverse transcription polymerase chain reaction was performed using mRNA isolated from 21 different tissues. The AvBD9 expression pattern distribution was differed among quails of different ages, layer hens, and broilers. It was widely expressed in all the tissues except the trachea, liver, and kidney and was highly expressed in the lung and heart of young quails. Similarly, it was widely expressed in all the tissues of adult quails except for the liver, kidney, spleen, thymus, and Harderian gland. In layer hens, AvBD9 was widely expressed in all the tissues except the trachea, glandular stomach, and cecum. Similarly, it was widely expressed in all the tissues of broilers except for the trachea, glandular stomach, rectum, cecum, bone marrow, and cecal tonsil. Recombinant AvBD9 (rAvBD9) was produced and purified by expressing the gene in Escherichia coli. Additionally, peptide according to quail AvBD9 sequence was synthesized, named sAvBD9. As expected, both rAvBD9 and sAvBD9 exhibited strong bactericidal properties against 11 strains of bacteria, including Grampositive and Gram-negative forms.
Immunogenetics, 2007
Antimicrobial peptides (AMPs), essential components of innate immunity, are found in a range of phylogenetically diverse species and are thought to act by disrupting the membrane integrity of microbes. In this paper, we used evolutionary signatures to identify sites that are most relevant during the functional evolution of these molecules and introduced amino acid substitutions to improve activity. We first demonstrate that the anti-microbial activity of chicken avian β-defensin-8, previously known as gallinacin-12, can be significantly increased against Escherichia coli, Listeria monocytogenes, Salmonella typhimurium, Salmonella typhimurium phoP− mutant and Streptococcus pyogenes through targeted amino acid substitutions, which confer increased peptide charge. However, by increasing the AMP charge through amino acid substitutions at sites predicted to be subject to positive selection, antimicrobial activity against Escherichia coli was further increased. In contrast, no further increase in activity was observed against the remaining pathogens. This result suggests that chargeincreasing modifications confer increased broad-spectrum activity to an AMP, whilst positive selection at particular sites is involved in directing the antimicrobial response against specific pathogens. Thus, there is potential for the rational design of novel therapeutics based on specifically targeted and modified AMPs.