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The first report of a Pelecaniformes defensin cluster: characterization of ?-defensin genes in the crested ibis based on BAC libraries.

ABSTRACT: Defensins play a key role in the innate immunity of various organisms. Detailed genomic studies of the defensin cluster have only been reported in a limited number of birds. Herein, we present the first characterization of defensins in a Pelecaniformes species, the crested ibis (Nipponia nippon), which is one of the most endangered birds in the world. We constructed bacterial artificial chromosome libraries, including a 4D-PCR library and a reverse-4D library, which provide at least 40 equivalents of this rare bird's genome. A cluster including 14 ?-defensin loci within 129?kb was assigned to chromosome 3 by FISH, and one gene duplication of AvBD1 was found. The ibis defensin genes are characterized by multiform gene organization ranging from two to four exons through extensive exon fusion. Splicing signal variations and alternative splice variants were also found. Comparative analysis of four bird species identified one common and multiple species-specific duplications, which might be associated with high GC content. Evolutionary analysis revealed birth-and-death mode and purifying selection for avian defensin evolution, resulting in different defensin gene numbers among bird species and functional conservation within orthologous genes, respectively. Additionally, we propose various directions for further research on genetic conservation in the crested ibis.

SUBMITTER: Lan H

PROVIDER: S-EPMC5381368 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature

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The first report of a Pelecaniformes defensin cluster: characterization of β-defensin genes in the crested ibis based on BAC libraries.

Lan Hong H Chen Hui H Chen Li-Cheng LC Wang Bei-Bing BB Sun Li L Ma Mei-Ying MY Fang Sheng-Guo SG Wan Qiu-Hong QH

Scientific reports 20141105

Defensins play a key role in the innate immunity of various organisms. Detailed genomic studies of the defensin cluster have only been reported in a limited number of birds. Herein, we present the first characterization of defensins in a Pelecaniformes species, the crested ibis (Nipponia nippon), which is one of the most endangered birds in the world. We constructed bacterial artificial chromosome libraries, including a 4D-PCR library and a reverse-4D library, which provide at least 40 equivalen ...[more]

PMID: 25372018

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Project description:BackgroundCitrus species constitute one of the major tree fruit crops of the subtropical regions with great economic importance. However, their peculiar reproductive characteristics, low genetic diversity and the long-term nature of tree breeding mostly impair citrus variety improvement. In woody plants, genomic science holds promise of improvements and in the Citrus genera the development of genomic tools may be crucial for further crop improvements. In this work we report the characterization of three BAC libraries from Clementine (Citrus clementina), one of the most relevant citrus fresh fruit market cultivars, and the analyses of 46.000 BAC end sequences. Clementine is a diploid plant with an estimated haploid genome size of 367 Mb and 2n = 18 chromosomes, which makes feasible the use of genomics tools to boost genetic improvement.ResultsThree genomic BAC libraries of Citrus clementina were constructed through EcoRI, MboI and HindIII digestions and 56,000 clones, representing an estimated genomic coverage of 19.5 haploid genome-equivalents, were picked. BAC end sequencing (BES) of 28,000 clones produced 28.1 Mb of genomic sequence that allowed the identification of the repetitive fraction (12.5% of the genome) and estimation of gene content (31,000 genes) of this species. BES analyses identified 3,800 SSRs and 6,617 putative SNPs. Comparative genomic studies showed that citrus gene homology and microsyntheny with Populus trichocarpa was rather higher than with Arabidopsis thaliana, a species phylogenetically closer to citrus.ConclusionIn this work, we report the characterization of three BAC libraries from C. clementina, and a new set of genomic resources that may be useful for isolation of genes underlying economically important traits, physical mapping and eventually crop improvement in Citrus species. In addition, BAC end sequencing has provided a first insight on the basic structure and organization of the citrus genome and has yielded valuable molecular markers for genetic mapping and cloning of genes of agricultural interest. Paired end sequences also may be very helpful for whole-genome sequencing programs.

Dataset Information

The first report of a Pelecaniformes defensin cluster: characterization of ?-defensin genes in the crested ibis based on BAC libraries.

Publications

The first report of a Pelecaniformes defensin cluster: characterization of β-defensin genes in the crested ibis based on BAC libraries.

Similar Datasets

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