Physical mapping of the giant panda immunoglobulin heavy chain constant region genes
Zhihui ZhaoYaofeng ZhaoQiang Pan‐HammarströmWei LiuZhaoliang LiuYonghui ZhaoNing LiLennart Hammarström
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Immunoglobulin heavy chain
Abstract Only 14 of the 25 V χ genes and pseudogenes had been found before as parts of the L regions. The cloning and linking described in the accompanying report allowed us now to assign to Lp or Ld some V χ genes which had been found before on scattered clones. In addition the sequences of several still unknown genes are reported here, thus completing the publication of the V χ genes of the x locus as far as they are potentially functional or have only one or two 1‐bp defects. Of the V χ genes of the K locus, 32 are potentially functional, 16 have minor defects, 3 have both potentially functional and slightly defective alleles and 25 are pseudogenes which amounts to a repertoire of 76 V χ ‐related gene sequences. The V χ genes of the L regions are, within the subgroups, particularly similar to each other, which is in part due to common evolutionary origins and in part caused by gene conversion‐like events. One donor‐acceptor pair could be clearly identified, since converted and not‐converted alleles of the acceptor gene were found. In other cases the duplicates of the converted genes served as non‐converted controls.
Pseudogene
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Mendelian inheritance
Phosphoglucomutase
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Colletotrichum lindemuthianum
Candidate gene
R gene
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Abstract The A mating type locus of Coprinus cinereus determines mating compatibility by regulating essential steps in sexual development. Each A locus contains several genes separated into two functionally independent complexes termed Aα and Aβ, and the multiple alleles of these genes generate an estimated 160 A mating specificities. The genes encode two classes of homeodomain-containing proteins designated HD1 and HD2. In this report we describe two newly cloned loci, A2 and A5, and compare them with A42, A43 and A6 that we have described previously. An Aβ-null locus, retaining just a single active HD1 gene from the α-complex, was generated by mutation. Using this as a transformation host, gene combinations that promote A-regulated development were identified. We demonstrate that each A locus contains members of three paralogous pairs of HD1 and HD2 genes. Different allelic versions of gene pairs are compatible but paralogous genes are incompatible. The genes present in four uncloned A loci were deduced using Southern analyses and transformations with available cloned genes. The combined analysis of nine A factors identifies sufficient A gene alleles to generate at least 72 A mating specificities.
Coprinus
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Summary Three rust resistance specificities, N , N1 and N2 , map to the complex N locus of flax. We used a degenerate PCR approach, with primers directed to the nucleotide binding site (NBS) domain characteristic of many plant resistance genes, to isolate resistance gene analogs (RGAs) from flax. One RGA clone detected RFLPs co‐segregating with alleles of the N locus. With this probe we isolated four related genes that occur within a 30kbp region and encode proteins with NBS and leucine‐rich repeat (LRR) domains and N‐terminal Toll/Interleukin‐1 Receptor homology (TIR) domains. One of these four genes was identified as the N resistance gene by sequence analysis of three mutant alleles and by transgenic expression. We isolated homologous genes from two flax lines containing the N1 or N2 specificities and from flax lines carrying no N locus resistance specificities. Analysis of shared polymorphisms among this set of 18 N locus sequences revealed three groups of genes with independent lineages. Sequence exchanges have only occurred between genes within each group, but not between groups. Two of the groups contain only one sequence from each haplotype and probably represent orthologous genes. However, the third group contains two genes from each haplotype. We suggest that the re‐assortment of variation by recombination/gene conversion at this locus is limited by the degree of sequence identity between genes.
Homology
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Leucine-rich repeat
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Cosmid
Genetic linkage
Chromosomal region
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ABSTRACT A method of mapping genes which specify enzymes without the necessity of obtaining genetic variants has been explored. Three enzymes whose structural genes have known genetic positions were chosen to see if the relationship between gene dosage and enzyme activity could be used as a tool in cytological localization. Zw, the gene specifying G6PD, is located in the X chromosome region, 18D-18F. The structural gene for 6PGD, Pgd, maps in the X chromosome bands 2C1-2E1. Idh-NADP, the gene which specifies IDH-NADP, is found on the third chromosome, in bands 66B-67C.
Structural gene
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Genetic linkage
Stripe rust
Rust (programming language)
Common wheat
Chromosomal region
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