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1.
Adaptions of the polymerase chain reaction were used to isolate cDNA sequences encoding the Major histocompatibility complex(Mhc) class II A gene(s) of the striped bass (Morone saxatilis). Four complete Mhc class II A genes were cloned and sequenced from a specimen originating in the Roanoke River, North Carolina, and another three A genes from a specimen originating from the Santee-Cooper Reservoir, South Carolina, identifying a total of seven unique sequences. The sequence suggests the presence of at least two Mhc class II A loci. The extensive sequence variability observed between the seven different Mhc class II clones was concentrated in the 1 encoding domain. The encoded 2, transmembrane, and cytoplasmic regions of all seven striped genes correlated well with those of known vertebrate Mhc class II proteins. Overall, the striped bass sequences showed greatest similarity to the Mhc class II A genes of the zebrafish. Southern blot analysis demonstrated extensive polymorphism in the Mhc class II A genes in members of a Roanoke river-caught population of striped bass versus a lesser degree of polymorphism in an aquacultured Santee-Cooper population of striped bass.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers (Mosa-A-S5) L35062, (Mosa-A-S8) L35066, (Mosa-A-R7) L35067, and (Mosa-A-S7) L35072 L35066, (Mossa-A-R7) L35067, and (Mosa-A-S7) L35072 相似文献
2.
Although major histocompatibility complex (Mhc) genes have been identified in a number of species, little is yet known about their organization in species other than human
and mouse. The zebrafish, Danio rerio, is a good candidate for full elucidation of the organization of its Mhc. As a step toward achieving this goal, a commercially available zebrafish BAC library was screened with probes specific for
previously identified zebrafish class I and class II genes, as well as for genes controlling the proteasome subunits LMP7
and LMP2. Restriction maps of the individual positive clones were prepared and the Mhc (LMP7) genes localized to specific fragments. The total length of genomic DNA fragments with Mhc genes was approximately 1700 kilobases (kb) (200 kb of fragments bearing class I loci and 1500 kb of fragments bearing class
II loci). One of the two class I loci (Dare-UCA) is closely associated with the LMP7 locus; the second class I locus (Dare-UAA) is more than 50 kb distant from the UCA locus and has no LMP genes associated with it. None of the class II genes are linked to the class I or the LMP genes. All six of the previously identified class II B genes and one of the three class II A genes were found to be present in the BAC clones; no new Mhc loci could be identified in the library. Each of the six previously identified class II B loci was found to be borne by a separate group of BAC clones. The Dare-DAB and -DAA loci were found on the same clone, approximately 15 kb apart from each other. An expansion of DCB and DDB loci was detected: the zebrafish genome may contain at least five closely related DCB and two closely related DDB loci which are presumably the products of relatively recent tandem duplication. These results are consistent with linkage
studies and indicate that in the zebrafish, the class I and class II loci are on different chromosomes, and the class II loci
are in three different regions, at least two of which are on different chromosomes.
Received: 14 August 1997 / Revised: 16 September 1997 相似文献
3.
Dynamics of Mhc evolution in birds and crocodilians: amplification of class II genes with degenerate primers 总被引:7,自引:0,他引:7
Genes of the major histocompatibility complex (Mhc) are the most polymorphic functional loci in mammalian populations, but little is known of Mhc variability in natural populations of nonmammalian vertebrates. To help extend such studies to birds and relatives, we present a pair of degenerate primers that amplify polymorphic segments of one chain (the β chain) of the class II genes from the major histocompatibility complex (Mhc) of archosaurs (birds + crocodilians). The primers target two conserved regions lying within portions of the antigen-binding site (ABS) encoded by the second exon and amplify multiple genes from both genomic DNA and cDNA. The pattern of nucleotide substitution in ABS codons of 51 sequences amplified and cloned from five species of passerine birds and an alligator (Alligator mississippiensis) indicates that archosaurian class II β genes are subject to selective forces similar to those operating in mammalian populations. Hybridization of a genomic clone generated by the primers revealed highly polymorphic bands in a sample of Florida scrub jays (Aphelocoma coerulescens coerulescens). Because the primers amplify only part of the ABS from multiple class II genes, they will be useful primarily for generating species specific clones, thereby providing a critical inroad to more detailed structural and evolutionary studies. 相似文献
4.
Jasna Bingulac-Popovic F. Figueroa Akie Sato William S. Talbot Stephen L. Johnson Michael Gates J. H. Postlethwait Jan Klein 《Immunogenetics》1997,46(2):129-134
The mammalian major histocompatibility complex (Mhc) consists of three closely linked regions, I, II, and III, occupying a single chromosomal segment. The class I loci in region
I and the class II loci in region II are related in their structure, function, and evolution. Region III, which is intercalated
between regions I and II, contains loci unrelated to the class I and II loci, and to one another. There are indications that
a similar Mhc organization exists in birds and amphibians. Here, we demonstrate that in the zebrafish (Danio rerio), a representative of the teleost fishes, the class II loci are divided between two linkage groups which are distinct from
the linkage group containing the class I loci. The β2-microglobulin-encoding gene is loosely linked to one of the class II loci. The gene coding for complement factor B, which
is one of the region III genes in mammals, is linked neither to the class I nor to the class II loci in the zebrafish. These
results, combined with preliminary data suggesting that the class I and class II regions in another order of teleost fish
are also in different linkage groups, indicate that close linkage of the two regions is not necessary either for regulation
of expression or for co-evolution of the class I and class II loci. They also raise the question of whether linkage of the
class I and class II loci in tetrapods is a primitive or derived character.
Received: 16 December 1996 / Revised: 6 February 1997 相似文献
5.
Nonlinkage of major histocompatibility complex class I and class II loci in bony fishes 总被引:11,自引:10,他引:1
Sato A Figueroa F Murray BW Málaga-Trillo E Zaleska-Rutczynska Z Sültmann H Toyosawa S Wedekind C Steck N Klein J 《Immunogenetics》2000,51(2):108-116
In tetrapods, the functional (classical) class I and class II B loci of the major histocompatibility complex (Mhc) are tightly linked in a single chromosomal region. In an earlier study, we demonstrated that in the zebrafish, Danio rerio, order Cypriniformes, the two classes are present on different chromosomes. Here, we show that the situation is similar in
the stickleback, Gasterosteus aculeatus, order Gasterosteiformes, the common guppy, Poecilia reticulata, order Cyprinodontiformes, and the cichlid fish Oreochromis niloticus, order Perciformes. These data, together with unpublished results from other laboratories suggest that in all Euteleostei,
the classical class I and class II B loci are in separate linkage groups, and that in at least some of these taxa, the class II loci are in two different groups.
Since Euteleostei are at least as numerous as tetrapods, in approximately one-half of jawed vertebrates, the class I and class II
regions are not linked.
Received: 30 August 1999 / Revised: 20 October 1999 相似文献
6.
A polymorphic system related to but genetically independent of the chicken major histocompatibility complex 总被引:21,自引:9,他引:12
Analyses of the major histocompatibility complex (Mhc) in chickens have shown inconsistencies between serologically defined haplotypes and haplotypes defined by the restriction fragment patterns of Mhc class I and class II genes in Southern hybridizations. Often more than one pattern of restriction fragments for Mhc class I and/or class II genes has been found among DNA samples collected from birds homozygous for a single serologically defined B haplotype. Such findings have been interpreted as evidence for variability within the Mhc haplotypes of chickens not detected previously with serological methods. In this study of a fully pedigreed family over three generations, the heterogeneity observed in restriction fragment patterns was found to be the result of the presence of a second, independently segregating polymorphic Mhc-like locus, designated Rfp-Y. Three alleles (haplotypes) are identified in this new system. 相似文献
7.
Shiina T Shimizu C Oka A Teraoka Y Imanishi T Gojobori T Hanzawa K Watanabe S Inoko H 《Immunogenetics》1999,49(5):384-394
Class I genomic clones of the quail (Coturnix japonica) major histocompatibility complex (MhcCoja) were isolated and characterized. Two clusters spanning the 90.8 kilobase (kb) and 78.2 kb class I gene regions were defined
by overlapping cosmid clones and found to contain at least twelve class I loci. However, unlike in the chicken Mhc, no evidence for the existence of any Coja class II gene was obtained in these two clusters. Based on comparative analysis of the genomic sequences with those of the
cDNA clones, Coja-A, Coja-B, Coja-C, and Coja-D (Shiina et al. 1999), these twelve loci were assigned to represent one Coja-A gene, two Coja-B genes (Coja-B1 and -B2), four Coja-C genes (Coja-C1-C4), four Coja-D genes (Coja-D1-D4), and one new Coja-E gene. A class I gene-rich segment of 24.6 kb in which five of these genes (Coja-B1, -B2, -D1, -D2 and -E) are densely packed were sequenced by the shotgun strategy. All of these five class I genes are very compact in size [2089
base pairs (bp)–2732 bp] and contain no apparent genetic defect for functional expression. A transporter associated with the
antigen processing (TAP) gene was identified in this class I gene-rich segment. These results suggest that the quail class I region is physically
separated from the class II region and characterized by a large number of the expressible class I loci (at least seven) in
contrast to the chicken Mhc, where the class I and class II regions are not clearly differentiated and only at most three expressed class I loci so far
have been recognized.
Received: 9 March 1998 / Revised: 12 October 1998 相似文献
8.
The zebrafish (Brachydanio rerio) offers many advantages for immunological and immunogenetic research and has the potential for becoming one of the most important nonmammalian vertebrate research models. With this in mind, we initiated a systematic study of the zebrafish major histocompatibility complex (Mhc) genes. In this report, we describe the cloning and characteristics of the zebrafish class I A genes coding for the chains of the heterodimer and thus complete the identification of all four classes and subclasses of the Mhc in this species. We describe the full class I cDNA sequence as well as the exon-intron organization of the class I A genes, including intron sequences. We identify three families of class I A genes which we designate Bree-UAA,-UBA, and -UCA. The three families originated about the time of the divergence of cyprinid and salmonid fishes. All three families are members of an ancient lineage that diverged from another, older lineage also represented in cyprinid fishes before the radiation of teleost orders. The fish class I A genes therefore evolve differently from mammalian class I A genes, in which the establishment of lineages and families mostly postdates the divergence of orders.The nucleotide sequence data reported in this Papershave been submitted to the EMBL/GenBank nucleotide sequence databases and have been assigned the accession numbers Z46776–Z46779 相似文献
9.
In order to understand the expression and evolution of host resistance to pathogens, we need to examine the links between genetic variability at the major histocompatibility complex (Mhc), phenotypic expression of the immune response and parasite resistance in natural populations. To do so, we characterized the Mhc class I and IIB genes of house sparrows with the goal of designing a PCR-based genotyping method for the Mhc genes using denaturing gradient gel electrophoresis (DGGE). The incredible success of house sparrows in colonizing habitats worldwide allows us to assess the importance of the variability of Mhc genes in the face of various pathogenic pressures. Isolation and sequencing of Mhc class I and IIB alleles revealed that house sparrows have fewer loci and fewer alleles than great reed warblers. In addition, the Mhc class I genes divided in two distinct lineages with different levels of polymorphism, possibly indicating different functional roles for each gene family. This organization is reminiscent of the chicken B complex and Rfp-Y system. The house sparrow Mhc hence appears to be intermediate between the great reed warbler and the chicken Mhc, both in terms of numbers of alleles and existence of within-class lineages. We specifically amplified one Mhc class I gene family and ran the PCR products on DGGE gels. The individuals screened displayed between one and ten DGGE bands, indicating that this method can be used in future studies to explore the ecological impacts of Mhc diversity. 相似文献
10.
Major histocompatibility complex (Mhc) genes influencing transplantation rejections were first described in mice within the H2 complex and secondly in chickens within the B complex. In chickens, Rfp-Y haplotypes have recently been identified which contain class I and class II Mhc-like genes that assort independently of the B complex. Three Rfp-Y haplotypes have been defined in a closed breeding flock of line N chickens. In this study, progeny were obtained from line
N Rfp-Y heterozygous matings to establish the role of Rfp-Y in transplantation immunity. Rfp-Y incompatibility did not induce significant one-way mixed lymphocyte responses. However, Rfp-Y-incompatible skin grafts were rejected more frequently and at a faster rate than Rfp-Y-compatible grafts by two-week-old chicks. The control Mhc B-incompatible grafts were rejected faster than the Rfp-Y-incompatible grafts; the latter were rejected at speeds that resemble rejection of minor histocompatibility antigens. We
conclude that Rfp-Y class I and II Mhc-like genes are linked to the expression of minor histocompatibility antigens in chickens.
Received: 21 June 1996 / Revised: 23 July 1996 相似文献
11.
The major histocompatibility complex (Mhc) encodes for highly variable molecules, responsible for foreign antigen recognition and subsequent activation of immune responses
in hosts. Mhc polymorphism should hence be related to pathogen resistance and immune activity, with individuals that carry either a higher
diversity of Mhc alleles or one specific Mhc allele exhibiting a stronger immune response to a given antigen. Links between Mhc alleles and immune activity have never been explored in natural populations of vertebrates. To fill this gap, we challenged
house sparrows (Passer domesticus) with two T-dependent antigens (phytohemagglutinin and sheep red blood cells) and examined both primary and secondary immune
responses in relation to their Mhc class I genotypes. The total number of Mhc alleles had no influence on either primary or secondary response to the two antigens. One particular Mhc allele, however, was associated with an increased response to both antigens. Our results point toward a contribution of the
Mhc, or of other genes in linkage disequilibrium with the Mhc, in the regulation of immune responses in a wild animal species. 相似文献
12.
Jan Klein Yoko Satta Naoyuki Takahata Colm O'hUigin 《Journal of medical primatology》1993,22(1):57-64
The major histocompatibility complex (Mhc) is a cluster of loci controlling the specific immune response in vertebrates. Mhc alleles often differ by a large number of nucleotide substitutions, some of which began to accumulate before the emergence of extant species. We have applied the theory of allelic genealogy to the primate Mhc genes with the aim of estimating the size of the founding populations. The calculations indicate that the long-term effective population size of the studied species was between 104 and 105 individuals and that it most likely never dropped below 103 individuals. 相似文献
13.
Recent duplication and inter-locus gene conversion in major histocompatibility class II genes in a teleost,the three-spined stickleback 总被引:3,自引:3,他引:0
Using a bacterial artificial chromosome (BAC) library, we analysed a 99.5 kb genomic segment containing the major histocompatibility class II genes of a teleost, the three-spined stickleback Gasterosteus aculeatus. Experiments with G. aculeatus have provided direct evidence for balancing selection by pathogens and mate choice driving MH class II beta polymorphism. Two sets of paralogous class II alpha genes and beta genes in a tandem arrangement were identified, designated Gaac-DAA/DAB and Gaac-DBA/DBB. Expression analysis of the beta genes using single-strand conformation polymorphism revealed that both gene copies are expressed. Based on an analysis of pairwise nucleotide polymorphisms, we estimate that the duplication into two paralogous class II loci occurred only 1.2–2.4 million years ago, 1–2 orders of magnitude more recently than in other fish, bird or mammalian species. At the 3-direction of the classical MH loci, we identified another seven genes or gene fragments, two of which (small inducible cytokine, complement regulatory factor) are related to immune function in other vertebrates. None of these genes were associated with MH class II genes in zebrafish, suggesting a markedly different organisation of the MH class II region in sticklebacks, and presumably, across bony fishes. When the nucleotide substitution pattern of the novel class II beta genes was analysed together with a representative sequence sample isolated from fish in northern Germany (n=27), we found that the peptide binding region of the Gaac-DAB and Gaac-DBB loci had undergone an inter-locus gene conversion (P=0.007). In accordance, we found a 10- to 20-fold higher frequency of CpG-islands on the MH class II segment compared to other species, a feature that may be conducive for inter-locus recombination. 相似文献
14.
The class I genes of the major histocompatibility complex (Mhc) are here investigated for the first time in a passerine bird. The great reed warbler is a rare species in Sweden with a
few semi-isolated populations. Yet, we found extensive Mhc class I variation in the study population. The variable exon 3, corresponding to the α2 domain, was amplified from genomic DNA with degenerated primers. Seven different genomic class I sequences were detected
in a single individual. One of the sequences had a deletion leading to a shift in the reading frame, indicating that it was
not a functional gene. A randomly selected clone was used as a probe for restriction fragment length polymorphism (RFLP) studies
in combination with the restriction enzyme Pvu II. The RFLP pattern was complex with 21–25 RFLP fragments per individual and extensive variation. Forty-nine RFLP genotypes
were detected in 55 tested individuals. To study the number of transcribed genes, we isolated 14 Mhc class I clones from a cDNA library from a single individual. We found eight different sequences of four different lengths
(1.3–2.2 kilobases), suggesting there are at least four transcribed loci. The number of nonsynonymous substitutions (d
N
) in the peptide binding region of exon 3 were higher than the number of synonymous substitutions (d
S
), indicating balancing selection in this region. The number of transcribed genes and the numerous RFLP fragments found so
far suggest that the great reed warbler does not have a "minimal essential Mhc" as has been suggested for the chicken.
Received: 13 May 1998 / Revised: 18 August 1998 相似文献
15.
Expression of too many co-dominant major histocompatibility complex (MHC) alleles is thought to be detrimental to proper functioning of the immune system. Polyploidy of the genome will increase the number of expressed MHC genes unless they are prone to a silencing mechanism. In polyploid Xenopus species, the number of MHC class I and II genes has been physically reduced, as it does not increase with higher ploidy genomes. In the zebrafish some class IIB loci have been silenced, as only two genomically bona fide loci, DAA/DAB and DEA/DEB, have been described. Earlier studies indicated a reduction in the number of genomic and expressed class II MHC genes in a hexaploid African large barb. This prompted us to study the number of MHC genes present in the genome of an African large barb individual (Barbus intermedius) in relation to those expressed, adopting the following strategy. Full-length cDNA sequences were generated from mRNA and compared with partial genomic class Ia and II sequences generated by PCR using the same primer set. In addition, we performed Southern hybridizations to obtain a verification of the number of class I and IIB genes. Our study revealed three 2-microglobulin, five class Ia, four class IIA, and four class IIB genes at the genomic level, which were shown to be expressed in the hexaploid barb individual. The class Ia and class II data indicate that the ploidy status does not correlate with the presence and expression of these MHC genes. 相似文献
16.
The genes of the major histocompatibility complex (MHC) are amongst the most variable in vertebrates and represent some of
the best candidates to study processes of adaptive evolution. However, despite the number of studies available, most of the
information on the structure and function of these genes come from studies in mammals and birds in which the MHC class I and
II genes are tightly linked and class II alpha exhibits low variability in many cases. Teleost fishes are among the most primitive
vertebrates with MHC and represent good organisms for the study of MHC evolution because their class I and class II loci are
not physically linked, allowing for independent evolution of both classes of genes. We have compared the diversity and molecular
mechanisms of evolution of classical MH class II α and class II β loci in farm populations of three salmonid species: Oncorhynchus kisutch, Oncorhynchus mykiss and Salmo salar. We found single classical class II loci and high polymorphism at both class II α and β genes in the three species. Mechanisms
of evolution were common for both class II genes, with recombination and point mutation involved in generating diversity and
positive selection acting on the peptide-binding residues. These results suggest that the maintenance of variability at the
class IIα gene could be a mechanism to increase diversity in the MHC class II in salmonids in order to compensate for the
expression of one single classical locus and to respond to a wider array of parasites. 相似文献
17.
Ulf Gyllensten Tomas Bergström Agnetha Josefsson Mats Sundvall Anne Savage Evan S. Blumer L. Humberto Giraldo Luis H. Soto David I. Watkins 《Immunogenetics》1994,40(3):167-176
Cotton-top tamarins (Saguinus oedipus) in captivity are unusual in that they exhibit low levels of polymorphism and allelic diversity at the major histocompatibility complex (Mhc) class I loci. Since the polymorphism has previously only been examined in captive tamarins, we analyzed the Mhc class I alleles of a population of wild tamarins. These wild tamarins, like their captive counterparts, exhibited limited class I polymorphism. We also assessed the levels of polymorphism and allelic diversity at the Mhc class II DQA1, DQB1, DQB2, and the DRB loci in captive populations of cotton-top tamarins. In contrast to the extensive polymorphism in Old World monkeys, only two alleles were detected at each of DQA1 and DQB1. Also, the DQB2 locus was monomorphic and conserved between New and Old World monkeys. Sequences derived from four putative DRB loci were obtained, and extensive polymorphism was found at all four loci. Phylogenetic analysis did not indicate that any of the tamarin DRB loci, with the possible exception of Saoe-DRB3, were orthologous to the human DRB loci. At three of the DRB loci (Saoe-DRB11, Saoe-DRB
*
W12, Saoe-DRB
*
W22), the number of nonsynonymous changes was higher than the number of synonymous changes in the putative antigen recognition sites, indicative of positive selection. We found no support for a restriction on the polymorphism at the cotton-top tamarin class II loci. However, the allelic diversity at some of the Saoe-DRB loci is more limited than for the HLA-DRB1, consistent with a restriction imposed by the bone marrow-chimerical lifestyle. 相似文献
18.
In terms of number of species, perciform (perch-like) fishes are one of the most diversified groups of modern vertebrates.
Within this group, the family Cichlidae is best known for its spectacular adaptive radiation in the great lakes of East Africa.
The molecular tool kit used in the study of this radiation includes the major histocompatibility complex (Mhc) genes. To refine this tool, information about the organization of the Mhc regions is badly needed. In this study, the first step was taken toward providing such information for the Mhc class one regions of Oreochromis niloticus, a representative species of the tilapiine branch of the Cichlidae, for which good bacterial artificial chromosome library
is available. Screening of the library with class I gene probes led to the identification and isolation of 31 class-I-positive
clones. Sequencing of one of these clones and partial characterization of the remaining clones for the presence of class I
exons resulted in the construction of two contigs representing the class I region of this species as well as identification
of seven additional class-I-positive singleton clones. The O. niloticus genome was shown to contain at least 28 class I genes or gene fragments. The shorter of the two contigs was approximately
330 kb long and contained eight class I genes/gene fragments; the longer contig encompassed 1,200 kb of sequence and contained
minimally 17 class I genes/gene fragments; three additional class I genes were found to be borne by a clone that might be
part of the shorter contig.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.
This work had been carried out in part at the Max-Planck-Institut für Biologie, Abteilung Immungenetik, Tübingen, Germany
(A.S., R.D., N.T., S.S., and J.K.).
The sequences reported in this paper have been deposited in the GenBank database (accession nos. AB270803–AB270897). 相似文献
19.
Little is known about the major histocompatibility (Mhc) genes of birds in different taxonomic groups or about how Mhc genes may be organized in avian species divergent by evolution or habitat. Yet it seems likely that much might be learned from birds about the evolution, organization, and function of this intricate complex of polymorphic genes. In this study a close relative of the chicken, the ring-necked pheasant (Phasianus colchicus), was examined for the presence and organization of Mhc B-G genes. The patterns of restriction fragments revealed by chicken B-G probes in Southern hybridizations and the patterns of pheasant erythrocyte polypeptides revealed in immunoblots by antisera raised against chicken B-G polypeptides provide genetic, molecular, and biochemical data confirming earlier serological evidence for the presence of B-G genes in the pheasant, and hence, the presence of a family of B-G genes in at least a second species of birds. The high polymorphism exhibited by the pheasant B-G gene family allowed genetic differences among individuals within the small experimental population in this study to be detected easily by restriction fragment patterns. Further evidence was found for the organization of the pheasant Mhc class I and class II genes into genetically independent clusters. Whether these gene clusters are fully comparable to the B and Rfp-Y systems in the chicken or whether yet another organization of Mhc genes has been encountered in the pheasant remains to be determined. 相似文献
20.