| 1. |
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| 2. |
- Abraham, David, et al.
(författare)
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Molecular phylogeny of the subfamilies in Geometridae (Geometroidea: Lepidoptera)
- 2001
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1095-9513 .- 1055-7903. ; 20:1, s. 65-77
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Tidskriftsartikel (refereegranskat)abstract
- Molecular sequence data from three gene fragments were used to examine critically a provisional phylogenetic classification based on morphological characters of the Geometridae, one of the most species-rich families of moths. The sister group relationship between Geometridae and Drepanidae gained further support from the molecular analysis, which was based on the ND1 mitochondrial gene and the first and second expansion segments of the 28S ribosomal RNA gene. Although the alignment of the second expansion segment contained regions with many gaps, it provided the most resolution of the gene fragments. Parsimony analysis of the combined data resulted in a cladogram in which species belonging to Drepanidae, Larentiinae, and Sterrhinae formed monophyletic groups. The Ennominae did not form a monophyletic group but rather were contained within a broader monophyletic group including Archiearinae, Geometrinae, and Alsophilinae (represented by only one species per group in the present study). The molecular results were used to explore further the relationship between Sterrhinae and Larentiinae, the question as to whether Ennominae actually represent a monophyletic group, and the relationships between Ennominae and some of the other subfamilies.
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| 3. |
- Bonneaud, C, et al.
(författare)
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Diversity of Mhc class I and IIB genes in house sparrows (Passer domesticus)
- 2004
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Ingår i: Immunogenetics. - : Springer Science and Business Media LLC. - 1432-1211 .- 0093-7711. ; 55:12, s. 855-865
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 4. |
- Hansson, Maria, et al.
(författare)
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Characterization of two distinct aryl hydrocarbon receptor (AhR2) genes in Atlantic salmon (Salmo salar) and evidence for multiple AhR2 gene lineages in salmonid fish
- 2003
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Ingår i: Gene. - 1879-0038. ; 303, s. 197-206
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Tidskriftsartikel (refereegranskat)abstract
- The aryl hydrocarbon receptor (AhR) mediates the toxicity of several environmental contaminants, e.g. 2,3,7,8-tetrachlorodibenzo-p-dioxin, and other halogenated hydrocarbons in vertebrates. This receptor initiates the transcription of several biotransformation enzymes, which in turn are responsible for causing severe harm to biological tissue. Here we describe the isolation and complete characterization of the first two AhR genes from the teleost fish Atlantic salmon (Salmo salar). The predicted amino acid sequences contain regions characteristic of other vertebrate AhRs including basic helix-loop-helix (bHLH) and PER-ARNT-SIM (PAS) domains but show little similarity to other vertebrate AhRs across the C-terminal half. Furthermore, they do not contain distinct Q-rich domains as found in the mammalian AhR, which is in line with previously described fish AhR genes. The salmon cDNAs encode 1106 and 1107 putative residues, respectively, approximately 50 amino acids longer than previously characterized AhR genes. Phylogenetic analyses demonstrated that the two salmon AhR sequences cluster within the AhR subfamily of the bHLH-PAS family, in a clade containing fish AhR2 genes. Although the two AbR2 forms are 92% identical at the amino acid level, the distribution of sequence differences and the presence of both forms in 30 tested individuals suggest that they are not allelic but derived from separate loci. Interestingly, they are not orthologs of the rainbow trout (Oncorhynchus mykiss) AhR2alpha and beta genes and the new salmon loci are therefore here designated AhR2gamma and AhR2delta. In line with this, PCR with DNA from rainbow trout revealed a new trout AhR locus that was more similar to the two salmon genes than to the trout AhR2alpha and beta genes, suggesting that the rainbow trout possesses at least three distinct AhR2 genes. The presence of multiple AhR genes in these species is probably a consequence of the genome duplications that occurred in the early evolution of fish and later also specifically in the salmonid lineage. Reverse transcription-PCR analyses revealed that both AhR2gamma and AhR2delta are transcribed in the liver, spleen and muscles of adult salmon.
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| 5. |
- Hansson, Maria, et al.
(författare)
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Unprecedented genomic diversity of AhR1 and AhR2 genes in Atlantic salmon (Salmo salar L.)
- 2004
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Ingår i: Aquatic Toxicology. - : Elsevier BV. - 1879-1514 .- 0166-445X. ; 68:3, s. 219-232
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Tidskriftsartikel (refereegranskat)abstract
- Aryl hydrocarbon receptor (AhR) genes encode proteins involved in mediating the toxic responses induced by several environmental pollutants. Here, we describe the identification of the first two AhR1 (alpha and beta) genes and two additional AhR2 (alpha and beta) genes in the tetraploid species Atlantic salmon (Salmo salar L.) from a cosmid library screening. Cosmid clones containing genomic salmon AhR sequences were isolated using a cDNA clone containing the coding region of the Atlantic salmon AhR2gamma as a probe. Screening revealed 14 positive clones, from which four were chosen for further analyses. One of the cosmids contained genomic AhR sequences that were highly similar to the rainbow trout (Oncorhynchus mykiss) AhR2alpha and beta genes. SMART RACE amplified two complete, highly similar but not identical AhR type 2 sequences from salmon cDNA, which from phylogenetic analyses were determined as the rainbow trout AhR2alpha and beta orthologs. The salmon AhR2alpha and beta encode proteins of 1071 and 1058 residues, respectively, and encompass characteristic AhR sequence elements like a basic-helix-loop-helix (bHLH) and two PER-ARNT-SIM (PAS) domains. Both genes are transcribed in liver, spleen and muscle tissues of adult salmon. A second cosmid contained partial sequences, which were identical to the previously characterized AhR2gamma gene. The last two cosmids contained partial genomic AhR sequences, which were more similar to other AhR type 1 fish genes than the four characterized salmon AhR2 genes. However, attempts to amplify the corresponding complete cDNA sequences of the inserts proved very difficult, suggesting that these genes are non-functional or very weakly transcribed in the examined tissues. Phylogenetic analyses of the conserved regions did, however, clearly indicate that these two AhRs belong to the AhR type 1 clade and have been assigned as the Atlantic salmon AhR1alpha and AhR1beta genes. Taken together, these findings demonstrate that multiple AhR genes are present in Atlantic salmon genome, which likely is a consequence of previous genome duplications in the evolutionary past of salmonids. Plausible explanations for the high incidence of AhR genes in fish and more specifically in salmortids, like rapid divergences in specialized functions, are discussed.
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| 6. |
- Madsen, Thomas, et al.
(författare)
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Population size and genetic diversity in sand lizards (Lacerta agilis) and adders (Vipera berus)
- 2000
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Ingår i: Biological Conservation. - 1873-2917. ; 94:2, s. 257-262
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Tidskriftsartikel (refereegranskat)abstract
- Because low genetic diversity may threaten the viability of isolated populations, conservation biologists have devoted much effort to quantify genetic variation. Two techniques routinely used involve levels of mini- and microsatellite polymorphism, with the assumption that levels of variation at these parts of the genome will be reflected in levels of variation at other loci. Our data challenge this assumption. We studied six populations of sand lizards (Lacerta agilis) and five populations of adders (Vipera berus), differing considerably in size and degree of isolation. They, therefore, offer an opportunity to examine how population parameters affect genetic variation at different parts of the genome. Relative population size (based on degree of isolation and number of animals) was not correlated with either minisatellite variability or microsatellite heterozygosity. However, our measures of genetic diversity at the Mhc class I loci of both sand lizards and adders revealed a significant correlation between relative population size and Mhc polymorphism: non-isolated/larger populations exhibited higher genetic diversity than did isolated/small populations. Consequently, only the Mhc-based estimates of genetic diversity yielded results in agreement with population genetic theory. (C) 2000 Elsevier Science Ltd. All rights reserved.
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| 7. |
- Ruby, T, et al.
(författare)
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Characterisation of a cluster of TRIM-B30.2 genes in the chicken MHC B locus
- 2005
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Ingår i: Immunogenetics. - : Springer Science and Business Media LLC. - 1432-1211 .- 0093-7711. ; 57:1-2, s. 116-128
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Tidskriftsartikel (refereegranskat)abstract
- We have identified and characterised a cluster of six TRIM-B30.2 genes flanking the chicken BF/ BL region of the B complex. The TRIM-B30.2 proteins are a subgroup of the TRIM protein family containing the tripartite motif ( TRIM), consisting of a RING domain, a B-box and a coiled coil region, and a B30.2-like domain. In humans, a cluster of seven TRIM- B30.2 genes has been characterised within the MHC on Chromosome 6p21.33. Among the six chicken TRIM- B30.2 genes two are orthologous to those of the human MHC, and two (TRIM41 and TRIM7) are orthologous to human genes located on Chromosome 5. In humans, these last two genes are adjacent to GNB2L1, a guanine nucleotide-binding protein gene, the ortholog of the chicken c12.3 gene situated in the vicinity of the TRIM-B30.2 genes. This suggests that breakpoints specific to mammals have occurred and led to the remodelling of their MHC structure. In terms of structure, like their mammalian counterparts, each chicken gene consists of five coding exons; exon 1 encodes the RING domain and the B-box, exons 2, 3 and 4 form the coiled- coil region, and the last exon represents the B30.2- like domain. Phylogenetic analysis led us to assume that this extended BF/ BL region may be similar to the human extended class I region, because it contains cluster of BG genes sharing an Ig-V like domain with the BTN genes ( Henry et al. 1997a) and six TRIM-B30.2 genes containing the B30.2-like domain, shared with the TRIM-B30.2 members and the BTN genes.
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| 8. |
- Ujvari, Beata, et al.
(författare)
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Low genetic diversity threatens imminent extinction for the Hungarian meadow viper (Vipera ursinii rakosiensis)
- 2002
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Ingår i: Biological Conservation. - 1873-2917. ; 105:1, s. 127-130
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Tidskriftsartikel (refereegranskat)abstract
- Meadow vipers (Vipera ursinii) are small venomous snakes whose range in Hungary has been greatly fragmented by anthropogenic habitat disturbance (especially, agriculture). We obtained DNA from a total of eight Hungarian snakes. Genetic variability at the major histocompatibility (Mhc) class I loci was much lower for these snakes than for specimens from two large Ukrainian populations. Within two Hungarian populations for which we had multiple individuals, band-sharing indices were 100 and 84.6% (versus 63.3 and 57% for the Ukraine populations). The Ukrainian snakes also displayed more RFLP fragments than the Hungarian vipers (mean 13.7 versus 9.0, respectively). In combination with reports of birth deformities, chromosomal abnormalities and low juvenile survival, these data strongly suggest that the Hungarian vipers are experiencing inbreeding depression. Genetic diversity is still present in the Hungarian vipers but among rather than within populations. Given the very low numbers of animals, the only feasible strategy to increase the genetic diversity and to save the Hungarian vipers from extinction is to implement a captive breeding program based on genetically screened animals. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 9. |
- von Schantz, Torbjörn, et al.
(författare)
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Artificial selection for increased comb size and its effects on other sexual characters and viability in gallus-domesticus (the domestic chicken)
- 1995
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Ingår i: Heredity. - : Springer Science and Business Media LLC. - 1365-2540 .- 0018-067X. ; 75:5, s. 518-529
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Tidskriftsartikel (refereegranskat)abstract
- The expression of secondary ornaments is often positively correlated with the bearer's condition. So far no study has reported on consequences of directional selection on male sexual ornaments in birds, i.e. it is unknown to what extent male sexual traits are genetically correlated and whether selection for secondary ornaments affects viability. In this study we estimate phenotypic and genotypic parameters of three male sexual traits, namely comb size, spur length and testes mass, by using two different lines of domestic chickens (Gallus domesticus). One of the two lines had been artificially selected for large comb size during nine generations whereas the other line was a randomly mated control line. As a result of the selection, male comb size was almost doubled. Data from the selection line indicate that comb size was negatively genetically correlated with testes mass and spur length. The cockerels from the selection line had accordingly lighter testes and shorter spurs than cockerels from the control line. A simple mate choice experiment with females and males from both lines indicated that preferred males had a larger joint expression of comb size and spur length than nonpreferred males. Data from three different selection lines, all with enlarged comb size, clearly reveal a negative effect of comb size on male viability.
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| 10. |
- von Schantz, Torbjörn, et al.
(författare)
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Female choice - Reply
- 1989
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 339:6224, s. 432-433
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Tidskriftsartikel (refereegranskat)
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