Domestication Genes Research Articles

Genetic diversity and introgression in the Scottish wildcat.

This paper describes a genetic analysis of wild-living cats in Scotland. Samples from 230 wild-living Scottish cats (including 13 museum skins) and 74 house cats from England and Scotland were surveyed for nine microsatellite loci. Pelage characteristics of the wild-living cats were recorded, and the cats were then grouped into five separate categories depending on the degree to which they conformed to the characteristics attributed to Felis silvestris Schreber, 1775. Allele frequency differences between the morphological groups are greater than those among the three house cat samples. Analysis of genetic distances suggests that more of the differences between individuals can be explained by pelage than geographical proximity, and that pelage and geographical location are not confounded. Ordination of the genetic distances suggests two main groups of wild-living cats, with intermediates, and one group is genetically very similar to the house cats, while the other group contains all cats taxonomically identified as wildcat based on morphology. A genetic mixture analysis gives similar results to the ordination, but also suggests that the genotypes of a substantial number of cats in the wildcat group are drawn from a gene pool with genotypes in approximately equilibrium proportions. We argue that this is evidence that these cats do not have very recent domestic ancestry. However, from the morphological data it is highly likely that this gene pool also contains a contribution from earlier introgression of domestic cat genes.

Doxorubicin-Induced Alterations of c- myc and c- jun Gene Expression in Rat Glioblastoma Cells: Role of c- jun in Drug Resistance and Cell Death

We studied the effect of doxorubicin on the expression of c- myc and c- jun in the rat glioblastoma cell line C6 and its doxorubicin-resistant variant C6 0.5, at equitoxic exposures. For quantitation, the mRNA levels of these oncogenes were related to those of two domestic genes, β-actin and glyceraldehyde phosphate dehydrogenase. After a transient overexpression of the genes during the first hour of incubation, there was a selective, dose-dependent down-regulation of both genes by doxorubicin in the sensitive cells. In the resistant cell line, c- myc expression was also decreased in response to doxorubicin incubation, but the expression of c- jun remained unchanged over the whole range of concentrations. In contrast, vincristine had no effect on the amounts of c- myc and c- jun mRNAs in either line. The effect of doxorubicin on the mRNA levels of c- jun was also observed on the JUN proteins by immunoblotting, but the MYC protein levels remained unchanged upon doxorubicin treatment. There was a significant correlation between the levels of c- myc and c- jun gene expression and the degree of growth inhibition induced by doxorubicin. In addition, doxorubicin induced a fragmentation of DNA in sensitive cells, but not in resistant cells, thus revealing a resistance to apoptosis in this line. Doxorubicin-induced cell death did not appear to be mediated by p53 in either cell line.

Differences between nuclear and mitochondrial introgressions of brown trout populations from a restocked main river and its unrestocked tributary

The introgression of domestic genes in wild trout populations as a result of intensive restocking has been observed to be low in numerous rivers of the Mediterranean watershed. With the aim of examining the process of introgression and improving our understanding the reasons for its possible limitations, we analysed the percentage of domestic genes for three protein-coding loci and for mitochondrial haplotypes. Two samples were analysed: a restocked river and a tributary which is no longer stocked. In order to follow the introgression over time, trout were separated into two age groups. The mitochondrial locus showed the same tendencies as those obtained with the nuclear loci, but with generally higher introgression values. A differential introgression among protein-coding loci was also observed. From these results, we discuss the possibility of selective factors acting against the domestic genes in river. The hypothesis of a difference in reproductive success between domestic males and females is also presented to explain the higher introgression of mtDNA.

Differences between nuclear and mitochondrial introgressions of brown trout populations from a restocked main river and its unrestocked tributary

The introgression of domestic genes in wild trout populations as a result of intensive restocking has been observed to be low in numerous rivers of the Mediterranean watershed. With the aim of examining the process of introgression and improving our understanding the reasons for its possible limitations, we analysed the percentage of domestic genes for three protein-coding loci and for mitochondrial haplotypes. Two samples were analysed: a restocked river and a tributary which is no longer stocked. In order to follow the introgression over time, trout were separated into two age groups. The mitochondrial locus showed the same tendencies as those obtained with the nuclear loci, but with generally higher introgression values. A differential introgression among protein-coding loci was also observed. From these results, we discuss the possibility of selective factors acting against the domestic genes in river. The hypothesis of a difference in reproductive success between domestic males and females is also presented to explain the higher introgression of mtDNA.

Nature and origin of polymorphism in feline MHC class II DRA and DRB genes.

Transcripts of the MHC class II DRA and DRB gene homologues of the domestic cat (Felis catus) were cloned and sequenced to compare the pattern and process of DR gene divergence. Homologous DRB exon 2 sequences from 36 feral domestic cats throughout the world plus from three species of Felidae (tiger cat, Iriomote cat, and Geoffroy's cat) were also determined. Limited variation in the domestic cat Feca-DRA gene was observed, but abundant variation in the Feca-DRB gene was seen comprising 61 distinct DRB alleles. Phylogenetic analyses resolved at least five monophyletic feline DRB allelic lineages (DRB*1 to *5), which are clearly distinct from those of human (HLA-DRB1 to 9 lineages), mouse (H-2Ebeta b, u, f), and dog DRB alleles. Approximately 80% of individual cats contained three to six distinct DRB sequences, indicating that feline MHC maintains two to three DRB loci. Five cats had three DRB sequences in a single allelic lineage, indicating the occurrence of recent gene duplication of feline DRB genes. DRB sequences isolated from three exotic cats demonstrated close association with a particular domestic cat DRB lineage, suggesting that these allelic lineages are derived from common ancestral alleles that existed prior to the divergence of these feline species about 10 to 15 million years ago. Patterns of synonymous and nonsynonymous nucleotide substitution rates that occurred in Ag recognition sites (ARS) and nonrecognition (NAR) sites demonstrated a strong role of natural selection--positive selection for Ag recognition sites and negative selection for nonrecognition sites of feline DRB sequences--in the process of evolution of DR molecules.

The cytological and genetical mechanisms of plant domestication exemplified by four crop models

Plant domestication includes a number of evolutionary mechanisms, such as mutation, hybridization, polyploidization, selection, and genetic drift. These evolutionary mechanisms will be used as entities in a graphical model system to be used as a formal descriptive method to describe the process of plant domestication. The most important crops can be arranged in four different crop domestication models: the bread wheat model, the cotton model, the soybean model, and the chili pepper model. Mixed-model situations occur. The existence of reproductive isolation connects the crop models with the gene pool concept. Cluster and analysis of taxa based on a numerical representation of crossability data allows a precise characterization of the different gene pools. The combined approach of crop domestication models, dendrograms, and gene pool representation creates a clear description of the mechanisms leading to a particular set of reproductive barriers and the extent of these barriers. The four models described here are general outlines. The included entities can be fine tuned to specific crop situations. This will be worked out forAllium cepa (onion) andLesquerella densipila (an oil seed crop). These crop domestication models can also be used in developing breeding strategies by illustrating the rationale of desired approaches such as hybridization improvement techniques or transformation.

A nuclear factor (NF2d9) that binds to the male-specific P450 (Cyp 2d-9) gene in mouse liver.

Expression of the Cyp 2d-9 (steroid 16 alpha-hydroxylase) gene in mouse liver is male specific in such Mus musculus domesticus strains as FVB/N, whereas the corresponding P450 genes in the wild mouse species Mus spretus are not sex specific in their expression. These parental differences in the gene expressions were independently inherited in F1 offspring from crosses of FVB/N and M. spretus. A 5' flanking sequence (-110CTC CTCCCTATTCCGGGCC-92) was defined as a regulatory element (named SDI-A1) for the domestic Cyp 2d-9 promoter. The nucleotide which corresponds to T at position -99 within SDI-A1 was found to be substituted with C in the wild mouse P450 genes. The placing of C at position -99 abolished the transcriptional activity of SDI-A1 in HepG2 cells as well as the binding of SDI-A1 to a nuclear factor. This factor (designated NF2d9) was purified from mouse nuclear extracts, and its cDNA cloned. The purified NF2d9 bound to SDI-A1 but not to the mutated SDI-A1 with C at position -99. The deduced amino acid sequence revealed that NF2d9 is 72 and 94% identical to mouse CP2 and human LBP-1a, respectively. NF2d9 thus belongs to the CP2 family and is the mouse homolog of human LBP-1a, which modulates human immunodeficiency virus type 1 transcription. Anti-NF2d9, which was raised against the bacterially expressed protein, supershifted the SDI-A1 complex with the liver nuclear extract. Both the bacterially expressed and in vitro-translated NF2d9 inhibited SDI-A1 complex formation, although they did not bind to SDI-A1 directly. The results, therefore, indicate that the domestic Cyp 2d-9 gene can be regulated through a specific association of NF2d9 with SDI-A1.

Standard karyotype of the river buffalo (Bubalus bubalis L., 2n = 50). Report of the committee for the standardization of banded karyotypes of the river buffalo.

During the 10th European Colloquium on Cytogenetics of Domestic Animals held in Utrech, The Netherlands, in 1992, an international committee on river buffalo chromosomes was established. At the recent 8th North American Colloquium on Domestic Animal Cytogenetics and Gene Mapping in Guelph, Canada (1993), Q-, G- and R-banded river buffalo karyotypes were presented and discussed. This material was used to establish the first standard karyotype of the river buffalo.

Wild pearl millet population (Pennisetum glaucum, Poaceae) integrity in agricultural Sahelian areas. An example from Keita (Niger)

Morphometric and isozymic analyses of adjacent cultivated and spontaneous populations of pearl millet in Niger revealed in the field a unique continuous distribution of phenotypes ranging from the most cultivated one to a typical cultivated × wild hybrid. The natural population was subdivided into a major wild group and a hybrid wild × cultivated group. Cultivated millet displayed an equilibrium state between recombined domesticated and wild genes. The natural population, in spite of a high rate of immigration by pollen from cultivated plants, retained its structure by apparently reproducing itself exclusively from the major wild group.

Characterization of MHC cDNA clones in the domestic cat. Diversity and evolution of class I genes.

The abundant functional polymorphism and evolutionary divergence of mammalian MHC class I genes has been affirmed recently by sequence analysis of more than 40 mouse H-2 and human HLA transcripts. In a comparative approach to the evolution of the MHC, we isolated eight molecular clones of feline MHC (termed FLA for feline leukocyte antigen) class I genes from a cDNA library of a cat T cell lymphoma line. DNA sequence analysis of eight clones revealed that they all fell into one of two internally identical allelic groups which differed by 9% of their nucleotide sequences. The occurrence of only two allelic cDNA clones is consistent with the expression of a single heterozygous functional class I gene in the studied cell line despite the occurrence of more than 20 class I copies estimated to be present in the cat genome. Comparison of the FLA class I coding sequence with other class I genes from other species revealed that the domestic cat genes display 81 to 82% sequence identity with human, and 73 to 79% sequence identity with mouse class I genes. Feline and human class I genes have similar sequences and protein structures, with three (alpha) extracellular domains, one transmembrane domain, and one cytoplasmic domain. Variable codons detected in FLA class I alleles were, in most cases, in positions which were also variable in humans and mice, whereas invariant positions with defined functional constraints were generally conserved and invariant between the three species as well. Southern analysis of DNA from diverse species of Felidae revealed a similar numerosity and restriction pattern indicating conservation of the organization of class I genes during the Felidae radiation.

Further studies with interspecific hybridization among mediterranean/African lupin species

Interspecific hybridization has a role to play in the domestication of wild species through the introgression of desirable genes from related domesticated species. Almost complete genetic isolation among the Mediterranean-African rough-seeded lupin species has hitherto ruled out introgression within that group. Recent work in Western Australia with L. atlanticus, L. cosentinii, L. pilosus and L. digitatus has nevertheless suggested that hybrid sterility may be overcome if specially selected lines of each are used in crossing. We have now selected F2-F5 plants and backcrosses (Bc1; Bc2) from L. atlanticus/L. cosentinii, some with improvement in seed fertility combined with domestication genes from either species. Relatively better F1-F2 plant fertility in subsequent crosses of L. atlanticus/L. digitatus than in L. atlanticus/L. cosentinii or L. digitatus/L. cosentinii indicate closer relationship between L. atlanticus and L. digitatus than in the other cross combinations. Use of embryo culture may help to overcome L. pilosus/L. atlanticus F1 plant sterility. Some of the interspecific selections could act as genetic bridges between L. cosentinii and L. pilosus.

Variability in the total and component galactosyl sucrose oligosaccharides of Lupinus species

The oligosaccharide compositions of 33 lupin seed accessions and cultivars, from 10 species, are reported. Seed weights varied from 3.8 to 66.6 g/100 seeds. Total oligosaccharide content ranged from just under lo%, to almost 23% dry matter. In all cases the quantity of oligosaccharides (raffinose, stachyose and verbascose) was higher than that of disacharides (sucrose and melibiose). Verbascose ranged from 0.0 to 33.4% of total oligosaccharide content, and raffinose from 4.7 to 47.4%. Stachyose was the predominant and most constant sugar in majority of the seeds examined, the highest level (75%) being recorded in one line of L. hispanicus. The amounts of stachyose and verbascose, which are considered to be of major importance as 'flatus factors', were higher than those recorded for most established legume crops, although considerable variation was found between lupin species and some within a lupin species. Sufficient variability appears to be present within L. angustifolius in total oligosaccharides, and to a smaller extent in component saccharides [other than that apparently associated with existing domestication gene(s)] to warrant selection for improved saccharide composition as part of the breeding process.

Genetic Variability and Agronomic Performance of Soybean Populations Developed from Plant Introductions1

Plant introductions (Pl's) of soybean [Glycine max (L.) Merr.] may enhance genetic improvement for yield beyond the level possible with the domestic gene pool of cultivars and experimental lines. The genetic variability and agronomic performance of soybean populations with five different percentages of PI germplasm were evaluated. Forty PI's and 40 domestic cultivars and experimental lines were intermated systematically during four generations to form the populations AP10 (100% PI), APII (75% PI), API2 (50% PI), AP13 (25% PI), and (0% PI). In 1980, 200 random lines from each population with a restricted range in maturity were evaluated for seed yield and time of maturity at two locations in Iowa. In 1981, 60 of the highest‐yielding lines from each population were evaluated for seed yield, time of maturity, plant height, and lodging at three Iowa locations. The genetic variability for seed yield among the 200 random lines was similar for API0 to API3 and about twice as large as the genetic variability for AP14. The mean yields of the random lines of 1980 and the selected lines of 1981 were greatest for AP14 and least for AP10. In the regression of mean yield of the populations in 1980 on percentage of PI germplasm in the populations, 73% of the variation was explained by the linear component. There was a similar decrease from API4 to API0 in the mean yields of the top 10 and 20 lines of each population that could be used as parents to form cycle 1 populations for recurrent selection. Lodging susceptibility of the populations decreased progressively from AP10 to AP14. The maximum difference in plant height among populations was only 8 cm. The use of PI germplasm for short‐term improvement of yield is not likely to be as productive as selection in populations developed from domestic cultivars or experimental lines. Longterm recurrent selection studies will be required to determine the ultimate value of PI germplasm for yield improvement of soybean.

Methods of conserving gametes and embryos of farm mammals

There are several methods of preserving domestic animal genes. In the present paper methods using frozen germ plasm are considered. Except in the mare, birth rates of more than 50% are obtained from deep-freezing spermatozoa. The freezing of oocytes has not been used yet in all domestic animals, but the techniques of freezing cattle, sheep, goat, rabbit and recently horse embryos are being developed. It is not yet possible to use these techniques in the pig. The success of gene preservation programmes depends not only on the technique used, but also on the efforts made by breeders and official organizations.