Analysis of the growth hormone (GH) gene in 12 strains of White Leghorn chickens revealed restriction fragment length polymorphisms (RFLPs) at three MspI sites and at a SacI site. Based on linkage disequilibrium analysis, they gave rise to eight different alleles (i.e. combinations of RFLPs), with five occurring at frequencies above 5% in at least one strain. Pairs of GH-RFLPs were at near maximal linkage disequilibrium, suggesting either a lack of recombination or the presence of selection pressure during evolution of the GH gene. Allele frequencies were determined in 12 non-inbred strains derived from three different genetic bases. These strains had been selected either for an array of egg production traits, resistance to Marek's disease or resistance to avian leukosis. Selection for disease resistance was consistently correlated with an increase in the frequency of one of the alleles. One strain segregated for only two alleles, which differed by three RFLPs. Analysis of variance in this strain indicated that the GH allele co-selected with resistance was associated with a delayed onset of ovulation but a higher persistency of ovulation as age progressed, resulting in an overall increase of egg production by 15% (age at first egg to 497 days). The resistance-associated GH allele was dominant for the onset of ovulation and recessive for the persistency of egg production. There was no significant effect of the GH genotype on juvenile body weight, egg weight or egg specific gravity.
Two highly polymorphic microsatellite DNA loci were used to determine paternity of larvae of primiparous Chionoecetes opilio females. In addition, female spermathecal contents were genotyped at the two loci and histological analysis of the organs was carried out to elucidate patterns of sperm competition. Females carrying their first brood from controlled laboratory matings and from matings in the wild were examined. Spermathecal contents from wild-caught females were cut into several cross sections and each section genotyped individually. Both wild and laboratory females commonly mated with several males whose ejaculates were stored and stratified in the spermathecae. Genetic typing of the offspring of laboratory-mated females revealed single paternity and indicated that the last mate to inseminate a female before oviposition gained paternity of the clutch. The predominant mechanism ensuring single paternity appeared to be sperm stratification. In wild-caught females, the microsatellite typing of the offspring also revealed single paternity, but larvae appeared to be sired by males whose genotypes were found in the spermathecal cross sections towards the dorsal end (blind end) of the spermathecae. This suggested that they were the first males to mate with females that they guarded until oviposition, and females remated with other males thereafter.Résumé : Deux loci d'ADN microsatellite hautement variables ont été utilisés pour déterminer la paternité des larves de femelles primipares de Chionoecetes opilio. De plus, la détermination des génotypes du contenu des spermathèques des femelles a été faite à partir de ces deux loci et l'analyse de coupes histologiques des organes a été réalisée dans le but d'élucider les modalités de compétition du sperme. Des femelles avec leur premières portées d'oeufs obtenues à partir d'accouplements contrôlés en laboratoire et d'accouplements en nature ont été examinées. Les spermathèques des femelles sauvages ont été coupées en plusieurs sections transversales et le génotype de chacune des sections a été déterminé. Les femelles sauvages ainsi que celles de laboratoire se sont accouplées avec plusieurs mâles dont le sperme était accumulé de façon stratifiée dans les spermathèques. La détermination du génotype de la progéniture des femelles accouplées en laboratoire a révélé qu'il y avait paternité unique et que le dernier mâle à inséminer une femelle avant la ponte des oeufs était le père. Le mécanisme prédominant assurant la paternité unique semble être la stratification des éjaculats. Chez les femelles sauvages, la détermination du génotype des larves a également démontré qu'il y avait paternité unique. Cependant, les oeufs semblaient avoir été fécondés par les mâles dont les génotypes se trouvaient dans les sections des spermathèques les plus éloignées de l'ouverture des organes. Ceci suggère qu'ils étaient les premiers à s'accoupler avec les femelles et qu'ils les auraient ensuite protégées jusqu'à ce qu'elles pondent. Les femelles se seraient donc ré-accouplées avec d'autres ...
Endonuclease activity upon depurinated DNA was measured in extracts of cultured fibrobrasis from xeroderma pigmentosum patients. Cell lines from complementation groups A, B, C, E, and the XP-variant -had slightly reduced levels of activity, but cell lines from complementation group D had one-sixth of the normal activity. An Cell lines developed from skin biopsies of these individuals have been reported to be defective in excision repair of DNA damage introduced by ultraviolet light or by various chemical agents (2,3). This defect is inferred from a reduction in the overall rate of DNA repair synthesis, and it remains unclear at which step the repair pathway is affected. A few XP-cell lines have been tested for defects in early steps of excision repair: two were shown to be unable to excise pyrimidine dimers from DNA (4), and another one was reported to be defective in the first step of repair, the endonucleolytic cleavage presumably near UV lesions of the DNA (5). Somatic cell hybridization studies have recently shown that mutations which lead to the XP phenotype fall into five or six complementation groups (6, 7). This number exceeds the number of steps postulated for excision repair, suggesting that the repair pathway is regulated in a very complex manner or that there exist multiple, or branched pathways of repair.Several enzyme activities believed to be involved in excision repair have been measured in extracts of XP-cell lines. Pedrini et al. (8) found no significant differences in the levels of polynucleotide ligase activity, DNA polymerase, single-strand exonuclease and double-strand endonuclease. Bacchetti et al. (9) compared endonucleolytic activity specific for UV-irradiated DNA in normal and two XP-cell lines and detected no difference. Under their assay conditions the major UV-specific endonuclease activity in fibroblast extracts did not cleave the DNA near pyrimidine dimers, but at other undetermined lesions. In an attempt to Abbreviation: XP, xeroderma pigmentosum. identify excision repair endonucleases we have also found that extracts from a normal cell line and from the XP-cell lines CRL 1157 and CRL 1160 (see Materials and Methods) contained equal levels of an endonuclease activity which preferentially cleaves UV-irradiated DNA at sites which are about 100 times less frequent than the number of pyrimidine dimers in the DNA. However, these studies led us also to compare endonuclease activity with depurinated DNA as a substrate in extracts from normal and XP fibroblasts. Such an activity has been previously reported in many microorganisms, plants and mammals (10-13). MATERIALS AND METHODSGrowth of Cells and Preparation of Extracts. Fibroblast cell lines from skin biopsies were obtained from the American Type Culture collection (ATCC). Strain numbers, complementation groups and relevant properties are summarized irk Table 1. Cells were grown at 370 in 32 ounce prescription bottles with 50 ml of Dulbecco's modified Eagle's medium (Gibco), supplemented with 15 mM N-2-hydroxyethylpiperazine...
DNA fingerprinting, a technique based on the detection of hypervariable minisatellite regions in DNA restriction fragments, was tested for its applicability to conduct population genetics in poultry. Using MspI digestion and phage M13 DNA as a probe, between 25 and 35 minisatellite-containing DNA fragments were observed per bird. Comparison of the banding pattern of offspring with their parents revealed that the bands were inherited as stable genetic traits. The variability of the DNA fingerprinting pattern was reduced in inbred strains. DNA fingerprints of chickens from five well-defined populations of known genetic relationships were analyzed and indices of genetic distances were computed. They correctly reflected the history of these strains, indicating that DNA fingerprinting may be a powerful tool to characterize genetic relationships between different breeding populations of the same species.
A random sample of 17 threespine stickleback nests was analysed using DNA fingerprinting. DNA from the guardian male and a random subsample of 10 fry per nest was probed with pYNZ132, a human single-locus VNTR probe which detects a multilocus fingerprint pattern in sticklebacks. Band-sharing indices (BSZs, the proportion of bands shared by two individuals) between the guardian male and its fry were calculated. In 147 of a total of 170 pair-wise comparisons the BSZs varied between 0.40 and 0.77. The guardian male was thought to be the true father of all these fry (Pc0.10). For the remaining 23 fry the BSZs vaned between 0.09 and 0.34, suggesting that these fry were fathered by a different male (P<0.06). Once the paternal bands in each legitimate fry were determined, the remaining (i.e. maternal) bands among these fry were compared.Based on the BSIs obtained, the minimum number of females that spawned per nest was determined, and the maternal DNA fingerprints of the legitimate fry were traced back.In one nest five eggs of the sample had been fertilized by a sneaker, in two nests the guardian male had stolen eggs from a rival male, and in another nest one of the eggs was fertilized by a sneaker and three were stolen eggs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.