Genetics Commons^™

Microevolutionary Patterns And Molecular Markers: The Genetics Of Geographic Variation In Ascaris Suum, Steven A. Nadler

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Molecular markers have been used only rarely to characterize the population genetic structure of nematodes. Published studies have suggested that different taxa may show distinct genetic architectures. Isoenzyme and RAPD markers have been used to investigate geographic variation of Ascaris suum at the level of infrapopulations (nematodes within individual hosts), within localities, and among geographic regions. Independent estimates of genetic differentiation among population samples based on isoenzyme and RAPD data showed similar patterns and substantial correlation. Heterozygote deficiencies within infrapopulations and large values for inbreeding coefficients among infrapopulations suggested that the composition of these populations was not consistent with a …

A Thyroid Hormone-Regulated Gene In Xenopus Laevis Encodes A Type Iii Iodothyronine 5-Deiodinase., Donald L. St Germain, Robert Schwartzman, Walburga Croteau, Akira Kanamori, Zhou Wang, Donald D. Brown, Valerie Galton

Dartmouth Scholarship

The type III iodothyronine 5-deiodinase metabolizes thyroxine and 3,5,3'-triiodothyronine to inactive metabolites by catalyzing the removal of iodine from the inner ring. The enzyme is expressed in a tissue-specific pattern during particular stages of development in amphibia, birds, and mammals. Recently, a PCR-based subtractive hybridization technique has been used to isolate cDNAs prepared from Xenopus laevis tadpole tail mRNA that represent genes upregulated by thyroid hormone during metamorphosis. Sequence analysis of one of these cDNAs (XL-15) revealed regions of homology to the mRNA encoding the rat type I (outer ring) 5'-deiodinase, including a conserved UGA codon that encodes selenocysteine in …

Estimation Of The Incidence Of A Rare Genetic Disease Through A Two-Tier Mutation Survey, R Chakraborty, M R Srinivasan, S Raskin

Faculty, Staff and Student Publications

Recent attempts to detect mutations involving single base changes or small deletions that are specific to genetic diseases provide an opportunity to develop a two-tier mutation-screening program through which incidence of rare genetic disorders and gene carriers may be precisely estimated. A two-tier survey consists of mutation screening in a sample of patients with specific genetic disorders and in a second sample of newborns from the same population in which mutation frequency is evaluated. We provide the statistical basis for evaluating the incidence of affected and gene carriers in such two-tier mutation-screening surveys, from which the precision of the estimates …

Genetics And Applications Of Nisin Production In Lactococcus Lactis Subsp. Lactis And Conjugal Exchange Of This Trait, Jeffery R. Broadbent

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Chapter I reviews current literature on gene transfer systems in lactic acid bacteria, how genetically altered microorganisms for food are presently regulated, and how nisin is used as a food preservative.

Chapter II investigates previous reports which linked genes for nisin biosynthesis and sucrose utilization (Nip⁺Suc⁺) to plasmid DNA in two well characterized L. lactis subsp. lactis strains. Plasmid curing studies, conjugations, and DNA-DNA hybridizations indicated that these genes were encoded by chromosomal loci in all Nip⁺Suc⁺ strains examined. Similar results were noted in nisin-sucrose transconjugants of L. lactis subsp. cremoris and S. …

Statistical Interpretation Of Dna Typing Data, R Chakraborty

Faculty, Staff and Student Publications

No abstract provided.

A Temperature-Sensitive Mutant Of Escherichia Coli Affected In The Alpha Subunit Of Rna Polymerase, Majid Mehrpouyan

Electronic Theses and Dissertations

A temperature-sensitive mutant of Escherichia coli affected in the alpha subunit of RNA polymerase has been investigated. Gene mapping and complementation experiments placed the mutation to temperature-sensitivity within the alpha operon at 72 min on the bacterial chromosome. The rate of RNA synthesis in vivo and the accumulation of ribosomal RNA were significantly reduced in the mutant at 44$\sp\circ$C. The thermostability at 44$\sp\circ$C of the purified holoenzyme from mutant cells was about 20% of that of the normal enzyme. Assays with T7 DNA as a template showed that the fraction of active enzyme competent for transcription was reduced as a …

Variants And Polymorphisms Of Three Repetitive Dna Families In The Human Genome, Robert M. Roudabush

Electronic Theses and Dissertations

A novel 0.6 kb LINE family in human DNA, designated L2Hs, has been described (Musich and Dykes 1986). Studies employing clone N6.4, containing three 0.6 kb segments of this family, indicate that these sequences are interspersed and moderately repetitive. Two additional variant sequences of the L2Hs family, N6.1 and N6.3, have been identified. Restriction mapping of each cloned segment indicates similarities among N6.4, N6.3 and N6.1. When the cloned DNAs were cleaved with restriction enzymes and subjected to cross-hybridization, each cloned insert produced a pattern indicating that the sequences contained in N6.1 and N6.3 are represented in at least one …

Population Amalgamation And Genetic Variation: Observations On Artificially Agglomerated Tribal Populations Of Central And South America, R Chakraborty, P E Smouse, J V Neel

Faculty, Staff and Student Publications

The interpretation of data on genetic variation with regard to the relative roles of different evolutionary factors that produce and maintain genetic variation depends critically on our assumptions concerning effective population size and the level of migration between neighboring populations. In humans, recent population growth and movements of specific ethnic groups across wide geographic areas mean that any theory based on assumptions of constant population size and absence of substructure is generally untenable. We examine the effects of population subdivision on the pattern of protein genetic variation in a total sample drawn from an artificial agglomerate of 12 tribal populations …

Parentage Analysis With Genetic Markers In Natural Populations I The Expected Proportion Of Offspring With Unambiguous Paternity, R Chakraborty, T R Meagher, P E Smouse

Faculty, Staff and Student Publications

Recent studies indicate that polymorphic genetic markers are potentially helpful in resolving genealogical relationships among individuals in a natural population. Genetic data provide opportunities for paternity exclusion when genotypic incompatibilities are observed among individuals, and the present investigation examines the resolving power of genetic markers in unambiguous positive determination of paternity. Under the assumption that the mother for each offspring in a population is unambiguously known, an analytical expression for the fraction of males excluded from paternity is derived for the case where males and females may be derived from two different gene pools. This theoretical formulation can also be …

Variant Forms Of Ataxia Telangiectasia, A. M. R. Taylor, E. Flude, B. Laher, Michael W. Stacey, E. Mckay, J. Watt, S. H. Greens, A. E. Harding

Bioelectrics Publications

Two ataxia telangiectasia patients with unusual clinical and cellular features are described. Cultured fibroblasts and PHA stimulated lymphocytes from these two patients showed a smaller increase of radiosensitivity than cells from other A-T patients, as measured by colony forming ability or induced chromosome damage respectively, after exposure to ionising radiation. The response of DNA synthesis to irradiation of these cells was, however, the same as for other A-T patients. Cells from a third patient with some clinical features of A-T but with a very protracted course also showed low levels of radiation induced chromosome damage, but colony forming ability and …

Detection Of Nonrandom Association Of Alleles From The Distribution Of The Number Of Heterozygous Loci In A Sample, R Chakraborty

Faculty, Staff and Student Publications

The distribution of the number of heterozygous loci in two randomly chosen gametes or in a random diploid zygote provides information regarding the nonrandom association of alleles among different genetic loci. Two alternative statistics may be employed for detection of nonrandom association of genes of different loci when observations are made on these distributions: observed variance of the number of heterozygous loci (s2k) and a goodness-of-fit criterion (X2) to contrast the observed distribution with that expected under the hypothesis of random association of genes. It is shown, by simulation, that s2k is statistically more efficient than X2 to detect a …

Cole1 Copy Number Mutants., Londa Schmidt, Joseph Inselburg

Dartmouth Scholarship

A deletion mutant of the colicin E1-derived plasmid, pDMS6642, exhibited an approximately fourfold increase in copy number. We subsequently isolated hydroxylamine-induced mutants of that plasmid that had a further increase in copy number. Analysis of them suggests that the increased copy number of pDMS6642 is associated with transcriptional readthrough from a Tn3 transposon into the region of ColE1 containing information that influences plasmid replication. The hydroxylamine mutation in one copy number mutant appeared to increase the plasmid copy number by stimulating readthrough transcription from the Tn3 transposon into the ColE1 replication control region, whereas the other hydroxylamine mutation acts by …

"Biological Determinism As A Social Weapon", Richard C. Lewontin

Special Collections: Oregon Public Speakers

No abstract provided.

How Teachers Of High School Biology May Introduce Heredity And Birds Through The Use Of Doves, Donald Hood Dickinson

Graduate Student Research Papers

It was the purpose of this study (1) to present a method of teaching principles of heredity at a level understandable to students of a high school biology class, (2) to present a list of resource materials for use in a heredity unit, and (3) to show how the use of live animals might intensify student interest in this subject as well as in other phases of bird life such as nest building, incubation of eggs, hatching of eggs, voice and communication, and effects of nutrition on chick development.