Biomedical subjects

J N Derr

Publications and source records attributed to J N Derr.

25 records · Page 2Linked to original sources

PubMed1992

Variation and the phylogenetic utility of the large ribosomal subunit of mitochondrial DNA from the insect order Hymenoptera.

Nucleotide sequence variation from a 573-bp region of the mitochondrial 16S rRNA gene was determined for representative hymenopteran taxa. An overall bias in the distribution of A and T bases was observed from all taxa; however, the terebrants (parasitoids) displayed significantly lower AT ratios as well as a higher degree of strand asymmetry. Moreover, a strong positive correlation was observed between relative AT richness and sequence divergence, suggesting selection at the nucleotide level for A and T bases as well as functionality. Overall sequence difference ranged from 2.3 to 53.4%, with the maximum divergence between members of the two Hymenopteran suborders. These data were used in a phylogenetic analysis to illustrate the utility and degree of resolution provided by this information at various hierarchical levels within this taxonomically diverse order. Parsimony analysis revealed strong evidence for monophyly of the aculeates and the terebrants. Most noteworthy was a strongly supported clade containing the two terebrant superfamilies Icheumonoidea and Chalcidoidea. Conversely, high sequence divergence values resulted in instability at the base of the tree and limited resolution at the higher taxonomic levels. Nevertheless, these results do identify those taxonomic levels for which 16S rRNA sequences are phylogenetically informative.

Animals↗

PubMed1992

Intra- and interspecific genome-size variation in the Salmonidae.

The nuclear DNA contents of 22 salmonid taxa, estimated primarily by flow-cytometric analysis relative to a chicken internal standard, were evaluated to compare intra- and interspecific variation in DNA content within this fish family. The average variability within taxa exceeded that among taxa. Intraspecific genome-size variation was substantial and, in some cases, exceeded the mean genome size for the species. The flow-cytometric method used here allows for rapid and reliable comparison of nuclear DNA contents within and among individuals from natural animal populations.

Animals↗

PubMed1991

Fertility in an F1 male hybrid of white-tailed deer (Odocoileus virginianus) x mule deer (O. hemionus).

The fecundity of an F1 male hybrid deer, from a cross between a male Odocoileus virginianus (white-tailed deer) and a female O. hemionus (mule deer), was assessed by cytogenetic and flow cytometric techniques. Analysis of chromosome morphology, nucleolus organizer expression, meiotic chromosome pairing, sperm production, and nuclear gene inheritance revealed no genetic anomalies that could potentially impair normal fertility. These observations are discussed in relation to recent reports of hybridization between natural populations of these two species.

Albumins↗

PubMed1986

Mitochondrial DNA analysis of hybridization between sympatric white-tailed deer and mule deer in west Texas.

Sympatric populations of white-tailed deer and mule deer (Odocoileus virginianus and Odocoileus hemionus, respectively) on a west Texas ranch share a common mitochondrial DNA restriction map genotype. Phylogenetic analysis indicates that this genotype is more characteristic of O. virginianus than of O. hemionus. The genotype of west Texas deer differs from that of O. virginianus from South Carolina by five mutational events (1.3% sequence divergence), whereas it differs from that of O. hemionus from California by 17 events (5.5% divergence). We suggest that interspecies hybridization has occurred, primarily between mule deer bucks and white-tailed deer does, with preferential absorption of hybrid offspring into the mule deer gene pool. Introgressive hybridization may be involved in ongoing displacement of mule deer by white-tailed deer in west Texas.

Animals↗

PubMedDate not supplied

Microsatellite diversity in captive bottlenose dolphins (Tursiops truncatus).

The utility of microsatellites for managing captive Tursiops truncatus was investigated. Specifically the level of genetic diversity among the loci examined and their usefulness for resolving paternity was assessed. Overall a relatively low level of genetic variation was found among captive dolphins. In addition, a high percentage of common alleles was found among dolphins belonging to different morphotypes (inshore versus offshore). The implications of these findings are discussed and suggestions are given for the use of genetic markers in captive propagation programs for T. truncatus.

Animals↗

PubMedDate not supplied

Chromosome conservation among the advanced pecorans and determination of the primitive bovid karyotype.

Extensive monobrachial QFH-band homologies were found among cattle (Bovidae), pronghorn (Antilocapridae), Masai giraffe (Giraffidae), and mule and whitetail deer (Cervidae). The deer species had identical karyotypes (2n = 70, NAA = 70). Interfamily comparisons demonstrated that cattle (2n = 60, NAA = 58) and pronghorn (2n = 58, NAA = 60) were karyotypically the most similar. The giraffe possessed a 2n = 30, NAA = 54, and differed from the other artiodactyls by having a preponderance of biarmed autosomes. The primarily acrocentric deer karyotypes showed several chromosome arm disruptions relative to the other species. Comparative cytogenetic data among the advanced pecorans strongly suggest that the 2n = 60, NAA = 58 karyotype found in several species of the tribe Bovini is probably near the primitive condition for the Bovidae. However, the ancestral conditions of the sex chromosomes within the Bovidae and among the advanced pecorans remain in question.

Animals↗

PubMedDate not supplied

Genetic diversity in twenty variants of the avian polyomavirus.

To determine if different pathotypes of the avian polyomavirus (APV) exist and to compare the genomes of APVs originating from different geographic areas, dates, and species of birds, the partial sequences of 18 APVs were determined. New viral sequences were compared with three published APV sequences. Two of the new viruses had identical sequences. Forty point mutations were found at 31 loci. A 27-bp deletion was found in the VP2 and VP3 open reading frames of one virus. A duplication of the putative origin of replication and adjacent enhancer region was previously reported in one APV. Smaller duplications involving the origin in one APV and a second enhancer region in another were discovered. All duplications were in tissue culture-adapted viruses, suggesting they occurred during the isolation process. Excluding duplications and the deletion, maximum variation between viruses was small (11 bp). A maximum parsimony tree was constructed that contained three major branches. The three earliest isolates were on separate branches. The European viruses were confined to branch I, but APVs from the United States were on all three branches. Lovebird, budgerigar, and macaw APVs were also on each of the three branches, suggesting that species-specific pathotypes have not developed. Most nonsynonymous mutations occurred in a small portion of the VP2 and VP3 open reading frames, demonstrating a selection for these mutations. That a glycine at VP2 221 will inhibit virus replication in chicken embryo fibroblasts (CEFs) has been previously reported. In contrast, six of seven of the new APVs isolated in CEFs had a glycine at VP2 221.

Amino Acid Substitution↗