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Biomedical subjects

G A Gall

Publications and source records attributed to G A Gall.

11 recordsLinked to original sources
PubMed1998

Mitochondrial and nuclear DNA sequence variability among populations of rainbow trout (Oncorhynchus mykiss).

Mitochondrial and nuclear DNA variability was examined to assess population genetic structure and phylogeographic relationships in rainbow trout. Single-strand conformation polymorphisms and restriction site differences within 1055 bp of the mitochondrial D-loop region and 1566 bp of nuclear DNA in six single-copy nuclear DNA regions identified 31 mitochondrial genotypes and 50 nuclear alleles. Gene trees were constructed by sequencing each variant allele or mitochondrial genotype identified. Examination of 30 populations in 10 native rainbow trout groups using analysis of molecular variance (AMOVA) indicated that 65% of mitochondrial variability and 35% of nuclear variability was explained by differences among the 10 groups. Phylogenetic patterns evident in mitochondrial and nuclear DNA were not always concordant. Differences in the evolutionary patterns detected by mitochondrial and nuclear DNA may reflect the differential impact of past introgression events on variability in the two genomes.

Alleles↗
PubMed1997

Polymorphic molecular markers from anonymous nuclear DNA for genetic analysis of populations.

A simple method is presented for developing polymorphic, anonymous DNA markers suitable for population genetic studies. Anonymous DNA fragments are screened for sequence variability using a common mutation detection technique (single strand conformation polymorphism analysis; SSCP) and locus-specific PCR primers are designed for polymorphic DNA fragments. Detection of the markers by SSCP analysis coupled with sequence analysis of SSCP variants allows rapid screening while retaining information about the genealogical relationship among alleles. Variability detected for six markers was assessed in rainbow trout Oncorhynchus mykiss and was compared with variability detected by similar analysis of intron loci. Between three and 12 distinct alleles were observed at each marker locus, and average within-population heterozygosity ranged from 0.12 to 0.44. Advantages and limitations of the methodology for population genetic analysis are discussed.

Alleles↗
PubMed1991

Genetics and reproduction in fish culture.

Fish genetics has made major strides during the past 20 yr due both to improvements in the ability of fish culturists to manage reproduction and to deliberate experimentation and application. The general finding has been that the quantitative genetics of fish differ little from those of other animals and that the applications of animal improvement techniques are similar for fish and other animals. In addition, a number of novel techniques, such as ploidy manipulation and sex reversal, are relatively easy to achieve with a number of fish species. As a result, some very specialized approaches to research have been possible, and applications to fish production seem to be limited only to the imagination of the breeder. However, only limited application has occurred over a major portion of the industry, and genetic improvement of stocks has been achieved in very few instances. The reason for this apparent dichotomy between opportunity and reality seems to be related to the industry's lack of emphasis on genetic improvement.

Agriculture↗
PubMed1979

Adult triploids in a rainbow trout family.

Six triploid individuals were found in a full-sib family of 11 adult rainbow trout (Salmo gairdneri) from a domesticated hatchery stock. The triploid individuals were normal in size and external appearance, had underdeveloped gonads, and showed no evidence of 3n/2n chimerism or mosaicism. XXY triploids were males, suggesting that the Y chromosome is male determining in trout. Because they may avoid production losses associated with sexual maturation in normal fish, triploid trout and salmon could potentially be useful in fish culture.

Aneuploidy↗
PubMed1979

Electrophoretic variation and differentiation in four strains of domesticated rainbow trout (Salmo gairdneri).

A total of 1462 rainbow trout (Salmo gairdneri Richardson) representing four California domestic strains, were examined electrophoretically at 24 gene loci to investigate the amount of genetic variability within strains and genetic differentiation between strains, relative to wild populations. Estimated heterozygosities of 0.071 to 0.134 were similar to those reported for wild populations and thus indicated that the domestic strains were at least as variable as wild populations. Genetic distances between strains ranged from 0.011 to 0.067, values typical of the level of differentiation observed between local conspecific populations in a variety of organisms. It was suggested that this high level of heterozygosity is due to mixing of populations in the strains' histories and perhaps also to balancing selection.

Albumins↗
PubMed1975

Chromosome cytology and polymorphism in the California High Sierra golden trout (Salmo aguabonita).

The population variability in chromosome karyotype was examined in six samples of California High Sierra golden trout, Salmo aguabonita. From the analysis of 1,318 cells from anterior kidney tissue of 92 specimens, the modal diploid chromosome number was 2n equals 58 with 104 chromosome arms. Of cells with 2n equals 58 chromosomes, the typical karyotype was one containing 44 chromosomes with median centromeres, 2 chromosomes with submedian centromeres, 2 with subterminal centromeres and 10 with terminal centromeres. In addition, many cells contained a chromosome with a prominent satellite. Variability in chromosome number within the six populations followed a Robertsonian pattern and permitted the identification of two distinct population distributions. One population, made up of two samples, was more variable than the other and supported the hypothesis that this population was of golden trout times rainbow trout hybrid origin. Texamination of metaphase 1 cells from testes showed numerous ring and rod multivalents consistent with the random nature of Robertsonian variability.

Animals↗
PubMedDate not supplied

Biochemical genetic variation in populations of golden trout, Salmo aguabonita: evidence of the threatened Little Kern River golden trout, S.a. whitei.

Eight wild populations of the High Sierra golden trout, Salmo aguabonita, and one domestic stock of rainbow trout, Salmo gairdneri, were examined for biochemical-genetic variation in eight protein systems. Variation within the eight systems was determined by at least 10 loci in both golden and rainbow trout and all the alleles identified in rainbow trout were observed as electro-phoretically identical phenotypes in golden trout. Variation was observed at an average of 51 percent of the loci in the golden trout samples and for five of the 10 loci in the rainbow trout. Average heterozygosity ranged from 12.6 to 13.9 percent for seven of the golden trout populations with one showing a low value of 5.4 percent. A comparable estimate of 12.1 percent was found for the rainbow stock. On the basis of genetic variation and allele frequencies at three loci, the eight golden trout populations were divided into two distinct groups. Three populations sampled from the Little Kern River basin tended to be genetically distinct from two additional Little Kern River basin populations and from three geographically distinct populations sampled from the eastern Kern River area. The former three populations were hypothesized to be of a recent rainbow-golden hybrid origin. Trout in the other two Little Kern River basin populations, sampled in head-waters of a stream tributary to the Little Kern River, were considered to be the threatened Little Kern golden trout, S. a. whitei Evermann, due to their high degree of genetic similarity to the geographically distinct subspecies S. a. aguabonita sampled from the eastern Kern River area. The finding of substantial genetic variation in the wild golden trout populations indicates that this threatened species is not at present genetically impoverished and thus does not appear to be in immediate danger of extinction through lack of adaptive capability.

Alcohol Oxidoreductases↗
PubMedDate not supplied

Para-albumin polymorphism: an unlinked two-locus system in rainbow trout.

Para-albumin (PALB), a new polymorphic protein system in rainbow trout, is described. Data from 20 ful-sib families established that the observed electrophoretic variability was controlled by two loci. Differential staining of two bands expressed by heterozygotes indicated that the PALB protein was a monomer and that the variability was the result of the expression of two alleles at each locus. The alleles at the two loci were further shown to be identical with regard to electrophoretic mobilities of the proteins. There was no evidence of linkage between the two loci. Consequently, it is concluded that the loci, PALB-1,2, reside on duplicate chromosomes that have retained their integrity since a tetraploidation event.

Alleles↗