PubMed Health⌕ Search

Biomedical subjects

T A Markow

Publications and source records attributed to T A Markow.

45 records · Page 3Linked to original sources
PubMed1978

Positive and negative geotaxis: sex-linked traits in Drosophila pseudoobscura.

Using a Hirsch classification maze, selection was made for positive and negative geotactic behaviors in three different strains of Drosophila pseudoobscura. Hybridization studies were then carried out with flies from the diverged strains. The geotactic scores of the parents and F1 flies indicate that both negative and positive geotactic behaviors in these strains are strongly influenced by genes in the X chromosome. Additional hybridization studies using flies from strains with similar phenotypes suggest that the diverged strains contain similar alleles and the number of loci in the X chromosomes responsible for these types of behavior is limited. The loci may be highly organized in the X chromosome.

Animals↗
PubMed1977

Effect of age and of screening pigment mutations on the phototactic behavior of Drosophila melanogaster.

Five different eye color mutations of Drosophila melanogaster have been tested for their effect on phototactic behavior. All five mutations seem to cause flies to be less photonegative than Canton-S control flies. The mutation sepia was found to produce this effect when heterozygous as well. It was also found that wild-type flies from highly photopositive and photonegative strains seem to be more photoneutral with age.

Age Factors↗
PubMed1977

Phototactic and geotactic behavior of countercurrent defective mutants of Drosophila melanogaster.

Ten behavioral mutations, originally isolated in the countercurrent fractionation device, were tested in phototaxis and geotaxis mazes. While none of the mutations caused an altered ERG, they all caused photomaze behavior to differ from that seen in Canton-S controls. Eight of the mutants showed altered geotactic behavior. There was no correlation between the kind of change in phototactic behavior and the geomaze behavior of a given mutant. Certain mutations cause flies to be more photopositive and more geonegative than Canton-S; others result in behavior that is photo- and geopositive. The results suggest that certain mutations may be affecting visual components other than the ERG while other mutations may be more centrally or generally acting.

Animals↗
PubMed1977

Genetic analysis of phototactic behavior in Drosophila simulans.

Phototaxis mazes have been employed to select photopositive and photonegative strains of Drosophila simulans. The results suggest that phototactic behavior in D. simulans, as in other Drosophila species, is a polygenic trait. Hybridization using divergent strains revealed that the genes controlling negative phototactic behavior in D. simulans are autosomal, as opposed to D. melanogaster in which negative phototactic behavior is known to be very strongly sex-linked.

Animals↗
PubMed1975

A genetic analysis of phototactic behavior in Drosophila melanogaster. II. Hybridization of divergent populations.

Artificial selection has produced populations of Drosophila melanogaster which show either positive or negative phototactic behavior. Selection was carried out in the presence of various marked multiple inversions used to suppress genetic recombination. Reciprocal hybridizations between photopositive and photonegative populations of flies have revealed the X chromosome of D. melanogaster to be important in phototactic behavior regardless of conditions which restricted genetic recombination during selection.

Animals↗
PubMed1975

A genetic analysis of phototactic behavior in Drosophila melanogaster I. Selection in the presence of inversions.

The effectiveness of selection for positive and negative phototactic behavior in populations of Drosophila melanogaster heterozygous for various multiple inversions was compared using the method of realized heritability. Selection in the presence of FM6, SM1 or TM3 alone was as effective as in populations carrying no inversions. However, the presence of FM6 and TM3 together reduced the effectiveness of selection for photopositive behavior and FM6 and SM1 and TM3 restricted the response to selection for negative phototactic behavior. The results are discussed in terms of the organization of genes influencing phototactic behavior in this species.

Animals↗
PubMedDate not supplied

Inbreeding and developmental stability in a small human population.

Inbreeding coefficients are reported for all members of the isolated Havasupai tribe of northern Arizona (USA), based upon pedigrees which are as deep as eight generations. Because inbreeding has been repeatedly shown to reduce developmental homeostasis in a large number of species, we ask if the degree of inbreeding in the Havasupai is associated with reduced developmental stability. Fluctuating asymmetry in two dermatoglyphic traits suggests that inbreeding significantly compromises developmental homeostasis in this population.

Analysis of Variance↗
PubMedDate not supplied

Effects of age on water balance in Drosophila species.

Age-related declines in physiological performance have been documented in a wide variety of organisms. However, it is unknown whether related species age in a similar manner or whether physiological differences associated with aging differ widely among species. Previous work has shown that the desiccation resistance of Drosophila melanogaster decreases rapidly with age. Other Drosophila species may have delayed reproductive maturity or may inhabit arid habitats, so that age-related changes in water balance may be a significant physiological constraint on their ecological success. We may, therefore, predict that physiological systems involved in water balance will deteriorate with age at a reduced rate in these species. We quantified several components of water budgets for 14 species of Drosophila, including both desert and mesic representatives differing in their age of maturity. Desiccation resistance decreased with age in all but one species studied, primarily because of increased rates of water loss. However, there was no significant relationship between the rate of aging, as indicated by the rate of increase in water-loss rates as flies aged, and either habitat or age of maturity.

Age Factors↗