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At least 883 records · Page 49Linked to original sources
PubMed1982

Analysis of the phenotypes exhibited by rudimentary-like mutants of Drosophila melanogaster.

Flies mutant for one or both of the last two enzymes of de novo pyrimidine biosynthesis express a number of phenotypes that are also expressed by mutants of the first four pathway enzymes (r and Dhod-null mutants). However, r-1 flies also express two phenotypes, mottled eyes and poor viability, that are not usually expressed by r and Dhod-null flies. Chemical determinations show that orotic acid, a substrate for the fifth pathway enzyme, accumulates in r-1 individuals but not in r and wild-type individuals. Moreover, flies simultaneously mutant for r and r-1 do not express the mottled-eye phenotype, showing that r is epistatic to r-1 for this r-1-specific phenotype. When genotypically wild-type flies are cultured on a medium containing 6-azauracil, the base of a potent inhibitor of the last enzyme of de novo pyrimidine biosynthesis, phenocopies are obtained that include the mottled-eye as well as the wing phenotypes of r-1 flies. These results support hypotheses that the phenotypes common to r, Dhod-null, and r-1 flies are consequences of uridylic acid deficiency, whereas the r-1-specific phenotypes result from orotic acid accumulation in flies lacking either or both of the last two enzymes of de novo pyrimidine biosynthesis.

Animals↗
PubMed1978

Drosophila hemolymph proteins: purification, characterization, and genetic mapping of larval serum protein 2 in D. melanogaster.

Three of the major protein species present in the hemolymph of Drosophila melanogaster larvae just prior to pupation are absent from second instar larvae but accumulate rapidly during the third instar. This article describes the purification and characterization of one of these, larval serum protein (LSP) 2, using an immunological assay. It is a homohexamer of molecular weight about 450,000, with a polypeptide molecular weight of 78,000--83,000. Fast and slow electrophoretic variants of this protein map between the markers vin and gs, at 36--37 on chromosome 3.

Animals↗
PubMed1980

Altered secretion of kidney lysosomal enzymes in the mouse pigment mutants ruby-eye, ruby-eye-2-J, and maroon.

Melanosomes and lysosomes share structural and biosynthetic properties. Three mouse pigment mutants, ruby-eye, ruby-eye-2-J, and maroon, have abnormally high concentrations of kidney lysosomal enzymes. concentrations of kidney nonlysosomal enzymes and of liver and serum lysosomal enzymes are normal. By light microscopy the mutants have normal kidney lysosome morphology. It does not appear that the mutant genes cause an increased rate of production of lysosomes since the increased kidney beta-glucuronidase concentration is not accompanied by a corresponding increase in rate of synthesis. The common defect in all mutants is a decreased rate of secretion of lysosomal enzymes from kidney into urine. Eight mouse pigment mutants are not known which affect both melanosome and lysosome function. They should serve as useful models for the study of the biogenesis, structure, and processing of these and other subcellular organelles.

Animals↗
PubMed1992

Uptake and incorporation in pteridines of externally supplied GTP in normal and pigment-deficient eyes of Drosophila melanogaster.

Some aspects of the synthesis of drosopterins in the eyes of Drosophila melanogaster have been studied in flies with different levels of white gene expression. The activity of GTP cyclohydrolase was found to differ between wild-type and yellow-eyed mutants in vivo but not in vitro. To elucidate the uptake of substrate, we measured the removal of labeled GTP from the incubation medium by excised pupal eyes and followed the subsequent fate of this label. It was found that GTP was dephosphorylated to guanosine extracellularly before label was taken up by the eye tissue. The uptake was much lower in yellow and white eyes than in wild-type eyes, and in the latter, a considerable part of the label was present in pteridine compounds. The strain differences in the uptake of label seem to be due to different rates of intracellular utilization of guanine derivatives in pteridine synthesis. We suggest that this is caused by a hampered transport of precursor (possibly GTP) in white and zeste eyes through the membrane of red pigment granules.

Animals↗
PubMed1976

Relations between twins' similarity of appearance and behavioral similarity: testing an assumption.

Questionnaires rating twins' physical similarity and similarity of dress were obtained from the parents of 121 identical and 70 same-sex fraternal twin pairs. Within-pair difference scores on several behavioral measures (two intelligence tests, two perceptual tests, one reading test, one test of speech articulation, and one personality inventory) were correlated with the twins' scores for physical similarity and similarity of dress. The correlations revealed no systematic relation between the similarity of appearance and the similarity of behaviors for either the identical twin pairs or the same-sex fraternal twin pairs. The assumption that twins' behaviors are more alike because they are more similar in appearance does not seem warranted.

Body Height↗
PubMed1977

Light intensity and phototaxis in the house fly: photonegativity in a yellow-eyed mutant.

Y-tube tests of phototactic behavior of house flies (Musca domestica L.) involving wild-type, yellow-eyed, and hybrid individuals were conducted under low (8 ft-candles, 86.1 lux) and high (1600 ft-candles, 17,222.8 lux) light intensities. The Y-tube design utilized either a clear or a dark stem leading to the branches where the photochoice was made. No significant differences were found in the responses of the wild-type and hybrid lines to either light intensity or Y-tube design. Significant differences were recorded for the yellow-eyed individuals only under high light intensities, whereas their behavior under low light conditions was indistinguishable from that of the wild phenotypes. Yellow-eyed flies showed a 68.6% photopositive response when tested in dark-stemmed Y-tubes under 1600 ft-candles intensity as compared to the 86.0% and 83.3% photopositive responses of the wild and hybrid lines, respectively. However, the yellow-eyed flies tested in the clear-stemmed Y-tubes under 1600 ft-candles showed only a 28.7% photopositive response--a clear reversal toward photonegativity. Light-dark adaptation of the highly sensitive yellow-pigmented eye while in the stem of the Y-tube is responsible for this switch toward photonegative behavior.

Animals↗
PubMed1977

Genetic and light intensity effects on the activity and emigratory behavior of the house fly, Musca domestica (L.).

The emigratory behavior and locomotor activity of yellow-eyed (y/y), wild-type (+/+), and heterozygous (+/y) house flies was examined at 8 fc (86 lx) and 1600 fc (17,223 lx) light intensities. At 8 fc, emigration rate and activity of the y/y flies was similar to that of the +/+ and +/y flies. However, at 1600 fc, the y/y flies emigrated at twice the rate and showed an activity of about one-third that of the other genotypes. The behavior of the +/+ and +/y flies remained similar regardless of the experimental design or light intensity. The excessive neural stimulation by high-intensity light resulting from reduced shielding pigments led to behavioral modifications in the visual and tactile responses of the y/y flies.

Animals↗
PubMed1976

Behavior and single gene substitution in Drosophila melanogaster. I. Mating and courtship differences with w, cn, and bw loci.

The effect of single allele substitutions into an isogenic background in Oregon-R inbred lines of Drosophila melanogaster on courtship and mating patterns has been studied. A comparison has been made between the white locus w, wco, we, the wild type w+, cn, bw, and cn bw to test the effect of eye pigmentation in influencing courtship and mating patterns. It was found that w, we, wco, cn, and bw females were more successful in mating than were wild-type and cn bw females, cn bw females being less successful than wild-type females. Also, w and cn bw males were equally successful in mating but less successful than wild-type males during the 20-min test period. The mutant males performed as well as the wild-type after courtship was initiated. The behavioral parameters measured were (1) courtship latency, the time from exposure of male to female until orientation; (2) mating speed, the time from beginning of orientation of male to female until successful copulation, and (3) copulation time.

Animals↗
PubMed1993

Mechanism of induction of Bar-like eye malformation by transient overexpression of Bar homeobox genes in Drosophila melanogaster.

The Bar locus of Drosophila is known to be a small complex consisting of two similar homeobox genes, BarH1 and BarH2. Using egr as an ommatidium marker, possible mechanisms of formation of malformed eyes were examined. As in the case of BarH1, overexpression of BarH2 was found to be capable of inducing Bar-like eye malformation. It was suggested that suppression of the anterior progression of the morphogenetic furrow and inhibition of reinitiation of normal ommatidial differentiation were mandatory to formation of the reduced eye morphology in Bar mutants.

Animals↗
PubMed1997

The effects of 20-hydroxyecdysone on the differentiation in vitro of cells from the eye imaginal disc from Drosophila melanogaster.

We have examined the effects of the insect ecdysteroid, 20-hydroxyecdysone, on the differentiation of neuronal and non-neuronal elements in the developing adult visual system, using in vitro methods in Drosophila. We examined the differentiation of early neuronal markers in the presence and absence of 1 microgram/ml 20-hydroxyecdysone. Immunoreactivity to 22C10, a marker of an early neuronal antigen, as well as to the photoreceptor-specific antibody 24B10, suggests that differentiation of neuronal and photoreceptor antigens does not require 20-hydroxyecdysone. In eye-discs cultured from animals 5 hours after the white prepupa (P + 5), ommochrome pigmentation first appeared after 2 days in 1 microgram/ml 20-hydroxyecdysone, but cultures lacked pigmentation without 20-hydroxyecdysone. Our culture conditions failed to support the formation of the second screening pigment, drosopterins, even with 20-hydroxyecdysone. Eye discs from P + 5 also formed lenses and interommatidial bristles in culture when 20-hydroxyecdysone was added but not in cultures devoid of the hormone. The differentiation of synaptotagmin and the elongation of extending photoreceptor neurites from eye disc fragments both occur in the absence of 20-hydroxyecdysone in cultures, but adding the hormone increased average neurite length. The threshold for enhanced neurite length was less than 125 ng/ml 20-hydroxyecdysone. Eye-disc cultures also developed immunoreactivity to histamine, the photoreceptor transmitter, from synthesis not re-uptake, in both the presence and in the absence of 20-hydroxyecdysone. These findings suggest that photoreceptor axons may be able to release transmitter in vivo both when they grow into the optic lobe and during the subsequent events in synapse formation.

Animals↗
PubMedDate not supplied

Skin type distribution and skin disease in Ireland.

The Irish are generally considered to have a fair complexion. We surveyed the distribution of skin type in an Irish city population (n = 1000). Skin type prevalence was as follows: type 1: 26%, type 2: 49.6%, type 3: 19.7%, type 4: 4.3%, type 5: 0.3%, type 6: 0.1%. Sunbeds were used by 16% of the population. Malignant melanoma occurred in 1.4% of patients, non-melanoma skin cancer in 6%. The high frequency of sunbed use in a fair skinned population and the high incidence of skin cancer is disturbing and highlights the need for ongoing public health education regarding ultraviolet radiation risks.

Adolescent↗