PubMed Health⌕ Search

Biomedical subjects

B Yedvobnick

Publications and source records attributed to B Yedvobnick.

24 records · Page 2Linked to original sources
PubMed1983

Molecular cloning of Notch, a locus affecting neurogenesis in Drosophila melanogaster.

The Notch locus is one of the best characterized loci in Drosophila melanogaster in terms of its genetic structure and developmental effects. Mutations in this locus profoundly affect the differentiation of the early embryo. Using an inversion involving the Notch locus and previously cloned sequences, we have isolated chromosomal segments from the Notch region (3C7) encompassing 80 kilobases (kb) of DNA. Based on comparison between mutant and wild-type DNA, we have positioned cloned sequences within the Notch genetic map; furthermore, we have defined a region of approximately 40 kb within which the structural lesions correlating with all Notch alleles mapped to date appear to reside. We have examined the transcriptional activity of the cloned sequences during ontogeny and find a single size class of poly(A)+ RNA, 10.5 kb long, that is homologous to sequences within this 40-kb region. We conclude that DNA sequences belonging to the Notch locus have been cloned and that the 10.5-kb poly(A)+ RNA is essential for wild-type Notch function. We discuss these structural and transcriptional data in light of the existing genetic and developmental characterization of the Notch locus.

Animals↗
PubMed1980

Analysis of disproportionate replication of ribosomal DNA in Drosophila melanogaster by a microhybridization method.

A microhybridization technique is described which requires only 1% of the starting material normally needed for filter-bound methods. Employing this technique, we have investigated the disproportionate replication (compensation) of ribosomal DNA in larval and adult stages of two strains of Drosophila melanogaster. Both stages of the Oregon R strain demonstrate XO compensation while neither stage of Canton S shows a significant elevation of ribosomal DNA content in XOs. It is demonstrated that the lack of disproportionate replication in the latter strain does not result from the absence of the genetic site cr+ which normally controls this process.

Animals↗
PubMed1980

Analysis of the autosomal mutation abo and its interaction with the ribosomal DNA or Drosophila melanogaster: the role of X-chromosome heterochromatin.

The autosomal recessive, maternal-effect mutation abnormal oocyte (abo: 2-38) preferentially lowers the viability os XO progeny. The severity of the sex-ratio distortion is reduced by duplications of maternal or zygotic heterochromatin (SANDLER 1970, 1977; PARRY and SANDLER 1974). Utilizing X-chromosome inversions that contain modifications in the quantity and arrangement of the heterochromatic functions, Xhabo and cr+, wer have extended our investigations of abo's influence on XO male recovery and rDNA redundancy (KRIDER, YEDVOBNICK and LEVINE 1979).--XO males bearing In(1)SCS1LSC4R or In(1)Wm4LSC4R are recovered twice as frequently as X chromosomes containing a single Xh region, implying that these inversions possess a duplication of Xhabo. abo mutant females heterozygous for In(1)SCS1LSC4R and wild-type X chromosomes generate XO progeny that do not contain elevated rDNA redundancies. XO males containing In(1)Wm4 exhibit male recoveries and rDNA elevations similar to those of males bearing a wild-type X chromosome, when both derive from a common abo/abo mother. Reciprocal crosses baetween In(1)Wm4 and Canton-S males to attached-X abo females show significant, though reuduced, sex ratios in the absence of an rDNA effect. The observation that abo can elevate the rDNA redundancy of In(1)Wm4, a chromosome that does not compensate, suggests that abo and cr+ functions are not directly related.

Animals↗
PubMed1979

The effect of abo phenotypic expression on ribosomal DNA instabilities in Drosophila melanogaster.

The recessive maternal-effect mutation, abnormal oocyte (abo:2--38), reduces viability in the offspring of homozygous mutant females. Zygotes lacking specific heterochromatic segments of the X or Y chromosomes are most severely affected. We have shown that abo/abo lines can lose the capacity to express the mutant phenotype, and that elevated rDNA redundancies can be observed in such stocks (Krider and Levine 1975). In this study, we describe a microhybridization procedure that facilitates the measurement of rDNA redundancy, using a small number of adult Drosophila. We show that instability of the rDNA content persists in an abo/abo line after loss of the capacity to express the phenotype, and that changes in rDNA amounts occur between successive generations of the stock. Further, we show that the rDNA content of XO progeny from abo/abo females is elevated. The effect is directly correlated with the expression of the abo phenotype, and it is not observed in the XO progeny of abo heterozygous females or abo homozygotes from lines that do not show abo expression.

Animals↗
PubMed1976

The ribosomes of Drosophila. III. RNA and protein homology between D. melanogaster and D. virilis.

The extent of interspecific homology between D. melanogaster and D. virilis for ribosomal RNA and ribosomal protein was examined using the techniques of two-dimensional gel electrophoresis, and RNA-DNA filter hybridization. Only 2 of the 71 ribosomal proteins resolved were found to be species specific, while comparisons of soluble larval hemolymph protein patterns showed little similarity. Depending on the technique employed, the sequence homology for 18S + 28S ribosomal RNA was found to be between 83-94%, and sequence homology for 5S rRNA was judged to be complete.

Animals↗