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A Preiss

Publications and source records attributed to A Preiss.

53 records · Page 3Linked to original sources
PubMed1994

The Notch signalling pathway is required for Enhancer of split bHLH protein expression during neurogenesis in the Drosophila embryo.

The Enhancer of split locus is required during many cell-fate decisions in Drosophila, including the segregation of neural precursors in the embryo. We have generated monoclonal antibodies that recognise some of the basic helix-loop-helix proteins encoded by the Enhancer of split locus and have used them to examine expression of Enhancer of split proteins during neurogenesis. The proteins are expressed in a dynamic pattern in the ventral neurogenic region and are confined to those ectodermal cells that surround a neuroblast in the process of delaminating. There is no staining in the neuroblasts themselves. We have also examined the relationship between Enhancer of split protein accumulation and the Notch signalling pathway. Protein expression is abolished in a number of neurogenic mutant backgrounds, including Notch, but is increased as a result of expressing a constitutively active Notch product. We conclude that Notch signalling activity is directly responsible for the accumulation of basic helix-loop-helix proteins encoded by the Enhancer of split locus.

Animals↗
PubMed1993

Drosophila evolution challenges postulated redundancy in the E(spl) gene complex.

The Enhancer of split [E(spl)] gene complex belongs to the class of neurogenic loci, which, in a concerted action, govern neurogenesis in Drosophila. Two genetically distinct functions, vital and neurogenic, reside within the complex defined by lethal mutations in the l(3) gro gene and by the typical neurogenic phenotype of deletions, respectively. Such deletions always affect several of the many embryonically active genes in the region, which cannot be mutated separately to lethality. Seven of these genes are extremely similar at the transcription and sequence level sharing the basic helix-loop-helix (bHLH) motif of transcriptional regulators. While these E(spl) bHLH genes seem to be required collectively for neurogenesis, they are nonessential individually, suggesting functional redundancy of the encoded gene products. No specific functions could yet be ascribed to any of the other genes located within the complex. One might expect these apparently dispensable genes, as well as the supposedly redundant bHLH genes, to be under little evolutionary constraint and, thus, to evolve most rapidly. However, we find the entire E(spl) gene complex highly conserved during Drosophila evolution, indicating that all the genes as well as their organization are of functional importance.

Amino Acid Sequence↗
PubMed1992

Hairless, a Drosophila gene involved in neural development, encodes a novel, serine rich protein.

Hairless is a dominant loss of function mutation in Drosophila affecting the formation of adult sensory organs. In the mutants, neuronal precursor cells do not differentiate, suggesting that Hairless might be involved in specifying or realizing neuronal fate in the fly, similar to the 'pro-neural' genes of the achaete-scute complex. As highlighted by the manifold phenotypic interactions of Hairless with most of the neurogenic loci, the gene might play an important role in nervous system development. Therefore, we initiated a molecular analysis of the Hairless locus in order to elucidate the function of its gene product and gain insight into the biochemical nature of the observed genetic interactions in which it participates. Here, we report the molecular cloning of the Hairless locus, confirmed by breakpoint and transformation analysis. Unexpectedly, Hairless activity peaks during embryogenesis, where transcripts accumulate primarily in endo- and mesodermal cell layers, and is lowest during larval stages, the lethal phase of Hairless mutants. The putative Hairless protein deduced from DNA sequencing is extremely basic and highly enriched in serine residues. Hairless appears to encode a novel protein without compelling homology to other known proteins which function in specifying peripheral nervous system development in Drosophila.

Amino Acid Sequence↗
PubMed1991

Triterpene saponins from Verbascum songaricum.

Songarosaponin A, B and C isolated from the aerial parts of Verbascum songaricum were shown to be 3-O-[alpha-L-rhamnopyranosyl-(1----4)-beta-D-glucopyranosyl-(1----3)]-[b eta-D-glucopyranosyl-(1----2)-beta-D-fucopyranosyl]-olea-11,13-die ne-3 beta-23,28-triol, 3-0-[alpha-L-rhamnopyranosyl-(1----4)-beta-D-glucopyranosyl-(1----3)]-[b eta-D-glucopyranosyl-(1----2)]-beta-D-fucopyranosyl]-olea-1 1-ene-3 beta-13,23,28-tetrol and 3-O-[beta-D-glucopyranosyl-(1----4)]-[beta-D-glucopyranosyl-(1----3)]-[b eta-D-glucopyranosyl-(1----2)]-beta-D-fucopyranosyl]-13 beta,28-epoxyolea-11-ene-3 beta,23-diol.

Carbohydrate Sequence↗
PubMed1991

Two genetically and molecularly distinct functions involved in early neurogenesis reside within the Enhancer of split locus of Drosophila melanogaster.

Molecular correlation of the genetic aspects of the function of the neurogenic gene Enhancer of split [E(spl)] has previously been hampered by the densely transcribed nature of the chromosomal region within which it resides. We present data indicating that two distinct molecular species contribute to E(spl) function. Analysis of new E(spl) alleles has allowed us to define two complementing functions within the locus. Subsequent phenotypic analysis of different E(spl) deficiencies combined with P element-transformed constructs has demonstrated that these two functions correspond to: (1) a family of helix-loop-helix (HLH) protein-encoding genes and (2) the single copy gene E(spl) m9/10, whose product shares homology with G-protein beta subunits. The zygotically active E(spl) HLH genes can, at least partially, substitute for one another's functions and their total copy number determines the activity of the locus. E(spl) m9/10 acts synergistically with the E(spl) HLH genes and other neurogenic genes in the process of neurogenesis. The maternal component of E(spl) m9/10 has the most pronounced effect in neurogenesis, while its zygotic component is predominantly required during postembryonic development. The lethality of trans-heterozygotes of null E(spl) deficiency alleles with a strong Delta point mutation is a result of the concomitant reduction in activity of both E(spl) HLH and m9/10 functions. Immunocytochemical localization of the E(spl) m9/10 protein has revealed that it is a ubiquitously distributed nuclear component in embryonic, larval and imaginal tissues.

Alleles↗
PubMed1990

Regulation of the segmentation gene fushi tarazu has been functionally conserved in Drosophila.

An evolutionary approach was applied to identify elements involved in the regulation of the segmentation gene fushi tarazu (ftz) by comparing the Drosophila melanogaster ftz gene with its Drosophila hydei homologue. The overall organization of the ftz gene is very similar in both species. Surprisingly, ftz proved to be inverted in the ANT-C of D. hydei with respect to D. melanogaster. Strong homologies extend over the entire 6 kb of the ftz upstream region with the best match in the 'upstream element'. We identified several highly conserved boxes embedded in unrelated sequences that correspond extremely well to two germ layer specific enhancers in the upstream element. Transformation experiments revealed that D. hydei ftz gene products can restore D. melanogaster ftz function and, furthermore, that trans-acting factors from D. melanogaster recognize and control D. hydei ftz regulatory elements. These findings indicate a conservation of the entire regulatory network among segmentation genes for several millions of years during the evolution of Drosophila.

Animals↗
PubMed1988

A deduced gene product from the Drosophila neurogenic locus, enhancer of split, shows homology to mammalian G-protein beta subunit.

The correct segregation of neural from epidermal lineages in Drosophila embryogenesis depends on the activity of the six zygotic "neurogenic" genes. One of the neurogenic genes, Enhancer of split, is particularly noteworthy in its genetic interactions with Notch and Delta, which both appear to code for transmembrane proteins with homology to the epidermal growth factor. Transformation experiments have demonstrated the cloning of sequences necessary for Enhancer of split gene function. We report here that the gene product derived from DNA sequencing shows homology to the beta subunit of mammalian G proteins and CDC4, a yeast cell cycle gene. We demonstrate that expression of the transcripts relates to the developing central nervous system. These data suggest a mechanism of interaction between the gene products of Notch and Enhancer of split.

Amino Acid Sequence↗
PubMed1988

The molecular genetics of Enhancer of split, a gene required for embryonic neural development in Drosophila.

In Drosophila, the very first steps in neurogenesis appear to be controlled by a small group of zygotically acting genes termed the neurogenic loci. Mutations in any of these genes result in a misrouting of epidermal lineages into the neural pathway. Morphological and molecular studies suggest that the correct ectodermal differentiation is mediated by a cell-cell interaction mechanism and that at least some of the neurogenic loci are involved in this mechanism. The molecular analyses of the neurogenic loci Notch and Delta revealed that the putative gene products are large transmembrane proteins with homology to mammalian epidermal growth factor. We describe here a molecular analysis of Enhancer of split [E(spl)], a third neurogenic locus, which displays striking genetic interactions with both Notch and Delta, suggesting a close functional relationship of the respective gene products. We provide evidence for a single genetic complementation group corresponding to a single transcription unit which is necessary for wild-type E(spl) function. P-element-mediated transformation indicates that this transcription unit includes functions associated with both the dominant E(spl)D mutation and the recessive visible allele groucho, and is necessary for the correct differentiation of the embryonic nervous system.

Animals↗
PubMed1987

The gooseberry-zipper region of Drosophila: five genes encode different spatially restricted transcripts in the embryo.

Genetic analysis of the Drosophila chromosome region 60 E9-F1 identified two functions affecting embryonic development; gooseberry (gsb), a segment polarity gene, and zipper (zip), an unclassified gene which affects cuticle formation severely. By contrast, molecular analysis revealed five genes with different temporal and spatial patterns of expression in the embryo. Candidate genes for gsb and zip functions were identified. Two adjacent genes are eventually expressed in regular stripes within the posterior region of each segment. One of them is expressed initially in a pair-rule mode; the second gene expresses reduced levels of transcripts in a mutant which leaves the transcribed region and the sequences up to the second gene intact. This observation, the patterns of transcripts in the embryo and the genetic data suggest that both genes are involved in gooseberry segmentation function. zip is expressed in neural tissue and not in epidermal anlagen. Embryos lacking zip activity also develop abnormal neural tissue consistent with the argument that the zip cuticle phenotype is a secondary effect. Additional newly identified genes are expressed in specific domains of the embryo, covering mesoderm anlagen and the dorsal region of embryos at blastoderm stage, respectively.

Journal Article↗
PubMed1986

A conserved family of nuclear proteins containing structural elements of the finger protein encoded by Krüppel, a Drosophila segmentation gene.

Krüppel (Kr), a segmentation gene of Drosophila, encodes a protein sharing structural features of the DNA-binding "finger motif" of TFIIIA, a Xenopus transcription factor. Low-stringency hybridization of the Kr finger coding sequence revealed multiple copies of homologous DNA sequences in the genomes of Drosophila and other eukaryotes. Molecular analysis of one Kr-homologous DNA clone identified a developmentally regulated gene. Its product, a finger protein, relates to Kr by the invariant positioning of crucial amino acid residues within the finger repeats and by a stretch of seven amino acids connecting the finger loops, the "H/C link." This H/C link is conserved in several nuclear and chromosome-associated proteins of Drosophila and other eukaryotic organisms including mammals. Our results demonstrate a new subfamily of evolutionarily conserved nuclear and possibly DNA-binding proteins that again relate to a Drosophila segmentation gene as in the case of the homeo domain.

Animals↗
PubMed1977

Sudan Black B: chemical structure and histochemistry of the blue main components.

Sudan Black B contains two blue main components, SSB-I and SSB-II. Their chemical structures were determinated by the aid of two-dimensional thin-layer chromatography, column chromatography, absorption, IR, mass, H1-NMR, and C13-NMR spectroscopy and were proved by alternate synthesis. SSB-I has been found to be 2,3-dihydro-2,2-dimethyl4-[(4-phenylazo-1-naphthalenyl)-azol]-1H-perimidine. For SSB-II was confirmed the known structure 2,3-dihydro-2,2-dimethyl-6-[(4-phenylazo-1-naphthalenyl)-azo]-1H-permidine. Relations of chemical structure of SSB-I and SSB-II to their staining properties are discussed.

Azo Compounds↗
PubMedDate not supplied

Molecular genetics of Krüppel, a gene required for segmentation of the Drosophila embryo.

Krüppel is a member of the 'gap' class of segmentation genes of Drosophila melanogaster, mutations of which cause contiguous groups of segments of the fruitfly embryo to fail to develop. In the case of Krüppel mutant embryos, thoracic and anterior abdominal segments are deleted. The molecular cloning of the Krüppel locus will lead to an understanding of the crucial role that gap genes seem to have in early embryonic development. It has already allowed the identification of a blastoderm-specific Krüppel transcript and the phenotypic rescue of mutant embryos by injected cloned DNA.

Alleles↗
PubMedDate not supplied

Production of phenocopies by Krüppel antisense RNA injection into Drosophila embryos.

The demonstration that a specific messenger RNA can be functionally inactivated in vivo by hybridization to complementary polynucleotide sequences suggests a direct approach to the study of gene function in cells of higher organisms. The experiments described here were designed to inhibit, by complementary RNA sequences, a specific gene function affecting the fate of the Drosophila embryo. We used the SP6 vector in vitro transcription system to transcribe parts of the normally untranscribed (nonsense) strand of the Krüppel (Kr) gene into complementary Kr RNA (Kr antisense RNA). Wild-type Drosophila embryos, injected with this RNA, developed into phenocopies of Kr mutant embryos.

Animals↗
PubMedDate not supplied

Spatial and temporal patterns of Krüppel gene expression in early Drosophila embryos.

The Krüppel (Kr) locus is a member of the 'gap' class of segmentation genes of Drosophila melanogaster. Mutations at the Kr locus cause the deletion of contiguous segments from the embryonic body pattern. We have elucidated the spatial and temporal characteristics of Kr gene expression during early embryo development, the localization of cytoplasmic Kr+ activity and its spatial requirement for normal segmentation.

Animals↗