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E M Meyerowitz

Publications and source records attributed to E M Meyerowitz.

122 records · Page 7Linked to original sources
PubMed1986

Lethal mutations flanking the 68C glue gene cluster on chromosome 3 of Drosophila melanogaster.

We have conducted a genetic analysis of the region flanking the 68C glue gene cluster in Drosophila melanogaster by isolating lethal and semilethal mutations uncovered by deficiencies which span this region. Three different mutagens were used: ethyl methanesulfonate (EMS), ethyl nitrosourea (ENU) and diepoxybutane (DEB). In the region from 68A3 to 68C11, 64 lethal, semilethal, and visible mutations were recovered. These include alleles of 13 new lethal complementation groups, as well as new alleles of rotated, low xanthine dehydrogenase, lethal(3)517 and lethal(3)B76. Six new visible mutations from within this region were recovered on the basis of their reduced viability; all proved to be semiviable alleles of lethal complementation groups. No significant differences were observed in the distributions of lethals recovered using the three different mutagens. Each lethal was mapped on the basis of complementation with overlapping deficiencies; mutations that mapped within the same interval were tested for complementation, and the relative order of the lethal groups within each interval was determined by recombination. The cytological distribution of genes within the 68A3-68C11 region is not uniform: the region from 68A2,3 to 68B1,3 (seven to ten polytene chromosome bands) contains at least 13 lethal complementation groups and the mutation low xanthine dehydrogenase; the adjoining region from 68B1,3 to 68C5,6 (six to nine bands) includes the 68C glue gene cluster, but no known lethal or visible complementation groups; and the interval from 68C5,6 to 68C10,11 (three to five bands) contains at least three lethal complementation groups and the visible mutation rotated. The developmental stage at which lethality is observed was determined for a representative allele from each lethal complementation group.

Alleles↗
PubMed1985

High resolution mapping of in situ hybridized biotinylated DNA to surface-spread Drosophila polytene chromosomes.

We describe a method of mapping genes or transcripts on polytene chromosomes by transmission electron microscopy. We present several applications which illustrate that, in favorable cases, the method has a resolution of ca. 10 kg, and that high resolution mapping of hybridization sites relative to bands and puffs can be achieved. We mapped sites of transcription for poly-(A) RNA and present evidence which shows that these sites are localized in some bands and puffs, but are also found in interbands.

Animals↗
PubMed1984

Adjacent chromosomal regions can evolve at very different rates: evolution of the Drosophila 68C glue gene cluster.

The 68C puff is a highly transcribed region of the Drosophila melanogaster salivary gland polytene chromosomes. Three different classes of messenger RNA originate in a 5000-bp region in the puff; each class is translated to one of the salivary gland glue proteins sgs-3, sgs-7, or sgs-8. These messenger RNA classes are coordinately controlled, with each RNA appearing in the third larval instar and disappearing at the time of puparium formation. Their disappearance is initiated by the action of the steroid hormone ecdysterone. In the work reported here, we studied evolution of this hormone-regulated gene cluster in the melanogaster species subgroup of Drosophila. Genome blot hybridization experiments showed that five other species of this subgroup have DNA sequences that hybridize to D. melanogaster 68C sequences, and that these sequences are divided into a highly conserved region, which does not contain the glue genes, and an extraordinarily diverged region, which does. Molecular cloning of this DNA from D. simulans, D. erecta, D. yakuba, and D. teissieri confirmed the division of the region into a slowly and a rapidly evolving portion, and also showed that the rapidly evolving region of each species codes for third instar larval salivary gland RNAs homologous to the D. melanogaster glue mRNAs. The highly conserved region is at least 13,000 bp long, and is not known to code for any RNAs.

Animals↗
PubMed1984

Steroid regulation of RNAs transcribed from the Drosophila 68c polytene chromosome puff.

The 68C region of the Drosophila melanogaster salivary gland polytene chromosomes harbors the structural genes for the three salivary gland glue proteins sgs-3, sgs-7, and sgs-8. This region is puffed during the third larval instar, the stage when glue proteins are being produced in the salivary glands. The puff regresses near the end of the third instar as a result of an increased titer of the steroid hormone ecdysterone in the larval hemolymph. The experiments reported here were designed to determine whether the ecdysterone effect on puffing at 68C is correlated with hormone effects on expression of the three puff RNAs. In the first series of experiments, it is shown that there is a more rapid disappearance of 68C RNA transcripts from salivary glands cultured in the presence of ecdysterone than from glands cultured in its absence. The second set of experiments, in which 68C transcripts were pulse-labeled in salivary glands cultured in the presence or absence of hormone, demonstrates that one effect of ecdysterone is to cause a sharp reduction in the rate at which newly synthesized 68C transcripts accumulate. The final experiments follow the time required for ecdysterone to produce this effect, and show that it occurs in salivary glands exposed to the hormone for as little as 15 min. In all of the experiments, the RNA products of the Sgs-3, Sgs-7, and Sgs-8 genes acted coordinately.

Animals↗
PubMed1984

A trans-acting regulatory product necessary for expression of the Drosophila melanogaster 68C glue gene cluster.

The mutation l(1)npr-1 is located at cytological location 2B5 on the X chromosome in Drosophila melanogaster. We have found that this mutation causes absence of the normal product of the 2B5 locus and that it has the following phenotypes: the 68C glue puff on the third chromosome does not regress when mutant salivary glands are cultured in the presence of ecdysterone; the three 68C glue protein mRNAs are not synthesized; and a transformed Drosophila strain carrying both a normal resident 68C Sgs-3 gene and an introduced functional Sgs-3 gene with only a few kb of flanking sequences expresses neither Sgs-3 RNA if the l(1)npr-1 mutation is crossed into the stock. Thus the normal product of the l(1)npr-1 gene is required for regression of the 68C puff, and the l(1)npr-1 gene product allows expression of the Sgs-3 gene by interacting, either directly or indirectly, with DNA sequences near this glue protein gene.

Animals↗
PubMed1983

DNA sequences, gene regulation and modular protein evolution in the Drosophila 68C glue gene cluster.

The 68C locus of the Drosophila melanogaster polytene chromosomes contains the structural genes for three glue polypeptides (sgs-3, sgs-7 and sgs-8) synthesized in the larval salivary glands during the third larval instar. When the messenger RNAs for the glue polypeptides are being synthesized, the locus is puffed; the puff regresses in response to the steroid hormone ecdysterone. The three 68C glue mRNAs are coded in a gene cluster of less than 5000 base-pairs, and are expressed co-ordinately. In the experiments described here we show that the coordinate expression of these RNAs does not result from amplification of the puff DNA, nor is it associated with puff DNA rearrangement. We also report the nucleotide sequence of 6751 base-pairs of genomic DNA that includes the entire gene cluster, and describe coding and non-coding sequences with possible regulatory roles. In addition, we deduce the amino acid sequences of the primary translation products of the glue mRNAs, and show that the glue proteins form a diverged gene family. The members of the family all contain an amino-terminal hydrophobic block of amino acids, which is absent in the mature, secreted glue proteins, and a cysteine-rich carboxy-terminal module. sgs-3 differs from sgs-7 and sgs-8 by containing a third module between the other two, comprised largely of tandem repeats of the five amino acids Pro-Thr-Thr-Thr-Lys.

Amino Acid Sequence↗
PubMed1983

The structural genes for three Drosophila glue proteins reside at a single polytene chromosome puff locus.

The polytene chromosome puff at 68C on the Drosophila melanogaster third chromosome is thought from genetic experiments to contain the structural gene for one of the secreted salivary gland glue polypeptides, sgs-3. Previous work has demonstrated that the DNA included in this puff contains sequences that are transcribed to give three different polyadenylated RNAs that are abundant in third-larval-instar salivary glands. These have been called the group II, group III, and group IV RNAs. In the experiments reported here, we used the nucleotide sequence of the DNA coding for these RNAs to predict some of the physical and chemical properties expected of their protein products, including molecular weight, amino acid composition, and amino acid sequence. Salivary gland polypeptides with molecular weights similar to those expected for the 68C RNA translation products, and with the expected degree of incorporation of different radioactive amino acids, were purified. These proteins were shown by amino acid sequencing to correspond to the protein products of the 68C RNAs. It was further shown that each of these proteins is a part of the secreted salivary gland glue: the group IV RNA codes for the previously described sgs-3, whereas the group II and III RNAs code for the newly identified glue polypeptides sgs-8 and sgs-7.

Amino Acid Sequence↗
PubMed1982

Molecular organization of a Drosophila puff site that responds to ecdysone.

The 68C locus in the polytene chromosomes of Drosophila melanogaster salivary glands is puffed during the last half of the third larval instar and harbors the structural gene for sgs3, one of the glue polypeptides synthesized by the glands during this period. This puff regresses in response to the steroid hormone ecdysone. We have isolated a set of overlapping cloned segments that define approximately 50 kb of DNA at the 68C puff locus. Three polysomal poly(A)+ RNAs that are abundant in the salivary glands during the intermolt-puff stage are transcribed from three genes (II, III and IV) that map near the center of the cloned DNA in a 5 kb cluster region. These are the only transcripts from the 50 kb of 68C DNA detectable in these glands, and they are undetectable in other larval tissues at this stage, or in whole animals at other stages of development. Correlative criteria indicate that gene IV, which yields an RNA of 1.1 kb, is the structural gene for sgs3. Genes II and III, which yield RNAs of 0.36 kb and 0.32 kb, respectively, are oppositely oriented so that their promoters are adjacent, suggesting that this pair may form a single regulated unit, a suggestion that is enhanced by the fact that the pair is bounded by an inverted repeat of 0.3 kb elements. The possible, but as yet unidentified, functions of this gene pair are discussed. A 9.2 kb element belonging to a family of transposable elements called roo is inserted adjacent to the 5 kb cluster region in some but not other D. melanogaster strains. This insertion has no obvious effect on the transcription of genes II, III and IV. Although roo elements yield a 9 kb poly(A)+ RNA in embryos, no roo transcripts were detected in intermolt salivary glands, whether they do or do not contain an element at the 68C puff site.

Chromosome Mapping↗
PubMed1980

A new high-capacity cosmid vector and its use.

The construction of a cosmid, MUA-3, designed for the convenient cloning of eukaryotic DNA segments up to 48 kb in length is described. The cosmid contains all of the plasmid pBR322 with approx. 400 bases of lambda DNA, including the cohesive end site, inserted at the pBR322 PstI endonuclease recognition site. Methods for using this vector to construct several types of Drosophila melanogaster genomic DNA libraries are given, and libraries made by these methods are characterized. A sheared Drosophila DNA-EcoRI linker library is shown to stably maintain average Drosophila DNA inserts of over 40 kb and up to 48 kb, and the efficiency of producing clones by a partial restriction and ligation method is shown to be over 3 X 10(5) clones/microgram of Drosophila DNA.

Bacteriophage lambda↗
PubMedDate not supplied

Eukaryotes have "two-component" signal transducers.

The eukaryotic proteins discussed above share a number of amino acid sequence features with prokaryotic members of the two-component signal transducer family. ETR1 and Sln1 each contain putative HPK and receivers, while Skn7 has similarity to receivers only. The other proteins--phytochromes, BCKDH kinase and the dr6 gene product--appear to be distant relatives of the two-component family because they have less-conserved motifs, although even biochemically defined prokaryotic family members can lack conserved motifs (Parkinson and Kofoid, 1992). The eukaryotic and prokaryotic proteins also show similar diversity with respect to the arrangements of the components; transmitters and receivers can lie within the same protein (for example, ETR1 and Sln1 in eukaryotes and BarA and LemA in prokaryotes) or receivers can lie on a separate protein (for example, Skn7 in yeast and CheY in bacteria (Stock et al., 1985)). The new eukaryotic members of the two-component family raise a number of questions, especially since their functions are not yet clearly defined. The identities of the signals transduced are unknown, except for the red light signal for phytochrome. Ethylene is presumably the signal for ETR1, but this has not been demonstrated directly. It also remains to be seen whether eukaryotic two-component modules are functionally homologous to the prokaryotic two-component systems; eukaryotic modules could be utilized in uncharacterized ways, possibly in combination with different signalling components. Among the eukaryotic proteins discussed here, BCKDH kinase has the best-understood function, yet its substrate is not an orthodox response regulator, and moreover, the substrate is phosphorylated at serine residues.

Arabidopsis↗
PubMedDate not supplied

The plant plan: multicellular life in the other Kingdom.

One must conclude, then, that plants and animals may have evolved in quite different fashions. There is no doubt that they have independently evolved development, and this is demonstrated by the nonhomology of genes serving identical developmental functions in prepattern formation. There is nonetheless also no doubt that plants and animals have evolved from a common eukaryotic ancestor, as indicated by the clear homology of the genes that control the chromatin level of gene regulation. There is also little doubt that some developmentally important genes of plants, such as the ethylene and red light receptors, have derived from an event of horizontal evolutionary transfer specific to plants. And it is at least possible to think that the variation on which Darwinian evolution acts in plants results in part from phenomena that are not seen in animals, namely, the controlled appearance and Mendelian inheritance of epigenetically silenced genes. Genomic and genetic analyses of plants thus reveal a type of organism with familiar features, but profound differences from the more-studied animals. Only by further study of plants and of animals can we fully understand the differences between plants and animals, and consequently distinguish between those features of developmental pattern formation and cellular signaling that are necessary aspects of complex organisms, and those that are accidents of evolutionary history.

Animals↗