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D Hirsh

Publications and source records attributed to D Hirsh.

At least 37 records · Page 2Linked to original sources
PubMed1995

A widely expressed novel C2H2 zinc-finger protein with multiple consensus phosphorylation sites is conserved in mouse and man.

We have cloned a murine cDNA whose deduced sequence encodes a 455-amino-acid (aa) zinc-finger protein (Zfp), PZf (penta Zf protein). Sequence analysis shows that PZf has multiple phosphorylation consensus sites for casein kinase II and protein kinase C in its N-terminal portion. This region (aa 1 to 197), which does not share significant homology to known aa sequences, has a number of charged (39 Glu, 15 Asp, 23 Lys, 22 Arg) and hydroxyl (20 Ser, 12 Thr) aa. This potentially phosphorylatable region is followed by five C2H2 Zf in the middle of the protein. The Pzf gene is transcribed as a 5-kb mRNA in all murine tissues examined. The human genome also seems to contain one or more Pzf-related genes.

Amino Acid Sequence↗
PubMed1995

A model of intrauterine infection and preterm delivery in mice.

OBJECTIVE: Our purpose was to determine whether intrauterine bacterial inoculation leads to preterm delivery in mice. STUDY DESIGN: Fifty-four female CD-1 mice at 75% of the length of the gestational period (14.5 days) received either an intrauterine bacterial inoculum of 2 to 10 x 10(3) Escherichia coli (n = 33), an intraperitoneal bacterial inoculum (n = 7), or an intrauterine injection of a sterile solution (n = 14). RESULTS: Delivery within 48 hours of surgery occurred in 91% of mice after intrauterine bacteria, in 0% after intraperitoneal bacteria, and in 7% after sterile intrauterine injection (p < 0.001). Intrauterine bacterial inoculation produced systemic infection (i.e., recovery of organisms from culture of the heart) in 50% of animals post partum. Intraperitoneal bacteria and intrauterine saline solution injections resulted in systemic infection rates of 20% and 0%, respectively, 48 hours after surgery. Five of seven animals injected with bacteria into the uterus had histologic evidence of metritis, mild in all cases. Intrauterine bacterial inoculation resulted in induction of ribonucleic acid transcripts for tumor necrosis factor-alpha, interleukin-1 alpha, interleukin-1 beta, and cyclooxygenase-2. CONCLUSIONS: Intrauterine inoculation with Escherichia coli in mice leads to preterm delivery and the local induction of factors known to be involved in human preterm labor with infection. The observation that intraperitoneal bacterial inoculation does not result in preterm delivery suggests that in this model labor is the product of a local (uterine) stimulus.

Animals↗
PubMed1994

Expression of I mu-C gamma hybrid germline transcripts subsequent to immunoglobulin heavy chain class switching.

Germline CH transcripts initiate from a non-coding I exon and terminate downstream of the associated CH exons. Ig heavy chain class switch recombination from the VDJ-C mu gene to particular downstream CH genes appears to be regulated by a process that involves mitogen and/or cytokine induction of germline CH transcripts from the downstream genes. We have examined the expression of germline C mu transcripts (I mu-C mu transcripts) in splenic B cells and pre-B cell lines after cytokine and mitogen stimulation. In contrast to the expression of the germline transcripts from downstream CH genes, expression of germline C mu transcripts was constitutive and unaffected by mitogen and cytokine treatment. After a primary switch recombination event, the germline I mu promoter, which is now associated with a downstream CH gene, continues to be active--leading to the generation of a novel germline transcript consisting of the I mu exon spliced to the CH exons of the switched CH gene. We discuss the potential role of the expression of hybrid I mu-containing transcripts in the class switch process. We also describe a novel and sensitive assay, based on the detection of the hybrid I mu-containing transcripts, that allows detection of class switch recombination events even in heterogeneous populations of cells.

Animals↗
PubMed1992

Conservation of gene organization and trans-splicing in the glyceraldehyde-3-phosphate dehydrogenase-encoding genes of Caenorhabditis briggsae.

The genes encoding body-wall-specific glyceraldehyde-3-phosphate dehydrogenase from Caenorhabditis briggsae were sequenced and compared to the homologous genes from Caenorhabditis elegans. The direct tandem organization of these genes, gpd-2 and gpd-3, and the size and location of the two introns in each gene are the same in C. elegans and C. briggsae. Primer-extension studies demonstrated that the two genes in C. briggsae are trans-splice differentially with the same splice leader (SL) RNAs as are observed in C. elegans. The gdp-2 gene is trans-spliced with SL1 while gdp-3 is trans-spliced with SL2. Significant sequence conservation was observed within the promoter regions of each species and may indicate those regions responsible for body-wall-muscle-specific gene expression and/or differential trans-splicing. Comparisons of the sequences suggest that the tandem repeat of the genes has been subjected to concerted evolution and that C. briggsae and C. elegans diverged much earlier than would be anticipated based on morphological similarities alone. Finally, an open reading frame found several hundred nucleotides upstream from gpd-2, in both species, appears to be homologous to the ATP synthase subunit, ATPase inhibitor protein, from bovine mitochondria.

Amino Acid Sequence↗
PubMed1990

mRNAs that mature through trans-splicing in Caenorhabditis elegans have a trimethylguanosine cap at their 5' termini.

Approximately 10% of the mRNAs in the nematode Caenorhabditis elegans mature through a trans-splicing mechanism that involves the transfer of a 22-nucleotide spliced leader to the 5' end of the pre-mRNA. The spliced leader RNA exists as a small nuclear ribonucleoprotein particle and has the trimethylguanosine cap that is characteristic of eucaryotic small nuclear RNAs. We found that the trimethylguanosine cap present on the spliced leader RNA was transferred to the pre-mRNA during the trans-splicing reaction. Thereafter, the trimethylguanosine cap was maintained on the mature mRNA. This is the first example of eucaryotic cellular mRNAs possessing a trimethylguanosine cap structure.

Animals↗
PubMed1989

Wild-type and mutant actin genes in Caenorhabditis elegans.

We have sequenced the four actin genes of Caenorhabditis elegans. These four genes encode typical invertebrate actins and are highly homologous, differing from each other by, at most, three amino acid residues. As a first step toward an understanding of the developmental regulation of this gene set we have also sequenced mutant actin genes. The mutant genes were cloned from two independent revertants of a single dominant actin mutant. For both revertants, reversion was accompanied by an actin gene rearrangement. The accumulation of actin mRNA during development in these two revertants is different from that of wild-type animals. We present here a correlation between actin gene structure and expression in wild-type and mutant animals. The results, suggest that co-ordinate regulation of actin genes is not essential for wild-type muscle function. In addition, it appears that changes in the 3' region of at least one of the actin mRNA may affect its steady-state regulation during development.

Actins↗
PubMed1989

Sequence comparisons of developmentally regulated collagen genes of Caenorhabditis elegans.

Collagen genes col-6, col-7 (partial), col-8, col-14 and col-19 from the nematode Caenorhabditis elegans were sequenced, and compared to the previously sequenced genes col-1 and col-2. The genes are between 1.0 and 1.2 kb in length, and each includes one or two short introns. The presumptive promoter regions contain sequences similar to the eukaryotic TATA promoter element. Two distinct, conserved sequences were found in the presumptive promoter regions of, respectively, the dauer larva-specific genes col-2 and col-6, and the primarily adult-specific genes col-7 and col-19. The domain structures of the collagen polypeptides are similar: each polypeptide contains two triple-helix forming (Gly-X-Y)n domains, one of 30-33 amino acids (aa), and the other of 127-132 aa. The latter domain is interrupted by one to three short (2-8 aa) non-(Gly-X-Y)n segments that occur at relatively conserved locations in each polypeptide. Sets of cysteine residues flank the (Gly-X-Y)n domains in all of the polypeptides. The genes can be placed into three families based upon amino acid sequence similarities. Genes within a family do not always exhibit similar developmental expression programs, suggesting that structural and regulatory regions of the genes have evolved separately. The codon usage in the genes is highly asymmetrical, with adenine appearing in the third position of 85% of the glycine codons, and 93% of the proline codons.

Amino Acid Sequence↗
PubMed1989

A second trans-spliced RNA leader sequence in the nematode Caenorhabditis elegans.

In the nematode Caenorhabditis elegans, the 22-nucleotide RNA sequence called the spliced leader (SL) is trans-spliced from the 100-nucleotide-long SL RNA to some mRNAs. We have identified a trans-spliced leader (SL2) whose sequence differs from that of the original spliced leader (SL1), although both are 22 nucleotides long. By primer-extension sequencing, SL2 but not SL1 was shown to be present at the 5' end of the mRNA encoded by one of the four glyceraldehyde-3-phosphate dehydrogenase genes. The other three glyceraldehyde-3-phosphate dehydrogenase genes encode mRNAs that have the SL1 but not the SL2 sequence at their 5' ends. Therefore, the trans-splicing process can discriminate the transfer of SL1 from that of SL2 in a gene-specific manner.

Animals↗
PubMed1988

Trans-spliced leader RNA exists as small nuclear ribonucleoprotein particles in Caenorhabditis elegans.

Maturation of some messenger RNAs in the nematode Caenorhabditis elegans involves the acquisition of a 22-base leader at their 5' ends. This 22-base leader, called the spliced leader (SL), is derived from the 5' end of a precursor RNA of 90-100 bases, called spliced leader RNA (SL RNA). SL RNA is transcribed from a 1-kilobase DNA repeat which also encodes the 5S ribosomal RNA. A subset of mRNAs in C. elegans acquire SL from SL RNA by a trans-splicing mechanism. SL behaves as a 5' exon in the trans-splicing reaction. Using antisera against the Sm antigen that is associated with small nuclear ribonucleoprotein particles (snRNPs), we precipitated SL RNA from extracts of C. elegans, indicating that it is bound by the Sm antigen in vivo. SL RNA also possesses the unique trimethylguanosine (m32,2,7G) cap characteristic of most small nuclear RNAs. Therefore, SL RNA is a chimaeric molecule, made up of an snRNA attached to a 5' exon and is a constituent of a snRNP.

Animals↗
PubMed1988

Trans splicing involves a novel form of small nuclear ribonucleoprotein particles.

The trans-splicing reaction occurring in trypanosomes and related species as well as in the nematode Caenorhabditis elegans involves the transfer of a 5' exon from a spliced leader transcript (SL RNA) to a precursor messenger RNA transcript with a 3' splice acceptor site. This seems to take place in the same nuclear compartment as normal cis splicing and proceeds through Y-branched intermediates analogous to the lariats formed in cis splicing. The cellular machinery catalysing cis and trans splicing might therefore be expected to share some components, particularly in the nematode where some mRNAs are produced by both cis and trans splicing. We generated possible secondary structures for the SL RNAs of several species and found they were remarkably similar although neither nucleotide sequence nor length is conserved. Each contained three stem-loops; strikingly the 5' splice site is adjacent to the turn of the most 5' loop and an Sm-binding consensus sequence is found between the second and third stem-loops. Sm is an antigen associated with small nuclear ribonucleoprotein particles (snRNPs). When incubated in HeLa cell nuclear extracts, SL RNAs become immunoprecipitable by anti-Sm, but not by other autoantibodies directed against proteins of mammalian snRNPs. We propose that SL RNAs have a dual function in the trans splicing process: they consist of a 5' exon covalently linked to an snRNA-like sequence and seem likely to exist as Sm snRNP particles (SL snRNPs) within the cell. Just as the RNA in the U1 snRNP base-pairs with the 5' splice site, rendering it susceptible to attack in the cis-splicing reaction, so might the SL snRNP autonomously activate its own 5' splice site and thereby eliminate the need for a U1-like snRNP in the trans-splicing machinery.

Animals↗
PubMed1988

Presence of the Caenorhabditis elegans spliced leader on different mRNAs and in different genera of nematodes.

Several different mRNAs from Caenorhabditis elegans contain the same 22-nucleotide leader sequence at their 5' ends that is acquired in a trans-splicing reaction. About 10 to 15% of the major proteins are translated from mRNAs that contain the spliced leader, among them two ribosomal proteins, ubiquitin, GAPDH, a heat shock protein (hsp70a), and three actins. The same spliced leader sequence is present in mRNAs isolated from nematodes from several different genera; but it is not present in mRNAs from other organisms. The spliced leader is encoded as a spliced leader (SL) RNA about 100 nucleotides long. The gene for the SL RNA is located in the 5S rDNA repeat in C. elegans; however, this association with the 5S repeat is not preserved in other genera. The 22-nucleotide spliced leader sequence is conserved in three genera of nematodes.

Actins↗
PubMed1987

A trans-spliced leader sequence on actin mRNA in C. elegans.

While determining the 5' ends of C. elegans actin mRNAs, we have discovered a 22 nucleotide spliced leader sequence. The leader sequence is found on mRNA from three of the four nematode actin genes. The leader also appears to be present on some, but not all, nonactin mRNAs. The actin mRNA leader sequence is identical to the first 22 nucleotides of a novel 100 nucleotide RNA transcribed adjacent, and in the opposite orientation, to the 5S ribosomal gene. The evidence suggests that the actin mRNA leader sequence is acquired from this novel nucleotide transcript by an intermolecular trans-splicing mechanism.

Actins↗
PubMed1987

Expression of chimeric genes in Caenorhabditis elegans.

We have shown the expression of transformed genes in the nematode Caenorhabditis elegans using a new gene fusion system. Vectors consisting of the flanking regions of a collagen gene (col-1) or a major sperm protein gene of C. elegans fused to the Escherichia coli uidA gene, encoding beta-glucuronidase, were microinjected into worms and found to be propagated as high-copy extrachromosomal tandem arrays. We have detected beta-glucuronidase activity in transformed lines, and have shown that the activity is dependent upon the correct reading frame of the construction and on the presence of the worm sequences. The enzyme activity was shown to be encoded by the chimeric beta-glucuronidase gene by co-segregation analysis and by inactivation with specific antisera. Expression is at a very low level, and seems to be constitutive. We have used histochemical techniques to visualize the enzyme activity in embryos.

Animals↗
PubMed1986

Two loci required for cytoplasmic organization in early embryos of Caenorhabditis elegans.

We have identified five new alleles, including an amber allele, at each of two loci (zyg-11 II and zyg-9 II) previously identified by temperature-sensitive strict maternal-effect lethal mutations. Genetic analysis indicates that each of these genes is expressed specifically during oogenesis and encodes a protein product whose function is required only during embryogenesis. Temperature-pulse experiments suggest that the time of action of both products is during the one-cell stage of embryogenesis. Phenotypic analysis reveals that mutations in both loci lead to disorganization of the cytoplasm in early embryos and to abnormalities in at least one of the meiotic divisions. Mutations at the zyg-9 locus appear to specifically affect microtubule function in one-cell embryos while zyg-11 mutations affect many cytoplasmic properties.

Alleles↗