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W F Dove

Publications and source records attributed to W F Dove.

At least 55 records · Page 3Linked to original sources
PubMed1993

Detailed physical and genetic mapping in the region of plasminogen, D17Rp17e, and quaking.

We present here a detailed physical map encompassing over 600 kb of mouse Chromosome (Chr) 17 in the region of plasminogen, D17Rp17e, and quaking. This region is cloned in yeast artificial chromosomes (YACs). We have identified several CpG islands within this region from pulsed field gel mapping of mouse genomic DNA and YAC DNA. Five new DNA probes have been generated. One, D17Leh514, is a minimum of about 90 kb distal to plasminogen. Four, D17Leh513, D17Leh512, D17Leh511, and D17Leh510, are proximal to D17Rp17e, the closest previously described genetic marker to quaking viable and quaking lethal-1 mutations. We have genetically mapped D17Leh511 to within 0.15 cM of these mutations. The genetic distance to D17Rp17e from D17Leh511 is also 0.15 cM; the physical distance of less than 360 kb (minimum 200 kb) is consistent with an approximation of 2 Mbp per cM.

Animals↗
PubMed1993

Mouse models of human phenylketonuria.

Phenylketonuria (PKU) results from a deficiency in phenylalanine hydroxylase, the enzyme catalyzing the conversion of phenylalanine (PHE) to tyrosine. Although this inborn error of metabolism was among the first in humans to be understood biochemically and genetically, little is known of the mechanism(s) involved in the pathology of PKU. We have combined mouse germline mutagenesis with screens for hyperphenylalaninemia to isolate three mutants deficient in phenylalanine hydroxylase (PAH) activity and cross-reactive protein. Two of these have reduced PAH mRNA and display characteristics of untreated human PKU patients. A low PHE diet partially reverses these abnormalities. Our success in using high frequency random germline point mutagenesis to obtain appropriate disease models illustrates how such mutagenesis can complement the emergent power of targeted mutagenesis in the mouse. The mutants now can be used as models in studying both maternal PKU and somatic gene therapy.

Animals↗
PubMed1993

Cloning and characterization of the altA alpha-tubulin gene of Physarum.

A cDNA clone derived from the altA locus, encoding one of several alpha-tubulins in Physarum, was sequenced and used to determine the developmental and cell cycle expression patterns of its corresponding gene. The predicted amino acid sequence of the altA gene product, alpha 1A-tubulin, is 92% identical to the other known Physarum alpha-tubulins, alpha 1B and alpha 2B, which are products of two tightly linked genes at the altB locus. The nucleotide sequence of the altA coding region is 82% identical to the two altB genes. Expression of the altA gene was found in all three cell types examined - amoeba, flagellate and plasmodium - but at substantially different levels in each. The peak level of altA message detected in flagellates was 14-fold higher than in amoebae, while the peak level in plasmodia was 5-fold lower than in amoebae. The expression pattern of altA and the predicted amino acid sequence of the alpha-tubulin it encodes suggest that alpha 1A is the substrate for post-translational acetylation, giving rise to the alpha 3-tubulin isoform found specifically in amoebae and flagellates. Northern blot analysis of plasmodial RNA samples from specific times in the cell cycle showed that the level of altA message varies over the cell cycle in a pattern similar to transcripts from other tubulin genes, with a peak at mitosis and little or no message detected during most of interphase.

Amino Acid Sequence↗
PubMed1993

Two alleles of a developmentally regulated alpha-tubulin locus in Physarum polycephalum replicate on different schedules.

The replication timing of a pair of natural alleles was compared at two alpha-tubulin loci of the Physarum plasmodium. Taking advantage of the naturally synchronous cell cycle of nuclei within the syncytial plasmodium, we analyzed the replication schedule of specific DNA fragments to a resolution of 10-min intervals within a 3-h S phase. At this level of resolution, differences in replication timing between polymorphic alleles at the same locus can be detected in a heterozygote. Specifically, the 3' region of the altA1 allele completes replication at between 20 and 40 min of S phase. The same region of the altA2 allele completes replication at between 40 and 80 min of S phase. In contrast, both alleles at the altB locus replicate concurrently within the first 10 to 15 min of S phase. Previous studies showed that both altA and altB are expressed in the plasmodium, their message levels peaking at mitosis, just minutes before the onset of S phase. However, altB message is detected at substantially higher levels than altA message on Northern (RNA) blots. The temporal windows over which the altA alleles each replicate are very broad in comparison with the levels of mitotic synchrony and altB replication synchrony in a single plasmodium. The allele-specific replication schedule of the altA locus demonstrates that the temporal organization of replicons is not strictly conserved between homologous chromosomes.

Alleles↗
PubMed1992

Multiple intestinal neoplasia caused by a mutation in the murine homolog of the APC gene.

Germ-line mutations of the APC gene are responsible for familial adenomatous polyposis (FAP), an autosomal dominantly inherited disease in humans. Patients with FAP develop multiple benign colorectal tumors. Recently, a mouse lineage that exhibits an autosomal dominantly inherited predisposition to multiple intestinal neoplasia (Min) was described. Linkage analysis showed that the murine homolog of the APC gene (mApc) was tightly linked to the Min locus. Sequence comparison of mApc between normal and Min-affected mice identified a nonsense mutation, which cosegregated with the Min phenotype. This mutation is analogous to those found in FAP kindreds and in sporadic colorectal cancers.

Adenomatous Polyposis Coli↗
PubMed1992

Transient expression in Physarum of a chloramphenicol acetyltransferase gene under the control of actin gene promoters.

We cloned and sequenced two actin promoters from Physarum, and constructed plasmids carrying these promoters upstream of a bacterial chloramphenicol acetyltransferase (cat) gene. We then tested the plasmids for their ability to express cat in Physarum amoebae. We present reliable methods for introducing plasmid DNA into Physarum amoebae by electroporation, and show that expression of the cat gene in amoebae occurs in the presence, but not the absence, of one or the other Physarum actin promoter.

Actins↗
PubMed1992

Cellular and molecular analysis of plasmodium development in Physarum.

The development of an amoeba into a plasmodium involves extensive changes in cellular organisation and gene expression. The genetic basis of a number of recessive mutations that block plasmodium development has been elucidated. The stage at which development becomes abnormal has been determined for all the mutants, as has the terminal phenotype. In order to investigate the changes in gene expression that accompany plasmodium development, a cDNA library has been made using RNA isolated from cell populations in which development was occurring.

Animals↗
PubMed1992

The Min (multiple intestinal neoplasia) mutation: its effect on gut epithelial cell differentiation and interaction with a modifier system.

Min is a fully penetrant dominant mutation that leads to the development of multiple intestinal adenomas throughout the duodenal-to-colonic axis. Min/+ C57BL6/J mice have an average life-span of 120 d. Multi-label immunocytochemical studies of these lesions demonstrate patches of differentiated enterocytes, and scattered enteroendocrine, goblet and Paneth cells. Expression of endogenous marker genes within these differentiated cells can be directly correlated with the position occupied by the adenoma along the duodenal-to-colonic axis and mirrors the regional differentiation of the normal gut epithelium. The presence of multiple lineages in adenomas together with their retention of spatial information suggests that tumorigenesis in Min/+ mice may be initiated in a multipotent stem cell normally located at the base of intestinal crypts. To study the time-dependent properties of these tumors, genetic conditions were sought in which Min/+ animals could survive for up to 300 d. Min is fully penetrant in hybrids with either AKR/J or MA/MyJ. However, the hybrids demonstrate a reduction in the number of intestinal adenomas. Preliminary backcross analysis is consistent with a single major modifier locus unlinked to Min in both the AKR/J and MA/MyJ strains. The increased lifespan of the hybrid animals is also associated with the development of invasive tumors. New tumors do not arise continuously over the lifespan of these animals; instead all adenomas appear to be established by 100 d of age or sooner. These studies indicate that the Min/+ mouse is a powerful model system for analyzing the mechanisms that establish and maintain a balance between proliferation and differentiation in the continuously renewing gut epithelium and for an assessment of the multi-step hypothesis of intestinal neoplasia.

Adenoma↗
PubMed1992

Preferential expression of one beta-tubulin gene during flagellate development in Physarum.

The microbial eukaryote Physarum polycephalum displays several distinct cell types in its life cycle, including amoebae, flagellates and plasmodia. Despite its relative simplicity, Physarum has a tubulin gene family of complexity comparable to that of Drosophila. We have identified beta-tubulin cDNAs from Physarum that are derived from the betA beta-tubulin locus and encode beta 1A tubulin. We have also identified a partial cDNA for the unlinked betB beta-tubulin gene, which encodes beta 1B tubulin. The polypeptide sequences encoded by betA and betB show 99% identity, but the nucleotide sequences show only 85% identity, consistent with an ancient duplication of these genes. The betB gene is expressed in amoebae, flagellates and plasmodia, whereas betA is expressed only in amoebae and flagellates. During the amoeba-flagellate transition the level of betA transcript increases over 100-fold, while the level of betB transcript changes very little. Thus Physarum has a mechanism for regulating the level of discrete beta-tubulin transcripts differentially during flagellate development. A need for this differential regulation could account for the maintenance of the virtually isocoding betA and betB beta-tubulin genes.

Amino Acid Sequence↗
PubMed1991

Meiotic mapping of murine chromosome 17: the string of loci around l(17)-2Pas.

We describe a genetic analysis of l(17)-2Pas, an embryonic lethal mutation on murine chromosome 17. Males transmitted the l(17)-2 allele to only 38% of their offspring, whereas females transmitted this allele at 50%. Two-point crosses revealed tight linkage between l(17)-2 and brachyury (T), and deletion mapping placed l(17)-2 outside of the hairpin-tail deletion (Thp). To map this mutation more precisely, we intercrossed hybrid mice that carry distinct alleles at many classical and DNA loci on chromosome 17 and obtained 172 animals recombinant in the T to H-2 region. Strong positive interference was observed over the 14 cM interval from T to H-2K. Thus, a single recombinant can be informative; one such recombinant places l(17)-2 distal of the molecular marker D17Leh66D. Robust genetic maps can be constructed with multilocus crosses that share anchor loci. DNA markers can be interpolated onto these maps retrospectively.

Animals↗
PubMed1991

Pleiotropic action of the murine quaking locus: structure of the qkv allele.

The spontaneous allele quakingviable (qkv) exerts effects on myelination and spermiogenesis. The defects generated by qkv were not separated in a multilocus mapping cross that provided a mapping resolution of 0.1 centiMorgans (cM). Furthermore, no distortions suggestive of a large chromosomal anomaly associated with qkv were apparent. One plausible interpretation is that the quaking locus contains more than one functional domain, either organized into overlapping genes or expressed by alternative splicing mechanisms. The cloning needed to analyze this locus will be enhanced by the very high resolution of the meiotic mapping cross reported here. The recombinational distances on this qkv map were compressed compared with those previously reported in a high-resolution map for qkl-1, an embryonic lethal allele of quaking induced by ethylnitrosourea. Additional crosses confirmed prior reports that the sex and the genetic background of the heterozygous parent can affect recombinational distances. These joint effects on recombination are strong enough to account for the discrepancy between the two maps. This variability of two-factor map values leads to the preferred multilocus map-building protocol discussed in the accompanying paper.

Animals↗
PubMed1991

Fission yeast promoter-probe vectors based on hygromycin resistance.

We have constructed fission yeast vectors that carry either complete or 5'-truncated alleles of the hph gene, encoding hygromycin B phosphotransferase. We show that plasmid-borne hph can be expressed in fission yeast to confer hygromycin resistance. The vectors permit selection or screening in fission yeast for promoter activity of DNA fragments from other species. We used the vectors to identify several genomic sequences from Physarum that provide promoter function in fission yeast.

Base Sequence↗
PubMed1991

Variable pathways for developmental changes of mitosis and cytokinesis in Physarum polycephalum.

The development of a uninucleate ameba into a multinucleate, syncytial plasmodium in myxomycetes involves a change from the open, astral mitosis of the ameba to the intranuclear, anastral mitosis of the plasmodium, and the omission of cytokinesis from the cell cycle. We describe immunofluorescence microscopic studies of the amebal-plasmodial transition (APT) in Physarum polycephalum. We demonstrate that the reorganization of mitotic spindles commences in uninucleate cells after commitment to plasmodium formation, is completed by the binucleate stage, and occurs via different routes in individual developing cells. Most uninucleate developing cells formed mitotic spindles characteristic either of amebae or of plasmodia. However, chimeric mitotic figures exhibiting features of both amebal and plasmodial mitoses, and a novel star microtubular array were also observed. The loss of the ameba-specific alpha 3-tubulin and the accumulation of the plasmodium-specific beta 2-tubulin isotypes during development were not sufficient to explain the changes in the organization of mitotic spindles. The majority of uninucleate developing cells undergoing astral mitoses (amebal and chimeric) exhibited cytokinetic furrows, whereas cells with the anastral plasmodial mitosis exhibited no furrows. Thus, the transition from astral to anastral mitosis during the APT could be sufficient for the omission of cytokinesis from the cell cycle. However, astral mitosis may not ensure cytokinesis: some cells undergoing amebal or chimeric mitosis contained unilateral cytokinetic furrows or no furrow at all. These cells would, most probably, fail to divide. We suggest that a uninucleate committed cell undergoing amebal or chimeric mitosis can either divide or else form a binucleate cell. In contrast, a uninucleate cell with a mitotic spindle of the plasmodial type gives rise only to a binucleate cells. Further, the decision to enter mitosis after commitment to the APT is independent of the developmental changes in the organization of the mitotic spindle and cytokinesis.

Cell Division↗
PubMed1990

A dominant mutation that predisposes to multiple intestinal neoplasia in the mouse.

In a pedigree derived from a mouse treated with the mutagen ethylnitrosourea, a mutation has been identified that predisposes to spontaneous intestinal cancer. The mutant gene was found to be dominantly expressed and fully penetrant. Affected mice developed multiple adenomas throughout the entire intestinal tract at an early age.

Adenoma↗