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Comparison of non-mutant and mutant waxy genes in rice and maize.

The waxy gene, which is responsible for the synthesis of amylose in endosperm and pollen, is genetically well characterized in many grasses including maize and rice. Homology between the previously cloned maize waxy gene and the rice gene has facilitated our cloning of a 15-kb HindIII fragment that contains the entire rice gene. A comparison of the restriction maps of the maize and rice genes indicates that many restriction sites within translated exons are conserved. In addition, the rice gene encodes a 2.4-kb transcript that programs the in vitro synthesis of a 64-kD pre-protein which is efficiently precipitated with maize waxy antisera. We demonstrate that these gene products are altered in rice strains containing mutant waxy genes. Southern blot analysis of 16 rice strains, ten containing waxy mutations, reveals that the waxy gene and flanking restriction fragments are virtually identical. These results contrast dramatically with the high level of insertions and deletions associated with restriction fragment length polymorphism and spontaneous mutations among the waxy alleles of maize.

Alleles↗

Phi SC623, a temperate actinophage of Streptomyces coelicolor Müller, and its relatives phi SC347 and phi SC681.

Three species-specific, temperate actinophages of Streptomyces coelicolor Müller, phi SC623, phi SC347 and phi SC681, were compared with respect to host range, virion structure, antiserum cross-inactivation, DNA-restriction pattern, DNA hybridization, and DNA base composition. The restriction map of phi SC623 (57 kb) was established with eight restriction enzymes; the homologies of this phage with phi SC347 and phi SC681 suggested that it might be a hybrid phage composed of approximately equal parts homologous to one of the other two phages. No homology was detected between phi SC623 and R4, a temperate, wide-host-range phage which can also lysogenize S. coelicolor Müller.

Bacteriophages↗

Deletion of a 55-kilobase-pair DNA element from the chromosome during heterocyst differentiation of Anabaena sp. strain PCC 7120.

The filamentous cyanobacterium Anabaena sp. strain PCC 7120 produces terminally differentiated heterocysts in response to a lack of combined nitrogen. Heterocysts are found approximately every 10th cell along the filament and are morphologically and biochemically specialized for nitrogen fixation. At least two DNA rearrangements occur during heterocyst differentiation in Anabaena sp. strain PCC 7120, both the result of developmentally regulated site-specific recombination. The first is an 11-kilobase-pair (kb) deletion from within the 3' end of the nifD gene. The second rearrangement occurs near the nifS gene but has not been completely characterized. The DNA sequences found at the recombination sites for each of the two rearrangements show no similarity to each other. To determine the topology of the rearrangement near the nifS gene, cosmid libraries of vegetative-cell genomic DNA were constructed and used to clone the region of the chromosome involved in the rearrangement. Cosmid clones which spanned the DNA separating the two recombination sites that define the ends of the element were obtained. The restriction map of this region of the chromosome showed that the rearrangement was the deletion of a 55-kb DNA element from the heterocyst chromosome. The excised DNA was neither degraded nor amplified, and its function, if any, is unknown. The 55-kb element was not detectably transcribed in either vegetative cells or heterocysts. The deletion resulted in placement of the rbcLS operon about 10 kb from the nifS gene on the chromosome. Although the nifD 11-kb and nifS 55-kb rearrangements both occurred under normal aerobic heterocyst-inducing conditions, only the 55-kb excision occurred in argon-bubbled cultures, indicating that the two DNA rearrangements can be regulated differently.

Chromosome Deletion↗

Molecular biology of the viral haemorrhagic disease virus of rabbits.

Viral haemorrhagic disease virus (VHDV) of rabbits is a small, nonenveloped DNA virus which contains a linear, single-stranded genome approximately 7,000 bases in length. The virions are icosahedral in symmetry, consisting of 180 subunits with pentamer-hexamer clustering. The capsid is composed of four structural polypeptides: VP1:60-61 kDa, VP2:54.7 kDa, VP3:52 kDa, and VP4:26-28 kDa. VP1 is a major structural polypeptide which constitutes approximately 54.7% of the total viral proteins. There are extensive antigenic relationships among the polypeptides. Haemagglutination activity is associated with the intact virions. The genome of the VHDV isolate strain (VHDV-NJ) is partially cloned, and 4.6 kb DNA fragment of restriction mapping has been determined, showing that there are few common restriction sites compared with the restriction site mapping of the parvoviruses. There are five viral-specific mRNA species, each coding for one of the five polypeptides identified by in vitro translation. The cDNA library from viral mRNA has been established. Southern blot hybridisation shows that, to some extent, H-I virus, minute virus of mice, porcine parvovirus and goose parvovirus share homology with VHDV. However, to clarify VHDV taxonomy, further efforts must be directed towards VHDV genome analysis.

Animals↗

[Physical mapping of the Bombyx mori nuclear polyhedrosis virus genome].

The restriction map of the nuclear polyhedrosis DNA virus of Bombyx mori has been determined with the use of four restriction endonucleases: NotI, BamHI, SmaI and KpnI. 18 cleavage sites have been localized on the viral DNA. Total length of the viral DNA is about 130 kb. The fragment containing a polyhedrin gene has been localized on the map by the blot hybridization technique.

Animals↗

Terminal redundancy and circular permutation of mycoplasma virus L3 DNA.

This communication reports the physical map of mycoplasma virus L3 (MV-L3) DNA derived from restriction patterns obtained by digestion with seven different restriction endonucleases. The length of the restriction map is 36,200 bp in contrast to the contour length of native MV-L3 DNA molecules which is 39,400 bp as determined by electron microscopy. The difference in length of 3,200 bp (corresponding to 8.1% of the native viral DNA contour length) is explained by terminal redundancy. It was possible to clone all fragments from particular restriction patterns into Escherichia coli vector pAT153, an indication of circular permutation within a population of MV-L3 DNA. However clear evidence has been obtained from the molar ratios of fragments and from hybridization experiments. We suppose that viral DNA is packaged from a concatemeric precursor molecule starting at a specific site called pac.

Acholeplasma laidlawii↗

Pulsed-field gel mapping of maize mitochondrial chromosomes.

Pulsed-field gel electrophoresis (PFGE) in combination with infrequently cutting restriction enzymes was used to investigate the structure of the mitochondrial (mt) genome of the maize variety Black Mexican Sweet (BMS). The mt genome of this variety was found to resemble that of the closely related B37N variety, with one recombination and five insertion/deletion events being sufficient to account for the differences observed between the two genomes. The majority of the BMS genome is organized as a number of subgenomic chromosomes with circular restriction maps. Several large repeated sequences are found in the BMS mt genome, but not all appear to be in recombinational equilibrium. No molecules large enough to contain the entire mt genome were discernible using these techniques. The mapping approach described here provides a means of quickly analyzing the large and complex mt genomes of plants.

Base Sequence↗

Organization of the human monoamine oxidase genes and long-range physical mapping around them.

A 265-kb yeast artificial chromosome containing sequences for human monoamine oxidase A and B (MAO-A and MAO-B) genes has been characterized. These two genes are localized within a region of about 240 kb and are arranged in a tail-to-tail configuration, with the 3' coding sequences separated by about 50 kb. A region about 2.5 Mb around the MAO loci was mapped by pulsed-field gel electrophoresis (PFGE). Comparisons between the restriction maps derived from the YAC and the long-range map derived from genomic digestions were in general agreement. The important features identified include a CpG island at the 5' end of the MAO-A and MAO-B genes, respectively. The combined information supports the order of markers within this region to be DXS77-DXS7-MAOA-MAOB.

DNA Probes↗

A 5.4-Mb continuous pulsed-field gel electrophoresis map of human 9q34.1 between ABL and D9S114, including the tuberous sclerosis (TSC1) region.

We constructed a long-range restriction map of the tuberous sclerosis (TSC1) region of human chromosome 9q34, extending from ABL (T39-2-2) to D9S114. The physical map includes five genes and seven anonymous markers. The maximum distance between ABL and D9S114 is 5.4 Mb. The TSC1 critical region, between D9S149 and D9S114, has a maximum distance of 2.7 Mb. The ratio of genetic and physical distance in the region is 1 cM:600 kb. We also used Southern blot analysis and a radiation hybrid cell line, E6B, to exclude 3 genes--PBX3A, RXR alpha, and TAN1--from the AK1 to D9S114 interval. This excludes them as disease genes for tuberous sclerosis.

Chromosome Mapping↗

Framework YAC contig anchored into a 3.2-Mb high-resolution physical map in proximal 11q13.

Despite the presence on band q13 of chromosome 11 of a number of genes predisposing individuals to various human diseases, most of this genomic region remains loosely mapped. Moreover, there is a relative dearth of yeast artificial chromosome (YAC) contigs from genome-wide studies: YACs are irregularly distributed over this chromosomal region and have not been arranged into contigs. We have thus undertaken fine-scale mapping of a 3.2-Mb region flanked by ACTN3 and FGF3. Since this region has demonstrated a high degree of YAC instability, we have established a framework contig by anchoring YACs and cosmids into a high-resolution physical map based on fluorescence in situ hybridization and long-range restriction mapping. The 3.2-Mb area studied includes the boundaries of regions thought to contain genes predisposing individuals to osteoporosis-pseudoglioma syndrome and insulin-dependent diabetes mellitus, as well as genes driving amplification events in human carcinomas. Another feature of this genomic area is that it cross-hybridizes to nonsyntenic regions of the genome. In addition, it spans the region where syntenic conservation with mouse chromosome 19 ends, making clones that we have anchored there valuable tools in understanding genome evolution.

Animals↗

A contiguous physical map of the pericentromeric region of chromosome 21q between D21Z1 and D21S13E.

We constructed a long range restriction map of the pericentromeric 21q region between the centromere, identified by the alphoid DNA sequence D21Z1, and D21S13E. The physical map showed the order and intermarker distances of five new loci, including two for which highly informative dinucleotide repeat polymorphisms were identified. The total distance between D21Z1 and D21S13E was 2400 kb. Comparison of genetic and physical distances indicated that there is about 400 to 500 kb per centimorgan that is not significantly different from the average 470 kb per centimorgan for the whole of chromosome 21q. Our physical mapping results do not indicate suppression of recombination in pericentromeric 21q.

Animals↗

Molecular identification and phylogeny of parasitic wasp species (Hymenoptera: Trichogrammatidae) by mitochondrial DNA RFLP and RAPD markers.

Mitochondrial DNA (mtDNA) restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) were tested for their ability to discriminate between seven species of minute parasitic wasps belonging to the genus Trichogramma. They proved to be reliable species-diagnostic molecular markers. Pairwise comparisons of the mtDNA restriction maps revealed considerable differentiation among the seven species. Percentage of common restriction sites ranged from 30% to 83%. Phylogenetic analyses performed either on the mtDNA nucleotide distance matrix or on the matrix of the restriction site-state generated a tree congruent with those based on allozymes and morphology. RAPD procedures also revealed species-specific banding patterns and seem promising for a rapid and easy identification of Trichogramma species. Moreover, for some Trichogramma species, RAPD banding patterns might be informative of the phylogenetic relatedness.

Animals↗

Molecular cloning of a lytic beta-1,3-glucanase gene from Oerskovia xanthineolytica LLG109. A beta-1,3-glucanase able to selectively permeabilize the yeast cell wall.

Molecular cloning of the beta gIII gene encoding for an endo-beta-1,3-glucanase (beta gl II) from Oerskovia xanthineolytica LLG109, a yeast-lytic gram-positive bacterium, has been conducted in order to elucidate its primary sequence and subsequently express it into B. subtilis. This endo-beta-1,3-glucanase exhibits low yeast-lytic activity toward viable S. cerevisiae cells, and it has shown ability to selectively permeabilize the yeast cell wall and release intracellular proteins produced by yeast. Highly degenerate oligonucleotides have been used to PCR-amplify a region of the beta-1,3-glucanase II encoding gene from O. xanthineolytica LLG109. The amplified fragment has been cloned and sequenced. The deduced amino acid sequence contains regions identical to the amino acid sequences previously determined by direct sequencing of the purified enzyme from O. xanthineolytica LLG109. By using the 180-bp PCR product as a homologous probe, we have been able to isolate four positive clones harboring plasmids pPF1A, pPF1B, pPF8A, and pPF9A, respectively, from a partial genomic library from O. xanthineolytica LLG109. All four plasmids contained a 2.7-kb BamHI insert that hybridized to the PCR probe under high stringency conditions. The 2.7-kb fragment seemed to be identical in all four cases regarding preliminary partial restriction mapping analysis done on the four plasmids. The 1.5-kb BamHI/KpnI restriction fragment from pPF8A and pPF9A hybridizing with the 180-bp PCR probe is presently being sequenced. The cloning of the lytic beta-1,3-glucanase from O. xanthineolytica LLG109 expands the number of yeast lytic beta-glucanases so far cloned. The availability of the nucleotide sequences of such a family of genes will allow further understanding of the role and mode of action of these enzymes in yeast cell wall degradation. In addition, a more extensive study on the structure and functional relationships of these enzymes will allow us to engineer "tailor-made" lytic beta-1,3-glucanases for use in new and improved large-scale selective cell permeabilization (SCP) and selective protein recovery (SPR) from yeast cells, not only from S. cerevisiae but also from alternative yeast expression systems such as Hansenula polymorpha, Pichia pastoris, and others, which are becoming of increasing importance in biotechnology.

Amino Acid Sequence↗

Metabolism of dibenzothiophene and naphthalene in Pseudomonas strains: complete DNA sequence of an upper naphthalene catabolic pathway.

From a soil isolate, Pseudomonas strain C18, we cloned and sequenced a 9.8-kb DNA fragment that encodes dibenzothiophene-degrading enzymes. Nine open reading frames were identified and designated doxABDEFGHIJ. Collectively, we refer to these genes as the DOX pathway. At the nucleotide level, doxABD are identical to the ndoABC genes that encode naphthalene dioxygenase of Pseudomonas putida. The DoxG protein is 97% identical to NahC (1,2-dihydroxynaphthalene dioxygenase) of P. putida. DoxE has 37% identity with cis-toluene dihydrodiol dehydrogenase. DoxF is similar to the aldehyde dehydrogenases of many organisms. The predicted DoxHIJ proteins have no obvious sequence similarities to known proteins. Gas chromatography with a flame ionization detector and mass spectroscopy confirmed that the DOX proteins convert naphthalene to salicylate and converting phenanthrene to 1-hydroxy-2-naphthoic acid. doxI mutants convert naphthalene to trans-o-hydroxybenzylidenepyruvate, indicating that the DoxI protein is similar to NahE (trans-o-hydroxybenzylidenepyruvate hydratase-aldolase). Comparison of the DOX sequence with restriction maps of cloned naphthalene catabolic pathway (NAH) genes revealed many conserved restriction sites. The DOX gene arrangement is identical to that proposed for NAH, except that the NAH equivalent of doxH has not been recognized. DoxH may be involved in the conversion of 2-hydroxy-4-(2'-oxo-3,5-cyclohexadienyl)-buta-2,4-dienoat e to cis-o-hydroxybenzylidenepyruvate. doxJ encodes an enzyme similar to NahD (isomerase). Our findings indicate that a single genetic pathway controls the metabolism of dibenzothiophene, naphthalene, and phenanthrene in strain C18 and that the DOX sequence encodes a complete upper naphthalene catabolic pathway similar to NAH.

Amino Acid Sequence↗

Long-range mapping of the calcium release channel and glucosephosphate isomerase loci using pulsed-field gel electrophoresis.

Long range restriction maps of the calcium release channel (CRC) and glucosephosphate isomerase (GPI) loci have been constructed using pulsed field electrophoresis, Southern blotting and CRC- and GPI-specific probes. The maps, deduced from the restriction fragments detected by the probes, covered 1.1 and 0.3 Mb respectively and no overlap between the maps of these closely linked loci was detected. The minimal distance between the GPI and CRC loci was estimated to be at least 500 kb.

Animals↗

Presence of an expressed beta-tubulin gene (TUBB) in the HLA class I region may provide the genetic basis for HLA-linked microtubule dysfunction.

An expressed beta-tubulin gene (TUBB) has previously been localized to chromosome region 6pter-p21 in man. By using a panel of deletion mutant cell lines and radiation-reduced hybrids containing fragments of chromosome 6, the TUBB locus could be mapped to the HLA class I region at 6p21.3. A long range restriction map including TUBB and several HLA class I genes was then generated by rotating field gel electrophoresis. The results show that TUBB maps to a segment 170-370 kb telomeric of HLA-C. This location suggests that a mutation at the TUBB locus could be the cause for certain forms of HLA-linked microtubule dysfunction, including immotile cilia syndrome.

Animals↗

Efficient Cre-lox linearisation of BACs: applications to physical mapping and generation of transgenic animals.

Due to the size of BAC, PAC and P1 clones, it is often difficult to construct detailed restriction maps, with large number of restriction fragments leading to ambiguity of mapping data. We report the use of Cre recombinase to linearise and asymmetrically introduce label at the unique loxP site of large loxP-containing clones. Subsequent partial digestion allows the direct ordering of restriction fragments. Additionally, BAC DNA linearised using the Cre-lox system has been used successfully to generate transgenic animals.

Animals↗