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Biomedical subjects

T Furuichi

Publications and source records attributed to T Furuichi.

103 records · Page 6Linked to original sources
PubMed1987

The fifth exon of the myelin proteolipid protein-coding gene is not utilized in the brain of jimpy mutant mice.

The jimpy mouse, an X-linked recessive dysmyelinating and demyelinating mutant, has been shown to contain abnormal myelin proteolipid protein (PLP) mRNA. To understand the molecular basis of the mutation, we analyzed the structure of PLP mRNA by an RNase-mapping procedure, using the probes specific to each exon of the mouse PLP gene. We found that the fifth exon of the PLP gene is not utilized in the jimpy.

Animals↗
PubMed1986

Highly mobile DNA segment of IncI alpha plasmid R64: a clustered inversion region.

When R64 DNA was digested with EcoRI, two DNA fragments not equimolar to the plasmid DNA were produced. A DNA region including these fragments was cloned (pKK009), and the pKK009 DNA sample was found to be a mixture of six or more DNA species with EcoRI, PstI, and AvaI cleavage sites at different positions, suggesting a complex rearrangement of DNA. When a part of the pKK009 DNA was removed by HindIII digestion, 33 different types of plasmids (pKK010-series plasmids) were obtained out of 58 clones tested, but no DNA rearrangement could be observed. On the basis of a comparison of the detailed restriction maps of these pKK010-series plasmids, we propose a model in which four DNA segments invert independently or in groups within the 1.95-kilobase region of R64, so that the arrangements of these four segments change randomly. The fixed pKK010-series plasmid DNA was again rearranged in the presence of R64, indicating that trans-acting gene function may be present to mediate the DNA rearrangement. The gene (tentatively designated as rci) was located on a 4.5-kilobase E9' fragment of R64.

Chromosome Inversion↗
PubMed1985

Functional complementation between the two homologous genes, ops and tps, during differentiation of Myxococcus xanthus.

Protein S is a development-specific protein of Myxococcus xanthus encoded by the tps gene. It has been shown that there are two extensively homologous genes (ops and tps) tandemly repeated in the same direction with a 1.4 kb spacer fragment between them (Inouye et al. 1983). Seven deletion mutants were constructed by removing the ops gene, the tps gene, segments of the spacer sequence or combinations of these regions. The deleted regions were replaced with DNA fragments carrying the Tn5 gene for kanamycin resistance. The effects of deleting different regions on morphological changes and on patterns of protein synthesis during fruiting body formation were examined. The process of fruiting body formation was severely delayed when both the ops and the tps genes were deleted. However, this delay could be suppressed by either the ops gene or the tps gene, individually, although in the latter case, a slight delay was still observed. These results indicate that the ops gene is expressed during fruiting body formation and plays a role in the normal program of M. xanthus differentiation. Furthermore, the role of the ops gene can be complemented by the tps gene. The deletion of the ops and/or tps genes had no effect on glycerol-spore formation.

Bacterial Proteins↗
PubMed1985

Two homologous genes coding for spore-specific proteins are expressed at different times during development of Myxococcus xanthus.

The ops and tps genes of Myxococcus xanthus have ca. 90% DNA and amino acid sequence homology and are in the same orientation separated by a spacer region of only 1.4 kilobases. The products of the two genes were found to cross-react immunologically, and both were capable of Ca2+-dependent self-assembly on the surface of myxospores. However, the ops and tps genes were expressed very differently during the developmental cycle of M. xanthus. The tps gene is induced early during fruiting body formation on a solid surface, and its product, protein S, is made in large quantities (up to 15% of total protein synthesis). When the cells turn into myxospores, protein S is assembled on the outer surface of the spore. We have now also found it in much smaller quantities inside the spores. The ops gene, on the other hand, appears to be induced later in development, after the cells have sporulated, since the ops gene product was found only inside the spores. When an ops gene under the control of a tps gene promoter was inserted into a wild-type strain, the ops gene product was synthesized at the same time as protein S and assembled onto the spore surface.

Bacterial Proteins↗
PubMed1985

Novel one-step cloning vector with a transposable element: application to the Myxococcus xanthus genome.

A new strategy was developed for rapid cloning of genes with a transposon mutation library. We constructed a transposon designated TnV that was derived from Tn5 and consists of the gene coding for neomycin phosphotransferase II as well as the replication origin of an Escherichia coli plasmid, pSC101, flanked by Tn5 inverted repeats (IS50L and IS50R). TnV can transpose to many different sites of DNA in E. coli and Myxococcus xanthus and confers kanamycin resistance (Kmr) to the cells. From the Kmr cells, one-step cloning of a gene which is mutated as a result of TnV insertion can be achieved as follows. Chromosomal DNA isolated from TnV-mutagenized cells is digested with an appropriate restriction enzyme, ligated, and transformed into E. coli cells with selection for Kmr. The plasmids isolated contain TnV in the target gene. The plasmid DNA can then be used as a probe for characterization of the gene and screening of clones from a genomic library. We used this vector to clone DNA fragments containing genes involved in the development of M. xanthus.

Cloning, Molecular↗
PubMed1985

Distribution of multicopy single-stranded DNA among myxobacteria and related species.

Multicopy single-stranded DNA (msDNA) is a short single-stranded linear DNA originally discovered in Myxococcus xanthus and subsequently found in Stigmatella aurantiaca. It exists at an estimated 500 to 700 copies per chromosome (T. Yee, T. Furuichi, S. Inouye, and M. Inouye, Cell 38:203-209, 1984). We found msDNA in other myxobacteria, including Myxococcus coralloides, Cystobacter violaceus, Cystobacter ferrugineus (Cbfe17), Nannocystis exedens, and nine independently isolated strains of M. xanthus. The presence of msDNA in N. exedens would extend its phylogenetic distribution into another family of myxobacteria. Flexibacter elegans, a Cytophaga-like gliding bacteria which may be even more distantly related, also contained an msDNA but at a much lower copy number. msDNA was not detected in closely related strains of the myxobacteria Cystobacter fuscus and C. ferrugineus (Cbfe16 and Cbfe18) and the more distantly related eubacteria Herpetosiphon giganteus, Taxeobacter ocellatus, Lysobacter antibioticus, Lysobacter enzymogenes, Cytophaga johnsonae, Rhodopseudomonas sphaeroides, and Rhodospirillum rubrum. Thus far, msDNA has been found in certain gliding bacteria but not in others.

Cytophaga↗
PubMed1984

Multicopy single-stranded DNA isolated from a gram-negative bacterium, Myxococcus xanthus.

A gram-negative bacterium, Myxococcus xanthus, was found to contain 500 to 700 copies per chromosome of a short single-stranded linear DNA fragment. When this DNA (multicopy single-stranded DNA; msDNA) labeled at the 5' end with kinase was used as a probe against total chromosomal blots, it hybridized to unique high molecular weight bands, which were cloned and sequenced. Labeling of msDNA was also possible using the Klenow fragment of DNA polymerase I as well as terminal deoxynucleotidyl transferase, permitting direct sequencing. The 5' end of msDNA was found to be primed by a short RNA segment. The DNA portion of msDNA consisted of 163 bases. Exact correspondence was seen between the msDNA sequence and the sequence of a chromosomal clone. An elaborate secondary structure is postulated for the msDNA sequence. A similar satellite DNA was also found in another myxobacterium, Stigmatella aurantiaca.

Base Sequence↗
PubMed1984

Effects of deletion of the gene for the development-specific protein S on differentiation in Myxococcus xanthus.

A deletion mutation of the gene for protein S (tps), a development-specific protein of Myxococcus xanthus, was constructed. No significant differences in the process of fruiting body formation or the yield of myxospores were observed between mutant and wild-type cells. On the other hand, when the tps gene was deleted together with a 2.0-kilobase sequence including the ops gene immediately upstream of the tps gene, fruiting body formation was substantially delayed, and the yield of myxospores was reduced. These results indicate that protein S is not essential for differentiation of M. xanthus, whereas a gene product(s) coded from the sequence upstream of the tps gene appears to be required for normal fruiting body formation.

Bacterial Proteins↗
PubMed1984

Physical and genetic analyses of the Inc-I alpha plasmid R64.

A 126-kilobase (kb) physical and genetic map of the Inc-I alpha plasmid R64 was constructed by using the restriction enzymes, BamHI, SalI, XhoI, HindIII, and EcoRI. The replication (Rep) and incompatability (Inc) functions of this plasmid were located in a 1.75-kb segment of an EcoRI fragment, E10 (3.3 kb). In addition, the genes determining growth inhibition of phage BF23 (Ibf), suppression of dnaG ( Sog ), resistance to tetracycline (Tetr), and resistance to streptomycin ( Strr ) were located on the 5.5-kb HindIII-XhoI fragment, the 8.1-kb EcoRI fragment (E5), the 4.6-kb HindIII fragment (H8), and the 4.1-kb HindIII fragment (H10), respectively. The map of R64 was compared with that of ColIb, which belongs to the Inc-I alpha group.

Base Composition↗
PubMed1982

Winter range utilization of a Japanese macaque troop in a snowy habitat.

The winter range utilization pattern of a Japanese macaque troop in a snowy habitat was studied. The vegetation areas essential for subsistence were found to be relatively undisturbed mixed and deciduous forests. The concept of essential resource area (ERA) is defined. Our comparison among three troops in the same habitat in the past and present with different population densities indicated that the per capita ERA is quite important in determining the range area. This implies that the population and range area are resource-correlated.

Animals↗
PubMedDate not supplied

A stimulus paradigm inducing long-term desensitization of AMPA receptors evokes a specific increase in BDNF mRNA in cerebellar slices.

Long-term desensitization of AMPA receptors (LTDA) is a core mechanism of long-term depression, a model of motor learning in the cerebellum. In this study we investigated the expression of neurotrophic factor genes after induction of LTDA in cultured cerebellar slices. LTDA was induced by application of quisqualate and monitored as a population response with a wedge recording technique. The levels of mRNA were quantified by reverse transcription followed by polymerase chain reaction. Quisqualate, at a dose and duration that reliably induced LTDA, elicited a significant and specific increase in BDNF mRNA with a peak at four hours after the application. By cell fractionation, the major source of BDNF mRNA increase was found to be in granule cells. In addition, a small but significant increase of transcripts with specific exon usage was observed in a Purkinje cell fraction. These results indicate that BDNF may be coinduced with LTDA and suggest that the slow and sustained increase of BDNF mRNA might play a role in later phases of synaptic plasticity in the cerebellum.

Animals↗