Published Papers - Ken Sahara

Molecular cloning and chromosomal localization of the Bombyx Sex-lethal gene.（訳）カイコSxl遺伝子のクローニングとマッピング

Niimi T, Sahara K, Oshima H, Yasukochi Y, Ikeo K, Traut W

Genome   49 ( 3 ) 263 - 268   2006.03  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

We cloned Bm-Sxl, an orthologue of the Drosophila melanogaster Sex-lethal (Sxl) gene from embryos of Bombyx mori. The full-length cDNAs were of 2 sizes, 1528 and 1339 bp, and were named Bm-Sxl-L and Bm-Sxl-S, respectively. Bm-Sxl-L consists of 8 exons and spans more than 20 kb of genomic DNA. The open reading frame (ORF) codes for a protein 336 amino acids in length. Bm-Sxl-S is a splice variant that lacks the second exon. This creates a new translation start 138 nucleotides downstream and an ORF that codes for 46 amino acids fewer at the N-terminus. Linkage analysis using an F2 panel mapped Bm-Sxl to linkage group 16 at 69.8 cM. We isolated 2 BACs that include the Bm-Sxl gene. With BAC-FISH we located Bm-Sxl cytogenetically on the chromosome corresponding to linkage group 16 (LG16) at position >68.8 cM.

Phylogeny of the sex determining gene Sex-lethal in insects.（訳）昆虫性決定遺伝子Sxlの系統関係

Traut W, Niimi T, Ikeo K, Sahara K

Genome   49 ( 3 ) 254 - 262   2006.03  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

SXL gene has acquired a pivotal role in the sex-determining pathway of Drosophila, although it does not act as a sex determiner in non-drosophilids. The SXL protein has moderately conserved N- and C-terminal regions and a well-conserved central region including 2 RNA recognition motifs. Our phylogenetic analysis shows that a single orthologue of the Drosophila Sex-lethal (Sxl) gene is present in the genomes of the malaria mosquito Anopheles gambiae, the honeybee Apis mellifera, the silkworm Bombyx mori, and the red flour beetle Tribolium castaneum. The D. melanogaster, D. erecta, and D. pseudoobscura genomes, however, contain 2 paralogous genes, Sxl and CG3056, which are orthologous to the Anopheles, Apis, Bombyx, and Tribolium Sxl. Hence, a duplication in the fly clade generated Sxl and CG3056.

Expression of Autographa californica multiple nucleopolyhedrovirus genes in mammalian cells and Upregulation of the host beta-actin gene.（訳）哺乳細胞における昆虫ウイルスAcMNPV遺伝子発現はβアクチン遺伝子発現を上昇させる

Fujita R, Matsuyama T, Yamagishi J, Sahara K, Asano S, Bando H

Journal of Virology   80 ( 5 ) 2390 - 2395   2006.03  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

The gene expression of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) was examined in two types of mammalian cells, human HeLa14 and hamster BHK cells. DNA microarray analysis followed by reverse transcription-PCR identified at least 12 viral genes transcribed in both HeLa14 cells and BHK cells inoculated with AcMNPV. 5' rapid amplification of cDNA ends was carried out to examine the transcriptional fidelity of these genes in HeLa14 cells. The transcription of ie-1, ie-0 and gp64 was initiated at a baculovirus early gene motif, CAGT, accompanied by a TATA motif. In addition, the same splicing observed for ie-0 mRNA in Sf9 cells occurred in HeLa14 cells. While the transcription initiation sites for pe38 and p6.9 were not located in the CAGT motif, most of them were in a typical eukaryotic RNA polymerase II promoter structure (a conventional TATA motif and/or an initiator).

Partial deletions of the W chromosome due to reciprocal translocation in the silkworm Bombyx mori.（訳）相互転座によるカイコW染色体の一部欠失

Abe H, Seki M, Ohbayashi F, Tanaka N, Yamashita J, Fujii T, Yokoyama T, Takahashi M, Banno Y, Sahara K, Yoshido A, Ihara J, Yasukochi Y, Mita K, Ajimura M, Suzuki MG, Oshiki T and Shimada T

Insect Molecular Biology   14 ( 4 ) 339 - 352   2005.08  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

In this study, we analysed the W chromosomal regions of the Zebra-W strain (T(W;3)Ze chromosome) and the Black-egg-W strain (T(W;10)+(w-2) chromosome) at the molecular level. Our results strongly indicate that the regions containing the W-Samurai and W-Mikan RAPD markers or the W-Mikan RAPD marker were deleted in the T(W;3)Ze and T(W;10)+(w-2) chromosomes, respectively, due to reciprocal translocation between the W chromosome and the autosome. This deletion apparently does not affect the expression of Fem; therefore, this deleted region of the W chromosome does not contain the putative Fem gene.

Resolution of sex chromosome constitution by genomic in situ hybridization and fluorescence in situ hybridization with (TTAGG)n telomeric probe in some species of Lepidoptera.（訳）GISHとテロメアFISHを組み合わせた鱗翅目昆虫の性染色体構成判定

Yoshido A, Marec F and Sahara K

Chromosoma   114 ( 3 ) 193 - 202   2005.07  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

We have developed a simple method to resolve the sex chromosome constitution in females of Lepidoptera by using a combination of genomic in situ hybridization (GISH) and fluorescence in situ hybridization with (TTAGG)( n ) telomeric probe (telomere-FISH). In pachytene configurations of sex chromosomes, GISH differentiated W heterochromatin and telomere-FISH detected the chromosome ends. With this method we showed that Antheraea yamamai has a standard system with a fully differentiated W-Z sex chromosome pair. In Orgyia antiqua, we confirmed the presence of neo-W and neo-Z chromosomes, which most probably originated by fusion of the ancestral W and Z with an autosome pair. In contrast to earlier data, Orgyia thyellina females displayed a neo-ZW(1)W(2) sex chromosome constitution. The combination of GISH and telomere-FISH enabled us to acquire not only reliable information about sex chromosome constitution but also an insight into sex chromosome evolution in Lepidoptera.

Inbreeding depression on female fecundity by genetic factors retained in small population of a male-haploid social mite.（訳）雄単数社会性ハダニの小さな個体群に認められた遺伝的要因による雌造卵数の近交弱性

Mori K, Saito Y, Sakagami T, Sahara K

Experimental and Applied Acarology   36 ( 43832 ) 15 - 23   2005.05  [Refereed]

International Conference Proceedings  Multiple authorship

We previously determined that certain recessive genes decrease female fecundity in a haplo-diploid spider mite, Stigmaeopsis miscanthi (Saito). However, whether the depression was caused by the breakdown of heterosis or the expression of deleterious genes retained in a population could not be determined, because we had started our inbreeding experiment from a mixture of two isolated populations. In order to answer this basic question, inbreeding effects on survival and fecundity were measured for eight small populations occurring far from the two initial populations. There was little depression of immature survival of inbred lineages in all populations. On the other hand, in two inbred lineages, both originating from the smallest populations, female oviposition decreased significantly with the increase of Wrights f-value, showing that mildly deleterious genes are actually retained even in natural populations of haplo-diploid organisms.

Enhancement of cauliflower mosaic virus 35S promoter in insect cells infected with baculovirus.（訳）核多核体病ウイルスに感染した昆虫細胞では植物ウイルスCMVの35Sプロモーター活性が上昇する

Abe T, Miyake N, Nishijima Y, Fujita R, Sahara K, Asano S, Bando H

Virus Research   112 ( 43832 ) 38 - 41   2005.04  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

We happened to discover that the cauliflower mosaic virus (CaMV) 35S promoter inserted into a recombinant Autographa californica multicapsid nucleopolyhedrovirus (rAcMNPV) was strongly activated during the replication of the recombinant virus in Spodoptera frugiperda (Sf9) cells. The expression of the luciferase gene from the 35S promoter in rAcMNPV was remarkably increased late in infection and was resistant to alpha-amanitin treatment. Primer extension indicated that transcriptional initiation from the 35S promoter in Sf9 cells occurred within one of the two baculoviral late promoter TAAG motifs located in the vicinity of the transcription start site in plant cells. These observations suggested that the CaMV 35S promoter served as a transcription start site for AcMNPV-induced RNA polymerase.

The Bombyx mori karyotype and the assignment of linkage groups.（訳）カイコにおけるカリオタイプと連関地図への統合

Yoshido A, Bando H, Yasukochi Y, Sahara K

Genetics   170   675 - 685   2005.03  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

Lepidopteran species have a relatively high number of small holocentric chromosomes (Bombyx mori, 2n = 56). Chromosome identification has long been hampered in this group by the high number and by the absence of suitable markers like centromere position and chromosome bands. In this study, we carried out fluorescence in situ hybridization (FISH) on meiotic chromosome complements using genetically mapped B. mori bacterial artificial chromosomes (BACs) as probes. The combination of two to four either green or red fluorescence-labeled probes per chromosome allowed us to recognize unequivocally each of the 28 bivalents of the B. mori karyotype by its labeling pattern. Each chromosome was assigned one of the already established genetic linkage groups and the correct orientation in the chromosome was defined. This facilitates physical mapping of any other sequence and bears relevance for the ongoing B. mori genome projects.

Organization of the Hox gene cluster of the silkworm, Bombyx mori: a split of the Hox cluster in a non-Drosophila insect.（訳）カイコにおけるHOX遺伝子クラスター：非ショウジョウバエ昆虫におけるHOXクラスターの分断

Yasukochi Y, Ashakumary LA, Wu C, Yoshido A, Nohata J, Mita K, Sahara K

Development Genes and Evolution   214 ( 12 ) 606 - 614   2004.10  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

Yasukochi Y, Ashakumary LA, Wu C, Yoshido A, Nohata J, Mita K and Sahara K (2004): Organization of the Hox gene cluster of the silkworm, Bombyx mori: a split of the Hox cluster in a non-Drosophila insect. Dev. Genes Evol. 214 (12), 606-614.

Use of RNAi technology to confer enhanced resistance to BmNPV on transgenic silkworms.（訳）BmNPVへの耐性強化を目指したトランスジェニックカイコにおけるRNAi技術の応用

Isobe R, Kojima K, Matsuyama T, Quan G-X, Kanda T, Tamura T, Sahara K, Asano S-I, Bando H

Archives of Virology   149 ( 10 ) 1931 - 1940   2004.10  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

Roles of actin networks in peristaltic squeezing of sperm bundles in Bombyx mori.（訳）カイコ精子束のスクイージングにおけるアクチンネットワークの役割

Sahara K and Kawamura N

Journal of Morphology   259 ( 1 ) 1 - 6   2004.01  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

W-derived BAC probes as a new tool for identification of the W chromosome and its aberrations in Bombyx mori.（訳）W由来のBACプローブはカイコにおけるW染色体とW染色体変異を特定する新たなツールである

Sahara K, Yoshido A, Kawamura N, Ohnuma A, Abe H, Mita K, Oshiki T, Shimada T, Asano S, Bando H, Yasukochi Y

Chromosoma   112 ( 1 ) 48 - 55   2003.06  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

Application of artificial insemination technique to eupyrene and/or apyrene sperm in Bombyx mori.（訳）人工授精によるカイコの有核と無核精子の機能解析

Sahara K and Takemura Y

Journal of Experimental Zoology Part A-Comparative Experimental Biology   297A ( 2 ) 196 - 200   2003.06  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

Moth sex chromatin probed by comparative genomic hybridization (CGH).（訳）CGHによるガ類Wクロマチンの比較

Sahara K, Marec F, Eickhoff U, Traut W

Genome   46 ( 2 ) 339 - 342   2003.04  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

Function analysis of an immediate early gene, ie1, of Bombyx mori nucleopolyhedrovirus in mammalian cells.（訳）哺乳細胞におけるBmNPVのie1遺伝子機能解析

Matsuyama T, Asano S, Sahara K, Bando H

Journal of Insect Biotechnology and Sericology   72 ( 2 ) 87 - 94   2003.01  [Refereed]

International Conference Proceedings  Multiple authorship

Glucose and ecdysteroid increase apyrene sperm production in in vitro cultivation of spermatocysts of Bombyx mori.（訳）グルコースもしくはエクダイステロイド添加培養はカイコ無核精子の生産を増加させる

Kawamura N, Sahara K, Fugo H

Journal of Insect Physiology   49 ( 1 ) 25 - 30   2003.01  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

Use of an N-terminal half truncated IE1 as an antagonist of IE1, an essential regulatory protein in baculovirus.（訳）バキュウロウイルスの必須調節因子であるIE1のアンタゴニストとしてのN末端部位の利用

Yamada Y, Matsuyama T, Quan GX, Kanda T, Tamura T, Sahara K, Asano S, Bando H

Virus Research   90 ( 43832 ) 253 - 261   2002.12  [Refereed]

Bulletin of University, Institute, etc.  Multiple authorship

Differences in diapause attributes between two forms distinguished by male-to-male aggression in a subsocial spider mite, Schizotetranychus miscanthi Saito.

Saito Y, Sakagami T, Sahara K

Ecological Research   17 ( 6 ) 645 - 653   2002.10  [Refereed]

International Conference Proceedings  Multiple authorship

In vitro cultivation of spermatocysts to matured sperm in the silkworm, Bombyx mori.（訳）カイコ精母細胞から精子への体外培養

Kawamura N and Sahara K

Developmet Growth and Differentiation   44 ( 4 ) 273 - 280   2002.08  [Refereed]

International Conference Proceedings  Multiple authorship

Cloning and expression of novel crystal protein genes cry39A and 39orf2 from Bacillus thuringiensis subsp. aizawai Bun1-14 encoding mosquitocidal proteins.（訳）Bacillus thuringiensis subsp. aizawai Bun1-14の持つ殺蚊性結晶タンパク質からの新規cry39Aと39orf2のクローニングと発現

Ito T, Sahara K, Bando H, Asano S

Journal of Insect Biotechnology and Sericology   71 ( 3 ) 123 - 128   2002.05  [Refereed]

International Conference Proceedings  Multiple authorship