Environmental Factors Controlling Capitulum Opening and Closing of Dandelion, Taraxacum albidum

The capitula of Taraxacum albidum kept in darkness opened whenthe temperature rose. The higher the temperature before thechange and greater the temperature rise, the larger the openingresponse was. The opening was promoted by light. The capitulakept in darkness at 20?1?C opened after exposure to light withoutthe temperature rise. The capitula closed 8–10 h afterthe beginning of the opening under constant light and temperatureconditions. (Received November 8, 1986; Accepted March 13, 1987)     

Patchwork-Type Spontaneous Activity in Neonatal Barrel Cortex Layer 4 Transmitted via Thalamocortical Projections

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Diurnal vertical migration of Gymnodinium mikimotoi during a red tide in Hoketsu Bay, Japan

The depth, velocity and timing of the vertical migration ofGymnodinium mikimotoi were examined using fluorometric fieldobservations. Gymnodinium mikimotoi can migrate vertically {smalltilde}20 m daily at velocities of {small tilde}2.2 m h^–1     

Ordered YAC Clone Contigs Assigned to Rice Chromosomes 3 and 11

Yeast artificial chromosome (YAC) clones were arranged on thepositions of restriction fragment length polymorphism (RFLP)and sequence-tagged site (STS) markers already mapped on thehigh-resolution genetic maps of rice chromosomes 3 and 11. Froma total of 416 and 242 YAC clones selected by colony/Southernhybridization and polymerase chain reaction (PCR) analysis,238 and 135 YAC clones were located on chromosomes 3 and 11,respectively. For chromosomes 3 and 11, 24 YAC contigs and islandswith total coverage of about 46% and 12 contigs and islandswith coverage of about 40%, respectively, were assigned. Althoughmany DNA fragments of multiple copy marker sequences could notbe mapped to their original locations on the genetic map bySouthern hybridization because of a lack of RFLP, the physicalmapping of YAC clones could often assign specific locationsof such multiple copy sequences on the genome. The informationprovided here on contig formation and similar sequence distributionrevealed by ordering YAC clones will help to unravel the genomeorganization of rice as well as being useful in isolation ofgenes by map-based cloning.     

Construction of YAC Contigs on Rice Chromosome 5

A physical map of rice chromosome 5 was constructed with yeastartificial chromosome (YAC) clones along a high-resolution molecularlinkage map carrying 118 DNA markers distributed over 123.7cM of genomic DNA. YAC clones have been identified by colonyand Southern hybridization for 105 restriction fragment lengthpolymorphism (RFLP) markers and by polymerase chain reaction(PCR) screening for 8 sequence-tagged site (STS) markers and5 randomly amplified polymorphic DNA (RAPD) markers. Of 458YACs, 235 individual YACs with an average insert length of 350kb were selected and ordered on chromosome 5 from the YAC library.Forty-eight contigs covering nearly 21 Mb were formed on thechromosome 5; the longest one was 6 cM and covered 1.5 Mb. Thelength covered with YAC clones corresponded to 62% of the totallength of chromosome 5. There were many multicopy sequencesof expressed genes on chromosome 5. The distribution of manycopies of these expressed gene sequences was determined by YACSouthern hybridization and is discussed. A physical map withthese characteristics provides a powerful tool for elucidationof genome structure and extraction of useful genetic informationin rice.     

Rice molecular genetic map using RFLPs and its applications

In the past decade, notable progress has been made in rice molecular genetic mapping using genomic or cDNA clones. A total of over 3000 DNA markers, mainly with RFLPs, have been mapped on the rice genome. In addition, many studies related to tagging of genes of interest, gene isolation by map-based cloning and comparative mapping between cereal genomes have advanced along with the development of a high-density molecular genetic map. Thus rice is considered a pivotal plant among cereal crops and, in addition to Arabidopsis, is a model plant in genome analysis. In this article, the current status of the construction of rice molecular genetic maps and their applications are reviewed.     

An Integrated High-density Linkage Map of Soybean with RFLP, SSR, STS, and AFLP Markers Using A Single F2 Population

Soybean [Glycine max (L.) Merrill] is the most important leguminouscrop in the world due to its high contents of high-quality proteinand oil for human and animal consumption as well as for industrialuses. An accurate and saturated genetic linkage map of soybeanis an essential tool for studies on modern soybean genomics.In order to update the linkage map of a F₂ population derivedfrom a cross between Misuzudaizu and Moshidou Gong 503 and tomake it more informative and useful to the soybean genome researchcommunity, a total of 318 AFLP, 121 SSR, 108 RFLP, and 126 STSmarkers were newly developed and integrated into the frameworkof the previously described linkage map. The updated geneticmap is composed of 509 RFLP, 318 SSR, 318 AFLP, 97 AFLP-derivedSTS, 29 BAC-end or EST-derived STS, 1 RAPD, and five morphologicalmarkers, covering a map distance of 3080 cM (Kosambi function)in 20 linkage groups (LGs). To our knowledge, this is presentlythe densest linkage map developed from a single F₂ populationin soybean. The average intermarker distance was reduced to2.41 from 5.78 cM in the earlier version of the linkage map.Most SSR and RFLP markers were relatively evenly distributedamong different LGs in contrast to the moderately clusteredAFLP markers. The number of gaps of more than 25 cM was reducedto 6 from 19 in the earlier version of the linkage map. Thecoverage of the linkage map was extended since 17 markers weremapped beyond the distal ends of the previous linkage map. Inparticular, 17 markers were tagged in a 5.7 cM interval betweenCE47M5a and Satt100 on LG C2, where several important QTLs wereclustered. This newly updated soybean linkage map will enableto streamline positional cloning of agronomically importanttrait locus genes, and promote the development of physical maps,genome sequencing, and other genomic research activities.     

Brain-derived neurotrophic factor induces cell surface expression of short-form tenascin R complex in hippocampal postsynapses

Brain-derived neurotrophic factor (BDNF) is involved in hippocampal functions such as learning and memory and it plays a crucial role in regulating synaptic plasticity. To investigate potential mechanisms by which BDNF participates in neuronal communication through postsynaptic membrane proteins, we generated monoclonal antibodies against the synaptoneurosomal particulate fraction of mouse brain. One of the monoclonal antibodies, termed mAb#27, was found to be useful for analyzing BDNF-induced externalization of synaptoneurosomal membrane proteins of the hippocampus. In dissociated neuronal cultures, BDNF stimulation increased mAb#27 immunoprecipitates of biotin-labeled proteins with apparent masses, 55kDa, 80kDa, 100kDa, 130kDa, 140kDa and 160kDa. The mAb#27 recognition molecules were located in specific hippocampal regions of the brain and at postsynaptic sites in cultured cells. Proteomic studies of the mAb#27 immunocomplex identified newly derived short forms of tenascin R (TNR) as the mAb#27 recognition molecule. Contactin 1, prostaglandin regulatory-like protein and GABA A receptor subunit beta3 were identified as TNR-associated proteins. These proteins were recruited to mAb#27 when BDNF was applied to cells in culture. Each molecules identified in the present study contributes to the postsynaptic plasticity or the active cycle of cellular vesicle membranes. The formation of the TNR complex may serve as an underlying basis for synaptic plasticity in the hippocampus. Our results demonstrate that BDNF plays a role in external molecular dynamics and is likely to regulate synaptic functions such as the enhancement of neuronal excitability through GABAergic neurons.