A Mutation Leading to Constitutive Expression of High Sexual Activities in the Yeast Saccharomyces cerevisiae

An a mating type mutant of the yeast Saccharomyces cerevisiaewhich expressed high sexual activities during vegetative growthwas isolated and characterized. Its constitutive sexual agglutinabilitywas higher than the sexual agglutinability of its parental straininduced by pheromone. It produced a pheromone and -pheromone-inactivatingsubstances in larger amounts than its parental strain. It alsoproduced large pear-shaped cells (shmooed cells) without pheromone,was more sensitive to pheromone, and grew vegetatively moreslowly than its parental strain. When the mutant was crossedto a wild type strain isogenic with the parental strain, amating type segregants with high constitutive sexual agglutinabilityshowed self-shmooing. However, in a mating type segregants self-shmooingwas not observed regardless of the degree of their sexual agglutinability.The cross between a and segregants, both of which carried themutation, had higher frequency of zygote formation than thecrosses between a and cells one of which or both of which wereof wild type. (Received September 9, 1985; Accepted February 8, 1986)     

Cloning, Expression Analysis, and Chromosomal Localization of BH-Protocadherin (PCDH7), a Novel Member of the Cadherin Superfamily

We have identified a novel member of the cadherin superfamily. Among the members of the superfamily, this protein exhibited the highest overall homology with protocadherin-1 (46–49% identity). Its mRNA was predominantly expressed in the brain and heart. Hence, we named the gene BH-protocadherin (BH-Pcdh) (HGMW-approved symbol PCDH7). BH-Pcdh has an extracellular domain consisting of seven repeats of the cadherin motif (EC 1 to 7). EC2 of BH-Pcdh is unique in having a 55-amino-acid insertion in the middle of the motif. There are three isoforms of BH-Pcdh, denoted -a, -b, and -c, which have different cytoplasmic tails and a 47-amino-acid deletion in the EC2–3 region of BH-Pcdh-c. While only a 9.0-kb message was detected in normal tissues, 4.5- and 9.0-kb mRNA species were seen in the human lung carcinoma cell line A549. Furthermore, only the 4.5-kb mRNA was detected in HeLa cell S3 and human gastric cancer cell lines MKN28 and KATO-III. Southern blot analysis indicated that the BH-Pcdh gene is likely to be conserved among various vertebrates. The BH-Pcdh gene was localized to human chromosome 4p15. Interestingly, 4p15 is a region of loss of heterozygosity in some head and neck squamous cell carcinomas.     

Inter-annual variation of reproductive parameters and fruit availability in two populations of Japanese macaques

Among wild Japanese macaques, which have clear reproductive seasonality, correspondence between fruit-food production in the mating season and birth rate in the following year was confirmed in two different habitats. One of the study areas was evergreen broad leaved forest on Yakushima Island, for which demographic and fruiting data for seven years were used. The other was a deciduous-coniferous mixed forest on Kinkazan Island in the cool temperate zone, for which 11 years of data were used. From the fruit-crop data, each year was classified as a good or bad fruiting year for each population. At both habitats, female macaques had fewer babies after bad fruiting years than after good fruiting years. In Yakushima, small troops had a lower birth rate than large troops and this tendency was clear after bad fruiting but not after good fruiting. On the other hand, in Kinkazan such differences due to troop size were not found. These findings were consistent with the observation that intertroop encounters occur more often and are more agonistic in Yakushima than in Kinkazan and large troops tend to be dominant to small troops in the Yakushima population. Thus annual fluctuations in fruit production appear to increase the difference in birth rates between troops of different sizes through intertroop competition in Yakushima, but not in Kinkazan.     

Identification of a Novel Human Gene Containing the Tetratricopeptide Repeat Domain from the Down Syndrome Region of Chromosome 21

The Down syndrome (DS) region on chromosome 21, which is responsiblefor the DS main features, has been defined by analysis of DSpatients with partial trisomy 21. Within the DS region, we constructeda 1.6-Mb P1 contig map previously. To isolate gene fragmentsfrom the 1.6-Mb region, we performed direct cDNA library screeningand exon trapping using the P1 clones and a human fetal braincDNA library, and obtained 67 cDNA fragments and 52 possibleexons. Among them, 23 cDNA fragments and 4 exons were interpretedto be derived from a single gene by localization on P1 clonesand by Northern analysis. To obtain the full-length cDNA sequence,longer cDNA clones were further screened from another humancDNA library which was enriched with longer cDNA species. Theseclones were sequenced and assembled to a sequence of 9045 bp.This transcribed sequence encodes a novel 2025 amino-acid proteincontaining tetratricopeptide repeat (TPR) motifs and thereforethe gene was designated as TPRD (a gene containing the TPR motifson the Down syndrome region). The TPR domain has been foundin a certain protein phosphatase and in other proteins involvedin the regulation of RNA synthesis or mitosis. The TPRD gene,the novel gene which was proved to be in the 1.6-Mb region andto have the interesting features described above, is a candidatefor genes responsible for the DS phenotypes.     

Effects of thiamine and pyridoxine on respiratory activity in Saccharomyces carlsbergensis strain 4228

Studies were made to elucidate the relationship among the thiamine-induced growth inhibition, decrease in cellular vitamin B₆ content and respiratory deficiency in Saccharomyces carlsbergensis strain 4228 [Nakamura et al., Biochem. Biophys. Res. Commun. 59, 771–776 (1974)]. Addition of pyridoxine to the thiamine-added culture at the beginning or in the course of cultivation brought about appearance of cytochrome spectra and the increase in the activity of heme-containing enzymes and in respiratory activity (Q _{O 2}). The effects of pyridoxine occurred prior to the restoration of growth. Pyridoxine was effective even in the presence of high levels of glucose in the growth medium (not less than 3%). On the basis of these results, the mechanism of the effects of thiamine and pyridoxine was discussed.     

Promotion of sporulation by caffeine pretreatment in saccharomyces cerevisiae

Cells cultured in the presence of caffeine had high sporulation ability. The sporulation-promotive effect of caffeine was studied, special attention being paid upon changes in nucleic acid metabolism. When transferred to a sporulation medium, the breakdown of RNA, the synthesis of protein, RNA and DNA, commitment to sporulation and the appearance of mature asci took place in caffeine-treated cells significantly earlier than in control cells. Commitment to sporulation occurred before the completion of premeiotic DNA synthesis in both caffeine-treated and control cells.     

Catalytic asymmetric synthesis of α-methyl-p-boronophenylalanine

p-Boronophenylalanine (l-BPA) is applied in clinical settings as a boron carrier for boron neutron capture therapy (BNCT) to cure malignant melanomas. Structural modification or derivatization of l-BPA, however, to improve its uptake efficiency into tumor cells has scarcely been investigated. We successfully synthesized (S)-2-amino-3-(4-boronophenyl)-2-methylpropanoic acid in enantioenriched form as a novel candidate molecule for BNCT. Key steps to enhance the efficiency of this synthesis were enantioselective alkylation of N-protected alanine tert-butyl ester with a Maruoka catalyst and Miyaura borylation reaction to install the boron functionality.     

Changes in production of the mating-type-specific glycoproteins, agglutination substances in association with mating type interconversion in homothallic strains of the yeast, Saccharomyces cerevisiae

Summary Sexual activity in homothallic strains of Saccharomyces cerevisiae was investigated. We succeeded in culturing homothallic haploid cells without conjugation, by lowering the pH value of the culture medium. In spore cultures of a homothallic strain both a and pheromones were detected. Agglutination substances of a and mating types were detected in homothallic haploid cells from spore cultures in early logarithmic phase regardless of mating type information at the HML and HMR loci, but either a or agglutination substance was detected predominantly in homothallic haploid cells from spore culture in late logarithmic phase, depending on mating type information at the HML and HMR loci.A part of this work was supported by Grants-in-Aid from Ministry of Education, Science and Culture, Japan, to N.Y.     

Effects of a Pulse of Blue Light on the Extracellular pH in the Pulvinus of Phaseolus vulgaris L.: Measurements with a Double-Barreled pH-Sensitive Electrode

Effects of a pulse of blue light on the extracellular pH inthe pulvinus of Phaseolus vulgaris L. were studied with double-barreledpH-sensitive microelectrodes. A blue-light pulse (30 s) inducedtransient alkalization, sometimes with initial acidification.This result is consistent with the hypothesis that blue lightinactivates the plasmalemma H⁺-ATPase. (Received January 17, 1995; Accepted May 29, 1995)