A Clostridium perfringens Vector for the Selection of Promoters

A promoter selection vector for Clostridium perfringens genes was constructed from a C. perfringens-Escherichia coli shuttle vector, pJIR418. The plasmid carries a promoterless chloramphenicol acetyltransferase gene (catP), derived from pIP401, downstream of the multiple cloning sites of pUC18. When a promoter region of the phospholipase C gene was inserted into one of the cloning sites, derivatives of C. perfringens strain 13 carrying the resultant plasmid acquired resistance to chloramphenicol. This plasmid should be a useful reporter system for C. perfringens genes.     

A Novel Assay System for Anti-Human Immunodeficiency Virus Type 1 (HIV-1) Activity Using a Subclone of a Monocytic Cell Line,U937

A subclonal cl.1–14 cell was established from a monocytic cell line U937 by a limiting dilution method. The anti-HIV-1 activity of some antiviral compounds was evaluated in HIV-1-infected cl.1–14 cells. The results demonstrated that although AZT was a potent inhibitor of HIV-1 replication in cl.1–14 cells, its 50% effective concentration (EC₅₀) values was 80 times higher than that in HIV-1 infected MT-4 cells; the EC₅₀ of AZT was 0.16 μM and 0.002 μM in cl.1–14 and MT-4 cells, respectively. In contrast, the anti-HIV-1 activity of ddA, ddI and ddC in cl.1–14 cells was comparable to that in MT-4 cells. The antiviral activity of nevirapine, dextran sulfate, curdlan sulfate and T22 did not differ significantly between the cl. 1–14 and MT-4 cells. The antiviral activity of several compounds in the HIV-1-infected cl.1–14 cells was similar to that in the HIV-1jr -fl -infected human peripheral macrophages. Our results suggest that cl.1–14 cell cultures are very useful for estimating antiviral activity and more advantageous than the use of peripheral blood macrophages.     

Identification of Surface-Exposed Parts of Red-Light- and Far-Red-Light- Absorbing Forms of Native Pea Phytochrome by Limited Proteolysis

Peptide fragments were obtained by limited proteolysis withtrypsin and Staphylococcus aureus V 8 protease from either theP_R or the P_FR form of 121-kDa phytochrome purified from etiolatedpea (Pisum sativum L.) shoots. Patterns of bands after polyacrylamidegel electrophoresis in the presence of SDS of the digests weredifferent, with some bands appearing preferentially when thedigestions were carried out with the P_R or the P_FR form. Amino-terminalsequences of the fragments were analyzed to determine the exactlocations of the amino-termini of the fragments within the aminoacid sequence of the apoprotein of pea phytochrome. The aminoacid compositions of some of the sequenced fragments were determinedin order to confirm the carboxy-terminal amino acids. Threecleavage regions were identified as kinetically favored sitesof cleavage of P_FR (Arg-746 to Lys-752, around Glu-877 and aroundArg-1010), whereas only one was identified for P_R (Glu-38 toArg-62). Regions of Glu-255, Arg-383, Arg-583 to Glu-620 andLys-1093 to Glu-1115 were also identified as potential sitesof proteolytic cleavage in both forms of the phytochrome. Othercleavage sites, the specificities of which have not yet beendetermined, are Glu-404, Glu-695 and Lys-1045. Surface-exposed parts of phytochrome in the P_R and P_FR formsare discussed. (Received June 13, 1992; Accepted October 27, 1992)     

Photosynthetic Adaptation to High Temperature Associated with Thylakoid Membranes of Synechococcus PCC7002

Photosynthetic adaptation to high temperature was investigatedin intact cells and isolated thylakoid membranes of the cyanobacterium,Synechococcus PCC7002. In intact cells, the thermal stabilityof photosynthesis and photosystem 2-mediated electron transportfrom H₂O to 1,4-benzoquinone changed in concert with growthtemperature. The photosystem 2-mediated electron transport fromH₂O to phenyl-1,4-benzoquinone showed greater thermal stabilityin thylakoid membranes isolated from cells which had adaptedto high temperature than in those from non-adapted cells. Enhancedthermal stability was also observed in the thylakoid membranesin the transport of electrons from H₂O to 2,6-dichlorophenolindophenolbut not in the transport of electrons from diphenylcarbazideto 2,6-dichlorophenolindophenol. These observations suggestthat oxygen-evolving sites acquire enhanced thermal stability,and that factors which are responsible for thermal stabilityremain in isolated thylakoid membranes. (Received October 30, 1992; Accepted December 18, 1992)     

Are daughters more costly to produce for Japanese macaque mothers?: Sex of the offspring and subsequent interbirth intervals

Based on a sample of 237 live births recorded over a period of 30 years, a tendency for longer interbirth intervals following the birth of daughters than sons was recognized, in the provisioned Arashiyama troop of Japanese macaques. This may indicate that female infants were more costly to produce than male infants. This tendency seemed to be independent of a mother’s rank.     

SYNCHRONIZATION OF CHLOROPLAST DIVISION IN THE ULTRAMICROALGA CYANIDIOSCHYZON MEROLAE (RHODOPHYTA) BY TREATMENT WITH LIGHT AND APHIDICOLIN

A system of highly synchronized chloroplast divisions was developed in the unicellular red alga Cyanidioschyzon merolae De Luca, Taddei, & Varano. Chloroplast divisions were examined by epifluorescence microscopy following treatments with light and inhibitors. When the cells during stationary phase were transferred into a new medium under a 12:12 h LD cycle, chloroplasts, mitochondria, and cell nuclei divided synchronously in that order soon after the initiation of dark periods. More than 40% of the cells contained dividing chloroplasts. To obtain a system of highly synchronized cell division and chloroplast division, the cells synchronized by a 12:12 h LD cycle were treated with various inhibitors. Nocodazole and propyzamide did not affect cell and organelle divisions, whereas aphidicolin markedly inhibited cell-nuclear divisions and cytokinesis and induced a delay in chloroplast division. More than 80% of the cells contained dividing chloroplasts when cells synchronized by light were treated with aphidicolin for 12 h. This synchronized system will be useful for studies of the molecular and cellular mechanisms of organelle divisions .     

Molecular cloning of two tandemly arranged peroxidase genes from Populus kitakamiensis and their differential regulation in the stem

A genomic library was prepared from Populus kitakamiensis and screened with the cDNA for an anionic peroxidase from P. kitakamiensis. One genomic clone was isolated that contained two tandemly oriented genes for anionic peroxidases, prxA3a and prxA4a. Both genes consisted of four exons and three introns; the introns had consensus nucleotides, namely, GT and AG, at their 5 and 3 ends, respectively. The prxA3a and prxA4a genes encoded 347 and 343 amino acid residues, respectively, including putative signal sequences at the amino-termini. Putative promoters and polyadenylation signals were found in the flanking regions of both genes. The sequence of the coding region of prxA3a was completely identical to that of the cDNA clone pA3, whereas the sequence of the coding region of prxA4a was only 73% identical to that of the cDNA clone pA3. Northern blot analysis showed that the patterns of expression of the mRNAs that corresponded to prxA3a and prxA4a differed in stems of P. kitakamiensis.