Initiation of meiosis and sporulation in Saccharomyces cerevisiae does not require a decrease in cyclic AMP.

Meiosis and sporulation of Saccharomyces cerevisiae are initiated in a guanine auxotroph by guanine deprivation (E. Bautz Freese, Z. Olempska-Beer, A. Hartig, and E. Freese, Dev. Biol. 102:438-451, 1984). We used this condition to examine a hypothesis (K. Matsumoto, I. Uno, and T. Ishikawa, Cell 32:417-423, 1983) that initiation of meiosis requires a low level of cAMP. We found that, after guanine deprivation, the intracellular concentration of cAMP transiently decreased not more than 20% and not at all if the cAMP phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) was added to the medium. Under these conditions, at least 76% of the cells sporulated in the absence of IBMX, and almost 100% sporulated in its presence. The sporulating cells continually excreted cAMP and utilized the gluconeogenic carbon source. The cells failed to sporulate efficiently and to form four-spored asci if simultaneously deprived of guanine and carbon. After guanine deprivation in glucose medium, sporulation remained suppressed and intracellular cAMP was unchanged. We conclude that, under conditions of guanine starvation, cAMP deficiency is not required for initiation of meiosis and sporulation, cAMP is produced in excess and excreted to the medium, the cells sporulate better if the cAMP concentration is increased by addition of IBMX, the cells require a gluconeogenic carbon source for complete and efficient sporulation, and suppression of sporulation by glucose is not mediated by cAMP.     

The rat MIS1/Pvt-1 locus is syntenic with MYC on chromosome 7

Mouse Pvt-1 and rat MIS1 are frequent proviral integration sites in retrovirally induced lymphomas. The Pvt-1 locus is also involved in mouse plasmacytoma (6;15) and in the variant Burkitt lymphoma (2;8) translocations. We show that the Pvt-1/MIS1 locus is syntenic with MYC on rat chromosome 7. This is consistent with a postulate of close linkage and, possibly, a functional relationship between the MYC protooncogene and the MIS1/Pvt-1 locus.     

Chemical analysis of Azospirillum lipopolysaccharides

Lipopolysaccharides (LPS) were extracted by hot phenol-water from five strains each of Azospirillum lipoferum and Azospirillum brasilense. Rhamnose, glucose, glucosamine and 3-deoxy-d-mannooctulosonic acid were comon sugar constituents of all LPS preparations. 2-O-Mefucose, 3-O-Me-fucose, 3-O-Me-rhamnose and 2-O-Megalactose were found in LPSs of some A. brasilense strains. Fatty acid spectra from all LPSs studied were almost identical with predominance of 3-hydroxymyristic and 3-hydroxypalmitic acids. 3-Hydroxypalmitic acid was the only amide-linked fatty acid. Lipopolysaccharides isolated from A. brasilense showed higher heterogeneity in sugar composition than those from A. lipoferum.Abbreviations glc gas liquid chromatography - ms mass spectrometry - LPS lipopolysaccharide - dOclA 3-deoxy-d-mannooctulosonic acid - 3-OH-16:0 3-hydroxypalmitic acid - nir^- nitrite reductase negative - nir⁺ nitrite reductase positive     

Synthesis and physical characterization of DNA fragments containing N4-methylcytosine and 5-methylcytosine.

The synthesis of N4-methyl-2'-deoxycytidine and its fully protected mononucleotide, suitable for the oligonucleotide synthesis by phosphotriester method is described. A set of octanucleotides - d(CGCGCGCG), d(CG5mCGCGCG), d(CG4mCGCGCG) and dodecanucleotides - d(GGACCCGGGTCC), d(GGA5mCCCGGGTCC), d(GGA4mCCCGGGTCC) has been synthesized in a solution. Physical characterization of the oligonucleotide duplexes by means of UV and CD spectrometry provides the evidence that 4mC similarly to 5mC favours the B--greater than Z transition, although both of these methylated cytosines inhibit the B--greater than A conformational change. N4-Methylcytosine in contrast to 5-methylcytosine reduces the DNA double helix thermal stability.     

Effects of Growth Regulators and Glutamine on In Vitro Development of Zygotic Embryos of Taro (Colocasia esculenta var. antiquorum)

Zygotic embryos of taro, Colocasia esculenta var. antiquorumcultured on Linsmaier-Skoog (LS) medium without the additionof hormones develop into mature plants only in the presenceof endosperm tissue. Growth is usually evident within the firstweek of culture when embryos swell and become green. Embryosexcised from endosperm and cultured on LS containing 0-01 mg1^–1 naphthaleneacetic acid (NAA), and 0–01 mg 1^–16-dimethylaminopurine (6-DMAP) grow at a rate comparable withcontrols for the first week of culture. During the second week,growth rates are higher than controls primarily because embryosform elongated hypocotyl regions which often produce swollentissues and/or callus. In the presence of 200 mg 1^–1 glutamineand a range of concentrations of 6-dimethylaminopurine, benzyladenine,or NAA, elongation of the hypocotyl axis is inhibited, and acompact callus may develop. Embryos grown on LS containing 200mg 1^–1 glutamine and 2.0 mg 1^–1 2, 4, 5-trichlorophenoxyaceticacid form friable callus which was used to generate short-livedsuspension cultures. Growth Regulators, Glutamine, tygotic embryos, Colocasia esculenta, endosperm     

Characterization of the toxicity and cytopathic specificity of a cloned Bacillus thuringiensis crystal protein using insect cell culture

An insecticidal protein gene from Bacillus thuringiensis var. aizawal was cloned in Escherichia coli. The cloned gene expressed at a high level and the synthesized protein appeared as an insoluble, phase-bright inclusion in the cytoplasm. These inclusions were isolated by density gradient centrifugation, the isolated protein was activated in vitro by different proteloytic regimes and the toxicity of the resulting preparations was studied using insect cells grown in tissue culture. The inclusions consisted of a 130 kDa polypeptide which was processed to a protease-resist-ant 55 kDa protein by tryptic digestion. This preparation lysed lepidopteran (Choristoneura fumiferana) CFI ceils but not dipteran (Aedes albopictus) calls. When the crystal protein was activated by sequential treatment, first with trypsin and then with Aedes aegypti gut proteases, the resulting 53 kDa polypeptide was now toxic only to the dipteran cells and not to the lepidopteran cells. Thus the dual specificity of this var. aizawal toxin results from differential proteolytic processing of a single protoxin. The trypsin-activated preparation was weakly active against Spodoptera frugiperda cells. Membrane binding studies of the trypsin-activated toxin revealed a 68 kDa protein in the lepidopteran ceil membranes, which may be the receptor for this toxin.     

Tissue specific expression of the acetylcholinesterase gene in Drosophila melanogaster

Summary Acetylcholinesterase (AChE) is mainly membrane bound in the central nervous system (CNS) of larvae and in the head and thorax of adults of Drosophila melanogaster; it is mostly soluble in the larval carcass, the adult abdomen, similar to that of the embryos (Zador et al. 1986). The enzyme shows the same number of isozymes (four or five) in larvae and adults as in the head of the fly or in embryos (Zador et al. 1986). In the Df(3R)GE26/MKRS stock both the membrane bound and the soluble enzyme are at about half normal levels while in the Df(3R)Ace ^HD1/MKRS stock this is true only for the membrane bound AChE. Therefore the effect of the above deficiencies in larvae and adults is consistent with that in embryos (Zador et al. 1986). In heat-sensitive combinations of certain Ace mutant alleles both the membrane bound and the soluble enzyme has reduced activity.Abbreviations AChE acetylcholinesterase (acetylcholine acetyl hydrolase, EC 3.1.1.7) - BAP 1,5-bis(allyldimethylammonium-phenyl)-pentan-3-one dibromide - CNS central nervous system     

Selection of methods of detecting lactose-fermenting Salmonella strains and evaluating their usefulness for diagnostic studies

Salmonella rods of subspecies I, lactose-fermenting were first isolated in Poland in 1980. They were isolated from a plus sample taken from a brain abscess of a child. Next strains were isolated from faeces of newborn and hospitalized children. Growth characteristic of colonies of lactose-fermenting Salmonella strains on selective-differentiating media (Mac Conkey's Levine, SS, So?tys) recommended for inoculation of clinical material resembled Escherichia coli. So far these type of colonies were omitted in diagnostic examinations. Lactose-fermenting variants showed on Bismuth sulfate agar "Difco" (WB) typical for Salmonella growth pattern. They grew on this medium after 48 hr of incubation in a form of black, medium sized colonies, with some metallic brilliance and characteristic blackening of the medium undercolonies. Precise knowledge of biochemical properties of lactose-fermenting Salmonella allows to supplement so far used diagnostic scheme with additional tests permitting differentiation of lactose-fermenting variants of Salmonella from the other members of Enterobacteriaceae family. Taking into consideration biochemical variants in diagnostic procedure i.e. lactose-fermenting Salmonella, allowedns to isolate in the years 1983-1985 lactose-positive strains in 1305 out of 2773 (47%) individuals positive for S. agona. In 1987, 246 persons (28.3%) out of 869 with lactose-fermenting Salmonella of various serotypes were simultaneously infected with lactose-negative variant. Lactose-fermenting strains of Salmonella belonged most frequently to the following genera: S. agona, S. enteritidis, S. oranienburg, S. typhimurium, and S. goldcoast. It was found that the modified diagnostic procedure makes possible the isolation and the identification of lactose-positive varians of Salmonella.     

A case of experimental transmission of the causative agent of plague from Ornithodoros tartakovskyi ticks to fleas of the great gerbil

Biological interrelations between ectoparasites from the colonies of great gerbil were studied experimentally. Hungry fleas Coptopsylla lamellifer are able to feed on the ticks Ornithodoros tartakovskyi infected with plague and in so doing be infected with plague agent. Such feeding is identified as "heterovampirism".