Alkaloids of the leaves of Voacanga grandifolia

Besides vobtusine and vobtusine-lactone, deoxyvobtusine was isolated from the leaves of Voacanga grandifolia (Miq. Rolfe. Spectral and chemical evi     

Role of Melanin in Release of Extracellular Enzymes and Selection of Aggressive Isolates of Bipolaris sorokiniana in Barley

Eighteen barley isolates of Bipolaris sorokiniana belonging to wild and clonal type of black, mixed and white subpopulations were quantitatively assayed for their melanin content and aggressiveness with respect to production of some of the extracellular enzymes such as cellulase, pectinase, amylase and protease. Cellulase and pectinase constituted major portion of the enzymes recovered from the black, mixed and white isolates. Enzyme production and aggressiveness were relatively higher in melanin devoid or low melanin isolates. The melanin deficient isolates were also differentiated from black and mixed isolates on the basis of variation in internal transcribed spacer region of the ribosomal DNA. Higher enzyme productions positively correlated with area under disease progress curve (AUDPC) and lesion development. Melanin content was negatively correlated with extracellular enzymes and aggressiveness of the isolates. Based on melanin content, lesion size, AUDPC and extracellular enzymes, the isolates were grouped in two major clusters (I and II) with further division of cluster II into two sub-clusters (II-A and II-B). The results appears to indicate a possible role of melanin in release of extracellular enzymes and hence in evolution and selection of aggressive isolates of B. sorokiniana in barley.     

Microbial reduction of ethyl acetoacetate using Sclerotium rolfsii

Summary A method for the quantitative enantioselective bioreduction of ethyl acetoacetate [1] to optically pure (+)-S-ethyl-3 hydroxybutyrate [II] usingSclerotium rolfsii mycelium is described. In a synthetic medium 1 g mycelium (dry weight) could convert 1 g of I to II within 2–3 days of fermentation (pH 5.8, 30°C). This is the first report demonstrating use ofS. rolfsii biomass for asymmetric reduction to get chiral building blocks.     

Monitoring of denitrification byPseudomonas aeruginosa using on-line fluorescence technique

Summary The NAD(P)H fluorescence ofPseudomonas aeruginosa dropped sharply upon addition of nitrate to an anaerobic culture, indicating that denitrification is not limited by mass transfer of nitrate through cell membrane to reach nitrate reductase. The effect of added nitrate concentration on fluorescence drop followed a typical saturation kinetics. The maximum specific denitrification rate under the studied condition was found to be 0.26±0.05 g NO ₃ ⁻ -N/g cells-hr.     

DNA replication initiates non-randomly at multiple sites near the c-myc gene in HeLa cells.

The origin of replication of the c-myc gene in HeLa cells was previously identified at low resolution within 3.5 kb 5' to the P1 promoter, based on replication fork polarity and the location of DNA nascent strands. To define the initiation events in the c-myc origin at higher resolution the template bias of nascent DNAs in a 12 kb c-myc domain has been analyzed by hybridization to strand specific probes. Strong switches in the asymmetry of nascent strand template preference confirm that replication initiates non-randomly at multiple sites within 2.4 kb 5' to the c-myc P1 promoter, and at other sites over a region of 12 kb or more. The strongest template biases occur in the 2.4 kb region 5' of the P1 promoter, shown earlier to contain sequences which allow the autonomous semiconservative replication of c-myc plasmids. An asymmetric pyrimidine heptanucleotide consensus sequence has been identified which occurs 12 times in the c-myc origin zone, and whose polarity exactly correlates with the polarity of nascent strand synthesis.     

Pathogenesis of SIVmac251 after atraumatic inoculation of the rectal mucosa in rhesus monkeys

Intrarectal inoculation of rhesus monkeys with low doses of SIV_mac led to a prolonged clinical and virological latency that was not observed for high intrarectal doses or for intravenous inoculation. Animals infected intrarectally with low virus doses remained negative for serum antibody responses to SIV for at least one year even though they readily transferred SIV to naive recipients via transfusion of whole blood.     

Determination of Gardnerella vaginalis Genome Size by Pulsed-Field Gel Electrophoresis

The chromosomal DNA of four strains of Gardnerella vaginaliswere digested with rare cutting restriction enzymes and analyzedby pulsed-field gel electrophoresis (PFGE). The four strainsstudied were two clinical isolates (GVP 004 & GVP 007) andtwo American Type Culture Collection strains (ATCC 14018 &ATCC 14019). The restriction enzyme SfiI generated two DNA fragmentsof about 0.6 Mb and 1.1 Mb in all four strains giving a G. vaginalisgenome size of about 1.7 Mb. A similar genome size was calculatedutilizing two more GC-rich sequence specific restriction endonucleases,NotI and AscI. When digested with AscI, the chromosomal DNAof all four strains gave rise to 11 to 12 DNA fragments rangingbetween 0.01 Mb to 0.43 Mb. DNA from the two clinical isolateswere digested by NotI (yielding 7 to 9 fragments), while theDNA from the two ATCC strains were resistant to NotI digestion.In contrast to the clinical isolates, DNA from the two ATCCstrains gave an identical profile for all restriction endonucleasestested. From double digestion experiments, the two SfiI sitescould be localized on two AscI fragments. From these PFGE studies,it is concluded that the G. vaginalis genome is a circular DNAthat ranges between 1.67 Mb and 1.72 Mb in size.