Communication in the migratory termite-hunting ant Pachycondyla (= Termitopone) marginata (Formicidae, Ponerinae)

The Neotropical species Pachycondyla marginata conducts well-organized predatory raids on the termite species Neocapritermes opacus and frequently emigrates to new nest sites. During both activities the ants employ chemical trail communication. The trail pheromone orginates from the pygidial gland. Among the substances identified in the pygidial gland secretions, only citronellal was effective as a trail pheromone. Isopulegol elicited an increase in locomotory activity in the ants and may function as a synergist recruitment signal. The chemical signal is enhanced by a shaking display performed by the recruiting ant.     

Factors affecting transient gene expression in cultured radiata pine cotyledons following particle bombardment

Transfer and expression of the β–glucuronidase gene ( gusA ) in cultured cotyledons of radiata pine ( Pinus radiata D. Don ) were obtained by particle bombardment. Conditions for optimum transient expression were established by using plasmid pB[/12], delivered by gold particles, 1.6 μm in diameter, into 8-day-old cultured cotyledons. Helium pressure of 7.6 MPa, bombardment distance between the stopping screen and the target tissues of 6 cm, and 0.8 μg of plasmid DNA per bombardment proved to be the best parameters for transient expression; using these parameters 79% of bombarded cotyledons showed GUS activity, with 4.3 blue spots per cotyledon. This system was used for studying the expression of several gus-driven promoters the expression of the sunflower ubiquitin gene promoter was higher (99% of positive cotyledons, with 14.2 blue spots per cotyledon) than that of the CaMV 35S promoter, whereas the rice actin and the maize alcohol dehydrogenase gene promoters gave lower gusA expression, as determined histochemically. These results were confirmed by using the gus fluorometric assay. Use of the sunflower ubiquitin gene promoter resulted in gusA expression up to 20 days after bombardment, with a significant level of gus expressing loci per bombarded cotyledon, whereas with the CaMV 35S promoter gusA expression was lost 12 days after bombardment.     

Somatic embryogenesis,organogenesis and callus growth kinetics of flax

The effects of plant growth regulators (PGR) on calli induction, morphogenesis and somatic embryogenesis of flax were studied. The organogenic and callus formation capacity were assessed for different types of source explants. Root and shoot explants were equally good material for calli production but the former produced calli without shoot regeneration capacity. Under the experimental conditions tested, 2,4-dichlorophenoxyacetic acid (2,4-D) + zeatin was the most efficient PGR combination on calli induction and biomass production. The calli were green but with no rhizogenic capacity. In contrast, and at similar concentrations, indole-3-butyric acid (IBA) + kinetin induced white or pale green friable calli with a good root regeneration capacity (60%). A factorial experiment with different combinations of 2,4-D + zeatin + gibberellic acid (GA₃) levels revealed that the direction of explant differentiation was determined by specific PGR interactions and concentrations. The results from these experiments revealed that the morphogenetic pathway (shoot versus root differentiation) can be manipulated on flax explants by raising the 2,4-D level from 0.05 to 3.2 mg l^?1 in the induction medium. The induction and development of somatic embryos from flax explants was possible in a range of 2,4-D + zeatin concentrations surrounding 0.4 mg l^?1 2,4-D and 1.6 mg l^?1 zeatin, the most efficient growth regulator combination.     

Candida biotypes in patients with oral leukoplakia and lichen planus

Prevalence of yeasts in 35 leukoplakia and 34 oral lichen planus patients was compared with that observed in persons without oral diseases. Serotype and morphotype were determined on Candida albicans isolates. Yeasts were isolated from the oral cavity specimens of 43.7% of the patients. C. albicans (serotype A) was the predominant species (76% in leukoplakia, 88.2% in lichen planus and 60.8% in healthy persons). Sixteen morphotypes were encountered on malt extract agar, being 732, 733, 734, 753 and 754 the most frequently found. Morphotypes SP1N and SP1Y were the most common on Sabouraud-trypheniltetrazolium agar (68.4% of the isolates from leukoplakia and 73.3% from lichen planus, but only 46.6% of the isolates from healthy oral mucosa showed SP1N morphotype). Presence of oral lesions was associated with a marked reduction in the yeast species and C. albicans biotypes, suggesting that C. albicans and particularly some of its biotypes, show a high potential of adaptation to the changes associated with the development of oral leukoplakia and lichen planus.     

Cloning and expression of the Neisseria meningitidis 5C outer membrane protein

The 5C outer membrane protein, one of the N. meningitidis class 5 proteins, was preferably expressed in bacteria isolated from the nasopharynx and its role in adhering to the mucosal cells and invading them as well as the development of anti-5C antibodies in healthy carriers was demonstrated. Anti-5C monoclonal antibodies are bactericidal in the presence of the human complement. The immunodominant region of the 5C protein is highly conserved among the different strains of N. meningitidis, and the opc gene, which encodes the protein, does not seem to show antigenic variations. Here the isolation of the opc gene from the Cuban strain B:4:P1.15 by PCR (Polymerase Chain Reaction) is presented. Under the regulation of the tryptophan promoter, the gene was cloned and sequenced in E. coli with a high level of expression and fused to the amino-terminal end of the interleukin-2 gene. In the dot-blot experiments, the presence of the gene in those strains which did not express the protein in the whole cell ELISA was also detectable.     

Inorganic self-organisation in precambrian cherts

Silica biomorphs are inorganic self-organized precipitates resulting from a crystal aggregation process controlled by a metal silicate membrane. They display morphological and symmetric properties of living organisms and form under physico-chemical conditions similar to some geochemical conditions suggested for the chemical precipitation of Precambrian chert precursors. In consequence, these inorganic precipitates are proposed as an alternative interpretation to be considered when trying to decipher the biogenicity of putative Precambrian microbiotas.     

Purification of amoebolytic substances from Bacillus licheniformis M-4

Three antibiotic peptides with amoebolytic activity have been purified from culture supernatants of Bacillus licheniformis M-4 (amoebicins m4-A, m4-B, and m4-C). They were hydrophilic peptides consisting of six different amino acids (Asp, Glu, Ser, Thr, Pro, Tyr). Their molecular weights ranged from 3,000 to 3,200. Purified amoebicins were active against human pathogenic and non-pathogenic strains of Naegleria. They also showed a broad antifungal spectrum, but a narrow antibacterial activity.Abbreviations (TFA) Trifluoroacetic acid     

A likelihood approach to calculating risk support intervals.

Genetic risks are usually computed under the assumption that genetic parameters, such as the recombination fraction, are known without error. Uncertainty in the estimates of these parameters must translate into uncertainty regarding the risk. To allow for uncertainties in parameter values, one may employ Bayesian techniques or, in a maximum-likelihood framework, construct a support interval (SI) for the risk. Here we have implemented the latter approach. The SI for the risk is based on the SIs of parameters involved in the pedigree likelihood. As an empirical example, the SI for the risk was calculated for probands who are members of chronic spinal muscular atrophy kindreds. In order to evaluate the accuracy of a risk in genetic counseling situations, we advocate that, in addition to a point estimate, an SI for the risk should be calculated.     

Presence of double‐stranded RNAs and virus‐like particles in the entomopathogenic fungus Metarhizium anisopliae

Nucleic acids from 41 strains of Metarhizium anisopliae, obtained from different parts of the world were extracted and examined by electrophoresis. Strong bands of double‐stranded RNA (dsRNA) were detected in two isolates from Brazil, V215 and V291, which had, respectively, 13 and 9 distinct bands ranging in size from ca. 0.75 to 3.5 kb. Icosahedral virus‐like particles (VLPs) (ca. 33 nm in diameter) were observed by transmission electron microscopy in extracts of these isolates. The VLPs and dsRNA were both absent from a clone of the isolate V291 which had been subcultured successively on solid medium. Bioassays against the aphid Myzus persicae showed no detectable difference in virulence between the clone of V291 which contained dsRNA and the clone that did not.     

Replication of the promiscuous plasmid pLSI: a region encompassing the minus origin of replication is associated with stable plasmid inheritance

Deletion of a region of the promiscuous plasmid pLS1 encompassing the initiation signals for the synthesis of the plasmid lagging strand led to plasmid instability in Streptococcus pneumoniae and Bacillus subtilis. This defect could not be alleviated by increasing the number of copies (measured as double-stranded plasmid DNA) to levels similar to those of the wild-type plasmid pLS1. Our results indicate that in the vicinity of, or associated with the single-stranded origin region of pLS1 there is a plasmid component involved in its stable inheritance. Homology was found between the DNA gyrase binding site within the par region of plasmid pSC101 and the pLS1 specific recombination site RS_R.