Isolated Phosphate-Solubilizing Soil Bacteria Promotes In vitro Growth of Solanum tuberosum L.

The capacity of four bacterial strains isolated from productive soil potato fields to solubilize tricalcium phosphate on Pikovskaya agar or in a liquid medium was evaluated. A bacterial strain was selected to evaluate in vitro capacity of plant-growth promotion on Solanum tuberosum L. culture. Bacterial strain A3 showed the highest value of phosphate solubilization, reaching a 20 mm-diameter halo and a concentration of 350 mg/l on agar and in a liquid medium, respectively. Bacterial strain A3 was identified by 16S rDNA analysis as Bacillus pumilus with 98% identity; therefore, it is the first report for Bacillus pumilus as phosphate solubilizer. Plant-growth promotion assayed by in vitro culture of potato microplants showed that the addition of bacterial strain A3 increased root and stems length after 28 days. It significantly increased stem length by 79.3%, and duplicated the fresh weight of control microplants. In this paper, results reported regarding phosphorus solubilization and growth promotion under in vitro conditions represent a step forward in the use of innocuous bacterial strain biofertilizer on potato field cultures.Key words: Bacillus sp., phosphorus soluble, Pikovskaya agar, potato rhizosphere, plant growth promoting rhizobacteria     

Glutathione S transferase mu polymorphism and gastric cancer in the Portuguese population

The glutathione S-transferases appear to form part of a protective mechanism against the development of cancer where environmental chemical carcinogens are involved. In humans one member of the mu class gene family (GSTM1) has been shown to be polymorphic and is only expressed in ~50% of individuals. Previous studies have shown a possible link between the null phenotype and susceptibility to cancer but have been equivocal regarding stomach cancer. To evaluate any association in Portuguese gastric cancer individuals with GSTM1 variability, we performed GST M 1 polymorphism by PCR amplification in 148 gastric cancer patients and in 84 healthy control individuals. We found no statistical differences between the gastric cancer and control populations (wild type phenotype: 52%, 48%; null phenotype: 48%, 52%, respectively). A subset analysis into site of tumour also revealed no significant differences between the groups, although we found a slight increase of the wild type phenotype in the samples of the antrum compared with the control population (57% vs 48%, respectively; 2= 1.18; p 0.28) and a slight increase of the null phenotype in the signet ring cells/mucocellular group (2= 1.05; p 0.3). However, in both cases it did not reach statistical significance. A subset analysis of the histological groups following the WHO criteria revealed a statistically significant difference (2= 3.704; p 0.05) between the moderately differentiated gastric adenocarcinoma and the presence of the wild type phenotype. These results do not support the hypothesis that the GSTM1 null phenotype predisposes to gastric cancer in the Portuguese population and the moderately differentiated gastric adenocarcinoma seems to be associated with the presence of the G STM 1 wild type phenotype.     

Relevance of Hemin for in vitro Differentiation of Trypanosoma cruzi1

Simple culture conditions that allow good growth and high yields of trypomastigotes are described. The proportion of metacyclic trypomastigotes increases with the concentration of hemin in the culture medium, reaching a peak of 80% after 10 days with 20 mg hemin/liter.     

Characteristics of a Microsporidium (Protozoa: Microspora) Infecting Grasshoppers (Orthoptera: Pyrgomorphidae) in Cape Verde, Africa

ABSTRACT A light and electron microscopic study was conducted of a microsporidium isolated from the grasshopper Pyrgomorpha cognata Krauss, 1877 collected in Santo Antão and Santiago Islands, Cape Verde. The evidence suggests that although there are some differences, such as tissues affected and size of spores, the organism appears conspecific with Nosema pyrgomorphae Toguebaye, Seck & Marchand, 1988, which was described from another species of the genus Pyrgomorpha Audinet-Serville, 1838 in Senegal. However, in addition to the differences in tissue specificity and size of spores, light microscopy studies also revealed some stages of the pathogen (uninucleate bodies and plasmodia) apparently not previously observed in N. pyrgomorphae .     

Pollen use by Megalopta sweat bees in relation to resource availability in a tropical forest

1. Spatial and temporal availability of pollen helps shape bee foraging behaviour and productivity, which has been studied in great detail at the landscape level, but never in a diverse tropical forest. 2. To study the effect of spatio‐temporal variation in resource distribution on pollen use and productivity, we identified pollen from spatially explicit nest collections of two generalist sweat bees, Megalopta genalis Meade‐Waldo and M. centralis Friese, from Barro Colorado Island, Panama, a 50‐ha forest dynamics plot during the 2007 dry and early wet seasons. Pollen from nests collected in 1998–1999 without spatial information was also identified. 3. Bees used pollen of at least 64 species; many of these occurred in only one collection. The 2007 collections contained pollen of 35 different species, but were dominated by five species, especially Hura crepitans L. and Pseudobombax septenatum (Jacq.) Dugand. 4. Temporal availability, but not distance from nest, influenced flower use at a 50‐ha scale. 5. Body size was not associated with minimum flight distance as inferred from pollen collections. 6. Nest productivity and pollen diversity decreased from the dry to wet seasons, mirroring community‐level availability of floral resources. 7. Results suggest that on a scale of 50 ha, bees are choosing certain host plant species regardless of distance from the nest, but adjusting foraging behaviour opportunistically based on the temporal availability of host flowers.     

ACROSOME BREAKDOWN IN LEPTODACTYLUS CHAQUENSIS (AMPHIBIA ANURA) SPERMATOZOA*

Acrosome breakdown in Leptodactylus chaquensis is described: during this process acrosome enlarges, becomes round-shaped and finally disrupts. Low tonicity media (0.025 M sucrose and 1/10 Holtfreter's solutions) favor acrosome breakdown and sperm fertility loosing. High tonicity media (0.250 M sucrose and Holtfreter's solutions) maintain acrosomes in an unreacted stage and sperm fertilizing capacity is preserved. Sperm motility does not seem to be a sufficient condition for the sperm to fertilize and also does not seem to be related with acrosome breakdown. The presence of lectins in the incubation media does not modify the time-course of acrosome breakdown.