Ontogenetic and temporal variations in herbivory and defense of Handroanthus spongiosus (Bignoniaceae) in a Brazilian tropical dry forest

We compared the richness and abundance of free-feeding herbivore insects (sap-sucking and leaf-chewing), leaf herbivory damage, leaf toughness and total phenolic content between two ontogenetic stages (juvenile and reproductive) of Handroanthus spongiosus (Rizzini) S. O. Grose (Bignoniaceae) throughout the rainy season in a Brazilian seasonally dry tropical forest. Twenty marked individuals of H. spongiosus were sampled per ontogenetic stage in each period of the rainy season (beginning, middle, and end). Herbivore richness and abundance did not differ between ontogenetic stages, but higher percentage of leaf damage, higher concentration of phenolic compounds, and lower leaf toughness were observed for juvenile individuals. The greatest morphospecies abundance was found at the beginning of the rainy season, but folivory increment was higher at the end, despite the fact that leaf toughness and total phenolic content increased in the same period. No significant relationships between leaf damage and both total phenolic content and leaf toughness were observed. These results suggest that insect richness and abundance do not track changes in foliage quality throughout plant ontogeny, but their decrease along rainy season confirms what was predicted for tropical dry forests. The general trends described in the current study corroborate those described in the literature about herbivores and plant ontogeny. However, the lack of relationship between herbivore damage and the two plant attributes considered here indicates that the analyses of multiple defensive traits (the defense syndrome) must be more enlightening to determine the mechanisms driving temporal and spatial patterns of herbivore attack.     

Pathogen-specific epitopes as epidemiological tools for defining the magnitude of Mycobacterium leprae transmission in areas endemic for leprosy

During recent years, comparative genomic analysis has allowed the identification of Mycobacterium leprae-specific genes with potential application for the diagnosis of leprosy. In a previous study, 58 synthetic peptides derived from these sequences were tested for their ability to induce production of IFN-γ in PBMC from endemic controls (EC) with unknown exposure to M. leprae, household contacts of leprosy patients and patients, indicating the potential of these synthetic peptides for the diagnosis of sub- or preclinical forms of leprosy. In the present study, the patterns of IFN-γ release of the individuals exposed or non-exposed to M. leprae were compared using an Artificial Neural Network algorithm, and the most promising M. leprae peptides for the identification of exposed people were selected. This subset of M. leprae-specific peptides allowed the differentiation of groups of individuals from sites hyperendemic for leprosy versus those from areas with lower level detection rates. A progressive reduction in the IFN-γ levels in response to the peptides was seen when contacts of multibacillary (MB) patients were compared to other less exposed groups, suggesting a down modulation of IFN-γ production with an increase in bacillary load or exposure to M. leprae. The data generated indicate that an IFN-γ assay based on these peptides applied individually or as a pool can be used as a new tool for predicting the magnitude of M. leprae transmission in a given population.     

Engineered Mammalian Vector to Express EGFP-Tagged Proteins as Biomarkers

Due to its specialized post-translational machinery, mammalian cells represent an interesting and not fully explored system to express snake toxins. Therefore, in this work, we built up a new mammalian expression vector that enhances the feasibility to use mammalian cells to express proteins as biomarkers. Among the modifications, an Igκ signal peptide and a 6xHis tag were inserted into this vector in order to drive the protein to the supernatant and simplify its purification, respectively. In addition, to facilitate selection of high producing clones and also tag proteins which may function as a biomarker, the sequence of enhanced green fluorescent protein (EGFP) was added. The efficiency of the resulting vector (pToxEGFP) was tested by cloning and expressing the viper venom disintegrin echistatin (Ech) that due to its affinity to integrin αvβ3 was tested as a molecular marker. Expression of EGFP-Ech was achieved in CHO-DXB11 cells resulting in a yield of 22 mg/L. The binding activity of this chimera protein was successfully achieved on human umbilical vein endothelial cells which highly express αvβ3. The results indicate that pToxEGFP may constitute an efficient and versatile expression vector to express tagged proteins with potential biomarker activity.     

Life history of the predatory mite <Emphasis Type="Italic">Phytoseiulus fragariae</Emphasis> on <Emphasis Type="Italic">Tetranychus evansi</Emphasis> and <Emphasis Type="Italic">Tetranychus urticae</Emphasis> (Acari: Phytoseiidae,Tetranychidae) at five temperatures

Tetranychus evansi Baker and Pritchard and Tetranychus urticae Koch (Acari: Tetranychidae) are important pests of Solanaceae in many countries. Several studies have demonstrated that T. urticae is an acceptable prey to many predatory mites, although the suitability of this prey depends on the host plant. T. evansi, has been shown to be an unfavorable prey to most predatory mites that have been tested against it. The predator Phytoseiulus fragariae Denmark and Schicha (Acari: Phytoseiidae) has been found in association with the two species in Brazil. The objective of this work was to compare biological parameters of P. fragariae on T. evansi and on T. urticae as prey. The study was conducted under laboratory conditions at 10, 15, 20, 25 and 30°C. At all temperatures, survivorship was lower on T. evansi than on T. urticae. No predator reached adulthood at 10°C on the former species; even on the latter species, only about 36% of the predators reached adulthood at 10°C. For both prey, in general, duration of each life stage was shorter, total fecundity was lower and intrinsic rate of population increase (r _m ) was higher with increasing temperatures. The slower rate of development of P. fragariae on T. evansi resulted in a slightly higher thermal requirement (103.9 degree-days) on that prey than on T. urticae (97.1 degree-days). The values of net reproduction rate (R ₀), intrinsic rate of increase (r _m ) and finite rate of increase (λ) were significantly higher on T. urticae, indicating faster population increase of the predator on this prey species. The highest value of r _m of the predator was 0.154 and 0.337 female per female per day on T. evansi and on T. urticae, respectively. The results suggested that P. fragariae cannot be considered a good predator of T. evansi.     

Catalysts of Cu(II) and Co(II) ions adsorbed in chitosan used in transesterification of soy bean and babassu oils - a new route for biodiesel syntheses

Catalysts of Cu(II) and Co(II) adsorbed in chitosan was used in transesterification of soy bean and babassu oils. The catalysts were characterized by infrared, atomic absorption and TG, and biodiesels was characterized by infrared, NMR, CG, TG, physic chemistry analysis. The maximum adsorption values found for copper and cobalt cations were 1.584 and 1.260mgg(-1), respectively, in 180min. However, conversion of oils in biodiesel was better when used Co(II) adsorbed in chitosan.     

Antennae: the strongest magnetic part of the migratory ant

Pachycondyla marginata (P.m.), a migratory and termitophageous ant, hunting only the termite species Neocapritermes opacus, migrates significantly oriented 13 degrees with respect to the magnetic North-South axis. Results of hysteresis curves at room temperature of four Pachycondyla marginata heads, thorax, pairs of antennae and abdomens, oriented parallel to the magnetic field, indicate that the antennae give the strongest saturation magnetization, suggesting this sensory organ as being also a magnetic sensory organ. The total saturation magnetization in a whole P.m. is composed by 42 +/- 3%, 24 +/- 3%, 19 +/- 3% and 15 +/- 3% of antennae, head, thorax and abdomen contributions, respectively. The abdomen hysteresis curve presents a wasp-waisted loop with Hcr/Hc of 4.75, characteristic of mixed magnetic systems.     

Integrated approaches to studying Medicago truncatula genome structure and function and their applications in biotechnology

Plant genetic engineering has become an invaluable tool in plant research. Although plant transformation is a well-established technique, transgene expression is still unpredictable. Silencing may involve epigenetic modifications or nuclear and chromosomal localization of transgenes. In this way, understanding nuclear structure and organization is important not only for increasing our knowledge of fundamental aspects of the genome but also for taking the greatest advantage of inserting foreign genes and controlling their expression in biotechnological applications. Integrated approaches are clearly required in order to elucidate such complex processes. By combining the analysis of the physical position of transgenes with markers for epigenetic modifications in the plant genome we can better understand the factors affecting transgene expression levels and analyze the genomic environments of differentially expressed transgenes. Medicago truncatula Gaertn. has become a well-known model for the legume family and is used in studies ranging from nodulation to environmental stresses. More recently its use in biotechnology has been explored. In this report we describe the application of fluorescence in situ hybridization (FISH) to detect foreign DNA sequences and to determine the organization of the nucleolar organizer regions (NORs) genes in both metaphase chromosomes and interphase nuclei. We also studied chromatin distribution by immunodetection of epigenetic marks in M. truncatula interphase nuclei from tissue sections. We present evidence that M. truncatula is amenable to this kind of studies, which will in turn contribute to a better exploitation of biotechnology applications for this important plant family.     

Assessment of microsatellite instability in colorectal cancer patients from Brazil

The replication error status analysis of DNA, through microsatellite instability detection, has become an indispensable tool for hereditary non-polyposis colorectal cancer screening. This study investigated the microsatellite instability in Brazilian individuals presenting colorectal cancer. In this study, 66 patients were clinically analyzed according to Amsterdam II and Bethesda guidelines. Normal and tumour tissues were collected and analyzed for MSI degree according to molecular markers BAT25, BAT26, BAT40, APC–D5S346, D2S123, and D17S250. Eight patients (12.1%) fulfilled the Amsterdam II guidelines, and 15 (22.7%) met the Bethesda guidelines. BAT25 was the most sensitive marker (86.7%), while BAT26 was the least sensitive (66.7%). The specificity of both markers was 100%, but all of the markers must be used since the contribution of each marker to the sensitivity and specificity of the test is complementary. Proximal tumours were significantly predominant among RER⁺ patients. Conclusions: Patients with a family history of colorectal cancer with the tumour in the proximal colon must be screened to replication error status as early as possible in order to avoid the progression of the disease.