Characteristics of Environmental <Emphasis Type="Italic">Paracoccidioides brasiliensis</Emphasis> Isolates

The ecological niche or exact habitat of the fungus Paracoccidioides brasiliensis is not known, and few isolates have been obtained from the environment. In this study, ten isolates were analyzed with respect to antigenic composition, serology, pathogenicity, and molecular aspects. Gp43 is considered to be the molecular basis for the serodiagnosis of paracoccidioidomycosis; however, in this study only six of the environmental isolates secreted this molecule (four in great amounts and two in small amounts). Other molecules were also produced. When exoantigens from these isolates were tested using immunodiffusion, only four preparations were positive by ID tests. However, when these exoantigens were tested by ELISA, all of them except one were able to detect anti-P. brasiliensis antibodies. In Western blot assays, these exoantigens showed different reactivities. Isolates that secreted gp43 presented positive reactions for this molecule, and isolates that did not secrete gp43 gave positive reactions for other minor molecules. RAPD analysis revealed that there is great genetic variation between these environmental isolates. These isolates were non-pathogenic: no mortality was observed among the inoculated mice during an 18-month follow-up period.     

Genome physical mapping from large-insert clones by fingerprint analysis with capillary electrophoresis: a robust physical map of Penicillium chrysogenum

Physical mapping with large-insert clones is becoming an active area of genomics research, and capillary electrophoresis (CE) promises to revolutionize the physical mapping technology. Here, we demonstrate the utility of the CE technology for genome physical mapping with large-insert clones by constructing a robust, binary bacterial artificial chromosome (BIBAC)-based physical map of Penicillium chrysogenum. We fingerprinted 23.1× coverage BIBAC clones with five restriction enzymes and the SNaPshot kit containing four fluorescent-ddNTPs using the CE technology, and explored various strategies to construct quality physical maps. It was shown that the fingerprints labeled with one or two colors, resulting in 40–70 bands per clone, were assembled into much better quality maps than those labeled with three or four colors. The selection of fingerprinting enzymes was crucial to quality map construction. From the dataset labeled with ddTTP–dROX, we assembled a physical map for P.chrysogenum, with 2–3 contigs per chromosome and anchored the map to its chromosomes. This map represents the first physical map constructed using the CE technology, thus providing not only a platform for genomic studies of the penicillin-producing species, but also strategies for efficient use of the CE technology for genome physical mapping of plants, animals and microbes.     

Holozygosity for sex-linked genes in males of the termiteIncisitermes schwarzi

The termite Incisitermes schwarzi has multiple sex chromosomes that have arisen by repeated translocations between autosomes and previously existing sex chromosomes. Two sex-linked allozyme loci--Acp-1 and Est-3--are holozygous, not hemizygous, in males (the heterogametic sex). Both loci show less than 1% crossing-over between X and Y chromosomes, and alleles of both are in marked disequilibrium with respect to X vs Y linkage. The two loci assort independently in female meiosis, indicating that they lie on different sex chromosomes. But they are tightly linked in male meiosis because of nonrandom assortment of the multiple X and Y chromosomes in males of this species. The findings of holozygosity and strong linkage disequilibrium suggest that differential selection in the two sexes at or near these loci may be responsible for the establishment of the translocations in this species. The existence of active Y-linked alleles also suggests that the translocations may have occurred recently.     

Essential oils from Azorean Laurus azorica

The essential oils isolated from leaves of ten and from unripe berries of eight populations of Laurus azorica (Seub.) Franco, collected on five islands of the Azorean archipelago, were analysed by GC and GC-MS. All oil samples were dominated by their monoterpene fraction (60-94%), alpha-pinene (15-37%) and 1,8-cineole (12-31%) being the main components of the leaf oils, while trans-beta-ocimene (27-45%) and alpha-pinene (12-22%) were the main components of the oils from the berries. The sesquiterpene fractions of the oils ranged from 3 to 17% and the main components were beta-caryophyllene (traces-8%) and beta-elemene (traces-3%) both in the leaf and berry oils. Some phenylpropanoid components were also present, in total amounting to 17%, trans-cinnamyl acetate (215% of the leaf oils) being the main component of this fraction. Cluster analysis of the enantiomeric composition of alpha- and beta-pinene in the oils from the leaves clearly showed two groups, one constituted by the two populations growing on the island S. Jorge, and the other constituted by the remaining populations.     

Inulavosin and its benzo‐derivatives,melanogenesis inhibitors,target the copper loading mechanism to the active site of tyrosinase

Tyrosinase, a melanosomal membrane protein containing copper, is a key enzyme for melanin synthesis in melanocytes. Inulavosin inhibits melanogenesis by enhancing a degradation of tyrosinase in lysosomes. However, the mechanism by which inulavosin redirects tyrosinase to lysosomes is yet unknown. The analyses of structure–activity relationship of inulavosin and its benzo‐derivatives reveal that the hydroxyl and the methyl groups play a critical role in their inhibitory activity. Intriguingly, the docking studies to tyrosinase suggest that the compounds showing inhibitory activity bind through hydrophobic interactions to the cavity of tyrosinase below which the copper‐binding sites are located. This cavity is proposed to be required for the association with a chaperon that assists in copper loading to tyrosinase in Streptomyces antibioticus. Inulavosin and its benzo‐derivatives may compete with the copper chaperon and result in a lysosomal mistargeting of apo‐tyrosinase that has a conformational defect.     

Dengue virus type 3 isolated from a fatal case with visceral complications induces enhanced proinflammatory responses and apoptosis of human dendritic cells

A recent (2007 to 2009) dengue outbreak caused by dengue virus (DENV) in Paraguay presented unusual severe clinical outcomes associated with 50% mortality rates. Although it has been reported that inflammatory responses influence the severity of dengue virus infection (T. Pang, M. J. Cardosa, and M. G. Guzman, Immunol. Cell Biol. 85:43-45, 2007), there remains a paucity of information on virus-innate immunity interactions influencing clinical outcome. Using human dendritic cells from a major innate immune cell population as an in vitro model, we have investigated signature cytokine responses as well as infectivity-replicative profiles of DENV clinical isolates from either a nonfatal case of classical dengue fever (strain DENV3/290; isolated in Brazil in 2002) or a fatal case of dengue fever with visceral complications isolated in Paraguay in 2007 (strain DENV3/5532). Strain DENV3/5532 was found to display significantly higher replicative ability than DENV3/290 in monocyte-derived dendritic cells (mdDCs). In addition, compared to DENV3/290 results, mdDCs exposed to DENV3/5532 showed increased production of proinflammatory cytokines associated with higher rates of programmed cell death, as shown by annexin V staining. The observed phenotype was due to viral replication, and tumor necrosis factor alpha (TNF-α) appears to exert a protective effect on virus-induced mdDC apoptosis. These results suggest that the DENV3/5532 strain isolated from the fatal case replicates within human dendritic cells, modulating cell survival and synthesis of inflammatory mediators.     

Carbohydrate accumulation and utilization by oocytes of Rhodnius prolixus

The processes of accumulation and mobilization of carbohydrate stores in eggs of Rhodnius prolixus were analyzed. During oogenesis, the total amounts of glycogen, glucose, and trehalose increased with an accumulation of proteins, especially when oocytes grew from 1.0 to 1.5 mm in length. At 2.0 mm length, when oocytes were ready for oviposition, nutrient reserves did not increase appreciably and trehalose content decreased. Mating did not affect the final content of carbohydrates or proteins in oocytes of mated and virgin females. A trehalase activity was detected in follicles containing vitellogenic oocytes, 1.0 and 1.5 mm length, in both mated and virgin females. This activity was extremely low in chorionated, 2.0-mm oocytes. After oviposition, glycogen content decreased in fertilized eggs, but not in unfertilized ones, and some was present in newly hatched nymphs. Glucose content remained constant in unfertilized eggs, but increased in fertilized ones, while total protein amount was constant in both groups after egg laying.     

Does Fire Trigger Seed Germination in the Neotropical Savannas? Experimental Tests with Six Cerrado Species

The Cerrado (Brazilian savanna) is a biodiversity hotspot with a history of fire that goes back as far as 10 million years. Fire has influenced the evolution of several aspects of the vegetation, including reproduction and life cycles. This study tested how fire by‐products such as heat and smoke affect the germination of six species common to two Cerrado open physiognomies: wet grasslands and the campo sujo (grassland with scattered shrubs and dwarf trees). We subjected seeds collected in northern Brazil to heat shock and smoke treatments, both separately and combined, using different temperatures, exposure times, and smoke concentrations in aqueous solutions. High temperatures and smoke did not break seed dormancy nor stimulate germination of the Cerrado study species. However, seeds were not killed by high temperatures, indicating that they are fire‐tolerant. Our findings differed from those of other fire‐prone ecosystems (mostly of Mediterranean vegetation), where fire stimulates germination. Moreover, we provide important information regarding germination strategies of non‐woody Cerrado plants, showing the importance of considering the tolerance of seeds to high temperatures when evaluating fire‐related traits in fire‐prone ecosystems.