Microbial Growth under Supercritical CO2

Growth of microorganisms in environments containing CO₂ above its critical point is unexpected due to a combination of deleterious effects, including cytoplasmic acidification and membrane destabilization. Thus, supercritical CO₂ (scCO₂) is generally regarded as a sterilizing agent. We report isolation of bacteria from three sites targeted for geologic carbon dioxide sequestration (GCS) that are capable of growth in pressurized bioreactors containing scCO₂. Analysis of 16S rRNA genes from scCO₂ enrichment cultures revealed microbial assemblages of varied complexity, including representatives of the genus Bacillus. Propagation of enrichment cultures under scCO₂ headspace led to isolation of six strains corresponding to Bacillus cereus, Bacillus subterraneus, Bacillus amyloliquefaciens, Bacillus safensis, and Bacillus megaterium. Isolates are spore-forming, facultative anaerobes and capable of germination and growth under an scCO₂ headspace. In addition to these isolates, several Bacillus type strains grew under scCO₂, suggesting that this may be a shared feature of spore-forming Bacillus spp. Our results provide direct evidence of microbial activity at the interface between scCO₂ and an aqueous phase. Since microbial activity can influence the key mechanisms for permanent storage of sequestered CO₂ (i.e., structural, residual, solubility, and mineral trapping), our work suggests that during GCS microorganisms may grow and catalyze biological reactions that influence the fate and transport of CO₂ in the deep subsurface.     

Soil properties and geomorphic processes influence vegetation composition,structure, and function in the Cerrado Domain

Plant and Soil - The Cerrado of central Brazil—the world’s largest Neotropical savanna – is comprised of a mosaic of highly heterogeneous vegetation growing on an extremely...     

A further proteomic study on the effect of iron in the human pathogen Trichomonas vaginalis

Iron is an essential element to support the growth and survival of Trichomonas vaginalis. It plays a critical role in the host-parasite interaction, and modulates the expression of virulence factors in this protozoan. In this work, parasites grown in iron-rich and iron-depleted media were analyzed by (i) light and scanning electron microscopy and (ii) 2-DE and MS. Withdrawal of iron from the culture medium resulted in dramatic changes in both the morphology and in the proteome pattern of T. vaginalis. Trophozoites underwent transformation from ellipsoid or amoeboid forms to rounded cells, whose flagella and axostyle were internalized. Forty-five proteins differentially expressed in parasites cultivated in the absence of iron were identified. In iron-depleted parasites, enzymes involved in energetic metabolism, proteolysis and hydrogenosomal iron-sulfur (Fe-S) proteins were down-regulated or even suppressed. Among up-regulated proteins, six isoforms of actin were detected. In addition, phosphoenolpyruvate carboxykinase, putative lactate dehydrogenase, and putative adenosine triphosphatase were also up-regulated or were exclusively observed in gels related to iron-depleted parasites. Our data demonstrate that iron has a pivotal role in the regulation of the morphological transformation of T. vaginalis and modulates the expression of both Fe-S and non-Fe-S proteins in the parasite.     

Expression of NADPH oxidase in human pancreatic islets

AIMS: NADPH oxidase (NOX) is a known source of superoxide anions in phagocytic and non-phagocytic cells. In this study, the presence of this enzyme in human pancreatic islets and the importance of NADPH oxidase in human β-cell function were investigated. MAIN METHODS AND KEY FINDINGS: In isolated human pancreatic islets, the expression of NADPH oxidase components was evidenced by real-time PCR (p22(PHOX), p47(PHOX) and p67(PHOX)), Western blotting (p47(PHOX) and p67(PHOX)) and immunohistochemistry (p47(PHOX), p67(PHOX) and gp91(PHOX)). Immunohistochemistry experiments showed co-localization of p47(PHOX), p67(PHOX) and gp91(PHOX) (isoform 2 of NADPH oxidase-NOX2) with insulin secreting cells. Inhibition of NADPH oxidase activity impaired glucose metabolism and glucose-stimulated insulin secretion. SIGNIFICANCE: These findings demonstrate the presence of the main intrinsic components of NADPH oxidase comprising the NOX2 isoform in human pancreatic islets, whose activity also contributes to human β-cell function.     

How promising is <Emphasis Type="Italic">Lasioseius floridensis</Emphasis> as a control agent of <Emphasis Type="Italic">Polyphagotarsonemus</Emphasis><Emphasis Type="Italic">latus</Emphasis>?

The blattisociid mite Lasioseius floridensis Berlese was found associated with the broad mite, Polyphagotarsonemus latus (Banks), on gerbera leaves in Mogi das Cruzes, State of Sao Paulo, Brazil. Blattisociid mites are not common on aerial plant parts, except under high air humidity levels. Some Lasioseius species have been mentioned as effective control agents of rice pest mites, but nothing is known about the biology of L. floridensis. The objective of this study was to evaluate whether the observed co-occurrence of L. floridensis and P. latus was just occasional or whether the latter could be important as food source for the former, assumed by laboratory evaluation of the ability of the predator to maintain itself, reproduce and develop on that prey. Biological parameters of L. floridensis were compared when exposed to P. latus and to other items as food. The study showed that mating is a pre-requisite for L. floridensis to oviposit and that oviposition rate was much higher on the soil nematode Rhabditella axei (Cobbold) (Rhabditidae) than on P. latus. Ovipositon on the acarid mite Tyrophagus putrescentiae (Schrank) was about the same as on P. latus, but it was nearly zero when the predator was fed the fungi Aspergillus flavus Link or Penicillium sp., or cattail (Typha sp.) pollen. Survivorship was higher in the presence of pollen and lower in the presence of A. flavus or Penicillium sp. than in the absence of those types of food. Life table parameters indicated that the predator performed much better on R. axei than on P. latus. To evaluate the potential effect of L. floridensis as predator of P. latus, complementary studies are warranted to determine the frequency of migration of L. floridensis to aerial plant parts, when predation on P. latus could occur.     

Dehydroepiandrosterone increases beta-cell mass and improves the glucose-induced insulin secretion by pancreatic islets from aged rats

The effect of dehydroepiandrosterone (DHEA) on pancreatic islet function of aged rats, an animal model with impaired glucose-induced insulin secretion, was investigated. The following parameters were examined: morphological analysis of endocrine pancreata by immunohistochemistry; protein levels of insulin receptor, IRS-1, IRS-2, PI 3-kinase, Akt-1, and Akt-2; and static insulin secretion in isolated pancreatic islets. Pancreatic islets from DHEA-treated rats showed an increased beta-cell mass accompanied by increased Akt-1 protein level but reduced IR, IRS-1, and IRS-2 protein levels and enhanced glucose-stimulated insulin secretion. The present results suggest that DHEA may be a promising drug to prevent diabetes during aging.     

Modes of cell death in the pupal perivisceral fat body tissue of the silkworm Bombyx mori L.

Cell death is a scheduled event during animal development and tissue turnover. Here, we affirm the presence of two major pathways of programmed cell death (PCD), viz. apoptotic and autophagic cell death, in the disintegrated pupal perivisceral (PV) fat body during pupal-adult metamorphosis. The acridine orange (a vital stain for apoptosis) staining pattern and DNA fragmentation assay have revealed the exact day (6th day of the pupal stage) of disintegration in the PV fat body as represented by chromatin condensation and DNA laddering. Electron microscopy and scanning electron microscopy have demonstrated the presence of cytoplasmic budding and giant autophagic vacuoles and the low numbers of mitochondria, all of which are attributes of autophagic cell death. Immunoblot analysis of proteosomal subunits 20S and 26S has established the involvement of proteolytic activity during PCD of PV tissue. Lysosomal participation during the PCD of PV tissues has been confirmed by the elevated level of the marker enzyme, acid phosphatase, which is distinct on day 6 of the pupal period. The results of the present study have thus ascertained the co-existence of both autophagic and apoptotic cell death in PV fat body tissue.     

Iron modulates ecto-phosphohydrolase activities in pathogenic trichomonads

The presence of iron in the extracellular medium is essential for both in vivo and in vitro survival of pathogenic microorganisms, including Trichomonas vaginalis and Tritrichomonas foetus. In these parasites, iron is directly involved in the proliferation, protein expression and activation of critical enzymes. The purpose of this study was to investigate the role of iron in ecto-ATPase, ecto-phophatase and secreted phosphatase activities of these trichomonads. We observed that trichomonads grown in iron-depleted medium exhibited a remarkable decrease in both ecto-ATPase and ecto-phosphatase activities, when compared to those cultivated under control conditions (iron-rich medium). Furthermore, parasites grown in iron-depleted medium restored their enzyme activities when they were re-inoculated into fresh iron-rich medium. We demonstrated that modulation of ecto-phosphohydrolase activities is due neither to enzyme–iron nor to substrate–iron complex formation, since iron addition directly to the medium where the enzymatic reactions occurred did not alter their activities. Previously, we had reported that a fresh clinical isolate of T. vaginalis was much more cytotoxic to epithelial cell monolayers than a long-term cultured one. In this study we witnessed that the fresh isolate of T. vaginalis presented higher activities to all herein investigated enzymes than the long-term cultured one. Altogether, our data clearly point out that iron has a pivotal role in the expression of phosphohydrolases in both trichomonads.     

A new species of Sturisoma Swainson, 1838 (Loricariidae: Loricariinae), from the Madeira River basin,with a discussion of historical biogeography of western Amazonas and Paraguay River basins

A new loricariin species of Sturisoma is described from the Cautário, Guaporé, Mamoré, Machado and Soteiro rivers, Madeira River basin, in Bolivia and Brazil. The new species is distinguished from its congeners by the presence of a middorsal longitudinal, thin dark brown stripe on the caudal peduncle, extending from two or three plates posterior to the dorsal-fin base, reaching the origin of the caudal fin, or one or two plates anterior to the origin of the caudal fin; small squarish anteriormost abdominal plates; and a middorsal longitudinal dark-brown stripe from first predorsal plate to near the dorsal-fin origin. Furthermore, the new species is diagnosed from congeners by plate morphology, counts on the median series, coalescent plates and ventrolateral thoracic plates, in addition to measurements related to body and head structures. An analysis of genetic distances using cytochrome C oxidase subunit 1 gene marker of the mitochondrial genome between the new species and several congeners is presented, in addition to a likelihood analysis to illustrate the position of the new taxon within Sturisoma. An identification key for species of the genus currently recorded at the upper Amazonas River basin is provided.