Yeast diversity in rice-cassava fermentations produced by the indigenous Tapirapé people of Brazil

The Tapirapé people of the Tapi'it?wa tribe of Brazil produce several fermented foods and beverages, one of which is called 'cauim'. This beverage usually makes up the main staple food for adults and children. Several substrates are used in its production, including cassava, rice, corn, maize and peanuts. A fermentation using rice and cassava was conducted, and samples were collected at 4-h intervals for microbial analysis. The yeast population was low at the beginning of the fermentation and reached 6.9 x 10(7) CFU mL(-1) after 48 h. During the fermentation process common yeast species were identified by sequencing of the D1/D2 domain of the large-subunit (26S) rRNA gene. The predominant yeast species found was Candida tropicalis. Candida intermedia, Candida parapsilosis, Pichia guilliermondii, Saccharomyces cerevisiae and Trichosporon asahii were also found in high numbers during the fermentation. Exophiala dermatidis, often associated with blastomycosis, was found in the mass before inoculation and during the initial stages of the fermentation. Examination of these indigenous fermented foods may provide clues as to how food production and preservation can be expanded and thereby contribute to improve nutrition in native tribes in the region.     

Intraspecific differences of Asian/Australian Phragmites australis subgroups reveal no potentially invasive traits

Hydrobiologia - Phragmites australis is a cosmopolitan plant species with high intraspecific diversity and phenotypic plasticity. Due to its variability and large ecological niche breadth,...     

Roles of plasma membrane proton ATPases AHA2 and AHA7 in normal growth of roots and root hairs in Arabidopsis thaliana

Plasma membrane H⁺‐ATPase pumps build up the electrochemical H⁺ gradients that energize most other transport processes into and out of plant cells through channel proteins and secondary active carriers. In Arabidopsis thaliana, the AUTOINHIBITED PLASMA MEMBRANE H⁺‐ATPases AHA1, AHA2 and AHA7 are predominant in root epidermal cells. In contrast to other H⁺‐ATPases, we find that AHA7 is autoinhibited by a sequence present in the extracellular loop between transmembrane segments 7 and 8. Autoinhibition of pump activity was regulated by extracellular pH, suggesting negative feedback regulation of AHA7 during establishment of an H⁺ gradient. Due to genetic redundancy, it has proven difficult to test the role of AHA2 and AHA7, and mutant phenotypes have previously only been observed under nutrient stress conditions. Here, we investigated root and root hair growth under normal conditions in single and double mutants of AHA2 and AHA7. We find that AHA2 drives root cell expansion during growth but that, unexpectedly, restriction of root hair elongation is dependent on AHA2 and AHA7, with each having different roles in this process.     

Diffusion-weighted MRI and quantitative biophysical modeling of hippocampal neurite loss in chronic stress

Chronic stress has detrimental effects on physiology, learning and memory and is involved in the development of anxiety and depressive disorders. Besides changes in synaptic formation and neurogenesis, chronic stress also induces dendritic remodeling in the hippocampus, amygdala and the prefrontal cortex. Investigations of dendritic remodeling during development and treatment of stress are currently limited by the invasive nature of histological and stereological methods. Here we show that high field diffusion-weighted MRI combined with quantitative biophysical modeling of the hippocampal dendritic loss in 21 day restraint stressed rats highly correlates with former histological findings. Our study strongly indicates that diffusion-weighted MRI is sensitive to regional dendritic loss and thus a promising candidate for non-invasive studies of dendritic plasticity in chronic stress and stress-related disorders.     

Evolutionary and experimental analyses of inorganic phosphate transporter PiT family reveals two related signature sequences harboring highly conserved aspartic acids critical for sodium-dependent phosphate transport function of human PiT2

The mammalian members of the inorganic phosphate (P(i)) transporter (PiT) family, the type III sodium-dependent phosphate (NaP(i)) transporters PiT1 and PiT2, have been assigned housekeeping P(i) transport functions and are suggested to be involved in chondroblastic and osteoblastic mineralization and ectopic calcification. The PiT family members are conserved throughout all kingdoms and use either sodium (Na+) or proton (H+) gradients to transport P(i). Sequence logo analyses revealed that independent of their cation dependency these proteins harbor conserved signature sequences in their N- and C-terminal ends with the common core consensus sequence GANDVANA. With the exception of 10 proteins from extremophiles all 109 proteins analyzed carry an aspartic acid in one or both of the signature sequences. We changed either of the highly conserved aspartates, Asp28 and Asp506, in the N- and C-terminal signature sequences, respectively, of human PiT2 to asparagine and analyzed P(i) uptake function in Xenopus laevis oocytes. Both mutant proteins were expressed at the cell surface of the oocytes but exhibited knocked out NaP(i) transport function. Human PiT2 is also a retroviral receptor and we have previously shown that this function can be exploited as a control for proper processing and folding of mutant proteins. Both mutant transporters displayed wild-type receptor functions implying that their overall architecture is undisturbed. Thus the presence of an aspartic acid in either of the PiT family signature sequences is critical for the Na+-dependent P(i) transport function of human PiT2. The conservation of the aspartates among proteins using either Na+- or H+-gradients for P(i) transport suggests that they are involved in H+-dependent P(i) transport as well. Current results favor a membrane topology model in which the N- and C-terminal PiT family signature sequences are positioned in intra- and extracellular loops, respectively, suggesting that they are involved in related functions on either side of the membrane. The present data are in agreement with a possible role of the signature sequences in translocation of cations.     

PCR-RFLP is used to investigate relations among species in the entomopathogenic genera Eryniopsis and Entomophaga

The shape and nucleation of primary conidia are important characters in the classification of the Entomophthoraceae (Zygomycetes). The five species in the genus Eryniopsis vary in the shapes of primary conidia, although within most genera in the order Entomophthorales species have the same shapes of primary conidia. Using PCR-RFLP, we investigated two species in Eryniopsis, Ery. caroliniana with oblong-ovoid primary conidia and Ery. ptychopterae with pear-shaped primary conidia, with five species of Entomophaga, all having pear-shaped conidia. Molecular results merged with morphological data indicate that Ery. ptychopterae belongs in the genus Entomophaga while Ery. caroliniana clearly differs from Entomophaga. Ery. ptychopterae and Ery. transitans are transferred to the genus Entomophaga. Our results support the idea that morphology of primary conidia is of major importance in defining entomophthoralean genera. These results also show that such studies can be conducted with species that have not been isolated, if fungal-filled cadavers can be obtained.     

Effects of exposure to 17alpha-ethinylestradiol during early development on sexual differentiation and induction of vitellogenin in zebrafish (Danio rerio)

The effect of acute stress on plasma beta-corticosterone (B), testosterone (T) and estradiol-17beta (E2) concentrations in juvenile alligators collected from sites with varying sediment contaminants was examined in this study. Dramatic increases in plasma B concentrations were observed in alligators from all of the sites after 2 h of capture although females from the intermediate contaminant site exhibited a significantly lower percentage increase in B than females from the other two sites. Males from the site with the highest contaminant levels exhibited elevated initial B concentrations relative to the other sites. This pattern was not observed after 2 h of restraint. Females from the highest contaminant site exhibited depressed initial T when compared to the other sites although this pattern was not observed after 2 h of restraint. Neither E2 nor T decreased after 2 h in females, whereas T concentrations decreased in all males over the same time period. The variance associated with these endpoints was also examined to determine whether it could serve as a more sensitive marker for perturbations of the endocrine system and stress response. Females from the higher and intermediate contaminant sites exhibited the lowest and highest standard errors (respectively) associated with 2 h plasma B concentrations with no differences among mean concentrations suggesting a perturbation of the stress response in these animals that was not detected by examining the means. We concluded that the environmental contaminants could be acting as stressors, leading to the observed differences.     

Competition between Pseudomonas fluorescens Ag1 and Alcaligenes eutrophus JMP134 (pJP4) during colonization of barley roots

Abstract: To use deliberately released beneficial microorganisms in the rhizosphere, we need a better understanding of the process of root colonization by seed-borne or soil-borne inocula. In this study, we determine the survival of Pseudomonas fluorescens Ag1 and Alcaligenes eutrophus JMP134, their colonization ability as affected by substrates, and the relative importance of migration versus competition for colonization of the root. Ag1 and the 2,4-dichlorophenoxy-acetic acid (2,4-D) degrader JMP134 were inoculated in sterile barley rhizosphere systems. After inoculation of seeds with individual strains, comparable population sizes were established in the rhizosphere as determined by immunofluorescence microscopic total cell counts. Both strains were motile and able to colonize the entire root system without percolating water to stimulate passive transport. Comparing immunofluorescence microscopic cell counts with colony-forming units demonstrated that a subpopulation of A. eutrophus JMP134 closely associated with the root was non-culturable in contrast to the population in rhizosphere soil. Hence, the sole use of culture-dependent methods may give misleading information about the distribution of bacteria in the rhizosphere. Colonization studies with both strains showed that co-inoculation of Ag1 and JMP134 caused a decrease of the population size of JMP134 if 2,4-D was not added to the soil as a specific carbon source for this strain. Thus, competition for limited carbon sources might influence the composition of the bacterial community in the rhizosphere. We also found that the presence of an established inoculum in the soil reduced subsequent root colonization by a seed-inoculated strain, probably by filling available niches, also indicating that competition from other bacteria may be an important factor determining the distribution of seed-borne inocula. This factor may be just as important for the distribution of bacteria as migration.     

Assessment of the postoperative discomfort of intra-auricularly hypophysectomized rats

Rats subjected to hypophysectomy make up one of the largest groups of experimental animals in Europe, since there is a legal demand for batch testing of industrially produced growth hormones. To describe the clinical performance of rats having undergone hypophysectomy, animals were examined postoperatively by monitoring behaviour, body temperature and food intake. Behavioural changes were observed in rats that had only been anaesthetized, as well as in sham-operated rats, while no behavioural deviations could be shown in hypophysectomized rats. On the first day after surgery all rats had declining body temperature and food intake; and this change was not reversed by treatment with carprofen, buprenorphine or oxytetracycline. The mortality rate in rats treated with buprenorphine was increased, as was the mortality rate in rats hypophysectomized when weighing more than 100 g. As there seemed to be no differences whether methohexital or a combination of fentanyl, fluanison and midazolam was used, the latter anaesthesia is recommended due to its analgesic potential. For post-surgical analgesic treatment, carprofen is recommended rather than buprenorphine. At best, the use of hypophysectomized rats should be replaced in industrial batch testing by an existing in vitro method.     

Characterization of glucagon-like peptide-1 receptor beta-arrestin 2 interaction: a high-affinity receptor phenotype

To dissect the interaction between beta-arrestin ((beta)arr) and family B G protein-coupled receptors, we constructed fusion proteins between the glucagon-like peptide 1 receptor and (beta)arr2. The fusion constructs had an increase in apparent affinity selectively for glucagon, suggesting that (beta)arr2 interaction locks the receptor in a high-affinity conformation, which can be explored by some, but not all, ligands. The fusion constructs adopted a signaling phenotype governed by the tethered (beta)arr2 with an attenuated G protein-mediated cAMP signal and a higher maximal internalization compared with wild-type receptors. This distinct phenotype of the fusion proteins can not be mimicked by coexpressing wild-type receptor with (beta)arr2. However, when the wild-type receptor was coexpressed with both (beta)arr2 and G protein-coupled receptor kinase 5, a phenotype similar to that observed for the fusion constructs was observed. We conclude that the glucagon-like peptide 1 fusion construct mimics the natural interaction of the receptor with (beta)arr2 with respect to binding peptide ligands, G protein-mediated signaling and internalization, and that this distinct molecular phenotype is reminiscent of that which has previously been characterized for family A G protein-coupled receptors, suggesting similarities in the effect of (beta)arr interaction between family A and B receptors also at the molecular level.