Characterization of low phosphorus insensitive mutants reveals a crosstalk between low phosphorus-induced determinate root development and the activation of genes involved in the adaptation of Arabidopsis to phosphorus deficiency

Low phosphorus (P) availability is one of the most limiting factors for plant productivity in many natural and agricultural ecosystems. Plants display a wide range of adaptive responses to cope with low P stress, which generally serve to enhance P availability in the soil and to increase its uptake by roots. In Arabidopsis (Arabidopsis thaliana), primary root growth inhibition and increased lateral root formation have been reported to occur in response to P limitation. To gain knowledge of the genetic mechanisms that regulate root architectural responses to P availability, we designed a screen for identifying Arabidopsis mutants that fail to arrest primary root growth when grown under low P conditions. Eleven low phosphorus insensitive (lpi) mutants that define at least four different complementation groups involved in primary root growth responses to P availability were identified. The lpi mutants do not show the typical determinate developmental program induced by P stress in the primary root. Other root developmental aspects of the low P rescue system, including increased root hair elongation and anthocyanin accumulation, remained unaltered in lpi mutants. In addition to the insensitivity of primary root growth inhibition, when subjected to P deprivation, lpi mutants show a reduced induction in the expression of several genes involved in the P starvation rescue system (PHOSPHATE TRANSPORTER 1 and 2, PURPLE ACID PHOSPHATASE 1, ACID PHOSPHATASE 5, and INDUCED BY PHOSPHATE STARVATION 1). Our results provide genetic support for the role of P as an important signal for postembryonic root development and root meristem maintenance and show a crosstalk in developmental and biochemical responses to P deprivation.     

Microbial diversity in Maras salterns, a hypersaline environment in the Peruvian Andes

Maras salterns are located 3,380 m above sea level in the Peruvian Andes. These salterns consist of more than 3,000 little ponds which are not interconnected and act as crystallizers where salt precipitates. These ponds are fed by hypersaline spring water rich in sodium and chloride. The microbiota inhabiting these salterns was examined by fluorescence in situ hybridization (FISH), 16S rRNA gene clone library analysis, and cultivation techniques. The total counts per milliliter in the ponds were around 2 x 10(6) to 3 x 10(6) cells/ml, while the spring water contained less than 100 cells/ml and did not yield any detectable FISH signal. The microbiota inhabiting the ponds was dominated (80 to 86% of the total counts) by Archaea, while Bacteria accounted for 10 to 13% of the 4',6'-diamidino-2-phenylindole (DAPI) counts. A total of 239 16S rRNA gene clones were analyzed (132 Archaea clones and 107 Bacteria clones). According to the clone libraries, the archaeal assemblage was dominated by microorganisms related to the cosmopolitan square archaeon "Haloquadra walsbyi," although a substantial number of the sequences in the libraries (31% of the 16S rRNA gene archaeal clones) were related to Halobacterium sp., which is not normally found in clone libraries from solar salterns. All the bacterial clones were closely related to each other and to the gamma-proteobacterium "Pseudomonas halophila" DSM 3050. FISH analysis with a probe specific for this bacterial assemblage revealed that it accounted for 69 to 76% of the total bacterial counts detected with a Bacteria-specific probe. When pond water was used to inoculate solid media containing 25% total salts, both extremely halophilic Archaea and Bacteria were isolated. Archaeal isolates were not related to the isolates in clone libraries, although several bacterial isolates were very closely related to the "P. halophila" cluster found in the libraries. As observed for other hypersaline environments, extremely halophilic bacteria that had ecological relevance seemed to be easier to culture than their archaeal counterparts.     

Raptor-rictor axis in TGFbeta-induced protein synthesis

Transforming growth factor-beta (TGFbeta) stimulates pathological renal cell hypertrophy for which increased protein synthesis is critical. The mechanism of TGFbeta-induced protein synthesis is not known, but PI 3 kinase-dependent Akt kinase activity is necessary. We investigated the contribution of downstream effectors of Akt in TGFbeta-stimulated protein synthesis. TGFbeta increased inactivating phosphorylation of Akt substrate tuberin in a PI 3 kinase/Akt dependent manner, resulting in activation of mTOR kinase. mTOR activity increased phosphorylation of S6 kinase and the translation repressor 4EBP-1, which were sensitive to inhibition of both PI 3 kinase and Akt. mTOR inhibitor rapamycin and a dominant negative mutant of mTOR suppressed TGFbeta-induced phosphorylation of S6 kinase and 4EBP-1. PI 3 kinase/Akt and mTOR regulated dissociation of 4EBP-1 from eIF4E to make the latter available for binding to eIF4G. mTOR and 4EBP-1 modulated TGFbeta-induced protein synthesis. mTOR is present in two multi protein complexes, mTORC1 and mTORC2. Raptor and rictor are part of mTORC1 and mTORC2, respectively. shRNA-mediated downregulation of raptor inhibited TGFbeta-stimulated mTOR kinase activity, resulting in inhibition of phosphorylation of S6 kinase and 4EBP-1. Raptor shRNA also prevented protein synthesis in response to TGFbeta. Downregulation of rictor inhibited serine 473 phosphorylation of Akt without any effect on phosphorylation of its substrate, tuberin. Furthermore, rictor shRNA increased phosphorylation of S6 kinase and 4EBP-1 in TGFbeta-independent manner, resulting in increased protein synthesis. Thus mTORC1 function is essential for TGFbeta-induced protein synthesis. Our data also provide novel evidence that rictor negatively regulates TORC1 activity to control basal protein synthesis, thus conferring tight control on cellular hypertrophy.     

Impact of long-term treatment with ivermectin on the prevalence and intensity of soil-transmitted helminth infections

Background

Control of soil-transmitted helminth (STH) infections relies on the periodic and long-term administration of anthelmintic drugs to high-risk groups, particularly school-age children living in endemic areas. There is limited data on the effectiveness of long-term periodic anthelmintic treatment on the prevalence of STHs, particularly from operational programmes. The current study investigated the impact of 15 to 17 years of treatment with the broad-spectrum anthelmintic ivermectin, used for the control of onchocerciasis, on STH prevalence and intensity in school-age and pre-school children.

Methods and Findings

A cross-sectional study was conducted in communities that had received annual or twice-annual ivermectin treatments and geographically adjacent communities that had not received treatment in two districts of Esmeraldas Province in Ecuador. Stool samples were collected from school-age children and examined for STH infection using the Kato-Katz and formol-ether concentration methods. Samples were collected also from pre-school children and examined by the formol-ether concentration method. Data on risk factors for STH infection were collected by parental questionnaire. We sampled a total of 3,705 school-age children (6–16 years) from 31 treated and 27 non-treated communities, and 1,701 pre-school children aged 0–5 years from 18 treated and 18 non-treated communities. Among school-age children, ivermectin treatment had significant effects on the prevalence (adjusted OR =  0.06, 95% CI 0.03–0.14) and intensity of Trichuris trichiura infection (adjusted RR = 0.28, 95% CI 0.11–0.70), but appeared to have no impact on Ascaris lumbricoides or hookworm infection. Reduced prevalence and intensities of T. trichiura infection were observed among children not eligible to receive ivermectina, providing some evidence of reduced transmission of T. trichiura infection in communities receiving mass ivermectin treatments.

Conclusion

Annual and twice-annual treatments with ivermectin over a period of up to 17 years may have had a significant impact on T. trichiura infection. The present data indicate that the long-term control of onchocerciasis with ivermectin may provide additional health benefits by reducing infections with trichuriasis. The addition of a second anthelmintic drug such as albendazole may be useful for a long-term effect on A. lumbricoides infection.     

Design and synthesis of an indol derivative as antibacterial agent against <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>

Several indole derivatives with antibacterial activity have been prepared using different protocols; however, some require special reagents and conditions. The aim of this study involved the synthesis of some indole derivatives using estrone and OTBS-estrone as chemical tools. The synthesis of the indole derivatives involves reactions such as follows: (1) synthesis of two indol derivatives (4 or 5) by reaction of estrone or OTBS-estrone with phenylhydrazine in medium acid; (2) reaction of 4 or 5 with 6-cloro-1-hexyne in medium basic to form two hexynyl-indol (7 or 8); (3) preparation of indol-propargylic alcohol derivatives (10 or 11) by reaction of benzaldehyde with 7 or 8 in medium basic; (4) synthesis of indol-aldehydes (12 or 13) via oxidation of 10 or 11 with DMSO; (5) synthesis of indeno-indol-carbaldehyde (15 or 16) via alkynylation/cyclization of 12 or 13 with hexyne in presence of copper(II); (6) preparation indeno-indol-carbaldehyde complex (19 or 20) via alkynylation/cyclization of 12 or 13 with 1-(hex-5-yn-1-yl)-2-phenyl-1H-imidazole. The antibacterial effect exerted by the indol-steroid derivatives against Streptococcus pneumoniae and Staphylococcus aureus bacteria was evaluated using dilution method and the minimum inhibitory concentration (MIC). The results showed that only the compound 19 inhibit the growth bacterial of S. aureus. In conclusion, these data indicate that antibacterial activity of 19 can be due mainly to functional groups involved in the chemical structure in comparison with the compounds studied.     

Androgens Exert a Cysticidal Effect upon Taenia crassiceps by Disrupting Flame Cell Morphology and Function

The effects of testosterone (T₄) and dihydrotestosterone (DHT) on the survival of the helminth cestode parasite Taenia crassiceps, as well as their effects on actin, tubulin and myosin expression and their assembly into the excretory system of flame cells are described in this paper. In vitro evaluations on parasite viability, flow cytometry, confocal microscopy, video-microscopy of live flame cells, and docking experiments of androgens interacting with actin, tubulin, and myosin were conducted. Our results show that T₄ and DHT reduce T. crassiceps viability in a dose- and time-dependent fashion, reaching 90% of mortality at the highest dose used (40 ng/ml) and time exposed (10 days) in culture. Androgen treatment does not induce differences in the specific expression pattern of actin, tubulin, and myosin isoforms as compared with control parasites. Confocal microscopy demonstrated a strong disruption of the parasite tegument, with reduced assembly, shape, and motion of flame cells. Docking experiments show that androgens are capable of affecting parasite survival and flame cell morphology by directly interacting with actin, tubulin and myosin without altering their protein expression pattern. We show that both T₄ and DHT are able to bind actin, tubulin, and myosin affecting their assembly and causing parasite intoxication due to impairment of flame cell function. Live flame cell video microscopy showing a reduced motion as well changes in the shape of flame cells are also shown. In summary, T₄ and DHT directly act on T. crassiceps cysticerci through altering parasite survival as well as the assembly and function of flame cells.     

Comparison of two populations of Pseudophilothrips ichini (Thysanoptera: Phlaeothripidae) as candidates for biological control of the invasive weed Schinus terebinthifolia (Sapindales: Anacardiaceae)

Brazilian peppertree, Schinus terebinthifolia Raddi (Sapindales: Anacardiaceae) (hereafter Schinus), is one of the worst invasive species in Florida and Hawaii. The thrips Pseudophilothrips ichini Hood (Thysanoptera: Phlaeothripidae) is being considered as a potential biological control agent of Schinus. Two populations of this thrips were collected in the weed's native range; one from central-east Brazil (Ouro Preto thrips) and a second from north-east Brazil (Salvador thrips). Temperature requirements, adult fecundity and impact on different plant haplotypes by P. ichini were examined in the laboratory. Complete development of thrips from both populations occurred at temperatures ranging from 20 to 30°C. Two approaches were used to model the predicted distributions of the thrips populations in the USA: the physiological model (NAPPFAST) based on cold tolerance and the ecological niche model based on climatic variables (MaxEnt). The physiological model predicted that both populations of P. ichini may establish in similar areas of the USA, overlapping with the distribution of Schinus. However, the niche model predicted that only the Ouro Preto thrips could establish in the USA. The difference in model predictions suggests an apparent preadaptation of the Salvador thrips to lower temperatures than those experienced at the locations they were collected in Brazil. The Ouro Preto thrips had similar fecundity on two Florida Schinus haplotypes, whereas lower fecundity on haplotype A was found for the Salvador thrips. Based on these results, the Ouro Preto population may be better adapted to the climatic conditions and plant haplotypes found in Florida. Moreover, greenhouse studies indicated that Schinus growth was greatly reduced by thrips feeding, which may result in lower weed reproduction and densities in the field.     

Strain selection for β-carotene production by Dunaliella

Four strains of Dunaliella were grown at 25°C and pH 8±0.5, with continous illumination at 200 W/m². Their maximum specific growth rates ranged from 0.093 day^-1 to 0.234 day^-1, nitrate yields from 3.0 to 7.8 g cells/g NaNO₃ and lipid contents from 3% to 6% of the dry wt, with carotenes 50 to 80% of the lipids. Of the carotenes, -carotene made up 7 to 19%; all-trans--carotene 32 to 52% and 9-cis--carotene 29 to 55%. There are, therefore, considerable intra-specific differences between strains of Dunaliella.     

East with the Night: Longitudinal Migration of the Orinoco Goose (Neochen jubata) between Manú National Park,Peru and the Llanos de Moxos,Bolivia

We report on the intra-Amazonian migration of a pair of Orinoco Geese (Neochen jubata) from Manú National Park, Peru. The species is Critically Endangered in Peru, so a major aim of the study was to aid conservation planning by learning the wet season location of the country''s last known breeding population. We captured a breeding pair on October 27, 2010, and fitted the birds with Microwave Telemetry, Inc. GPS/Argos satellite PTT''s. The pair migrated ∼655 km from Manú National Park to the Llanos de Moxos, Bolivia (Dept. of Bení) in a predominantly longitudinal migration, reaching their final destination on December 23, 2010. Major movements (>5 km per time period) were almost exclusively at night and were undertaken with and without moonlight. Foraging areas used at stopovers in the Llanos de Moxos were remarkably limited, suggesting the importance of grazing lawns maintained by the geese and other herbivores, possibly including cattle. Orinoco Geese are resident in the Llanos de Moxos year-round, so the Manú geese represent a partial migration from the Bení region. We hypothesize that cavity nest limitation explains the partial migration of Orinoco Geese from the Llanos de Moxos.