A host-targeting signal in virulence proteins reveals a secretome in malarial infection

Malaria parasites secrete proteins across the vacuolar membrane into the erythrocyte, inducing modifications linked to disease and parasite survival. We identified an 11-amino acid signal required for the secretion of proteins from the Plasmodium falciparum vacuole to the human erythrocyte. Bioinformatics predicted a secretome of >320 proteins and conservation of the signal across parasite species. Functional studies indicated the predictive value of the signal and its role in targeting virulence proteins to the erythrocyte and implicated its recognition by a receptor/transporter. Erythrocyte modification by the parasite may involve plasmodial heat shock proteins and be vastly more complex than hitherto realized.     

Simulating coconut growth, development and yield with the InfoCrop-coconut model

Simulation modeling of perennial crops has immense potential for generating information for plantation managers. We report the development of the InfoCrop-coconut model and its application to coconut (Cocos nucifera L.) growing in diverse tropical and subtropical environments. The model is based on the generic crop model InfoCrop that simulates various annual crops in tropical and subtropical regions. The InfoCrop-coconut model was calibrated and validated with data compiled from published studies comprising many physiological, agronomical and nutritional experiments conducted between 1978 and 2005 in diverse geographic locations throughout India. The treatments included various water and nutrient regimes and varieties of coconut. Time to first flowering varied between 4 and 6 years, leaf production varied from 8 to 15 leaves year(-1) and nut yield ranged from 3000 to 27,000 nuts ha(-1) year(-1). The genetic coefficients used for calibration and validation were generated from field experiments conducted during 1995-2005. Model efficiency and validation performance were analyzed statistically. Simulated trends in phenological development, total dry mass and its partitioning, and nut yield agreed closely with observed values, although a 15% error was observed in a few cases. Considering that field measurements have an experimental error of 10-15% and wide variation existed within treatments, the model adequately simulated the effects of management practices and agro-climatic conditions over short periods. For a range of agro-climatic zones, simulated potential yields varied from 26 to 30 Mg ha(-1) year(-1) and potential annual dry mass production varied from 52 to 62 Mg ha(-1), depending on environment. We conclude that InfoCrop-coconut can be used to increase the efficiency of agronomic experiments designed to aid coconut crop management.     

Environmental controls on the spatial variability of savanna productivity in the Northern Territory, Australia

Gross Primary Productivity (GPP) is a critical measure of the health and sustainability of natural ecosystems. Understanding the magnitude, spatial patterns and processes of GPP will underpin predictions of the impact of climate change on the carbon cycle. In Australia, savannas account for one third of the terrestrial carbon stores and therefore, estimating the magnitude of savanna GPP and studying the spatial relationship between GPP and environmental determinants at the regional scale is essential in understanding ecosystem responses to increasing atmospheric CO₂ concentrations and climate change. In this study we employed an integrated approach combining in situ measurements, eddy covariance based flux tower data and remote sensing techniques to examine the role of environmental drivers in controlling the spatial variation in GPP of savannas in the Northern Territory (NT), Australia. We used field based light use efficiency (LUE), regional specific meteorology and Moderate Resolution Imaging Spectro-radiometer (MODIS) based fraction of absorbed Photosynthetically Active Radiation (fPAR) data to estimate GPP. The estimated GPP agreed quite well (only a 6% error) with GPP estimated from flux tower at the Howard Springs site. The spatial pattern of GPP along the Northern Australian Tropical Transect (NATT) was calculated and showed a strong gradient in GPP from the coast (12.50°S where rainfall was 1622 mm year⁻¹) to inland (17.73°S where mean rainfall was 643 mm year⁻¹) with a decrease of 77%. A decreasing trend in GPP with rainfall is noticed especially at the dry end of the transect studied. However, in the wet end and middle part of the transect (e.g. dominated by different Eucalyptus species), the response of GPP to changes in rainfall is reduced. This finding suggests that the influence of rainfall on various Eucalyptus species may be dampened by biotic factors. Our results suggest that future changes in precipitation driven by climate change may affect the future distribution and dynamics of GPP in northern Australia.     

Influence of continuous light and fensulfothion treatment on acetylcholinesterase in roots of Pisum sativum

Fensulfothion, O,O-diethyl O-[p-(methylsulfinyl)phenyl] phosphorothioate, an organophosphorus pesticide, inhibits the activity but not the de novo synthesis of acetylcholinesterase in pea (Pisum sativum) roots. The rate of incorporation of labeled amino acids from ¹⁴C-labeled chlorella protein hydrolysate into acetylcholinesterase is affected by the light conditions under which the seedlings are grown. The de novo synthesis of acetylcholinesterase is increased when the seedlings are continuously irradiated with far-red (730 nm) light and is decreased when the plants are grown in total darkness. The pesticide affects acetylcholinesterase synthesis when the seedlings are continuously illuminated with far-red or red (660 nm) light, but has no influence on its synthesis in dark-grown as well as in white (18-hr light and 6-hr dark cycle) light-exposed seedlings. Curiously, far-red irradiation increases the de novo synthesis of acetylcholinesterase when compared to its influence on the total protein synthesis. In the presence of fensulfothion it decreases the synthesis of acetylcholinesterase, but has no significant effect on the total protein synthesis.     

Ammonia toxicity and its effect on the growth of the South African abalone Haliotis midae Linnaeus

The current study investigated acute toxicity to ammonia of the South African abalone, Haliotis midae, from three size classes relevant to mariculture operations, and the chronic impact of sub-lethal ammonia levels on growth of juvenile abalone.Results showed that tolerance to ammonia (at pH 7.8 and T_a = 15 °C) increases with body size (i.e. age) as indicated by 36 h LC₅₀ values: juvenile abalone (1-2.5 cm shell length) had the lowest LC₅₀ of 9.8 μg l^− 1 FAN, whereas LC₅₀ was 12.9 μg l^− 1 FAN in “cocktail”-size abalone (5-8 cm shell length). The highest LC₅₀ of 16.4 μg l^− 1 FAN was observed in “brood stock”-size animals (10-15 cm). When “cocktail”-size abalone were allowed to acclimatize to sub-lethal ammonia levels for 48 h, their ammonia tolerance increased compared with non-acclimatized abalone of the same size: LC₅₀ was 2.0 μg l^− 1 FAN higher at 14.8 μg l^− 1 FAN.Growth of juvenile abalone (1-2.5 cm shell length) during chronic exposure to sub-lethal FAN levels is inhibited: specific growth rate (SGR) is significantly reduced by 58.7% to 0.10 ± 0.03% d^− 1 (weight) compared with 0.24 ± 0.06% d^− 1 of abalone of a control group (no ammonia).The results demonstrate the negative effects of ammonia not only on survival but also on growth of farmed abalone, both impair profitability of the farming operation. The information from the present study will be helpful in determining water quality requirements in South African abalone farms.     

茶叶中农药残留及其通过茶汤进入人体量的估算

茶是世界上最普及的饮料.茶树由于受到大量病虫危害而需要施用许多农药.鉴于公众对食品安全性关注度的日益提高,本文对红茶中7种农药的残留量及其通过泡茶进入茶汤的残留量进行了研究.红茶中的农药残留量为0.18～1.90 mg/kg,其中只有一部分能进入茶汤而被人体摄入.将茶叶冲泡因素考虑在内,通过饮茶进入人体的农药残留量只有...     

Evaluation of Different Conventional Breading Materials on Functional Quality Attributes of Battered and Breaded Fish Cutlets

ABSTRACT

Breading and battering of fish results in a physically superior product with a higher economic value from low-value fish. The present work was undertaken to evaluate three conventional breading materials for fish cutlets. Standard sized fish cutlets were molded with and dipped in a batter mix, followed by breading with bread crumbs (CB), pressed rice (PR), or noodle vermicelli (NS). The products were evaluated for coating parameters such as pickup, adhesion degree, cooking loss, and frying yield. The coating pickup ranged from 10.95% to 36.00%, and a maximum pickup was found with pressed rice (PR). Similarly, the adhesion degree in PR was 26.47%, which was highest among the three. Cooking loss was highest with control (conventional breadcrumb) at 15.92%. After analyzing the frying yield, it was found that PR yielded the maximum at 16.75% and less oil absorption. PR also had significantly (p < .05) higher hue angle value than both the NS and CB. Maximum browning and tough texture was observed in the NS sample. Frying tolerance was better with PR breading, which maintained better color during deep frying operations. This study can help industries to utilze low-cost breading material in preparing enrobed snack products.     

Erythrocyte G protein-coupled receptor signaling in malarial infection

Erythrocytic mechanisms involved in malarial infection are poorly understood. We have found that signaling via the erythrocyte beta2-adrenergic receptor and heterotrimeric guanine nucleotide-binding protein (Galphas) regulated the entry of the human malaria parasite Plasmodium falciparum. Agonists that stimulate cyclic adenosine 3',5'-monophosphate production led to an increase in malarial infection that could be blocked by specific receptor antagonists. Moreover, peptides designed to inhibit Galphas protein function reduced parasitemia in P. falciparum cultures in vitro, and beta-antagonists reduced parasitemia of P. berghei infections in an in vivo mouse model. Thus, signaling via the erythrocyte beta2-adrenergic receptor and Galphas may regulate malarial infection across parasite species.