Arthropod Diversity and Community Structure in Relation to Land Use in the Mekong Delta, Vietnam

Declining biodiversity in agro-ecosystems, caused by intensification of production or expansion of monocultures, is associated with the emergence of agricultural pests. Understanding how land-use and management control crop-associated biodiversity is, therefore, one of the key steps towards the prediction and maintenance of natural pest-control. Here we report on relationships between land-use variables and arthropod community attributes (for example, species diversity, abundance and guild structure) across a diversification gradient in a rice-dominated landscape in the Mekong delta, Vietnam. We show that rice habitats contained the most diverse arthropod communities, compared with other uncultivated and cultivated land-use types. In addition, arthropod species density and Simpson’s diversity in flower, vegetable and fruit habitats was positively related to rice cover in the local landscape. However, across the landscape as a whole, reduction in heterogeneity and the amount of uncultivated cover was associated, generally, with a loss of diversity. Furthermore, arthropod species density in tillering and flowering stages of rice was positively related to crop and vegetation richness, respectively, in the local landscape. Differential effects on feeding guilds were also observed in rice-associated communities with the proportional abundance of predators increasing and the proportional abundance of detritivores decreasing with increased landscape rice cover. Thus, we identify a range of rather complex, sometimes contradictory patterns concerning the impact of rice cover and landscape heterogeneity on arthropod community attributes. Importantly, we conclude that that land-use change associated with expansion of monoculture rice need not automatically impact diversity and functioning of the arthropod community.     

Chloroplast targeting of phytochelatin synthase in Arabidopsis: effects on heavy metal tolerance and accumulation

The enzymatically synthesized thiol peptide phytochelatin (PC) plays a central role in heavy metal tolerance and detoxification in plants. In response to heavy metal exposure, the constitutively expressed phytochelatin synthase enzyme (PCS) is activated leading to synthesis of PCs in the cytosol. Recent attempts to increase plant metal accumulation and tolerance reported that PCS over-expression in transgenic plants paradoxically induced cadmium hypersensitivity. In the present paper, we investigate the possibility of synthesizing PCs in plastids by over-expressing a plastid targeted phytochelatin synthase (PCS). Plastids represent a relatively important cellular volume and offer the advantage of containing glutathione, the precursor of PC synthesis. Using a constitutive CaMV 35S promoter and a RbcS transit peptide, we successfully addressed AtPCS1 to chloroplasts, significant PCS activity being measured in this compartment in two independent transgenic lines. A substantial increase in the PC content and a decrease in the glutathione pool were observed in response to cadmium exposure, when compared to wild-type plants. While over-expressing AtPCS1 in the cytosol importantly decreased cadmium tolerance, both cadmium tolerance and accumulation of plants expressing plastidial AtPCS1 were not significantly affected compared to wild-type. Interestingly, targeting AtPCS1 to chloroplasts induced a marked sensitivity to arsenic while plants over-expressing AtPCS1 in the cytoplasm were more tolerant to this metalloid. These results are discussed in relation to heavy metal trafficking pathways in higher plants and to the interest of using plastid expression of PCS for biotechnological applications.     

Fatal outcome of human influenza A (H5N1) is associated with high viral load and hypercytokinemia

Avian influenza A (H5N1) viruses cause severe disease in humans, but the basis for their virulence remains unclear. In vitro and animal studies indicate that high and disseminated viral replication is important for disease pathogenesis. Laboratory experiments suggest that virus-induced cytokine dysregulation may contribute to disease severity. To assess the relevance of these findings for human disease, we performed virological and immunological studies in 18 individuals with H5N1 and 8 individuals infected with human influenza virus subtypes. Influenza H5N1 infection in humans is characterized by high pharyngeal virus loads and frequent detection of viral RNA in rectum and blood. Viral RNA in blood was present only in fatal H5N1 cases and was associated with higher pharyngeal viral loads. We observed low peripheral blood T-lymphocyte counts and high chemokine and cytokine levels in H5N1-infected individuals, particularly in those who died, and these correlated with pharyngeal viral loads. Genetic characterization of H5N1 viruses revealed mutations in the viral polymerase complex associated with mammalian adaptation and virulence. Our observations indicate that high viral load, and the resulting intense inflammatory responses, are central to influenza H5N1 pathogenesis. The focus of clinical management should be on preventing this intense cytokine response, by early diagnosis and effective antiviral treatment.     

Photodynamic therapy and tumor imaging of hypericin-treated squamous cell carcinoma

Background

The use of cellular and cordless telephones has increased dramatically during the last decade. There is concern of health problems such as malignant diseases due to microwave exposure during the use of these devices. The brain is the main target organ.

Methods

Since the second part of the 1990's we have performed six case-control studies on this topic encompassing use of both cellular and cordless phones as well as other exposures. Three of the studies concerned brain tumours, one salivary gland tumours, one non-Hodgkin lymphoma (NHL) and one testicular cancer. Exposure was assessed by self-administered questionnaires.

Results

Regarding acoustic neuroma analogue cellular phones yielded odds ratio (OR) = 2.9, 95 % confidence interval (CI) = 2.0–4.3, digital cellular phones OR = 1.5, 95 % CI = 1.1–2.1 and cordless phones OR = 1.5, 95 % CI = 1.04–2.0. The corresponding results were for astrocytoma grade III-IV OR = 1.7, 95 % CI = 1.3–2.3; OR = 1.5, 95 % CI = 1.2–1.9 and OR = 1.5, 95 % CI = 1.1–1.9, respectively. The ORs increased with latency period with highest estimates using > 10 years time period from first use of these phone types. Lower ORs were calculated for astrocytoma grade I-II. No association was found with salivary gland tumours, NHL or testicular cancer although an association with NHL of T-cell type could not be ruled out.

Conclusion

We found for all studied phone types an increased risk for brain tumours, mainly acoustic neuroma and malignant brain tumours. OR increased with latency period, especially for astrocytoma grade III-IV. No consistent pattern of an increased risk was found for salivary gland tumours, NHL, or testicular cancer.     

Development of thermostable Candida antarctica lipase B through novel in silico design of disulfide bridge

Lipase B from Candida antarctica (CalB) is a versatile biocatalyst for various bioconversions. In this study, the thermostability of CalB was improved through the introduction of a new disulfide bridge. Analysis of the B‐factors of residue pairs in CalB wild type (CalB‐WT) followed by simple flexibility analysis of residues in CalB‐WT and its designated mutants using FIRST server were newly proposed to enhance the selective power of two computational tools (MODIP and DbD v1.20) to predict the possible disulfide bonds in proteins for the enhancement of thermostability. Five residue pairs (A162‐K308, N169‐F304, Q156_‐L163, S50‐A273, and S239C‐D252C) were chosen and the respective amino acid residues were mutated to cysteine. In the results, CalB A162C‐K308C showed greatly improved thermostability while maintaining its catalytic efficiency compared to that of CalB‐WT. Remarkably, the temperature at which 50% of its activity remained after 60‐min incubation (T) of CalB A162C_K308C was increased by 8.5°C compared to that of CalB‐WT (55 and 46.5°C, respectively). Additionally, the half‐life at 50°C of CalB A162C‐K308C was 4.5‐fold higher than that of CalB‐WT (220 and 49 min, respectively). The improvement of thermostability of CalB A162C‐K308C was elucidated at the molecular level by molecular dynamics (MD) simulation. Biotechnol. Bioeng. 2012; 109:867–876. © 2011 Wiley Periodicals, Inc.     

Abnormal mitochondrial dynamics and synaptic degeneration as early events in Alzheimer's disease: implications to mitochondria-targeted antioxidant therapeutics

Synaptic pathology and mitochondrial oxidative damage are early events in Alzheimer's disease (AD) progression. Loss of synapses and synaptic damage are the best correlates of cognitive deficits found in AD patients. Recent research on amyloid beta (Aβ) and mitochondria in AD revealed that Aβ accumulates in synapses and synaptic mitochondria, leading to abnormal mitochondrial dynamics and synaptic degeneration in AD neurons. Further, recent studies using live-cell imaging and primary neurons from amyloid beta precursor protein (AβPP) transgenic mice revealed reduced mitochondrial mass, defective axonal transport of mitochondria and synaptic degeneration, indicating that Aβ is responsible for mitochondrial and synaptic deficiencies. Tremendous progress has been made in studying antioxidant approaches in mouse models of AD and clinical trials of AD patients. This article highlights the recent developments made in Aβ-induced abnormal mitochondrial dynamics, defective mitochondrial biogenesis, impaired axonal transport and synaptic deficiencies in AD. This article also focuses on mitochondrial approaches in treating AD, and also discusses latest research on mitochondria-targeted antioxidants in AD. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.     

Distribution of polyunsaturated fatty acids in red algae of the genus Gracilaria, a promising source of prostaglandins

The fatty acid (FA) composition and the content of the prostaglandin PGE₂ were determined in the red algae Gracilaria vermiculophylla and G. austramaritima from Peter the Great Bay (Sea of Japan), as well as in G. tenuistupitata, G. ?hangii, and G. bailiniae from lagoons in southern Vietnam (in the South China Sea). Polyunsaturated FA (PUFA) comprised 49?C56% of the total FAs in algae from the Sea of Japan, while in algae from the South China Sea their share was 20% at most. The content of arachidonic acid (20:4n-6) in the total FAs of G. vermiculophylla was as high as 45.4%, while the level of 20:4n-6 in Gracilaria from coastal waters of Vietnam did not exceed 12.5%. G. austramaritima stood out for its high content of eicosapentaenoic acid 20:5n-3 (33.5%). The ratios of 20:4n-6/20:5n-3 in G. vermiculophylla, G. austramaritima, G. tenuistupitata, G. changii, and G. bailiniae were 10.6, 0.3, 3.9, 4.0, and 1.5, respectively. The content of PGE₂ was the highest (286 ??g/g dry weight) in G. vermiculophylla from the Sea of Japan and did not exceed 20 ??g/g dry weights in other Gracilaria species. This study showed that it is possible to introduce G. vermiculophylla from the Sea of Japan into the mariculture of northern Vietnam. In the experiment, during 3 weeks of cultivation, the biomass of introduced Gracilaria increased 1.2?C1.3 times in a sea lagoon in Vietnam and 1.5?C2 times in an aquarium; the algal growth rates were 1.57 ± 0.21% per day. In cultivated Gracilaria, the level of 20:4n-6 decreased to 5.9% (20:4n-6/20:5n-3 = 2.3) and the level of PGE₂ decreased to 12 ??g/g in dry weight. The PUFA compositions of G. vermiculophylla from various natural populations differed insignificantly; however, the stress caused by introduction led to a sharp reduction in the content of 20:4n-6, which was probably connected with a decreased biosynthesis rate of PUFAs of the n-6 series. At the same time, approximately equal amounts of PGE₂ methyl ester were extracted from natural and cultivated G. vermiculophylla after treatment by a method proposed for obtaining prostaglandins. Thus, the cultivation conditions evidently did not influence the prostaglandin biosynthesis enzyme complex in G. vermiculophylla; this species, when grown in mariculture, can be used as a source of prostaglandins.     

The co-selection of fluoroquinolone resistance genes in the gut flora of vietnamese children

Antimicrobial consumption is one of the major contributing factors facilitating the development and maintenance of bacteria exhibiting antimicrobial resistance. Plasmid-mediated quinolone resistance (PMQR) genes, such as the qnr family, can be horizontally transferred and contribute to reduced susceptibility to fluoroquinolones. We performed an observational study, investigating the copy number of PMQR after antimicrobial therapy. We enrolled 300 children resident in Ho Chi Minh City receiving antimicrobial therapy for acute respiratory tract infections (ARIs). Rectal swabs were taken on enrollment and seven days subsequently, counts for Enterobacteriaceae were performed and qnrA, qnrB and qnrS were quantified by using real-time PCR on metagenomic stool DNA. On enrollment, we found no association between age, gender or location of the participants and the prevalence of qnrA, qnrB or qnrS. Yet, all three loci demonstrated a proportional increase in the number of samples testing positive between day 0 and day 7. Furthermore, qnrB demonstrated a significant increase in copy number between paired samples (p<0.001; Wilcoxon rank-sum), associated with non-fluoroquinolone combination antimicrobial therapy. To our knowledge, this is the first study describing an association between the use of non-fluoroquinolone antimicrobials and the increasing relative prevalence and quantity of qnr genes. Our work outlines a potential mechanism for the selection and maintenance of PMQR genes and predicts a strong effect of co-selection of these resistance determinants through the use of unrelated and potentially unnecessary antimicrobial regimes.