Malate metabolism in Hoya carnosa mitochondria and its role in photosynthesis during CAM phase III

This study investigated the respiratory properties and the role of the mitochondria isolated from one phosphoenolpyruvate carboxykinase (PCK)-CAM plant, Hoya carnosa, in malate metabolism during CAM phase III. The mitochondria showed high malate dehydrogenase (mMDH) and aspartate amino transferase (mAST), and a significant amount of malic enzyme (mME) activities. H. carnosa readily oxidized malate via mME and mMDH in the presence of some cofactors such as thiamine pyrophosphate (TPP), coenzyme A (CoA) or NAD(+). A high respiration rate of malate oxidation was observed at pH 7.2 with NAD(+) and glutamate (Glu). Providing AST and Glu simultaneously into the respiratory medium strongly increased the rates of malate oxidation, and this oxidation was gradually inhibited by an inhibitor of alpha-ketoglutarate (alpha-KG) carrier, pyridoxal-5'-phosphate (PLP). The mitochondria readily oxidized aspartate (Asp) or alpha-KG individually with low rates, while they oxidized Asp and alpha-KG simultaneously with high rates, and this simultaneous oxidation was also inhibited by PLP. By measuring the capacity of the mitochondrial shuttle, it was found that the OAA produced via mMDH seemed not to be transported outside the mitochondria, but mAST interconverted OAA and Glu to Asp and alpha-KG, respectively, and exported them out via a malate-aspartate (malate-Asp) shuttle. The data in this research suggest that during phase III of PCK-CAM, H. carnosa mitochondria oxidized malate via both mME and the mMDH systems depending on metabolic requirements. However, malate metabolism by the mMDH system did not operate via a malate-OAA shuttle similarly to Ananas comosus mitochondria, but it operated via a malate-Asp shuttle similarly to Kalancho? daigremontiana mitochondria.     

MicroRNAs can regulate human APP levels

A number of studies have shown that increased APP levels, resulting from either a genomic locus duplication or alteration in APP regulatory sequences, can lead to development of early-onset dementias, including Alzheimer's disease (AD). Therefore, understanding how APP levels are regulated could provide valuable insight into the genetic basis of AD and illuminate novel therapeutic avenues for AD. Here we test the hypothesis that APP protein levels can be regulated by miRNAs, evolutionarily conserved small noncoding RNA molecules that play an important role in regulating gene expression. Utilizing human cell lines, we demonstrate that miRNAs hsa-mir-106a and hsa-mir-520c bind to their predicted target sequences in the APP 3'UTR and negatively regulate reporter gene expression. Over-expression of these miRNAs, but not control miRNAs, results in translational repression of APP mRNA and significantly reduces APP protein levels. These results are the first to demonstrate that levels of human APP can be regulated by miRNAs.     

Influenza A H5N1 clade 2.3.4 virus with a different antiviral susceptibility profile replaced clade 1 virus in humans in northern Vietnam

Background

Prior to 2007, highly pathogenic avian influenza (HPAI) H5N1 viruses isolated from poultry and humans in Vietnam were consistently reported to be clade 1 viruses, susceptible to oseltamivir but resistant to amantadine. Here we describe the re-emergence of human HPAI H5N1 virus infections in Vietnam in 2007 and the characteristics of the isolated viruses.

Methods and Findings

Respiratory specimens from patients suspected to be infected with avian influenza in 2007 were screened by influenza and H5 subtype specific polymerase chain reaction. Isolated H5N1 strains were further characterized by genome sequencing and drug susceptibility testing. Eleven poultry outbreak isolates from 2007 were included in the sequence analysis. Eight patients, all of them from northern Vietnam, were diagnosed with H5N1 in 2007 and five of them died. Phylogenetic analysis of H5N1 viruses isolated from humans and poultry in 2007 showed that clade 2.3.4 H5N1 viruses replaced clade 1 viruses in northern Vietnam. Four human H5N1 strains had eight-fold reduced in-vitro susceptibility to oseltamivir as compared to clade 1 viruses. In two poultry isolates the I117V mutation was found in the neuraminidase gene, which is associated with reduced susceptibility to oseltamivir. No mutations in the M2 gene conferring amantadine resistance were found.

Conclusion

In 2007, H5N1 clade 2.3.4 viruses replaced clade 1 viruses in northern Vietnam and were susceptible to amantadine but showed reduced susceptibility to oseltamivir. Combination antiviral therapy with oseltamivir and amantadine for human cases in Vietnam is recommended.     

Engineering of FRT-lacZ fusion constructs: induction of the Pseudomonas aeruginosa fadAB1 operon by medium and long chain-length fatty acids

Without prior knowledge of the promoters of various genes in bacteria, it can be difficult to study gene regulation using reporter-gene fusions. Regulation studies of promoters are ideal at their native locus, which do not require prior knowledge of promoter regions. Based on a previous study with FRT-lacZ-KmR constructs, we constructed two novel FRT-lacZ-GmR plasmids. This allows easy engineering of Pseudomonas aeruginosa reporter-gene fusions, post-mutant construction, with the Flp-FRT system. We demonstrate the usefulness of one of these FRT-lacZ-GmR plasmids to study the regulation of the fadAB1 operon in P. aeruginosa at its native locus. The fadAB1 operon, involved in fatty acid (FA) degradation, was significantly induced in the presence of several medium chain-length fatty acids (MCFA) and, to a lesser degree, long chain-length fatty acids (LCFA). In addition to the previous work on the FRT-lacZ-KmR tools, these new constructs increase the repertoire of tools that can be applied to P. aeruginosa or other species and strains of bacteria where kanamycin resistance may not be appropriate.     

Uses and Conservation of Plant Species in a National Park—A Case Study of Ben En, Vietnam

Uses and Conservation of Plant Species in a National Park—A Case Study of Ben En, Vietnam. This paper surveys the use of wild and cultivated plants by local people in Ben En National Park, Vietnam, and analyzes its impact on the conservation status of some of the utilized species. A total of 208 species used for a range of nonmedicinal purposes are listed. See Hoang et al. (2008a) for 230 medicinal plants used in the park. Most species are used for food. The use of plants contributes very significantly to the livelihood of local people in the park, but the current use patterns are not sustainable and would lead to local extinction of rare and endangered species if no additional conservation measures are introduced. Men collect nonmedicinal plants more often than women. A total of 38 useful plant species are commercialized, and contribute 12% of the average income of individual households. Bamboo shoots of Schizostachyum funghomii (Poaceae) are the most important for income generation. The monetary equivalent of noncommercialized useful plants probably far exceeds the value of the traded plant products. Plant use is independent of the ethnicity of the different populations living in the park. Larger households make use of a greater variety of useful plant species than small families. Abundant species in the forest have a higher use index (UI) than less common species. Out of the 208 useful species, as many as 27 were found to be endangered locally, many more than the 11 or 8 endangered species included in national or global red lists. Currently, useful plants, especially important timber trees, are more abundant in the less disturbed parts of the park, far away from the villages, indicating the pressures of illegal logging and harvesting near villages on the ecosystems.     

Food, feed or medicine: The multiple functions of edible wild plants in Vietnam

Many of the edible wild plants that are included in local food baskets have both therapeutic and dietary functions. Such medicinal foods have been part of Eastern medicinal theories since ancient times and have recently received attention in the USA and Europe within the fields of functional foods, neutraceuticals and phyto-nutrients. This paper provides an example from Vietnam of the continued use of a multitude of edible wild vegetables. Vietnamese traditional medicine also holds an important position within the health care system and many of the plants that are used have both dietary and medicinal functions. Using a combination of qualitative and quantitative techniques (Rapid Rural Appraisal and Food Frequency Questionnaires), information on over 90 species of edible wild plants was obtained from 4 villages in the Mekong Delta and the Central Highlands. About a third of the plants also had therapeutic roles, forty percent were used also as livestock feeds and one fifth were used as food/livestock feed/ medicine. From a nutrition viewpoint it is important to pay attention to this group of traditional foods for several reasons. Their direct nutritional contribution is often significant but neglected. Very little is known about the health benefits of regular consumption of small quantities of medicinal foods and an important “medicinal role” of traditional plant medicines may be the contribution of small quantities of trace minerals and vitamins. The parallel functions as livestock feeds make animal products more accessible to poor households and help improve the quality of their diets.     

Cell source,differentiation, functional stimulation,and potential application of human thermogenic adipocytes in vitro

Recent investigations have showed that the functional thermogenic adipocytes are present in both infants and adult humans. Accumulating evidence suggests that the coexistence of classical and inducible brown (brite) adipocytes in humans at adulthood and these adipocytes function to generate heat from energy resulting in reducing body fat and improving glucose metabolism. Human thermogenic adipocytes can be differentiated in vitro from stem cells, cell lines, or adipose stromal vascular fraction. Pre-activated human brite adipocytes in vitro can maintain their thermogenic function in normal or obese immunodeficient mice; therefore, they improve glucose homeostasis and reduce fat mass in obese animals. These key findings have opened a new door to use in vitro thermogenic adipocytes as a cell therapy to prevent obesity and related disorders. Thus, this paper intends to highlight our knowledge in aspects of in vitro human brite/brown adipocytes for the further studies.     

Single-molecule sorting reveals how ubiquitylation affects substrate recognition and activities of FBH1 helicase

DNA repair helicases function in the cell to separate DNA duplexes or remodel nucleoprotein complexes. These functions are influenced by sensing and signaling; the cellular pool of a DNA helicase may contain subpopulations of enzymes carrying different post-translational modifications and performing distinct biochemical functions. Here, we report a novel experimental strategy, single-molecule sorting, which overcomes difficulties associated with comprehensive analysis of heterologously modified pool of proteins. This methodology was applied to visualize human DNA helicase F-box–containing DNA helicase (FBH1) acting on the DNA structures resembling a stalled or collapsed replication fork and its interactions with RAD51 nucleoprotein filament. Individual helicase molecules isolated from human cells with their native post-translational modifications were analyzed using total internal reflection fluorescence microscopy. Separation of the activity trajectories originated from ubiquitylated and non-ubiquitylated FBH1 molecules revealed that ubiquitylation affects FBH1 interaction with the RAD51 nucleoprotein filament, but not its translocase and helicase activities.