Pteropus lylei primarily forages in residential areas in Kandal,Cambodia

相似文献   

In Vitro and In Vivo Antitumor Activity of a Novel Semisynthetic Derivative of Cucurbitacin B

Lung cancer is the most deadly type of cancer in humans, with non-small-cell lung cancer (NSCLC) being the most frequent and aggressive type of lung cancer showing high resistance to radiation and chemotherapy. Despite the outstanding progress made in anti-tumor therapy, discovering effective anti-tumor drugs is still a challenging task. Here we describe a new semisynthetic derivative of cucurbitacin B (DACE) as a potent inhibitor of NSCLC cell proliferation. DACE arrested the cell cycle of lung epithelial cells at the G2/M phase and induced cell apoptosis by interfering with EGFR activation and its downstream signaling, including AKT, ERK, and STAT3. Consistent with our in vitro studies, intraperitoneal application of DACE significantly suppressed the growth of mouse NSCLC that arises from type II alveolar pneumocytes due to constitutive expression of a human oncogenic c-RAF kinase (c-RAF-1-BxB) transgene in these cells. Taken together, these findings suggest that DACE is a promising lead compound for the development of an anti-lung-cancer drug.     

Use of a genetically engineered protein for the design of a multivalent MRI contrast agent

The majority of clinically used contrast agents (CAs) for magnetic resonance imaging have low relaxivities and thus require high concentrations for signal enhancement. Research has turned to multivalent, macromolecular CAs to increase CA efficiency. However, previously developed macromolecular CAs do not provide high relaxivities, have limited biocompatibility, and/or do not have a structure that is readily modifiable to tailor to particular applications. We report a new family of multivalent, biomacromolecular, genetically engineered protein polymer-based CAs; the protein backbone contains evenly spaced lysines that are derivatized with gadolinium (Gd(III)) chelators. The protein's length and repeating amino acid sequence are genetically specified. We reproducibly obtained conjugates with an average of 8-9 Gd(III) chelators per protein. These multivalent CAs reproducibly provide a high relaxivity of 7.3 mM (-1) s (-1) per Gd(III) and 62.6 mM (-1) s (-1) per molecule. Furthermore, they can be incorporated into biomaterial hydrogels via chemical cross-linking of the remaining free lysines, and provide a dramatic contrast enhancement. Thus, these protein polymer CAs could be a useful tool for following the evolution of tissue engineering scaffolds.     

Comblike, monodisperse polypeptoid drag-tags for DNA separations by end-labeled free-solution electrophoresis (ELFSE)

The development of innovative technologies designed to reduce the cost and increase the throughput of DNA separations continues to be important for large-scale sequencing and genotyping efforts. We report research aimed at the further development of a free-solution bioconjugate method of DNA size separation by capillary electrophoresis (CE), in particular, the determination of an optimal molecular architecture for polyamide-based "drag-tags". We synthesized several branched poly(N-methoxyethyl glycine)s (poly(NMEG)s, a class of polypeptoids) as novel friction-generating entities for end-on attachment to DNA molecules. A 30-mer poly(NMEG) "backbone," comprising five evenly spaced reactive epsilon-amino groups, was synthesized on solid phase, cleaved, and purified to monodispersity by RP-HPLC. Three different comblike derivatives of this backbone molecule were created by (1) acetylating the epsilon-amino groups or (2) appending small, monodisperse NMEG oligomers (a tetramer and an octamer). Grafting of the oligo(NMEG)s was done using solution-phase amide bond formation chemistry. Once purified to total monodispersity, the three different drag-tags were studied by free-solution electrophoresis to observe the effect of branching on their hydrodynamic drag or "alpha" and hence their ability to separate DNA. Drag was found to scale linearly with total molecular weight, regardless of branch length. The octamer-branched drag-tag-DNA conjugate was used to separate ssDNA products of 50, 75, 100, and 150 bases in length by free-solution CE in less than 10 min. Hence, the use of branched or comblike drag-tags is both a feasible and an effective way to achieve high frictional drag, allowing the high-resolution separation of relatively large DNA molecules by free-solution CE without the need to synthesize very long polymers.     

Trypanosomatid flagellum biogenesis: ARL-3A is involved in several species

Overexpression in Leishmania amazonensis promastigotes of the GTPase-deficient small G protein LdARL-3A-Q70L specifically provokes the loss of the flagella without affecting cell viability and body size. However, motility is lost and, remarkably, cells do not survive in the insect vector Lutzomyia longipalpis gut, leading to interruption of parasite transmission. We report here that overexpression of the same protein in Leishmania major, Leishmania donovani, and Crithidia fasciculata also led to significant alterations of the flagella. Surprisingly, ablation of TbARL-3A expression by RNAi in Trypanosoma brucei brucei also provoked flagella shortening, revealing that overexpression of the GTPase-deficient protein seems functionally equivalent to a drastic reduction in its native counterpart abundance. This renders possible complementary studies of an essential pathway in related organisms. Potential significance for the protein function is discussed as well as future strategies for stopping the transmission of several neglected parasitic diseases.     

LdARL-1 His-tagged recombinant protein: purification by immobilized metal affinity expanded bed adsorption

Previously we have cloned three ADP-ribosylation factor-like (ARL) genes from the parasitic protozoan Leishmania donovani: LdARL-3A and 3B, LdARL-1. LdARL-3A was previously purified as an active native form, which was able to bind GTP in vitro. In this paper, we have performed the production and the purification of Histidine-tagged (His-tagged) LdARL-1 recombinant protein by immobilized metal affinity chromatography (IMAC) using expanded bed adsorption (EBA) technology. This protein was purified with more than 95% purity and could be successfully used for GTP-binding assay.     

Integrated Analysis of Environment,Cattle and Human Serological Data: Risks and Mechanisms of Transmission of Rift Valley Fever in Madagascar

BackgroundRift Valley fever (RVF) is a vector-borne disease affecting ruminants and humans. Madagascar was heavily affected by RVF in 2008–2009, with evidence of a large and heterogeneous spread of the disease. The identification of at-risk environments is essential to optimize the available resources by targeting RVF surveillance in Madagascar. Herein, the objectives of our study were: (i) to identify the environmental factors and areas favorable to RVF transmission to both cattle and human and (ii) to identify human behaviors favoring human infections in Malagasy contexts.Conclusions/SignificanceOur integrated approach analyzing environmental, cattle and human datasets allow us to bring new insight on RVF transmission patterns in Madagascar. The association between cattle seroprevalence, humid environments and high cattle density suggests that concomitant vectorial and direct transmissions are critical to maintain RVF enzootic transmission. Additionally, in the at-risk humid environment of the western, north-western and the eastern-coast areas, suitable to Culex and Anopheles mosquitoes, vectorial transmission probably occurs in both cattle and human. The relative contribution of vectorial or direct transmissions could be further assessed by mathematic modelling.     

Interactions of the monomeric and dimeric flavones apigenin and amentoflavone with the plasma membrane of L929 cells; a fluorescence study.

Flavonoids are ubiquitous polyphenolic compounds, found in vascular plants, which are endowed with a large variety of biological effects. Some of these effects have been assumed to result from interactions with the cell plasma membrane. In order to investigate the nature of these interactions a fluorescence study was performed with two flavonoids, currently used in one of the laboratories: apigenin and its homologous dimer amentoflavone. After preliminary assays with DPH in several types of phospholipid liposomes, the effects of these flavonoids on the membrane of mouse L929 fibroblasts were compared, using the non-permeant probe TMA-DPH. Amentoflavone, unlike apigenin, induced a static quenching effect, which denoted an important, but reversible, association of the molecule with the plasma membrane. In addition, amentoflavone treatment induced a dose-dependent increase in TMA-DPH fluorescence anisotropy, which could be interpreted as an increase in membrane lipidic order. For apigenin, the effect was much less important. Moreover, exploiting the capacity of TMA-DPH to label endocytic compartments, it was shown that, after association with the membrane, amentoflavone is not internalized into the cell. Possible correlations of these membrane effects with other biological properties are discussed.     

农田和森林土壤中氧化亚氮的产生与还原

采用土壤淤浆方法对丹麦农田和山毛榉森林土壤反硝化过程中Ｎ２Ｏ的产生与还原进行了研究。同时考察了硝酸根和铵离子对反硝化作用的影响。结果表明,森林土壤反硝化活性大于农田土壤,但农田土壤中Ｎ２Ｏ还原活性大于森林土壤,表现在农田和森林土壤中Ｎ２Ｏ／Ｎ２的产生比率分别为０．１１和３．６５。硝酸根和铵离子能促进两种土壤中的Ｎ２Ｏ产生,但可降低农田土壤中的Ｎ２Ｏ还原速率,与农田土壤相比,硝酸根可降低森林土壤Ｎ２     

High Prevalence of Anemia in Children and Adult Women in an Urban Population in Southern Brazil

This population-based study was designed to detect the prevalence of anemia in a healthy population of children (18 months to 7 years) and women (14 to 30 years) tested in 2006–2007 in the state of Rio Grande do Sul, Brazil as part of an effort to tackle this massive problem that still affects so many people in the XXI century. Anemia was defined according to the WHO. Capillary blood was measured and socioeconomic status was determined according to the Brazilian Association of Market Research Agencies. The median prevalence of anemia in 2198 children was 45.4% and in 1999 women 36.4%. Anemia decreased with age during childhood; although significantly more prevalent in lower classes individuals, it was also high in the upper classes. There are indirect evidences that the lack of iron supplementation and/or iron fortified food may play a role in it. Professionals and society wise measures of education have to be implemented in order to address possible biologic factors involved in childhood psychosocial development in southern Brazil.