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Chromera velia is a recently discovered, photosynthetic, marine alveolate closely related to apicomplexan parasites, and more distantly to perkinsids and dinoflagellates. To date, there are no published studies on the sterols of C. velia. Because apicomplexans and perkinsids are not known to synthesize sterols de novo, but rather obtain them from their host organisms, our objective was to examine the composition of the sterols of C. velia to assess whether or not there is any commonality with dinoflagellates as the closest taxonomic group capable of synthesizing sterols de novo. Furthermore, knowledge of the sterols of C. velia may provide insight into the sterol biosynthetic capabilities of apicomplexans prior to loss of sterol biosynthesis. We have found that C. velia possesses two primary sterols, 24-ethylcholesta-5,22E-dien-3β-ol, and 24-ethylcholest-5-en-3β-ol, not common to dinoflagellates, but rather commonly found in other classes of algae and plants. In addition, we have identified computationally three genes, SMT1 (sterol-24C-methyltransferase), FDFT1 (farnesyl diphosphate farnesyl transferase, squalene synthase), and IDI1 (isopentenyl diphosphate Δ-isomerase), predicted to be involved in sterol biosynthesis by their similarity to analogous genes in other sterol-producing eukaryotes, including a number of algae.  相似文献   
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Neutrophils expel extracellular traps (NETs) to entrap and exterminate the invaded micro-organisms. Acute/chronic inflammatory disorders are often observed with aberrantly enhanced NETs formation and high nitric oxide (NO) availability. Recent study from this laboratory demonstrated release of NETs from human neutrophils following treatment with SNP or SNAP. This study is an extension of our previous finding to explore the extracellular bacterial killing, source of DNA in the expelled NETs, their ability to induce proinflammatory cytokines release from platelets/THP-1 cells, and assessment of NO-mediated free radical formation by using a consistent NO donor, DETA-NONOate. NO-mediated NETs exhibited extracellular bacterial killing as determined by colony forming units. NO-mediated NETs formation was due to the activation of NADPH oxidase and myeloperoxidase. NO- or PMA-mediated NETs were positive for both nuclear and mitochondrial DNA as well as proteolytic enzymes. Incubation of NETs with human platelets enhanced the release of IL-1β and IL-8, while with THP-1 cells, release of IL-1β, IL-8, and TNFα was observed. This study demonstrates that NO by augmenting enzymatic free radical generation release NETs to promote extracellular bacterial killing. These NETs were made up of mitochondrial and nuclear DNA and potentiated release of proinflammatory cytokines.  相似文献   
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Inteins and other self-catalytic enzymes, such as glycosylasparaginases and hedgehog precursors, initiate autocleavage by converting a peptide bond to a (thio)ester bond when Ser, Thr, or Cys undergoes an N-[S/O] acyl migration assisted by residues within the precursor. Previous studies have shown that a His at position 10 in intein Block B is essential for this initial acyl migration and N-terminal splice junction cleavage. This His is present in all inteins identified to date except the Thermococcus kodakaraensis Tko CDC21-1 intein orthologs and the inactive Arthrobacter species FB24 Arth_1007 intein. This study demonstrates that the Tko CDC21-1 intein is fully active and has replaced the lost catalytic function normally provided by the Block B His using a compensatory mechanism involving a conserved ortholog-specific basic residue (Lys(58)) present outside the standard intein conserved motifs. We propose that Lys(58) catalyzes the initial N-S acyl migration by stabilizing the thiazolidine-tetrahedral intermediate, allowing it to be resolved by water-mediated hydrolysis rather than by protonating the leaving group as His is theorized to do in many other inteins. Autoprocessing enzymes may have more flexibility in evolving catalytic variations because high reaction rates are not required when performing single-turnover reactions on "substrates" that are covalently attached to the enzyme. Consequently, inteins have more flexibility to sample catalytic mechanisms, providing insight into various strategies that enzymes use to accomplish catalysis.  相似文献   
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To evaluate genetic homogeneity of 1-year-old guava (Psidium guajava L.) plants developed from in vitro somatic embryogenesis, DNA from leaf tissues of seven randomly selected plants along with the mother plant, was isolated and subjected to molecular analysis. A total of six Simple Sequence Repeat (SSR) primer pairs, producing reproducible and clear bands ranging from 100 to 300?bp in size, resulted in amplification of single band (allele), corresponding homozygous individuals. Moreover, of 10 different inter-simple sequence repeat (ISSR) primers screened, six produced resolvable, reproducible and scorable bands. All these ISSRs produced a total of 25 bands, ranging between 300 and 1,200?bp length, and the number of scorable bands, for each primer varied from three to six with an average of 4.1 bands per primer. The amplification products were monomorphic across all the micropropagated plants produced by all SSR and ISSR primers applied. The monomorphic banding pattern in micropropagated plants and the mother plant confirms the genetic homogeneity of the in vitro raised plants and demonstrates the reliability of our in vitro propagation system for guava.  相似文献   
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Dengue fever is the most important arboviral disease in the tropical and sub-tropical countries of the world. Delhi, the metropolitan capital state of India, has reported many dengue outbreaks, with the last outbreak occurring in 2013. We have recently reported predominance of dengue virus serotype 2 during 2011–2014 in Delhi. In the present study, we report molecular characterization and evolutionary analysis of dengue serotype 2 viruses which were detected in 2011–2014 in Delhi. Envelope genes of 42 DENV-2 strains were sequenced in the study. All DENV-2 strains grouped within the Cosmopolitan genotype and further clustered into three lineages; Lineage I, II and III. Lineage III replaced lineage I during dengue fever outbreak of 2013. Further, a novel mutation Thr404Ile was detected in the stem region of the envelope protein of a single DENV-2 strain in 2014. Nucleotide substitution rate and time to the most recent common ancestor were determined by molecular clock analysis using Bayesian methods. A change in effective population size of Indian DENV-2 viruses was investigated through Bayesian skyline plot. The study will be a vital road map for investigation of epidemiology and evolutionary pattern of dengue viruses in India.  相似文献   
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