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481.
A study was carried out to determine the presence of paralytic shellfish poisoning (PSP) toxin-producing dinoflagellates in the coastal waters of Peninsula Malaysia. This followed first ever occurrences of PSP in the Straits of Malacca and the northeast coast of the peninsula. The toxic tropical dinoflagellate Pyrodinium bahamense var. compressum was never encountered in any of the plankton samples. On the other hand, five species of Alexandrium were found. They were Alexandrium affine, Alexandrium leei, Alexandrium minutum, Alexandrium tamarense and Alexandrium tamiyavanichii. Not all species were present at all sites. A. tamiyavanichii was present only in the central to southern parts of the Straits of Malacca. A. tamarense was found in the northern part of the straits, while A. minutum was only found in samples from the northeast coast of the peninsula. A. leei and A. affine were found in both the north and south of the straits. Cultured isolates of A. minutum and A. tamiyavanichii were proven toxic by the receptor binding assay for PSP toxins but A. tamarense clones were not toxic. Mean toxin content for the A. tamiyavanichii and A. minutum clones were 26 and 15 fmol per cell STX equivalent, respectively. This study has provided evidence on the presence of PSP toxin-producing Alexandrium species in Malaysian waters which suggests that PSP could increase in importance in the future. 相似文献
482.
Tom Swinfield Sabine Both Terhi Riutta Boris Bongalov Dafydd Elias Noreen Majalap‐Lee Nicholas Ostle Martin Svtek Jakub Kvasnica David Milodowski Tommaso Jucker Robert M. Ewers Yi Zhang David Johnson Yit Arn Teh David F. R. P. Burslem Yadvinder Malhi David Coomes 《Global Change Biology》2020,26(2):989-1002
Logging, pervasive across the lowland tropics, affects millions of hectares of forest, yet its influence on nutrient cycling remains poorly understood. One hypothesis is that logging influences phosphorus (P) cycling, because this scarce nutrient is removed in extracted timber and eroded soil, leading to shifts in ecosystem functioning and community composition. However, testing this is challenging because P varies within landscapes as a function of geology, topography and climate. Superimposed upon these trends are compositional changes in logged forests, with species with more acquisitive traits, characterized by higher foliar P concentrations, more dominant. It is difficult to resolve these patterns using traditional field approaches alone. Here, we use airborne light detection and ranging‐guided hyperspectral imagery to map foliar nutrient (i.e. P, nitrogen [N]) concentrations, calibrated using field measured traits, over 400 km2 of northeastern Borneo, including a landscape‐level disturbance gradient spanning old‐growth to repeatedly logged forests. The maps reveal that canopy foliar P and N concentrations decrease with elevation. These relationships were not identified using traditional field measurements of leaf and soil nutrients. After controlling for topography, canopy foliar nutrient concentrations were lower in logged forest than in old‐growth areas, reflecting decreased nutrient availability. However, foliar nutrient concentrations and specific leaf area were greatest in relatively short patches in logged areas, reflecting a shift in composition to pioneer species with acquisitive traits. N:P ratio increased in logged forest, suggesting reduced soil P availability through disturbance. Through the first landscape scale assessment of how functional leaf traits change in response to logging, we find that differences from old‐growth forest become more pronounced as logged forests increase in stature over time, suggesting exacerbated phosphorus limitation as forests recover. 相似文献
483.
Wendy Chui Phing Lau Mohd Y. Rafii Mohd Razi Ismail Adam Puteh 《Critical reviews in biotechnology》2016,36(1):87-98
The eating and cooking qualities of rice are heavily emphasized in breeding programs because they determine market values and they are the appealing attributes sought by consumers. Conventional breeding has developed traditional varieties with improved eating and cooking qualities. Recently, intensive genetic studies have pinpointed the genes that control eating and cooking quality traits. Advances in genetic studies have developed molecular techniques, thereby allowing marker-assisted breeding (MAB) for improved eating and cooking qualities in rice. MAB has gained the attention of rice breeders for the advantages it can offer that conventional breeding cannot. There have been successful cases of using MAB to improve the eating and cooking qualities in rice over the years. Nevertheless, MAB should be applied cautiously given the intensive effort needed for genotyping. Perspectives from conventional breeding to marker-assisted breeding will be discussed in this review for the advancement of the eating and cooking qualities of fragrance, amylose content (AC), gel consistency (GC) and gelatinization temperature (GT) in rice. These four parameters are associated with eating and cooking qualities in rice. The genetic basis of these four parameters is also included in this review. MAB is another approach to rice variety improvement and development in addition to being an alternative to genetic engineering. The MAB approach shortens the varietal development time, and is therefore able to deliver improved rice varieties to farmers within a shorter period of time. 相似文献
484.
Aniyizhai Annamalai Noreen Singh Stephanie S. O’Malley 《The Yale journal of biology and medicine》2015,88(3):271-277
Smoking rates in people with serious mental illness (SMI) are disproportionately high compared to the general population. It is a leading contributor to the early mortality in this population. Smoking cessation rates are low in this group, though patients are motivated to quit. Unfortunately, health care providers do not always prioritize smoking cessation for this population. This review provides an overview of prevalence rates, biological effects that maintain smoking, and evidence-based treatments for smoking cessation in SMI. In addition, objective and qualitative data from a chart review of 78 patients with SMI prescribed smoking cessation treatment at one community mental health center are described. Of these, 30 (38.5 percent) were found to either quit (16/78) or reduce (14/78) smoking. Varenicline appeared to be particularly effective. Review of the literature and results of this study suggest that smoking cessation pharmacotherapies are effective for SMI patients and should be offered to those who smoke. 相似文献
485.
The structure and composition of a biological membrane can severely influence the activity of membrane-embedded proteins. Here, we show that the E. coli aquaglyceroporin GlpF has only little activity in lipid bilayers formed from native E. coli lipids. Thus, at first glance, GlpF appears to not be optimized for its natural membrane environment. In fact, we found that GlpF activity was severely affected by negatively charged lipids regardless of the exact chemical nature of the lipid headgroup, whereas GlpF was not sensitive to changes in the lateral membrane pressure. These observations illustrate a potential mechanism by which the activity of an α-helical membrane protein is modulated by the negative charge density around the protein. 相似文献
486.
Peptide binding specificity of the chaperone calreticulin 总被引:1,自引:0,他引:1
Sandhu N Duus K Jørgensen CS Hansen PR Bruun SW Pedersen LØ Højrup P Houen G 《Biochimica et biophysica acta》2007,1774(6):701-713
Calreticulin is a molecular chaperone with specificity for polypeptides and N-linked monoglucosylated glycans. In order to determine the specificity of polypeptide binding, the interaction of calreticulin with polypeptides was investigated using synthetic peptides of different length and composition. A large set of available synthetic peptides (n=127) was tested for binding to calreticulin and the results analysed by multivariate data analysis. The parameter that correlated best with binding was hydrophobicity while beta-turn potential disfavoured binding. Only hydrophobic peptides longer than 5 amino acids showed binding and a clear correlation with hydrophobicity was demonstrated for oligomers of different hydrophobic amino acids. Insertion of hydrophilic amino acids in a hydrophobic sequence diminished or abolished binding. In conclusion our results show that calreticulin has a peptide-binding specificity for hydrophobic sequences and delineate the fine specificity of calreticulin for hydrophobic amino acid residues. 相似文献
487.
Hirst M Delaney A Rogers SA Schnerch A Persaud DR O'Connor MD Zeng T Moksa M Fichter K Mah D Go A Morin RD Baross A Zhao Y Khattra J Prabhu AL Pandoh P McDonald H Asano J Dhalla N Ma K Lee S Ally A Chahal N Menzies S Siddiqui A Holt R Jones S Gerhard DS Thomson JA Eaves CJ Marra MA 《Genome biology》2007,8(6):R113-12
488.
Sellan Giacomo Thompson Jill Majalap Noreen Brearley Francis Q. 《Plant and Soil》2019,441(1-2):173-190
Plant and Soil - To investigate how different tree species affect the composition of SOM and its mineralization in boreal forest ecosystems. We used pyrolysis GC–MS for molecular-level... 相似文献
489.
RNA binding proteins (RBP) play essential roles in the highly conserved and coordinated process of ribosome biogenesis. Our laboratory has previously characterized two essential and abundant RBPs, P34 and P37, in Trypanosoma brucei which are required for several critical steps in ribosome biogenesis. The genes for these proteins have only been identified in kinetoplastid organisms but not in the host genome. We have identified a homolog of the TbP34 and TbP37 in a T. cruzi strain (termed TcP37/NRBD). Although the N-terminal APK-rich domain and RNA recognition motifs are conserved, the C-terminal region which contains putative nuclear and nucleolar localization signals in TbP34 and TbP37 is almost entirely missing from TcP37/NRBD. We have shown that TcP37/NRBD is expressed in T. cruzi epimastigotes at the level of mature mRNA and protein. Despite the loss of the C-terminal domain, TcP37/NRBD is present in the nucleus, including the nucleolus, and the cytoplasm. TcP37/NRBD interacts directly with Tc 5S rRNA, but does not associate with polyadenylated RNA. TcP37/NRBD also associates in vivo and in vitro with large ribosomal protein TcL5 and, unlike the case of T. brucei, this association is strongly enhanced by the presence of 5S rRNA, suggesting that the loss of the C-terminal domain of TcP37/NRBD may alter the interactions within the complex. These results indicate that the unique preribosomal complex comprised of L5, 5S rRNA, and the trypanosome-specific TcP37/NRBD or TbP34 and TbP37 is functionally conserved in trypanosomes despite the differences in the C-termini of the trypanosome-specific protein components. 相似文献
490.
ClpX and ClpP are essential for the efficient acquisition of genes specifying type IA and IB restriction systems 总被引:7,自引:2,他引:5
Svetlana Makovets Annette J. B. Titheradge & Noreen E. Murray 《Molecular microbiology》1998,28(1):25-35
Efficient acquisition of genes that encode a restriction and modification (R–M) system with specificities different from any already present in the recipient bacterium requires the sequential production of the new modification enzyme followed by the restriction activity in order that the chromosome of the recipient bacterium is protected against attack by the restriction endonuclease. We show that ClpX and ClpP, the components of ClpXP protease, are necessary for the efficient transmission of the genes encoding Eco KI and Eco AI, representatives of two families of type I R–M systems, thus implicating ClpXP in the modulation of restriction activity. Loss of ClpX imposed a bigger barrier than loss of ClpP, consistent with a dual role for ClpX, possibly as a chaperone and as a component of the ClpXP protease. Transmission of genes specifying Eco KI was more dependent on ClpX and ClpP than transmission of the genes for Eco AI. Sensitivity to absence of the protease was also influenced by the mode of gene transfer; conjugative transfer and transformation were more dependent on ClpXP than transduction. In the absence of either ClpX or ClpP transfer of the Eco KI genes by P1-mediated transduction was impaired, transfer of the Eco AI genes was not. 相似文献