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81.
82.
Sarangi N.P. Athukorala Khalid Y. Rashid Teresa de Kievit 《Biocontrol Science and Technology》2010,20(8):875-890
Pseudomonas chlororaphis strain PA23 has demonstrated excellent biocontrol in the canola phyllosphere. This bacterium produces the non-volatile antibiotics phenazine and pyrrolnitrin as well as the volatile antibiotics nonanal, benzothiazole and 2-ethyl-1-hexanol. In vitro experiments were conducted to study the effects of different mutations on the production of these three organic volatile antibiotics by PA23. In planta experiments in the greenhouse investigated the role of the non-volatile antibiotics on root colonization and biocontrol ability of PA23 against Sclerotinia sclerotiorum on sunflower. Analysis of phenazine- and pyrrolnitrin-deficient Tn mutants of PA23 revealed no differences in production of the three volatile antibiotics. On all sampling dates, PA23 applied alone or in combination with the mutants showed significantly higher (P = 0.05) root bacterial number and Sclerotinia wilt suppression (P = 0.05). Decline of the bacterial population seemed to be inversely proportional to/or negatively correlated with the number of antibiotics produced by PA23 but the relative importance of phenazine or pyrrolnitrin on root colonization and/or wilt suppression was not clear. In several cases, the strains producing at least one antibiotic maintained relatively higher bacterial numbers than non-producing strains. However, by 6 weeks after sowing, there was a rapid and significant (P = 0.05) increase in the proportion of introduced bacteria capable of producing at least one antibiotic over the total bacterial population. Furthermore, combining certain mutants with PA23 reduced the root colonization and biocontrol ability of PA23. Strain PA23-314 (gacS mutant) showed competitive colonization in comparison to the other mutants for most sampling dates. 相似文献
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Murai T Mohamed M Bernard H Mahedi PA Saburi R Higashi S 《Primates; journal of primatology》2007,48(2):117-121
Successful or unsuccessful female transfers were observed seven times during a 32-month field study of proboscis monkeys (Nasalis larvatus) inhabiting a riverine forest along a tributary of the Kinabatangan River, Sabah, Malaysia. In all cases, the females voluntarily
left their own groups and immediately joined with another one. When adult females tried to shift to other groups, adult males
called them back to their own groups, but appeared to be indifferent to subadult females. When the adult females returned,
the males never attacked the females physically, but instead often emitted herding sounds to them. One subadult female was
repelled by a resident adult female. When one adult female transferred into a new one-male group, she left her behind son
in an all-male group. The number of females often fluctuated in most study groups, with this fluctuation being more prominent
among subadult females than adult females. It is likely that female transfer in proboscis monkeys is not a rare occurrence
and that it is especially common among sub-adult females. 相似文献
86.
Anthemis cotula is a widespread invasive alien species in Kashmir Himalaya. Being a winter annual, the species reproduces entirely by achenes and synchrony between germination requirements of the species and the habitat conditions must be of critical importance in its invasiveness. To examine how the achenes of different ages respond to different environmental cues, two laboratory experiments were performed wherein effects of different nitrogen applications and growth hormones under continuous light and dark conditions were explored. Results show that the achenes are positively photoblastic and have requirement for after‐ripening. Nitrogen applied either as potassium nitrate or as thiourea significantly improved achene germination both under continuous light and dark conditions. Although kinetin (6‐furfurylaminopurine) did not influence achene germination, gibberellic acid (GA3) applied at 1.0 mM concentration had the most significant effect on the final percentage germination under both light and dark conditions. These results suggest that the achenes have an elaborate mechanism of sensing the habitat conditions that helps them to synchronise their germination with favourable environmental conditions – a strategy that aids the species in ensuring recruitment, survival and its spread in Kashmir Himalaya. 相似文献
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Sojka D Hajdusek O Dvorák J Sajid M Franta Z Schneider EL Craik CS Vancová M Buresová V Bogyo M Sexton KB McKerrow JH Caffrey CR Kopácek P 《International journal for parasitology》2007,37(7):713-724
Ticks are ectoparasitic blood-feeders and important vectors for pathogens including arboviruses, rickettsiae, spirochetes and protozoa. As obligate blood-feeders, one possible strategy to retard disease transmission is disruption of the parasite's ability to digest host proteins. However, the constituent peptidases in the parasite gut and their potential interplay in the digestion of the blood meal are poorly understood. We have characterised a novel asparaginyl endopeptidase (legumain) from the hard tick Ixodes ricinus (termed IrAE), which we believe is the first such characterisation of a clan CD family C13 cysteine peptidase (protease) in arthropods. By RT-PCR of different tissues, IrAE mRNA was only expressed in the tick gut. Indirect immunofluorescence and EM localised IrAE in the digestive vesicles of gut cells and within the peritrophic matrix. IrAE was functionally expressed in Pichia pastoris and reacted with a specific peptidyl fluorogenic substrate, and acyloxymethyl ketone and aza-asparagine Michael acceptor inhibitors. IrAE activity was unstable at pH > or = 6.0 and was shown to have a strict specificity for asparagine at P1 using a positional scanning synthetic combinatorial library. The enzyme hydrolyzed protein substrates with a pH optimum of 4.5, consistent with the pH of gut cell digestive vesicles. Thus, IrAE cleaved the major protein of the blood meal, hemoglobin, to a predominant peptide of 4kDa. Also, IrAE trans-processed and activated the zymogen form of Schistosoma mansoni cathepsin B1 -- an enzyme contributing to hemoglobin digestion in the gut of that bloodfluke. The possible functions of IrAE in the gut digestive processes of I. ricinus are compared with those suggested for other hematophagous parasites. 相似文献
88.
Microresonator mass sensors for detection of Bacillus anthracis Sterne spores in air and water 总被引:1,自引:0,他引:1
Angelica P. Davila Jaesung Jang Amit K. Gupta Tom Walter Arthur Aronson Rashid Bashir 《Biosensors & bioelectronics》2007,22(12):3028
Towards the goal of developing a real-time monitoring device for microorganisms, we demonstrate the use of microcantilevers as resonant mass sensors for detection of Bacillus anthracis Sterne spores in air and liquid. The detection scheme was based on measuring resonant frequency decrease driven by thermally induced oscillations, as a result of the added mass of the spores with the use of a laser Doppler vibrometer (LDV). Viscous effects were investigated by comparing measurements in air and deionized (DI) water along with theoretical values. Moreover, biological experiments were performed which involved suspending spores onto the cantilevers and performing mass detection in air and water. For detection of spores in water, the cantilevers were functionalized with antibodies in order to fix the spores onto the surface. We demonstrate that as few as 50 spores on the cantilever can be detected in water using the thermal noise as excitation source. Measurement sensitivity of 9.23 Hz/fg for air and 0.1 Hz/fg for water were obtained. These measurements were compared with theoretical values and sources of improvement in cantilever sensitivity in a viscous medium were also discussed. It is expected that by driving the cantilevers and using higher order modes, detection of a single spore in liquids should be achievable. 相似文献
89.
Seasonality and historic trends in the reef fisheries of Pulau Banggi, Sabah, Malaysia 总被引:2,自引:0,他引:2
L. S. L. Teh D. Zeller A. Cabanban L. C. L. Teh U. Rashid Sumaila 《Coral reefs (Online)》2007,26(2):251-263
The reef fisheries of Pulau (meaning “island” in Malay) Banggi, Sabah are not managed, and lack baseline fisheries data despite
forming part of a proposed marine park. Thus, a combination of qualitative and quantitative approaches was applied to obtain
a baseline picture about the past and present state of the fisheries. Fish landings were monitored, and fisher interviews
conducted to investigate seasonal effects and historical changes in Banggi’s reef fisheries. Monsoon winds were a major driver
of seasonal differences in catch quantities for the hook and line, but not the gillnet fishery. Spatial distribution of fishing
effort and target species also differed by season. Fishers consistently indicated that Banggi’s fisheries were declining,
with a suggested three to four times decrease in catch rates over the last 20 years. Interestingly, it appeared that substantial
decreases began in the year 2000. The responses of fishers to seasonal changes, and the resultant implications for management
are discussed. Importantly, the need for immediate management policies to prevent further declines and to maintain sustainable
reef fisheries is stressed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
L. S. L. TehEmail: |
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