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91.
El-Sayed A. Kassim 《Microbiology and immunology》1982,26(6):449-454
Cellulase enzyme was produced by a selected strain of Aspergillus niger isolated from deteriorated wood and grown on different carbon sources. Filter paper gave the highest yield, followed by carboxymethyl cellulose (CMC). Cellobiose as well as glucose gave a low yield, while the yield from lactose was negligible. The concentration of filter paper cellulose that induced the maximum yield of the enzyme was 1%. Both soluble cellulose (CMC) and cotton cellulose treated with phosphoric acid (swollen) were easily hydrolyzed by cellulase; an increase in cellulase concentration lead to more hydrolysis of CMC and gave linearity in the reaction velocity. At certain concentrations of the enzyme, increase in CMC concentration, (up to 1%) resulted in more reducing sugar. Beyond this point no more hydrolysis occur. 相似文献
92.
Alhaji Hamisu Maimusa Abu Hassan Ahmad Nur Faeza Abu Kassim Hamdan Ahmad Hamady Dieng Junaid Rahim Muhammad Ahmad Dahiru 《Entomological Research》2019,49(2):87-92
This study was conducted to isolate and identify lactobacilli from larval and adult midgut of wild Aedes aegypti (Ae. aegypti) to find candidate bacteria for paratransgenic control. Characterization of the bacterial symbionts was done using Gram staining, motility test, catalase test, and biochemical tests, among others, and the morphological features were confirmed using a standard scheme that simplifies the identification of lactic acid bacteria. A total of 174 strains were isolated and identified, 135 strains from larval midgut and 39 strains from adult midgut (mean ± SE, 4.00 ± 0.72; P = 0.00). The isolated species were confirmed to be Lactobacillus fermentum, L. casei, L. acidophilus, L. viridescens, L. brevis and L. gasseri. It can be concluded that Ae. aegypti has the potential of harboring the cultivable bacterial symbionts. In conclusion, the isolated species were nominated for paratransgenic control, particularly L. fermentum, being found in large numbers from both larval and adulxt midgut. 相似文献
93.
SX Dong SJ Davies PS Ashton S Bunyavejchewin MN Supardi AR Kassim S Tan PR Moorcroft 《Proceedings. Biological sciences / The Royal Society》2012,279(1744):3923-3931
The response of tropical forests to global climate variability and change remains poorly understood. Results from long-term studies of permanent forest plots have reported different, and in some cases opposing trends in tropical forest dynamics. In this study, we examined changes in tree growth rates at four long-term permanent tropical forest research plots in relation to variation in solar radiation, temperature and precipitation. Temporal variation in the stand-level growth rates measured at five-year intervals was found to be positively correlated with variation in incoming solar radiation and negatively related to temporal variation in night-time temperatures. Taken alone, neither solar radiation variability nor the effects of night-time temperatures can account for the observed temporal variation in tree growth rates across sites, but when considered together, these two climate variables account for most of the observed temporal variability in tree growth rates. Further analysis indicates that the stand-level response is primarily driven by the responses of smaller-sized trees (less than 20 cm in diameter). The combined temperature and radiation responses identified in this study provide a potential explanation for the conflicting patterns in tree growth rates found in previous studies. 相似文献
94.
L. Banin T. R. Feldpausch O. L. Phillips T. R. Baker J. Lloyd K. Affum‐Baffoe E. J. M. M. Arets N. J. Berry M. Bradford R. J. W. Brienen S. Davies M. Drescher N. Higuchi D. W. Hilbert A. Hladik Y. Iida K. Abu Salim A. R. Kassim D. A. King G. Lopez‐Gonzalez D. Metcalfe R. Nilus K. S.‐H. Peh J. M. Reitsma B. Sonké H. Taedoumg S. Tan L. White H. Wöll S. L. Lewis 《Global Ecology and Biogeography》2012,21(12):1179-1190
95.
Five independent tobacco regenerant clones obtained after transformation withAgrobdcterium rhizogenes strain TR101 (four clones of the T phenotype, clone 5 a mixture of plants of the T and T′ phenotypes) and untransformed plants
cultivatedin vitro were gradually acclimated to the atmosphere and transferred to the soil substrate in pots. During 28 d after transplanting
the increase of the leaf area was in T phenotype plants greater than in untransformed plants, but 14 d later no significant
differences were observed between T phenotype and untransformed plants in leaf area and dry matter. T′phenotype plants, however,
had significantly lower values in all growth parameters than T phenotype and control plants. Abaxial net photosynthetic CO2 uptake (PN) was in both T (clones 1–4) and T′ plants significantly lower than that in control and clone 5T plants. Nevertheless,
due to the relatively higher adaxial PN in T plants, the total PN through both leaf surfaces was significantly lower only
in clone 4 and clone 5′ plants. The tendency to higher transpiration rates (E) in clones 1 – 4 in comparison with the control
resulted in significant differences in water use efficiency (W.U.E.). Relatively higher E in T plants of clones 1 – 4 was
connected most probably with their more developed root system (greater root dry-matter) than in untransformed plants, because
no influence of the differences in stornata density on E was found. 相似文献
96.
97.
The extent to which environmental heterogeneity can account for tree species coexistence in diverse ecosystems, such as tropical rainforests, is hotly debated, although the importance of spatial variability in contributing to species co-existence is well recognized. Termites contribute to the micro-topographical and nutrient spatial heterogeneity of tropical forests. We therefore investigated whether epigeal termite mounds could contribute to the coexistence of plant species within a 50 ha plot at Pasoh Forest Reserve, Malaysia. Overall, stem density was significantly higher on mounds than in their immediate surroundings, but tree species diversity was significantly lower. Canonical correspondence analysis showed that location on or off mounds significantly influenced species distribution when stems were characterized by basal area. Like studies of termite mounds in other ecosystems, our results suggest that epigeal termite mounds provide a specific microhabitat for the enhanced growth and survival of certain species in these species-rich tropical forests. However, the extent to which epigeal termite mounds facilitate species coexistence warrants further investigation. 相似文献
98.
Edwige Sopie Yapo Tanoh Hilaire Kouakou Mongomaké Kone Justin Yatty Kouadio Patrice Kouame Jean-Michel Merillon 《Journal of plant biochemistry and biotechnology.》2011,20(2):196-204
An efficient protocol for a complete plant regeneration by somatic embryogenesis was developed with Smooth Cayenne pineapple (Ananas comosus L.). Previous works showed that this species is responsive to somatic embryogenesis. In the present work the influence of components of culture medium in the induction, development and conversion of somatic embryos was investigate in order to establish a somatic embryogenesis protocol. Nodular callus (83.67%) was initiated from leaf explants of young plants on CIM3 medium. The highest frequency (37.6%) of embryogenic callus induction was obtained from 4-week-old calluses on EIM3 medium supplemented with 3.0 mg/l picloram. The highly organized callus induction and the development of somatic embryos were achieved after the transfer of callus clumps onto EIM3 medium containing 1.0 mg/l BAP + 0.1 mg/l NAA. The frequency of somatic embryo formation was of 39.5?±?2.45 embryos per callus. Up to 97% of the somatic embryos were converted into complete plants within 4 week on MSB medium with 1.0 mg/l BAP + 0.05 mg/l GA3 + 500 mg/l glutamine. The continuation of the elongation of the shoots occurred on this medium). Shoots obtained from all the above methods were rooted in MSB medium with activated charcoal. Complete plantlets were transferred onto specially made polyethylene bags containing soil mixture and transferred to the greenhouse. Survival rate of the plantlets under ex vitro conditions was 98% and maximum average number of plantlets (80?±?0.6). The well-developed plantlets were transferred to an open field where the plants produced normal fruits. 相似文献
99.
Vanessa J. Kelly Tilo Winkler Jose G. Venegas Mamary Kone Daniel L. Hamilos Roshi Afshar Josalyn L. Cho Andrew D. Luster Benjamin D. Medoff R. Scott Harris 《PloS one》2015,10(12)
Background
Allergic non-asthmatic (ANA) adults experience upper airway symptoms of allergic disease such as rhinorrhea, congestion and sneezing without symptoms of asthma. The aim of this study was to utilize PET-CT functional imaging to determine whether allergen challenge elicits a pulmonary response in ANA subjects or whether their allergic disease is truly isolated to the upper airways.Methods
In 6 ANA subjects, bronchoalveolar lavages (BAL) were performed at baseline and 24h after instillation of an allergen and a diluent in separate lung lobes. After instillation (10h), functional imaging was performed to quantify and compare regional perfusion, ventilation, fractional gas content (Fgas), and glucose uptake rate (Ki) between the baseline, diluent and allergen lobes. BAL cell counts were also compared.Results
In ANA subjects, compared to the baseline and diluent lobes, perfusion and ventilation were significantly lower in the allergen lobe (median [inter-quartile range], baseline vs. diluent vs. allergen: Mean-normalized perfusion; 0.87 [0.85–0.97] vs. 0.90 [0.86–0.98] vs. 0.59 [0.55–0.67]; p<0.05. Mean-normalized ventilation 0.89 [0.88–0.98] vs. 0.95 [0.89–1.02] vs. 0.63 [0.52–0.67], p<0.05). In contrast, no significant differences were found in Fgas between baseline, diluent and allergen lobes or in Ki. Total cell counts, eosinophil and neutrophil cell counts (cells/ml BAL) were significantly greater in the allergen lobe compared to the baseline lobe (all P<0.05).Conclusions
Despite having no clinical symptoms of a lower airway allergic response (cough and wheeze) allergic non-asthmatic subjects have a pulmonary response to allergen exposure which manifests as reduced ventilation and perfusion. 相似文献100.
Adam Konečný Arnaud Estoup Jean‐Marc Duplantier Josef Bryja Khalilou Bâ Maxime Galan Caroline Tatard Jean‐Francois Cosson 《Molecular ecology》2013,22(2):286-300
An understanding of the evolutionary history and dynamics of invasive species is required for the construction of predictive models of future spread and the design of biological management measures. The black rat (Rattus rattus) is a major vertebrate invader with a worldwide distribution. Despite the severe ecological, economic and health impacts of this species, its evolutionary history has been little studied. We carried out extensive specimen sampling in Senegal, West Africa, and used microsatellite markers to describe the pattern and processes of invasion in this large continental area. The genetic data obtained were combined with historical knowledge concerning the presence of this species in Senegal. Data were analysed by a combination of Bayesian clustering and approximate Bayesian computation methods. The invasion pathways closely paralleled the history of human trade routes in Senegal. In several places, we detected the occurrence of multiple introductions from genetically different sources. Long‐distance migration between towns and villages was also observed. Our findings suggest that genetic bottlenecks and admixture have played a major role in shaping the genetics of invasive black rats. These two processes may generate genetic novelty and favour rapid evolution along the invasion pathways. 相似文献