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Leaf age effects on the leaf conductance to water vapour diffusionof the adaxial and abaxial leaf surfaces were measured in themorning and in the afternoon on 17 different plantain and banana(Musa spp.) genotypes. The irradiance levels increased three-foldwhile leaf to air vapour pressure deficit levels increased two-to four-fold from morning to afternoon during the sampling periodin a field site located in the humid forest-moist savanna transitionzone of Nigeria. Conductance values were reduced in older, andsenescing leaves relative to the young and mature leaves bothin the morning and in the afternoon. Conductances were higherfor the abaxial leaf surfaces than the adaxial surface and higherin the afternoon than in the morning, with some genotypic differences.Lower values of leaf conductance to water vapour in the afternoonunder a short dry spell was sufficiently variable (P 0·05)among the test genotypes to indicate potential adaptation totransient dry conditions. Differential and relative leaf conductanceadjustments were noted among genotypes experiencing a shortdry spell versus non-limiting soil moisture conditions. Significantgenotypic differences were observed for leaf conductance amongthe 17 genotypes during the afternoon on the lower leaf surfaceof younger leaves. ABB cooking banana cultivars 'Fougamou' and'Bluggoe' might be potentially promising cultivars for transientdry conditions while AAB plantain 'Bobby Tannap' and one ofits hybrids TMPx 582-4 could be very sensitive to short dryspells according to this evaluation.Copyright 1994, 1999 AcademicPress Musa spp., Musa hybrids, adaxial leaf surface, abaxial leaf surface, stomatal response 相似文献
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Tan Laura X. L. van Dongen Wouter F. D. Sherman Craig D. H. Ekanayake Kasun B. Dann Peter Sutherland Duncan R. Weston Michael A. 《Biological invasions》2021,23(8):2485-2487
Biological Invasions - A correction to this paper has been published: https://doi.org/10.1007/s10530-021-02548-x 相似文献
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Ekanayake PM Kang HS De Zyosa M Jee Y Lee YH Lee J 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2006,145(3-4):318-324
The mitochondrial enzyme manganese superoxide dismutase (mitMn-SOD) is one of the antioxidant enzymes involved in cellular defense against oxidative stress and catalyzes the conversion of O2− into the stabler H2O2. In this study, a putative gene encoding Mn-SOD from disk abalone (Haliotis discus discus, aMn-SOD) was cloned, sequenced, expressed in Escherichia coli K12(TB1) and the protein was purified using pMAL protein purification system. Sequencing resulted ORF of 681 bp, which corresponded to 226 amino acids. The protein was expressed in soluble form with molecular weight of 68 kDa including maltose binding protein and pI value of 6.5. The fusion protein had 2781 U/mg activity. The optimum temperature of the enzyme was 37 °C and it was active in a range of acidic pH (from 3.5 to 6.5). The enzyme activity was reduced to 50% at 50 °C and completely heat inactivated at 80 °C. The alignment of aMn-SOD amino acid sequence with Mn-SODs available in NCBI revealed that the enzyme is conserved among animals with higher than 30% identity. In comparison with human mitMn-SOD, all manganese-binding sites are also conserved in aMn-SOD (H28, H100, D185 and H189). aMn-SOD amino acid sequence was closer to that of Biomphalaria glabrata in phylogenetic analysis. 相似文献
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doi: 10.1111/j.1741‐2358.2011.00518.x Relationship between nutritional status and tooth loss in an older population from Sri Lanka Objective: To determine the relationship between tooth loss and nutritional status in older individuals in Sri Lanka. Background: In developing countries, both the prevalence of malnutrition and oral disease are high among older individuals. Materials and methods: Four hundred and eighty subjects aged 60 years and above were selected to be included in the sample, of which 437 responded giving an overall response rate of 91%. Data were collected by means of an interviewer administered questionnaire, an oral examination and a physical examination to determine height and weight to calculate the body mass index (BMI). Results: Based on the WHO cut‐offs for BMI, 62, 20 and 18% of the sample were normal, under‐ and over‐weight, respectively. A multinomial logistic regression analysis with normal weight as the reference category revealed that missing teeth and denture status were associated with being underweight but not with being overweight. Conclusion: In older individuals, tooth loss is significantly associated with being underweight. 相似文献
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Wui Ann Woon Paul B. Ravindran Piyasiri Ekanayake Siti Amirah Yivonne Y.F. Lim Christopher H.S. Vun Jamsari Khalid 《Reports of Practical Oncology and Radiotherapy》2018,23(5):346-359
Aim
The aim of this study was to investigate the sensitivity of the trajectory log file based quality assurance to detect potential errors such as MLC positioning and gantry positioning by comparing it with EPID measurement using the most commonly used criteria of 3%/3?mm.Materials and methods
An in-house program was used to modified plans using information from log files, which can then be used to recalculate a new dose distribution. The recalculated dose volume histograms (DVH) were compared with the originals to assess differences in target and critical organ dose. The dose according to the differences in DVH was also compared with dosimetry from an electronic portal imaging device.Results
In all organs at risk (OARs) and planning target volumes (PTVs), there was a strong positive linear relationship between MLC positioning and dose error, in both IMRT and VMAT plans. However, gantry positioning errors exhibited little impact in VMAT delivery. For the ten clinical cases, no significant correlations were found between gamma passing rates under the criteria of 3%/3?mm for the composite dose and the mean dose error in DVH (r?<?0.3, P?>?0.05); however, a significant positive correlation was found between the gamma passing rate of 3%/3?mm (%) averaged over all fields and the mean dose error in the DVH of the VMAT plans (r?=?0.59, P?<?0.001).Conclusions
This study has successfully shown the sensitivity of the trajectory log file to detect the impact of systematic MLC errors and random errors in dose delivery and analyzed the correlation of gamma passing rates with DVH. 相似文献7.
Plants are widely used in soil conservation to control and prevent erosion on hillslopes and on riverbanks. Previous research has shown the mechanical root reinforcement on soil stability can be considerable. However, land and forest managers still require information and simple tools to enable them to determine how and when a species becomes effective in terms of soil stabilisation. This paper uses root length data from a trial of young New Zealand trees and shrubs to develop a simple model to account for the spatial occupancy of a planting site by roots, and by implication their potential strength contribution to soil reinforcement. It is developed by calculating root surface area in contact with the soil to obtain an effective radius of the root spread about the stem. The approach generates a set of coefficients that are unique to a species for a given site which can then be used in the generalised model to predict root site occupancy, which is taken as a proxy for when soil reinforcement is attained. This information can then be used to assess effectiveness of different species mixes in planting plans. 相似文献
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Among vertebrates, some teleosts are unique in having bone which lacks osteocytes embedded in the matrix. The fate of cells that secrete the matrix of these acellular bones has not been investigated thoroughly. Histological and fluorescent microscopic analysis of the vertebral bone of Oryzias latipes demonstrated that acellularity is not a secondary appearance of an early cellular bone during ontogeny. Vertebral bone is devoid of cells embedded in the matrix throughout development. Cells that secrete bone matrix do not become trapped in their own secretion. Instead, they always remain as a surface layer over the outer surface of the bone. Fluorescent microscopic visualization of tetracycline injected into growing fish demonstrated that bone was only deposited by osteoblasts lining the outer surface of the bone; no deposition of bone took place on the inner surface. 相似文献
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Saccharopine dehydrogenase catalyzes the NAD-dependent oxidative deamination of saccharopine to l-lysine and α-ketoglutarate. Lysine 99 is within hydrogen-bond distance to the α-carboxylate of the lysine substrate and D319 is in the vicinity of the carboxamide side chain of NADH. Both are conserved and may be important to the overall reaction. Replacing K99 with M gives decreases of 110-, 80- and 20-fold in the V(2)/K(m) values for lysine, α-ketoglutarate and NADH, respectively. Deuterium isotope effects on V and V/K(Lys) increase, while the solvent deuterium isotope effects decrease compared to the C205S mutant enzyme. Data for K99M suggest a decreased affinity for all reactants and a change in the partition ratio of the imine intermediate to favor hydrolysis. A change in the bound conformation of the imine and/or the distance of the imine carbon to C4 of the nicotinamide ring of NADH is also suggested. Changing D319 to A decreases V(2)/K(NADH) by 33-fold. Primary deuterium and solvent deuterium isotope effects decrease compared to C205S suggesting a non-isotope sensitive step has become slower. NADH binds to enzyme first, and sets the site for binding of lysine and α-ketoglutarate. The slower step is likely the conformational change generated upon binding of NADH. 相似文献
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