Cell wall disassembly during papaya softening: Role of ethylene in changes in composition,pectin-derived oligomers (PDOs) production and wall hydrolases     

J. Adriana Sañudo-Barajas  John Labavitch  Carl Greve  Tomás Osuna-Enciso  Dolores Muy-Rangel  Jorge Siller-Cepeda 《Postharvest Biology and Technology》2009,51(2):158-167

Cell wall disassembly in ripening climacteric fruit is a highly complex process where ethylene plays a crucial role. Ethylene inhibitors can be used to explore the changes in the cell wall matrix and cross-linked polysaccharides in ethylene-regulated processes. The results of applying the ethylene receptor blocking inhibitor 1-methylcyclopropene (1-MCP) and the ethylene-releasing compound ethephon (2-chloroethylphosphonic acid) indicate that softening of ‘Maradol’ papaya fruit is dependent on ethylene. When fruit were induced to ripen extensively by exposure to a high dose of ethephon, 1-MCP inhibited the subsequent softening dramatically, but when inhibition of the ethylene response was caused by application of 1-MCP, subsequent fruit treatment with ethephon promoted extensive loss of galactose from the water-soluble polysaccharides, but this was not accompanied by fruit softening. The cell wall changes accompanying normal fruit softening were pectin solubilization and polyuronide depolymerization and these processes occurred simultaneously. Polygalacturonase likely is responsible for the ripening-associated changes in ‘Maradol’ papaya fruit texture and pectin polymer integrity. An increase in extractable fruit polygalacturonase follows the increased presence of pectin-derived oligosaccharides.  相似文献   

Report on the growth of rabbit fish in fish ponds in Fiji     

Tom Lichatowich  Dan Popper 《Aquaculture (Amsterdam, Netherlands)》1975,5(2):211-212

Some data are presented about the gain in weight of rabbit fishes (Siganus vermiculatus) grown at different densities in dirt ponds.  相似文献   

Evaluation of crossbred Brahman and continental European beef cattle in a subtropical environment for birth and weaning traits     

W D Williamson  P E Humes 《Journal of animal science》1985,61(5):1137-1145

A total of 528 birth and 475 weaning records collected over a 3-yr period were analyzed to evaluate the productivity of several beef cattle breed crosses. The calves were produced by artificial insemination using 17 Brahman, 15 Chianina, 15 Maine Anjou and 16 Simmental sires bred to Angus and Hereford dams varying in age from 3 to 11 yr. Breed-of-sire effects were important (P less than .05 to P less than .001) for gestation length, birth weight, conformation score and condition score, but were not observed for birth weight adjusted for gestation length, percentage calving assistance, survival rate or weaning weight. Brahman crosses had the longest gestation lengths, being 4.7 d longer than Simmental crosses, which were the shortest in length. Chianina crosses were the heaviest at birth and experienced the most calving difficulty. Simmental crosses had the highest survival rate. Although breed-of-sire differences were observed in conformation score, the difference was less than one-third of a grade between the highest-scoring Simmental crosses and the lowest-scoring Brahman and Chianina crosses. Brahman crosses had the highest condition scores, being approximately one-third of a grade higher than the lowest-ranking Chianina crosses. Differences among the sire breeds for weaning weight were surprisingly small, varying only 3 kg from the heaviest to lightest breed-of-sire groups. Angus dams had shorter gestation lengths (P less than .001) and produced calves that weighed more at weaning (P less than .001) and scored higher for conformation (P less than .001) and condition (P less than .001) score than Hereford dams.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Determining reference values for stem water potential and maximum daily trunk shrinkage in young apple trees based on plant responses to water deficit   总被引：1，自引：0，他引：1  

Tom De Swaef  Kathy Steppe  Raoul Lemeur 《Agricultural Water Management》2009,96(4):541-550

The use of plant water status indicators such as midday stem water potential (Ψ_stem) and maximum daily trunk shrinkage (MDS) in irrigation scheduling requires the definition of a reference or threshold value, beyond which irrigation is necessary. These reference values are generally obtained by comparing the seasonal variation of plant water status with the environmental conditions under non-limiting soil water availability. In the present study an alternative approach is presented based on the plant’s response to water deficit. A drought experiment was carried out on two apple cultivars (Malus domestica Borkh. ‘Mutsu’ and ‘Cox Orange’) in which both indicators (Ψ_stem and MDS) were related to several plant physiological responses. Sap flow rates, maximum net photosynthesis rates and daily radial stem growth (DRSG) (derived from continuous stem diameter variation measurements) were considered in the assessment of the approach. Depending on the chosen plant response in relationship with Ψ_stem or MDS, the obtained reference values varied between −1.04 and −1.46 MPa for Ψ_stem and between 0.17 and 0.28 mm for MDS. In both cultivars, the approach based on maximum photosynthesis rates resulted in less negative Ψ_stem values and smaller MDS values, compared to the approaches with sap flow and daily radial stem growth. In the well-irrigated apple trees, day-to-day variations in midday Ψ_stem and MDS were related to the evaporative demand. These variations were more substantial for MDS than for midday Ψ_stem.  相似文献   

Integrated modelling of natural and social systems in land change science   总被引：1，自引：0，他引：1  

Eleanor Milne  Richard J. Aspinall  Tom A. Veldkamp 《Landscape Ecology》2009,24(9):1145-1147

  相似文献   

Microstructure of wood char     

J. B. Zicherman  R. B. Williamson 《Wood Science and Technology》1981,15(4):237-249

Summary Past research on the combustion and pyrolysis of wood have often indicated a link between wood microstructure and its observed properties in fire exposure. The present research, after utilizing an instrumented fire exposure shown to simulate actual fire conditions, examines the microstructure of fire damaged wood and considers the implications of microstructural changes seen on the burning process.Differences in microstructural detail between wood and char, as well as fissure geometry, were shown to be consistent. The demarcation between damaged and undamaged wood was shown to be extremely small (several cell layers in thickness). The resulting microstructural observations are considered in light of published kinetic data on wood combustion and current theories and data on thermal degradation of wood.The authors wish to acknowledge the general support of the University of California Forest Products Laboratory as well as grant support to the University of California Berkeley Fire Research Group (NSF-Rann-S-22053, NFPCA-S-22584), University of California Berkeley Electron Microscopy Lab. (NSF-GB-38359) and the University of California, Davis Department of Botany (NSF-GB-29653). In addition we would also like to thank Dr. Arno P. Schniewind, University of California Forest Products Laboratory and Dr. R. Falk, University of California, Davis, Department of Botany  相似文献   

Climatology of Acacia mearnsii. 1. Characteristics of natural sites and exotic plantations     

Trevor H. Booth  Tom Jovanovic 《New Forests》1988,2(1):17-30

Climatic variation in the natural distribution of Acacia mearnsii in Australia was analysed. Data from sites where the species has been successfully grown in plantations and trials in Africa, Asia and South America were used to determine the species' climatic adaptability. Annual mean temperatures at these plantations and trial sites ranged from 13.9 to 23.9°C, whilst annual mean precipitation ranged from 693 to 2263 mm. The coldest month minimum temperature at these sites was –0.6°C. This information, along with other details of climatic requirements presented in the paper, will assist in selecting sites for future trials at new locations.  相似文献   

Flavonol glycosides from Aconitum vulparia   总被引：1，自引：0，他引：1  

Fico G  Braca A  Morelli I  Tomè F 《Fitoterapia》2003,74(4):420-422

The isolation of five flavonol glycosides (1-5) from the flowers of Aconitum vulparia is reported, together with the 1H- and 13C-NMR spectral data in CD(3)OD of compound 3 and 5.  相似文献   

<Emphasis Type="Italic">Pinus halepensis</Emphasis> somatic embryogenesis is affected by the physical and chemical conditions at the initial stages of the process     

Catia Pereira  Itziar Aurora Montalbán  Olatz García-Mendiguren  Tomás Goicoa  Maria Dolores Ugarte  Sandra Correia  Jorge Manuel Canhoto  Paloma Moncaleán 《Journal of Forest Research》2016,21(3):143-150

Pinus halepensis has been described as a drought-tolerant species with high plasticity to growth in different environments. Its eco-physiological characteristics could facilitate the use of this species in large afforestations in the future scenery of climate change. Somatic embryogenesis is a biotechnological tool with potential for large-scale clonal propagation. In order to establish an improved regeneration protocol for Pinus halepensis, the effects of different temperatures (18, 23, and 28 °C) and water availability conditions (2, 3, and 4 g L^?1 Gelrite^®), during initiation of embryonal masses on the rate of initiation, proliferation, maturation, and the number of embryos developed, were evaluated. It was found that environmental conditions during the initiation stage of Pinus halepensis somatic embryogenesis influence the success of initiation and proliferation. In contrast, there was no effect of these conditions on the maturation rates and the number of somatic embryos. Somatic embryos were obtained in all treatments tested, indicating that plants can be produced from extreme conditions of induction, such as high temperatures (28 °C) and low water availability conditions (4 g L^?1).  相似文献   

New prenylflavans from Cyperus conglomeratus     

Abdel-Razik AF  Nassar MI  El-Khrisy ED  Dawidar AA  Mabry TJ 《Fitoterapia》2005,76(7-8):762-764

In addition to luteolin and its 7-methyl ether, the CH2Cl2-MeOH (1:1) extract of Cyperus conglomeratus afforded two new prenylflavans identified as 7,3'-dihydroxy-5,5'-dimethoxy-8-prenylflavan and 5,7,3'-trihydroxy-5'-methoxy-8-prenylflavan. The structures were established by CIMS, 1H-NMR, 13C-NMR, H-H COSY, HMQC, HMBC and DEPT analysis.  相似文献