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排序方式: 共有792条查询结果,搜索用时 218 毫秒
51.
水果形状的傅里叶描述子研究 总被引:15,自引:0,他引:15
水果的形状是水果分级的重要指标之一。本文研究了不规则物体形状的数学描述方法,认为在水果的分级过程中采用曲线拟合的方法来描述水果的形状是不合适的;提出了仅需利用物体的边界信息求物体的形心坐标和描述果形的新方法;发现用Fourier描述子的前4个谐波分量的变化特性就能较好地代表水果的形状,用前15个谐波分量来描述形状则可以达到相当高的精度。而且傅立叶描述子可以进行平移、旋转和缩放,并具有很强的水果外形重建功能,是一描述水果形状的非常有效的方法。 相似文献
52.
Exobasidium symploci-japonicae var. carpogenum, causing Exobasidium fruit deformation on Symplocos lucida collected in Fukuoka Prefecture, Japan, is newly described based on morphological observations of hymenial structure and mode of basidiospore germination. This new variety differs morphologically from the type variety, particularly in the septal number of basidiospores and in the shapes and sizes of conidia formed on the medium. Colonies of this new variety are also distinguishable from those of the type variety by yeast-like growth, morphology, and color of colonies.Contribution no.178, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Japan 相似文献
53.
How fruit abundance affects the chimpanzee party size: a comparison between four study sites 总被引:4,自引:0,他引:4
Hashimoto C Suzuki S Takenoshita Y Yamagiwa J Basabose AK Furuichi T 《Primates; journal of primatology》2003,44(2):77-81
We examined the relationship between fruit abundance and chimpanzee (Pan troglodytes) party size by comparing data from four study sites: the Kalinzu Forest Reserve, Uganda, the Djinji Camp and Guga Camp in
the Ndoki Forest, Congo, and Kahuzi-Biega National Park, Democratic Republic of Congo. Although the difference in the fruit
abundance between the sites was responsible for the difference in the party size between the sites, the seasonal changes in
fruit abundance did not explain the changes in the party size in each study site. Across the four study sites, there were
significant correlations of the mean and minimum of monthly party size with the mean of monthly fruiting-tree density, and
a significant correlation of the maximum of monthly party sizes with the minimum of monthly fruiting-tree density. We proposed
a hypothesis that (1) the monthly fruit abundance affects the monthly party size in the sites where the fruit availability
is as low as to limit the party size during a major part of a year, while (2) the party size does not increase with the increase
in the monthly fruit abundance, but is affected by other social factors, in the sites where the minimum of monthly fruit abundance
is high enough for chimpanzees to form parties of an adequate size.
Electronic Publication 相似文献
54.
Expression of cucumber lipid-body lipoxygenase in transgenic tobacco: lipid-body lipoxygenase is correctly targeted to seed lipid bodies 总被引:2,自引:0,他引:2
A particular isoform of lipoxygenase (LOX, EC 1.13.11.12) localized on lipid bodies has been shown by earlier investigations
to play a role during seed germination in initiating the mobilization of triacylglycerols. On lipid bodies of germinating
cucumber (Cucumis sativus L.) seedlings, the modification of linoleoyl moieties by this LOX precedes the hydrolysis of the ester bonds. We analyzed
the expression and intracellular location of this particular LOX form in leaves and seeds of tobacco (Nicotiana tabacum L.) transformed with one construct coding for cucumber lipid-body LOX and one construct coding for cucumber LOX fused with
a hemagglutinin epitope. In both tissues, the amount of lipid-body LOX was clearly detectable. Biochemical analysis revealed
that in mature seeds the foreign LOX was targeted to lipid bodies, and the preferred location of the LOX on lipid bodies was
verified by immunofluorescence microscopy. Cells of the endosperm and of the embryo exhibited fluorescence based on the immunodecoration
of LOX protein whereas very weak fluorescent label was visible in seeds of untransformed control plants. Further cytochemical
analysis of transformed plants showed that the LOX protein accumulated in the cytoplasm when green leaves lacking lipid bodies
were analyzed. Increased LOX activity was shown in young leaves of transformed plants by an increase in the amounts of endogenous
(2E)-hexenal and jasmonic acid.
Received: 9 August 1999 / Accepted: 28 September 1999 相似文献
55.
In order to clearly establish the properties of the enzymes responsible for hexose phosphorylation we have undertaken the
separation and characterization of these enzymes present in tomato fruit (Martinez-Barajas and Randall 1996). This report
describes the partial purification and characterization of glucokinase (EC. 2.7.1.1) from young green tomato fruit. The procedure
yielded a 360-fold enrichment of glucokinase. Tomato fruit glucokinase is a monomer with a molecular mass of 53 kDa. Glucokinase
activity was optimal between pH 7.5 and 8.5, preferred ATP as the phosphate donor (K
m = 0.223 mM) and exhibited low activity with GTP or UTP. The tomato fruit glucokinase showed highest affinity for glucose
(K
m = 65 μM). Activity observed with glucose was 4-fold greater than with mannose and 50-fold greater than with fructose. The tomato
fruit glucokinase was sensitive to product inhibition by ADP (K
i = 36 μM). Little inhibition was observed with glucose 6-phosphate (up to 15 mM) at pH 8.0; however, at pH 7.0 glucokinase
activity was inhibited 30–50% by physiological concentrations of glucose 6-phosphate.
Received: 4 October 1997 / Accepted: 10 January 1998 相似文献
56.
R. Socias i Company 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(5):588-601
The large size and the long generation time of fruit trees generally reduce the possibilities of obtaining genetic information
on the transmission and heritability of useful agronomic traits in these species. However, from breeding work carried out
with fruit trees, an important amount of data is now available, although large differences are apparent among the different
species. There is not much information known about almond compared to what is available on other Prunus fruit species, but more data have been accumulated on it than on most of the other nut trees, thus making almond special
among all the temperate fruit and nut species. Only five qualitative traits have been described in almond, with an additional
two also possibly qualitative. Heritabilities have been estimated for an important number of quantitative traits, mainly phenological
times and fruit characters. Important information is available on molecular markers, including enzymes, RFLPs, RAPDs and other
recently developed markers. Linkages, however, have only been established among molecular markers, allowing accurate genetic
maps to be built but not yet enabling agronomical characters to be located in these maps, probably because the latter have
not been sufficiently studied. The effectiveness of the application of genetic maps in plant breeding will depend on the accuracy
of the study of different agronomic traits and their expression, implying more field work and recognition of this work. Ultimately,
any new fruit cultivar has to be grown in the field and has to allow the grower to make a profit.
Received: 1 June 1997 / Accepted: 1 September 1997 相似文献
57.
58.
Unlike most pollinators, yucca moths are active pollinators of their host plants. Females lay their eggs in the flowers they pollinate, and their larvae feed solely on the resulting seeds. Previous evidence suggests that the yucca moth Tegeticula maculata avoids self-pollinating their host Yucca whipplei . Other yucca moths may self-pollinate more frequently. When pollinating, yucca moths are also reported to fly large distances between plants, bypassing neighbouring plants in the process. We experimentally verify the suggestion of Pellmyr et al . that yucca is more likely to retain fruits from self-pollination if overall fruit set is low. Thus, selection on moths to avoid self-pollinating should be density dependent. We found no evidence that mating with close neighbours resulted in inbreeding depression, thus the moth's long-distance flights between plants are yet to be explained. 相似文献
59.
1. Insect oral secretions are important for the induction of a number of plant responses, but the relative role of mechanical damage in the induction of these responses is often not well understood. Damage from the frugivore Heliothis subflexa, a specialist on Physalis species, causes herbivore‐induced fruit abscission. In this field study, we examined the separate and combined effects of mechanical damage and H. subflexa oral secretions on Physalis fruit abscission. 2. To determine the relative role of mechanical and chemical factors, the following treatments were administered to fruit: (1) three levels of mechanical damage, (2) natural herbivore damage by control larvae and by larvae surgically treated to inhibit saliva secretion, and (3) injection of H.subflexa oral secretions and a water control. Abscission of mechanically damaged fruit with and without the addition of oral secretions was also compared. 3. Mechanical damage was sufficient to cause fruit abscission, and the addition of oral secretions to mechanically damaged fruit did not cause an increase in fruit abscission. Normal caterpillars and those treated to inhibit saliva secretion caused similar abscission rates. 4. Though most studies examining the effects of insect oral secretions on induced plant responses find these chemical stimuli to be important or essential, the results of the present study showed that oral secretions are not necessary for fruit abscission. Future work is needed to determine the relative importance of mechanical damage in herbivore‐induced plant responses in other systems. 相似文献
60.
Vishwas A. Bapat Prabodh K. Trivedi Antara Ghosh Vidhu A. Sane Thumballi R. Ganapathi Pravendra Nath 《Biotechnology advances》2010
Development and ripening in fruit is a unique phase in the life cycle of higher plants which encompasses several stages progressively such as fruit development, its maturation, ripening and finally senescence. During ripening phase, several physiological and biochemical changes take place through differential expression of various genes that are developmentally regulated. Expression and/or suppression of these genes contribute to various changes in the fruit that make it visually attractive and edible. However, in fleshy fruit massive losses accrue during post harvest handling of the fruit which may run into billions of dollars worldwide. This encouraged scientists to look for various ways to save these losses. Genetic engineering appears to be the most promising and cost effective means to prevent these losses. Most fleshy fruit ripen in the presence of ethylene and once ripening has been initiated proceeds uncontrollably. Ethylene evokes several responses during ripening through a signaling cascade and thousands of genes participate which not only sets in ripening but also responsible for its spoilage. Slowing down post ripening process in fleshy fruit has been the major focus of ripening-related research. In this review article, various developments that have taken place in the last decade with respect to identifying and altering the function of ripening-related genes have been described. Role of ethylene and ethylene-responsive genes in ripening of fleshy fruit is also included. Taking clues from the studies in tomato as a model fruit, few case studies are reviewed. 相似文献