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排序方式: 共有262条查询结果,搜索用时 15 毫秒
101.
LARQUE-SAAVEDRA A.; RODRIGUEZ M. T.; TREJO C.; NAVA T. 《Journal of experimental botany》1985,36(11):1787-1792
Larqué-Saavedra, A., Rodriguez, M. T., Trejo, C. andNava, T. 1985. Abscisic acid accumulation and water relationsof four cultivars of Phaseolus vulgaris L. under drought.J.exp. Bot 36: 17871792. Plants of four cultivars of Phaseolus vulgaris L. differingin drought resistance were grown in pots under greenhouse conditionsand prior to flowering water was withheld from the pots untilthe mid-day transpiration rate reached values below 1.0 µgH2O cm2 s1 (designated the droughtstage). At this point leaves were harvested on 3 or 4 occasionsover 24 h to determine the abscisic acid (ABA) concentration,total water potential (), solute potential (1) and turgor potential(p). Results showed that values of , 1, and p differed between cultivarswhen they reached the drought stage. The stomatalsensitivity to changes in and p, was as follows: Michoacán12A3 > Negro 150 Cacahuate 72 > Flor de Mayo. These datacorrelated well with the pattern of drought resistance reportedfor the cultivars. ABA accumulation at the drought stage differedbetween cultivars at each sampling time, but overall differencesin ABA level between cultivars were not significant. ABA levelsdid not, therefore, correlate with the drought resistance propertiesreported for the cultivars. Results are discussed in relationto and hour of the day when bean samples were taken for ABAanalysis. Key words: Phaseolus vulgaris L., drought resistance, abscisic acid 相似文献
102.
103.
Ultrastructural Changes in Cotyledons of Pineapple Guava (Myrtaceae) During Somatic Embryogenesis 总被引:3,自引:0,他引:3
Ultrastructural studies (SEM and TEM) were performed on cotyledonsof pineapple guava ( Feijoa sellowiana Berg, Myrtaceae) inducedto form embryos on medium containing 1.0 mg l-1(4.5µM2,4-D) and 0.3M sucrose. At the time of culture, the cells werefilled with protein and lipid bodies. Microbodies and poorlydifferentiated organelles could also be seen. In contrast togerminating cotyledons, where lipid and protein reserves werequickly metabolized, cells of the embryogenically induced cotyledonsshowed evidence of reserve consumption only after 5 d of culture.Subepidermal cells of the upper cotyledonary surface underwentseveral divisions giving rise to a meristematic layer of severalcells thickness from which somatic embryos developed. Embryoscould also be formed directly by successive divisions of epidermalcells. Cells involved in somatic embryo formation containeda large nucleus with a conspicuous nucleolus and dense cytoplasmwhere numerous ribosomes, mitochondria, plastids with starchand short profiles of rough endoplasmic reticulum were present.Plasmodesmata were present both in cell walls of the meristematiccells and in few celled embryos whereas in degenerating embryosor in more advanced stages of somatic embryo development noplasmodesmata could be found. Although oil bodies were not observedin the meristematic cells they were identified in very youngembryos, being the first reserve compounds to appear. Cellsnot involved in somatic embryo differentiation were characterizedby the presence of several microbodies containing a crystalloidinclusion and elongated mitochondria. Feijoa sellowiana ; pineapple guava; somatic embryogenesis; ultrastructural studies 相似文献
104.
105.
N. PHILIP ASHMOLE PEDRO OROMÍ MYRTLE J. ASHMOLE JOSE L. MARTÍN 《Biological journal of the Linnean Society. Linnean Society of London》1992,46(1-2):207-234
Invertebrate communities in volcanic habitats of different ages on the islands of La Palma and El Hierro were studied using standardized trapping and searching techniques. A variety of graphical and numerical approaches were used to analyse relationships among the sites. Young, barren lava flows constitute aeolian ecosystems with a fauna of generalized detritivores and predators, especially collembolans, earwigs, thysamirans and crickets. Surface samples have many individuals and low diversity; those from caves have smaller numbers but similar taxonomic composition.
Vegetated surface habitats have richer communities, with diverse herbivores and predators but largely without the pioneer 'lavicolous' species. Caves with high humidity and stable temperature contain mainly specialized troglobitic species, but if there are both dry and humid sections lavicoles may also be present. Divergence into distinct epigean and hypogean communities results from both abiotic and biotic processes, including erosion and plant succession. While these occur mainly on the surface they also affect caves, increasing humidity and providing insulation from variations in external environmental conditions; the process is considered as a form of 'maturation' of the caves. Various models of succession are considered, which might help to account for the disappearance of lavicoles from mature epigean and hypogean communities. 相似文献
Vegetated surface habitats have richer communities, with diverse herbivores and predators but largely without the pioneer 'lavicolous' species. Caves with high humidity and stable temperature contain mainly specialized troglobitic species, but if there are both dry and humid sections lavicoles may also be present. Divergence into distinct epigean and hypogean communities results from both abiotic and biotic processes, including erosion and plant succession. While these occur mainly on the surface they also affect caves, increasing humidity and providing insulation from variations in external environmental conditions; the process is considered as a form of 'maturation' of the caves. Various models of succession are considered, which might help to account for the disappearance of lavicoles from mature epigean and hypogean communities. 相似文献
106.
THIERRY BACKELJAU ANTON J. DE WINTER RAMON MARTIN TERESA RODRIGUEZ LUC DE BRUYN 《Zoological Journal of the Linnean Society》1994,110(1):1-18
A comparison of the genital features of Arion urbiae and A. anguloi suggests that the species are extremely similar, if not identical. This hypothesis is supported by an electrophoretic analysis of 13 putative enzynme loci, which shows that the two species are also genetically yery similar (I = 0.947), while the related A. subfuscus consists of two distinct genetic types (I = 0.421). These results are further confirmed by a study of esterase profiles obtained with isoelectric focusing. It is therefore concluded that A. urbiae and A. anguloi are most probably conspecifie, whereas the genetic types of A. subfuscus may represent two different species. 相似文献
107.
ALBERTO BÚRQUEZ K. JOSE SARUKHÁAN ANA L. PEDROZA 《Botanical journal of the Linnean Society. Linnean Society of London》1987,94(4):407-419
A detailed account of the changes in visitor numbers and behaviour, inflorescence phenology, and breeding systems is presented. Inflorescences open early in the morning (05.00 hours). Stigmas remain receptive for 15 h, while anther dehiscence occurs 20 h after inflorescence opening. Maximum pollen viability occurs the next day at 05.00 hours. This combination of features largely precludes self-pollination. Controlled pollinations show that apomixis and auto-pollination are absent, and indicate strong incompatibility. In contrast, cross-pollinations do not differ in fruit set from open-pollinated controls. The fruit set in inflorescences exposed to pollinators for different periods after opening (and later stopping pollinator activity by fumigation), indicates that pollination occurs soon after inflorescence opening.
The visitors comprise a numerous and diverse fauna (15 families; 34 species). Features such as pollen loads, abundance, behaviour, and diet patterns, segregate them into: herbivores and predators (Aves, Orthoplera), pollen thieves (Apidae), and true pollinators (most Coleoptera and Diptera). The elevation in inflorescence temperature during opening, and 24 h later, is discussed in relation to cantharophily.
Astrocaryum mexicanum is an example of a highly diverse pollination system in which many animals can coexist. It represents an important resource during the dry season, and provides food and space for refuge and mating. The genetic consequences of having a host of pollinators with different dispersal capabilities are explored. 相似文献
The visitors comprise a numerous and diverse fauna (15 families; 34 species). Features such as pollen loads, abundance, behaviour, and diet patterns, segregate them into: herbivores and predators (Aves, Orthoplera), pollen thieves (Apidae), and true pollinators (most Coleoptera and Diptera). The elevation in inflorescence temperature during opening, and 24 h later, is discussed in relation to cantharophily.
Astrocaryum mexicanum is an example of a highly diverse pollination system in which many animals can coexist. It represents an important resource during the dry season, and provides food and space for refuge and mating. The genetic consequences of having a host of pollinators with different dispersal capabilities are explored. 相似文献
108.
BECANA MANUEL; APARICIO-TEJO PEDRO; PE?A JOSE; AGUIRREOLEA JONE; S?NCHEZ-D?AZ MANUEL 《Journal of experimental botany》1986,37(5):597-605
Nitrate and water stress were used to induce senescence in rootnodules of alfalfa (Medicago sativa L. cv. Aragon). Nodule senescencewas assessed by determinations of the nitrogenase (C2H2-reducing)activity, and the leghaemoglobin (LHb) and total soluble proteincontents of the nodules. Nodules responded similarly to and water stress in many respects, but there was a significant difference.All parameters of nodule activity, expressed on the basis ofnodule dry weight (DW), consistently decreased following treatmentwith or during drought; there was a significant interaction (synergism) between the inhibitory effects of and water stress on nitrogenase activity, but sucheffects were merely additive in the case of LHb content or LHb/solubleprotein ratio. However, caused the selective decay of LHb with respect to other nodular soluble proteins,whereas the decrease of LHb during water stress was due to ageneral inhibition of protein synthesis and to an increasedproteolytic activity in the nodule cytosol rather than to aspecific proteolysis of LHb. Key words: Leghaemoglobin, Medicago saliva, nitrogen fixation, root nodule senescence, water stress 相似文献
109.
CARLOS A. VEGA GERALD M. BUENING SERGIO D. RODRIGUEZ C. ANDREW CARSON 《The Journal of eukaryotic microbiology》1986,33(4):514-518
ABSTRACT. Clones of in vitro-cultured Babesia bigemina-infected erythrocytes were concentrated by several density gradient procedures. The density range of infected erythrocytes containing pairs of parasites was 1.077 to 1.089 g/ml, whereas the density range of infected erythrocytes containing single parasites was 1.092 to 1.100 g/ml. Three enzymes-lactate dehydrogenase, glucose-phosphate isomerase, and glutamate dehydrogenase-were found associated with infected erythrocytes. The parasite-specific enzyme and/or isoenzymes were shown to have different mobility patterns in starch gel electrophoresis from those found in the normal bovine erythrocytes. The enzyme 6-phosphogluconate dehydrogenase was not detected as a parasite-specific enzyme in B. bigemina-infected erythrocytes. 相似文献
110.