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41.
D. Lauzer G. Laublin G. Vincent M. Cappadocia 《Plant Cell, Tissue and Organ Culture》1992,28(2):215-223
Two wild yams of West Africa, Dioscorea abyssinica Hoch, and D. mangenotiana Miège were micropropagated from nodal cultures. Both species produced 4–5 nodes per each node cultured. The size of nodal cuttings was critical, segments shorter than 0.5 cm being less suitable for micropropagation. The number of nodes produced was constant even after 5 cycles of subculture; however, D. abyssinica continuous subculture decreased propagation efficiency, resulting in a reduced number of reculturable nodes at each cycle. In D. mangenotiana, the decrease in multiplication efficiency affected both the number of total and reculturable nodes. Large-sized microtubers were induced on nodal segments maintained under 8-h daylength in both species. In D. abyssinica, however, microtubers were induced on media containing 20, 40, 60 and 80 g l-1 sucrose, whereas in D. mangenotiana only 40 and 60 g l-1 sucrose favoured tuberization. Cytological studies confirmed that the chromosome number of D. abyssinica was 2n=40, although a high incidence of cytochimerism and cells with 2n=38 were observed in root meristems. In D. mangenotiana clones, the chromosome number was 2n=40, as against 2n=72 and 2n=80 reported in literature. This species also displayed karyological stability.Abbreviations BA
benzyladenine
- NAA
naphthaleneacetic acid
- PPF
photosynthetic photon flux 相似文献
42.
Plasticity of the tobacco genome was studied by testing the DNAs of protoplast-derived regenerants with three different repetitive
DNA sequences by the method of quantitative DNA/DNA hybridizations. A large population of 91 regenerants belonging to 35 different
protoclones was analysed and a high degree of heterogeneity in the contents of the different DNA repeats was detected. The
contents of middle repetitive sequences of two types were more stable or changed in the same direction, while the highly repetitive
sequence varied independently and displayed a significant reduction in comparison with the two other sequences. Comparing
the variation within the subpopulations of plants of the same clonal origin and the variation among the protoclones led to
a conclusion that the pre-existing DNA variability in the starting plant material and/or thein vitro stress during the very early stages of protoclone regeneration played a decisive role in the formation of modified genomes
in regenerants. 相似文献
43.
The intensity of light scattered at 90° to the incident beam and the effective hydrodynamic radii of mitochondria incubated under a variety of conditions have been measured. Addition of high concentrations of uncouplers to respiring mitochondria resulted in a decrease in scatter which was not due to swelling. Addition of valinomycin to mitochondria depleted of substrate in K+-free medium produced an increase in scatter that was not due to shrinking. It is concluded that changes in the intensity of scattered light are not reliable indices of changes of volume of mitochondria, and that changes in conformation with changes in metabolic state dominate changes in light scatter. A molecular mechanism for the effect of metabolic state upon the scattered intensity is suggested. 相似文献
44.
Two basic cell types occur in the hemolymph of Bulinus truncatus rohlfsi: granulocytes and hyalinocytes. Granulocytes are divided into three subtypes: (1) Granulocytes I, which account for 19% of the hemocytes, are small, young amoebocytes with 1–20 filopodia and small numbers of cytoplasmic granules, including some lysosomes; (2) granulocytes II, which account for 78% of the cells, are large, fully developed amoebocytes that possess 1–20 filopodia and many granules, both acidophilic and basophilic, including numerous lysosomes, phagosomes, and mitochondria; and (3) spent granulocytes, which are rare, have few filopodia, large accumulations of glycogen granules and prominent vacuoles in addition to lysosomes in the cytoplasm. These three subtypes of granulocytes probably represent ontogenetic stages within a single cell line. In addition, granulocytes with 40 or more filopodia and little ectoplasm, found in only 1 of 45 snails examined, probably reflect a pathologic condition. Hyalinocytes, which account for 3% of all hemocytes, are similar in size to mature granulocytes, but have few or no cytoplasmic granules and lack filopodia and glycogen granules. Total hemocyte concentration in hemolymph is 328,000 ± 188,000 cells/ml. 相似文献
45.
46.
Ultraviolet light-induced unscheduled DNA synthesis in primary cultures of human placentae examined as a function of radiation-dose and repair-incubation period was found to be dependent upon cell type and independent of gestational age. Primary cultures obtained by continuous harvesting of enzymatically released cells from fragments of 11-week and term specimens contained cytotrophoblasts and fibroblasts. Fibroblasts exhibited 3-fold more repair than did cytotrophoblasts from the same organ at both 11 weeks and term. 相似文献
47.
Crude trichophytin was fractionated to find out if its lipid fraction could cause inflammatory delayed allergic skin reactions in dermatophyte-sensitized guinea pigs. The following fractions were obtained: polysaccharide-peptide, total lipids, total lipids without free fatty acids and free fatty acids. The crude trichophytin and polysaccharide-peptide fraction gave rise to strong and equal allergic delayed skin reactions after 24 h. The total lipids gave statistically significant weaker, but clearly positive reactions, and of the same degree as the free fatty acid fraction. The total lipids without free fatty acids did not produce reactions in the sensitized animals, indicating that free fatty acids are responsible for the allergic skin reactions. In some cases the free fatty acids showed comparatively intense reactions. It can be concluded that free fatty acids are antigenic substances that are, sometimes, involved in the allergic delayed skin reactions in dermatophytosis. 相似文献
48.
D Vincent A Notter J Magron C Cellier-Chapuis 《Comptes rendus des séances de la Société de biologie et de ses filiales》1976,170(6):1227-1231
Study on 41 cases. The cholinesterasic activity of human amniotic fluid, free from blood, is very weak, in average 0,10 microkatal, approximatively 300 times weaker than mother's serum. In this "total cholinesterase", we find a large amount (about 40%) of acetylcholinesterase. Amniotic cholinesterases have an prominent placentary origin, with, in addition, a likely activity proceeding from cellular elements. 相似文献
49.
50.