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51.
马桑菌株的生物学特性 总被引:3,自引:0,他引:3
对从湖北、四川、云南等地采集的尼泊尔马桑(Coriaria nepalensis Wall.)根瘤中分离的20株内生菌纯培养物所进行的研究表明,其形态均具有弗兰克氏菌属的特征。在粗细不一的分枝菌丝体上有泡囊和孢囊,有的还有串珠状结构的菌丝体。不同菌株在液体培养基上生长速度很不一致;菌丝体多呈絮状或颗粒状沉淀,个别还呈薄膜状沉淀;绝大多数菌株的菌丝体具有不同色调的色素;在S培养基中大多数都能产生可溶性色素。上述这些培养特征常因培养基成分和培养方式的不同而有差异。大多数菌株的胞壁组分属Ⅱ型,少数菌株为Ⅲ型;全细胞糖型变化很大,20个菌株可划分为6个糖型,而且绝大多数糖型与已知弗兰克氏菌有所不同。此外,有65%的菌株还具有明显的抗菌活性。 相似文献
52.
We investigated the effect of flowering time, display size, and local floral density on fruit set in Tolumnia variegata, a pollination-limited orchid that offers no reward to its pollinator(s). During 1990, natural variation in flowering time, display size, and fruit set were monitored in 508 plants at one locality in Puerto Rico. The following season, orchid floral abundance per host tree (Randia aculeata) was manipulated to investigate its effect on fruit set. Four floral abundance treatments were established (700, 500, 300, and 100), each replicated four times. Flowering time was the most important trait affecting fruit set. The proportion of plants setting at least one fruit was significantly high early and late in the season, but low during the flowering peak. Thus, strong disruptive selection differential on flowering phenology was found. Display size had little effect on fruit set. A weak, but significant disruptive selection differential on display size was found. Orchid floral abundance per host tree had a significant effect on fruit set. Early in the season, T. variegata flowers with intermediate number of conspecific flowers exhibited a greater probability of setting fruit than those in host trees with fewer or more flowers. Our results show that flowering phenology may be evolutionarily unstable, possibly a consequence of the deception pollination system. Furthermore, a deception strategy would be relatively unsuccessful in populations where plants are found in either very dense or sparse patches. 相似文献
53.
Analysis of the multi-stem clump structure ofLitsea japonica Juss. growing in a coastal dwarf forest
The multi-stem clump structure of a coastal dwarf forest dominated byLitsea japonica Juss. was investigated in order to clarify the sprouting characteristics and self-maintenance of clumps by stem alternation.
The size and age distribution of multi-stem clumps were analyzed using cumulative relative frequency curves.L. japonica had a large number of stems and an even height distribution or young age-biased distribution of stems within a clump. These
results indicated the sequential flushing of sprouts at high frequency. Height distribution within a clump ofL. japonica was relatively even compared to other species. This clump structure suggested the stable self-maintenance of individuals
in all ranges of size and age without disturbances. It originated specific sprouting characteristics as a response to the
severe stress of salty wind.Ardisia sieboldii Miq. had few stems within a clump. Although the stem height distribution of large individuals tended to be even, most clumps
had a large size-biased distribution of stem height which indicated simultaneous sprouting. From this structure, sprouts of
this species were thought to be of less significance in the stable self-maintenance of individuals thanL. Japonica. 相似文献
54.
55.
本文用6个剂量的^60Co-γ射线辐照含有大肠杆菌内毒素的甘露醇、葡萄糖、甲硝唑原料药,并用家兔法和鲎试剂法检验细菌内毒素的活性变化。结果表明,γ辐照能有效地消除原料药中细菌内毒素的生理活性。 相似文献
56.
Guo-Ling Nan Adelheid R. Kuehnle 《In vitro cellular & developmental biology. Plant》1995,31(3):131-136
Summary Five parameters were examined for their effect on transformation ofDendrobium tissues by microprojectile bombardment. The superpromoter in pBI426 produced at least 1.5 times as many transient transformants
as the single cauliflower mosaic virus 35S promoter in pBI121 (37 to 69% vs. 0 to 44%) with dark and frequent GUS (β-glucuronidase) staining. Tissue, genotype, and type of microparticle significantly affected transient GUS activity. Higher
expression was seen in protocormlike bodies and in hybrid UH44 compared to etiolated shoots and protocorms and to hybrids
M61 and K1329-39. Microparticles of 1.6-μm Bio-Rad gold were more effective than 1.0-μm ASI gold. Transient GUS activity did
not differ among protocormlike bodies bombarded using helium propellant pressures of 650, 900, or 1100 psi. Transgenic plants
were recovered fromDendrobium UH800 protocormlike bodies bombarded with pBI426-coated, 1.1-μm tungsten particles using an early-model gunpowder-driven
apparatus with an estimated stable transformation rate of 11.7%. One transgenic plant ofDendrobium UH44 was recovered from etiolated shoot explants bombarded with pBI121-coated, 1.1-μm tungsten particles using the Dupont
PDS-1000 with a stable transformation rate of 0.17%. Positive selection results showed 100 to 200 mg·liter−1 kanamycin to be appropriate for regeneration of transgenic plants from protocormlike bodies, protocorms, and etiolated shoot
explants over a 3- to 9.5-mo. period. 相似文献
57.
Dr. Arthur K. Satterley 《Facies》1994,30(1):119-149
Summary The Upper Triassic Dachsteinkalk of the Hochk?nig Massif, situated 50 km south of Salzburg in the Northern Calcareous Alps,
corresponds to a platform margin reef complex of exceptional thickness. The platform interior limestones form equally thick
sequences of the well known cyclic Lofer facies. Sedimentation in the reef complex was not so strongly controlled by low-amplitude
sea-level oscillations as was the Lofer facies. The westernmost of the 8 facies of the reef complex is an oncolite-dominated
lagoon, in which wave-resistant stromatolite mounds with a relief of a few metres were periodically developed. The transition
to the central reef area is accomplished across the back-reef facies. In the back-reef facies patch reefs and calcisponges
appear. The proportion of coarse bioclastic sediment increases rapidly over a few hundred metres before the central reef area
is encountered. The central reef area consists of relatively widely spaced small patch reefs that did not develop wave-resistant
reef framework structures. The bulk of the sediment in the central reef area is coarse bioclastic material, provided by the
dense growth of reef organisms and the wave-induced disintegration of patch reefs. Collapse of the reef margin is recorded
by the supply of large blocks of patch reef material to the upper reef slope. Additionally, coarse, loose bioclastic debris
was supplied to the upper reef slope and this was incorporated into debris flows on the reef slope and turbidites found at
the base of the slope and in the off-reef facies. Partially lithified packstones and wackestones of the lower to middle reef
slope were modified by mass movement to form breccia and rudstone sheets. The latter reach out hundreds of metres into the
off-reef facies environment. A reef profile is presented which was derived by the restoration of strike and dip information.
In conjunction with constraints imposed by sedimentary facies related to slope processes, the angle of slope in the reef margin
area ranged from 11° to 5°, forming a concave (dished downwards) slope. Water depth estimations require that the central reef
area did not develop in water of less than 10 metres depth. At the reef margin water depths were about 30 metres, at the base
of the reef slope 200 metres and deepening in the off-reef facies to 250 metres. While previous work on reef complexes from
this type of setting suggests growth in a heavily storm-dominated environment, the present author finds little evidence for
the storm generation of the fore reef breccias, although there is good evidence for storm-influenced sedimentation and reworking
in the central reef area.
Post-depositional processes were characterised by continued slope processes causing brecciation and hydraulic injection of
red internal sediments downwards into the reef slope and off-reef limestones. Hydrothermal circulation caused a number of
phases of post-depositional (diagenetic) brecciation. There appears not to have been an important period of emergence at the
Triassic/Jurassic boundary. 相似文献
58.
59.
The nest site characteristics of the freshwater three-spined stickleback, Gasterosteus aculeatus (form leiurus ), were quantitatively investigated in springs and the main stream of the Yamayoke and the Tsuya River system, central Japan. Most nests (93·4%) were on a muddy or sandy substratum, at depths of 10–40 cm (84·3%), in water velocities less than 15 cm s−1 (76·2%) and in the temperature range of 14 to 16° C (82·7%), Spring-fed localities provided more of these conditions than the main stream channel and hence contained more potential nesting areas. Thus, they were utilized by male sticklebacks both temporally (prolonged breeding season) and spatially (more nest sites). 相似文献
60.
In this study we investigated Arabidopsis thaliana (L.) Heynh. inflorescence development by characterizing morphological changes at the shoot apex during the transition to flowering. Sixteen-hour photoperiods were used to synchronously induce flowering in vegetative plants grown for 30 d in non-inductive 8-h photoperiods. During the first inductive cycle, the shoot apical meristem ceased producing leaf primordia and began to produce flower primordia. The differentiation of paraclades (axillary flowering shoots), however, did not occur until after the initiation of multiple flower primordia from the shoot apical meristem. Paraclades were produced by the basipetal activation of buds from the axils of leaf primordia which had been initiated prior to photoperiodic induction. Concurrent with the activation of paraclades was the partial suppression of paraclade-associated leaf primordia, which became bract leaves. The suppression of bract-leaf primordia and the abrupt initiation of flower primordia during the first inductive photoperiod is indicative of a single phase change during the transition to flowering in photoperiodically induced Arabidopsis. Morphogenetic changes characteristic of the transition to flowering in plants grown continuously in 16-h photoperiods were qualitatively equivalent to the changes observed in plants which were photoperiodically induced after 30 d. These results suggest that Arabidopsis has only two phases of development, a vegetative phase and a reproductive phase; and that the production of flower primordia, the differentiation of paraclades from the axils of pre-existing leaf primordia and the elongation of internodes all occur during the reproductive phase. 相似文献