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51.
MASAKAZU HARA YURI SHINODA YASUTAKA TANAKA & TORU KUBOI 《Plant, cell & environment》2009,32(5):532-541
Dehydrins are hydrophilic proteins that accumulate during embryogenesis and osmotic stress responses in plants. Here, we report an interaction between citrus dehydrin Citrus unshiu cold-regulated 15 kDa protein (CuCOR15) and DNA. Binding of CuCOR15 to DNA was detected by an electrophoretic mobility shift assay, a filter-binding assay and Southwestern blotting. The binding was stimulated by physiological concentrations of Zn2+ , but little stimulation occurred when other divalent cations, such as Mg2+ , Ca2+ , Mn2+ , Ni2+ and Cu2+ , were substituted for Zn2+ . Ethylenediaminetetraacetic acid cancelled the Zn2+ -stimulated binding. A binding curve and competitor experiments suggested that the DNA binding of CuCOR15 exhibited low affinity and non-specificity. Moreover, tRNA competed with the DNA binding. Histidine-rich domains and a polylysine segment-containing domain participated in the DNA binding. These results suggest that CuCOR15 can interact with DNA, and also RNA, in the presence of Zn2+ . Dehydrin may protect nucleic acids in plant cells during seed maturation and stress responses. 相似文献
52.
NAGAO MASAYUKI; ESASHI YOJI; TANAKA TERUKO; KUMAGAI TAKAYOSHI; FUKUMOTO SHITSUE 《Plant & cell physiology》1959,1(1):39-47
- Seed germination of Begonia Evansiana ANDR. was investigatedat 29?C.
- The germination was induced under long-day conditions,the criticaldaylength being about 8 hours. Exposure to at least2 or 3 cyclesof long days was necessary for germination. Theseeds couldgerminate under otherwise non-inductive photoperiods,when thedark period was interrupted with a short period ofillumination.Thus the photoperiodic behaviour of Begonia seedsin germinationis similar to that of typical long-day plantsin flowering.
- The application of gibberellin brought aboutno germinationin complete darkness, but markedly reduced thecritical daylengthfor germination, even 1-minute photoperiodsbeing inductive.The germination under continuous light wasalso favoured bygibberellin application. The action of gibberellinin germinationof Begonia seeds may be to intensify the lightaction or tosubstitute for a part of it.
53.
To elucidate the regulatory mechanism for tyrosinase gene expression in vivo, we microinjected a mouse tyrosinase minigene, mg-Qrs-J, into the fertilized eggs of BALB/c albino mice. As a result, we obtained six pigmented founder mice that exhibited non-standard coat color variations as well as the wild-type phenotype. These founder mice were subsequently crossed with BALB/c albino mice to establish the transgenic lines. As a consequence, two primary lines and five sublines have been obtained from four of the six founder mice. We found that not only uniformly pigmented phenotypes but also patterned phenotypes were inherited by their descendants. The possible underlying mechanism of the patterned phenotypes is discussed. 相似文献
54.
JEFFREY A. HARVEY T. M. BEZEMER RIETA GOLS YUTAKA NAKAMATSU TOSHIHARU TANAKA 《Physiological Entomology》2008,33(3):217-225
Abstract The larvae of most endoparasitoid wasps consume virtually all host tissues before pupation. However, in some clades, the parasitoid larvae primarily consume haemolymph and fat body and emerge through the side of the host, which remains alive and active for up to several days. The evolutionary significance of this host‐usage strategy has attracted attention in recent years. Recent empirical studies suggest that the surviving larva guards the parasitoid broods against natural enemies such as predators and hyperparasitoids. Known as the ‘usurpation hypothesis’, the surviving larvae bite, regurgitate fluids from the gut, and thrash the head capsule when disturbed. In the present study, the ‘usurpation hypothesis’ is tested in the association involving Manduca sexta, its parasitoid Cotesia congregata, and a secondary hyperparasitoid Lysibia nana. Percentage parasitoid survival is higher and hyperparasitism lower when cocoons of C. congregata are attached to the dorsum of M. sexta caterpillars. Fat body contents in several associations involving solitary and gregarious parasitoids feeding on haemolymph and fat body are also compared. The amount of fat body retained in parasitized caterpillars varies considerably from one association to another. In M. sexta and Pieris brassicae, considerable amounts of fat body remain after parasitoid emergence whereas, in Cotesia kariyai and Cotesia rufricus, virtually all of the fat body is consumed by the parsasitoid larvae. The length of post‐egression survival of parasitized caterpillars differs considerably in several tested associations. In Pseudeletia separata, most larvae die within a few hours of parasitoid emergence whereas, in M. sexta, parasitized larvae live up to 2 weeks after parasitoid emergence. Larvae in other associations parasitized by gregarious and solitary endoparasitoids live for intermediate periods. The results are discussed in relation to the adaptive significance of different feeding strategies of immature parasitoids and of the costs and benefits of retaining the parasitized caterpillar in close proximity with the parasitoid cocoons. 相似文献
55.
Several cell types migrated cut from small pieces of newt testes cultivated in vitro. Flat fibroblastic cells migrated out within a few days. Then, secondary spermatogonia, identified by the presence of germ cell-specific substances and by the shape and appearance of their nucleus and subcellular organelles, migrated out over the sheet of fibroblastic cells. Sertoli cells co-migrated with secondary spermatogonia, maintaining a similar cellular arrangement to that of testicular cells in vivo. Mitosis of secondary spermatogonia both in clusters and as single cells was frequent from the third day until about 2 weeks after inoculation. During mitosis, active and periodic rotation of chromosomes was observed. Identification of the cell types and studies on their behavior were performed by electron microscopy and phase contrast microscopy. 相似文献
56.
Fractal Analysis of Plant Root Systems 总被引:13,自引:1,他引:12
The morphology of root systems of crop plants was analysed byfractal geometry using an image processing system. Results indicatethat these root systems have a fractal structure (D; 1.48 相似文献
57.
The -amylase induced by helminthosporol and gibberellic acidin the embryo-less endosperm of barley was separated into thethree fractions, 1, 2 and 3, by DEAE-cellulose column chromatography.A maximum amount of the 2. was induced by gibberellic acid andthat of the as by helminthosporol. After rechromatography, the2 induced by gibberellic acid and the as induced by helminthosporolshowed their respective single bands in an electrophoresis agargel zymogram. On the other hand, the ai induced by helminthosporoland gibberellic acid showed three bands. Dihydrohelminthosporic acid, a derivative of helminthosporol,induced the same isozymes as helminthosporol did. (Received May 8, 1967; ) 相似文献
58.
WATANABE KAZUHIKO; TANAKA KUNISUKE; ASADA KOZI; KASAI ZENZABURO 《Plant & cell physiology》1971,12(1):161-164
The effects of phytic acid, myo-inositol hexaphosphoric acid,in the induction and growth of rice seed callus were studied.Phytic acid was substituted for myo-inositol in the inductionof the callus and preferable effects were shown on the growthof the callus.
1Present address: Hyogo Agricultural Experiment Station, Akashi,Hyogo, Japan (Received June 30, 1970; ) 相似文献
59.
The DEAE-cellulose column chromatography has shown two differentforms of starch synthetase, which are referred to as fractionsI and II in extracts of rice seeds (non-waxy and waxy varieties)harvested at the milky stage. Similarly treated leaf extractsof rice (non-waxy) and maize (non-waxy) also demonstrate dieexistence of two major isozyme fractions. In all enzyme preparationstested, ADP-glucose was the sole glucosyl donor and UDP-glucosewas totally inactive. Rechromatography, on a DEAE-cellulosecolumn, of two enzyme fractions (I and II) separated from non-waxyrice seed extracts did not alter their elution patterns. Someof their enzymic properties were compared, in particular, theirglucosyl-acceptor (primer) specificities. Regardless of potentamylase activities in the two fractions, notable differenceswere observed in that fraction I utilized the long-chain oligosaccharides[maltododecaose] and various types of high molecular -glucansmore readily than fraction II. However, short-chain oligosaccharides[maltose, maltotriose and maltotetraose] were utilized morereadily by fraction II than by fraction I. A possible role forthe two starch synthetase isozymes in starch synthesis in plantcells is discussed. (Received January 5, 1971; ) 相似文献
60.
JIRO KIKKAWA 《Austral ecology》1977,2(2):121-136
Two controversial areas of ecology are examined critically to ascertain the limits of some current theories. In the field of population ecology it is argued that no general theory can explain the regulation of animal numbers. Existing theories are considered inadequate because either (1) evidence points to multiple causes rather than a single cause, (2) propositions lose scientific appeal by accumulating qualifiers, or (3) conflicting theories are irrefutable in scientific inquiry. Different research strategies are required to discover generalities in population regulation. In the field of community organization it is pointed out that too much emphasis on the competitive exclusion principle has blinded ecologists from the clustering of resources and of species populations. Conditions of co-existence as well as segregation are considered important in the organization of communities, which allow elements of chance in small scale distribution. The ecological world is likened to the physical world in which small scale disorder leads to order on a large scale. For the development of a global ecology the acceleration of studies in the tropics and the southern hemisphere is urged. 相似文献