共查询到20条相似文献,搜索用时 271 毫秒
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ChangesofConAReceptorSitesonMammalianSpermsduringCapacitationandAcrosomeReactionDUANChong-wen(段崇文),CHENDa-yuan(陈大元)(StateKeyL... 相似文献
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TWONEWSPECIESFROMTRICHOSANTHES(CUCURBITACEAE)YuehChun-hsiHuangLu-qiChengChing-yung〔ABTRACT〕TrichosanthesreferactaYuehetL.Q.H... 相似文献
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ExistenceandFunctionsofNeurotensinHumanEarlyPlacentalVilliZHANGChong-li(张崇理);CHENGLi-ren(程丽仁),SHENWei-bin(沈卫斌);YINHong(殷红);HU... 相似文献
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植物体细胞胚发生的分子基础① 总被引:17,自引:1,他引:16
MolecularFoundationinPlantSomaticEmbryogenesisXINGGeng-ShengCUIKai-RongSHANLunWANGYa-Fu(TheStateKeyLaboratoryofAridAgroecolog... 相似文献
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达乌尔黄鼠染色体银染核仁组织者分析 总被引:2,自引:1,他引:1
达乌尔黄鼠染色体银染核仁组织者分析ANALYSISONCHROMOSOMESAg-NORSOFCITELLUSDAURICUSKeywordsCilellusdauricus;Chromosome;Ag-NOR达乌尔黄鼠(cilellusdauric... 相似文献
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X. C. ZHANG 《植物研究》1998,18(1):107-117
GENUSANTROPHYUMKAULF.FROMCHINAANDNEIGHBORINGREGIONSX.C.ZHANG(Theherbarium(PE),InstituteofBotany,ChineseAcademyofSciences,Bei... 相似文献
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Compared to seeds, somatic embryos accumulated relatively low levels and different types of storage carbohydrates. The regulation of starch accumulation was studied to determine its effects on desiccation tolerance and vigor of dry somatic embryos. Somatic embryos of Medicago sativa are routinely matured through three phases: 7 days of development; 10 days of phase I maturation, a rapid growth phase; and 10 days of phase II maturation, a phase leading to the acquisition of desiccation tolerance. The control of starch deposition was investigated in alfalfa somatic embryos by manipulating the composition of the phase I maturation medium with different levels of sucrose, abscisic acid, glutamine and different types of carbohydrates and amino acids. After phase II maturation, mature somatic embryos were collected for desiccation and subsequent conversion, or for biochemical analyses. Starch deposition occurred primarily during phase I maturation, and variations in the composition of this medium influenced embryo quality, storage protein and starch accumulation. A factorial experiment with two levels of glutamine × three levels of sucrose showed that increasing the sucrose concentration from 30 to 80 g/l increased embryo size and starch content, but had minimal effect on accumulation of storage proteins; glutamine also increased embryo size, but decreased starch content and increased accumulation of the high salt soluble S-2 (medicagin) storage proteins. ABA did not influence any of the parameters tested when included in phase I maturation at concentration up to 10 μM. Replicating sucrose with maltose, glucose, or glucose and fructose did not alter embryo size or starch accumulation (mg/g fresh weight), but replacement with fructose alone reduced embryo size, and replacement with glucose alone reduced germination. Suplementation with the amino acids, asparagine, aspartic acid and glutamine increased seedling vigor, but decreased the starch content of embryos. The data indicate that starch accumulation in somatic embryos is regulated by the relative availability of carbon versus nitrogen nutrients in the maturation medium. The quality of mature somatic embryos, determined by the rate of seedling development (conversion and vigor), correlated with embryo size, storage protein and free amino acid but not with starch. Therefore, further improvements in the quality of somatic embryo may be achieved through manipulation of the maturation medium in order to increase storage protein, but not starch deposition. 相似文献
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Manoj K. Rai N. S. Shekhawat Harish Amit K. Gupta M. Phulwaria Kheta Ram U. Jaiswal 《Plant Cell, Tissue and Organ Culture》2011,106(2):179-190
Abscisic acid (ABA) plays a significant role in the regulation of many physiological processes of plants. It is often used
in tissue culture systems to promote somatic embryogenesis and enhance somatic embryo quality by increasing desiccation tolerance
and preventing precocious germination. ABA is also employed to induce somatic embryos to enter a quiescent state in plant
tissue culture systems and during synthetic seed research. Application of exogenous ABA improves in vitro conservation and
the adaptive response of plant cell and tissues to various environmental stresses. ABA can act as anti-transpirant during
the acclimatization of tissue culture-raised plantlets and reduces relative water loss of leaves during the ex vitro transfer
of plantlets even when non-functional stomata are present. This review focuses on the possible roles of ABA in plant tissue
culture and recent developments in this area. 相似文献
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Françoise Cailloux Josiane Julien-Guerrier Laurent Linossier Alain Coudret 《Plant science》1996,120(2):2028-196
A high frequency of secondary embryogenesis was induced from isolated early cotyledonary-stage somatic embryos of Hevea brasiliensis. A long-term embryogenic line was established by the use of recurrent embryogenesis and maintained for 3 years on hormone-free medium by the transfer of selected proembryogenic masses every 10 days.
The addition of 234 mM sucrose as stress with sucrose and 10−5 M abscisic acid (ABA) to the culture medium enhanced the maturation of somatic embryos. Under these culture conditions, the embryo population was composed of 45% globular, 18% oblong and 37% torpedo-stage embryos. These somatic embryos had well-formed tissue structure, a well-defined epidermis, protein storage bodies, and a high accumulation of starch. The triglyceride content was five times as high in the torpedo-stage embryos that developed on medium supplemented with 234 mM sucrose and 10−5 M ABA as in embryos obtained on basal medium with 58 mM sucrose. 相似文献
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L. Alemanno M. Berthouly N. Michaux-Ferriere 《In vitro cellular & developmental biology. Plant》1997,33(3):163-172
Summary In order to improve the late phases of Theobroma cacao L. embryogenesis from tissues of maternal origin, zygotic embryogenesis and somatic embryogenesis were compared, with respect
to morphological, histological, and physiological parameters. Zygotic embryogenesis could be divided into three steps: (a)
embryogenesis sensu stricto, (b) a growth period in which cotyledonary embryos reached their final dimensions, and (c) a maturation period in which embryos
accumulated protein and starch reserves, dehydrated to a water content equal to 30%, and underwent a modification in soluble
sugar composition. Monosaccharides and sucrose contents decreased to the benefit of the oligosaccharides raffinose and stachyose.
The formation of somatic embryos by use of basic protocols was studied to define the limiting factors that could lie behind
their poor development. Morphological abnormalities of somatic embryos, which represented 80% of the total population, were
described. A histological study showed that somatic embryos lacked starch and protein reserves; moreover, their water content
was much higher than that of their zygotic counterparts. Introducing a growth period into the culture protocol made for better
embryo development. Adding sucrose and abscisic acid to the maturation medium was effective in increasing reserve synthesis
and resulted in higher germination, conversion, and acclimatization rates. 相似文献
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C. Cabasson D. Alvard D. Dambier P. Ollitrault C. Teisson 《Plant Cell, Tissue and Organ Culture》1997,50(1):33-37
Liquid medium improves and facilitates somatic embryo development from Citrus deliciosa Ten. suspension cultures. Three different
culture conditions were compared to determine a means of overcoming poor somatic embryo development. Somatic embryos derived
from suspension cultures were plated on solid medium, maintained in suspension culture or temporarily immersed. About 60%
of somatic embryos plated on solid medium developed to the cotyledonary stage, but were hyperhydric. Continuous growth in
suspension culture at 100 rpm hindered cotyledon and protoderm formation, and somatic embryos were unable to develop beyond
the globular stage. Temporary immersion promoted somatic embryo development, i.e. 66% of the somatic embryos produced were
cotyledonary, and were morphologically similar to nucellar embryos. This latter culture system also improved regeneration
synchronization by hampering secondary embryogenesis at the onset of germination. Irrespective of the culture system used,
most cotyledonary somatic embryos studied had no caulinary meristem or starch and protein reserves, thus explaining the low
germination rates obtained.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Anatomical Sequence and Morphometric Analysis during Somatic Embryogenesis on Cultured Cotyledon Explants of Camellia japonica L. 总被引:1,自引:0,他引:1
This article describes the origin and anatomical developmentof somatic embryos differentiated on Camellia japonica L. cotyledonscultured on Murashige and Skoog's medium containing 1 mg l-1of 6-benzylaminopurine. Only the abaxial surface of the cotyledonexplants was morphogenetically competent. Embryos developedin abaxial parenchymatic protuberances or nodules arising bydedifferentiation and active cell division in the epidermisand subepidermis. After 12-15 d in culture, successive divisionsat the surface of the nodules led to the formation of embryogenicprecursor cells which dedifferentiated into embryogenic cells;most somatic embryos apparently had a multicellular origin frommulticellular proembryonal complexes, though a number of few-celledproembryos within a thick common wall seemed to have originatedunicellularly. Between days 24 and 27, somatic embryos at theheart-shaped, torpedo-shaped and cotyledonary stages were apparent.Computer-aided image analysis of the histological events showeda progressive increase in the nucleus-to-cell area ratio. Duringthe first 7 d culture the explants exhibited a rapid declinein protein body content, which was high in the initial cotyledon,and an increase in starch content. Developing nodules stronglyPAS-positive, but starch content subsequently declined in thetissues underlaying embryogenic areas and reached a minimumwhen somatic embryos developed.Copyright 1993, 1999 AcademicPress Camellia japonica, camellia, cellular changes, somatic embryogenesis, histology, image analysis 相似文献
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Developmental potential of cumulus cell-derived culture frozen in a quiescent state after nucleus transfer 总被引:1,自引:0,他引:1
An efficient method for freezing donor cells is necessary when using nucleus transfer of somatic cells for large-scale cloning. In the present study, we developed a method for freezing and thawing bovine cumulus cell-derived cultured cells to be used as nucleus donors. Cumulus cells were obtained from ovaries of living and slaughtered bovine and cultured in vitro. Cumulus cell-derived cultured cells were serum-starved for several days to induce a quiescent state and then frozen at -70 degrees C for at least 2 d. Immediately thereafter or 2 h after thawing, the cells were used as donor cells for nuclear transfer without additional in vitro culture. The fusion rate with recipient cytoplasts was not affected by the cumulus cell source (slaughtered or living) or time after thawing (0 and 2 h). The cleavage rate of frozen-thawed cumulus cell-derived cultured cells from slaughtered cows immediately after thawing (0 h) was highest (97%) and was significantly higher than that of controls (85%) or cells transferred 2 h after thawing (85%). There were no significant differences among any of the groups in the potential of the nuclear transfer embryos to develop into blastocysts (34 vs 44 and 44%, 39 vs 45 and 46%). Thus, storage of bovine cumulus cell-derived cultured cells in the quiescent state at -70 degrees C is effective and might be useful and convenient for large-scale cloning. The maximum storage periods and developmental potential of embryos after such nucleus transfers requires further examination. 相似文献
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Background and Aims
Secondary somatic embryogenesis has been postulated to occur during induction of peach palm somatic embryogenesis. In the present study this morphogenetic pathway is described and a protocol for the establishment of cycling cultures using a temporary immersion system (TIS) is presented.Methods
Zygotic embryos were used as explants, and induction of somatic embryogenesis and plantlet growth were compared in TIS and solid culture medium. Light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to describe in vitro morphogenesis and accompany morpho-histological alterations during culture.Key Results
The development of secondary somatic embryos occurs early during the induction of primary somatic embryos. Secondary somatic embryos were observed to develop continually in culture, resulting in non-synchronized development of these somatic embryos. Using these somatic embryos as explants allowed development of cycling cultures. Somatic embryos had high embryogenic potential (65·8 ± 3·0 to 86·2 ± 5·0 %) over the period tested. The use of a TIS greatly improved the number of somatic embryos obtained, as well as subsequent plantlet growth. Histological analyses showed that starch accumulation precedes the development of somatic embryos, and that these cells presented high nucleus/cytoplasm ratios and high mitotic indices, as evidenced by DAPI staining. Morphological and SEM observations revealed clusters of somatic embryos on one part of the explants, while other parts grew further, resulting in callus tissue. A multicellular origin of the secondary somatic embryos is hypothesized. Cells in the vicinity of callus accumulated large amounts of phenolic substances in their vacuoles. TEM revealed that these cells are metabolically very active, with the presence of numerous mitochondria and Golgi apparatuses. Light microscopy and TEM of the embryogenic sector revealed cells with numerous amyloplasts, large nuclei and nucleoli, and numerous plasmodesmata. Plantlets were obtained and after 3 months in culture their growth was significantly better in TIS than on solid culture medium. However, during acclimatization the survival rate of TIS-grown plantlets was lower.Conclusions
The present study confirms the occurrence of secondary somatic embryos in peach palm and describes a feasible protocol for regeneration of peach palm in vitro. Further optimizations include the use of explants obtained from adult palms and improvement of somatic embryo conversion rates. 相似文献20.
Somatic embryogenesis in Hevea is stimulated when the embryogenesis induction medium contains maltose, rather than glucose, fructose, or sucrose, in equimolarity (Blanc et al., 1999). Kinetic analyses were carried out on various physiological and biochemical indicators over the 8 weeks that the induction phase then expression of somatic embryogenesis can take. Embryogenesis induction in the presence of glucose, fructose or sucrose revealed strong callus growth in the first 3-4 weeks, associated with a high intra- and extracellular hexose content, a high starch content and a substantial decline in protein synthesis. In the presence of maltose, callus growth was slow and only half that seen with sucrose. This morphogenetic behaviour is associated with a drop in endogenous hexose and starch contents, and an increase in protein synthesis in the first three weeks of culture. The induction of embryogenesis in the presence of maltose was uniform and twice as fast as with sucrose supply. At the end of culture, peroxidase activity, antioxidant and membrane protein contents increased in these calluses; these characteristics may be associated with somatic embryo organization and with the maintenance of effective membrane integrity within a nutrient environment that has become limiting. These new results tally with data in the literature on the roles of sugars, and provide some precise information with regard to the 'carbohydrate deficit' hypothesis usually put forward to explain maltose action. An analysis of these results led to the hypothesis that regulation of endogenous hexose contents at a low level, through slow maltose hydrolysis, was a key element of the biochemical signal leading this callus towards somatic embryogenesis. 相似文献