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Reynolds TL  Kitto SL 《Plant physiology》1992,100(4):1744-1750
Uninucleate microspores in anther cultures of bread wheat (Triticum aestivum cv Pavon) are capable of producing haploid pollen embryoids and plants. To gain an understanding of this alternate pathway of pollen development, we constructed a cDNA library to young pollen embryoids, isolated embryoid-specific genes, and analyzed their expression patterns during morphogenesis. Two embryoid-abundant clones, pEMB4 and 94, were expressed very early during culture, suggesting that these genes are associated with development and are not simply expressed as a consequence of differentiation. The accumulation patterns of five cloned mRNAs may indicate the activation of specific genes associated with the major morphological and physiological activities connected with the differentiation of embryoids in vitro. These results suggest that embryoid-abundant gene expression is causally related to this pathway because gene expression is spatially and temporally specific and is not observed when microspores are cultured under noninductive conditions.  相似文献   

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The involvement of macrophages (Mφs) as host, accessory, and effector cells in the development of infectious diseases, together with their central role in iron homeostasis, place these immune cells as key players in the interface between iron and infection. Having previously shown that the functional expression of NRAMP-1 results in increased protein phosphorylation mediated in part by an iron-dependent inhibition of Mφ protein-tyrosine phosphatase (PTP) activity, we sought to study the mechanism(s) underlying this specific event. Herein we have identified the mononuclear dicitrate iron complex [Fe(cit)2H4-x](1+x)− as the species responsible for the specific inhibition of Mφ PTP activity. By using biochemical and computational approaches, we show that [Fe(cit)2]5− targets the catalytic pocket of the PTP SHP-1, competitively inhibiting its interaction with an incoming phosphosubstrate. In vitro and in vivo inhibition of PTP activity by iron-citrate results in protein hyperphosphorylation and enhanced MAPK signaling in response to LPS stimulation. We propose that iron-citrate-mediated PTP inhibition represents a novel and biologically relevant regulatory mechanism of signal transduction.  相似文献   

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Staswick PE 《Plant physiology》1989,90(4):1252-1255
A temporary vegetative storage protein, composed of similar 25 kilodalton and 27 kilodalton subunits, was found to be abundant in soybean (Glycine max (L.) Herr. var Hobbit) leaves, stems, pods, flower petals, germinated cotyledons, and less abundant in roots, nodules and seeds. Total pod protein was highest at 3 weeks after flowering and declined by 37% within 3 weeks during seed development. During this time the vegetative storage protein declined from 18% to 1.5% of the total pod protein and accounted for 45% of the protein lost from pods. This indicates that the vegetative storage protein makes a significant contribution to the pool of nutrients mobilized from pods for transport to developing seeds.  相似文献   

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We have investigated the regulation and localization of mitogen-activated protein kinase (MAPK) and mitogen-activated protein kinase kinase (MAPKK) in both cytosolic and nuclear fractions of glomerular mesangial cells. p42 MAPK was localized by both immunoblot and kinase activity in both cytosol and nucleus and was rapidly activated, in both fractions, by fetal bovine serum and TPA. Downregulation of protein kinase C (PKC) by TPA inhibited stimulation of cytosolic p42 MAPK, but unexpectedly had no effect on stimulated p42 MAPK in the nucleus. Next we studied the upstream kinase p45 MAPKK by indirect immunofluorescence microscopy, Western blot analysis, and kinase specific activity. Unlike MAPK, p45 MAPKK is almost exclusively cytosolic in resting cells and kinase activity stimulated by TPA is restricted to the cytosol. Interestingly, PKC downregulation for 24 h with TPA dramatically enhanced nuclear MAPKK as assessed by all three techniques. Cytosolic stimulated MAPKK was attenuated in PKC downregulation. Collectively these results show that in mesangial cells: (i) p42 MAPK and p45 MAPKK localize in both the cytosol and the nucleus, and (ii) PKC exerts a negative effect on nuclear MAPKK activity as documented by PKC downregulation, which augments p45 MAPKK nuclear mass and activity. These results indicate that the dual regulation of these two kinases is under differential control in the cytosol and the nucleus.  相似文献   

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Human calmodulin-like protein (CLP) is a calcium-binding protein down-regulated in a cell culture model of mammary tumorigenesis as well as in a majority of breast cancers in vivo. CLP down-regulation may be a result of the poorly differentiated state of these cell lines and tumors, or CLP expression may be incompatible with the uncontrolled cell growth associated with tumorigenesis. To learn more about CLP expression and regulation, we determined the distribution of CLP in various human tissues by immunohistochemistry. CLP was expressed exclusively in the epithelium of the tissues surveyed and was most abundant in thyroid, breast, prostate, kidney, and skin. CLP expression appears to increase in stratified epithelium during differentiation, as illustrated in the skin where CLP staining intensified from the basal through the spinous to the granular layers. Using a normal human keratinocyte culture model, we examined CLP expression in response to various agents known to affect keratinocyte differentiation. Agents that inhibit (epidermal growth factor, EGF) or permit (keratinocyte growth factor) terminal differentiation correspondingly regulate CLP expression. Factors modulating the EGF receptor signaling pathway were particularly potent in regulating CLP expression. CLP expression correlated with an agent's ability to promote terminal differentiation regardless of the agent's effect on keratinocyte proliferation. These studies show that CLP expression is coordinately regulated by, and may be involved in, the program of terminal differentiation in human keratinocytes and, likely, other differentiating epithelial cell types.  相似文献   

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Chang YC  Walling LL 《Plant physiology》1991,97(3):1260-1264
The levels of abscisic acid (ABA) during embryogenesis in the soybean (Glycine max) cultivar Dare were quantitated. An increase in the quantity of ABA per cotyledon was correlated with a decrease in the chlorophyll a/b binding (Cab) protein gene mRNA population. Soybean cotyledons were cultured in vitro in the presence or absence of ABA. Quantitation of cotyledonary ABA levels and Cab mRNA levels indicated that the application of 5 × 10−5 molar and 5 × 10−6 molar exogenous ABA decreased Cab mRNA prevalences. S1 nuclease protection experiments demonstrated that exogenous ABA modulated the level of Cab3 mRNA. These data strongly suggest that one of the developmental regulators of Cab gene expression during soybean embryogeny is the plant hormone, ABA; ABA negatively regulates Cab mRNA accumulation.  相似文献   

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2,4_D对甘薯体细胞胚胎发生的调控   总被引:7,自引:0,他引:7  
将来源于‘徐薯18’叶片的胚性愈伤组织,接种在含有不同2,4D浓度的液体MS培养基中进行悬浮培养,悬浮细胞表现出不同的形态结构、分裂方式和发育途径:2,4D浓度为1mg/L时,细胞均等分裂,增殖迅速;不含2,4D时,细胞多进行不均等分裂,并发育成体细胞胚。不同2,4D浓度中培养的悬浮细胞,其胞外过氧化物同工酶谱及其随时间变化的方式有很大差异,并与细胞的生长、发育过程密切相关  相似文献   

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Rhizobium fredii USDA257 forms nitrogen-fixing nodules on soybean cultivar Peking, but not on cultivar McCall. This pattern of nodulation persists when McCall and Peking seedlings are cultivated together in plastic growth pouches. Reciprocal grafting experiments confirm that the root genotype, and not that of the shoot, regulates such cultivar specificity. When Peking roots are grafted onto McCall seedlings, the nodulation responses of roots similarly remain unaffected. Transposon-mutant 257DH4, which is derived from USDA257, can form nitrogen-fixing nodules on McCall. Such nodulation is blocked by the presence of USDA257 in the inoculum. Grafting experiments indicate that blocking is not due to a translocatable inhibitor produced by McCall roots or triggered by their interaction with USDA257. Thus, neither freely diffusible nor graft-transmissible substances are involved in cultivar-specific interactions of soybean with R. fredii and its derivatives.  相似文献   

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This review is concerned with the structure and function of the protein products and homeobox genes of the HOX complex. We also trace a relationship between morphological evolution and the evolution of the homoeotic complex.  相似文献   

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Protein synthesis was studied during precocious and natural soybean seed (Glycine max [L.] Merr.) maturation. Developing seeds harvested 35 days after flowering were precociously matured through controlled dehydration. Total soluble proteins and proteins labeled with [35S]methionine were extracted from control, developing seeds and from precociously and naturally matured seeds and were analyzed by one-dimensional PAGE and fluorography. The results demonstrated that several polypeptides which were designated “mature polypeptides,” were synthesized de novo during precocious and natural seed maturation. Two of these polypeptides, 31 and 128 kilodalton in mass, also stained intensely with Coomassie blue, suggesting their abundant accumulation during seed maturation. Results from in vitro translation experiments showed that the mRNAs corresponding to these “maturation polypeptides” accumulated during precocious maturation and in naturally matured seeds, but not in seeds freshly harvested 35 days after flowering (control). The role of the “maturation polypeptides” is currently unknown; however, their presence and that of their corresponding mRNAs was coincident with the ability of matured seeds to establish seedling growth. This study has demonstrated that precocious seed maturation treatments may be extremely useful for investigations of metabolic events and molecular control mechanisms affecting soybean seed maturation.  相似文献   

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Doklady Biochemistry and Biophysics - The expression profiles of the PAP genes, encoding proteins associated with plastid multisubunit RNA polymerase, were studied in dry seeds, during germination,...  相似文献   

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Regulation of Soybean Embryogenesis by Abscisic Acid   总被引:7,自引:0,他引:7  
Abscisic Acid (ABA) stimulates growth and protein accumulationin soybean (Glycine max. L. Merr.) embryos during the earlyphases of embryogenesis. Growth of mid-stage embryos is suppressedby ABA, but protein accumulation is not impaired. Metabolitedistribution studies indicate that ABA alters partitioning ofsucrose in older embryos such that protein accumulation is sustainedat the expense of lipid accumulation. The responses of in vitrocultured embryos to ABA is consistent with the normal patternof ABA accumulation and disappearance that occurs during embryogenesisin situ. A close correlation exists between ABA levels and embryogrowth rates in situ in three cultivars of soybeans. Dependingon the age or stage of the developing embryo, ABA either servesto promote or inhibit embryo growth. Key words: Embryogenesis, ABA, Seeds, Soybean.  相似文献   

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