Changes of Template Activity and Proteins of Chromatin during Wheat Germination

Relationships between changes in template activity and composition of chromatin during germination of wheat embyros (Triticum aestivum L.) were investigated. The template activity of chromatin was determined with exogenous DNA-dependent RNA polymerase II (EC 2.7.7.6) prepared from wheat embryos. It was essentially constant for 18 hours of germination, corresponding to 2.5% of that of a native calf thymus DNA. Thereafter, the activity increased 2-fold and 5-fold at 24 and 60 hours of germination, respectively.     

Germination-induced Changes in Chromosomal Proteins of Spring and Winter Wheat Embryos

The template activity of chromatin from winter wheat embryos gradually increased during germination and was regulated with some nonhistone proteins different from the two major ones, molecular weight 39k and 59k polypeptides, previously reported.     

Involvement of Coat Proteins in Bacillus subtilis Spore Germination in High-Salinity Environments

The germination of spore-forming bacteria in high-salinity environments is of applied interest for food microbiology and soil ecology. It has previously been shown that high salt concentrations detrimentally affect Bacillus subtilis spore germination, rendering this process slower and less efficient. The mechanistic details of these salt effects, however, remained obscure. Since initiation of nutrient germination first requires germinant passage through the spores'' protective integuments, the aim of this study was to elucidate the role of the proteinaceous spore coat in germination in high-salinity environments. Spores lacking major layers of the coat due to chemical decoating or mutation germinated much worse in the presence of NaCl than untreated wild-type spores at comparable salinities. However, the absence of the crust, the absence of some individual nonmorphogenetic proteins, and the absence of either CwlJ or SleB had no or little effect on germination in high-salinity environments. Although the germination of spores lacking GerP (which is assumed to facilitate germinant flow through the coat) was generally less efficient than the germination of wild-type spores, the presence of up to 2.4 M NaCl enhanced the germination of these mutant spores. Interestingly, nutrient-independent germination by high pressure was also inhibited by NaCl. Taken together, these results suggest that (i) the coat has a protective function during germination in high-salinity environments; (ii) germination inhibition by NaCl is probably not exerted at the level of cortex hydrolysis, germinant accessibility, or germinant-receptor binding; and (iii) the most likely germination processes to be inhibited by NaCl are ion, Ca²⁺-dipicolinic acid, and water fluxes.     

Observations on Germination and Acetylcholinesterase Activity in Wheat Seeds

In the above article Fig. 1 appeared incorrectly; it shouldhave appeared as below:     

Observations on Germination and Acetylcholinesterase Activity in Wheat Seeds

Wheat seeds treated with organophosphorus insecticides exhibitdelayed germination both in the laboratory and in the field.Since (i) organophosphorus compounds inhibit cholinesteraseenzymes in animals and (ii) acetylcholine and cholinesterasehave been reported to occur in some plants, the hypothesis waspropounded that organophosphorus insecticides inhibit cholinesteraseactivity during cereal seed germination. Using biochemical andphysiological techniques, this hypothesis was tested in thelaboratory on wheat seeds germinated with and without the organophosphorusinsecticide, chlorfenvinphos. Evidence is presented for in vitroactivity of acetylcholinesterase in wheat seedlings and inhibitionof this activity by the insecticide. The possibility is discussedof a link between delayed germination and anti-cholinesteraseactivity of organophosphorus insecticides Wheat seeds, Triticum aestwum L., acetylcholinesterase, electrophoresis, germination, assay     

Acetylation and Phosphorylation of Histones and Nonhistone Chromosomal Proteins in Neuronal and Glial Nuclei Purified from Cerebral Hemispheres of Developing Rat Brain

The processes of acetylation and phosphorylation of histones and nonhistone proteins (NHPs) in neuronal and glial nuclei purified from cerebral hemispheres of rats at 1, 10, and 30 days of age were investigated. Purified neuronal and glial nuclei were incubated in the presence of [3H]acetyl-CoA and of [gamma-32P]ATP. Histones and NHPs were extracted and fractionated by gel electrophoresis. Densitometric and radioactive patterns were obtained. The results showed an increase of acetylation and phosphorylation from 1 to 10 and 30 days of age in both neuronal and glial nuclei in almost all histone and NHP fractions. Among the histones, the H3 fraction was always more labeled than the other fractions and showed the most remarkable differences during postnatal development. In the NHP fractions, the increase in acetylation from 1 to 10 and 30 days of age was more evident in the low-molecular-weight region of neuronal nuclei than in the corresponding fraction of glial nuclei. The appearance of highly phosphorylated proteins (70,000-90,000 daltons)--absent at 1 day, appearing at 10 days, and more evident at 30 days of age--was observed in both neuronal and glial nuclei.     

小麦种子成熟和萌发过程中的假萌发素活性

用SDS-PAGE方法研究了假萌发素(ψG)在小麦种子成熟和萌发过程中活性的变化.结果表明:在种子成熟过程中只有ψG表达,扬花后10 d,在颖壳、内外桴、种皮和果皮中皆可检测到ψG的草酸氧化酶活性,随着发育进程的推进,ψG的活性增大.在种子萌发过程中,在小麦品种中育5号的维管束过渡区中除了萌发素G和G'外,还可检测到ψG的草酸氧化酶活性.由于ψG在种子成熟过程中主要存在于颖壳、内外桴、果皮及种皮这些保护组织中,且开始大量表达的时间正是生长接近停止时,于是推测ψG很可能通过降解草酸产生H2O2而推动这些组织细胞壁的木质化.     

Behavior of the Nucleoside Triphosphate Diphosphatase in Pea Cotyledon Chromatin during Germination

The behavior of nucleoside triphosphate diphosphatase (NTDPase)of pea cotyledon chromatin was investigated by a comparisonof the activities of amylase and protease in the cytoplasm.The activities of NTDPase and amylase increased from the 3rdto the 5th day during germination, but the activity of proteaseincreased more rapidly at the stage of imbibition. The inhibitorsactinomycin D and cycloheximide markedly inhibited the increasein the activities of NTDPase and amylase, but their inhibitionof protease was much less. Inhibition of germination by saltstress was accompanied by reductions in the increases in NTDPaseand protease activities, but not by a reduction in amylase activity.Removal of the embryo from dormant seeds had the same effecton these activities as salt stress did. These results suggestthat formation of the NTDPase in the chromatin of the cotyledonis under the control of the embryonic tissue. (Received October 22, 1980; Accepted January 20, 1981)     

Transcriptional Activity,Chromosomal Distribution and Expression Effects of Transposable Elements in Coffea Genomes

Plant genomes are massively invaded by transposable elements (TEs), many of which are located near host genes and can thus impact gene expression. In flowering plants, TE expression can be activated (de-repressed) under certain stressful conditions, both biotic and abiotic, as well as by genome stress caused by hybridization. In this study, we examined the effects of these stress agents on TE expression in two diploid species of coffee, Coffea canephora and C. eugenioides, and their allotetraploid hybrid C. arabica. We also explored the relationship of TE repression mechanisms to host gene regulation via the effects of exonized TE sequences. Similar to what has been seen for other plants, overall TE expression levels are low in Coffea plant cultivars, consistent with the existence of effective TE repression mechanisms. TE expression patterns are highly dynamic across the species and conditions assayed here are unrelated to their classification at the level of TE class or family. In contrast to previous results, cell culture conditions per se do not lead to the de-repression of TE expression in C. arabica. Results obtained here indicate that differing plant drought stress levels relate strongly to TE repression mechanisms. TEs tend to be expressed at significantly higher levels in non-irrigated samples for the drought tolerant cultivars but in drought sensitive cultivars the opposite pattern was shown with irrigated samples showing significantly higher TE expression. Thus, TE genome repression mechanisms may be finely tuned to the ideal growth and/or regulatory conditions of the specific plant cultivars in which they are active. Analysis of TE expression levels in cell culture conditions underscored the importance of nonsense-mediated mRNA decay (NMD) pathways in the repression of Coffea TEs. These same NMD mechanisms can also regulate plant host gene expression via the repression of genes that bear exonized TE sequences.     

拟南芥WRKY61转录因子的转录活性与互作蛋白分析

该研究采用双荧光素酶报告系统、酵母双杂交和双分子荧光互补实验,对拟南芥AtWRKY61的转录活性及与AtWRKY61转录因子的互作蛋白进行了分析,并用qRT-PCR方法分析AtWRKY61对多种非生物逆境的响应特征,为进一步揭示AtWRKY61的功能与分子调控机制奠定基础。绿色荧光蛋白介导的亚细胞定位分析显示,AtWRKY61定位于细胞核内;基于原生质体的双荧光素酶报告系统和酵母实验发现,AtWRKY61具有转录抑制活性。qRT-PCR分析表明,AtWRKY61对多种非生物逆境的处理具有明显的响应,可能是在多条信号通路中发挥作用。酵母双杂交与双分子荧光互补分析表明,AtWRKY61与自身以及同组的AtWRKY9和AtWRKY72存在互作关系,暗示可能通过形成WRKY复合物来行使特定的转录抑制功能。     

Changes in Soluble RNA and Ribonuclease Activity During Germination of Wheat

Gross changes in protein and nucleic acid were studied in germinating wheat seeds. The nucleic acid fraction was separated on columns of methylated albumin-keiselguhr. It was found that more than 50% of the transfer RNA was lost from the embryo in the first 10 to 15 hours of germination. This was followed by a period of rapid resynthesis of transfer RNA, to the normal level at about 20 hours. The decline and increase in transfer RNA was accompanied by a change in the ratios of certain amino acid acceptor species. Evidence is also presented that an embryo ribonuclease is lost during the first 10 to 15 hours, followed by the appearance of a second seedling ribonuclease between 15 and 30 hours of germination.     

Involvement of Polypyrimidine Tract-Binding Protein (PTB)-Related Proteins in Pollen Germination in Arabidopsis

The pollen grains of most angiosperms contain stores of RNAsand their translation products required for pollen germinationand subsequent early elongation of pollen tubes. Polypyrimidinetract-binding protein (PTB), which is involved in the regulationof pre-mRNA alternative splicing, internal ribosomal entry site(IRES)-mediated translation and mRNA localization/sorting, isknown to act as a bridging molecule between RNAs and a varietyof cellular factors to fulfill cellular functions in both thenucleus and cytoplasm. Moreover, it has been reported that PTBplays roles in the differentiation and development of animalcells and tissues. In the Arabidopsis genome, there are twoPTB-related genes, tentatively termed AtPTB1 and AtPTB2. Inthe present study, the physiological functions of AtPTBs wereinvestigated using genetic and cytological approaches. The AtPTBpromoter was highly active in vegetative cells of mature pollengrains, and AtPTB was localized in the nucleus and cytoplasmof these vegetative cells. Mutations in the AtPTB genes resultedin decreased germination efficiency, and this effect was rescuedby introduction of the AtPTB2 promoter::AtPTB2–GFP. Takentogether, these findings suggest that AtPTB is involved in pollengermination through possible RNA metabolism processes in late-maturingand mature pollen grains.     

Non-histone Proteins Associated with Chromatin of Spirogyra during the Conjugation Process

Non-histone proteins were isolated from purified chromatin of Spirogyra sp. at different stages of the life cycle. Conjugation- specific acidic proteins were separated by DEAE-Sephadex A50 column chromatography. The protein fraction includes an inhibitor of chromatin-directed RNA synthesis.