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91.
Bacillus anthracis makes highly stable, heat-resistant spores which remain viable for decades. Effect of various stress conditions on sporulation in B. anthracis was studied in nutrient-deprived and sporulation medium adjusted to various pH and temperatures. The results revealed that sporulation efficiency was dependent on conditions prevailing during sporulation. Sporulation occurred earlier in culture sporulating at alkaline pH or in PBS than control. Spores formed in PBS were highly sensitive towards spore denaturants whereas, those formed at 45°C were highly resistant. The decimal reduction time (D-10 time) of the spores formed at 45°C by wet heat, 2 M HCl, 2 M NaOH and 2 M H2O2 was higher than the respective D-10 time for the spores formed in PBS. The dipicolinic acid (DPA) content and germination efficiency was highest in spores formed at 45°C. Since DPA is related to spore sensitivity towards heat and chemicals, the increased DPA content of spores prepared at 45°C may be responsible for increased resistance to wet heat and other denaturants. The size of spores formed at 45°C was smallest amongst all. The study reveals that temperature, pH and nutrient availability during sporulation affect properties of B. anthracis spores.  相似文献   
92.
Endosperm cellularization is essential for embryo development and viable seed formation. Loss of function of the FERTILIZATION INDEPENDENT SEED (FIS) class Polycomb genes, which mediate trimethylation of histone H3 lysine27 (H3K27me3), as well as imbalanced contributions of parental genomes interrupt this process. The causes of the failure of cellularization are poorly understood. In this study we identified PICKLE RELATED 2 (PKR2) mutations which suppress seed abortion in fis1/mea by restoring endosperm cellularization. PKR2, a paternally expressed imprinted gene (PEG), encodes a CHD3 chromatin remodeler. PKR2 is specifically expressed in syncytial endosperm and its maternal copy is repressed by FIS1. Seed abortion in a paternal genome excess interploidy cross was also partly suppressed by pkr2. Simultaneous mutations in PKR2 and another PEG, ADMETOS (ADM), additively rescue the seed abortion in fis1 and in the interploidy cross, suggesting that PKR2 and ADM modulate endosperm cellularization independently and reproductive isolation between plants of different ploidy is established by imprinted genes. Genes upregulated in fis1 and downregulated in the presence of pkr2 are enriched in glycosyl‐hydrolyzing activity, while genes downregulated in fis1 and upregulated in the presence of pkr2 are enriched with microtubule motor activity, consistent with the cellularization patterns in fis1 and the suppressor line. The antagonistic functions of FIS1 and PKR2 in modulating endosperm development are similar to those of PICKLE (PKL) and CURLY LEAF (CLF), which antagonistically regulate root meristem activity. Our results provide further insights into the function of imprinted genes in endosperm development and reproductive isolation.  相似文献   
93.
A Weed Reaches New Heights Down Under   总被引:1,自引:0,他引:1       下载免费PDF全文
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94.
Psoriasis is a polygenic chronic skin condition, associated with many systemic disorders. Though it is most studied dermatological condition, molecular mechanism leading to its pathogenesis is still unclear. An insight into its proteome may help unrevealing some biomarkers and therapeutic targets. In this study, we carried out mass spectrometry based quantitative proteomic analysis of serum from psoriasis patients by employing Tandem Mass Tags (TMT) approach. We identified 861,887 MS/MS spectra corresponding to 493 proteins. These dysregulated proteins were further classified by Gene Ontology and protein-protein interaction of dys-regulated proteins revealed networks in psoriasis patients.  相似文献   
95.
96.
Electroporation was used for gene delivery and evaluation of various parameters affecting transient expression of a gene for β-glucuronidase ( gus ) in leaf protoplasts of Oryza sativa var. Basmati-370. Transient expression was found to be dependent on voltage, capacitance, amount of plasmid and carrier DNA as well as period of culture. Maximum GUS activity was obtained when a 150 ms pulse at 300 V cm-1 and 200 μF was applied to the protoplasts (l–2×106ml−1) in an electroporation buffer containing 20 μg of plasmid and 30 μg of calf thymus DNA, assayed 48 h after electroporation. DNA topology did not influence expression of the gene as both linear and supercoiled templates resulted in similar activities, but a 4-fold decrease in expression was observed if the gene was excised, reflecting the positive influence of vector sequences on gene expression.  相似文献   
97.
Investigations were undertaken on the desiccation and freezingsensitivity of recalcitrant seeds of three species: tea [Camelliasinensis (L.) O. Kuntze], cocoa (Theobroma cacao L.) and jackfruit(Artocarpus heterophyllus Lamk.). All species showed changesin the physiological characteristics, desiccation and freezingsensitivity of both the seed and the embryonic axes with increasingseed maturity. Fully mature seeds of tea, cocoa and jackfruitsurvived desiccation to 24, 35 and 31% moisture content, respectively,but at these moisture levels seeds were not able to toleratefreezing in liquid nitrogen (-196 °C). Some survival ofcryopreservation was, however, achieved for excised embryonicaxes of partially and fully-mature tea and jackfruit seeds afterdrying to 14% moisture content; cocoa axes were totally freezingsensitive at all three stages of physiological maturity studied.Biochemical investigations on fully mature axes after desiccationand freezing showed that the decline in viability with moisturelevel was associated with increased leachate conductivity, lipidperoxidation products and/or soluble carbohydrates. Evidencefor disruption of cell membranes during desiccation and freezingwas supported by ultrastructural studies.Copyright 1995, 1999Academic Press Camellia sinensis (L.) O. Kuntze, Theobroma cacao L., Artocarpus heterophyllus Lamk., Phaseolus vulgaris L., tea, cocoa, jackfruit, french bean, seeds, embryonic axes, desiccation, freezing, cryopreservation  相似文献   
98.
Precocene treatment does not disrupt the events of reproduction in Glossina morsitans morsitans or induce any apparent changes in treated tsetse. However, some females of the F1 generation are either sterile or show retardations in follicle development. Sterility is not reversed spontaneously or with juvenile hormone analogues. The critical period for precocene action is related to each ovulation. The corpora allata of precocene-treated tsetse are normal, but those of F1 sterile females are degenerate. The occurrence of retardation has enabled the characterisation of stages in follicle development in G. m. morsitans.  相似文献   
99.
By means of contact angle determinations with two liquids, on hydrated as well as on dried protein layers, the long-range and the short-range contributions to the protein surface tensions, and from these the protein (G 131) and the protein-ligand (G 132) free energies of interaction in aqueous media, were determined. For human serum albumin (HSA), human IgG, and human IgA, the differences between G 131 HYDRATED and G 131 DRY were connected with the behavior of these proteins in low concentrations of (NH4)2SO4 versus saturated (NH4)2SO4 solutions. By interpolation, intermediate points are found that correlate well with the known salting-out properties of these three proteins. On the basis of the data, it is predicted that the precipitation of IgG by 1/3 saturated (NH4)2SO4 is preventable, or reversible, by the admixture of 15% dimethylsulfoxide; both predictions are confirmed experimentally. From the G 132 values found, it is shown that HSA and IgG should attach to phenyl ligands under physiological conditions, but that IgA is so hydrophilic that it only can adhere to phenyl ligands after partial dehydration brought about when admixed with 1 M (NH4)2SO4. Closer analysis of the values obtained for the long-range and short-range components of the surface tensions of HSA, IgG, and IgA allow deeper insight into their functional, chemical, and physicochemical properties.  相似文献   
100.
Circadian regulation of hippocampal long-term potentiation   总被引:4,自引:0,他引:4  
The goal of this study is to investigate the possible circadian regulation of hippocampal excitability and long-term potentiation (LTP) measured by stimulating the Schaffer collaterals (SC) and recording the field excitatory postsynaptic potential (fEPSP) from the CA1 dendritic layer or the population spike (PS) from the soma in brain slices of C3H and C57 mice. These 2 strains of mice were of interest because the C3H mice secrete melatonin rhythmically while the C57 mice do not. The authors found that the magnitude of the enhancement of the PS was significantly greater in LTP recorded from night slices compared to day slices of both C3H and C57 mice. They also found significant diurnal variation in the decay of LTP measured with fEPSPs, with the decay slower during the night in both strains of mice. There was evidence for a diurnal rhythm in the input/output function of pyramidal neurons measured at the soma in C57 but not C3H mice. Furthermore, LTP in the PS, measured in slices prepared during the day but recorded during the night, had a profile remarkably similar to the night group. Finally, PS recordings were carried out in slices from C3H mice maintained in constant darkness prior to experimentation. Again, the authors found that the magnitude of the enhancement of the PS was significantly greater in LTP recorded from subjective night slices compared to subjective day slices. These results provide the 1st evidence that an endogenous circadian oscillator modulates synaptic plasticity in the hippocampus.  相似文献   
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