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951.
本文将鱼类抗冻蛋白应用于植物细胞的超低温保存。结果表明,在水稻悬浮细胞的两步法保存中,浓度为0.01mg/ml的抗冻蛋白具有特别的负作用,相对高浓度的抗冻蛋白则能减小细胞存活率的波动性。在玻璃化法保存中,浓度为0.2mg/ml的抗冻蛋白能改善保存效果,更高浓度的抗冻蛋白(>5mg/ml)反而会降低保存效果。环境冰晶量、抗冻蛋白浓度、低温保护剂浓度和细胞膜组成等是影响抗冻蛋白使用效果的几大因素。作者在机理分析中认为,一方面,抗冻蛋白能和冰晶作用,抑制重冰晶,防止去玻璃化;另一方面,抗冻蛋白也能和细胞膜作用,诱发膜表面冰晶形成。 相似文献
952.
Adding gelling agents to cotton ovule culture media leads to subtle changes in fiber development 总被引:1,自引:0,他引:1
Barbara A. Triplett Damicca S. Johnson 《In vitro cellular & developmental biology. Plant》1999,35(3):265-270
Summary Young cotton (Gossypium hirsutum) ovules will produce fiber in vitro when floated on a defined culture medium. Our laboratory is interested in examining the
effects of altered gravity environments on fiber development as a model for the effects of gravity on cell expansion and cellulose
biosynthesis. Since liquid culture media are unsuitable for altered gravity experiments, addition of gelling agents to cotton
ovule culture media is necessary. In this study we have systematically examined the effects of four gelling agents at several
concentrations on fiber production in culture. A rapid screening method using toluidine blue O staining indicated that after
3 wk in culture, fiber growth on 0.15% (wt/vol) Phytagel™ medium was similar to fiber growth on liquid medium. More detailed
analysis of fiber development revealed that fiber length was not influenced by the addition of Phytagel™. Accumulation of
cellulose, however, was reduced 50–60% compared with fibers produced in liquid media after 3 wk in culture. The fiber cellulose
content rose with additional time in culture for both solid and liquid media treatments. By 4 wk in culture, the difference
in cellulose content of fiber cell walls grown on solid versus liquid media was less than 20%. This variance in growth response
on gelled media could be due to differences in media matric potential, to the immobility of ions trapped within the gel, or
to toxicity of contaminants copurifying with Phytagel™. By identifying why ovule growth and fiber cellulose biosynthesis are
reduced in cultures grown on gelled media, it will be possible to reveal new information about these processes in system that
is less complicated than physiological systems at the whole plant level.
Names of companies or commercial products are given solely for the purpose of providing specific information; their mention
does not imply recommendation or endorsement by the U.S. Department of Agriculture over others not mentioned. 相似文献
953.
Li Hongchao Machii Hiroaki Hagio Takashi Takezaki Akane Hirabayashi Toshio 《Plant Cell, Tissue and Organ Culture》1999,58(2):119-125
A fast-growing, small, granular, embryogenic callus was selected from primary calli induced from the Japanese wheat cultivar
Nakasoushu and the Australian wheat cultivar Bodallin. Regenerable and fine suspension cultures were induced three to six
months after liquid culture was initiated and were characterized by dense cytoplasm and active division. These suspension
cultures routinely provided high yields of protoplasts with about 90% viability when incubated in a modified KMP (Kao and
Michayluk, 1975) medium containing 1 mg l-1 2,4-D (2,4-dichlorophenoxyacetic acid), and 1 mg l-1 zeatin. Nakasoushu and Bodallin protoplasts divided at frequencies of 8.6% and 11.1%, respectively, in agarose-solidified
media. When Nakasoushu protoplasts were cultured with effective nurse cells of sorghum and wheat, protoplast division increased
to 16.9% and 12.6%, respectively. Plating efficiencies varied from 0.03% to 2.5%. After subculture, protocolonies yielded
embryogenic calli and somatic embryos, from which green plants were eventually regenerated. Whole plants obtained from Nakasoushu
protoplasts were fertile, demonstrating the first report of Japanese cultivars in wheat protoplast cultures.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
954.
Partial purification and characterization of geissoschizine dehydrogenase from suspension cultures of Catharanthus roseus 总被引:1,自引:0,他引:1
The characterization and partial purification of geissoschizine dehydrogenase from Catharanthus roseus cell suspension cultures are described. The 35-fold purified enzyme removes the 21α-hydrogen of geissoschizine in a NADP+-dependent reaction. NAD+, FAD or FMN cannot act as cofactors for the dehydrogenation. Structurally related indole alkaloids are not dehydrogenated. In comparison to enzymes of the ajmalicine pathway, geissoschizine dehydrogenase shows an extremely low specific activity. 相似文献
955.
Marcelo Vizona Liberato Bruna Medeia Campos Geizecler Tomazetto Lucy Isobel Crouch Wanius Garcia Ana Carolina de Mattos Zeri David Nichol Bolam Fabio Marcio Squina 《The Journal of biological chemistry》2022,298(5)
Deciphering how enzymes interact, modify, and recognize carbohydrates has long been a topic of interest in academic, pharmaceutical, and industrial research. Carbohydrate-binding modules (CBMs) are noncatalytic globular protein domains attached to carbohydrate-active enzymes that strengthen enzyme affinity to substrates and increase enzymatic efficiency via targeting and proximity effects. CBMs are considered auspicious for various biotechnological purposes in textile, food, and feed industries, representing valuable tools in basic science research and biomedicine. Here, we present the first crystallographic structure of a CBM8 family member (CBM8), DdCBM8, from the slime mold Dictyostelium discoideum, which was identified attached to an endo-β-1,4-glucanase (glycoside hydrolase family 9). We show that the planar carbohydrate-binding site of DdCBM8, composed of aromatic residues, is similar to type A CBMs that are specific for crystalline (multichain) polysaccharides. Accordingly, pull-down assays indicated that DdCBM8 was able to bind insoluble forms of cellulose. However, affinity gel electrophoresis demonstrated that DdCBM8 also bound to soluble (single chain) polysaccharides, especially glucomannan, similar to type B CBMs, although it had no apparent affinity for oligosaccharides. Therefore, the structural characteristics and broad specificity of DdCBM8 represent exceptions to the canonical CBM classification. In addition, mutational analysis identified specific amino acid residues involved in ligand recognition, which are conserved throughout the CBM8 family. This advancement in the structural and functional characterization of CBMs contributes to our understanding of carbohydrate-active enzymes and protein–carbohydrate interactions, pushing forward protein engineering strategies and enhancing the potential biotechnological applications of glycoside hydrolase accessory modules. 相似文献
956.
Plant cell wall is the most abundant substrate for bioethanol production, and plants also represent a key resource for glycoside hydrolase (GH). To exploit efficient way for bioethanol production with lower cellulase loading, the potential of plant GH for lignocellulose bioconversion was evaluated. The GH activity for cell wall proteins (CWPs) was detected from fresh corn stover (FCS), and the synergism of which with Trichoderma reesei cellulase was also observed. The properties for the GH of FCS make it a promising enzyme additive for lignocellulose biodegradation. To make use of the plant GH, novel technology for hydrolysis and ethanol fermentation was developed with corn stover as substrate. Taking steam-exploded corn stover as substrate for hydrolysis and ethanol fermentation, compared with T. reesei cellulase loaded alone, the final glucose and ethanol accumulation increased by 60% and 63% respectively with GH of FCS as an addition. 相似文献
957.
958.
The focus of this study was to alter the xylan content of corn stover and poplar using SO2‐catalyzed steam pretreatment to determine the effect on subsequent hydrolysis by commercial cellulase preparations supplemented with or without xylanases. Steam pretreated solids with xylan contents ranging from ~1 to 19% (w/w) were produced. Higher xylan contents and improved hemicellulose recoveries were obtained with solids pretreated at lower severities or without SO2‐addition prior to pretreatment. The pretreated solids with low xylan content (<4% (w/w)) were characterized by fast and complete cellulose to glucose conversion when utilizing cellulases. Commercial cellulases required xylanase supplementation for effective hydrolysis of pretreated substrates containing higher amounts of xylan. It was apparent that the xylan content influenced both the enzyme requirements for hydrolysis and the recovery of sugars during the pretreatment process. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 相似文献
959.
金针菇液体培养特性及胞外酶研究 总被引:7,自引:0,他引:7
测定了金针菇在PDY液体培养基中生长时 ,培养液 pH值的变化 ,蛋白质含量和菌丝球重量 ;研究了羧甲基纤维素酶、半纤维素酶、多酚氧化酶、愈创木酚氧化酶和漆酶的酶活性变化。结果表明 ,在整个培养期内 5种酶均有酶活性 ,但不同酶的活性有较大差异 ,产酶高峰也不尽相同 相似文献
960.
Tracing carbon and oxygen isotope signals from newly assimilated sugars in the leaves to the tree-ring archive 总被引:1,自引:0,他引:1
ARTHUR GESSLER ELKE BRANDES NINA BUCHMANN GERHARD HELLE HEINZ RENNENBERG & ROMAIN L. BARNARD 《Plant, cell & environment》2009,32(7):780-795
The analysis of δ 13 C and δ 18 O in tree-ring archives offers retrospective insights into environmental conditions and ecophysiological processes. While photosynthetic carbon isotope discrimination and evaporative oxygen isotope enrichment are well understood, we lack information on how the isotope signal is altered by downstream metabolic processes.
In Pinus sylvestris , we traced the isotopic signals from their origin in the leaf water ( δ18 O) or the newly assimilated carbon ( δ 13 C), via phloem sugars to the tree-ring, over a time-scale that ranges from hours to a growing season.
Seasonally, variable13 C enrichment of sugars related to phloem loading and transport did lead to uncoupling between δ 13 C in the tree-ring, and the c i / c a ratio at the leaf level. In contrast, the oxygen isotope signal was transferred from the leaf water to the tree-ring with an expected enrichment of 27‰, with time-lags of approximately 2 weeks and with a 40% exchange between organic oxygen and xylem water oxygen during cellulose synthesis.
This integrated overview of the fate of carbon and oxygen isotope signals within the model tree species P. sylvestris provides a novel physiological basis for the interpretation of δ13 C and δ 18 O in tree-ring ecology. 相似文献
In Pinus sylvestris , we traced the isotopic signals from their origin in the leaf water ( δ
Seasonally, variable
This integrated overview of the fate of carbon and oxygen isotope signals within the model tree species P. sylvestris provides a novel physiological basis for the interpretation of δ