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41.
42.
Contribution of sucrose synthase, ADP-glucose pyrophosphorylase and starch synthase to starch synthesis in developing pea seeds 总被引:11,自引:0,他引:11
Using genetic variability existing amongst nine pea genotypes (Pisum sativum L.), the biochemical basis of sink strength in developing pea seeds was investigated. Sink strength was considered to be reflected by the rate of starch synthesis (RSS) in the embryo, and sink activity in the seed was reflected by the relative rate of starch synthesis (RRSS). These rates were compared to the activities of three enzymes of the starch biosynthetic pathway [sucrose synthase (Sus), ADP-glucose pyrophosphorylase and starch synthase] at three developmental stages during seed filling (25, 50 and 75% of the dry seed weight). Complete sets of data collected during seed filling for the nine genotypes showed that, for all enzyme activities (expressed on a protein basis), only Sus in the embryo and seed coat was linearly and significantly correlated to RRSS. The contribution of the three enzyme activities to the variability in RSS and RRSS was evaluated by multiple regression analysis for the first two developmental stages. Only Sus activity in the embryo could explain, at least in part, the significant variability observed for both the RSS and the RRSS at each developmental stage. We conclude that Sus activity is a reliable marker of sink activity in developing pea seeds. 相似文献
43.
Rachel Cameron Jeff Davies Wayne Adcock Andrew MacGregor John P. Barford Yvonne Cossart Colin Harbour 《Biologicals》1997,25(4):391-401
The manufacturing process for albumin in Australia is based primarily on ion-exchange chromatography. The capacity of ion-exchange matrices to remove non-enveloped viruses (canine parvovirus and poliovirus type 1) was assessed using a scaled-down chromatographic process which was shown to yield product meeting purity criteria set for the manufacturing process. Poliovirus type 1 and canine parvovirus were added at one tenth the volume of desalted and delipidated Supernatant II+III produced by traditional Cohn Fractionation from human plasma before the material was applied to DEAE and CM ion-exchangers connected in series. Samples were taken at equilibration, wash, elution and regeneration steps and the log clearance and reduction of the viruses calculated. The mean clearance and reduction factors for viral load of poliovirus type 1 were 5·3 logs and 3·2 logs, respectively and 1·8 logs and 1·8 logs for canine parvovirus. 相似文献
44.
Sea urchin Hox genes: insights into the ancestral Hox cluster 总被引:3,自引:0,他引:3
We describe the Hox cluster in the radially symmetric sea urchin and
compare our findings to what is known from clusters in bilaterally
symmetric animals. Several Hox genes from the direct-developing sea urchin
Heliocidaris erythrogramma are described. CHEF gel analysis shows that the
Hox genes are clustered on a < or = 300 kilobase (kb) fragment of DNA,
and only a single cluster is present, as in lower chordates and other
nonvertebrate metazoans. Phylogenetic analyses of sea urchin, amphioxus,
Drosophila, and selected vertebrate Hox genes confirm that the H.
erythrogramma genes, and others previously cloned from other sea urchins,
belong to anterior, central, and posterior groups. Despite their radial
body plan and lack of cephalization, echinoderms retain at least one of the
anterior group Hox genes, an orthologue of Hox3. The structure of the
echinoderm Hox cluster suggests that the ancestral deuterostome had a Hox
cluster more similar to the current chordate cluster than was expected Sea
urchins have at least three Abd-B type genes, suggesting that Abd-B
expansion began before the radiation of deuterostomes.
相似文献
45.
The application of simple growth and non-growth associated concepts from microbial systems describing substrate uptake and production formation is considered unlikely to assist in the understanding of antibody formation and, hence, in maximising antibody yield. Such concepts have many significant limitations — notably, their strict application only to products of catabolic pathways and their inability to include metabolisms which either have multiple catabolic pathways (eg, fermentation and respiration in yeast and animal cells) or in which the major product of interest is predominantly anabolic in nature (eg. amino acid production in bacteria and antibody formation in animal cells). In addition, products which undergo an assembly and secretion process or a secretion process which allows intracellular pools of product to exist are also not well described by such simple relationships. In this work, inadequacies in the current approach to the study of the kinetics of growth of hybridoma cells and antibody production are described and the examples of growth ofSaccharomyces cerevisiae andCandida utilis, amino acid production by bacteria and antibody production by animal cells are used to illustrate these limitations. Having identified these limitations, suggestions are made as to how studies might be undertaken to assist our future understanding of the process of antibody manufacture and, subsequently, maximizing antibody yield. The process of characterising the metabolism of anabolic products is subject to detailed computer simulation of the pathways involved. It is argued that such approaches will assist us in understanding more fully the nature of biosynthetic products and how they integrate with the major energy producing pathways of the cell and the cell cycle. This will assist in maximising the yield of such products. 相似文献
46.
This paper presents batch culture data of the murine hybridoma, AFP-27, cultured in conventional basal media and in a nutrient-rich modified version. Expression of antibody was fivefold higher in the enriched formulation, with significant product secretion in the decline phase. Cultures were initiated at conventional inculation densities (1 2 × 105 viable cells ml–1) and high inoculation densities (1.5 1.7 × 106 viable cells ml–1). Amino acid levels have been reported for all cultures, with apparent differences described. Relative levels of intracellular amino acids are also reported, with significant accumulation of proline, glycine and alanine. The results have significance in the design of enriched media which are clearly beneficial for commercial production of antibodies from hybridomas. 相似文献
47.
Summary The use of hybridoma cell lines to produce monoclonal antibodies for therapeutic use carries with it the risk of transmitting viruses known to contaminate such cell lines. It is shown here that a murine monoclonal IgM can be heated at 80 °C for 72 hours without loss of activity and with significant killing of two types of test virus. 相似文献
48.
Secretory Proteins from Adrenal Medullary Cells Are Carboxyl-Methylated In Vivo and Released Under Their Methylated Form by Acetylcholine 总被引:1,自引:0,他引:1
The carboxyl methylation of secretory proteins in vivo was investigated in bovine adrenal medullary cells in culture. Chromogranin A, the major intragranular secretory protein in adrenal medullary cells, and other secretory proteins were found to be carboxyl-methylated within secretory vesicles. The in vivo labeling pattern using [methyl-3H]methionine and the in vitro labeling pattern using S-adenosyl-[methyl-14C]methionine of intravesicular secretory proteins were similar. The detection of methylated chromogranin A in mature secretory vesicles required 3-6 h, a time consistent with the synthesis and storage of secretory proteins in this tissue. Carboxyl-methylated chromogranin A was secreted from medullary cells by exocytosis via activation of nicotinic cholinergic receptor and recovered still under the methylated form in the incubation medium. Since protein-carboxyl-methylase is cytosolic, these results suggest that methylation of secretory proteins is a cotranslational phenomenon. 相似文献
49.
50.
Thérèse S Lapperre Jacob K Sont Annemarie van Schadewijk Margot ME Gosman Dirkje S Postma Ingeborg M Bajema Wim Timens Thais Mauad Pieter S Hiemstra 《Respiratory research》2007,8(1):85-9