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991.
Summary. In order to produce doubled-haploid maize plants tolerant of oxidative stress, in vitro microspore selection was carried out
in anther culture with reactive oxygen species (ROS) progenitors such as paraquat, menadione, tert-butylhydroperoxide (t-BHP), and methionine combined with riboflavin. All the ROS progenitors reduced the anther induction,
the formation of microspore-derived structures, and their regeneration potential. Abnormal cell divisions and progeny cell
degradation could be observed during the development of microspores treated with ROS progenitors. Menadione and t-BHP influenced
the microspore developmental pathway, as menadione induced the formation of embryoids, while t-BHP increased the proportion
of calli in the microspore-derived structures. As the result of in vitro selection, 15, 10, 10, and 3 fertile doubled-haploid
plants were obtained in cultures treated with paraquat, t-BHP, methionine combined with riboflavin, and menadione, respectively.
Correspondence and reprints: Agricultural Research Institute, Hungarian Academy of Sciences, Brunszvik utca 2, 2462 Martonvásár,
Hungary. 相似文献
992.
Cell culture media supplementation of infrequently used sugars for the targeted shifting of protein glycosylation profiles 下载免费PDF全文
Patrick Hossler Christopher Racicot Christopher Chumsae Sean McDermott Keith Cochran 《Biotechnology progress》2017,33(2):511-522
Mammalian cells in culture rely on sources of carbohydrates to supply the energy requirements for proliferation. In addition, carbohydrates provide a large source of the carbon supply for supporting various other metabolic activities, including the intermediates involved in the protein glycosylation pathway. Glucose and galactose, in particular, are commonly used sugars in culture media for these purposes. However, there exists a very large repertoire of other sugars in nature, and many that have been chemically synthesized. These sugars are particularly interesting because they can be utilized by cells in culture in distinct ways. In the present work it has been found that many infrequently used sugars, and the corresponding cellular response towards them as substrates, led to differences in the protein N‐glycosylation profile of a recombinant glycoprotein. The selective media supplementation of raffinose, trehalose, turanose, palatinose, melezitose, psicose, lactose, lactulose, and mannose were found to be capable of redirecting N‐glycan oligosaccharide profiles. Despite this shifting of protein glycosylation, there were no other adverse changes in culture performance, including both cell growth and cellular productivity over a wide range of supplemented sugar concentrations. The approach presented highlights a potential means towards both the targeted shifting of protein glycosylation profiles and ensuring recombinant protein comparability, which up to this point in time has remained under‐appreciated for these under‐utilized compounds. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:511–522, 2017 相似文献
993.
A practical approach in bioreactor scale‐up and process transfer using a combination of constant P/V and vvm as the criterion 下载免费PDF全文
Sen Xu Linda Hoshan Rubin Jiang Balrina Gupta Eric Brodean Kristin O'Neill T. Craig Seamans John Bowers Hao Chen 《Biotechnology progress》2017,33(4):1146-1159
Bioreactor scale‐up is a critical step in the production of therapeutic proteins such as monoclonal antibodies (MAbs). With the scale‐up criterion such as similar power input per volume or O2 volumetric mass transfer coefficient ( ), adequate oxygen supply and cell growth can be largely achieved. However, CO2 stripping in the growth phase is often inadequate. This could cascade down to increased base addition and osmolality, as well as residual lactate increase and compromised production and product quality. Here we describe a practical approach in bioreactor scale‐up and process transfer, where bioreactor information may be limited. We evaluated the sparger and (CO2 volumetric mass transfer coefficient) from a range of bioreactor scales (3–2,000 L) with different spargers. Results demonstrated that for oxygen is not an issue when scaling from small‐scale to large‐scale bioreactors at the same gas flow rate per reactor volume (vvm). Results also showed that sparging CO2 stripping, , is dominated by the gas throughput. As a result, a combination of a minimum constant vvm air or N2 flow with a similar specific power was used as the general scale‐up criterion. An equation was developed to determine the minimum vvm required for removing CO2 produced from cell respiration. We demonstrated the effectiveness of using such scale‐up criterion with five MAb projects exhibiting different cell growth and metabolic characteristics, scaled from 3 to 2,000 L bioreactors across four sites. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1146–1159, 2017 相似文献
994.
The effects of chitosan, acetic acid and citric acid on production and release of hyoscyamine and scopolamine in hairy root
cultures of Brugmansia candida were studied. Chitosan and acetic acid were tested at different concentrations and also at different media pH values. At
pH 5.5, and at certain concentrations, acetic acid and chitosan increased the content of root scopolamine and hyoscyamine,
and promoted the release of both alkaloids. Lowering the pH to 3.5 and 4.5 reduced the accumulation of both alkaloids in the
roots, but at a pH of 4.5, their release increased significantly. Acetic and citric acid stimulated the release of scopolamine
and hyoscyamine.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
995.
Ferrie A.M.R. Taylor D.C. MacKenzie S.L. Keller W.A. 《Plant Cell, Tissue and Organ Culture》1999,57(2):79-84
Brassica oleracea accessions possess traits that would be useful in commercial Brassica crops. These traits can be studied
more effectively through the production of doubled haploid plants. Nineteen B. oleracea accessions from several subspecies
possessing significant sn-2 erucic acid were screened for suitability for microspore culture using techniques well established
for Brassica. Fifteen of the 19 accessions produced embryos. Genotypic differences were observed with embryogenesis ranging
from 0 to 3000 embryos/100 buds. Embryogenesis was improved for two of four accessions by initiating cultures in NLN medium
with 17% sucrose, then reducing sucrose to 10% after 48 h. An increase in embryogenesis for the same two accessions was observed
when microspores were cultured at a density of 100 000/ml rather than 50 000 microspores/ml. A culture temperature of 32 °C
for 48 h was beneficial for three of the four accessions when compared to a longer incubation period (72 h) or a higher temperature
(35 °C). One accession line, Bo-1, was found to produce microspore-derived embryos which contained triacylglycerols with significant
proportions of erucic acid at the sn-2 position.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
996.
997.
Agocha Augustine E. Eghbali-Webb Mahboubeh 《Molecular and cellular biochemistry》1997,172(1-2):195-198
Cardiac fibroblasts constitute greater than 90% of non-myocyte cells in the heart. Because they are responsible for synthesis of components of the extracellular matrix, growth factors and cytokines in the myocardium, they play an important role in normal and pathologic performance of the heart. An understanding of their biology requires in depth studies in a stable and reliable system in which the biological responses of cardiac fibroblasts to various stimuli can be determined. With the exception of few, all studies have been performed on cardiac fibroblasts obtained from rodent hearts. We present a method for isolation and subsequent culture of viable cardiac fibroblasts from ventricular tissue of adult human. This method allows rapid and reliable isolation and subsequent culture of cardiac fibroblasts from adult heart tissue without the need for cumbersome isolation techniques and complex nutrient-enriched and hormone-supplemented culture media for maintenance. 相似文献
998.
A pathway for conversion of the metabolic intermediate phosphoenolpyruvate (PEP) and the formation of acetate, succinate, formate, and H2 in the anaerobic cellulolytic bacterium Ruminococcus flavefaciens FD-1 was constructed on the basis of enzyme activities detected in extracts of cells grown in cellulose- or cellobiose-limited continuous culture. PEP was converted to acetate and CO2 (via pyruvate kinase, pyruvate dehydrogenase, and acetate kinase) or carboxylated to form succinate (via PEP carboxykinase, malate dehydrogenase, fumarase, and fumarate reductase). Lactate was not formed even during rapid growth (batch culture, µ = 0.35/h). H2 was formed by a hydrogenase rather than by cleavage of formate, and 13C-NMR and14 C-exchange reaction data indicated that formate was produced by CO2 reduction, not by a cleavage of pyruvate. The distribution of PEP into the acetate and succinate pathways was not affected by changing extracellular pH and growth rates within the normal growth range. However, increasing growth rate from 0.017/h to 0.244/h resulted in a shift toward formate production, presumably at the presence of H2. This shift suggested that reducing equivalents could be balanced through formate or H2 production without affecting the yields of the major carbon-containing fermentation endproducts. 相似文献
999.
Morphological and isozyme variation was observed among plants regenerated from callus cultures of Cereus peruvianus. Different morphological types of shoots (68%) were observed in 4-year-old regenerated plants, while no distinct morphological variants were observed in plants grown from germinated seeds. Isozyme patterns of 633 plants regenerated from calli and of 261 plants grown from germinated seeds showed no variation in isocitrate dehydrogenase isozyme, and the differential sorbitol dehydrogenase, alcohol dehydrogenase, malate dehydrogenase, acid phosphatase, and peroxidase isozyme patterns observed in regenerated plants were attributed to nonallelic variation. Allelic variation was detected at three isoesterase loci. The proportion of polymorphic loci for both populations was 13.6% and the deviation from Hardy–Weinberg equilibrium for the Est-1 and Est-7 loci observed in somaclones was attributed to the manner in which the regenerant population was established. The high values for genetic identity among regenerant and seed-grown plant populations are in accordance with the low levels of interpopulation genetic divergence. In somaclones of C. peruvianus, morphological divergence was achieved within a short time but was not associated with any isozyme changes and also was not accompanied by biochemical genetic divergence. 相似文献
1000.