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21.
It is known that few wheat cultivars maintain their resistance to rust diseases for a long period of time, particularly when crop populations become genetically more uniform. A number of genetically diverse, so far unexploited, sources of rust resistance in the natural as well as mutagenized population of wheat cultivars were identified. Several of these genes were placed in agronomically superior well-adapted backgrounds so that they could be used as pre-breeding stocks for introducing genetic diversity for resistance in a crop population. Some of these stocks when employed as parents in several cross combinations in a breeding programme have generated a number of promising cultivars with diversity for resistance.Many presently grown wheats in India, near-isogenic lines each with Lr14b, Lr14ab, Lr30 and certain international cultivars were identified as possessing diverse sources of adult plant resistance (APR) to leaf rust. Prolonged leaf rust resistance in some of the Indian cultivars was attributed to the likely presence of Lr34 either alone or in combination with other APR components. Tests of allelism carried out in certain cultivars that continue to show adequate levels of field resistance confirm the presence of Lr34, which explains the role that this gene has played in imparting durability for resistance to leaf rust. Also, Lr34 in combination with other APR components increases the levels of resistance, which suggests that combination of certain APR components should be another important strategy for breeding cultivars conferring durable and adequate levels of resistance. A new adult plant leaf rust resistance source that seems to be associated with durability in Arjun has been postulated. Likewise, cultivars possessing Sr2 in combination with certain other specific genes have maintained resistance to stem rust.Further, non-specific resistances that were transferred across widely different genotypes into two of the popular Indian wheats provided easily usable materials to the national breeding programmes for imparting durable resistance to stripe rust. 相似文献
22.
P. N. Joshi B. Biswal G. Kulandaivelu U. C. Biswal 《Radiation and environmental biophysics》1994,33(2):167-176
Response of senescing leaves of wheat seedlings to ultraviolet A (UVA) radiation (365 nm) has been examined. The results indicate that senescence-induced disorganization of thylakoid membrane, decline in carotenoid-to-chlorophyll energy transfer, and enhancement of lipid peroxidation are furthered by radiation. The senescence-induced decline in photochemical activity of photosystem II further declines on irradiation. UVA does not specifically alter any site other than those damaged by senescence. 相似文献
23.
24.
Sushama Chaphalkar Rajdeep Dongre Deepa Joshi Sabita Dey 《Biotechnic & histochemistry》1993,68(3):166-168
A synthetic aromatic polymer has been used for preparing replicas of different microorganisms. This method of preparing highly concentrated (9.6 k) microbiological samples for scanning electron microscopy was compared with a standard method. The micrographs of the replicated samples are satisfactory. This method is rapid, cost effective and produces good results, especially in the case of spore-forming mycelial microorganisms. 相似文献
25.
R. Ashton Lavoie Jeffrey T. Zugates Andrew T. Cheeseman Matt A. Teten Srivatsan Ramesh Julia M. Freeman Summer Swango Jeremy Fitzpatrick Amod Joshi Bradley Hollers Zufan Debebe Tyler K. Lindgren Amber N. Kozak Vinay K. Kondeti Mary K. Bright Eric J. Yearley Alexander Tracy Jacob A. Irwin Michael Guerrero 《Biotechnology and bioengineering》2023,120(10):2953-2968
Adeno-associated virus-based gene therapies have demonstrated substantial therapeutic benefit for the treatment of genetic disorders. In manufacturing processes, viral capsids are produced with and without the encapsidated gene of interest. Capsids devoid of the gene of interest, or “empty” capsids, represent a product-related impurity. As a result, a robust and scalable method to enrich full capsids is crucial to provide patients with as much potentially active product as possible. Anion exchange chromatography has emerged as a highly utilized method for full capsid enrichment across many serotypes due to its ease of use, robustness, and scalability. However, achieving sufficient resolution between the full and empty capsids is not trivial. In this work, anion exchange chromatography was used to achieve empty and full capsid resolution for adeno-associated virus serotype 5. A salt gradient screen of multiple salts with varied valency and Hofmeister series properties was performed to determine optimal peak resolution and aggregate reduction. Dual salt effects were evaluated on the same product and process attributes to identify any synergies with the use of mixed ion gradients. The modified process provided as high as ≥75% AAV5 full capsids (≥3-fold enrichment based on the percent full in the feed stream) with near baseline separation of empty capsids and achieved an overall vector genome step yield of >65%. 相似文献
26.
Studies on the lipozyme-catalyzed synthesis of butyl laurate 总被引:4,自引:0,他引:4
The effects of temperature, speed of agitation, enzyme concentration, etc., on butyl laurate synthessis using Mucor miehei lipase (Lipozymetrade mark) have been studied. Although the soluble enzyme was quite thermcstable in aqeous solution, it deactivated rapidly at and above 40 degrees C in the presence of butanol. This enzyme immobilized on an anion-exchange resin (Lipozymetrade mark) showed enhanced stability (as compared to the soluble form) to denaturation by butanol under the same conditions. The denaturation of M. miehei lipase was found to be a function of the butanol concentration in the aqueous phase, and rapid denaturation takes place at the concentration corresponding to its saturation at that temperature. (c) 1995 John Wiley & Sons, Inc. 相似文献
27.
Antifreeze polypeptides from the Newfoundland ocean pout,Macrozoarces americanus: presence of multiple and compositionally diverse components 总被引:1,自引:0,他引:1
Choy L Hew Don Slaughter Shashikant B. Joshi Garth L. Fletcher V. S. Ananthanarayanan 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1984,155(1):81-88
Summary Eight major antifreeze polypeptides (AFP) were purified from the sera of Newfoundland ocean pout. Except for their approximately identical size (6,000 Dalton), these components were shown to be separate entities by their behaviour on polyacrylamide gel electrophoresis, ion exchange chromatography, gel permeation and reverse phase high performance liquid chromatography. They could also be divided into two cross-reactive, yet distinct, immunological groups. Amino acid analysis demonstrated that ocean pout AFP are different from all of the other antifreezes studied to date. The ocean pout AFP do not contain the abundance of alanine (60 mol%) found in winter flounder and shorthorn sculpin AFP nor the high half-cystine residues (8 mol%) observed in sea raven AFP. It is suggested that ocean pout AFP represent a new type of macromolecular antifreeze.Abbreviations
AFGP
antifreeze glycoprotein(s)
-
AFP
antifreeze polypeptide(s)
-
HPLC
high performance liquid chromatography
-
SDS
sodium dodecyl sulfate
-
PAGE
polyacrylamide gel electrophoresis 相似文献
28.
The NADH-dependent stearoyl CoA desaturase of hepatic microsomes (EC 1.14.99.5) is an enzyme system consisting of cytochrome b5 reductase (EC 1.6.2.2), cytochrome b5, and the terminal desaturase. We have developed a simple method for routine assay of the terminal enzyme based on complementation of the enzyme with chick embryo liver microsomes lacking desaturase activity. Desaturation of [1-14C]stearoyl CoA by the enzyme-microsome mixture is then assayed by thin-layer chromatography of the reaction products and determination of the amount of oleate formed. Microsomes from the livers of starved-refed rats were used as the source of the stearoyl CoA desaturase. The enzyme alone, solubilized and free from cytocrome b5 reductase and cytochrome b5, was unable to catalyze the desaturation of stearoyl CoA. However, after preincubation with chick embryo liver microsomes in the presence of 1% Triton X-100, the enzyme was active. The enzyme activity was linear with time and desaturase protein under the conditions described and depended on the concentrations of Triton X-100 present in the preincubation and the assay. The optimum concentrations of Triton X-100 were 1% for the preincubation and 0.1-0.15% in the assay. The desaturation activity was dependent on NADH and O2, and was inhibited 95% by 1 mM KCN. The use of chick embryo liver microsomes in this method eliminates the need to use purified cytochrome b5 reductase, cytochrome b5, and liposomes for routine assays and greatly reduces the complexities of timing and order of addition encountered in the existing assays. 相似文献
29.
Using dinitrophenylated human lymphocytes and phytohaemagglutinin-stimulated human lymphoblasts as antigens, antibodies were
produced in rabbits. The immunological reactivities of the antisera so produced were tested against various types of leukemic
cells after absorbing the sera with pooled normal leukocytes. Both the sera showed reactivity with all types of leukemic cells
and no specific affinity for lymphoid leukemic cells was seen. This may suggest the presence of some common antigens on all
types of leukemic cells or that dinitrophenylation brings about similar changes on all types of normal leukocytes. 相似文献
30.
The formation of germtubes by twelve clinical isolates of C. albicans was studied in human serum containing per millilitre 103 to 109 organisms as: Staphylococcus pyegene, Escherichia coli, Klebsiella pneumoniae, Lactobacillus acidophilus and Proteus vulgaris. All the five bacteria inhibited formation of germtubes by C. albicans at all concentrations and the percent germtube formed diminished with increasing concentration of the bacteria. Lactobacillus acidophilus inhibited the formation of germtubes maximally followed by Staphylococcus pyogene, Escherichia coli and Klebsiella pneumoniae. Proteus vulgaris in the concentrations of 103 to 107 bacteria per millilitre produced only insignificant inhibition of formation of germtubes by C. albicans. Since germtubes of C. albicans are invasive, it is suggested that inhibition of blastospo-regermtube transformation may be significantly responsible for prevention of infection by C. albicans by coexisting bacterial flora. 相似文献