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1.
2.
Fast and slow growing Rhizobium spp. isolated from Cajanus cajan and Cicer arietinum were compared in terms of colony characteristics, utilisation of carbon sources, acid production, symbiotic effectiveness and nodulating competitiveness. Fast growing isolates from C. cajan and C. arietinum formed 3–6 mm diameter colonies on yeast-extract mannitol agar after 4 days and were unlike the slow growers which produced colonies of c. 1 mm diameter after 7–10 days at 28 °C. The fast growing Rhizobium spp. from C. cajan utilised a wider range of carbon sources than the slow growing isolates from this host. Fast and slow growing strains from C. arietinum were able to utilise most of the carbon sources tested suggesting that the slow growers possessed glycolytic pathways similar to those in other fast growing species of Rhizobium. In culture, slow growing isolates from C. cajan produced a near-neutral to alkaline reaction (pH 66·7-5) whereas the fast growers from this host and both fast and slow growing isolates from C. arietinum produced an acidic reaction (pH 4·4–5·6). These data are discussed in the context of Norris' (1965) evolutionary concept of the Leguminosae. Under glassshouse conditions, fast and slow growing strains isolated from C. cajan and C. arietinum were equally effective on their respective hosts. In competition with slow growing rhizobia, half of the fast growers formed more than 70% of the nodules on C. cajan grown in sand. In all but one instance similar results were obtained when plants were grown in soil. With C. arietinum grown in sand or soil, all fast growing isolates from this host formed more than 85% of the nodules in competition with slow growing strains. 相似文献
3.
M. V. NARASIMHA RAO 《The Journal of eukaryotic microbiology》1966,13(4):565-573
SYNOPSIS. During conjugation of Kahlia the micronuclei divide 3 times before synkaryon formation and 2 times thereafter. The 1st division is heterotypic, as in other ciliates, in that it is characterized by the parachute stage. Following this stage, 24 to 26 bivalents and 4 to 8 univalents appear in the micronuclear area. When the bivalents move to organize the metaphase plate, the univalents lag behind and fail to reach the equatorial region at the same time. Due to this irregular behavior of the univalents there is no distinct metaphase in the first meiotic division. A few meiotic irregularities including the breakdown of the spindle apparatus have been observed. During the breakdown of the spindle apparatus the chromosomes fuse into irregular bodies which resemble the chromosome aggregates observed during the somatic divisions. Generally 1, and rarely more, of the products of the 1st division enter the 2nd division. The spindles of this division are oriented parallel to the long axis of the cell, and 1 of the daughter nuclei reaches the partition membrane separating the conjugants. This nucleus alone undergoes the 3rd division, resulting in the formation of gametic nuclei. Reciprocal exchange and fusion of the gametic nuclei result in the synkaryon formation. The synkaryon divides twice in rapid succession resulting in 4 daughter nuclei; 1 of them degenerates and 2 condense and become functional micronuclei. The chromosomes of the remaining daughter nucleus resemble in size and number the bivalents of the 1st meiotic division. They become polytenic and then reproduce to give rise to the polyploid macronucleus. The development of the macronucleus has been traced from a single diploid set of chromosomes and no evidence has been found for the formation of genetic “subnuclei.” During the early stages of the development of the macronuclear anlage, somatic pairing forces keep the homologs together, while in the later stages these forces cease to exert influence. While these changes are in progress the old macronucleus; breaks up into small irregular polymorphic bodies which are scattered throughout in the cytoplasm. The exconjugants usually encyst and the cysts are not favorable for detailed cytologic study. 相似文献
4.
钾营养对水稻光合器功能的效应与谷粒产量的影响 总被引:1,自引:0,他引:1
水稻广陆矮四号和威优35盆栽试验的结果表明,施钾使叶绿体内基粒增多,Hill反应及光合磷酸化活力增强。分蘖末期在叶绿体反应液中添加KCl也可提高非环式光合磷酸化活力。适量施钾降低量子需要量可能与上述效应有关。钾使叶片超微结构改善:乳突大而多;硅化程度明显增加,故叶片更直立。叶水势及净光合率提高,两者呈直线正相关。灌桨期剑叶净光合率与谷粒产量呈直线正相关。 相似文献
5.
γ-氨基丁酸可由谷氨酸脱羧酶(glutamate decarboxylase, GAD)催化谷氨酸一步合成,反应体系成分简单、环境友好。然而,绝大多数GAD酶催化pH偏酸性且反应范围狭小,需要加入无机盐维持最适催化环境,增加了生产附加成分。此外,随着产物γ-氨基丁酸的生成,溶液pH会逐渐上升,不利于GAD酶的持续转化。本研究首先从实验室保藏的一株高产γ-氨基丁酸的植物乳杆菌(Lactobacillus plantarum)中克隆得到谷氨酸脱羧酶LpGAD,基于酶蛋白表面电荷修饰,选择9个位点进行定点突变及组合突变,酶学性质表征结果显示三突变体LpGADS24R/D88R/Y309K在催化pH区间内酶活力整体提高,尤其拓宽了在偏中性pH 6.0下的酶活,为野生酶的1.68倍。接下来,通过分子动力学模拟解析了酶活提高的机理。此外,将Lpgad与LpgadS24R/D88R/Y309K突变基因分别在谷氨酸棒杆菌(Corynebacterium glutamicum) E01中过表达,通过优化确定了摇瓶最适转化条件为反应温度40 ℃,菌体量OD600=20,底物L-谷氨酸100.0 g/L,5-磷酸吡哆醛添加量为100 μmol/L。5 L发酵罐中,不调节pH,通过分批投料底物L-谷氨酸,γ-氨基丁酸产量高达402.8 g/L,较对照菌株提高了1.63倍。本研究成功拓宽了LpGAD的pH催化范围及酶活,提高了γ氨基丁酸的转化效率,为实现其规模化工业生产奠定了基础。 相似文献
6.
为了优化草菇子实体多肽的提取工艺和探究其抗氧化活性,以草菇子实体为原料,采用酶解法提取草菇子实体多肽,通过单因素试验得出最佳的酶解工艺,并使用Box-Behnken设计试验组合。结果表明:草菇子实体提取多肽的最佳工艺为料液比1:52 (g/mL)、加酶量7 200 U/g、酶解温度43 ℃,此工艺条件下的多肽得率为67.76%。从1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除能力、铁离子还原能力、超氧阴离子自由基清除能力和羟自由基清除能力4个方面研究其体外抗氧化能力,结果表明,草菇子实体多肽对DPPH自由基清除率为74.11%,超氧阴离子自由基和羟自由基清除率分别在69.64%和91.83%达到稳定,草菇子实体多肽还具有一定的还原力,说明草菇子实体多肽可以作为优质抗氧化肽的良好来源。该研究为草菇多肽的高效制备和抗氧化肽等高附加值产品的研发提供理论依据。 相似文献
7.
The distribution pattern of 14 C-sucrose from 14 C-sucrose applied to vegetative okra plants and leaves 1–9 on separate plants during the green pod development stage were investigated in relation to duration and leaf position. Results indicated bi-directional transport of assimilates to both apical and basal portions of the stem. Within 48 h 14 C moved to all plant parts; stem and leaves appeared to be strong sinks. In plants fed at the vegetative stage, 48 h after feeding, 66% of the fed activity was exported from the fed leaf. At the pod development stage, about 35% of the activity exported from the fed leaf was present in green pods and 65% in vegetative parts. In plants where leaf 1–9 was fed, irrespective of the position of the fed leaf, the subtending fruit was the strongest sink among the reproductive parts. Leaves and stems were the principal sinks. 相似文献
8.
Approaches to breeding for salinity tolerance - a case study on Porteresia coarctata 总被引:2,自引:0,他引:2
R LATHA C SRINIVAS RAO H M SR SUBRAMANIAM P EGANATHAN M S SWAMINATHAN 《The Annals of applied biology》2004,144(2):177-184
Cereals are the world's major source of food for human nutrition. Among these, rice (Oryza sativa) is the most prominent and represents the staple diet for more than two-fifths (2.4 billion) of the world's population, making it the most important food crop of the developing world (Anon., 2000a). Rice production in vast stretches of coastal areas is hampered due to high soil salinity. This is because rice is a glycophyte and it does not grow well under saline conditions. In order to increase rice production in these areas there is a need to develop rice varieties suited to saline environments. Research has shown that Porteresia coarctata, a highly salt tolerant wild relative of rice growing in estuarine soils, is an important material for transferring salt tolerant characteristics to rice. It is quite possible that Porteresia may be used as a parent for evolving better and truly salt resistant varieties. The inadequate results and the difficulties associated with conventional breeding techniques necessitate the use of the tools of crop biotechnology in unravelling some of the characteristics of Porteresia that have been highlighted in this report. In view of the limited resources available for increasing salinity tolerance to the breeders to wild rice germplasm, Porteresia is undoubtedly one of the key source species for elevating salinity tolerance in cultivated rice. 相似文献
9.
S. RAJA SHANMUKHA RAO N. RAMAYYA 《Botanical journal of the Linnean Society. Linnean Society of London》1977,74(1):47-56
In Hibiscus , stomata are anisocytic, anomocytic, paracytic and tetracytic, the first type being the most frequent and occurring in all plant parts in the ten species studied, whereas the others are scarce and have a limited organographic distribution. The stem, petiole, pedicel, staminal tube, ovary and style are stomatiferous; the leaf-blade, stipule, bracteole and sepals are amphistomatic and petals hypostomatic in the species investigated.
The stomatal types are often homoplastic, the anisocytic being either mesogenous trilabrate or mesoperigenous dolabrate, the anomocytic, mesoperigenous dolabrate or mesogenous trilabrate, and the tetracytic, mesoperigenous dolabrate or mesoperigenous trilabrate. But the typical paracytic stomata (with the subsidiaries completely enclosing the poles) are constantly mesogenous dolabrate and therefore probably indicate mesogenous dolabrate development. Although several patterns of stomatogenesis are encountered in any specific organ, only one of them is found to be dominant. A new subcategory of stomatal ontogeny, mesoperigenous trilabrate, is proposed in Hibiscus. No significant stomatal variation involving reduction in the divisive capacity of the meristemoid has been observed from the vegetative to floral parts; and stomata functioning as hydathodes have not been noticed in the latter, thus indicating that florogenic factors have no effect on the stomata. 相似文献
The stomatal types are often homoplastic, the anisocytic being either mesogenous trilabrate or mesoperigenous dolabrate, the anomocytic, mesoperigenous dolabrate or mesogenous trilabrate, and the tetracytic, mesoperigenous dolabrate or mesoperigenous trilabrate. But the typical paracytic stomata (with the subsidiaries completely enclosing the poles) are constantly mesogenous dolabrate and therefore probably indicate mesogenous dolabrate development. Although several patterns of stomatogenesis are encountered in any specific organ, only one of them is found to be dominant. A new subcategory of stomatal ontogeny, mesoperigenous trilabrate, is proposed in Hibiscus. No significant stomatal variation involving reduction in the divisive capacity of the meristemoid has been observed from the vegetative to floral parts; and stomata functioning as hydathodes have not been noticed in the latter, thus indicating that florogenic factors have no effect on the stomata. 相似文献
10.
Phytochrome mediated induction of nitrate reductase activity in etiolated maize leaves 总被引:1,自引:0,他引:1
L. VIJAYA MOHAN RAO NEERAJ DATTA SUDHIR K. SOPORY SIPRA GUHA-MUKHERJEE 《Physiologia plantarum》1980,50(2):208-212
The effects of red and far-red light on the enhancement of in vitro nitrate reductase activity and on nitrate accumulation in etiolated excised maize leaves were examined. Illumination for 5 min with red light followed by a 4-h dark period caused a marked increase in nitrate reductase activity, whereas a 5-min illumination with far-red light had no effect on the enzyme activity. The effect of red light was completely reversed by a subsequent illumination with the same period of far-red light. Continuous far-red light also enhanced nitrate reductase activity. Both photoreversibility by red and far-red light and the operation of high intensity reaction under continuous far-red light indicated that the induction of nitrate reductase was mediated by phytochrome. Though nitrate accumulation was slightly enhanced by red and continuous far-red light treatments by 17% and 26% respectively, this is unlikely to account for the entire increase of nitrate reductase activity. The far-red light treatments given in water, to leaves preincubated in nitrate, enhanced nitrate reductase activity considerably over the dark control. The presence of a lag phase and inhibition of increase in enzyme activity under continuous far-red light-by tungstate and inhibitors of RNA synthesis and protein synthesis-rules out the possibility of activation of nitrate reductase and suggests de novo synthesis of the enzyme affected by phytochrome. 相似文献