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151.
Nidhi?P.?ChananaEmail author Vibha?Dhawan Sant?S.?Bhojwani 《Plant Cell, Tissue and Organ Culture》2005,83(2):169-177
Androgenesis is a phenomenon in which microspores are made to bypass the sexual pathway and follow the sporophytic mode of development to generate new plants without the intervention of fertilization under specialized in vitro conditions. Microspore culture provides an ideal system, with a large, relatively uniform population of haploid cells, for use in mutant selection, genetic transformation and in studies on the molecular mechanism of induction of androgenesis and embryogenesis. This paper involves a study on establishing a reproducible and efficient protocol for microspore embryogenesis in various varieties of Brassica juncea. The genotype had a pronounced effect on androgenic response in microspore cultures. The cultivar Rajat exhibited the most response, producing around 3500 embryos/100 buds. The microspores of B. juncea cv. PR-45 from ed plants maintained at a day/night temperature of 10 °C/5 °C form embryos with suspensors with varied morphology. The microspore embryos germinated to produce plants with frequencies. These plants exhibited 52% survival and 74% fertility. 相似文献
152.
Deepak?PremEmail author Subhadra?Singh Padam?Prakash?Gupta Jaivir?Singh Sish?Pal?Singh?Kadyan 《Plant Cell, Tissue and Organ Culture》2005,80(2):209-214
Guar (Cyamopsis tetragonoloba L. Taub) is a drought tolerant and multipurpose grain legume cash crop grown primarily under rainfed conditions in several countries. The effect of various growth regulators and their combinations on a variety of explants, namely the embryo, cotyledons, cotyledonary nodes, shoot tip and hypocotyle, has been studied and an efficient system for callus induction and regeneration from callus has been developed. It was established that Murashige and Skoogs culture medium containing 2,4-dichlorophenoxyacetic acid (10.0M) in combination with 6-benzylaminopurine (5.0M) with embryo or cotyledon explants is most suitable for induction of green and friable morphogenic callus, with a range of 82.5–95% of cultured explants responding to callus induction. Efficient de novo shoot regeneration was achieved by culturing the callus obtained on this medium on Murashige and Skoogs medium containing 1-naphthlenacetic acid (13.0M) in combination with 6-benzylaminopurine (5.0M) with a range of 82.1–88.4% of callus clumps producing 20–25 shoots. In vitro rooting of cultured shoots was obtained on half-salt concentration of Murashige and Skoogs culture medium supplied with indole-3-butyric acid (5.0M) on which 82–90% of cultured shoots produced healthy roots. The in vitro regenerated plants were grown to pod setting and subsequent maturity under greenhouse conditions. 相似文献
153.
Drought Induces Oxidative Stress and Enhances the Activities of Antioxidant Enzymes in Growing Rice Seedlings 总被引:7,自引:0,他引:7
When rice seedlings grown for 10 and 20 days were subjected to in vitro drought stress of −0.5 and −2.0 MPa for 24 h, an increase in the concentration of superoxide anion (O2.−), increased level of lipid peroxidation and a decrease in the concentration of total soluble protein and thiols was observed
in stressed seedlings compared to controls. The concentration of H2O2 as well as ascorbic acid declined with imposition of drought stress, however glutathione (GSH) concentration declined only
under severe drought stress. The activities of total superoxide dismutases (SODs) as well as ascorbate peroxidase (APX) showed
consistent increases with increasing levels of drought stress, however catalase activity declined. Mild drought stressed plants
had higher guaiacol peroxidase (GPX) and chloroplastic ascorbate peroxidase (c-APX) activity than control grown plants but
the activity declined at the higher level of drought stress. The activities of enzymes involved in regeneration of ascorbate
i.e. monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) were higher
in drought stressed plants compared to controls. Results suggest that drought stress induces oxidative stress in rice plants
and that besides SOD, the enzymes of ascorbate-glutathione cycle, which have not been studied in detail earlier under stressful
conditions, appear to function as important component of antioxidative defense system under drought stress. 相似文献
154.
Ohmori K Umeda M Tanaka N Takagi H Yoshimura I Sasaki K Asasda S Sakai A Araki H Asakura M Baba H Fushiwaki Y Hamada S Kitou N Nakamura T Nakamura Y Oishi H Sasaki S Shimada S Tsuchiya T Uno Y Washizuka M Yajima S Yamamoto Y Yamamura E Yatsushiro T;Non-Genotoxic Carcinogen Study Group in the Environmental Mutagen Society of Japan 《Alternatives to laboratory animals : ATLA》2005,33(6):619-639
The Bhas promotion assay is a cell culture transformation assay designed as a sensitive and economical method for detecting the tumour-promoting activities of chemicals. In order to validate the transferability and applicability of this assay, an inter-laboratory collaborative study was conducted with the participation of 14 laboratories. After confirmation that these laboratories could obtain positive results with two tumour promoters, 12-O-tetradecanoylphorbol-13-acetate (TPA) and lithocholic acid (LCA), 12 coded chemicals were assayed. Each chemical was tested in four laboratories. For eight chemicals, all four laboratories obtained consistent results, and for two of the other four chemicals, only one of the four laboratories showed inconsistent results. Thus, the rate of consistency was high. During the study, several issues were raised, each of which were analysed step-by-step, leading to revision of the protocol of the original assay. Among these issues were the importance of careful maintenance of mother cultures and the adoption of test concentrations for toxic chemicals. In addition, it is suggested that three different types of chemicals show positive promoting activity in the assay. Those designated as T-type induced extreme growth enhancement, and included TPA, mezerein, PDD and insulin. LCA and okadaic acid belonged to the L-type category, in which transformed foci were induced at concentrations showing growth-inhibition. In contrast, M-type chemicals, progesterone, catechol and sodium saccharin, induced foci at concentrations with little or slight growth inhibition. The fact that different types of chemicals similarly induce transformed foci in the Bhas promotion assay may provide clues for elucidating mechanisms of tumour promotion. 相似文献
155.
Norepinephrine and dopamine have important role in movement disorders but their role in movement disorders associated with
Japanese encephalitis (JE) has not been evaluated. Therefore, in the present study, cerebrospinal fluid (CSF) catecholamine
levels and its metabolites in JE patients with movement disorders were compared with those without JE. CSF was collected by
lumbar puncture and analyzed by HPLC-ED. Norepinephrine, dopamine and homovanillic acid concentrations were significantly
(P<0.005) lower in JE patients compared to control groups. Low levels of catecholamines in JE associated movement disorders
compared to idiopathic Parkinson’s disease and other extrapyramidal symptoms may be due to severe structural damage to thalamus,
basal ganglia and brainstem in JE patients as revealed by MRI findings. 相似文献
156.
A method for microperfusion of isolated segments of the midgut epithelium of Drosophila larvae has been developed to characterize cellular transport pathways and membrane transporters. Stereological ultrastructural
morphometry shows that this epithelium has unusually long tight junctions, with little or no lateral intercellular volume
normally found in most epithelia. Amplification of the apical and basal aspects of the cells, by ≈ 17-fold and ≈ 7-fold, respectively,
predicts an almost exclusively transcellular transport system for solutes. This correlates with the high lumen-negative transepithelial
potential (Vt) of 38 to 45 mV and high resistance (Rt) of 800 to 1400 Ω • cm2 measured by terminated cable analysis, in contrast to other microperfused epithelia like the renal proximal tubule. Several
blockers (amiloride 10−4 M, ouabain 10−4 M, bumetanide 10−4 M), K+-free solutions, or organic solutes such as D-glucose 10 mM or DL-alanine 0.5 mM failed to affect Vt or Rt. Bafilomycin-A1 (3 to 5 μM) decreased Vt by ≈ 40% and short-circuit current (Isc) by ≈ 50%, and decreased intracellular pH when applied from the basal side only, consistent with an inhibition of an electrogenic
V-H+-ATPase located in the basal membrane. Gradients of H+ were detected by pH microelectrodes close to the basal aspect of the cells or within the basal extracellular labyrinth. The
apical membrane is more conductive than the basal membrane, facilitating secretion of base (presumably HCO3−), driven by the basal V-H+-ATPase. 相似文献
157.
High frequency somatic embryogenesis of Eleutheorcoccus chiisanensis was achieved through suspension culture of embryogenic cells in hormone-free Murashige and Skoog liquid medium supplemented with 30 g sucrose l−1. Cotyledonary somatic embryos were germinated and converted into plantlets using 20 μM gibberellic acid which were then grown in a 10 l airlift bioreactor. HPLC analysis revealed the accumulation of eleutheroside B, E and E1 in the embryos and plantlets. Thus mass production of embryos and plantlets of E. chiisanensis can be achieved in liquid cultures and the biomass produced may become an alternative source of eleutherosides. 相似文献
158.
Arsenic (As) is a potential contaminant of groundwater as well as soil in many parts of the world. The effects of increasing
concentration of As (25 μm and 50 μm As2O3) in the medium on the content of starch and sugars and activity levels of enzymes involved in starch and sugar metabolism
i.e. α-amylase, β-amylase, starch phosphorylase and acid invertase were studied in germinating seeds of two rice cvs. Malviya-36 and Pant-12 during 0–120 h period. As toxicity in situ led to a marked decline in the activities of α-amylase, β-amylase in endosperms as well as embryoaxes of germinating rice
seeds. The activity of acid invertase increased in endosperms as well as embryoaxes whereas starch phosphorylase activity
declined in endosperms but increased in embryoaxes under As treatment. In endosperms a decline in starch mobilization was
observed under As toxicity, however under similar conditions the content of total soluble sugars increased in embryoaxes.
The observed inhibition in activities of amylolytic enzymes might contribute to delayed mobilization of endospermic starch
which could affect germination of seeds in As polluted environment, while the induced acid invertase activity and increased
sugar accumulation in embryoaxes could serve as a possible component for adaptation mechanism of rice seedlings grown under
As containing medium. 相似文献
159.
P.?Baskaran N.?JayabalanEmail author 《In vitro cellular & developmental biology. Plant》2005,41(4):532-539
Summary An efficient rapid and large-scale in vitro clonal propagation of the valuable medicinal herb Eclipta alba (Asteraceae) by enhanced axillary shoot proliferation in cotyledonary node segments was designed. The medium type, various carbon sources,
plant growth regulators, and coconut water markedly influenced in vitro propagation of Eclipta alba. An in vitro plantlet production system has been investigated on Murashige and Skoog (MS) medium with the synergistic combination of benzyladenine
(4.4μM), kinetin (4.6μM), 2-isopentenyladenine (4.9μM), gibberellic acid (1.4μM), 5% coconut water, and 3% sucrose which promoted the maximum number of shoots as well as beneficial shoot length: Subculturing
of cotyledonary node segments on a similar medium enabled continuous production of healthy shoots with similar frequency.
Rooting was highest (94.3%) on full strength. MS medium containing 9.8 μM indolebutyric acid. Micropropagated plants established in garden soil, farmyard soil, and sand (2∶1∶1) were uniform and identical
to the donor plant with respect to growth characteristics as well as floral features. These plants grew normally without showing
any morphological variation. 相似文献
160.
Asha?Jacob Nutan?MalpathakEmail author 《In vitro cellular & developmental biology. Plant》2005,41(3):291-295
Summary Shoot regeneration in hairy root cultures of Solanum khasianum Clarke influences root growth, solasodine production. and permeabilization of solasodine into the medium. These parameters
are dependent on exogenously supplied auxin and cytokinin: the effect being both concentration-and clone-dependent. Hairy
root cultures with no shoot regeneration showed high permeabilization of solasodine into the medium by the sixth week of incubation,
suggesting the medium acts as a sink for the solasodine synthesized by the roots. Solasodine in the culture medium was toxic
to the transformed roots and caused browning of root tips. In a separate set of experiments, the hairy root cultures showed
regeneration of approximately 50–70 mm long shoots after treatment with indole-3-acetic acid and kinetin. These hairy root
cultures had inereased levels of solasodine production, compared to cultures without shoot regeneration. The plantlets formed
in the hairy root cultures accumulated some of the solasodine, thereby reducing its permcabilization into the medium. Transport
of solasodine from root to shoot reduced the toxic effect of solasodine in the root zone and extended the exponential growth
phase by 8-10d. 相似文献