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71.
72.
A method for the genetic transformation of several citrus cultivars is described, including cultivars observed to be recalcitrant
to conventional epicotyl-mediated transformation. Embryogenic cell suspension cultures, established from unfertilized ovules
were used as target tissues for Agrobacterium-mediated transformation. Several modifications were made to the culture environment to investigate factors required for efficient
transfer of the T-DNA and the subsequent regeneration of transgenic citrus plants. It was determined that co-cultivation of
citrus cells and Agrobacterium in EME medium supplemented with maltose (EME-M) and 100 μM acetosyringone for 5 days at 25°C was optimum for transformation
of each of the citrus cultivars. Efficient selection was obtained and escapes were prevented when the antibiotic hygromycin
B was used as a selection antibiotic following transformation with an Agrobacterium strain containing hptII in the T-DNA region. Transgenic embryo regeneration and development was enhanced in medium that contained a liquid overlay
consisting of a 1:2 mixture of 0.6 M BH3 and 0.15 M EME-M media. PCR and Southern blot analyses confirmed the presence of
the T-DNA and the stable integration into the genome of regenerated plants, while RT-PCR demonstrated variable amounts of
RNA being transcribed in different transgenic lines. This protocol can create an avenue for insertion of useful traits into
any polyembryonic citrus cultivar that can be established as embryogenic cell suspension cultures, including popular specialty
mandarins and seedless cultivars. 相似文献
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76.
Dutt S Kléber M Matasci M Sommer L Zimmermann DR 《The Journal of biological chemistry》2006,281(17):12123-12131
We previously showed the selective expression of the chondroitin sulfate proteoglycans versican V0 and V1 in barrier tissues that impede the migration of neural crest cells during embryonic trunk development (Landolt, R. M., Vaughan, L., Winterhalter, K. H., and Zimmermann, D. R. (1995) Development 212, 2303-2312). To test for an active involvement of these isoforms in the guidance process, we have now established protocols to isolate intact versican V0 and V1 in quantities sufficient for functional experiments. Using stripe choice assays, we demonstrate that pure preparations of either a mixture of versican V0/V1 or V1 alone strongly inhibit the migration of multipotent Sox10/p75NTR double-positive early neural crest stem cells on fibronectin by interfering with cell-substrate adhesion. We show that this inhibition is largely core glycoprotein-dependent, as the complete removal of the glycosaminoglycan chains has only a minor effect on the inhibitory capacity. Our findings support the notion that versican variants V0 and V1 act, possibly in concert with other inhibitory molecules such as aggrecan and ephrins, in directing the migratory streams of neural crest cells to their appropriate target tissues. 相似文献
77.
Snehlata Chaudhary Ishwar Dutt Vats Madhu Chopra Parbati Biswas Santosh Pasha 《Bioorganic & medicinal chemistry letters》2009,19(15):4364-4366
One of the efficient modes of treatments of chronic hypertension and cardiovascular disorders has been to restrain the formation of angiotensin-II by inhibiting the action of angiotensin-converting enzyme (ACE) on angiotensin-I. The efforts continue towards achieving superior molecules or drugs with improved affinities, better bioavailability and thus to achieve long duration of action with minimum side effects. Previously, we reported a library of tripeptidomimics of Ornithyl–Proline (Orn–Pro) conjugated with various unnatural amino acids and carboxylic acid derived heterocyclics based on the SAR studies of existing ACE inhibitors. Their synthesis and screening for possible inhibitors of angiotensin-converting enzyme (ACE) revealed that increase in the backbone chain length by one carbon atom results in a sudden decrease in their activity. Therefore, in the present study heterocycles with different chain length were introduced to interact with the hydrophobic S2 sub-site of ACE and screened for their in vitro ACE inhibition activity. Further, their binding interaction with C-domain of somatic ACE was also determined. Docking and consequent LUDI scores showed good correlation with binding of these molecules in the active site of ACE. Results suggest that heterocycles with C3 chain length are more appropriate for the effective binding of the tripeptidomimics within the active site of ACE. 相似文献
78.
The present study, carried out to identify stress-modulated calmodulin (CaM)-binding proteins in sorghum, resulted in the isolation of several proteins, which showed binding to CaM-Sepharose matrix. Calmodulin gel overlay assay and MALDI-ToF MS analysis revealed that an 85 kDa protein (Hsp85), which interacted with calmodulin, cross-reacted with anti-N. crassa Hsp80 antibodies. Since these antibodies bind to plant Hsp90, sorghum Hsp85 is likely to be a member of the Hsp90 family. This study provides the first evidence that a member of Hsp90 (Hsp85) in plants exhibits CaM-binding properties. 相似文献
79.
Swarnima Agnihotri Dharm Dutt C. H. Tyagi Alok Kumar J. S. Upadhyaya 《World journal of microbiology & biotechnology》2010,26(8):1349-1359
Fungi producing xylanases are plentiful but alkali-thermo-tolerant fungi producing cellulase-poor xylanase are rare. Out of
12 fungal strains isolated from various sources, Coprinellus disseminatus SW-1 NTCC 1165 yielded the highest xylanase activity (362.1 IU/ml) with minimal cellulase contamination (0.64 IU/ml). The
solid state fermentation was more effective yielding 88.59% higher xylanase activity than that of submerged fermentation.
An incubation period of 7 days at 37°C and pH 6.4 accelerated the xylanase production up to the maximum level. Among various
inexpensive agro-residues used as carbon source, wheat bran induced the maximum xylanase titres (469.45 IU/ml) while soya
bean meal was the best nitrogen source (478.5 IU/ml). A solid substrate to moisture content ratio of 1:3 was suitable for
xylanase production while xylanase titre was repressed with the addition of glucose and lactose. The xylanase and laccase
activities under optimized conditions were 499.60 and 25.5 IU/ml, respectively along with negligible cellulase contamination
(0.86 IU/ml). Biochemical characterization revealed that optimal xylanase activity was observed at pH 6.4 and temperature
55°C and xylanase is active up to pH 9 (40.33 IU/ml) and temperature 85°C (48.81 IU/ml). SDS–PAGE and zymogram analysis indicated
that molecular weight of alkali-thermo-tolerant xylanase produced by C. disseminatus SW-1 NTCC 1165 was 43 kDa. 相似文献
80.
P. Rama Chandra Prasad K. S. Rajan C. B. S. Dutt P. S. Roy 《Biodiversity and Conservation》2010,19(11):3073-3087
Phytodiversity is affected both by natural and anthropogenic factors and in Island ecosystems these impacts can devastate
or reduce diversity, if the native vegetation is lost. In addition to rich species richness and diversity, Island systems
are the sites of high endemism and any threat to these ecosystems will consequently lead to loss and extinction of species.
To understand the dynamics including feedbacks of these changes in phytodiversity of North Andaman Islands, a conceptual framework
is proposed which focuses on understanding the land-use and land-cover changes and its impact with phytodiversity. In considering
land-use and land-cover changes this work highlights the direct and indirect drivers of changes—socio-economic, biophysical
and climatic factors. Migration of population, their socio economic needs and government policies were identified as major
driving forces threatening the phytodiversity of these Islands. Apart from human beings, natural disasters like tsunami and
introduced herbivorous animals like elephants also contributed to forest destruction in these Islands. The integrated analysis
based on such framework will provide insights for holistic resource management including ecological conservation. 相似文献