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51.
Subhra Prakash Chakrabarty Hemalatha Balaram 《Biochimica et Biophysica Acta - Proteins and Proteomics》2010,1804(9):1743-1750
Reversible zinc chelation via thiol groups of cysteines leading to modulation of activity in redox regulated proteins forms a basis for switching on–off of various biochemical processes. Silent information regulator 2 (Sir2), a NAD+ dependent deacetylase, contains a non-catalytic zinc ion coordinated by thiol groups of cysteines. Using Plasmodium falciparum Sir2 (PfSir2), we have examined the effect of zinc removal on the structure and activity of this enzyme. Our studies show that the enzyme with high affinity for zinc exhibits partial collapse of structure upon removal of the metal ion. Zinc reconstitution of apo PfSir2 led to recovery of both structure and activity highlighting the reversibility of the process. 相似文献
52.
Y. H. Dewir D. Chakrabarty S. -H. Lee E. -J. Hahn K. -Y. Paek 《Biologia Plantarum》2010,54(2):357-360
The present study reports an efficient protocol for indirect shoot organogenesis and plantlets regeneration of Withania somnifera (L.) Dunal. Leaf explants were cultured on Murashige and Skoog (MS) medium supplemented with different concentrations and
combinations of 6-benzylaminopurine (BAP) and indole-3-acetic acid (IAA). The highest callus induction rate (89.5 %) and shoot
regeneration rate (92 %) were obtained when 2 mg dm−3 BAP was combined with 0.5 mg dm−3 IAA. Three major withanolides (withaferine A, 12-deoxywithastramonolide and withanolide A) were investigated in different
plant organs from in vitro and greenhouse grown plants. Leaves contained higher contents of withanolides and phenolics than roots or stems, whereas
roots contained the highest contents of flavonoids and polysacharides. In vitro grown plants contained greater contents of phenolics, flavonoids and polysaccharides while lower contents of withanolides
than greenhouse grown plants. 相似文献
53.
Six parent and their 12 gamma ray-induced somatic flower colour mutants of garden rose were characterized to discriminate
the mutants from their respective parents and understanding the genetic diversity using Random amplification of polymorphic
DNA (RAPD) markers. Out of 20 primers screened, 14 primers yielded completely identical fragments patterns. The other 7 primers
gave highly polymorphic banding patterns among the radiomutants. All the cultivars were identified by using only 7 primers.
Moreover, individual mutants were also distinguished by unique RAPD marker bands. Based on the presence or absence of the
48 polymorphic bands, the genetic variations within and among the 18 cultivars were measured. Genetic distance between all
18 cultivars varied from 0.40 to 0.91, as revealed by Jaccard’s coefficient matrix. A dendrogram was constructed based on
the similarity matrix using the Neighbor Joining Tree method showed three main clusters. The present RAPD analysis can be
used not only for estimating genetic diversity present in gamma ray-induced mutants but also for correct identification of
mutant/new varieties for their legal protection under plant variety rights. 相似文献
54.
Sanjay Dwivedi R. D. Tripathi Sudhakar Srivastava Ragini Singh Amit Kumar Preeti Tripathi Richa Dave U. N. Rai Debasis Chakrabarty P. K. Trivedi R. Tuli B. Adhikari M. K. Bag 《Protoplasma》2010,245(1-4):113-124
The exposure of paddy fields to arsenic (As) through groundwater irrigation is a serious concern that may not only lead to As accumulation to unacceptable levels but also interfere with mineral nutrients in rice grains. In the present field study, profiling of the mineral nutrients (iron (Fe), phosphorous, zinc, and selenium (Se)) was done in various rice genotypes with respect to As accumulation. A significant genotypic variation was observed in elemental retention on root Fe plaque and their accumulation in various plant parts including grains, specific As uptake (29–167 mg kg?1 dw), as well as As transfer factor (4–45%). Grains retained the least level of As (0.7–3%) with inorganic As species being the dominant forms, while organic As species, viz., dimethylarsinic acid and monomethylarsonic acid, were non-detectable. In all tested varieties, the level of Se was low (0.05–0.12 mg kg?1 dw), whereas that of As was high (0.4–1.68 mg kg?1 dw), considering their safe/recommended daily intake limits, which may not warrant their human consumption. Hence, their utilization may increase the risk of arsenicosis, when grown in As-contaminated areas. 相似文献
55.
Saxena AK Rao J Chakrabarty R Saxena M Srimal RC 《Bioorganic & medicinal chemistry letters》2007,17(6):1708-1712
A series of 1-[3-(4-substituted phenylthio) propyl]-4-(substituted phenyl) piperazines has been synthesized and evaluated for hypotensive activity. The QSAR studies indicate that resonance and hydrophobic parameters of the aryl substituents are important for hypotensive activity. The similar role of resonance parameter in describing the variance of 5-HT(2A) receptor binding affinities of these compounds suggests a possible role of 5-HT(2A) receptors in mediating the hypotensive action of title compounds. 相似文献
56.
Beyond host-pathogen interactions: microbial defense strategy in the host environment 总被引:1,自引:0,他引:1
Fialho AM Stevens FJ Das Gupta TK Chakrabarty AM 《Current opinion in biotechnology》2007,18(3):279-286
Many extracellular pathogenic bacteria colonize human or animal bodies through evasion of the host immune system, a process called host-pathogen interaction. What happens when other intruders try to invade the same host and try to establish themselves in the same niche is largely unknown. In one well-studied case, Pseudomonas aeruginosa is known to secrete the protein azurin as a weapon against such invaders as cancers, parasites and viruses. The production of such weapons by pathogenic bacteria could provide important insights into how a pathogen responds in the post-colonization state to impede other intruders for its own survival. Moreover, these molecules might find use in the pharmaceutical industry as next-generation therapeutics. 相似文献
57.
58.
Temporal development of roots is key to the understanding of root system architecture of plants which influences nutrient uptake, anchorage and plant competition. Using time lapse imaging we analyzed developmental patterns of length, growth angle, depth and curvature of Phaseolus basal roots from emergence till 48 h in two genotypes, and TLP19 with contrasting growth angles. In both genotypes all basal roots appeared almost simultaneously, but their growth rates varied which accounted for differences in root length. The growth angles of the basal roots fluctuated rapidly during initial development due to oscillatory root growth causing local bends. Beyond 24 h, as the root curvature stabilized, so did the growth angle. Therefore growth angle of basal roots is not a very reliable quantity for characterizing root architecture, especially during early seedling development. Comparatively, tip depth is a more robust measure of vertical distribution of the basal roots even during early seedling development.Key words: B98311basal root, kinematics, root architecture, root growth, spatiotemporal analysis, root imagingVertical and horizontal placements of the roots in the soil influence plant performance through acquisition of below ground resources like water and nutrients, plant anchorage and intra- and inter-plant competition.1–4 Therefore the architecture of the root system plays important roles in regulating plant growth and yield, especially under abiotic stresses.5 As a seedling grows to become a mature plant, the root architecture develops continuously in response to various cues e.g., genotypic, environmental, hormonal, etc. Therefore studies of root architecture of plants of different ages are important for understanding the influence of these cues in regulating plant growth.The root scaffold of a plant is comprised of different types of roots with different functions. A mature common bean (Phaseolus vulgaris L.) plant has root system consisting of primary, adventitious, lateral and basal roots. Among these, the basal roots are typically the earliest emerging secondary roots from the hypocotyl6 forming a major part of the mature root system. We have recently demonstrated important differences in architectural traits of the basal roots of common bean in the early seedling stage between two contrasting class of genotypes and how auxin-ethylene interplay regulates these traits.7 While this study of basal roots at a fixed time allows assessment and comparison of root development up to that point of time, investigation of the temporal events of emergence and growth of the basal roots is important and complementary to the understanding of their architectural traits. Therefore in the present study, we examined the detailed developmental patterns of basal roots through time lapse imaging in two genotypes.We chose two bean genotypes with contrasting basal root growth angles (BRGA) relative to the gravity— producing basal roots of smaller BRGA (41.7° ± 14°) and TLP19 having roots of larger BRGA (56.4° ± 18°). B983118 The germinated seedling with 2–3 cm radical was transferred to the blue germination paper (Anchor Paper Co., St. Paul, MN), which was suspended in nutrient solution7 inside a growth chamber (ACMAS Technocracy Limited, Delhi, India) maintained at 25 ± 1°C. Time lapse photography was carried out for 48 h at 30 min intervals using Nikon D200 digital camera fitted with a macro lens to obtain high resolution digital images of the roots. Imaging started from the visibility of the protrusions of emerging basal root along the root-shoot interface. A computer program was developed in Matlab® 7.8 (Mathworks, Natick) to analyze the images semi-automatically. From every image the computer program identified the basal roots using contrast of color between the roots (mostly white) and the germination paper (blue). Root midlines were determined following the methodology of Miller et al.9 and smoothed using the method of overlapping polynomials. Length of the midline is root length. The angle between gravity and the line connecting the root tip to the base is BRGA.7 The vertical distance of the root tip from the base of the lowest emerging root along the gravity vector is tip depth. From the midline, root curvature was also determined using the equation
(1)
where [x(x), y(s)] is coordinate of any point along the root midline, s is normalized distance along the midline, and the primes denote derivatives with respect to s. Here positive curvature signifies bending upward and vice versa. 相似文献
59.
Proline switches, controlled by cis-trans isomerization, have emerged as a particularly effective regulatory mechanism in a wide range of biological processes. Here we report the structures of both the cis and trans conformers of a proline switch in the Crk signaling protein. Proline isomerization toggles Crk between two conformations: an autoinhibitory conformation, stabilized by the intramolecular association of two tandem SH3 domains in the cis form, and an uninhibited, activated conformation promoted by the trans form. In addition to acting as a structural switch, the heterogeneous proline recruits cyclophilin A, which accelerates the interconversion rate between the isomers, thereby regulating the kinetics of Crk activation. The data provide atomic insight into the mechanisms that underpin the functionality of this binary switch and elucidate its remarkable efficiency. The results also reveal new SH3 binding surfaces, highlighting the binding versatility and expanding the noncanonical ligand repertoire of this important signaling domain. 相似文献
60.
Y.H.?Dewir D.?Chakrabarty M.B.?Ali E.J.?Hahn K.Y.?PaekEmail author 《Plant Growth Regulation》2005,46(3):241-251
In vitro regenerated shoots of Spathiphyllum from bioreactor were hydroponically cultured for 30 days. The response of plant growth and photosynthesis to different substrates,
photosynthetic photon flux (PPF), nutrient scheduling and electrical conductivity (EC) of hydroponic solution were studied.
The best plant growth response was observed in perlite based substrates with moderate PFF (70–100μmol m−2 s−1). Highest fresh weight, dry weight, shoot length, root length, root number and photosynthetic characteristics (chlorophyll,
carotenoids and Fv/Fm) was observed in continuous immersion system. Plant growth responses, photosynthetic rate, stomatal
conductance and transpiration rate were also found to be affected by EC levels. The optimum EC of a balanced nutrient solution
was recorded as 1.2 dS m−1. Photosynthetic activity was also characterized in terms of photochemical efficiency using measurements of chlorophyll fluorescence.
Fv/Fm (it is a measure of the intrinsic or maximum efficiency of PSII i.e. the quantum efficiency if all PSII centers were
open) also decreased significantly in plants grown under higher EC level; a decrease in this parameter indicates down regulation
of photosynthesis or photoinhibition. Antioxidant defense enzymes such as catalase (CAT), ascorbate peroxidase (APX), peroxidase
(POD), glutathione reductase (GR) and monodehydroascorbate reductase (MDHAR) significantly elevated in the leaves and roots
of plantlets at higher EC levels. This increase could reflect a defense response to the cellular damage provoked by higher
EC levels in the nutrient solution. 相似文献