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31.
In vitro asymbiotic seed germination of Dendrobium nobile varied significantly with fruit harvesting time and growth medium used for culturing seeds. Seeds harvested 129 days after
pollination (DAP) possessing globular shaped embryos and a discontinuous cuticle layer showed a substantially greater germination
on P668 medium. Alternatively, immature seeds harvested 96 and 116 DAP displayed a significantly lower germination response
on various growth media. Most of the ovules at 96 DAP are in archesporial and megaspore mother cell stages, whereas the majority
of ovules are mature and fertilized at 116 DAP. Mature seeds harvested 158 DAP also germinated at a higher frequency at Stage
5 (emergence of the first leaf) after 8 weeks of culture on different growth media indicating the absence of testa imposed
dormancy in this endangered epiphytic orchid. 相似文献
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Background
Allelopathic functions of plant-released chemicals are often studied through growth bioassays assuming that these chemicals will directly impact plant growth. This overlooks the role of soil factors in mediating allelopathic activities of chemicals, particularly non-volatiles. Here we examined the allelopathic potential of 8-hydroxyquinoline (HQ), a chemical reported to be exuded from the roots of Centaurea diffusa.Methodology/Principal Findings
Growth bioassays and HQ recovery experiments were performed in HQ-treated soils (non-sterile, sterile, organic matter-enriched and glucose-amended) and untreated control soil. Root growth of either Brassica campestris or Phalaris minor was not affected in HQ-treated non-sterile soil. Soil modifications (organic matter and glucose amendments) could not enhance the recovery of HQ in soil, which further supports the observation that HQ is not likely to be an allelopathic compound. Hydroxyquinoline-treated soil had lower values for the CO2 release compared to untreated non-sterile soil. Soil sterilization significantly influenced the organic matter content, PO4-P and total organic nitrogen levels.Conclusion/Significance
Here, we concluded that evaluation of the effect of a chemical on plant growth is not enough in evaluating the ecological role of a chemical in plant-plant interactions. Interaction of the chemical with soil factors largely determines the impact of HQ on plant growth. 相似文献33.
Vinayakam Kalaivani Upendra Kumar Kagola Parnandi Venkata Rajeswari Shaik Kaleemulla Ravipati Praveena Navoori Vijaya 《Luminescence》2024,39(2):e4636
Tin oxide (SnO2) nanocrystalline powders doped with erbium ion (Er3+) in different molar ratios (0, 3, 5, and 7 mol%) were prepared using a solid-state reaction technique. These samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible absorption, visible upconversion, and near-infrared luminescence techniques. XRD analysis revealed the tetragonal rutile structure of SnO2 and the average crystallite size was about 32 nm. From Tauc's plots, it was confirmed that the substitution of Er3+ ions into the SnO2 host lattice resulted in the narrowing its band gap. Optical absorption bands at 520 and 654 nm correspond to the 4f electron transitions of Er3+ further confirming visible light absorption. Infrared luminescence spectra showed a broad band centred at 1536 nm which is assigned to the 4I13/2 → 4I15/2 transition of Er3+. Visible upconverted emission spectra under 980 nm excitation exhibit a strong red luminescence with a main peak at 672 nm which is attributed to the 4F9/2 → 4I15/2 transition of Er3+. Power-dependent upconversion spectra confirmed that two photons participated in the upconversion mechanism. Enhancement in the intensities of both visible and infrared luminescence was observed when raising the concentration. The results pave the way for the potential applications of these nanocrystalline powders in energy harvesting applications such as infrared light upconverting layer in solar cells, light emitting diodes, infrared broadband sources and amplifiers, and biological labelling. 相似文献
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A mammalian ortholog of Saccharomyces cerevisiae Vac14 that associates with and up-regulates PIKfyve phosphoinositide 5-kinase activity
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Sbrissa D Ikonomov OC Strakova J Dondapati R Mlak K Deeb R Silver R Shisheva A 《Molecular and cellular biology》2004,24(23):10437-10447
Multivesicular body morphology and size are controlled in part by PtdIns(3,5)P(2), produced in mammalian cells by PIKfyve-directed phosphorylation of PtdIns(3)P. Here we identify human Vac14 (hVac14), an evolutionarily conserved protein, present in all eukaryotes but studied principally in yeast thus far, as a novel positive regulator of PIKfyve enzymatic activity. In mammalian cells and tissues, Vac14 is a low-abundance 82-kDa protein, but its endogenous levels could be up-regulated upon ectopic expression of hVac14. PIKfyve and hVac14 largely cofractionated, populated similar intracellular locales, and physically associated. A small-interfering RNA-directed gene-silencing approach to selectively eliminate endogenous hVac14 rendered HEK293 cells susceptible to morphological alterations similar to those observed upon expression of PIKfyve mutants deficient in PtdIns(3,5)P(2) production. Largely decreased in vitro PIKfyve kinase activity and unaltered PIKfyve protein levels were detected under these conditions. Conversely, ectopic expression of hVac14 increased the intrinsic PIKfyve lipid kinase activity. Concordantly, intracellular PtdIns(3)P-to-PtdIns(3,5)P(2) conversion was perturbed by hVac14 depletion and was elevated upon ectopic expression of hVac14. These data demonstrate a major role of the PIKfyve-associated hVac14 protein in activating PIKfyve and thereby regulating PtdIns(3,5)P(2) synthesis and endomembrane homeostasis in mammalian cells. 相似文献
35.
Management of root lesion nematode, Pratylenchus delattrei in crossandra using oil cakes 总被引:1,自引:0,他引:1
Selected oil cakes, neem, castor and mahua, were tried independently and in combination with a chemical nematicide (carbofuran 3G) for the management of Pratylenchus delattrei in crossandra under glass house conditions. The neem oil cake was effective compared to other oil cakes used and there was a synergistic effect when the neemcake was coupled with carbofuran 3G in the management of Pratylenchus delattrei. The treatment resulted in better establishment of seedlings, and with increased plant bio-mass and flower yield. 相似文献
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Beinker P Schlee S Auvula R Reinstein J 《The Journal of biological chemistry》2005,280(45):37965-37973
ClpB cooperates with the DnaK chaperone system in the reactivation of protein from aggregates and is a member of the ATPases associated with a variety of cellular activities (AAA+) protein family. The underlying disaggregation reaction is dependent on ATP hydrolysis at both AAA cassettes of ClpB but the role of each AAA cassette in the reaction cycle is largely unknown. Here we analyze the activity of the separately expressed and purified nucleotide binding domains of ClpB from Thermus thermophilus. The two fragments show different biochemical properties: the first construct is inactive in ATPase activity assays and binds nucleotides weakly, the second construct has a very high ATPase activity and interacts tightly with nucleotides. Both individual fragments have lost their chaperone function and are not able to form large oligomers. When combined in solution, however, the two fragments form a stable heterodimer with oligomerization capacities equivalent to wild-type ClpB. This non-covalent complex regains activity in reactivating protein aggregates in cooperation with the DnaK chaperone system. Upon complex formation the ATPase activity of fragment 2 is reduced to a level similar to wild-type ClpB. Hence functional ClpB can be reassembled from its isolated AAA cassettes showing that covalent linkage of these domains is not a prerequisite for the chaperone activity. The observation that the intrinsically high ATPase activity of AAA2 is suppressed by AAA1 allows a hypothetical assignment of their mechanistic function. Whereas the energy gained upon ATP hydrolysis at the AAA2 is likely to drive a conformational change of the structure of ClpB, AAA1 might function as a regulator of the chaperone cycle. 相似文献
39.
Cyclodextrins in drug delivery: An updated review 总被引:2,自引:0,他引:2
The purpose of this review is to discuss and summarize some of the interesting findings and applications of cyclodextrins
(CDs) and their derivatives in different areas of drug delivery, particularly in protein and peptide drug delivery and gene
delivery. The article highlights important CD applications in the design of various novel delivery systems like liposomes,
microspheres, microcapsules, and nanoparticles. In addition to their well-known effects on drug solubility and dissolution,
bioavailability, safety, and stability, their use as excipients in drug formulation are also discussed in this article. The
article also focuses on various factors influencing inclusion complex formation because an understanding of the same is necessary
for proper handling of these versatile materials. Some important considerations in selecting CDs in drug formulation such
as their commercial availability, regulatory status, and patent status are also summarized. CDs, because of their continuing
ability to find several novel applications in drug delivery, are expected to solve many problems associated with the delivery
of different novel drugs through different delivery routes.
Published: October 14, 2005 相似文献
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