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61.
The flower is the most significant and beautiful part of plants. Flowers are very useful organs in plant developmental phenomenon.
During flower bud opening, various events takes place in a well defined sequence, representing all aspects of plant development,
such as cell division, cellular differentiation, cell elongation or expansion and a wide spectrum of gene expression. The
complexity of flower bud opening illustrates that various biological mechanisms are involved at different stages. Senescence
represents the ultimate stage of floral development and results in wilting or abscission of whole flower or flower parts.
Senescence is an active process and governed by a well defined cell death program. Once a flower bud opens, the programmed
senescence of petal allows the removal of a metabolically active tissue. In leaves, this process can be reversed, but in floral
tissue it cannot, indicating that a highly controlled genetic program for cell death is operating. The termination of a flower
involves at least two, sometimes overlapping, mechanisms. In one, the perianth abscises before the majority of its cells initiate
a cell death program. Abscission may occur before or during the mobilization of food reserves to other parts of the plant.
Alternatively, the petals may be more persistent, so that cell deterioration and food remobilization occur while the petals
are still part of the flower. The overall pattern of floral opening varies widely between plant genera, therefore, a number
of senescence parameters have been used to group plants into somewhat arbitrary categories. Opening and senescence of rose
flower is still an unsolved jigsaw in the world of floriculture industry and the mechanism behind the onset of the very early
events in the sequence still remains to be elucidated. Hence, for advancing the knowledge on the pertinent aspect of bud opening
and senescence the literature has been cited under this review. 相似文献
62.
Pallavi B. Nahar Shuklangi A. Kulkarni Mahesh S. Kulye Santosh B. Chavan Girish Kulkarni Armugham Rajendran 《Biocontrol Science and Technology》2008,18(4):337-355
The effect of repeated conidial sub-culturing of Metarhizium anisopliae on its virulence against Helicoverpa armigera (Hübner) was studied. The LT50 observed against third instar larvae of H. armigera for the first sub-culture was 3.4 days; it increased to 4.5 and 5.6 days for the 20th and the 40th sub-cultures, respectively. The LT50 values after passage of the 40th sub-culture on H. armigera decreased to 4.4 and 3.7 days for the 40th (first in vivo) and the 40th (fifth in vivo) passages, respectively. Similarly, the LC50 of M. anisopliae towards third instar larvae of H. armigera increased from the first sub-culture (0.17×104) to (3.0×104) for the 40th conidial transfers on potato dextrose agar and again decreased to 0.74×104 and 0.23×104 in the 40th (first in vivo) and the 40th (fifth in vivo) passage, respectively. Similar trends for LC50 and LT50 values were seen when sugarcane woolly aphid, Ceratovacuna lanigera Zehntner was used as a host. Significant variation in appressorium formation and cuticle-degrading enzyme production such as chitinase, chitin deacetylase, chitosanase and protease during subsequent sub-culturing and passage through H. armigera was observed. Though there was no effect on internal transcribed spacer (ITS) sequence pattern, interestingly, in randomly amplified polymorphic DNA (RAPD), significant differences in the band intensities and in the banding pattern for different sub-cultures of M. anisopliae were observed. As stable virulence towards the insect pest is desirable for commercialisation of a mycoinsecticide, such changes in virulence due to repeated in vitro transfer need to be monitored and minimised. 相似文献
63.
Shuklangi A. Kulkarni Vandana Ghormade Girish Kulkarni Manisha Kapoor Santosh B. Chavan Armugam Rajendran 《Biocontrol Science and Technology》2008,18(8):809-828
Metarhizium isolates from soil (53) and insect hosts (10) were evaluated for extracellular production of cuticle degrading enzyme (CDE) activities such as chitinase, chitin deacetylase (CDA), chitosanase, protease and lipase. Regression analysis demonstrated the relation of CDE activities with Helicoverpa armigera mortality. On basis of this relation, ten isolates were selected for further evaluation. Subsequently, based on LT50 of the 10 isolates towards H. armigera, five isolates were selected. Out of these five isolates, three were selected on the basis of higher conidia production (60–75 g/kg rice), faster sedimentation time (ST50) (2.3–2.65 h in 0.1% (w/v) Tween 80) and lower LC50 (1.4–5.7×103 conidia/mL) against H. armigera. Finally, three Metarhizium isolates were selected for the molecular fingerprinting using ITS sequencing and RAPD patterning. All three isolates, M34412, M34311 and M81123, showed comparable RAPD patterns with a 935G primer. These were further evaluated for their field performance against H. armigera in a chickpea crop. The percent efficacies with the three Metarhizium isolates were from 65 to 72%, which was comparable to the chemical insecticide, endosulfan (74%). 相似文献
64.
Nitish Kumar Sudheer D. V. N. Pamidimarri Meenakshi Kaur Girish Boricha Muppala P. Reddy 《Biologia》2008,63(3):378-382
Jatropha curcas is an oil bearing species with multiple uses and considerable economic potential as a biofuel crop. The effect of NaCl stress
on growth, ion accumulation, contents of protein, proline, and antioxidant enzymes activity in callus cultures of J. curcas was investigated. Exposure of callus to NaCl decreased growth in a concentration dependent manner. NaCl treated callus accumulated
Na and declined in K, Ca and Mg contents. Na/K ratio increased steadily as a function of external NaCl treatment. NaCl induced
significant differences in quality and quantity of proteins, whereas, proline accumulation remained more or less constant
with treatment. NaCl stress enhanced the activity of superoxide dismutase (SOD; E.C. 1.15.1.1) and peroxidase (POX; E.C. 1.11.1.7).
Further in the isoenzyme studies, four SOD isoenzymes (SOD 1, 2, 3, and 4) and two POX isoenzymes (POX 1 and 2) were detected
with the treatment. NaCl strongly induced activity of SOD 4 isoenzyme in 40, 60, 80 mM and POX 2 isoenzyme in 40 and 80 mM
NaCl concentrations. Increase in antioxidant enzymes activity could be a response to cellular damage induced by NaCl. This
increase could not stop the deleterious effects of NaCl, but it reduced stress severity and thus allowed cell growth to occur. 相似文献
65.
Puthanveetil P Wang F Kewalramani G Kim MS Hosseini-Beheshti E Ng N Lau W Pulinilkunnil T Allard M Abrahani A Rodrigues B 《American journal of physiology. Heart and circulatory physiology》2008,295(4):H1753-H1762
Glycogen is an immediate source of glucose for cardiac tissue to maintain its metabolic homeostasis. However, its excess brings about cardiac structural and physiological impairments. Previously, we have demonstrated that in hearts from dexamethasone (Dex)-treated animals, glycogen accumulation was enhanced. We examined the influence of 5'-AMP-activated protein kinase (AMPK) on glucose entry and glycogen synthase as a means of regulating the accumulation of this stored polysaccharide. After Dex, cardiac tissue had a limited contribution toward the development of whole body insulin resistance. Measurement of glucose transporter 4 (GLUT4) at the plasma membrane revealed an excess presence of this transporter protein at this location. Interestingly, this was accompanied by an increase in GLUT4 in the intracellular membrane fraction, an effect that was well correlated with increased GLUT4 mRNA. Both total and phosphorylated AMPK increased after Dex. Immunoprecipitation of Akt substrate of 160 kDa (AS160) followed by Western blot analysis demonstrated no change in Akt phosphorylation at Ser(473) and Thr(308) in Dex-treated hearts. However, there was a significant increase in AMPK phosphorylation at Thr(172), which correlated well with AS160 phosphorylation. In Dex-treated hearts, there was a considerable reduction in the phosphorylation of glycogen synthase, whereas glycogen synthase kinase-3-beta phosphorylation was augmented. Our data suggest that AMPK-mediated glucose entry combined with the activation of glycogen synthase and a reduction in glucose oxidation (Qi et al., Diabetes 53: 1790-1797, 2004) act together to promote glycogen storage. Should these effects persist chronically in the heart, they may explain the increased morbidity and mortality observed with long-term excesses in endogenous or exogenous glucocorticoids. 相似文献
66.
Enzymic changes in response to zinc nutrition 总被引:1,自引:0,他引:1
Nalini Pandey Girish Chandra Pathak Amit Kumar Singh Chandra Prakash Sharma 《Journal of plant physiology》2002,159(10)
With a view to evaluating the suitability of Zn induced changes in enzyme activities and for assessing Zn nutrient status, black gram (Vigna mungo L. cv. IPU 94) was grown under controlled sand culture at five levels of Zn supply ranging from 0.01 to 10 μmol/L. Leaves of 60 d old plants were examined for Zn concentration and activities of fructose 1,6 biphosphate aldolase, carbonic anhydrase, total superoxide dismutase, Cu-Zn SOD, acid phosphatase and ribonuclease, which have been shown to be activated/inhibited by Zn deficiency. Sub-optimal supply of Zn decreased the activities of FBPAse, CA, total SOD and Cu-Zn SOD and increased the activities of APase and RNAse. Activities of the Zn enzymes CA and Cu-Zn SOD, are highly correlated with Zn supply, and suitable as indicators of Zn nutrient status of plants. Activation of APase and RNAse by other micronutrient deficiencies and stress conditions does not favour their use as indicators of Zn nutrient stress. 相似文献
67.
KR Rupesh PL PremKumar Vasanth V Shiva Kumar Seetharaman S Jayachandran 《BMC microbiology》2002,2(1):5-7
Background
Seeds of the legume plant Lathyrus sativus, which is grown in arid and semi arid tropical regions, contain Diamino Propionic acid (DAP). DAP is a neurotoxin, which, when consumed, causes a disease called Lathyrism. Lathryrism may manifest as Neurolathyrism or Osteolathyrism, in which the nervous system, and bone formation respectively, are affected. DAP ammonia lyase is produced by a few microorganisms such as Salmonella typhi, Salmonella typhimurium and Pseudomonas, and is capable of detoxifying DAP. 相似文献68.
69.
William A. Kronert Girish C. Melkani Anju Melkani Sanford I. Bernstein 《The Journal of biological chemistry》2014,289(18):12779-12790
Intramolecular communication within myosin is essential for its function as motor, but the specific amino acid residue interactions required are unexplored within muscle cells. Using Drosophila melanogaster skeletal muscle myosin, we performed a novel in vivo molecular suppression analysis to define the importance of three relay loop amino acid residues (Ile508, Asn509, and Asp511) in communicating with converter domain residue Arg759. We found that the N509K relay mutation suppressed defects in myosin ATPase, in vitro motility, myofibril stability, and muscle function associated with the R759E converter mutation. Through molecular modeling, we define a mechanism for this interaction and suggest why the I508K and D511K relay mutations fail to suppress R759E. Interestingly, I508K disabled motor function and myofibril assembly, suggesting that productive relay-converter interaction is essential for both processes. We conclude that the putative relay-converter interaction mediated by myosin residues 509 and 759 is critical for the biochemical and biophysical function of skeletal muscle myosin and the normal ultrastructural and mechanical properties of muscle. 相似文献
70.
Girish B. Chhed Helen B. Patrzyc Arvind K. Bhargava Pamela F. Crain Satinder K. Sethi James A. McCloskey 《Nucleosides, nucleotides & nucleic acids》2013,32(3):597-611
Abstract From 24 hour collections of urines of chronic myelogenous leukemia (CML) patients, a novel nucleoside was isolated. It was assigned the structure, 5′-deoxyinosine (I) on the basis of UV, NMR and mass spectrometry and by comparison of the spectral data and HPLC and TLC mobilities with those of the authentic sample. Another nucleoside, 5′-deoxy-5′-methylthioadenosine sulfoxide previously isolated from the urines of immunodeficient children was also found in the urine of a CML patient. Possible origin and significance of both of these nucleosides are discussed. 相似文献