NISCAIR Online Periodicals Repository Collection: IJBB Vol.47(4) [August 2010]

Dietary restriction prevents diabetogenic effect of streptozotocin in mice

Thu, 29 Jul 2010 22:58:59 GMT

Title: Dietary restriction prevents diabetogenic effect of streptozotocin in mice

Authors: Goyary, D; Sharma, R

Abstract: The beneficial role of dietary restriction (DR) was studied in streptozotocin (STZ)-induced diabetes in mice. The DR mice exhibited the lower blood glucose (mg/dl) level as compared to ad libitum (AL) fed ones. After 3 months’ DR, STZ treatment to both AL and DR mice showed significant (p<0.001) elevation of the blood glucose level in AL-fed mice, while a lower level of glucose was maintained in DR-fed mice. The ability of maintaining a low blood glucose level in STZ-treated DR mice indicated that STZ might have been ineffective from its action on beta cells of pancreas by long-term DR. Thus, these findings suggested that DR may be an important tool for preventing the diabetic conditions. However, further studies are required to know the mechanism(s) of DR protection against diabetogenic action of STZ in experimental animals.

Page(s): 254-256

Role of H₂O₂ and cell wall monoamine oxidases in germination of Vigna radiata seeds

Thu, 29 Jul 2010 22:58:59 GMT

Title: Role of H₂O₂ and cell wall monoamine oxidases in germination of Vigna radiata seeds

Authors: Verma, Giti; Sharma, Samir

Abstract: Plant cell wall expresses monoamine oxidases (MAOs) that catalyze oxidation of secreted amines and produce H₂O₂ in the process. The H₂O_2, so produced is used by cell wall peroxidases for lignification of cell wall or for plant defense. The natural substrates for these MAOs are elusive, but polyamines and certain catecholamines have been proposed as candidates. Reactive oxygen species are also known to act as signaling molecules controlling plant metabolism. Mungbean (Vigna radiata) has long served as the plant model of choice while studying molecular programs followed during germination and seed development. In this study, we tested the effect of externally added MAO substrates epinephrine and H₂O₂ on storage protein mobilization in germinating seeds of Vigna radiata. The seeds were imbibed in the presence of 50 M epinephrine and 10 M H₂O₂. These low concentrations of the two compounds were used to exclude direct effects on proteolysis and were arrived at after testing a range of the two and choosing the most effective concentration. These seeds showed 11% and 7% decrease in fresh weight respectively, indicating greater storage mobilization and a corresponding 19% and 46% increase in axis length as compared to untreated seeds. Soluble protein in seeds treated with epinephrine and H₂O₂ decreased significantly by 34% and 33% as compared to untreated seeds. Electrophoretic analysis of seed proteins revealed a startling and selective depletion of storage proteins in treated seeds. The results indicated a clear involvement of H₂O₂ in storage protein mobilization in the cotyledons. We propose that H₂O₂ generated within cell walls of seeds serves as a signaling molecule guiding germination events, including protein reserve mobilization.

Page(s): 249-253

Polygalacturonase inhibitor protein from fruits of anthracnose resistant and susceptible varieties of Chilli (Capsicum annuum L)

Thu, 29 Jul 2010 22:58:59 GMT

Title: Polygalacturonase inhibitor protein from fruits of anthracnose resistant and susceptible varieties of Chilli (Capsicum annuum L)

Authors: Shivashankar, S; Thimmareddy, C; Roy, Tapas K

Abstract: Chilli fruit is highly susceptible to anthracnose infection at the stage of harvest maturity, due to which the fruit yield in the leading commercial variety Byadgi is severely affected. Field studies on screening of several varieties for resistance to anthracnose have shown that a variety of chilli AR-4/99K is resistant to anthracnose infection. In many crops, resistance to fungal attack has been correlated with PGIP activity in developing fruits based on which transgenic varieties have been developed with resistance to fungi. The present study was carried out to determine whether anthracnose resistance in AR-4/99K was due to the increased levels of PGIP alone and/ or due to differences, if any, in the properties of PGIP. Hence, a comparative study of the properties of polygalacturonase inhibitor protein (PGIP) isolated from fruits of anthracnose resistant chilli var AR-4/99K and a susceptible variety Byadgi was conducted with the objective of utilizing the information in genetic transformation studies. Both the PGIPs from anthracnose resistant and susceptible varieties of chilli exhibited similarities in the elution pattern on Sephadex gel, DEAE cellulose, PAGE and SDS-PAGE. The two PGIPs were active over a wide range of pH and temperature. Both PGIPs showed differential inhibitory activity against polygalacturonase (PG) secreted by Colletotrichum gleosporoides, C. capsici, C. lindemuthianum, Fusarium moniliforme and Sclerotium rolfsii. The inhibitory activity of PGIP from both resistant and susceptible varieties was the highest (82% and 76%, respectively) against the PG from Colletotrichum capsici, a pathogen causing anthracnose rot of chilli, while the activity was lower (1.27 to 12.3%) on the other fungal PGs. Although PGIP activity decreased with fruit maturation in both the varieties, the resistant variety maintained a higher activity at 45 days after flowering (DAF) as compared to the susceptible variety which helped it to overcome the infection by anthracnose as against the susceptible variety (Byadgi) in which PGIP activity was drastically reduced at maturity. The molecular mass of PGIP as determined by SDS-PAGE was found to be 37 kDa. N-terminal sequence analysis of the PGIP showed the first six amino acid residues from N-terminal end were Asp-Thr-His-Lys-Ser-Glu (DTHKSE), respectively. The similarities in properties of the two PGIPs support the earlier findings that resistance of AR-4/99K to anthracnose fungus is a result of its higher PGIP activity at maturity.

Page(s): 243-248

Homology modeling and QSAR analysis of 1,3,4-thiadiazole and 1,3,4-triazole derivatives as carbonic anhydrase inhibitors

Thu, 29 Jul 2010 22:58:59 GMT

Title: Homology modeling and QSAR analysis of 1,3,4-thiadiazole and 1,3,4-triazole derivatives as carbonic anhydrase inhibitors

Authors: Akula, N V Murali Krishna; Kumar, Surendra; Singh, Vineet; Tiwari, Meena

Abstract: Carbonic anhydrase (CA) inhibitors are very interesting target for designing anticancer (hypoxic) and antiglaucoma drugs. In the present study, a 3D homology modeling of human carbonic anhydrase-IX (hCA-IX) isozyme, based upon the crystal structure of murine CA-XIVA (PDB CODE 1RJ5) was performed, as no experimental 3D structures are available. A homology model of hCA-IX was developed and validated. To explore the responsible physicochemical properties of 1,3,4-thiadiazole and 1,3,4-triazole derivatives for carbonic anhydrase inhibition, a quantitative structure activity relationship (QSAR) study was performed having hCA-II and hCA-IX inhibitory activity respectively. In hCA-II and hCA-IX inhibitory activities, four significant models with good correlations ( 0.945 & 0.926) were obtained; two models (models 1 and 3) were selected based on statistical criterion. The QSAR study revealed that in case of hCA-II, overall increase in size and volume of molecule, introduction of electropositive surfaces might increase the inhibitory activity, whereas in case of hCA-IX, decreasing the hydrophobicity and introduction of electron releasing substituents might increase the hCA-IX inhibitory activity.

Page(s): 234-242

NISCAIR Online Periodicals Repository Collection: IJBB Vol.47(4) [August 2010]

Dietary restriction prevents diabetogenic effect of streptozotocin in mice

Role of H2O2 and cell wall monoamine oxidases in germination of Vigna radiata seeds

Polygalacturonase inhibitor protein from fruits of anthracnose resistant and susceptible varieties of Chilli (Capsicum annuum L)

Homology modeling and QSAR analysis of 1,3,4-thiadiazole and 1,3,4-triazole derivatives as carbonic anhydrase inhibitors

Role of H₂O₂ and cell wall monoamine oxidases in germination of Vigna radiata seeds