NISCAIR Online Periodicals Repository Collection: IJEB Vol.50(10) [October 2012]

Individual variation in response to simulated hypoxic stress of rats

Title: Individual variation in response to simulated hypoxic stress of rats

Authors: Ghosh, Dishari; Kumar, Rajesh; Pal, Karan

Abstract: With an aim to categorize the animals exposed to simulated hypobaric hypoxia and to evaluate the hormonal profile responsible for individual variation in response to hypoxic stress, degree of tolerance to hypobaric hypoxia was measured by exposing the animals to a simulated altitude of 10,668 m at 32 °C and animals were categorized as low and high tolerant groups based on their gasping time. The hormonal profiles of these groups were evaluated just after exposure to the test. The results showed a distinct individual difference in response to hypoxic tolerance test. There was a significant increase in plasma norepinephrine concentration in high tolerant group than low tolerant rats. After hypoxic tolerance test, total circulating corticosterone (CORT) level also increased but this was not significant in high tolerant rats as compared to low tolerant rats. Corticosteroid binding globulin (CBG) concentration differ significantly between high and low tolerant groups of rats resulting in significant changes in circulating free corticosterone that in turn may be responsible for individual differences in hypoxic gasping time. Significant differences were also observed in prolactin and testosterone levels of both the groups. The results established the method of differentiating the animals according their response to hypoxic tolerance test. These data indicate that multiple components rather than only plasma glucocorticoid of the stress response are providing a basis for individual differences in physiological responses to hypoxic stress.

Page(s): 744-748

High acid invertase activity for a prolonged period in developing seeds/podwall of wild chickpea is detrimental to seed filling

Title: High acid invertase activity for a prolonged period in developing seeds/podwall of wild chickpea is detrimental to seed filling

Authors: Kaur, Harinderjeet; Gupta, Anil Kumar; Kaur, Narinder; Sandhu, Jeet Singh

Abstract: In the present study factors responsible for low seed biomass in wild Cicer species has been investigated. Cicer judaicum and chickpea cultivar PBG-1 were investigated to compare activities of some enzymes involved in carbon metabolism in podwall and seeds during crop development. Seed filling duration in wild species was about 15 days shorter than that of cultivated varieties due to rapid loss of moisture content and hence resulted in earlier maturity and reduced seed biomass. Longer seed filling duration appeared to be an important factor responsible for greater biomass of chickpea seeds. Because of absence of phosphoenol pyruvate carboxylase from 25-35 days after flowering and low sucrose synthase activities, the podwall of C. judaicum is not in a position to contribute significantly to the sink filling capacity of seeds. High acid invertase, low sucrose synthase activities during seed storage phase cause detrimental effect on seed filling and resulting in highly reduced sink strength and productivity of wild species. Successful transfer of stress tolerance from wild Cicer species to chickpea cultivars need to prevent the transfer of these observed unfavourable biochemical factors so that the productivity of chickpea crop remains unaffected during utilization of wild Cicer species in chickpea improvement.

Page(s): 735-743

Protocol for augmented shoot organogenesis in selected variety of soybean [Glycine max L. (Merr.)]

Title: Protocol for augmented shoot organogenesis in selected variety of soybean [Glycine max L. (Merr.)]

Authors: Devi, M K Akitha; Sakthivelu, G; Giridhar, P; Ravishankar, G A

Abstract: Development of a reproducible, versatile and efficient in vitro plant regeneration system is highly warranted for Indian soybean varieties for their mass multiplication in view of their commercial significance. Accordingly a protocol for direct shoot organogenesis in soybean variety JS 335 has been developed. Using cotyledonary node explants significant organogenic responses, mean shoot number and shoot length were observed when these were incubated on MS medium supplemented with 0.89 µM Benzyladenine (BA) and 5 μg/L triacontanol (TRIA) where in 9.3 ± 0.5 shoots were obtained. TRIA at 5 μg /L able to produce 6.8 ± 0.5 shoot buds in presence of 0.98 µM IBA and 0.89 µM BA. Highest mean shoot buds (14.0 ± 0.5 and 9.0 ± 0.5) and mean shoot length (4.6 ± 0.3 and 10.0 ± 0.7) were obtained when cotyledonary node and shoot tip explants were cultured on MS medium containing 0.14 µM gibberellic acid (GA₃), 0.89 µM BA and 5 μg/L TRIA. Moreover, TRIA supported highest mean root number (6.3±0.5) and root length (21.5 ± 0.57 cm). Field survival of in vitro derived plants of TRIA treatment was 70% and the overall growth and seed yield was also significantly better than control plants. This protocol may be used for improving the in vitro regeneration of soybean variety JS 335 for transformation studies.

Page(s): 729-734

Screening, isolation, taxonomy and fermentation of an antibiotic producer Streptomyces xinghaiensis from soil capable of acting against linezolid resistant strains

Title: Screening, isolation, taxonomy and fermentation of an antibiotic producer Streptomyces xinghaiensis from soil capable of acting against linezolid resistant strains

Authors: Kumar, Konda Shravan; Anuradha, Sriramoju; Sarma, Gadepalli Rama; Venkateshwarlu, Yenamandra; Kishan, Veerabrahma

Abstract: Linezolid resistant cultures are emerging in hospitals. In the present study 3 soil actinomycetes were isolated in a screening programme having potential to produce antibiotic against linezolid resistant cases. One culture was coded as RK-46 and further studied. The micromorphology, biochemical tests and 16S ribosomal DNA gene sequence analysis were conducted to know the identity of the culture and was found as a strain of Streptomyces xinghaiensis. The culture produced antibiotic active against five clinical resistant strains. The antibiotic production was tested by cultivating in eleven different media. The fermentation profile was studied in YEME medium supplemented with calcium carbonate. The maximum activity was noticed at 72 h. Antibiotic activity was extracted into ethyl acetate and was subjected to activity guided purification by column chromatography, TLC and HPLC methods. The pure compound was eluted with retention time of 6.8 min and subjected to ¹H, ¹³C NMR and Mass spectral analysis. The acquired data was compared with that in natural products data base, and was found to be a known antibiotic, reductiomycin. The purified compound showed activity against 5 linezolid resistant cultures and on Mycobacterium tuberculosis. This compound is also showing mild anti cancer activity and is biologically permeable as per Lipinksi’s rule.

Page(s): 718-728