NISCAIR Online Periodicals Repository Collection: IJEB Vol.46(10) [October 2008]

Effect of salinity stress on growth and carbohydrate metabolism in three rice (Oryza sativa L.) cultivars differing in salinity tolerance

Title: Effect of salinity stress on growth and carbohydrate metabolism in three rice (Oryza sativa L.) cultivars differing in salinity tolerance

Authors: Pattanagul, Wattana; Thitisaksakul, Maysaya

Abstract: Rice seedlings cv. Khao Dawk Mali 105 (salt-sensitive), Luang Anan (moderately salt-tolerant) and Pokkali (salt-tolerant) were exposed to 0, 50, 100 and 150 mM NaCl for 9 d. Salinity stress caused reduction in leaf relative water contents in all cultivars. Shoot length of cv. Pokkali was least affected by salinity stress whereas increased root length in response to salinity stress was apparent in cvs. Khao Dawk Mali 105 and Luang Anan. Increased salinity level also caused reduction in fresh and dry weights in cvs. Khao Dawk Mali 105 and Luang Anan, but had no effect in cv. Pokkali except at 150 mM. Accumulation of total soluble sugars and sucrose in mature leaves were observed in cv. Khao Dawk Mali 105 exposed to high level of salinity whereas their concentrations in cvs. Luang Anan and Pokkali remained the same as control plants. Accumulation of sucrose in cv. Khao Dawk Mali 105 was suggested to be resulted from the alteration of photosynthate partitioning since the activities of sucrose phosphate synthase were not affected by salinity in this cultivar. On the contrary, salinity stress induced an accumulation of starch in cv. Pokkali. It is suggested that partitioning sugars into starch may involve in salinity tolerance by avoiding metabolic alterations.

Page(s): 736-742

Cost effectiveness of colony lysis and colony PCR methods for screening of recombinant Escherichia coli colonies ¾ A comparative study

Title: Cost effectiveness of colony lysis and colony PCR methods for screening of recombinant Escherichia coli colonies ¾ A comparative study

Authors: Azhahianambi, P; Ghosh, S; Kumar, C Ashok; Suryanarayana, V V S

Abstract: Economizing the research protocols by using low cost technologies is the need of laboratories of developing world. Screening of recombinant E. coli colonies is the crucial step in gene cloning and expression studies. In the present study, the cost effectiveness of colony lysis method and colony PCR method in the screening of recombinant E. coli colonies was compared. The colony lysis method was 20 two times more cost effective and less time consuming and can be used to screen the recombinant E. coli colonies in large scale instead of colony PCR method.

Page(s): 731-735

Molecular and biochemical evaluation of genetic effect of Calotropis procera (Ait.) latex on Aspergillus terreus (Thom)

Title: Molecular and biochemical evaluation of genetic effect of Calotropis procera (Ait.) latex on Aspergillus terreus (Thom)

Authors: Qari, Sameer H

Abstract: The present study was conducted to observe the genotoxic effect of latex of Calotropis procera. Dense conidial suspensions of Aspergillus terreus Thom were treated with different concentrations of Calotropis latex and assayed for percentage survival, auxotrophic mutants, DNA and total protein contents and further subjected to RAPD and SDS-PAGE tests. It was found that latex of Calotropis procera had potent lethal and mutagenic activities. Percentage survival decreased as concentration or time of exposure increased. Frequency of auxotrophic mutants increased with increase in concentration or exposure time. Most auxotrophic mutants were amino acid requiring mutants. DNA and total protein contents of each mutant was significantly lower than wild type of Aspergillus terreus. RAPD demonstrated polymorphic genetic bands which were the electrophoretic products of PCR for all mutants compared with the wild type strain. SDS-PAGE results expressed a polymorphism of protein bands as well. All these results indicated the mutagenicity of latex of Calotropis procera.

Page(s): 725-730

Concentration of cations in different parts of male reproductive system and their influence on in vitro sperm motility in lizard, Mabuya carinata Schneider.

Title: Concentration of cations in different parts of male reproductive system and their influence on in vitro sperm motility in lizard, Mabuya carinata Schneider.

Authors: Aranha, Ivan; Bhagya, M; Yajurvedi, H N

Abstract: Concentrations of mono- and divalent cations in the testis, three different regions of the epididymis and the vas deferens of lizard, M. carinata were determined. The concentrations of Na⁺,K⁺ and Ca²⁺increased gradually from testis to vas deferens. However, no significant variation in the levels of Mg²⁺ was observed between testis and anterior epididymis, and between posterior epididymis and vas deferens. Further, in an in vitro sperm motility study, wherein different concentrations of the cations were tested, the maximum forward progressive motility of posterior epididymal spermatozoa was observed following treatment with 140 mM NaCl, 25 mM KCl, and 50 mM CaCl₂ whereas, treatment with magnesium brought about a decrease in sperm motility. The results indicate that Na⁺,K⁺, and Ca²⁺ have stimulatory effect at an optimum dose, whereas Mg²⁺ has an inhibitory effect even at very low concentration, on sperm motility in the lizard M. carinata.

Page(s): 720-724