Abstract

The planet earth, on which we live in communities, is being increasingly 'ruptured' because of human activities; its carrying capacity is under great stress because of demographic pressures. The pressure is especially affecting the people living in the dry areas because of the marginal and fragile nature of the resources they have access to. There are over 2,000 million hectares of land that have been degraded, with a loss of agrobiodiversity, increased water scarcity and increased natural resource destruction. Superimposed on this is the fact that the neglectful and exploitive use of natural resources has set the train of global climate change in motion.

It is anticipated that the impact of climate change will cut across all boundaries. Crops, cropping systems, rotations and biota will undergo transformation. To maintain the balance in the system, there is a need for new knowledge, alternative policies and institutional changes. The marginalized people in dry areas are likely to be most seriously hit by the shifts in moisture and temperature regimes as a result of the global climate change. To help them cope with the challenges, there is a need for a new paradigm in agricultural research and technology transfer that makes full use of modern science and technology in conjunction with traditional knowledge. This necessitates more investment by international agencies and national governments for supporting the relevant integrated research and sustainable development efforts, with full participation of the target communities. Only such an approach can enable the vulnerable communities of the dryland areas to use the natural resources in a sustainable manner and thus help protect the environment for future generations.

The clock is ticking and the future of the world lies in the collective responsibility and wisdom of all nations on this planet. This should be reflected in the endorsement of a solid future plan.

The potato tuber moth, Phthorimaea operculella (Zeller), in tropical and subtropical countries, is the most destructive pest of potato, Solanum tuberosum L. The larvae attack foliage and tubers in the field and in storage. The purpose of this study was to evaluate the efficacy of a Bt-cry5 transgene to control the potato tuber moth in tuber tissues. Tuber bioassays using stored (11-12 mo old) and newly harvested tubers of Bt-cry5-Lemhi Russet and Bt-cry5-Atlantic potato lines showed up to 100% mortality of 1st instars. Mortality was lowest in the newly harvested tubers of Bt-cry5-Atlantic lines (47.1-67.6%). Potato tuber moth mortality was 100% in the Bt-cry5-Spunta lines that were transformed with Bt-cry5 gene controlled by the CaMV 35S promoter (pBIML5 vector) and in 2 of 3 lines transformed with Bt-cry5 gene controlled by the Gelvin super promoter (pBIML1 vector). The transgenic Spunta lines expressing Bt-cry5 controlled by the patatin promoter (pBMIL2 vector) showed the lowest tuber moth mortality (25.6 and 31.1%). The Bt-cry5 transgenic lines with high tuber expression of B. thuringiensis have value in an integrated pest management system to control potato tuber moth.

Bacteria commonly adapt to increases in the osmolarity of the environment by the intracellular accumulation of small organic solutes (osmolytes) that function by restoring turgor. We have investigated the mechanism of osmotic regulation in Rhizobium meliloti, the root nodule symbiont of alfalfa. As a soil microbe, this organism is subjected to variable osmolarity and a number of other environmental conditions to which it must respond appropriately. Natural abundance I3C nuclear magnetic resonance spectroscopy was used to identify the osmolytes accumulated by osmotically stressed R. meliloti. The complement of osmolytes and their concentrations were found to depend on the level of osmotic stress, growth phase of the culture, carbon source, and the presence of osmolytes in the growth medium. The osmolytes accumulated by 22 different bacterial strains are presented and compared to those of R . meliloti 102F34. o

We have investigated the mechanism of osmotic stress adaptation (osmoregulation) in Agrobacterium tumefaciens biotype I (salt-tolerant) and biotype II (salt-sensitive) strains. Using natural-abundance 13C nuclear magnetic resonance spectroscopy, we identified all organic solutes that accumulated to significant levels in osmotically stressed cultures. When stressed, biotype I strains (C58, NT1, and A348) accumulated glutamate and a novel disaccharide, P-fructofuranosyl-ft-mannopyranoside, commonly known as mannosucrose. In the salt-sensitive biotype II strain K84, glutamate was observed but mannosucrose was not. We speculate that mannosucrose confers the extra osmotic tolerance observed in the biotype I strains. In addition to identifying the osmoregulated solutes that this species synthesizes, we investigated the ability of A. tumefaciens to utilize the powerful osmotic stress protectant glycine betaine when it is supplied in the medium. Results from growth experiments, nuclear magnetic resonance spectroscopy, and a 14C labeling experiment demonstrated that in the absence of osmotic stress, glycine betaine was metabolized, while in stressed cultures, glycine betaine accumulated intracellularly and conferred enhanced osmotic stress tolerance. Furthermore, when glycine betaine was taken up in stressed cells, its accumulation caused the intracellular concentration of mannosucrose to drop significantly. The possible role of osmoregulation of A. tumefaciens in the transformation of plants is discussed.Much attention has been focused on the soil phytopathogen Agrobacterium tumefaciens because of its ability to genetically transform plant cells. The process of transformation, which results in crown gall disease in dicotyledonous plants, involves the transfer of a piece of DNA from the tumor-inducing (Ti) plasmid of the pathogen to the plant (19,28). Although most reports are concerned with the genetic mechanism of the transformation process, there has been some recent interest in the relationship of the physiology of the pathogen to its virulence. For example, it has been shown that the induction of the virulence (vir) genes on the Ti plasmid by the plant signal molecule, acetosyringone, is enhanced by other environmental factors, such as low pH and the presence of glycine betaine in the induction medium (25). That glycine betaine may play a role in the transformation process is intriguing to us since this compound also plays a key role in microbial osmotic stress adaptation, the focus of our research.A common mechanism of osmotic stress adaptation in bacteria is the rapid intracellular accumulation of organic compounds (osmolytes), which results in the restoration of turgor (27). One of the best-known osmolytes is glycine betaine (6,15,27). In the enteric bacteria Escherichia coli, Salmonella typhimurium, and Klebsiella pneumoniae, glycine betaine is taken up from the medium and enhances the growth of osmotically stressed cultures 4-to 7-fold (14). Some species have the ability to synthesize glycine betaine and need n...

Background: Norfloxacin is the most commonly used agent for the prophylaxis against spontaneous bacterial peritonitis (SBP) in patients with liver cirrhosis. Rifaximin, another broad spectrum antibiotic, is used for the treatment of traveler's diarrhea and hepatic encephalopathy. Objective: We aimed to test the efficacy of rifaximin versus norfloxacin for prevention of SBP in patients with hepatitis C virus (HCV)-related liver cirrhosis. Patients and methods: 86 patients with HCV-related liver cirrhosis and ascites were enrolled and divided into two groups of matching age, sex and Child-Pugh class. Group I was given norfloxacin 400 mg/day as single dose, and group II rifaximin 1200 mg/day in three divided doses. They were followed for up to one year. Study endpoints were SBP, hepatocellular carcinoma, compliance failure, death, or liver transplantation. Results: More than 70% of patients received the antimicrobial as primary prophylaxis and the rest were given secondary prophylaxis against SBP. The mean follow-up period was 10.16 ± 2.64 months for norfloxacin and 10.26 ± 2.32 months for rifaximin (p = 0.863). Although statistically insignificant (p = 0.265), patients on rifaximin developed fewer episodes of SBP than those on norfloxacin (4.7% vs. 14%). Also, the infection-free duration before SBP was longer (p = 0.129) with rifaximin than norfloxacin (9.5 vs. 5.0 months). Rifaximin significantly reduced the rate of new compared to past episodes of SBP by 20.9% (p = 0.007) vs. 13.9% for norfloxacin (p = 0.112). Overall survival was equal in both groups. Patients adhered to therapy regimen of norfloxacin for significantly longer time than rifaximin (p = 0.010). Conclusion: Rifaximin is -at least -as good as norfloxacin. It seems to be an appropriate alternative for long-term primary and secondary prophylaxis of SBP in cirrhotic patients with ascites. Modification of dose regimen should be considered to improve patient's compliance to rifaximin.