Modulation of plant resistance to diseases by water-soluble chitosan

Low-molecular-weight water-soluble chitosan with a molecular weight of 5 kDa obtained after enzymatic hydrolysis of native crab chitosan was shown to display an elicitor activity by inducing the local and systemic resistance of Solanumi tuberosum potato and Lycopesicon esculentum tomato to Phytophthora infestans and nematodes, respectively. Chitosan induced the accumulation of phytoalexins in tissues of host plants, decreased the total content and changed the composition of free sterols producing adverse effects on infesters, activated chitinases, beta-glucanases, and lipoxygenases, and stimulated the generation of reactive oxygen species. The activation of protective mechanisms in plant tissues inhibited the growth of taxonomically different pathogens (parasitic fungus Phytophthora infestans and root knot nematode Meloidogyne incognita).     

Induction of Resistance to Phytophthora in Tubers of Transgenic Potato

Resistance of transgenic cultivars based on the expression of one or more resistance genes is sooner or later broken by pathogens whose race-producing rates are high. Thus, combining transgenesis with elicitor-induced resistance is a promising approach. The elicitor-induced resistance is based on the expression of multiple resistance genes, which can prevent the adaptation of pathogens to transgenic cultivars, maintain the stability of cultivars, and increase their lifespan. In this work, we used transgenic potato cultivars Temp and Superior transformed with Bacillus thuringiensis -endotoxin gene and Luk'yanovskii transformed with leukocyte interferon gene. Arachidonic acid (10^–8 M) and soluble chitosan (5 kDa, 100 g/ml) were used as elicitors for tuber treatment. Our data showed that pretreatment with elicitors causes a 15–25% increase in both the systemic prolonged resistance of potato tubers to Phytophthora infestansand their ability to repair mechanical damage.     

Diagnostic criteria for diabetes revisited: making use of combined criteria

Background  

Existing cut-offs for fasting plasma glucose (FPG) and post-load glucose (2hPG) criteria are not equivalent in the diagnosis of diabetes and glucose intolerance. Adjusting cut-offs of single measurements have not helped so we undertook this project to see if they could be complementary.     

Epimerization of hydroxyl group in the lupan series of triterpenes

Two methods of obtaining of 3 alpha-betulinic acid and related compounds from their 3 beta-epimers were studied: the reaction of bimolecular substitution and the stereoselective reduction of 3-ketoderivatives. The substitution of acyloxy by formyloxy group in 3-O-tosyllupeol or of the betulin hydroxyl by benzoyloxy group resulted only in delta 2, 3-elimination products, with none of the expected products of bimolecular substitution being found. The catalytic hydrogenation of betulonic acid over Raney nickel resulted only in reduction of the isopropenyl double bond, whereas the use of 5% Ru/C gave a 60:40 mixture of epimers of dihydrobetulinic acid. Practically the same mixture of betulinic acid epimers was obtained when reducing betulonic acid with L-Selectride. The cytotoxic activity of 3 alpha-betulinic acid increased toward melanoma Bro cells and decreased toward melanoma MS cells.     

Role of proteinase inhibitors in potato protection

Mechanical damage or infection of potatoes with Phytophthora infestans caused an accumulation of only serine protease inhibitors in exudates of potato tubers. Among them, proteins prevailed that are structurally similar to those present in healthy tubers: a 22-kDa trypsin inhibitor, a 21-kDa serine protease inhibitor consisting of two polypeptide chains, and a 8-kDa potato chymotrypsin I inhibitor produced de novo. The accumulated proteins inhibited the growth of hyphae and germination of zoospores of P. infestans. Treatment with elicitors, jasmonic and arachidonic acids, intensified the accumulation of these inhibitors in tubers in response to the wound stress, whereas salicylic acid blocked this process. These results suggest that the lipoxygenase metabolism plays a substantial role in signal transduction of the protective system of resting potato tubers.     

Epimerization of Hydroxyl Group in Lupan Series Triterpenoids

Two methods of obtaining 3-betulinic acid and related compounds from their 3-epimers were studied: the reaction of bimolecular substitution and the stereoselective reduction of 3-ketoderivatives. The substitution of acyloxy by formyloxy group in 3--tosyllupeol or of the belulin hydroxyl by benzoyloxy group resulted only in ^{2, 3}-elimination products, with none of the expected products of bimolecular substitution being found. The catalytic hydrogenation of betulonic acid over Raney nickel resulted only in reduction of the isopropenyl double bond, whereas the use of 5% Ru/C gave a 60 : 40 mixture of epimers of dihydrobetulinic acid. Practically the same mixture of betulinic acid epimers was obtained when reducing betulonic acid with L-Selectride. The cytotoxic activity of 3-betulinic acid increased toward the Bro melanoma cells and decreased toward the MS melanoma cells.     

Isolation and characterization of highly pathogenic avian influenza virus subtype H5N1 from donkeys

Background  

The highly pathogenic H5N1 is a major avian pathogen that crosses species barriers and seriously affects humans as well as some mammals. It mutates in an intensified manner and is considered a potential candidate for the possible next pandemic with all the catastrophic consequences.     

<Emphasis Type="Italic">TRAF1/C5</Emphasis>polymorphism is not associated with increased mortality in rheumatoid arthritis: two large longitudinal studies

Introduction  

Recently an association between a genetic variation in TRAF1/C5 and mortality from sepsis or cancer was found in rheumatoid arthritis (RA). The most prevalent cause of death, cardiovascular disease, may have been missed in that study, since patients were enrolled at an advanced disease stage. Therefore, we used an inception cohort of RA patients to investigate the association between TRAF1/C5 and cardiovascular mortality, and replicate the findings on all-cause mortality. As TRAF1/C5 associated mortality may not be restricted to RA, we also studied a large cohort of non-RA patients.