A comparative study of transgenic canola (<Emphasis Type="Italic">Brassica napus</Emphasis> L.) harboring either chimeric or native <Emphasis Type="Italic">Chit</Emphasis>42 genes against phytopathogenic fungi

Canola (Brassica napus L.), an agro-economically important crop in the world, is sensitive to many fungal pathogens. One strategy to combat fungal diseases is genetic engineering through transferring genes encoding the pathogenesis-related (PR) proteins such as chitinase which cause the chitin degradation of fungal cell wall. Chitinase Chit42 from Trichoderma atroviride (PTCC5220) plays an important role in biocontrol and has high antifungal activity against a wide range of phytopathogenic fungi. This enzyme lacks a chitin binding domain (ChBD) which is involved in binding activity to insoluble chitin. In the present study, we investigated the effect of chitin binding domain fused to Chit42 when compared with native Chit42. These genes were over-expressed under the CaMV35S promoter in B. napus, R line Hyola 308. Transformation of cotyledonary petioles was achieved by pBISM2 and pBIKE1 constructs containing chimeric and native Chit42 genes respectively, via Agrobacterium method. The insertion of transgenes in T₀ generation was verified through polymerase chain reaction (PCR) and Southern blot analysis. Antifungal activity of expressed chitinase in transgenic plants was also investigated by bioassays. The transgenic canola expressing chimeric chitinase showed stronger inhibition against phytopathogenic fungi that indicates the role of chitin binding domain.     

Epistatic effects of genes encoding tumor necrosis factor-α, immunoglobulin allotypes, and HLA antigens on susceptibility to non-insulin-dependent (type 2) diabetes mellitus

 Non-insulin-dependent diabetes mellitus (NIDDM) is a complex disease with a very high degree of heritability. Linkage and segregation analyses have not been very productive in identifying genes responsible for polygenic diseases such as NIDDM, and the majority of the genes determining susceptibility to this disorder remain to be identified. Using a case-control study design, we investigated the possible roles of genes coding for HLA class II antigens, tumor necrosis factor-α (TNF-α), and immunoglobulin (Ig) allotypes (GM and KM) in a group of Caucasians from Belgium (214 NIDDM patients and 200 controls). All genetic markers were determined by polymerase chain reaction-based methods. We demonstrate that particular homozygous genotypes of TNF-α and GM and KM allotypes epistatically interact with HLA-DQα1^{Arg 52} and contribute to an increased relative risk of NIDDM. Received: 3 January 1999 / Accepted: 18 March 1999     

Taste attractiveness of free amino acids for juveniles of Persian sturgeon <Emphasis Type="Italic">Acipenser persicus</Emphasis>

Taste preferences towards 20 free amino acids (L-isomers, 0.1–0.0001 M) were determined in juveniles of Persian sturgeon Acipenser persicus. It was found that most amino acids (16) had a positive effect on extraoral gustatory reception (increased the frequency of catching artificial pellets by fishes). The most efficient amino acids were the following: threonine, histidine, arginine, asparagine, phenylalanine, cysteine, glutamine, and glycine. Fifteen amino acids were efficient for intraoral gustatory receptors: serine, arginine, cysteine, histidine, alanine, and some others. The presence of these amino acids in pellets increased the consumption. Amino acids decreasing the frequency of catching or consumption of pellets were not found. Highly significant positive correlation was found between the amino acid ranges mediated by the extraoral and intraoral gustatory reception. The fishes demonstrated maximum sensitivity to aspartic acid, 0.01 and 0.001 M, respectively, for intraoral and extraoral gustatory systems. The threshold concentrations of arginine and glycine were higher for the intraoral gustatory system (0.01 M) than for the extraoral one (0.1 M). The comparison of Persian sturgeon with sturgeon fishes (Russian sturgeon A. gueldenstaedtii, Siberian sturgeon A, baerii, and starred sturgeon A. stellatus) studied earlier confirmed high species specificity of intraoral taste preferences in representatives of Acipenser genus. Species specificity of extraoral taste ranges was less pronounced.     

Therapeutic effects of Typha elephantina leave’s extract against paracetamol induced renal injury in rabbits

Present study focuses on ameliorative potential of Typha elephantina leave’s aqueous (TE.AQ) extract against Paracetamol (PCM) induced toxicity in rabbits. We fed the male rabbits with 300 mg PCM in alone and in combination with TE.AQ at different doses i.e. (100, 200 and 300 mg/kg body weight) or silymarin (100 mg/kg) daily for 21 days. PCM in alone significantly (P < 0.5) increased serum urea, uric acid, creatinine, total protein, albumin, globulin and blood urea nitrogen. Serum sodium, potassium and magnesium level were high. The glutathione, radical scavenging activity and Thiobarbituric acid reactive substances were significantly reduced. Treatment with TE.AQ at dose rate 300 mg/kg body weight and Silymarin significantly ameliorated all the parameters when compared with PCM administered group. The 100 and 200 mg of TE.AQ showed no significant effects. The histopathological examination confirmed the therapeutic potential of TE.AQ. These results established the presence of natural antioxidants in Typha elephantina leaves.     

Effect of exposure to extremely low electro-magnetic field during prenatal period on mice spleen

Total body weight of newborns, the volume of spleen, and the number of megakaryocytes decreased following the exposure to ELF-MF (6 x 10(-3) T and 50 Hz) at 1-5, 6-10, 11-15, and 16-20 days of pregnancy of mice. The complete period of gestation was sensitive to ELF-MF exposure; the initial days were more prone to exposure. The results suggest that the use of ELF-MF producing instruments should be limited during gestation.     

Geometrical correlations in the nucleosomal DNA conformation and the role of the covalent bonds rigidity

We develop a simple elastic model to study the conformation of DNA in the nucleosome core particle. In this model, the changes in the energy of the covalent bonds that connect the base pairs of each strand of the DNA double helix, as well as the lateral displacements and the rotation of adjacent base pairs are considered. We show that because of the rigidity of the covalent bonds in the sugar-phosphate backbones, the base pair parameters are highly correlated, especially, strong twist-roll-slide correlation in the conformation of the nucleosomal DNA is vividly observed in the calculated results. This simple model succeeds to account for the detailed features of the structure of the nucleosomal DNA, particularly, its more important base pair parameters, roll and slide, in good agreement with the experimental results.     

Effects of the exogenous application of auxin and cytokinin on carbohydrate accumulation in grains of rice under salt stress

Phytohormones, such as auxin and cytokinin, are known to be involved in the regulation of plant responses to salinity stress and counteract the adverse effect of stress conditions. This work investigated the effects of the exogenous spraying of indole-3-acetic acid (IAA) and kinetin (KIN) during the reproductive phase on grain yield by examining the 1000-grain weight and filled-grain percentage as well as the changes in starch, total soluble sugars, sucrose, glucose and fructose concentrations in the grains of two rice cultivars under salt stress. The results indicated that the applied IAA and KIN led to an increased grain yield, 1000-grain weight and filled-grain percentage for both rice cultivars under salt stress. The storage starch content in the grain of the salt-sensitive cultivar was more than that in the salt-tolerant cultivar under IAA application compared with KIN, whereas a decrease in the total soluble sugar content was observed with both IAA and KIN treatments, in comparison to the non-hormone treatment. Interestingly, this study showed that IAA led to a much higher increase in the sucrose content in grain, as compared to the KIN. Furthermore, this experiment suggests that glucose and fructose may play important roles during salt stress because there were clearly higher concentrations of these sugars in the grain of the stressed cultivars under IAA and KIN application: it appears that their accumulation was the earliest response detected during the grain-filling period in rice. Finally, this work indicated that an increase in the rice grain yield, 1000-grain weight and filled-grain percentage are associated with an increase in the contents of starch, sucrose, glucose and fructose in grain caused by the application of IAA and KIN.     

Dynamic Nanofin Heat Sinks

The limitation of hot spot cooling in microchips represents an important hurdle for the electronics industry to overcome with coolers yet to exceed the efficiencies required. Nanotechnology‐enabled heat sinks that can be magnetophoretically formed onto the hot spots within a microfluidic environment are presented. CrO₂ nanoparticles, which are dynamically chained and docked onto the hot spots, establish tuneable high‐aspect‐ratio nanofins for the heat exchange between these hot spots and the liquid coolant. These nanofins can also be grown and released on demand, absorbing and releasing the heat from the hot spots into the microfluidic system. It is shown that both high aspect ratio and flexibility of the fins have a dramatic effect on increasing the heat sinking efficiency. The system has the potential to offer a practical cooling solution for future electronics.