Molecular Weights of Vesicular Stomatitis Virus and Its Defective Particles by Laser Light-Scattering Spectroscopy

Laser light-scattering spectroscopy has been used to determine the diffusion coefficients of vesicular stomatitis virus and three of its defective particles in order to calculate their molecular weights.     

Exploring genetic variability within lentil (Lens culinaris Medik.) and across related legumes using a newly developed set of microsatellite markers

Lentil (Lens culinaris Medik.) is an economically important grain legume, yet the genetic and genomic resources remain largely uncharacterized and unexploited in this crop. Microsatellites have become markers of choice for crop improvement applications. Hence, simple sequence repeat (SSR) markers were developed for lentil through the construction of genomic library enriched for GA/CT motifs. As a result 122 functional SSR primer pairs were developed from 151 microsatellite loci and validated in L. culinaris cv. Precoz. Thirty three SSR markers were utilized for the analysis of genetic relationships between cultivated and wild species of Lens and related legumes. A total of 123 alleles were amplified at 33 loci ranging from 2–5 alleles with an average of 3.73 alleles per locus. Polymorphic information content (PIC) for all the loci ranged from 0.13 to 0.99 with an average of 0.66 per locus. Varied levels of cross genera transferability were obtained ranging from 69.70 % across Pisum sativum to 12.12 % across Vigna radiata. The UPGMA based dendrogram was able to establish the uniqueness of each genotype and grouped them into two major clusters clearly resolving the genetic relationships within lentil and related species. The new set of SSR markers reported here were efficient and highly polymorphic and would add to the existing repertoire of lentil SSR markers to be utilized in molecular breeding. Moreover, the improved knowledge about intra- and inter-specific genetic relationships would facilitate germplasm utilization for lentil improvement.     

Introgression of Pi2 and Pi5 Genes for Blast (Magnaporthe oryzae) Resistance in Rice and Field Evaluation of Introgression Lines for Resistance and Yield Traits

Blast caused by Magnaporthe oryzae is the most devastating disease causing significant loss in rice production. The destructive nature of the disease is mainly due to the genetic plasticity of M. oryzae which complicates the breeding strategies. Blast can be effectively managed by the deployment of R genes. In this study, broad‐spectrum blast resistance genes Pi2 and Pi5 were introgressed independently into popular but blast susceptible rice variety, Samba Mahsuri (BPT5204) by applying marker‐assisted backcross breeding approach. Tightly linked markers AP5930 for Pi2 and 40N23r for Pi5 gene were used in foreground selection. Background selection helped to identify the lines with maximum recovery of recurrent parent genome (RPG). The RPG recovery in Pi2 introgression lines was up to 90.17 and 91.46% in Pi5 lines. Homozygous introgression lines in BC₃F₄ generation carrying Pi2 and Pi5 gene were field evaluated for blast resistance, yield per se and yield‐related traits. The lines showed resistance to leaf and neck blast in multilocation field evaluation. Improved BPT5204 lines with improvement for blast resistance were on par with original BPT5204 in terms of grain yield and grain features.     

URP‐based DNA Fingerprinting of Bipolaris sorokiniana Isolates Causing Spot Blotch of Wheat

Spot blotch, caused by the pathogen Bipolaris sorokiniana is an important disease of wheat and is responsible for large economic losses world wide. In this study, molecular variability in B. sorokiniana isolates collected from different regions of India was investigated using URP‐PCR technique. All the 40 isolates used in the study were pathogenic when tested on susceptible host, Agra local, although they varied in pathogenicity. Isolate BS‐49 was least virulent showing 4.5 infection index while BS‐75 was the most virulent with 63.4 infection index. The universal rice primers (URPs’) are primers which have been derived from DNA repeat sequences in the rice genome. Out of the 12 URP markers used in the study, 10 markers were effective in producing polymorphic fingerprint patterns from DNA of B. sorokiniana isolates. The analysis of entire fingerprint profile using unweighted pair group method with arithmetic averages (UPGMA) differentiated B. sorokiniana isolates obtained from different geographic regions. One isolate BS‐53 from northern hill zone was different from rest of the isolates showing less than 50% similarity. Broadly, three major clusters were obtained using UPGMA method. One cluster consisted of isolates from North western plain zone; second cluster having isolates from North eastern plain zone and third cluster consisted of isolates from Peninsular zone showing more than 75% genetic similarity among them. One of the markers, URP‐2F (5′GTGTGCGATCAGTTGCTGGG3′) amplified three monomorphic bands of 0.60, 0.80 and 0.90 kb size which could be used as specific markers for identification of B. sorokiniana. Further, based on URP‐PCR analysis, the grouping of the isolates according to the geographic origin was possible. This analysis also provided important information on the degree of genetic variability and relationship between the isolates of B. sorokiniana.     

Barium Bismuth Niobate Double Perovskite/Tungsten Oxide Nanosheet Photoanode for High‐Performance Photoelectrochemical Water Splitting

Recently, a new method to effectively engineer the bandgap of barium bismuth niobate (BBNO) double perovskite was reported. However, the planar electrodes based on BBNO thin films show low photocurrent densities for water oxidation owing to their poor electrical conductivity. Here, it is reported that the photoelectrochemical (PEC) activity of BBNO‐based electrodes can be dramatically enhanced by coating thin BBNO layers on tungsten oxide (WO₃) nanosheets to solve the poor conductivity issue while maintaining strong light absorption. The PEC activity of BBNO/WO₃ nanosheet photoanodes can be further enhanced by applying Co_0.8Mn_0.2O_x nanoparticles as a co‐catalyst. A photocurrent density of 6.02 mA cm^?2 at 1.23 V (vs reversible hydrogen electrode (RHE)) is obtained using three optically stacked, but electrically parallel, BBNO/WO₃ nanosheet photoanodes. The BBNO/WO₃ nanosheet photoanodes also exhibit excellent stability in a high‐pH alkaline solution; the photoanodes demonstrate negligible photocurrent density decay while under continuous PEC operation for more than 7 h. This work suggests a viable approach to improve the PEC performance of BBNO absorber‐based devices.     

Occurrence of nitrogen-fixing Azospirillum in vesicular-arbuscular mycorrhizal fungi

Nitrogenase activity measured by acetylene reduction, was detected when surface-sterilized spores of vesicular-arbuscular (VA) mycorrhizal fungi (Glomus fasciculatum, G. intraradices, G. scientillans, G. mosseae, Gigaspora gilmorei andEndogone dusii) were inoculated into nitrogen-free liquid medium containing malic acid and incubated under microaerophilic conditions (99% N₂+1% O₂) at 30°C.Azospirillum species were isolated from the nitrogenase-active cultures.     

Ansamitocin P3 Depolymerizes Microtubules and Induces Apoptosis by Binding to Tubulin at the Vinblastine Site

Maytansinoid conjugates are currently under different phases of clinical trials and have been showing promising activity for various types of cancers. In this study, we have elucidated the mechanism of action of ansamitocin P3, a structural analogue of maytansine for its anticancer activity. Ansamitocin P3 potently inhibited the proliferation of MCF-7, HeLa, EMT-6/AR1 and MDA-MB-231 cells in culture with a half-maximal inhibitory concentration of 20±3, 50±0.5, 140±17, and 150±1.1 pM, respectively. Ansamitocin P3 strongly depolymerized both interphase and mitotic microtubules and perturbed chromosome segregation at its proliferation inhibitory concentration range. Treatment of ansamitocin P3 activated spindle checkpoint surveillance proteins, Mad2 and BubR1 and blocked the cells in mitotic phase of the cell cycle. Subsequently, cells underwent apoptosis via p53 mediated apoptotic pathway. Further, ansamitocin P3 was found to bind to purified tubulin in vitro with a dissociation constant (K_d) of 1.3±0.7 µM. The binding of ansamitocin P3 induced conformational changes in tubulin. A docking analysis suggested that ansamitocin P3 may bind partially to vinblastine binding site on tubulin in two different positions. The analysis indicated that the binding of ansamitocin P3 to tubulin is stabilized by hydrogen bonds. In addition, weak interactions such as halogen-oxygen interactions may also contribute to the binding of ansamitocin P3 to tubulin. The study provided a significant insight in understanding the antiproliferative mechanism of action of ansamitocin P3.