Mutagenesis: investigating the process and processing the outcome for crop improvement

The discoveries during the late 1920s that the genetic material is amenable to changes excited geneticists who saw new opportunities for both basic and practical applications. During the 1950s, induced mutagenesis was widely pursued in the US, Europe, Japan and China. In India, Swaminathan and his team at the Indian Agricultural Research Institute, New Delhi initiated a major programme on mutagenesis in crop plants. These studies were broadly aimed at understanding the process of mutation, testing the efficacy of various mutagens, identifying optimum dose and the best method of treatment for different crop species; isolation of mutants of basic and applied value; elucidating the biological effects of radiation-treated media, seeds and vegetative propagules on the organisms consuming them

Comparative shoot regeneration in diploid and amphidiploid Brassica species and their interspecific hybrids

Shoot regeneration response in interspecific hybrids of Brassica species were assessed in relation to the diploid pollen parents and amphidiploid female parents. Superior regeneration responses were observed in interspecific combinations of B. carinata and B. nigra (BBC), B. juncea and B. campestris (AAB), and B. napus and B. campestris (AAC). Though synthetic B. napus regenerated with a frequency less than that of the better regenerating parent (B. oleracea), higher regeneration response was observed in the hybrid between B. napus and B. campestris. Two triploid combinations of the genetic constitution ABC, one obtained by crossing synthetic B. napus with B. nigra and the other by crossing natural B. juncea with B. oleracea, showed low regeneration responses. The response improved substantially in a tetraploid of the constitution ABBC obtained by crossing B. juncea with B. carinata. Key words: Brassica, alloploids, shoot regeneration

Noninvasive Embedding of Single Co Atoms in Ge(111)2x1 Surfaces

We report on a combined scanning tunneling microscopy (STM) and density functional theory (DFT) based investigation of Co atoms on Ge(111)2x1 surfaces. When deposited on cold surfaces, individual Co atoms have a limited diffusivity on the atomically flat areas and apparently reside on top of the upper pi-bonded chain rows exclusively. Voltage-dependent STM imaging reveals a highly anisotropic electronic perturbation of the Ge surface surrounding these Co atoms and pronounced one-dimensional confinement along the pi-bonded chains. DFT calculations reveal that the individual Co atoms are in fact embedded in the Ge surface, where they occupy a quasi-stationary position within the big 7-member Ge ring in between the 3rd and 4th atomic Ge layer. The energy needed for the Co atoms to overcome the potential barrier for penetration in the Ge surface is provided by the kinetic energy resulting from the deposition process. DFT calculations further demonstrate that the embedded Co atoms form four covalent Co-Ge bonds, resulting in a Co4+ valence state and a 3d5 electronic configuration. Calculated STM images are in perfect agreement with the experimental atomic resolution STM images for the broad range of applied tunneling voltages.Comment: 19 pages, 15 figures, 3 table

Resynthesized Brassica juncea lines with novel organellar genome constitution obtained through protoplast fusion

This article does not have an abstract

Peripherally inserted central catheter‐related deep vein thrombosis: contemporary patterns and predictors

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/107486/1/jth12549.pd

Peripherally inserted central catheter‐related deep vein thrombosis: contemporary patterns and predictors: reply

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109637/1/jth12721.pd

Distribution of fatty acids during germination of soybean seeds

Gas chromatographic determination of the fatty acids in the seeds of soybean (Glycine max) showed mainly linoleic, oleic and palmitic acids with linoleic acid being the major component. Changes in the distribution of fatty acids were measured during germination in the cotyledons and roots. A decrease in palmitic and oleic acids was observed in the cotyledons from 6 to 12 days, while linoleic acid increased during the same period. In roots also, the major fatty acid was linoleic acid, while palmitic and linolenic acids were higher in roots in comparison with the cotyledons. During the 3-12 days of germination period, no major changes in the distribution pattern of fatty acids were observed in the roots. The possible significance of these changes is discussed

Induction of polyploidy in watermelon

Several colchicine treatment methods were tried in the varieties Farrukhabadi and Asahi Yamato of watermelon in order to induce chromosome doubling in them. Treatment of seedlings by drop method in the cotyledonary stage with an emulsion comprising 0.2% colchicine, stearic acid, morpholine and lanoline gave the highest percentage of affected plants (38.59%). Next in efficiency was the periodic application of drops of 0.4% colchicine on the growing point. The tetraploids had all the usual characteristics associated with autopolyploidy and during meiosis in a microsporocyte 11 quadrivalents were observed. The mean frequency of quadrivalents per cell was 5.91. Seed fertility in tetraploid watermelon was much reduced and from 4x×2x crosses in Farrukhabadi one fruit containing 67 seeds was obtained. The 3x seeds germinated only when the seed coat was partly removed and the fruit set on a 3x plant had seeds without embryo. There appears to exist genetic variability with regard to the ability of a strain to yield a completely seedless triploid and it is consequently necessary to produce triploids of many varieties and select the desirable ones for the commercial production of seedless watermelon