George Kidd

Chromosome diminution in Ascaris suum Two-fold increase of nucleosomal histone to DNA ratios during development

The swine intestinal nematode, Ascaris suum, eliminates chromatin material from its primordial somatic cells during early embryogenesis. A technique for isolation of nuclei from pre- and post-diminution stage embryos has been developed and these isolated nuclei were used in investigations of nuclear events during diminution. The amount of DNA per nucleus determined by diphenylamine assays and isotope dilutions was 0.66 pg and 0.29 pg in pre- and post-diminution nuclei, respectively. Thus, A. suum loses 56% of its nuclear DNA during diminution. The loss of nuclear DNA enabled in vivo examination of histone to DNA ratios as a function of changes in DNA quantities. Ascaris histones were identified by acid extractability and tryptic fingerprint comparison with rat liver histones. Measurement of histone quantities was accomplished using linearity of Coomassie blue binding to histones separated in dodecyl sulfate gels. Ascaris nucleosomal histones levels were relatively constant in pre- and post-diminution nuclei. However, nucleosomal histone to DNA ratios approximately doubled during diminution.

Optimization of Sorghum Primary Callus Growth

Summary Growth of primary callus of sorghum ( S. bicolor var. Sart ) was optimized and formation of black growth inhibiting pigment(s) was minimized. Etiolated shoots were cultured on media containing Murashige and Skoog salts as well as 3% (w/v) sucrose, 3 mg/l 2,4-D, and 10% (v/v) coconut water. Carbon source, auxin, and cytokinin were varied singly, while the remaining components were maintained at the above levels. 2,4-dichlorophenoxyacetic acid was the only auxin that enhanced callus growth, especially at 3 mg/l. All of the cytokinins tested - kinetin, N-6-benzyladenine, zeatin, 6-(γ,γ-dimethylallylamino) purine, 6-dimethylaminopurine (0.1 mg/1), and coconut water (10-20%) - promoted equal callus growth. As compared to sucrose- and sorbitol-containing media, greater primary callus growth occurred with 1% glucose or fructose. On sorbitol, there was no callus formation; on sucrose, callus formation occurred only at 3%. None of the media consistently resulted in callus growth without formation of black pigment(s).

Somatic embryogenesis and regeneration from milkweed cell cultures

Abstract Whole plants of two milkweed species (Asclepias syriaca, A. tuberosa) were regenerated from cell cultures via in vitro embryogenesis. This process could provide a means for rapid selection of superior varieties of milkweed for hydrocarbon crop development.

Mycogen magically turns around agrigenetics

This short article describes how Mycogen, which acquired Agrigenetics/Lubrizol`s seed industry in the 1993, finally turned a profit after drastic sales and brand consolidation updates. Lubrizol is a supplier of lubricant additives to the energy industry. Until Mycogen turned it around, Agrigenetics stood as a stark example of the unfulfilled dreams plaguing agbiotech.