The Pathway to Bacterial Genetics

This chapter reviews Esther Zimmer’s early training, as she set out on a parallel career pathway, from Neurospora to bacteria, to her future husband Joshua Lederberg. While still a junior at Hunter College, Zimmer found the best possible mentor in Bernard Ogilvie Dodge, the foremost expert in Neurospora, the new model organism of genetic research. After graduation, Dodge helped her gain further research experience at the Industrial Hygiene Research Laboratory in Bethesda, Maryland, where she worked with Alexander Hollaender, an expert in radiation biology. After two years of training in the procedures for developing X-ray and UV induced mutations, Zimmer acquired her bona fides for graduate school. She was accepted to graduate school at Stanford University because of Dodge’s association with George Beadle, who, with Edward Tatum, had developed a new paradigm for biochemical genetics: “one gene: one enzyme.” In 1946, their similar experiences in Neurospora research brought Joshua and Esther together.

The Thiamin-Requiring 3 Mutation of Arabidopsis 5-Deoxyxylulose-Phosphate Synthase 1 Highlights How the Thiamin Economy Impacts the Methylerythritol 4-Phosphate Pathway

The thiamin-requiring mutants of Arabidopsis have a storied history as a foundational model for biochemical genetics in plants and have illuminated the central role of thiamin in metabolism. Recent integrative genetic and biochemical analyses of thiamin biosynthesis and utilization imply that leaf metabolism normally operates close to thiamin-limiting conditions. Thus, the mechanisms that allocate thiamin-diphosphate (ThDP) cofactor among the diverse thiamin-dependent enzymes localized in plastids, mitochondria, peroxisomes, and the cytosol comprise an intricate thiamin economy. Here, we show that the classical thiamin-requiring 3 (th3) mutant is a point mutation in plastid localized 5-deoxyxylulose synthase 1 (DXS1), a key regulated enzyme in the methylerythritol 4-phosphate (MEP) isoprene biosynthesis pathway. Substitution of a lysine for a highly conserved glutamate residue (E323) located at the subunit interface of the homodimeric enzyme conditions a hypomorphic phenotype that can be rescued by supplying low concentrations of thiamin in the medium. Analysis of leaf thiamin vitamers showed that supplementing the medium with thiamin increased total ThDP content in both wild type and th3 mutant plants, supporting a hypothesis that the mutant DXS1 enzyme has a reduced affinity for the ThDP cofactor. An unexpected upregulation of a suite of biotic-stress-response genes associated with accumulation of downstream MEP intermediate MEcPP suggests that th3 causes mis-regulation of DXS1 activity in thiamin-supplemented plants. Overall, these results highlight that the central role of ThDP availability in regulation of DXS1 activity and flux through the MEP pathway.

G6PD deficiency is a common genetic trait that can protect heterozygotes from dying from malaria

G6PD deficiency is a common genetic trait that can protect heterozygotes from dying from malaria (save in the extremely tiny fraction of individuals who have CNSHA). AHA in a G6PD-deficient child or adult, on the other hand, is a medical emergency that, if not treated promptly and properly, can be fatal. Fava bean consumption is the most common cause of AHA: favism is seen in at least 35 countries, with thousands of cases reported each year. Both primaquine and rasburicase have been linked to iatrogenic deaths in the same and other nations, and these deaths may have been averted. Population screening and health education, as well as the cultivation of fava bean types with nil or low vicine and convicine levels, can help to prevent fascism. G6PD biology is eminently interdisciplinary, having served as a model system in biochemical genetics and in understanding how the red cell responds to oxidative stress; a tool for studying X-chromosome inactivation (human development's most spectacular epigenetic event); a tool for studying clonal populations for years; and a pioneer in the molecular genetics of enzymopathies.

ASSESSMENT OF GENETIC STRUCTURE VARIABILITY OF RAINBOW TROUT Oncorhynchus mykiss (WALBAUM, 1792) OF UKRAINIAN LOCAL STOCKS USING POLYMORPHIC BLOOD PLASMA PROTEINS

Rainbow trout is a valuable species of aquaculture, which is characterized by a high level of variability. Aim. The goal was to study the peculiarities of genetic variability of rainbow trout based on polymorphism of transferrin (TF), posttransferrin (PTF), esterase (EST) (EC 3.1.1.1.) and albumin (ALB) loci. Methods. Electrophoretic separation of plasma proteins of rainbow trout from three local stocks (Chernivtsi, Kharkiv and Transcarpathian) was carried out in the native polyacrylamide gel. Results. Peculiarities of the distribution and relative electrophoretic mobility of allelic variants of the studied loci of rainbow trout of Ukrainian local stocks were established.The results demonstrated the effectiveness of the analysis using methods of biochemical genetics to establish the characteristics of the genetic structure, the level of heterozygosity of local stocks and to carry out their differentiation. Conclusion. The use of selected markers would allow monitoring the dynamics of changes in the state of local stocks under the established conditions of cultivation in the future. Key words: rainbow trout, polymorphic blood plasma proteins, transferrin, posttransferrin, esterase, albumin.

A Review of the Results of the Very Long Chain Fatty Acid Analyses for X-linked Adrenoleukodystrophy at the Biochemical Genetics Laboratory of the Institute of Human Genetics-National Institutes of Health, Manila

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