The incorporation into a 7% polyacrylamide gel of a nucleic acid-specific photochemical reagent 4,5',8-trimethylpsoralen at a concentration of 1 mg/dl of acrylamide solution improves both the sensitivity and the efficiency of the transfer of plasmid DNA fragments from the gel onto nitrocellulose filters. This improvement allows detection by blot hybridization of DNA fragments as small as 57 bp ...

A modular total synthesis of the natural product (+)-varitriol (1) and seven analogs was achieved by using combined coinage metal catalysis. Starting from enynol 13, reagent-controlled introduction of stereogenic centers and efficient center-to-axis-to-center chirality transfer viaα-hydroxyallene 5 afforded (+)-varitriol with 6.4% yield over 10 steps.

The mechanism of the previously developed cross-coupling reaction of aryl Grignard reagents with aryl halides was explored in more detail. Single electron transfer from an aryl Grignard reagent to an aryl halide initiates a radical chain by giving an anion radical of the aryl halide. The following propagation cycle consists entirely of anion radical intermediates.

This review provides a good overview of biological nitrogen fixation in the growth of leguminous plants, particularly relating to fertilizer needs for crops. In addition to plants that form nodules that host nitrogen-fixing bacteria, other bacteria form different associations with plants, and this is currently under intense study to determine if there is significant nitrogen transfer to the pla...

o-Phthaldialdehdye reagent was used in assaying urea with a miniature centrifugal analyzer. Seventeen samples can be assayed kinetically in 2 min at a current cost of less than a penny per test. The reaction is initiated in the instrument upon simultaneous mixing of the o-phthaldialdehyde reagent containing 10 microliter of sample with dilute sulfuric acid/N-(1-naphthyl)ethylenediamine dihydroc...

Abstract

Up-regulation of the high-affinity transport system (HATS) for NO(3)(-) and stimulation of lateral root (LR) growth are two important adaptive responses of the root system to nitrogen limitation. Up-regulation of the NO(3)(-) HATS by nitrogen starvation is suppressed in the atnrt2.1-1 mutant of Arabidopsis (Arabidopsis thaliana), deleted for both NRT2.1 and NRT2.2 nitrate transporter genes. We ...

Short term (2-hour) incorporation of nitrogen from nitrate, glutamine, or asparagine was studied by supplying them as unlabeled ((14)N) tracers to growing pea (Pisum sativum L.) leaves, which were previously labeled with (15)N, and then following the elimination of (15)N from various amino components of the tissue. Most components had active and inactive pools. Ammonia produced from nitrate was...