Corrinoid (vitamin B12-like) cofactors contain various alpha-axial ligands, including 5,6-dimethylbenzimidazole (DMB) or adenine. The bacterium Salmonella enterica produces the corrin ring only under anaerobic conditions, but it can form "complete" corrinoids aerobically by importing an "incomplete" corrinoid, such as cobinamide (Cbi), and adding appropriate alpha- and beta-axial ligands. Under...

In the Aplysia mechanoafferent B21, afferent transmission is in part regulated via the control of active spike propagation. When B21 is peripherally activated at its resting membrane potential, spikes fail to propagate to an output process, and afferent transmission does not occur. In this report we show that the propagation failure is in part a result of the fact that the somatic region of B21...

Normal human serum contains a few hundred micro-microgrammes (,u,ug.) of vitamin B12 per ml. A micro-microgramme is one-millionth of a millionth of a gramme, or I/I,000,000,000 of a milligramme. No chemical method is capable of measuring such small amounts. Specialized techniques are necessary and, with one exception, all methods employ microbiological assays. Certain micro-organisms require vi...

Extensive research on the formation of methionine has implicated vitamin B12 as a cofactor in the final reaction of the biosynthetic sequence. Since plants and fungi do not produce or require B12, an alternate reaction must also exist. It is thus not surprising that Escherichia coli has been found to possess two mechanisms for the methylation of homocysteine to methionine (9). These reactions a...

Objective: Investigations were carried out to isolate bacteria from saline-alkali soils and determined optimized alkaline protease activity and stability produced by a wild strain of bacillus sp. in submerged fermentation (SMF). Methods: Optimum temperature for enzyme activity in the crude extract was 40 ◦C at a pH between 8.0 and 9.0. The studies on pH stability showed that the enzyme...

In a recent Cognition paper (Cognition 85 (2002) B21), Bornkessel, Schlesewsky, and Friederici report ERP data that they claim "show that online processing difficulties induced by word order variations in German cannot be attributed to the relative infrequency of the constructions in question, but rather appear to reflect the application of grammatical principles during parsing" (p. B21). In th...