Role of Notch signaling in establishing the hemilineages of secondary neurons in Drosophila melanogaster.

The secondary neurons generated in the thoracic central nervous system of Drosophila arise from a hemisegmental set of 25 neuronal stem cells, the neuroblasts (NBs). Each NB undergoes repeated asymmetric divisions to produce a series of smaller ganglion mother cells (GMCs), which typically divide once to form two daughter neurons. We find that the two daughters of the GMC consistently have distinct fates.

Comparison of microbial receptor assay and liquid chromatography for determination of penicillin G and amoxicillin in milk powder.

A microbial receptor assay (Charm II Tablet Beta-Lactam Test) and liquid chromatography (LC) were compared for determination of penicillin G (PG) and amoxicillin (AMOX) in reconstituted milk powder. Nonfat dry milk and whole dry milk were reconstituted (10%, w/v) to concentrations of 0, 2.5, 5, 7.

Screening method for identification of beta-lactams in bovine urine by use of liquid chromatography and a microbial inhibition test.

Objective: To develop a multiple-residue screening method for the detection of beta-lactams in bovine urine.

Animals: 6 clinically normal Holstein cows and 6 calves.

Procedure: Pooled urine obtained from cows was used as a negative-control sample or spiked with varying concentrations of 6 beta-lactam antibiotics.

Potential for milk containing penicillin G or amoxicillin to cause residues in calves.

The potential for antibiotic residues in calves from consuming milk containing penicillin G or amoxicillin was investigated. Six calves were fed milk replacer, 6% body weight twice daily, containing 0.293, 2.

Determination of tetracycline antibiotics in beef and pork tissues using ion-paired liquid chromatography.

A simplified procedure was developed for determination of tetracycline antibiotics in tissues which improved stability of these compounds in sample extracts and eliminated the need for troublesome cleanup procedures. Tissues were homogenized in water. Acetonitrile (16 mL) and then 1 mL of 0.