Large-scale production and chemical characterization of the protective higher plant allelochemicals: -Canavanine and -canaline

Procedures are presented for the large-scale preparation of -canavanine, and its principal catabolic product -canaline, compounds of demonstrated importance in biochemical ecology studies, and as higher plant chemotherapeutic agents. Mass spectroscopic and NMR data are provided for these experimentally-valuable natural products.     

Progress toward the synthesis of nonionic oligonucleotide analogues with sulfonate and sulfonamide internucleotide linkages.

The synthesis of building blocks for the preparation of nonionic oligonucleotide analogues with sulfonate and sulfonamide internucleotide linkages is described. Coupling conditions for the conversion of several of these monomers to dimers are also described.     

Growth status of school-age Mayan children in Belize,Central America

This paper reports the growth status of a sample of Mopan Maya school children living in a rural village in Belize. These children exhibit a growth pattern typical of chronic undernutrition, in that a high percentage are stunted (66%), but virtually none are wasted by WHO criteria. The Belize Maya children are compared to four other Amerindian groups and found to be shorter and lighter than a semi-urban group from Guatemala, but taller and heavier than three rural groups from Guatemala and Mexico. The Belize children exhibit the largest arm circumferences among all five groups. This pattern of growth is discussed in light of current ideas concerning the contribution of genetics vs. environment to childhood growth and population wellbeing. © 1994 Wiley-Liss, Inc.     

TRIDENS X OKLAHOMENSIS (T. FLAVUS X T. STRICTUS), AN INTERSPECIFIC STERILE HYBRID IN THE ERAGROSTEAE (GRAMINEAE)

The incidence of Tridens oklahomensis Feath. with T. flavus (L.) Hitchc. and T. strictus (Nutt.) Nash together with its morphological intermediacy between the latter two species suggests a hybrid origin. Field and laboratory studies conducted over several years provide substantial evidence of an interspecific cross. Tridens oklahomensis appears in generally disturbed habitats, such as roadsides and cleared areas, where the adventive (for this region) T. strictus occurs as overlapping populations with the ubiquitous T. flavus. At no time has the supposed hybrid been recorded solely with one or the other of the two species. On a moisture gradient, T. strictus is found mainly in swales and ditches while T. flavus occurs on the drier and more general upland. The hybrid occurs toward the moist end of gradient, near T. strictus. On this basis it is reasoned that the latter is the pistillate parent. The hybrid is sterile and has no vegetative means of spreading. Under these conditions its presence is limited to chance fertilization in those situations where T. strictus has invaded the range of the more widespread T. flavus.     

Comparison and evaluation of the specificity and binding capacity of commercial and in house affinity columns used in sample preparation for analysis of growth-promoting drugs

Immunoaffinity chromatography (IAC) and affinity chromatography (AC) are widely used for extraction of drugs from biological samples. Fifteen column types were purchased from five different manufacturers and their ability to bind specific drugs including β-agonists and anabolic steroids over a range of analyte concentrations in fortified bovine urine samples was assessed. The performance data obtained from these columns were compared with columns produced in this laboratory (in house columns). The in house columns gave the highest recoveries, ranging from 92 to 100% at the 1 ng spiking concentration, for five of the seven analytes assessed. Forty percent (11 of 27) of all the commercial column assessments recorded recoveries of less than 50% even when the lowest spiking concentration was applied (1 ng). For one manufacturer, only one of seven different columns purchased delivered extraction efficiencies greater than 50%. The extraction efficiencies of the clenbuterol columns were the highest with all commercially prepared columns showing at least 50% binding of radiolabelled tracer. Recoveries of -nortestosterone were the lowest. The variability of these products with respect to quality control requires constant monitoring.