mon ion (the direct transfer of OH+, although unlikely (Jerina et al., 1971), with generation of a cationoid intermediate serves as an acceptable and reasonable mechanism for this type of enzyme reaction) in the formation of the polar metabolites of aldrin. The aldrin ketone would be the resultant product of a NIH shift. The observed parallel enhancement in the production of dieldrin and trans-aldrin diol (TAD) by p-aminobenzoic acid, as indicated in Table 111, is not inconsistent with the one enzyme proposal. The apparent stimulation by NADPH, which has been previously observed (Yu et al., 1971), suggests a further resemblance to mixed function oxidase systems.Aldrin alcohol formation is best explained by a simple hydration mechanism involving protonation and neutralization by a water molecule. This is not an uncommon reaction, even from a nonenzymatic viewpoint. Since the aldrin alcohol is not formed with the boiled enzyme blank, there appears to be an enzyme which can incorporate a proton (H+) or equivalent species, also forming a cationoid-type intermediate. Subsequent neutralization of this intermediate would afford the aldrin alcohol (possibly both isomers (endo and exo) would be formed if the neutralization reaction is nonstereoselective). The apparent absence of an epoxide hydrase in these pea and bean root systems precludes the intermediacy of dieldrin in the formation of the diols and, therefore, simplifies the metabol-ic picture. I t is likely that further studies of the metabolizing abilities of plants will reveal many metabolizing reactions exhibited by animal systems.

FATE OF BENOMYL IN SOIL cated 1.4% of it to the shoots (Table III). During the same period, radioactivity in the nutrient solutions in which these plants were grown decreased from an average of 86.2% on day 1 to 4.6% on day 7 (Figure 1). Autoradiograms of treated plants showed that most of the radioactivity was concentrated in the roots, lower stem, and leaf sections nearest the stalk, but that some activity was present throughout the plant, including the meristematic tissues.One-month-old sorghum growing in solutions treated with 5 ppm of the compound (Table IV) absorbed 1.8% of the radioactivity and translocated 0.7% of it to the shoots within 1 hr; after 7 days in these treated solutions, the roots contained 42.9% and 1.4% had been translocated to the shoots. When roots of 7-day-treated plants were placed in untreated nutrient solutions, radioactivity leached from the roots to the cultures, indicating that much of the radiolabeled material was present in a free form (Table IV). Autoradiograms of treated plants showed that radioactivity was present in the stems 1 hr after treatment, but only the 7-and 14-day plants showed 14C in the leaf blades, concentrated along the center veins.

No abstract

A rat, given a single oral dose of [14C] cymoxanil, 1‐(2‐cyano‐2‐methoxyimino‐[2‐14C]‐acetyl)‐3‐ethylurea, eliminated 91% of the radioactivity within 72 h. The urine contained 71%, the faeces 11%, and the expired air about 7% of the radiolabel; no 14C residue was found in the internal organs. Greater than 70% of the radioactivity in the urine was identified. The major metabolite was characterised as glycine, both free and conjugated, as hippuric acid and phenylaceturic acid [N‐(phenylacetyl)‐glycine], and probably in the form of polypeptides of low molecular weight. The other metabolites identified included 2‐cyano‐2‐methoxyiminoacetic acid, 2‐cyano‐2‐hydroxyiminoacetic acid and 1‐ethylimidazolidine‐2, 4, 5‐trione. The minor metabolites included succinic acid and 2‐oxoglutaric acid which indicated reincorporation of metabolic 14C. Cymoxanil, as such, was not detected in the urine.