The degradation of herbicide atrazine (2-chloro-4-ethylamino-6-isopropylamino-1, 3, 5triazine) by a soil bacterium is reported. The bacterium involved is a species of Nocardia , which utilizes the atrazine as the sole source of carbon and nitrogen. A new metabolite, 4amino-2-chloro-1, 3, 5-triazine, of the degradation of atrazine in the presence of glucose has been identified. The results further substantiated that atrazine can be degraded by soil micro organisms and indicated that deamination can also occur, as well as dealkylation. 4-Amino-2-chloro-1,3,5-triazine did not show phytotoxic activity to oat (Avena sativa L.), demonstrating that deamination insures detoxification. Many of the pesticides introduced into the environment are degraded. The properties of the degradation products are usually dif ferent from those of the parent compound in toxicological activity and in chemical and physical characteristics. It is thus important not only to know how much parent compound remains in the environment but also to identify and quantify the products of degradation and investigate their properties.

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The purpose of this paper is to elucidate the final degradative pathways of atrazine (I) by a Nocardia strain through experiments on the degradation of its metabolite, 4-amino-2-chloro-6isopropylamino-l ,3,5-triazine (Ha). This compound, in the bacterial medium, was transformed into several products identified as 2-chloro-4,6-diamino-l,3,5-triazine (lie), 4-amino-2-hydroxy-6isopropylamino-l ,3,5-triazine (VIII), 4-amino-l ,2-dihydro-l ,3,5-triazin-2-one (IV) and dicyanodiamidine (VII). The formation of (lie) was attributed to a microbial TV-dealkylation, while the detection of (IV) and (VII) was attributed to a chemical degradation of the intermediate 4-amino-2chloro-l,3,5-triazine (III). Compound (III) undergoes rapid hydrolysis and does not accumulate in the culture medium. Onthe basis of the microbial and chemical results, we propose a degradative pathway for atrazine. The study of transformation of "foreign chemicals" has increased in recent years because of the large amount of chemicals introduced in the environment. The transformations of pesticides in the environment may result from the activity of cellular or extracellular components of the biota (microorganisms, algae, higher plants and animals) as well as from chemical and photochemical reactions. It is very difficult to distinguish between these transformations, because all factors are often closely linked. Moreover, the properties of degradation products from pesticides are considerably different from

Daucus carota L. cell lines stably resistant to the herbicide chlorsulfuron (CS) have been isolated according to a stepwise selection. Studies carried out during different selection steps show that the specific activity of the target enzyme acetohydroxyacid synthase (AHAS) increases along with CS resistance. Southern hybridization analysis performed with aBrassica napus AHAS probe in a CS highly-resistant cell line reveals the presence of a greatly amplifiedEcoRI fragment of genomic DNA. This indicates that AHAS overproduction induced by stepwise selection is due to gene amplification. Regenerants from some resistant cell lines maintained the CS-resistant trait at the whole plant level.

Isoelectrofocusing has been used to separate various chlorophyll-protein complexes of photosystem two (PS II). Light-harvesting complexes containing chlorophyll a and chlorophyll b (LHC II) were located in bands having p/s in the region of 4.5. At slightly higher pH other light-harvesting complexes containing little or no chlorophyll b were found. In the most basic region of the isoelectrofocusing gel, were located PS II core complexes characterized by con­taining the proteins of CP47, CP43, D 1, D 2 and α-subunit of cytochrome b559. The number of PS II core bands depended on the particular conditions employed for the separation procedure and in some cases were contaminated by CP 29. It is suggested that this heterogeneity resulting from different protonation states of the PS II. The least-acidic PS II core complex (pI 5.5) was found to bind the herbicides atrazine, diuron and dinoseb. In contrast, a PS II core complex with a p / of 4.9 bound only diuron. Its inability to bind atrazine was shown to be due to the low pH but no such explanation could be found for dinoseb. When atrazine-resistant mutant Senecio vulgaris was used, no binding of radioactive atra­ zine was observed with the PS II cores having a p i of 5.5. It is therefore suggested that the normal atrazine binding observed with PS II cores involves the high affinity site detected with intact membranes. With the PS II cores, however, this site has a reduced affinity probably due to structural modification in the D 1-polypeptide resulting from the isolation procedures.