Structural and functional alterations induced by two sulfonamide antibiotics on barley plants.

Synthetic veterinary medicines are introduced routinely in the environment after animal treatment to prevent and control infectious diseases and up to 80% the administered dose can be excreted unaltered. As a consequence, the soil is the environment most contaminated by such molecules. However, information about their implications on the growth of vegetal organisms is still scarce. With the aim of better elucidating the effects of veterinary antibiotics on plants, barley was grown in a nutrient solution containing 40 µM (about 11,500 µg L(-1)) of two well-known sulfonamide antibiotics, sulfadimethoxine (SDM) and sulfamethazine (SZ). After 15 d of treatment, the effects on root apparatus were particularly evident, while the photosynthetic tissues remained almost unaffected. SDM and SZ stimulated root hairs and lateral root development a few mm behind the root tips. In particular, from a structural point of view, treated plants showed root shortening and an advanced differentiation in comparison to controls, later confirmed using light microscopy. At a functional level, the two active molecules were found to induce root electrolyte release, such as K(+), possibly due to an impairment of membrane permeability. The research concludes that sulfonamides can have profound effects on morphology and functionality of roots of crop plants. As these alterations might have consequences on their productivity, further studies are necessary to assess effects on plants at laboratory and field conditions.

Oxidation versus Reductive Detoxification of SO(2) by Chloroplasts.

Intact chloroplasts isolated from spinach (Spinacia oleracea L. cv Yates) both oxidized and reduced added sulfite in the light. Oxidation was fast only when endogenous superoxide dismutase was inhibited by cyanide. It was largely suppressed by scavengers of oxygen radicals. After addition of O-acetylserine, chloroplasts reduced sulfite to cysteine and exhibited sulfite-dependent oxygen evolution. Cysteine synthesis from sulfite was faster than from sulfate. The results are discussed in relation to species-specific differences in the phytotoxicity of SO(2).

Differences in chlorophyll-protein complexes and composition of polypeptides between thylakoids from bundle sheaths and mesophyll cells in maize.

Thylakoids from enzymatically separated bundle sheath and mesophyll tissue chloroplasts were examined for their chlorophyll-proteins by tube sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE). Differences were found in distribution of chlorophyll among peaks. The chlorophyll-protein a peak (CPa), considered to be the photosystem II (PSII) reaction centre by many authors, was seen to be absent in bundle sheath thylakoid samples. The slab SDS-PAGE revealed the absence of the polypeptides present in PSII preparations of chloroplast subfractions having only PSII activity. This finding confirms Anderson's hypothesis of the structure of grana and stroma thylakoids.

[Monitoring of laborers previously exposed to aromatic amines, in accordance with Circulars No. 46 of 12/6/1979 and No. 61 of 4/6/1981 of the Ministry of Labor]. / Problematiche del monitoraggio dei lavoratori ex esposti ad amine aromatiche in seguito alle circolari no 46 del 12/6/1979 e no 61 del 4/6/1981 del ministero del lavoro.

The present report deal, a year after its beginning, with the results of a programme for health control regarding 592 ex-employees of Società Bergamasca Industrie Chimiche. Azo dyes were obtained from benzidine and beta-naphthylamine in this factory from 1947 to 1968. The report analyses the organizing difficulties and the troubles which caused a scarce performance of the programme at different levels: the subjects interested in the control, the Commission responsible for the district, the doctors in charge, the laboratories, the hospital division. In the end some proposals are advanced referring to the provision of the ministerial circular letter no 46, dated june 12, 1979, about the medical control of workers who leave the hazardous working job.