Noradrenergic control of ascorbic acid and glutathione concentrations in brown fat of cold-exposed rats

Ascorbic acid and glutathione concentrations increase in brown fat of cold-exposed rats. This phenomenon can be reproduced by noradrenaline or isoproterenol administration, and thus seems to be under sympathetic control. Histological study shows ascorbic acid storage in brown adipocyte nuclei.     

Noradrenergic control of ascorbic acid and glutathione concentrations in brown fat of cold-exposed rats

Summary Ascorbic acid and glutathione concentrations increase in brown fat of cold-exposed rats. This phenomenon can be reproduced by noradrenaline or isoproterenol administration, and thus seems to be under sympathetic control. Histological study shows ascorbic acid storage in brown adipocyte nuclei.     

Covalent binding of aflatoxin B1 to liver DNA in rats pretreated with ethanol

Summary Male Fischer F-344 rats were given ethanol in the drinking water and/or by single oral administration. Following this, the animals received p.o. 100 ng/kg of the hepatocarcinogen [³H]aflatoxin B₁ (AFB₁). 24 h later, the level of DNA-bound AFB₁ was determined in the liver and was found not to be affected by any type of ethanol pretreatment. A cocarcinogenic effect of ethanol in the liver is therefore unlikely to be due to an effect on the metabolic activation and inactivation processes governing the formation of DNA-binding AFB₁ metabolites.To whom correspondence should be addressed.Acknowledgment. We thank the European Science Foundation for the Toxicology Research Fellowship awarded to M.M.     

Covalent binding of aflatoxin B1 to liver DNA in rats pretreated with ethanol

Male Fischer F-344 rats were given ethanol in the drinking water and/or by single oral administration. Following this, the animals received p.o. 100 ng/kg of the hepatocarcinogen [3H]aflatoxin B1 (AFB1). 24 h later, the level of DNA-bound AFB1 was determined in the liver and was found not to be affected by any type of ethanol pretreatment. A cocarcinogenic effect of ethanol in the liver is therefore unlikely to be due to an effect on the metabolic activation inactivation processes governing the formation of DNA-binding AFB1 metabolites.     

Uptake of aflatoxin B1 by the skin of rats

Zusammenfassung Nachweis der Absorption von Aflatoxin B₁ durch die Rattenhaut. Die toxische Leberwirkung nach der Hautbepinselung entsprach den von anderen Autoren gefundenen Verhältnissen bei peroraler oder intraperitonealer Verabreichung.     

Fungistatic action of aflatoxin B1

Résumé La croissance des plusieurs espèces d'Aspergillus et dePenicillium dans un milieu modifié de Czapek a été inhibitée par l'aflatoxin B₁. Cet arrêt de croissance pourrait être annulé en substituant au nitrate de sodium un extrait de levure comme source d'azote.

---

---

This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture.     

Free radicals and aflatoxin biosynthesis

Summary The addition of some halogenated alkanes (bromotrichloromethane, carbontetrachloride and chloroform) to cultures ofA. parasiticus andA. flavus have shown a high stimulating effect on aflatoxin biosynthesis. When the production of aflatoxin increases during the stimulating effect the peroxidase activity is inhibited.Acknowledgments. Supported by Cassa di Risparmio di Roma, funds from Ministry of Education and Faculty of Science of La Sapienza Rome University.     

Kinetics of transformation of aflatoxin B1 into aflatoxin M1 in lactating mouse: an ELISA analysis

A new enzyme-linked immunosorbent assay (ELISA) was used to study the kinetics of transformation of aflatoxin B1 into aflatoxin M1 in lactating mice. Aflatoxin M1 concentration in the milk samples reached a maximum 30 min after injection of aflatoxin B1 and decreased thereafter. At the maximum time, the levels of aflatoxin M1 in the samples were proportional to the dosages administered. Aflatoxin B1 was also detected in the milk samples but at a lower concentration.     

Uptake of aflatoxin B1 by plastic materials

Zusammenfassung Aflatoxin wird von einigen gebräuchlichen Kunststoffen innerhalb kurzer Zeit in verhältnismässig grosser Menge absorbiert. Die vorliegenden Ergebnisse erlauben es, analytische Fehler bei Verwendung ungeeigneten Materials zur Zirkulation oder Filtration von Aflatoxinlösungen zu vermeiden.

---

---

This is contribution No. 660 of the Euratom Biology Division.     

Resistance to ethidium bromide inAspergillus nidulans

Summary A mutant ofAspergillus nidulans resistant to ethidium bromide was isolated and the semi-dominant gene responsible for this resistance was allocated on linkage group II at 17.42±3.05 units of recombination from thewA₃ gene. The gene also confers cross-resistance to acriflavin, malachite green and crystal violet. It was also shown that riboflavin is antagonistic to the toxic effect of ethidium bromide, at certain concentrations. The mechanisms which could be responsible for the toxic effect of this drug are discussed and compared with those of acriflavin. The use of theEtb ₁ gene in genetical analysis through the parasexual cycle is suggested.Acknowledgements. The authors are thankful to the National Council for the Development of Science and Technology (CNPq) for financial support through PIG-SIP 04/053 FAPESP.     

Production and characterization of antibody against aflatoxin M1

Summary Antibody against aflatoxin M₁ was obtained after immunization of rabbits with bovine serum albumin-afla M₁ oxime conjugate. The antibody has greatest binding efficiency for afla M₁, and was less efficient for afla B₁. Cross-reaction of antibody with aflatoxin Q₁, aflatoxicol, and aflatoxin B_2a was weak. Aflatoxin B₂, G₁, and G₂ and afla B₁-guanine adduct showed almost no cross-reaction with the antibody. The sensitivity of the binding assay for aflatoxin M₁ detection is in the range of 1–10 ng per assay. Detailed methods for the preparation of the conjugate, production of immune serum, and methods for antibody determination are described.Supported by the College of Agricultural and Life Sciences, North Central Regional project NC-129, the University of Wisconsin-Madison, and by Public Health Service research grant number CA 15064 from the National Cancer Institute, NIH.The authors wish to thank Dr R.C. Garner for providing aflatoxin-B-guanine adduct, and Dr Dennis H. Hseih for providing aflatoxicol and aflatoxin Q₁.     

Production and characterization of antibody against aflatoxin M1

Antibody against aflatoxin M1 was obtained after immunization of rabbits with bovine serum albumin-afla M1 oxime conjugate. The antibody has greatest binding efficiency for afla M1, and was less efficient for afla B1. Cross-reaction of antibody with aflatoxin Q1, aflatoxicol, and aflatoxin B2a was weak. Aflatoxin B2, G1, and G2 and afla B1-guanine adducts showed almost no cross-reaction with the antibody. The sensitivity of the binding assay for aflatoxin M1 detection is in the range of 1-10 ng per assay. Detailed methods for the preparation of the conjugate, production of immune serum, and methods for antibody determination are described.