Protective effect of vitamins against trichothecene toxicity towardsSaccharomyces cerevisiae

Summary Several trichothecene mycotoxins were shown to inhibit the growth ofSaccharomyces cerevisiae. This effect was most pronounced with the macrocyclic trichothecenes, especially verrucarin A. Much less growth inhibition was observed with T-2 toxin. Verrucarol, diacetoxyscirpenol, acetyl T-2 toxin, HT-2 toxin, T-2 tetraol and neosolaniol were inactive at a concentration of 75 g of toxin per disc. Incubation ofS. cerevisiae with verrucarin A together with vitamins resulted in a decrease in toxicity. Pyridoxine-HCl, Ca-pantothenate, thiamine-HCl and -tocopheryl acetate were amongst the most potent of the vitamins tested which reversed growth inhibition, overcoming the inhibitory potential of the toxins.9 December 1986The authors thank Dr J. Behrend, Makor Company, Israel, for a generous gift of verrucarin A and roridin A.     

Sexual behavior without adult morphogenesis inLocusta migratoria

Summary Injection of azadirachtin into young Vth (=last) instarLocusta hoppers inhibits molt and a considerable portion of the animals survice for more than 40 days as over-aged nymphs; in contrast, the duration of the Vth instar is 8–10 days in normal controls. Males of over-aged nymphs exhibit adult sexual behavior, and injection of juvenile hormone intensifies this behavior. The results demonstrate that the terminal molt leading to morphogenetic adult differentiation is not necessary for an adult behavioral pattern to develop, and/or to become overt, in a hemimetabolous insect.We thank Prof. H. Rembold for a generous gift of azadirachtin and Mr Y. Toren for keeping the locust culture.     

Inverse effect of gibberellin and Amo-1618 on growth,catalase and peroxidase activity in cucumber seedlings

Zusammenfassung Gibberellin beschleunigt das Wachstum von Hypokotylen bei Gurkensämlingen und verlangsamt die Katalase- und Peroxydasetätigkeit in Hypokotylen und Kotyledonen. Amo-1618 verlangsamt das Wachstum, beschleunigt jedoch die Tätigkeit dieser Enzyme in Hypokotylen, Kotyledonen und Wurzelanlagen. Das Ausmass der durch Gibberellin verursachten Verlangsamung, bzw. der durch Amo-1618 verursachten Beschleunigung stand zum Effekt auf die Hypokotyl-Elongation in entsprechender Konzentrationsabhängigkeit. Gleichzeitige Anwendung beider Substanzen führte zu Aufhebung des Retardierungseffektes.     

Prianicin A and B,nor-sesterterpenoid peroxide antibiotics from red sea sponges

Summary The antibiotic properties of 2 acidic C₂₄H₄₀O₄ nor-sesterterpenoid peroxides, prianicin A (1) and B (2), against gram-positive and gram-negative bacteria, and against fungi are herein described. They are 4–10 times more effective than tetracycline againstbeta hemolytic Streptococcus, but significantly non-effective against a variety of gram-negative bacteria.Acknowledgment. The authors are grateful to Prof. A. Kjaer of the Organic Chemistry Department of the Technical University of Denmark, for his help and fruitful discussions.     

Protective effect of vitamins against trichothecene toxicity towards Saccharomyces cerevisiae

Several trichothecene mycotoxins were shown to inhibit the growth of Saccharomyces cerevisiae. This effect was most pronounced with the macrocyclic trichothecenes, especially verrucarin A. Much less growth inhibition was observed with T-2 toxin. Verrucarol, diacetoxyscirpenol, acetyl T-2 toxin, HT-2 toxin, T-2 tetraol and neosolaniol were inactive at a concentration of 75 micrograms of toxin per disc. Incubation of S. cerevisiae with verrucarin A together with vitamins resulted in a decrease in toxicity. Pyridoxine-HCl, Ca-pantothenate, thiamine-HCl and alpha-tocopheryl acetate were amongst the most potent of the vitamins tested which reversed growth inhibition, overcoming the inhibitory potential of the toxins.     

Increasing p16INK4a expression decreases forebrain progenitors and neurogenesis during ageing

Mammalian ageing is associated with reduced regenerative capacity in tissues that contain stem cells. It has been proposed that this is at least partially caused by the senescence of progenitors with age; however, it has not yet been tested whether genes associated with senescence functionally contribute to physiological declines in progenitor activity. Here we show that progenitor proliferation in the subventricular zone and neurogenesis in the olfactory bulb, as well as multipotent progenitor frequency and self-renewal potential, all decline with age in the mouse forebrain. These declines in progenitor frequency and function correlate with increased expression of p16INK4a, which encodes a cyclin-dependent kinase inhibitor linked to senescence. Ageing p16INK4a-deficient mice showed a significantly smaller decline in subventricular zone proliferation, olfactory bulb neurogenesis, and the frequency and self-renewal potential of multipotent progenitors. p16INK4a deficiency did not detectably affect progenitor function in the dentate gyrus or enteric nervous system, indicating regional differences in the response of neural progenitors to increased p16INK4a expression during ageing. Declining subventricular zone progenitor function and olfactory bulb neurogenesis during ageing are thus caused partly by increasing p16INK4a expression.     

Some Characteristics ofOchromonas hemolysins

Résumé On a observé que les hémolysines d'Ochromonas malhamensis ont été tendues inactives par differentes protéines. Ce sont les enzymes du foiedu rat qui ont apparemment détruit les hémolysines. Cette observation peut expliquer l'absence de mortalité chez les souris et les rats pendant l'injection d'hémolysines.

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This research has been financed in part by Grant No. FG-IS-176 made by the United States Department of Agriculture under P. L. 480.