The activity of monoamine oxidases A and B in gamma-irradiated rabbit brains

Summary The activities of monoamine oxidases A and B towards 5-hydroxytryptamine and -phenethylamine, respectively, were compared in the left and right caudatus, hippocampus, parietal cortex, cerebellum and frontal cortex 6 months after gamma-irradiation (single dose of 23 Gy) of either the right hemisphere or of the whole rabbit brain (in which case, a dose of 16 Gy). No difference in monoamine oxidase A or B activities were found in any of the brain regions.Acknowledgment. This study was supported by grants from the Swedish Medical Research Council (12x–5664 and 04x–4145), Hansson's, Lion's, Mångberg's and Sundblad's funds.     

Hsp104 is a highly conserved protein with two essential nucleotide-binding sites

Most eukaryotic cells produce proteins with relative molecular masses in the range of 100,000 to 110,000 after exposure to high temperatures. These proteins have been studied only in yeast and mammalian cells. In Saccharomyces cerevisiae, heat-shock protein hsp104 is vital for tolerance to heat, ethanol and other stresses. The mammalian hsp110 protein is nucleolar and redistributes with growth state, nutritional conditions and heat shock. The relationships between hsp110, hsp104 and the high molecular mass heat-shock proteins of other organisms were unknown. We report here that hsp104 is a member of the highly conserved ClpA/ClpB protein family first identified in Escherichia coli and that additional heat-inducible members of this family are present in Schizosaccharomyces pombe and in mammals. Mutagenesis of two putative nucleotide-binding sites in hsp104 indicates that both are essential for function in thermotolerance.     

A yeast prion provides a mechanism for genetic variation and phenotypic diversity

A major enigma in evolutionary biology is that new forms or functions often require the concerted effects of several independent genetic changes. It is unclear how such changes might accumulate when they are likely to be deleterious individually and be lost by selective pressure. The Saccharomyces cerevisiae prion [PSI+] is an epigenetic modifier of the fidelity of translation termination, but its impact on yeast biology has been unclear. Here we show that [PSI+] provides the means to uncover hidden genetic variation and produce new heritable phenotypes. Moreover, in each of the seven genetic backgrounds tested, the constellation of phenotypes produced was unique. We propose that the epigenetic and metastable nature of [PSI+] inheritance allows yeast cells to exploit pre-existing genetic variation to thrive in fluctuating environments. Further, the capacity of [PSI+] to convert previously neutral genetic variation to a non-neutral state may facilitate the evolution of new traits.     

Highly purified noradrenaline storage vesicles from bovine splenic nerve trunk: Preliminary electron microscopy

Résumé Les vésicules de la NA du nerf splénique de Buf ont été obtenues par gradient de centrifugation («sucrose-heavy water»), Le rapport NA/protéine observé est de 4 à 7 fois plus élevé que celui qui a été mentionné précédemment. L'examen préliminaire de cette fraction, par microscopie électronique, révèle une couche importante et pratiquement pure de vésicules à la surface du sédiment.

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Supported by Research Career Program Award No. 5-K03-HE-0592 from the Nat. Heart and Lung Inst. and Research Grant No. 5-R01-GM15490 from the Nat. Inst. Gen. Med. Sci., U.S.P.H.S.

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Supported by the Swedish Medical Research Council No. K70-14X-2479-03A and Knut and Alice Wallenbergs Foundation.     

Evidence for the participation of the preoptic area in male mating behaviour

Zusammenfassung Bei Ratten kann durch kleine, umschriebene elektrolytische Läsionen basal in der präoptischen Area das typische Verhalten der männlichen Tiere im Coitus sowohl beim Weibchen als auch beim Männchen ausgelöst werden. Diese Reaktionen werden offenbar durch einen rein neuralen Mechanismus hervorgerufen und scheinen in weitem Masse unabhängig von der Stimulation durch Sexualhormone.