Seed germination in response to diurnal fluctuations of temperature

Diurnal fluctuations in temperature may initiate or accelerate germination in certain flowering plants, and the effectiveness of the stimulus varies according to the amplitude of fluctuation and the presence or absence of light. Attempts to assess the adaptive significance of the phenomenon, however, have been limited by the scarcity of data for species of contrasted ecology. We report here an investigation of germination responses to fluctuating temperatures, conducted on seeds of herbaceous species collected from native populations near Sheffield. The results suggest that requirements for diurnal fluctuations in temperature are characteristic of the germination of species from particular types of habitat and provide mechanisms which cause seeds to germinate at times and in places favourable for seedling establishment.     

Dissociation of glucocorticoid effects of C-21 steroids at high concentrations in thymocytes

Summary A dissociation between inhibition of RNA synthesis and cell lysis was observed when thymocytes of adrenalectomized rats were incubated with high concentrations of pregn-4-ene-11-ol-3, 20-dione and pregna-1,4-diene-11-ol-3,20-dione. In contrast, no dissociation of these effects was found with the typical glucocorticoids cortisol and corticosterone, nor with their 1,4-diene analogs under the same conditions.Acknowledgments. This work was supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina to the Instituto de Biologia y Medicina Experimental and the Programa de Regulación Hormonal y Metabólica as well as by financial help from the Secretaría de Ciencia y Tecnología.     

Survival and endogenous spleen colonies of irradiated mice after skin wounding and hydroxyurea treatment

Summary Wound trauma-induced survival from radiation may be related to increased mitosis in hematopoietic cells. This is supported by the cell cycle-dependent drug hydroxyurea, which 1. blocked survival of wounded mice injected 2 or 3 days after 900 rad and 2. reduced the number of endogenous CFU-s in wounded mice injected shortly before 700 rad.Supported by the Armed Forces Radiobiology Research Institute, Defense Nuclear Agency, under Research Work Unit MJ00018. Views presented in this paper are those of the authors; no endorsement by the Defense Nuclear Agency has been given or should be inferred.Research was conducted according to the principles enunciated in the Guide for the Care and Use of Laboratory Animals prepared by the Institute of Laboratory Research, National Research Council.     

Structure,biosynthesis and functions of glycoprotein glycans

Since the pioneering work on structure and function of heteroglycans compiled in the classical books edited by A. Gottschalk in 1972¹, there have been several promising developments in glycoconjugate research, as reviewed in this article.In Part 1, contributed by A. Kobata, current knowledge on heteroglycan structures is presented and representative examples taken from higher organisms are given. Part 2, written by J. F. G. Vliegenthart and J. P. Kamerling, covers the most important achievements in methodology: procedures to obtain pure glycans and to analyze their structures. Part 3, contributed by J. Paulson, is devoted to biosynthesis of glycans now describable as pathways since several of the glycosyltransferases have been isolated and analyzed for specificity. In Part 4, contributed by E. Buddecke, current knowledge on functional roles of glycans is presented. It will become apparent that the prerequisite for valid work either in biosynthetic or functional context depends on solid structural information. This is particularly true whenever glycosyltransferase reaction products are being analyzed, or glycans involved in biological functions are investigated. Although in past years, a great deal of important knowledge has been gathered by use of crude glycosidase or glycosyltransferase activities (a notable example is found in reference 2), one may now postulate that glycans implicated in biological reactions should be thoroughly analyzed.This review may familiarize newcomers with the field of glycoconjugate research with special emphasis on glycoprotein glycans. Glycolipids are not included in this article as they have recently been reviewed by S. I. Hakomori³. The reader is also referred to several excellent monographs^4,5 and the Proceedings of the Glycoconjugate Symposia held biannually^6–8.     

Ferredoxin reductase catalyzes styrene oxidation to styrene oxide

Summary The flavoprotein ferredoxin reductase catalyzed the oxidation of styrene to styrene oxide in the presence of NADPH. This reaction was inhibited by the addition of catalase and superoxide dismutase. The addition of the nonheme iron protein ferredoxin partially inhibited styrene oxidation. H₂O₂ was also able to catalyze this reaction when added to the enzyme in the absence of NADPH.Acknowledgments. This work was supported by C.N.R. (National Research Council), Rome, Italy contract No. 79.03197.04.     

Cyclic AMP concentration in the rat's preoptic region

Summary In rats adapted to a 1212 h light-dark (LD) schedule, cyclic AMP concentration in the preoptic region showed a L minimum and D maximum. No significant fluctuations were observed in the parietal cortex.Supported by grant No. 79.01946.04 awarded by the National Research Council (CNR), Rome, Italy.     

Structural transformation reactions of anthocyanins

Summary Spectroscopic evidence shows that the flavylium cation (1) undergoes hydroxylation to form the carbinol base (2) and can also deprotonate to form the anhydro (quinonemethane) bases (3a and3b). The anhydro bases hydrate to the carbinol base. The carbinol base above pH 6, or the ionzed carbinol base (2a), undergoes diring fission to produce the cischalcone (4).The editors do not hold themselves responsible for the opinions expressed in the authors' brief reports. — Les auteurs sont seuls responsables des opinions exprimées das ces brèves communications. — Für die Kurzmitteilungen ist ausschliesslich der Autor verantwortlich. — Per le brevi comunicazioni è responsabile solo l'autore. — ë . — Solo los autores son responsables de las opiniones expresadas en estas comunicationes breves.Acknowledgment. This research was supported by a grant from the Welch Food Co., Westfield, NY.     

Occurrence of Hyp3-bradykinin in methanol extracts of the skin of the South African leptodactylid frogHeleophryne purcelli

Summary Methanol extracts of the skin of the South African amphibians belonging to the genusHeleophryne (H. purcelli purcelli, H. purcelli depressa, H. purcelli orientalis, H. natalensis) contain large amounts (20–500 g/g fresh tissue) of Hyp³-bradykinin.Supported by grants from the Consiglio Nazionale delle Ricerche, Italy, and from the Ministry of Education, Japan.