The structure of a spherical plant virus (bromegrass mosaic virus) established by neutron diffraction.

The localization of the RNA in a spherical plant virus is established by neutron diffraction. For BMV, this localization is different at low pH than it is at high pH (swollen virus).     

Partial trisomy 15q1

Summary A supernumerary extra chromosome of maternal origin, precisely described from QM- and C-banding patterns, was studied in a mentally defective boy with a severe convulsive disorder. This case is considered to represent a specific phenotype of trisomy 15q1. The suggestion that in cases of partial trisomy 15q different phenotypes are due to the second chromosome involved in interchange is supported by the observation of a tertiary trisomy in 2 sibs. It resulted from a balanced reciprocal translocation in the mother t(8q+15q-) and caused an unusual malformation syndrome (mental deficiency, cleft lip and palate, funnel chest, hypospadias).     

Somatostatin-induced inhibition of insulin secretion from isolated islets of rat pancreas in presence of glucagon.

In order to study the oeffect of somatostatin on the endocrine pancreas directly, islets isolated from rat pancreas by collagenase were incubated for 2 hrs 1) at 50 and 200 mg/100 ml glucose in the absence and presence of somatostatin (1, 10 and 100 mg/ml) and2) at 200 mg/100 ml glucose together with glucagon (5 mug/ml), with or without somatostatin (100 ng/ml). Immunologically measurable insulin was determined in the incubation media at 0, 1 and 2 hrs. Insulin release was not statistically affected by any concentration stomatostatin. On the other hand, somatostatin exerted a significant inhibitory action on glucagon-potentiated insulin secretion (mean +/- SEM, mu1/2 hrs/10 islets: glucose and glucagon: 1253 +/- 92; glucose, glucagon and somatostatin: 786 +/- 76). The insulin output in th epresence of glucose, glucagon and somatostatin was also significantly smaller than in thepresence of glucose alone (1104 +/- 126) or of glucose and somatostatin (1061 +/- 122). The failure of somatostatin to affect glucose-stimulated release of insulin from isolated islets contrasts its inhibitory action on insulin secretion as observed in the isolated perfused pancreas and in vivo. This discrepancy might be ascribed to the isolation procedure using collagenase. However, somatostatin inhibited glucagon-potentiated insulin secretion in isolated islets which resulted in even lower insulin levels than obtained in the parallel experiments without glucagon. It is concluded that the hormone of the alpha cells, or the cyclic AMP system, might play a part in the machanism of somatostatin-induced inhibition of insulin release from the beta-cell.     

The activation of adrenal cortex mitochondrial malic enzyme by Ca2+ and Mg2+.

Adrenal cortex mitochondria prepared by a standard method do not exhibit malic enzyme activity. Addition of physiological concentrations of Ca2+ and Mg2+ enables these mitochondria to reduce added NADP+ by malate to form free NADPH. Half-maximum activation of the mitochondrial malic enzyme requires 0.3 mM Ca2+ and 1 mM Mg2+. Solubilized mitochondrial malic enzymes is independent of Ca2+ and has a K M of 0.2 mM for Mg2+. The Ca2+ effect is dependent on an initial period of active Ca2+ uptake which also causes other changes in respiratory properties similar to those observed with mitochondria from other tissues. After Ca2+ accumulation has taken place, free Ca2+, but not additional accumulation, is still required for malic enzyme activity. The requirement for Mg2+ can be met by Mn2+ (1 mM). This concentration of Mn2+ alone yielded only a slight activation of mitochondrial malic enzyme while higher concentrations of Mn2+ alone gave good activation of the mitochondrial malic enzy.e The NADPH generated by the Ca2+-Mg2+ activated malic enzyme effectively supports the 11beta-hydroxylation of deoxycorticosterone, whereas in the presence of malate, or malate plus Mg2+ but absence of Ca2+, the energy linked transhydrogenase supplies all the required NADPH. The activated malic enzyme appears to be more efficient than transhydrogenase in generating NADPH to support 11beta-hydroxylation. Cyanide and azide have been found to inhibit solubilized mitochondrial malic enzyme.     

Die Plasmo- und Karyoskopie im auffallenden Lichte in ihrer Bedeutung für die botanische Zytologie und Protoplasmaforschung

Ohne ZusammenfassungDer Inhalt dieser Mitteilung ist zum größeren Teile auf der Tagung der Deutschen Botanischen Gesellschaft anläßlich ihres 50jährigen Bestehens zu Berlin am 19. Mai 1932 vorgetragen worden, weswegen sich die hier mitgeteilten Ergebnisse ganz auf botanische Objekte beschränken.     

Anwendung der Schwebemethode zur Bestimmung des spezifischen Gewichts isolierter Zellkerne

Ohne Zusammenfassung     

Kleine Beiträge zur Bestimmung des IEP von Protoplasten

Zusammenfassung Die Keimung der kugeligen, glatten, möglichst durchsichtigen und weitlumigen Pollen hauptsächlich vonBetula verrucosa, Alopecurus pratensis, Melandryum album,Phaseolus multiflorus undUrtica dioica ist in Abhängigkeit von der extrazellularen C_H in mit 1 % Agar versetzten Rohrzuckerlösungen, welche mittels HCl- oder NaOH-Zusatz eine wechselnd abgestufte C_H bekommen haben, untersucht worden. Das für bestimmte Reaktionsbereiche gefundene Keimungsminimum ist wegen der Ergebnisse von Paralleluntersuchungen über die je nach der C_H des Mediums wechselnde Refraktion n_s der Objekte als der Zone des IEP ihrer Protoplasten benachbart gedeutet worden.Neben den experimentell durch refraktometrische Messungen gestützten Erörterungen sind theoretische Betrachtungen über den C_H-Einfluß auf die Pollenkeimung und über das in dem C_H-Bereich um den IEP zu erwartende Keimungsverhalten der Pollen angestellt und in Übereinstimmung mit den experimentellen Resultaten befunden worden.Die Ausführung weiterer Vergleichsverfahren zum Aufsuchen des IEP der Pollen, auch solcher an Pollen weniger eng begrenzter Vorbedingungen, ist zurückgestellt worden.     

Experimentelle und theoretische Untersuchungen über die Entdifferenzierung und Teilung pflanzlicher Dauerzellen

Ohne Zusammenfassung     

Doppelbrechung und Orientierungsrate der Leptonen fließenden Protoplasmas

Summary At defined speeds threads of protoplasm have been drawn out mechanically from a fusion of isolated gymnoplasts using an experimental arrangement described by Gerendás [3]. The polarization device, as well as the method of measuring the birefringence by means of a variable azimuth compensator of fixed retardation, viz. a rotating /30-mica plate, is the same as described formerly [7g-i. Then in dependence on the variable speeds of formation the protoplasmic threads show a different intensity of negative birefringence, and, what is more, it is found a distinct parallelism between birefringence, as an expression of the orientation rate of the leptones, and the speed of spinning. Always when a birefringent gel like protoplasm is put under tension, the intensity of its original birefringence or its orientation rate increases (and in the reverse order). It is to conclude that in order to analyse the leptonic structures in dependence on the effective forces, there is a great need for a quantitative approach to the anisotropy of protoplasmic constituents.     

Synthesis of myelin glycosphingolipids (galactosylceramide and galactosyl(3-O-sulfate)ceramide (sulfatide)) by cloned cell lines derived from mouse neurotumors

Clonal cell lines derived from both spontaneous and chemically induced rat and mouse brain tumors were screened for their ability to incorporate H232SO4 into galactosyl(3-O-sulfate)ceramide (sulfatide). High levels of 35SO4 incorporation into sulfatide were found only in two of the mouse cell lines studied (G26-20 and -24). Tumors produced by subcutaneous injection of these cell lines into C57BL/6 mice were also unique in that they contained high levels of both sulfatide and galactosylceramide. The synthesis of large amounts of sulfatide and galactosylceramide by a clonal cell line of neurological origin suggests that the original tumor was of oligodendrocyte or Schwann cell origin. In common with a large number of mouse and rat astrocyte cell strains and their derived tumors, these glial cells lacked the ability to synthesize gangliosides such as monosialotetraglycosylceramide and disialotetraglycosylceramide (as judged by analytical and [3H]GlcNH2 incorporation studies). This appears to be a unique characteristic of neuroblastoma-derived cell strains such as N18, NB2a, and NB41A.