Xanthine oxidase activity in regenerating liver

The xanthine oxidase activity of mouse regenerating liver has been shown to be elevated during the period of rapid liver growth and proliferation. This increase is evident when the enzyme activity is expressed per unit wet tissue weight, per unit nitrogen, or per cell. The adrenal cortex probably plays only a minor role in implementing this phenomenon. Further augmentation of the xanthine oxidase level of regenerating liver is not induced by the administration of large quantities of the substrate, xanthine, to the animal.     

Characterization of Plant Alcohol Dehydrogenase

The final activity of the alcohol dehydrogenase (E.C.1.1.1.1, abbreviated ADH) from germinating pea, isolated by fractionating with ammonium sulphate, chromatography on DEAE cellulose and gel filtration, was 80,000, from bean 25,000 and from lentil 13,500 units per mg protein. Molecular weights of the ADHs are close to each other: pea and bean ADH 60,000, lentil ADH 70,000. The K_m values are mutually similar with three enzymes, i.e. of the order of 10⁻⁴M for NAD and 10⁻²M for ethanol. The pH optima lie in the alkaline region. These enzymes catalyse oxidation of a number of monovalent alcohols. At temperatures above 60°C the enzymes are thermally unstable. Stability is enhanced slowly by ethanol but not by NAD. Pyrazol, imidazol and pyridine inhibit plant ADH similarly to the enzyme from horse liver. There is a similarity between plant alcohol dehydrogenases and animal and yeast enzymes.     

LOPHOSTEUS SUPERBUS PANDER: ZÄHNE, ZAHNKNOCHEN UND BESONDERE SCHUPPENFORMEN

Morphological and histological studies of numerous remains of Lophosteus superbus Pander from erratic boulders of Beyrichia Limestone prove that the peculiar teeth recently brought to notice by Gross (1969) belong to Lophosteus and are not of acanthodian origin. The structure of these teeth as well as that of some tooth-bearing bones and scales is described. The investigation was extended to cover the teeth of smaller Devonian actinopterygians and cross-opterygians to establish whether Lophosteus is an actinopterygian, a crossopterygian, or even a member of a hitherto unknown group of Osteichthyes. Results unfortunately proved negative, as the very small teeth of various species offer too few distinct and symptomatic histological characteristics. A solution of this question must await the discovery of determinable skull and lower jaw bones of the genus Lophosteus.
Die morphologische und histologische LTntersuchung zahlreicher in nordwest-deutschen Geschieben des Beyrichienkalkes gefundener Reste von Lophosteus superbus Pander beweist, daß die kürzlich von Gross (1969) erwähnten, eigenartigen und nicht von Acanthodiern stammenden Zähne zu Lophosteus gehören. Der Bau der Zähne und einiger Zahnknochen und Schuppen wird beschrieben. Um die Fragen zu klaren, ob Lophosteus zu den Actinopterygiern oder zu den Crossopterygiern gehört oder gar zu einer bisher unbekannten Gruppe der Osteichthyes, wurde die Untersuchung auch auf die Zähne kleiner devonischer Actinopterygier und Crossopterygier ausgedehnt. Das Ergebnis war leider negativ: die sehr kleinen Zähne der verschiedenen untersuchten Arten bieten zu wenig kennzeichnende und unterscheidende histologische Merkmale. Nur von der Entdeckung bestimmbarer Schädel- und Unterkiefer-Knochen der Gattung Lophosteus kann die Entscheidung dieser Frage erhofft werden.     

Carotenoid Distribution in Bleached Substrains of Euglena gracilis

SYNOPSIS. Several substrains of Euglena gracilis var. bacillaris made chlorotic by treatment with pyribenzamine or streptomycin, or by growth at high temperature (35–36°C.), have been examined for their carotenoid content. They differ from the normal green strain both qualitatively and quantitatively. Some strains produce no detectable carotenoids while the carotenoid concentration in the strains producing most is at best only one-fifth that of the normal strain. In all substrains producing carotenoids, the carotene fraction consists of β-carotene accompanied by some members of the phytofluene series. In only two of these substrains, HB-G and PBZ-G3, are xanthophylls produced in significant amounts. In HB-G, the main pigment is echinenone, and in PBZ-G3 it is zeaxanthin. The significance of these findings is briefly discussed.     

Über das Gebiss der Acanthodier und Placodermen

In their dentition, acanthodians and placoderms differ from other fishes by the ontogenetie development and replacement of their teeth and by the histology of the functional elements (teeth, cutting edges of the jaws). In some cases special diets are indicated. In general, however, their dentition seems to have been less effective than that of elasmobranchs and teleostomes. This fact may partly account for their early extinction.
Die Eigenart des Gebisses der Aoanthodier und Placodermen inbezug auf die Zahnbildung (Ontogenese), den Zahnersatz und den histologischen Bau der funktionalen Elemente (Zähne, Schneidekanten des Kieferknochens) wird dargestellt. Aus dem Bau des Gebisses läßt sich die Nahrung dieser Tiere teilweise erschließen. Das eigenartige Gebiß verursaehte vermutlich eine Konkurrenzunterlegenheit beim Nahrungserwerb gegenüber den Elasmobranchiern und Teleostomen, vielleicht einer der Gründe, der zum frühen Aussterben der Acanthodier und Placodermen führte.     

A new cardiid bivalve from the Pliocene Baklan Basin (Turkey) and the origin of modern Ponto‐Caspian taxa

Abstract: We present the first record of the cardiid genus Monodacna from the Pliocene of Anatolia, Turkey. Monodacna imrei sp. nov. was found in the Pliocene Killik Formation from the western margin of the Baklan Basin, in very marginal brackish to freshwater lacustrine deposits. The new record extends the stratigraphic range of the modern Ponto‐Caspian genus back into the Pliocene and adds to earlier evidence that modern Ponto‐Caspian taxa originated in the Pliocene of south‐western Turkey.