In vitro demonstration of peroxidase activity in the fish kidney soluble supernatant and its physiological importance

Zusammenfassung In der Kopfniere des TeleostiersAnabes testudineus wurde eine besonders hohe Peroxidase-Aktivität nachgewiesen, insbesondere deren Iodid-Oxydation zu Tri-Iodid.     

Cytotoxic T cells specific for the circumsporozoite protein of Plasmodium falciparum

Malaria is initiated by the inoculation of a susceptible host with sporozoites from an infected mosquito. The sporozoites enter hepatocytes and develop for a period as exoerythrocyte or hepatic stage parasites. Vaccination with irradiated sporozoites can provide protective immunity and a recent study shows that this can also be conferred by immunization with a recombinant salmonella expressing only the circumsporozoite protein that normally covers the sporozoites. Protection against infection is likely to be mediated by cytotoxic CD8+ cells, as depletion of CD8+ T cells in a sporozoite-immunized animal can completely abrogate immunity. Here we demonstrate directly the existence of CD8+ cytotoxic T lymphocytes (CTL) that recognize the circumsporozoite protein. B10.BR mice immunized with sporozoites or with recombinant vaccinia virus expressing the CS protein of Plasmodium falciparum contain CTL that specifically kill L cell fibroblasts transfected with the gene encoding the same CS protein. The peptide epitope from the CS protein that is recognized by CTL from this strain of mice is from a variant region of the protein.     

Expression of active human factor IX in transfected cells

Factor IX is the precursor of a serine protease that functions in the intrinsic blood clotting pathway. Deficiencies in this plasma glycoprotein result in haemophilia B (or Christmas disease) and occur in about 1 in 30,000 males. Patients are currently treated with fresh frozen plasma or prothrombin complex concentrates prepared from pooled plasma from normal individuals. There are several problems with this method of treatment, including the probable exposure of the patients to contaminants such as the viral agents responsible for hepatitis and AIDS (acquired immune deficiency syndrome). As a first step towards an alternative source of pure human factor IX, we report here on the use of recombinant DNA techniques to produce biologically active factor IX in cultured mammalian cells. Stable cell lines were produced by cotransfecting a baby hamster kidney (BHK) cell line with a plasmid containing a gene for factor IX and a plasmid containing a selectable marker. Protein secreted by these cell lines reduces the clotting time of plasma from factor IX-deficient patients. We present additional evidence that this protein is authentic human factor IX.     

Reflection signature of seismic and aseismic slip on the northern Cascadia subduction interface

At the northern Cascadia margin, the Juan de Fuca plate is underthrusting North America at about 45 mm x yr(-1) (ref. 1), resulting in the potential for destructive great earthquakes. The downdip extent of coupling between the two plates is difficult to determine because the most recent such earthquake (thought to have been in 1700) occurred before instrumental recording. Thermal and deformation studies indicate that, off southern Vancouver Island, the interplate interface is presently fully locked for a distance of approximately 60 km downdip from the deformation front. Great thrust earthquakes on this section of the interface (with magnitudes of up to 9) have been estimated to occur at an average interval of about 590 yr (ref. 3). Further downdip there is a transition from fully locked behaviour to aseismic sliding (where high temperatures allow ductile deformation), with the deep aseismic zone exhibiting slow-slip thrust events. Here we show that there is a change in the reflection character on seismic images from a thin sharp reflection where the subduction thrust is inferred to be locked, to a broad reflection band at greater depth where aseismic slip is thought to be occurring. This change in reflection character may provide a new technique to map the landward extent of rupture in great earthquakes and improve the characterization of seismic hazards in subduction zones.     

Hydrolysis of riboflavin by plants

Résumé Il a été prouvé que l'hydrolyse de la riboflavine à l'aide d'une enzyme se produit dans les extraits de plantes appartenant aux familles desLiliacées, Amaryllidacées etCannas (ou Balisier).On a trouvé le lumichrome et le ribitole parmi les produits de l'hydrolyse. La réaction est stchiométrique, les conditions favorisant une activité optimale sont les suivantes: pH 7.4, température 37°, quantités catalytiques de glutathione reduit.     

How do thermophilic proteins deal with heat?

Recent years have witnessed an explosion of sequence and structural information for proteins from hyperthermophilic and thermophilic organisms. Complete genome sequences are available for many hyperthermophilic archaeons. Here, we review some recent studies on protein thermostability along with work from our laboratory. A large number of sequence and structural factors are thought to contribute toward higher intrinsic thermal stability of proteins from these organisms. The most consistent are surface loop deletion, increased occurrence of hydrophobic residues with branched side chains and an increased proportion of charged residues at the expense of uncharged polar residues. The energetic contribution of electrostatic interactions such as salt bridges and their networks toward protein stability can be stabilizing or destabilizing. For hyperthermophilic proteins, the contribution is mostly stabilizing. Macroscopically, improvement in electrostatic interactions and strengthening of hydrophobic cores by branched apolar residues increase the enthalpy change between the folded and unfolded states of a thermophilic protein. At the same time, surface loop deletion contributes to decreased conformational entropy and decreased heat capacity change between the folded and unfolded states of the protein. Received 28 February 2001; received after revision 26 March 2001; accepted 27 March 2001     

Hyper-tetraploids in pea

Summary Cytomorphologically, five hypertetraploids; three hexasomic (4n+2=30), one double pentasomic (4n+1+1=30) and one multiple aneuploid tetraploid (4n+2+1+1+1=33), where isolated in the C₃ generation of pea autotetraploids. Plants with 30 chromosomes were morphologically very distinct from their euploids and characterized by variation in plant height and morphology of leaves. Hexasomic and double pentasomic tetraploids were characterized by the presence of a hexavalent and two pentavalents, respectively. The multiple aneuploid tetraploid showed very vigorous growth and varying frequencies of hexavalents and pentavalents. All the five aneuploids showed high Anaphase-I anomalies; pollen sterility ranged from 50% to 81%.Financial assistance of C.S.I.R., New Delhi, India is acknowledged.     

Radioimmunoassay of progesterone in uterine flushings of buffalo (Bubalus bubalis)

Summary The concentration of progesterone as determined by radioimmunoassay varied in accordance with the phase of ovarian activity.The authers are indebted to Dr. D. Sundaresan, for the encouragement during the course of study. Progesterone antiserum from Dr. B.J.A. Furr is gratefully acknowledged.