Structural characterization of the human B lymphocyte-restricted differentiation antigen CD22. Comparison with CD21 (complement receptor type 2/Epstein-Barr virus receptor)

CD22 and CD21 are glycoproteins primarily expressed on normal and neoplastic human B cells. The surface expression of these two molecules parallel each other during normal B cell differentiation, and the reported relative mobilities for CD22 and CD21 are 130/140 kDa and 140 kDa, respectively. Herein we present a detailed analysis of the biosynthesis and structure of CD22 and also compare it directly to CD21. Electrophoresis under reducing and nonreducing conditions suggested that CD22 and CD21 may have similarities in intra-chain disulfide bond formation. Biosynthesis and processing of CD22 and CD21 were very similar with respect to kinetics and post-translational modification, and both could be phosphorylated. However, endoglycosidase digestion (using N-glycanase and endoglycosidase H) and peptide mapping (using V8 protease and N-chlorosuccinimide) strongly suggested that CD22 and CD21 are distinct gene products.     

A novel sickle cell mutation of yet another origin in Africa: the Cameroon type

Summary The sickle cell mutation (^s) arose as at least three independent events in Africa and once in Asia, being termed the Senegal, Benin, Bantu and Indian types respectively. An investigation in Cameroon was carried out to determine whether the atypical sickle genes observed in the neighboring countries are the result of recombination or the presence of a sickle cell mutation of a different genetic origin. It was conducted on 40 homozygous SS patients followed at the Blood Transfusion Center in the capital city of Yaoundé. On 80 ^s chromosomes, 13 exhibited a novel polymorphic pattern that was observed three times in the homozygous state. This chromosome contains an ^AT gene. The restriction fragment length polymorphism haplotype is different from all the other ^s chromosomes in both the 5 and 3 regions, but has previously been reported in sporadic cases. The (AT)8(T)5 sequence in the — 500 region of the gene is specific and different from that of the Senegal, Benin, Bantu or Indian ^s genes. All the carriers of this specific chromosome belong to the Eton ethnic group and originate from the Sanaga river valley. This observation strongly argues for yet another independent origin of the sickle cell mutation in Africa, here referred to as the Cameroon type. The Benin haplotype and a Benin/ Bantu recombinant haplotype have been observed in the other studied populations: Ewondo, Bamiléké, Bassa, Yambassa and Boulou.     

Interaction of ovomucoid from duck egg proteins with aldehydes-dextrans]

The interaction of ovomucoid proteinase inhibitor prepared from duck egg white with a dextran of a molecular weight of 70,000 preliminary treated with potassium periodate. Irrespective of the number of the sites of the ovomucoid binding to aldehyde-dextran the anti-chymotryptic activity is equal to that of the native inhibitor, while the antitryptic activity decreases proportionally to the number of ovomucoid amino groups involved in the reaction with dextran. When a few ovomucoid molecules are immobilized on the polysaccharide macromolecule the perturbing effect of the protein-protein interactions is minimal, as the rigid polymeric chain prevents from the formation of associates of proteins immobilized on this backbone.     

Increased preproenkephalin A gene expression in the rat heart after induction of a myocardial infarction.

The expression of preproenkephalin A (ppENK) gene was investigated in the rat heart, following the onset of myocardial infarction induced by ligation of the left anterior descending coronary artery. The relative abundance of ppENK mRNA and the level of enkephalins were measured by Northern blot analysis and radioimmunoassay, respectively, in the ventricles from control-unoperated, sham-operated, and operated rats. Three hours after the surgery, a comparison between rats with infarction and sham-operated rats revealed that the relative abundance of ppENK mRNA and the level of enkephalins were increased three- to four- and two- to three-fold, respectively, in the ventricles of rats with infarction. No difference was observed between rats with infarction and sham-operated rats 24 h after the surgery, or between rats with infarction compared at time intervals of 3 and 24 h following the surgery. The abundance of the ppENK mRNA in the polysomal fraction of the ventricular septum was also measured 3 h after the surgery and found to be threefold higher in rats with infarction as compared with sham-operated rats. These results indicate that the level of enkephalins rapidly increases in the ventricles of rats following myocardial infarction, and that this higher level may be ascribed to a stimulation of the local synthesis of enkephalins.     

Identification of a CA repeat at the TCRA locus using yeast artificial chromosomes: a general method for generating highly polymorphic markers at chosen loci.

The creation of a comprehensive genetic map in human has been limited by the lack of highly polymorphic markers spaced evenly throughout the human genome. We have utilized yeast artificial chromosomes (YAC) containing large human DNA inserts to help identify highly polymorphic (CA)n repeats at a chosen locus. The DNA of a YAC containing the locus was subcloned in M13 vectors, and the recombinants were screened at high stringency to detect preferentially long (CA)n repeats (n greater than 20). These repeats, which are the most likely to be highly polymorphic, were then studied to confirm both the level of polymorphism and their precise genetic location. This strategy has permitted the identification of a new, highly polymorphic CA repeat (77% heterozygosity) at the T cell receptor alpha chain (TCRA) locus on chromosome 14q. It provides a powerful marker for assessing the role of this locus in the susceptibility to autoimmune and infectious diseases. This approach should permit the development of highly polymorphic markers at any targeted locus and rapidly improve the current human genetic map.     

Genetic mapping of three human homologues of murine t-complex genes localizes TCP10 to 6q27, 15 cM distal to TCP1 and PLG

Human homologues of mouse t-complex genes have been cloned and localized physically to chromosome 6p or 6q. TCP1, TCP10, and PLG are human homologues of genes located in the proximal portion of the t-complex on mouse chromosome 17. We present here results of genetic mapping of these human t-complex homologues previously localized to 6q25-q27, 6q21-q27, and 6q26-q27, respectively, by physical techniques. TCP1 and PLG do not recombine with each other and are separated from TCP10 by about 15 cM, while the corresponding mouse genes are no more than 4 cM apart. Genetic mapping with markers well localized cytogenetically places TCP1 and PLG proximal to TCP10 and localizes the latter to the cytogenetic band 6q27. It is likely that the organization of human t-complex homologues on 6q is similar to that of t haplotypes rather than that of wildtype murine chromosome 17.     

Quinovic acid glycosides from Uncaria guianensis.

From the bark of Uncaria guianensis, two new quinovic acid glycosides, quinovic acid 3 beta-O-beta-D-quinovopyranoside and quinovic acid 3 beta-O-beta-D-fucopyranosyl-(27----1)-beta-D-glucopyranosylester, have been isolated, in addition to known quinovic acid 3 beta-O-[beta-D-glucopyranosyl-(1----3)-beta-D-fucopyranosyl]-(27----1)- beta-D-glucopyranosylester and quinovic acid 3 beta-O-beta-D-fucopyranoside. Their structures were elucidated by spectral and chemical studies.     

Floral morphogenesis in Anagallis: Scanning-electron-micrograph sequences from individual growing meristems before,during, and after the transition to flowering

Non-destructive scanning electron microscopy allows one to visualize changing patterns of individual cells during epidermal development in single meristems. Cell growth and division can be followed in parallel with morphogenesis. The method is applied here to the shoot apex of Anagallis arvensis L. before, during, and after floral transition. Phyllotaxis is decussate; photoperiodic induction of the plant leads to the production of a flower in the axil of each leaf. As seen from above, the recently formed oval vegetative dome is bounded on its slightly longer sides by creases of adjacent leaf bases. The rounded ends of the dome are bounded by connecting tissue, horizontal bands of node cells between the opposed leaf bases. The major growth axis runs parallel to the leaf bases. While slow-growing at the dome center, this axis extends at its periphery to form a new leaf above each band of connecting tissue. Connecting tissue then forms between the new leaves and a new dome is defined at 90° to the former. The growth axis then changes by 90°. This is the vegetative cycle. The first observed departure from vegetative growth is that the connecting tissue becomes longer relative to the leaf creases. Presumably because of this, the major growth axis does not change in the usual way. Extension on the dome continues between the older leaves until the axis typically buckles a second time, on each side, to form a second crease parallel to the new leaf-base crease. The tissue between these two creases becomes the flower primordium. The second crease also delimits the side of a new apical dome with the major axis and growth direction altered by 90°. During this inflorescence cycle the connecting tissue is relatively longer than before. Much activity is common to both cycles. It is concluded that the complex geometrical features of the inflorescence cycle may result from a change in a biophysical boundary condition involving dome geometry, rather than a comprehensive revision of apical morphogenesis.Abbreviation SEM scanning electron microscopy, micrograph Use of the SEM facility of Professor G. Goffinet, Institute of Zoology, University of Liège, is greatly appreciated. We thank Dr. R. Jacques, C.N.R.S., Le Phytotron, Gif-sur-Yvette, France, for providing the experimental material, and Mr. Philippe Ongena for expert photography. Support was from grants from the U.S. Department of Agriculture and National Science Foundation as well as from the Fonds National de la Recherche Scientifique, Fonds de la Recherche Fondamentale et Collective, and the Action de Recherche Concertée of Belgium.