Insect glycobiology: a lectin multigene family in Drosophila melanogaster.

Glycodeterminants play an important role in mediating cellular and cell-substrate interactions during development and immune-related reactions enabling an organism to distinguish self determinants from non-self or modified-self determinants. One of the hallmarks of sugar recognition molecules (lectins) is their wide range of binding activities and their organisation in multigene families. Here we describe a group of Drosophila genes that are possible members of the C-type lectin family.     

Variations in dental measurements between Saguinus species and their systematic relationships.

Multivariate analysis is applied to dental measurements of Saguinus species to analyse their systematic relationships. The shape distance between Saguinus midas midas and S. midas niger is larger than that between S. nigricollis and S. fuscicollis, both of which are generally recognized as valid species. In dental form, S. bicolor is the closest relative of S. midas. S. inustus is not linked to S. leucopus. S. geoffroyi and S. leucopus, as S. inustus shows closer affinity with S. labiatus and S. mystax than with the former 3 species.     

Connectin filaments link thick filaments and Z lines in frog skeletal muscle as revealed by immunoelectron microscopy

In an earlier study connectin, an elastic protein of striated muscle, was found to be associated with "gap filaments" originating from the thick filaments in the myofibril, but it was not clear whether it extends to Z lines or not (Maruyama, K., H. Sawada, S. Kimura, K. Ohashi, H. Higuchi, and Y. Umazume, 1984, J. Cell Biol., 99:1391-1397). In the present immunoelectron microscopic study using polyclonal antibodies against native connectin, we have concluded that the connectin structures are directly linked to Z lines from the thick (myosin) filaments in myofibrils of skinned fibers of frog skeletal muscle. There were five distinct antibody-binding stripes in each half of the A band and two stripes in the A-I junction region. Deposits of antibodies were recognized in I bands and Z lines. We suggest that connectin filaments run alongside the thick filaments, starting from a region approximately 0.15 micron from the center of the A band.     

Mutagenicity of isoquinoline alkaloids, especially of the aporphine type

The mutagenicity of 44 isoquinoline alkaloids was tested in Salmonella typhimurium TA100 and TA98 in the presence or absence of S9 mix. The alkaloids tested included compounds from the isoquinoline, benzylisoquinoline, bisbenzylisoquinoline, monoterpene isoquinoline, berberine, morphinane, hasubanan, benzo[c]phenanthridine and aporphine groups. Among the alkaloids tested, liriodenine was the most potent mutagen for TA100 and roemerine was the most potent for TA98. A clear structure-mutagenicity relationship was observed in a series of aporphine alkaloids (aporphine, dehydroaporphine, 7-oxoaporphine and 4,5-dioxoaporphine), and 10,11-non-substituted aporphines were suggested to exert their mutagenicity through metabolic activation of the 10,11 positions, possibly as the 10,11-epoxides.     

Mutagenicities of xanthone derivatives in Salmonella typhimurium TA100, TA98, TA97, and TA2637

The mutagenicities of naturally occurring xanthones were tested in Salmonella typhimurium TA100, TA98, TA97, and TA2637 by the preincubation method. Xanthydrol, gentisein, gentisin, isogentisin, 1-hydroxy-3,7-dimethoxyxanthone, 1,3,7,-trimethoxyxanthone, desmethylbellidifolin, bellidifolin and dimethylbellidifolin were mutagenic, but unsubstituted xanthone was not mutagenic to TA100, TA98, TA97 and TA2637 with or without a metabolic activation system. The β-O-glucosides, norswertianolin and swertianolin, were only mutagenic when a metabolic activation system containing β-glucosidase was used, and the C-glucoside mangiferin was not mutagenic even with this system.     

Production of recombinant sarcotoxin IA in Bombyx mori cells.

A cDNA for sarcotoxin IA, an antibacterial protein of Sarcophaga peregrina (fleshfly), was inserted into a silkworm baculovirus vector and expressed in Bm-N cells, a line of Bombyx mori cells. When a cysteine proteinase inhibitor, p-chloromercuribenzenesulphonic acid, was present in the culture medium, a significant amount of recombinant sarcotoxin IA accumulated, but without this reagent the product seemed to be degraded in this system. The C-terminus of the recombinant sarcotoxin IA seemed to be glycine, not amidated arginine as found in authentic sarcotoxin IA. Probably, Bm-N cells lack the C-terminal alpha-amidation enzyme.     

ATP-dependent unwinding of the double helix and extensive supercoiling by Escherichia coli recA protein in the presence of topoisomerase

recA protein, which is essential for genetic recombination in Escherichia coli, causes extensive unwinding of the double helix by an ATP-dependent reaction and accumulation of positive supercoiling in closed circular double-stranded DNA. Initiation of the extensive unwinding was largely dependent on homologous single-stranded DNA. Therefore, it is likely that the extensive unwinding is initiated mainly at the site of D-loops. "Nascent D-loops" in which the two DNA molecules did not interwind were also good initiation sites of extensive unwinding. When the concentration of Mg2+ was decreased from the standard conditions for D-loop formation (13 mM MgCl2; the higher Mg2+ condition) to the lower Mg2+ condition (1 to 2 mM MgCl2), extensive unwinding by recA protein was initiated very quickly in the absence of single-stranded DNA. Results showed that this single-stranded DNA-independent initiation of extensive unwinding (i) requires negative superhelicity of the double-stranded DNA and (ii) is a first order reaction with respect to the DNA. These observations suggest that, under the lower Mg2+ condition, the extensive unwinding starts at a transiently denatured site in the negative superhelical DNA. Once initiated, the unwinding by recA protein is propagated extensively, even under conditions that do not allow its initiation. Therefore, the propagation of unwinding is a processive reaction ("processive unwinding"). Previous studies indicated that recA protein promotes "distributive unwinding" of double helix which depends on single-stranded DNA. Therefore, recA protein promotes unwinding of the double helix by either of two distinct pathways. Stress caused by the processive unwinding could explain the dissociation of D-loops and reversible inactivation of the double-stranded DNA in a D-loop cycle.     

Purification and some properties of a lectin from the hemolymph of Periplaneta americana (American cockroach)

A lectin showing specificity for human A-type red blood cells was purified to homogeneity from the hemolymph of the American cockroach Periplaneta americana by affinity chromatography on bovine submaxillary gland mucin. This lectin was a huge molecule with molecular mass of about 1500 kDa, with a single subunit of 30-kDa protein, and required Ca2+ for expression of lectin activity. Electron microscopic examination showed that these molecules were rods with helical structure with an average length of 50.5 nm and width of 10 nm. The molecule was suggested to contain tandemly aligned basic units of 10 nm length.     

Purification and characterization of a neutral protease from rat-liver cytosolic fraction

Rat liver cytosol contains a neutral protease which degrades acetylated hemoglobin and some urea-denatured proteins maximally at pH 7.5. The enzyme was purified to homogeneity by conventional chromatographic techniques. It appears to be a metalloprotease since it is inhibited by EDTA and o-phenanthroline, the metal-depleted enzyme can be reactivated by Co2+, Zn2+, Mn2+, or Mg2+, and it is not inhibited by reagents specific for carboxyl, seryl, or thiol proteases. The enzyme has an apparent molecular weight of 200,000 as determined on Sephacryl S-200 column chromatography, and electrophoresis in sodium dodecyl sulfate showed 3 protein bands corresponding to the molecular weights of 110,000, 74,000, and 40,000.