Effects of dynamic impacts on human bones

Flat bones of human skeleton were subjected to dynamic indentation with ball indenters. The impacted surface was studied under high magnification and also by using the technique of multiple beam interferometry. The impulse caused the pile up of material at a little distance from the edge of the indent. The diameter of indent is found to increase as fourth root of the energy of impact. Bone structure also has the tendency to minimize the damage caused by external forces. There was about 90% recovery in deformation in the depth of indents due to internal stresses created inside the bone by the impact.     

Interaction of lentil lectin with human platelets. Evidence against glycoprotein II as aggregation mediator

Human platelets bind on an average of 5 × 10⁵ molecules of lentil lectin/cell with an apparent dissociation constant of 3 × 10^?7 M. The lectin binds mainly to surface glycoprotein II with an apparent molecular weight of 125,000. Lentil lectin neither caused aggregation nor did it inhibit platelet aggregation by other agents. It had no influence on the binding of thrombin to platelets or on thrombin-induced clot retraction. The hypothesis that glycoprotein II mediates platelet aggregation needs reevaluation.     

Post-translational processing of 7S and 11S components of soybean storage proteins

The synthesis and processing of the major storage proteins in soybean cotyledons was studied both in vivo and in vitro. The and subunits of 7S as well as the 11S proteins are synthesized as higher molecular weight-precursors on membrane-bound polysomes. The initial translation products of the 7S are proteolytically cleaved during translation suggesting the removal of a signal peptide as evidenced by the presence of 2 and 2 peptides immunoreactive with 7S antibody in the in vitro chain completion products of the membrane-bound polysomes. This is followed or accompanied by cotranslational glycosylation, which increases their size equivalent to that of initially-synthesized precursors. In vivo pulse-labelled 7S and products are of slightly higher molecular weights than the immunoprecipitable chain-completion products, indicating further post-translational modifications. A slow post-translational processing during a period of 1.5 to 16 h yields the final 7S and glycoproteins.Acidic and basic subunits of the 11S protein appear to be synthesized from common large molecular weight (60K-59K) precursors. Antibodies to the 11S acidic component recognize both acidic and basic domains in the precursor while those raised against basic subunits appear to be specific for that region only. The processing of the 11S precursor is also very slow and occurs post-translationally. This slow rate of processing, coupled with a temporal difference in the synthesis of 7S and 11S components, suggests a highly coordinated mechanism for synthesis and packaging of these proteins into protein bodies during seed development.     

A study of the pollen grains of Amaranthus spinosus Linné and A. Dubius Mart ex Thellung and their hybrids

A pollen-morphology study of Amaranthus spinosus, A. dubius, and their hybrids has been carried out. Three pollen types have been observed, namely (1) Type A: micrograins; (2) Type B: grains with smaller pores; and (3) Type C: grains with larger pores. Type B is characteristic of A. spinosus, Type C of A. dubius, and the micrograins of the hybrids. Pollen size range, and frequency of the various morphotypes serve to throw light on the biosystematics of the plants studied.     

On the induction of umu gene expression in Salmonella typhimurium strain TA1535/pSK1002 by some nitrofurans.

Several nitrofurans were found to induce umu gene expression in Salmonella typhimurium TA1535/pSK1002 as defined on the basis of at least a 2-fold increase of beta-galactosidase activity over the background level. beta-Galactosidase activity increased with increasing concentrations of the chemical, attained a maximum at a concentration which was different for different nitrofurans used, and then gradually decreased with a further increase of the nitrofuran concentration. The umu gene expression test revealed that the genotoxic activity was highest for furazolidone and lowest for 5-nitro-2-furaldehyde.     

Reassessment of the prevalence of heat-stable enterotoxin (NAG-ST) among environmental Vibrio cholerae non-O1 strains isolated from Calcutta, India, by using a NAG-ST DNA probe.

A collection of 521 environmental isolates of Vibrio cholerae which were previously examined by the suckling mouse assay and found to be negative for the heat-stable enterotoxin NAG-ST were reassessed by a recently developed DNA probe for NAG-ST. A total of 12 (2.3%) of the isolates hybridized with the NAG-ST probe. By using a cholera toxin (CT) DNA probe, the CT gene was detected in six of the strains in the collection, although none of the isolates of V. cholerae non-O1 hybridized with both of the toxin probes. All of the NAG-ST and CT probe-positive strains were hemolysin positive. Thirty-fold-concentrated supernatants of the three representative NAG-ST DNA probe-positive V. cholerae non-O1 strains gave positive fluid accumulation ratios in the suckling mouse assay even after heating (100 degrees C for 5 min) and also inhibited the binding of a NAG-ST monoclonal antibody to the bound NAG-ST in a competitive enzyme-linked immunosorbent assay (ELISA). Likewise, all six CT probe-positive V. cholerae non-O1 strains produced in vitro CT when examined by the CT bead ELISA. HindIII digest patterns of chromosomal DNA from the representative NAG-ST gene-positive strains were visually indistinguishable. Between the groups of NAG-ST probe-positive strains examined, there was a variation in the hybridizable fragments, with one group of strains exhibiting a hybridizable fragment similar to that of the NRT 36 reference strain; a smaller HindIII fragment hybridized with the NAG-ST probe in the other group of strains.(ABSTRACT TRUNCATED AT 250 WORDS)     

Developmental profiles of arylsulfatases A and B in rat cerebral cortex and spinal cord.

Arylsulfatases A (EC 3.1.6.1) and B (EC 3.1.6.12) are lysosomal enzymes that can remove sulfate groups from sulfatides and sulfo-glycosaminoglycans, respectively. The activities of these enzymes in cerebral cortex and in spinal cord of developing rat pups were measured. The tissues were homogenized and the arylsulfatases A and B in the soluble fraction were separated from each other by anion exchange chromatography on DE-52 cellulose. Subsequently, the enzyme activities were assayed with p-nitrocatechol sulfate as substrate at 37 degrees C and pH 5.6. We observed a developmental profile of arylsulfatase A, similar to that previously reported for cerebroside sulfatase (EC 3.1.6.8; (Van der Pal et al. (1990) Biochim. Biophys. Acta 1043, 91-96]. The activity of arylsulfatase A increased gradually during development, whereas arylsulfatase B rose more steeply, peaked around day 15 and declined thereafter. As a consequence the ratio between B and A forms of arylsulfatase dropped from about 4 in 1-week-old pups to 2.2 (cortex) and 0.7 (cord) in 7-week-old rat pups.     

Embryo culture of Costus speciosus (Koen.) Sm. to regenerate variable diosgenin yielding clones

Mature embryos of Costus speciosus were excised and cultured on Schenk and Hildebrandt's (1972) nutrient medium containing auxins and cytokinins either alone or in combination. Multiple shoots were obtained when kinetin and indole-3-butyric acid were supplemented each at 0.1 mg 1^–1 concentration. Embryo-derived plantlets were multiplied through propagation of rhizomes and the propagules derived from a single embryo were designated as an embryoclone. Twenty such embryo-clones were maintained in the field. Variations in rhizome biomass yield and diosgenin contents of these embryoclones were noted. Thirty-six percent of the embryo-clones studied were high diosgenin yielding types. Diosgenin contents at the intraclonal level were uniform. The in vitro raised plants were morphologically uniform and indistinguishable from their parent.Abbreviations SH Schenk and Hildebrandt (1972) medium - Kn kinetin - BAP 6-benzylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - NAA 1-naphthaleneacetic acid - IBA indole-3-butyric acid - IAA indole-3-acetic acid - CA casaminoacids (vitamin free) - TLC thin layer chromatography     

Hemoglobins,XLVIIII

Summary Hagfish hemoglobin has three main components, one of which is Hb III. It is monomeric and consists of 148 amino acid residues (M = 17 350). Its complete primary structure, previously published, is discussed here. The proximal amino acid (F8) of the heme linkage is histidine as always in the hemoglobins, but the regularly expected distal histidine E7 is substituted by glutamine. This substitution, leading to a new kind of heme linkage, has hitherto only been demonstrated in opossum hemoglobin. It is suggested that E7, Gln, is directed out of the heme pocket, and that the adjacent Ell, Ile, is directed toward the inside of the pocket, giving the distal heme contact instead of histidine.Myxine Hb III has an additional tail of 9 amino acid residues at its N-terminal end, as has the hemoglobin ofLampetra fluviatilis. The genetic codes ofMyxine andLampetra hemoglobins show 117 differences, in spite of many morphological resemblances between hagfish and lamprey. Their primary hemoglobin structures show differences substantial enough to bo compatible with the divergence of the two families some 400–500 million years ago.     

Crystal and molecular structure of the sulfhydryl protease calotropin DI at 3·2 Å resolution

The three-dimensional structure of the sulfhydryl protease calotropin DI from the madar plant, Calotropis gigantea, has been determined at 3·2 Å resolution using the multiple isomorphous replacement method with five heavy atom derivatives. A Fourier synthesis based on protein phases with a mean figure of merit of 0·857 was used for model building. The polypeptide backbone of calotropin DI is folded to form two distinct lobes, one of which is comprised mainly of α-helices, while the other is characterized by a system of all antiparallel pleated sheets. The overall molecular architecture closely resembles those found in the sulfhydryl proteases papain and actinidin.Despite the unknown amino acid sequence of calotropin DI a number of residues around its active center could be identified. These amino acid side-chains were found in a similar arrangement as the corresponding ones in papain and actinidin. The polypeptide chain between residues 1 and 18 of calotropin DI folds in a unique manner, providing a possible explanation for the unusual inability of calotropin DI to hydrolyze those synthetic substrates that papain and actinidin act upon.