Significance of glycosylation patterns of rat Zajdela ascitic hepatocellular carcinoma: effect of enzymatic removal of surface sialic acid on humoral response.

BACKGROUND AND AIM: Rat Zajdela ascitic hepatocellular carcinoma (ZAH) is a malignant cell type with some properties in common with rat hepatocytes. The aim of this study was to determine the glycosylation patterns of surface glycoproteins of two cell lines C and D of ZAH by lectin binding for identification and characterization of tumor-specific markers. METHODS: Plasma membrane proteins from these cells were separated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, and probed using radio-iodinated lectins. RESULTS: We observed a decrease in the binding of concavalin A, and an increase in the binding of wheat germ agglutinin (WGA) to glycoproteins from the tumor cell lines as compared with those from normal liver cells. We showed that the increase in binding of WGA was mainly due to increased sialylation of the surface glycoproteins of the tumor cells. The major sialylated glycoproteins of the tumor cells contained O-linked carbohydrate chains. It was also shown that removal of surface sialic acid by neuraminidase significantly decreased the lethality of the tumor and led to increased survival of tumor-bearing animals. The decreased lethality of the tumor appears to be due to increased antigenicity of the desialylated tumor cells. CONCLUSION: Taken together, the presence of highly sialylated O-linked glycosylation of gp120 in ZAH tumor cells and its absence in normal liver cells is of significance with respect to the biological properties of this tumor.

Microsatellite mutation in the maternally/paternally transmitted D18S51 locus: two cases of allele mismatch in the child.

BACKGROUND: We investigated 2 cases of paternity dispute with 17 autosomal short tandem repeats (STR), that indicated a mismatch to the maternally and paternally inherited allele at D18S51 locus in children under inquiry. METHODS: 17 autosomal and Y STR loci were analyzed using AmpFlSTR Identifiler, PowerPlex 16, AmpFlSTR(R)Y-filertrade mark kits. The mitochondrial DNA hypervariable regions HV1 and HV2 and 6 STR markers on X chromosome were amplified and sequenced. RESULTS: In case M1, allelic representation in the mother, questioned child and suspected father was 14/19, 12/20 and 12/14 respectively. A complete match with the mother at 6 X STR loci and mitochondrial hypervariable regions was observed. In case F1, allelic representation was 13/14, 14/20 and 16/18 respectively. A complete match with the father at 17 Y chromosome STR loci was observed. D18S51 sequence analysis indicates the expansion of 1 repeat in M1 and 2 repeats in F1 leading to allele mismatch in the child. CONCLUSION: The probability of maternity and paternity were 0.999999 and 0.999999 respectively. This is the first report of a maternally/paternally transmitted D18S51 mutations in the paternity DNA testing. These results conclusively determined that the mother and suspected father are the biological parents of the questioned children in both the cases.

Constitutive optimized production of streptokinase in Saccharomyces cerevisiae utilizing glyceraldehyde 3-phosphate dehydrogenase promoter of Pichia pastoris.

A novel expression vector constructed from genes of Pichia pastoris was applied for heterologous gene expression in Saccharomyces cerevisiae. Recombinant streptokinase (SK) was synthesized by cloning the region encoding mature SK under the control of glyceraldehyde 3-phosphate dehydrogenase (GAP) promoter of Pichia pastoris in Saccharomyces cerevisiae. SK was intracellularly expressed constitutively, as evidenced by lyticase-nitroanilide and caseinolytic assays. The functional activity was confirmed by plasminogen activation assay and in vitro clot lysis assay. Stability and absence of toxicity to the host with the recombinant expression vector as evidenced by southern analysis and growth profile indicate the application of this expression system for large-scale production of SK. Two-stage statistical approach, Plackett-Burman (PB) design and response surface methodology (RSM) was used for SK production medium optimization. In the first stage, carbon and organic nitrogen sources were qualitatively screened by PB design and in the second stage there was quantitative optimization of four process variables, yeast extract, dextrose, pH, and temperature, by RSM. PB design resulted in dextrose and peptone as best carbon and nitrogen sources for SK production. RSM method, proved as an efficient technique for optimizing process conditions which resulted in 110% increase in SK production, 2352 IU/mL, than for unoptimized conditions.

Paternal exclusion: allele sharing in microsatellite testing.

BACKGROUND: A paternity disagreement analyzed with 15 autosomal microsatellite markers indicated allele sharing between the mother, questioned child and the alleged father generating an inconclusive paternity result. DESIGN AND METHODS: In total, 15 autosomal and 17 Y tandem repeat loci were analyzed using AmpF/STR Identifiler, AmpF/STR Y-filer kits followed by six microsatellite markers on X chromosome in DNA extracted from peripheral blood samples of the mother, questioned child and alleged father. RESULTS: Microsatellite analysis examined with 15 autosomal short tandem repeats (STRs) indicated at least one allele sharing at 14 loci between the mother, questioned child and alleged father except for the TPOX locus where a paternal-child allele mismatch was observed. Y chromosome investigations using 17 repeat markers signified the case as non-paternity (exclusion). A complete match of the six X chromosome loci in the questioned child with the mother was observed. CONCLUSIONS: Our investigations on inconclusive paternity due to atypical allele sharing in autosomal microsatellites were resolved with X- and Y-chromosome STR analyses confirming the case as non-paternity.

Mother-child double incompatibility at vWA and D5S818 loci in paternity testing.

BACKGROUND: In a paternity dispute case, 17 autosomal short tandem repeats (STR) were examined and signified a possible paternal mismatch at vWA locus and a maternal mismatch at D5S818 locus in the child under investigation. METHODS: Seventeen autosomal, 17 Y-chromosome and six X-chromosome repeat loci were used in parentage analysis. The mutated vWA and D5S818 alleles were amplified, cloned and sequenced to analyze the repeat structure. RESULTS: The vWA locus genotype in the mother, questioned child and suspected father were 18/19, 16/18 and 14/18, and were 13/15, 11/12 and 11/14, respectively, for the D5S818 locus. A complete match with the mother at six X-chromosome STR loci and with the father at 17 Y-chromosome STR loci was observed. Nucleotide sequence analysis of the family at vWA alleles indicated the maternal loss of the repeat motif TCTA by two repeat units and a loss of AGAT repeat by one unit in the D5S818 locus leading to an allele mismatch in the child. The probability of maternity and paternity were 0.999999 and 0.999999, respectively. CONCLUSIONS: This is the first study of a maternally transmitted microsatellite mutation in the loci D5S818 and vWA in paternity DNA testing. The results convincingly established that the mother and suspected father are the biological parents of the questioned child.