Demonstration of cross-reacting material in Tay–Sachs disease

Antibodies against placental hexosaminidase A and kidney alpha-subunits were raised in rabbits after cross-linking the antigens with glutaraldehyde. Anti-(alpha(n)-subunit) antiserum (anti-alpha(n)) precipitated hexosaminidase A but not hexosaminidase B, whereas anti-(hexosaminidase A) antiserum precipitated both hexosaminidases A and B. Specific anti-(hexosaminidase A) antiserum was prepared by absorbing antiserum with hexosaminidase B. Both anti-alpha(n) and anti-(hexosaminidase A) antisera precipitated the CR (cross-reacting) material from eight unrelated patients with Tay-Sachs disease. Immunotitration, immunoelectrophoresis, double-immunodiffusion and radial-immunodiffusion techniques were used to demonstrate the presence of CR material. The CR-material-antibody complex was enzymically inactive. Antiserum raised against kidney or placental hexosaminidase A, without cross-linking with glutaraldehyde, failed to precipitate the CR material, implying that treatment of the protein with glutaraldehyde exposes antigenic determinants that are hidden in the native protein. Since anti-(hexosaminidase B) antiserum did not precipitate the CR material during the immunoelectrophoresis of Tay-Sachs liver extracts, it is suggested that altered alpha-subunits do not combine with beta-subunits. By using immunotitration we have demonstrated the competition between the hexosaminidase B-free Tay-Sachs liver extract and hexosaminidase A for the common binding sites on monospecific anti-(cross-linked hexosaminidase A) antiserum. The amount of CR material in the liver samples from seven cases of Tay-Sachs desease was found to be in the same range as theoretically calculated alpha-subunits in normal liver samples. Similar results were obtained by the radial-immunodiffusion studies. The present studies therefore suggest that Tay-Sachs disease is caused by a structural-gene mutation.     

Fungi parasitising the eggs of certain fresh water fishes

By the present investigations the parasitic abilities of five isolates of Saprolegniaceous fungi have been established on the eggs of three fresh water fishesviz., Channa marulius Ham.,Channa gachua Ham., andNotoptenis notopterus Ham. These fungi areAchlya orion CokerAchlya prolifera (Nees) De Bary,Aphanomyces laevis Minden andSaprolegnia ferax (Gruith) Thuret.     

Purification and properties of glutathione peroxidase from human placenta.

Glutathione peroxidase (glutathione--H2O2 oxidoreductase; EC 1.11.1.9) was purified to homogeneity from human placenta by using (NH4)2SO4 precipitation, ion-exchange chromatography, Sephadex gel filtration and preparative polyacrylamide-disc-gel electrophoresis. Glutathione peroxidase from human placenta is a tetramer, having 4g-atoms of selenium/mol of protein. The molecular weight of the enzyme is about 85000 with a subunit size of about 22,000. Kinetic properties of the enzyme are described. On incubation with cyanide, glutathione peroxidase is completely and irreversibly inactivated and selenium is released as a low-molecular-weight fragment. Reduced glutathione, beta-mercaptoethanol and dithiothreitol protect the enzyme from inactivation by cyanide and the release of selenium. Properties of human placental glutathione peroxidase are similar to those of isoenzyme A reported earlier by us from human erythrocytes. The presence of isoenzyme, B, reported earlier by us in human erythrocytes, was not detected in placenta. Also selenium-independent glutathione peroxidase (isoenzyme II), which is specific for cumene hydroperoxide, was not present in human placenta.     

The artifactual nature of fluoride inhibition of reverse transcriptase and associated ribonuclease H

Surprisingly, the $\text{sn}$-1 configuration of 1-0-hexadecyl-2-acetyl-glycerylphosphorylcholine showed significant activity, 3.22 × 10^?9 M, when compared to the $\text{sn}$-3 enantiomer, 2.92 × 10^?10 M and a racemic mixture with a value of 7.2 × 10^?10 M. A methoxy substitution at the C-1 or C-2 position of octadecyl glycerylphosphorylcholine gave a derivative with high biological activity for stimulating serotonin release from rabbit platelets. A 1-0-dodecyl-2-methoxy analogue showed very low activity; also, a comparable series of 0-benzyl derivatives were inactive. Examination of 1-0-hexadecyl, 1-0-octadecyl- or 1-0-dodecyl-2-acetyl-$\text{sn}$-glyceryl-3-phosphorylcholine showed that the hexadecyl compound had three times the biological activity of the octadecyl and five times that of the dodecyl.     

Antigenic relationships in calf thymus and human leukemic cell terminal deoxynucleotidyl transferase.

Antibody to purified terminal deoxynucleotidyl transferase (nucleosidetriphosphate : DNA deoxy-nucleotidylexotransferase, E.C. 2.7.7.31) from calf thymus was prepared in rabbits using terminal deoxynucleotidyl transferase crosslinked to bovine serum albumin. These antibodies, partially purified by 60% ammonium sulfate precipitation and Sephadex G-200 column chromatography, produced one precipitation band with calf thymus terminal deoxynucleotidyl transferase on immunodiffusion. This antibody preparation also inhibited the in vitro activity of terminal deoxynucleotidyl transferase from calf thymus, acute leukemic lymphoblasts and Molt-4 cells but not that of DNA polymerases alpha, beta and psi from these cells     

Maturation of rat spermatozoa: ESR spin labeling studies.

The ability of spermatozoa to reduce nitroxide spin--TEMPO has been used as a parameter to understand maturation, capacitation and calcium uptake of sperm obtained from Holstman strain rats. The rate of spin label reduction by sperm follows the trend--caput greater than cauda greater than corpus. With the increase in age, the electron donating capability shows first a gradual increase, for 60- to 85-day-old rats, peaking at 85 days (corresponding to puberty) and leveling off after 92 days. Calcium uptake takes place in two phases which corresponds to accumulation of and activation by calcium. The presence of polyclonal antibody which is known to cause agglutination, does not adversely affect the sperm activity.     

Combined chemical-enzymic synthesis of deoxygenated oligosaccharide analogs: transfer of deoxygenated D-GlcpNAc residues from their UDP-GlcpNAc derivatives using N-acetylglucosaminyltransferase I

The 3'-, 4'-, and 6'-deoxy analogs of UDP-GlcpNAc have been synthesized chemically and found to act as donor-substrates for N-acetylglucosaminyltransferase-I (GnT-I) from human milk. Incubation of UDP-GlcpNAc and these deoxy analogs with GnT-I in the presence of alpha-D-Manp-(1----3)-[alpha-D-Manp-(1----6)]-beta-D-Manp -O(CH2)8COOMe gave beta-D-GlcpNAc-(1----2)-alpha-D-Manp-(1----3)-[alpha-D-Manp- (1----6)]- beta-D-Manp-O(CH2)8COOMe (6), and the deoxy analogs 12-14 where HO-3, HO-4, and HO-6, respectively, of the beta-D-GlcNAc residue were replaced by hydrogen. The tetrasaccharide glycosides 6 and 12-14 were characterized by 1H-n.m.r. spectroscopy and evaluated as acceptors for GnT-II, the next enzyme in the pathway of biosynthesis of Asn-linked oligosaccharides. Deoxygenation of the 3-position of the beta-D-GlcNAc residue of 6 completely abolished its acceptor activity, whereas removal of HO-4 or HO-6 caused only modest decreases in activity.     

Effect of phenolics on plant amine oxidases

Phenolic compounds at low concentrations decrease pea diamine oxidase activity without affecting growth, but they have no effect on barley polyamine oxidase in spite of a decrease in growth.     

Increased virulence ofMycobacterium avium Kirschberg in thioacetamide treated rabbits

An attempt has been made to determine the correlation between liver damage and the virulence of mildly pathogenicMycobacterium avium in thioacetamide treated rabbits. Liver damage increased the susceptibility of rabbits to infection even with a moderately virulent organism.