Effects of Controlled Atmospheres on Production of Sesquiterpenoid Stress Metabolites by White Potato Tuber: Possible Involvement of Cyanide-resistant Respiration

Levels of katahdinone (solavetivone), lubimin, rishitin, and phytuberin, sesquiterpenoid stress metabolites of white potato (Solanum tuberosum), were monitored in tuber slices which were challenged with an extract of Phytophthora infestans and incubated under controlled atmospheres. A mixture of ethylene in air enhanced stress metabolite production. This enhancement was amplified by higher partial pressures of oxygen. Stress metabolite production was inhibited by salicylhydroxamic acid. These results suggest the involvement of cyanide-resistant respiration in the production of potato stress metabolites, compounds which may serve as phytoalexins.     

Steroid sulphatase levels in XX males,including observations on two affected cousins

Summary Quantitative assays of steroid sulphatase in XX males have shown that some individuals have two functional loci, and others only one. Two affected cousins, who cannot share the same X-chromosome, nevertheless have male levels of steroid sulphatase, suggesting functional abnormality of the X chromosome.The hypothesis is advanced that these and other unusual features of X-chromosome function in some XX males, could be explained if such cases were due to an autosomal mutation, exercising its effect by causing abnormal inactivation of a subterminal area of Xp which normally escapes the inactivation process.     

Heparin-inhibitable lectins: Marked similarities in chicken and rat

Extracts of young rat lung contain a heparin-inhibitable lectin that closely resembles one recently purified from chicken liver. Both lectins interact with heparin and N-acetyl-D-galactosamine, and were purified by gel filtration on Sepharose CL-2B followed by affinity chromatography on heparin-Sepharose. They both behave as high molecular weight aggregates that can be dissociated into two peptides with apparent molecular weights of 13,000 and 16,000 by gel electrophoresis in SDS. Samples of purified lectin contained up to 20% DNA by weight, and the degree of lectin aggregation and hemagglutination activity was greatly reduced by treatment with micrococcal nuclease without inhibiting heparin-binding activity. Association of lectin with DNA is an artifact of homogenization in high salt, since only 2% of the lectin is found associated with a purified nuclear fraction.     

Absolute configurations of isoflavans

The absolute configurations of isoflavans and isoflavanquinones isolated from Cyclolobium, Dalbergia and Machaerium species were established by comparison of their ORD curves with that of (3S)-5,7,3′,4′-tetra-methoxyisoflavan and (3S)-7,4′-dimethoxyisoflavan-2′,5′-quinone, respectively. The assignments were checked by the ozonolysis of the isoflavan (?)-duartin to (R)-paraconic acid and the oxidation of isoflavans to isoflavanquinones. The PMR spectra of the dihydropyran ring of the isoflavans are discussed in terms of the preferred conformation of this ring.     

Resting eggs, seasonal dynamics, and production of Bosmina longispina maritima (P. E. Muller) (Cladocera) in the northern Baltic proper

The seasonal dynamics and production of Bosmina longispina maritimawas studied both in the pelagic zone and bottom sediments ofthe northern Baltic proper in 1979. Resting eggs started tohatch in April–May, but the pelagic zone population didnot show signs of increase until August; this is typical forthe species in this area. Relatively few of those hatched inthe spring and early summer survived the low temperatures andlack of food below the thermocline. The population increasewas started with individuals hatched after the thermal stratificationweakened. From August until October the number of resting eggsin the sediment rose in direct response to their productionin the pelagic zone. A new hatching period began in October–November,but conditions in the pelagic zone were not suitable for theirfurther development. Such mistiming of hatching may, along withother factors, help to explain the large annual variations inthe productivity of B. longispina maritima in the Baltic. Sexualreproduction was found to be of relatively greater importancein the study area than in the areas where Bosmina reaches higherproductivity. This was assumed to be due to more intense selectionpressures in the prevailing conditions.     

Characterization and determination of titratable groups of proteins by linearization of titration curves. II. Application to lysozyme

The potentiometric acid-base titration curve of fully protonated lysozyme at ionic strengths of 0.10 and 1.0 m has been performed. The stoichiometry and the pK_a values of each titratable group have been determined through the linearization of titration curves. Two types of carboxylic groups with pK_a values of 3.76 and 5.02, the imidazole group with pK_a 7.37 and the amine group with pK_a 9.63, have been identified at an ionic strength of 0.10 m at 25.0°C. The number of titratable groups found per mole of protein has been 5.12 and 5.60 for the two types of carboxylic groups, 1.13 for the imidazole group, and 3.19 for the amino groups. The endpoint of the titration of the protein obtained by this method accords quite well with the endpoint obtained by the use of Gran function applied to the excess of strong base.     

Expression and characterization of the N-terminal half of antistasin, an anticoagulant protein derived from the leech Haementeria officinalis

Antistasin, a 15-kDa anticoagulant protein isolated from the salivary glands of the Mexican leech Haementeria officinalis, has been shown to be a potent inhibitor of factor Xa in the blood coagulation cascade. Antistasin possesses a twofold internal homology between the N- and C-terminal halves of the molecule, suggesting a gene duplication event in the evolution of the antistasin gene. This structural feature also suggests that either or both halves of the protein may possess biological activity if expressed as separate domains. Because the N-terminal domain contains a factor Xa P1-reactive site, we chose to express this domain in an insect cell baculovirus expression system. Characterization of this recombinant half antistasin molecule reveals that the N-terminal domain inhibits factor Xa in vitro, with a K(i) of 1.7 nM.     

Murine p53 inhibits the function but not the formation of SV40 T antigen hexamers and stimulates T antigen RNA helicase activity

We have characterized the effects of p53 on several biochemical activities of simian virus 40 (SV40) large tumor (T) antigen. While p53 induced a strong inhibition of the T antigen DNA helicase activity, surprisingly, its RNA helicase activity was stimulated. This supports the liklihood that the DNA and RNA helicase activities of T antigen reflect discrete functions. p53 did not significantly affect the ATP-dependent conversion of T antigen monomers to hexamers. However, the ability of these hexamers to assemble on a DNA fragment containing the viral origin was impaired by p53. Thus, these results suggest that p53 inhibits the function but not the formation of T antigen multimers. This conclusion was further supported by the observation that the addition of a purified p53:T antigen complex was as inhihitory as free p53 to the DNA helicase activity of free T antigen. Thus our data indicates that the targets of p53 inhibition are the functional units of T antigen, namely the hexamers.     

A new variant glyoxalase I allele that is readily detectable in stimulated lymphocytes and lymphoblastoid cell lines but not in circulating lymphocytes or erythrocytes

We describe an allele of the human glyoxalase GLO locus that encodes an enzymatically inactive form of the protein, which would not have been detected if only circulating erythrocytes and lymphocytes had been studied. The new allele is named GLO*3 and its protein product, GLO 3. Circulating blood cells of GLO*2/GLO*3 heterozygotes have just one electrophoretic band that migrates as the normal 2-2 dimer. Lymphoblastoid cell lines and phytohemagglutinin-stimulated lymphocytes from the same individuals have two electrophoretic bands, one with the mobility of the 2-2 dimer and one with the mobility of the 2-1 dimer that is present in GLO*2/GLO*1 heterozygotes, but a band with the mobility of the 1-1 dimer is not present. Therefore, the GLO*3 allele encodes a monomer that has the electrophoretic mobility of GLO 1 but is enzymatically inactive unless it is combined with normal monomers in 2-3 and 1-3 heterodimers. The failure to detect the GLO 3 protein in red cells and unstimulated lymphocytes is attributed to a relatively great instability or small rate of production in those cells. Consistent with this interpretation is the reduction of GLO activity in red cells of GLO*2/GLO*3 and GLO*1/GLO*3 heterozygotes to 65% or less of that in normal homozygotes and heterozygotes, while the activity of GLO*3 heterozygous lymphoblastoid cells is about 80% of normal. In contrast, the GLO activity of lymphoblastoid cells that had one copy of the GLO locus deleted by γ-irradiation was 50%–60% of normal. Our observations indicate that certain kinds of mutant alleles of the GLO locus, and perhaps other loci, may not be detected in electrophoretic surveys on circulating blood cells only. The segregation of alleles that are not expressed in circulating red and white blood cells could confuse attempts to determine parentage, as they might have in the family described here. The observations also demonstrate the feasibility of mapping human genes by using ionizing radiation to create partial chromosome deletions in cultured cells.