Rapid and early determination of sex using trophoblast biopsy specimens and Y chromosome specific DNA probes.

The feasibility of determining sex by analysing deoxyribonucleic acid (DNA) with two probes specific for Y chromosomes was shown using DNA obtained from samples of blood from 30 non-related males and females of different ethnic origin. The DNA was spotted on nitrocellulose filters and hybridised with both a repetitive (P1) and a unique (49f) sequence specific for the human Y chromosome. A strong positive signal with both probes indicated the presence of male DNA. The sex of 12 fetuses was then similarly determined by molecular characterisation of DNA from trophoblast biopsy specimens. Chorionic samples were obtained in seven cases before termination of pregnancy in the first trimester and the aborted embryos subjected to karyotyping and sex chromatin analysis. In the five other cases samples were obtained from placentas obtained during caesarean section. Results of hybridisation were compared with those from cytogenic studies and actual sex at birth. The sex of all 12 fetuses was determined correctly by hybridisation.     

Accumulation of nucleotides by starved Escherichia coli cells as a probe for the involvement of ribonucleases in ribonucleic acid degradation.

The acid-soluble ribonucleic acid degradation products formed by Escherichia coli cells starved for a carbon source have been identified. They comprise oligonucleotides, nucleoside diphosphates, 5'- and 3'-nucleoside monophosphates, nucleosides, and free bases. The majority of these products are excreted phates, nucleosides, and free bases. The majority of these products are excreted into the medium, and only small and constant amounts are kept in the pool. During carbon starvation at elevated temperatures, mutants deficient in ribonuclease I do not form oligonucleotides and 3'-nucleoside monophosphates, and mutants that contain a modified form of polynucleotide phosphorylase do not accumulate nucleoside diphosphates. 5'-Nucleoside monophosphates do accumulate, however, in a mutant containing thermoabile ribonuclease II, under conditions where more than 95% of all enzyme activity had been destroyed. The data presented confirm the participation of ribonuclease I and polynucleotide phosphorylase in the final steps of ribonucleic acid degradation and indicate that an exonuclease forming 5'-nucleoside monophosphates is also involved.     

Purification and properties of a triacylglycerol lipase from Mycobacterium phlei.

In order to study the metabolism of triacylglycerol in mycobacteria, an intracellular particulate triacylglycerol lipase (EC 3.1.1.3) was purified 800-fold from stationary phase cells of Mycobacterium phlei. Extraction of whole cell suspensions with 5% Triton X-100, followed by ion-exchange chromatography of the extract on two successive DEAE-cellulose columns produced a preparation which was nearly homogeneous by the criterion of analytical isoelectric focusing in acrylamide gels (one band, pI. 3.8) and by polyacrylamide gel electrophoresis. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis resolved the preparation into six protein bands. Lipase activity stable to electrophoresis in sodium dodecyl sulfate was extracted from the 40 000 molecular weight region of the gels. ith phosphate or maleate buffer the enzyme exhibits a broad pH optimum around 6.0 with sigmoid saturation kinetics (Hill number 2), and an apparent Km of 8.8 mM for tripalmitoylglycerol. Citrate and other carboxylic acids increase the apparent V up to 3-fold with the Hill number approaching 1.0. In a series of p-nitrophenyl esters tested (C2-C18), p-nitrophenylmyristate was hydrolyzed most rapidly. The saturation curve for p=nitrophenylmyristate was sigmoid and unaffected by citrate. The role of this activity in the metabolism of triacylglycerols by Mycobacteria is discussed.     

The effect of inflammation on rat liver beta-galactosidase and beta-N-acetylglucosaminidase.

Reduced activities of β-galactosidase and β-N-acetylglucosaminidase were found in rat livers following experimentally induced inflammation. The greatest reduction in glycosidase activities were found 24 h after inflammation. The lysosomal fraction accounted for the bulk of both glycosidase activities in experimental and control rats. Kinetic experiments showed that inflammation did not affect K_m values, but did result in a significant reduction in V_max values. One suggestion to explain the results is that inflammation causes a reduction in biosynthesis or activation of the two glycosidases in rat liver.     

Biodegradation of polystyrene, poly(metnyl methacrylate), and phenol formaldehyde.

The biodegradation of three synthetic 14C-labeled polymers, poly(methyl methacrylate), phenol formaldehyde, and polystyrene, was studied with 17 species of fungi in axenic cultures, five groups of soil invertebrates, and a variety of mixed microbial communities including sludges, soils, manures, garbages, and decaying plastics. Extremely low decomposition rates were found. The addition of cellulose and mineral failed to increase decomposition rates significantly.     

Studies of bovine liver glutamate dehydrogenase by analytical affinity chromatography on immobilized AMP analogs.

Bovine liver glutamate dehydrogenase has been studied by analytical affinity chromatography on two immobilized AMP analogs, i.e., N⁶-(6-aminohexyl)-AMP and 8-(6-aminohexyl)-amino-AMP. The existence of various enzyme-coenzyme and enzyme-effector complexes has been verified. Also the cooperative formation of two ternary complexes, i.e., glutamic dehydrogenase (GHD)-NADP-glutamate and GDH-ADP-leucine, has been shown. The results of this study have been rationalized by the “ligand exclusion theory.” which has been proposed for the regulation of the glutamic dehydrogenase. It has been shown that the active site and the ADP-binding effector site are oriented close to each other on the enzyme. Furthermore, the data suggest that the adenylic site is not identical to the nonactive coenzyme binding site. A mechanism based on electrostatic interactions is suggested for the cooperative binding of oxidized coenzyme and substrate. Dissociation constants for complexes between the enzyme and two coenzyme fragments (P-ADPR and 2′,5′-ADP) have been estimated.     

The Viking mission: Implications for life on Mars

Summary The results of the Viking Biology experiments are best explained by non-biological phenomena: The interaction of the reagents with the materials comprising the regolith. Conditions of water activity, temperature, availability of carbon sources and others in most regions of the planet are too extreme for survival and growth of any known Earth microorganisms. Although the possibility persists that some very unusual form of life is somewhere on that planet the evidence is best interpreted as negative. Even though there is no evidence for current life on Mars, whether or not life ever originated there is not known.