Nucleosides. LXV. Synthesis of New Pteridine–N8–Nucleosides

A general synthetic approach to various isoxanthopterin‐nucleosides starting from 6‐methyl‐2‐methylthio‐4(3H), 7(8H)‐pterdinedione (1) has been developed. Ribosylation with 1‐O‐acetyl‐2,3,5‐tri‐O‐benzoyl‐β‐d‐ribofuranose via the silyl‐method led to 2 and reaction with 1‐chloro‐2‐deoxy‐3,5‐di‐O‐p‐toluoyl‐α‐d‐ribofuranose using the DBU‐method afforded 28. Protection of the amide function at O⁴ by benzylation to 5 and by a Mitsunobu reaction with 2‐(4‐nitrophenyl)ethanol to 29 gave soluble intermediates which can be oxidized to the corresponding 2‐methylsulfonyl derivatives 8 and 30, respectively. Nucleophilic displacement reactions of the highly reactive 2‐methylsulfonyl functions by various amines proceeded under mild conditions to isoxanthopterin‐N₈‐ribo‐ (11–17) and 2′‐deoxyribomucleosides (31–33). Debenzylation can be achieve by Pd‐catalyzed hydrogenation (9 to 19) and cleavage of the npe‐protecting group (31, 32 to 34, 35) works well with DBU by β‐elimination.     

Bibliography of ‘molecular systematic’ studies of bryophytes. I. 1985–2000

A bibliography of all studies using characters of DNA sequences to address questions pertaining to the systematics of bryophytes are enumerated. In total 90 research articles are listed. These are arranged according to method of data gathering (Random or specific amplification) and the genomic source of the data analyzed (i.e., nuclear, chloroplastic or mitochondrial).     

Chemical Selection of Mutants That Affect Alcohol Dehydrogenase in Drosophila II. Use of 1–PENTYNE–3–Ol

We describe a procedure for the selection of alcohol dehydrogenase negative mutants in Drosophila. The method consists of exposing eggs and larvae to low concentrations of 1-pentyne-3-ol dissolved in the culture medium. Only those flies with greatly reduced levels of alcohol dehydrogenase activity survive. In addition, genotypically negative flies die if their mothers are alcohol dehydrogenase positive. Using this procedure and formaldehyde to generate mutants, we were able to detect seven alcohol dehydrogenase negative mutants out of 350,000 individuals subjected to selection. At least five of the mutants contain small deletions that include the alcohol dehydrogenase locus.     

One cell–one immunoglobin. Origin of limited heterogeneity of myeloma proteins

Plasma-cell tumour 5563 forms a single molecular species of immunoglobulin IgG(2)a, i.e. one variant of heavy chain and one variant of light chain. The molecules formed are labile and undergo alterations in charge properties, which rapidly lead to heterogeneity of the myeloma protein after synthesis. The single immunoglobulin species originally formed is found only after the shortest time-intervals tested, i.e. 10min incubation. Two types of changes in charge properties take place: (1) The originally formed protein (component o) is converted via an intermediate o' into the most basic form of 5563 myeloma protein found in serum (component a). Charge differences between these components are suppressed at pH8.9, but can be studied by chromatography at pH6.5 or by analysis of isoelectric points by isoelectric focusing in polyacrylamide gel. The conversion of components o and o' into component a apparently commences soon after assembly of the molecules and proceeds to completion extracellularly. (2) The second type of charge difference that distinguishes components a, b, c and d is exhibited over the pH range 6.0-8.9, but not at acid pH, and has been studied by electrophoresis at pH8.9, by chromatography and by isoelectric focusing. Conversion of component a into components b, c, d and e is only partial so that all five components can be found at decreasing concentrations in serum. Both types of charge alteration can be effected in vitro in the presence of serum, with optimum pH8.0. None of the charge differences could be attributed to the secretion process, since a component with the same isoelectric point as component o was found in secreted myeloma protein (1h). We have found no evidence to support the idea that the first type of change from component o to component a is due to ring formation of N-terminal [(14)C]glutamine into pyrrolid-2-one-5-carboxylic acid; however, our findings do not exclude this process happening very rapidly to a precursor of component o, possibly the polypeptide chain during or immediately after synthesis. In studying this point we noted that not only the heavy chains but also the kappa-type light chain of mouse 5563 myeloma protein have a blocked N-terminus.     

Heterogeneity of protein–polysaccharides of porcine articular cartilage. The chondroitin–sulphate proteins associated with collagen

Pig articular cartilage, from which protein-polysaccharides soluble in iso-osmotic sodium acetate had been removed, was extracted in three further stages with 8m-urea in 2m-sodium acetate and with tris-HCl buffer after bacterial collagenase digestion, followed by the same urea-sodium acetate solution, thus leaving only 2% of the original uronic acid in the tissue. The histological appearance of the cartilage was unaltered until after collagenase digestion. The collagenase used did not affect the viscosity or molecular size of a protein-polysaccharide preparation obtained previously. The protein-polysaccharides in each extract differed in size, amino acid composition and protein content, but protein and keratan sulphate contents were not related to hydrodynamic size, in contrast with protein-polysaccharides extracted previously before collagenase digestion. Hydroxyproline could not be removed from those obtained by the first urea-sodium acetate extraction until degraded by heat. The galactosamine/pentose molar ratio agreed closely with the galactosamine/serine molar ratio that was destroyed on treatment with 0.5m-sodium hydroxide, showing that chondroitin sulphate was attached only to serine residues. From these molar ratios the chondroitin sulphate chains were calculated to be of the same average length in protein-polysaccharides in all three extracts although somewhat shorter than in protein-polysaccharides extracted previously. Some threonine residues were also destroyed on alkali treatment suggesting that keratan sulphate may be attached to threonine. These findings together with previous results show that differences in size, composition and physical state extend to all the protein-polysaccharides in cartilage.     

Micropropagation of the threatened Nepalese medicinal plant Swertia chirata Buch.–Ham. ex Wall.

 Multiplication by adventitious shoot regeneration from root explants was found to be the most suitable method for the propagation of Swertia chirata. A two-step system consisting of an initial 3-week cultivation on modified Murashige and Skoog medium supplemented with 3 μM 6-benzylaminopurine (BAP), followed by another period of 3 weeks on hormone-free medium was used. After rooting and acclimatization micropropagated plants could be successfully cultivated in Nepal. Received: 28 July 1997 / Revision received: 10 February 1998 / Accepted: 16 February 1999     

Microbial metabolism of aromatic nitriles. Enzymology of C–N cleavage by Nocardia sp. (Rhodochrous group) N.C.I.B. 11216

1. An organism utilizing benzonitrile as sole carbon and nitrogen source was isolated by the enrichment-culture technique and identified as a Nocardia sp. of the rhodochrous group. 2. Respiration studies indicate that nitrile degradation proceeds through benzoic acid and catechol. 3. Cell-free extracts of benzonitrile-grown cells contain an enzyme that catalyses the conversion of benzonitrile directly into benzoic acid without intermediate formation of benzamide. 4. This nitrilase enzyme was purified by DEAE-cellulose chromatography and gel filtration on Sephadex G-100 in the presence and absence of substrate. The purity of the enzyme was confirmed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and isoelectric focusing on polyacrylamide gel. 5. The enzyme shows a time-dependent substrate-activation process in which the substrate catalyses the association of inactive subunits of mol.wt. 45000 to form the polymeric 12-unit active enzyme of mol.wt. 560000. The time required for complete association is highly dependent on the concentration of the enzyme, temperature and pH. 6. The associated enzyme has a pH optimum of 8.0 and K(m) with benzonitrile as substrate of 4mm. The activation energy of the reaction as deduced from the Arrhenius plot is 51.8kJ/mol. 7. Enzyme activity is inhibited by thiol-specific reagents and several metal ions. 8. Studies with different substrates indicate that the nitrilase is specific for nitrile groups directly attached to the benzene ring. Various substituents in the ring are compatible with activity, though ortho-substitution, except by fluorine, renders the nitrile invulnerable to attack. 9. The environmental implications of these findings and the possible significance of the enzyme in the regulation of metabolism are discussed.     

We appreciate the invaluable contributions of the following reviewers during the editing of Vol. 8 Nos. 1–2.

Acknowledgments

We appreciate the invaluable contributions of the following reviewers during the editing of Vol. 8 Nos. 1–2.     

Macrofauna standing stock of the Dogger Bank. A comparison: III. 1950–54 versus 1985–87. A final summary

The macrofauna communities on the Dogger Bank in April/May 1985–87 were compared with those in April/May 1950–54 (Ursin, 1960). Unpublished data from Birkett on the central and western Dogger Bank from April/May 1952–54 were also used for the comparison. The changes in the communities from the fifties to the eighties were made clear by the increasing species numbers and in an increase or dominance of short-living opportunistic species. In contrast, a decrease in long-living bivalves was found. The total biomass in 1985–87 was 2.5 to 8 times higher than in 1950–54. Similarities between stations were below 20%. Some hypotheses concerning natural and anthropogenic impacts are given to interpret the observed changes.     

Consistency vs. contingency of trait–performance linkages across taxa

An important approach to generalizing across different taxa and systems is to focus on functional traits rather taxonomic identity. However, this approach assumes, usually implicitly, that the same value of the same trait will have the same effect in all taxa. This assumption is probably never true in the strictest sense, but it is less clear to what extent even the direction and shape of trait–performance relationship are consistent among taxa. Wildova et al. (Oikos 116:836–852, 2007) addressed this question by manipulating traits in a highly calibrated model of clonal plants, parameterized for six sedge species. They found traits connected to growth and allocation were largely consistent in their performance effects across taxa, while morphological and architectural traits were much more contingent. This result suggests that traits not directly related to resource acquisition and use should show much less consistent patterns across systems and be less susceptible to ecological generalizations.     

Purification,Crystallization and Some Enzymatic Properties of Acid Protease of Cladosporium sp. No. 45–2

An acid protease of Cladosporium sp. No. 45–2 was purified and crystallized by precipitation with ammonium sulfate, fractional precipitation with acetone, and pH adjustment. About 600 mg of third crystallized preparation was obtained from one liter of culture broth. The purified enzyme was chromatographically homogeneous and confirmed to be monodispersive by physicochemical criteria such as uhracentrifugal and electrophoretical analysis. The enzyme was most active at pH values between 2.5 and 2.7 toward both casein and hemoglobin and was stable at pH values from 2.5 to 7.0 on twenty hour incubation at 30°C.

Millimolar concentration of sodium lauryl sulfate markedly inhibited the enzyme, wheares diisopropyl phosphorofluoridate, sulfhydryl reagents, ethylenediaminetetra acetic acid, and divalent metal ion relatively little affected the activity. The enzyme was most resistant toward S-PI among the acid proteases tested.     

Analysis of the Putative Remains of a European Patron Saint–St. Birgitta

Saint Birgitta (Saint Bridget of Sweden) lived between 1303 and 1373 and was designated one of Europe''s six patron saints by the Pope in 1999. According to legend, the skulls of St. Birgitta and her daughter Katarina are maintained in a relic shrine in Vadstena abbey, mid Sweden. The origin of the two skulls was assessed first by analysis of mitochondrial DNA (mtDNA) to confirm a maternal relationship. The results of this analysis displayed several differences between the two individuals, thus supporting an interpretation of the two skulls not being individuals that are maternally related. Because the efficiency of PCR amplification and quantity of DNA suggested a different amount of degradation and possibly a very different age for each of the skulls, an orthogonal procedure, radiocarbon dating, was performed. The radiocarbon dating results suggest an age difference of at least 200 years and neither of the dating results coincides with the period St. Birgitta or her daughter Katarina lived. The relic, thought to originate from St. Birgitta, has an age corresponding to the 13^th century (1215–1270 cal AD, 2σ confidence), which is older than expected. Thus, the two different analyses are consistent in questioning the authenticity of either of the human skulls maintained in the Vadstena relic shrine being that of St. Birgitta. Of course there are limitations when interpreting the data of any ancient biological materials and these must be considered for a final decision on the authenticity of the remains.     

U.S. National Institutes of Health Core Consolidation–Investing in Greater Efficiency

The U.S. National Institutes of Health (NIH) invests substantial resources in core research facilities (cores) that support research by providing advanced technologies and scientific and technical expertise as a shared resource. In 2010, the NIH issued an initiative to consolidate multiple core facilities into a single, more efficient core. Twenty-six institutions were awarded supplements to consolidate a number of similar core facilities. Although this approach may not work for all core settings, this effort resulted in consolidated cores that were more efficient and of greater benefit to investigators. The improvements in core operations resulted in both increased services and more core users through installation of advanced instrumentation, access to higher levels of management expertise; integration of information management and data systems; and consolidation of billing; purchasing, scheduling, and tracking services. Cost recovery to support core operations also benefitted from the consolidation effort, in some cases severalfold. In conclusion, this program of core consolidation resulted in improvements in the effective operation of core facilities, benefiting both investigators and their supporting institutions.