Novel Fusicoccins R and S,and the Fusicoccin S Aglycon (Phomopsiol) from Phomopsis amygdali Niigata 2-A,and Their Seed Germination-stimulating Activity in the Presence of Abscisic Acid

Our search for new 3-hydroxyfusicoccins structurally related to cotylenin A from a culture of Phomopsis amygdali Niigata 2-A resulted in the isolation of novel 3-hydroxy fusicoccins, called fusicoccins R and S, and the fusicoccin S aglycon, called phomopsiol, together with known 3α-hydroxyfusicoccin J. The structure of phomopsiol was identified as that of O-demethyl-3-epicotylenol based on spectroscopic evidence. The structures of fusicoccins R and S were also determined to be those of 3′-deacetyl-3α-hydroxyfusicoccin A and 3β-hydroxy-3-epifusicoccin H. The lettuce seed germination-stimulating activity of fusicoccins R and S, phomopsiol and 3α-hydroxyfusicoccin J was examined in the presence of ABA; fusicoccin R and 3α-hydroxyfusicoccin J were highly active, while fusicoccin S and phomopsiol were inactive. The possible biosynthetic relationships among these novel fusicoccins having a 3α- or 3β-hydroxy group in their diterpene moiety are briefly discussed.     

The reaction of ammonia with acylated disaccharides : XI. The wohl reaction with octa-O-acytylmelibiononitrile

Octa-O-acetylmelibiononitrile (1) was prepared from melibiose oxime. The reaction of aqueous ammonia with 1 gave 1,1-bis(acetamido)-1-deoxy-5-O-α-D-galactopyranosyl-D-arabinitol (2), N-acetyl-5-O-α-D-galactopyranosyl-α-D-arabinofuranosylamine (3), and the anomeric pair of 5-O-α-D-galactopyranosyl-D-arabinofuranoses (4 and 5). The hepta-O-acetyl derivative of 2 was prepared, and the acyclic structure of the nitrogen-containing moiety was established by oxidation with periodate. The α anomeric configuration of 3 was demonstrated by periodate oxidation and subsequent reduction with sodium borohydride and hydrolysis.     

Circular dichroism studies on α- and β-ketosides of 5-acetamido-3,5-dideoxy- -glycero- -galacto-nonulopyranosonic acid (N-acetylneuraminic acid) and of some of its derivatives

The circular dichroism spectra of a number of N-acetylneuraminic acid derivatives in aqueous solution were studied. For all compounds, the Cotton effects were found to be in the spectral range of the acetamido and carboxyl chromophores. The c.d. curves of the methyl, ethyl, and allyl α- -ketosides are characterized by a broad, positive band centered at λ ≈ 195 nm with a slight skew towards the higher wavelengths and weak bands between λ 225 and 255 nm, whereas the methyl β- -ketoside and the corresponding methyl ester show only an intense positive band with a broad shoulder in the same spectral range. 5-Acetamido-3,5-dideoxy- -glycero-β- -galacto-nonulopyranose, its methyl β- -ketoside, and 5-acetamido-3,5-dideoxy- -glycero- -galacto-nonulopyranosonamide containing only the acetamido chromophore showed one single positive Cotton effect centered at λ ≈ 192 nm. The c.d. spectrum of 5-acetamido-3,5-dideoxy- -glycero- -galacto-nonulopyranosonic acid confirms the β- configuration of the free acid in aqueous solution, whereas the shape of the c.d. curve of O-(N-acetyl-α- -neuraminopyranosyl)-(2→3)-O-β- -galactopyranosyl-(1→4)- -glucopyranose resembles that of the methyl, ethyl, and allyl α- -ketosides 2-4.     

Regioselective synthesis of novel 3-alkoxy (phenyl) thiophosphorylamido-2-(per-O-acetylglycosyl-1′-imino)thiazolidine-4-one derivatives from O-alkyl N-glycosyl(thiosemicarbazido)phosphonothioates

A series of 3-alkoxy(phenyl)thiophosphorylamido-2-(per-O-acetylglycosyl-1′-imino)thiazolidine-4-one derivatives were prepared by the reaction of 1-alkoxy(phenyl)thiophosphoryl-4-(per-O-acetylglycosyl) thiosemicarbazides with ethyl bromoacetate. ¹H/¹³C HMBC measurements corroborated by X-ray crystallographic results revealed the exclusive regioselectivity of these ring closures toward the N-2 position of the thiosemicarbazide moiety. The bioactivity data of 3a-k suggest that the thiazolidine-4-one ring is critical for the herbicidal and fungicidal activities.     

Synthesis and Properties of Modified Oligodeoxyribonucleotides Containing 2"-O-(2,3-Dihydroxypropyl)uridine and 2"-O-(2-Oxoethyl)uridine

A new uridine derivative, 2"-O-(2,3-dihydroxypropyl)uridine, and its 3"-phosphoramidite were obtained for direct introduction into oligonucleotides during automated chemical synthesis. Oligonucleotides 10 to 15 nt long harboring 2"-O-(2,3-dihydroxypropyl)uridine residues were synthesized; periodate oxidation of these oligomers gave oligonucleotides containing 2"-O-(2-oxoethyl)uridine residues. The presence of a reactive aldehyde group in 2" position of the carbohydrate moiety was confirmed by the interaction withp-nitrophenylhydrazine and methionine methyl ester. The thermostability of DNA duplexes containing modified units does not practically differ from that of the natural analogues.     

Mēthylation de dērivēs n-acylēs du 2-amino-2-dēsoxy-D-glucose en prēsence de sels d'argent: observations sur le comportement du groupement ambident acetamido (ou benzamido)

The behavior of the acetamido (and benzamido) ambident, nucleophilic group under methylation with methyl iodide and silver oxide has been studied for several 2-acetamido-2-deoxy-D-glucose derivatives. When silver perchlorate was added, alkylation occurred at the oxygen atom, giving methyl imidates that were labile in acidic medium. Benzyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-D-glucopyranoside was converted into N-(benzyl 3,4,6-tri-O-acetyl-2-deoxy-β-D-glucopyranoside-2-yl) methyl acetimidate (83%), which was subsequently hydrolyzed quantitatively in acidic medium into the corresponding amine salt. Similar results were obtained with benzyl 3,4,6-tri-O-acetyl-2-benzamido-2-deoxy-β-d-glucopyranoside, methyl 2-acetamido-2-deoxy-3,4,6-tri-O-methyl-β-D-glucopyranoside, and benzyl 2-acetamido-3,4,6-tri-O-benzyl-2-deoxy-β-D-glucopyranoside. Under Kuhn's methylation conditions (methyl iodide-silver oxide-N,N-dimethylformamide), alkylation of the just mentioned derivatives occurred at both oxygen and nitrogen atoms.     

Assignment of absolute configuration and optical purity determination of (R)- and (S)-econazole nitrate by enantioselective HPLC: Method development and application

A method is described for the synthesis and optical purity determination of (?)-(R)- and (+)-(S)-econazole via the optically pure intermediates, (R)- and (S)-imidazolylethanol, which are available by chromatographic resolution or by fractional crystallization of diastereomeric O,O′-disubstituted (R*;R*)- or (S*;S*)-tartaric acid monoesters of the parent imidazolylethanol racemate. Furthermore, this method allows the chromatographic assignment of the absolute configuration of the chiral center of the imidazolylethanol enantiomers and consequently of econazole enantiomers. In addition, a direct liquid chromatographic enantioseparation method for the determination of the optical purity of (R)- and (S)-econazole and other chiral imidazoles on a protein type CSP (OVM) is described and applied to confirm chromatographically the absolute configuration evaluations. © 1994 Wiley-Liss, Inc.     

Influence on Insecticidal Activity of the 3-(3,4-Methylenedioxyphenyl) Group in the 1,4-Benzodioxanyl Moiety of Haedoxan

The influence on the insecticidal activity of haedoxan A of its 3-(3,4-methylenedioxyphenyl) group in the 1,4-benzodioxanyl moiety was examined with two (±)-(1S*,2R*,5R*,6S*)-6-[(2R*,3R*)-3-alkyl-6- methoxy-2-methoxymethyl-1,4-benzodioxan-7-yl]-2-(2,6-dimethoxyphenoxy)-1-hydroxy-3,7-dioxabicyclo-[3.3.0]octanes. Replacement of the methylenedioxyphenyl group of haedoxan by methyl and n-butyl group resulted in a large decrease in the activity, indicating the importance of the 3-aryl group for the potent insecticidal activity of haedoxan.     

On the evolution of Tn21-like multiresistance transposons: sequence analysis of the gene (aacC1) for gentamicin acetyltransferase-3-I(AAC(3)-I), another member of the Tn21-based expression cassette

Summary The aminoglycoside-3-O-acetyltransferase-I gene (aacC1) from R plasmids of two incompatibility groups (R1033 [Tn1696], and R135) was cloned and sequenced. In the case of R1033, it was shown that theaacC gene is coded by a precise insertion of 833 bp between theaadA promoter and its structural gene in a Tn21 related transposon (Tn1696). This insertion occurs at the same target sequence as that of the OXA-1 β-lactamase gene insertion in Tn2603. Upstream of theaacC gene, we found an open reading frame (ORF) which is probably implicated in the site-specific recombinational events involved in the evolution of this family of genetic elements. These results provide additional confirmation of the role of Tn21 elements as naturally occurring interspecific transposition and expression casssettes.     

Behavior of R388rep(Ts)::Tn5, a thermosensitive Tn5 vector,and its derivatives inErwinia carotovora and some species of rhizobiaceae

R388rep(Ts)::Tn5 a thermosensitive, Tn5 vector (pCHR81) developed by Sasakawa and Yoshikawa [12], was found to be compatible with two strains ofErwinia carotovora and a strain ofRhizobium meliloti. pCHR81 was introduced into these organisms at lower temperatures and rendered suicidal at higher temperatures, giving rise to Tn5 transposed. To the transconjugants ofE. carotovora, which were cured of the R388 moiety and carrying Tn5 transposed, another Tn5 vector R388rep(Ts)::Tn5-Tcl (pCHR82) was re-introduced; this is a derivative of R388rep(Ts)::Tn5 with a tetracycline resistance marked instead of the original antibiotic resistances of Tn5. Gua⁺ gene ofE. carotovora was transferred by the cultures carrying only R388rep(Ts)::Tn5 or by those carrying R388rep(Ts)::Tn5-Tc and transposed Tn5. Though one strain of each ofAgrobacterium tumefaciens andA. radiobacter showed restriction to R388rep(Ts)::Tn5 plasmid maintenance, derivatives devoid of R388 and carrying Tn5 transposed were obtained. Streptomycin resistance gene on Tn5 was expressed in the cultures of all four species.     

Fast liquid chromatography for racemic atenolol acetate separation—The analytical protocol

Kinetic resolution of (R ,S )‐atenolol is a faster strategy to produce (S )‐atenolol. Since this racemate is a less soluble compound, resolution of its ester offers high concentrations in the process. A good analytical method is required to observe the enantiomer concentrations. This paper described application of ultra‐fast liquid chromatography on the atenolol ester separation using different resolution media and analytical procedures. Chiralcel OD column resolved the ester. The chromatograms indicated different characteristics of the process. The enantiomers could be recognized by the column in less than 1 (one) hour. Symmetrical peaks were obtained, but several procedures produced peaks with wide bases and slanted baselines. Efficient enantioresolution was obtained at high mobile phase flow rate, decreased concentration of amine‐type modifier, but increased alcohol content in the mobile phase. High UV detection wavelength was required. At 1.0 mL/min, the (90/10/0.5) composition resulted α  = 1.46 and R _S  = 0.9998 that were good separation.     

Conformational Preferences of Hypermodified Nucleoside Lysidine (k2C) Occurring at “Wobble” Position in Anticodon Loop of tRNAIle

Conformational preferences of hypermodified nucleoside, 4-amino-2-(N⁶-lysino)-1-(β-D-ribofuranosyl) pyrimidinium (Lysidine or 2-lysyl cytidine), usually designated as k²C, have been investigated theoretically by the quantum chemical perturbative configuration interaction with localized orbitals (PCILO) method. The zwitterionic, non-zwitterionic, neutral, and tautomeric forms have been studied. Automated geometry optimization using molecular mechanics force field (MMFF), semi-empirical quantum chemical PM3, and ab initio molecular orbital Hartree-Fock SCF quantum mechanical calculations have also been made to compare the salient features. The predicted most stable conformations of zwitterionic, non-zwitterionic, neutral, and tautomeric form are such that in each of these molecules the orientation of lysidine moiety (R) is trans to the N(1) of cytidine. The preferred base orientation is anti (χ = 3°) and the lysine substituent folds back toward the ribose ring. This results in hydrogen bonding between the carboxyl oxygen O(12a) of lysine moiety and the 2′-hydroxyl group of ribose sugar. In all these four forms of lysidine O(12a)…H-C(9) and O(12b)…H-N(11) interactions provide stability to respective stable conformers. Watson-Crick base pairing of lysidine with A is feasible only with the tautomeric form of usual anti oriented lysidine. This can help in recognition of AUA codon besides in avoiding misrecognition of AUG.     

AnO(N 2 logN) restriction map comparison and search algorithm

We present anO(R logP) time,O(M+P ² ) space algorithm for searching a restriction map withM sites for the best matches to a shorter map withP sites, whereR, the number of matching site pairs, is bounded byMP. As first proposed by Watermanet al. (1984,Nucl. Acids Res. 12, 237–242) the objective function used to score matches is additive in the number of unaligned sites and the discrepancies in the distances between adjacent aligned sites. Our algorithm is basically a sparse dynamic programming computation in which “candidate lists” are used to model the future contribution of all previously computed entries to those yet to be computed. A simple modification to the algorithm computes the distance between two restriction maps withM andN sites, respectively, inO(MN(logM+logN)) time. This author’s work was supported in part by National Library of Medicine Grant R01-LM4960. This author’s work was supported in part by National Library of Medicine Grant R01-LM5110.     

Influence of Guidelines and Passageways on Tunneling Behavior of Reticulitermes flavipes (Kollar) and R. virginicus (Banks) (Isoptera: Rhinotermitidae)

Tunneling behavior of laboratory-maintained cultures of Reticulitermes flavipes (Kollar) and R. virginicus (Banks) was examined to determine (1) if the termites build tunnels along preexisting wires or tunnels, and (2) whether tunnels are arranged to optimize search efficiency. Tunnel patterns were considered optimal if, for the number of tunnels present, the maximum area was explored. Termites entered either control arenas or arenas in which they encountered a wire or a pre-formed tunnel. Analyses revealed that R. flavipes and R. virginicus almost always follow pre-formed tunnels, but do not follow wires as readily. Within each species, the distributions of tunnels in treatment arenas were different from distributions in control arenas, most often when pre-formed tunnels were the treatment. Optimal tunnel arrangements in control arenas were found in 62% of R. flavipes patterns with 2 tunnels and in 43% of R. virginicus patterns with 2 tunnels. None of the 3-tunnel patterns from control arenas of R. flavipes and 29% of those of R. virginicus had optimal arrangements. Overall, the spatial arrangement of tunnels in control arenas was significantly different between R. flavipes and R. virginicus.     

On the Pathways for CO Egress from Carboxy Human Cytoglobin. A Molecular‐Dynamics Investigation

This work discloses two bona fide gates through which the CO ligand can leave the distal cavity of carboxy human cytoglobin, reaching the solvent. The investigation was based on molecular dynamics, aided by a minimal randomly‐oriented force applied to the ligand. The shortest pathway progresses toward the main gate, H81‐R84, in the open state, with the H81 imidazole moiety turned toward the solvent. A longer pathway develops toward the diametrically opposed W31‐W151 gate. In between, CO may be entrapped into binding cavities, either along the path toward the gates, or in a cul‐de‐sac, from which CO may even be incapable to escape. This behavior contrasts with carboxy myoglobin, where the corresponding H64 gate, when opened, is the sole used by CO to get to the solvent. These observations, which could hold also for other small ligands of biological interest, such as O₂, NO, and NO$\rm{{_{3}^{-}}}$ , provide an answer to a neglected aspect of the mysterious six‐coordinated globins.     

Convenient and Efficient Syntheses of Oligodeoxyribonucleotides Containing O 6-(Carboxymethyl)Guanine and O 6-(4-Oxo-4-(3-Pyridyl)Butyl)Guanine

O ⁶-(carboxymethyl)guanine (O ⁶-CMG) and O ⁶-(4-oxo-4-(3-pyridyl)butyl)guanine (O ⁶-pobG) are toxic lesions formed in DNA following exposure to alkylating agents. O ⁶-CMG results from exposure to nitrosated glycine or nitrosated bile acid conjugates and may be associated with diets rich in red meat. O ⁶-pobG lesions are derived from alkylating agents found in tobacco smoke. Efficient syntheses of oligodeoxyribonucleotides (ODNs) containing O ⁶-CMG and O ⁶-pobG are described that involve nucleophilic displacement by the appropriate alcohol on a common synthetic ODN containing the reactive base 2-amino-6-methylsulfonylpurine. ODNs containing O ⁶-pobG and O ⁶-CMG were found to be good substrates for the S. pombe alkyltransferase-like protein Atl1.

[Supplemental materials are available for this article. Go to the publisher's online edition of Nucleosides, Nucleotides & Nucleic Acids to view the free supplemental file.]     

Enantioselective biocatalytic synthesis of (S)-monastrol

The first enantioselective biocatalytic synthesis of (S)-monastrol has been developed via an unexpected and unusual enzymatic pathway as suitable route. Whereas attempts for a direct hydrolysis of racemic monastrol were not successful, formation of racemic O-butanoyl monastrol and subsequent enantioselective hydrolysis furnished O-butanoyl (S)-monastrol with 97% ee. Cleavage of the O-butanoyl moiety then gave the desired (S)-monastrol with 96% ee.     

Behavioral response of Riptortus pedestris (Hemiptera: Alydidae) 2nd instar nymphs to their gut symbiont,Burkholderia sp., in laboratory conditions

Many arthropods including insects have symbiotic relationships with diverse microorganisms that can confer fitness benefits to their hosts. Riptortus pedestris is a serious pest on leguminous crops in East Asia including South Korea and Japan. Recently, has been reported that R. pedestris form symbiosis with Gram‐negative bacteria in the genus Burkholderia where they acquire symbionts from soil environments without vertical transmission from each generation. In order to address how R. pedestris acquire their symbiont from environment, we hypothesized that R. pedestris would detect and exhibit preference toward the Burkholderia symbionts. In this study, we conducted a series of dual‐choice experiments and Y‐tube olfactometer experiments to monitor and evaluate behavioral responses by 2nd instar R. pedestris toward the Burkholderia treatment and untreated control under various experimental settings in the laboratory. In dual‐choice experiments, there was no significant preference by R. pedestris to the Burkholderia treatment compared with untreated control. Also, no significant difference was detected in the first choice frequency, visiting frequency, and residence time of the insects between the two treatments. Likewise, there was no detectable preference by R. pedestris to microbial odors from the symbionts in Y‐tube experiments. Therefore, our results indicate that there was no evidence supporting that 2nd instar R. pedestris exhibit preference to the Burkholderia symbiont in the laboratory conditions of this study. Further studies are required to evaluate behavioral responses of later immature stages (i.e., 3rd and 4th instar) to the symbionts and provide choice settings at larger semi‐field arenas.     

Genetic diversity and population structure of Rhododendron simsii (Ericaceae) as revealed by microsatellite markers

Rhododendron simsii Planch. (Ericaceae) is a valuable horticultural and medicinal plant species. In this study, the genetic diversity of eight wild R. simsii populations from the Dabie Mountains (central China) was investigated with 29 microsatellite markers. The results showed that R. simsii harbored a high level of genetic diversity (H_E: 0.64–0.79; H_O: 0.71–0.94; I = 1.917; h = 0.826), and 84.34% of this genetic variation was maintained within populations, while variation among populations only accounted for 15.66%. The number of alleles ranged from 6 to 11, with an average of 9.069. Heterozygote excess was found, with the mean F_IS and F_IT values of ?0.1739 and 0.0092, respectively. The average value of gene flow (Nm) was 1.3525. Within‐population, genetic diversity (I) ranged from 1.131 to 1.681. Cluster analyses divided the eight populations into two clades: the ‘Ltjiuzihe’ population formed its own cluster, while the other seven populations clustered together. There was a weak negative correlation between genetic and geographic distance. The results are highly relevant for the conservation and sustainable utilization of wild R. simsii germplasm resources in central China.     

New reports on flavonoids,benzoic- and chlorogenic acids as rare features in the Psychotria alliance (Rubiaceae)

Five flavonoid glycosides, three chlorogenic and one benzoic acid were isolated from leaves of seven species belonging to the genera Notopleura, Palicourea and Psychotria. In most species, common flavonol glycosides based upon quercetin and kaempferol were recorded, which corresponds well to literature data on other species of the Psychotria alliance. From Notopleura polyphlebia, however, the new dihydroflavonol glycoside (2R,3R)-7,4′-O-dimethyl-aromadendrin 5-O-β-d-apiofuranosyl-(1→6)-β-d-glucopyranoside (1) was isolated, which is remarkable in terms of both the structure of the aglycone as well as the rarity of apiose as sugar moiety. In addition to flavonoids, benzoic and chlorogenic acids are a common and frequently neglected feature in the alliance, but all appear to be of limited chemosystematic significance when compared to tryptamine-iridoid alkaloids prominently known from this group.