Brickellin,a novel flavone from brickellia veronicaefolia and b. chlorolepis

A new highly oxygenated flavone methyl ether has been isolated from Brickellia veronicaefolia and B. chlorolepis. It has been identified as 5,6′-dihydroxy-6,7,2′,3′,4′-pentamethoxyflavone and given the name brickellin.     

Modified polynucleotides. V. Slow-down of nuclease action by 5-alkyluracil-containing DNAs

Poly d/[³H]A-r⁵U/ type of synthetic models of bacteriophage DNAs containing thymine analogues were prepared by DNA polymerase and tested for stability against nucleases /$\text{r}$ was a n-alkyl group from methyl to pentyl/. The 5-pentyluracil-containing copolymer was found to be most stable: 50 % degradation with pancreatic DNase, spleen DNase, snake venom phosphodiesterase or micrococcal nuclease required 3–15 times as much time as that of poly d/A-T/.     

13C NMR spectral analysis of eperuane diterpenes

The ¹³C NMR spectra of some eperuane diterpenes have been recorded and the signals assigned. The substituent shielding effects in these compounds, in comparison with those observed in other series of diterpenes, are also presented.     

First Principles Prediction of Gas-Phase Composition and Substrate Temperature for Diamond Film Growth

Abstract

A model consisting of ten hydrocarbon species and eight reactions is proposed to describe the gas-phase chemistry of diamond film growth. Based on the model, the gas-phase compositions of the chemical species were computed assuming thermodynamic equilibrium using molecular and transition-state data predicted by ab initio molecular orbital theory, and thermodynamic quantities calculated by statistical mechanics. Although the absolute compositions predicted by the model are in fair agreement with experimental data available in the literature, the model qualitatively accounts for experimentally observed changes in the concentrations of various gas-phase species with increasing addition of methane to the feed gas. The calculations also predict the pattern of temperature variance in the gas-phase close to the substrate with changes in methane concentration in the feed gas, leading to first-principles predictions of favorable conditions for diamond growth.     

Adverse effects of extracts of Artocarpus altilis Park,and Azadirachta indica (A. Juss) on the reproductive physiology of the adult female tick,Boophilus microplus (Canest.)

Summary

Adverse effects of extracts from the plants Artocarpus altilis and Azadirachta indica on egg laying and hatching in the tick Boophilus microplus were quantified. A 50% inhibition of egg laying was achieved by a dose of 0.54 and 0.46 μg crude ethanol extract per tick, respectively. These doses also caused a 65% and 80% hatching failure, respectively. Extracts, particularly those of A. indica, inhibit protein and lipid sequestration by ovaries and oocytes. GC-MS analyses revealed reductions in the quantities of four methyl esters sequestered from the ovaries into the oocytes oviposited on the 12th day of engorgement by the treated ticks in the order of (A. indica effects are in parentheses): undecanoic acid 10-methyl-,methyl ester 40% (100%); tetradecanoic acid, methyl ester 100% (100%); tetradecanoic acid, 12-methyl-,methyl ester 100% (100%) and pentadecanoic acid, 14-methyl-,methyl ester 30% (75%).     

Characterization of mycosporine‐serine‐glycine methyl ester,a major mycosporine‐like amino acid from dinoflagellates: a mass spectrometry study

Several unknown mycosporine‐like amino acids (MAAs) have been previously isolated from some cultured species of toxic dinoflagellates of the Alexandrium genus (Dinophyceae). One of them, originally called M‐333, was tentatively identified as a shinorine methyl ester, but the precise nature of this compound is still unknown. Using a high‐resolution reversed‐phase liquid chromatography mass spectrometry analyses (HPLC/MS), we found that natural populations of the red tide dinoflagellate Prorocentrum micans Ehrenberg showed a net dominance of M‐333 together with lesser amounts of other MAAs. We also documented the isolation and characterization of this MAA from natural dinoflagellate populations and from Alexandrium tamarense (Lebour) Balech cultures. Using a comparative fragmentation study in electrospray mass spectrometry between deuterated and non‐deuterated M‐333 compounds and synthesized mono and dimethyl esters of shinorine, this novel compound was characterized as mycosporine‐serine‐glycine methyl ester, a structure confirmed by nuclear magnetic resonance. These isobaric compounds can be differentiated by their fragmentation patterns in MS³ experiments because the extension and the specific site of the methylation changed the fragmentation pathway.     

Effect of Methyl Jasmonate on the Germination and the Degradation of Storage Reserve in Rice Seed

The effects of methyl jasmonate (MeJA, Nippon Zeon Co., Ltd, Tokyo, Japan) on germination and the degradation of storage reserve in rice （Oryza sativa L.） seeds were studied. There were dual effects of MeJA on seed germination and seedling growth of rice, low concentration of MeJA promoted germination and seedling growth whereas high concentration of MeJA inhibited germination and seedling growth. The optimal concentration of promotion was 5×10-7 mol/L. The acid phosphatase activity, α-amylase activity, degradation of starch and salt-soluble proteins were affected same as germination by MeJA. MeJA inhibited the degradation of glutelins, the higher the concentration, the higher the extent of inhibition above 5×10-7 mol/L.The results showed that either promotion or inhibition of germination by MeJA was very close to the effect on the activity of α-amylase. The mechanisms between abscisic acid and MeJA affection on seed germination and seedling growth were compared.