Methylation of histone H3 at lysine 4 and expression of the maltase-glucoamylase gene are reduced by dietary resistant starch

Methylated histone H3 at lysine 4 (K4) is associated with euchromatin and is involved in the transactivation of genes. However, it is unknown whether histone methylation is involved with changes in gene expression induced by nutrients. In this study, we examined whether methylations of histone H3 at K4 on maltase-glucoamylase (Mgam), which is responsible for the digestion of starch in the small intestine, as well as Mgam expression were altered by feeding rats an indigestible starch (resistant starch, RS). The mRNA and protein levels and the activities of MGAM were reduced in rats fed an RS diet compared with those fed a regular starch diet. Furthermore, we found that decreases in di- and tri-methylation of histone H3 at K4, as well as reduced acetylation of histones H3 and H4 on the Mgam gene were associated with a reduction of Mgam gene expression. These results suggest that the reductions of jejunal MGAM levels and activities caused by the RS diet are regulated at the mRNA level through a decrease in methylation of histone H3 at K4 and reduced acetylation of histones H3 and H4 on the Mgam gene.     

Studies on Nicotinoids1) as an Insecticide

Toxicities of some nicotinoids as an insecticide were determined. 5′-methylnornicotine, a new synthetic isomer of nicotine, shows similar toxicity to nicotine. The essential moiety in nicotinoids molecule responsible for high toxicity may be 3-pyridylmethylamine group, the amino nitrogen of which must have high basicity (p^K_a′: 7.4~9.0). All nicotinoids of high toxicity are estimated to be largely as monocation at physiological pH of 7.     

Evaluation of O,O-Dialkyl O-Cyanophenyl Phosphates and Phosphorothioates as Insecticides

Various O,O-dialkyl O-cyanophenyl phosphates and phosphorothioates were prepared and their biological activities were examined. Among them, O,O-dimethyl O- (4-chloro-2-cyanophenyl) phosphorothioate was found to have selective and high toxicity to houseflies. O,O-Dimethyl O- (4-cyanophenyl) phosphorothioate, O,O-diethyl O- (4-cyanophenyl) phosphorothioate and O,O-diethyl O- (2-chloro-4-cyanophenyl) phosphorothioate showed high insecticidal activty to American cockroaches, though the former two were not so effective to houseflies. The dimethyl esters of these series exhibited markedly lowered mammalian toxicity. Among the O-ethyl O-cyanophenyl phenylphosphonothioates, O-ethyl O- (2-chloro-4-cyanophenyl) phenylphosphonothioate was highly effective to mites, while less effective to insects.     

Flagellum-mediated motility in Pelotomaculum thermopropionicum SI

The basic functions of a propionate-oxidizing bacterium Pelotomaculum thermopropionicum flagellum, such as motility and chemotaxis, have not been studied. To investigate its motility, we compared with that of Syntrophobacter fumaroxidans, an aflagellar propionate-oxidizing bacterium, in soft agar medium. P. thermopropionicum cells spread, while S. fumaroxidans cells moved downward slightly, indicating flagellum-dependent motility in P. thermopropionicum SI. The motility of P. thermopropionicum was inhibited by the addition of carbonyl cyanide m-chlorophenyl hydrazone, a proton uncoupler, which is consistent with the fact that stator protein, MotB of P. thermopropionicum, shared sequence homology with proton-type stators. In addition, 5-N-ethyl-N-isopropyl amiloride, an Na⁺ channel blocker, showed no inhibitory effect on the motility. Furthermore, motAB of P. thermopropionicum complemented the defective swimming ability of Escherichia coli ?motAB. These results suggest that the motility of P. thermopropionicum SI depends on the proton-type flagellar motor.     

Synthesis, antimicrobial activity and conformational analysis of novel substituted pyridines: BF(3)-promoted reaction of hydrazine with 2-alkoxy pyridines

Some new 2-alkoxy-3-cyano-4,6-diarylpyridines 3,4 were synthesized by condensation of different alpha,beta-unsaturated ketones 1 with malononitrile 2, followed by cyclization in sodium alkoxide/alcohol system. Lewis acid-catalyzed reaction of 4 with hydrazine afforded the corresponding 1H-pyrazolo[3,4-b]pyridines 5. The potency of the results as antimicrobial agents has been evaluated. The structure of the newly prepared compounds was assessed by microanalysis, IR and NMR spectra. Molecular mechanics (MM2) and semiemperical (AM1) molecular orbital calculations have been performed for the most biologically active compounds 5b and c to get insight into their molecular structures and to learn more about their stable molecular conformations.