Evaluation of alternative substrates for determining methane-oxidizing activities and methanotrophic populations in soils

The magnitude of methane emission is a net result of methane production and the oxidation rate. The possibility of measuring oxidized products of alternative substrates of methane monooxygenase was examined to determine methane-oxidizing ability of soils, and to count methanotrophic populations in soils. Wetland rice soils were incubated under methane containing air to enirch the methanotrophs. Methane loss and oxygen uptake were inhibited by acetylene, dimethylether, and nitrapyrin (N-Serve). Acetylene was used routinely, because it inhibited methane oxidation even at a low concentration of 0.03 to 0.06 l ml^-1 in the incubation headspace. Propylene at 10 kPa was used as an alternative substrate of methane monooxygenase, and the formation of propylene oxide was measured. When soils were incubated under methane, their methane-oxidizing activity increased. Propylene oxide formation increased simultaneously. Acetylene also blocked propylene oxidation. The results of several experiments and propylene oxide formation (r=0.87 after long-transformation). These results indicate that propylene oxide formation can be used as a semiquantitative measure of the methane-oxidizing activity of soils. The colonies of soluble methane monooxygenase-forming methanotrophs were counted on Cu-deficient methanotroph agar medium by the formation of naphthol from haphthalene. The counts increased from 10⁴ (0 days) to 10⁷ (21 days) g^-1 soil during oxic incubation under methane.     

Regulation of mammalian tooth cusp patterning by ectodin

Mammalian tooth crowns have precise functional requirements but cannot be substantially remodeled after eruption. In developing teeth, epithelial signaling centers, the enamel knots, form at future cusp positions and are the first signs of cusp patterns that distinguish species. We report that ectodin, a secreted bone morphogenetic protein (BMP) inhibitor, is expressed as a "negative" image of mouse enamel knots. Furthermore, we show that ectodin-deficient mice have enlarged enamel knots, highly altered cusp patterns, and extra teeth. Unlike in normal teeth, excess BMP accelerates patterning in ectodin-deficient teeth. We propose that ectodin is critical for robust spatial delineation of enamel knots and cusps.     

Specialized inhibitory synaptic actions between nearby neocortical pyramidal neurons

We found that, in the mouse visual cortex, action potentials generated in a single layer-2/3 pyramidal (excitatory) neuron can reliably evoke large, constant-latency inhibitory postsynaptic currents in other nearby pyramidal cells. This effect is mediated by axo-axonic ionotropic glutamate receptor-mediated excitation of the nerve terminals of inhibitory interneurons, which connect to the target pyramidal cells. Therefore, individual cortical excitatory neurons can generate inhibition independently from the somatic firing of inhibitory interneurons.     

Environmental factors affecting productivity, indican content, and indigo yield in Polygonum tinctorium Ait., a subtropical crop grown under temperate conditions

Polygonum tinctorium Ait. is a herbaceous subtropical annual plant, belonging to the family Polygonaceae. Within the cells of its leaves P. tinctorium accumulates large amounts of a colorless glycoside, indican (indoxyl beta-d-glucoside), from which the blue dye indigo is synthesized. P. tinctorium is well-known in Japan, where it had been cultivated to produce natural indigo for textile dyeing, whereas it represents a potentially interesting new crop in Europe. To better understand the effects of environmental parameters on P. tinctorium crop production and indigo yield, field experiments were carried out in central Italy under temperate climate. Three lines were tested during the 2001 and 2002 growing seasons, and plant/leaf yields as well as indican contents were evaluated. The results showed that P. tinctorium grown in temperate climate conditions can be harvested three times a year. Yields of 82 and 120 t ha(-1) of fresh plant yield were obtained in 2001 and 2002, respectively. The contrasting weather conditions between the two years significantly affected biomass production, which was higher in the 2002 season, characterized by wet weather conditions. The cycle length from sowing to the last harvest was accomplished in 229-238 days when plants had accumulated 2017-2018 degrees C. Green leaves accounted for 40-45% by weight of fresh plant tissue and contained 11-20 g kg(-1) indican. The three lines did not significantly differ in the main productive parameters or in fresh leaf indican content (14.1 g kg(-1) mean value). Photosynthetic active radiation influences indican leaf production according to the model y = 0.0004x + 8.566 (P < 0.01, correlation coefficient = 0.818). Indican content ranged from 12 to 25 g kg(-1) of fresh leaves with PAR daily values from 10000 to 40000 mEinstein m(-2) (recorded in May and at the end of July-beginning of August, respectively). The results indicate that in nonlimiting rainfall conditions a very high indican content and a potentially high indigo yield can be obtained by cultivating P. tinctorium in this pioneer geographical area.     

A novel series of O,O-diethyl O-(1,3-disubstituted-1,2,4-triazol-5-yl) phosphorothioates. Part II. Quantitative structure–activity relationships

The in-vivo toxicity data of 33 O,O-diethyl O-(1-alkyl-3-R″-1,2,4-triazol-5-yl) phosphorothioates, reported in Part I of this series, were subjected to multiregression analyses for the following organisms: Leptinotarsa decemlineata (larvae), Macrosiphum euphorbiae (aphids), Culex pipiens (adults), Spodoptera littoralis (larvae) and the rat. The activities were found to depend mainly on the steric parameters of R″, these being best expressed by the values L, B₁ and B₄ of the computer program STERIMOL. It was shown that there were different steric requirements for each species and these are discussed. The predictive values of the best equations were also estimated.