Neurohemal organ extracts effect the ventilation oscillator in crustaceans.

Extracts of the pericardial organs of crabs injected into intact animals cause an increase in the frequency of scaphognathite beating. The active factor is not dopamine of 5-hydroxytryptamine, which are present in pericardial organs; it is probably a peptide. The factor may represent a hormonal mechanism of coordinating heart rate and ventilation.     

四株虫生真菌的鉴定及其醇提取物对Hela细胞的抑制作用

[背景]虫生真菌是非常重要的自然资源,但被发现和利用的种类相对较少.[目的]鉴定从野外采集的4株虫生真菌,并探讨4株菌的醇提物对宫颈癌Hela细胞的抑制活性.[方法]结合形态学特征与rDNA ITS和β-Tubulin序列分析对4株虫生真菌进行种类鉴定,采用四甲基偶氮唑盐[3-(4,5-Dimethyl-2-Thiaz...     

Amperometric study of the inhibitory effect of carboxylic acids on tyrosinase

A tyrosinase-modified Pt electrode, based on physical entrapment of the enzyme in agar–agar gel, was constructed and used to investigate the inhibitory effect of six carboxylic acids. At an applied potential of −50 mV versus saturated calomel electrode (SCE), the bioelectrode develops a fast, steady state response, linearly correlated with the phenol concentration up to 10 mg/l, with a sensitivity of 3.7 nA l/mg. A kinetic analysis of the amperometric response to phenol, recorded in the absence and in the presence of carboxylic acids (benzoic, 3-bromobenzoic, 4-ethylbenzoic, acetic, phenylacetic, 2-naphthylacetic acids), revealed that for the first four compounds the inhibition process corresponds to an uncompetitive one. Using the Lineweaver–Burk linearization the inhibition constants as well as the inhibition coefficients were calculated for the strong inhibitors: benzoic, 3-bromobenzoic, 4-ethylbenzoic and acetic acids.     

Changes in the rooting inhibitory effect of chestnut extracts during cold storage of the cuttings

Extracts of cold stored chestnut cuttings ( Castanea sativa Mill.) were examined for the inhibitory effect on the stimulation of rooting by 1AA which has been detected previously in extracts from freshly collected cuttings. The extracts were fractionated by paper chromatography and the different zones of the chromatograms were bioassayed together with 1AA by the bean rooting test. The bean rooting test showed that the inhibitory effect decreased with the length of cold storage period, so that after 5 months of storage, the inhibitory effect had disappeared, and a root promoting zone was found on the chromatograms. A comparative study of phenolics in this zone, before and after cold storage, revealed the formation of vanillyl and salicyl alcohols in the chilled material. Vanillyl and salicyl alcohols are rooting stimulators and increase the effect of 1AA on rooting in bean cuttings.     

Alcoholic fermentation: On the inhibitory effect of ethanol

The inhibitory effect of ethanol is studied during alcoholic fermentation in strict anaerobiosis (initial dissolved oxygen stripped by gasing pure nitrogen). It is demonstrated that the ethanol produced during the batch fermentation is more inhibitory than the added ethanol (in the range of 0 to 72.6g/liter). By analogy with noncompetitive enzyme kinetic inhibition, the inhibition constant for added ethanol is 105.2 g/liter and 3.8 g/liter for produced ethanol, which exhibits the same inhibition effects in all experiments where ethanol was added. The measurement of the intracellular alcohol concentration can explain the dual inhibitory effects of ethanol.