Multiple xenobiotic-inducible P450s are involved in alkoxycoumarin and alkoxyresorufin metabolism in higher plants

O-Dealkylation of two series of fluorescent 7-alkoxy-coumarins and 7-alkoxyphenoxazones by plant cytochrome P450s was investigated in Helianthus tuberosus tuber tissues treated with prototype P450 inducers, environmental pollutants or agrochemicals. Methoxy-, ethoxy-, propoxy-and butoxycoumarins and methoxy- and ethoxyresorufins were metabolized by fplant microsomes. Dealkylation of pentoxy- and benzyloxyresorufins was not detected. All dealkylating activities were enhanced by aging plant tissues in the presence of xenobiotics, in some cases up to 20-fold relative to the activities detected in control tissues. Increases in total P450 in the same tissues never exceeded 3-fold. The isozymes induced by prototype P450 inducers clearly differed from those in mammalian liver. That multiple P450s with overlapping substrate specificities were involved in the metabolism of both alkoxycoumarins and alkoxyresorufins was demonstrated by (1) the differential induction of the activities in response to exposure to xenobiotics, (2) the differential inhibition of the activities by clotrimazole, paclobutrazole and tetcyclacis in aminopyrine and benzo(a)pyrene-treated tissues, and(3) the selective inhibition observed with antibodies raised against purified ethoxycoumarin deethylase fractions. Our results suggest that the measurement of the dealkylation of such fluorescent substrates in plants might be useful to monitor environmental pollution.     

Biotypes of Agrobacterium tumefaciens in Hungary

Isolates of Agrobacterium tumefaciens from Hungary were separated into three biotypes on the basis of their physiological characters. Biotypes 1 and 2 corresponded with those of Keane et al . (1970). The most common isolates were of biotype 2. Isolates from grapevines formed a separate biotype which might be distinguished from biotype 1 by D-(–)tartrate and malonate utilization. Many isolates with biotype-intermediate characters were found. Isolates utilizing D-(–)tartrate, erythritol and malonate were included into biotype 2, although many of them were 3–ketolactose positive. Biotypes were not separated geographically and biotype 1 and 2 apparently occurred together.     

Accumulation and metabolism of aldicarb by the free-living nematodes Aphelenchus avenae and Panagrellus redivivus

The accumulation and metabolism of aldicarb has been compared in two species of free-living soil nematodes, Aphelenchus avenae and Panagrellus redivivus, which differ considerably in their sensitivity to this and other pesticides. Similar levels of aldicarb were found to accumulate in the two species. The results showed that although the rate of uptake of aldicarb was greater in P. redivivus, so also was the rate of metabolism and elimination. Levels of toxic metabolites of aldicarb were two to three times higher in the more susceptible species A. avenae after 24 h incubation than in the less susceptible P. redivivus. The toxicological significance of these findings is discussed in relation to previous work with the organophosphorus pesticide phorate and its effects on the same two nematode species.     

乳酸菌黏附小鼠派伊尔结及影响因子的研究

目的研究乳酸菌结合小鼠派伊尔结（PP）的性质,确定乳酸菌黏附小鼠PP的影响因子。方法测定10株荧光标记的乳酸菌对PP组织切片黏附性,分析细菌表面疏水性和酵母、红细胞凝集性与黏附性的关系。结果凝集酵母、红细胞能力强的乳酸菌,PP黏附性强。除嗜酸乳杆菌（L.acidophilm）外,其他9株乳酸菌的表面疏水性与凝集酵母、红细胞的能力呈显著的负相关性（r=-0．60和r=-0．53,P〈0．05）。L.acidophilm黏附PP的能力最强。L．acidophilm黏附PP能力和红细胞凝集性均可被D（＋）-甘露糖、D（＋）-半乳糖抑制。结论乳酸菌黏附PP的能力受疏水性和表面特异性凝集素的影响。L.acidophilm表面D（＋）-甘露糖、D（＋）-半乳糖特异性凝集素可能参与黏附PP的过程。