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91.
茚虫威属于噁二嗪类杀虫剂,与大多数杀虫剂不同的是其进入害虫体内需要经活化代谢转变成N-去甲氧羰基代谢物(decarbomethoxylated metabolite,DCJW)后不可逆地阻断钠通道,进而发挥杀虫活性。茚虫威由于其作用机制不同于常见的使钠离子通道延迟关闭的菊酯类药剂而被广泛用于鳞翅目和一些同翅目、鞘翅目害虫的防治。抗药性是任何杀虫药剂使用后面临的问题,茚虫威也不例外,许多害虫对其产生了不同程度的抗性。昆虫对茚虫威产生抗性的机制包括酯酶活性、谷胱甘肽S-转移酶(glutathione S-transferase,GST)和P450活性的增加以及分子靶标F1845Y、V1848I、L1014P的突变,这些对茚虫威抗性机制的研究基本都是基于抗性种群和敏感种群开展的,需要进一步验证其对抗性研究的贡献度。针对我国田间害虫种群对茚虫威的抗性现状,及时实施对茚虫威有效的抗性治理是迫切的。对于茚虫威的抗性治理除了传统的杀虫药剂轮用、混用外,需要利用其作用机制特点开展抗性治理策略研究。一是充分利用其活化代谢的特点,开展组合药剂的研究应用;二是菊酯类药剂和茚虫威的作用机制均与钠离子通道有关,但是前者是使钠离子通道关闭延迟,而后者是阻断钠离子通道,开展相关基础研究,使菊酯类药剂与茚虫威合理地用于抗性治理中。本文综述了茚虫威的抗性现状、抗性机制与交互抗性、茚虫威的抗性风险评价,针对茚虫威的抗性特点提出了抗性治理策略。 相似文献
92.
Organic N constitutes more than 90% of total N in surface soil horizons. Amino acids, peptides and proteins represent the
most abundant N species. There are indications that clay minerals influence the degradation of proteins, but little is known
about the effect of oxides and hydroxides on protein decay. We therefore conducted an incubation experiment with mixtures
of beech leaf litter and Fe oxide, Al hydroxide, Mn oxide or quartz sand. The protein amounts (quantified as α-NH2–N) during the 498-day experiment were recorded. During the first 90–239 days, plant-derived proteins were decomposed, resulting
in a decline of protein amounts to about 60% of the initial value. Later in the experiment, the protein amounts increased
again to between 70% and 90% of the initial amount, because microbial resynthesis of proteins outweighed decomposition. The
change from dominating decomposition to prevailing microbial resynthesis occurred when the microorganisms had to adapt to
less favourable conditions and therefore built new, protein-rich biomass. Although the mineral phases did not influence protein
decomposition initially, Fe oxide and Al hydroxide stabilized plant-derived proteins. Al hydroxide reduced protein resynthesis
in the second phase of the experiment, probably due to a reduction of microbial activity. Mn oxide increased protein decomposition
and lowered microbial resynthesis due to its oxidative properties. The mineral phases therefore resulted in a shift of the
relative intensities of protein decomposition and microbial resynthesis.
Received: 26 August 1998 相似文献
93.
系统探讨了几种激活方法对水牛卵母细胞孤雌发育的影响。体外成熟 (IVM) 2 6 h的水牛卵母细胞经 7%乙醇(EH)、钙离子载体 (A2 3187)或离子霉素 (Ion)激活处理 5 min后 ,在 2 m mol/ L 6 -甲二氨基嘌呤 (6 - DMAP)中培养 3~4 h,然后再继续培养 6~ 11d,观察其胚胎发育情况。结果发现 ,5μmol/ L Ion激活处理的水牛卵母细胞分裂率显著高于 EH处理的卵母细胞 (6 3.0 % vs5 4 .2 % ,P<0 .0 5 ) ,其原核形成率也显著高于 EH处理的卵母细胞。激活处理前 ,无Ca2 培养液孵育时间的长短 ,对水牛卵母细胞孤雌发育无显著影响 (P>0 .0 5 )。如用 A2 3187激活处理水牛卵母细胞 ,其激活分裂率则随着浓度的升高而提高。从而表明 ,5 μmol/ L Ion可有效激活水牛卵母细胞 相似文献
94.
啤酒大麦使用W -HE生物表面活化剂、C -HE植物生长调节剂、喷施宝、丰产宝、生根粉能促进大麦生育前期的生长发育 ,增加分蘖 ,抑制后期的节间生长 ,有利于根系的发育和干物质的积累 ,对植株有较为明显的活化和调节作用 ,增产效果明显 相似文献
95.
显微注射Ca^2+激活小鼠M Ⅱ期卵母细胞 总被引:2,自引:0,他引:2
胞质内显微注入Ca^2+可以激活小鼠M Ⅱ期卵母细胞,且随着卵龄的增加,激活率明显升高。卵龄小于16h(hCG注射后)注射Ca^2+引起的激活率很低,卵龄超过18h,激活率达到50%以上。卵龄小于16h的卵母细胞,卵内注入超纯水未能激活卵母细胞,而在18 ̄19h卵龄组,注射水的对照组激活率为35%,但显著或极显著地低于注射Ca^2+的试验组。激活前注射EDTA卵母细胞的激活率约为30%,激活后注射 相似文献
96.
97.
98.
In most interspecific hybridization among diploid Brassica species (n = 8, 9, 10), few or no hybrids are obtained, and the three crosses of tetraploid (n = 17, 18, 19) by diploid species are usually only partially successful, especially in one of the reciprocal crosses. Such a cross-incompatibility complex is explained in this paper by a polar-nuclei activation (PNA) hypothesis which proposes two reversible functions, a normal reproduction and a sexual barrier, of double fertilization in higher plants. The first, i.e. the relative activating value (AV) of diploid species, was estimated as 1.0–3.5, whereas that of tetraploid species was 2.7–5.2. In addition, crosses with a polar nuclei activation index (AI) of about 15–87 % were compatible but those beyond the two limits were incompatible, 50 % of those showing normal seed development after self-pollination. 相似文献
99.
Study on the Changes of the Amount of Microorganism and Microbial Biomass Carbon in Soil of Greenhouse Cropping 总被引:3,自引:1,他引:3
通过对四川省温江、双流两地不同设施种植年限土壤中微生物数量及其生物量碳的研究,结果表明,不同设施种植年限大棚土壤中的微生物数量是露地的1.63~3.50倍,且大棚土壤中好气性微生物总数随种植年限的增加有逐渐降低的趋势,三大微生物数量占微生物总数的比例中,细菌表现为随设施种植年限的增加而增加;放线菌和真菌表现为下降;露地土壤微生物多样性指数分别是设施年限为1a、2a和4a的大棚土壤的1.29倍、2.28倍和3.45倍,前者明显高于后者。随设施年限的增加,土壤微生物生物量碳、有机碳及微生物对有机碳的利用率都表现 相似文献
100.
This study was designed to examine whether or not specific tree species (Picea glauca, Picea mariana, Pinus banksiana, Populus tremuloides), their post-fire stand age, or their position in a successional pathway had any significant effect on the functional diversity of associated soil microbial communities in a typical mixed boreal forest ecosystem (Duck Mountain Provincial Forest, Manitoba, Canada). Multivariate analyses designed to identify significant biotic and/or abiotic variables associated with patterns of organic substrate utilization (assessed using the BIOLOG™ System) revealed the overall similarity in substrate utilization by the soil microbial communities. The five clusters identified differed mainly by their substrate-utilization value rather than by specific substrate utilization. Variability in community functional diversity was not strongly associated to tree species or post-fire stand age; however, redundancy analysis indicated a stronger association between substrate utilization and successional pathway and soil pH. For example, microbial communities associated with the relatively high pH soils of the P. tremuloides-P. glauca successional pathway, exhibited a greater degree of substrate utilization than those associated with the P. banksiana-P. mariana successional pathway and more acidic soils. Differences in functional diversity specific to tree species were not observed and this may have reflected the mixed nature of the forest stands and of their heterogeneous forest floor. In a densely treed, mixed boreal forest ecosystem, great overlap in tree and understory species occur making it difficult to assign a definitive microbial community to any particular tree species. The presence of P. tremuloides in all stand types and post fire stand ages has probably contributed to the large amount of overlap in utilization profiles among soil samples. 相似文献