Are we analysing knockdown in the right way? how independence of the knockdown-recovery process from mortality may affect measures for behavioural effects in pesticide bioassays

In pesticide bioassays, especially those with neurotoxic agents, effects on animals are typically grouped into classes according to behaviour, such as normal and affected behaviour, which may range from unstable walking behaviour, to unable to move, to mortality. Generally, recovery is observed in all these effect classes, except the last. Mortality, however, disturbs the analysis of the recovery processes because it decreases the number of animals that otherwise could have shown a reversible effect. We consider that this interaction between mortality and other, reversible, effects is a conceptual problem, and give arguments in favour of analysing changes in behaviour and mortality as two independent, simultaneously occurring neurotoxic syndromes. As an illustration, two data sets are analysed in both ways and these show that marked differences may exist between conclusions reached by the two viewpoints. The consequences thereof are discussed in relation to toxico-kinetic explanations for neurotoxicant effects on behaviour and mortality. © 1999 Society of Chemical Industry     

一个水稻新黄绿叶突变体基因的分子定位

在水稻品种武运粳7号中发现了一个黄绿叶自然突变体,经过多代自交形成了稳定的突变系。该突变系和武运粳7号的正反交F2代的遗传分析表明该材料的黄绿叶由1对隐性基因控制,命名为 ygl 2。利用已有的微卫星（SSR）标记和新发展的SSR标记将 ygl 2基因定位于RM1340、RM7269、RM6298、SSR6 16和RM7434、SSR6 5、SSR6 9、RM5957之间,排列位置为RM1340-RM7269-RM6298-SSR6 16 -ygl 2-RM7434-SSR6 5、SSR6 9-RM5957,它们之间的遗传距离分别为238、0.37、0.00、0.62、0.74、0.49、0.86和1.62 cM,这为 ygl 2基因的分子标记辅助选择育种和图位克隆奠定了基础。     

Potential allelopathic effects of Suregada multiflorum and the influence of soil type on its residue's efficacy

This experiment was conducted to determine the potential allelopathic effects of the aqueous extracts and dried leaf powder of Suregada multiflorum and to find the herbicidal effects of its granule on the weed species, barnyardgrass (Echinochloa crus‐galli) and slender amaranth (Amaranthus viridis), in various growth media (germination paper, sand, and soil). Observations in this study demonstrated that the potential and magnitude of their inhibitory effects varied among the plant parts. The leaves and branches possessed the strongest inhibition levels, followed by the bark. The aqueous extract from the leaves of S. multiflorum had a remarkably stronger inhibitory effect on the germination and growth of slender amaranth, compared with barnyardgrass; when applied at the concentration of 100 g L^–1, it completely inhibited the germination and initial seedling growth of slender amaranth. In addition, all the treatments of the dried leaf powder had stronger inhibition effects than the aqueous extract. Interestingly, the inhibitory effects of the dried leaf granule of S. multiflorum were stronger than the effects of the dried leaf powder at equal rates. The degree of inhibitory effect of the S. multiflorum granule, applied in various growing media, can be classified in order of decreasing inhibition as germination paper = sand > clay soil. The present study indicates that the S. multiflorum granule product that was developed in this research has the potential to provide a powerful organic herbicide for controlling slender amaranth.     

Analysis of metsulfuron‐methyl residues in wheat field soil: a comparison of HPLC and bioassay techniques

BACKGROUND: Metsulfuron‐methyl is a low‐application‐rate sulfonylurea herbicide that is widely used to control broad‐leaved weeds in wheat. Owing to its persistent nature, its residues may be present at phytotoxic levels for the next crop in rotation. Therefore, a comparative evaluation of HPLC and bioassay techniques was made for the analysis of this herbicide in wheat field soil. RESULTS: Metsulfuron‐methyl was applied to wheat crop at different rates (4, 8 and 12 AI ha^?1) at 28 days after sowing as a post‐emergence application, and the soil was analysed for metsulfuron‐methyl residues by HPLC and lentil seed bioassay techniques. The bioassay was found to be the more sensitive technique. At the recommended rate of application, 4 g AI ha^?1, the bioassay technique could detect the residue up to 30 days in surface soil, while, with HPLC, residues were not detectable on the 15th day. The half‐lives of metsulfuron‐methyl by HPLC and bioassay were calculated as 6.3–7.8 and 17.5 days respectively. Under field conditions, residues of metsulfuron‐methyl were also detected in subsurface soil by the bioassay technique at trace levels, but were not detected by the solvent extraction/HPLC method. CONCLUSION: Lentil seed bioassay is a more sensitive technique than HPLC. Traces of residues detected in subsurface soil indicated the mobility of metsulfuron‐methyl into lower layers. Copyright © 2009 Society of Chemical Industry     

A Simplified Rice DNA Extraction Protocol for PCR Analysis

DNA molecular marker technology has been advancing rapidly during past decades and its application perspective seems very brilliant in crop breeding, varietal purity test of crop seeds and germplasm fingerprinting [1]. Among various DNA markers, the PCR-based marker is the most popular and efficient one since it needs small amounts of DNA with relative low quality [2]. Meanwhile, PCR is also an essential approach for detection of target genes in transgenic breeding and genetic modified (…     

Pathogenic and genetic diversity of Puccinia triticina from triticale in Poland between 2012 and 2015

Variation among Puccinia triticina isolates collected from triticale in Poland between 2012 and 2015 was studied based on virulence and simple sequence repeat (SSR) markers. Two hundred and forty-two single-uredinial isolates from four geographically separated locations were tested for virulence against 33 near-isogenic Thatcher lines containing known Lr resistance genes, and their molecular genotypes were characterized with 34 SSR markers. Structure and relationships of the regional and annual populations of P. triticina were analysed using an assignment-based approach for both the virulence and SSR data. The molecular marker analysis was based on two different models of SSR evolution: the stepwise mutation model with a variable mutation rate (SMMv) and the infinite alleles model (IAM). A highly significant deviation from Hardy–Weinberg equilibrium among SSR genotypes, a high proportion of heterozygotes, and a moderate association of relationships between virulence phenotypes and SSR genotypes were consistent with the occurrence of clonal lineages of related races within the population. While the results suggest that genetic drift and mutation affect variation within the pathogen population, it seems that migration has the most significant role in shaping the population structure of P. triticina occurring on triticale in Poland.     

嗜卷书虱和嗜虫书虱体内磷酸酯酶的生化与毒理学特性比较研究

采用药膜法对嗜卷书虱和嗜虫书虱进行生物测定,从5种杀虫剂对两种书虱的LC50可以看出,嗜卷书虱对两种拟除虫菊酯类药剂较嗜虫书虱敏感,嗜虫书虱对丁硫克百威较为敏感,而对有机磷类药剂的作用两种书虱的敏感性相似。两种书虱体内酸性磷酸酯酶（ACP）和碱性磷酸酯酶（ALP）的活力比较结果表明：嗜卷书虱和嗜虫书虱体内ACP的比活力为分别14 μmol/mg&#8226;30 min和2.2 μmol/mg&#8226;30 min,ALP的比活力分别为0.092 μmol/mg&#8226;30 min和0.046 μmol/mg&#8226;30 min。经方差分析,两种书虱ACP和ALP的比活力之间均存在显著性差异(p<0.05)。动力学参数比较结果显示,两种书虱ACP的V _max值之间的差异达到显著水平,而ALP的K _m值之间存在显著性差异。离体试验结果表明,5种药剂对磷酸酯酶的作用各不相同,个别药剂在低浓度下表现诱导作用,说明磷酸酯酶在不同外源毒物的解毒代谢过程中所起的作用有所不同。     

Effect of partial plant resistance in brassicas on tolerance of diamondback moth (Plutella xylostella) larvae to cypermethrin

Brassica cultivars with varying degrees of partial plant resistance were fed to larvae (up to 4th instar) of the diamondback moth (DBM), Plutella xylostella, and were bioassayed by topical application of cypermethrin to investigate the interaction of plant resistance with insecticide. Larvae reared on the least preferred brassica, Minicole, showed a significantly higher LD₅₀ value than those on the most preferred brassica, Chinese cabbage. Bioassay of 4th instar DBM larvae fed on artificial diet containing pure compounds of glucosinolates revealed a negative interaction between their susceptibility to cypermethin and certain glucosinolates (in particular sinigrin), suggesting that such compounds induced the production of insecticide-detoxifying enzymes.