Negative effects of agrocin 84-encoding Agrobacterium plasmids on symbiotic properties of Rhizobium meliloti

Two plasmids, pAgK84::Tn5-Mob from Agrobacterium radiobacter carrying genes for the production of agrocin 84, and RP4-4 from E. coli were inserted either separately or together into a strain of Rhizobium meliloti. Each of these plasmid-containing R. meliloti transconjugants was less effective than the wild type strain in their ability to fix nitrogen in Medicago tornata. The pAgK84::Tn5-Mob-containing transconjugant was significantly less effective than that containing RP4-4. The transconjugant strains were inferior to the wild type strain in their ability to nodulate seedlings and to compete for nodulation.     

The contribution of setal blades to effective swimming in the aquatic mite Limnochares americana (Acari: Prostigmata: Limnocharidae)

Two rows (anterior and posterior) of long fine setae inserted on the 3rd, 4th and 5th segments of the last two pairs of legs of L. americana form functional swimming blades. Each swimming setal is mounted in a mobile basal socket, and the structure of the setal base and socket configuration ensure that the blades will be passively erected during the leg's power stroke to provide increased thrust and collapsed during the recovery stroke to reduce water resistance. The erect swimming blades increase the effective area for thrust by approximately 500%, making it possible for the mite to lift itself off the bottom. The IVth legs contribute the greater proportion of the thrust developed during paddling, and the 4th segment (genu) bears the largest swimming blades on both legs.     

External coincidence and photoperiodic time measurement in the spider mite Tetranychus urticae

The incidence of diapause in the spider mite Tetranychus urticae was predicted for various photoperiodic regimes, according to the external coincidence model of photoperiodic time measurement. A phase response curve was constructed for the hypothetical photoperiodic oscillator in these mites: entrainment of this photoperiodic oscillator to a variety of ‘complete’ and ‘skeleton’ photoperiods was calculated using a transformation method for circadian rhythms. The external coincidence model proved adequate to describe experimental results with T. urticae in ‘complete’ photoperiods (T = 24 hr), symmetrical ‘skeleton’ photoperiods (T = 24 hr), asymmetrical ‘skeleton’ photoperiods (T = 24 hr) (night-interruption experiments), and ‘resonance’ experiments, in which the light component of a light/dark cycle was held constant at 8 hr and the dark component was varied over a wide range in successive experiments, providing cycles with period lengths up to 92 hr. The external coincidence model proved inadequate to explain results obtained in a ‘T-experiment’ with T. urticae comprising 1 hr pulses of light in a cycle of LD1:17.5 (T = 18.5 hr) with the first pulse of the train starting at different circadian phases. The validity and limitations of the external coincidence model as an explanation of photoperiodic time measurement in T. urticae are discussed in view of the above results.     

The large mimosoid genus Inga Mill. (tribe Ingeae,Caesalpinioideae) is nodulated by diverse Bradyrhizobium strains in its main centers of diversity in Brazil

Inga (Caesalpinioideae) is the type genus of the Ingeae tribe in the mimosoid clade. It comprises about 300 species, all trees or treelets, and has an exclusively neotropical distribution, with Brazil as its main center of diversity. In this study, we analyzed the diversity of 40 strains of rhizobia isolated from root nodules collected from ten species of Inga belonging to different types of vegetation in Brazil. Sequences of their housekeeping genes (dnaK, recA, rpoB, gyrB and glnII), 16S rRNA genes, internal transcribed spacer (ITS) regions, as well as their symbiosis-essential genes (nodC and nifH) were used to characterize them genetically. The ability of the rhizobia to form nodules on Inga spp., and on the promiscuous legume siratro (Macroptilium atropurpureum) was also evaluated. A multilocus sequence analysis (MLSA) combined with an analysis of the ITS region showed that the isolates were distributed into four main groups (A-D) within the large genus Bradyrhizobium. Analysis of the nodC and nifH genes showed that the isolates formed a separate branch from all described species of Bradyrhizobium, except for B. ingae. Most of the tested isolates formed nodules on siratro and all isolates tested nodulated Inga spp. Our results suggest a unique co-evolutionary history of Bradyrhizobium and Inga and demonstrate the existence of potential new species of microsymbionts nodulating this important and representative genus of leguminous tree from the Caesalpinioideae mimosoid clade.     

刺槐核糖体蛋白同源基因RpRPL22在共生结瘤过程中功能研究

目的: 核糖体蛋白(RPs)属于多功能蛋白,能够参与调控细胞生长和响应胁迫条件。RpRPL22是一个从豆科植物刺槐中分离得到的结瘤相关基因,通过序列比对发现其与核糖体大亚基蛋白RPL22高度同源。对其如何通过调控根瘤菌侵染而在共生结瘤过程中发挥重要作用进行了较为深入的探索。方法: 利用实时荧光定量PCR技术(qRT-PCR)分析RpRPL22在接菌后不同时间及不同植物组织的表达变化。利用cDNA末端快速扩增技术(RACE)获得目的基因cDNA全长。通过GFP报告基因进行RpRPL22亚细胞定位分析。通过Gateway BP重组技术构建RNA干扰(RNAi)重组载体,借助电转化法将重组载体转至农杆菌K599,利用农杆菌介导植物根部,接菌后观察和测量植株表型。首先从宏观水平统计观察目的基因是否对结瘤过程有影响,其次从分子水平揭示目的基因在共生结瘤过程的重要功能。结果: 不同接菌时期、不同植物组织目的基因qRT-PCR相对表达量结果显示,几乎在所有取样的接菌时间,目的基因RpRPL22在接菌根中的相对表达量都低于未接菌对照根,只有接菌后第25天除外。在成熟的根瘤中,接菌后第25天该基因的表达量也最高。洋葱表皮和毛状根亚细胞定位结果均显示在椰菜花叶病毒(CaMV)的35S启动子控制下,RpRPL22融合绿色荧光蛋白GFP的荧光信号在细胞核和细胞质有明显的表达。RNAi转化植株的表型统计观察结果,比如植株鲜重、植株的有效结瘤数目较对照组均有明显的降低;同时RNAi转化植株在根瘤菌侵染过程形成的侵染线数目和根瘤原基数目较对照均显著降低。根瘤切片实验用于观察根瘤显微超微结构,结果显示RNAi植株根瘤中固氮区的受菌侵染细胞数目与对照相比明显减少。电镜观察根瘤单个受菌侵染细胞中类菌体形态显示,RNAi根瘤中类菌体侵染细胞胞体多呈不规则形状,皱缩变形严重,环类菌体周间隙空间增大,多共生体融合,表现出细胞凋亡的迹象。对照根瘤中的受菌侵染细胞胞体多呈圆形椭圆形,胞质饱满丰富且分布均匀,细胞发育正常,表明RNAi植株根瘤发育过程明显受阻。结论: 核糖体蛋白(RP)能够参与调控豆科植物共生结瘤过程,相关同源基因RpRPL22可能在起始根瘤菌侵染植物和阻止类菌体降解过程中起重要作用。     

盐城地区未成年过敏性疾病患者吸入性过敏原IgE检测结果分析

摘要 目的：通过研究分析盐城地区未成年过敏性疾病患者吸入性过敏原特异性IgE检测结果分布变化特点,为过敏性疾病预防和临床诊疗提供科学依据。方法：自2020年1月至2021年3月期间,选择430例未成年(<18岁)过敏性疾病患者,血清检测方法采用欧蒙公司生产的过敏原特异性IgE检测试剂盒。结果：430例患者中,血清过敏原IgE阳性166例(38.60%),其中尘螨和屋尘是主要的吸入性过敏原。血清IgE阳性率男性39%,女性36% (P>0.05),中学组女性阳性率（61.11 %）高于男性（45.83 %）（P<0.05）。不同年龄组间IgE阳性率有统计学差异（P<0.05）,蟑螂、尘螨、霉菌、豚草、屋尘和年龄组间有统计学差异（P<0.05）。不同临床症状与IgE阳性率有统计学差异(P<0.05),其中呼吸道过敏症状组IgE阳性率最高（48.30 %）,不同症状组间主要过敏原都是尘螨。屋尘阳性患者均合并尘螨阳性,其中70.93 %的患者表现出了呼吸道过敏症状。结论：尘螨、屋尘是盐城地区未成年过敏性疾病患者最主要的吸入性过敏原,研究血清过敏原分布,对未成年人过敏性疾病的预防、诊疗具有重要意义。     

麦田肥料减施下深耕对麦叶爪螨和麦岩螨种群发生的影响

为探究不同耕作方式和肥料水平对两种麦田害螨(麦叶爪螨Pentfaleus major和麦岩螨Petrobia latens)种群发生的影响,2019-2020年研究了浅耕(耕深13 cm)和深耕(耕深25cm)下标准施肥(600 kg/hm2)和肥料减施(375 kg/hm2)麦田两种害螨的若虫、成虫和种群发生动态.结果表明:相同肥料和耕作处理中麦叶爪螨发生量都明显高于麦岩螨发生量,麦叶爪螨是麦田主要害螨.与标准肥处理相比,肥料减施显著降低了 2019年浅耕和深耕下麦岩螨若虫发生量,以及2020年深耕麦田麦岩螨种群发生量.另一方面,与浅耕处理相比,深耕显著降低了 2019年标准肥麦田麦岩螨若虫发生量,并显著降低了 2019年和2020年标准肥麦田麦叶爪螨成虫发生量,以及2019年和2020年标准肥麦田麦叶爪螨和麦岩螨种群发生量.可见,肥料减施和深耕处理都可降低麦田麦叶爪螨和麦岩螨种群发生量,有利于实现麦田害螨生态防控.     

New water mites of the family Hygrobatidae (Acari,?Hydrachnidia) from Turkey

In this study, the findings of three water mite species of the family Hygrobatidae collected from different streams in Turkey were evaluated. Hygrobates (s. str.) anatolicus Esen & Pešić, sp. n. is described as new for science. Hygrobates (Rivobates) diversiporus Sokolow, 1927 and Atractides (s. str.) nikooae Pešić, 2004, which were illustrated and thoroughly discussed, are new records for the Turkish fauna.     

Positive association between thrips and spider mites in seedling cotton

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Survival,development and reproduction of Euseius finlandicus (Oudemans) (Acari: Phytoseiidae) fed on various kinds of food substances

Laboratory experiments were conducted to investigate the effect of diet on the biology of the phytoseiid mite, Euseius finlandicus (Oudemans). The predatory mite was able to develop and reproduce better when fed on the eriophyid mites, Aceria olivi (Zaher and Abou-Awad), Aceria dioscoridis (Soliman and Abou-Awad) and Cisaberoptus kenyae (Keifer). The developmental time of immature stages was the shortest when fed on motile stages of eriophyid mite species, followed by the spider mite, Tetranychus urticae Koch, and then pollen grains of Ricinus communis L., Phoenix dactylifera L. and Helianthus annuus L. Total egg production was highest when the predator fed on A. olivi, A. dioscoridis and C. kenyae recording at the rate of 51.0 50.0 and 43.84 eggs/female, respectively, but lowest on pollen grains, R. communis, P. dactylifera and H. annuus at the rate of 11.96, 5.3 and 2.0 eggs/female, respectively. But, the reproduction was nil on the tetranychid mite, T. urticae. Also, sex ratio of the progeny favoured females, when the predatory mite was reared on the eriophyid preys. E. finlandicus recorded the highest intrinsic rate of increase (r_m?=?0.31 females/female/day) when fed on A. dioscoridis, followed by (0.30 and 0.23 females/female/day) when fed on A. olivi and C. kenyae, respectively. In contrast, the lowest intrinsic rate of increase (r_m?=??0.31) was noted when fed on H. annuus pollen grains. The eriophyid mite, as a prey, recorded the shortest developmental time and highest oviposition rate of E. finlandicus.