Influence of wolbachia infection on the fitness of the stored-product pest Liposcelis tricolor (Psocoptera: Liposcelididae)

Wolbachia are maternally inherited intracellular bacteria (Rickettsiaceae) that infect a wide range of arthropods and nematodes and that are associated with various reproductive abnormalities in their hosts. In this study, the effects of removal of Wolbachia infection on development, survival, and reproduction of Liposcelis tricolor Badonnel (Psocoptera: Liposcelididae) were investigated in laboratory. The Wolbachia-free strain was obtained by the removal of Wolbachia infection by using 1% rifampicin treatment on the Wolbachia-infected strain (control) for 4 wk, and no Wolbachia gene product was detected in this strain throughout the experiment. The results showed that the removal of Wolbachia infection had negative effects on the fitness of L. tricolor. Compared with the control strain, the Wolbachia-free strain (both in the first [F1] and second [F2] generation) had prolonged developmental times, reduced survivorship of immature stages, and reduced fecundity and longevity, resulting in much smaller rm values. Using rm values, the fitness for Wolbachia-free F1 and F2 relative to the control were calculated as 0.45 and 0.27, respectively. The results of this study further confirmed our previous conclusion that Wolbachia infection have positive effects on fecundity and fertility of L. tricolor, and for optimal reproduction of L. tricolor, Wolbachia must be present in psocids.     

Cardinium is associated with reproductive incompatibility in the predatory mite Metaseiulus occidentalis (Acari: Phytoseiidae)

Cardinium, a bacterium from the Bacteroidetes group, is associated with reproductive manipulations such as cytoplasmic incompatibility, parthenogenesis, and feminization in some arthropod species. We, and others, have shown that Cardinium, but not Wolbachia, is an endosymbiont in some populations of Metaseiulus occidentalis, a phytoseiid mite that is an important predator of spider mite pests of agricultural crops. However, the precise biological effects that Cardinium may have on M. occidentalis remain unclear. In this study we show, in two sets of crosses between different colonies of Cardinium-free (C-) M. occidentalis females and Cardinium-containing (C+) males, that fecundity was reduced in parental females, F1 progeny survival rates were reduced, and fewer female progeny were produced when compared to the reciprocal and control crosses. There were no differences in these attributes in the reciprocal and two control crosses. Cardinium was transmitted maternally but there was no observed paternal transmission. Finally, Cardinium did not cause asexual (thelytoky) reproduction in M. occidentalis. Thus, Cardinium is associated with nonreciprocal reproductive incompatibility in M. occidentalis and our results support the hypothesis that Cardinium is a reproductive parasite in this agriculturally important predator. Cardinium may therefore affect the evolution and ecology of M. occidentalis and biological control efforts using this mite.     

Efficacy of pyriproxyfen for control of stored-product psocids (Psocoptera) on concrete surfaces

The insect growth regulator pyriproxyfen was evaluated as a surface treatment for control of three stored-product psocid pests Liposcelis bostrychophila Badonnel, Liposcelis decolor (Pearman), and Liposcelis paeta Pearman (Psocoptera: Liposcelididae). Nymphs were exposed for 35 d on a concrete surface treated with 2.3 mg of active ingredient/m2 pyriproxyfen. Exposure to pyriproxyfen significantly reduced the numbers of both adults and nymphs in comparison with untreated controls. In adults, the greatest reduction (> 90%) was for L. decolor and L. bostrychophila, whereas for L. paeta it was 49%. Few adults of any species were found in the pyriproxyfen treatments. The greatest numbers of nymphs were recorded for L. bostrychophila for both pyriproxyfen treatments and controls. Few adults of any species were found in the pyriproxyfen treatments. The results indicate that pyriproxyfen is effective for control of L. bostrychophila, L. decolor, and L. paeta on concrete, and although complete control was not achieved, the results warrant further long-term study to determine whether pyriproxyfen can completely eliminate psocid populations over time.     

Cardinium symbionts cause cytoplasmic incompatibility in spider mites

Intracellular symbiotic bacteria belonging to the Cytophaga-Flavobacterium-Bacteroides lineage have recently been described and are widely distributed in arthropod species. The newly discovered bacteria, named Cardinium sp, cause the expression of various reproductive alterations in their arthropod hosts, including cytoplasmic incompatibility (CI), induction of parthenogenesis and feminization of genetic males. We detected 16S ribosomal DNA sequences similar to those of Cardinium from seven populations of five spider mite species, suggesting a broad distribution of infection of Cardinium in spider mites. To clarify the effect of Cardinium on the reproductive traits of the infected spider mites, infected mites were crossed with uninfected mites for each population. In one of the populations, Eotetranychus suginamensis, CI was induced when infected males were crossed with uninfected females. The other six populations of four species showed no reproductive abnormalities in the F(1) generation, but the possibility of CI effects in the F(2) generation remains to be tested. One species of spider mite, Tetranychus pueraricola, harbored both Cardinium and Wolbachia, but these symbionts seemed to have no effect on the reproduction of the host, even when the host was infected independently with each symbiont.     

Population biology of cytoplasmic incompatibility: maintenance and spread of Cardinium symbionts in a parasitic wasp

Bacteria that cause cytoplasmic incompatibility (CI) are perhaps the most widespread parasites of arthropods. CI symbionts cause reproductive failure when infected males mate with females that are either uninfected or infected with a different, incompatible strain. Until recently, CI was known to be caused only by the alpha-proteobacterium Wolbachia. Here we present the first study of the population biology of Cardinium, a recently discovered symbiont in the Bacteroidetes that causes CI in the parasitic wasp Encarsia pergandiella (Hymenoptera: Aphelinidae). Cardinium occurs at high frequency ( approximately 92%) in the field. Using wasps that were recently collected in the field, we measured parameters that are crucial for understanding how CI spreads and is maintained in its host. CI Cardinium exhibits near-perfect rates of maternal transmission, causes a strong reduction in viable offspring in incompatible crosses, and induces a high fecundity cost, with infected females producing 18% fewer offspring in the first 4 days of reproduction. We found no evidence for paternal transmission or horizontal transmission of CI Cardinium through parasitism of an infected conspecific. No evidence for cryptic parthenogenesis in infected females was found, nor was sex allocation influenced by infection. We incorporated our laboratory estimates into a model of CI dynamics. The model predicts a high stable equilibrium, similar to what we observed in the field. Interestingly, our model also predicts a high threshold frequency of CI invasion (20% for males and 24% for females), below which the infection is expected to be lost. We consider how this threshold may be overcome, focusing in particular on the sensitivity of CI models to fecundity costs. Overall our results suggest that the factors governing the dynamics of CI Wolbachia and Cardinium are strikingly similar.     

反硝化除磷菌筛选及其特性研究

【目的】研究反硝化除磷菌特性。【方法】通过微生物筛选和生物学特性研究方法,从对虾养殖池塘中筛选出多株可在有氧条件下同时具有反硝化除磷功能的菌种。【结果】菌株LY-1可在18 h内将初始量为10 mg/L的亚硝酸盐氮降低至0.04 mg/L,PO43?-P降低至0.05 mg/L。在DO浓度为5.0?5.9 mg/L时,该菌反硝化除磷率近100%。试验选取具有反硝化除磷功能的枯草芽孢杆菌为阳性对照菌,大肠杆菌为阴性对照菌,比较研究了菌株LY-1在不同pH、温度、盐度、PO43?-P浓度、亚硝酸盐浓度时反硝化除磷的强弱,在pH为5?9范围时,该菌亚硝酸盐氮去除率近99%,PO43?-P去除率86%;温度为30°C时,该菌反硝化除磷率近100%;盐度为5‰?15‰、PO43?-P浓度为10 mg/L、亚硝酸盐氮浓度为20 mg/L时,该菌亚硝酸盐氮和PO43?-P去除率均可达99%。【结论】菌株LY-1反硝化除磷性能显著高于对照菌(P<0.05)。通过菌株LY-1形态学观察、生理生化及16S rRNA基因序列分析,初步鉴定为蜡样芽孢杆菌(Bacillus cereus)。     

海南地区螺旋粉虱三类次级内共生菌的检测

螺旋粉虱Aleurodicus dispersus Russell是一种重要的农林害虫。本研究分别利用次级内共生菌Cardinium和Arsenophonus的16S rDNA和Wolbachia wsp基因对海南省16地区的螺旋粉虱的3种次级内共生菌Cardinium, Arsenophonus和Wolbachia感染情况及相关基因序列进行了测定和分析。3种次级内共生菌Cardinium, Arsenophonus和Wolbachia检测结果表明, Cardinium和Arsenophonus均可感染海南地区的螺旋粉虱, 其中乐东、 陵水和澄迈3个地区所有寄主上的螺旋粉虱的Arsenophonus感染率为100%, 三亚、 琼中和临高部分寄主上的螺旋粉虱的Arsenophonus感染率为66.7%, 而儋州、 五指山和万宁3个地区的螺旋粉虱未发现被Arsenophonus感染; 三亚的番石榴上的螺旋粉虱的Cardinium感染率为100%, 琼海白沙的印度紫檀上螺旋粉虱的Cardinium感染率为100%, 其他寄主上的感染率均小于66.7%; 在所检测的43个螺旋粉虱种群中, 40和31个种群中分别检测出有Arsenophonus 和Cardinium感染, 种群感染率分别为93.0%和72.1%; 在所有检测的个体中, 120个个体中有105个感染Arsenophonus, 93个个体中有70个感染Cardinium, 个体感染率分别为87.5% 和75.3%; 在检测的所有样本中, 只有三亚印度紫檀上的螺旋粉虱检测到Wolbachia, 种群感染率为2.3%, 个体感染率仅为0.8%。这些检测结果表明, 海南地区螺旋粉虱次级内共生菌Arsenophonus的感染率高于Cardinium的感染率, Wolbachia的感染率极低。序列分析表明, 海南不同螺旋粉虱种群的Cardinium的16S rDNA序列一致, 而且与烟粉虱的Cardinium 16S rDNA序列一致性很高, 为97.6%; 不同螺旋粉虱种群的Arsenophonus的16S rDNA序列也完全一致, 其与西班牙加那利群岛螺旋粉虱的Arsenophonus的16S rDNA序列一致性较高, 为85.1%。此外, Wolbachia wsp基因序列分析表明, 海南螺旋粉虱的Wolbachia为B组, 这是国内螺旋粉虱感染Wolbachia的首次报道。     

一株海洋好氧反硝化细菌的鉴定及其好氧反硝化特性

【目的】从处理海洋养殖循环水的生物滤器生物膜中分离到1株具有好氧反硝化活性的细菌(菌株2-8),并进一步研究了该菌的分类地位及反硝化特性。【方法】采用16S rRNA基因序列分析对菌株进行初步鉴定,采用好氧培养技术,探讨了碳源种类、起始pH、NaCl浓度、C/N、温度和摇床转速对菌株2-8好氧反硝化活性的影响。【结果】该菌株的16S rRNA基因序列与Pseudomonas segetis FR1439T(AY770691)的相似性最高,达到99.9%,因此初步鉴定菌株2-8属于假单胞菌属(Pseudomonas sp.2-8)。碳源类型和C/N对其好氧反硝化作用的影响最为显著,以柠檬酸钠为唯一碳源,C/N为15时脱氮效率最高,低C/N导致亚硝酸盐的积累;其好氧反硝化的最适温度和pH分别为30℃和7.5;菌株2-8在摇床转速为160r/min下脱氮效果最好;NaCl浓度对其反硝化活性的影响不明显。【结论】在初始硝酸氮浓度为140mg/L,以柠檬酸钠为唯一碳源、C/N为15、pH为7.5、NaCl浓度为30g/L,30℃以及160r/min摇床培养的条件下,菌株2-8在48h内脱氮率可达92%且无亚硝酸盐积累。     

黄颡鱼卵水霉病病原的分离鉴定及其无性繁殖特性

【目的】对黄颡鱼卵水霉病病原进行分离鉴定,并对其无性繁殖特性进行研究。【方法】采用传统方法从患水霉病的黄颡鱼卵上进行丝状真菌的分离,然后通过人工感染实验证实分离菌株的致病性,通过形态学观察和ITS rDNA序列分析对致病菌株进行鉴定,并进一步通过单因子法研究其无性繁殖特性。【结果】从患水霉病的黄颡鱼卵上分离了4株丝状真菌,经人工感染试验证实其中一株丝状真菌HP对黄颡鱼卵具有致病性,并进一步研究了其形态与无性繁殖特性,开展了ITS rDNA序列分析。实验结果表明,菌株HP菌丝为透明管状结构,中间无横隔,分枝较少;游动孢子囊多数呈棒状,游动孢子发育成熟后从孢子囊中释放出来,并迅速游离;能够产生第二孢孢子;新孢子囊以内层出的方式产生;藏卵器呈球形,与雄器同枝或异枝。菌株HP的ITS rDNA序列与GenBank基因库中水霉属菌株自然聚类,同源性高达99%,与多子水霉菌株Arg4S(GenBank登录号GQ119935)的亲缘关系最近。结合形态特征与ITS序列鉴定的结果,判定菌株HP为多子水霉(Saprolegnia ferax)。此外,菌株HP在5°C-35°C、pH 4-10范围内均能产生游动孢子,产生游动孢子的最适温度和pH分别为20°C和7,而且5-25 mg/L福尔马林和0.25 1.25 mg/L二硫氰基甲烷对菌株HP产生游动孢子具有明显的抑制作用。【结论】分离鉴定了黄颡鱼卵水霉病病原,并确定了其无性繁殖特性,可以作为该病防治用药的依据。     

一株红假单胞菌的分离及对Cu2+的去除

【背景】重金属污染对环境和人类的健康构成了重大威胁,因此,重金属污染的治理迫在眉睫。生物治理因成本低、处理效果好和无二次污染等优点,在处理重金属污染时被优先选择。【目的】从辽河入海口深13 m的水体中,利用紫色非硫细菌富集培养基筛选产色素能力强并对高浓度Cu~(2+)有高效去除能力的菌株。【方法】采用形态学、生理生化特性和分子生物学方法鉴定菌种;采用二乙基二硫代氨基甲酸钠分光光度法测定Cu~(2+)的含量。【结果】鉴定菌株为红假单胞菌属,将其命名为Rhodopseudomonas sp. gh32。菌株gh32的最适生长温度和最适pH分别为30°C和7.0,其在pH 5.0-10.0范围内可正常生长,在3 mmol/L的CuSO4溶液中能够正常生长,能利用葡萄糖、甘露糖和果糖等单糖和硫化氢。菌株gh32在24h内对Cu~(2+)的去除率均在99%以上,处理能力为1 331 g/g干菌重或167.6 g/g湿菌重。【结论】菌株gh32对Cu~(2+)具有较强的耐受性和很好的去除效果,是治理含Cu~(2+)废水的潜力菌株。本研究为生物治理重金属废水提供了支持。     

玉米茎基腐病生防菌的筛选及应用

【目的】拟针对禾谷镰孢进行生防菌的筛选和应用研究,以期为玉米茎基腐病生防菌剂的研制奠定基础。【方法】通过对峙培养法对玉米茎基腐病的主要致病菌禾谷镰孢进行玉米内生生防细菌的筛选,从玉米主栽品种九单48幼苗内部获得一株具有较强抑菌效果的内生生防细菌(简称48SJ7-1);基于传统鉴定、16S rRNA基因序列测定及系统发育分析,对48SJ7-1进行鉴定;并通过盆栽试验测定该生防菌株的防效。【结果】菌株48SJ7-1经鉴定为甲基营养型芽孢杆菌,GenBank登录号为KU377993,48SJ7-1盆栽防效为68.47%,与对照药剂2%戊唑醇悬浮种衣剂差异不显著。【结论】48SJ7-1对玉米茎基腐病的主要致病菌禾谷镰孢有较好防效,对玉米生长还有明显的促进作用,而且表观上无药害发生。     

转几丁质酶和葡聚糖酶基因水稻对土壤三种弹尾目昆虫和一种环节动物的影响

采用 3个试验研究转几丁质酶和苜蓿 1,3- β -葡聚糖酶双价基因水稻对土壤弹尾目昆虫和环节动物线蚓的影响。①平皿实验 :观察弹尾目与转基因水稻组织间的营养关系及其在无土壤情况下对弹尾目昆虫繁殖率的短期影响 ;②土壤 -植物残留物单物种微宇宙试验 :观察土壤中不同转基因水稻组织含量对土壤动物繁殖率的短期影响 ;③土壤 -植物残留物多物种微宇宙试验 :模拟大田状况 ,观察多物种共存较长时间后转基因水稻对土壤动物密度的影响。结果表明 :Folsomiacandida取食新鲜转基因水稻叶片和根组织 2 1d后 ,繁殖率比野生型水稻组分别降低 4 5 1% (F1,8=9 9,P <0 0 5 )和 30 5 % (F1,8=5 8,P <0 0 5 ) ;在掺有转基因水稻组织 (30g/kg)的土壤中 ,F .candida 2 1d后的繁殖率比野生型水稻组下降 19 3% (F3 ,16=3 6 ,P <0 0 5 ) ;在掺有转基因水稻组织土壤 (30g/kg)的多物种实验中 ,转基因水稻组中的F .candida、Enchytraeuscrypticus16周后的密度比野生型水稻组分别降低 19 4 % (F1,48=6 8,P <0 0 5 )和 38 0 % (F1,48=6 4 2 ,P <0 0 0 1) ,而Sinellacurviseta的密度升高 84 8% (F1,48=6 4 2 ,P <0 0 0 1)。因此 ,转几丁质酶和葡聚糖酶双价基因水稻对土壤弹尾目和线蚓都是有影响的 ,对某些种类表现     

Wolbachia和Cardinium对皮氏叶螨生殖的影响及在寄主体内的定位

Wolbachia和Cardinium均为母系遗传的胞内共生菌, 它们能够通过诱导胞质不亲和（cytoplasmic incompatibility, CI）以调控寄主的生殖。目前, 关于Wolbachia和Cardinium共同对同一寄主进行生殖操控的机制还不清楚。本研究以皮氏叶螨Tetranychus piercei McGregor广州种群为实验材料, 通过杂交实验和荧光原位杂交的方法, 研究Wolbachia和Cardinium单感染和双感染对寄主生殖的影响。结果表明： 单感染Wolbachia诱导较弱的CI, 不亲和组合的未孵化率为17.8%±1.6%。单感染Cardinium及双感染Wolbachia和Cardinium能诱导高强度的CI, 不亲和组合的未孵化率分别为70.3%±1.3%和72.9%±1.2%。同时双感染Wolbachia和Cardinium雌螨的平均产卵量为35.2±1.2, 显著高于单感染和不感染的雌螨的产卵量。Wolbachia 和Cardinium分别诱导以及共同诱导CI的水平与精子形成过程中的感染情况有关。Wolbachia和Cardinium的垂直传播模式结果显示, 在卵的不同发育阶段, Wolbachia和Cardinium主要伴随着营养物质从滋养细胞、 中肠、 输卵管进入发育中的卵。研究结果为进一步了解 Wolbachia和Cardinium的母系遗传机制提供了重要依据。     

Purification of a pituitary receptor for somatostatin. The utility of biotinylated somatostatin analogs.

A somatostatin (SRIF) receptor and its associated Gi regulatory proteins was purified from GH4C1 rat pituitary cells by: 1) saturation of the membrane-bound receptor with biotinyl-NH-[Leu8,D-Trp22,Tyr25] SRIF28 (bio-S28); 2) solubilization of receptor-ligand (R.L) complex with deoxycholate-lysophosphatidylcholine (D.L); 3) adsorption of solubilized receptor-ligand complex to immobilized streptavidin; and 4) elution of receptor and G-protein by GTP. The receptor, a glycoprotein with an average M(r) of 85,000, was then purified to substantial homogeneity on immobilized wheat germ agglutinin. The 85-kDa glycoprotein was identified as a SRIF receptor by several criteria. (a) It had the same size as the chemically cross-linked R.[125I]L complex. (b) Yield of the purified protein increased and plateaued in the same range of bio-S28 concentrations where specific high affinity binding reached saturation. (c) It was copurified with appropriate G-protein subunits. The 85-kDa receptor and two other proteins with M(r) values of 35,000 and 40,000, the sizes of G beta and G alpha, did not appear in eluates from control streptavidin columns done with SRIF receptors loaded with nonbiotinylated S14. The 40-kDa protein was identified as a Gi alpha by ADP-ribosylation from [32P]NAD catalyzed by pertussis toxin. (d) Both the chemically cross-linked R.[125I]L complex and SRIF receptor purified from [35S]methionine-labeled GH4C1 cells were reduced in size to about 38 kDa by endoglycosidase F. (e) Amino acid sequence from the purified receptor was nearly identical with that of a recently cloned SRIF receptor subtype.     

嗜卷书虱抗气调品系的选育及其适合度研究

于恒温条件下以人工饲料饲养的嗜卷书虱Liposcelis bostrychophila,在35% CO₂和1% O₂组配的气调环境中以50%左右的选择压力处理,以选育其抗气调性。至30代获得抗性品系(CA-R),抗性倍数达5.6倍,且有继续增强的基因潜能。该抗性品系对气调的抗性不太稳定,在无选择压力的情况下经室内5代饲养,抗性衰退了63.2%。CA-R品系与敏感品系在无气调选择压力的条件下相比具有一定程度的繁殖不利性;但没有发现CA-R品系在生长发育特性上的不利性。以净增殖率来衡量,CA-R品系相对于敏感品系具有0.39的适合度。     

一株瘤胃源乳酸利用菌的分离鉴定及其体外代谢特性

【目的】从饲喂高精料的本地山羊瘤胃内分离到一株利用乳酸并能产生大量丙酸的菌株L9,并进一步研究了该菌在调控瘤胃微生物发酵中的作用。【方法】采用厌氧培养技术,结合形态、生理生化特性和16SrRNA基因序列分析结果。【结果】该菌株被鉴定为反刍兽新月形单胞菌（Selenomonas ruminantium）。该菌株体外代谢特性研究表明,L9可利用乳酸作为唯一碳源,该菌在24h内可对90mmol／L的乳酸完全降解。体外摸拟瘤胃急性酸中毒的发酵试验结果表明,以淀粉为底物时,与对照组相比,添加菌株L9可显著降低瘤胃微生物体外培养体系中乳酸浓度,提高pH值,提高总挥发性脂肪酸和丙酸浓度,并显著降低乙酸与丙酸的浓度比（P〈0．05）。【结论】结果显示,菌株L9是一株可代谢乳酸,促进丙酸生成,提高总挥发性脂肪酸浓度的有益瘤胃细菌。     

乙酸驱动条件下粪产碱杆菌Y5的碳氮共脱除特性

【目的】研究微生物的碳氮共脱除特性及其关键影响因素。【方法】以乙酸为唯一碳源分离获得的碳氮共脱除菌株Y5为模式菌株,分析菌株Y5的16S r RNA基因序列、碳源和氮源去除动力学,以及碳源种类、碳氮比(C/N)、溶解氧浓度(DO)、温度和p H等影响效果。【结果】菌株Y5归属于粪产碱杆菌。与葡萄糖及多种有机酸相比,菌株Y5在以乙酸为唯一碳源的条件下具有较高的TOC和NH4+-N去除速率。在好氧条件下,当起始TOC浓度为1 000 mg/L,氨氮浓度为110 mg/L时,菌株Y5的NH4+-N、TOC和总氮(TN)去除率分别达99.54%、92.95%和86.55%,最大NH4+-N、TOC和TN去除速率分别为903.58、505.81和406.03 mg/(L·d)。【结论】粪产碱杆菌Y5在以乙酸为唯一碳源的条件下具有较强的碳氮共脱除能力,其最佳反应条件为:C/N=10,p H 7.0-8.0,溶氧6.20 mg/L,反应温度为30°C。     

抗生素和肠道细菌对小菜蛾适合度的影响

【目的】小菜蛾是危害十字花科蔬菜的世界性重要害虫。通过分析抗生素对小菜蛾的毒性效应,了解肠道细菌对小菜蛾适合度的影响,有助于更好地阐明小菜蛾肠道细菌的功能。【方法】利用抗生素处理含有高丰度肠道细菌的萝卜苗饲养品系(FZss)小菜蛾幼虫,同时利用抗生素处理饲料饲养的无肠道细菌(SLss)小菜蛾幼虫,分析抗生素及肠道细菌对小菜蛾适合度的影响。【结果】抗生素处理FZss品系小菜蛾导致了小菜蛾发育历期延长,虫重、蛹重、化蛹率、产卵量和成虫寿命降低。利用抗生素处理无肠道菌的SLss品系小菜蛾幼虫,小菜蛾化蛹率和单雌产卵量均显著降低,而对发育历期、虫重和蛹重则无影响。【结论】综合两个研究的结果发现抗生素处理后宿主适合度的降低一方面是由于抗生素的毒性效应导致,另一方面是由于小菜蛾肠道细菌的缺失引起。抗生素的毒性效应主要表现为对化蛹率和单雌产卵量的影响,而肠道细菌则对小菜蛾的发育历期、虫重、蛹重以及成虫寿命具有重要的促进作用。     

Antagonistic interaction between male-killing and cytoplasmic incompatibility induced by Cardinium and Wolbachia in the whitefly,Bemisia tabaci

Cardinium and Wolbachia are maternally inherited bacterial symbionts of arthropods that can manipulate host reproduction by increasing the fitness of infected females.Here,we report that Cardinium and Wolbachia coinfection induced male-killing and cytoplasmic incompatibility(CI)when they coexisted in a cryptic species of whitefly,Bemisia tabaci Asia II7.Cardinium and Wolbachia symbionts were either singly or simul-taneously localized in the bacteriocytes placed in the abdomen of B.tabaci nymphs and adults.Cardinium-Wolbachia coinfection induced male-killing and resulted in a higher female sex ratio in the intraspecific amphigenetic progeny of Asia II7 IcwH and IcwL lines;interestingly,male-illing induction was enhanced with increased Cardinium titer.Moreover,single infection of Wolbachia induced partial CI in the Asia II7 Iw line and resulted in reduced fecundity,higher embryonic mortality,and lower female sex ratio.The uninfected Asia II7 Iu line had significantly higher fecundity,lower embryonic and nymphal mortalities,and a lower level of CI than both the Wolbachia infected Asia II7 Iw line and the Cardinium--Wolbachia-coinfected Asia II7 IcwH line.Our findings indicate that Cardinium-Wolbachia coinfection induced male-killing,which may have had antag-onistic effects on Wolbachia-induced CI in the Asia II7 whiteflies.For the first time,our study revealed that B.tabaci Asia II7 reproduction is co-manipulated by Cardinium and Wolbachia endosymbionts.     

Chondroitinase ABC digestion of dermatan sulphate. N.m.r. spectroscopic characterization of the oligo- and poly-saccharides.

Dermatan sulphates, in which iduronate was the predominant uronate constituent, were partially digested by chondroitinase ABC to produce oligosaccharides of the following structure: delta UA-[GalNAc(4SO3)-IdoA]mGalNAc(4SO3) [where m = 0-5, delta UA represents beta-D-gluco-4-enepyranosyluronate, IdoA represents alpha-L-iduronate and GalNAc(4SO3) represents 2-acetamido-2-deoxy-beta-D-galactose 4-O-sulphate], which were fractionated by gel-permeation chromatography and examined by 100 MHz 13C-n.m.r. and 400/500 MHz 1H-n.m.r. spectroscopy. Experimental conditions were established for the removal of non-reducing terminal unsaturated uronate residues by treatment with HgCL2, and reducing terminal N-acetylgalactosamine residues of the oligosaccharides were reduced with alkaline borohydride. These modifications were shown by 13C-n.m.r. spectroscopy to have proceeded to completion. Assignments of both 13C-n.m.r. and 1H-n.m.r. resonances are reported for the GalNAc(4SO3)-IdoA repeat sequence in the oligosaccharides as well as for the terminal residues resulting from enzyme digestion and subsequent modifications. A full analysis of a trisaccharide derived from dermatan sulphate led to the amendment of published 13C-n.m.r. chemical-shift assignments for the polymer.