Effects of infection with a granulosis virus on larval growth, development and ecdysteroid production in the cabbage looper, Trichoplusia ni

ABSTRACT. Granulosis virus-infected Trichoplusia ni (Hûbner) larvae exhibited an increased larval life span with no supernumerary moult and no pupation. Weight gain was not affected. Insects infected shortly after hatching were slower in reaching the fourth and fifth stadia than were control insects. Haemolymph ecdysteroid titres were lower in virus-infected insects than control insects, but these differences were only significant ( P <0.05) in the fifth stadium. Electron microscopic examination of the pro thoracic glands revealed extensive granulosis virus infection, and glands from virus-infected insects produced no RIA-detectable ecdysteroids in vitro. Injection of 20-OII-ecdysone into virus-infected larvae at various concentrations and times did not induce pupation.     

Cauliflower mosaic virus gene VI causes growth suppression, development of necrotic spots and expression of defence-related genes in transgenic tobacco plants

Summary In order to study possible functions of the inclusion body matrix protein (IBMP) encoded by gene VI of cauliflower mosaic virus (CaMV), the XbaI fragment containing the gene VI of a Japanese strain of CaMV (CaMV S-Japan) was transferred to tobacco plants by Ti mediated transformation. Eight out of 18 kanamycin resistant plants (40%) expressed detectable levels of IBMP. Those transgenic plants expressing IBMP produced leaves with light green color, and their growth was suppressed as compared with control plants. Symptom-like necrotic spots also appeared on the leaves and stems of the mature transgenic plants. Furthermore, in these transgenic plants, pathogenesis-related proteins 1a, 1b and 1c were highly expressed and the activity of 1,3--glucanase was increased up to eightfold. From these results, we concluded that expression of the IBMP is associated with symptom development.     

Pulsed field gel electrophoresis and physical mapping of large DNA fragments in the Tm-2a region of chromosome 9 in tomato

Summary A method has been developed which allows the isolation of very high molecular weight DNA (>2 million bp) from leaf protoplasts of tomato (Lycopersicon esculentum). The DNA isolated in this manner was digested in agarose with rare-cutting restriction enzymes and separated by pulsed field gel electrophoresis. The size range of the reslting fragments was determined by hybridization to a number of single copy clones and the suitability of these enzymes for the mapping of large DNA fragments was evaluated. Furthermore, five genetically tightly linked single copy clones have been used to begin the construction of a physical map in a region of the genome containing the Tm-2a gene which confers resistance to tobacco mosaic virus. Two of the five clones were found to be on the same 560 kb SalI fragment and therefore are no further apart than that distance. The remaining three markers are distributed over at least 3 million bp, so that the total minimum physical distance of that cluster is at least 4 million bp. The results are discussed with respect to correlations between recombination frequencies and physical distance as well as physical mapping large regions of a complex plant genome like tomato.     

Sublethal effects of aldicarb on the behaviour of Aphis fabae and two clones of Myzus persicae and on the transmission of beet mosaic virus by these aphids

In laboratory experiments treatment of sugar-beet plants with aldicarb stimulated the mobility of Aphis fabae and two clones of Myzus persicae which were susceptible (S) and resistant (R) to carbamate-based insecticides, respectively. On the other hand, the number of aphids probing and the total number of probes made was reduced, and hence the transmission of beet mosaic virus (BMV) was restricted. In outdoor experiments the spread of BMV from aldicarb-treated plants by naturally infesting aphids was also restricted. The number of infected plants decreased with increasing distance from the sources of infection.

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Résumé Des plantes de betterave traitées au laboratoire avec de l'aldicarbe ont stimulé la mobilité d'Aphis fabae et de deux clones de Myzus persicae, l'un sensible et l'autre résistant à des insecticides contenant des carbamates. Par ailleurs, le nombre de pucerons en train de sonder les feuilles ainsi que le nombre total de sondages ont été réduits et ainsi la transmission du virus de la mosaïque de la betterave (BMV) a été limitée. Dans des expériences à l'extérieur, la vitesse de propagation de BMV par des pucerons sur des plantes traitées à l'aldicarbe a été aussi plus limitée. Le nombre de plantes contaminées diminuait avec la distance de la source de contamination.

     

Electrical recording and ultrastructure of stylet penetration by the greenhouse whitefly

Earlier studies have indicated that interior (physical and/or chemical) properties of a plant may be responsible for feeding-site selection by the greenhouse whitefly, Trialeurodes vaporariorum (Westw.). In order to study the process of feeding-site selection further, stylet-penetration activities and the pathway followed by the stylets in host-plant tissue were investigated using a DC electrical recording method and transmission electron microscopy (TEM). Penetrating whiteflies attached to a gold wire were included in an electrical circuit to record electrical penetration graphs (EPGs). Seven EPG patterns have been distinguished, five of which could be correlated with components of the stylet-penetration process: 1) one with penetration of the leaf surface, 2) one with intercellular penetration and salivary-sheath secretion, 3) one with sieve element penetration and ingestion, 4) one with short penetration of a cell, and 5) one with xylem penetration. The stylet pathway is almost completely intercellular before the phloem is reached and in contrast to aphids, brief symplast punctures are very rare. In general, it takes T. vaporariorum more than half an hour from the start of a penetration to reach a sieve element. Rejection of feeding sites occurs within a few minutes of penetration by adult whiteflies, a time span in which stylets are presumed to penetrate just beyond the epidermis. Properties of the apoplast close to the leaf surface seem therefore to play a major role in feeding-site selection.

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Résumé De précédentes études ont montré que les propriétés internes (physiques et/ou chimiques) d'une plante peuvent induire la sélection du site de nutrition de la mouche blanche de serres, Trialeurodes vaporariorum (Westw.). Afin d'étudier plus avant le processus de sélection du site de nutrition, les activités de piqûre et le chemin suivi par le stylet dans les tissus de la plante-hôte ont été étudiés par une méthode d'enregistrement électrique en courant continu ainsi que par microscopie à transmission d'électrons (TEM). Des aleurodes en activité de piqûre attachées à un fil d'or ont été incluses dans un circuit électrique pour enregistrer des graphes de pénétration électriques (EPG). Sept motifs d'EPG ont été distingués, dont cinq peuvent être corrélés aux composantes du processus de pénétration du stylet: 1) un avec pénétration de la surface foliaire, 2) un avec pénétration interecellulaire et sécrétion d'une gaine de salive, 3) un avec pénétration du phloème, 4) un avec courte pénétration d'une cellule, et 5) un avec pénétration du xylème. Le parcours du stylet est presque entièrement intercellulaire avant que le phloème soit atteint. Contrairement aux pucerons, les ponctions brèves dans le symplasme sont rares. Généralement, T. vaporariorum met plus d'une demi-heure, à partir du début d'une piqûre, pour atteindre un vaisseau. Le rejet des sites de nutrition par les aleurodes adultes se passe quelques minutes après la pénétration du stylet; pendant ce laps de temps, le stylet pénétrerait juste sous l'épiderme. Le rôle des propriétés de l'apoplaste près de la surface foliaire semble donc majeur dans la sélection des sites de nutrition.

     

Expression of herpes simplex virus glycoprotein D on antigen presenting cells infected with vaccinia recombinants and protective immunity

We studied the effect of the temporal regulation of herpes simplex virus (HSV) type 1 glycoprotein D (gD-1) expression in Ia⁺ epidermal cells (EC) and macrophages on virus specific immunity and protection from HSV-2 challenge. gD-1 was expressed on the surface of cells infected with a vaccinia recombinant containing gD-1 under the control of an early vaccinia virus promoter (VP176). It was not expressed in cells infected with a recombinant (VP254) in which gD-1 is controlled by a late vaccinia virus promoter. BALB/c mice immunized with both recombinants seroconverted to HSV-2 as determined by neutralization. However, HSV specific delayed type hypersensitivity (DTH) responses were significantly (p<0.025) higher in VP176 than VP254 immunized animals. Both VP176 and VP254 immunized mice were protected from severe neurological disease due to HSV-2 challenge at 14 days post immunization, but long term protection was observed only in VP176 immunized mice.     

A putative replicative form of the abutilon mosaic virus (gemini group) in a chromatin-like structure

Summary The putative replicative form of the abutilon mosaic virus (AbMV), a geminivirus, was purified from infected plants. It was shown to consist of a bipartite genome of 2660 and 2640 bp. This double-stranded DNA has a closed or relaxed circular conformation and part of it is packed in nucleoprotein complexes with a chromatin-like structure. Similarities between the geminiviruses and the animal simian virus 40 are discussed against this back-ground.Cloning was performed under L2/B1 conditions according to the licence of the ZKBS 1526/1This article is based on a doctoral study by A.A. and T.F. in the Faculty of Biology, University of Hamburg     

Purification and characterization of lymphocytic clonal growth factor (LCGF) derived from human-human hybridoma SH-76 cells

Human-human hybridoma SH-76 cells were found to produce a factor that supported the growth of lymphocytic cells at low densities. The factor was purified from serum-free conditioned medium of the hybridoma cells by a successive application of ammonium sulfate precipitation, DEAE-Toyopearl, TSK G3000 SW and DEAE-5PW column chromatograph. The purified factor was a 72K single protein. The factor showed marked growth stimulating effect on lymphocytic cell lines, but had no effect on the growth of human adhesive cancer cell lines. Thus, the factor is a lymphocytic clonal growth factor (LCGF), as found previously in human plasma (Miyata, 1988). The LCGF of SH-76 cells could be produced in growth factor-free RPMI medium and purified easily from the conditioned medium. The factor is inactivated by heating at over 80°C, but is much more stable than the LCGF in human plasma.     

应用蛋白印迹法检测鼻咽癌病人血清中抗Epstein—Barr病毒IgA/EA抗体

曾毅等建立了一系列检测EB病毒IgA/VCA和IgA/EA抗体的鼻咽癌早期诊断方法,取得了满意的结果。为了进一步提高对鼻咽癌诊断更为特异的IgA/EA抗体的检出率,我们建立了检测EB病毒IgA/EA抗体的蛋白印迹法。方法敏感特异,结果令人满意。 本法中所用的两个质粒系由本实验室与西德Pettenkofer研究所Wolf教授的实验室合作构建。pUCARG1140和pUC9MBcE3.2质粒均为表达质粒,前者携带着来源于EB病毒Bam     

纸坊病病毒病因的研究

1985年4～10月与1986年6～8月,在贵州省沿河县的纸坊村和崔家坨村先后发生了病因不明的传染病。纸坊村约有1/5的村民发病,病死率为12％,崔家坨村有1/10的村民发病,病死率高达30％。发病波及各年龄组,以青壮年为多,有家庭集聚现象。 本病起病急,轻症者只有头晕、乏力、肌痛、多汗、心悸伴以低热,有的初期有短暂的腹泻。重症者有高热(40℃以上)、大汗、心悸、游走性肌肉痉挛伴有明显疼痛和触痛,以腰骶部及四肢肌肉为好发部位。病人烦燥不安,2～5天内死亡。经实验室检查,排除了食物中毒、农药中毒、钩端螺旋体病和弓形体感染。从病人和接触者的粪便中分离到9株病毒,性状一致,为RNA型25nm的球形颗粒,耐酸,耐乙醚,能凝集人“O”型血球。经血清学鉴定为ECHO3型病毒。16份病人双份血清的检测结果表明,恢复期血清对该病毒中和抗体有4倍以上升高者共8例(纸坊村和崔家坨各4例)。病人单份血清也都有较高的抗体。有理由认为两年中先后在两个村庄发生的传染病与ECHO3型病毒有密切关系。查阅文献,尚未见有关ECHO3型病毒引起以肌痛、游走性肌痉挛为特征的疾病的报道。