Interaction between macrophages of various origin and Toxoplasma gondii under conditions in vitro.

The study of proliferation of a virulent strain of Toxoplasma in cultures of macrophages of various origin revealed a certain sequence in the development of the pathogen: penetration and phagocytosis of the parasite, the stage of disintegration of one part of population and active proliferation of the other, resulting in the destruction of host cells. It was found that the penetration and phacocytosis were more active if macrophages from resistant animals (rats) were used, in comparison with those isolated from susceptible animals (white mice, guinea pigs). The activity of proliferation of a virulent strain of Toxoplasma also differs with the host cells: the toxoplasma multiply more rapidly in macrophages from susceptible animals than in those from resistant animals. The following changes of macrophages due to proliferation of the parasite were observed: change of form of the cell accompanied with the loss of cytoplasmatic processes, vacuolation of the cytoplasm, displacement of the nucleus towards the periphery followed by its pycnosis and rupture of the cell.     

Propagation of Toxoplasma gondii in suspension cultures of HeLa cells.

A novel method of Toxoplasma gondii cultivation in suspension cultures has been introduced using silicone-coated glass vessels (working volume 100 ml). The cells were kept in suspension by a magnetic impeller at 75 rpm at a temperature of 37 degrees C. HeLa cells grown on MEM with calf serum were used as host substrate. The HeLa cells were infected with zoites of Toxoplasma gondii virulent P strain. After seven days the host cells were destroyed by the toxoplasmas and the number of zoites was up to 24 x 10(6)/ml.     

Prevalence of Toxoplasma gondii in small mammals from the Ardennes region, France

Serum samples from 218 small mammals trapped in forest and grassland in the Ardennes region (North-eastern France) were tested for antibodies to Toxoplasma gondii. Using the modified agglutination test, positive results were found in 4/92 Apodemus sp., 3/64 Clethrionomys glareolus, 0/26 Microtus agrestis, 0/4 Micromys minutus, 3/5 Sorex sp., 2/9 Arvicola terrestris, and 7/18 Talpa europaea. Toxoplasma gondii was not isolated from the heart of seropositive individuals after bioassay in mice. Seroprevalence was significantly higher in large fossorial mammals living in grassland than in small forest mammals, probably related to ecological factors.     

Serodiagnosis of Toxoplasma gondii in habitually aborting women and other adults from North Jordan

The prevalence of anti-Toxoplasma gondii antibodies in serum samples of 55 habitually aborting women, 46 women with normal pregnancies, 92 outpatient adults, and 150 University students from North Jordan was studied using the enzyme linked immunosorbent assay (ELISA). Sera from the habitually aborting group were also tested by the indirect immunofluorescent (IIF) test. No significant difference was found between the overall prevalence rates in University students, outpatient adults and women with normal pregnancies (25.3%, 22.8% and 26.1% respectively). The prevalence in habitually aborting women exceeded two times that in women with normal pregnancies or in outpatient females (58.2%, 26.1% and 25.0% respectively), and was approximately three times that in female University students (18.3%). The greatest difference in the prevalence rate between habitually aborting women and those with normal pregnancies or outpatient females was found in groups having the highest antibody level (greater than or equal to 100% of standard positive controls). A positive correlation between the results of the ELISA and those of the IIF test occurred at titres of greater than or equal to 1:40 of the latter test in habitually aborting women.     

茛力花的离体培养和快速繁殖

茛力花短缩茎作为外植体进行离体培养,成功建立了快繁技术体系。不同浓度激素对其增殖及根的形成有不同影响。各个阶段最适培养基：（1）增殖培养基为MS＋BA3．0mg／L＋NAA1．0mg／L,培养30d,增殖率稳定为4．65;（2）壮苗培养基为MS＋6-BA0．2mg／L＋IBA0．2mg／L;（3）生根培养基为1／2MS＋NAA4mg／L＋蔗糖20g/L时,生根率达95％。     

In vitro evaluation of the antagonistic properties of Trichoderma spp. against Pyrenochaeta lycopersici and Phomopsis sclerotioides1

In vitro evaluation of the antagonistic properties of Trichoderma spp. against Pyrenochaeta lycopersici and Phomopsis sclerotioides was carried out, using two different methods: the cellophane-agar plate method and the duaí culture method. With these methods, the direct interaction between pathogen and antagonist was demonstrated, showing very remarkable differences between the different isolates. Growth inhibition ranging from 20 to 100% was found. Proliferation in non-sterilized soil was investigated for the isolates showing the most interesting antagonistic properties. A Belgian isolate of Trichoderma hamatum was found to be able to proliferate very well in soil and to maintain a high population density during the whole experimental period.     

In vitro culture of Orobanche ramosa

Orobanche spp. (broomrapes) are holoparasites that subsist on the roots of many important crops and can considerably reduce yield. The control of Orobanche spp. includes physical, chemical and biological methods. Interactions between parasitic angiosperms and their hosts first occur at the level of parasite seed germination. The seeds of all Orobanchaceae germinate in soil under natural conditions only in response to specific chemical exudates from the host plant. This study describes the influence of different plant growth regulators and host plant root exudates on germination and development of calli from Orobanche seeds in vitro . The effect of indole-3-acetic acid, gibberellic acid and kinetin on the germination of Orobanche seeds varied with concentration. These plant growth regulators also affected the period of germination and the structure of calli and protrusions. An in vitro system for the collection of tobacco root exudates was established. Compounds released from the host roots of three different tobacco cultivars were found to provoke high levels of germination of the Orobanche seeds without any period of pre-conditioning. This study developed methods for the investigation of host–parasite interactions and the effect of germination stimulants in Orobanche spp.     

In vitro secretion of metabolic end-products by piscine haemoflagellates Cryptobia salmositica and C. bullocki (Kinetoplastida: Bodonidae) and the relationship of these products to the pH in the medium.

Pathogenic and nonpathogenic strains of Cryptobia salmositica Katz, 1951 and C. bullocki Strout, 1965 produced hydrogen peroxide, pyruvate and lactate under in vitro conditions in Minimum Essential Medium (MEM). As parasite number increased, the phenol red in the medium changed from red to yellow. This change was not associated with a decrease in pH, or an increase in pyruvate or lactate, but was correlated with an increased secretion of hydrogen peroxide. Parasites incubated at 10 degrees C in medium at pH 6.0, 6.5, 7.0 and 7.3 were active for about I week with decreasing activity in the absence of serum. Parasites in saline (pH 6.0, 6.5, 7.0 and 7.3) were nonmotile within 24 h and were dead in about 1 week. This suggests that these Cryptobia spp. are sensitive to changes in pH and require medium which is buffered, either with serum or Hepes.     

“双玫瑰”萱草的离体培养和快速繁殖

“双玫瑰”萱草茎尖作为外植体进行离体培养,成功建立了“双玫瑰”萱草组培快繁技术体系。结果表明,不同浓度激素对其诱导、增殖及根的形成有不同影响。各个阶段最适培养基：（1）分化培养基为MS＋6-BA2．0mg／L＋NAA0．1mg,／L,培养25d左右,可诱导出不定芽,平均每株产芽6个,分化频率为100％;（2）壮苗培养基为MS＋6-BA0．2mg／L＋IBA0．02;（3）生根培养基为I／2MS＋NAA0．4mg／L,生根率达100％。     

In vitro analysis of host plant specificity in Rhizoctonia solani

Rhizoctonia solani is a plant pathogenic fungus with a wide host range. Host plant specificity within R. solani was analysed on seedlings grown aseptically on agar, which allowed continuous observation of both the fungus and the whole plant without disturbing the interaction. Symptom development on cauliflower, Arabidopsis , eggplant, tomato and potato by 32 R. solani isolates, belonging to six different anastomosis groups (AGs), was studied. Host plant specificity of isolates, as analysed by similarity clustering, was similar to AG-related host plant specificity as observed in the field, with AG3 isolates (except two avirulent strains) separating from the other isolates. Two R. solani isolates with a reciprocal pathogenicity on cauliflower and tomato were selected for further studies. These showed that in the pathogenic combination, R. solani isolates grew over the plant, adhered and formed infection structures, while in the nonpathogenic combination isolates grew over the plant, but neither adhesion nor the formation of infection structures occurred. From these data, it was concluded that host plant specificity is mediated in the early steps of the infection process.     

In vitro production of pycnidia by Septoria tritici

The in vitro production of pycnidia bySeptoria tritici was examined on six media reported to induce the formation of fruiting bodies. Among 26 freshly isolated cultures from various parts of the world, consistent differences in growth type were found which were only partially influenced by nutritional and environmental conditions. Cultures with yeast-like growth produced hardly any pycnidia or pseudopycnidia, while cultures with intermediate or mycelial growth types produced them frequently. Incubation in continuous darkness induced intermediate to mycelial growth types rather than yeast-like growth types in some cultures, and concomitantly the production of more pycnidia. Potato-dextrose agar induced intermediate to mycelial growth types and production of (pseudo)pycnidia more often than V8 agar and wheat leaf extract agar, which had previously been reported to be especially beneficial to (pseudo) pycnidium formation byS. tritici. Isolates with a consistently yeast-like growth type, producing (virtually) no fructifications under any of the experimental conditions, were slightly stimulated to form pseudopycnidia on water agar supplemented with sterile pieces of maize, wheat or carnation leaves.     

In vitro metabolism of etrimfos by house flies

The metabolism of etrimfos, O,O-dimethyl-O-(6-ethoxy-2-ethyl-4-pyrimidinyl) phosphorothioate was studied in vitro in a diazinon-resistant (Rutgers) and a susceptible (CSMA) strain of house flies. Practically no metabolism of etrimfos occurred without the addition of cofactors. However, the addition of the cofactor, reduced glutathione, resulted in a substantial amount of metabolism in both strains, the metabolism being higher in the resistant strain. The major route of metabolism was via the glutathione transferase system and the predominant metabolite was desmethyl etrimfos. Although the oxygen analog could not be isolated, microsomal oxidation of etrimfos resulted in the inhibition of acetylcholinesterase, suggesting the formation of the oxygen analog. Bovine serum albumin also degraded etrimfos yielding desmethyl etrimfos and 6-ethoxy-2-ethyl-4-hydroxypyrimidine.     

In vitro activity of isothiocyanates against Fusarium graminearum

Isothiocyanates are biotoxic degradation products formed as a result of enzymatic hydrolysis of glucosinolates present in Brassica species. The application of biofumigant Brassica crops, as an alternative crop protection method for soilborne pathogens and pests is increasingly gaining interest. However, little is known of the potential of biofumigation to reduce the inoculum of Fusarium species affecting cereals. The aim of this study was to evaluate the antifungal activity of five isothiocyanates, namely allyl, benzyl, ethyl, 2-phenylethyl and methyl isothiocyanates, against germination and growth of Fusarium graminearum under in vitro conditions. Aromatic isothiocyanates were more inhibitory than the aliphatic isothiocyanates against mycelial growth, whereas the reverse was observed for conidial germination. Among the tested isothiocyanates, allyl and methyl isothiocyanates were more efficient overall, showing lower ED₅₀ values (35–150 mg/L) for conidial germination and mycelial radial growth. The findings suggest that Brassica plants containing allyl and methyl glucosinolates could have a suppressive effect, reducing the inoculum of F. graminearum in soil prior to cereal production.     

In vitro expression of variation of glyphosate tolerance in Sorghum halepense

The in vitro response of five different Sorghum halepense biotypes against the non-selective, broad-spectrum herbicide glyphosate was assessed. Seeds from donor plants (collected in various sites all over Greece) were aseptically germinated on a hormone-free liquid Murashige and Skoog (MS) medium and emerging plantlets were inoculated on a solid MS medium supplemented with 13.6 μM 2.4-dichlorophenoxyacetic acid and 4.6 μM kinetin for callus induction. Exponentially growing calli were initially subcultured twice on induction medium and then transferred to a selection medium containing 10⁻³ M or 10⁻⁴ M (a.i.) glyphosate. The fresh weight of the cultured calli and the callus viability (expressed as callus dehydrogenase activity) were reduced as glyphosate concentration increased. Significant differences were observed among different biotypes. Regenerated plantlets were submitted to a conventional evaluation for glyphosate tolerance. The observed in vitro response of S. halepense to glyphosate was directly related to the in vivo herbicide tolerance observed both on donor and on regenerant plants.     

dsRNA分解酶PAC 1对4种植物病毒、3种类病毒dsRNA的降解活性检测及转pac 1基因烟草的获得

 将来自粟酒裂殖酵母的pac 1基因,导入原核表达载体pET-5a中,并转入大肠杆菌BL21(DE3)pLysS,经IPTG诱导,其表达产物能够降解4种植物病毒Cucumber mosaic virus(CMV)、Tobacco mosaic virus(TMV)、Rice black-streaked dwarf(RBSDV)和Rice dwarf virus(RDV)和3种类病毒Apple scar skin viroid(ASSVd)、Coleus blumei viroid(CBVd)和Hopstunt viroid(HSVd)的dsRNA。将pac 1导入双元载体pBI121,并转入根癌农杆菌LBA4404,以烟草(品种NC89)组培苗的叶片为受体材料进行转化,经过诱导愈伤、分化、再生和筛选培养,获得了50株Kan抗性植株,收获T₁种子分别播种,对这些转基因植株进行分子生物学检测。PCR、PCR-Southern和RT-PCR检测结果表明,pac 1基因已整合到受体基因组中。     

黄瓜褐斑病防治药剂的离体活性筛选

离体条件下针对黄瓜褐斑病菌对19种杀菌剂进行了活性筛选。结果表明,不同杀菌剂对褐斑病菌菌丝生长和孢子萌发抑制作用不同。对褐斑病菌菌丝生长具有强烈抑制作用的杀菌剂为苯醚甲环唑、咪鲜胺、代森锰锌及嘧霉胺,其EC50分别4.21、4.67、5.59 μg/mL及4.11 μg/mL。甲氧基丙烯酸酯类杀菌剂及防治卵菌病害的药剂对褐斑病菌菌丝生长几乎没有影响。烯肟菌酯、福美双、代森锰锌、烯酰吗啉、百菌清和多菌灵对褐斑病菌孢子萌发具有强烈抑制作用,其EC50分别为3.34、6.62、0.28、3.54、0.53 μg/mL及0.26 μg/mL。50 μg/mL的嘧霉胺虽对孢子萌发抑制作用较小,但10 μg/mL时即可导致萌发的芽管出现明显卷曲、畸形。     

Studies on the chiral isomers of fonofos and fonofos oxon: II. In vitro metabolism

The in vitro metabolism of the chiral isomers of fonofos and fonofos oxon in the presence of mouse liver mixed-function oxidase and serum esterase was investigated. The metabolism of ³⁵S-labeled phenyl-(S)_P-fonofos mediated by mixed-function oxidase took place stereoselectively, resulting predominantly in (R)_P-fonofos oxon. Similarly, (R)_P-fonofos was converted to (S)_P-oxon. In each case, however, a significant amount of racemization occurred. Other products were diphenyl disulfide and diphenyl disulfide oxide. In addition to stereospecificity, the oxidative metabolism of (R)_P-fonofos proceeded at a rate faster than that of (S)_P-fonofos. Stereoselective rate differences also were observed in mouse or rat serum-catalzyed degradation of the fonofos oxon enantiomers, the (S)_P isomer being degraded about twofold faster than its enantiomer. The differences in toxicities of the isomers of fonofos and fonofos oxon were consistent with the in vitro metabolism data.