trans-Dominant Inhibition of Geminiviral DNA Replication by Bean Golden Mosaic Geminivirus rep Gene Mutants     

Hanson SF  Maxwell DP 《Phytopathology》1999,89(6):480-486

ABSTRACT Geminiviruses are a group of single-stranded DNA viruses that cause major losses on a number of important crops throughout the world. Bean golden mosaic virus (BGMV) is a typical bipartite, whitefly-transmitted geminivirus that causes a severe disease on beans (Phaseolus vulgaris) in the Western Hemisphere. The lack of natural resistance to geminiviruses has led to attempts to engineer resistance, particularly through the use of pathogen-derived resistance strategies. The rep gene contains several conserved domains including nucleoside triphosphate (NTP)-binding and DNA-nicking domains and is the only geminiviral gene necessary for replication. Previous analysis by our group and others has demonstrated that the NTP-binding and DNA-nicking domains are necessary for geminiviral DNA replication. The ability of the rep gene and rep gene mutants to interfere with geminiviral DNA replication, when expressed in trans, was examined using a transient assay in a tobacco suspension cell culture system. Wild-type (wt) and mutant rep genes were cloned into plasmids under the control of the cauliflower mosaic virus 35S promoter for in planta expression and coinoculated into tobacco cells with infectious clones of various geminiviruses. The wt rep gene from BGMV-GA was able to support replication of BGMV-GA DNA-B. Several different rep gene mutants, with function-abolishing mutations in the NTP-binding or DNA-nicking domains, were potent trans-dominant inhibitors of geminiviral DNA replication.  相似文献   

Sexual Recombination in Gibberella zeae     

Bowden RL  Leslie JF 《Phytopathology》1999,89(2):182-188

ABSTRACT We developed a method for inducing sexual outcrosses in the homothallic Ascomycete fungus Gibberella zeae (anamorph: Fusarium graminearum). Strains were marked with different nitrate nonutilizing (nit) mutations, and vegetative compatibility groups served as additional markers in some crosses. Strains with complementary nit mutations were cocultured on carrot agar plates. Ascospores from individual perithecia were plated on a minimal medium (MM) containing nitrate as the sole nitrogen source. Crosses between different nit mutants segregated in expected ratios (3:1 nit(-):nit(+)) from heterozygous perithecia. Analysis of vegetative compatibility groups of progeny of two crosses indicated two and three vegetative incompatibility (vic) genes segregating, respectively. For rapid testing of sexual recombination between nit mutants, perithecia were inverted over MM to deposit actively discharged ascospores. Development of proto-trophic wild-type colonies was taken as evidence of sexual recombination. Strains of G. zeae group 2 from Japan, Nepal, and South Africa, and from Indiana, Kansas, and Ohio in the United States were sexually interfertile. Four group 1 strains were not interfertile among themselves or with seven group 2 strains. Attempts to cross G. zeae with representatives of F. acuminatum, F. avenaceum, F. culmorum, F. crookwellense, F. oxysporum, and three mating populations of G. fujikuroi were not successful.  相似文献   

Seasonal dynamics of the free-living phase of Anocentor nitens at Pedro Leopoldo, Minas Gerais, Brazil     

Borges LM  Oliveira PR  Ribeiro MF 《Veterinary parasitology》1999,87(1):73-81

An understanding of seasonal dynamics in the free-living phase of the tropical horse tick, Anocentor nitens, is vital for effective control measures. This study examines seasonal changes in the oviposition and incubation periods, eclosion rates, reproductive success, and larval survival in the free-living phase during the period June 1995-July 1997. Ten engorged female ticks, placed individually in wire-gauze tubes, were exposed in a field of Brachiaria decumbens fortnightly each month, and monitored to measure the duration of the various reproductive parameters, and success. Larval abundance was estimated indirectly, through the percentage of females with viable progeny, and directly by using a flagging method. Duration of the free-living cycle ranged from 12.3 weeks (October and December) to 23.5 weeks (March). The cycle was prolonged in cold and dry months. Larval survival was longer from February to July, and reduced from August to February. Oviposition was recorded in all months, and the egg production index ranged from 26.7 to 47.1%. The eclosion rate ranged from 0.1 to 76.6% in different months. Monthly estimates of larval abundance in the pasture were similar for the two methods used, being higher in months with higher temperatures, relative humidity and rainfall.  相似文献   

Ultrastructural identification of small granule prolactin (PRL) cells in goat adenohypophysis by the colloidal-gold method     

Vásquez F  Gómez MA  Serrano J  Bernabé A 《Anatomia, histologia, embryologia》1999,28(5-6):315-318

We describe ultrastructural characteristics of PRL cells with small secretory granules, immunostained with ovine antiserum, in adult Murciano-Granadina milking goats during anoestrus, the last third of gestation and lactation. This cell subtype is considered to comprise a stable population that decreases numerically during gestation and lactation, and that may change during these stages to show large granules.  相似文献   

Vaccination of ostriches (Struthio camelus, Linnaeus, 1758) against Newcastle disease: evidence for vaccine compatibility and seroconversion after vaccinations using the hemagglutination inhibition and virus neutralization tests     

Bolte AL  Voelckel K  Kaleta EF 《DTW. Deutsche tier?rztliche Wochenschrift》1999,106(2):62-65

Newcastle disease (ND) remains to be the worldwide most important infectious disease of poultry. This epizootic is in Germany and many other countries a notifiable disease. Prophylactic vaccination is the major tool for the control of ND in poultry and other birds. Eighty-three ostriches (Struthio camelus) which were kept on farms in Germany were checked for the presence of NDV-specific antibodies. Some of these birds are said to be vaccinated against Newcastle disease. Only some of these ostriches contained antibodies which were measurable in haemagglutination inhibition and virus neutralisation tests. Twenty-three previously unvaccinated ostriches were vaccinated with commercially available vaccines. Both the LaSota live and inactivated oil emulsion vaccines were well tolerated following conjunctival or subcutaneous application, respectively. Neither local nor systemic side reactions were observed. After the vaccinations high antibody titres were detected in hemagglutination inhibition and virus neutralisation tests. A strong correlation between both established methods (r = 0.92; < 0.001) were noted.  相似文献   

Trichinella antigens: a review   总被引：13，自引：0，他引：13  

Dea-Ayuela MA  Bolas-Fernández F 《Veterinary research》1999,30(6):559-571

This paper presents a review of the Trichinella antigens within the context of species variation. As with other parasites, Trichinella antigens can be classified according to their localisation as surface, excretory/secretory (ES) and somatic components. Surface antigens are mainly constituents of the outer cuticle although secretions from inner parts of the body wall as well as from the oesophagus can temporarily accumulate in the surface. ES antigens come mainly from the excretory granules of the stichosome, whereas somatic constitutive antigens come from the internal parts of the worms. ES products are considered very important from an immunological point of view as they are easily targeted by the immune system, whereas parasite death is required for exposure of somatic products. Some of the antigenic components have been characterised chemically. Phosphorylcholine is an important hapten that modulates the immune responses in Trichinella infections. Glycoproteins are the major components of surface and excretory/secretory products. A 43-kDa glycoprotein has been regarded as a good candidate for diagnosis and vaccination purposes. Recently some glycans have received special attention either as relevant epitopes or as parasite evasion strategies.  相似文献   

Serological and biochemical follow-up in cattle naturally infected with Fasciola hepatica, and comparison with a climate model for predicting risks of fasciolosis     

Bossaert K  Lonneux JF  Godeau JM  Peeters J  Losson B 《Veterinary research》1999,30(6):615-628

Several biological parameters were measured in 31 heifers naturally infected with Fasciola hepatica during one grazing season in the Belgian Ardennes. A forecast model based on daily temperature used to assess the risk of fasciolosis was fitted to this assay. Cattle were turned out to two pastures. Each pasture was divided into two plots: one was treated with calcium cyanamide and the other was left untreated. The Lymnaea truncatula snails were counted on three different occasions. The results indicated a poor molluscicide efficiency. Body weight gains, anti-Fasciola antibody levels, faecal egg counts, levels of sorbitol dehydrogenase (SDH) and gamma-glutamyl transferase (gamma GT), packed cell volumes, white blood cells and differential leucocyte counts were determined monthly. No statistically significant difference was observed between animals from the two plots regardless of the recorded data. No correlation was found between body weight gains and other biological data. The sampling date had a significant effect on the antibody responses within a same group, and on the enzymatic levels for all groups combined. The forecast results were consistent with the recorded data. Temperature was a major bioclimatic constraint on the transmission of life cycle, and risk of infection occurred mainly in late spring (May/June) and in early September. Current results might be used to issue advice on the need for flukicide treatment of cattle. The indicators of the infection considered alone were useless and it is concluded that herd diagnosis of fasciolosis may rely on the rise of specific antibody levels, possibly associated with an increase in hepatic enzyme activities.  相似文献   

The influence of dietary crude protein intake on bone and mineral metabolism in sheep     

Brand TS  Johnson Q  Franck F  Veith W  Conradie R  Hough FS 《Journal of the South African Veterinary Association》1999,70(1):9-13

Increased dietary protein consumption is thought to cause calciuresis, a negative calcium balance and increased bone loss that may result in skeletal deformities and fracture. To explore this hypothesis, 40 approximately 100-day-old meat-type Merino ram lambs were fed, for 6 months, diets with an increasing crude protein (CP) content (114, 142, 171 and 190 g/kg DM) but approximately on an iso-nutrient basis with regard to metabolisable energy, calcium and phosphorus. Increased protein consumption modestly (NS) enhanced calciuresis and resulted in significant (P < or = 0.01) limb skewness. This could not, however, be ascribed to osteopaenic bones, and compared with animals consuming lower protein rations, the bone mineral density (BMD) and vertebral trabecular bone volume of animals fed high protein diets were significantly increased: the BMD of thoracic vertebrae was positively related to the CP intake (r = 0.62; P < or = 0.001). In animals consuming higher protein diets, skeletal radiology and quantitative bone histology revealed no evidence of increased bone turnover as would be expected in animals that are in negative calcium balance. No relationship existed between limb skewness and the growth rate of lambs. However, the ratio of Ca:P in the forelimb (r = -0.98), vertebrae (r = -0.72) and rib (r = -0.42) was found to be inversely correlated with increased protein intake and resulted from an increase in the phosphorus content of bone, while the amount of bone calcium was unaffected. We conclude that qualitative micro-architectural abnormalities, and not mere bone loss, may underlie the skeletal deformities induced by increased protein consumption in sheep.  相似文献   

Observations on some cardiopulmonary effects of midazolam, xylazine and a midazolam/ketamine combination in the goat     

Stegmann GF 《Journal of the South African Veterinary Association》1999,70(3):122-126

Xylazine, midazolam and a midazolam/ketamine combination were administered to 6 goats in a randomised 3-way block design. All goats received all treatments with at least a 7-day interval between treatments. Statistically significant (P < 0.05) changes were observed in some of the measured cardiopulmonary variables for xylazine and midazolam/ ketamine. Xylazine administration resulted in statistically significant decreases in minute volume, arterial partial pressure of oxygen, heart rate and mean arterial blood pressure. The increase in arterial partial pressure of carbon dioxide was not statistically significant. For the midazolam/ketamine combination, the decrease in tidal volume was statistically significant, but not the decrease in minute volume and increase in arterial partial pressure of carbon dioxide. The decrease in the arterial partial pressure of oxygen was also statistically significant. The mean arterial blood pressure for the combination was statistically significantly higher compared to xylazine. The changes in cardiopulmonary variables after midazolam administration were not statistically significant, such as tidal and minute volume, arterial partial pressure of oxygen and carbon dioxide. However, clinically significant effects such as hypoventilation and hypoxia were observed after its administration. The change in mean arterial blood pressure was minimal.  相似文献   

Paul e. Nelson, 1927 to 1996     

Tammen JF  Toussoun TA  Horst RK  Burgess LW  Marasas WF 《Phytopathology》1999,89(12):1126

  相似文献