Evidence of Two Formae Speciales in Venturia inaequalis, Responsible for Apple and Pyracantha Scab

ABSTRACT Genetic relationships, mating crosses, and host specificity of Venturia inaequalis isolates from Malus spp. and of Spilocaea pyracanthae isolates from Pyracantha spp. were evaluated. Sequence analysis of the complete internal transcribed spacer (ITS) region (ITS1-5.8S to ITS2) revealed a total similarity between these two putative species. ITS restriction fragment length polymorphism carried out with five restriction enzymes on a collection of 28 isolates confirmed a lack of diversity in this region between and within these two populations. Additional isolates from three related species (V. pirina, V. nashicola, and S. eriobotryae) were divided into two distinct monophyletic groups in a phylogenetic tree using ITS sequence comparison. These groups were related to their anamorph (i.e., Spilocaea or Fusicladium). When inoculated on their host of origin, fields isolates caused typical symptoms of scab disease, and a host specificity was demonstrated by cross pathogenicity of isolates from Malus x domestica and Pyracantha spp. Mating on dried leaves in vitro between one isolate of each putative species led to production of numerous perithecia. Ninety-six sporulating monoascosporic progenies were isolated from this cross. Based on these genetic and pathogenic data, we proposed that pathogens responsible for scab on Malus spp. and Pyracantha spp. are considered as two formae speciales belonging to V. inaequalis.     

Occurrence of antibodies to Neospora caninum and Toxoplasma gondii in dogs from Pernambuco, Northeast Brazil

A serological survey was carried out to assess the occurrence of anti-Neospora caninum antibodies in dogs from the State of Pernambuco. A total of 625 serum samples of dogs (289 from Paulista, 168 from Amaraji and 168 from Garanhuns) were tested by an immunofluorescence antibody assay for the detection of anti-N. caninum antibodies. A total of 177 (28.3%; IC 95%, 24.9-32.1) samples were positive. The seropositivity rates found in Paulista, Amaraji and Garanhuns were 26% (IC 95%, 21-31.4), 26.2% (IC 95%, 19.7-33.5) and 34.5% (IC 95%, 27.4-42.2), respectively. Of the 177 serum samples positive to anti-N. caninum antibodies, 170 were additionally tested for the presence of anti-Toxoplasma gondii antibodies and out of these 57.6% (IC 95%, 49.8-65.2) were positive. The results indicate that dogs from Amaraji, Paulista and Garanhuns are exposed to both N. caninum and T. gondii infections. The presence of dogs infected by N. caninum in Pernambuco represents a potential risk factor for the occurrence of outbreaks of abortion in cattle and small ruminants in this state. This study is the largest serological survey on the presence of anti-N. caninum antibodies in dogs carried out in Brazil and reports for the first time the exposure to N. caninum and T. gondii in dogs from Pernambuco.     

Rotifer community structure in fish‐farming systems associated with a Neotropical semiarid reservoir in north‐eastern Brazil

The study was conducted to assess the community structure of planktonic rotifers and their relation to the environmental impact of Nile tilapia, Oreochromis niloticus (Linaeus, 1758), aquaculture activities (ponds and net‐tanks), associated with a Neotropical semiarid reservoir in Brazil. Our hypothesis was that the ecological attributes of the rotifer community were different when considering the influence of fish aquaculture activities. We identified 28 species, with 10 species from the Brachionidae family. The average density and diversity index of rotifers were higher in reservoir stations, with mean values in the ponds approximately 50% lower than those of the reservoir. The microphagous species dominated during all the time, while the raptorial species were accidental in all studied environments. The ponds were represented by four significant indicator species: Brachionus caudatus, B. leydigi, Dicranophoroides caudatus and Testudinella patina and the reservoir by three: B. falcatus, B. havanaensis and Conochilus dossuarius. In general, nine species were significantly associated with some categories of environmental conditions, such as high or low turbidity and low values of conductivity and TDS. Four of the five best bioindicator species belonged to the microphagous genus Brachionus. B. havanaensis indicated five environmental conditions (IndVal > 93.1%), and it appeared to be a key species in this Neotropical semiarid reservoir influenced by aquaculture activities. The dominance of microphagous rotifers suggests a functional redundancy of species in the studied environments. We found that these systems and their management affected the planktonic rotifer community in this region of Brazil by increasing the species richness.     

Evaluation of the Influence of Natural and Antrhopogenic Processes on Water Quality in Karstic Region

This paper presents a comprehensive study on the quality of surface and groundwater in an environmentally sensitive karstic watershed strongly pressed by urban growth. The objective of the study was to assess the integrated effects of human activities and natural characteristics of karstic environments on the quality of surface and groundwater using multivariate statistical techniques. Data from 18 physical, chemical, and microbiological water quality variables obtained throughout a hydrological year were analyzed using principal components analysis (PCA) and cluster analysis. The PCA was carried out individually for surface water and groundwater. Our goal was to study the behavior of the water quality variables at each of these systems, as well as to infer the importance of these variables on the dynamics of the water resources in the region. Our results for surface water showed that the 18 original variables could be reduced to five principal components which together accounted for 69% of the total variation in the data, whereas for groundwater, 70% of the total variation in the data was explained by five principal components. In order to evaluate the impacts of anthropic activities on the water quality at the monitoring locations, the cluster analysis was applied to the ten sampling points. The analysis identified five clusters, two of which are formed by points with low contamination levels and three where the anthropic interference is noticeable. The results suggest the existence of specific contamination sources in many points, including in the groundwater, and highlight the natural vulnerability of the karstic environments.     

Design,optimization, and application of a conventional PCR assay with an internal control for detection of ‘Candidatus Mycoplasma turicensis’ 16S rDNA in domestic cats from Brazil

Background: ‘Candidatus Mycoplasma turicensis’ (CMtc) is a hemotrophic bacterial species that can, alone or in combination, induce anemia in cats. The diagnostic test of choice for hemoplasma infections is PCR. Conventional PCR assays have been developed for the detection of Mycoplasma haemofelis (Mhf) and ‘Candidatus M. haemominutum’ (CMhm) but not for CMtc. Although real‐time PCR assays have been reported for all of the feline hemoplasmas, the expense of necessary instrumentation precludes its use in Brazil and many other countries. Objectives: The goals of this study were to develop and optimize a conventional PCR assay to diagnose CMtc using an internal control to detect false‐negative results, and to evaluate the occurrence of CMtc infection in domestic cats from Brazil. Methods: Species‐specific primers were designed and a PCR assay was developed for the detection of CMtc 16S rDNA in cat blood. Sensitivity was determined by serial 10‐fold dilutions of plasmid and DNA extracted from blood from an experimentally infected cat. EDTA blood samples from 373 cats were collected. DNA was extracted using a silica‐based protocol and tested using the PCR assay. Results: Primer concentration, annealing temperature, and MgCl₂ concentration were optimized in the presence and absence of the internal control. Two samples negative for the internal control were excluded. Of the remaining 371 samples (117 healthy and 254 unhealthy cats), 17 (4.6%) were positive for CMtc. Conclusion: These results demonstrate the utility of an optimized PCR assay to detect CMtc in feline blood samples. We also report for the first time the prevalence of CMtc infection in domestic cats in Brazil.     

Shedding of Neospora caninum oocysts by dogs fed tissues from naturally infected water buffaloes (Bubalus bubalis) from Brazil

Attempts were made to isolate Neospora caninum from naturally infected water buffaloes (Bubalus bubalis) from Brazil. Brains from six buffaloes with indirect fluorescent antibodies (>1:100) to N. caninum were used to isolate the parasite by bioassay in dogs and gerbils followed by in vitro culture. Shedding of Neospora-like oocysts was noticed in dogs fed brains from three buffaloes (isolate designation NcBrBuf-1, 2 and 4). Two more isolates (NcBrBuf-3 and 5) were obtained by in vitro culture of the brains of gerbils previously infected with brains of two other buffaloes. The identity of the isolates was confirmed by biological and molecular methods. The isolates were found to be non-pathogenic to gerbils. All five isolates amplified the gene 5 amplicons using Neospora-specific PCR assay. The sequences of gene 5 fragments and the common toxoplasmatiid ITS-1 fragments were analyzed. The dynamics of oocyst production in the dogs indicate that water buffaloes are natural intermediate hosts for N. caninum. This is the first report of isolation of N. caninum from water buffaloes.     

Intraguild predation between an exotic and a native coccinellid in Argentina: the role of prey density

Journal of Pest Science - Harmonia axyridis Pallas is a generalist predator native to Asia. It has been released both for classical and neoclassical biological control programs worldwide. Its...     

Protective effect of oral administration of transgenic tobacco seeds against verocytotoxic Escherichia coli strain in piglets

The use of transgenic plants as delivery system for antigenic proteins is attractive for its simplicity and increases likelihood for local immune response at sites of infection. The aim of this study was to evaluate the protective effect of oral administration of tobacco seeds, expressing the FedA, the major protein of the F18 adhesive fimbriae, and B subunit of verocytotoxin, against verocytotoxin-producing E. coli (VTEC) strain in piglets. Forty-three early weaned piglets, were randomly divided into 4 experimental groups: 3 test groups and a control. Treatment groups orally received a bolus, with different dose of tobacco seeds on 0, 1, 2, 14 days post primary administration. After challenge, with 1*10¹⁰ CFU of O138 Escherichia coli strain, piglets showed clinical scores significantly higher in the control group compared to orally immunized groups (P?<?0.05) and the latter showed a faster recovery than in CG. In conclusion, oral administration of recombinant tobacco seeds expressing antigenic proteins against VTEC strains can induce a protective effect against challenger strain in piglets.