Biometrical, biological, biochemical and molecular characteristics of Meloidogyne incognita isolates and related species

Meloidogyne incognita is one of the most polyphagous species of root-knot nematodes occurring in Brazil and worldwide. Eight M. incognita isolates were studied, representing two enzymatic phenotypes (esterase and malate desydrogenase: I1/N1, I2/N1) and four cryptic Meloidogyne sp.1 (S2/N1) isolates, representing one cytological type (3n?=?40–46). Three M. hispanica isolates (Hi3/N1, 2n?=?32–36) and two of an atypical Meloidogyne sp.2 (S2a/N3, 3n?=?40–44) were included in this study for comparison. All isolates were tested with three M. incognita-specific molecular markers. The primer pairs B06F/R, miF/R and incK14F/R amplified three species-specific fragments of 1,200?bp, 955?bp and 399?bp, respectively for M. incognita and Meloidogyne sp.1 isolates. No amplification occurred in the M. hispanica and Meloidogyne sp.2 isolates, except with primers miF/R (1,650?bp). The genetic variability of the Meloidogyne spp. isolates was evaluated, using RAPD and ISSR markers. The phylogenetic analyses revealed two strongly supported monophyletic clades: clade I, consisting of M. hispanica and the atypical Meloidogyne sp.2 isolates, and clade II, clustering together all M. incognita and the Meloidogyne sp.1 isolates. Considering the biometrical, cytological and molecular approaches, it was possible to conclude that the isolates with three enzymatic phenotypes (I1/N1, I2/N1 and S2/N1) presented the characteristics described for M. incognita. Some correlations were detected between the isozymatic phenotypes and the tree topology (S2a/N3, Hi3/N1, I1/N1, S2/N1), but no strict correlation could be observed for the phenotype I2/N1 and one isolate of S2/N1. Morphologically, the Msp.2 isolates differ from M. incognita and M. hispanica by the female stylet features presenting straight cone tip and round pear shaped knobs, posteriorly sloping. The results of this study suggested that the Msp.2 isolates with phenotypes S2aN3 belong to a new or an unidentified species closely related to M. hispanica.     

Humoral immune response to a recombinant hemoplasma antigen in experimental 'Candidatus Mycoplasma turicensis' infection

'Candidatus Mycoplasma turicensis' is a feline hemoplasma species that was isolated in a cat with hemolytic anemia. PCR has been widely used to investigate and diagnose 'Candidatus Mycoplasma turicensis' infection, but so far, little is known about the humoral immune response in infected cats. Recently, enzyme-linked immunosorbent assays (ELISA) were developed to monitor anti-feline hemoplasma antibodies. The aim of the present study was to investigate the humoral immune response in cats experimentally infected with 'Candidatus Mycoplasma turicensis' and to monitor the influence of the pre-administration of methylprednisolone and subsequent antibiotic treatment. Serum and plasma samples from 15 specified pathogen-free cats infected with 'Candidatus Mycoplasma turicensis' were analyzed by ELISA. Seroconversion was demonstrated in all cats, and the antibodies remained detectable until the end of the study (up to 100 weeks post-exposure). In some cats, the ELISA seemed more sensitive and better able to demonstrate exposure to 'Candidatus Mycoplasma turicensis' than PCR. The peak antibody level occurred after the peak of the bacterial blood loads. The methylprednisolone administrations were associated with increased antibody levels, while antibiotic treatment, particularly with doxycycline, resulted in a decrease in antibody levels. Additionally, preliminary data indicated that three of four seropositive cats were protected from bacteremia after a subsequent challenge. In conclusion, the ELISA was found to be a useful tool to investigate the humoral immune response in hemoplasma-infected cats and a desirable addition to PCR to study the pathogenesis of hemoplasma infections.     

Rubber tree early selection for yield stability in time and among locations

Rubber production in the rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell. Arg.] can be expressed differently in different environments. Thus the objective of the present study was to select productive progenies, stable and responsive in time and among locations. Thirty progenies were assessed by early yield tests at three ages and in three locations. A randomized block design was used with three replications and ten plants per plot, in 3 × 3 m spacing. The procedure of the mixed linear Reml/Blup model—restricted maximum likelihood/best non-biased linear prediction was used in the genetic statistical analyses. In all the individual analyses, the values observed for the progeny average heritability ( $ \hat{h}_{pa}^{2} $ ) were greater than those of the additive effect based on single individuals ( $ \hat{h}_{a}^{2} $ ) and within plot additive ( $ \hat{h}_{ad}^{2} $ ). In the joint analyses in time, there was genotype × test interaction in the three locations. When 20 % of the best progenies were selected the predicted genetic gains were: Colina G_G = 24.63 %, Selvíria G_G = 13.63 %, and Votuporanga G_G = 25.39 %. Two progenies were among the best in the analyses in the time and between locations. In the joint analysis among locations there was only genotype × location interaction in the first early test. In this test, selecting 20 %, the general predicted genetic gain was G_G = 25.10 %. Identifying progenies with high and stable yield over time and among locations contributes to the efficiency of the genetic breeding program. The relative performance of the progenies varies depending of the age of early selection test.     

Ribosomal RNA phylogeny of bacterial and fungal pathogens of Agriotes wireworms

Wireworms, the polyphagous larvae of click beetles belonging to the genus Agriotes (Coleoptera: Elateridae), are severe and widespread agricultural pests affecting numerous crops. Biological control agents and methods for this general pest are highly solicited. In a screening for microbial Agriotes pathogens, an intracellular bacterium and a mitosporic fungus were isolated. Phylogenetic analysis based on ribosomal RNA operon sequences of both micro-organisms corroborated their previous morphology-based taxonomic classification. The bacterial pathogen has been assigned to the taxonomic genus Rickettsiella (Gammaproteobacteria) wherein it represents a new pathotype, ‘Rickettsiella agriotidis’, that appears most closely related to subjective synonyms of the nomenclatural type species, Rickettsiella popillae. The fungal pathogen has been shown to belong to the form-species Beauveria bassiana, i.e., an obligate anamorph related to the genus Cordyceps (Ascomycota: Hypocreales). Furthermore, the B. bassiana strain from Agriotes has been shown to be potentially susceptible to identification by gIi-diagnosis, i.e., a diagnostic method making use of the strain-specific presence of self-splicing group-I introns within the ribosomal RNA operons of certain hyphomycetous fungi.     

Short-term spatiotemporal variation of soil CO2 emission,temperature, moisture and aeration in sugarcane field reform areas under the influence of precipitation events

Soil CO₂ emission (FCO₂) in agricultural areas results from the interaction of different factors such as climate and soil conditions. Our objective was to investigate the spatiotemporal variation of FCO₂, temperature (T_soil), moisture (M_soil) and air-filled pore space (AFPS), as well as their interactions, during the sugarcane field reform. The study was conducted on a 90 × 90 m sampling grid with 100 points at 10 m spacings. Ten assessments of FCO₂, T_soil and M_soil were carried out at each point over a 28-day period. The greatest mean values of FCO₂ (0.74 g m⁻² hr⁻¹) and M_soil (31.7%) were obtained on Julian day 276, 2013, being associated with precipitation events at the study site. Also, the smallest values of AFPS (19.17%) and T_soil (20.90°C) were observed on the same day. The spatial variability of FCO₂, T_soil, M_soil and AFPS was best described by an adjusted spherical model, although an exponential model better fitted some results. The spatial pattern of all soil attributes showed little temporal persistency, indicating a high complexity for FCO₂ during precipitation. Correlation maps assisted in identifying regions where M_soil and AFPS better controlled the emission process and where T_soil was important. A major challenge for world agriculture is to increase the efficiency of conventional soil management practices. We highlight the importance of the spatial pattern of soil properties that directly influence the CO₂ emission dynamics. Future mitigation actions should involve less intense tillage and ensure homogeneous applications of soil inputs, thereby reducing production costs and the contribution of these activities to CO₂ emissions during the sugarcane field reform.     

Dietary roughage sources affect lactating Holstein x Zebu cows under experimental conditions in Brazil: a meta-analysis

Tropical Animal Health and Production - To reduce costs, lactating cows are often fed a higher proportion of roughage and alternative feeds; however, such protocols may not lead to optimal milk...     

Identification of coagulase-negative staphylococci from bovine mastitis using RFLP-PCR of the groEL gene

Coagulase-negative staphylococci (CNS) have become the predominant pathogens causing bovine mastitis in many countries. CNS infections are associated with damage to milk secretory tissue of the mammary gland by increased connective tissue stroma, moderate increases of somatic cells count in milk and significant production decreases. These consequences impose serious economic losses for the farmers and the dairy industry. Routine veterinary laboratories do not usually identify CNS at the species level. Thereby, the aims of this study were to identify the most common staphylococcal pathogens involved in bovine mastitis using PCR-restriction fragment length polymorphism (RFLP) analysis of a partial groEL gene sequence and to compare our results with the identification carried out by the conventional method. A total of 54 isolates of Staphylococcus, involved in bovine mastitis, were analyzed by this method. The size and number of the fragments obtained by either AluI or HindIII/PvuII digestions made possible to form clear patterns differentiating, among the isolates, 11 of the most common species of animal staphylococcal pathogens. Most of the isolates clustered together with the reference strain of Staphylococcus chromogenes (28) and the type strain of Staphylococcus epidermidis (8). Besides, some isolates clustered together with the type strain of Staphylococcus aureus (5). All patterns were confirmed by the conventional biochemical method, showing concordant results. Thus, the PCR-RFLP of the groEL gene constitutes a reliable and reproducible molecular method for identification of CNS species responsible for bovine mastitis.     

Real-time PCR-based prevalence study, infection follow-up and molecular characterization of canine hemotropic mycoplasmas

Hemotropic mycoplasmas (hemoplasmas) have been reported in several mammalian species including dogs. Infections may lead to hemolytic anemia, but investigations in the dog had been hampered by the lack of adequate diagnostic methods. Only recently sensitive PCR-based assays were reported for the two canine hemoplasmas, Mycoplasma haemocanis and Candidatus Mycoplasma haematoparvum. By applying these assays, 15.4% of 460 dogs from the south of France tested hemoplasma positive. It was hypothesized that this high prevalence may be associated with the presence of Rhipicephalus sanguineus, a proposed vector for canine hemoplasmas. To address this hypothesis and expand the PCR-based knowledge on canine hemoplasmosis, we investigated dogs in a climatic zone that does not allow for the permanent establishment of R. sanguineus. Blood samples were collected throughout a year from 889 dogs in Switzerland: 1.2% of the dogs tested real-time PCR positive. The infection status was not significantly associated with anemia, age or gender. Phylogenetic analyses of Candidatus M. haematoparvum and M. haemocanis isolates revealed > or =99.8% identity to published sequences. All samples collected from three infected dogs throughout a follow-up period of < or =13 months tested PCR positive. Interestingly, the majority of the infected dogs either had been imported from or had visited regions where R. sanguineus is indigenous. Thus, canine hemoplasma prevalence was found to be low in a country with a climate incompatible with frequent occurrence of R. sanguineus. Nonetheless, veterinarians may expect hemoplasma infections in dogs with a travel history and/or after potential tick vector exposure.     

Hemorrhagic diathesis and bone marrow aplasia secondary to lomustine overdose in a dog

A 9‐year‐old mixed breed 13 kg spayed female dog was presented for evaluation of two masses in the right abdominal mammary gland region. Surgery was conducted to excise the masses. A grade I complex mammary gland carcinoma and high grade (grade III) mast cell tumor with an inguinal lymph node metastasis were diagnosed. Forty‐seven days after the surgical procedure, the mast cell tumor relapsed, and neoadjuvant treatment with lomustine (81 mg/m²) was prescribed. Thirteen days from initiation of lomustine therapy, the dog was re‐presented to the hospital with bloody diarrhea, hematemesis, epistaxis, an elevated rectal temperature, depression, severe dehydration, and marked dyspnea. The CBC showed severe thrombocytopenia and leukopenia. According to the owner, lomustine (45mg per os [PO]) was mistakenly administered daily for 10 consecutive days (total dose, 810 mg/m²). The dog died and a necropsy was performed. The main gross lesions consisted of severe multifocal hemorrhages in multiple organs, especially in the digestive system. Histopathologic evaluation revealed disseminated hemorrhages, as well as marked bone marrow aplasia. This report describes the clinical, hematologic, gross, and histologic findings in a fatal case of lomustine overdose in a dog.