Effects of Microalgae and Alfalfa Meal on Population Growth and Production of a Freshwater Rotifer,Euchlanis dilatata (Rotifera: Mongononta)

Population growth and production of the freshwater rotifer, Euchlanis dilatata, were determined after being fed 1 of 12 diets: Scenedesmus quadricauda (S), Chlorella vulgaris (C), baker's yeast (Saccharomyces cerevisiae) (Y), alfalfa meal (Medicago spp.) (A), and eight combinations of S+C, S+Y, C+Y, S+C+Y, S+A, C+A, S+C+A, and Y+A (mixture in the same ratio by equal nitrogen weight). Results showed that both microalgal and alfalfa meal alone and in combination with Y had a significantly higher (P < 0.05) population growth and production compared with Y alone. The mean maximum E. dilatata population density fed on S, S+Y, C, C+Y, S+C, S+C+Y, Y, A, S+A, C+A, S+C+A, and Y+A diets were 65 ± 7.5 (mean ± SE), 124.6 ± 17.2, 115.8 ± 7.9, 41.5 ± 7.9, 131 ± 14.1, 93.5 ± 8.7, 14.5 ± 7.6, 129.5 ± 18.5, 255.0 ± 20.5, 180 ± 30.5, 124.5 ± 25.4, and 61.5 ± 24.5 individuals/mL, respectively. Correspondingly, the mean population growth rates (K) through the 16‐d culture period were 0.29, 0.40, 0.45, 0.27, 0.34, 0.41, 0.26, 0.51, 0.58, 0.59, 0.39, and 0.45/d, respectively. Results indicated that alfalfa meal in combination with microalgae and yeast could be used as primary diets for E. dilatata culture. This may reduce the costs of rotifer production.     

Salinity-induced changes in biometric,physiological and anatomical parameters of Passiflora edulis Sims plants propagated by different methods

ABSTRACT

Salinity is one of the most important abiotic stresses limiting agricultural production worldwide. Here, we investigated the biometric, physiological and anatomical changes of Passiflora edulis plants propagated from seeds, cuttings and grafts and exposed to salt stress (0.3 – control and 6.3 dS m^?1). Saline stress significantly reduced plant height, the number of leaves, total chlorophyll, stomatal conductance, shoot dry weight, total dry weight, total water consumption and root volume. Among the propagation methods evaluated, plants propagated from seeds were more sensitive to salinity, while plants propagated from cuttings showed smaller alterations when subjected to salinity. Similar behavior was observed for anatomical characteristics, since plants propagated from seeds presented more pronounced anatomical alterations, such as greater thicknesses of the leaf mesophyll, upper epidermis, lower epidermis, palisade parenchyma and spongy parenchyma and also was observed presence of calcium oxalate crystals in the form of druses in greater quantity in the root cortex, in comparison to plants propagated from cuttings. The approach used in this study allowed identifying the type of yellow passion fruit propagation (cuttings) that was best for physiological and anatomical adaptation to salt stress and will be potentially useful in programs for improvement of the crop.     

Adsorption and Desorption of Arsenate in Different Soils and Gold Mining Substrates of Minas Gerais State,Brazil

Background  Arsenic (As) availability in natural environment is related to the element’s adsorption and desorption processes in soils. Total As is better related to available As in temperate soils than in tropical soils. In tropical soils, total As is not very significant in terms of availability, therefore justifying the necessity for studies into As dynamics. Knowledge of As dynamics in soil as well as development of new analytical methodologies involving tropical soils are insufficient and necessary for future mitigation projects. Objective  The objectives of this study were: (1) To adjust methodologies which may assist in understanding arsenate dynamics in tropical soils and substrates; (2) To evaluate the adsorption and desorption of arsenate in soils and substrate samples, and to find a minimum value of arsenate available in soil which is lethal to sorghum plants. Material and Methods  Samples of three soils from Minas Gerais State (YL, RYL, and CS) and two sulfide substrates of gold mining (B1 and B2) were used in the assays. All the material was physically and chemically characterized. Remaining As (As-rem) and remaining P (P-rem) of each material, along with MAC_P and MAC_As (using the Langmuir isotherms), were obtained. After agitation to obtain MAC_P and MAC_As, arsenate was extracted by anionic resin and Mehlich-III to evaluate arsenate desorption of the material retained on the filter paper. Subsequently, arsenate desorption curves for the different materials were obtained, and arsenate availability was determined through a bioassay with sorghum plants. Samples of soils and substrate B1 were incubated with six levels of As doses. Plants were grown under greenhouse conditions for 30 days. The plants were then harvested, dried and weighed. Available As in the soils and substrate was determined by Mehlich-III. Results and Discussions  As-rem level decreased from YL (sandy) to RYL (clayey) soil samples, which always showed lower values than P-rem. Among the soils and substrates evaluated, RYL showed the highest MAC_As and MAC_P, followed by CS, YL and Bl. The results were in accordance with the values observed for As-rem and P-rem and confirm the idea that the ability of the assayed materials to remove As from the soil/substrate solution is higher than the ability to remove P. On the other hand, the binding energy (a) between soil/substrate and As is weaker than the binding energy of P. Given the fact that the studied soils present a real ability to remove As from the solution, only a small part of As would be unavailable considering MAC_As as a reference. As-Mehlich-III values were higher than As-resin for substrate Bl. Mehlich-III seemed to be more appropriate to extract labile forms of arsenate in substrate B1 as well as in the soils. Available As by Mehlich-III (26.9 mg/dm³) was considered a reference of As LCL to sorghum plants. CC50 was sensitive to the buffering capacity of each soil, showing values varying from 1.34 mg/dm³ As (clay soil with lower As-rem) to 12.31 mg/dm³ As (sandy soil with higher As-rem). Conclusions  The adaptation of the As-rem and MAC_As methodologies was satisfactory and of great value in the study of adsorption, desorption and As availability for soils and mining substrate. Mehlich-III was also satisfactory to estimate available As and was sensitive to soil buffering capacity. Nevertheless, resin can also be used as an alternative. MAC_As varied among soils and was higher than MAC_p. However, As showed higher lability than P. Using Mehlich-III, we determined the value corresponding to CC50 that showed a good reference of toxicity to available As. Outlook  The environmental implications of the As behavior are quite serious. Beside the fact that arsenate is removed very fast from the soil solution, an anthropogenic input of the element, being part of the soil quantity factor, may remain in a reversible form for a long time. As may therefore return to the soil solution and becomes available to plants, animals and the entire environment. Considering that CC50 is the maximum contents of available As the environment can tolerate to allow some vegetal biomass production, the maximum capacity of As immobilization in each soil is reduced when compared to the soils’ MAC_As values. Therefore, the maximum and safe values of reference to be used in the evaluation of incidental discharge of the element in soils must be reduced.     

Monitoring virulence and sexual compatibility in Brazilian Bremia lactucae populations

During the winter, there is a high occurrence of downy mildew on lettuce caused by Bremia lactucae. This oomycete shows variability in virulence, so understanding the genetic structure of the pathogen population becomes essential for obtaining resistant cultivars. Thus, the objective of this study was to determine sexual compatibility in Brazilian populations of B. lactucae and investigate the occurrence of sexual reproduction of the pathogen on lettuce (Lactuca sativa) and prickly lettuce (Lactuca serriola). Leaf samples were collected in 33 municipalities in seven Brazilian states. The virulence structure of the populations was monitored using the EU-C sextet code. B. lactucae populations from the states of São Paulo, Paraná, Rio de Janeiro, and Rio Grande do Sul shared six of the 15 virulence factors evaluated. Twenty-five virulence phenotypes (v-phenotypes) were found, with the sextet codes 31-00-02, 31-16-02, 31-24-02, and 31-01-02 being more frequent. The predominance of some v- phenotypes indicates that clonal reproduction is still the main form of B. lactucae propagation. The genes and resistance factors of the cultivars Argelès (Dm38), Balesta, and Bartoli are recommended as suitable sources of lettuce resistance in Brazil. Natural occurrence of oospores was detected in most sampled locations, in lettuce and prickly lettuce plants. Virulence variability of Brazilian isolates is the result of the pathogen's ability to reproduce both sexually and asexually, with a prevalence of homothallic isolates; although the majority were of the predominant B₂ mating type, there was a high incidence of predominant B₁ in addition to B₁ = B₂.     

Cerebral neuroblastoma and pituitary adenocarcinoma in two budgerigars (Melopsittacus undulatus)

Case 1: A tumor mass involving the rostral part of left cerebrum was found in a two-year-old female budgerigar (Melopsittacus undulatus) at necropsy. Histologically, the neoplastic cells were arranged in sheets or cords and occasionally showed nest growth patterns. These uniform tumor cells had a little cytoplasm and ovoid or round basophilic nuclei with clearly distinct cytoplasmic membranes. The tumor cells were strong diffusely immunostained with both neuron-specific enolase (NSE) and neurofilament protein and partially for synaptophysin. They lacked chromogranin A, glial fibrillary acidic protein (GFAP), vimentin, S-100, and cytokeratin antigen expression. Moreover, they had no reaction to antibodies against pituitary hormones, such as adrenocorticotrophic hormone (ACTH), growth hormone, and prolactin. The histological and immunohistochemical examination determined the tumor as neuroblastoma. Case 2: An extremely enlarged pituitary mass was found above the sella turcica of a male budgerigar. It was soft and well delineated from the adjacent structures. On histological examination, this tumor consisted of a sheet of large closely packed polyhedral cells that had scant to a large amount of pale to strongly eosinophilic cytoplasm. The pleomorphic nuclei were apparently variable in shape, from small round hyperchromatic to very large vesicular forms. The cell boundaries were not clearly distinct. The multifocal immunolabelling of neoplastic cells for NSE, synaptophysin, GFAP, and ACTH appeared, whereas a few cells reacted with vimentin and S-100 and stained negative for other markers, which were also utilized for case 1. Histological and immunohistochemical findings led to identification of corticotroph adenocarcinoma in the pituitary gland.     

Evaluation of immunohistochemistry for the diagnosis of sporotrichosis in dogs

The aim of this study was to apply immunohistochemistry (IHC) for the diagnosis of canine sporotrichosis and to compare this method with the Grocott’s silver stain (GSS) and periodic acid Schiff (PAS) techniques. Eighty-seven dogs with sporotrichosis (group 1) and 35 with American tegumentary leishmaniosis (ATL) (group 2) were studied. The fungus was detected in group 1 by GSS, PAS and IHC. IHC was also applied to group 2 to evaluate the occurrence of cross-reactions. PAS, GSS and IHC detected yeast cells in 19.5%, 43.7% and 65.5% of the group 1 cases, respectively. The detection of intracellular antigens of Sporothrix schenckii by IHC increased the sensitivity of the histological diagnosis to 80.5%. No positive reaction was observed in ATL lesions. The results suggest that IHC may be indicated for the diagnosis of sporotrichosis because of its higher diagnostic sensitivity.     

Use of GGEbiplot methodology and Griffing's diallel method for genetic analysis of partial resistance to phoma black stem disease in sunflower

Abstract

The objectives of the present study were to estimate the general combining ability (GCA) and specific combining ability (SCA) for partial resistance to phoma black stem and to identify the most promising combination for the selection of improved breeding lines. The response of five parental genotypes and their F1 hybrids to a phoma black stem isolate (MA6) were evaluated in a diallel programme under controlled growth chamber conditions. Significant GCA and SCA indicate that both additive and non-additive gene effects contributed in the inheritance of partial resistance to phoma black stem, however, the Baker ratio showed that the additive genetic effects were more important than nonadditive ones. It is recommended that the GGEbiplot methodology could be an excellent tool for visualizing entry by tester (diallel) data. By using this technique to analyse black stem severity data, interaction among the sunflower genotypes in providing partial resistance to phoma black stem was clearly identified. Based on GGEbiplot presentation and Griffing's diallel analysis, the mutant line ‘M6-54-1’ showed the largest GCA, indicating contribution towards partial resistance, and the genotype B454/03 presented the smallest GCA, indicating contribution towards susceptibility. Our results show that the F1 hybrids ‘SDR18×B454/03’ and ‘M6-54-1×B454/03’ showing heterosis for partial resistance to phoma black stem come from the crosses between a susceptible genotype ‘B454/03’ and two partially resistant genotypes (SDR18 and M6-54-1), originated from different breeding programmes. We conclude therefore that these genotypes possess at least some different resistance genes, which were expressed in the hybrids and led to the observed effects.     

Characterization of single nucleotide polymorphism in Tunisian grapevine genome and their potential for population genetics and evolutionary studies

In this study, two gene fragments corresponding to the VvMYBA1 and VvMYBA2 loci were sequenced on a sample of grapes including cultivated and wild accessions originating from Tunisia, Germany and France. A total of 42 SNPs were detected in the sequenced fragments giving an average of 1 SNP every 33 bp. High level of polymorphism was observed in the samples either in cultivated or wild accessions. Pattern of nucleotide diversity indicates a non departure from neutrality expectations for wild grapevine sample for gene VvMYBA1 and VvMYBA2 and for cultivated sample for gene VvMYBA1. However, a linkage to a selective sweep was revealed for cultivated grapevine gene pool in gene VvMYBA2. A genetic structure of the studied sample according to accession taxonomic status was revealed by the UPGMA clustering with a considerable overlap. This result was confirmed by significant but low genetic differentiation values between cultivated and wild sample. The number of migrants Nm based on sequence data information between Tunisian cultivars and Tunisian wild accessions showed a low level of gene flow between those germplasms. This finding indicates that Tunisian cultivars do not derive directly from local wild populations but could mostly correspond to imported materials introduced during historical times. However, the possibility that some cultivars derived from ancestral events of local domestication or cross hybridization with native wild plants was not completely excluded for Tunisian grapevine accessions.