Caprine toxoplasmosis in Southern Brazil: a comparative seroepidemiological study between the indirect immunofluorescence assay,the enzyme-linked immunosorbent assay,and the modified agglutination test

Tropical Animal Health and Production - This study investigated the prevalence of caprine toxoplasmosis in goat herds from Southern Brazil by the indirect immunofluorescence assay (IFA), and...     

Continuous Production of Biogenic Magnetite Nanoparticles by the Marine Bacterium Magnetovibrio blakemorei Strain MV-1T with a Nitrous Oxide Injection Strategy

Magnetotactic bacteria (MTB) produce magnetosomes, which are membrane-embedded magnetic nanoparticles. Despite their technological applicability, the production of magnetite magnetosomes depends on the cultivation of MTB, which results in low yields. Thus, strategies for the large-scale cultivation of MTB need to be improved. Here, we describe a new approach for bioreactor cultivation of Magnetovibrio blakemorei strain MV-1^T. Firstly, a fed-batch with a supplementation of iron source and N₂O injection in 24-h pulses was established. After 120 h of cultivation, the production of magnetite reached 24.5 mg∙L⁻¹. The maximum productivity (16.8 mg∙L⁻¹∙day⁻¹) was reached between 48 and 72 h. However, the productivity and mean number of magnetosomes per cell decreased after 72 h. Therefore, continuous culture in the chemostat was established. In the continuous process, magnetite production and productivity were 27.1 mg∙L⁻¹ and 22.7 mg∙L⁻¹∙day⁻¹, respectively, at 120 h. This new approach prevented a decrease in magnetite production in comparison to the fed-batch strategy.     

Short-term changes in nitrogen availability, gas fluxes (CO2, NO, N2O) and microbial biomass after tillage during pasture re-establishment in Rondônia, Brazil

Anthropogenic conversion of primary forest to pasture for cattle production is still frequent in the Amazon Basin. Practices adopted by ranchers to restore productivity to degraded pasture have the potential to alter soil N availability and N gas losses from soils. We examined short-term (35 days) effects of tillage prior to pasture re-establishment on soil N availability, CO₂, NO and N₂O fluxes and microbial biomass C and N under degraded pasture at Nova Vida ranch, Rondônia, Brazilian Amazon. We collected soil samples and measured gas fluxes in tilled and control (non tilled pasture) 12 times at equally spaced intervals during October 2001 to quantify the effect of tillage. Maximum soil NH₄⁺ and NO₃⁻ pools were 13.2 and 6.3 kg N ha⁻¹ respectively after tillage compared to 0.24 and 6.3 kg N ha⁻¹ in the control. Carbon dioxide flux ranged from 118 to 181 mg C–CO₂ m² h⁻¹ in the control (non-tilled) and from 110 to 235 mg C–CO₂ m² h⁻¹ when tilled. Microbial biomass C varied from 365 to 461 μg g⁻¹ in the control and from 248 to 535 μg g⁻¹ when tilled. The values for N₂O fluxes ranged from 1.22 to 96.9 μg N m⁻² h⁻¹ in the tilled plots with a maximum 3 days after the second tilling. Variability in NO flux in the control and when tilled was consistent with previous measures of NO emissions from pasture at Nova Vida. When tilled, the NO/N₂O ratio remained <1 after the first tilling suggesting that denitrification dominated N cycling. The effects of tilling on microbial parameters were less clear, except for a decrease in qCO₂ and an increase in microbial biomass C/N immediately after tilling. Our results suggest that restoration of degraded pastures with tillage will lead to less C matter, at least initially. Further long-term research is needed.     

Free amino acid composition of quince (Cydonia oblonga Miller) fruit (pulp and peel) and jam

Twenty-one free amino acids present in several samples of quince fruit (pulp and peel) and quince jam (homemade and industrially manufactured) were analyzed by GC/FID. The analyses showed some differences between quince pulps and peels. Generally, the highest content in total free amino acids and in glycine was found in peels. As a general rule, the three major free amino acids detected in pulps were aspartic acid, asparagine, and hydroxyproline. For quince peels, usually, the three most abundant amino acids were glycine, aspartic acid, and asparagine. Similarly, for quince jams the most important free amino acids were aspartic acid, asparagine, and glycine or hydroxyproline. This study suggests that the free amino acid analysis can be useful for the evaluation of quince jam authenticity. It seems that glycine percentage can be used for the detection of quince peel addition while high alanine content can be related to pear addition.     

Cross-crop effects on larval growth,survivorship and fecundity of <Emphasis Type="Italic">Helicoverpa armigera</Emphasis>

The cotton bollworm Helicoverpa armigera is a destructive pest that affects a variety of crop plants. Because of its polyphagous feeding habit, mobility as adults, and high fecundity, the expanding infestations of H. armigera in different crops have caused economic losses and difficulties for pest population management. In Brazil, a sequence of different crop systems in the same area and crop rotation during the year can create a spatio-temporal mosaic of crops where H. armigera can persist. However, the consequences of the simultaneous and/or alternating presence of host plants for H. armigera populations through generations are unknown. In this study, we simulated, in the laboratory, hypothetical situations for the availability of soybean and cotton crops in the landscape. We evaluated the effects of: (1) the number of generations during which a population feeds on a host-plant species; (2) the succession of host-plant species on which populations have fed for two generations; and (3) the parental host plant on the fitness of H. armigera populations. Only the current host plant on which larvae fed affected the performance of the H. armigera populations. Decrease of mortality rates during the immature period was slowed when the larvae fed on soybean. The lowest value of reproductive potential (R ₀) was found for individuals originating from mating between females and males reared in cotton. Our results indicated that pest-management and biological-control plans for H. armigera should be developed on a regional scale rather than for just a specific crop area.     

Extreme resistance to infection by potato virus X in genotypes of wild tuber-bearingSolanum species

Summary Clones derived from thirty-one different accessions (nineteen of Argentine origin) belonging to eightSolanum species were screened for resistance to infection by potato virus X strain cp (PVX cp) by mechanical inoculation of plantlets that had been micropropagated in vitro. Estimates of PVX multiplication obtained by enzyme linked immunosorbent assay and slot blot nucleic acid hybridization allowed the identification of resistant clones derived from five accessions belonging toS. commersonii S. oplocense, S. sparsipilum andS. tuberosum andigena. Resistant genotypes supported PVX concentrations 5 to 15 times smaller than did the susceptible control cultivar Spunta. Graft inoculation test confirmed the presence of extreme resistance similar to that conferred by the ‘immunity’ gene X¹ (also called RX_act).     

Effect of Artificial Diets on Growth,Survival and Condition of Adult Cuttlefish, <Emphasis Type="Italic">Sepia officinalis</Emphasis> Linnaeus, 1758

The effects of artificial diets on growth and body condition of adult cuttlefish, Sepia officinalis were tested in two experiments. Supplemented prepared diets (fish myofibrillar protein concentrate) were fed during a 30-day and a 21-day experiments. Growth, feeding rate and food conversion of group-reared cuttlefish were analyzed. The first of these experiments tested four artificial diets, made with increasing levels of lysine, on adult cuttlefish. According to the chemical analysis, diets 1–3 had limiting concentrations of lysine and other essential amino acids (compared to mantle composition of the cuttlefish), while diet 4 was the only one where almost all essential amino acids were present in concentrations similar or higher than the ones present in cuttlefish mantle. A second experiment was conducted by isolating 16 adult cuttlefish individually, and feeding them the same four artificial diets, in order to obtain individual data. During Experiment 1, only the diet with the best chemical score (diet 4) produced growth (p < 0.05), with a mean instantaneous growth rate (MIGR) of 0.30% wet body weight (BW) d⁻¹. Similarly, individually reared cuttlefish fed diet 4 produced the highest IGR’s (0.26, 0.38 and 0.48% BW d⁻¹) and grew larger (p < 0.01). Comparison of cuttlefish fed the artificial diets vs. thawed shrimp and unfed cuttlefish indicated that cuttlefish fed the artificial diets were in an intermediate state. Growth rates obtained with the artificial diets (<0.4% BW d⁻¹) were considerably lower compared to natural prey, live or frozen, reported by other authors.     

Prospects of polyploidizing cassava, Manihot esculenta Crantz, by unreduced microspores

Eleven interspecific hybrids of cassava with the wild relatives Manihot glaziovii, M. pseudoglaziovii. M. dichotoma and M. anomala were examined to detect unreduced microspores. The frequency of dyads and triads was counted, as well as pollen viability. Of these hybrids, the second generation progeny of cassava×M. glaziovii showed a high frequency of unreduced microspores (3.7%) permitting their selection for further manipulation of this character. An association of vegetatively-reproduced genotypes and the occurrence of unreduced microspores has also been observed.     

Grain number and grain weight in wheat lines contrasting for stem water soluble carbohydrate concentration

In wheat, the ability to store and remobilise large amounts of stem water soluble carbohydrates (WSC) to grain constitutes a desirable trait to incorporate into germplasm targeted to regions with frequent terminal drought. The main aim of this paper was to examine the relationships between WSC storage, grain number and grain weight across several environments. A small set of recombinant inbred lines (2–4) contrasting in stem WSC were grown in six field trials where water availability, sowing date and/or N level were manipulated, with line yields ranging from 400 to 850 g m⁻² across experiments. Biomass, N and WSC concentration (WSCc, mg g⁻¹ dry weight) and amount (WSCa, g m⁻²) were monitored. A resource-oriented area-based model [Fischer, R.A., 1984. Growth and yield of wheat. In: Smith, W.H., Bante, S.J. (Eds.), Potential Productivity of Field Crops Under Different Environments. International Rice Research Institute, Los Baños, pp. 129–154] and intrinsic rates of organ growth were used to investigate the consequences on grain number of potential competition between spike and stem around flowering.     

Spasmolytic Effect of Caulerpine Involves Blockade of Ca2+ Influx on Guinea Pig Ileum

In this work, we investigated the spasmolytic effect of caulerpine, a bisindole alkaloid isolated from marine algae of the Caulerpa genus, on guinea pig ileum. Our findings indicated that caulerpine inhibited phasic contractions induced by carbachol (IC₅₀ = 7.0 ± 1.9 × 10⁻⁵ M), histamine (IC₅₀ = 1.3 ± 0.3 × 10⁻⁴ M) and serotonin (IC₅₀ = 8.0 ± 1.4 × 10⁻⁵ M) in a non-selective manner. Furthermore, caulerpine concentration-dependently inhibited serotonin-induced cumulative contractions (pD′₂ = 4.48 ± 0.08), shifting the curves to the right with E_max reduction and slope of 2.44 ± 0.21, suggesting a noncompetitive antagonism pseudo-irreversible. The alkaloid also relaxed the ileum pre-contracted by KCl (EC₅₀ = 9.0 ± 0.9 × 10⁻⁵ M) and carbachol (EC₅₀ = 4.6 ± 0.7 × 10⁻⁵ M) in a concentration-dependent manner. This effect was probably due to inhibition of Ca²⁺ influx through voltage-gated calcium channels (Ca_V), since caulerpine slightly inhibited the CaCl₂-induced contractions in depolarizing medium without Ca²⁺, shifting the curves to the right and with E_max reduction. According to these results, the spasmolytic effect of caulerpine on guinea pig ileum seems to involve inhibition of Ca²⁺ influx through Ca_V. However, other mechanisms are not discarded.