The organophosphorous insecticide chlorpyrifos affects the neuroepithelial junction, the bioelectric parameters of the skin of the frog Caudiverbera caudiverbera, and the structure of model cell membranes

The current study examines the acute effects of the organophosphorus pesticide chlorpyrifos on a sympathetic synapse of the frog Caudiverbera caudiverbera. Nerve stimulation was followed immediately by a transient increase in the short-circuit current (SCC) and in the potential difference (PD), which consisted of a rapid and then a slow component. Chlorpyrifos concentrations from 5 μM to 1.0 mM caused a dose-dependent block of both components to a 10% of their control values, which was reversed by washout. The pesticide blockade did not affect the skin response to noradrenaline. X-ray diffraction and fluorescence spectroscopy studies on membrane models showed marked phospholipid perturbation, which favors changes in ion channel conformation and interferes with receptor proteins, thus altering noradrenergic transmission and Cl⁻ secretion in the mucous glands. The foregoing results may be interpreted as a reversible inhibition of the neuroepithelial synapse to nerve stimulation, possibly due to non-specific lip μd-protein perturbation, interference with synaptic transmission, and transient Cl⁻ channel inactivation.     

Electrophysiological Recordings from Embryonic Mouse Motoneurons Cultured on Electrospun Poly-Lactic Acid (PLA) and Polypyrrole-Coated PLA Scaffolds

Background:Biomaterials used as cell growth stimulants should be able to provide adequate cell adhesion with no alteration in cell function. In this work, we developed a 3D model of mouse spinal cord motoneurons on scaffolds composed of electrospun PLA fibers and plasma-polymerized PPy-coated PLA fibers. Methods:The functionality of the cultured motoneurons was assessed by evaluating both the electrophysiological response (i.e., the whole-cell Na⁺ and K⁺ currents and the firing of action potentials) and also the expression of the VAChaT by immunostaining techniques. While the expression of the VAChaT was confirmed on motoneurons cultured on the fibrous scaffolds, the electrophysiological responses indicated Na⁺ and K⁺ currents with lower amplitude and slower action potentials when compared to the response recorded from spinal cord motoneurons cultured on Poly-DL-Ornithine/Laminin- and plasma-polymerized PPy-coated coverslips.Results:From a morphological viewpoint, motoneurons cultured on PLA and PPy-coated PLA scaffolds did not show the development of dendritic and/or axonal processes, which were satisfactorily observed in the bidimensional cultures.Conclusion:We hypothesize that the apparently limited development of dendritic and/or axonal processes could produce a deleterious effect on the electrophysiological response of the cells, which might be due to the limited growth surface available in the fibrous scaffolds and/or to an undesired effect of the purification process.Key Words: Electrophysiology, Pyrrol, Scaffolds     

Isolation and pathogenicity of Colletotrichum spp. causing anthracnose of strawberry in south west Spain

Anthracnose, caused by Colletotrichum spp., is a major disease of cultivated strawberry, Fragaria × ananassa. This study identifies the Colletotrichum spp. which causes strawberry anthracnose in the southwest of Spain. A survey of the region was carried out, and the strains isolated were identified as C. acutatum by using the polymerase chain reaction (PCR) with genus and species-specific primers, demonstrating that this species is currently the causal agent of strawberry anthracnose in the studied region. The pathogenicity of C. acutatum and C. gloeosporioides strains was evaluated on two principal strawberry cultivars (cvs Camarosa and Ventana) under field conditions, the latter being more pathogenic than the former.     

Mites associated with budgerigars Melopsittacus undulatus (Psittaciformes: Psittacidae) and the first report of Ornithonyssus bursa (Mesostigmata: Macronyssidae) in Mexico

Background:Hematophagous mites affect numerous bird species, causing severe injuries to the budgerigars. Some species can cause dermatitis in humans.Aims:The purpose was to morphologically identify the mites related to budgerigars (Melopsittacus undulatus) and their nests in Yucatan, Mexico.Methods:In May 2022, a private budgerigar hatchery was visited and mites were collected from the bodies of the birds and their nests. The morphological traits of the mites were confirmed by scanning electron microscopy.Results:Four of 30 birds showed severe clinical signs of mite infestation. The Budgerigars revealed lesions in the cere, nostrils, eyelids, beak, and paws. The bird’s skin showed signs of dryness and beige coloring. The birds with severe damage also presented anorexia and had deformed paws and beaks. The parasitosis was caused by the “burrowing mites,” Knemidocoptes pilae. The burrowing mites and the Grallacheles bakeri were recovered and identified from paw scabs. To eliminate mites, a topical application of Ivermectin was administered to the necks of the birds. The dose was a single, which has a residuality of 21 days. Two drops (0.115 mg/ml) of ivermectin were applied to each bird. A gradual reduction in crusted lesions due to mite mortality was noted. The “tropical fowl mite” Ornithonyssus bursa was identified in the nests, which represents the first record in Mexico.Conclusions:Three species of mites were discovered in a single budgerigar hatchery. This emphasizes the importance of deworming birds and keeping a clean environment in their cages to reduce the potential for parasitic mite infestation.     

Candidate genes underlying QTL for flowering time and their interactions in a wide spring barley (Hordeum vulgare L.) cross

Response to vernalization and photoperiod are the main determinants controlling the time to flowering in temperate cereals. While the individual genes that dete...     

Soybean molasses as an organic carbon source in the farming of Litopenaeus vannamei (Boone, 1931) in a biofloc system

Soybean molasses was evaluated as a partial replacement for sugarcane molasses as a carbon source for biofloc development in the superintensive culture of Pacific white shrimp (Litopenaeus vannamei). A 50‐day study was conducted with juvenile (3.2 g) shrimp stocked in 16 800 L tanks at a stocking density of 250 shrimp m^?3. Control of total ammonia concentration was performed by the addition of combined mixtures of soybean and sugarcane molasses to the culture water. Three different molasses treatments were evaluated using different soybean‐to‐sugarcane molasses ratios: 15–85%, 38–62% and 60–40% respectively. The control group was treated only with sugarcane molasses. Water quality, chlorophyll a concentration, heterotrophic bacterial load, Vibrio spp. concentration and zootechnical indexes were all evaluated. Total ammonia concentration was controlled by heterotrophic and chemotrophic pathways. Biofloc formation, as quantified by measuring the total suspended solids, was not altered. The Vibrio spp. concentration showed a significant reduction in treatments with soybean‐to‐sugarcane molasses ratios of 38–62% and 60–40%. All combined mixtures of soybean and sugarcane molasses could maintain water quality and productivity in the superintensive culture of L. vannamei using the biofloc system. Thus, the potential use of a residue from agroindustry as a carbon source in a biofloc culture is demonstrated.     

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.     

Kinetic modeling of malonylgenistin and malonyldaidzin conversions under alkaline conditions and elevated temperatures

The conversion and degradation of malonylglucosides were kinetically characterized under elevated pH/heat conditions. Malonylgenistin and malonyldaidzin were heated at 60, 80, and 100 degrees C and pH values of 8.5, 9, and 9.5. A simple kinetic model was developed, which adequately predicted the conversion and degradation reactions. The conversion and degradation rates increased as temperature and pH increased. The rates of conversion of both malonylglucosides into their respective beta-glucosides were comparable under all pH/heat treatments. However, at 100 degrees C, the rates of degradation of malonyldaidzin were approximately double those of malonylgenistin, under all pH treatments. When malonlydaidzin was heated at 100 degrees C and pH 9.5, degradation of the produced daidzin occurred. Therefore, an alternative kinetic model was developed to better predict the conversion and degradation of malonyldaidzin occurring at 100 degrees C and pH 9.5. The models developed provide soy food manufacturers with guidelines for better control of the profile and level of isoflavones..     

Broccoli processing wastes as a source of peroxidase

A peroxidase isozyme (BP) was purified to homogeneity from broccoli stems ( Brassica oleraceae var. maraton) discarded from industrial processing wastes. BP specific activity was 1216 ABTS [2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid)] units/mg, representing 466-fold that of crude extract. BP is a monomeric glycoprotein containing 16% carbohydrates, with a molecular mass of 49 kDa and an isoelectric point close to 4.2. From kinetic data it showed a two-substrate ping-pong mechanism, and the catalytic efficiency measured as the rate-limiting step of free BP regeneration was 3.4 x 10(6) M(-1) s(-1). The ABTS K m value was 0.2 mM, which was about 20 times lower than that reported for acidic commercial horseradish peroxidase (HRP). Assessment of BP secondary structure showed 30% helical character, similar to HRP and cytochrome c peroxidase. BP lost only 25% activity after 10 min of heating at 55 degrees C and pH 6; it was stable in the pH range from 4 to 9 and showed an optimum pH of 4.6 using ABTS as substrate. BP was active on substrates normally involved in lignin biosynthesis, such as caffeic and ferulic acids, and also displayed good catechol oxidation activity in the presence of hydrogen peroxide. Reverse micellar extraction was successfully used as potential large-scale prepurification of broccoli peroxidase, achieving a purification factor of 7, with 60% activity yield. Stems from the broccoli processing industry have a high potential as an alternative for peroxidase purification.