Homogeneous Canine Chest Phantom Construction: A Tool for Image Quality Optimization

Digital radiographic imaging is increasing in veterinary practice. The use of radiation demands responsibility to maintain high image quality. Low doses are necessary because workers are requested to restrain the animal. Optimizing digital systems is necessary to avoid unnecessary exposure, causing the phenomenon known as dose creep. Homogeneous phantoms are widely used to optimize image quality and dose. We developed an automatic computational methodology to classify and quantify tissues (i.e., lung tissue, adipose tissue, muscle tissue, and bone) in canine chest computed tomography exams. The thickness of each tissue was converted to simulator materials (i.e., Lucite, aluminum, and air). Dogs were separated into groups of 20 animals each according to weight. Mean weights were 6.5 ± 2.0 kg, 15.0 ± 5.0 kg, 32.0 ± 5.5 kg, and 50.0 ± 12.0 kg, for the small, medium, large, and giant groups, respectively. The one-way analysis of variance revealed significant differences in all simulator material thicknesses (p < 0.05) quantified between groups. As a result, four phantoms were constructed for dorsoventral and lateral views. In conclusion, the present methodology allows the development of phantoms of the canine chest and possibly other body regions and/or animals. The proposed phantom is a practical tool that may be employed in future work to optimize veterinary X-ray procedures.     

Effect of the presence and location of corpus luteum on competence of bovine cumulus-oocyte complexes

This study aimed to determine the effect of presence of the corpus luteum (CL) and its influence on cumulus–oocyte complexes (COCs) obtained from the ipsilateral or contralateral ovary in bovine on the recovery and capacity of the oocytes to sustain mono-spermic fertilization, undergo preimplantation development, and develop to the blastocyst stage. Ovaries were collected at a local slaughterhouse and kept in pairs corresponding to the same animal. In the first experiment the variables evaluated were compared between cows with (CCL⁺) and without (CCL^-) CL, and for the second experiment, comparisons were made between ovaries with an ipsilateral (CL⁺), contralateral (CL⁻), and no (NCL). The recovery rate of COCs was higher in ovaries from CCL⁻ cows, and a higher proportion of grade 1 COCs were recovered from this group. A higher proportion of metaphase I oocytes at 7 h of maturation, and a higher rate of cleavage were observed in the CCL⁺ group; however, a higher proportion of embryos were obtained from the CCL⁻ group. Besides, COCs from the CL⁺ group had a lower proportion of grades 1 and 2 morphological qualities, lower rate of metaphase II oocytes at 22 h of maturation, and lower rate of formation of two pronuclei, whereas a higher proportion of unfertilized oocytes after in vitro fertilization. On the other hand, the COCs from the CL⁻ group displayed a lower proportion of oocytes with more than two pronuclei, higher cleavage rate, and higher final blastocyst production were obtained when compared to CL+. Thus, the effects of CL on the competence of bovine COCs are different depending on the anatomical proximity of their location in the animal, negatively affecting the quality of COCs located in the same ovary, but not having negative effects on the competence of COCs in the ovaries contralateral to their location.     

Molecular cloning and functional expression of a novelNeurospora crassa xylose reductase inSaccharomyces cerevisiae in the development of a xylose fermenting strain

The development of a xylose-fermentingSaccharomyces cerevisiae yeast would be of great benefit to the bioethanol industry. The conversion of xylose to ethanol involves a cascade of enzymatic reactions and processes. Xylose (aldose) reductases catalyse the conversion of xylose to xylitol. The aim of this study was to clone, characterise and express a cDNA copy of a novel aldose reductase (NCAR-X) from the filamentous fungusNeurospora crassa inS. cerevisiae. NCAR-X harbours an open reading frame (ORF) of 900 nucleotides. This ORF encodes a protein (NCAR-X, assigned NCBI protein accession ID: XP_956921) consisting of 300 amino acids, with a predicted molecular weight of 34 kDa. TheNCAR-X-encoded aldose reductase showed significant homology to the xylose reductases ofCandida tenuis andPichia stipitis. WhenNCAR-X was expressed under the control of phosphoglycerate kinase I gene (PGK1) regulatory sequences inS. cerevisiae, its expression resulted in the production of biologically active xylose reductase. Small-scale oxygen-limited xylose fermentation with theNCAR-X containingS. cerevisiae strains resulted in the production of less xylitol and at least 15% more ethanol than the strains transformed with theP. stipitis xylose reductase gene (PsXYL1). TheNCAR-X-encoded enzyme produced byS. cerevisiae was NADPH-dependent and no activity was observed in the presence of NADH. The co-expression of theNCAR-X andPsXYL1 gene constructs inS. cerevisiae constituted an important part of an extensive research program aimed at the development of xylolytic yeast strains capable of producing ethanol from plant biomass.     

Structural and ecophysiological adaptations to forest gaps

To survive new microclimatic conditions of a forest gap environment, plant species must physiologically and structurally adjust. A morpho-anatomical, ultrastructural and ecophysiological study was performed at three different times in a forest gap that was created by illegal selective logging. The study followed the early successional Actinostemon verticillatus and the late-successional Metrodorea brevifolia, to elucidate the adaptive strategies of acclimation to gaps. Additionally, Schinus terebinthifolius was included in the study in order to test the plasticity of a pioneer species that grows on forest edges, where this species had higher values of leaf thickness, leaf mass area and succulence. M. brevifolia had succulent leaves, high leaf area and a thin cuticle. A. verticillatus presented the densest leaves and was the only species to show leaf morpho-anatomical plasticity. Ultrastructural and physiological differences were observed only in A. verticillatus and M. brevifolia leaves from the gap: increase in the stroma volume, oil droplets, plastoglobuli, photochemical and non-photochemical quenching. Photosynthetic efficiency showed that the early stages of gap formation are the most critical. Acclimation strategies of A. verticillatus suggest this species invests in the efficiency of photosynthesis by increasing its leaf thickness, leaf mass area and in water content maintenance by increasing the density of its leaves, at the expense of gas exchange, was compensated by a high density of stomata. M. brevifolia compensates for the higher cost of leaves and lower leaf plasticity with ultrastructural changes that are used to adjust the photosynthetic process, which promotes a shorter leaf payback time.     

Long-term treatment with fluoxetine induces desensitization of 5-HT4 receptor-dependent signalling and functionality in rat brain

The mode of action of antidepressant drugs may be related to mechanisms of monoamines receptor adaptation, including serotonin 5-HT₄ receptor subtypes. Here we investigated the effects of repeated treatment with the selective serotonin reuptake inhibitor fluoxetine for 21 days (5 and 10 mg/kg, p.o., once daily) on the sensitivity of 5-HT₄ receptors by using receptor autoradiography, adenylate cyclase assays and extracellular recording techniques in rat brain. Fluoxetine treatment decreased the density of 5-HT₄ receptor binding in the CA1 field of hippocampus as well as in several areas of the striatum over the doses of 5–10 mg/kg. In a similar way, we found a significant lower response to zacopride-stimulated adenylate cyclase activity in the fluoxetine 10 mg/kg/day treated group. Furthermore, post-synaptic 5-HT₄ receptor activity in hippocampus-measured as the excitatory action of zacopride in the pyramidal cells of CA1 evoked by Schaffer collateral stimulation was attenuated in rats treated with both doses of fluoxetine. Taken together, these results support the concept that a net decrease in the signalization pathway of 5-HT₄ receptors occurs after chronic selective serotonin reuptake inhibitor treatment: this effect may underlie the therapeutic efficacy of these drugs.     

Affinity labeling of residues within Hv2 of guinea pig anti-azobenzenearsonate antibodies of different isotypes and from different strains

Anti-p-azobenzenearsonate (ARS) antibodies of IgG1 and IgG2 isotypes produced in inbred strain 13 and strain 2 guinea pigs were affinity labeled with N-(bromoacetyl)-3-[(p-arsonophenyl)azo]-L-tyrosine (BAAT) or N-(bromoacetyl)-p-arsanilic acid (BAA). BAAT was shown to modify approximately 50% of the binding sites specifically and BAA approximately 30%. Both reagents preferentially modified residues in the heavy (H) chain to the extent that it contained over 80% of the affinity label associated with the native molecule. At least 80% of label borne by the variable domain of the H chain (VH) was found in the second hypervariable region (Hv2). BAAT labeled all anti-ARS antibodies exclusively at position N-59, which contains a lysyl residue. BAA labeled predominantly tyrosine at N-57 and, to a lesser extent, lysine-59 and tyrosine-50. Comparison of Hv2 sequences in anti-ARS and in antibodies reactive with other haptens has shown that tyrosine at N-50 and N-57 as well as lysine at N-59 is distinctive of antibodies with anti-ARS specificity, thus implying their involvement in antigen binding. The predominant sequence of Hv2 was identical in anti-ARS IgG1 and IgG2 molecules induced in either inbred guinea pig strain following either carrier priming or conventional immunization. Although limited variability does occur among the various populations of anti-ARS antibodies in certain residue positions in Hv2, no significant differences in the binding affinities or in the indexes of heterogeneity were seen among the various kinds of anti-ARS antibodies.     

Phytoplankton Growth and Microzooplankton Grazing in the Subtropical Northeast Atlantic

Dilution experiments were performed to estimate phytoplankton growth and microzooplankton grazing rates during two Lagrangian surveys in inner and eastern locations of the Eastern North Atlantic Subtropical Gyre province (NAST-E). Our design included two phytoplankton size fractions (0.2–5 µm and >5 µm) and five depths, allowing us to characterize differences in growth and grazing rates between size fractions and depths, as well as to estimate vertically integrated measurements. Phytoplankton growth rates were high (0.11–1.60 d⁻¹), especially in the case of the large fraction. Grazing rates were also high (0.15–1.29 d⁻¹), suggesting high turnover rates within the phytoplankton community. The integrated balances between phytoplankton growth and grazing losses were close to zero, although deviations were detected at several depths. Also, O₂ supersaturation was observed up to 110 m depth during both Lagrangian surveys. These results add up to increased evidence indicating an autotrophic metabolic balance in oceanic subtropical gyres.     

Chemical Characterization and Phytotoxic Effects of the Aerial Parts of Ruzigrass (Urochloa ruziziensis)

Studies of the phytotoxic effects between plants can be a crucial tool in the discovery of innovative compounds with herbicide potential. In this sense, we can highlight ruzigrass (Urochloa ruziziensis), which is traditionally used in the crop rotation system in order to reduce weed emergence. The aim of this work was to characterize the secondary metabolites of ruzigrass and to evaluate its phytotoxic effects. In total, eight compounds were isolated: friedelin, oleanolic acid, α‐amyrin, 1‐dehydrodiosgenone, sitosterol and stigmasterol glycosides, tricin and p‐coumaric acid. Phytotoxic effects of the crude methanolic extract and fractions of ruzigrass were assessed using germination rate, initial seedling growth, and biomass of Bidens pilosa, Euphorbia heterophylla and Ipomoea grandifolia. Chemometric analysis discriminated the weed species into three groups, and B. pilosa was the most affected by fractions of ruzigrass. The phytotoxic activities of 1‐dehydrodiosgenone, tricin, and p‐coumaric acid are also reported, and p‐coumaric acid and 1‐dehydrodiosgenone were active against B. pilosa.