Endothelium-independent effects of phyllanthin and hypophyllanthin on vascular tension

The purpose of this study was to investigate the modulating effects of phyllanthin and hypophyllanthin on vascular tension, using in the in vitro model of isolated rat aorta. Our results indicated that both phyllanthin and hypophyllanthin significantly relaxed the sustained contraction induced by phenylephrine (PE) in a concentration-dependent manner. In addition, endothelial removal had no significant influence on the vasorelaxation responses of the aortic rings toward these two compounds. Furthermore, both compounds inhibited the contraction of aortic muscle provoked by either PE (1 μM) or KCl (40 mM) as well as the spontaneous contraction of the Ca²⁺-depleted muscle. In high K⁺- Ca²⁺ free solution, phyllanthin (100 μM), but not hypophyllanthin, significantly inhibited the contractile responses upon cumulative addition of CaCl₂. Both compounds (100 μM) significantly inhibited PE-induced contraction in Ca²⁺-free condition, but could not affect caffeine-induced contraction. Taken together, phyllanthin and hypophyllanthin could modulate the vascular tension via the endothelium-independent mechanisms. The modulating effects of both compounds were possibly involved with the blockade of Ca²⁺ entry into vascular smooth muscle cells and inhibition of PE-mediated Ca²⁺ release from sarcoplasmic reticulum.     

ermB-mediated erythromycin resistance in Streptococcus uberis from bovine mastitis

The ermB gene was identified in 111 erythromycin resistant isolates of Streptococcus uberis from cases of bovine mastitis associated either with a constitutive (47/111) or an inducible (64/111) phenotype, as well as a phenotypic resistance to all macrolides tested. Resistance to lincosamides was identified in 14 other isolates of S. uberis from bovine mastitis cases and was mainly mediated by the linB gene; resistance conferred by a combination of two genes (linB–lnuD, ermB–linB) was also detected.     

Production and characterization of fibroin hydrogel using waste silk fibers

The use of natural resources, especially processing wastes, as low cost and environmentally friendly alternative aiming high value-added applications is a subject of broad interest. Since the Brazilian silk production annually generates a large amount of waste during the silk fibers processing, this work explores the preparation and characterization of silk fibroin hydrogels using spinning waste silk fibers from textile processing and the processed ones. Hydrogels were obtained directly by dialyzing silk fibroin solutions against frequent changes of water until the gelation point and then lyophilized and characterized in terms of their morphology, crystallinity, thermal resistance and secondary structure. X-ray diffraction analysis revealed the presence of β-sheet conformation related to sol-gel transition. FT-IR spectra indicated the coexistence of random coil (silk I) and β-sheet (silk II) structures, with predominance of β-sheet conformation for hydrogels from processed silk fibers. From thermogravimetric analysis the presence of β-sheet secondary conformation was demonstrated by a degradation peak around 292 °C for both hydrogels. Freeze-dried hydrogels presented sheet or leaf like morphology and no significant change was observed among the hydrogels from waste silk fibers and processed ones. These characteristics suggest that silk fibroin hydrogels prepared from spinning waste silk fibers and obtained directly by dialysis can be potential candidates for biomaterials application, such as drug delivery systems and for wound dressings.     

Phenotypic and genetic characterization of Salmonella enterica subsp. enterica serovar Typhimurium isolated from pigs in Rio Grande do Sul, Brazil

This study aimed to investigate the relatedness of porcine Salmonella enterica subsp. enterica (S.) serovar Typhimurium strains isolated in Southern Brazil. Sixty-six isolates from pigs belonging to three commercial companies were submitted to phage typing, XbaI-macrorestriction (PFGE), IS200 hybridization, rep-PCR, antimicrobial susceptibility testing, and PCR assay targeting the spvR region. All strains presented a unique rep-PCR pattern and 63 strains had a common IS200 profile. One pulse-type (XA) was the most prevalent (39/66 strains) and included strains of phage types DT177, DT192, DT194 and RDNC. The spvR region was detected in three strains, which harboured plasmids of 90 kb. High rates of tetracycline, sulfonamide and streptomycin resistance were found. Isolates from farms located in different geographic regions but associated to the same commercial companies clustered together and presented a common resistance profile. Results suggested that clonal groups of S. Typhimurium are present in pig commercial companies in Southern Brazil.     

Cover Image,Volume 74, Issue 8

The cover image, by Marisa Skaljac et al., is based on the Research Article Fitness costs of infection with Serratia symbiotica are associated with greater susceptibility to insecticides in the pea aphid Acyrthosiphon pisum, DOI: 10.1002/ps.4881 . Image Credit: Marisa Skaljac.

     

Tree-grass coexistence in a flood-disturbed, semi-arid savanna system

The coexistence of trees and grasses in savanna ecosystems is a contentious phenomenon. Fire and herbivory disturbances are often cited as major structuring forces that create a sustainable tree–grass relationship. However, periodic flooding of savanna patches may also enable coexistence. The aim of this study was to investigate the effects of flood-disturbance on the recruitment patterns of Acacia karroo trees in a semi-arid savanna system in South Africa. We analysed the spatial coincidence of A. karroo seedlings with tussocks of the tall spiny grass Stipagrostis namaquensis in the riverbed and related herbivory intensity to spatial position. The data showed that A. karroo seedlings were significantly positively associated with S. namaquensis (Chi-square test, $ \chi_{1}^{2} = 4 5. 20 $ , n = 118, P < 0.001); A. karroo seedlings growing inside of tussocks experienced less browsing pressure than those growing in the floodplain (Kruskal–Wallis test, H = 11.90, n = 118, P < 0.01); and recruitment success of A. karroo trees was spatially discrete (K–S test, D = 0.78, n = 196, P < 0.01). We suggest that floods create an enemy-free zone, which S. namaquensis colonises and then facilitates successful A. karroo establishment. High levels of A. karroo recruitment in the riverbed may replenish the woodlands fringing the river, which appear to be sink areas for A. karroo seedlings. Thus, the interaction between disturbances at different spatial and temporal scales (flooding versus herbivory) seems to maintain the inherently unstable coexistence of tree and grass species in this ecosystem. These findings also suggested that flood disturbances alter the tree–grass relationship.     

Light and scanning electron microscopy of the miracidium of Echinostoma paraensei (Trematoda, Echinostomatidae)

Echinostoma paraensei was described 1967 by Lie and Basch. Recently its natural definitive host, the aquatic rodent Nectomys squamipes, endemic in Brazil, was identified. As most of the echinostomatids, this species presents a zoonotic potential. The morphology and topography of the E. paraensei miracidium obtained from adult worms collected from the natural definitive host N. squamipes is described by light and electron microscopy. The arrangement and the dimensions of the epidermal plates are given. The eyespots are composed by two pairs of lenses measuring 6.03 microm. SEM observations shows that the miracidium body is covered by cilia except at the terebratorium region and the presence of alpha-tubulin in the cilia of the larvae is first recorded by immunelabeling. Nineteen papilla-like structures arranged in three axes and four groups were observed at the terebratoriun, this structure is retractable, presenting folds and a corrugated surface with profiles of cytoplasmic expansions, forming network of anatomizing folds.     

Rabbit metabolic response and selected meat quality traits: Evaluation of dietary PLX®23 and LycoBeads® feed supplement

Effects of dietary supplementation of verbascoside and lycopene, alone and in combination, on some blood parameters, plasma oxidative status and meat quality traits in intensively reared rabbits were investigated. The test lasted 60 days and was conducted on 200 weaned‐rabbits, divided into four groups of 50 animals each (5 animals each cage × 10 repetitions). The control group (CON) received a fattening feed without any feed supplements, whereas the experimental groups received the following: the first, an integration in 22 g of PLX^®23 (Lippia citriodora extract; VB group) per ton of feed; the second, an integration in 100 g of LycoBeads^® (Solanum lycopersicum extract; LIC group) per ton of feed; and the third, an integration of both feed supplements in combination at the same doses (LIC+VB group). The dietary supplementation with Lippia citriodora and Solanum lycopersicum resulted in an improvement of the blood lipid profile, oxidative plasma markers, and hepatic and renal activity of treated growing rabbits. Feed additives also produced meat with a lower content in SFA and an increased PUFA content, and inhibited the lipid oxidation improving the oxidative stability of rabbit meat. The dietary supplementation, even reporting no effects on productive parameters and carcass yield, showed an improvement on several blood parameters, as indicator of animal welfare, and on quality and healthy meat markers.     

Dietary effect of lemon verbena extract on selected blood parameters and on plasma oxidative profile in Avelignese horses

The effect of Lippia citriodora extract on selected blood parameters and on plasma oxidative markers in Avelignese horses was evaluated. Twenty‐four horses were divided into three groups, consisting of eight animals each. Results of two experimental groups, 0.5 mg of verbascoside per kg of metabolic body weight (bw^0.75) in the low‐dose group (LVB) and 1.0 mg of verbascoside per kg of metabolic body weight (bw^0.75) in the high‐dose group (HVB), were compared to the control group (CON). Groups fed L. citriodora extract (HVB and LVB) showed a significant decrease in triglycerides, total cholesterol and LDL cholesterol (p < .01), bilirubin, and transaminases (p < .05), and an increase in HDL cholesterol (p < .01) compared to the CON group. Oxidative status was improved due to significant decrease in plasma concentration of ROMs and TBARS (p < .01) and increase in levels of vitamin A and vitamin E (p < .01). Based on obtained results, it is assumed that dietary supplementation with L. citriodora extract might find a useful application in horse feeding, with positive impact observed in blood parameters and plasma oxidative markers, with beneficial effects on the physiological welfare of livestock animals.