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BACKGROUND: Silver nanoparticles (AgNPs), particularly those entrapped in polymeric nanosystems, have arisen as options for managing plant bacterial diseases. Among the biopolymers useful for the entrapment of AgNPs, chitosan is promising because of its low cost, good biocompatibility, antimicrobial properties and biodegradability. The present study aimed: (i) to greenly-synthesize AgNPs using different concentrations of aqueous extract of tomato leaves followed by entrapment of AgNPs with chitosan (CH-AgNPs); (ii) to characterize the optical, structural and biological properties of the nanosystems produced; (iii) to evaluate the antimicrobial activities of AgNPs and nanomaterials; and (iv) to assess the effectiveness of AgNPs and nanomaterials for controlling tomato bacterial wilt caused by Ralstonia solanacearum. RESULTS: Spherical and oval AgNPs had incipient colloidal instability, although the concentration of the tomato leaf extract influenced both size (< 87 nm) and the polydispersity index. Nanomaterials (< 271 nm in size) were characterized by a highly stable matrix of chitosan containing polydisperse AgNPs. Free AgNPs and CH-AgNPs were stable for up to 30 days, with no significant alteration in physicochemical parameters. The AgNPs and nanomaterials had antibacterial activity and decreased bacterial growth at micromolar concentrations after 48 h. Morphological changes in R. solanacearum cells were observed after treatment with CH-AgNPs. The application of CH-AgNPs at 256 µmol L-1 reduced the incidence of bacterial wilt in a partially resistant tomato genotype but not in the susceptible line. CONCLUSION: Greenly-synthesized chitosan-derived nanomaterials containing AgNPs produced with leaf extracts from their own species appear to comprise a promising and sustainable alternative in an integrated management approach aiming to reduce the yield losses caused by bacterial wilt. © 2019 Society of Chemical Industry.

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Biofilms are microbial sessile communities attached to surfaces that are known for causing many medical problems. A bacterial biofilm of clinical relevance is formed by the gram-negative bacteria Pseudomonas aeruginosa. During the formation of a biofilm, the initial adhesion of the cells is of crucial importance, and the characteristics of the contact surface have great influence on this step. In the present study, we aimed to use matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling as a new methodology to monitor P. aeruginosa biofilm development. Biofilms were grown within polypropylene tubes containing a glass slide, and were harvested after 3, 5, 7, 9, or 12 days of inoculation. Planktonic cells were obtained separately by centrifugation as control. Two independent MALDI-TOF experiments were performed, one by collecting biofilms from both the glass slide and the polypropylene tube internal surface, and the other by acquiring biofilms from these surfaces separately. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to evaluate the morphological progression of the biofilm. The molecular results showed that MALDI profiling is able not only to distinguish between different biofilm stages, but it is also appropriate to indicate when the biofilm cells are released at the dispersion stage, which occurred first on polypropylene surface. Finally, the present study pointed out that MALDI profiling may emerge as a promising tool for the clinical diagnostic and prognostic workup of biofilms formation and control.

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Effective methods for gamete preservation should have low impact on DNA integrity. The present study investigated the effects of vitrification of goat ovarian tissues on the occurrence of DNA fragmentation and DNA double-stand breaks using the terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling (TUNEL) assay and detection of phosphorylated histone H2AX (γH2AX), respectively. Goat ovaries were collected at a local abattoir and 12 tissue fragments were prepared from each ovarian pair. Tissue fragments were used as fresh control samples or were cultured in vitro, vitrified or vitrified and cultured. Vitrification was performed using the Ovarian Tissue Cryosystem. Fragments from all groups (control and treatments) were processed for histology, transmission electron microscopy, TUNEL assay and immunofluorescence. Compared with fresh control samples, a lower percentage of morphologically normal follicles was detected in the vitrification followed by culture treatment group (P<0.05). Normal follicular ultrastructure was observed in all groups. Immunofluorescence revealed the presence of γH2AX foci in few oocytes and ovarian stromal cells. TUNEL-positive follicles were found in samples without significant differences among groups (P>0.05). In conclusion, the vitrification protocol used in the present study did not increase DNA damage in preantral follicles enclosed in goat ovarian tissues.

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This study aimed to investigate potential acute and subchronic toxicity of rhodium (II) citrate in female Balb/c mice after intraperitoneal injections. In the acute test, independent groups received five doses; the highest dose (107.5 mg/kg) was equivalent to 33 times that used in our previous reports. The other doses were chosen as proportions of the highest, being 80.7 (75%), 53.8 (50%), 26.9 (25%) or 13.8 mg/kg (12.5%). Animals were monitored over 38 days and no severe signs of toxicity were observed, according to mortality, monitoring of adverse symptoms, hematological, biochemical and genotoxic parameters. We conclude that the median lethal dose (LD50) could be greater than 107.5 mg/kg. In the subchronic test, five doses of Rh2Cit (80, 60, 40, 20 or 10 mg/kg) were evaluated and injections were conducted on alternate days, totaling five applications per animal. Paclitaxel (57.5 mg/kg) and saline solution were controls. Clinical observations, histopathology of liver, lung and kidneys and effects on hematological, biochemistry and genotoxic records indicated that Rh2Cit induced no severe toxic effects, even at an accumulated dose up to 400 mg/kg.We suggest Rh2Cit has great potential as an antitumor drug without presenting acute and subchronic toxicity.

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Background: For decades, the mechanisms maintaining the dormancy, survival and growth of mammalian primordial follicles as well as their growth up to an early antral stage have been not well understood. In recent years, data obtained from studies on the expression and quantification of mRNA for several growth factors and from studies with genetically modified mouse models have revealed a number of molecules, whose functions are indispensable for (i) the maintenance of follicular quiescence, (ii) primordial follicle survival and (iii) activation, and/or (iv) the growth of primary follicles up to an early antral stage. Review: This review focuses on expression of mRNA and protein for growth factors, cytokines and their respective receptors in early follicles, as well as on the intrafollicular signaling cascades that lead to the in-vitro activation of primordial follicles. Furthermore, fundamental information on the levels of mRNA for growth factors at different stages of follicular development and the in-vitro effects of several locally expressed factors on ovarian follicular development will be discussed. During the transition into the primary stage or from the primary into the secondary follicle stage of goats there is a significant increase in the mRNA expression of different factors (BMP-6, BMP-15, KL, EGF, VIP, GDF-9). The detection of these different factors depends on the species. In rat ovaries, GHR is detected in oocytes, granulosa and theca cells. The presence of the mRNA for GHR, but not that for GH has been detected in rat pre-antral follicles. GHR mRNA has only been found in granulosa cells, while positive immunostaining for GHR has been observed in both oocytes and granulosa cells. Also in vitro studies with goat primordial follicles have demonstrated that different factors, estradiol and progesterone promote primordial follicle activation and/or oocyte growth. Recently, several studies have been performed with mouse primordial follicles to understand how intrafollicular cytokines and growth factors may control the fate of primordial follicles in the ovary. In rodents, anti-Mullerian hormone has been shown to inhibit mouse primordial follicle growth and to downregulate c-kit expression in rats, suggesting that, at least in rodents, the kit system plays a key role in initiation of follicular growth. In relation to control of primary and secondary follicles, several in vitro studies have demonstrated that FSH, activin-A, EGF, GH, IGF-I and IGF-II stimulate oocyte growth and follicular development in different species. Conclusion: This review updates the information on expression of mRNA and proteins for growth factors and their role in the regulation of development from primordial to early antral follicles. The growing knowledge of the molecules that control the dormancy, survival, activation and growth of primordial follicles will not only contribute for a better understanding of the physiology of the mammalian ovary, but will also enable researchers to develop more promising methods for promoting growth of oocytes from primordial follicles, the richest follicular resource in the mammalian ovary.

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