Schistosoma mansoni-New Zealand rabbit model: resistance induced by infection followed by active immunization with protective antigens

In previous studies, rabbits immunized with adult worm antigens released from fresh adult schistosomes incubated in saline media showed a significant level of protection against challenge parasites. Focusing on the rabbit-Schistosoma mansoni model, concomitant immunity was investigated. A peculiar form of response to cercarial infection was observed: rabbits subjected to percutaneous infection and similar reinfections at different times after primary infection killed schistosomula from the challenge infection as well as established parasites from the primary infection. In this study the challenge infection stimulus was replaced by active immunization with an adult worm-derived protective antigenic mixture. The results show that immunization of New Zealand rabbits with an adult worm antigenic extract is capable of inducing a response that results in a significant reduction of the mean worm burden of the primary infection earlier than did homologous infection, as compared to worm reduction due to a second infection.     

Maternal prenatal depressive symptoms predict infant NR3C1 1F and BDNF IV DNA methylation

Prenatal maternal psychological distress increases risk for adverse infant outcomes. However, the biological mechanisms underlying this association remain unclear. Prenatal stress can impact fetal epigenetic regulation that could underlie changes in infant stress responses. It has been suggested that maternal glucocorticoids may mediate this epigenetic effect. We examined this hypothesis by determining the impact of maternal cortisol and depressive symptoms during pregnancy on infant NR3C1 and BDNF DNA methylation. Fifty-seven pregnant women were recruited during the second or third trimester. Participants self-reported depressive symptoms and salivary cortisol samples were collected diurnally and in response to a stressor. Buccal swabs for DNA extraction and DNA methylation analysis were collected from each infant at 2 months of age, and mothers were assessed for postnatal depressive symptoms. Prenatal depressive symptoms significantly predicted increased NR3C1 1F DNA methylation in male infants (β = 2.147, P = 0.044). Prenatal depressive symptoms also significantly predicted decreased BDNF IV DNA methylation in both male and female infants (β = −3.244, P = 0.013). No measure of maternal cortisol during pregnancy predicted infant NR3C1 1F or BDNF promoter IV DNA methylation. Our findings highlight the susceptibility of males to changes in NR3C1 DNA methylation and present novel evidence for altered BDNF IV DNA methylation in response to maternal depression during pregnancy. The lack of association between maternal cortisol and infant DNA methylation suggests that effects of maternal depression may not be mediated directly by glucocorticoids. Future studies should consider other potential mediating mechanisms in the link between maternal mood and infant outcomes.     

Mutagenic activation of dialkylnitrosamines by intact urothelial cells

Intact urothelial cells isolated from bladders of untreated inbred NZO/BIGd or NZC/BIGd mice and NZR/Gd rats activated dimethyl, diethyl, dipropyl, and dibutyl nitrosamines in a liquid culture mutagenesis fluctuation assay using Salmonella typhimurium TA100 as target organism. Rat and mouse urothelial cells were highly effective at 1.5 X 10(5) cells/ml, in O2 gas phase, and no cofactors were required. Relative mutagenic activities were estimated at equitoxic (LD50) concentrations of the 4 nitrosamines. Nitrosamines with odd-carbon chain substitutents were more active than the C-even compounds. Although dibutylnitrosamine is a powerful bladder carcinogen in both rats and mice while the other 3 compounds very rarely cause bladder tumours, the most active promutagens were dipropyl and dimethyl, followed by diethyl and dibutyl nitrosamines. None were active in absence of urothelial cells. Mouse bladder cells were more active than those from NZR rats. There were sex differences in the mice with NZC males and NZO females predominating, but in NZR rats urothelial cells from male and female animals were equally active. These dialkylnitrosamines are widely distributed in the environment, and our results indicate that direct mutagenic activation in the urothelium could be one factor contributing to the incidence of bladder cancer.     

Distribution et échantillonnage des populations de Amblyseius manihoti Moraes (Acari, Phytoseiidae) sur manioc au Brésil

Distribution of Amblyseius manihoti (Acari, Phytoseiidae) on manioc and development of sampling plan
Sampling plans were developed for Amblyseius manihoti , a predator of the cassava green mite Mononychellus progresivus Doreste (Acari, Tetranychidae). Analysis of intra-plant distribution showed a more stable and constant distribution of A. manihoti on the leaves 9–12 (numbering starting from the first fully developed leaf), hence leaves belonging to this stratum were chosen as the sampling unit. Within this unit, A. manihoti displayed aggregated distributions between plants. The proposed binomial and the enumerative sampling procedures permitted reliable estimates of A. manihoti densities. For population monitoring, 100 sample units per field were sufficient to provide satisfactory estimates of densities.     

Heterogenized polymetallic catalysts Part II. Oxidation of 3,5-di-t-butylphenol by Cu(II), Fe(III) and Pd(II) complexed to a polyphenylene polymer containing ß-di- and triketone surface ligands; an improved catalyst system

Polyphenylene polymer preparation involves the cyclic trimerization polymerization of acetylated methyl benzoate with diacetyl benzene. Since the methyl benzoate groups do not take part in the polymerization they are present in high concentration. The ß-diketone ligands were placed on the surface by reaction of the methylbenzoate group with base and a methyl ketone and the triketone by reaction with base to give the ß-triketone. The ß-triketones can bind two metal ions in a known geometry that is suitable for bimetallic catalysis of the rapid polyelectron oxidation of catechols. The final catalytic surfaces were prepared by treating the chemically modified polymer with copper(II), iron(II) and palladium(II) acetonitrile complexes with non-coordinating BF₄⁻ as the anion. Since the metal ions contain no strongly coordinating ligand, they are very reactive species. These surfaces catalyzed the rapid air oxidation of 3,5-di-tert-butylcatechol (DTBC). The diketone surfaces gave only 3,5-di-tert-butyl-o-quinone (DTBQ) while the triketone surfaces gave ring-cleaved products, confirming the special catalytic effect of the triketone surface. Also, only the triketone catalysts showed any activity for ring cleavage oxidation of DTBQ. These catalysts were much more reactive than previous ones using the same polyphenylene polymer but without the methyl benzoate groups. With these polymers the di- and triketone groups were placed on the surface by chemical modification of the unpolymerized acetyl groups.     

Identification and functional expression of a new xylose isomerase from the goat rumen microbiome in Saccharomyces cerevisiae

The current climate crisis demands replacement of fossil energy sources with sustainable alternatives. In this scenario, second-generation bioethanol, a product of lignocellulosic biomass fermentation, represents a more sustainable alternative. However, Saccharomyces cerevisiae cannot metabolize pentoses, such as xylose, present as a major component of lignocellulosic biomass. Xylose isomerase (XI) is an enzyme that allows xylose consumption by yeasts, because it converts xylose into xylulose, which is further converted to ethanol by the pentose-phosphate pathway. Only a few XI were successfully expressed in S. cerevisiae strains. This work presents a new bacterial XI, named GR-XI 1, obtained from a Brazilian goat rumen metagenomic library. Phylogenetic analysis confirmed the bacterial origin of the gene, which is related to Firmicutes XIs. After codon optimization, this enzyme, renamed XySC1, was functionally expressed in S. cerevisiae, allowing growth in media with xylose as sole carbon source. Overexpression of XySC1 in S. cerevisiae allowed the recombinant strain to efficiently consume and metabolize xylose under aerobic conditions.