Immobilization of L-asparaginase towards surface-modified carbon nanotubes

L-asparaginase (LA) is an enzyme that catalyzes L-asparagine hydrolysis into L-aspartic acid and ammonia and is mainly applied in pharmaceutical and food industries. The LA currently commercialized for pharmaceutical purposes is produced from two main bacterial sources: recombinant Escherichia coli and Erwinia chrysanthemi. However, some disadvantages are associated with its free form, such as the shorter half-life. Immobilization of LA has been proposed as an efficient approach to overcome this limitation. In this work, a straightforward method, including the functionalization of multi-walled carbon nanotubes (MWCNTs) through a hydrothermal oxidation treatment and the immobilization of LA by adsorption over pristine and modified MWCNTs was investigated. Different operation conditions, including pH, contact time, ASNase/MWCNT mass ratio, and the operational stability of the immobilized LA, were evaluated. The characterization of the LA-MWCNT bioconjugate was addressed using different techniques, namely Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA), and Raman spectroscopy. Functionalized MWCNTs showed promising results, with an immobilization yield and a relative recovered activity of commercial LA above 95%, under the optimized adsorption conditions (pH 8, 60 min of contact, and 1.510–3 g.mL-1 of LA). The LA-MWCNT bioconjugate also showed improved enzyme operational stability (6 consecutive reaction cycles without activity loss), proving its suitability for application in industrial processes.publishe

Immobilization of L-asparaginase towards surface-modified carbon nanotubes

L-asparaginase (ASNase, EC 3.5.1.1) is an enzyme that catalyzes L-asparagine hydrolysis into L-aspartic acid and ammonia and is mainly applied in pharmaceutical and food industries [1]. The ASNase currently commercialized for pharmaceutical purposes is produced from two main bacterial sources: recombinant Escherichia coli and Erwinia chrysanthemi. However, some disadvantages are associated with its free form, such as the shorter half-life [2]. Immobilization of ASNase has been proposed as an efficient approach to overcome this limitation [3]. In this work, a straightforward method, including the functionalization of multi-walled carbon nanotubes (MWCNTs) through a hydrothermal oxidation treatment with nitric acid, and the immobilization of ASNase by adsorption over pristine and modified MWCNTs was investigated. Different operation conditions, including pH, contact time, ASNase/MWCNT mass ratio, and the operational stability of the immobilized ASNase were evaluated. The characterization of the ASNase-MWCNT bioconjugate was addressed using different techniques, namely Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA), and Raman spectroscopy. Functionalized MWCNTs showed promising results, with an immobilization yield and a relative recovered activity of commercial ASNase above 95%, under the optimized adsorption conditions (pH 8, 60 min of contact and 1.5´10–3 g.mL-1of ASNase). The ASNase-MWCNT bioconjugate also showed improved enzyme operational stability (6 consecutive reaction cycles without activity loss), proving its suitability for application in industrial processes.publishe

Quantum gravity phenomenology at the dawn of the multi-messenger era—A review

The exploration of the universe has recently entered a new era thanks to the multi-messenger paradigm, characterized by a continuous increase in the quantity and quality of experimental data that is obtained by the detection of the various cosmic messengers (photons, neutrinos, cosmic rays and gravitational waves) from numerous origins. They give us information about their sources in the universe and the properties of the intergalactic medium. Moreover, multi-messenger astronomy opens up the possibility to search for phenomenological signatures of quantum gravity. On the one hand, the most energetic events allow us to test our physical theories at energy regimes which are not directly accessible in accelerators; on the other hand, tiny effects in the propagation of very high energy particles could be amplified by cosmological distances. After decades of merely theoretical investigations, the possibility of obtaining phenomenological indications of Planck-scale effects is a revolutionary step in the quest for a quantum theory of gravity, but it requires cooperation between different communities of physicists (both theoretical and experimental). This review, prepared within the COST Action CA18108 “Quantum gravity phenomenology in the multi-messenger approach”, is aimed at promoting this cooperation by giving a state-of-the art account of the interdisciplinary expertise that is needed in the effective search of quantum gravity footprints in the production, propagation and detection of cosmic messengers.publishedVersio

Effect of eCG and progestagen on ovarian follicle population in goats

International audienceThe aim of present study was to evaluate the response of ovarian follicle population to eCG/progestagen treatment in goats. In second half of February, seven Serrana goats (G-eCG) received 250 UI of eCG (Intergonan®, Intervet, Holland) at the removal of intravaginal sponges impregnated with 20 mg of flugestone acetate (Chronogest® CR 20 mg, Intervet, Holland) and kept in place during 6 days. Six other Serrana goats (G-C) remained untreated as controls. Ovarian transrectal ultrasonographic examinations were performed in both groups at 0 h, 20 h, 42 h, 72 h and 92 h after eCG administration in G-eCG. Follicles were counted and classified according to the following classes: total follicles, 0.05) between groups were found in any class of follicles. However, an increase of total follicles between 0 h (7.1 ± 0.4) and 72 h (9.9 ± 0.4) or 92 h (10.3 ± 0.6; P 0.05). Also, in G-eCG, the number of 3-5 follicles class increased from 0 h (1.7 ± 0.3) to 42 h (3.8 ± 0.2; P 5 class, the number of follicles remained constant (1.2 ± 0.2) in all examinations, without differences between groups. The number of follicles <3 mm was constant in both groups until 42 h (4.7 ± 0.3) but increased at 92 h (7.1 ±0.5; P < 0.001) in G-eCG. These results suggest that low dose of eCG stimulate the number of 3-5 mm follicles present in ovaries but not the small (<3 class) follicles, in order to ovulate

Characterization of mammary pathogenic Escherichia coli reveals the diversity of Escherichia coli isolates associated with bovine clinical mastitis in Brazil

ABSTRACT: Mammary pathogenic Escherichia coli (MPEC) is one of the most common pathogens associated with clinical mastitis. We analyzed isolates obtained from milk samples of cows with clinical mastitis, collected from 10 farms in Brazil, to verify molecular and phenotypic characteristics. A total of 192 (4.5%) mammary pathogenic E. coli isolates were obtained from 4,275 milk samples analyzed, but we tested 161. We assigned most of these isolates to E. coli phylogroups B1 (52.8%) and A (36.6%), although phylogroups B2, C, D, E, and unknown also occurred. All isolates were assessed for the presence of several genes encoding virulence factors, such as adhesins (sfaDE, papC, afaBC III, ecpA, fimH, papA, and iha), toxins (hlyA, cnf1, sat, vat, and cdt), siderophores (iroN, irp2, iucD, ireA, and sitA), an invasion protein (ibeA), and serum resistance proteins (traT, KpsMTII, and ompT), and isolates from phylogroups B1, B2, and E showed up to 8 genes. Two isolates harbored the locus of enterocyte effacement (escN+) and lack the bundle-forming pilus (bfpB−) operon, which corresponds to a molecular profile of a subgroup of diarrheagenic E. coli (aEPEC), thus being classified as hybrid MPEC/aEPEC isolates. These isolates displayed a localized adherence-like pattern of adherence in HeLa cells and were able to promote F-actin polymerization underneath adherent bacteria. Based on the pulsed-field gel electrophoresis analyses, considerable genetic variability was observed. A low index of antimicrobial resistance was observed and 2 extended-spectrum β-lactamase–producing E. coli were identified, both harboring blaCTX-M15 gene, and were classified as ST10 and ST993 using multilocus sequence typing. A total of 148 (91.2%) isolates were weak biofilm producers or formed no biofilm. Because raw milk is still frequently consumed in Brazil, the occurrence of virulence factor–encoding genes from extraintestinal or diarrheagenic E. coli added to the presence of extended-spectrum β-lactamase–producing isolates can turn this veterinary medicine problem into a public health concern

Ocorrência de lesões em carcaças de bovinos de corte no Pantanal em função do transporte Occurrence of carcass bruising of beef cattle in the Pantanal related to time spent transport

O trabalho teve como objetivo avaliar a influência do transporte na ocorrência de lesões, em carcaças de bovinos abatidos no Pantanal Sul Matogrossense, por meio da quantificação do número e do tamanho das lesões, assim como a localização da freqüência de ocorrência das lesões nos principais cortes comerciais padronizados para o mercado interno. Do total de 121 carcaças avaliadas, foi observado que 102 (84,3%) tiveram uma ou mais lesões, totalizando 270 lesões que resultaram na remoção de 56,1kg de carne, com média geral de 0,5kg por animal ou 0,6kg por animal, considerando-se apenas os animais que tiveram lesões. A freqüência de lesões em carcaças de bovinos evidenciou diferença significativa de acordo com as condições de transporte. As maiores proporções de lesões foram encontradas em animais submetidos ao transporte rodoviário por mais de uma hora e distâncias maiores que 70km, sendo grande parte em estradas não-pavimentadas. Conclui-se que os animais submetidos à série sucessiva de manejo e transportados em estradas não-pavimentadas por longas distâncias apresentaram maior proporção de lesões, sendo que os animais provenientes do lote VI apresentaram maior número de lesões.<br>This study aimed to assess the influence of transport on the occurrence of carcass bruising of cattle slaughtered in the Pantanal, by quantifying the number and size of bruises, locating the frequency of occurrence of bruises in the main commercial cuts standardized for interne market. From a total of 121 carcasses assessed, 102 (84.3%) had one or more bruises, totaling 270 bruises, which resulted in the removal of 56.1kg meat. The frequency of carcass bruises of cattle showed significant difference, according to the conditions of transport. The highest proportions of bruises found in animals submitted to road transport for more than one hour in distances longer than 70km, a great part of which on dirty toads. The conclusion is that the animals submitted to the successive series of handling and transported on dirty roads for long distances caused the highest proportion of bruises, whereas the animals submitted to lot IV presented the highest number of bruises