A versatile characterization of poly(N-isopropylacrylamideco- N,N'-methylene-bis-acrylamide) hydrogels for composition, mechanical strength, and rheology

Poly(N-isopropylacrylamide-co-N,N"-methylene-bisacrylamide) (P(NIPAAm-co-MBA)) hydrogels were prepared in water using redox initiator. The copolymer composition at high conversion (> 95%) was determined indirectly by HPLC (high performance liquid chromatography) analysis of the leaching water and directly by solid state 13C CP MAS NMR (cross polarization magic angle spinning nuclear magnetic resonance) spectroscopy of the dried gels, and was found to be close to that of the feed. The effect of cross-linker (MBA) content in the copolymer was investigated in the concentration range of 1.1–9.1 mol% (R:90–10; R = mol NIPAAm/mol MBA) on the rheological behaviour and mechanical strength of the hydrogels. Both storage and loss modulus decreased with decreasing cross-linker content as revealed by dynamic rheometry. Gels R70 and R90 with very low cross-linker content (1.2–1.5 mol% MBA) have a very loose network structure, which is significantly different from those with higher cross-linker content manifesting in higher difference in storage modulus. The temperature dependence of the damping factor served the most accurate determination of the volume phase transition temperature, which was not affected by the cross-link density in the investigated range of MBA concentration. Gel R10 with highest cross-linker content (9.1 mol% MBA) behaves anomalously due to heterogeneity and the hindered conformation of the side chains of PNIPAAm

Occurrence of regulated mycotoxins and other microbial metabolites in dried cassava products from Nigeria

Open Access JournalDried cassava products are perceived as one of the potential sources of mycotoxin ingestion in human foods. Processing either contributes to the reduction of toxins or further exposes products to contamination by microorganisms that release metabolic toxins into the products. Thus, the prevalence of microbial metabolites in 373 processed cassava products was investigated in Nigeria. With the use of liquid chromatography tandem-mass spectrometry (LC-MS/MS) for the constituent analysis, a few major mycotoxins (aflatoxin B1 and G1, fumonisin B1 and B2, and zearalenone) regulated in food crops by the Commission of the European Union were found at concentrations which are toxicologically acceptable in many other crops. Some bioactive compounds were detected at low concentrations in the cassava products. Therefore, the exposure of cassava consumers in Nigeria to regulated mycotoxins was estimated to be minimal. The results provide useful information regarding the probable safety of cassava products in Nigeri

Efficacy of metabolites of a Streptomyces strain (AS1) to control growth and mycotoxin production by Penicillium verrucosum, Fusarium verticillioides and Aspergillus fumigatus in culture

The objectives of this study were to determine the efficacy of metabolites of a Streptomyces strain AS1 on (a) spore germination, (b) mycelial growth, (c) control of mycotoxins produced by Penicillium verrucosum (ochratoxin A, OTA), Fusarium verticillioides (fumonisins, FUMs) and Aspergillus fumigatus (gliotoxin) and (d) identify the predominant metabolites involved in control. Initial screening showed that the Streptomyces AS1 strain was able to inhibit the mycelial growth of the three species at a distance, due to the release of secondary metabolites. A macroscopic screening system showed that the overall Index of Dominance against all three toxigenic fungi was inhibition at a distance. Subsequent studies showed that the metabolite mixture from the Streptomyces AS1 strain was very effective at inhibiting conidial germination of P. verrucosum, but less so against conidia of A. fumigatus and F. verticillioides. The efficacy was confirmed in studies on a conducive semi-solid YES medium in BioScreen C assays. Using the BioScreen C and the criteria of Time to Detection (TTD) at an OD = 0.1 showed good efficacy against P. verrucosum when treated with the Streptomyces AS1 extract at 0.95 and 0.99 water activity (aw) when compared to the other two species tested, indicating good efficacy. The effective dose for 50% control of growth (ED50) at 0.95 and 0.99 aw were approx. 0.005 ng/ml and 0.15 μg/ml, respectively, with the minimum inhibitory concentration (MIC) at both aw levels requiring > 40 μg/ml. In addition, OTA production was completely inhibited by 2.5 μg/ml AS1 extract at both aw levels in the in vitro assays. Ten metabolites were identified with four of these being predominant in concentrations > 2 μg/g dry weight biomass. These were identified as valinomycin, cyclo(L-Pro-L-Tyr), cyclo(L-Pro-L-Val) and brevianamide F

Analysis of Mycotoxin and Secondary Metabolites in Commercial and Traditional Slovak Cheese Samples

Cheese represents a dairy product extremely inclined to fungal growth and mycotoxin production. The growth of fungi belonging to Aspergillus, Penicillium, Fusarium, Claviceps, Alternaria, and Trichoderma genera in or on cheese leads to undesirable changes able to affect the quality of the final products. In the present investigation, a total of 68 types of commercial and traditional Slovak cheeses were analyzed to investigate the occurrence of fungal metabolites. Altogether, 13 fungal metabolites were identified and quantified. Aflatoxin M1, the only mycotoxin regulated in milk and dairy products, was not detected in any case. However, the presence of metabolites that have never been reported in cheeses, such as tryptophol at a maximum concentration level from 13.4 to 7930 µg/kg (average: 490 µg/kg), was recorded. Out of all detected metabolites, enniatin B represents the most frequently detected mycotoxin (0.06–0.71 µg/kg) in the analyzed samples. Attention is drawn to the lack of data on mycotoxins’ origin from Slovak cheeses; in fact, this is the first reported investigation. Our results indicate the presence of fungal mycotoxin contamination for which maximum permissible levels are not established, highlighting the importance of monitoring the source and producers of contamination in order to protect consumers’ health

Detection of Endophyte Mycotoxins by Service Laboratories: Providing Answers for Safe Feed

. A global network of service laboratories exists to test livestock feed materials (typically grass hay and pellets) for ergovaline, ergot alkaloids and lolitrem B to ensure ‘safe feeds’ are being given to livestock. These compounds are mycotoxins produced by endophytic fungi that naturally reside in feed material. They have been purposely bred into grass species, as they enhance the plant’s survival from drought and insect predation. Unfortunately, ergovaline and other ergot alkaloids also cause vasoconstrictive effects and reproductive difficulties in livestock, resulting in a $1 million annual loss in production for the cattle industry in the USA alone. Lolitrem B is a neurotoxicant that causes a syndrome known as ‘ryegrass staggers,’ which involves a tremoring response in the animal. Clients of these service laboratories include hay farmers who want to be confident that the product they are selling is safe to feed to livestock; veterinarians who are trying to rule out causes of disease in clinical cases; individuals wanting to check personal feed sources; and researchers investigating innovative solutions to these feed contaminants. Each year, approximately 33,000 containers of hay are shipped overseas from the USA, including Pacific Rim and Middle Eastern countries, bringing in an estimated$130 million annually. If the importing country requires it, the material in these containers must be tested for the appropriate mycotoxin(s) and have a certificate stating that the level found was below the established threshold of toxicity. Discussion of sample submission, analysis and result receipt will be compared amongst international laboratories known to perform analyses for these mycotoxins

Fungal diversity and metabolomic profiles in GM and isogenic non-GM maize cultivars from Brazil

The Author(s) 2020. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. To view a copy of this licence, http://creativecommons.org/licenses/by/4.0/.There is little knowledge of the microbial diversity, mycotoxins and associated secondary metabolites in GM maize and isogenic non-GM cultivars (cvs). This study has quantified the microbial populations and dominant fungal genera in 6 cvs of each type representative of herbicide, pesticide or stacked resistance to both. The predominant mycotoxins and targeted metabolomics profiles were also compared between the two sets of cvs. This showed that the overall fungal populations were 8.8 CFUs g−1 maize. The dominant genera, isolated from maize samples, whether surface-sterilised or not, in all maize cvs were Fusarium, followed by Penicillium, Aspergillus and occasionally Cladosporium and Alternaria. The analysis of the targeted metabolomics showed that approx. 29 different metabolites were detected. These were dominated by fumonisins and minor Penicillium spp. metabolites (questiomycin A and rugulovasine A). Interestingly, the range and number of mycotoxins present in the GM cvs were significantly lower than in the non-GM maize samples. This suggests that while the fungal diversity of the two types of maize appeared to be very similar, the major contaminant mycotoxins and range of toxic secondary metabolites were much lower in the GM cvs.Peer reviewedFinal Published versio

Rapid, simple and cost-effective molecular method to differentiate the temperature sensitive (ts+) MS-H vaccine strain and wild-type Mycoplasma synoviae isolates

Mycoplasma synoviae infection in chickens and turkeys can cause respiratory disease, infectious synovitis and eggshell apex abnormality; thus it is an economically important pathogen. Control of M . synoviae infection comprises eradication, medication or vaccina- tion. The differentiation of the temperature sensitive (ts + ) MS-H vaccine strain from field iso- lates is crucial during vaccination programs. Melt-curve and agarose gel based mismatch amplification mutation assays (MAMA) are provided in the present study to distinguish between the ts + MS-H vaccine strain, its non-temperature sensitive re-isolates and wild- type M . synoviae isolates based on the single nucleotide polymorphisms at nt367 and nt629 of the obg gene. The two melt-MAMAs and the two agarose-MAMAs clearly distinguish the ts + MS-H vaccine strain genotype from its non-temperature sensitive re-isolate genotype and wild-type M . synoviae isolate genotype, and no cross-reactions with other Mycoplasma species infecting birds occur. The sensitivity of the melt-MAMAs and agarose-MAMAs was 10 3 and 10 4 copy numbers, respectively. The assays can be performed directly on clinical samples and they can be run simultaneously at the same annealing temperature. The assays can be performed in laboratories with limited facilities, using basic real-time PCR machine or conventional thermocycler coupled with agarose gel electrophoresis. The advantages of the described assays compared with previously used methods are simplicity, sufficient sensitivity, time and cost effectiveness and specificity

A closed expression for the UV-divergent parts of one-loop tensor integrals in dimensional regularization

Starting from the general definition of a one-loop tensor N-point function, we use its Feynman parametrization to calculate the UV-divergent part of an arbitrary tensor coefficient in the framework of dimensional regularization. In contrast to existing recursion schemes, we are able to present a general analytic result in closed form that enables direct determination of the UV-divergent part of any one-loop tensor N-point coefficient independent from UV-divergent parts of other one-loop tensor N-point coefficients. Simplified formulas and explicit expressions are presented for A-, B-, C-, D-, E-, and F-functions.Comment: 19 pages (single column), the result of previous versions is further evaluated leading to a closed analytic expression for the UV-divergent part of an arbitrary one-loop tensor coefficient, title is modified accordingly, a sign error in the appendix (C_{00000000}) has been corrected, a mathematica notebook containing an implementation of the newly derived formula is attache

Cultivation area affects the presence of fungal communities and secondary metabolites in Italian durum wheat grains

In this study, durum wheat kernels harvested in three climatically different Italian cultivation areas (Emilia Romagna, Umbria and Sardinia) in 2015, were analyzed with a combination of different isolation methods to determine their fungal communities, with a focus on Fusarium head blight (FHB) complex composition, and to detect fungal secondary metabolites in the grains. The genus Alternaria was the main component of durum wheat mycobiota in all investigated regions, with the Central Italian cultivation area showing the highest incidence of this fungal genus and of its secondary metabolites. Fusarium was the second most prevalent genus of the fungal community in all cultivation environments, even if regional differences in species composition were detected. In particular, Northern areas showed the highest Fusarium incidence, followed by Central and then Southern cultivation areas. Focusing on the FHB complex, a predominance of Fusarium poae, in particular in Northern and Central cultivation areas, was found. Fusarium graminearum, in the analyzed year, was mainly detected in Emilia Romagna. Because of the highest Fusarium incidence, durum wheat harvested in the Northern cultivation area showed the highest presence of Fusarium secondary metabolites. These results show that durum wheat cultivated in Northern Italy may be subject to a higher FHB infection risk and to Fusarium mycotoxins accumulation