Intracellular localization of dietary and naked DNA in intestinal tissue of Atlantic salmon, Salmo salar L. using in situ hybridization

There is a continuing interest in the fate of DNA from genetically modified organisms (GMO) in the food chain including the uptake of DNA by intestinal cells from dietary sources containing GM feed ingredients. The objective of this study was to elucidate the uptake and persistence of foreign DNA in the intestinal tract of Atlantic salmon Salmo salar L. using in situ hybridization (ISH) that enables the intracellular localization of the DNA, and polymerase chain reaction (PCR) to verify the ISH results qualitatively. Two salmon intestinal models were employed for the investigations; intestinal tissues were sampled in two models namely (a) in vivo from salmon-fed diets containing 30% GM soybeans or 30% nonGM (nGM) soybeans, and (b) ex vivo from intestinal sleeves incubated using different concentrations of PCR-amplified test DNAs (211 and 305 bp) designed from the 35S promoter/plant DNA junction of the RoundupReady soybean (RRS) genome. Additionally, for the incubation study, the effect of a mucolytic agent dithiothreitol (DTT) and a permeability enhancer sodium deoxycholate (SDA) on DNA uptake were investigated. Both treatments were found to enhance DNA uptake ex vivo. Dietary DNA and PCR-amplified DNA could be visualized by ISH in the salmon intestine with more frequently observed signals in the ex vivo model compared to the in vivo model. All results could be verified by PCR. Dietary DNA was localized in the cell vacuolar system and in lamina propria of the mid intestine. Thus, based on the investigated DNA fragment lengths, this study shows that foreign DNA, can be taken up by Atlantic salmon intestinal tissue.     

Production of three anti-listerial peptides by Lactobacillus curvatus in MRS broth

Three novel bioactive peptides (BAP1–3) from Lactobacillus curvatus CWBI-B28 were isolated and purified using de Man, Rogosa and Sharp (MRS) broth by a three-step protein purification protocol including ammonium sulfate precipitation, hydrophobic C₁₈ Sep-Pak column and reverse-phase high performance liquid chromatography (RP-HPLC). This procedure allowed the recovery of chromatographically pure antimicrobial peptides with the yields of 19%, 10% and 15% of BAP1, BAP2 and BAP3, respectively. The respective apparent molecular masses as determined by tricine-SDS-polyacrilamide gel electrophoresis were 6365, 3426 and 3496. N-terminal amino acid sequencing of the BAPs and comparison of their sequences with those of international data bases indicated that BAP1 is more likely to be a casein-derived bioactive protein produced upon hydrolysis of the tryptone present in MRS broth by Lb. curvatus CWBI-B28 during active growth. However, the identity of BAP2 and BAP3 could not be determined with certainty; yet, they would be novel bacteriocins not fitting in any of the known classes of bacteriocins. Therefore, this strain would have the ability to produce intrinsic antimicrobial substances and also release bioprotective peptides from milk-proteins upon cultivation in milk or casein-containing food products due to its proteolytic activity. Thus, Lb. curratus CWBI-B28 possesses a good potential to be used in food preservation and safety.     

Biotransformation of hop derived compounds by Brettanomyces yeast strains

Several hop derived compounds in wort are known to be converted by yeast during fermentation, influencing the overall perception of the beer. A deeper understanding of such metabolic processes during fermentation is needed to achieve better control of the outcome. Here, the interaction between hop derived compounds and the yeast genera Brettanomyces was studied. Several Brettanomyces strains with different genomic backgrounds were selected, focusing on two traits: beta-glucosidase activity and nitrate assimilation. The role of three beta-glucosidases present in Brettanomyces bruxellensis and Brettanomyces anomalus and their impact on the final monoterpene alcohol profile was analysed. The beta-glucosidase activity was highly strain dependent, with B. anomalus CRL-49 exhibiting the highest conversion. Such activity could not be related to the release of aglycones from hops during fermentation, as a substantial part of such activity was intracellular. Nevertheless, the reduction of geraniol to β-citronellol was remarkably efficient for all Brettanomyces strains during fermentation, and it is suggested that two oxidoreductases BbHye2 and BbHye3 may have an influence. Moreover, the transfer of nitrate from hops to wort and its further assimilation by Brettanomyces species was analysed. The amount of nitrate in wort proved to be linearly proportional to the contact time of the hops with the wort. The level of nitrate assimilation by yeast was shown to be dependent on the nitrate assimilation cluster (YNR, YNI, YNT). Hence, the desired yeast strains may be selected according to the genetic make-up. © 2020 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling     

Expert system driven software

Using large finite element analysis codes for heat transfer computations and for stresses and displacements under thermal loads computations is not always very simple because of the complexity of the problems and the number of domains involved. Often faulty results from computations are being used until an expert discovers that something was wrong in the simulation. As a result of recent advances in Artificial Intelligence techniques, solutions to these problems are now possible by making use of Knowledge Based Systems in which expertise in several domains can easily be introduced. In this paper, we present an application of knowledge based systems for a finite element analysis code in Heat Transfer. The system is fairly general, and we think that application to any well structured numerical code should be straightforward.     

The complete sequence of a 6794 bp segment located on the right arm of chromosome II of Saccharomyces cerevisiae. Finding of a putative dUTPase in a yeast

The DNA sequence of a 6794 bp fragment located at about 100 kb from the right telomere of chromosome II from Saccharomyces cerevisiae has been determined. Sequence analysis reveals five open reading frames. One is the ARO4 gene encoding the 3-deoxy-D -arabinoheptulosonate 7-phosphate synthase. Another presents strong homology with the S5 ribosomal protein from bacteria. The open reading frame YBR1705 shows significant homology with dUTPase, suggesting for the first time the existence of such an enzyme in S. cerevisiae.     

Responses of plant-parasitic nematodeMeloidogyne incognita to carbon dioxide determined by video camera-computer tracking

A computer tracking system was used to quantify the responses of infective second-stage juveniles of the plant-parasitic nematodeMeloidogyne incognita to carbon dioxide. A sudden increase in concentration caused an increase in the rate of locomotion and a decrease in the frequency of changes of direction. The threshold was about 0.01 % vol CO₂/vol gas when the baseline concentration was very low and 0.05% CO₂ when the baseline concentration was 1% CO₂. The latter value represents a relative change of 5%. Concentrations above 10% CO₂ caused a general decrease in movement. In a second type of experiment, a constant concentration gradient of CO₂ was established, and the net movement of the nematodes along the gradient was determined. At low concentrations, the threshold was about 0.02% CO₂/cm. At higher concentrations, the threshold gradient was below 0.01% CO₂/cm or a relative gradient of less than 1% change/cm. At all concentrations to which nematodes responded they were attracted. The degree of orientation was estimated to be approximately 10% under most conditions. The rate of migration under the most favorable conditions was about 0.7 cm/hr. Three possible functions of the response are discussed: attraction to roots, movement toward optimal depth in soil, and as a collimating stimulus.     

Thermal instability with radiation by the method of energy

Energy-stability theory is applied to the case of radiation heat transfer in an optically thin, quiescent fluid layer heated from below and bounded by rigid, black, perfectly conducting planes. The radiation term in the energy equation destroys the quadratic character of the energy identity. It is shown, however, that the right-hand side of the energy identity can be bounded by a suitable quadratic term for all physically allowable disturbances. The result is a conditional stability limit dependent upon disturbance amplitude. Results are computed for a variety of cases; these are compared to existing linear and energy stability results.