Limited enzymatic hydrolysis can improve the interfacial and foaming characteristics of beta-conglycinin

In this contribution, we have determined the effect of limited enzymatic hydrolysis on the interfacial (dynamics of adsorption and surface dilatational properties) and foaming (foam formation and stabilization) characteristics of a soy globulin (beta-conglycinin, fraction 7S). The degree of hydrolysis (DH = 0, 2, and 5%), the pH of the aqueous solution (pH = 5 and 7), and the protein concentration in solution (at 0.1, 0.5, and 1 wt %) were the variables studied. The temperature and the ionic strength were maintained constant at 20 degrees C and 0.05 M, respectively. The rate of adsorption and surface dilatational properties (surface dilatational modulus, E, and loss angle) of beta-conglycinin at the air-water interface depend on the pH and DH. The adsorption decreased drastically at pH 5.0, close to the isoelectric point of beta-conglycinin, because of the existence of a lag period and a low rate of diffusion. The interfacial characteristics of beta-conglycinin are much improved by enzymatic treatment, especially in the case of acidic aqueous solutions. Hydrolysates with a low DH have improved functional properties (mainly foaming capacity and foam stability), especially at pH values close to the isoelectric point (pI), because the protein is more difficult to convert into a film at fluid interfaces at pH approximately equal to pI.     

Identification of sole (Solea solea) and Greenland halibut (Reinhardtius hippoglossoides) by PCR amplification of the 5S rDNA gene.

Polymerase chain reaction (PCR) amplification of the nuclear 5S rDNA gene, has been used for the identification of sole (Solea solea) and Greenland halibut (Reinhardtius hippoglossoides). Two species-specific primers were designed to amplify specific fragments of the 5S rDNA gene in each species. The remarkably different size of the amplicons obtained gives, by simple agarose gel electrophoresis, two distinguishable band patterns for both flatfish species. This genetic marker can be very useful for the accurate identification of S. solea and Greenland halibut, to enforce labeling regulations.     

In vitro shoot regeneration from immature seeds of Epimedium alpinum induced by thidiazuron and CPPU

In vitro propagation of Epimedium alpinum L. was carried out using immature seed explants. The effects of various concentrations of thidiazuron (TDZ) and 1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU), on the induction of organogenic callus, were evaluated. Organogenesis occurred most efficiently when explants were transiently exposed (48 h) to 20 μM CPPU or 80 μM TDZ followed by culture on hormone-free woody-plant medium (WPM). Organogenic callus consisting of white, compact clumps of tissue proliferated slowly on hormone-free WPM. To promote adventitious shoot induction, the effects of different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzyladenine (BA) were investigated. The highest per cent shoot regeneration, 66.7% of explants, and the maximum mean number of shoots, 2.6 per explant, were obtained on WPM containing 1.1 μM 2,4-D and 22 μM BA. Shoots were rooted on hormone-free WPM and well-developed plantlets were successfully transferred to soil.     

Ontogeny of the digestive tract of thick lipped grey mullet (Chelon labrosus) larvae reared in “mesocosms”

This work describes the ontogeny of the digestive tract in thick lipped grey mullet (Chelon labrosus) larvae reared until day 36 post-hatching with the semi-extensive technology in mesocosms. Diet was constituted by live preys, rotifers, Artemia and wild zooplankton, then compound diet was added from day 20 (p. h.). Linear growth, weight growth and digestive enzymes specific activities were studied during larval ontogeny. Pancreatic enzymes (trypsin and amylase) and intestinal enzymes (leucine-alanine peptidase “Leu-ala”, aminopeptidase N “AN” and alkaline phosphatase “AP”) were assayed in larvae sampled throughout the rearing trial to evaluate gastrointestinal maturation along the development.The trypsin specific activities were very high during the first two weeks and then declined as observed in marine fish species. A following increase in trypsin specific activity from day 20 was attributed notably to ingestion of particle compound diet. In contrast to the pattern generally described in fish larvae, amylase specific activity showed a continuous increase. This could be attributed to the fact that C. labrosus is an omnivorous species and suggests that the fish might be able to use efficiently diets containing higher levels of starch or other carbohydrates since the end of larval development.Relative expression of intestinal brush border membrane enzymes (AP and AN) and cytosolic enzyme (Leu-ala), showed an abrupt increase of both AP/leu-ala and AN/leu-ala ratios at day 8 (p. h.), indicating that maturation of intestinal tract in C. labrosus larvae is particularly precocious. It is assumed that larvae of C. labrosus might support early co-feeding and weaning strategies, which could reasonably be initiated since mouth opening.     

Soil properties and habitats determine the response of bacterial communities to agricultural wastewater irrigation

Increasing temperatures and variability of precipitation events due to climate change will lead in the future to higher irrigation demands in agroecosystems.However,the use of secondary treated wasterwater(TWW)could have consequences for the receiving soil environment and its resident microbial communities.The objective of this study was to characterize the importance of soil properties and habitats to the response of soil bacteria and archaea to irrigation with TWW.Two agricultural soils with contrasting textures(loamy sand or silt loam)and,for each,three variants differing in soil organic carbon and nitrogen,as generated by long-term fertilization,were analyzed.For each of these six soils,prokaryotic communities from two habitats,i.e.,root-free bulk soil and the rhizosphere of developing cucumber plants in the greenhouse,were characterized.Communities were analyzed by the quantity and diversity of their polymerase chain reaction(PCR)-amplified 16S rRNA genes.To account for TWW-associated nutrient effects,potable water(PW)served as a control.Amplicon sequence analysis showed that prokaryotic communities mainly consisted of bacteria(99.8%).Upon irrigation,regardless of the water quality,prokaryotic diversity declined,p H increased,and no bacterial growth was detected in bulk soil.In contrast,the growth of cucumbers was stimulated by TWW,indicating that plants were the main beneficiaries.Moreover,strong responses were seen in the rhizosphere,suggesting an indirect effect of TWW by altered rhizodepositions.The main bacterial responders to TWW were Proteobacteria,Bacteroidetes,Actinobacteria,and Planctomycetes.Changes in bacterial communities due to TWW were less pronounced in all variants of the silt loam,indicating the importance of clay and soil organic carbon for buffering effects of TWW on soil bacterial communities.Hence,soil organic carbon and soil texture are important parameters that need to be considered when applying TWW in agriculture.     

Lycopene degradation and isomerization kinetics during thermal processing of an olive oil/tomato emulsion

The stability of lycopene in an olive oil/tomato emulsion during thermal processing (80-140 °C) was studied. Initially, the degradation of total lycopene (all-E plus Z-forms) occurred quickly at temperatures above 100 °C. However, a nonzero plateau value, depending on the processing temperature, was attained after longer treatment times. Besides degradation, the isomerization of total-Z-lycopene as well as the individual isomerization of all-E-, 5-Z-, 9-Z-, and 13-Z-lycopene was studied in detail. After prolonged heating, the isomer conversion reached a temperature-dependent equilibrium state. The degradation of total lycopene and the isomerization could be described by a fractional conversion model. The temperature dependency of the corresponding reaction rate constants was quantified by the Arrhenius equation. The activation energy of degradation was estimated to be 28 kJ/mol, and the activation energy of overall (all-E and total-Z) isomerization was estimated to be 52 kJ/mol.     

Formulation engineering can improve the interfacial and foaming properties of soy globulins

In this contribution, we have analyzed the effect of different strategies, such as change of pH (5 or 7) or ionic strength (at 0.05 and 0.5 M), and addition of sucrose (at 1 M) and Tween 20 (at 1 x 10(-4) M) on interfacial characteristics (adsorption, structure, dynamics of adsorption, and surface dilatational properties) and foam properties (foam capacity and stability) of soy globulins (7S and 11S at 0.1 wt %). We have observed that (1) the adsorption (presence of a lag period, diffusion, and penetration at the air-water interface) of soy globulins depends on the modification in the 11S/7S ratio and on the level of association/dissociation of these proteins by varying the pH and ionic strength (I), the effect of sucrose on the unfolding of the protein, and the competitive adsorption between protein and Tween 20 in the aqueous phase. The rate of adsorption increases at pH 7, at high ionic strength, and in the presence of sucrose. (2) The surface dilatational properties reflect the fact that soy globulin adsorbed films exhibit viscoelastic behavior but do not have the capacity to form a gel-like elastic film. The surface dilatational modulus increases at pH 7 and at high ionic strength but decreases with the addition of sucrose or Tween 20 into the aqueous phase. (3) The rate of adsorption and surface dilatational properties (surface dilatational modulus and phase angle) during adsorption at the air-water interface plays an important role in the formation of foams generated from aqueous solutions of soy globulins. However, the dynamic surface pressure and dilatational modulus are not enough to explain the stability of the foam.     

A programmable dual-RNA-guided DNA endonuclease in adaptive bacterial immunity

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems provide bacteria and archaea with adaptive immunity against viruses and plasmids by using CRISPR RNAs (crRNAs) to guide the silencing of invading nucleic acids. We show here that in a subset of these systems, the mature crRNA that is base-paired to trans-activating crRNA (tracrRNA) forms a two-RNA structure that directs the CRISPR-associated protein Cas9 to introduce double-stranded (ds) breaks in target DNA. At sites complementary to the crRNA-guide sequence, the Cas9 HNH nuclease domain cleaves the complementary strand, whereas the Cas9 RuvC-like domain cleaves the noncomplementary strand. The dual-tracrRNA:crRNA, when engineered as a single RNA chimera, also directs sequence-specific Cas9 dsDNA cleavage. Our study reveals a family of endonucleases that use dual-RNAs for site-specific DNA cleavage and highlights the potential to exploit the system for RNA-programmable genome editing.     

QTL analysis of main and epistatic effects for flour color traits in durum wheat

The aim of this work was to map quantitative trait loci (QTLs) associated with flour yellow color (Fb*) and yellow pigment content (YPC) in durum wheat (Triticum turgidum L. var. durum). Additionally, QTLs affecting flour redness (Fa*) and brightness (FL*) color parameters were investigated. A population of 93 RILs (UC1113 × Kofa) was evaluated in three locations of Argentina over 2 years. High heritability values (>94%) were obtained for Fb* and YPC, whereas FL* and Fa* showed intermediate to high values. The main QTLs affecting Fb* and YPC overlapped on chromosome arms 4AL (4AL.2), 6AL (6AL.2), 7AS, 7AL, 7BS (7BS.2) and 7BL (7BL.2). The 7BL.1 QTL included the Psy-B1 locus, but one additional linked QTL was detected. A novel minor QTL located on 7AS affected Fb*, with an epistatic effect on YPC. An epistatic interaction occurred between the 7AL and 7BL.2 QTLs. The 4AL.2 QTL showed a strong effect on Fb* and was involved in two digenic epistatic interactions. The 6AL.2 QTL explained most of the variation for Fb* and YPC. The main QTLs affecting FL* and Fa* were located on 2BS and 7BL, respectively. These results confirm the complex inheritance of flour color traits and open the possibility of developing perfect markers to improve pasta quality in Argentinean breeding programs.     

Combination of TLC and HPLC-MS/MS methods. Approach to a rational quality control of Chinese star anise

In this study, a methodological approach for an effective and reliable quality control of Chinese star anise (Illicium verum Hook. F.) is developed and validated. A combined method of TLC and HPLC-MS/MS was used for differentiation of various Illicium species, especially Chinese and Japanese star anise. Species can be distinguished by their TLC flavonoid pattern. A sensitive and selective HPLC/ESI-MS/MS method was developed for the detection and quantification of lower admixtures of I. anisatum and of further toxic Illicium species at a low concentration range using the sesquiterpene lactone anisatin as a marker. The proposed assay includes a solid-phase extraction cleanup procedure with a high recovery (>90%). Chromatographic separation of anisatin was carried out on a C18 column, followed by MS detection using ESI in negative mode. The precursor/product ion transitions m/z 327 --> 127 (quantifier) and m/z 327 --> 297 (qualifier) were monitored. Statistical evaluation of this multireaction-monitoring procedure reveals good linearity and intra- and interday precision. The limits of detection and quantification are 1.2 and 3.9 microg/kg, respectively.