Encapsulation of Bixin with High Amylose Starch as Affected by Temperature and Whey Protein

Microencapsulation of bixin using high-amylose corn starch was carried out by the acidification method. Bixin powders were characterized by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), FT-IR spectrometry, color parameters, encapsulation efficiency, bixin release profile. In addition, the effect of whey protein (WP) on the microencapsulation process was investigated. The results obtained from DSC, X-ray diffraction and FT-IR spectrometry indicated that only in the samples prepared at 90 °C (B0WP90°C, B10WP90°C, and B20WP90°C) there was formation of crystalline structures, with melting temperatures at 117.2°, 105° and 104 °C, respectively. The possible interactions between bixin, WP and amylose starch are also discussed.     

Spontaneous sister chromatid exchange and chromosome aberration frequency in humans: the familial effect.

The possible effects of environmental and genetic factors on spontaneous frequencies of sister chromatid exchanges (SCEs) and cells with chromosome aberrations (CAs) in human lymphocytes were investigated by analysing 177 completed families (mother, father and at least one child). After removing the effects of methodological, biological and life-style factors by the use of multifactor analysis of variance (MANOVA), SCEs and CAs residuals were analysed by simple correlation analysis and principal component analysis. SCEs and CAs inter-familiar variability was higher than that found within families. A significant correlation was found between the average SCE frequencies shared by parents (the so-called 'midpoint parents', or 'midparent') and offspring (linear slope b=0.26+/-0.07, p<0.05), but also between mother and father (b=0.23+/-0.11, p<0.05) suggesting the presence of an effective environmental factor. The midparent-offspring correlation was found to be sustained by the mother-offspring relationship (b=0.28+/-0.08, p<0.05), being the father-offspring correlation not significant (b=0.16+/-0.11, p0.05). Concerning CAs, no statistically significant correlation between parents was found, but the strong relationship between mother and offspring was confirmed (b=0.468+/-0.11, p<0.001). The SCEs correlation between mother vs. offspring disappeared for older offspring (over 23 years old). The obtained findings strongly showed that the genetic make-up is barely detectable in the presence of domestic environment factors which are shown to play the major role in determining the interfamilial variability of SCE and CA in a general population. These results strengthen the suitability of the use of SCEs and CAs analysis in human cytogenetic surveillance for the detection of effective environmental factors.     

Coenzyme Q-3 as an antioxidant. Its effect on the composition and structural properties of phospholipid vesicles.

Coenzyme Q-3 incorporated into the lipid bilayer at physiological concentration provided an 80% inhibition of the lipid peroxidation induced by ferrous ions. In coenzyme Q-containing vesicles, the fluorescence lifetime and the fluorescence anisotropy decay of the probe, 1,6-diphenyl-1,3,5-hexatriene, were measured in order to find out if the presence of the quinone can cause variations in the membrane organization. Our data show that two distinct populations of the probe were present and that both populations were available to quenching by coenzyme Q. The overall effects of coenzyme Q on the static and dynamic properties of the model membranes were: a very small effect in the ordering of the fatty acid chain, and a more noticeable decrease of the probe correlation time and, therefore, an increase in membrane fluidity at increasing quinone concentration. When vesicles were peroxidized in the absence of the coenzyme Q, the fluidity markedly decreased; in its presence, the fluidity was nearly unchanged. The results suggest that the antioxidant properties of coenzyme Q can be ascribed to its ability to react with free radicals. The effect on the fluidity of the lipid bilayer might imply that a requisite for a molecule to act as an efficient antioxidant could be its ability to readily diffuse within the membrane.     

Incorporation of ubiquinones into lipid vesicles and inhibition of lipid peroxidation

Ubiquinone incorporation into vesicles to evaluate its antioxidative effect on lipid peroxidation has been studied. Only sonication and not vortication allows comparable incorporation patterns of the various ubiquinone homologues into lipid vesicles. The measure of malondialdehyde, a convenient index for determining the extent of autoxidation, shows that both the naturally occurring homologues and synthetic shorter-chain ones, also in the oxidized form, possess similar antioxidant efficiency.     

The Tat system of Gram-positive bacteria

The twin-arginine protein translocation (Tat) system has a unique ability to translocate folded and co-factor-containing proteins across lipid bilayers. The Tat pathway is present in bacteria, archaea and in the thylakoid membranes of chloroplasts and, depending on the organism and environmental conditions, it can be deemed important for cell survival, virulence or bioproduction. This review provides an overview of the current understanding of the Tat system with specific focus on Gram-positive bacteria. The ‘universal minimal Tat system’ is composed of a TatA and a TatC protein. However, this pathway is more commonly composed of two TatA-like proteins and one TatC protein. Often the TatA-like proteins have diverged to have two different functions and, in this case, the second TatA-like protein is usually referred to as TatB. The correct folding and/or incorporation of co-factors are requirements for translocation, and the known quality control mechanisms are examined in this review. A number of examples of crosstalk between the Tat system and other protein transport systems, such as the Sec–YidC translocon and signal peptidases or sheddases are also discussed. Further, an overview of specific Gram-positive bacterial Tat systems found in monoderm and diderm species is detailed. Altogether, this review highlights the unique features of Gram-positive bacterial Tat systems and pinpoints key questions that remain to be addressed in future research. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.     

Comparison between responses to gametophytic and sporophytic recurrent selection in maize (Zea mays L.)

Summary Experiments were conducted to determine the chromosomal location of the gene conditioning overproduction of a methionine-rich, 10-K zein in maize kernels of line BSSS53. In addition, the chromosomal location of the structural gene encoding the overproduced protein was determined. Whereas the structural gene, designated Zps10/(22), was found to be located on the long arm of chromosome 9 near the centromere, the locus regulating overproduction of the zein protein was mapped to the short arm of chromosome 4. This regulatory gene has been designated Zpr10/(22). Regulation of 10-K zein production by Zpr10/(22) is, therefore, via a trans-acting mechanism.