Integrative physiology and transcriptome reveal salt-tolerance differences between two licorice species: Ion transport, Casparian strip formation and flavonoids biosynthesis.

BACKGROUND: Glycyrrhiza inflata Bat. and Glycyrrhiza uralensis Fisch. are both original plants of 'Gan Cao' in the Chinese Pharmacopoeia, and G. uralensis is currently the mainstream variety of licorice and has a long history of use in traditional Chinese medicine. Both of these species have shown some degree of tolerance to salinity, G. inflata exhibits higher salt tolerance than G. uralensis and can grow on saline meadow soils and crusty saline soils. However, the regulatory mechanism responsible for the differences in salt tolerance between different licorice species is unclear. Due to land area-related limitations, the excavation and cultivation of licorice varieties in saline-alkaline areas that both exhibit tolerance to salt and contain highly efficient active substances are needed. The systematic identification of the key genes and pathways associated with the differences in salt tolerance between these two licorice species will be beneficial for cultivating high-quality salt-tolerant licorice G. uralensis plant varieties and for the long-term development of the licorice industry. In this research, the differences in growth response indicators, ion accumulation, and transcription expression between the two licorice species were analyzed. RESULTS: This research included a comprehensive comparison of growth response indicators, including biomass, malondialdehyde (MDA) levels, and total flavonoids content, between two distinct licorice species and an analysis of their ion content and transcriptome expression. In contrast to the result found for G. uralensis, the salt treatment of G. inflata ensured the stable accumulation of biomass and total flavonoids at 0.5 d, 15 d, and 30 d and the restriction of Na+ to the roots while allowing for more K+ and Ca2+ accumulation. Notably, despite the increase in the Na+ concentration in the roots, the MDA concentration remained low. Transcriptome analysis revealed that the regulatory effects of growth and ion transport on the two licorice species were strongly correlated with the following pathways and relevant DEGs: the TCA cycle, the pentose phosphate pathway, and the photosynthetic carbon fixation pathway involved in carbon metabolism; Casparian strip formation (lignin oxidation and translocation, suberin formation) in response to Na+; K+ and Ca2+ translocation, organic solute synthesis (arginine, polyamines, GABA) in response to osmotic stresses; and the biosynthesis of the nonenzymatic antioxidants carotenoids and flavonoids in response to antioxidant stress. Furthermore, the differential expression of the DEGs related to ABA signaling in hormone transduction and the regulation of transcription factors such as the HSF and GRAS families may be associated with the remarkable salt tolerance of G. inflata. CONCLUSION: Compared with G. uralensis, G. inflata exhibits greater salt tolerance, which is primarily attributable to factors related to carbon metabolism, endodermal barrier formation and development, K+ and Ca2+ transport, biosynthesis of carotenoids and flavonoids, and regulation of signal transduction pathways and salt-responsive transcription factors. The formation of the Casparian strip, especially the transport and oxidation of lignin precursors, is likely the primary reason for the markedly higher amount of Na+ in the roots of G. inflata than in those of G. uralensis. The tendency of G. inflata to maintain low MDA levels in its roots under such conditions is closely related to the biosynthesis of flavonoids and carotenoids and the maintenance of the osmotic balance in roots by the absorption of more K+ and Ca2+ to meet growth needs. These findings may provide new insights for developing and cultivating G. uralensis plant species selected for cultivation in saline environments or soils managed through agronomic practices that involve the use of water with a high salt content.

Carotenoid Extraction from Plant Tissues.

Carotenoids are the natural pigments available in nature and exhibit different colors such as yellow, red, and orange. These are a class of phytonutrients that have anti-cancer, anti-inflammatory, anti-oxidant, immune-modulatory, and anti-aging properties. These were used in food, pharmaceutical, nutraceutical, and cosmetic industries. They are divided into two classes: carotenes and xanthophylls. The carotenes are non-oxygenated derivatives and xanthophylls are oxygenated derivatives. The major source of carotenoids are vegetables, fruits, and tissues. Carotenoids also perform the roles of photoprotection and photosynthesis. In addition to the roles mentioned above, they are also involved and act as precursor molecules for the biosynthesis of phytohormones such as strigolactone and abscisic acid. This chapter briefly introduces carotenoids and their extraction method from plant tissue. Proposed protocol describes the extraction of carotenoid using solvents chloroform and dichloromethane. Reverse-phase HPLC can be performed with C30 columns using gradient elution. The column C30 is preferred to the C18 column because the C30 column has salient features, which include selective nature in the separation of structural isomers and hydrophobic, long-chain compounds, and shows the best compatibility with highly aqueous mobile phases. A complete pipeline for the extraction of carotenoids from plant tissue is given in the present protocol.

Outdoor cultivation and metabolomics exploration of Chlamydomonas engineered for bisabolene production.

Demonstrating outdoor cultivation of engineered microalgae at considerable scales is essential for their prospective large-scale deployment. Hence, this study focuses on the outdoor cultivation of an engineered Chlamydomonas reinhardtii strain, 3XAgBs-SQs, for bisabolene production under natural dynamic conditions of light and temperature. Our preliminary outdoor experiments showed improved growth, but frequent culture collapses in conventional Tris-acetate-phosphate medium. In contrast, modified high-salt medium (HSM) supported prolonged cell survival, outdoor. However, their subsequent outdoor scale-up from 250 mL to 5 L in HSM was effective with 10 g/L bicarbonate supplementation. Pulse amplitude modulation fluorometry and metabolomic analysis further validated their improved photosynthesis and uncompromised metabolic fluxes towards the biomass and the products (natural carotenoids and engineered bisabolene). These strains could produce 906 mg/L bisabolene and 54 mg/L carotenoids, demonstrating the first successful outdoor photoautotrophic cultivation of engineeredC. reinhardtii,establishing it as a one-cell two-wells biorefinery.

Plant age-dependent dynamics of annatto pigment (bixin) biosynthesis in Bixa orellana.

Age affects the production of secondary metabolites, but how developmental cues regulate secondary metabolism remains poorly understood. The achiote tree (Bixa orellana L.) is a source of bixin, an apocarotenoid used in diverse industries worldwide. Understanding how age-dependent mechanisms control bixin biosynthesis is of great interest for plant biology and for economic reasons. Here we overexpressed miRNA156 (miR156) in B. orellana to comprehensively study the effects of the miR156-SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) module on age-dependent bixin biosynthesis in leaves. Overexpression of miR156 in annatto plants (miR156ox) reduced BoSPL transcript levels, impacted leaf ontogeny, lessened bixin production, and increased abscisic acid levels. Modulation of expression of BoCCD4-4 and BoCCD1, key genes in carotenoid biosynthesis, was associated with diverting the carbon flux from bixin to abscisic acid in miR156ox leaves. Proteomic analyses revealed an overall low accumulation of most secondary metabolite-related enzymes in miR156ox leaves, suggesting that miR156-targeted BoSPLs may be required to activate several secondary metabolic pathways. Our findings suggest that the conserved BomiR156-BoSPL module is deployed to regulate leaf dynamics of bixin biosynthesis, and may create novel opportunities to fine-tune bixin output in B. orellana breeding programs.

Optimization and Characterization of Spirulina and Chlorella Hydrolysates for Industrial Application.

Chlorella and Spirulina are the most used microalgae mainly as powder, tablets, or capsules. However, the recent change in lifestyle of modern society encouraged the emergence of liquid food supplements. The current work evaluated the efficiency of several hydrolysis methods (ultrasound-assisted hydrolysis UAH, acid hydrolysis AH, autoclave-assisted hydrolysis AAH, and enzymatic hydrolysis EH) in order to develop liquid dietary supplements from Chlorella and Spirulina biomasses. Results showed that, EH gave the highest proteins content (78% and 31% for Spirulina and Chlorella, respectively) and also increased pigments content (4.5 mg/mL of phycocyanin and 12 µg/mL of carotenoids). Hydrolysates obtained with EH showed the highest scavenging activity (95-91%), allowing us, with the other above features, to propose this method as convenient for liquid food supplements development. Nevertheless, it has been shown that the choice of hydrolysis method depended on the vocation of the product to be prepared.

Carotenoids in familial hypobetalipoproteinemia disorders: Malabsorption in Caco2 cell models and severe deficiency in patients.

BACKGROUND: Familial hypobetalipoproteinemias (FHBL) are rare genetic diseases characterized by lipid malabsorption. We focused on abetalipoproteinemia (FHBL-SD1) and chylomicron retention disease (FHBL-SD3), caused by mutations in microsomal triglyceride transfer protein (MTTP) and SAR1B genes, respectively. Treatments include a low-fat diet and high-dose fat-soluble vitamin supplementations. However, patients are not supplemented in carotenoids, a group of lipid-soluble pigments essential for eye health. OBJECTIVE: Our aim was to evaluate carotenoid absorption and status in the context of hypobetalipoproteinemia. METHODS: We first used knock-out Caco-2/TC7 cell models of FHBL-SD1 and FHBL-SD3 to evaluate carotenoid absorption. We then characterized FHBL-SD1 and FHBL-SD3 patient status in the main dietary carotenoids and compared it to that of control subjects. RESULTS: In vitro results showed a significant decrease in basolateral secretion of α- and ß-carotene, lutein, and zeaxanthin (-88.8 ± 2.2 % to -95.3 ± 5.8 %, -79.2 ± 4.4 % to -96.1 ± 2.6 %, -91.0 ± 4.5 % to -96.7 ± 0.3 % and -65.4 ± 3.6 % to -96.6 ± 1.9 %, respectively). Carotenoids plasma levels in patients confirmed significant deficiencies, with decreases ranging from -89 % for zeaxanthin to -98 % for α-carotene, compared to control subjects. CONCLUSION: Given the continuous loss in visual function despite fat-soluble vitamin treatment in some patients, carotenoid supplementation may be of clinical utility. Future studies should assess the correlation between carotenoid status and visual function in aging patients and investigate whether carotenoid supplementation could prevent their visual impairment.

A novel micronutrients and methyl jasmonate cocktail of elicitors via seed priming improves drought tolerance by mitigating oxidative stress in rice (Oryza sativa L.).

Drought is a major limiting factor for rice (Oryza sativa L.) production globally, and a cost-effective seed priming technique using bio-elicitors has been found to have stress mitigating effects. Till date, mostly phytohormones have been preferred as bio-elicitors, but the present study is a novel attempt to demonstrate the favorable role of micronutrients-phytohormone cocktail, i.e., iron (Fe), zinc (Zn), and methyl jasmonate (MJ) via seed priming method in mitigating the deleterious impacts of drought stress through physio-biochemical and molecular manifestations. The effect of cocktail/priming was studied on the relative water content, chlorophyll a/b and carotenoid contents, proline content, abscisic acid (ABA) content, and on the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), NADPH oxidase (Nox), and catalase (CAT). The expressions of drought-responsive genes OsZn-SOD, OsFe-SOD, and Nox1 were found to be modulated under drought stress in contrasting rice genotypes -N-22 (Nagina-22, drought-tolerant) and PS-5 (Pusa Sugandh-5, drought-sensitive). A progressive rise in carotenoids (10-19%), ABA (18-50%), proline (60-80%), activities of SOD (27-62%), APX (46-61%), CAT (50-80%), Nox (16-30%), and upregulated (0.9-1.6-fold) expressions of OsZn-SOD, OsFe-SOD, and Nox1 genes were found in the primed plants under drought condition. This cocktail would serve as a potential supplement in modern agricultural practices utilizing seed priming technique to mitigate drought stress-induced oxidative burst in food crops.

Algae Food Products as a Healthcare Solution.

Diseases such as obesity; cardiovascular diseases such as high blood pressure, myocardial infarction and stroke; digestive diseases such as celiac disease; certain types of cancer and osteoporosis are related to food. On the other hand, as the world's population increases, the ability of the current food production system to produce food consistently is at risk. As a result, intensive agriculture has contributed to climate change and a major environmental impact. Research is, therefore, needed to find new sustainable food sources. One of the most promising sources of sustainable food raw materials is macroalgae. Algae are crucial to solving this nutritional deficiency because they are abundant in bioactive substances that have been shown to combat diseases such as hyperglycemia, diabetes, obesity, metabolic disorders, neurodegenerative diseases and cardiovascular diseases. Examples of these substances include polysaccharides such as alginate, fucoidan, agar and carrageenan; proteins such as phycobiliproteins; carotenoids such as ß-carotene and fucoxanthin; phenolic compounds; vitamins and minerals. Seaweed is already considered a nutraceutical food since it has higher protein values than legumes and soy and is, therefore, becoming increasingly common. On the other hand, compounds such as polysaccharides extracted from seaweed are already used in the food industry as thickening agents and stabilizers to improve the quality of the final product and to extend its shelf life; they have also demonstrated antidiabetic effects. Among the other bioactive compounds present in macroalgae, phenolic compounds, pigments, carotenoids and fatty acids stand out due to their different bioactive properties, such as antidiabetics, antimicrobials and antioxidants, which are important in the treatment or control of diseases such as diabetes, cholesterol, hyperglycemia and cardiovascular diseases. That said, there have already been some studies in which macroalgae (red, green and brown) have been incorporated into certain foods, but studies on gluten-free products are still scarce, as only the potential use of macroalgae for this type of product is considered. Considering the aforementioned issues, this review aims to analyze how macroalgae can be incorporated into foods or used as a food supplement, as well as to describe the bioactive compounds they contain, which have beneficial properties for human health. In this way, the potential of macroalgae-based products in eminent diseases, such as celiac disease, or in more common diseases, such as diabetes and cholesterol complications, can be seen.

Multiomics Analysis Reveals the Chemical and Genetic Bases of Pigmented Potato Tuber.

Anthocyanins and carotenoids determine the diversity of potato tuber flesh pigmentation; here, the underlying chemical and genetic bases were elucidated by multiomics analyses. A total of 31 anthocyanins and 30 carotenoids were quantified in five differently pigmented tubers. Cyanidin and pelargonidin derivatives determined the redness, while malvidin, petunidin, and delphinidin derivatives contributed to purpleness. Violaxanthin derivatives determined the light-yellow color, while zeaxanthin and antheraxanthin derivatives further enhanced the deep-yellow deposition. Integrated transcriptome and proteome analyses identified that F3'5'H highly enhanced anthocyanin biosynthesis in purple flesh and was responsible for metabolic divergence between red and purple samples. BCH2 significantly enhanced carotenoid biosynthesis in yellow samples and along with ZEP, NCED1, and CCD1 genes determined metabolic divergence between light and deep-yellow samples. The weighted correlation network analysis constructed a regulatory network revealing the central role of AN1 in regulating anthocyanin biosynthesis, and 10 new transcription factors related to anthocyanin and carotenoid metabolism regulation were identified. Our findings provide targeted genes controlling tuber pigmentation, which will be meaningful for the genetic manipulation of tuber quality improvement.

Determination of the effects of pre-harvest bagging treatment on kiwifruit appearance and quality via transcriptome and metabolome analyses.

Bagging is an effective cultivation strategy to produce attractive and pollution-free kiwifruit. However, the effect and metabolic regulatory mechanism of bagging treatment on kiwifruit quality remain unclear. In this study, transcriptome and metabolome analyses were conducted to determine the regulatory network of the differential metabolites and genes after bagging. Using outer and inner yellow single-layer fruit bags, we found that bagging treatment improved the appearance of kiwifruit, increased the soluble solid content (SSC) and carotenoid and anthocyanin levels, and decreased the chlorophyll levels. We also identified 41 differentially expressed metabolites and 897 differentially expressed genes (DEGs) between the bagged and control 'Hongyang' fruit. Transcriptome and metabolome analyses revealed that the increase in SSC after bagging treatment was mainly due to the increase in D-glucosamine metabolite levels and eight DEGs involved in amino sugar and nucleotide sugar metabolic pathways. A decrease in glutamyl-tRNA reductase may be the main reason for the decrease in chlorophyll. Downregulation of lycopene epsilon cyclase and 9-cis-epoxycarotenoid dioxygenase increased carotenoid levels. Additionally, an increase in the levels of the taxifolin-3'-O-glucoside metabolite, flavonoid 3'-monooxygenase, and some transcription factors led to the increase in anthocyanin levels. This study provides novel insights into the effects of bagging on the appearance and internal quality of kiwifruit and enriches our theoretical knowledge on the regulation of color pigment synthesis in kiwifruit.

Whole-genome resequencing analysis of the medicinal plant Gardenia jasminoides.

Background: Gardenia jasminoides is a species of Chinese medicinal plant, which has high medicinal and economic value and rich genetic diversity, but the study on its genetic diversity is far not enough. Methods: In this study, one wild and one cultivated gardenia materials were resequenced using IlluminaHiSeq sequencing platform and the data were evaluated to understand the genomic characteristics of G. jasminoides. Results: After data analysis, the results showed that clean data of 11.77G, Q30 reached 90.96%. The average comparison rate between the sample and reference genome was 96.08%, the average coverage depth was 15X, and the genome coverage was 85.93%. The SNPs of FD and YP1 were identified, and 3,087,176 and 3,241,416 SNPs were developed, respectively. In addition, SNP non-synonymous mutation, InDel mutation, SV mutation and CNV mutation were also detected between the sample and the reference genome, and KEGG, GO and COG database annotations were made for genes with DNA level variation. The structural gene variation in the biosynthetic pathway of crocin and gardenia, the main medicinal substance of G. jasminoides was further explored, which provided basic data for molecular breeding and genetic diversity of G. jasminoides in the future.

RNA-Seq analysis of the pyloric caecum, liver, and muscle reveals molecular mechanisms regulating fillet color in rainbow trout.

BACKGROUND: The characteristic pink-reddish color in the salmonids fillet is an important, appealing quality trait for consumers and producers. The color results from diet supplementation with carotenoids, which accounts for up to 20-30% of the feed cost. Pigment retention in the muscle is a highly variable phenotype. In this study, we aimed to understand the molecular basis for the variation in fillet color when rainbow trout (Oncorhynchus mykiss) fish families were fed an Astaxanthin-supplemented diet. We used RNA-Seq to study the transcriptome profile in the pyloric caecum, liver, and muscle from fish families with pink-reddish fillet coloration (red) versus those with lighter pale coloration (white). RESULTS: More DEGs were identified in the muscle (5,148) and liver (3,180) than in the pyloric caecum (272). Genes involved in lipid/carotenoid metabolism and transport, ribosomal activities, mitochondrial functions, and stress homeostasis were uniquely enriched in the muscle and liver. For instance, the two beta carotene genes (BCO1 and BCO2) were significantly under-represented in the muscle of the red fillet group favoring more carotenoid retention. Enriched genes in the pyloric caecum were involved in intestinal absorption and transport of carotenoids and lipids. In addition, the analysis revealed the modulation of several genes with immune functions in the pyloric caecum, liver, and muscle. CONCLUSION: The results from this study deepen our understanding of carotenoid dynamics in rainbow trout and can guide us on strategies to improve Astaxanthin retention in the rainbow trout fillet.

Comparison of the effect of various sources of saturated fatty acids on infant follow-on formulas oxidative stability and nutritional profile.

Fortification of infant follow-on formulas (IFF) with docosahexaenoic acid (DHA), which is prone to lipid oxidation, is required by European regulation. This study aimed to identify lipid formulation parameters that improve the nutritional profile and oxidative stability of IFF. Model IFF were formulated using different lipid and emulsifier sources, including refined (POM) or unrefined red palm oil (RPOM), coconut oil (COM), dairy fat (DFOM), soy lecithin, and dairy phospholipids (DPL). After an accelerated storage, RPOM and DFOM with DPL had improved oxidative stability compared to other IFF. Specifically, they had a peroxide value twice lower than POM and 20% less loss of tocopherols for DFOM-DPL. This higher stability was mainly explained by the presence of compounds such as carotenoids in RPOM and sphingomyelin in DFOM-DPL very likely acting synergistically with tocopherols. Incorporation of dairy lipids and carotenoids into DHA-enriched IFF compositions seems promising to enhance their stability and nutritional quality.

Overexpression of potato ORANGE (StOR) and StOR mutant in Arabidopsis confers increased carotenoid accumulation and tolerance to abiotic stress.

ORANGE (OR) plays essential roles in regulating carotenoid homeostasis and enhancing the ability of plants to adapt to environmental stress. However, OR proteins have been functionally characterized in only a few plant species, and little is known about the role of potato OR (StOR). In this study, we characterized the StOR gene in potato (Solanum tuberosum L. cv. Atlantic). StOR is predominantly localized to the chloroplast, and its transcripts are tissue-specifically expressed and significantly induced in response to abiotic stress. Compared with wild type, overexpression of StOR increased ß-carotene levels up to 4.8-fold, whereas overexpression of StORHis with a conserved arginine to histidine substitution promoted ß-carotene accumulation up to 17.6-fold in Arabidopsis thaliana calli. Neither StOR nor StORHis overexpression dramatically affected the transcript levels of carotenoid biosynthetic genes. Furthermore, overexpression of either StOR or StORHis increased abiotic stress tolerance in Arabidopsis, which was associated with higher photosynthetic capacity and antioxidative activity. Taken together, these results indicate that StOR could be exploited as a potential new genetic tool for the improvement of crop nutritional quality and environmental stress tolerance.

Magnesium transporter CsMGT10 of tea plants plays a key role in chlorosis leaf vein greening.

Magnesium (Mg2+), as the central atom of chlorophyll, is the most abundant divalent cation for plant growth and development in living cells. MRS2/MGT magnesium transporters play important roles in coping with magnesium stress, chloroplast development and photosynthesis. However, the molecular mechanism of MGT influencing tea plant leaf vein color remains unknown. Here, we demonstrate that CsMGT10 may be a potential transporter influencing leaf vein color. CsMGT10 belongs to Clade A member of MRS2/MGT family. CsMGT10 has the highest expression level in leaves of tea plants. And it is mainly expressed in aboveground parts, especially in vascular bundles. Moreover, CsMGT10 localizes to the chloroplast envelope of tea plants with a high affinity to Mg2+. And the GMN motif is required for its magnesium transport function. Ectopic expression of CsMGT10 in Arabidopsis leaf variegation mutant var5-1 can restore green color of chlorosis leaf veins, and the contents of chlorophyll and carotenoid change significantly, proving its essential role in leaf vein greening. Furthermore, the chlorophyll and carotenoid of tea leaves treated with CsMGT10 antisense oligonucleotides also decrease significantly. Our findings indicate that CsMGT10 mainly acts as Mg2+ transporter in chloroplast envelope of leaf veins, which may play a key role in leaf vein greening of tea plants.

Dynamic change of the carotenoid metabolic pathway profile during oolong tea processing with supplementary LED light.

Carotenoid-derived volatiles are important contributors to tea aroma quality. However, the profile of the carotenoid pathway and carotenoid-derived volatiles (CDVs) artificial regulation in oolong tea processing has yet to be investigated. In the present work, the content and varieties of carotenoid-derived volatiles, the genome-wide identification of carotenoid cleavage dioxygenase (CsCCD) gene family, the expression level of CsCCD and other key genes in the carotenoid pathway, and the profile of carotenoid substances were analyzed by multi-omics and bioinformatics methods with innovative postharvest supplementary LED light during oolong tea processing. The results showed that during oolong tea processing, a total of 17 CDVs were identified. The content of ß-ionone increased up to 26.07 times that of fresh leaves and its formation was significantly promoted with supplementary LED light from 0.54 µg/g to 0.83 µg/g in the third turning over treatment. A total of 11 CsCCD gene family members were identified and 119 light response cis-acting regulatory elements of CsCCD were found. However, the expression level of most genes in the carotenoid pathway including CsCCD were reduced due to mechanical stress. 'Huangdan' fresh tea leaves had a total of 1 430.46 µg/g 22 varieties of carotenoids, which mainly composed of lutein(78.10%), ß-carotene(8.24%) and zeaxanthin(8.18%). With supplementary LED light, the content of antherxanthin and zeaxanthin in xanthophyll cycle was regulated and CDVs such as α-ionone, ß-ionone, pseudoionone, damascenone, 6,10-dimethyl-5,9-undecadien-2-one, citral, geranyl acetate and α-farnesene were promoted significantly in different phases during oolong tea processing. Our results revealed the profile of the carotenoid metabolism pathway in oolong tea processing from the perspective of precursors, gene expression and products, and put forward an innovative way to improve CDVs by postharvest supplementary LED light.

Emulsifying properties, in vitro digestive characteristics, and ß-carotene bioaccessibility of mandarin peel pectin emulsions prepared with different carrier oil phases.

Mandarin peel pectin (MPP) emulsions were prepared with different oil phase loadings with or without ß-carotene, and their emulsifying characteristics, digestive properties and ß-carotene bioaccessibility were investigated. Results revealed that all MPP emulsions exhibited good loading efficiency for ß-carotene, while their apparent viscosity and interfacial pressure (π) of MPP emulsions increased significantly after the addition of ß-carotene. Emulsification of MPP emulsions as well as digestibility were significantly dependent on the kind of oil. MPP emulsions prepared with long-chain triglycerides (LCT) oil (soybean, corn, and olive oil) exhibited higher volume average particle size (D4,3), apparent viscosity, π values, and bioaccessibility of carotene compared to those prepared with medium-chain oils (MCT). MPP emulsions with LCT rich in monosaturated fatty acids (olive oil) had the highest ß-carotene encapsulation efficiency, bioaccessibility, etc. than from other oils. This study provides a theoretical basis for the efficient encapsulation and high bioaccessibility of carotenoids with pectin emulsions.

Genetic deletion of Bco2 and Isx establishes a golden mouse model for carotenoid research.

OBJECTIVE: Low plasma levels of carotenoids are associated with mortality and chronic disease states. Genetic studies in animals revealed that the tissue accumulation of these dietary pigments is associated with the genes encoding ß-carotene oxygenase 2 (BCO2) and the scavenger receptor class B type 1 (SR-B1). Here we examined in mice how BCO2 and SR-B1 affect the metabolism of the model carotenoid zeaxanthin that serves as a macular pigment in the human retina. METHODS: We used mice with a lacZ reporter gene knock-in to determine Bco2 expression patterns in the small intestine. By genetic dissection, we studied the contribution of BCO2 and SR-B1 to zeaxanthin uptake homeostasis and tissue accumulation under different supply conditions (50 mg/kg and 250 mg/kg). We determined the metabolic profiles of zeaxanthin and its metabolites in different tissues by LC-MS using standard and chiral columns. An albino Isx-/-/Bco2-/- mouse homozygous for Tyrc-2J was generated to study the effect of light on ocular zeaxanthin metabolites. RESULTS: We demonstrate that BCO2 is highly expressed in enterocytes of the small intestine. Genetic deletion of Bco2 led to enhanced accumulation of zeaxanthin, indicating that the enzyme serves as a gatekeeper of zeaxanthin bioavailability. Relaxing the regulation of SR-B1 expression in enterocytes by genetic deletion of the transcription factor ISX further enhanced zeaxanthin accumulation in tissues. We observed that the absorption of zeaxanthin was dose-dependent and identified the jejunum as the major zeaxanthin-absorbing intestinal region. We further showed that zeaxanthin underwent oxidation to ε,ε-3,3'-carotene-dione in mouse tissues. We detected all three enantiomers of the zeaxanthin oxidation product whereas the parent zeaxanthin only existed as (3R, 3'R)-enantiomer in the diet. The ratio of oxidized to parent zeaxanthin varied between tissues and was dependent on the supplementation dose. We further showed in an albino Isx-/-/Bco2-/- mouse that supra-physiological supplementation doses (250 mg/kg) with zeaxanthin rapidly induced hypercarotenemia with a golden skin phenotype and that light stress increased the concentration of oxidized zeaxanthin in the eyes. CONCLUSIONS: We established the biochemical basis of zeaxanthin metabolism in mice and showed that tissue factors and abiotic stress affect the metabolism and homeostasis of this dietary lipid.

Role of carotenoids in adipose tissue through the AMPK-mediated pathway.

Diet is a critical factor in controlling adiposity and white adipose tissue (WAT) physiology. A high-fat diet (HFD) alters WAT function and affects AMP-activated protein kinase (AMPK) - a cellular sensor - dysregulating lipolysis and lipid metabolism in adipocytes. Otherwise, AMPK activation may attenuate oxidative stress and inflammation. Interest in natural therapies, such as carotenoid consumption or supplementation, is growing due to their health benefits. Carotenoids are lipophilic pigments present in vegetables and fruits, which cannot be synthesized by the human body. Interventions focused on ameliorating complications induced by a HFD indicate a positive contribution of the carotenoids to the AMPK activation. This review aims to outline the mechanism of carotenoids in the AMPK pathway in adipose tissue and their contribution in regulating adipogenesis. Different carotenoids can act as an agonist of the AMPK signaling pathway, activating upstream kinases, upregulating transcriptional factors, inducing WAT browning, and blocking adipogenesis. In addition, the improvement of some "homeostatic" factors, such as adiponectin, may mediate the AMPK activation induced by carotenoids. With these findings, we encourage clinical trials to confirm the role of carotenoids in the AMPK pathway in a long-term treatment, mainly in obesity cases.

Evaluation of Various Escherichia coli Strains for Enhanced Lycopene Production.

Lycopene is a carotenoid widely used as a food and feed supplement due to its antioxidant, anti-inflammatory, and anti-cancer functions. Various metabolic engineering strategies have been implemented for high lycopene production in Escherichia coli, and for this purpose it was essential to select and develop an E. coli strain with the highest potency. In this study, we evaluated 16 E. coli strains to determine the best lycopene production host by introducing a lycopene biosynthetic pathway (crtE, crtB, and crtI genes cloned from Deinococcus wulumuqiensis R12 and dxs, dxr, ispA, and idi genes cloned from E. coli). The 16 lycopene strain titers diverged from 0 to 0.141 g/l, with MG1655 demonstrating the highest titer (0.141 g/l), while the SURE and W strains expressed the lowest (0 g/l) in an LB medium. When a 2 × YTg medium replaced the MG1655 culture medium, the titer further escalated to 1.595 g/l. These results substantiate that strain selection is vital in metabolic engineering, and further, that MG1655 is a potent host for producing lycopene and other carotenoids with the same lycopene biosynthetic pathway.