Making extra room for carotenoids in plant cells: new opportunities for biofortification

[EN] Plant carotenoids are essential for photosynthesis and photoprotection and provide colors in the yellow to red range to non-photosynthetic organs such as petals and ripe fruits. They are also the precursors of biologically active molecules not only in plants (including hormones and retrograde signals) but also in animals (including retinoids such as vitamin A). A carotenoid-rich diet has been associated with improved health and cognitive capacity in humans, whereas the use of carotenoids as natural pigments is widespread in the agrofood and cosmetic industries. The nutritional and economic relevance of carotenoids has spurred a large number of biotechnological strategies to enrich plant tissues with carotenoids. Most of such approaches to alter carotenoid contents in plants have been focused on manipulating their biosynthesis or degradation, whereas improving carotenoid sink capacity in plant tissues has received much less attention. Our knowledge on the molecular mechanisms influencing carotenoid storage in plants has substantially grown in the last years, opening new opportunities for carotenoid biofortification. Here we will review these advances with a particular focus on those creating extra room for carotenoids in plant cells either by promoting the differentiation of carotenoid-sequestering structures within plastids or by transferring carotenoid production to the cytosol.We greatly thank Carmen and Pilar Torres-Montilla for their collaboration and help in the design and execution of the figures. We also thank Luca Morelli and BioRender.com for some of the images. Work in our lab is funded by Spanish grants BIO2017-84041-P and PID2020-115810GB-I00 from the Agencia Estatal de Investigacion (AEI) and 202040E299 from Consejo Superior de Investigaciones Cientificas (CSIC) to MRC. STM was supported by PhD fellowship FPU16/04054 from the Spanish Ministerio de Educacion y CulturaTorres-Montilla, S.; Rodriguez-Concepcion, M. (2021). Making extra room for carotenoids in plant cells: new opportunities for biofortification. Progress in Lipid Research. 84:1-9. https://doi.org/10.1016/j.plipres.2021.101128S198

Crecimiento del Cangrejo de Tierra Cardisoma Guanhumi en Puerto Rico

     The land crabs’ integument release process during molting represents a moment of vulnerability due to the desiccation risk and the lack of water availability for the molting.  The aim of this study is to ascertain Cardisoma guanhumi growth increase.  A marking-recapture study was conducted to estimate crab growth.  The study was carried out in six Puerto Rico locations.  It was found that growth increment is 8.7%, which is larger than previously reported; this increment varies among study sites.  Forests with higher vegetation coverage and lower edge density favor a larger growth increment. Crab´s habitat conservation is essential for the species´ survival.     Para los cangrejos terrestres, el proceso de liberación del integumento en el proceso de muda representa un momento de vulnerabilidad debido al riesgo de desecación y la disponibilidad de agua para el proceso de muda.  El objetivo de este estudio es determinar el incremento en crecimiento del cangrejo de tierra Cardisoma guanhumi.  Se realizó un estudio de marca-recaptura para estimar el crecimiento de los cangrejos.  El estudio se realizó en seis localidades en Puerto Rico.  Encontramos que el incremento en crecimiento es de 8.7% y que hay una diferencia entre los lugares de estudio.  Este incremento es mayor que lo reportado anteriormente.  La diferencia entre los lugares de estudio se debe a diferencias en la estructura de los bosques.  Los bosques con mayor cobertura vegetal y menos densidad de borde favorecen un incremento en crecimiento.  La conservación del hábitat del cangrejo es esencial para la sobrevivencia de esta especie

Cre-LoxP-regulated expression of monoclonal antibodies driven by an ovalbumin promoter in primary oviduct cells

<p>Abstract</p> <p>Background</p> <p>A promoter capable of driving high-level transgene expression in oviduct cells is important for developing transgenic chickens capable of producing therapeutic proteins, including monoclonal antibodies (mAbs), in the whites of laid eggs. Ovalbumin promoters can be used as oviduct-specific regulatory sequences in transgenic chickens, but their promoter activities are not high, according to previous reports.</p> <p>Results</p> <p>In this study, while using a previously characterized ovalbumin promoter, we attempted to improve the expression level of mAbs using a Cre/<it>lox</it>P-mediated conditional excision system. We constructed a therapeutic mAb expression vector, pBS-DS-hIgG, driven by the CMV and CAG promoters, in which the expression of the heavy and light chains of humanized immunoglobulin G (hIgG) is preceded by two floxed stuffer reporter genes. In the presence of Cre, the stuffer genes were precisely excised and hIgG expression was induced in pBS-DS-hIgG-transfected 293T cells. In chicken oviduct primary culture cells, hIgG was expressed after transfection of pBS-DS-hIgG together with the ovalbumin promoter-driven Cre expression vector. The expression level of hIgG in these cells was increased 40-fold over that induced directly by the ovalbumin promoter. On the other hand, hIgG was not induced by the ovalbumin promoter-driven Cre in chicken embryonic fibroblast cells.</p> <p>Conclusions</p> <p>The Cre/<it>lox</it>P-based system could significantly increase ovalbumin promoter-driven production of proteins of interest, specifically in oviduct cells. This expression system could be useful for producing therapeutic mAbs at high level using transgenic chickens as bioreactors.</p

Learner Engagement, Retention and Success: Why Size Matters in Massive Open Online Courses (MOOCs)

Massive open online courses (MOOCs) are usually six to ten weeks long. Participation tends to decrease as the courses progress, leading to low completion rates. This led to the question: Could shorter MOOCs contribute to learners’ engagement, retention and success? This paper compares two versions of Study Skills MOOC, which shared the same content but were delivered in different length formats. One was deployed as a single six-week course and the other as two three-week blocks. In total, 617 people registered for the two versions. Data sources included learning analytics, surveys and the Spanish version of the General Self-Efficacy Scale. Both versions of the Study Skills MOOC resulted in increased participants’ self-efficacy. However, learners enrolled in the version composed of two three-week blocks were also more engaged with course content, other students and the facilitators. Their retention and completion rates were higher than those in the longer version of the course. Reasons linked to goal proximity, motivation, interactions and social modelling are discussed

Interference with plastome gene expression and Clp protease activity in Arabidopsis triggers a chloroplast unfolded protein response to restore protein homeostasis

Disruption of protein homeostasis in chloroplasts impairs the correct functioning of essential metabolic pathways, including the methylerythritol 4-phosphate (MEP) pathway for the production of plastidial isoprenoids involved in photosynthesis and growth. We previously found that misfolded and aggregated forms of the first enzyme of the MEP pathway are degraded by the Clp protease with the involvement of Hsp70 and Hsp100/ClpC1 chaperones in Arabidopsis thaliana. By contrast, the combined unfolding and disaggregating actions of Hsp70 and Hsp100/ClpB3 chaperones allow solubilization and hence reactivation of the enzyme. The repair pathway is promoted when the levels of ClpB3 proteins increase upon reduction of Clp protease activity in mutants or wild-type plants treated with the chloroplast protein synthesis inhibitor lincomycin (LIN). Here we show that LIN treatment rapidly increases the levels of aggregated proteins in the chloroplast, unleashing a specific retrograde signaling pathway that up-regulates expression of ClpB3 and other nuclear genes encoding plastidial chaperones. As a consequence, folding capacity is increased to restore protein homeostasis. This sort of chloroplast unfolded protein response (cpUPR) mechanism appears to be mediated by the heat shock transcription factor HsfA2. Expression of HsfA2 and cpUPR-related target genes is independent of GUN1, a central integrator of retrograde signaling pathways. However, double mutants defective in both GUN1 and plastome gene expression (or Clp protease activity) are seedling lethal, confirming that the GUN1 protein is essential for protein homeostasis in chloroplasts

A root specific induction of carotenoid biosynthesis contributes to ABA production upon salt stress in arabidopsis

Abscisic acid (ABA) is a hormone that plays a vital role in mediating abiotic stress responses in plants. Salt exposure induces the synthesis of ABA through the cleavage of carotenoid precursors (xanthophylls), which are found at very low levels in roots. Here we show that de novo ABA biosynthesis in salt-treated Arabidopsis thaliana roots involves an organ-specific induction of the carotenoid biosynthetic pathway. Upregulation of the genes encoding phytoene synthase (PSY) and other enzymes of the pathway producing ABA precursors was observed in roots but not in shoots after salt exposure. A pharmacological block of the carotenoid pathway substantially reduced ABA levels in stressed roots, confirming that an increase in carotenoid accumulation contributes to fuel hormone production after salt exposure. Treatment with exogenous ABA was also found to upregulate PSY expression only in roots, suggesting an organ-specific feedback regulation of the carotenoid pathway by ABA. Taken together, our results show that the presence of high concentrations of salt in the growth medium rapidly triggers a root-specific activation of the carotenoid pathway, probably to ensure a proper supply of ABA precursors required for a sustained production of the hormone

Nutritional Enrichment of Plant Leaves by Combining Genes Promoting Tocopherol Biosynthesis and Storage

The enrichment of plant tissues in tocochromanols (tocopherols and tocotrienols) is an important biotechnological goal due to their vitamin E and antioxidant properties. Improvements based on stimulating tocochromanol biosynthesis have repeatedly been achieved, however, enhancing sequestering and storage in plant plastids remains virtually unexplored. We previously showed that leaf chloroplasts can be converted into artificial chromoplasts with a proliferation of plastoglobules by overexpression of the bacterial crtB gene. Here we combined coexpression of crtB with genes involved in tocopherol biosynthesis to investigate the potential of artificial leaf chromoplasts for vitamin E accumulation in Nicotiana benthamiana leaves. We show that this combination improves tocopherol levels compared to controls without crtB and confirm that VTE1, VTE5, VTE6 and tyrA genes are useful to increase the total tocopherol levels, while VTE4 further leads to enrichment in alpha-tocopherol (the tocochromanol showing highest vitamin E activity). Additionally, we show that treatments that further promote plastoglobule formation (e.g., exposure to intense light or dark-induced senescence) result in even higher improvements in the tocopherol content of the leaves. An added advantage of our strategy is that it also results in increased levels of other related plastidial isoprenoids such as carotenoids (provitamin A) and phylloquinones (vitamin K1)

Presencia de Aphis arbuti Ferrari y Wahlgreniella nervata (Gillete) (Hemiptera, Aphididae) en los madroños de la Comunidad de Madrid y estudio de la fumagina asociada.

Determinación de los pulgones asociados al madroño y su relación con los hongos desarrollados sobre la melaza

Fe speciation in Iron modified natural zeolites as sustainable environmental catalysts

Natural purified mordenite from Palmarito de Cauto (ZP) deposit, Cuba, was subjected to a hydrothermal ion exchange process in acid medium with Fe2+ or Fe3+ salts (Fe2+ZP and Fe3+ZP). The set of samples was characterized regarding their textural properties, morphology, and crystallinity, and tested in the NO reduction with CO/C3H6. Infrared spectroscopy coupled with NO as a probe molecule was used to give a qualitative description of the Fe species&rsquo; nature and distribution. The exchange process caused an increase in the iron loading of the samples and a redistribution, resulting in more dispersed Fe2+ and Fe3+ species. When contacted with the NO probe, Fe2+ZP showed the highest intensity of nitrosyl bands, assigned to NO adducts on isolated/highly dispersed Fe2+/Fe3+ extra-framework sites and FexOy clusters. This sample is also characterized by the highest NO sorption capacity and activity in NO reduction. Fe3+ZP showed a higher intensity of nitrosonium (NO+) species, without a correlation to NO storage and conversion, pointing to the reactivity of small FexOy aggregates in providing oxygen atoms for the NO to NO+ reaction. The same sites are proposed to be responsible for the higher production of CO2 observed on this sample, and thus to be detrimental to the activity in NO SCR

The Value of ICT and the Students&#039; Heterogeneity

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