Tissue-Specific Transcriptomes Reveal Gene Expression Trajectories in Two Maturing Skin Epithelial Layers in Zebrafish Embryos.

Epithelial cells are the building blocks of many organs, including skin. The vertebrate skin initially consists of two epithelial layers, the outer periderm and inner basal cell layers, which have distinct properties, functions, and fates. The embryonic periderm ultimately disappears during development, whereas basal cells proliferate to form the mature, stratified epidermis. Although much is known about mechanisms of homeostasis in mature skin, relatively little is known about the two cell types in pre-stratification skin. To define the similarities and distinctions between periderm and basal skin epithelial cells, we purified them from zebrafish at early development stages and deeply profiled their gene expression. These analyses identified groups of genes whose tissue enrichment changed at each stage, defining gene flow dynamics of maturing vertebrate epithelia. At each of 52 and 72 hr post-fertilization (hpf), more than 60% of genes enriched in skin cells were similarly expressed in both layers, indicating that they were common epithelial genes, but many others were enriched in one layer or the other. Both expected and novel genes were enriched in periderm and basal cell layers. Genes encoding extracellular matrix, junctional, cytoskeletal, and signaling proteins were prominent among those distinguishing the two epithelial cell types. In situ hybridization and BAC transgenes confirmed our expression data and provided new tools to study zebrafish skin. Collectively, these data provide a resource for studying common and distinguishing features of maturing epithelia

Use of in-vivo induced antigen technology to identify bacterial genes expressed during Solea senegalensis infection with Photobacterium damselae subsp. piscicida

The marine fish pathogen Photobacterium damselae subsp. piscicida (Phdp) is responsible for important disease outbreaks affecting several fish species including flatfish Solea senegalensis (Kaup). Phdp is able to avoid host defences by invasion and intracellular survival in non-phagocytic cells, mainly epithelial cells. Virulence factors reported in Phdp include restricting complement-mediated activity, apoptosis of phagocytes caused by exotoxins secretion, iron acquisition mechanisms such as siderophores that enable the pathogen to obtain iron from transferrin and ability to bind haemin and antioxidant enzymatic activities capable to counteract superoxide radicals (Do Vale et al., 2005; Andreoni and Magnano, 2014). Commonly, genes expressed during pathogen infection are important for pathogenicity. In vivo-induced antigen technology (IVIAT) (Handfield et al., 2000) has been used to identify in vivo-induced genes using pooled sera from fish that have experienced photobacteriosis. Materials and methods Sera were obtained from surviving S. senegalensis specimens after sublethal infection with Phdp (Lg41/01) and subsequently pooled and adsorbed against in vitro grown Phdp Lg41/01 and Escherichia coli BL21 (DE3) cells and lysates according to Handfield et al. (2000). The efficiency of sera adsorption was evaluated based on the immunoreactivity after each adsorption step with whole and lysed Phdp cells grown in vitro. A genomic expression library of Phdp Lg41/01 was generated in E. coli BL21 (DE3) using pET-30 expression system (Novagen, San Diego, CA, USA). The expression library was probed with adsorbed and non-absorbed sera using immunoblot technique. Reactive clones of in vivo-induced and in vitro antigens were obtained, purified and their inserted DNA sequenced (Macrogen Europe, Amsterdam, The Netherlands). Nucleotide sequences were compared against the NCBI protein database using BLASTx. Results A progressive reduction in sera immunoreactivity against in vitro grown Phdp cells was detected after the adsorption rounds, especially after the first adsorption step. Thus, following adsorption steps substantially removed antibodies against in vitro expressed antigens and resulted in relative enrichment in antibodies recognizing in vivo expressed antigens. The library from Phdp Lg14/01 constructed in E. coli BL21 (DE3) consisted of approximately 6500 recombinants. A total of 117 clones were selected for their reactivity with pooled adsorbed and non-adsorbed sera from convalescent S. senegalensis specimens after a first round of screening. In a second screening, 14 out of 117 candidate clones showed positive reaction, among which two clones were clearly positive and two gave weak reaction against adsorbed sera. Predicted proteins codified by inserted sequences have intracellular and membrane cell location and are involved in virulence, synthesis of intermediary products, energy metabolism and gene replication. Inosine-5’-monophosphate dehydrogenase (IMPDH) and alkyl hydroperoxide reductase (AhpC) have been identified as in vivo induced antigens expressed during S. senegalensis infection with Phdp. Iron/manganese superoxide dismutase (Fe/Mn-SOD) and alanyl-tRNA synthetase (AlaRS) proteins have also been identified, though with weak signal. Discussion and conclusion Identification of immunogenic bacterial proteins during Phdp infection is essential for understanding bacterial pathogenesis and development of effective vaccines. AhpC peroxidase activity has a protective role by reducing hydrogen peroxide, peroxynitrite and organic hydroperoxides. Immunization with AhpC conferred protection against Helicobacter pylori infection (O’Riordan et al., 2012). IMPDH catalyzes the conversion of products essential in de novo synthesis of guanine nucleotides. Adequate levels of purine nucleotides are critical for cell proliferation, nucleic acid replication, cell signaling and as a biochemical energy source. This gene is an important therapeutic target against bacterial diseases (Shu and Nair,2008). In conclusion, different genes expressed during Phdp infection in S. senegalensis have been identified. Among them, IMPDH and AhpC have been identified as in vivo induced antigens expressed during S. senegalensis infection with Phdp. Thus, they are likely to play a role in the virulence of Phdp. The antigenic character of these proteins makes them potential targets for the development of new vaccines. References Andreoni, F., and Magnani, M., 2014. Photobacteriosis: Prevention and Diagnosis. Journal of Immunology Research, 2014: 1-7. Do Vale, A., Silva, M.T., dos Santos, N.M., Nascimento, D.S., Reis Rodrigues, P., Costa Ramos, C., Ellis, A.E., and Azevedo, J.E., 2005. AIP56, a novel plasmid-encoded virulence factor of Photobacterium damselae subsp. piscicida with apoptogenic activity against sea bass macrophages and neutrophils. Molecular Microbiology, 58: 1025-1038. Handfield, M., Brady, L.J., Progulske-Fox, A., and Hillman, J.D., 2000. IVIAT: a novel method to identify microbial genes expressed specifically during human infections. Trends in Microbiology, 8: 336-339. O’Riordan A.A., Morales V.A., Mulligan L., Faheem N., Windle H.J., and Kelleher D.P., 2012. Alkyl hydroperoxide reductase: a candidate Helicobacter pylori vaccine. Vaccine, 30:3876-3884. Shu, Q., and Nair, V., 2008. Inosine monophosphate dehydrogenase (IMPDH) as a target in drug discovery. Medicinal Research Reviews, 28:219-232.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Grade retention and school entry age in Spain: a structural problem

Grade retention has been the focus of the education debate in Spain for decades. On average, more than 30% of students have repeated at least one grade before they finish (or dropout from) their compulsory studies. The present research provides new evidence on this issue by investigating the influence of Spain’s school entry age upon students’ grade retention. Using data from 15-year-old students who participated in the PISA 2006, 2009, 2012 and 2015 assessments, we implement a regression discontinuity analysis. Our key finding is that students who were born late in the year (younger students) are more likely to repeat a grade. Yet, once they reach secondary education, the disadvantage they suffer due to their younger school starting age seems to disappear. Hence, the key reason why younger students have lower PISA scores than older students in Spain is due to their increased likelihood of repeating a grade, rather than being due to their relative age per se. To avoid these artificial disadvantages of younger students and unfair retention, we suggest that policymakers inform families about this school entry issue and also make the school entry law more flexible. This would facilitate parents of younger children to choose whether to delay their children’s school enrolment or not

Does it matter what children read? New evidence using longitudinal census data from Spain

It has long been thought that encouraging children to read is likely to be beneficial for the development of their literacy skills. However, a lot less attention has been paid to the issue of whether what students read matters for their academic progress. This paper therefore considers the association between the frequency young people read five different types of text (comics, short stories, books, newspapers and magazines) and their scores on standardised reading and mathematics tests. Drawing upon large longitudinal census data from the largest administrative region in Spain, we find that frequency of reading comics, newspapers and magazines is not associated with the development of children’s cognitive skills. In contrast, there is clear and consistent evidence of a positive and increasing association between the frequency children read books and their academic achievement. We consequently conclude that recommended reading time for children should be focused upon the time they spend reading books and not other material

Cost assessment of clean generation incentives in Mexico for utility scale solar photovoltaic projects

Mexico recently opened the electric generation sector to competition. In addition, regulations to reach clean generation goals were implemented. These regulations include Clean Energy Certificates (CELs) obligations (similar to the Renewable Portfolio Standards in the United States), and the obligation of electricity suppliers to go into long term contracts with generators to guarantee the required electric energy and CELs supply. These contracts are procured through an auction mechanism. The purpose of this research is to i) estimate the cost of reaching the goals through the implemented policy, and ii) evaluate if the projects could be economically feasible by selling electricity in the short term market, without the incentives. This research looked at three different utility scale solar photovoltaic projects that will operate under long term contracts for the provision of electric energy and CELs. The revenues of the projects under the contract terms were modeled and contrasted with projected Locational Marginal Prices (LMPs). In addition, a discounted cash flow analysis was done for the three projects, both under long term contract conditions and short term market conditions. Two projects were found to be financially feasible under short term market conditions. For these projects, the LMP was between $1.34 and$4.03 USD/MWh higher than the long term contract price. One project was not feasible under short term market conditions. For this project to be feasible in the short term market, the LMPs needed to be over $1.49 USD/MWh higher than the projections, while the price paid in the contract for this project was approximately$1.29 USD/MWh higher than the projected LMPs. These results show that the policy implemented is efficient, provides benefits to customers, and in some cases to investors. In the cases where the projects were feasible without the incentive, they would have sold their energy for a higher price without the long term contract mechanism. In addition, the project that was not financially feasible under short term market conditions would have needed a higher premium over the LMP price, than the premium achieved through the long term contract.Energy and Earth Resource

Identification Of Mitotically Competent SOX2+ Cells In White Matter Of Normal Human Adult Brain

SOX2 expression is linked to the undifferentiated state of stem cells in mammalian neurogenic niches. While its expression has been reported in the adult human subventricular zone (SVZ), to date it has not been detected in adult human white matter. Here we describe a population of SOX2+ cells from the white matter of the adult human temporal lobe, which proliferate and express glial markers in vitro

A metaheuristic approach for the repositioning problem in bike sharing systems (bss): a study case in Toluca, México

The impact of Bike Sharing Systems (BSS) in the world had experienced such success that nowadays most iconic cities in the world have adopted its own system. The particular characteristics of the user’s mobility in every city have not allowed developing a generalized procedure to operate the systems. Moreover, the lack of symmetry in the mobility patterns, and the dynamic users’ behavior lead to eventually “unbalance” the system, this is, to a lack of bikes at stations, and therefore bikes have to be repositioned to stations where effective demand is present, and there is no unified or scientifically supported methodology. In this paper we deal with a study case in Toluca city (Huizi system), in which the entity in charge of current operational activities wants to design a procedure scientifically based to perform repositioning daily activities at the minimum operational cost guarantying the availability of bikes for the users (service level). Due to operational requirements, this bi-objective problem was formulated using a dynamic scope and stated as a combinatorial optimization model and finally solved using a multi-objective evolutionary algorithm