In vivo Analysis of Choroid Plexus Morphogenesis in Zebrafish

BACKGROUND: The choroid plexus (ChP), a component of the blood-brain barrier (BBB), produces the cerebrospinal fluid (CSF) and as a result plays a role in (i) protecting and nurturing the brain as well as (ii) in coordinating neuronal migration during neurodevelopment. Until now ChP development was not analyzed in living vertebrates due to technical problems. METHODOLOGY/PRINCIPAL FINDINGS: We have analyzed the formation of the fourth ventricle ChP of zebrafish in the GFP-tagged enhancer trap transgenic line SqET33-E20 (Gateways) by a combination of in vivo imaging, histology and mutant analysis. This process includes the formation of the tela choroidea (TC), the recruitment of cells from rhombic lips and, finally, the coalescence of TC resulting in formation of ChP. In Notch-deficient mib mutants the first phase of this process is affected with premature GFP expression, deficient cell recruitment into TC and abnormal patterning of ChP. In Hedgehog-deficient smu mutants the second phase of the ChP morphogenesis lacks cell recruitment and TC cells undergo apoptosis. CONCLUSIONS/SIGNIFICANCE: This study is the first to demonstrate the formation of ChP in vivo revealing a role of Notch and Hedgehog signalling pathways during different developmental phases of this process

Gi/o-protein coupled receptors in the aging brain

Cells translate extracellular signals to regulate processes such as differentiation, metabolism and proliferation, via transmembranar receptors. G protein-coupled receptors (GPCRs) belong to the largest family of transmembrane receptors, with over 800 members in the human species. Given the variety of key physiological functions regulated by GPCRs, these are main targets of existing drugs. During normal aging, alterations in the expression and activity of GPCRs have been observed. The central nervous system (CNS) is particularly affected by these alterations, which results in decreased brain functions, impaired neuroregeneration, and increased vulnerability to neuropathologies, such as Alzheimer's and Parkinson diseases. GPCRs signal via heterotrimeric G proteins, such as Go, the most abundant heterotrimeric G protein in CNS. We here review age-induced effects of GPCR signaling via the Gi/o subfamily at the CNS. During the aging process, a reduction in protein density is observed for almost half of the Gi/o-coupled GPCRs, particularly in age-vulnerable regions such as the frontal cortex, hippocampus, substantia nigra and striatum. Gi/o levels also tend to decrease with aging, particularly in regions such as the frontal cortex. Alterations in the expression and activity of GPCRs and coupled G proteins result from altered proteostasis, peroxidation of membranar lipids and age-associated neuronal degeneration and death, and have impact on aging hallmarks and age-related neuropathologies. Further, due to oligomerization of GPCRs at the membrane and their cooperative signaling, down-regulation of a specific Gi/o-coupled GPCR may affect signaling and drug targeting of other types/subtypes of GPCRs with which it dimerizes. Gi/o-coupled GPCRs receptorsomes are thus the focus of more effective therapeutic drugs aiming to prevent or revert the decline in brain functions and increased risk of neuropathologies at advanced ages.This work was supported by Fundação para a Ciência e Tecnologia, Centro 2020 and Portugal 2020, the COMPETE program, QREN, and the European Union (FEDER program) via the GoBack project (PTDC/CVT-CVT/32261/2017), the pAGE program (Centro-01-0145-FEDER-000003), and Institute for Biomedicine iBiMED (UID/BIM/04501/2013; UID/BIM/04501/2019).publishe

Decomposition Analysis Resolution Process (DAR) of Systems Engineering Applied to Development of Countermeasure on Leakage of Engine Head-Gasket

Part 5: Aeronautical and Automotive EngineeringInternational audienceThis paper reviews a countermeasure development of leakage from coolant seals of head-gaskets in a diesel engine applying the Decomposition Analysis and Resolution Process (DAR). We can find complexity arising from some causes of leakage even in a simple square-ring rubber seal. The major causes are (1) large displacement around a head-gasket generated by the combustion, (2) seal distortion at a high compression, (3) seal rubber degradation induced by coolant microorganism deterioration, (4) uncontrolled seal production and (5) unsuitable rubber composition. Through our DAR, we can resolve the complexity of the leakage and can clarify all the cause positions and their relationships. We can confirm that an improved silicone rubber seal, which has a higher fatigue strength, an excellent acid-resistance and a uniform contact property, is the correct resolution. This paper also shows development of a hydrogenated nitrile rubber seal as a permanent measure, which can extend the Middle of Life (MOL) of Product Lifecycle Management (PLM) of the industrial diesel engine production