Innovative technologies in human reproduction: challenges ahead

Inaugural lecture delivered by Prof. dr. Susana M. Chuva de Sousa Lopes on acceptance of the position of Professor Developmental Biology, in particular human development at Leiden University on June 29, 2020Inaugural lecture delivered by Prof. dr. Susana M. Chuva de Sousa Lopes on acceptance of the position of Professor Developmental Biology, in particular human development at Leiden University on June 29, 2020LUMC / Geneeskund

BMPs, TGFbetas and integrins in muscle and germ cell development in mice

We characterized the expression of PSmad1/5/8 (BMP R-Smads) and PSmad2 (TGFbeta R-Smad) during peri-implantation and gastrulation in the mouse, and further characterized the expression of PSmad2 until E12.5, showing were the BMP and TGFbeta Smad-dependent signalling pathways are active (Chapter 2, 3 and 4). The role of ALK2 (BMP signalling) and ALK5 (TGFbeta signalling) in the development of PGCs in the mouse was studied in detail. ALK2 is needed for the formation of PGCs before gastrulation occurs and it signals in the visceral endoderm, a tissue that was previously not associated with primordial germ cell formation (Chapter 3). In contrast to suggestions derived from studies in vitro, ALK5 is probably not involved in PGC migration through the hindgut and to the gonadal ridges and TGF 1 is unlikely to be a chemoattractant for PGCs as proposed (Chapter 4). However, there may be a role for TGF signalling in PGC development in controlling mitotic arrest of PGCs in the gonadal ridges. Beta1 integrin was also implicated in PGC migration to the genital ridges. Beta1 integrin has two isoforms in mice: a more common one beta1A and a muscle specific beta1D that is upregulated late during development. We studied whether the replacement of beta1A by beta1D influenced the development of PGCs, but this occurred normally and we found no evidence of an effect on migration on the genetic background used. Furthermore, beta1 integrin has been implicated in heart development. We showed that the replacement of beta1A by beta1D did not cause heart abnormalities during development. However, we were able to show a clear role for beta1A during myogenesis. The differentiation of primary myoblasts was abnormal when only beta1D was expressed, while secondary myoblasts were formed normally. Furthermore, we showed a novel role of beta1 integrin during placentation, in particular the development of the labyrinthine layer (Chapter 5). CTGF is known to crosstalk with both TGFbeta and BMP in vitro. We studied possible interactions between them, focusing on heart development, where BMP and TGFbeta are known to play prominent roles. However, we were not able to detect direct crosstalk. Both CTGF and TGFbeta are associated with fibrosis. We investigated whether CTGF and TGFbeta were expressed following experimental induction of myocardial infarction in the mouse and showed that both genes are present in particular in the scar tissue and that TGFbeta Smad-dependent signalling is transient 1 week post-infarction and largely restricted to cardiac fibroblasts (Chapter 6)

Glutamate-N-methyl-D-aspartate receptor modulation and minocycline for the treatment of patients with schizophrenia: an update

Growing consistent evidence indicates that hypofunction of N-methyl-D-aspartate (NMDA) transmission plays a pivotal role in the neuropathophysiology of schizophrenia. Hence, drugs which modulate NMDA neurotransmission are promising approaches to the treatment of schizophrenia. The aim of this article is to review clinical trials with novel compounds acting on the NMDA receptor (NMDA-R). This review also includes a discussion and translation of neuroscience into schizophrenia therapeutics. Although the precise mechanism of action of minocycline in the brain remains unclear, there is evidence that it blocks the neurotoxicity of NMDA antagonists and may exert a differential effect on NMDA signaling pathways. We, therefore, hypothesize that the effects of minocycline on the brain may be partially modulated by the NMDA-R or related mechanisms. Thus, we have included a review of minocycline neuroscience. The search was performed in the PubMed, Web of Science, SciELO, and Lilacs databases. The results of glycine and D-cycloserine trials were conflicting regarding effectiveness on the negative and cognitive symptoms of schizophrenia. D-serine and D-alanine showed a potential effect on negative symptoms and on cognitive deficits. Sarcosine data indicated a considerable improvement as adjunctive therapy. Finally, minocycline add-on treatment appears to be effective on a broad range of psychopathology in patients with schizophrenia. The differential modulation of NMDA-R neurosystems, in particular synaptic versus extrasynaptic NMDA-R activation and specific subtypes of NMDA-R, may be the key mediators of neurogenesis and neuroprotection. Thus, psychotropics modulating NMDA-R neurotransmission may represent future monotherapy or add-on treatment strategies in the treatment of schizophrenia

β-thalassemia Intermedia In A Brazilian Patient With - 101 (c > T) And Codon 39 (c > T) Mutations

Context: We verified molecular alterations in a 72-year-old Brazilian male patient with a clinical course of homozygous β-thalassemia intermedia, who had undergone splenectomy and was surviving without regular blood transfusions. The blood cell count revealed microcytic and hypochromic anemia (hemoglobin = 6.5 g/dl, mean cell volume = 74 ft, mean cell hemoglobin = 24 pg) and hemoglobin electrophoresis showed fetal hemoglobin = 1.3%, hemoglobin A 2 = 6.78% and hemoglobin A = 79.4%. Objective: To identify mutations in a patient with the symptoms of β-thalassemia intermedia. Design: Molecular inquiry into the mutations possibly responsible for the clinical picture described. Setting: The structural molecular biology and genetic engineering center of the Universidade Estadual de Campinas, Campinas, Brazil. Procedures: DNA extraction was performed on the patient's blood samples. The polymerase chain reaction (PCR) was done using five specific primers that amplified exons and the promoter region of the β globin gene. The samples were sequenced and then analyzed via computer programs. Results: Two mutations that cause the disease were found: -101 (C > T) and codon 39 (C > T). Conclusions: This cases represents the first description of -101 (C > T) mutation in a Brazilian population and it is associated with a benign clinical course.12112830Baysal, E., Carver, M.F.H., The beta and delta-thalassemia repository (1995) Hemoglobin., 19 (3-4), pp. 213-236Zago, M.A., Costa, F., Bottura, C., Beta-thalassemia in Brazil (1981) Braz. J. Med. Biol. Res., 14 (6), pp. 383-388Ewing, B., Green, P., Base-calling of automated sequencer traces using Phred. II Error probabilities (1998) Genome Res., 8 (3), pp. 186-194Green, P., (2002), http://bozeman.genome.washington.edu/phrap.docs/phrap.html, The Phred/Phrap/Consed System Home Page. Phrap Assembler. Available at URL September 30Gordon, D., Abajian, C., Green, P., Consed: A graphical tool for sequence finishing (1998) Genome Res., 8 (3), pp. 195-20

Phiclust: a clusterability measure for single-cell transcriptomics reveals phenotypic subpopulations

The ability to discover new cell phenotypes by unsupervised clustering of single-cell transcriptomes has revolutionized biology. Currently, there is no principled way to decide whether a cluster of cells contains meaningful subpopulations that should be further resolved. Here, we present phiclust (phi(clust)), a clusterability measure derived from random matrix theory that can be used to identify cell clusters with non-random substructure, testably leading to the discovery of previously overlooked phenotypes.Theoretical PhysicsBiological and Soft Matter Physic

Spin-Lattice Relaxation in Si Quantum Dots

We consider spin-lattice relaxation processes for electrons trapped in lateral Si quantum dots in a $[001]$ inversion layer. Such dots are characterized by strong confinement in the direction perpendicular to the surface and much weaker confinement in the lateral direction. The spin relaxation is assumed to be due to the modulation of electron $g$-factor by the phonon-induced strain, as was shown previously for the shallow donors. The results clearly indicate that the specific valley structure of the ground electron state in Si quantum dots causes strong anisotropy for both the one-phonon and two-phonon spin relaxation rates. In addition, it gives rise to a partial suppression of the two-phonon relaxation in comparison to the spin relaxation of donor electrons.Comment: RevTex file, 3 PS figure

Green functions for generalized point interactions in 1D: A scattering approach

Recently, general point interactions in one dimension has been used to model a large number of different phenomena in quantum mechanics. Such potentials, however, requires some sort of regularization to lead to meaningful results. The usual ways to do so rely on technicalities which may hide important physical aspects of the problem. In this work we present a new method to calculate the exact Green functions for general point interactions in 1D. Our approach differs from previous ones because it is based only on physical quantities, namely, the scattering coefficients, $R$ and $T$, to construct $G$. Renormalization or particular mathematical prescriptions are not invoked. The simple formulation of the method makes it easy to extend to more general contexts, such as for lattices of $N$ general point interactions; on a line; on a half-line; under periodic boundary conditions; and confined in a box.Comment: Revtex, 9 pages, 3 EPS figures. To be published in PR

BMP-SMAD Signaling Regulates Lineage Priming, but Is Dispensable for Self-Renewal in Mouse Embryonic Stem Cells

Naive mouse embryonic stem cells (mESCs) are in a metastable state and fluctuate between inner cell mass- and epiblast-like phenotypes. Here, we show transient activation of the BMP-SMAD signaling pathway in mESCs containing a BMP-SMAD responsive reporter transgene. Activation of the BMP-SMAD reporter transgene in naive mESCs correlated with lower levels of genomic DNA methylation, high expression of 5-methylcytosine hydroxylases Tet1/2 and low levels of DNA methyltransferases Dnmt3a/b. Moreover, naive mESCs, in which the BMP-SMAD reporter transgene was activated, showed higher resistance to differentiation. Using double Smad1;Smad5 knockout mESCs, we showed that BMP-SMAD signaling is dispensable for self-renewal in both naive and ground state. These mutant mESCs were still pluripotent, but they exhibited higher levels of DNA methylation than their wild-type counterparts and had a higher propensity to differentiate. We showed that BMP-SMAD signaling modulates lineage priming in mESCs, by transiently regulating the enzymatic machinery responsible for DNA methylation

BMP-SMAD Signaling Regulates Lineage Priming, but Is Dispensable for Self-Renewal in Mouse Embryonic Stem Cells

Biological and Soft Matter Physic