A test setup was designed and built to test energy recovery ventilator membranes. The purpose of this test setup was to measure the heat transfer and water vapor transfer rates through energy recover ventilator membranes and find their effectiveness, with air conditions that resemble residential use. Two test chambers were constructed with different channel heights above the membrane; one was 1mm and the other 2mm. The 2mm setup gave measureable results, but small air leaks in the system of 7.0% and 6.2% left room for error. The 1mm setup also had air leaks but they were smaller than the 2mm setup, with leak rates of 1.0% and 5.1%. The permeance of the membrane was found to be 2.58x10^-5 g/(m2*s*Pa) for the 2mm test chamber and 9.90x10^-54 g/(m2*s*Pa) for the 1mm test chamber.

Le SARM et l’ERV sont deux bactéries responsables d’infections nosocomiales importantes. Elles sont retrouvées au sein des différents centres hospitaliers à travers le monde et leur présence cause de grands problèmes en santé publique. Elles constituent notamment une cause majeure de complication des soins de santé avec, en conséquence, une augmentation de la mortalité et de la morbidité, une prolongation de l’hospitalisation et une hausse importante des coûts de santé (INSPQ). La détection rapide du SARM et de l’ERV permettrait un meilleur contrôle de ces maladies nosocomiales. Présentement, le dépistage se fait séparément. Afin de réduire le temps d’exécution des analyses, nous proposons de combiner le dépistage des 2 microorganismes. Le projet consistait au développement d’une méthode d’analyse diagnostique pour la détection simultanée du SARM et de l’ERV par PCR. Par la suite, nous avons procédé à la validation de la méthode sur 99 spécimens de patients. La réalisation de ce projet de recherche se scinde en trois étapes importantes : 1) l’élaboration d’un nouveau bouillon de culture permettant la croissance du SARM et de l’ERV, 2) la mise au point de la PCR en temps réel et finalement, 3) la validation de cette méthode grâce à un nombre significatif de spécimens de patients. Nous avons trouvé qu’un nouveau bouillon de culture, contenant 25 g/L de NaCl, d’aztréonam et de céfotaxime permettait la croissance concomitante du SARM et de l’ERV tout en inhibant la croissance du SASM et des entérobactéries. Notre PCR multiplex permet l’amplification du SARM traditionnel et SARM-AC, de la souche récemment découverte en Europe ainsi que les 2 principaux génotypes d’ERV. Nous avons validé ces deux innovations auprès de 99 participants. Analysées par la méthode de référence, la sensibilité et la spécificité de notre bouillon sont de 50% et de 95% respectivement pour le SARM. Analysée par notre PCR multiplex, la sensibilité augmente à 92,8%. La sensibilité et la spécificité de notre bouillon avec notre PCR multiplex ERV sont de 100%. La validation du nouveau bouillon (1D) a démontré qu’il est aussi efficace voire plus que le bouillon utilisé actuellement. La nouvelle PCR permet l’amplification du SARM et de l’ERV simultanément dans un même programme PCR.

Long terminal repeat (LTR) retrotransposons account for approximately 10% of mouse and 8% of human genomes and may play a role in modifying gene expression. Many species harbor retrotransposon families encompassing both autonomous and non-autonomous members. Specifically, the mouse Early Transposon (ETn) family members lack all retroviral genes but are transcriptionally and retrotranspositionally active, causing over 20 known insertional germline mutations. ETns owe their retrotransposition potential to proteins encoded by structurally intact MusD retrotransposons with whom they share LTRs. ETn elements are transcribed at a much higher level than MusD retrotransposons in embryos and undifferentiated cells, suggesting their evasion of host restriction mechanisms. However, mechanisms responsible for the replicative success of non-autonomous retrotransposon subfamilies over their coding-competent relatives are poorly understood. In the first stage of my research, I analyzed regulatory sequences in an ETn LTR responsible for its high promoter activity in the undifferentiated cell line P19. I found that three GC-boxes that may function as Sp1/Sp3 binding sites act synergistically and are indispensable for undifferentiated cell-specific promoter activity of the LTR. Sp1 binding partners may be responsible for the restricted ETn expression. Moreover, I have shown that unlike many retroviruses, ETn elements possess multiple transcription initiation sites and that they have amplified via intracellular retrotransposition in the P19 teratocarcinoma cell line. In the next step of my research, I performed analysis of epigenetic mechanisms as a means of ERV suppression. Specifically, I showed that in embryonic stem cells, autonomous MusD retrotransposons are epigenetically suppressed to a greater degree than non-autonomous ETn retrotransposons, illustrated by a higher level of DNA methylation and a lower level of active histone modifications. I hypothesize that MusD elements may be silenced by DNA methylation and repressive chromatin spreading into the LTR from the CpG-rich internal retroviral sequence absent in ETn elements. I propose that internal structure largely devoid of high CG content enables ETn elements to evade host-imposed transcriptional repression, contributing to their high mutagenic activity in the mouse germline.

Long terminal repeat (LTR) retrotransposons account for approximately 10% of mouse and 8% of human genomes and may play a role in modifying gene expression. Many species harbor retrotransposon families encompassing both autonomous and non-autonomous members. Specifically, the mouse Early Transposon (ETn) family members lack all retroviral genes but are transcriptionally and retrotranspositionally active, causing over 20 known insertional germline mutations. ETns owe their retrotransposition potential to proteins encoded by structurally intact MusD retrotransposons with whom they share LTRs. ETn elements are transcribed at a much higher level than MusD retrotransposons in embryos and undifferentiated cells, suggesting their evasion of host restriction mechanisms. However, mechanisms responsible for the replicative success of non-autonomous retrotransposon subfamilies over their coding-competent relatives are poorly understood. In the first stage of my research, I analyzed regulatory sequences in an ETn LTR responsible for its high promoter activity in the undifferentiated cell line P19. I found that three GC-boxes that may function as Sp1/Sp3 binding sites act synergistically and are indispensable for undifferentiated cell-specific promoter activity of the LTR. Sp1 binding partners may be responsible for the restricted ETn expression. Moreover, I have shown that unlike many retroviruses, ETn elements possess multiple transcription initiation sites and that they have amplified via intracellular retrotransposition in the P19 teratocarcinoma cell line. In the next step of my research, I performed analysis of epigenetic mechanisms as a means of ERV suppression. Specifically, I showed that in embryonic stem cells, autonomous MusD retrotransposons are epigenetically suppressed to a greater degree than non-autonomous ETn retrotransposons, illustrated by a higher level of DNA methylation and a lower level of active histone modifications. I hypothesize that MusD elements may be silenced by DNA methylation and repressive chromatin spreading into the LTR from the CpG-rich internal retroviral sequence absent in ETn elements. I propose that internal structure largely devoid of high CG content enables ETn elements to evade host-imposed transcriptional repression, contributing to their high mutagenic activity in the mouse germline.

Long terminal repeat (LTR) retrotransposons account for approximately 10% of mouse and 8% of human genomes and may play a role in modifying gene expression. Many species harbor retrotransposon families encompassing both autonomous and non-autonomous members. Specifically, the mouse Early Transposon (ETn) family members lack all retroviral genes but are transcriptionally and retrotranspositionally active, causing over 20 known insertional germline mutations. ETns owe their retrotransposition potential to proteins encoded by structurally intact MusD retrotransposons with whom they share LTRs. ETn elements are transcribed at a much higher level than MusD retrotransposons in embryos and undifferentiated cells, suggesting their evasion of host restriction mechanisms. However, mechanisms responsible for the replicative success of non-autonomous retrotransposon subfamilies over their coding-competent relatives are poorly understood. In the first stage of my research, I analyzed regulatory sequences in an ETn LTR responsible for its high promoter activity in the undifferentiated cell line P19. I found that three GC-boxes that may function as Sp1/Sp3 binding sites act synergistically and are indispensable for undifferentiated cell-specific promoter activity of the LTR. Sp1 binding partners may be responsible for the restricted ETn expression. Moreover, I have shown that unlike many retroviruses, ETn elements possess multiple transcription initiation sites and that they have amplified via intracellular retrotransposition in the P19 teratocarcinoma cell line. In the next step of my research, I performed analysis of epigenetic mechanisms as a means of ERV suppression. Specifically, I showed that in embryonic stem cells, autonomous MusD retrotransposons are epigenetically suppressed to a greater degree than non-autonomous ETn retrotransposons, illustrated by a higher level of DNA methylation and a lower level of active histone modifications. I hypothesize that MusD elements may be silenced by DNA methylation and repressive chromatin spreading into the LTR from the CpG-rich internal retroviral sequence absent in ETn elements. I propose that internal structure largely devoid of high CG content enables ETn elements to evade host-imposed transcriptional repression, contributing to their high mutagenic activity in the mouse germline. / Medicine, Faculty of / Medical Genetics, Department of / Graduate

Thesis advisor: Welkin E. Johnson / Endogenous retroviruses (ERVs) make up a significant portion of vertebrate genomes, and serve as a fossil record of past retroviral infections. Although most ERV genes acquire inactivating mutations over time, some loci retain open reading frames (ORFs) across one or more of the viral genes. The ERV-Fc family, for example, endogenized in multiple mammalian hosts 10 to 30 million years ago, yet many copies maintain intact ORFs corresponding to the env gene, including loci in humans (HERV-Fc1-env) and baboons (babERV-Fc2-env). We previously identified intact ERV-Fc-related env sequences in eight additional mammalian species: chimpanzee, bonobo, aardvark, grey mouse lemur, squirrel monkey, marmoset, dog, and panda. Here we present the results of our assays of expression of these full-length Env proteins. We found that most of the precursors were not cleaved to form the functional surface (SU) and transmembrane (TM) subunits, even when a canonical furin cleavage site was still intact. An exception was babERV-Fc2, in which reconstruction of the cleavage site led to cleavage into SU and TM subunits. Furthermore, removal of 22 residues from the C-terminus of the cytoplasmic tail of babERV-Fc2 enhanced syncytia formation and the ability of babERV-Fc2 pseudotyped virions to infect 293T cells, suggesting the presence of an R-peptide cleavage mechanism. A survey of a small panel of cells revealed that only human cell lines were infectable by babERV-Fc2 pseudotyped murine leukemia virus (MLV) particles, whereas cells of old world monkey, canine, feline and chicken origin were not susceptible to infection. Ectopic expression of native Env codon optimized babERV-Fc2 Env can also inhibit infection by reconstructed babERV-Fc2 pseudotyped virus, raising the possibility that the endogenous glycoprotein encoded in the baboon genome may function as a viral entry inhibitor. Our results suggest that exaptation of ERV Env proteins as antiviral defense genes involves a combination of selective pressures: selection to preserve the receptor-binding and receptor interference functions of Env, but also selection to eliminate the membrane fusion related functions. / Thesis (PhD) — Boston College, 2018. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Biology.

Les lymphocytes T CD4 naïfs sont des cellules plastiques, capables de moduler finement leur programmation selon les signaux environnementaux qu'ils intègrent. Ils adaptent ainsi leur phénotype et leur fonction au type de danger Lors d'une infection par un agent pathogène intracellulaire par exemple, ils acquièrent un phénotype Th1 sous l'influence de médiateurs solubles tels que l'IL-12 et l' IFN-γ. Ces signaux mobilisent un set restreint de facteurs de transcription, coordonné par Tbet, qui programment la cellule afin qu'elle induise l'élimination du danger par des mécanismes impliquant une production massive d'IFN-γ. En réponse à des allergènes ou à des parasites extracellulaires, les lymphocytes T peuvent aussi acquérir un phénotype Th2, caractérisé par l'expression du facteur de transcription Gata-3 et par la production d'IL-4, d'IL-5 et d'IL-13. Afin de garantir la stabilité des lignages, ces processus de différenciation peuvent s'accompagner d'une perte de potentialité. Contrairement aux cellules T naïves, les cellules Th1 sont par exemple incapables d'allumer le programme d'expression génique Th2 en présence d'IL-4, et les lymphocytes Th2 verrouillent le programme Th1. Si nous savons aujourd'hui que l'acquisition des fonctions effectrices, comme l'équilibre entre détermination cellulaire et plasticité, sont régulés par des mécanismes épigénétiques, la plupart des acteurs moléculaires qui contrôlent la programmation des lymphocytes T au niveau de la chromatine reste encore à identifier. Durant ma thèse, j'ai étudié le rôle de la lysine méthyltransférase SETDB1, qui catalyse la di- ou tri-méthylation de la lysine 9 de l'histone 3 (H3K9me3), dans la différenciation des lymphocytes T CD4. Il avait déjà été proposé qu'H3K9me3 ait un impact sur la programmation de ces cellules en réponse aux signaux de l'environnement, mais personne n'avait encore étudié le rôle de SETDB1 dans ces processus lorsque j'ai commencé ma thèse. A l'aide d'une lignée murine déficiente pour SETDB1 spécifiquement dans les lymphocytes T, nous avons montré in vitro et in vivo que la balance Th1/Th2 est fortement augmentée en l'absence de l'enzyme, et que cette dérégulation résulte d'une perte de répression du réseau génique Th1. [...] / Upon activation, naïve CD4 T cells differentiate into distinct helper or regulatory T cell subsets depending on environmental signals received. This process relies on complex and lineage-specific gene expression programs whose dynamics and stability are regulated at the level of the chromatin. The epigenetic pathways involved, however, remain largely unknown. Here, we report that the histone methyltransferase SETDB1 critically controls the Th1 gene expression program. SETDB1-deficient naïve CD4 T cells show exacerbated Th1 priming, and when exposed to a Th1-instructive signal, SETDB1-deficient Th2 cells cross lineage boundaries and transdifferentiate into Th1 cells. Surprisingly, SETDB1 does not appear to control Th1 gene promoter activity. Instead, it deposits the repressive H3K9me3 mark at a restricted and cell-type specific set of endogenous retroviruses (ERVs) strongly associated with genes involved in immune processes. Refined bioinformatic analyses indicated that these retrotransposons either flank and repress Th1 gene cis-regulatory elements or behave themselves as Th1 gene enhancers. In conclusion, H3K9me3 deposition by SETDB1 ensures T cell lineage integrity by repressing a repertoire of ERVs that have been exapted into cis-regulatory modules to shape and control the Th1 gene network.

<p>Energy recovering techniques for air conditioning has increased in recent years and new prod- </p><p>ucts have been introduced to the market where the Membrane-based Energy Recovery Ventilator </p><p>(ERV) is one promising product. The aim of this study was to evaluate a new type of membrane </p><p>material for an ERV and give an analysis of the need for digital control of the air flow rate to </p><p>improve efficiency. A prototype counter-flow ERV was used in the test to validate the performance under different </p><p>flow conditions. The result was promising for the tested membrane material with high moisture </p><p>and heat transfer. The optimisation of the flow rate was found to be superfluous, since the relation </p><p>between the energy transferred by the ERV and the air flow rate was almost linear.</p>

Energy recovering techniques for air conditioning has increased in recent years and new prod- ucts have been introduced to the market where the Membrane-based Energy Recovery Ventilator (ERV) is one promising product. The aim of this study was to evaluate a new type of membrane material for an ERV and give an analysis of the need for digital control of the air flow rate to improve efficiency. A prototype counter-flow ERV was used in the test to validate the performance under different flow conditions. The result was promising for the tested membrane material with high moisture and heat transfer. The optimisation of the flow rate was found to be superfluous, since the relation between the energy transferred by the ERV and the air flow rate was almost linear.

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