Influenza D virus (IDV) has first been identified in 2011 in the USA and was shown to mainly circulate in cattle. While IDV is associated with mild respiratory signs, its prevalence is still unknown. In the present study we show that IDV has been circulating throughout France in cattle and small ruminants, with 47.2% and 1.5% seropositivity, respectively. The high prevalence and moderate pathogenicity of IDV in cattle suggest that it may play an initiating role in the bovine respiratory disease complex.

The mouse HSP70.1 gene, which codes for a heat shock protein (hsp70), is highly transcribed at the onset of zygotic genome activation (ZGA). This expression, which occurs in the absence of stress, is then repressed. It has been claimed that this gene does not exhibit a stress response until the blastocyst stage. The promoter of HSP70.1 contains four heat shock element (HSE) boxes which are the binding sites of heat shock transcription factors (HSF). We have been studying the presence and localization of the mouse HSFs, mHSF1 and mHSF2, at different stages of embryo development. We show that mHSF1 is already present at the one-cell stage and concentrated in the nucleus. Moreover, by mutagenizing HSE sequences and performing competition experiments (in transgenic embryos with the HSP70.1 promoter inserted before a reporter gene), we show that, in contrast with previous findings, HSE boxes are involved in this spontaneous activation. Therefore, we suggest that HSF1 and HSE are important in this transient expression at the two-cell stage and that the absence of typical inducibility at this early stage of development results mainly from the high level of spontaneous transcription of this gene during the ZGA.All organisms respond to proteotoxic stress (heat shock or toxic agent exposure) by the synthesis of a group of proteins called heat shock proteins. Heat shock proteins are classified into different families on the basis of molecular mass (20, 70, and 90 kDa) and distinguished according to their inducibility: some members of heat shock families, such as heat shock cognate (hsc), are constitutively synthesized, whereas others (hsp) are expressed only following stress. Heat shock proteins interact with numerous other proteins, and their main function is the control of the accurate folding and translocation of polypeptides in the different cellular compartments (reviewed by Parsell and Lindquist [38].

Heat shock genes are found in all organisms, and synthesis of heat shock proteins is induced by various stressors in nearly all the cells forming these organisms. However, a particular situation is noticed for hsp 70 genes in mouse embryos at the beginning of their development. First, spontaneous expression of hsp 70 is observed at the onset of zygotic genome activity. Second, inducible expression is delayed until morula or early blastocyst stages. A better understanding of both these points depends on a more careful analysis of hsp 70 expression in relation to their major regulators, the heat shock factors. In this review, we will see how the development of the preimplantation embryo highlights the complexity of heat shock gene regulation involving trans-cis interactions and the cellular and nuclear environment.

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In L. monocytogenes EGDe, the lmo0501 gene locus encodes a protein similar to the mannitol transcription regulator (MltR) protein in B. subtilis and B. stearothermophilus. In this study we investigated its functional role in L. monocytogenes EGDe cells in view of growth under different stress conditions. Increased lmo0501 gene expression at mRNA level was detected in response to cold, osmotic and organic acid stress exposure. An EGDe Δlmo0501 mutant strain was diminished in growth compared to the wild type strain in minimal defined medium containing either glucose or fructose, as carbon sources. Furthermore the lmo0501 null mutant had retarded growth under cold (4°C), salt (NaCl) and organic acid stress conditions compared to the parental wild type strain. Our results confirm the role of the lmo0501 gene in view of adaptation of L. monocytogenes cells to stress conditions as well as a contribution to the efficient utilization of glucose and fructose as carbon sources.Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-60467 Originally published at: Michel, E. The lmo0501 gene coding for a putative transcription activator protein in Listeria monocytogenes promotes growth under cold, osmotic and acid stress conditions. 2011, University of Zurich, Vetsuisse Faculty.