University of Geneva

About: University of Geneva is a education organization based out in Geneva, Switzerland. It is known for research contribution in the topics: Population & Galaxy. The organization has 26887 authors who have published 65265 publications receiving 2931373 citations. The organization is also known as: Geneva University & Universite de Geneve.

Bidirectional promoters generate pervasive transcription in yeast

Abstract: Genome-wide pervasive transcription has been reported in many eukaryotic organisms, revealing a highly interleaved transcriptome organization that involves hundreds of previously unknown non-coding RNAs. These recently identified transcripts either exist stably in cells (stable unannotated transcripts, SUTs) or are rapidly degraded by the RNA surveillance pathway (cryptic unstable transcripts, CUTs). One characteristic of pervasive transcription is the extensive overlap of SUTs and CUTs with previously annotated features, which prompts questions regarding how these transcripts are generated, and whether they exert function. Single-gene studies have shown that transcription of SUTs and CUTs can be functional, through mechanisms involving the generated RNAs or their generation itself. So far, a complete transcriptome architecture including SUTs and CUTs has not been described in any organism. Knowledge about the position and genome-wide arrangement of these transcripts will be instrumental in understanding their function. Here we provide a comprehensive analysis of these transcripts in the context of multiple conditions, a mutant of the exosome machinery and different strain backgrounds of Saccharomyces cerevisiae. We show that both SUTs and CUTs display distinct patterns of distribution at specific locations. Most of the newly identified transcripts initiate from nucleosome-free regions (NFRs) associated with the promoters of other transcripts (mostly protein-coding genes), or from NFRs at the 3' ends of protein-coding genes. Likewise, about half of all coding transcripts initiate from NFRs associated with promoters of other transcripts. These data change our view of how a genome is transcribed, indicating that bidirectionality is an inherent feature of promoters. Such an arrangement of divergent and overlapping transcripts may provide a mechanism for local spreading of regulatory signals-that is, coupling the transcriptional regulation of neighbouring genes by means of transcriptional interference or histone modification.

LTP promotes formation of multiple spine synapses between a single axon terminal and a dendrite

Abstract: Structural remodelling of synapses and formation of new synaptic contacts has been postulated as a possible mechanism underlying the late phase of long-term potentiation (LTP), a form of plasticity which is involved in learning and memory Here we use electron microscopy to analyse the morphology of synapses activated by high-frequency stimulation and identified by accumulated calcium in dendritic spines LTP induction resulted in a sequence of morphological changes consisting of a transient remodelling of the postsynaptic membrane followed by a marked increase in the proportion of axon terminals contacting two or more dendritic spines Three-dimensional reconstruction revealed that these spines arose from the same dendrite As pharmacological blockade of LTP prevented these morphological changes, we conclude that LTP is associated with the formation of new, mature and probably functional synapses contacting the same presynaptic terminal and thereby duplicating activated synapses

Recommendations for a nomenclature system for human gene mutations

Abstract: This document has been written in response to meetings on “Locus-specific Mutation Databases” held on March 24, 1996 in Heidelberg, Germany and “Mutation Databases” on October 29, 1996 in San Francisco, California. As a chairperson of the Nomenclature committee, the first author had accepted the task of preparing and circulating a document with recommendations for debate, further discussions and most importantly for final approval/acceptance at the October 1996 meeting in San Francisco. Four drafts of this document (August 5, 1996, September 5, 1996, November 29, 1996, and May 29, 1997) were distributed to a number of investigators, the majority of whom were co-authors in the Beaudet et al, 1996 and Beutler et al, 1996 papers. This document contains modifications according to their suggestions, opinions and criticisms. Furthermore, many colleagues had offered suggestions, criticisms, and ideas through electronic communication. During the October 1996 meeting in San Francisco, there was a sufficient discussion of these recommendations and it was agreed that another, further modified draft of the document would be posted on the “World Wide Web” for final debate for a period of several weeks. This present document is also the result of all of these discussions and was approved during that October 27, 1997 meeting in Baltimore. Two manuscripts were recently published in “Human Mutation” that contain mutation nomenclature recommendations (Beaudet et al., 1996 and Beutler et al., 1996). These documents present the views of the authors after discussions during the October 19, 1994, Montreal, and the October 24-25, 1995 Minneapolis meetings. Other previously published papers/ letters on nomenclature issues include the following: Beaudet & Tsui, 1993; Beutler, 1993; Antonarakis & McKusick, 1994. It is obvious that the most unambiguous nomenclature system is that based on genomic DNA. Even Received 5 September 1997; accepted 3 October 1997.

Coat Proteins and Vesicle Budding

Abstract: The trafficking of proteins within eukaryotic cells is achieved by the capture of cargo and targeting molecules into vesicles that bud from a donor membrane and deliver their contents to a receiving compartment. This process is bidirectional and may involve multiple organelles within a cell. Distinct coat proteins mediate each budding event, serving both to shape the transport vesicle and to select by direct or indirect interaction the desired set of cargo molecules. Secretion, which has been viewed as a default pathway, may require sorting and packaging signals on transported molecules to ensure their rapid delivery to the cell surface.