492 research outputs found
Caractérisation structurale et fonctionnelle des ARNtm mitochondriaux de jakobides
Mémoire numérisé par la Direction des bibliothÚques de l'Université de Montréal
Hand gesture recognition for driver vehicle interaction
International audienceIn this paper, we present a new driver vehicle interface based on hand gestures that uses a hierarchical model to minimize resources requirements. Depth information is provided by time of flight sensor with automotive certification. In particular, we develop our implementation of a Random Forest based posture classification in two subcases: micro gestures at the wheel and macro gestures in front of the touch screen
The Pioneering Role of Sci in Post Publication Public Peer Review (P4R)
Scientists observe, discover, justify and eventually share their findings with the scientific
community. Dissemination is an integral aspect of scientific discovery, since discoveries which go
unnoticed have no or little impact on science. Today, peer review is part of this process of scientific
dissemination as it contributes proactively to the quality of a scientific article. As the numbers of
scientific journals and scientific articles published therein are increasing steadily, processes such
as the single-blind or double-blind peer review are facing a near collapse situation. In fact, these
traditional forms of reviewing have reached their limits and, because of this, are also increasingly
considered as unfair, sloppy, superficial and even biased. In this manuscript, we propose forms of
post-publication public peer review (P4R) as valuable alternatives to the traditional blind peer review
system. We describe how the journal Sci has explored such an approach and provide first empirical
evidence of the benefits and also challenges, such a P4R approach faces
ATXR5 and ATXR6 are H3K27 monomethyltransferases required for chromatin structure and gene silencing.
Constitutive heterochromatin in Arabidopsis thaliana is marked by repressive chromatin modifications, including DNA methylation, histone H3 dimethylation at Lys9 (H3K9me2) and monomethylation at Lys27 (H3K27me1). The enzymes catalyzing DNA methylation and H3K9me2 have been identified; alterations in these proteins lead to reactivation of silenced heterochromatic elements. The enzymes responsible for heterochromatic H3K27me1, in contrast, remain unknown. Here we show that the divergent SET-domain proteins ARABIDOPSIS TRITHORAX-RELATED PROTEIN 5 (ATXR5) and ATXR6 have H3K27 monomethyltransferase activity, and atxr5 atxr6 double mutants have reduced H3K27me1 in vivo and show partial heterochromatin decondensation. Mutations in atxr5 and atxr6 also lead to transcriptional activation of repressed heterochromatic elements. Notably, H3K9me2 and DNA methylation are unaffected in double mutants. These results indicate that ATXR5 and ATXR6 form a new class of H3K27 methyltransferases and that H3K27me1 represents a previously uncharacterized pathway required for transcriptional repression in Arabidopsis
Small Molecule Catalysts with Therapeutic Potential
Catalysts are employed in many areas of research and development where they combine high efficiency with often astonishing selectivity for their respective substrates. In biology, biocatalysts are omnipresent. Enzymes facilitate highly controlled, sophisticated cellular processes, such as metabolic conversions, sensing and signalling, and are prominent targets in drug development. In contrast, the therapeutic use of catalysts per se is still rather limited. Recent research has shown that small molecule catalytic agents able to modulate the redox state of the target cell bear considerable promise, particularly in the context of inflammatory and infectious diseases, stroke, ageing and even cancer. Rather than being âactiveâ on their own in a more traditional sense, such agents develop their activity by initiating, promoting, enhancing or redirecting reactions between biomolecules already present in the cell, and their activity therefore depends critically on the predisposition of the target cell itself. Redox catalysts, for instance, preferably target cells with a distinct sensitivity towards changes in an already disturbed redox balance and/or increased levels of reactive oxygen species. Indeed, certain transition metal, chalcogen and quinone agents may activate an antioxidant response in normal cells whilst at the same time triggering apoptosis in cancer cells with a different pre-existing âbiochemical redox signatureâ and closer to the internal redox threshold. In pharmacy, catalysts therefore stand out as promising lead structures, as sensor/effector agents which are highly effective, fairly selective, active in catalytic, i.e., often nanomolar concentrations and also very flexible in their structural design
Unleashing the Biological Potential of Fomes fomentarius via Dry and Wet Milling
Fomes fomentarius, usually referred to as tinder conk, is a common wood-based fungus
rich in many interesting phytochemicals and with an unique porous structure. Dry or wet ball
milling of this sponge on a planetary mill results in small particles with sizes in the range of
10 ”m or below. Suspended in water and without preservatives or other stabilizers, the resulting
micro-suspensions are sterile for around six days, probably due to the increased temperatures of
around 80 âŠC especially during the wet milling process. The suspensions also exhibit excellent
antioxidant activities as determined in the DPPH, ferric reducing antioxidant potential (FRAP) and
2,20
-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. In the DPPH assay, IC50 values
of 0.02â0.04% w/v and 0.04% w/v were observed for dry and wet milled samples, respectively. In
the FRAP assay, IC50 values of <0.02% w/v and 0.04% w/v were observed for dry and wet milled
samples, respectively. In contrast, the ABTS assay provided IC50 values of 0.04% w/v and 0.005%
w/v, respectively. Notably, this activity is mostlyâalbeit not exclusivelyâassociated with the highly
porous particles and their large surfaces, although some active ingredients also diffuse into the
surrounding aqueous medium. Such suspensions of natural particles carrying otherwise insoluble
antioxidants on their surfaces provide an interesting avenue to unleash the antioxidant potential
of materials such as sponges and barks. As dry milling also enables longer storage and transport,
applications in the fields of medicine, nutrition, agriculture, materials and cosmetics are feasible
Selenomethionine: A Pink Trojan Redox Horse with Implications in Aging and Various Age-Related Diseases
Selenium is an essential trace element. Although this chalcogen forms a wide variety of
compounds, there are surprisingly few small-molecule organic selenium compounds (OSeCs) in
biology. Besides its more prominent relative selenocysteine (SeCys), the amino acid selenomethionine
(SeMet) is one example. SeMet is synthesized in plants and some fungi and, via nutrition, finds its way
into mammalian cells. In contrast to its sulfur analog methionine (Met), SeMet is extraordinarily redox
active under physiological conditions and via its catalytic selenide (RSeRâ)/selenoxide (RSe(O)Râ)
couple provides protection against reactive oxygen species (ROS) and other possibly harmful oxidants.
In contrast to SeCys, which is incorporated via an eloquent ribosomal mechanism, SeMet can
enter such biomolecules by simply replacing proteinogenic Met. Interestingly, eukaryotes, such as
yeast and mammals, also metabolize SeMet to a small family of reactive selenium species (RSeS).
Together, SeMet, proteins containing SeMet and metabolites of SeMet form a powerful triad of
redox-active metabolites with a plethora of biological implications. In any case, SeMet and its family
of natural RSeS provide plenty of opportunities for studies in the fields of nutrition, aging, health
and redox biology
A Whiff of Sulfur: One Wind a Day Keeps the Doctor Away
Reactive Sulfur Species (RSS), such as allicin from garlic or sulforaphane from broccoli, are
fre-quently associated with biological activities and possible health benefits in animals and humans.
Among these Organic Sulfur Compounds (OSCs) found in many plants and fungi, the Volatile Sulfur
Compounds (VSCs) feature prominently, not only because of their often-pungent smell, but also
because they are able to access places which solids and solutions cannot reach that easily. Indeed,
inorganic RSS such as hydrogen sulfide (H2S) and sulfur dioxide (SO2
) can be used to lit-erally
fumigate entire rooms and areas. Similarly, metabolites of garlic, such as allyl methyl sulfide (AMS),
are formed metabolically in humans in lower concentrations and reach the airways from inside the
body as part of oneâs breath. Curiously, H2S is also formed in the gastrointestinal tract by gut bacteria,
and the question of if and for which purpose this gas then crosses the barriers and enters the body is
indeed a delicate matter for equally delicate studies. In any case, nature is surprisingly rich in such
VSCs, as fruits (for instance, the infamous durian) demonstrate, and therefore these VSCs represent a
promising group of compounds for further studies
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