E cadherin appears to be an essential on/off switch for initiating bile canaliculi formation.

The mechanisms underlying cell polarization are fundamental to biology but remain incompletely understood. This is especially true for hepatocytes, which display a particularly complex polarization that enables the formation of the bile canaliculi (BC) network crucial for liver excretory functions. To identify key proteins involved in hepatocyte polarization, BC formation, structure or function, we employed a proteomic approach comparing the human hepatocyte cell line HepG2 to its sub clone HepG2/C3A known for its markedly greater efficiency in forming mature BCs.

Variation in albumin glycation rates in birds suggests resistance to relative hyperglycaemia rather than conformity to the pace of life syndrome hypothesis.

The pace of life syndrome (POLS) hypothesis suggests that organisms' life history and physiological and behavioural traits should co-evolve. In this framework, how glycaemia (i.e.

The cell origin of reactive oxygen species and its implication for evolutionary trade-offs.

The allocation of resources in animals is shaped by adaptive trade-offs aimed at maximizing fitness. At the heart of these trade-offs, lies metabolism and the conversion of food resources into energy, a process mostly occurring in mitochondria. Yet, the conversion of nutrients to utilizable energy molecules (adenosine triphosphate) inevitably leads to the by-production of reactive oxygen species (ROS) that may cause damage to important biomolecules such as proteins or lipids.

Novel model organisms and proteomics for a better biological understanding.

The concept of « model organisms » is being revisited in the light of the latest advances in multi-omics technologies that can now capture the full range of molecular events that occur over time, regardless of the organism studied. Classic, well-studied models, such as Escherichia coli, Saccharomyces cerevisiae, to name a few, have long been valuable for hypothesis testing, reproducibility, and sharing common platforms among researchers. However, they are not suitable for all types of research.

Ready to dive? Early constraints help juvenile southern elephant seals (Mirounga leonina) acclimatize to aquatic life.

Breath-holding foraging implies different adaptations to limit oxygen (O2) depletion and maximize foraging time. Physiological adjustments can be mediated through O2 consumption, driven by muscle mitochondria, which can also produce reactive oxygen species during reoxygenation. Southern elephant seals spend months foraging at sea, diving for up to 1 h.

Fieldwork on animals living in extreme conditions as a source of biomedical innovation.

Most biomedical research on animals is based on the handful of the so-called standard model organisms, i.e. laboratory mice, rats or , but the keys to some important biomedical questions may simply not be found in these.

Reduced ATP turnover during hibernation in relaxed skeletal muscle.

Hibernating brown bears, due to a drastic reduction in metabolic rate, show only moderate muscle wasting. Here, we evaluate if ATPase activity of resting skeletal muscle myosin can contribute to this energy sparing. By analyzing single muscle fibers taken from the same bears, either during hibernation or in summer, we find that fibers from hibernating bears have a mild decline in force production and a significant reduction in ATPase activity.

The role of microRNA in the regulation of hepatic metabolism and energy-expensive processes in the hibernating dormouse.

The garden dormouse (Eliomys quercinus) is a fat-storing mammal that undergoes annual periods of hibernation to mitigate the effects of food scarcity, low ambient temperatures, and reduced photoperiod that characterize winter. Like other hibernating species, this animal suppresses its metabolic rate by downregulating nonessential genes and processes in order to prolong available energy stores and limit waste accumulation throughout the season. MicroRNAs (miRNAs) are short, single-stranded, noncoding RNAs that bind to mRNA and mediate post-transcriptional suppression, making miRNA ideal for modulating widespread changes in gene expression, including global downregulation typified by metabolic rate depression.

Glycation resistance and life-history traits: lessons from non-conventional animal models.

Glycation reactions play a key role in the senescence process and are involved in numerous age-related pathologies, such as diabetes complications or Alzheimer's disease. As a result, past studies on glycation have mostly focused on human and laboratory animal models for medical purposes. Very little is known about glycation and its link to senescence in wild animal species.

Molecular fingerprint of gilthead seabream physiology in response to pollutant mixtures in the wild.

The increase in trace element concentrations in the aquatic environment due to anthropogenic activities, urges the need for their monitoring and potential toxicity, persistence, bioaccumulation, and biomagnification at different trophic levels. Gilthead seabream is a species of commercial importance in the Mediterranean Sea, both for the aquaculture and fisheries sectors, however very little is known about their trace element contamination accumulation and the resulting effect on their health status. In the present study, 135 juveniles were collected from seven coastal lagoons known to be essential nursery areas for this species.

Diversifying the concept of model organisms in the age of -omics.

In today's post-genomic era, it is crucial to rethink the concept of model organisms. While a few historically well-established organisms, e.g.

Honey Bee Larval Hemolymph as a Source of Key Nutrients and Proteins Offers a Promising Medium for Artificial Rearing.

, a major ectoparasite of the Western honey bee , is a widespread pest that damages colonies in the Northern Hemisphere. Throughout their lifecycle, females feed on almost every developmental stage of their host, from the last larval instar to the adult. The parasite is thought to feed on hemolymph and fat body, although its exact diet and nutritional requirements are poorly known.

Toward countering muscle and bone loss with spaceflight: GSK3 as a potential target.

We examined the effects of ∼30 days of spaceflight on glycogen synthase kinase 3 (GSK3) content and inhibitory serine phosphorylation in murine muscle and bone samples from four separate missions (BION-M1, rodent research [RR]1, RR9, and RR18). Spaceflight reduced GSK3β content across all missions, whereas its serine phosphorylation was elevated with RR18 and BION-M1. The reduction in GSK3β was linked to the reduction in type IIA fibers commonly observed with spaceflight as these fibers are particularly enriched with GSK3.

Induction of ATF4-Regulated Atrogenes Is Uncoupled from Muscle Atrophy during Disuse in Halofuginone-Treated Mice and in Hibernating Brown Bears.

Activating transcription factor 4 (ATF4) is involved in muscle atrophy through the overexpression of some atrogenes. However, it also controls the transcription of genes involved in muscle homeostasis maintenance. Here, we explored the effect of ATF4 activation by the pharmacological molecule halofuginone during hindlimb suspension (HS)-induced muscle atrophy.

Both age and social environment shape the phenotype of ant workers.

Position within the social group has consequences on individual lifespans in diverse taxa. This is especially obvious in eusocial insects, where workers differ in both the tasks they perform and their aging rates. However, in eusocial wasps, bees and ants, the performed task usually depends strongly on age.

Resistance to glycation in the zebra finch: Mass spectrometry-based analysis and its perspectives for evolutionary studies of aging.

In humans, hyperglycemia is associated with protein glycation, which may contribute to aging. Strikingly, birds usually outlive mammals of the same body mass, while exhibiting high plasma glucose levels. However, how birds succeed in escaping pro-aging effects of glycation remains unknown.

Molecular Liver Fingerprint Reflects the Seasonal Physiology of the Grey Mouse Lemur () during Winter.

Grey mouse lemurs () are primates that respond to environmental energetic constraints through strong physiological seasonality. They notably fatten during early winter (EW), and mobilize their lipid reserves while developing glucose intolerance during late winter (LW), when food availability is low. To decipher how the hepatic mechanisms may support such metabolic flexibility, we analyzed the liver proteome of adult captive male mouse lemurs, whose seasonal regulations are comparable to their wild counterparts.

Hibernating brown bears are protected against atherogenic dyslipidemia.

To investigate mechanisms by which hibernators avoid atherogenic hyperlipidemia during hibernation, we assessed lipoprotein and cholesterol metabolisms of free-ranging Scandinavian brown bears (Ursus arctos). In winter- and summer-captured bears, we measured lipoprotein sizes and sub-classes, triglyceride-related plasma-enzyme activities, and muscle lipid composition along with plasma-levels of antioxidant capacities and inflammatory markers. Although hibernating bears increased nearly all lipid levels, a 36%-higher cholesteryl-ester transfer-protein activity allowed to stabilize lipid composition of high-density lipoproteins (HDL).

Concurrent BMP Signaling Maintenance and TGF-β Signaling Inhibition Is a Hallmark of Natural Resistance to Muscle Atrophy in the Hibernating Bear.

Muscle atrophy arises from a multiplicity of physio-pathological situations and has very detrimental consequences for the whole body. Although knowledge of muscle atrophy mechanisms keeps growing, there is still no proven treatment to date. This study aimed at identifying new drivers for muscle atrophy resistance.

Cardiomyocyte Protection by Hibernating Brown Bear Serum: Toward the Identification of New Protective Molecules Against Myocardial Infarction.

Ischemic heart disease remains one of the leading causes of death worldwide. Despite intensive research on the treatment of acute myocardial infarction, no effective therapy has shown clinical success. Therefore, novel therapeutic strategies are required to protect the heart from reperfusion injury.

Daytime Restricted Feeding Affects Day-Night Variations in Mouse Cerebellar Proteome.

The cerebellum harbors a circadian clock that can be shifted by scheduled mealtime and participates in behavioral anticipation of food access. Large-scale two-dimensional difference gel electrophoresis (2D-DIGE) combined with mass spectrometry was used to identify day-night variations in the cerebellar proteome of mice fed either during daytime or nighttime. Experimental conditions led to modified expression of 89 cerebellar proteins contained in 63 protein spots.