Thermal exchanges during sleep in anhidrotic ectodermal dysplasia

Anhidrotic ectodermal dysplasia is a congenital syndrome characterized by the absence of sweat glands. A sweating test was performed on such a patient and proved his inability to sweat. Thermal exchanges during night sleep were then measured in this patient and compared with data obtained from a healthy control subject. Ambient conditions were as follows: dry bulb temperature 32.2 degrees C, relative humidity 30%-40%, wind speed 0.7 m.s-1. Polysomnographic recordings showed normal sleep patterns in both subjects, but a "first night effect" in the patient. Rectal (Tre) and mean skin (Tsk) temperatures and loss of mass were monitored continuously throughout the 8-h sleep recording. Loss of mass averaged 34.1 g.h-1 in the patient vs 78.1 g.h-1 in the control subject. No relationship with sleep stages was observed in the patient, in contrast to the control subject who experienced a decrease in evaporation during rapid eye movement sleep. Body temperatures varied little in the patient, but decreased until the 6th h of sleep in the control subject. On two occasions there was a 0.3 degrees C fall in the Tre of the patient during two slow wave sleep (SWS) phases, while Tsk and loss of mass did not change. As thermolytic processes had not varied on these two occasions, it was concluded that the fall in Tre indicated a concomitant decrease in metabolic heat production, in agreement with the assumption that SWS represented a state of energy conservation.     

Ultrastructure du labium de la larve du Speophyes lucidulus delarouzeei (Coleoptera,Catopidae)

We successively examined the two main parts of the labium: the ligula and the palps. The organs located on the ligula have a simple innervation and may represent various types of mechanoreceptors. The palps are crowned by 13 different sensilla which have various receptions (mechanoreception, olfaction, gustation). Several described sensilla hold an unknown function.     

LOW THERMAL LIMIT OF GROWTH RATE OF SYMBIODINIUM CALIFORNIUM (DINOPHYTA) IN CULTURE MAY RESTRICT THE SYMBIONT TO SOUTHERN POPULATIONS OF ITS HOST ANEMONES (ANTHOPLEURA SPP.; ANTHOZOA,CNIDARIA)1

Symbiodinium californium (#383, Banaszak et al. 1993 ) is one of two known dinoflagellate symbionts of the intertidal sea anemones Anthopleura elegantissima, A. xanthogrammica, and A. sola and occurs only in hosts at southern latitudes of the North Pacific. To investigate if temperature restricts the latitudinal distribution of S. californium, growth and photosynthesis at a range of temperatures (5°C–30°C) were determined for cultured symbionts. Mean specific growth rates were the highest between 15°C and 28°C (μ 0.21–0.26 · d^?1) and extremely low at 5, 10, and 30°C (0.02–0.03 · d^?1). Average doubling times ranged from 2.7 d (20°C) to 33 d (5, 10, and 30°C). Cells cultured at 10°C had the greatest cell volume (821 μm³) and the highest percentage of motile cells (64.5%). Growth and photosynthesis were uncoupled; light‐saturated maximum photosynthesis (P_max) increased from 2.9 pg C · cell^?1 · h^?1 at 20°C to 13.2 pg C · cell^?1 · h^?1 at 30°C, a 4.5‐fold increase. Less than 11% of daily photosynthetically fixed carbon was utilized for growth at 5, 10, and 30°C, indicating the potential for high carbon translocation at these temperatures. Low temperature effects on growth rate, and not on photosynthesis and cell morphology, may restrict the distribution of S. californium to southern populations of its host anemones.     

Relation between colonic proglucagon expression and metabolic response to oligofructose in high fat diet-fed mice

Several data suggest that fermentable dietary fiber could play a role in the control of obesity and associated metabolic disorders. The aim of this study was to investigate the putative role of short chain fructo-oligosaccharide (OFS) - a non-digestible oligosaccharide - in mice fed a standard diet and in mice fed two distinct high fat diets inducing metabolic disorders associated to obesity. We confirmed, in mice, several effects previously shown in rats fed a standard diet enriched with OFS, namely an increase in total and empty caecum weight, a significant decrease in epididymal fat mass, and an increase in colonic and portal plasma glucagon-like peptide-1 (GLP-1), a phenomenon positively correlated with a higher colonic proglucagon mRNA level. Curiously, 4-week treatment with OFS added at the same dose induced different effects when added in the two different high fat diets. OFS decreased energy intake, body weight gain, glycemia, and epididymal fat mass only when added together with the high fat-carbohydrate free diet, in which OFS promoted colonic proglucagon expression and insulin secretion. Our results support an association between the increase in proglucagon expression in the proximal colon and OFS effects on glycemia, fat mass development, and/or body weight gain. In conclusion, dietary oligosaccharides would constitute an interesting class of dietary fibers promoting, in certain conditions, endogenous GLP-1 production, with beneficial physiological consequences. This remains to be proven in human studies.     

ELLIPTOCHLORIS MARINA SP. NOV. (TREBOUXIOPHYCEAE,CHLOROPHYTA), SYMBIOTIC GREEN ALGA OF THE TEMPERATE PACIFIC SEA ANEMONES ANTHOPLEURA XANTHOGRAMMICA AND A. ELEGANTISSIMA (ANTHOZOA,CNIDARIA)1

Symbiotic green algae from two species of intertidal Pacific sea anemones, Anthopleura elegantissima and Anthopleura xanthogrammica, were collected from the northeastern Pacific coast of North America across the known range of the symbiont. Freshly isolated Anthopleura symbionts were used for both morphological and molecular analyses because Anthopleura symbiont cultures were not available. Light and transmission electron microscopy supported previous morphological studies, showing the symbionts consist of spherical unicells from 5 to 10 μm in diameter, with numerous vesicles, and a single bilobed chloroplast. Pyrenoids were not seen in LM, but a thylakoid‐free area was observed in TEM, consistent with previous findings. Many algal cells extracted from fresh anemone tissue were observed in the process of division, producing two autospores within a maternal cell wall. The morphology of the green symbionts matches that of Elliptochloris Tscherm.‐Woess. Molecular phylogenetic analyses of the nuclear SSU rDNA and the plastid encoded gene for the large subunit of RUBISCO (rbcL) support the monophyly of these green algal symbionts, regardless of host species and geographic origin. Phylogenetically, sequences of the Anthopleura symbionts are nested within the genus Elliptochloris and are distinct from sequences of all other Elliptochloris spp. examined. Given the ecological and phylogenetic distinctions among the green algal symbionts in Anthopleura spp. and the named species of Elliptochloris, we designate the green algal symbionts as a new species, Elliptochloris marina (Trebouxiophyceae, Chlorophyta).     

The cytosolic domain of human Tom22 modulates human Bax mitochondrial translocation and conformation in yeast

The role of the mitochondrial protein receptor Tom22p in the interaction of pro-apoptotic protein Bax with yeast mitochondria was investigated. Co-immunoprecipitation assays showed that human Bax interacted with different TOM subunits, including Tom22p. Expression of the cytosolic receptor domain of human Tom22 increased Bax mitochondrial localization, but decreased the proportion of active Bax. BN-PAGE showed that the cytosolic domain of Tom22 interfered with the oligomerization of Bax. These data suggest that the interaction with the cytosolic domain of Tom22 helps Bax to acquire a conformation able to interact with the outer mitochondrial membrane.     

Distinctive Serum miRNA Profile in Mouse Models of Striated Muscular Pathologies

Biomarkers are critically important for disease diagnosis and monitoring. In particular, close monitoring of disease evolution is eminently required for the evaluation of therapeutic treatments. Classical monitoring methods in muscular dystrophies are largely based on histological and molecular analyses of muscle biopsies. Such biopsies are invasive and therefore difficult to obtain. The serum protein creatine kinase is a useful biomarker, which is however not specific for a given pathology and correlates poorly with the severity or course of the muscular pathology. The aim of the present study was the systematic evaluation of serum microRNAs (miRNAs) as biomarkers in striated muscle pathologies. Mouse models for five striated muscle pathologies were investigated: Duchenne muscular dystrophy (DMD), limb-girdle muscular dystrophy type 2D (LGMD2D), limb-girdle muscular dystrophy type 2C (LGMD2C), Emery-Dreifuss muscular dystrophy (EDMD) and hypertrophic cardiomyopathy (HCM). Two-step RT-qPCR methodology was elaborated, using two different RT-qPCR miRNA quantification technologies. We identified miRNA modulation in the serum of all the five mouse models. The most highly dysregulated serum miRNAs were found to be commonly upregulated in DMD, LGMD2D and LGMD2C mouse models, which all exhibit massive destruction of striated muscle tissues. Some of these miRNAs were down rather than upregulated in the EDMD mice, a model without massive myofiber destruction. The dysregulated miRNAs identified in the HCM model were different, with the exception of one dysregulated miRNA common to all pathologies. Importantly, a specific and distinctive circulating miRNA profile was identified for each studied pathological mouse model. The differential expression of a few dysregulated miRNAs in the DMD mice was further evaluated in DMD patients, providing new candidates of circulating miRNA biomarkers for DMD.     

Clinical and genetic heterogeneity in laminopathies

Mutations in the LMNA gene encoding lamins A/C are responsible for more than ten different disorders called laminopathies which affect various tissues in an isolated (striated muscle, adipose tissue or peripheral nerve) or systemic (premature aging syndromes) fashion. Overlapping phenotypes are also observed. Associated with this wide clinical variability, there is also a large genetic heterogeneity, with 408 different mutations being reported to date. Whereas a few hotspot mutations emerge for some types of laminopathies, relationships between genotypes and phenotypes remain poor for laminopathies affecting the striated muscles. In addition, there is important intrafamilial variability, explained only in a few cases by digenism, thus suggesting an additional contribution from modifier genes. In this regard, a chromosomal region linked to the variability in the age at onset of myopathic symptoms in striated muscle laminopathies has recently been identified. This locus is currently under investigation to identify modifier variants responsible for this variability.     

A centronuclear myopathy--dynamin 2 mutation impairs autophagy in mice

Dynamin 2 (Dnm2) is involved in endocytosis and intracellular membrane trafficking through its function in vesicle formation from distinct membrane compartments. Heterozygous (HTZ) mutations in the DNM2 gene cause dominant centronuclear myopathy or Charcot-Marie-Tooth neuropathy. We generated a knock-in Dnm2R465W mouse model expressing the most frequent human mutation and recently reported that HTZ mice progressively developed a myopathy. We investigated here the cause of neonatal lethality occurring in homozygous (HMZ) mice. We show that HMZ mice present at birth with a reduced body weight, hypoglycemia, increased liver glycogen content and hepatomegaly, in agreement with a defect in neonatal autophagy. In vitro studies performed in HMZ embryonic fibroblasts point out to a decrease in the autophagy flux prior to degradation at the autolysosome. We show that starved HMZ cells have a higher number of immature autophagy-related structures probably due to a defect of acidification. Our results highlight the role of Dnm2 in the cross talk between endosomal and autophagic pathways and evidence a new role of Dnm2-dependent membrane trafficking in autophagy which may be relevant in DNM2-related human diseases.