Bringing obesity to light: Rev-erbα, a central player in light-induced adipogenesis in the zebrafish?

Background:Recent studies have led to an expansion of potential factors capable of stimulating obesity. Increasing evidence indicates that environmental factors, including disturbance of circadian rhythms, also contribute to its etiology.Objectives:To determine the effects of altered circadian rhythms on adipogenesis and to better understand how circadian and adipogenic regulatory pathways are linked, zebrafish larvae were exposed to various light/dark cycles or hypercaloric feeding (HCF).Methods:Clock and adipogenic gene expression was quantitative real time PCR. Adipogenesis was characterized using coherent anti-Stokes Raman scattering microscopy (CARS) and whole-mount lipid composition was analyzed by gas chromatography. The clock protein Rev-erbα and the adipogenesis-regulating protein Pparγ were localized by immunohistochemistry.Results:Zebrafish larvae exposed to continuous light (LL) had a sevenfold higher prevalence of adipocytes compared with control fish under a 14 h light and 10 h dark cycle. It was also significantly higher compared with that in HCF larvae with control light/dark cycle, which showed a 5.5-fold increase compared with control animals. Although total fatty acid content was unaffected, adipocyte lipid composition was altered in LL zebrafish. In contrast, shifting the onset and duration of the light periods did not affect adipogenesis or total fatty acid content. Gene expression analysis revealed effects of LL and HCF on circadian cyclicity, with increased expression of the clock gene period2 and altered circadian rev-erbα expression in LL larvae. Immunostaining revealed for the first time that Rev-erbα and Pparγ colocalize in adipocytes, which together with the gene expression analysis suggests interplay between Rev-erbα and Ppar isoforms.Conclusions:The amount of light, but not shifted light/dark cycles, affected adipogenesis and lipid composition, possibly due to increased period2 expression, which, in turn, enhances Rev-erbα-regulated gene expression. As the pparβδ promoter includes three Rev-erbα binding sites, we hypothesize that pparβδ may be a direct target that ultimately activates Pparγ

Type I Collagen from Jellyfish Catostylus mosaicus for Biomaterial Applications

Collagen is the predominant protein in animal connective tissues and is widely used in tissue regeneration and other industrial applications. Marine organisms have gained interest as alternative, nonmammalian collagen sources for biomaterial applications because of potential medical and economic advantages. In this work, we present physicochemical and biofunctionality studies of acid solubilized collagen (ASC) from jellyfish Catostylus mosaicus (JASC), harvested from the Persian Gulf, compared with ASC from rat tail tendon (RASC), the industry-standard collagen used for biomedical research. From the protein subunit (alpha chain) pattern of JASC, we identified it as a type I collagen, and extensive molecular spectroscopic analyses showed similar triple helical molecular signatures for JASC and RASC. Atomic force microscopy of fibrillized JASC showed clear fibril reassembly upon pH neutralization though with different temperature and concentration dependence compared with RASC. Molecular (natively folded, nonfibrillized) JASC was shown to functionalize rigid substrates and promote MC3T3 preosteoblast cell attachment and proliferation better than RASC over 6 days. On blended collagen-agarose scaffolds, both RASC and JASC fibrils supported cell attachment and proliferation, and scaffolds with RASC fibrils showed more cell growth after 6 days compared with those scaffolds with JASC fibrils. These results demonstrate the potential for this new type I collagen as a possible alternative to mammalian type I collagen for biomaterial applications. © 2018 American Chemical Society

EXAFS study of rare-earth element coordination in calcite

Extended X-ray absorption fine-structure (EXAFS) spectroscopy is used to characterize the local coordination of selected rare-earth elements (Nd3+, Sm3+, Dy3+, Yb3+) coprecipitated with calcite in minor concentrations from room-temperature aqueous solutions. Fitting results confirm substitution in the Ca site, but first-shell Nd-O and Sm-O distances are longer than the Ca-O distance in calcite and longer than what is consistent with ionic radii sums for sixfold coordination in the octahedral Ca site. In contrast, first-shell Dy-O and Yb-O distances are shorter than the Ca-O distance and are consistent with ionic radii sums for sixfold coordination. Comparison of Nd-O and Sm-O bond lengths with those in lanthanide sesquioxides and with ionic radii trends across the lanthanide series suggests that Nd3+ and Sm3+ have sevenfold coordination in a modified Ca site in calcite. This would require some disruption of the local structure, with an expected decrease in stability, and possibly a different charge compensation mechanism between Nd and Sm vs. Yb and Dy. A possible explanation for the increased coordination for the larger rare-earth elements involves bidentate ligation from a CO3 group. Because trivalent actinides such as Am3+ and Cm3+ have ionic radii similar to Nd3+, their incorporation in calcite may result in a similar defect structure

Perilipin 5 mediated lipid droplet remodelling revealed by coherent Raman imaging

Accumulation of fat in muscle tissue as intramyocellular lipids (IMCLs) is closely related to the development of insulin resistance and subsequent type 2 diabetes. Most IMCLs organize into lipid droplets (LDs), the fates of which are regulated by lipid droplet coat proteins. Perilipin 5 (PLIN5) is an LD coating protein, which is strongly linked to lipid storage in muscle tissue. Here we employ a tandem in vitro/ex vivo approach and use chemical imaging by label-free, hyperspectral coherent Raman microscopy to quantify compositional changes in individual LDs upon PLIN5 overexpression. Our results directly show that PLIN5 overexpression in muscle alters individual LD composition and physiology, resulting in larger LDs with higher esterified acyl chain concentration, increased methylene content, and more saturated lipid species. These results suggest that lipotoxic protection afforded by natural PLIN5 upregulation in muscle involves molecular changes in lipid composition within LDs. This journal is</p