Lipid droplets in skeletal muscle during grass snake (Natrix natrix L.) development

Comparative proteomic analysis of tail regeneration in the green anole lizard, Anolis carolinensis

As amniote vertebrates, lizards are the most closely related organisms to humans capable of appendage regeneration. Lizards can autotomize, or release their tails as a means of predator evasion, and subsequently regenerate a functional replacement. Green anoles (Anolis carolinensis) can regenerate their tails through a process that involves differential expression of hundreds of genes, which has previously been analyzed by transcriptomic and microRNA analysis. To investigate protein expression in regenerating tissue, we performed whole proteomic analysis of regenerating tail tip and base. This is the first proteomic data set available for any anole lizard. We identified a total of 2,646 proteins - 976 proteins only in the regenerating tail base, 796 only in the tail tip, and 874 in both tip and base. For over 90% of these proteins in these tissues, we were able to assign a clear orthology to gene models in either the Ensembl or NCBI databases. For 13 proteins in the tail base, 9 proteins in the tail tip, and 10 proteins in both regions, the gene model in Ensembl and NCBI matched an uncharacterized protein, confirming that these predictions are present in the proteome. Ontology and pathways analysis of proteins expressed in the regenerating tail base identified categories including actin filament-based process, ncRNA metabolism, regulation of phosphatase activity, small GTPase mediated signal transduction, and cellular component organization or biogenesis. Analysis of proteins expressed in the tail tip identified categories including regulation of organelle organization, regulation of protein localization, ubiquitin-dependent protein catabolism, small GTPase mediated signal transduction, morphogenesis of epithelium, and regulation of biological quality. These proteomic findings confirm pathways and gene families activated in tail regeneration in the green anole as well as identify uncharacterized proteins whose role in regrowth remains to be revealed. This study demonstrates the insights that are possible from the integration of proteomic and transcriptomic data in tail regrowth in the green anole, with potentially broader application to studies in other regenerative models.

New insights into the function of lipid droplet-related proteins and lipid metabolism of salt-stimulated porcine biceps femoris: label-free quantitative phosphoproteomics, morphometry and bioinformatics

BACKGROUND

Lipid droplets (LDs) are important multifunctional organelles responsible for lipid metabolism of postmortem muscle. However, the dynamics in their building blocks (cores and layers) and phosphorylation of lipid droplet-related proteins (LDRPs) regulating meat lipolysis remain unknown at salt-stimulated conditions.

RESULTS

LDRPs extracted from cured porcine biceps femoris (1% and 3% salt) were subjected to label-free quantitative phosphoproteomic analysis and LDs morphological validation. Results indicated that 3% salt curing significantly decreased triglyceride (TG) content with increase in glycerol and decrease in LDs fluorescence compared to 1% salt curing. Comparative phosphoproteomics showed that there were significant changes in phosphorylation at 386 sites on 174 LDRPs between assayed groups (P < 0.05). These differential proteins were mainly involved in lipid and carbohydrate metabolism. Curing of 3% salt induced more site-specific phosphorylation of perilipin 1 (PLIN1, at Ser81) and adipose triglyceride lipase (ATGL, at Ser399) than 1%, whereas the phosphorylation (at Ser600) of hormone-sensitive lipase (HSL) was up-regulated. Ultrastructure imaging showed that LDs were mostly associated with mitochondria, and the average diameter of LDs decreased from 2.34 μm (1% salt) to 1.73 μm (3% salt).

CONCLUSION

Phosphoproteomics unraveled salt-stimulated LDRPs phosphorylation of cured porcine meat provoked intensified lipolysis. Curing of 3% salt allowed an enhanced lipolysis than 1% by up-regulating the phosphorylation sites of LDRPs and recruited lipases. The visible splitting of LDs, together with sarcoplasmic disorganization, supported the lipolysis robustness following 3% salt curing. The finding provides optimization ideas for high-quality production of cured meat products. © 2023 Society of Chemical Industry.

Unique Features of River Lamprey (Lampetra fluviatilis) Myogenesis

The river lamprey (L. fluviatilis) is a representative of the ancestral jawless vertebrate group. We performed a histological analysis of trunk muscle fiber differentiation during embryonal, larval, and adult musculature development in this previously unstudied species. Investigation using light, transmission electron (TEM), and confocal microscopy revealed that embryonal and larval musculature differs from adult muscle mass. Here, we present the morphological analysis of L. fluviatilis myogenesis, from unsegmented mesoderm through somite formation, and their differentiation into multinucleated muscle lamellae. Our analysis also revealed the presence of myogenic factors LfPax3/7 and Myf5 in the dermomyotome. In the next stages of development, two types of muscle lamellae can be distinguished: central surrounded by parietal. This pattern is maintained until adulthood, when parietal muscle fibers surround the central muscles on both sides. The two types show different morphological characteristics. Although lampreys are phylogenetically distant from jawed vertebrates, somite morphology, especially dermomyotome function, shows similarity. Here we demonstrate that somitogenesis is a conservative process among all vertebrates. We conclude that river lamprey myogenesis shares features with both ancestral and higher vertebrates.