F13A1 transglutaminase expression in human adipose tissue increases in acquired excess weight and associates with inflammatory status of adipocytes.

OBJECTIVE: F13A1/FXIII-A transglutaminase has been linked to adipogenesis in cells and to obesity in humans and mice, however, its role and associated molecular pathways in human acquired excess weight have not been explored. METHODS: We examined F13A1 expression and association to human weight gain in weight-discordant monozygotic twins (Heavy-Lean difference (ΔWeight, 16.8 kg ± 7.16 for n = 12). The twin pairs were examined for body composition (by dual-energy X-ray absorptiometry), abdominal body fat distribution (by magnetic resonance imaging), liver fat content (by magnetic resonance spectroscopy), circulating adipocytokines, leptin and adiponectin, as well as serum lipids. Affymetrix full transcriptome mRNA analysis was performed from adipose tissue and adipocyte-enriched fractions from subcutaneous abdominal adipose tissue biopsies. F13A1 differential expression between the heavy and lean co-twins was examined and its correlation transcriptome changes between co-twins were performed. RESULTS: F13A1 mRNA showed significant increase in adipose tissue (p < 0.0001) and an adipocyte-enriched fraction (p = 0.0012) of the heavier co-twin. F13A1 differential expression in adipose tissue (Heavy-Lean ΔF13A1) showed significant negative correlation with circulating adiponectin (p = 0.0195) and a positive correlation with ΔWeight (p = 0.034), ΔBodyFat (0.044) and ΔAdipocyte size (volume, p = 0.012;) in adipocyte-enriched fraction. A whole transcriptome-wide association study (TWAS) on ΔF13A1 vs weight-correlated ΔTranscriptome identified 182 F13A1-associated genes (r > 0.7, p = 0.05) with functions in several biological pathways including cell stress, inflammatory response, activation of cells/leukocytes, angiogenesis and extracellular matrix remodeling. F13A1 did not associate with liver fat accumulation. CONCLUSIONS: F13A1 levels in adipose tissue increase with acquired excess weight and associate with pro-inflammatory, cell stress and tissue remodeling pathways. This supports its role in expansion and inflammation of adipose tissue in obesity.

Dimorphism in cryptophytes-The case of Teleaulax amphioxeia/Plagioselmis prolonga and its ecological implications.

Growing evidence suggests that sexual reproduction might be common in unicellular organisms, but observations are sparse. Limited knowledge of sexual reproduction constrains understanding of protist ecology. Although Teleaulax amphioxeia and Plagioselmis prolonga are common marine cryptophytes worldwide, and are also important plastid donors for some kleptoplastic ciliates and dinoflagellates, the ecology and development of these protists are poorly known. We demonstrate that P. prolonga is the haploid form of the diploid T. amphioxeia and describe the seasonal dynamics of these two life stages. The diploid T. amphioxeia dominates during periods of high dissolved inorganic nitrogen (DIN) and low irradiance, temperature, and grazing (winter and early spring), whereas the haploid P. prolonga becomes more abundant during the summer, when DIN is low and irradiance, temperature, and grazing are high. Dimorphic sexual life cycles might explain the success of this species by fostering high genetic diversity and enabling endurance in adverse conditions.

Copepods drive large-scale trait-mediated effects in marine plankton.

Fear of predation may influence food webs more than actual predation. However, the mechanisms and magnitude of nonconsumptive predator effects are largely unknown in unicellular-dominated food webs such as marine plankton. We report a general mechanism of chemically induced predator effects in marine plankton. Copepods, the most abundant zooplankton in the oceans, imprint seawater with unique polar lipids-copepodamides-which trigger toxin production and bioluminescence in harmful dinoflagellates. We show that copepodamides also elicit defensive traits in other phytoplankton, inducing the harmful algal bloom-forming diatom Pseudo-nitzschia seriata to produce 10 times more toxins, and colony-forming diatoms to decrease colony size by half. A 1-year study in the northeast Atlantic revealed that natural copepodamide concentrations are high enough to induce harmful algal toxins and size reduction in dominant primary producers when copepods are abundant. We conclude that copepodamides will structure marine plankton toward smaller, more defended life forms on basin-wide scales.