Viruses contribute to the mortality of marine microbes, consequentially altering biological species composition and system biogeochemistry. Although it is well established that host cells provide metabolic resources for virus replication, the extent to which infection reshapes host metabolism at a global level and the effect of this alteration on the cellular material released following viral lysis is less understood. To address this knowledge gap, the growth dynamics, metabolism and extracellular lysate of roseophage-infected Sulfitobacter sp. 2047 was studied using a variety of techniques, including liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics. Quantitative estimates of the total amount of carbon and nitrogen sequestered into particulate biomass indicate that phage infection redirects B75% of nutrients into virions. Intracellular concentrations for 82 metabolites were measured at seven time points over the infection cycle. By the end of this period, 71% of the detected metabolites were significantly elevated in infected populations, and stable isotope-based flux measurements showed that these cells had elevated metabolic activity. In contrast to simple hypothetical models that assume that extracellular compounds increase because of lysis, a profile of metabolites from infected cultures showed that 470% of the 56 quantified compounds had decreased concentrations in the lysate relative to uninfected controls, suggesting that these small, labile nutrients were being utilized by surviving cells. These results indicate that virus-infected cells are physiologically distinct from their uninfected counterparts, which has implications for microbial community ecology and biogeochemistry.

Milk and dairy products are an important source of choline, a nutrient essential for human health. Infant formula derived from bovine milk contains a number of metabolic forms of choline, all contribute to the growth and development of the newborn. At present, little is known about the factors that influence the concentrations of choline metabolites in milk. The objectives of this study were to characterize and then evaluate associations for choline and its metabolites in blood and milk through the first 37 weeks of lactation in the dairy cow. Milk and blood samples from twelve Holstein cows were collected in early, mid and late lactation and analyzed for acetylcholine, free choline, betaine, glycerophosphocholine, lysophosphatidylcholine, phosphatidylcholine, phosphocholine and sphingomyelin using hydrophilic interaction liquid chromatography-tandem mass spectrometry, and quantified using stable isotope-labeled internal standards. Total choline concentration in plasma, which was almost entirely phosphatidylcholine, increased 10-times from early to late lactation (1305 to 13,535 µmol/L). In milk, phosphocholine was the main metabolite in early lactation (492 µmol/L), which is a similar concentration to that found in human milk, however, phosphocholine concentration decreased exponentially through lactation to 43 µmol/L in late lactation. In contrast, phosphatidylcholine was the main metabolite in mid and late lactation (188 µmol/L and 659 µmol/L, respectively), with the increase through lactation positively correlated with phosphatidylcholine in plasma (R 2 = 0.78). Unlike previously reported with human milk we found no correlation between plasma free choline concentration and milk choline metabolites. The changes in pattern of phosphocholine and phosphatidylcholine in milk through lactation observed in the bovine suggests that it is possible to manufacture infant formula that more closely matches these metabolites profile in human milk.

Domestic broiler chickens rapidly accumulate fat and are naturally hyperglycemic and insulin resistant, making them an attractive model for studies of human obesity. We previously demonstrated that short-term (5 h) fasting rapidly upregulates pathways of fatty acid oxidation in broiler chickens and proposed that activation of these pathways may promote leanness. The objective of the current study was to characterize adipose tissue from relatively lean and fatty lines of chickens and determine if heritable leanness in chickens is associated with activation of some of the same pathways induced by fasting. We compared adipose gene expression and metabolite profiles in white adipose tissue of lean Leghorn and Fayoumi breeds to those of fattier commercial broiler chickens. Both lipolysis and expression of genes involved in fatty acid oxidation were upregulated in lean chickens compared with broilers. Although there were strong similarities between the lean lines compared with broilers, distinct expression signatures were also found between Fayoumi and Leghorn, including differences in adipogenic genes. Similarities between genetically lean and fasted chickens suggest that fatty acid oxidation in white adipose tissue is adaptively coupled to lipolysis and plays a role in heritable differences in fatness. Unique signatures of leanness in Fayoumi and Leghorn lines highlight distinct pathways that may provide insight into the basis for leanness in humans. Collectively, our results provide a number of future directions through which to fully exploit chickens as unique models for the study of human obesity and adipose metabolism.

Domestic broiler chickens rapidly accumulate adipose tissue and are naturally hyperglycemic and insulin resistant, making them an attractive model for the study of obesity and insulin resistance. We previously showed that 5‐hour fasting rapidly upregulated pathways that would limit fat storage and promote fatty acid oxidation in broiler white adipose tissue. Our current objective was to determine if genetically determined leanness in chickens was due to activation of the same pathways induced by fasting. We used Affymetrix microarrays to identify differentially expressed genes in white adipose tissue of Fayoumi and broilers, which differ in adiposity by approximately 3‐fold. Cluster analysis revealed distinct similarities between expression profiles of lean Fayoumi and fasted broilers, compared to fed broilers, including genes involved in substrate oxidation. Lean chickens showed significant upregulation of energy‐sensing signaling pathways in white adipose tissue based on mRNA and Western blot analyses, including upregulation of the 5’ AMP‐activated protein kinase (AMPK) pathway. Adipose metabolites and fatty acid profiles were measured using LC‐MS/MS and GC‐MS, respectively. Our results indicated significant differences in adipose metabolism, stress signaling and adipogenesis between genetically lean and fatty lines of chickens, which may have relevance for studies of human obesity.

The p21 protein, which is upregulated in response to UV‐light, halts cell cycle and can promote apoptosis. Levels of p21 mRNA can be quantified by Real‐Time PCR. We have designed a protocol using Real‐Time PCR to detect the upregulation of p21 transcript in HaCat cells after UV‐irradiation to be used in an undergraduate laboratory course. Cultured HaCat cells were exposed to 15mJ/cm2 UV‐B light, total RNA was extracted and reverse transcribed, and Real‐Time PCR with SYBR Green was performed. Following this level of exposure, levels of p21 were significantly higher in irradiated cells than non‐irradiated cells. This protocol can easily be adapted to be used in any Molecular Biology or Biochemistry Laboratory Course.