The use of cultured cells has been instrumental in studying biochemical, molecular, and cellular processes. The composition of serum that cells are maintained in can have a profound impact on important cellular checkpoints. We have analyzed cell growth and apoptosis in an estrogen receptor positive breast cancer cell line in the presence of serum that have been treated to remove steroids or lipids, as well-described in the literature. We showed that maintaining cells in the presence of charcoal-dextran-treated serum causes reduced growth rate, which can be reversed by the addition of estradiol. Silica-treated-serum also slowed down cell growth and induced apoptosis. In order to investigate the role of lipids in these phenotypes, we investigated the levels of a wide range of lipids in different sera. We showed that silica-treatment significantly depletes phosphatidylcholines and cholesterol. We also show that lipogenesis is stimulated when cells are cultured with silica-treated-serum and this was reversed by the addition of exogenous lipids, which also restored growth rate and apoptosis. Our results show that cultured cells are sensitive to different serum, most likely due to the differences in levels of structural and signaling metabolites present in their growth environment.

The sample analysis and data interpretation is the most challenging step of fire debris analysis, due to the presence of combustion and pyrolysis products in the substrate material. In this study, a headspace solid phase microextraction (HS-SPME) procedure was applied to the extraction of combustion and pyrolysis products from three commonly used carpet substrate materials, made of nylon 6,6 and polyesters. Each carpet sample was burned with and without two different ignitable liquids (ILs), i.e., gasoline and kerosene, and the Total Ion Chromatograms (TICs) and Extracted Ion Profiles of characteristic class compounds of ILs were obtained and compared to those of unburned neat ILs, using gas-chromatography mass spectrometry (GC-MS), to study the possible interferences of these substrate materials in fire debris analysis.

The telomeric repeat‐containing RNA, TERRA, associates with both telomeric DNA and telomeric proteins, often forming RNA:DNA hybrids (R‐loops). TERRA is most abundant in cancer cells utilizing the alternative lengthening of telomeres (ALT) pathway for telomere maintenance, suggesting that persistent TERRA R‐loops may contribute to activation of the ALT mechanism. Therefore, we sought to identify the enzyme(s) that regulate TERRA metabolism in mammalian cells. Here, we identify that the 5′–3′ exoribonuclease XRN2 regulates the stability of TERRA RNA. Moreover, while stabilization of TERRA alone was insufficient to drive ALT, depletion of XRN2 in ALT‐positive cells led to a significant increase in TERRA R‐loops and exacerbated ALT activity. Together, our findings highlight XRN2 as a key determinant of TERRA metabolism and telomere stability in cancer cells that rely on the ALT pathway.

DOI: https://doi.org/10.1002/pmic.201800370 In article number 1800370, Brovkovych et al. study the lipid composition of different types of serum in which cultured cells are maintained and show that these cells are sensitive to different serum, most likely due to the differences in levels of structural and signaling metabolites present in the growth environment.

Most studies of T cells have focused on those that respond to foreign peptides. However, other specialized populations of T cells exist that recognize lipid antigens and make up a substantial component of the human immune system. These lipid reactive T cells recognize antigens presented by antigen presentation molecules from the CD1 family. Four CD1 molecules exist (CD1a, CD1b, CD1c and CD1d), and each is capable of presenting a unique repertoire of lipids antigens to T cells. Much of what we have learned about lipid reactive T cells stems from studies of CD1d restricted NKT cells as these are present is both mice and humans and can be detected using CD1d/α-GalCer tetramers. In contrast, our understanding of the biology of CD1a, CD1b, CD1c restricted T cells is relatively limited. However, the recent generation of CD1a, CD1b and CD1c tetramers is helping with the identification and characterisation of these CD1-restricted T cells. We have produced CD1 tetramers loaded with mammalian self-lipids or lipid antigens from Mycobacterium tuberculosis. In conjunction, with a tetramer-based enrichment method, we have successfully identified both autoreactive and microbial lipid antigen specific T cells from healthy human blood. We reveal the phenotypic characteristics of these CD1-restricted T cells and used CD1 mutagenesis to provide new insight into TCR recognition of CD1-lipid antigen complexes. Collectively, these studies will serve as a basis for future studies of lipid reactive T cells in health and disease.