Assessment of Differentiation States of Hematopoietic Stem Cells Following in Vitro Culture Using Side and Forward Scatter of Flow Cytometry

Hematopoietic stem cells (HSC) are defined by the International Society of Hematotherapy and Graft Engineering (ISHAGE) as those at low side scatter, positive for CD34 and CD45dim for their numeration with flow cytometry. However, we found that these CD34+ cells increase their granularity and size following in vitro culture, which was exhibited in flow cytometry as more events at higher side scatter and forward scatter. To further determine whether such a change in the cell event distribution is related to HSC differentiation, HSC markers and differentiation markers of in vitro-cultured HSC were detected by flow cytometry at different side scatter and forward scatter levels using modified ISHAGE gating strategies.nbsp The results revealed that cultured HSC with higher side scatter have a lower percentage of cells positive for HSC markers and a higher percentage of differentiation makers, while those with higher forward scatter have a higher percentage of differentiation makers but a slightly higher percentage of stem cell markers, suggesting that side scatter and forward scatter levels of cultured HSC correlate with the differentiation level of these cells

Thermodynamic behavior of correlated electron-hole fluids in van der Waals heterostructures

Coupled two-dimensional electron-hole bilayers provide a unique platform to study strongly correlated Bose-Fermi mixtures in condensed matter. Electrons and holes in spatially separated layers can bind to form interlayer excitons, composite Bosons expected to support high-temperature exciton superfluids. The interlayer excitons can also interact strongly with excess charge carriers when electron and hole densities are unequal. Here, we use optical spectroscopy to quantitatively probe the local thermodynamic properties of strongly correlated electron-hole fluids in MoSe2/hBN/WSe2 heterostructures. We observe a discontinuity in the electron and hole chemical potentials at matched electron and hole densities, a definitive signature of an excitonic insulator ground state. The excitonic insulator is stable up to a Mott density of ~$0.8\times {10}^{12} \mathrm{cm}^{-2}$ and has a thermal ionization temperature of ~70 K. The density dependence of the electron, hole, and exciton chemical potentials reveals strong correlation effects across the phase diagram. Compared with a non-interacting uniform charge distribution, the correlation effects lead to significant attractive exciton-exciton and exciton-charge interactions in the electron-hole fluid. Our work highlights the unique quantum behavior that can emerge in strongly correlated electron-hole systems

Identification of novel mutations in Chinese Hans with autosomal dominant polycystic kidney disease

<p>Abstract</p> <p>Background</p> <p>Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited renal disease with an incidence of 1 in 400 to 1000. The disease is genetically heterogeneous, with two genes identified: <it>PKD1 </it>(16p13.3) and <it>PKD2 </it>(4q21). Molecular diagnosis of the disease in at-risk individuals is complicated due to the structural complexity of <it>PKD1 </it>gene and the high diversity of the mutations. This study is the first systematic ADPKD mutation analysis of both <it>PKD1 </it>and <it>PKD2 </it>genes in Chinese patients using denaturing high-performance liquid chromatography (DHPLC).</p> <p>Methods</p> <p>Both <it>PKD1 </it>and <it>PKD2 </it>genes were mutation screened in each proband from 65 families using DHPLC followed by DNA sequencing. Novel variations found in the probands were checked in their family members available and 100 unrelated normal controls. Then the pathogenic potential of the variations of unknown significance was examined by evolutionary comparison, effects of amino acid substitutions on protein structure, and effects of splice site alterations using online mutation prediction resources.</p> <p>Results</p> <p>A total of 92 variations were identified, including 27 reported previously. Definitely pathogenic mutations (ten frameshift, ten nonsense, two splicing defects and one duplication) were identified in 28 families, and probably pathogenic mutations were found in an additional six families, giving a total detection level of 52.3% (34/65). About 69% (20/29) of the mutations are first reported with a recurrent mutation rate of 31%.</p> <p>Conclusions</p> <p>Mutation study of <it>PKD1 </it>and <it>PKD2 </it>genes in Chinese Hans with ADPKD may contribute to a better understanding of the genetic diversity between different ethnic groups and enrich the mutation database. Besides, evaluating the pathogenic potential of novel variations should also facilitate the clinical diagnosis and genetic counseling of the disease.</p

Adaptive Modulation of MHC Class I Expression and Immune Evasion to Cytotoxic Immunocytes in Cancer Cells

It has been well-demonstrated that cancer cells can escape from the immune surveillance of Cytotoxic T lymphocytes (CTL) and natural killer cells (NK cells) by modulating their MHC class I expression. In order to get insight into the mechanism in which cancer cells regulate their MHC class I expression in response to the attack of CTL and NK cells, different concentration of effector cells were used to examine the effects of low effector/target ratio on the MHC class I expression shifting, tanswells were used to separate effector cells and target cells in culture to check if the cell to cell contact is required for the MHC class I expression shifting, and intracellular flow cytometry was used to determine if MHC class I protein synthesis in cancer cells were also changed with their surface antigen in current studies. Our data indicate that (1) both elimination of target cells and direct regulation of MHC class I expression in target cells contributed to modulation of MHC class I expression in cancer cells (2) effector cell mediated-regulation of MHC class I expression in cancer cells required cell to cell contact (3) the shifting of surface MHC class I antigen on the cancer cells might be caused by the change of MHC class I protein synthesis in cancer cells and (4) application of inadequate numbers of effector cells may induce immune evasion of cancer cells, a cautionary tale for future clinical studies

Significant inter-annual fluctuation in CO2 and CH4 diffusive fluxes from subtropical aquaculture ponds: implications for climate change and carbon emission evaluations

Aquaculture ponds are potential hotspots for carbon cycling and emission of greenhouse gases (GHGs) like CO and CH , but they are often poorly assessed in the global GHG budget. This study determined the temporal variations of CO and CH concentrations and diffusive fluxes and their environmental drivers in coastal aquaculture ponds in southeastern China over a five-year period (2017-2021). The findings indicated that CH flux from aquaculture ponds fluctuated markedly year-to-year, and CO flux varied between positive and negative between years. The coefficient of inter-annual variation of CO and CH diffusive fluxes was 168% and 127%, respectively, highlighting the importance of long-term observations to improve GHG assessment from aquaculture ponds. In addition to chlorophyll-a and dissolved oxygen as the common environmental drivers, CO was further regulated by total dissolved phosphorus and CH by dissolved organic carbon. Feed conversion ratio correlated positively with both CO and CH concentrations and fluxes, showing that unconsumed feeds fueled microbial GHG production. A linear regression based on binned (averaged) monthly CO diffusive flux data, calculated from CO concentrations, can be used to estimate CH diffusive flux with a fair degree of confidence (r  = 0.66; p < 0.001). This algorithm provides a simple and practical way to assess the total carbon diffusive flux from aquaculture ponds. Overall, this study provides new insights into mitigating the carbon footprint of aquaculture production and assessing the impact of aquaculture ponds on the regional and global scales

Emerging exciton physics in transition metal dichalcogenide heterobilayers

Atomically thin transition metal dichalcogenides (TMDs) are 2D semiconductors with tightly bound excitons and correspondingly strong light–matter interactions. Owing to the weak van der Waals bonding between layers, TMDs can be isolated and stacked together to form synthetic heterostructures with emergent electronic and excitonic properties. In this Review, we focus on the emergent exciton physics in moiré superlattices and in TMD heterobilayers coupled to optical cavities, where exciton behaviour can be dramatically modified by the environment. In moiré superlattices, a small twist angle or lattice mismatch between the layers introduces a periodic variation in the interlayer alignment that leads to exciton localization, modified optical selection rules and strong correlations. In cavity–heterostructure systems, light–matter interaction is enhanced and exciton states can couple to the cavity to form exciton-polaritons, whose properties depend on the specific TMD layers involved and their alignment. Here, we discuss recent theoretical and experimental progress towards realizing exotic exciton states in TMD heterobilayers and comment on future scientific and technological directions