Effects of Simulated Microgravity on Embryonic Stem Cells

There have been many studies on the biological effects of simulated microgravity (SMG) on differentiated cells or adult stem cells. However, there has been no systematic study on the effects of SMG on embryonic stem (ES) cells. In this study, we investigated various effects (including cell proliferation, cell cycle distribution, cell differentiation, cell adhesion, apoptosis, genomic integrity and DNA damage repair) of SMG on mouse embryonic stem (mES) cells. Mouse ES cells cultured under SMG condition had a significantly reduced total cell number compared with cells cultured under 1 g gravity (1G) condition. However, there was no significant difference in cell cycle distribution between SMG and 1G culture conditions, indicating that cell proliferation was not impaired significantly by SMG and was not a major factor contributing to the total cell number reduction. In contrast, a lower adhesion rate cultured under SMG condition contributed to the lower cell number in SMG. Our results also revealed that SMG alone could not induce DNA damage in mES cells while it could affect the repair of radiation-induced DNA lesions of mES cells. Taken together, mES cells were sensitive to SMG and the major alterations in cellular events were cell number expansion, adhesion rate decrease, increased apoptosis and delayed DNA repair progression, which are distinct from the responses of other types of cells to SMG

Contrasting Response of the Calcareous Nannoplankton Communities After the Eocene Hyperthermal Events in the Tropical Atlantic Ocean

Latest Paleocene and early Eocene hyperthermals were geologically brief, profound environmental perturbations caused by massive additions of 13 C-depleted carbon to the ocean-atmosphere system, and therefore provide ancient analogs to assess the impact of modern global warming on the Earth\u27s ecosystem. We document and compare population changes in calcareous nannoplankton, the major primary producers in Paleogene oceans, across three consecutive hyperthermal episodes of differing magnitudes (i.e., the most severe Paleocene/Eocene Thermal Maximum (PETM), the relatively mild Eocene Thermal Maximum 2 (ETM2) and the least severe H2) in the tropical Atlantic. Across all three hyperthermal events, the total abundance and the abundance of the eutrophic and mesotrophic taxa decreased significantly, while oligotrophic taxa increased markedly, suggesting that oligotrophy prevailed in tropical Atlantic surface waters. A nonmetric multidimensional scaling ordination revealed that, during the peak of each hyperthermal, nannoplankton communities featured excursion taxa and assemblages substantially deviated from the pre-event composition. However, during the recovery phase, nannoplankton communities rapidly returned to quasi pre-event compositions for the ETM2 and H2 perturbations, but remained distinct from the pre-event composition for the PETM. This contrast between pre- and post-event compositions of nannoplankton communities may imply that the PETM perturbation exceeded the resilience threshold of the tropical Atlantic surface ecosystem and caused a regime shift, cautioning the possible risk of an abrupt state change in oceanic ecosystem under the present situation, which has a considerably faster and greater perturbation to the C cycle than during the PETM

The Upregulated Expression of the Citrus <i>RIN4</i> Gene in HLB Diseased Citrus Aids <i>Candidatus</i> Liberibacter Asiaticus Infection

The citrus industry has been threatened by Huanglongbing (HLB) for over a century. Here, an HLB-induced Arabidopsis RPM1-interacting protein 4 (RIN4) homologous gene was cloned from Citrus clementina, and its characteristics and function were analyzed to determine its role during citrus–Candidatus Liberibacter asiaticus (CLas) interactions. Quantitative real-time PCR showed that RIN4 was expressed in roots, stems, leaves and flowers, with the greatest expression level in leaves. Its expression was suppressed by gibberellic acid, indole-3-acetic acid, salicylic acid and jasmonic acid treatments, but was induced by abscisic acid and salt treatments, as well as wounding. The transient expression of a RIN4-GFP showed that RIN4 was localized in the cell membrane. RIN4-overexpressing transgenic C. maxima cv. ‘Shatianyou’ plants were obtained, and some transgenic plants showed greater sensitivity to CLas infection and earlier HLB symptoms appearance than non-transgenic controls. Results obtained in this study indicated that the upregulated expression of RIN4 in HLB diseased citrus may aid CLas infection

Transcriptomic and physiological comparison of Shatangju (Citrus reticulata) and its late-maturing mutant provides insights into auxin regulation of citrus fruit maturation

Previous studies have shown that abscisic acid (ABA) and ethylene are involved in pulp maturation and peel coloration in the nonclimacteric citrus fruits. There are also signs indicating that other plant hormones may play some roles in citrus fruit ripening. In this study, we compared profiles of genome-wide gene expression and changes in hormones and peel pigments between fruits of Shatangju mandarin (Citrus reticulata Blanco, designated WT) and its natural mutant, Yuenongwanju (designated MT). The MT fruit matures ~2 months later than the WT fruit. Significant differences in fruit diameter, total soluble solids, titratable acid content, chlorophylls and carotenoids were detected between the fruits of the two genotypes at the sampled time points. Genome-wide transcriptome profiling showed that many genes involved in auxin and ABA metabolism and/or signaling pathways were differentially expressed between the MT and the WT fruits. Importantly, the expression of CrYUCCA8 was significantly lower and the expression of CrNCED5 was significantly higher in WT than in MT fruits at 230 and 250 DPA, respectively. In addition, the indole-3-acetic acid (IAA) level in the MT fruit was significantly higher than that in the WT counterpart, whereas a significantly lower level of ABA was detected in the mutant. Treatment of the WT fruit with exogenous IAA significantly delayed fruit maturation. Our results provide experimental evidence supporting the notion that auxin is a negative regulator of fruit maturation in citrus

Light extraction enhancement of SOI-based erbium/oxygen Co-implanted photonic crystal microcavities

H5 photonic crystal(PC) microcavities co-implanted with erbium(Er) and oxygen(O) ions were fabricated on silicon-on-insulator(SOI) wafers. Photoluminescence(PL) measurements were taken at room temperature and a light extraction enhancement of up to12 was obtained at1.54μm, as compared to an identically implanted unpatterned SOI wafer. In addition, we also explored the adjustment of cavity modes by changing the structural parameters of the PC, and the measured results showed that the cavity-resonant peaks shifted towards shorter wavelengths as the radius of the air holes increased, which is consistent with the theoretical simulation.?2011 Chinese Institute of Electronics

An investigation on the respiratory mechanics of mechanically ventilated patients during spontaneous breathing trials with enhanced low‐level pressure support ventilation

Abstract Introduction Low‐level pressure support ventilation (PSV) is most commonly adopted in spontaneous breathing trials (SBTs), and some have proposed setting the positive end‐expiratory pressure (PEEP) to 0 cmH2O in order to shorten the observation time of SBTs. This study aims to investigate the effects of two PSV protocols on the patients' respiratory mechanics. Material and method A prospective randomized self‐controlled crossover design was adopted in this study, which involved enrolling 30 difficult‐to‐wean patients who were admitted to the intensive care unit of the First Affiliated Hospital of Guangzhou Medical University between July 2019 and September 2021. Patients were subjected to the S group (pressure support: 8 cmH2O, PEEP: 5 cmH2O) and S1 group (PS: 8 cmH2O, PEEP: 0 cmH2O) for 30 min in a random order, and respiratory mechanics indices were dynamically monitored via a four‐lumen multi‐functional catheter with an integrated gastric tube. Among the 30 enrolled patients, 27 were successfully weaned. Result The S group showed higher airway pressure (Paw), intragastric pressure (Pga) and airway pressure–time product (PTP) than the S1 group. The S group also showed a shorter inspiratory trigger delay, (93.80 ± 47.85) versus (137.33 ± 85.66) ms (P = 0.004); and fewer abnormal triggers, (0.97 ± 2.65) versus (2.67 ± 4.48) (P = 0.042) compared with the S1 group. Stratification based on the causes of mechanical ventilation revealed that under the S1 protocol, patients with chronic obstructive pulmonary disease (COPD) had a longer inspiratory trigger delay compared to both post‐thoracic surgery (PTS) patients and patients with acute respiratory distress syndrome. Despite providing greater respiratory support, S group led to significant reductions in inspiratory trigger delay and less abnormal triggers compared to S1 group, especially among patients with chronic obstructive pulmonary disease. Conclusion These findings suggest that the zero PEEP group was more likely to induce a higher number of patient–ventilator asynchronies in difficult‐to‐wean patients

An Analysis of the Gene Expression Associated with Lymph Node Metastasis in Colorectal Cancer

Objective. This study aimed to explore the genes regulating lymph node metastasis in colorectal cancer (CRC) and to clarify their relationship with tumor immune cell infiltration and patient prognoses. Methods. The data sets of CRC patients were collected through the Cancer Gene Atlas database; the differentially expressed genes (DEGs) associated with CRC lymph node metastasis were screened; a protein–protein interaction (PPI) network was constructed; the top 20 hub genes were selected; the Gene Ontology functions and the Kyoto Encyclopedia of Genes and Genomes pathways were enriched and analyzed. The Least Absolute Shrinkage and Selection Operator (LASSO) regression method was employed to further screen the characteristic genes associated with CRC lymph node metastasis in 20 hub genes, exploring the correlation between the characteristic genes and immune cell infiltration, conducting a univariate COX analysis on the characteristic genes, obtaining survival-related genes, constructing a risk score formula, conducting a Kaplan–Meier analysis based on the risk score formula, and performing a multivariate COX regression analysis on the clinical factors and risk scores. Results. A total of 62 DEGs associated with CRC lymph node metastasis were obtained. Among the 20 hub genes identified via PPI, only calcium-activated chloride channel regulator 1 (CLCA1) expression was down-regulated in lymph node metastasis, and the rest were up-regulated. A total of nine characteristic genes associated with CRC lymph node metastasis (KIF1A, TMEM59L, CLCA1, COL9A3, GDF5, TUBB2B, STMN2, FOXN1, and SCN5A) were screened using the LASSO regression method. The nine characteristic genes were significantly related to different kinds of immune cell infiltration, from which three survival-related genes (TMEM59L, CLCA1, and TUBB2B) were screened. A multi-factor COX regression showed that the risk scores obtained from TMEM59L, CLCA1, and TUBB2B were independent prognostic factors. Immunohistochemical validation was performed in tissue samples from patients with rectal and colon cancer. Conclusion. TMEM59L, CLCA1, and TUBB2B were independent prognostic factors associated with lymphatic metastasis of CRC