The proximal cis-acting elements Sp1, Sp3 and E2F regulate mouse mer gene transcription in sertoli cells

Mer belongs to the Tyro 3 family of receptor tyrosine kinases (RTKs). Together with Axl and Rse, the three RTKs are believed to play important functional roles in the male gonads because gene knockout male mice lacking all of these receptors are infertile. In the present study, postnatal expression of Axl and Rse in mouse testes decreased during maturation while expression of Mer increased age-dependently during testicular development. To investigate the transcriptional regulation of gene expression in the testis, a ≈ 1.5 kb fragment of the 5′ flanking sequence of Mer was isolated. The sequence lacks a typical TATA or CAAT box. 5′ RACE revealed that the putative major transcriptional start site of Mer is located at +102 bp upstream of the translation initiation site. Using transient transfections of luciferase reporter constructs driven by various lengths of the 5′ flanking sequence, the gene segment -321/+126 showed the highest transcriptional activity in a mouse Sertoli cell line (TM4). DNAase I footprinting experiments revealed four footprints within the region from -321 to -26, including three binding sites for the transcriptional factor Specificity protein 1 (Sp1) and one for an unknown transcriptional factor. Electrophoretic mobility shift assay (EMSA), supershift assay, mutation studies and cotransfection demonstrated that those Sp1 cis-acting motifs interacted either with Sp1 or Sp1/Sp3, depending on location and the nearby nucleotide sequences. An E2F binding site which down-regulates Mer transcription, as revealed by EMSA, deletion and mutation studies, was identified downstream in the proximity of the promoter. Taking all of these data together, the study has demonstrated that Sp1, Sp3, E2F and probably another unknown transcriptional factor play a critical role in regulating the proximal promoter activities of Mer.postprin

A multidisciplinary programme to care people with suicide and attempted suicide in the Eastern District

Congress Theme: New Discoveries and Technologies in Suicide PreventionSession - OP20-7N: Understanding and Helping Suicide Attempters 2BACKGROUND: Suicide is a highly taboo and stigmatized issue in Chinese societies. This greatly affects people’s help-seeking behaviour when encountering such problems. The community -based suicide prevention progamme aims at targeting all individuals with or without risky suicidal behavior to help promote its prevention to minimize its stigmatisation and to enhance help-seeking behavior. Collaboration platform among various disciplines had been ..

In search of suitable in vitro models to study germ cell movement across the blood-testis barrier

The movement of preleptotene/leptotene spermatocytes across the blood-testis barrier, also known as the Sertoli cell barrier, during stages VIII to XI of the seminiferous epithelial cycle is one of the most important cellular events taking place in the mammalian testis. Without the passage of spermatocytes, spermatogenesis would be halted, resulting in transient or permanent sterility. Unfortunately, we have very little knowledge on how preleptotene/leptotene spermatocytes cross the blood-testis barrier. While we know cytokines, proteases and androgens to mediate Sertoli cell junction restructuring, most data continue to be derived from experiments using Sertoli cells cultured alone in two dimensions. Thus, additional in vitro models which include germ cells must come into use. In this Commentary, we hope to shed new light on how we may better study spermatocyte movement across the BTB

Enhanced absorption of CVD grown molybdenum disulfide monolayers via surface plasmon resonance with silver nano-triangles

© 2019 Optical Society of America. Transient reflection was performed on large-area chemical vapor deposition (CVD) grown monolayer MoS2 flakes with silver nano-triangles coated on the surface to characterize its modifications to the optical properties of MoS2. Broadband transient reflection was carried out over a range of different pump wavelengths to tune in and out of the plasmonic resonance band of the nano-triangles. Large enhancement in transient reflectivity was observed, which approximately followed the plasmon resonance spectrum of the nano-triangles. Finite-difference time-domain simulationswere performed to verify that there is an increased absorption due to local surface plasmon-induced near-field enhancements. We also report observation of the dynamics of the MoS2 exciton bleaching bands, which showed subtle differences in recombination dynamics related to the exciton-plasmon coupling strength for excitation on-resonance and off-resonance at the silver nano-triangles plasmonic band

Difference in T helper responses during hepatitis flares in hepatitis B e antigen (HBeAg)-positive patients with genotypes B and C: implication for early HBeAg seroconversion

The underlying mechanisms for earlier hepatitis B e antigen (HBeAg) seroconversion in patients with chronic hepatitis B virus (HBV) genotype B when compared with genotype C are unknown. We aimed to determine whether there were any differences in the T helper (Th) responses during hepatitis flares in HBeAg-positive patients with genotypes B and C. Proliferative response measured by 3H-thymidine uptake and Th responses measured by Enzyme-Linked Immunosorbent Spot assays for interleukin (IL)-2, interferon-gamma (IFN-γ), IL-4, IL-5 and IL-10 were performed in 10 patients with genotype B and 10 with genotype C with hepatitis flares. HBV genotypes, core promoter, precore mutations, sequence of HBV core region and HBV DNA levels were determined. There was no difference in the HBV DNA levels during hepatitis flares between patients with genotypes B and C. Patients with genotype B had a significantly higher number of IFN-γ producing cells [with hepatitis B core antigen (HBcAg) stimulation] and lower number of IL-10 producing cells (with HBcAg and HBeAg stimulation) compared with patients with genotype C (P = 0.011, =0.043, <0.001 respectively). There was a trend (P = 0.058) that patients with genotype B had a higher cumulative rate of HBeAg seroconversion. Patients with precore mutants also had a significantly higher number of IFN-γ producing cells (with HBcAg stimulation) and lower number of IL-10 producing cells (with HBeAg stimulation) compared to patients without precore mutant (P = 0.038, =0.016 respectively). HBV genotype B induces a greater Th1 and lesser Th2 response than genotype C. This provides immunologic evidence for the higher chance of HBeAg seroconversion in patients with genotype B. © 2007 The Authors.link_to_subscribed_fulltex

Immune response during immunoclearance phase of Chinese patients with HBV genotypes B and C

Background: Chronic hepatitis B patients with genotype B achieve HBeAg seroconversion at an earlier age compared with those with genotype C (Yuen et al., Hepatology 2003). Whether this is due to differences in tile immune response to file hepatitis B virus during the imrnunoclearance phase between patients with genotypes B and C has never been studied. Aims: To compare the immune response during the immunoclearance phase of patients with genotypes B and C. Patients and Methods: 20 HBeAg-positive patients with elevated ALT levels, 10 with genotype B and 10 with genotype C, were recruited. Proliferation and Till and Th2 immune responses of peripheral blood mononuclear cells were measured by 3H-thymidine uptake and ELISPOT assays respectively. The core promoter and precore mutations and HBV DNA levels were determined. Results: The followings are the interim results of first 12 patients (4 and 8 with genotypes B and C respectively). P values were not calculated because of the anlall number of patients. There were no differences in ALT and HBV DNA levels between two groups. Four patients with genotype B and 4 patients with genotype C had precore and core promoter mutations respectively. Compared to patients with genotype C, patients with genotype B had a higher stimulation index (proliferative response) towards HBcAg (4.6 vs. 2.7 respectively) and HBeAg (1.9 vs. 1.6 respectively). The results of tile ELISPOT assays are listed in the table. Conclusions: Compared to patients with genotype B, patients with genotype C have a lower proliferative response and greater induction of IL-10 production towards HBcAg and HBeAg. These phenomena may explain the delayed HBeAg seroconversion in patients with genotype C.link_to_subscribed_fulltextThe 40th Annual Meeting of The European Association for the Study of the Liver, Paris, France, 13-17 April 2005 . In Journal of Hepatology, 2005, v. 42 n. Suppl. 2, p. 152, poster abstract no. 41

Changes in the expression of junctional and nonjunctional complex component genes when inter-Sertoli tight junctions are formed in vitro

Throughout spermatogenesis, germ cells move progressively from the basal to the adluminal compartment, which is accompanied by continual disassembly and reassembly of intercellular junctions suggesting germ cell movement is composed of intermittent phases of junction disassembly and reassembly. A study was performed to correlate the expression of junctional-complex components (such as zonula occludens-1 [ZO-1], a tight-junction component protein) and nonjunctional complex components (such as urokinase-type plasminogen activator [uPA], a serine protease; cathepsin L, a cysteine protease; α2-macroglobulin, a nonspecific protease inhibitor; and cystatin C, a cysteine protease inhibitor) at the time when inter-Sertoli tight junctions were established in vitro. This is an attempt to investigate whether the expression of nonjunctional component genes also correlates with the formation of inter-Sertoli tight junctions in vitro. This is part of an effort to understand the physiologic elements of germ cell movement in the epithelium. Sertoli cells cultured in vitro are known to undergo programmed cell death. To ensure that the changes in target gene expression were not the result of apoptosis, Sertoli cells were cultured in vitro at densities of 0.25, 0.75, and 3 x 106 cells/cm2 for up to 7 days on bicameral culture units coated with Matrigel (Collaborative Research) and were assessed by morphologic analysis and agarose gel electrophoresis. It was noted that many of the Sertoli cells cultured at 3 x 106 cells/cm2 underwent apoptosis by day 7, in contrast to cultures at 0.25 and 0.75 x 106 cells/cm2 illustrating the Sertoli cell number per unit of area may be an important parameter to be considered when studying Sertoli cell function in vitro. Also, it was shown that the expression of ZO-1 increased significantly between days 2 and 3 prior to the establishment of inter-Sertoli tight junctions assessed by transepithelial resistance measurement (TER), which illustrates that ZO-1 can be used as a marker to monitor this cellular event. More interestingly, there was also a transient increase in the expression of uPA and cathepsin L between days 2 and 3 at the time preceding the formation of tight junctions. In Sertoli cells cultured at low density (2 x 104 cells/cm2), when a confluent monolayer of cells could not form, there were no changes in the expression of either ZO-1, uPA, or cathepsin L throughout the 7-day culture period. These results show that the establishment of specialized junctions, such as tight junctions between Sertoli cells in vitro, may require the participation of both junctional and nonjunctional complex components.link_to_subscribed_fulltex

Quantification of temperature-dependent charge separation and recombination dynamics in non-fullerene organic photovoltaics

Transient optical spectroscopy is used to quantify the temperature-dependence of charge separation and recombination dynamics in P3TEA:SF-PDI2 and PM6:Y6, two non-fullerene organic photovoltaic (OPV) systems with a negligible driving force and high photocurrent quantum yields. By tracking the intensity of the transient electroabsorption response that arises upon interfacial charge separation in P3TEA:SF-PDI2, a free charge generation rate constant of ≈2.4 × 1010 s−1 is observed at room temperature, with an average energy of ≈230 meV stored between the interfacial charge pairs. Thermally activated charge separation is also observed in PM6:Y6, and a faster charge separation rate of ≈5.5 × 1010 s−1 is estimated at room temperature, which is consistent with the higher device efficiency. When both blends are cooled down to cryogenic temperature, the reduced charge separation rate leads to increasing charge recombination either directly at the donor-acceptor interface or via the emissive singlet exciton state. A kinetic model is used to rationalize the results, showing that although photogenerated charges have to overcome a significant Coulomb potential to generate free carriers, OPV blends can achieve high photocurrent generation yields given that the thermal dissociation rate of charges outcompetes the recombination rate