The Fun30 nucleosome remodeller promotes resection of DNA double-strand break ends

Chromosomal double-strand breaks (DSBs) are resected by 5′-nucleases to form 3′ single-strand DNA (ssDNA) substrates for binding by homologous recombination and DNA damage checkpoint proteins. Two redundant pathways of extensive resection were described both in cells ^1-3 and in vitro^4-6, one relying on Exo1 exonuclease and the other on Sgs1 helicase and Dna2 nuclease. However, it remains unknown how resection proceeds within the context of chromatin where histones and histone-bound proteins represent barriers for resection enzymes. Here, we have identified the yeast nucleosome remodeling enzyme Fun30 as novel factor promoting DSB end resection. Fun30 is the major nucleosome remodeler promoting extensive Exo1- and Sgs1-dependent resection of DSBs while the RSC and INO80 chromatin remodeling complexes play redundant roles with Fun30 in resection adjacent to DSB ends. ATPase and helicase domains of Fun30, which are needed for nucleosome remodeling ⁷, are also required for resection. Fun30 is robustly recruited to DNA breaks and spreads around the DSB coincident with resection. Fun30 becomes less important for resection in the absence of the histone-bound Rad9 checkpoint adaptor protein known to block 5′ strand processing ⁸ and in the absence of either histone H3 K79 methylation or γ-H2A, which mediate recruitment of the Rad9 ^{9, 10}. Together these data suggest that Fun30 helps to overcome the inhibitory effect of Rad9 on DNA resection.

Toxicity of gold nanoparticles (AuNPs): A review

Gold nanoparticles are a kind of nanomaterials that have received great interest in field of biomedicine due to their electrical, mechanical, thermal, chemical and optical properties. With these great potentials came the consequence of their interaction with biological tissues and molecules which presents the possibility of toxicity. This paper aims to consolidate and bring forward the studies performed that evaluate the toxicological aspect of AuNPs which were categorized into in vivo and in vitro studies. Both indicate to some extent oxidative damage to tissues and cell lines used in vivo and in vitro respectively with the liver, spleen and kidney most affected. The outcome of these review showed small controversy but however, the primary toxicity and its extent is collectively determined by the characteristics, preparations and physicochemical properties of the NPs. Some studies have shown that AuNPs are not toxic, though many other studies contradict this statement. In order to have a holistic inference, more studies are required that will focus on characterization of NPs and changes of physical properties before and after treatment with biological media. So also, they should incorporate controlled experiment which includes supernatant control Since most studies dwell on citrate or CTAB-capped AuNPs, there is the need to evaluate the toxicity and pharmacokinetics of functionalized AuNPs with their surface composition which in turn affects their toxicity. Functionalizing the NPs surface with more peculiar ligands would however help regulate and detoxify the uptake of these NPs.

Phospholipase D and phosphatidic acid-mediated generation of superoxide in Arabidopsis

Phospholipase D (PLD), which hydrolyzes phospholipids into free head groups and phosphatidic acid (PA), may regulate cellular processes through the production of lipid and lipid-derived messengers. We have genetically abrogated PLD alpha, the most prevalent isoform of PLD in plants, and the depletion of PLD alpha in Arabidopsis decreased the levels of PA and superoxide production in Arabidopsis leaf extracts. Addition of PA promoted the synthesis of superoxide in the PLD alpha-depleted plants, as measured by chemiluminescence and superoxide dismutase-inhibitable, NADPH-dependent reduction of cytochrome c and nitroblue tetrazolium. The PA-enhanced generation of superoxide was associated mainly with microsomal membranes. Among various lipids tested, PA was the most effective stimulator with the optimal concentrations between 100 and 200 microM. The PA-promoted production of superoxide was observed also in leaves directly infiltrated with PA. The added PA was more effective in stimulating superoxide generation in the PLD alpha-depleted leaves than in the PLD alpha-containing, wild-type leaves, suggesting that PA produced in the cell was more effective than added PA in promoting superoxide production. These data indicate that PLD plays a role in mediating superoxide production in plants through the generation of PA as a lipid messenger.

Subcellular distribution and tissue expression of phospholipase Dalpha, Dbeta, and Dgamma in Arabidopsis

Three phospholipase Ds (PLDs; EC 3.1.4.4) have been cloned from Arabidopsis, and they exhibit two distinct types of activities: polyphosphoinositide-requiring PLDbeta and PLDgamma, and polyphosphoinositide-independent PLDalpha. In subcellular fractions of Arabidopsis leaves, PLDalpha and PLDgamma were both present in the plasma membrane, intracellular membranes, mitochondria, and clathrin-coated vesicles, but their relative levels differed in these fractions. In addition, PLDgamma was detected in the nuclear fraction. In contrast, PLDbeta was not detectable in any of the subcellular fractions. PLDalpha activity was higher in the metabolically more active organs such as flowers, siliques, and roots than in dry seeds and mature leaves, whereas the polyphosphoinositide-dependent PLD activity was greater in older, senescing leaves than in other organs. PLDbeta mRNA accumulated at a lower level than the PLDalpha and PLDgamma transcripts in most organs, and the expression pattern of the PLDbeta mRNA also differed from that of PLDalpha and PLDgamma in different organs. Collectively, these data demonstrated that PLDalpha, PLDbeta, and PLDgamma have different patterns of subcellular distribution and tissue expression in Arabidopsis. The present study also provides evidence for the presence of an additional PLD that is structurally more closely related to PLDgamma than to the other two PLDs.

Adsorption stripping voltammetry of phenol at Nafion-modified glassy carbon electrode in the presence of surfactants

In this paper, a new voltammetric method for the determination of phenol is described. In pH 8.00 phosphate buffer and in the presence of long-chain cationic surfactant-cetyltrimethylammonium bromide-phenol has a very sensitive oxidation peak at 0.47 V (vs. SCE) on the Nafion-modified glassy carbon electrode (GCE). The experimental parameters, such as supporting electrolyte and pH values, amounts of Nafion, varieties and concentration of surfactants, accumulation potential and time, as well as scan rate were optimized. The peak current is linear with the concentration of phenol in the range from 8x10(-9) to 1x10(-5) M, and the detection limit is 1x10(-9) M after being accumulated at -0.50 V (vs. SCE) for 3 min. Trace levels of phenol in water samples were determined by using this voltammetric method, the average recovery was calculated to be 99.56%.

A kinetic model for the metabolic interaction of two substrates at the active site of cytochrome P450 3A4

In many cases, CYP3A4 exhibits unusual kinetic characteristics that result from the metabolism of multiple substrates that coexist at the active site. In the present study, we observed that alpha-naphthoflavone (alpha-NF) exhibited a differential effect on CYP3A4-mediated product formation as shown by an increase and decrease, respectively, of the carboxylic acid (P(2)) and omega-3-hydroxylated (P(1)) metabolites of losartan, while losartan was found to be an inhibitor of the formation of the 5,6-epoxide of alpha-NF. Thus, to address this problem, a kinetic model was developed on the assumption that CYP3A4 can accommodate two distinct and independent binding domains for the substrates within the active site, and the resulting velocity equations were employed to predict the kinetic parameters for all possible enzyme-substrate species. Our results indicate that the predicted values had a good fit with the experimental observations. Therefore, the kinetic constants can be used to adequately describe the nature of the metabolic interaction between the two substrates. Applications of the model provide some new insights into the mechanism of drug-drug interactions at the level of CYP3A4.

Hepatitis B virus stimulates G6PD expression through HBx-mediated Nrf2 activation

Metabolic reprogramming is a hallmark of physiological changes in cancer. Cancer cells primarily apply glycolysis for cell metabolism, which enables the cells to use glycolytic intermediates for macromolecular biosynthesis in order to meet the needs of cell proliferation. Here, we show that glucose-6-phosphate dehydrogenase (G6PD), the first and rate-limiting enzyme of the pentose phosphate pathway, is highly expressed in chronic hepatitis B virus (HBV)-infected human liver and HBV-associated liver cancer, together with an elevated activity of the transcription factor Nrf2. In hepatocytes, HBV stimulates by its X protein (HBx) the expression of G6PD in an Nrf2 activation-dependent pathway. HBx associates with the UBA and PB1 domains of the adaptor protein p62 and augments the interaction between p62 and the Nrf2 repressor Keap1 to form HBx–p62–Keap1 complex in the cytoplasm. The aggregation of HBx–p62–Keap1 complexes hijacks Keap1 from Nrf2 leading to the activation of Nrf2 and consequently G6PD transcription. Our data suggest that HBV upregulates G6PD expression by HBx-mediated activation of Nrf2. This implies a potential effect of HBV on the reprogramming of the glucose metabolism in hepatocytes, which may be of importance in the development of HBV-associated hepatocarcinoma.

Enzyme kinetics of cytochrome P450-mediated reactions

The most common drug-drug interactions may be understood in terms of alterations of metabolism, associated primarily with changes in the activity of cytochrome P450 (CYP) enzymes. Kinetic parameters such as Km, Vmax, Ki and Ka, which describe metabolism-based drug interactions, are usually determined by appropriate kinetic models and may be used to predict the pharmacokinetic consequences of exposure to one or multiple drugs. According to classic Michaelis-Menten (M-M) kinetics, one binding site models can be employed to simply interpret inhibition (pure competitive, non-competitive and uncompetitive) or activation of the enzyme. However, some cytochromes P450, in particular CYP3A4, exhibit unusual kinetic characteristics. In this instance, the changes in apparent kinetic constants in the presence of inhibitor or activator or second substrate do not obey the rules of M-M kinetics, and the resulting kinetics are not straightforward and hamper mechanistic interpretation of the interaction in question. These unusual kinetics include substrate activation (autoactivation), substrate inhibition, partial inhibition, activation, differential kinetics and others. To address this problem, several kinetic models can be proposed, based upon the assumption that multiple substrate binding sites exist at the active site of a particular P450, and the resulting kinetic constants are, therefore, solved to adequately describe the observed interaction between multiple drugs. The following is an overview of some cytochrome P450-mediated classic and atypical enzyme kinetics, and the associated kinetic models. Applications of these kinetic models can provide some new insights into the mechanism of P450-mediated drug-drug interactions.

Identification of the major human liver cytochrome P450 isoform(s) responsible for the formation of the primary metabolites of ziprasidone and prediction of possible drug interactions

AIMS

To identify the cytochrome P450 (CYP) isoform(s) responsible for the formation of the primary metabolite of ziprasidone (ziprasidone sulphoxide), to determine the kinetics of its formation and to predict possible drug interactions by investigating CYP isoform inhibition in an in vitro study.

METHODS

In vitro metabolism of [14C]-ziprasidone was studied using human liver microsomes. The metabolites were identified using mass spectrometry. The kinetics of metabolite formation were determined using [14C]-ziprasidone (10-200 microM) over 5 min, and Km and Vmax were estimated from Lineweaver-Burk plots. IC50 values for the inhibition of specific probe substrates for CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4, by ziprasidone, risperidone and 9-hydroxyrisperidone were also determined using human liver microsomes from three subjects. Mean Ki values were calculated.

RESULTS

Three CYP-mediated metabolites - ziprasidone sulphoxide, ziprasidone sulphone and oxindole acetic acid - were identified. The apparent Km and Vmax values for the formation of the major metabolite, ziprasidone sulphoxide (measured as the sum of sulphoxide and sulphone) were 235 microM and 1.14 nmol mg(-1) protein min(-1), respectively. Isoform-selective inhibitors and recombinant enzymes indicated that CYP3A4 is responsible for the formation of ziprasidone metabolites. Ziprasidone was not a substrate for the other isoforms studied. Similar in vitro inhibition of CYP2D6 (Ki 6.9-16 microM) and CYP3A4 (Ki 64-80 microM) was obtained with ziprasidone, risperidone and 9-hydroxyrisperidone. The in vivo free drug concentrations associated with clinically effective doses of ziprasidone are at least 1500-fold lower than the mean Ki for either CYP2D6 inhibition or CYP3A4 inhibition.

CONCLUSIONS

Ziprasidone is predominantly metabolized by CYP3A4 in human liver microsomes and is not expected to mediate drug interactions with coadministered CYP substrates, at clinically effective doses.

Improvement of skin paddle survival by application of vascular endothelial growth factor in a rat TRAM flap model

The effect of vascular endothelial growth factor (VEGF) on skin flap survival and its ability to induce a pharmacological delay by promoting angiogenesis in a flap was studied in a rat transverse rectus abdominis musculocutaneous flap, using a 3 x 8-cm skin paddle with the inferior epigastric vessels as its main vascular supply. Forty-three Sprague-Dawley rats were divided into four groups. In group 1, VEGF was injected into the femoral vein after the flap was elevated. In group 2, VEGF was injected intra-arterially into the flap through the superior epigastric artery after the flap was elevated. In group 3, VEGF was injected into the subcutaneous fascial layer in the area where the flap would be dissected, and the flap was then raised 7 days after injection. In group 4, the flap was dissected and replaced, using saline injection as the control. On postoperative day 5, the survival area of each skin paddle was measured and the flap was harvested for histological analysis. The results showed that the mean survival area +/- standard deviation for the skin paddle was 6.82 +/- 4.89 cm2 (28.4 +/- 20.4% of the whole skin paddle) in the control group, and 4.2 +/- 3.0 cm2 (17.5 +/- 12.5%) and 6.02 +/- 5.97 cm2 (25.1 +/- 24.9%) in the groups with VEGF systemic and intra-arterial administration respectively. The skin survival area in the group with preoperative subcutaneous administration of VEGF was 17.85 +/- 2.88 cm2 (74.4 +/- 12%), which was significantly higher than the other three groups (p < 0.01). Histological semiquantitative analysis showed increased neovascularization in the flap treated with VEGF preoperatively. The data demonstrate that preoperative treatment with VEGF can induce angiogenesis and enhance skin paddle survival in a musculocutaneous flap.

Microtubule-associated deacetylase HDAC6 promotes angiogenesis by regulating cell migration in an EB1-dependent manner

Angiogenesis, a process by which the preexisting blood vasculature gives rise to new capillary vessels, is associated with a variety of physiologic and pathologic conditions. However, the molecular mechanism underlying this important process remains poorly understood. Here we show that histone deacetylase 6 (HDAC6), a microtubule-associated enzyme critical for cell motility, contributes to angiogenesis by regulating the polarization and migration of vascular endothelial cells. Inhibition of HDAC6 activity impairs the formation of new blood vessels in chick embryos and in angioreactors implanted in mice. The requirement for HDAC6 in angiogenesis is corroborated in vitro by analysis of endothelial tube formation and capillary sprouting. Our data further show that HDAC6 stimulates membrane ruffling at the leading edge to promote cell polarization. In addition, microtubule end binding protein 1 (EB1) is important for HDAC6 to exert its activity towards the migration of endothelial cells and generation of capillary-like structures. These results thus identify HDAC6 as a novel player in the angiogenic process and offer novel insights into the molecular mechanism governing endothelial cell migration and angiogenesis.

High-level dietary vitamin A enhances T-helper type 2 cytokine production and secretory immunoglobulin A response to influenza A virus infection in BALB/c mice

Vitamin A supplementation during acute pneumonia has not improved recovery in most human clinical trials. We hypothesize that high vitamin A intake may decrease the production of T-helper type-1 (Th1) cytokines and thereby inhibit antiviral responses. Such decreases might impair recovery from viral respiratory infections. We thus examined the effect of three interventions on viral pneumonia: 1) a high level vitamin A [250,000 IU/kg diet or 75,000 retinol equivalents (RE)/kg], or 2) control diet (4000 IU/kg diet or 1200 RE/kg) given before and during infection, and 3) initiating the high level diet upon infection to simulate the adjuvant therapy used in clinical trials. No difference was seen among the interventions in severity of disease (weight loss, lung virus titers and survival). However, both the high level diet group and the group in which vitamin A was increased at the time of infection had greater salivary immunoglobulin (Ig)A responses (geometric means, 166 and 105 microg/L, respectively) than did the control group (59 microg/L) (P = 0.0019). In contrast, the serum IgG response was higher in the control group (324+/-158 mg/L) than in the high level group (225+/-95 mg/L) (P = 0.028), although it did not differ from the group in which the diet was changed upon infection (230+/-163 mg/L) (P = 0.084). The production of interferon-gamma (IFN-gamma), a Th1 cytokine, was lower in the high level diet group (median, 0.153 microg/L) compared with the control group (median, 0.839 microg/L) (P = 0.014), whereas the production of interleukin-10 (IL-10), a Th2 cytokine, was higher with the high level diet (median, 0.304 microg/L) than with the control (median, 0.126 microg/L) (P = 0.022). This change in the Th1/Th2 pattern was not sufficient to affect recovery from viral pneumonia but may account for the increased IgA and decreased IgG responses seen with high level dietary vitamin A in this study. These data reinforce the lack of utility of vitamin A in treating acute pneumonia in children and suggest that high dose vitamin A supplements may enhance Th2-mediated immune responses, which are particularly beneficial in the case of extracellular bacterial and parasitic infections and IgA-mediated responses to mucosal infections.

Antitumor effect of sFlt-1 gene therapy system mediated by Bifidobacterium Infantis on Lewis lung cancer in mice

Soluble fms-like tyrosine kinase receptor (sFlt-1) is a soluble form of extramembrane part of vascular endothelial growth factor receptor-1 (VEGFR-1) that has antitumor effects. Bifidobacterium Infantis is a kind of non-pathogenic and anaerobic bacteria that may have specific targeting property of hypoxic environment inside of solid tumors. The aim of this study was to construct Bifidobacterium Infantis-mediated sFlt-1 gene transferring system and investigate its antitumor effect on Lewis lung cancer (LLC) in mice. Our results demonstrated that the Bifidobacterium Infantis-mediated sFlt-1 gene transferring system was constructed successfully and the system could express sFlt-1 at the levels of gene and protein. This system could not only significantly inhibit growth of human umbilical vein endothelial cells induced by VEGF in vitro, but also inhibit the tumor growth and prolong survival time of LLC C57BL/6 mice safely. These data suggest that Bifidobacterium Infantis-mediated sFlt-1 gene transferring system presents a promising therapeutic approach for the treatment of cancer.

Serotypes, genotypes and antimicrobial resistance patterns of human diarrhoeagenic Escherichia coli isolates circulating in southeastern China

Diarrhoeagenic Escherichia coli (DEC) infection is a major health problem in developing countries. The prevalence and characteristics of DEC have not been thoroughly investigated in China. Consecutive faecal specimens from outpatients with acute diarrhoea in nine sentinel hospitals in southeastern China were collected from July 2009 to June 2011. Bacterial and viral pathogens were detected by culture and RT-PCR, respectively. DEC isolates were further classified into five pathotypes using multiplex PCR. The O/H serotypes, sequence types (STs) and antimicrobial susceptibility profiles of the DEC isolates were determined. A total of 2466 faecal specimens were collected, from which 347 (14.1%) DEC isolates were isolated. DEC was the dominant bacterial pathogen detected. The DEC isolates included 217 EAEC, 62 ETEC, 52 EPEC, 14 STEC, one EIEC and one EAEC/ETEC. O45 (6.6%) was the predominant serotype. Genotypic analysis revealed that the major genotype was ST complex 10 (87, 25.6%). Isolates belonging to the serogroups or genotypes of O6, O25, O159, ST48, ST218, ST94 and ST1491 were highly susceptible to the majority of antimicrobials. In contrast, isolates belonging to O45, O15, O1, O169, ST38, ST226, ST69, ST31, ST93, ST394 and ST648 were highly resistant to the majority of antimicrobials. DEC accounted for the majority of bacterial pathogens causing acute diarrhoea in southeastern China, and it is therefore necessary to test for all DEC, not only the EHEC O157:H7. Some serogroups or genotypes of DEC were highly resistant to the majority of antimicrobials. DEC surveillance should be emphasized.

Useful polyclonal antibodies against synthetic peptides corresponding to immunoglobulin light chain constant region for immunohistochemical detection of immunoglobulin light chain amyloidosis

For the immunohistochemical detection of immunoglobulin (Ig) light chain amyloidosis on formalin-fixed, paraffin-embedded tissue sections, we prepared polyclonal antibodies against synthetic peptides corresponding to positions 118-134 of Ig lambda light chain and positions 116-133 of Ig kappa light chain. Nineteen cases of systemic Ig lambda light chain amyloidosis (Alambda amyloidosis), 10 cases of systemic Ig kappa light chain amyloidosis (Akappa amyloidosis), one case of immunohistochemically unclassified systemic amyloidosis and five cases of localized Alambda amyloidosis were tested with these antibodies. Anti-lambda (118-134) antiserum and the affinity-purified antibody both reacted with 18 of the 19 cases of systemic Alambda amyloidosis and all cases of localized Alambda amyloidosis, although the immunoexpression was somewhat variable in intensity in different areas within the same specimen in both systemic and localized amyloidosis. The signal intensities in plasma cells and serum reacted for anti-lambda (118-134) antiserum were weaker than signals obtained with commercially available anti-Ig lambda light chain antibodies. Anti-kappa (116-133) antiserum and the affinity-purified antibody reacted with nine of the 10 cases of systemic Akappa amyloidosis. We conclude that these antibodies against synthetic peptides corresponding to the Ig light chain constant region are useful for the classification of amyloidosis on formalin-fixed, paraffin-embedded tissue sections.

Two novel aggregation-induced emission active coumarin-based Schiff bases and their applications in cell imaging

Two coumarin-based AIE-active compounds emitting ESIPT fluorescence with large Stocks-shifts were applied to cell imaging.

Clinical outcomes of ultrasound-guided radiofrequency ablation for the treatment of primary papillary thyroid microcarcinoma

AIM

To evaluate the safety, efficacy, and long-term outcomes of ultrasound-guided radiofrequency ablation (RFA) for the treatment of primary papillary thyroid microcarcinoma (PTMC).

MATERIALS AND METHODS

A total of 37 patients with 38 PTMC nodules underwent RFA at a power of 20 W between September 2014 and December 2017. The clinical data of these patients were reviewed retrospectively and analysed. Imaging studies of the nodules were conducted, and the patients' thyroid function was assessed before RFA; 1, 3, 6, and 12 months after RFA; and every 6 months thereafter. The volumes and volume reduction rate (VRR) of the nodules were also calculated.

RESULTS

RFA with a low power of 20 W was used in the treatment of 37 patients with 38 PTMC nodules. All nodules achieved complete ablation, no complications occurred, and thyroid function was not affected. During follow-up, the volume of the nodules gradually decreased. Twelve months after ablation, the mean volumes of the nodules significantly decreased to 0.01±0.03 ml with a VRR of 99.34±3.49%. At a median follow-up of 6 (range: 1-18) months, 37 of the 38 nodules were completely absorbed, and no recurrence was observed in all 37 patients.

CONCLUSIONS

Low-power RFA showed good safety and promising efficacy outcomes for the treatment of PTMC. In addition to surgery and active surveillance, RFA may be an alternative treatment option for patients with PTMC.

Single-cell RNA expression profiling of SARS-CoV-2-related ACE2 and TMPRSS2 in human trophectoderm and placenta

OBJECTIVES

To examine the characteristics and distribution of possible severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) target cells in the human trophectoderm (TE) and placenta.

METHODS

Bioinformatics analysis was performed based on published single-cell transcriptomic datasets of early TE and first- and second-trimester human placentae. We conducted the transcriptomic analysis of 4198 early TE cells, 1260 first-trimester placental cells and 189 extravillous trophoblast cells (EVTs) from 24-week placentae (EVT_24W) using the SMART-Seq2 method. In addition, to confirm the bioinformatic results, we performed immunohistochemical staining of three first-trimester, three second-trimester and three third-trimester placentae from nine women recruited prospectively to this study. We evaluated the expression of the SARS-CoV-2-related molecules angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2).

RESULTS

Via bioinformatic analysis, we identified the existence of ACE2 and TMPRSS2 expression in human TE as well as in first- and second-trimester placentae. In the human TE, 54.4% of TE1 cells, 9.0% of cytotrophoblasts (CTBs), 3.2% of EVTs and 29.5% of syncytiotrophoblasts (STBs) were ACE2-positive. In addition, 90.7% of TE1 cells, 31.5% of CTBs, 22.1% of EVTs and 70.8% of STBs were TMPRSS2-positive. In placental cells, 20.4% of CTBs, 44.1% of STBs, 3.4% of EVTs from 8-week placentae (EVT_8W) and 63% of EVT_24W were ACE2-positive, while 1.6% of CTBs, 26.5% of STBs, 1.9% of EVT_8W and 20.1% of EVT_24W were TMPRSS2-positive. Pathway analysis revealed that EVT_24W cells that were positive for both ACE2 and TMPRSS2 (ACE2 + TMPRSS2-positive) were associated with morphogenesis of branching structure, extracellular matrix interaction, oxygen binding and antioxidant activity. The ACE2 + TMPRSS2-positive TE1 cells were correlated with an increased capacity for viral invasion, epithelial-cell proliferation and cell adhesion. Expression of ACE2 and TMPRSS2 was observed on immunohistochemical staining in first-, second- and third-trimester placentae.

CONCLUSIONS

ACE2- and TMPRSS2-positive cells are present in the human TE and placenta in all three trimesters of pregnancy, which indicates the possibility that SARS-CoV-2 could spread via the placenta and cause intrauterine fetal infection. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Modulation of Photocatalytic Properties by Strain in 2D BiOBr Nanosheets

BiOBr nanosheets with highly reactive {001} facets exposed were selectively synthesized by a facile hydrothermal method. The inner strain in the BiOBr nanosheets has been tuned continuously by the pH value. The photocatalytic performance of BiOBr in dye degradation can be manipulated by the strain effect. The low-strain BiOBr nanosheets show improved photocatalytic activity. Density functional calculations suggest that strain can modify the band structure and symmetry in BiOBr. The enhanced photocatalytic activity in low-strain BiOBr nanosheets is due to improved charge separation attributable to a highly dispersive band structure with an indirect band gap.

A highly selective turn-on fluorescent probe for Al(III) based on coumarin and its application in vivo

In this study, a turn-on coumarin-based fluorescent probe, 7-hydroxy-6-[(2-hydroxy-naphthalen-1-ylmethylene)-amino]-4-methyl-chroman-2-one (CN), was developed for detecting Al(3+) in aqueous systems. The binding ratio of CN-Al(3+) complexes was determined from the Job plot and ESI-MS data to be 1 : 1. The binding constant (Ka) of Al(3+) binding to CN was calculated to be 9.55 × 10(4) M(-1) from a Benesi-Hildebrand plot and the detection limit was evaluated to be as low as 0.10 μM (LOD = 3σ/slope). CN could be used as an effective fluorescent probe for detecting Al(3+) in living HeLa cells. Moreover, CN could also be applied in the in vivo detection of Al(3+) in zebrafish.

Solution and air stable host/guest architectures from a single layer covalent organic framework

Single-layer COF-1 hosts fullerene guests, which can be introduced by a brief immersion in fullerene solution.

Enrichment of Cdk1-cyclins at DNA double-strand breaks stimulates Fun30 phosphorylation and DNA end resection

DNA double-strand breaks (DSBs) are one of the most cytotoxic types of DNA lesion challenging genome integrity. The activity of cyclin-dependent kinase Cdk1 is essential for DSB repair by homologous recombination and for DNA damage signaling. Here we identify the Fun30 chromatin remodeler as a new target of Cdk1. Fun30 is phosphorylated by Cdk1 on Serine 28 to stimulate its functions in DNA damage response including resection of DSB ends. Importantly, Cdk1-dependent phosphorylation of Fun30-S28 increases upon DNA damage and requires the recruitment of Fun30 to DSBs, suggesting that phosphorylation increases in situ at the DNA damage. Consistently, we find that Cdk1 and multiple cyclins become highly enriched at DSBs and that the recruitment of Cdk1 and cyclins Clb2 and Clb5 ensures optimal Fun30 phosphorylation and checkpoint activation. We propose that the enrichment of Cdk1-cyclin complexes at DSBs serves as a mechanism for enhanced targeting and modulating of the activity of DNA damage response proteins.

Identification of in vitro metabolites of Indinavir by "intelligent automated LC-MS/MS" (INTAMS) utilizing triple quadrupole tandem mass spectrometry

In an effort to improve the efficiency of the TSQ 7000 LC-MS/MS system for identification of drug metabolites in biological matrices in support of drug discovery programs, a combination of instrument control language procedures for the Finnigan MAT TSQ 7000 mass spectrometer, referred to as INTAMS, were composed. INTAMS was designed to conduct unattended, automatic liquid chromatography/mass spectrometry (LC-MS) and LC-MS/MS analyses of drugs and metabolites in commonly encountered in vitro biological matrices. A novel peak detection algorithm was developed to automatically detect and record the pseudomolecular ions and retention times of chromatographic components, even if not fully resolved. This algorithm was used in combination with an automated technique for predicting the molecular weights of metabolites based on incremental changes of the molecular weight of the parent drug resulting from well-known biotransformation processes. When applied to a sample of an incubation mixture of the HIV protease inhibitor Indinavir with a rat liver S9 preparation, the results obtained by the automatic metabolite detection procedures for LC-MS and LC-MS/MS analyses in real time were the same as those which were determined manually, by a knowledgeable operator.

Resistance against Ralstonia solanacearum in tomato depends on the methionine cycle and the γ-aminobutyric acid metabolic pathway

Bacterial wilt caused by Ralstonia solanacearum is a complex and destructive disease that affects over 200 plant species. To investigate the interaction of R. solanacearum and its tomato (Solanum lycopersicum) plant host, a comparative proteomic analysis was conducted in tomato stems inoculated with highly and mildly aggressive R. solanacearum isolates (RsH and RsM, respectively). The results indicated a significant alteration of the methionine cycle (MTC) and downregulation of γ-aminobutyric acid (GABA) biosynthesis. Furthermore, transcriptome profiling of two key tissues (stem and root) at three stages (0, 3 and 5 days post-inoculation) with RsH in resistant and susceptible tomato plants is presented. Transcript profiles of MTC and GABA pathways were analyzed. Subsequently, the MTC-associated genes SAMS2, SAHH1 and MS1 and the GABA biosynthesis-related genes GAD2 and SSADH1 were knocked-down by virus-induced gene silencing and the plants' defense responses upon infection with R. solanacearum RsM and RsH were analyzed. These results showed that silencing of SAHH1, MS1 and GAD2 in tomato leads to decreased resistance against R. solanacearum. In summary, the infection assays, proteomic and transcriptomic data described in this study indicate that both MTC and GABA biosynthesis play an important role in pathogenic interaction between R. solanacearum and tomato plants.