Mechanism of the toxic effects of tetracycline on blood meal digestion in Haemaphysalis longicornis.

The extensive utilization of antibiotics in the field of animal husbandry gives rise to various concerns pertaining to the environment and human health. Here, we demonstrate that the administration of tetracycline impedes blood meal digestion in the tick Haemaphysalis longicornis. Tissue sectioning, 16S rRNA high-throughput sequencing, and transcriptome sequencing of the midgut were employed to elucidate the mechanism underlying tetracycline toxicity. The treatment group consisted of engorged female ticks that were subjected to tetracycline microinjections (75 µg per tick), whereas the control group received sterile water injections. On days 2 and 4 following the injections, the tick body weight changes were assessed and the midguts were dissected and processed. Change in tick body weight in tetracycline-treated group was less than in the control group. In tetracycline-treated ticks, midgut epithelial cells were loosely connected and blood meal digestion was impaired compared to the control group. There was no significant change in midgut bacterial diversity after tetracycline treatment. On day 2 following treatment, the relative abundance of Escherichia-Shigella was significantly decreased, whereas the relative abundance of Allorhizobium was significantly increased compared to the control group. On day 4 following treatment, the relative abundance of Escherichia-Shigella, Allorhizobium, Ochrobactrum, and Acidibacter decreased significantly, whereas the relative abundance of Paraburkholderia and Pelomonas increased significantly. Tetracycline treatment also affected midgut gene expression, producing a cumulative effect wherein the differentially expressed genes (DEGs) were mostly down-regulated. KEGG enrichment pathway analysis revealed that on day 2 the up-regulated DEGs were significantly enriched in 21 pathways, including apoptosis and phagosome. Comparatively, the down-regulated DEGs were significantly enriched in 26 pathways, including N-glycan biosynthesis, lysosome, and autophagy. In contrast, on day 4 the up-regulated DEGs were significantly enriched in 10 pathways including aminoacyl-tRNA biosynthesis, ribosome biogenesis, RNA transport, and DNA replication, whereas the down-regulated differential genes were significantly enriched in 11 pathways including lysosome, peroxisome, N-glycan biosynthesis, and fatty acid synthesis. This indicates that tetracycline injection inhibited blood meal digestion by affecting midgut digestive cells, gut flora diversity, and gene expression. These findings could contribute to tick control by inhibiting blood meal digestion.

Chemical Enhancement and Quenching in Single-Molecule Tip-Enhanced Raman Spectroscopy.

Despite intensive research in surface enhanced Raman spectroscopy (SERS), the influence mechanism of chemical effects on Raman signals remains elusive. Here, we investigate such chemical effects through tip-enhanced Raman spectroscopy (TERS) of a single planar ZnPc molecule with varying but controlled contact environments. TERS signals are found dramatically enhanced upon making a tip-molecule point contact. A combined physico-chemical mechanism is proposed to explain such an enhancement via the generation of a ground-state charge-transfer induced vertical Raman polarizability that is further enhanced by the strong vertical plasmonic field in the nanocavity. In contrast, TERS signals from ZnPc chemisorbed flatly on substrates are found strongly quenched, which is rationalized by the Raman polarizability screening effect induced by interfacial dynamic charge transfer. Our results provide deep insights into the understanding of the chemical effects in TERS/SERS enhancement and quenching.

Identification of Inosine and 2'-O-Methylinosine Modifications in Yeast Messenger RNA by Liquid Chromatography-Tandem Mass Spectrometry Analysis.

The discovery of reversible modifications in messenger RNA (mRNA) opens new research directions in RNA modification-mediated epigenetic regulation. Yeast is an extensively used model organism in molecular biology. Systematic investigation and profiling of modifications in yeast mRNA would promote our understanding of the physiological regulation mechanisms in yeast. However, due to the high abundance of ribosomal RNA (rRNA) and transfer RNA (tRNA) in total RNA, isolation of low abundance of mRNA frequently suffers from the contamination of rRNA and tRNA, which will lead to the false-positive determination and inaccurate quantification of modifications in mRNA. Therefore, obtaining high-purity mRNA is critical for precise determination and accurate quantification of modifications in mRNA, especially for studies that focus on discovering new ones. Herein, we proposed a successive orthogonal isolation method by combining polyT-based purification and agarose gel electrophoresis purification for extracting high-purity mRNA. With the extracted high-purity yeast mRNA, we systemically explored the modifications in yeast mRNA by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis. The results showed that in addition to the previously reported eight kinds of modifications, two novel modifications of inosine (Ino) and 2'-O-methylinosine (Im) were identified to be prevalent in yeast mRNA. It is worth noting that Im was reported for the first time, to the best of our knowledge, to exist in living organisms in the three domains of life. Moreover, we observed that the levels of 10 kinds of modifications including Ino and Im in yeast mRNA exhibited dynamic change at different growth stages of yeast cells. Furthermore, Im in mRNA showed a significant decrease while in response to H2O2 treatment. These results indicated that the two newly identified modifications in yeast mRNA were involved in yeast cell growth and response to environmental stress. Taken together, we reported two new modifications of Ino and Im in yeast mRNA, which expends the diversity of RNA modifications in yeast and also suggests new regulators for modulating yeast physiological functions.

Optical characteristics of bilayer decoupling MoS2 grown by the CVD method.

Study of exciton recombination process is of great significance for the optoelectronic device applications of two-dimensional transition metal chalcogenides (TMDCs). This research investigated the decoupling MoS2 structures by photoluminescence (PL) measurements. First, PL intensity of the bilayer MoS2 (BLM) is about twice of that of the single layer MoS2 (SLM) at low temperature, indicating no transition from direct bandgap to indirect bandgap for BLM due to the decrease of interlayer coupling which can be shown by Raman spectra. Then, the localized exciton emission appears for SLM at 7 K but none for BLM, showing different exciton localization characteristics. The PL evolution with respect to the excitation intensity and the temperature further reveal the filling, interaction, and the redistribution among free exciton states and localized exciton states. These results provide very useful information for understanding the localized states and carrier dynamics in BLM and SLM.

Angle-resolved polarized Raman spectra of the basal and edge plane of MoS2.

Angle-resolved polarized (ARP) Raman spectroscopy can be utilized to characterize the Raman modes of two-dimensional layered materials based on crystal symmetry or crystal orientation. In this paper, the polarization properties of E 1 2g and A1g modes on the basal plane and edge plane of high purity 2H-MoS2 bulk crystal grown by chemical vapor transport (CVT) method were investigated by ARP Raman spectroscopy. The I and II type ARP Raman spectroscopy with four kinds of polarization configurations: αY, αX, ßY, and ßX were used to explore the intensity dependence of E 1 2g and A1g modes at different planes on the polarization direction of incident/scattered light. The results show that the E 1 2g and A1g modes exhibit different polarization properties dependent on the polarization of the incident laser and the in-plane rotation of the sample at different planes. The experimental results were confirmed and analyzed through theoretical calculation. Our work sheds light on the intriguing effect of the subtle atomic structure in stacked MoS2 layers on the resulting ARP Raman properties. This provides a reference for the study of other two-dimensional layered crystalline materials by ARP Raman spectroscopy.

Probing the deformation of [12]cycloparaphenylene molecular nanohoops adsorbed on metal surfaces by tip-enhanced Raman spectroscopy.

[n]Cycloparaphenylene ([n]CPP) molecules have attracted broad interests due to their unique properties resulting from the distorted and strained aromatic hoop structures. In this work, we apply sub-nanometer resolved tip-enhanced Raman spectroscopy (TERS) to investigate the adsorption configurations and structural deformations of [12]CPP molecules on metal substrates with different crystallographic orientations. The TERS spectra for a [12]CPP molecule adsorbed on the isotropic Cu(100) surface are found to be essentially the same over the whole nanohoop, indicating an alternately twisted structure that is similar to the [12]CPP molecule in free space. However, when the [12]CPP molecules are adsorbed on the anisotropic Ag(110) surface, the molecular shape is found to be severely deformed into two types of adsorption configurations: one showing an interesting "Möbius-like" feature and the other showing a symmetric bending structure. Their TERS spectral features are found to be site-dependent over the hoop and even show peak splitting for the out-of-plane C-H bending vibrations. The deformed structural models gain strong support from the spatial distribution of "symmetric" TERS spectra at different positions on the hoop. Further TERS imaging, with a spatial resolution down to ∼2 Å, provides a panoramic view on the local structural deformations caused by different tilting of the benzene units in real space, which offers insights into the subtle changes in the aromatic properties over the deformed hoop owing to inhomogeneous molecule-substrate interactions. The ability of TERS to probe the molecular structure and local deformation at the sub-molecular level, as demonstrated here, is important for understanding surface science as well as molecular electronics and optoelectronics at the nanoscale.

Tetracycline inhibits tick host reproduction by modulating bacterial microbiota, gene expression and metabolism levels.

BACKGROUND: Ticks are disease vectors that are a matter of worldwide concern. Antibiotic treatments have been used to explore the interactions between ticks and their symbiotic microorganisms. In addition to altering the host microbial community, antibiotics can have toxic effects on the host. RESULTS: In the tick Haemaphysalis longicornis, engorged females showed reproductive disruption after microinjection of tetracycline. Multi-omics approaches were implemented to unravel the mechanisms of tick reproductive inhibition in this study. There were no significant changes in bacterial density in the whole ticks on Day (D)2 or D4 after tetracycline treatment, whereas the bacterial microbial community was significantly altered, especially on D4. The relative abundances of the bacteria Staphylococcus, Bacillus and Pseudomonas decreased after tetracycline treatment, whereas the relative abundances of Coxiella and Rhodococcus increased. Ovarian transcriptional analysis revealed a cumulative effect of tetracycline treatment, as there was a significant increase in the number of differentially expressed genes with treatment time and a higher number of downregulated genes. The tick physiological pathways including lysosome, extracellular matrix (ECM)-receptor interaction, biosynthesis of ubiquinone and other terpenoids-quinones, insect hormone biosynthesis, and focal adhesion were significantly inhibited after 4 days of tetracycline treatment. Metabolite levels were altered after tetracycline treatment and the differences increased with treatment time. The differential metabolites were involved in a variety of physiological pathways; the downregulated metabolites were significantly enriched in the nicotinate and nicotinamide metabolism, galactose metabolism, and ether lipid metabolism pathways. CONCLUSIONS: These findings indicate that tetracycline inhibits tick reproduction through the regulation of tick bacterial communities, gene expression and metabolic levels. The results may provide new strategies for tick control. © 2023 Society of Chemical Industry.

Comparing the effects of dexmedetomidine and dexamethasone as perineural adjuvants on peripheral nerve block: A PRISMA-compliant systematic review and meta-analysis.

BACKGROUND: Dexmedetomidine (Dexm), a selective alpha-2 adrenoceptor agonist, and dexamethasone (Dexa), a very potent and highly selective glucocorticoid, have both been proven effectively to prolong the duration of local anesthetics (LA) in regional anesthesia. However, data comparing the efficacy of Dexm and Dexa as perineural adjuvants are inconsistent. Therefore, this systematic review and meta-analysis of randomized and quasi-randomized controlled trials (RCTs) was conducted to compare the effects of Dexm and Dexa when used as LA adjuvants on peripheral nerve block (PNB). METHODS: We systematically searched PubMed, Cochrane Library, EMBASE, Web of Science, and ScienceDirect databases up to October, 2020. The primary outcome was the duration of analgesia. Secondary outcomes included incidence of rescue analgesia, cumulative opioid consumption, time required for onset of sensory and motor blockades, duration of sensory and motor blockades, incidence of postoperative nausea and vomiting (PONV), and side effect-associated outcomes (e.g., bradycardia, sedation, hypotension, rates of infection, and neurological complications). The study was registered on PROSPERO, number CRD42020188796. RESULTS: After screening of full-text relevant articles, 13 RCTs that met the inclusion criteria were retrieved for this systematic review. It was revealed that perineural Dexm provided equivalent analgesic duration to perineural Dexa. Besides, the intake of Dexm increased the incidence of rescue analgesia in limbs surgery, as well as the cumulative opioid consumption, and decreased the time required for onset of sensory and motor blockades for long-acting LA (all P < .05). Other analysis revealed insignificant difference between the 2 groups in terms of the incidence of PONV (P > .05). Additionally, 2 studies demonstrated that Dexm possesses more sedative properties than Dexa (P < .05). CONCLUSIONS: This meta-analysis indicated that the analgesic duration of Dexm and Dexa as LA adjuvants in PNB is the same. Meanwhile, the effects of perineural Dexm and Dexa on some secondary outcomes, including the incidence of rescue analgesia, cumulative opioid consumption, and time required for onset of sensory and motor blockades, are associated with the surgical site and type of LA.

[Clinical observation on wheat grain moxibustion for chronic superficial gastritis of spleen-stomach deficiency and cold].

OBJECTIVE: To compare the clinical effect of wheat grain moxibustion and warming acupuncture on chronic superficial gastritis of spleen-stomach deficiency and cold. METHODS: A total of 200 patients with chronic superficial gastritis of spleen-stomach deficiency and cold were randomly divided into a wheat grain moxibustion group (100 cases, 13 cases dropped off ) and a warming acupuncture group (100 cases, 16 cases dropped off ). The acupoints of Zhongwan (CV 12), Tianshu (ST 25), Qihai (CV 6), Liangqiu (ST 34) and Zusanli (ST 36) were selected in both groups. The patients in the wheat grain moxibustion group were treated with wheat grain moxibustion, and 5 cone were given on every acupoint each time. Moxibustion was performed after acupuncture in the warming acupuncture group, and 3 cone each acupoint. Both groups were treated every other day for 15 times. The scores of clinical symptoms and signs, scores of physical component summary (PCS) and mental component summary (MCS) of quality of life in the two groups were recorded before and after treatment and during follow-up 1 month after treatment, and the clinical effects of the two groups were evaluated after treatment and during follow-up. RESULTS: After treatment and during follow-up, the scores of clinical symptoms and signs of the two groups were lower than before treatment (P<0.05), and the scores of PCS and MCS of quality of life were higher than before treatment (P<0.05). At follow-up, the score of clinical symptoms and signs in the wheat grain moxibustion group was lower than that in the warming acupuncture group (P<0.01), and the scores of PCS and MCS of quality of life were higher than those in the warming acupuncture group (P<0.001). The total effective rate of the wheat grain moxibustion group was 93.1% (81/87), which was higher than 82.1% (69/84) of the warming acupuncture group at follow-up (P<0.001). CONCLUSION: The wheat grain moxibustion can effectively improve the clinical symptoms, signs and quality of life in patients with chronic superficial gastritis of spleen-stomach deficiency and cold, and its long-term effect is better than warming acupuncture.

Britannin stabilizes T cell activity and inhibits proliferation and angiogenesis by targeting PD-L1 via abrogation of the crosstalk between Myc and HIF-1α in cancer.

BACKGROUND: Programmed cell death-ligand 1 (PD-L1) is overexpressed in tumor cells, which causes tumor cells to escape T cell killing, and promotes tumor cell survival, cell proliferation, migration, invasion, and angiogenesis. Britannin is a natural product with anticancer pharmacological effects. PURPOSE: In this work, we studied the anticancer potential of britannin and explored whether britannin mediated its effect by inhibiting the expression of PD-L1 in tumor cells. METHODS: In vitro, the mechanisms underlying the inhibition of PD-L1 expression by britannin were investigated by MTT assay, homology modeling and molecular docking, RT-PCR, western blotting, co-immunoprecipitation, and immunofluorescence. The changes in tumor killing activity, cell proliferation, cell cycle, migration, invasion, and angiogenesis were analyzed by T cell killing assays, EdU labeling, colony formation, flow cytometry, wound healing, matrigel transwell invasion, and tube formation, respectively. In vivo, the antitumor activity of britannin was evaluated in the HCT116 cell xenograft model. RESULTS: Britannin reduced the expression of PD-L1 in tumor cells by inhibiting the synthesis of the PD-L1 protein but did not affect the degradation of the PD-L1 protein. Britannin also inhibited HIF-1α expression through the mTOR/P70S6K/4EBP1 pathway and Myc activation through the Ras/RAF/MEK/ERK pathway. Mechanistically, britannin inhibited the expression of PD-L1 by blocking the interaction between HIF-1α and Myc. In addition, britannin could enhance the activity of cytotoxic T lymphocytes and inhibit tumor cell proliferation and angiogenesis by inhibiting PD-L1. Finally, in vivo observations were confirmed by demonstrating the antitumor activity of britannin in a murine xenograft model. CONCLUSION: Britannin inhibits the expression of PD-L1 by blocking the interaction between HIF-1α and Myc. Moreover, britannin stabilizes T cell activity and inhibits proliferation and angiogenesis by inhibiting PD-L1 in cancer. The current work highlights the anti-tumor effect of britannin, providing insights into the development of cancer therapeutics via PD-L1 inhibition.

Determination of cytidine modifications in human urine by liquid chromatography - Mass spectrometry analysis.

Both DNA cytosine methylation (5-methyl-2'-deoxycytidine, m5dC) and RNA cytosine methylation (5-methylcytidine, m5rC) are important epigenetic marks that play regulatory roles in diverse biological processes. m5dC and m5rC can be further oxidized by the ten-eleven translocation (TET) proteins to form 5-hydroxymethyl-2'-deoxycytidine (hm5dC) and 5-hydroxymethylcytidine (hm5rC), respectively. 2'-O-methyl-5-hydroxymethylcytidine (hm5rCm) was recently also identified as a second oxidative metabolite of m5rC in RNA. Previous studies showed that the dysregulation of cytidine modifications in both DNA and RNA are closely related to a variety of human diseases. These cytidine modifications are generally excreted from cell into urine. If these cytidine modifications exhibit specific features related to certain diseases, determination of the cytidine modifications in urine could be utilized as non-invasive diagnostic of diseases. Here, we established a solid-phase extraction in combination with liquid chromatography-mass spectrometry (LC-MS/MS) analysis for simultaneous detection of these cytidine modifications in human urine samples. The developed method enabled the distinct detection of these cytidine modifications. We reported, for the first time, the presence of hm5rCm in human urine. Furthermore, we found that compared to the healthy controls, the contents of hm5dC, hm5rC, and hm5rCm showed significant increases in urine samples of cancer patients, including lymphoma patients, gastric cancer patients, and esophageal cancer patients. This study indicates that the urinary hydroxylmethylation modifications of hm5dC, hm5rC, and hm5rCm may serve as potential indicator of cancers.

Visually constructing the chemical structure of a single molecule by scanning Raman picoscopy.

The strong spatial confinement of a nanocavity plasmonic field has made it possible to visualize the inner structure of a single molecule and even to distinguish its vibrational modes in real space. With such ever-improved spatial resolution, it is anticipated that full vibrational imaging of a molecule could be achieved to reveal molecular structural details. Here we demonstrate full Raman images of individual vibrational modes at the ångström level for a single Mg-porphine molecule, revealing distinct characteristics of each vibrational mode in real space. Furthermore, by exploiting the underlying interference effect and Raman fingerprint database, we propose a new methodology for structural determination, which we have called 'scanning Raman picoscopy', to show how such ultrahigh-resolution spectromicroscopic vibrational images can be used to visually assemble the chemical structure of a single molecule through a simple Lego-like building process.

Bacterial Community Diversity and Screening of Growth-Affecting Bacteria From Isochrysis galbana Following Antibiotic Treatment.

Algal cultures are generally co-cultures of algae and bacteria, especially when considering outdoor cultivation. However, the effects of associated bacteria on algal growth remain largely unexplored, particularly in the context of Isochrysis galbana. In the present study, we investigated the effects of antibiotic on the growth of I. galbana and its associated bacterial community. We found advantageous responses of I. galbana to antibiotic exposure, evidenced by the increased growth, and the maximal photochemical efficiency of PSII (Fv/Fm). Since antibiotics can cause major disturbances within bacterial community, we further conducted 16S rDNA amplicon sequencing to determine the changes of bacterial community diversity following antibiotic treatment. We found that antibiotic treatment considerably and negatively affected the abundance and diversity of bacterial community, and 17 significantly decreased bacterial species in the antibiotic-treated medium, including Pseudomonas stutzeri, were identified. Further co-culture experiments revealed that P. stutzeri inhibited the growth of I. galbana, and the inhibitory activity was retained in the cell-free bacterial filtrate. These results indicated that the negative effect of bacteria was not exclusively transmitted through contact with I. galbana but could be also mediated via secretory compounds. Taken together, our findings not only fully characterized the bacterial community associated with I. galbana and how the bacterial community changed in response to antibiotic perturbations, but also provided a valuable information about the interactions between I. galbana and its associated bacteria, which might help improve the yield, and quality of I. galbana during its cultivation processes.

Abdominal paracentesis drainage ameliorates severe acute pancreatitis in rats by regulating the polarization of peritoneal macrophages.

AIM: To investigate the role of peritoneal macrophage (PM) polarization in the therapeutic effect of abdominal paracentesis drainage (APD) on severe acute pancreatitis (SAP). METHODS: SAP was induced by 5% Na-taurocholate retrograde injection in Sprague-Dawley rats. APD was performed by inserting a drainage tube with a vacuum ball into the lower right abdomen of the rats immediately after the induction of SAP. To verify the effect of APD on macrophages, PMs were isolated and cultured in an environment, with the peritoneal inflammatory environment simulated by the addition of peritoneal lavage in complete RPMI 1640 medium. Hematoxylin and eosin staining was performed. The levels of pancreatitis biomarkers amylase and lipase as well as the levels of inflammatory mediators in the blood and peritoneal lavage were determined. The polarization phenotypes of the PMs were identified by detecting the marker expression of M1/M2 macrophages via flow cytometry, qPCR and immunohistochemical staining. The protein expression in macrophages that had infiltrated the pancreas was determined by Western blot. RESULTS: APD treatment significantly reduced the histopathological scores and levels of amylase, lipase, tumor necrosis factor-α and interleukin (IL)-1ß, indicating that APD ameliorates the severity of SAP. Importantly, we found that APD treatment polarized PMs towards the M2 phenotype, as evidenced by the reduced number of M1 macrophages and the reduced levels of pro-inflammatory mediators, such as IL-1ß and L-selectin, as well as the increased number of M2 macrophages and increased levels of anti-inflammatory mediators, such as IL-4 and IL-10. Furthermore, in an in vitro study wherein peritoneal lavage from the APD group was added to the cultured PMs to simulate the peritoneal inflammatory environment, PMs also exhibited a dominant M2 phenotype, resulting in a significantly lower level of inflammation. Finally, APD treatment increased the proportion of M2 macrophages and upregulated the expression of the anti-inflammatory protein Arg-1 in the pancreas of SAP model rats. CONCLUSION: These findings suggest that APD treatment exerts anti-inflammatory effects by regulating the M2 polarization of PMs, providing novel insights into the mechanism underlying its therapeutic effect.