A 2D carbon nitride-based electrochemical aptasensor with reverse amplification for highly sensitive detection of okadaic acid in shellfish.

Okadaic acid (OA) is one of the main virulence factors of diarrheal shellfish toxins (DSP). It is of great significance to detect OA with an accurate, specific and cost-effective technique in the fields of seafood safety and water quality control. In this work, an electrochemical aptasensor with reverse amplification was developed for the sensitive detection of OA. A two-dimensional graphite-phase nanomaterial (carbon nitride) modified with an anti-OA aptamer and thionine (Th) was immobilized onto the surface of the electrochemical electrode as the sensitive element to capture target OA molecules. ssDNA-modified carbon nitride was used as the reverse amplification element by hybridizing with non-OA linked aptamers. The preparation of the electrochemical aptasensor was well characterized by Scanning Electron Microscopy (SEM), zeta potential detection, UV-Vis absorption, Brunner-Emmet-Teller (BET) measurements, and electrochemical measurements. The quantitative assessment of OA was achieved by differential pulse voltammetry (DPV). Experimental results indicated that this aptasensor showed a concentration-dependent response to OA with a good detection performance including in terms of selectivity, repeatability, reproducibility, and stability. It exhibited 100-fold selectivity between OA and other toxins including dinophysistoxins (DTX), pectenotoxins (PTX), and yessotoxins (YTX). In addition, it showed a much wider quantification range, which is 10-13 M-10-10 M (0.080-80.50 pg mL-1). The detection limit was as low as 10-13 M (0.080 pg mL-1). The aptasensor also successfully achieved significant practicality on real shellfish samples contaminated by OA. All these results demonstrated that the reverse amplification strategy for marine toxin detection may provide a label-free and rapid detection approach for portable applications in the fields of environmental monitoring and food security.

Application of Nanozymes in Environmental Monitoring, Management, and Protection.

Nanozymes are nanomaterials with enzyme-like activity, possessing the unique properties of nanomaterials and natural enzyme-like catalytic functions. Nanozymes are catalytically active, stable, tunable, recyclable, and versatile. Therefore, increasing attention has been paid in the fields of environmental science and life sciences. In this review, we focused on the most recent applications of nanozymes for environmental monitoring, environmental management, and environmental protection. We firstly introduce the tuning catalytic activity of nanozymes according to some crucial factors such as size and shape, composition and doping, and surface coating. Then, the application of nanozymes in environmental fields are introduced in detail. Nanozymes can not only be used to detect inorganic ions, molecules, organics, and foodborne pathogenic bacteria but are also involved in the degradation of phenolic compounds, dyes, and antibiotics. The capability of nanozymes was also reported for assisting air purification, constructing biofuel cells, and application in marine antibacterial fouling removal. Finally, the current challenges and future trends of nanozymes toward environmental fields are proposed and discussed.

Progress in the Development of Detection Strategies Based on Olfactory and Gustatory Biomimetic Biosensors.

The biomimetic olfactory and gustatory biosensing devices have broad applications in many fields, such as industry, security, and biomedicine. The development of these biosensors was inspired by the organization of biological olfactory and gustatory systems. In this review, we summarized the most recent advances in the development of detection strategies for chemical sensing based on olfactory and gustatory biomimetic biosensors. First, sensing mechanisms and principles of olfaction and gustation are briefly introduced. Then, different biomimetic sensing detection strategies are outlined based on different sensing devices functionalized with various molecular and cellular components originating from natural olfactory and gustatory systems. Thereafter, various biomimetic olfactory and gustatory biosensors are introduced in detail by classifying and summarizing the detection strategies based on different sensing devices. Finally, the future directions and challenges of biomimetic biosensing development are proposed and discussed.

Odor-induced modification of oscillations and related theta-higher gamma coupling in olfactory bulb neurons of awake and anesthetized rats.

Olfactory gamma oscillations (40-100 Hz) are generated spontaneously in animals and represent the activity of local olfactory bulb (OB) networks, which play important roles in cognitive mechanisms. In addition, high-frequency oscillations (HFO, 130-180 Hz) have attracted widespread attention and are novel neuronal oscillations with a frequency range closer to high gamma oscillations (60-100 Hz, HGOs). Both HGOs and HFOs are distinctly regulated by θ rhythm in the hippocampus. To understand their mediation mechanisms in the OB, we investigated whether local field potential (LFP) oscillations including HGOs and HFOs and even their coupling with theta rhythm are modified by odor stimulation in both freely moving and anesthetized rats. Therefore, we combined electrophysiological technology and cross-frequency coupling analysis approaches to determine the difference in the odor-modulated LFP oscillations between awake and anesthetized rats. The obtained results indicate that LFP oscillations including HGOs and HFOs were differently modified by odor stimulation in animals of both states. However, θ-HGO and θ-HFO coupling were modified in only awake animals. It is suggested that these oscillations and their interactions with theta oscillations may play crucial roles in olfactory network activity. This could pave the way for further understanding the underlying mechanisms of oscillations in OB neurons towards odor sensation.

In Vivo Bioelectronic Nose Based on a Bioengineered Rat Realizes the Detection and Classification of Multiodorants.

Inspired by the powerful capability of the biological olfactory system, we developed an in vivo bioelectronic nose based on a bioengineered rat by recording electrophysiological-responsive signals from the olfactory bulb with implanted multichannel microelectrodes. The bioengineered rat was prepared by overexpressing a selected olfactory receptor (OR3) on the rat olfactory epithelium, and multichannel electrophysiological signals were obtained from the mitral/tufted (M/T) cell population of the olfactory bulb. The classification of target multiodorants was realized by analyzing the redundant stimuli-responsive firing information. Ligand odorants induced significant firing changes with specific response patterns compared with nonligand odorants. The responsive curves were dependent on the concentration of target ligand odorants ranging from 10-6 to 10-3 M, and the detection limit was as low as 10-5 M. In addition, different ligand odorants were successfully discriminated via principal component analysis. This in vivo bioelectronic nose provides a novel approach for the detection of specific target odorants and has promising application potential in the field of rapid on-site odor discrimination.

Preparation and application of taste bud organoids in biomedicine towards chemical sensation mechanisms.

Taste is one of the most basic and important sensations that is able to monitor the food quality and avoid intake of potential danger materials. Whether as an inevitable symptom of aging or a complication of cancer treatment, taste loss very seriously affects the patient's life quality. Taste bud organoids provide an alternative and convenient approach for the research of taste functions and the underlying mechanisms due to their characteristics of availability, strong maneuverability, and high similarity to the in-vivo taste buds. This review gives a systemic and comprehensive introduction to the preparation and application of taste bud organoids towards chemical sensing mechanisms. First, the basic structures and functions of taste buds will be briefly introduced. Then, the currently available approaches for the preparation of taste bud organoids are summarized and discussed, which are mainly divided into two categories, that is, the stem/progenitor cell-derived approach and the tissue-derived approach. Next, different applications of taste bud organoids in biomedicine are outlined based on their central roles such as disease modeling, biological sensing, gene regulation, and signal transduction. Finally, the current challenges, future development trends, and prospects of research in taste bud organoids are proposed and discussed.

Isoleucine increases muscle mass through promoting myogenesis and intramyocellular fat deposition.

Isoleucine (Ile), as a branched-chain amino acid (BCAA), has a vital role in regulating body weight and muscle protein synthesis. However, the regulatory effect of Ile on muscle mass under high-fat diet (HFD) conditions and intramyocellular lipid deposition remains largely unclear. In this study, a feeding experiment with HFD with or without 25 g L-1 Ile was performed using 32 wild male C57BL/6J mice randomly divided into two groups. The results showed that Ile significantly increased both muscle and fat mass, as well as causing insulin resistance and meanwhile upregulating the levels of key adipogenic and myogenic proteins. More importantly, Ile damaged the mitochondrial function by vacuolation, swelling and cristae fracture in the gastrocnemius (GAS) and tibialis anterior (TA) with downregulation of mitochondrial function-related genes. Furthermore, Ile promoted myogenesis and more lipid droplet accumulation in myotubes. Compared with the control, the protein levels of myosin heavy chain (MyHC), myoblast determination protein 1 (MyoD), myogenin (MyoG), peroxisome proliferator-activated receptor gamma (PPARg) and fatty acid synthase (FAS) were upregulated in the Ile group, whereas the protein levels of adipose triglyceride lipase (ATGL) and lipoprotein lipase (LPL) were downregulated. Collectively, Ile increased muscle mass through myogenesis and intramyocellular lipid deposition. Our findings provide a new perspective for not only improving the lean juiciness of farm animals by increasing intramyocellular lipid accumulation, but also modulating myopathies under obesity.

MicroRNA-323-3p promotes myogenesis by targeting Smad2.

Skeletal muscle is an important and complex organ with multiple biological functions in humans and animals. Proliferation and differentiation of myoblasts are the key steps during the development of skeletal muscle. MicroRNA (miRNA) is a class of 21-nucleotide noncoding RNAs regulating gene expression by combining with the 3'-untranslated region of target messenger RNA. Many studies in recent years have suggested that miRNAs play a critical role in myogenesis. Through high-throughput sequencing, we found that miR-323-3p showed significant changes in the longissimus dorsi muscle of Rongchang pigs in different age groups. In this study, we discovered that overexpression of miR-323-3p repressed myoblast proliferation and promoted differentiation, whereas the inhibitor of miR-323-3p displayed the opposite results. Furthermore, we predicted Smad2 as the target gene of miR-323-3p and found that miR-323-3p directly modulated the expression level of Smad2. Then luciferase reporter assays verified that Smad2 was a target gene of miR-323-3p during the differentiation of myoblasts. These findings reveal that miR-323-3p is a positive regulator of myogenesis by targeting Smad2. This provides a novel mechanism of miRNAs in myogenesis.

Differences between porcine longissimus thoracis and semitendinosus intramuscular fat content and the regulation of their preadipocytes during adipogenic differentiation.

Intramuscular fat (IMF) plays an important role in pork quality. However, differences in the adipogenic regulation of IMF content between pig longissimus thoracis (LT) and semitendinosus (ST) remain unclear. Here, we found that IMF content of 180-day-old pig LT was greater than that of pig ST. Furthermore, lipid accumulation was earlier and greater in LT intramuscular preadipocytes (L-IMA) than in ST intramuscular preadipocytes (S-IMA) during differentiation. Interestingly, glucose consumption was lower in L-IMA than in S-IMA. Moreover, monounsaturated fatty acid content was greater in L-IMA than in S-IMA, whereas polyunsaturated fatty acid content was lower. Levels of the expression of key adipogenic genes were higher in L-IMA than S-IMA. Compared with S-IMA, adipogenic signals were more activated in L-IMA after adipogenic induction. In conclusion, IMF deposition differences between pig LT and ST were due to different glucose consumption, fatty acid composition, expression of key adipogenic genes and level of activating adipogenic signals between S-IMA and L-IMA during adipogenesis.

Comparative Analysis of Long Noncoding RNAs Expressed during Intramuscular Adipocytes Adipogenesis in Fat-Type and Lean-Type Pigs.

The meat quality of local breed pigs is more tender and juicier than the imported varieties. The important reason is that the intramuscular fat content is high. Even through modest sequence conservation and evolution, the expression pattern and function of long noncoding RNAs (lncRNAs) seem to be conserved. In spite of that, analysis of lncRNAs associated with intramuscular fat development remains unknown to us in porcine. Here, we systematically investigated lncRNAs of intramuscular adipocytes of fat local Bamei pigs and lean Large White pigs to consider the function of lncRNAs on intramuscular fat development. We selected three piglets of both breeds separately to isolate intramuscular preadipocytes, performed RNA sequencing across four stages (0, 2, 4, and 8 d) during the intramuscular preadipocytes differentiation, and identified 1932 lncRNAs (760 novel). In addition, we have screened lnc_000414 closely related to fat synthesis. This lncRNA function as an inhibitor in the proliferation of porcine intramuscular adipocytes. These novel findings will provide new targets for improving pork quality and making pig breeding better.

PDGFRα Regulated by miR-34a and FoxO1 Promotes Adipogenesis in Porcine Intramuscular Preadipocytes through Erk Signaling Pathway.

Suitable intramuscular fat (IMF) content improves porcine meat quality. The vital genes regulating IMF deposition are necessary for the selection and breeding of an IMF trait. However, the effect and mechanism of PDGFRα on IMF deposition are still unclear. Here, PDGFRα is moderately expressed in porcine longissimus dorsi muscle (LD), whereas it highly expressed in white adipose tissue (WAT). Moreover, PDGFRα-positive cells were located in the gaps of LD fibers which there were IMF adipocytes. Compared with 180-day-old and lean-type pigs, the levels of PDGFRα were much higher in one-day-old and fat-type pigs. Meanwhile the levels of PDGFRα gradually decreased during IMF preadipocyte differentiation. Furthermore, PDGFRα promoted adipogenic differentiation through activating Erk signaling pathway. Based on PDGFRα upstream regulation analysis, we found that the knockdown of FoxO1 repressed lipogenesis by downregulating PDGFRα, and miR-34a inhibited adipogenesis through targeting PDGFRα. Collectively, PDGFRα is a positive regulator of IMF deposition. Therefore, we suggest that PDGFRα is a possible target to improve meat quality.

MicroRNA 200a inhibits erythroid differentiation by targeting PDCD4 and THRB.

Previous studies on erythropoiesis revealed that microRNAs (miRNAs) play a critical role in erythroid differentiation. Given the abundance of identified miRNAs and the limited understanding of erythroid miRNAs, additional examination is required. Here, two sets of erythroid differentiation miRNome data were analysed to screen for novel erythroid-inhibiting miRNAs. MIR200A was selected based on its pattern of downregulated expression in the miRNome datasets during induction of erythroid differentiation. Overexpression of MIR200A in K562 and TF-1 cells confirmed its inhibitory role in erythroid differentiation. Further in vivo study indicated that overexpression of mir200a inhibited primitive erythropoiesis of zebrafish. Transcriptome analyses after MIR200A overexpression in TF-1 cells indicated a significant role in regulating erythroid function and revealed potential regulation networks. Additionally, bioinformatics and experimental analyses confirmed that PDCD4 (programmed cell death 4) and THRB (thyroid hormone receptor, beta) are both targets of MIR200A-3p. Gain- and loss-of-function studies of PDCD4 and THRB revealed that the two targets were capable of promoting erythroid gene expression. Overall, our results revealed that microRNA 200a inhibits erythroid differentiation by targeting PDCD4 and THRB.

MiR-218 Inhibits Erythroid Differentiation and Alters Iron Metabolism by Targeting ALAS2 in K562 Cells.

microRNAs (miRNAs) are involved in a variety of biological processes. The regulatory function and potential role of miRNAs targeting the mRNA of the 5'-aminolevulinate synthase 2 (ALAS2) in erythropoiesis were investigated in order to identify miRNAs which play a role in erythroid iron metabolism and differentiation. Firstly, the role of ALAS2 in erythroid differentiation and iron metabolism in human erythroid leukemia cells (K562) was confirmed by ALAS2 knockdown. Through a series of screening strategies and experimental validations, it was identified that hsa-miR-218 (miR-218) targets and represses the expression of ALAS2 by binding to the 3'-untranslated region (UTR). Overexpression of miR-218 repressed erythroid differentiation and altered iron metabolism in K562 cells similar to that seen in the ALAS2 knockdown in K562 cells. In addition to iron metabolism and erythroid differentiation, miR-218 was found to be responsible for a reduction in K562 cell growth. Taken together, our results show that miR-218 inhibits erythroid differentiation and alters iron metabolism by targeting ALAS2 in K562 cells.