Reconstructing dynamics correlation network to simultaneously improve activity and stability of 2,3-butanediol dehydrogenase by design of distal interchain disulfide bonds.

The complete enzyme catalytic cycle includes substrate binding, chemical reaction and product release, in which different dynamic conformations are adopted. Due to the complex relationship among enzyme activity, stability and dynamics, the directed evolution of enzymes for improved activity or stability commonly leads to a trade-off in stability or activity. It hence remains a challenge to engineer an enzyme to have both enhanced activity and stability. Here, we have attempted to reconstruct the dynamics correlation network involved with active center to improve both activity and stability of a 2,3-butanediol dehydrogenase (2,3-BDH) by introducing inter-chain disulfide bonds. A computational strategy was first applied to evaluate the effect of introducing inter-chain disulfide bond on activity and stability of three 2,3-BDHs, and the N258C mutation of 2,3-BDH from Corynebacterium glutamicum (CgBDH) was proved to be effective in improving both activity and stability. In the results, CgBDH-N258C showed a different unfolding curve from the wild type, with two melting temperatures (Tm) of 68.3 °C and 50.8 °C, 19.7 °C and 2 °C higher than 48.6 °C of the wild type. Its half-life was also improved by 14.8-fold compared to the wild type. Catalytic efficiency (kcat/Km) of the mutant was increased by 7.9-fold toward native substrate diacetyl and 8.8-fold toward non-native substrate 2,5-hexanedione compared to the wild type. Molecular dynamics simulations revealed that an interaction network formed by Cys258, Arg162, Ala144 and the catalytic residues was reconstructed in the mutant and the dynamics change caused by the disulfide bond could be propagated through the interactions network. This improved the enzyme stability and activity by decreasing the flexibility and locking more "reactive" pose, respectively. Further construction of mutations including A144G showing a 44-fold improvement in catalytic efficiency toward meso-2,3-BD confirmed the role of modifying dynamics correlation network in tunning enzyme activity and selectivity. This study provided important insights into the relationship among dynamics, enzyme catalysis and stability, and will be useful in the designing new enzymes with co-evolution of stability, activity and selectivity.

pH sensor based on tilted fiber Bragg grating surface plasmon resonance with a polyaniline reaction deposition film layer.

In this paper, we propose a surface plasmon resonance (SPR) fiber-optic pH sensor combined with a tilted fiber Bragg grating (TFBG) by continuously coating gold and polyaniline (PANI) onto the surface of a TFBG. The micron-scale thickness polyaniline film provides the sensor with good sensitivity, and it achieves accurate measurement of pH values ranging from 2 to 12 by utilizing the pH-responsive mechanism of PANI and the surface plasmon resonance characteristics. Experimental results show that within the 2-12 pH range, the sensitivity of the TFBG surface plasmon resonance pH sensor based on PANI coating is 0.50335 nm/pH, and results demonstrate, a linear correlation coefficient between wavelength and pH value reaching 0.96614. This indicates significant potential for future engineering applications in real-world pH measurement using this sensor.

Regulation of quantum spin conversions in a single molecular radical.

Free radicals, generally formed through the cleavage of covalent electron-pair bonds, play an important role in diverse fields ranging from synthetic chemistry to spintronics and nonlinear optics. However, the characterization and regulation of the radical state at a single-molecule level face formidable challenges. Here we present the detection and sophisticated tuning of the open-shell character of individual diradicals with a donor-acceptor structure via a sensitive single-molecule electrical approach. The radical is sandwiched between nanogapped graphene electrodes via covalent amide bonds to construct stable graphene-molecule-graphene single-molecule junctions. We measure the electrical conductance as a function of temperature and track the evolution of the closed-shell and open-shell electronic structures in real time, the open-shell triplet state being stabilized with increasing temperature. Furthermore, we tune the spin states by external stimuli, such as electrical and magnetic fields, and extract thermodynamic and kinetic parameters of the transition between closed-shell and open-shell states. Our findings provide insights into the evolution of single-molecule radicals under external stimuli, which may proof instrumental for the development of functional quantum spin-based molecular devices.

The Influence of Laser Process Parameters on the Adhesion Strength between Electroless Copper and Carbon Fiber Composites Determined Using Response Surface Methodology.

Laser process technology provides a feasible method for directly manufacturing surface-metallized carbon fiber composites (CFCs); however, the laser's process parameters strongly influence on the adhesion strength between electroless copper and CFCs. Here, a nanosecond ultraviolet laser was used to fabricate electroless copper on the surface of CFCs. In order to achieve good adhesion strength, four key process parameters, namely, the laser power, scanning line interval, scanning speed, and pulse frequency, were optimized experimentally using response surface methodology, and a central composite design was utilized to design the experiments. An analysis of variance was conducted to evaluate the adequacy and significance of the developed regression model. Also, the effect of the process parameters on the adhesion strength was determined. The numerical analysis indicated that the optimized laser power, scanning line interval, scanning speed, and pulse frequency were 5.5 W, 48.2 µm, 834.0 mm/s, and 69.5 kHz, respectively. A validation test confirmed that the predicted results were consistent with the actual values; thus, the developed mathematical model can adequately predict responses within the limits of the laser process parameters being used.

Rice Grain Detection and Counting Method Based on TCLE-YOLO Model.

Thousand-grain weight is the main parameter for accurately estimating rice yields, and it is an important indicator for variety breeding and cultivation management. The accurate detection and counting of rice grains is an important prerequisite for thousand-grain weight measurements. However, because rice grains are small targets with high overall similarity and different degrees of adhesion, there are still considerable challenges preventing the accurate detection and counting of rice grains during thousand-grain weight measurements. A deep learning model based on a transformer encoder and coordinate attention module was, therefore, designed for detecting and counting rice grains, and named TCLE-YOLO in which YOLOv5 was used as the backbone network. Specifically, to improve the feature representation of the model for small target regions, a coordinate attention (CA) module was introduced into the backbone module of YOLOv5. In addition, another detection head for small targets was designed based on a low-level, high-resolution feature map, and the transformer encoder was applied to the neck module to expand the receptive field of the network and enhance the extraction of key feature of detected targets. This enabled our additional detection head to be more sensitive to rice grains, especially heavily adhesive grains. Finally, EIoU loss was used to further improve accuracy. The experimental results show that, when applied to the self-built rice grain dataset, the precision, recall, and mAP@0.5 of the TCLE-YOLO model were 99.20%, 99.10%, and 99.20%, respectively. Compared with several state-of-the-art models, the proposed TCLE-YOLO model achieves better detection performance. In summary, the rice grain detection method built in this study is suitable for rice grain recognition and counting, and it can provide guidance for accurate thousand-grain weight measurements and the effective evaluation of rice breeding.

Screening and optimization of phage display cyclic peptides against the WDR5 WBM site.

Of the various WD40 family proteins, WDR5 is a particularly important multifunctional adaptor protein that can bind to several protein complexes to regulate gene activation, so it was considered as a promising epigenetic target in anti-cancer drug development. Despite many inhibitors having been discovered directing against the arginine-binding cavity in WDR5 called the WIN site, the side hydrophobic cavity called the WBM site receives rather scant attention. Herein, we aim to obtain novel WBM-targeted peptidic inhibitors with high potency and selectivity. We employed two improved biopanning approaches with a disulfide-constrained cyclic peptide phage library containing 7 randomized residues and identified several peptides with micromole binding activity by docking and binding assay. To further optimize the stability and activity, 9 thiol-reactive chemical linkers were utilized in the cyclization of the candidate peptide DH226027, which had good binding affinity. This study provides an effective method to discover potent peptides targeting protein-protein interactions and highlights a broader perspective of peptide-mimic drugs.

Unravelling the Superiority of Nonbenzenoid Acepleiadylene as a Building Block for Organic Semiconducting Materials.

Acepleiadylene (APD), a nonbenzenoid isomer of pyrene, exhibits a unique charge-separated character with a large molecular dipole and a small optical gap. However, APD has never been explored in optoelectronic materials to take advantage of these appealing properties. Here, we employ APD as a building block in organic semiconducting materials for the first time, and unravel the superiority of nonbenzenoid APD in electronic applications. We have synthesized an APD derivative (APD-IID) with APD as the terminal donor moieties and isoindigo (IID) as the acceptor core. Theoretical and experimental investigations reveal that APD-IID has an obvious charge-separated structure and enhanced intermolecular interactions as compared with its pyrene-based isomers. As a result, APD-IID displays significantly higher hole mobilities than those of the pyrene-based counterparts. These results imply the advantages of employing APD in semiconducting materials and great potential of nonbenzenoid polycyclic arenes for optoelectronic applications.

BsLPMO10A from Bacillus subtilis boosts the depolymerization of diverse polysaccharides linked via ß-1,4-glycosidic bonds.

Lytic polysaccharide monooxygenase (LPMO) is known as an oxidatively cleaving enzyme in recalcitrant polysaccharide deconstruction. Herein, we report a novel AA10 LPMO derived from Bacillus subtilis (BsLPMO10A). A substrate specificity study revealed that the enzyme exhibited an extensive active-substrate spectrum, particularly for polysaccharides linked via ß-1,4 glycosidic bonds, such as ß-(Man1 â†’ 4Man), ß-(Glc1 â†’ 4Glc) and ß-(Xyl1 â†’ 4Xyl). HPAEC-PAD and MALDI-TOF-MS analyses indicated that BsLPMO10A dominantly liberated native oligosaccharides with a degree of polymerization (DP) of 3-6 and C1-oxidized oligosaccharides ranging from DP3ox to DP6ox from mixed linkage glucans and beechwood xylan. Due to its synergistic action with a variety of glycoside hydrolases, including glucanase IDSGLUC5-38, xylanase TfXYN11-1, cellulase IDSGLUC5-11 and chitinase BtCHI18-1, BsLPMO10A dramatically accelerated glucan, xylan, cellulose and chitin saccharification. After co-reaction for 72 h, the reducing sugars in Icelandic moss lichenan, beechwood xylan, phosphoric acid swollen cellulose and chitin yielded 3176 ± 97, 7436 ± 165, 649 ± 44, and 2604 ± 130 µmol/L, which were 1.47-, 1.56-, 1.44- and 1.25-fold higher than those in the GHs alone groups, respectively (P < 0.001). In addition, the synergy of BsLPMO10A and GHs was further validated by the degradation of natural feedstuffs, the co-operation of BsLPMO10A and GHs released 3266 ± 182 and 1725 ± 107 µmol/L of reducing sugars from Oryza sativa L. and Arachis hypogaea L. straws, respectively, which were significantly higher than those produced by GHs alone (P < 0.001). Furthermore, BsLPMO10A also accelerated the liberation of reducing sugars from Celluclast® 1.5 L, a commercial cellulase cocktail, on filter paper, A. hypogaea L. and O. sativa L. straws by 49.58 % (P < 0.05), 72.19 % (P < 0.001) and 54.36 % (P < 0.05), respectively. This work has characterized BsLPMO10A with a broad active-substrate scope, providing a promising candidate for lignocellulosic biomass biorefinery.

The Impact of an Authoritarian Personality on Pro-Environmental Behaviour for Air Pollution Mitigation through Interactions with Social Norms.

This study examines how risk perception and authoritarian personality affect public engagement in mitigating air pollution. Data were collected (n = 2010) from 13 Chinese cities with varying air pollution gradients using questionnaires. The results demonstrated that air pollution was significantly correlated with people's risk perception and concern about air pollution, which significantly affected their pro-environmental behaviour (PEB). However, high-risk perceptions undermine the public's self-efficacy and reduce people's PEB in the private sphere. People with high scores of the authoritarian personality type were reluctant to engage in PEB in the private sphere; interestingly, it can also be transformed into a stronger PEB in the public sphere via social norms. Thus, this study suggests that educational activities can break the negative link between authoritarianism and environmentalism, leading to behavioural change. Hence, it is essential for education programs to harvest positive outcomes via adaptive approaches for varying authoritarian personalities.

BdPUL12 depolymerizes ß-mannan-like glycans into mannooligosaccharides and mannose, which serve as carbon sources for Bacteroides dorei and gut probiotics.

Symbiotic bacteria, including members of the Bacteroides genus, are known to digest dietary fibers in the gastrointestinal tract. The metabolism of complex carbohydrates is restricted to a specified subset of species and is likely orchestrated by polysaccharide utilization loci (PULs) in these microorganisms. ß-Mannans are plant cell wall polysaccharides that are commonly found in human nutrients. Here, we report the structural basis of a PUL cluster, BdPUL12, which controls ß-mannan-like glycan catabolism in Bacteroides dorei. Detailed biochemical characterization and targeted gene disruption studies demonstrated that a key glycoside hydrolase, BdP12GH26, performs the initial attack on galactomannan or glucomannan likely via an endo-acting mode, generating mannooligosaccharides and mannose. Importantly, coculture assays showed that the B. dorei promoted the proliferation of Lactobacillus helveticus and Bifidobacterium adolescentis, likely by sharing mannooligosaccharides and mannose with these gut probiotics. Our findings provide new insights into carbohydrate metabolism in gut-inhabiting bacteria and lay a foundation for novel probiotic development.

Revisiting Acepleiadylene: Two-Step Synthesis and π-Extension toward Nonbenzenoid Nanographene.

Acepleiadylene (APD), a nonbenzenoid nonalternant isomer of pyrene, exhibits different electronic properties from pyrene, but has been rarely studied since its first synthesis in 1956, probably due to the difficulties in synthesis and further derivatization. In this work, we revisited this long-known compound and developed a new two-step synthetic route to efficiently access APD on the gram scale. Theoretical and experimental characterizations elucidated the unique properties of APD as compared with its benzenoid isomer pyrene, particularly revealing its dipolar structure with a narrow optical gap. The functionalization of APD was demonstrated for the first time, providing doubly brominated APD as a key precursor for further π-extension. As a proof of concept, a π-extended APD and a cyclotrimer nanographene (C48H24) were constructed, opening up new avenues to nonbenzenoid nanographenes with low HOMO-LUMO gaps.

Phage-Display Based Discovery and Characterization of Peptide Ligands against WDR5.

WD40 is a ubiquitous domain presented in at least 361 human proteins and acts as scaffold to form protein complexes. Among them, WDR5 protein is an important mediator in several protein complexes to exert its functions in histone modification and chromatin remodeling. Therefore, it was considered as a promising epigenetic target involving in anti-cancer drug development. In view of the protein-protein interaction nature of WDR5, we initialized a campaign to discover new peptide-mimic inhibitors of WDR5. In current study, we utilized the phage display technique and screened with a disulfide-based cyclic peptide phage library. Five rounds of biopanning were performed and isolated clones were sequenced. By analyzing the sequences, total five peptides were synthesized for binding assay. The four peptides are shown to have the moderate binding affinity. Finally, the detailed binding interactions were revealed by solving a WDR5-peptide cocrystal structure.

Hedgehog-like Bi2S3 nanostructures: a novel composite soft template route to the synthesis and sensitive electrochemical immunoassay of the liver cancer biomarker.

An effective electrochemical immunosensor for detecting the liver cancer biomarker was developed based on the hedgehog-like Bi2S3 nanostructure, which was synthesized using novel CTAB-trimellitic acid as a composite soft template and thiourea as the sulfur source by a simple hydrothermal method with 20-fold sensitivity enhancement and one order of magnitude increase of linear range. The electrochemical immunosensor presented excellent performance, and could be applied to detect the cancer biomarker in clinical serum samples.

A novel bifunctional glucanase exhibiting high production of glucose and cellobiose from rumen bacterium.

Herbivores gastrointestinal microbiota is of tremendous interest for mining novel lignocellulosic enzymes for bioprocessing. We previously reported a set of potential carbohydrate-active enzymes from the metatranscriptome of the Hu sheep rumen microbiome. In this study, we isolated and heterologously expressed two novel glucanase genes, Cel5A-h38 and Cel5A-h49, finding that both recombinant enzymes showed the optimum temperatures of 50 °C. Substrate-specificity determination revealed that Cel5A-h38 was exclusively active in the presence of mixed-linked glucans, such as barley ß-glucan and Icelandic moss lichenan, whereas Cel5A-h49 (EC 3.2.1.4) exhibited a wider substrate spectrum. Surprisingly, Cel5A-h38 initially released only cellotriose from lichenan and further converted it into an equivalent amount of glucose and cellobiose, suggesting a dual-function as both endo-ß-1,3-1,4-glucanase (EC 3.2.1.73) and exo-cellobiohydrolase (EC 3.2.1.91). Additionally, we performed enzymatic hydrolysis of sheepgrass (Leymus chinensis) and rice (Orysa sativa) straw using Cel5A-h38, revealing liberation of 1.91 ± 0.30 mmol/mL and 2.03 ± 0.09 mmol/mL reducing sugars, respectively, including high concentrations of glucose and cellobiose. These results provided new insights into glucanase activity and lay a foundation for bioconversion of lignocellulosic biomass.

Enhanced stability of a rumen-derived xylanase using SpyTag/SpyCatcher cyclization.

Microbiota from herbivore rumen is of great interest for mining glycoside hydrolases for lignocellulosic biomass biorefinement. We previously isolated a highly active but poorly thermostable xylanase (LXY) from a rumen fluid fosmid library of Hu sheep, a local high-reproductive species in China. In this study, we used a universal enzyme-engineering strategy called SpyTag/SpyCatcher molecular cyclization to improve LXY stability via isopeptide-bond-mediated ligation. Both linear and cyclized LXY (L- and C-LXY, respectively) shared similar patterns of optimal pH and temperature, pH stability, and kinetic constants (km and Vmax). However, the C-LXY showed enhanced thermostability, ion stability, and resilience to aggregation and freeze-thaw treatment than L-LXY, without compromise of its catalytic efficiency. Circular dichroism and intrinsic and 8-anilino-1-naphthalenesulfonic acid-binding fluorescence analysis indicated that the cyclized enzyme was more capable of maintaining its secondary and tertiary structures than the linear enzyme. Taken together, these results promote the cyclized enzyme for potential applications in the feed, food, paper pulp, and bioenergy industries.

Transcriptome Analysis Reveals That Alfalfa Promotes Rumen Development Through Enhanced Metabolic Processes and Calcium Transduction in Hu Lambs.

A healthy gut is very important for young animal development. The rumen of ruminants expands in size with the colonization of microbiota by 2 months of age. This process is promoted by alfalfa intervention. To elucidate the mechanism of this promotion, we performed transcriptomic analyses using a cohort of 23 lambs to evaluate the effects of starter diets plus alfalfa on the development of the rumen wall from the pre- to the postweaning period. The quantitative PCR analyses were used to validate selected genes that were differentially expressed in the transcriptome mapping. We found that several metabolic processes associated with rumen tissue development were affected by solid feed intake, with genes linked to the calcium signaling transduction pathway and the metabolism of pteridine-containing compounds and homocysteine metabolic process being upregulated in the group with alfalfa intervention. The results suggest that the pteridine-containing compounds and calcium signaling are targets for precise regulation of rumen development.

Metatranscriptomics of the Hu sheep rumen microbiome reveals novel cellulases.

BACKGROUND: Cellulosic biomass has great potential as a renewable biofuel resource. Robust, high-performance enzymes are needed to effectively utilize this valuable resource. In this study, metatranscriptomics was used to explore the carbohydrate-active enzymes (CAZymes), especially glycoside hydrolases (GHs), present in the rumen microbiome of Hu sheep. Select CAZymes were experimentally verified and characterized after cloning and expression in E. coli. RESULTS: The metatranscriptomes of six Hu sheep rumen microbiomes yielded 42.3 Gbp of quality-checked sequence data that represented in total 2,380,783 unigenes after de novo assembling using Trinity and clustered with CD-HIT-EST. Annotation using the CAZy database revealed that 2.65% of the unigenes encoded GHs, which were assigned to 111 different CAZymes families. Firmicutes (18.7%) and Bacteroidetes (13.8%) were the major phyla to which the unigenes were taxonomically assigned. In total, 14,489 unigenes were annotated to 15 cellulase-containing GH families, with GH3, GH5 and GH9 being the predominant. From these putative cellulase-encoding unigenes, 4225 open reading frames (ORFs) were predicted to contain 2151 potential cellulase catalytic modules. Additionally, 147 ORFs were found to encode proteins that contain carbohydrate-binding modules (CBMs). Heterogeneous expression of 30 candidate cDNAs from the GH5 family in E. coli BL21 showed that 17 of the tested proteins had endoglucanase activity, while 7 exhibited exoglucanase activity. Interestingly, two of the GH5 proteins (Cel5A-h28 and Cel5A-h11) showed high specific activity against carboxymethylcellulose (CMC) and p-nitrophenyl-ß-d-cellobioside (pNPC) (222.2 and 142.8 U/mg), respectively. The optimal pH value for activity of Cel5A-h11 and Cel5A-h28 was 6.0 for both enzymes, and optimal temperatures were 40 and 50 °C, respectively. Both enzymes retained over 70 and 60%, respectively, of their original activities after incubation at 40 °C for 60 min. However, their activities were rapidly diminished upon exposure to higher temperatures. Cel5A-h11 and Cel5A-h28 retained more than 80 and 60% of their maximal enzymatic activities after incubation for 16 h in buffered solutions in the pH range from 4.0 to 9.0. CONCLUSION: The metatranscriptomic results revealed that the rumen microbiome of Hu sheep encoded a repertoire of new enzymes capable of cellulose degradation and metatranscriptomics was an effective method to discover novel cellulases for biotechnological applications.

Reversible Dilation of Cerebral Macrovascular Changes in MELAS Episodes.

PURPOSE: To investigate the cerebral macrovascular changes as well as the relationship of large vessels and cerebral blood flow (CBF) in mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) using magnetic resonance angiography (MRA) and arterial spin labeling (ASL) perfusion MR imaging (MRI). METHODS: A total of 20 patients diagnosed with MELAS (12 males, 8 females; mean age, 23.3 years) underwent conventional MRI, time-of-flight (TOF) MRA and three dimensional ASL. Follow-up scans were performed in 10 patients. The changes of cerebral arteries and branches on MRA images from both acute and recovery patients were independently evaluated by two radiologists. Lesion distribution and CBF were observed on the integrated maps of MRA and ASL. RESULTS: In 14 patients with clinical onsets, increased CBF was observed in all stroke-like lesions. Dilations of a single artery (four middle cerebral arteries, two posterior cerebral arteries) were found in six patients. Dilations of multiple arteries (two anterior cerebral arteries, seven middle cerebral arteries, six posterior cerebral arteries) were found in seven patients. Normal angiography was shown in one acute patient. Cortical terminal branches feeding the lesion areas were more obviously dilated than the main trunks. The dilated vessels returned to normal on follow-up scans concurrently with decreased CBF in nine patients who were resuscitated from episode attacks. Vasodilation was even seen in one preclinical patient who suffered a recurrent episode 50 days later. CONCLUSION: Reversible dilation of cerebral macrovascular changes could be a new feature of MELAS and a presumed reason for fluctuant CBF. It would shed new light on the mitochondrial angiopathy.

SpyTag/SpyCatcher molecular cyclization confers protein stability and resilience to aggregation.

The capacities for thermal and inhibitor tolerance are critical for industrial enzymes and loss of activity is a major challenge in deploying natural enzymes for commercial applications. Protein engineering approaches, such as site-directed mutagenesis and directed evolution, have been devoted to modifying natural enzymes. Recently, a post-translation protein engineering strategy, the SpyTag/SpyCatcher system, was introduced. Here, we have generated a thermo- and ion-tolerant cyclized xylanase (C-TFX) by fusing the SpyTag and SpyCatcher peptides to its N- and C- terminus respectively. Compared with the linear enzyme, C-TFX retained greater residual activity after heating or metal ion exposure. Intrinsic fluorescence and circular dichroism analysis revealed that the isopeptide bond mediated by SpyTag/SpyCatcher cyclization contributed to enhanced thermo- and ion-stability, probably by stabilizing its secondary and conformational structure. In addition, the heat-challenged C-TFX was observed to degrade natural lignocellulosic substrates efficiently. The cyclized xylanase was more stable and resistent to denaturation and aggregation than the linear enzyme. The "superglue" SpyTag/SpyCatcher cyclization system enables the enzyme to maintain its structural conformation, which will be of particular interest in engineering of enzymes for industrial application such as feed additives and functional oligosaccharides production.

Identification of microRNAs with heat stress responsive and immune properties in Marsupenaeus japonicus based on next-generation sequencing and bioinformatics analysis: Essential regulators in the heat stress-host interactions.

Summer mortality syndrome is one of the most serious issue for Marsupenaeus japonicus aquaculture in China. Since it causes massive economic loss and threatens sustainability of M. japonicus aquaculture industry, thus, there is an urgent desire to reveal the heat stress-host interactions mechanisms that lead to mass mortalities of M. japonicus in hot summer months. MicroRNAs (miRNAs) are small noncoding RNAs that involved in regulation of diverse biological processes, including stress and immune response, and might serve as potential regulators in the heat stress-host interactions. In the present study, miRNAs with heat stress responsive and immune properties were identified and characterized in M. japonicus by small RNA sequencing and bioinformatics analysis. In total, 79 host miRNAs were identified, among which 15 miRNAs were differentially expressed in response to heat stress. Target genes prediction and function annotation revealed that a variety of host cellular processes, such as signal transduction, transcription, anti-stress response, ribosomal biogenesis, lipid metabolism, cytoskeleton, etc, were potentially subject to miRNA-mediated regulation in response to heat stress. Furthermore, a total of 30 host miRNAs that potentially involved in interaction with white spot syndrome virus (WSSV) were obtained via predicting and analyzing the target genes from WSSV. The results showed that a batch of WSSV genes that code for structural proteins and enzymes that are essential for WSSV infection and proliferation, such as envelope proteins, capsid proteins, immediate-early proteins, collagen-like protein, protein kinase, thymidylate synthetase, TATA-box bind protein, etc, were predicted to be targeted by host miRNAs. Several of the host miRNAs with predicted antiviral capacity were down-regulated under heat stress, indicating a repression of host miRNA-mediated antiviral immune response. This study highlighted the essential roles of host miRNAs in the heat stress-host interactions and provided valuable information for further investigation on the mechanism of miRNA-mediated heat stress and immune response of shrimp.