Identification and characterization of TatD DNase in planarian Dugesia japonica and its antibiofilm effect.

TatD DNase, a key enzyme in vertebrates and invertebrates, plays a pivotal role in various physiological processes. Dugesia japonica (D. japonica), a flatworm species, has remarkable regenerative capabilities and possesses a simplified immune system. However, the existence and biological functions of TatD DNase in D. japonica require further investigation. Here, we obtained the open reading frame (ORF) of DjTatD and demonstrated its conservation. The three-dimensional structure of DjTatD revealed its active site and binding mechanism. To investigate its enzymological properties, we overexpressed, purified, and characterized recombinant DjTatD (rDjTatD). We observed that DjTatD was primarily expressed in the pharynx and its expression could be significantly challenged upon stimulation with lipopolysaccharide, peptidoglycan, gram-positive and gram-negative bacteria. RNA interference results indicated that both DjTatD and DjDN2s play a role in pharyngeal regeneration and may serve as functional complements to each other. Additionally, we found that rDjTatD and recombinant T7DjTatD effectively reduce biofilm formation regardless of their bacterial origin. Together, our results demonstrated that DjTatD may be involved in the planarian immune response and pharyngeal regeneration. Furthermore, after further optimization in the future, rDjTatD and T7DjTatD can be considered highly effective antibiofilm agents.

Flavihumibacter fluminis sp. nov., a novel thermotolerant bacterium isolated from river silt.

A yellow, Gram-stain-positive, strictly aerobic, thermotolerant, non-motile and rod-shaped bacterial strain, designated RY-1T, was isolated from a silt sample of Fuyang River, Wuqiang County, Hengshui City, Hebei Province, PR China. Cells showed oxidase- and catalase-positive activities. Growth occurred at 20-45 °C (optimum, 37 °C) and pH 6.0-8.0 (optimum, pH 7.0), and in the presence of 0-1.5 % (w/v) NaCl (optimum, 0%). A phylogenetic tree based on 16S rRNA gene sequences revealed that strain RY-1T formed a phylogenetic lineage with Flavihumibacter members within the family Chitinophagaceae. A comparison of 16S rRNA gene sequences showed that strain RY-1T was most closely related to Flavihumibacter cheonanensis WS16T (98.6 %), Flavihumibacter sediminis CJ663T (97.7 %) and Flavihumibacter solisilvae 3-3T (97.6 %). The genome size of strain RY-1T was 4.71 Mb, and the DNA G+C content was 44.3  %. The average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity values between strain RY-1T and reference strains were all lower than the threshold values for species delineation. Strain RY-1T contained menaquinone-7 and iso-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1G as the sole respiratory isoprenoid quinone and major cellular fatty acids (≥5 %), respectively. The major polar lipids consisted of phosphatidylethanolamine, three unidentified aminolipids and four unidentified lipids. According to the results of phenotypic, phylogenetic and chemotaxonomic characteristics, strain RY-1T represents a novel species of the genus Flavihumibacter, for which the name Flavihumibacter fluminis sp. nov. is proposed. The type strain is RY-1T (=GDMCC 1.2775T=JCM 34870T).

Sulfur metabolism in Rhodococcus species and their application in desulfurization of fossil fuels.

Organosulfur compounds in fossil fuels have been a major concern in the process of achieving zero-sulfur fuel production. Biodesulfurization (BDS) is an environmentally friendly strategy for the removal of refractory organosulfur compounds from fossil fuels. Even though researchers are committed to engineering the desulfurization-specific pathway for improving BDS efficiency, the industrial application of BDS is still difficult. Recently, the sulfur metabolism of Rhodococcus has begun to attract attention due to its influences on the BDS process. In this review, we introduce the sulfur metabolism in Rhodococcus, including sulfur absorption, reduction, and assimilation; and summarize desulfurization in Rhodococcus, including the desulfurization mechanism, the regulation mechanism of the 4S pathway, and the strategies of optimizing the 4S pathway to improve BDS efficiency. In particular, the influence of sulfur metabolism on BDS efficiency is discussed. In addition, we consider the latest genetic engineering strategies in Rhodococcus. An improved understanding of the relationship between sulfur metabolism and desulfurization will enable the industrial application of BDS.

Flavobacterium selenitireducens sp. nov., isolated from rhizosphere soil of ancient mulberry.

A Gram-stain-negative, non-motile, aerobic, yellow, convex, rod-shaped mesophilic bacterial strain, designated strain D33T, was isolated from rhizosphere soil of ancient mulberry in Dezhou city, Shandong province, PR China. The strain grew at 8-37 °C (optimum, 30 °C), pH 4-9 (optimum, pH 7) and growth occurred at 0.5-5.5 % (w/v) NaCl (optimally at 1 %). The results of the phylogenetic analyses of 16S rRNA gene and whole genome sequences indicated that D33T was closely related to members of the genus Flavobacterium and had the highest 16S rRNA gene sequence similarity with 'Flavobacterium agri' KACC 19300 (95.4 %), Flavobacterium ichthyis NST-5T (94.6 %), Flavobacterium ahnfeltiae KCTC 32467T (93.6 %) and Flavobacterium longum JCM 19141T (93.6 %). The genome size of D33T was 3.8 Mb and the DNA G+C content was 48.0 mol%. The average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH) and average amino acid identity (AAI) values among D33T and reference strains were lower than the threshold values for species delineation. The only respiratory quinone of D33T was menaquinone 6 (MK-6). The predominant fatty acids (>5 %) were C15:0, C16 : 0, C18 : 0, iso-C15:0, iso-C17 : 0 3-OH, anteiso-C15 : 0 and summed feature 9 . The polar lipid profile contained phosphatidylethanolamine, two unidentified aminophospholipids, three unidentified aminolipids and two unidentified lipids. Combined data from phenotypic, phylogenetic and chemotaxonomic studies indicated that D33T is a representative of a novel species of the genus Flavobacterium, for which the name Flavobacterium selenitireducens sp. nov. is proposed. The type strain is D33T (=GDMCC 1.1946T=KACC 22131T).

The Wnt/Ca2+ signaling pathway is essential for the regeneration of GABAergic neurons in planarian Dugesia japonica.

The growth and differentiation of neurons are critical events in the establishment of proper neuron connectivity and function. Planarians have a remarkable ability to completely regenerate a functional nervous system from a pluripotent stem cell population. Thus, planarians provide a powerful model to identify genes required for neuronal differentiation in vivo. The Wnt/Ca2+ signaling pathway is crucial for cancer development, arousing inflammatory responses, and neurodegeneration. We analyzed the expression patterns and RNAi phenotypes for members of the Wnt/Ca2+ signaling pathway in the planarian, Dugesia japonica. The expression of DjWnt5a, DjPLC-ß, DjCamKII, and DjCaln during regeneration was surprisingly similar and revealing in the regenerated brain. RNAi knockdown of DjWnt5a, DjPLC-ß, DjCamKII, and DjCaln led to defects in regenerated brains including brain partial deletions, incompact phenotypes at the posterior of the new brain, and lateral branches, which could not regenerate. Furthermore, the expressions of GAD and the number of GABAergic neurons decreased. Together, these results suggest that the Wnt/Ca2+ signaling pathway is required for GABAergic neuron regeneration.

Paraflavitalea devenefica sp. nov., isolated from urban soil.

A Gram-stain-negative, rod-shaped, mesophilic, milky white-pigmented, aerobic, non-spore-forming and non-flagellated bacterium, designated strain X16T, was isolated from urban soil of Zibo, Shandong, China. According to 16S rRNA gene sequence analysis, the isolate showed highest similarities with Paraflavitalea soli 5GH32-13T (97.6 %), Pseudoflavitalea soli KIS20-3T (96.2 %), Pseudobacter ginsenosidimutans Gsoil 221T (96.0 %) and Pseudoflavitalea rhizosphaerae T16R-265T (95.8 %). The neighbour-joining tree based on 16S rRNA gene sequences showed that strain X16T formed a subcluster with Paraflavitalea soli 5GH32-13T, and the subcluster was closely related to Pseudoflavitalea soli KIS20-3T, Pseudobacter ginsenosidimutans Gsoil 221T and Pseudoflavitalea rhizosphaerae T16R-265T. Strain X16T also formed a subcluster with Paraflavitalea soli 5GH32-13T in phylogenetic tree based on genomic sequences. The polar lipids are phosphatidylethanolamine, two unknown aminolipids, two unknown aminophospholipids, two unknown lipids and two unknown phospholipids. The major quinone of strain X16T is menaquinone-7 and the main fatty acids (>10 % of total fatty acids) of strain X16T are iso-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1 G. The genome length of strain X16T is 8.7 Mb with a DNA G+C content of 47.4 %. ANI values among strain X16T and strain Paraflavitalea soli 5GH32-13T, Pseudobacter ginsenosidimutans Gsoil 221T, and Pseudoflavitalea rhizosphaerae T16R-265T are 78.1, 70.7, 70.6 %, respectively. On the basis of the results of the polyphasic characterization presented in this study, it is concluded that strain X16T represents a novel species. Besides, strain X16T can detoxify high toxicity selenite [Se(IV)] to low toxicity elemental selenium [Se(0)], for which the name Paraflavitale devenefica sp. nov. is proposed. The type strain is X16T (=KACC 21698T=GDMCC1.1757T).

Synthetic small regulatory RNAs in microbial metabolic engineering.

Small regulatory RNAs (sRNAs) finely control gene expression in prokaryotes and synthetic sRNA has become a useful high-throughput approach to tackle current challenges in metabolic engineering because of its many advantages compared to conventional gene knockouts. In this review, we first focus on the modular structures of sRNAs and rational design strategies of synthetic sRNAs on the basis of their modular structures. The wide applications of synthetic sRNAs in bacterial metabolic engineering, with or without the aid of heterogeneously expressed Hfq protein, were also covered. In addition, we give attention to the improvements in implementing synthetic sRNAs, which make the synthetic sRNA strategy universally applicable in metabolic engineering and synthetic biology. KEY POINTS: • Synthetic sRNAs can be rationally designed based on modular structures of natural sRNAs. • Synthetic sRNAs were widely used for metabolic engineering in various microorganisms. • Several technological improvements made the synthetic sRNA strategy more applicable.

Potential targets for intervention against doxorubicin-induced cardiotoxicity based on genetic studies: a systematic review of the literature.

Cardiotoxicity is a well-known adverse effect of doxorubicin (Dox) administration, but the underlying molecular mechanism of this effect is not fully understood. Over the past two decades, considerable efforts have focused on the potential molecular targets of cardiotoxicity in the hope that novel targeted therapies will be generated to attenuate Dox-induced cardiotoxicity. Here, we provide a comprehensive overview of genetically modified animals that show enhanced or reduced susceptibility to the cardiotoxic effects of Dox. We focused on the process by which the molecules involved in DNA damage, oxidative stress, apoptosis, autophagy and necrosis are affected in the presence of Dox. We also present a protein-protein interaction network and explain the contribution of the components to the process of Dox-induced cardiotoxicity. More importantly, data from the literature have indicated that PI3Kγ and Rac1 are potential targets with therapeutic advantages in cancer therapy; molecules that target these proteins can simultaneously attenuate Dox-induced cardiotoxicity and enhance its anticancer activity. This review highlights the potential molecular targets that are critical regulators involved in Dox-mediated cardiotoxicity, thus providing further insight into the development of potential treatment strategies to prevent the cardiotoxic effects and enhance the anticancer efficiency of Dox in cancer patients.

Protein arginine methyltransferase 1 mediates regeneration in Dugesia japonica.

As a typical organism of platyhelminth, Dugesia japonica attracts more and more attention for its strong regenerative ability. Protein arginine methyltransferase (PRMT) family is composed of a class of enzymes with methyltransferase activities, which play fundamental roles in vivo in many important physiological processes. PRMT1 is a predominant type Ⅰ PRMT, which has been reported to be expressed in Schmidtea mediterranea. Nevertheless, the existence and the specific biological functions of PRMT1 in Dugesia japonica need further investigation. In this study, we acquired the full-length sequence of DjPRMT1 and confirmed it was a conserved protein. Thereafter, whole-mount in situ hybridization results showed DjPRMT1 was mainly expressed in neoblasts of adult worms, and obvious aggregation of DjPRMT1 was observed at the wound site in early stages of regeneration. Silencing of the DjPRMT1 gene retarded the movement of planarians with decreased DjPIWI-A expression, and DjPRMT1 knockdown also affected planarian regeneration with slightly attenuated proliferation around the blastema of posterior-facing wounds regeneration. In summary, these preliminary results demonstrated DjPRMT1 was involved in the regeneration of planarian.

Selection and characterization of a Vibrio parahaemolyticus OmpU antibody by phage display.

Vibrio parahaemolyticus (V. parahaemolyticus) is a well-known food-borne human pathogen that can cause a variety of clinical manifestations after the consumption of raw or undercooked seafoods. The crucial roles of Vibrio OmpU in bacterial pathogenesis have been found in recent studies. In the present study, we screened for single domain antibody fragment (sdAb) candidates that bind to V. parahaemolyticus OmpU by using a sdAb phage display library and isolated several positive phage clones. The UAb28, which was one of the positive clones, was shown high enrichment and affinity. The CDRs of UAb28 are speculated to perform the OmpU binding function by molecular docking. The capable of recognizing OmpU was verified by binding and inhibition assays. The UAb28 might be useful in future studies to develop the potential sdAb-based immunotherapeutics against V. parahaemolyticus infection.

Roseomonas selenitidurans sp. nov., isolated from urban soil, and emended description of Roseomonas frigidaquae.

An aerobic, non-motile, Gram-stain-negative, pink, convex, coccobacilli-shaped, mesophilic bacterium, designated strain BU-1T, was isolated from an urban soil sample from Zibo city, Shandong province, PR China. The strain grew at 20-37 °C (optimum, 30 °C), pH 5-10 (optimum, pH 7) and growth occurred with 0-2 % (w/v) NaCl (optimally with 0.5 %). The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that BU-1T was closely related to members of the genus Roseomonas and had highest 16S rRNA gene sequence similarities with Roseomonas frigidaquae JCM 15073T (97.8 %), Roseomonas tokyonensis JCM 14634T (96.9 %), Roseomonas stagni JCM 15034T (96.5 %), and Roseomonas riguiloci JCM 17520T (95.9 %). BU-1T also formed a subcluster with R. frigidaquae JCM 15073T and R. stagni JCM 15034T in phylogenetic trees based on genomic sequences. The genome size of BU-1T was 5.79 Mb and the DNA G+C content was 71.7 %. ANI, dDDH and AAI values between BU-1T and R. frigidaquae JCM 15073T were 84.0, 27.2 and 86.7 %, respectively. Furthermore, the genome of BU-1T contained 5446 predicted protein coding genes and 4945 (90.8%) of them had classifiable functions. BU-1T contained Q-10 as the main ubiquinone. The predominant fatty acids (>10 %) were summed feature 3, summed feature 8 and C16:0. The polar lipid profile contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and five unidentified aminolipids. Combined data from phenotypic, phylogenetic and chemotaxonomic studies indicated that strain BU-1T is a representative of a novel species of the genus Roseomonas. Since strain BU-1T can reduce highly toxic selenite [Se(IV)] to low toxicity elemental selenium [Se(0)], the name Roseomonas selenitidurans sp. nov. is proposed. The type strain is BU-1T (=KACC 21750T =GDMCC 1.1776T).

A novel agent attenuates cardiotoxicity and improves antitumor activity of doxorubicin in breast cancer cells.

Doxorubicin (Dox) is a well-known chemotherapeutic agent used in the treatment of various cancers. However, Dox-induced cardiotoxicity limits its further clinical use. We have previously reported a small molecular named biotin-conjugated ADTM analog (BAA) that exhibits cytoprotective effects against oxidative stress-induced cell injury in cardiomyoblast H9c2 cells. Here, the protective effects of BAA, indexed by attenuation of the cardiotoxicity induced by Dox as well as synergistic antitumor activity that increases the chemotherapeutic efficacy of Dox were investigated. Our results demonstrated that BAA significantly ameliorated Dox-induced toxicity in the H9c2 cells and zebrafish models. In addition, BAA attenuated Dox-induced endoplasmic reticulum (ER) stress in H9c2 cells. An ER stress inhibitor, 4-phenylbutyric acid, reversed the protective effect of BAA in H9c2 cells. In contrast, in human breast tumor MDA-MB-231 cells, BAA significantly enhanced Dox-induced cytotoxicity through upregulating Dox-induced ER stress response. Taken together, our findings indicate that Dox combined with BAA can significantly enhance its antitumor activity in breast cancer cells and reduce its cardiotoxicity, at least in part, by mediating ER stress activation.

Cloning and identification of Bartonella α-enolase as a plasminogen-binding protein.

Bartonella infection is distributed worldwide with animal and public health. Recent studies have shown that host cells infection by Bartonella has a series of different infection stages, beginning with encounter and adherence to the cells. In this study, we expressed and purified recombinant Bartonella henselae (B. henselae) α-enolase. And we found that B. henselae α-enolase is highly conserved in Bartonella species. The interacting protein partners of B. henselae α-enolase were showed by String-11. The interactions between B. henselae α-enolase and human plasminogen were subsequently confirmed by ELISA, pull down, T7 phage display and molecular docking assays. And the plasminogen-binding sites of B. henselae α-enolase are predicted at 247FYKNGSYFY255. These findings will help elucidate and improve the understanding of the molecular mechanisms of Bartonella infection.

Synthesis and biological activities evaluation of sanjuanolide and its analogues.

Sanjuanolide, psorachalcone A and its seven new analogues were synthesized via a combinatorial strategy by aldol reaction. In order to investigate the effect between electron density in π-conjugated systems and biological activities, several electron-withdrawing and electron-donating groups were introduced at C-4 and the phenolic hydroxyl groups of sanjuanolide. The two natural products and its seven new analogues were investigated for their inhibitory effects against five cancer cell lines. Moreover, the hydroxyisoprenyl group may be important to maintain the biological activities of sanjuanolide.

Molecular cloning and characterization of a novel Y-box gene from planarian Dugesia japonica.

Y-box binding protein (YB protein) is an ancient conserved multifunctional DNA/RNA-binding protein. A novel YB protein DjY2 gene from planarian Dugesia japonica was cloned by RACE method and characterized. This cDNA contains 689 bp with a putative open reading frame of 197 amino acids. It has a predicted molecular mass of 22.14 kDa and an isoelectric point of 9.67. Whole-mount in situ hybridization and relative quantitative real-time PCR were used to study the spatial and temporal expression pattern of DjY2 in the process of planarian regeneration. Results showed that DjY2 was expressed in many parts of the body in intact planarian, but the expression level was low in head and pharynx. The transcripts of DjY2 was significantly increased both at the head parts and the tail parts after amputation, especially at the site of cutting. The spatial expression gradually recovered to the state of intact planarian with the time of regeneration. Our results indicated that DjY2 might participate in the process of regeneration in planarian.

The inhibition of GSK-3ß promotes the production of reactive oxygen species via ß-catenin/C/EBPα signaling in the spleen of zebrafish (Danio rerio).

In this study, the mechanism that the inhibition of glycogen synthase kinase-3ß (GSK-3ß) promotes the production of reactive oxygen species (ROS) via ß-catenin/CCAAT/enhancer binding protein α (C/EBPα) signaling was investigated in the spleen of zebrafish (Danio rerio). The results demonstrated that the inhibition of GSK-3ß induced the mRNA expression of ß-catenin and C/EBPα by lithium (Li) treatments or GSK-3ß RNA interference. The levels of hydrogen peroxide (H2O2), superoxide anion (O2.-), and hydroxy radical (·OH) as well as the activity of superoxide dismutase (SOD) were increased, while the activities of catalase (CAT) and glutathione peroxidase (GSH-PX) were decreased in the spleen and ZF4 cells of zebrafish by Li+ treatments. In addition, GSK-3ß RNA interference increased ROS levels and decreased the activities of CAT and GSH-PX in the spleen. The fluorescence intensity of ROS was increased but the mitochondrial membrane potential (MMP) was decreased by Li+ treatments in ZF4 cells labeled with 2',7'-dichlorofluorescein diacetate (DCFH-DA) and Rhodamine-123, respectively. The results of present study indicated that the inhibition of GSK-3ß promoted the ROS production via ß-catenin/C/EBPα signaling in the spleen of zebrafish, and the balance between ROS and antioxidants could be destroyed by the GSK-3ß/ß-catenin/C/EBPα signaling. The results may be a valuable contribution to understanding the modulatory mechanism of GSK-3ß/ß-catenin/C/EBPα signaling on the antioxidant system in fish species.

Mitochondria-Targeting Small Molecules Effectively Prevent Cardiotoxicity Induced by Doxorubicin.

Doxorubicin (Dox) is a chemotherapeutic agent widely used for the treatment of numerous cancers. However, the clinical use of Dox is limited by its unwanted cardiotoxicity. Mitochondrial dysfunction has been associated with Dox-induced cardiotoxicity. To mitigate Dox-related cardiotoxicity, considerable successful examples of a variety of small molecules that target mitochondria to modulate Dox-induced cardiotoxicity have appeared in recent years. Here, we review the related literatures and discuss the evidence showing that mitochondria-targeting small molecules are promising cardioprotective agents against Dox-induced cardiac events.

Identification and functional analysis of invasion associated locus B (IalB) in Bartonella species.

Bartonellosis is caused by the genus Bartonella. Bartonella is widely distributed in the ruminants, cats, dogs, rodents and other mammals including humans. At least 13 species or subspecies of Bartonella are zoonotic, and each species appears to be highly adapted to one or a limited number of reservoir animals in which it is asymptomatic, while it can be transmitted to humans in which a variety of clinical manifestations can be caused. It was reported that Bartonella henselae infection rate among domestic cats was high in nature, making it one of the leading, important, and easily neglected zoonotic diseases. The aims of this study were to identify the expression, localization, immunogenicity and functional mechanism of Bartonella virulence factor IalB. We found that recombinant IalB protein could react with the serum from infected reservoir hosts and anti-IalB polyclonal antibodies could react with different Bartonella species by western blot analysis. According to these results, we proposed that IalB protein and anti-IalB antibodies would be good candidates for diagnosis of Bartonella infection by antigen-based anti-IalB antibodies or antibody-based IalB antigen capture immunoassay, respectively. We also found that IalB had a putative 22-amino-acid signal sequence and little IalB was localized to the outer membrane of Bartonella birtlesii by electron microscopy assay. Incubation with anti-IalB polyclonal antibodies resulted in inhibition of the invasion of mouse erythrocytes by B. birtlesii. According to these results, we propose that IalB could be a secreted protein that facilitates Bartonella entry into erythrocytes. In conclusion, these results improve our understanding of IalB as a candidate for immunodiagnosis and how IalB affects Bartonella-erythrocyte entry.

Microbial production of mevalonate.

Mevalonate, an important intermediate product of the mevalonate pathway, has a broad spectrum of applications. With the rapid growth of metabolic engineering and synthetic biology, mevalonate biosynthesis by microorganisms is feasible and holds great promise in the future. In this review, we summarize the applications of mevalonate and its derivatives and describe the biosynthesis pathways of mevalonate. The current status of mevalonate biosynthesis is also detailed with an emphasis on metabolic engineering strategies to enhance mevalonate production in typical industrial organisms, including Escherichia coli, Saccharomyces cerevisiae, and Pseudomonas putida, suggesting new insights for the efficient production of biosynthesized mevalonate.

DjFARP Contributes to the Regeneration and Maintenance of the Brain through Activation of DjRac1 in Dugesia japonica.

FERM, RhoGEF, and Pleckstrin domain protein (FARP) mediated RhoGTPase pathways are involved in diverse biological processes, such as neuronal development and tumorigenesis. However, little is known about their role in neural regeneration. We uncovered for the first time that FARP-Rac1 signaling plays an important role in neural regeneration in Dugesia japonica, a planarian that possesses unparalleled regenerative capacities. The planarian FARP homolog DjFARP was primarily expressed in both intact and regenerating brain and pharynx tissue. Functional studies suggested that downregulation of DjFARP with dsRNA in Dugesia japonica led to smaller brain sizes, defects in brain lateral branches, and loss of cholinergic, GABAergic, and dopaminergic neurons in both intact and regenerating animals. Moreover, the Rho GTPase DjRac1 was shown to play a similar role in neural regeneration and maintenance. Rac1 activation assay showed that DjFARP acts as a guanine nucleotide exchange factor (GEF) for DjRac1. Together, these findings indicate that the brain defects seen in DjFARP knockdown animals may be attributable to DjRac1 inactivation. In conclusion, our study demonstrated that DjFARP-DjRac1 signaling was required for the maintenance and proper regeneration of the brain in Dugesia japonica.