Odd-Paired is Involved in Morphological Divergence of Snail-Feeding Beetles.

Body shape and size diversity and their evolutionary rates correlate with species richness at the macroevolutionary scale. However, the molecular genetic mechanisms underlying the morphological diversification across related species are poorly understood. In beetles, which account for one-fourth of the known species, adaptation to different trophic niches through morphological diversification appears to have contributed to species radiation. Here, we explored the key genes for the morphological divergence of the slender to stout body shape related to divergent feeding methods on large to small snails within the genus Carabus. We show that the zinc-finger transcription factor encoded by odd-paired (opa) controls morphological variation in the snail-feeding ground beetle Carabus blaptoides. Specifically, opa was identified as the gene underlying the slender to stout morphological difference between subspecies through genetic mapping and functional analysis via gene knockdown. Further analyses revealed that changes in opa cis-regulatory sequences likely contributed to the differences in body shape and size between C. blaptoides subspecies. Among opa cis-regulatory sequences, single nucleotide polymorphisms on the transcription factor binding sites may be associated with the morphological differences between C. blaptoides subspecies. opa was highly conserved in a wide range of taxa, especially in beetles. Therefore, opa may play an important role in adaptive morphological divergence in beetles.

Antibody Screening System Using a Herpes Simplex Virus (HSV)-Based Probe To Identify a Novel Target for Receptor-Retargeted Oncolytic HSVs.

Herpes simplex virus (HSV) is a promising tool for developing oncolytic virotherapy. We recently reported a platform for receptor-retargeted oncolytic HSVs that incorporates single-chain antibodies (scFvs) into envelope glycoprotein D (gD) to mediate virus entry via tumor-associated antigens. Therefore, it would be useful to develop an efficient system that can screen antibodies that might mediate HSV entry when they are incorporated as scFvs into gD. We created an HSV-based screening probe by the genetic fusion of a gD mutant with ablated binding capability to the authentic HSV entry receptors and the antibody-binding C domain of streptococcal protein G. This engineered virus failed to enter cells through authentic receptors. In contrast, when this virus was conjugated with an antibody specific to an antigen on the cell membrane, it specifically entered cells expressing the cognate antigen. This virus was used as a probe to identify antibodies that mediate virus entry via recognition of certain molecules on the cell membrane other than authentic receptors. Using this method, we identified an antibody specific to epiregulin (EREG), which has been investigated mainly as a secreted growth factor and not necessarily for its precursor that is expressed in a transmembrane form. We constructed an scFv from the anti-EREG antibody for insertion into the retargeted HSV platform and found that the recombinant virus entered cells specifically through EREG expressed by the cells. This novel antibody-screening system may contribute to the discovery of unique and unexpected molecules that might be used for the entry of receptor-retargeted oncolytic HSVs.IMPORTANCE The tropism of the cellular entry of HSV is dependent on the binding of the envelope gD to one of its authentic receptors. This can be fully retargeted to other receptors by inserting scFvs into gD with appropriate modifications. In theory, upon binding to the engineered gD, receptors other than authentic receptors should induce a conformational change in the gD, which activates downstream mechanisms required for viral entry. However, prerequisite factors for receptors to be used as targets of a retargeted virus remain poorly understood, and it is difficult to predict which molecules might be suitable for our retargeted HSV construct. Our HSV-based probe will allow unbiased screening of antibody-antigen pairs that mediate virus entry and might be a useful tool to identify suitable pairs for our construct and to enhance our understanding of virus-cell interactions during infection by HSV and possibly other viruses.

Gene expression analysis of three homeobox genes throughout early and late development of a feather star Anneissia japonica.

Crinoids are considered as the most basal extant echinoderms. They retain aboral nervous system with a nerve center, which has been degraded in the eleutherozoan echinoderms. To investigate the evolution of patterning of the nervous systems in crinoids, we examined temporal and spatial expression patterns of three neural patterning-related homeobox genes, six3, pax6, and otx, throughout the development of a feather star Anneissia japonica. These genes were involved in the patterning of endomesodermal tissues instead of the ectodermal neural tissues in the early planktonic stages. In the stages after larval attachment, the expression of these genes was mainly observed in the podia and the oral nervous systems instead of the aboral nerve center. Our results indicate the involvement of these three genes in the formation of oral nervous system in the common ancestor of the echinoderms and suggest that the aboral nerve center is not evolutionally related to the brain of other bilaterians.

Construction of full-length Japanese reference panel of class I HLA genes with single-molecule, real-time sequencing.

Human leukocyte antigen (HLA) is a gene complex known for its exceptional diversity across populations, importance in organ and blood stem cell transplantation, and associations of specific alleles with various diseases. We constructed a Japanese reference panel of class I HLA genes (ToMMo HLA panel), comprising a distinct set of HLA-A, HLA-B, HLA-C, and HLA-H alleles, by single-molecule, real-time (SMRT) sequencing of 208 individuals included in the 1070 whole-genome Japanese reference panel (1KJPN). For high-quality allele reconstruction, we developed a novel pipeline, Primer-Separation Assembly and Refinement Pipeline (PSARP), in which the SMRT sequencing and additional short-read data were used. The panel consisted of 139 alleles, which were all extended from known IPD-IMGT/HLA sequences, contained 40 with novel variants, and captured more than 96.5% of allelic diversity in 1KJPN. These newly available sequences would be important resources for research and clinical applications including high-resolution HLA typing, genetic association studies, and analyzes of cis-regulatory elements.

Syncytial Mutations Do Not Impair the Specificity of Entry and Spread of a Glycoprotein D Receptor-Retargeted Herpes Simplex Virus.

Membrane fusion, which is the key process for both initial cell entry and subsequent lateral spread of herpes simplex virus (HSV), requires the four envelope glycoproteins gB, gD, gH, and gL. Syncytial mutations, predominantly mapped to the gB and gK genes, confer hyperfusogenicity on HSV and cause multinucleated giant cells, termed syncytia. Here we asked whether interaction of gD with a cognate entry receptor remains indispensable for initiating membrane fusion of syncytial strains. To address this question, we took advantage of mutant viruses whose viral entry into cells relies on the uniquely specific interaction of an engineered gD with epidermal growth factor receptor (EGFR). We introduced selected syncytial mutations into gB and/or gK of the EGFR-retargeted HSV and found that these mutations, especially when combined, enabled formation of extensive syncytia by human cancer cell lines that express the target receptor; these syncytia were substantially larger than the plaques formed by the parental retargeted HSV strain. We assessed the EGFR dependence of entry and spread separately by using direct entry and infectious center assays, respectively, and we found that the syncytial mutations did not override the receptor specificity of the retargeted viruses at either stage. We discuss the implications of these results for the development of more effective targeted oncolytic HSV vectors. IMPORTANCE: Herpes simplex virus (HSV) is investigated not only as a human pathogen but also as a promising agent for oncolytic virotherapy. We previously showed that both the initial entry and subsequent lateral spread of HSV can be retargeted to cells expressing tumor-associated antigens by single-chain antibodies fused to a receptor-binding-deficient envelope glycoprotein D (gD). Here we introduced syncytial mutations into the gB and/or gK gene of gD-retargeted HSVs to determine whether viral tropism remained dependent on the interaction of gD with the target receptor. Entry and spread profiles of the recombinant viruses indicated that gD retargeting does not abolish the hyperfusogenic activity of syncytial mutations and that these mutations do not eliminate the dependence of HSV entry and spread on a specific gD-receptor interaction. These observations suggest that syncytial mutations may be valuable for increasing the tumor-specific spreading of retargeted oncolytic HSV vectors.

Methylome diversification through changes in DNA methyltransferase sequence specificity.

Epigenetic modifications such as DNA methylation have large effects on gene expression and genome maintenance. Helicobacter pylori, a human gastric pathogen, has a large number of DNA methyltransferase genes, with different strains having unique repertoires. Previous genome comparisons suggested that these methyltransferases often change DNA sequence specificity through domain movement--the movement between and within genes of coding sequences of target recognition domains. Using single-molecule real-time sequencing technology, which detects N6-methyladenines and N4-methylcytosines with single-base resolution, we studied methylated DNA sites throughout the H. pylori genome for several closely related strains. Overall, the methylome was highly variable among closely related strains. Hypermethylated regions were found, for example, in rpoB gene for RNA polymerase. We identified DNA sequence motifs for methylation and then assigned each of them to a specific homology group of the target recognition domains in the specificity-determining genes for Type I and other restriction-modification systems. These results supported proposed mechanisms for sequence-specificity changes in DNA methyltransferases. Knocking out one of the Type I specificity genes led to transcriptome changes, which suggested its role in gene expression. These results are consistent with the concept of evolution driven by DNA methylation, in which changes in the methylome lead to changes in the transcriptome and potentially to changes in phenotype, providing targets for natural or artificial selection.

Quantitative analysis of glycosaminoglycans, chondroitin/dermatan sulfate, hyaluronic acid, heparan sulfate, and keratan sulfate by liquid chromatography-electrospray ionization-tandem mass spectrometry.

We developed a method using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) with a selected reaction monitoring (SRM) mode for simultaneous quantitative analysis of glycosaminoglycans (GAGs). Using one-shot analysis with our MS/MS method, we demonstrated the simultaneous quantification of a total of 23 variously sulfated disaccharides of four GAG classes (8 chondroitin/dermatan sulfates, 1 hyaluronic acid, 12 heparan sulfates, and 2 keratan sulfates) with a sensitivity of less than 0.5 pmol within 20 min. We showed the differences in the composition of GAG classes and the sulfation patterns between porcine articular cartilage and yellow ligament. In addition to the internal disaccharides described above, some saccharides derived from the nonreducing terminal were detected simultaneously. The simultaneous quantification of both internal and nonreducing terminal saccharides could be useful to estimate the chain length of GAGs. This method would help to establish comprehensive "GAGomic" analysis of biological tissues.

The genome of Lyophyllum shimeji provides insight into the initial evolution of ectomycorrhizal fungal genomes.

Mycorrhizae are one of the most fundamental symbioses between plants and fungi, with ectomycorrhizae being the most widespread in boreal forest ecosystems. Ectomycorrhizal fungi are hypothesized to have evolved convergently from saprotrophic ancestors in several fungal clades, especially members of the subdivision Agaricomycotina. Studies on fungal genomes have identified several typical characteristics of mycorrhizal fungi, such as genome size expansion and decreases in plant cell-wall degrading enzymes (PCWDEs). However, genomic changes concerning the evolutionary transition to the ectomycorrhizal lifestyle are largely unknown. In this study, we sequenced the genome of Lyophyllum shimeji, an ectomycorrhizal fungus that is phylogenetically related to saprotrophic species and retains some saprotroph-like traits. We found that the genome of Ly. shimeji strain AT787 lacks both incremental increases in genome size and reduced numbers of PCWDEs. Our findings suggest that the previously reported common genomic traits of mycorrhizal fungi are not essential for the ectomycorrhizal lifestyle, but are a result of abolishing saprotrophic activity. Since Ly. shimeji is commercially consumed as an edible mushroom, the newly available genomic information may also impact research designed to enhance the cultivation of this mushroom.

The draft genome sequence of the Japanese rhinoceros beetle Trypoxylus dichotomus septentrionalis towards an understanding of horn formation.

The Japanese rhinoceros beetle Trypoxylus dichotomus is a giant beetle with distinctive exaggerated horns present on the head and prothoracic regions of the male. T. dichotomus has been used as a research model in various fields such as evolutionary developmental biology, ecology, ethology, biomimetics, and drug discovery. In this study, de novo assembly of 615 Mb, representing 80% of the genome estimated by flow cytometry, was obtained using the 10 × Chromium platform. The scaffold N50 length of the genome assembly was 8.02 Mb, with repetitive elements predicted to comprise 49.5% of the assembly. In total, 23,987 protein-coding genes were predicted in the genome. In addition, de novo assembly of the mitochondrial genome yielded a contig of 20,217 bp. We also analyzed the transcriptome by generating 16 RNA-seq libraries from a variety of tissues of both sexes and developmental stages, which allowed us to identify 13 co-expressed gene modules. We focused on the genes related to horn formation and obtained new insights into the evolution of the gene repertoire and sexual dimorphism as exemplified by the sex-specific splicing pattern of the doublesex gene. This genomic information will be an excellent resource for further functional and evolutionary analyses, including the evolutionary origin and genetic regulation of beetle horns and the molecular mechanisms underlying sexual dimorphism.

Antiemetic effects of baclofen in a shrew model of postoperative nausea and vomiting: Whole-transcriptome analysis in the nucleus of the solitary tract.

AIMS: The molecular genetic mechanisms underlying postoperative nausea and vomiting (PONV) in the brain have not been fully elucidated. This study aimed to determine the changes in whole transcriptome in the nucleus of the solitary tract (NTS) in an animal model of PONV, to screen a drug candidate and to elucidate the molecular genetic mechanisms of PONV development. METHODS: Twenty-one female musk shrews were assigned into three groups: the Surgery group (shrew PONV model, n = 9), the Sham group (n = 6), and the Naïve group (n = 6). In behavioral studies, the main outcome was the number of emetic episodes. In genetic experiments, changes in the transcriptome in the NTS were measured. In a separate study, 12 shrews were used to verify the candidate mechanism underlying PONV. RESULTS: A median of six emetic episodes occurred in both the Sham and Surgery groups. Whole-transcriptome analysis indicated the inhibition of the GABAB receptor-mediated signaling pathway in the PONV model. Baclofen (GABAB receptor agonist) administration eliminated emetic behaviors in the shrew PONV model. CONCLUSIONS: Our findings suggest that the GABAB receptor-mediated signaling pathway is involved in emesis and that baclofen may be a novel therapeutic or prophylactic agent for PONV.

Staging of regeneration process of an arm of the feather star Oxycomanthus japonicus focusing on the oral-aboral boundary.

Crinoids have strong regenerative capability and rapidly restore their lost body parts such as arms. We observed the regeneration process of arms of the feather star (stalkless crinoid), Oxycomanthus japonicus, and divided the process into 10 stages. We clarify the position at which the oral and aboral epidermis adhere in wound closure and track the oral-aboral boundary in the regenerate during the entire process of regeneration. We suggest that the concepts of distalization and intercalation, which are proposed to understand animal regeneration integrally, are also applicable to arm regeneration of the feather star. In addition, we clarify that pinnules, appendages extending from the sides of an arm, start to grow in the oral region of the regenerating arm even though a complete pinnule has an oral-aboral axis. The mode of morphogenesis of pinnules in arm regeneration suggests that the oral region functions as the primary patterning tissue for pinnules.

Potent anti-tumor effects of receptor-retargeted syncytial oncolytic herpes simplex virus.

Most oncolytic virotherapy has thus far employed viruses deficient in genes essential for replication in normal cells but not in cancer cells. Intra-tumoral injection of such viruses has resulted in clinically significant anti-tumor effects on the lesions in the vicinity of the injection sites but not on distant visceral metastases. To overcome this limitation, we have developed a receptor-retargeted oncolytic herpes simplex virus employing a single-chain antibody for targeting tumor-associated antigens (RR-oHSV) and its modified version with additional mutations conferring syncytium formation (RRsyn-oHSV). We previously showed that RRsyn-oHSV exhibits preserved antigen specificity and an ∼20-fold higher tumoricidal potency in vitro relative to RR-oHSV. Here, we investigated the in vivo anti-tumor effects of RRsyn-oHSV using human cancer xenografts in immunodeficient mice. With only a single intra-tumoral injection of RRsyn-oHSV at very low doses, all treated tumors regressed completely. Furthermore, intra-venous administration of RRsyn-oHSV resulted in robust anti-tumor effects even against large tumors. We found that these potent anti-tumor effects of RRsyn-oHSV may be associated with the formation of long-lasting tumor cell syncytia not containing non-cancerous cells that appear to trigger death of the syncytia. These results strongly suggest that cancer patients with distant metastases could be effectively treated with our RRsyn-oHSV.

Networking and Specificity-Changing DNA Methyltransferases in Helicobacter pylori.

Epigenetic DNA base methylation plays important roles in gene expression regulation. We here describe a gene expression regulation network consisting of many DNA methyltransferases each frequently changing its target sequence-specificity. Our object Helicobacter pylori, a bacterium responsible for most incidence of stomach cancer, carries a large and variable repertoire of sequence-specific DNA methyltransferases. By creating a dozen of single-gene knockout strains for the methyltransferases, we revealed that they form a network controlling methylome, transcriptome and adaptive phenotype sets. The methyltransferases interact with each other in a hierarchical way, sometimes regulated positively by one methyltransferase but negatively with another. Motility, oxidative stress tolerance and DNA damage repair are likewise regulated by multiple methyltransferases. Their regulation sometimes involves translation start and stop codons suggesting coupling of methylation, transcription and translation. The methyltransferases frequently change their sequence-specificity through gene conversion of their target recognition domain and switch their target sets to remodel the network. The emerging picture of a metamorphosing gene regulation network, or firework, consisting of epigenetic systems ever-changing their specificity in search for adaptation, provides a new paradigm in understanding global gene regulation and adaptive evolution.

Corrigendum: Networking and Specificity-Changing DNA Methyltransferases in Helicobacter pylori.

[This corrects the article DOI: 10.3389/fmicb.2020.01628.].

Ethylene signaling mediates host invasion by parasitic plants.

Parasitic plants form a specialized organ, a haustorium, to invade host tissues and acquire water and nutrients. To understand the molecular mechanism of haustorium development, we performed a forward genetics screening to isolate mutants exhibiting haustorial defects in the model parasitic plant Phtheirospermum japonicum. We isolated two mutants that show prolonged and sometimes aberrant meristematic activity in the haustorium apex, resulting in severe defects on host invasion. Whole-genome sequencing revealed that the two mutants respectively have point mutations in homologs of ETHYLENE RESPONSE 1 (ETR1) and ETHYLENE INSENSITIVE 2 (EIN2), signaling components in response to the gaseous phytohormone ethylene. Application of the ethylene signaling inhibitors also caused similar haustorial defects, indicating that ethylene signaling regulates cell proliferation and differentiation of parasite cells. Genetic disruption of host ethylene production also perturbs parasite invasion. We propose that parasitic plants use ethylene as a signal to invade host roots.

Genomes of the Venus Flytrap and Close Relatives Unveil the Roots of Plant Carnivory.

Most plants grow and develop by taking up nutrients from the soil while continuously under threat from foraging animals. Carnivorous plants have turned the tables by capturing and consuming nutrient-rich animal prey, enabling them to thrive in nutrient-poor soil. To better understand the evolution of botanical carnivory, we compared the draft genome of the Venus flytrap (Dionaea muscipula) with that of its aquatic sister, the waterwheel plant Aldrovanda vesiculosa, and the sundew Drosera spatulata. We identified an early whole-genome duplication in the family as source for carnivory-associated genes. Recruitment of genes to the trap from the root especially was a major mechanism in the evolution of carnivory, supported by family-specific duplications. Still, these genomes belong to the gene poorest land plants sequenced thus far, suggesting reduction of selective pressure on different processes, including non-carnivorous nutrient acquisition. Our results show how non-carnivorous plants evolved into the most skillful green hunters on the planet.

Genomic insights of body plan transitions from bilateral to pentameral symmetry in Echinoderms.

Echinoderms are an exceptional group of bilaterians that develop pentameral adult symmetry from a bilaterally symmetric larva. However, the genetic basis in evolution and development of this unique transformation remains to be clarified. Here we report newly sequenced genomes, developmental transcriptomes, and proteomes of diverse echinoderms including the green sea urchin (L. variegatus), a sea cucumber (A. japonicus), and with particular emphasis on a sister group of the earliest-diverged echinoderms, the feather star (A. japonica). We learned that the last common ancestor of echinoderms retained a well-organized Hox cluster reminiscent of the hemichordate, and had gene sets involved in endoskeleton development. Further, unlike in other animal groups, the most conserved developmental stages were not at the body plan establishing phase, and genes normally involved in bilaterality appear to function in pentameric axis development. These results enhance our understanding of the divergence of protostomes and deuterostomes almost 500 Mya.

Precursor ion scanning and sequencing of arginine-ADP-ribosylated peptide by mass spectrometry.

Arginine (Arg)-specific ADP-ribosylation is one of the posttranslational modifications of proteins and is thought to play an important role in reversibly regulating functions of the target proteins in eukaryotes. However, the physiological target protein has not been established. We examined the fragmentation pattern of both ADP-ribosyl-Arg (ADP-R-Arg) and Arg-ADP-ribosylated peptides by quadrupole tandem mass spectrometry and found a specific cleavage of ADP-R-Arg into N-(ADP-ribosyl)-carbodiimide (ADP-R-carbodiimide) and ornithine. Based on this specific fragmentation pattern, we successfully identified the modification site and sequence of Arg-ADP-ribosylated peptide using a two-step collision and showed that ADP-R-carbodiimide is an excellent marker ion for precursor ion scanning of Arg-ADP-ribosylated peptide. We propose that a combination of the precursor ion scanning with ADP-R-carbodiimide as a marker ion and two-step collision is useful in searching for physiological target proteins of Arg-ADP-ribosylation.

Indoleamine 2,3-dioxygenase as a new target for malignant glioma therapy. Laboratory investigation.

OBJECT: Indoleamine 2,3-dioxygenase (IDO), a kynurenine pathway (KP) enzyme catalyzing oxidation of the essential amino acid tryptophan (Trp), is thought to be involved in the immune resistance of malignant tumors through T-cell inactivation caused by Trp depletion and metabolite accumulation. Human malignant gliomas may use this strategy to escape immune attack. The object of this study was to investigate the possibility of IDO-dependent Trp depletion by malignant gliomas and the practicability of using an IDO inhibitor together with anticancer drugs to reserve Trp without decreasing the cytotoxicity of the drugs. METHODS: The authors studied expression of IDO and other KP enzymes and the effects of an IDO inhibitor, 1-methyl L-tryptophan (1MT), on Trp metabolism and cytotoxicity of anticancer drugs, together with direct measurement of KP metabolites, in cultured human malignant glioma cells. RESULTS: Upon interferon-gamma (IFN-gamma) stimulation, the glioma cells greatly increased their IDO mRNA expression concomitant with depletion of Trp. The IDO inhibitor 1MT successfully prevented Trp consumption by the stimulated glioma cells. Combining 1MT with anticancer drugs (temozolomide, bischloroethylnitrosourea [BCNU], etoposide and cisplatin) did not interfere with the drugs' suppression of growth of LN229 glioma cells but rather increased their inhibitory effects on IDO activity. CONCLUSIONS: These findings suggest that the robust IDO expression with rapid consumption of Trp in human glioma cells induced by IFN-gamma could lead to immune resistance in glioma cells. Indoleamine 2,3-dioxygenase inhibitors that prevent Trp depletion could be used with anticancer drugs to improve therapeutic effects.

A draft genome assembly of the solar-powered sea slug Elysia chlorotica.

Elysia chlorotica, a sacoglossan sea slug found off the East Coast of the United States, is well-known for its ability to sequester chloroplasts from its algal prey and survive by photosynthesis for up to 12 months in the absence of food supply. Here we present a draft genome assembly of E. chlorotica that was generated using a hybrid assembly strategy with Illumina short reads and PacBio long reads. The genome assembly comprised 9,989 scaffolds, with a total length of 557 Mb and a scaffold N50 of 442 kb. BUSCO assessment indicated that 93.3% of the expected metazoan genes were completely present in the genome assembly. Annotation of the E. chlorotica genome assembly identified 176 Mb (32.6%) of repetitive sequences and a total of 24,980 protein-coding genes. We anticipate that the annotated draft genome assembly of the E. chlorotica sea slug will promote the investigation of sacoglossan genetics, evolution, and particularly, the genetic signatures accounting for the long-term functioning of algal chloroplasts in an animal.