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The dead end gene has been identified as a essential factor for Primordial germ cells (PGCs) migration and survival in many species, but its role in Monopterus albus is unclear. In order to clarify the function of dead end gene in M.albus PGCs migration and survival, we first characterized the expression profile of M.albus dead end (Madnd) in developing embryos and various tissues. qRT-PCR revealed that Madnd transcripts were exclusively detected in gonad, including ovary, testis and ovotestis.Embryos injected with a Madnd morpholino (Madnd-MO) exhibited down-regulation of the vasa gene. Furthermore, the GFP signal show the PGCs migration in control group were injected with GFP-nanos3 3′-UTR mRNA for visualization, as described in a previous study, yet it was disappeared after embryos injected with Madnd-MO.Finally, we characterized the genomics sequence of the Madnd gene and designed five gRNAs for genome editing. Three gRNAs were selected for microinjection according to the results of in vitro tests. gRNAd1 was used for microinjection with the Cas9 protein and was confirmed to be effective. Our analysis in this study suggested that Madnd play a key role in PGCs migration and survival in M. albus. These data provide the basis for the production of fast-growing and reproductively M.albus sterile.

Chinese rice-field eels rhabdovirus (CrERV), belonging to the genus Perhabdovirus in the family Rhabdoviridae, is the causative agent of the haemorrhagic disease of Chinese rice-field eels, Monopterus albus. The present study aims to establish a cell line derived from the kidney of Chinese rice-field eel (CrEK) for the further study of the pathogenic virus. CrEK cells were epithelioid-like and grew well in M199 medium supplemented with 10% foetal bovine serum at 28°C, and the cell line has been subcultured for more than 80 times. Karyotyping analysis of CrEK cells at 25th passage indicated a modal chromosome number of 24. Significant cytopathic effect (CPE) was observed in CrEK cells after infection with CrERV, and the virus titre reached 107.8 ± 0.45 TCID50 /mL. The transmission electron microscopy revealed that there were a large number of virus particles in the cytoplasm of cells. The virus infection in cells was also assayed by using indirect immunofluorescence assay (IFA), fluorescence in situ hybridization (FISH), reverse transcription PCR (RT-PCR) and quantitative real-time reverse transcription-PCR (qRT-PCR). In experimental infection, CrERV cultured by cells could cause over 90% mortality in fish. CrEK represents the first kidney cell line originated from Chinese rice-field eels and be a potential material for investigating the mechanism of virus infection in this fish and the control methods for the disease.

Dyslipidemia is one of the most important cardiovascular disease (CVD) risk factors. Polyunsaturated fatty acids (FAs), and especially omega-3 FAs, could significantly contribute to the management of dyslipidemia and the prevention of CVD. The anti-hyperlipidemic effect of selected fish oils (eel, sardine, trout, cod liver) was comparatively evaluated in a high fat diet (HFD)-fed mouse model. At the end of 30 days on the HFD, all animals were hyperlipidemic and were switched to a diet consisting of 90% standard rodent chow plus 10% of oil from eel, sardine, cod liver, or trout. At the end of 60 days on these diets, blood glucose, total blood cholesterol, triglycerides (TGs), and high density lipoprotein (HDL) were quantitated. All diets, except sardine and standard rodent chow, showed statistically significant decreases in blood glucose from day 30 to 90. Total blood cholesterol decreased in all diets except the HFD group, which was continued on this diet until the end of the study. Eel and cod liver oil diets showed significant decreases in TGs. All dietary groups showed a decrease in HDL, but only the trout and standard chow groups exhibited statistically significant decreases. The fish oils tested here for effects on hyperlipidemia vary in per cent of omega-3 FAs and omega-6/-3 FA ratios as determined by gas chromatography Overall, smoked eel was the best source of omega-3 FA, with a balance of omega-6 FA, that ameliorated HFD-induced mixed hyperlipidemia.

Eel larvae apparently feed on marine snow, but many aspects of their feeding ecology remain unknown. The eukaryotic 18S rRNA gene sequence compositions in the gut contents of four taxa of anguilliform eel larvae were compared with the sequence compositions of vertically sampled seawater particulate organic matter (POM) in the oligotrophic western North Pacific Ocean. Both gut contents and POM were mainly composed of dinoflagellates as well as other phytoplankton (cryptophytes and diatoms) and zooplankton (ciliophoran and copepod) sequences. Gut contents also contained cryptophyte and ciliophoran genera and a few other taxa. Dinoflagellates (family Gymnodiniaceae) may be an important food source and these phytoplankton were predominant in gut contents and POM as evidenced by DNA analysis and phytoplankton cell counting. The compositions of the gut contents were not specific to the species of eel larvae or the different sampling areas, and they were most similar to POM at the chlorophyll maximum in the upper part of the thermocline (mean depth: 112 m). Our results are consistent with eel larvae feeding on marine snow at a low trophic level, and feeding may frequently occur in the chlorophyll maximum in the western North Pacific.

The structure and gene sequence of the fish mitochondrial genome are generally considered to be conservative. However, two types of gene arrangements are found in the mitochondrial genome of Anguilliformes. In this paper, we report a complete mitogenome of Muraenesox cinereus (Anguilliformes: Muraenesocidae) with rearrangement phenomenon. The total length of the M. cinereus mitogenome was 17,673 bp, and it contained 13 protein-coding genes, two ribosomal RNAs, 22 transfer RNA genes, and two identical control regions (CRs). The mitochondrial genome of M. cinereus was obviously rearranged compared with the mitochondria of typical vertebrates. The genes ND6 and the conjoint trnE were translocated to the location between trnT and trnP, and one of the duplicated CR was translocated to the upstream of the ND6. The tandem duplication and random loss is most suitable for explaining this mitochondrial gene rearrangement. The Anguilliformes phylogenetic tree constructed based on the whole mitochondrial genome well supports Congridae non-monophyly. These results provide a basis for the future Anguilliformes mitochondrial gene arrangement characteristics and further phylogenetic research.

The synthesis and release of LH and FSH in the pituitary of vertebrates are differentially regulated during gonadal development and maturation. However, the underlying neuroendocrine mechanisms remain to be fully elucidated. The present study examined the possible involvement of isotocin (Ist), an oxytocin-like neuropeptide, in the regulation of Lh and Fsh in a teleost, the ricefield eel Monopterus albus. The immunoreactive isotocin receptor 2 (Istr2) was shown to be localized to Lh but not Fsh cells. In contrast, immunoreactive isotocin receptor 1 (Istr1) was not observed in either Lh or Fsh cells in the pituitary. Interestingly, Lh cells in female ricefield eels expressed Istr2 and secreted Lh in response to Ist challenge stage-dependently and in correlation with ovarian vitellogenesis. Moreover, Ist decreased Lh contents in the pituitary of female fish, indicating its stimulatory roles on Lh release in vivo. The induction of Lh release by Ist in dispersed pituitary cells was blocked by a PLC or IP3R inhibitor but not by a PKA or PKC inhibitor, indicating the involvement of the IP3/Ca2+ pathway. Collectively, the above results indicate that isotocin may bind to Istr2 to stimulate Lh release via the IP3/Ca2+ pathway, and play important roles in the ovarian maturation in ricefield eels. Furthermore, the present study suggests a novel neuroendocrine mechanism underlying the differential regulation of Lh and Fsh in vertebrates.

Previously, we demonstrated that maternal exposure to high, intermediate, or lowly contaminated European eels with a mixture of chemicals, during pregnancy and lactation, resulted in adult despair-like behavior, selectively in male offspring mice. Here, we investigate if depression-like behavior in offspring males was transient or permanent by monitoring immobility behavior, a measure of behavioral despair, at three distinct stages of life, including young adult (post-natal day (PND) 55), mature adult (PND 200) and middle (PNDs 335-336) age, in the forced swimming (FST) and the tail suspension (TST) tests. Oxidative stress markers including malondialdehyde (MDA) levels and superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities were evaluated in the hippocampus, prefrontal cortex, and cerebellum of middle-aged animals. Findings showed a significant enhancement of immobility behavior in the TST performed at young adult age (all p 0.05) in the FST carried out at mature adult age (all p 0.001) and in both behavioral tests realized at middle age (all p 0.05, except one p = 0.06) in mice perinatally exposed to eels compared with non-exposed controls. Antioxidant-related enzyme activities, including SOD and CAT, were only elevated in the hippocampus of middle-aged males perinatally exposed to the two more polluted eels (all p 0.05). Further, lipid peroxidation, assessed by MDA levels, was not found to be differentially regulated in the selected areas of middle-aged brains of exposed mice (all p 0.05). Collectively, this suggested limited oxidative metabolism disturbances in middle-aged brains exposed to eels. In summary, our results highlighted that offspring males perinatally exposed to naturally contaminated reared and river eels with persistent organic pollutants (POPs) and heavy metals displayed chronic depression-like phenotype. As extrapolation of data to humans should be done with precaution, retrospective and prospective epidemiological studies are needed to clarify this potential relationship, stressed in our animal model, between maternal polluted fish consumption and chronically low mood in offspring.

Smad2, a receptor-activated Smad, plays a critical role in regulating gametogenesis. In this study, a smad2 homologue was identified and sequenced from ricefield eel ovary cDNA, and its mRNA and protein expression levels were analysed during oocyte development. The cDNA sequence of ricefield eel smad2 consisted of 1863 bp encoding a 467-amino acid protein that had high sequence homology with Smad proteins in other teleosts, especially in Poeciliopsis prolifica. The results of real-time quantitative PCR (RT-qPCR) analysis revealed that smad2 is expressed in the ovary during gonad development, increased continuously until the early vitellogenic stage in the ovaries, and then decreased with ovary maturation. Smad2 protein immunoreactivity was localized in the cytoplasm of follicular cells, oogonia, and primary growth stage oocytes. In vitro experiments revealed that follicle-stimulating hormone (FSH) and human chorionic gonadotropin (hCG) promoted smad2 expression in ovary tissue in a time- and dose-dependent manner, respectively. In summary, Smad2 plays a potentially vital role in ricefield eel ovary development.

Soot is characterized by a multiscale structural organization, the only diagnostic tool that can give access to it is the transmission electron microscope (TEM). However, as it is a diffraction-based technique, TEM images only conjugate aromatic systems and, thus, it is particularly useful to combine it with electron energy-loss spectroscopy (EELS), which is able to provide quantitative information about the relative abundance of sp3 and sp2 hybridized carbon. In this paper, a method for the EELS spectrum analysis of carbonaceous materials, recently developed for electron-irradiated graphite and glassy carbon composition analysis, has been applied for the first time on soot samples, in order to test its performance in soot nanostructure study in combination with TEM and high-resolution TEM (HRTEM). Soot samples analyzed were collected in the soot inception region of premixed flames of different hydrocarbon fuels. EELS, in agreement with TEM and HRTEM, showed a quite disordered and heterogeneous structure for young soot, with a relatively low sp2 content and slight presence of fullerene-like structures, more evident in the case of methane soot hinting to the effect of more saturated aliphatic fuels on soot characteristics at soot inception.

Taiwan is one of the richest in the world in terms of eel fauna. In this study, we examined the osteological and morphological characteristics of eels under order Anguilliformes. Furthermore, we focused on the neurocranium of total of 30 Anguilliformes fishes under family Congridae (10), Muraenesocidae (1), Muraenidae (7), Nemichthyidae (1), Nettastomatidae (2), Ophichthidae (5), Synaphobranchidae (4), which are caught in Taiwanese waters. This paper shows the results of a comparative study on osteological characters of the neurocranium including the ratio of seven length characters using its NCL (neurocranium length), NCW (neurocranium width), OBL (orbit length), MFW (maximum frontal width), NCDB (neurocranium depth at basisphenoid), PEVW (premaxilla-ethmovomer width) and mPOBL (mid pre-orbital length), and 20 morphological diagnostic characters for 30 eel species. Results shows that species under family Nemichthyidae and Nettastomatidae have the highest values on the ratio of NCL/MFW, NCL/NCDB, and NCW/mPOBD. In morphological characters, it shows that species of the same family mostly share similar formation of the PEV plate and frontal structure. The usage of the length measurements and morphological diagnostic characters of neurocranium allowed for a more in depth understanding of how similar or different these eels can be. The neurocranial description and morphological characters may prove valuable for identification purposes and might be necessary tool for further studies on the status of order Anguilliformes.

To discover multifunctional agents for the treatment of Alzheimer's disease (AD), a series of chalcone-O-carbamate derivatives was designed and synthesized based on the multitarget-directed ligands strategy. The in vitro biological activities were evaluated including AChE/BChE inhibition, MAO-A/MAO-B inhibition, antioxidant activities, Aβ1-42 aggregation inhibition, metal-chelating properties and neuroprotective effects against H2O2-induced PC12 cell injury. The results showed compounds 5b and 5h indicated highly selective BChE inhibitory activity with IC50 values of 3.1 μM and 1.2 μM, respectively and showed highly selective MAO-B inhibitory potency with IC50 values of 1.3 μM and 3.7 μM, respectively. In addition, compounds 5b and 5h could inhibit self-induced Aβ1-42 aggregation with 63.9% and 53.1% inhibition percent rate, respectively. Particularly, compound 5b was a potent antioxidant agent and neuroprotectant, as well as a selective metal chelator by chelating Cu2+ and Al3+. Moreover, compound 5b could inhibit and disaggregate Cu2+-induced Aβ1-42 aggregation, which was further supported by the TEM images. Furthermore, compounds 5b and 5h could cross the blood-brain barrier (BBB) in vitro and conformed to the Lipinski's rule of five. Finally, the in vivo assay exhibited that compound 5b could improve scopolamine-induced cognitive impairment. Taken together, these results revealed that compound 5b might be a potential multifunctional agent for the treatment of AD, and deserved to do further structure optimization.

A series of fifteen acetylcholinesterase inhibitors were designed and synthesised based upon the previously identified lead compound 5,6-dimethoxy-1-oxo-2,3-dihydro-1H-inden-2-yl 1-benzylpiperidine-4-carboxylate (5) which showed good inhibitory activity (IC50 0.03 ± 0.07 μM) against acetylcholinesterase. A series of compounds were prepared wherein the ester linker in the original lead compound was exchanged for a more metabolically stable amide linker and the indanone moiety was exchanged for a range of aryl and aromatic heterocycles. The two most active analogues 1-benzyl-N-(5,6-dimethoxy-8H-indeno[1,2-d]thiazol-2-yl)piperidine-4-carboxamide (28) and 1-benzyl-N-(1-methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl) piperidine-4-carboxamide (20) afforded in vitro IC50 values of 0.41 ± 1.25 and 5.94 ± 1.08 μM, respectively. In silico screening predicts that 20 will be a blood brain-barrier permeant, and molecular dynamic simulations are indicative of a close correlation between the binding of 20 and the Food and Drug Administration-approved cholinesterase inhibitor donepezil (1).

A series of chalcone Mannich base derivatives were designed, synthesized and evaluated as multifunctional agents for the treatment of Alzheimer’s disease based on the multi-target directed ligands design strategy. In vitro assays demonstrated that most of the derivatives exerted potent selective inhibitory potency on AChE with good multifunctional properties. Among them, representative compound 7c exhibited moderate inhibitory potency for EeAChE (IC50 = 0.44 μM) and MAO-B inhibition (IC50 = 1.21 μM), good inhibitory effect on self-induced Aβ1−42 aggregation (55.0%, at 25 μM), biometal chelating property, moderate antioxidant activity with a value 1.93-fold of Trolox. Moreover, both kinetic analysis of AChE inhibition and molecular modeling study revealed that 7c showed a mixed-type inhibition, binding simultaneously to CAS and PAS of AChE. In addition, 7c also displayed high BBB permeability. These properties indicated 7c may be a promising multifunctional agent for the treatment of AD.

A cladistic analysis of the eel families Derichthyidae and Colocongridae is herein proposed for the first time on the basis of morphological data. We discovered dozens of new phylogenetic characters derived from a detailed analysis of the pectoral skeleton, an anatomical system neglected by most previous studies. Our maximum parsimony analysis indicates that Colocongridae sensu lato is paraphyletic, with its two constituent genera Coloconger and Congriscus appearing as successive sister groups of derichthyids. Monophyly of the family Derichthyidae, which has been questioned by some studies, is herein strongly supported by 10 unambiguous synapomorphies. We also stress the importance of the appendicular skeleton as a useful source of phylogenetic information for the resolution of systematic problems within Anguilliformes.

[Soot nanostructure was analyzed in fuel-rich premixed laminar C2H4/O2 flames at a constant equivalence ratio of 2.4 and different maximum temperatures, namely, 1620 and 1690 K, obtained using different cold gas velocities. Flame structure and bulk properties of soot as H/C ratio, reactivity and absorption coefficient were investigated, along with morphological, nanostructural, and chemical features (using TEM, HRTEM, EELS). It was found that dehydrogenation and aromatization of soot occurring along the flames are favored at the beginning of the flame in higher flame temperature conditions. Nevertheless, it was noticeable that soot reaches rather similar final nanostructure and bulk properties, independently on the temperature, at least in the 1620-1690 K range investigated.object Object]

Anguillid herpesvirus 1 (AngHV) is one of the vital pathogenic agents found in the wild and cultured eel populations, which has brought significant losses to eel culture industry in China. In this study, AngHV ORF95 was characterized. Bioinformatics analysis showed that ORF95 putatively encodes a structural protein that is homologous to hemagglutinin-esterase (HE) protein of infectious salmon anemia virus (ISAV). Temporal transcription and expression analysis indicated that ORF95 is a viral late gene. Subcellular localization analysis revealed that ORF95 was predominantly localized in the cytoplasm. Further, western blot analysis indicated that ORF95 is a structural protein of virion envelope. These results provide a novel basis to make further efforts to clarify the function of ORF95 in the process of AngHV infection and the possibility to use ORF95 as antigen to develop AngHV subunit vaccine.

Age and growth of early-life-stage Atlantic tarpon Megalops atlanticus collected from Mississippi coastal waters in the northcentral Gulf of Mexico (GOM) are described using otolith microstructure analysis. Tarpon leptocephali (n = 95, 16.0-27.8 mm standard length, LS ) collected from June throughOctober 2013-2018, ranged in age from 22 to 43 days (mean = 30.9 ± 0.5 days). Leptocephalus somatic growth rates ranged 0.46-1.24 mm day-1 (mean = 0.76 ± 0.02 mm day-1 ), and leptocephalus otolith growth rates ranged 1.78-3.97 μm day-1 (mean = 2.58 ± 0.04 μm day-1 ). Growth rates were inversely correlated to leptocephalus age, indicating the shrinkage phase associated with leptocephalus metamorphosis. Juvenile tarpon (n = 358, 50-359 mm fork length, LF ) were collected from August through December 2007-2018. Juveniles exhibited a positive allometric relationship (adjusted R2 = 0.99, P

Although 11-ketotestosterone (11KT) and testosterone (T) are major androgens in both teleosts and humans, their 5α-reduced derivatives produced by steroid 5α-reductase (SRD5A/srd5a), i.e., 11-ketodihydrotestosterone (11KDHT) and 5α-dihydrotestosterone (DHT), remains poorly characterized, especially in teleosts. In this study, we compared the presence and production of DHT and 11KDHT in Japanese eels and humans. Plasma 11KT concentrations were similar in both male and female eels, whereas T levels were much higher in females. In accordance with the levels of their precursors, 11KDHT levels did not show sexual dimorphism, whereas DHT levels were much higher in females. It is noteworthy that plasma DHT levels in female eels were higher than those in men. In addition, plasma 11KDHT was undetectable in both sexes in humans, despite the presence of 11KT. Three srd5a genes (srd5a1, srd5a2a and srd5a2b) were cloned from eel gonads. All three srd5a genes were expressed in the ovary, whereas only both srd5a2 genes were expressed in the testis. Human SRD5A1 was expressed in testis, ovary and adrenal, whereas SRD5A2 was expressed only in testis. Human SRD5A1, SRD5A2 and both eel srd5a2 isoforms catalyzed the conversion of T and 11KT into DHT and 11KDHT, respectively, whereas only eel srd5a1 converted T into DHT. DHT and 11KDHT activated eel androgen receptor (ar)α-mediated transactivation as similar fashion to T and 11KT. In contrast, human AR and eel arβ were activated by DHT and11KDHT more strongly than T and 11KT. These results indicate that in teleosts, DHT and 11KDHT may be important 5α-reduced androgens produced in the gonads. In contrast, DHT is the only major 5α-reduced androgens in healthy humans.

Environmental DNA (eDNA) analysis with species-specific primer/probe sets is promising as a tool to quantify fish abundance and distribution. Nevertheless, several factors could reduce the accuracy of this method. Here, we aimed to analyze whether intraspecific variability and diel activity rhythm affect eDNA detection in Japanese eels (Anguilla japonica). For this purpose, we performed tank experiments focusing on two points. First, we assessed the effects of base pair sequences with probe region polymorphism on eDNA detection. Next, we evaluated the influences of diel rhythm, activity, and individual differences in eDNA release rate on eDNA concentration. We examined the base pair sequences of the probe regions of 20 individuals and found genetic mismatches in two of them. The eDNA concentration was estimated to be much lower in these variants than it was in the other individuals. We conducted a rearing experiment on four non-variant individuals to explore the influences of diel activity and inter-individual differences in eDNA detection. Nocturnal eel activity was reflected in the eDNA detection but the inter-individual differences remained large. The observed weak positive correlations between eDNA concentration and activity suggest that eDNA emission is highly dependent on basal metabolism. The present study suggests that consideration of polymorphic sites at the probe region and diel activity rhythms should improve the accuracy and precision of abundance estimation through eDNA. Such fine-tuning is applicable not only for eels but also for other fishes to be targeted by eDNA technology.

A new species of the genus Cirrhimuraena (Anguilliformes: Ophichthidae), Cirrhimuraena indica sp. nov., is described based on eight specimens collected from the Paradip (Odisha) and Petuaghat harbours (West Bengal) along the Bay of Bengal. The species is distinct in having the upper jaw fringed with 16-17 cirri before posterior nostril and 4-5 in between the anterior and posterior nostrils on the side; dorsal fin originates above the level of gill opening, predorsal length is 9.3-10.9 in total length; the head is relatively large, the length is 9.3-9.8 in total length; no infraorbital pores are observed between the nostrils; teeth are numerous, small, conical and in bands on each jaw; pores are present before the gill opening 10-11 and before anus 47-48; pectoral-fin length is 2.4-2.8 in head length; predorsal vertebrae are 8-10, pre-anal vertebrae 43-47 and total vertebrae 164-169. In the maximum likelihood tree analysis for COI gene, the new species belongs to the same clade as the other congener of Cirrhimuraena chinensis and is separated from the species morphologically and genetically.

Bacteriophages (or phages) play major roles in the evolution of bacterial pathogens via horizontal gene transfer. Multiple phages are often integrated in a host chromosome as prophages, not only carrying various novel virulence-related genetic determinants into host bacteria but also providing various possibilities for prophage-prophage interactions in bacterial cells. In particular, Escherichia coli strains such as Shiga toxin (Stx)-producing E. coli (STEC) and enteropathogenic E. coli (EPEC) strains have acquired more than 10 prophages (up to 21 prophages), many of which encode type III secretion system (T3SS) effector gene clusters. In these strains, some prophages are present at a single locus in tandem, which is usually interpreted as the integration of phages that use the same attachment (att) sequence. Here, we present phages integrating into T3SS effector gene cluster-associated loci in prophages, which are widely distributed in STEC and EPEC. Some of the phages integrated into prophages are Stx-encoding phages (Stx phages) and have induced the duplication of Stx phages in a single cell. The identified attB sequences in prophage genomes are apparently derived from host chromosomes. In addition, two or three different attB sequences are present in some prophages, which results in the generation of prophage clusters in various complex configurations. These phages integrating into prophages represent a medically and biologically important type of inter-phage interaction that promotes the accumulation of T3SS effector genes in STEC and EPEC, the duplication of Stx phages in STEC, and the conversion of EPEC to STEC and that may be distributed in other types of E. coli strains as well as other prophage-rich bacterial species., Author summary Multiple prophages are often integrated in a bacterial host chromosome and some are present at a single locus in tandem. The most striking examples are Shiga toxin (Stx)-producing and enteropathogenic Escherichia coli (STEC and EPEC) strains, which usually contain more than 10 prophages (up to 21). Many of them encode a cluster of type III secretion system (T3SS) effector genes, contributing the acquisition of a large number of effectors (>30) by STEC and EPEC. Here, we describe prophages integrating into T3SS effector gene cluster-associated loci in prophages, which are widely distributed in STEC and EPEC. Two or three different attachment sequences derived from host chromosomes are present in some prophages, generating prophage clusters in various complex configurations. Of note, some of such phages integrating into prophages are Stx-encoding phages (Stx phages) and have induced the duplication of Stx phages. Thus, “prophage-in-prophage” represents an important inter-phage interaction as they can promote not only the accumulation of T3SS effectors in STEC and EPEC but also the duplication of Stx phages and the conversion of EPEC to STEC.

G protein-coupled estrogen receptor 1 (Gper1) mediates many rapid, non-genomic estrogenic effects in vertebrates, and plays an important reproductive role in the maintenance of oocyte meiotic arrest in teleost fishes. In the present study, two genes for Gper1, namely gper1a and gper1b, were identified in the genome of a teleost fish, the ricefield eel (Monopterus albus) through Blast and syntenic analysis. Although genes neighboring gper1b are of high synteny, ricefield eel Gper1b shares very low (around 15) percent identities with Gper1 homologues of other vertebrates. In transiently transfected HEK293T cells, both ricefield eel Gper1a and Gper1b responded to estradiol (E2) and estradiol-BSA (E2-BSA) challenges by activating pCRE but not pSRE luciferase reporters, which were abolished by G-15 and NF-449. The production of cAMP was also increased in HEK293T cells transfected with Gper1a or Gper1b expression construct after E2-BSA challenge, which was also abolished by G-15. Surprisingly, both Gper1a and Gper1b showed ligand-independent effects on pCRE luciferase reporters at higher transfected doses (10 ng). RT-PCR analysis showed that the transcript of gper1a is broadly expressed in tissues of both female and male fish while the expression of gper1b in tissues demonstrates obvious sexual dimorphism, with transcripts detected in all tissues examined in female whereas they were barely detectable in some peripheral tissues of male including the testis. In the ovary, the expression of both gper1a and gper1b was detected in the oocyte but not the follicular layer, with the mRNA levels increased during vitellogenesis, peaked at the late vitellogenic stage, and decreased precipitously at the full-grown and germinal vesicle breakdown (GVBD) stages. Moreover, E2 and E2-BSA induced cAMP production in the in vitro incubated follicles at mid-vitellogenic stage but not the GVBD stage, and the induction could be completely abolished by G-15, a Gper1 inhibitor. Taken together, these results suggest that both Gper1a and Gper1b may play important roles in the development and maturation of ovarian follicles in ricefield eels, possibly through inhibition of oocyte meiotic resumption.

A new species of snake eel Xyrias anjaalai sp. nov. (Anguilliformes: Ophichthidae) is described from morphological analysis of 12 specimens and molecular analysis of four specimens, caught off Kollam, Kerala, southwestern India, by deep-sea trawling. X. anjaalai is distinguished from its congeners by having a large eye diameter, a short snout, a different dentition pattern as in the 3rd row of maxillary teeth beginning at the level of the 4th vomerine tooth between the two existing rows in the inner series of maxillary teeth, an irregular tooth patch for approximately 1/10th of the lateral side of the dental arch in the distal portion and a vertebral count of predorsal vertebrae 18–21, preanal vertebrae 73–76 and total vertebrae 147–149. Phylogenetic relationships of X. anjaalai with other species in Ophichthidae were examined using partial nucleotide sequences of the COI gene (617 bp). The genetic analyses suggest that the new species is closest to X. revulsus followed by Apterichtus klazingai with Kimura 2 parameter (K2P) values of 0.6 and 2.8% respectively. In the phylogenetic reconstruction, sequences of X. anjaalai formed a distinct clade demonstrating their uniqueness as a separate species.

Taiwan is one of the richest in the world in terms of eel fauna. In this study, we examined the osteological and morphological characteristics of eels in the family Muraenidae. Furthermore, we focused on the neurocranium of 34 muraenid species in the genera Echidna (2), Enchelycore (3), Gymnomuraena (1), Gymnothorax (25), Scuticaria (1), Strophidon (1), and Uropterygius (1), which are caught in Taiwanese waters. This paper shows the results of a comparative study on osteological characters of the neurocranium including the ratio of nine length characters and 20 diagnostic characters for 34 eel species in the family Muraenidae. The subfamily Uropterygiinae is distinguished from the subfamily Muraeninae in having the lowest value on the depth of mid pre-orbit due to the termination of the ethmoidal crest toward premaxilla. Moreover, aside from Gymnomuraena zebra, the species of subfamily Uropterygiinae have the lowest orbit length. These results in neurocranial comparative morphology between the species are consistent with their previous classification based on molecular results. These morphological and osteological characters may be valuable for taxonomic purposes and might be used as the basis for further studies on the status of genera in Muraenidae.

Siva1, which induces extensive apoptosis, has been well characterized. To elucidate the molecular function of Siva1 in ricefield eel, molecular characterization and phylogenetic analysis were performed, and the mRNA expression in the ovary at different developmental stages and ovary tissues exposed to H2O2 and Z-VAD-FMK in vitro were also evaluated. The results indicated that ricefield eel Siva1 was highly conserved and contains three conserved motifs, despite 83 amino acid differences upstream of the initiation codon. Phylogenetic analysis demonstrated that ricefield eel Siva1 clusters together with the Siva1 protein of the other fish, with high sequence homology with that of Lates calcarifer. Quantitative real-time polymerase chain reaction analysis showed high siva1 expression levels in the ovary and low expression levels in the liver. The higher mRNA levels of siva1 were detected in the IE and IM, and the lower siva1 mRNA levels were found in the OM, IL, and TE during gonadal development. Additionally, siva1 expression levels in the ovarian tissues were significantly increased at 1 h post incubation (hpi) with H2O2 and then significantly decreased at 2 hpi; however, siva1 expression was upregulated significantly at 4 and 8 hpi, similar to the patterns observed with caspase3, which was used as a molecular marker of apoptosis. Moreover, the siva1 mRNAs were elevated significantly than that in control groups at 1 hpi, but the expression of siva1 was down-regulated dramatically at 2, 4, and 8 hpi, which were similar with that of caspase3 expression profiles after Z-VAD-FMK incubation. What’s more, Pearson’s correlation coefficients showed strongly positive relationships between siva1 and caspase3. These findings suggest that Siva1 plays an important apoptosis role in gonadal development of ricefield eel.

ObjectivesAging causes stiffness and decreased function of the renal artery (RA). Histological study with light microscopy can reveal microscopic structural remodeling but no functional changes. The present study aimed to clarify the association between structural and functional aging of the RA through the use of scanning acoustic microscopy.MethodsFormalin-fixed, paraffin-embedded cross-sections of renal arteries from 64 autopsy cases were examined. Speed-of-sound (SOS) values of three layers, which correspond to the stiffness, were compared among different age groups. SOS of the tunica media was examined in terms of blood pressure (BP) and SOS of the ascending aorta. Vulnerability to proteases was assessed by SOS reduction after collagenase treatment.ResultsThe tunica intima presented inward hypertrophy with luminal narrowing, and the tunica media showed outward hypertrophic remodeling with aging. SOS of the tunica media and internal and external elastic laminae showed a reverse correlation with age. SOS of the tunica media was negatively correlated with BP and strongly associated with that of the aorta. The tunica media of young RAs were more sensitive to collagenase compared with the old ones.ConclusionsScanning acoustic microscopy is useful for observing the aging process of the RA. This technique simultaneously shows structural and mechanical information from each portion of the RA. In the process of aging, the RA loses contractile function and elasticity as a result of protease digestion. The tunica media and the internal and external elastic laminae exhibit reduced stiffness, but the tunica intima stiffens with atherosclerosis. As a consequence, the RA’s outer shape changes from round to oval with inward and outward hypertrophy. This indicates that the inner resistant intima supports the mechanical weakness of the tunica media to compensate for an increase in BP with aging.

Alzheimer&rsquo, s disease (AD) is characterised by the apoptosis of cholinergic neurons and the consequent attenuation of acetylcholine mediated neurotransmission, resulting in neurodegeneration. Acetyl-cholinesterase (AChE) and butyryl-cholinesterase (BuChE) are attractive therapeutic targets in the treatment of AD since inhibition of these enzymes can be used to restore synaptic concentrations of acetylcholine. Whilst inhibitors for these enzymes such as galantamine and rivastigmine have been approved for use, none are able to halt the progression of AD and are responsible for the production of troublesome side-effects. Efficacious cholinesterase inhibitors have been isolated from natural plant-based compounds with many demonstrating additional benefits beyond cholinesterase inhibition, such as antioxidation and anti-inflammation, which are key parts of AD pathology. In this study, five natural flavan-3-ol (catechin) compounds: ((-)-epicatechin (EC), catechin, (-)-epicatechin-3-gallate (ECG),) (-)-epigallocatechin (EGC), (-)-epigallocatechin-3-gallate (EGCG), isolated from green tea, were screened for their cholinesterase inhibitory activity using the Ellman assay. The kinetics of inhibition was determined using reciprocal Lineweaver-Burk plots. EGCG was the only compound found to produce statistically significant, competitive inhibition, of both AChE (p &lt, 0.01) and BuChE (p &lt, 0.01) with IC50 values of 0.0148 &micro, mol/mL and 0.0251 &micro, mol/mL respectively. These results, combined with previously identified antioxidative and anti-inflammatory properties, highlight the potential use of EGCG in the treatment of AD, provided it can be delivered to cholinergic neurons in therapeutic concentrations. Further testing of EGCG in vivo is recommended to fully characterise the pharmacokinetic properties, optimal method of administration and efficacy of this novel plant-based compound.

A new species of the synaphobranchid genus Atractodenchelys is described based on 31 specimens collected off Quy Nhon and Nha Trang, southern Vietnam. The new species can be distinguished from the only two congeners in the genus by having much fewer total vertebrae (155‒158, vs. 168‒172 in A. phrix and 186‒199 in A. robinsorum), a relatively long head (head length 10.1‒12.3% TL), a relatively short snout (30.0‒35.8% HL), head longer than trunk length (vs. about equal in length in both species); and 5‒6 compound teeth on vomer (vs. 7‒8 in A. robinsorum).

International audience; Since its discovery in birds, gonadotropin-inhibitory hormone (GnIH) has triggered investigation in the other groups of vertebrates. In the present study, we have identified a single gnih gene in the European eel (Anguilla anguilla), a representative species of a basal group of teleosts (Elopomorphs). We have also retrieved a single gnih gene in Osteoglossomorphs, as well as in more recently emerged teleosts, Clupeocephala. Phylogeny and synteny analyses allowed us to infer that one of the two gnih paralogs emerged from the teleost-specific whole genome duplication (TWGD or 3R), would have been lost shortly after the 3R, before the emergence of the basal groups of teleosts. This led to the presence of a single gnih in extant teleosts as in other vertebrates. Two gnih paralogs were still found in some teleost species, such as in salmonids, but resulting from the additional whole genome duplication that specifically occurred in this lineage (4R). Eel gnih was mostly expressed in the diencephalon part of the brain, as analyzed by quantitative real-time PCR. Cloning of eel gnih cDNA confirmed that the sequence of the GnIH precursor encoded three putative mature GnIH peptides (aaGnIH-1, aaGnIH-2 and aaGnIH-3), which were synthesized and tested for their direct effects on eel pituitary cells in vitro. Eel GnIH peptides inhibited the expression of gonadotropin subunits (lhβ, fshβ, and common a-subunit) as well as of GnRH receptor (gnrh-r2), with no effect on tshβ and gh expression. The inhibitory effect of GnIH peptides on gonadotropic function in a basal teleost is in agreement with an ancestral inhibitory role of GnIH in the neuroendocrine control of reproduction in vertebrates.

Local population frequently consumes moray eels and dusky groupers from the Canary Islands. These species are top predators and the interactions between them include predation but also, in some cases, collaborative hunting. These fish are well known to cause ciguatera (CFP) outbreaks in several marine areas such as Japan, Hawaii, French Polynesia and Caribe. Groupers have been involved in CFP events in the Canary Islands, however, moray eels have not yet been well studied in this regard. The present research seeks to describe the finding of a black moray in the stomach of a positive dusky grouper during its necropsy, and to clarify the implication of groupers and moray eels in the food webs, accumulating CTXs in the Canarian environment. The study also updates statistics on the presence of toxic groupers in this archipelago. For these purposes, 248 grouper samples from the CFP official control in the Canary Islands (2018–2019) were analysed and 36 moray eels (5 species) were collected under the EuroCigua project and one was obtained during a dusky grouper necropsy. All samples were analysed with the Neuro-2a cell-based assay (CBA) to evidence CTX-like toxicity. Regarding the necropsied grouper and the moray eel found in its stomach content, the LCMS/MS method allowed the identification and quantification of CCTX1 in both fish at similar levels while none of the P-CTXs for which standards were available were detected. Among groupers, 25.4 % displayed CTX-like toxicity with differences between islands. For moray eels 38.9 % showed toxicity, involving 4 species. Black moray exhibited a high proportion of positives (9/12) and a positive correlation was found between CTX-like toxicity quantification and the black moray weight. Regarding the grouper, and the moray eel found in its stomach, the LCMS/MS method allowed the identification and quantification of C-CTX1 in both fish at similar levels. This found suggests a trophic interaction between these species and their role in maintaining CTXs in the Canary waters where local population commonly demand those species for consumption. The island of El Hierro stands out above all the other Canary Islands with the concerning percentage of positive grouper samples and the high CTX toxicity levels obtained in moray eel specimens analysed in this marine area. This is the first report of CTX-like toxicity in flesh of moray eels fished in the Canary archipelago and the confirmation of the presence of C-CTX1 by LCMS/MS in a black moray from this marine area. info:eu-repo/semantics/acceptedVersion

Previous research has established a correlation between literacy skills and sign language skills among deaf children raised in signing families, but little research has examined the impact of early signing skills on the rate of growth of emergent literacy in early childhood. A subset of data was extracted from a larger dataset containing national longitudinal data from a three-year investigation of early literacy development of deaf children who were between the ages of three and six at the outset of the study. Selection criteria for inclusion in this limited sample included: 1) being rated as having little or no access to spoken language and 2) being raised in homes in which signs were regularly used as a means of communication (N = 56). Our purpose was twofold: 1) to examine and describe the trajectories of growth in letter and word identification skill for this sample in relation to the participants' initial ages; and 2) to assess the degree to which the presence or deaf parents in the home (DoD) and the receptive American Sign Language (ASL) skills of the participants impacted both the level of emerging print literacy and its rate of growth over the three year period. We hypothesized that both the presence of a deaf parent in the home and the acquisition of ASL skills, a strong native language, would contribute to both the overall letter and word identification skills and to the rates of growth of this skill over time. Results indicated that having a deaf parent did, indeed, impact emergent literacy attainment, but its effect was rendered nonsignificant when ASL skill was taken into consideration. Possession of stronger ASL skills, whether or not the children had deaf parents, contributed significantly to both the levels and rate of growth. The findings contribute to the body of work that emphasizes the importance early language skills (spoken or signed) to later academic success and dispels the myth that deaf children with deaf parents have exclusive access to the acquisition of these skills.

In spite of many decades of research, the spawning migration of the European eel Anguilla anguilla from the European coast to the Sargasso Sea remains a mystery. In particular, the role of the swimbladder as a buoyancy regulating structure is not yet understood. In this study, we exercised silver eels in a swim tunnel under elevated hydrostatic pressure. The transcriptome of gas gland tissue of these exercised eels was then compared to the known transcriptome of not exercised (control) silver eel gas gland cells. Due to the high infection rate of the eel population with the swimbladder parasite Anguillicola crassus, the comparison also included an exercised group of silver eels with a heavily damaged swimbladder, and we compared the previously published transcriptome of not exercised silver eels with a highly damaged swimbladder with the exercised group of silver eels with a heavily damaged swimbladder. The comparisons of unexercised (control) silver eels with exercised silver eels with functional swimbladder (EF), as well as with exercised silver eels with damaged swimbladder (ED), both showed a significant elevation in transcripts related to glycolytic enzymes. This could also be observed within the comparison of unexercised silver eels with a highly infected swimbladder with exercised eels with a damaged swimbladder (DED). In contrast to EF, in ED a significant elevation in transcript numbers of mitochondrial NADH dehydrogenase was observed. While in EF the transcriptional changes suggested that acid production and secretion was enhanced, in ED these changes appeared to be related to thickened tissue and thus elevated diffusion distances. The remarkable number of differentially expressed transcripts coding for proteins connected to cAMP-dependent signaling pathways indicated that metabolic control in gas gland cells includes cAMP-dependent pathways. In contrast to ED, in EF significant transcriptional changes could be related to the reconstruction of the extracellular matrix, while in ED tissue repair and inflammation was more pronounced. Surprisingly, in exercised eels hypoxia inducible transcription factor expression was elevated. In EF, a large number of genes related to the circadian clock were transcriptionally modified, which may be connected to the circadian vertical migrations observed during the spawning migration.

Our previous work documented significant advancements in steroid-induced progression of oogenesis, demonstrating that co-treatment of female eels with 11-ketotestosterone (11KT) and estradiol-17β (E2) successfully induced uptake of vitellogenin by oocytes. Here we evaluate the effects of this steroid co-treatment on subsequent time to ovulation and egg quality in shortfinned eels artificially matured by hypophysation. Co-treatment with 11KT (1 mg) and E2 (0.2 or 2 mg) significantly reduced time to ovulation and therefore, the amount of pituitary homogenate required, without any detrimental effects on gonadosomatic index, oocyte diameter or the total weight of stripped eggs. E2 treatment resulted in promising increases in fertilization rates. These indicators suggest that co-treatment with 11KT and E2 holds promise for future artificial maturation practices in terms of minimising fish handling and stress, and of reducing the need for expensive pituitary preparations.

Low egg quality and embryonic survival are critical challenges in aquaculture, where assisted reproduction procedures and other factors may impact egg quality. This includes European eel (Anguilla anguilla), where pituitary extract from carp (CPE) or salmon (SPE) is applied to override a dopaminergic inhibition of the neuroendocrine system, preventing gonadotropin secretion and gonadal development. The present study used either CPE or SPE to induce vitellogenesis in female European eel and compared impacts on egg quality and offspring developmental competence with emphasis on the maternal-to-zygotic transition (MZT). Females treated with SPE produced significantly higher proportions of floating eggs with fewer cleavage abnormalities and higher embryonic survival. These findings related successful embryogenesis to higher abundance of mRNA transcripts of genes involved in cell adhesion, activation of MZT, and immune response (dcbld1, epcam, oct4, igm) throughout embryonic development. The abundance of mRNA transcripts of cldnd, foxr1, cea, ccna1, ccnb1, ccnb2, zar1, oct4, and npm2 was relatively stable during the first eight hours, followed by a drop during MZT and low levels thereafter, indicating transfer and subsequent clearance of maternal mRNA. mRNA abundance of zar1, epcam, and dicer1 was associated with cleavage abnormalities, while mRNA abundance of zar1, sox2, foxr1, cldnd, phb2, neurod4, and neurog1 (before MZT) was associated with subsequent embryonic survival. In a second pattern, low initial mRNA abundance with an increase during MZT and higher levels persisting thereafter indicating the activation of zygotic transcription. mRNA abundance of ccna1, npm2, oct4, neurod4, and neurog1 during later embryonic development was associated with hatch success. A deviating pattern was observed for dcbld1, which mRNA levels followed the maternal-effect gene pattern but only for embryos from SPE treated females. Together, the differences in offspring production and performance reported in this study show that PE composition impacts egg quality and embryogenesis and in particular, the transition from initial maternal transcripts to zygotic transcription.

The life cycle of European eel (Anguilla anguilla), a catadromous species, is complex and enigmatic. In nature, during the silvering process prior to their long spawning migration, reproductive development is arrested, and they cease feeding. In studies of reproduction using hormonal induction, eels are equivalently not feed. Therefore, in female eels that undergo vitellogenesis, the liver plays different, essential roles being involved both in vitellogenins synthesis and in reallocating resources for the maintenance of vital functions, performing the transoceanic reproductive migration and completing reproductive development. The present work aimed at unravelling the major transcriptomic changes that occur in the liver during induced vitellogenesis in female eels. mRNA-Seq data from 16 animals (eight before induced vitellogenesis and eight after nine weeks of hormonal treatment) were generated and differential expression analysis was performed comparing the two groups. This analysis detected 1,328 upregulated and 1,490 downregulated transcripts. Overrepresentation analysis of the upregulated genes included biological processes related to biosynthesis, response to estrogens, mitochondrial activity and localization, while downregulated genes were enriched in processes related to morphogenesis and development of several organs and tissues, including liver and immune system. Among key genes, the upregulated ones included vitellogenin genes (VTG1 and VTG2) that are central in vitellogenesis, together with ESR1 and two novel genes not previously investigated in European eel (LMAN1 and NUPR1), which have been linked with reproduction in other species. Moreover, several upregulated genes, such as CYC1, ELOVL5, KARS and ACSS1, are involved in the management of the effect of fasting and NOTCH, VEGFA and NCOR are linked with development, autophagy and liver maintenance in other species. These results increase the understanding of the molecular changes that occur in the liver during vitellogenesis in this complex and distinctive fish species, bringing new insights on European eel reproduction and broodstock management.

The eastern Baltic cod (Gadus morhua) population has been decreasing in the Baltic Sea for at least 30 years. Condition indices of the Baltic cod have decreased, and previous studies have suggested that this might be due to overfishing, predation, lower dissolved oxygen or changes in salinity. However, numerous studies from the Baltic Sea have demonstrated an ongoing thiamine deficiency in several animal classes, both invertebrates and vertebrates. The thiamine status of the eastern Baltic cod was investigated to determine if thiamine deficiency might be a factor in ongoing population declines. Thiamine concentrations were determined by chemical analyses of thiamine, thiamine monophosphate and thiamine diphosphate (combined SumT) in the liver using high performance liquid chromatography. Biochemical analyses measured the activity of the thiamine diphosphate-dependent enzyme transketolase to determine the proportion of apoenzymes in both liver and brain tissue. These biochemical analyses showed that 77% of the cod were thiamine deficient in the liver, of which 13% had a severe thiamine deficiency (i.e. 25% transketolase enzymes lacked thiamine diphosphate). The brain tissue of 77% of the cod showed thiamine deficiency, of which 64% showed severe thiamine deficiency. The thiamine deficiency biomarkers were investigated to find correlations to different biological parameters, such as length, weight, otolith weight, age (annuli counting) and different organ weights. The results suggested that thiamine deficiency increased with age. The SumT concentration ranged between 2.4-24 nmol/g in the liver, where the specimens with heavier otoliths had lower values of SumT (P = 0.0031). Of the cod sampled, only 2% of the specimens had a Fulton's condition factor indicating a healthy specimen, and 49% had a condition factor below 0.8, indicating poor health status. These results, showing a severe thiamine deficiency in eastern Baltic cod from the only known area where spawning presently occurs for this species, are of grave concern.

Thyroid-stimulating hormone (TSH) is an important glycoprotein in hypothalamic-pituitary-thyroid axis, which plays a crucial role in the synthesis and release of thyroid hormones in vertebrates. Rice field eel, Monopterus albus, a protogynous hermaphroditic fish, which undergoes sex reversal from a functional female to a male, is an ideal model to investigate the regulation of sex differentiation. In this study, we obtained the cDNA sequence of thyroid-stimulating hormone β subunit (tshβ) from rice field eel, which contained a complete open reading frame and encoded a putative protein of 151 amino acids. Multiple alignment of protein sequences showed that tshβ was highly conserved in teleost. The tissue distribution indicated that tshβ showed high expression in the pituitary, moderate expression in the brain region, gonad, intestine and liver, and low expression in other peripheral tissues. During natural sex reversal, the expression of tshβ had no significant difference in the pituitary. Compared to that in the ovary, the expression of tshβ increased significantly in the gonad at late intersexual and male stages. After treatment by different doses of triiodothyronine (T3) (1 μg/g, 10 μg/g and 100 μg/g body weight), serum T3 and free triiodothyronine (FT3) increased sharply, while the expression of tshβ were inhibited significantly in the pituitary. Although T3 had no significant effect on the levels of serum E2, it stimulated the release of serum 11-KT at high-dose group. We also detected the effects of T3 on the expression of gonadal differentiation-related genes in rice field eel. T3 treatment inhibited the expression of foxl2, cyp19a1a and dax1, while stimulated the expression of sox9a1. These results indicate that TSH may be involved in sex differentiation, and THs may play roles in the regulation of male development and sex reversal in rice field eel.

In a study of 39 isolates of Edwardsiella piscicida made from Korean aquaculture sites, sul genes were detected in 16 isolates and dfr genes in 19. Ten isolates were shown to contain both sul and dfr genes. MIC and disc diffusion zones assays were performed to measure the phenotypic susceptibilities of the 39 isolates. Normalized resistance interpretation was applied to these data to categorize isolates as either fully susceptible or as manifesting reduced susceptibility. The standard CLSI protocols specify the use of a mixture of sulfamethoxazole/trimethoprim (20:1) in both MIC and disc diffusion tests. Using the CLSI MIC protocol, 100% of the isolates containing dfr genes, but only 75% of the isolates containing sul genes, were categorized as manifesting reduced susceptibility. Using the CLSI disc diffusion protocol, only 58% of the isolates containing dfr genes and 69% of those containing sul genes were categorized as manifesting reduced susceptibility. When the single agent trimethoprim was substituted for the combined mixture in both the MIC and disc diffusion protocols, 100% of the dfr-positive isolates were categorized as NWT. When the single-agent sulfamethoxazole was substituted, the analysis of the MIC characterized 100% and the disc zone data 94% of the sul-positive isolates as manifesting reduced susceptibility. It is argued that the use of trimethoprim and sulfamethoxazole as single agents in phenotypic susceptibility tests would provide more meaningful data than the currently recommended use of these two agents combined.

Genetically encoded fluorescent sensors are widely used to visualize secondary messengers, metabolites and dynamic events in living cells. However, almost all of these sensors are based on Aequorea GFPs or GFP-like proteins, which do not correctly maturate and fluoresce under hypoxia or anoxic conditions, greatly limiting their application in biomedical research. Herein, we provide a novel strategy for design of sensors and report a series of thiol redox-sensitive sensor based on a recently discovered oxygen-independent fluorescent protein UnaG from Japanese eel. These redox sensors have large dynamic range, rapid responsiveness, a flexible "switch", and pH-independence, are particularly compatible with hypoxia conditions, and therefore represent a substantial improvement for live-cell redox measurement. We further demonstrated the versatility of these redox sensors, by simultaneously monitoring redox changes and hypoxia state in living cells, thereby proving its capability as a powerful and flexible tool for indexing multidimensional metabolism data in the context of physiological stressors and pathological states. These redox sensors are not only the first case of UnaG-based functional sensors, but also the first case of functional sensors based on non GFP-like proteins. Based on this strategy, more oxygen-independent biosensors could be developed, hence, provide new opportunities for bioimaging.

Alzheimer’s disease (AD) is the most common progressive form of brain neurodegeneration and the most prevailing cause of dementia. Unfortunately, the aetiology of AD is not completely studied but different factors are associated with the development of AD such as among others low level of acetylcholine, aggregation of β-amyloid (Aβ), hyperphosphorylated tau protein, oxidative stress, and inflammation. The study encompass organic syntheses of 2,3-dihydro-1H-cyclopenta[b]quinoline with 5,6-dichloronicotinic acid and suitable linkers derivatives as multifunctional agents for AD treatment. Afterwards self-induced amyloid beta aggregation, inhibition studies of acetylcholinesterase and butyrylcholinesterase and molecular docking studies were performed. The results showed that 3b compound exhibited the best acetylcholinesterase inhibitory activity, with IC50 value of 0.052 µM which is lower compared to references. Besides, all synthesised compounds showed good butyrylcholinesterase inhibitory activity with IC50 values from 0.071 to 0.797 µM. Compound 3b exhibited strong Aβ1–42 aggregation inhibitory effect with 25.7% at 5 µM to 92.8% at 100 µM as well as good anti-inflammatory effect. Thus, new compounds could create new perspectives for further development as a multi-target-directed agent for AD treatment.

The bacterium Pseudomonas anguilliseptica has in recent years emerged as a serious threat to production of lumpfish in Norway. Little is known about the population structure of this bacterium despite its association with disease in a wide range of different fish species throughout the world. The phylogenetic relationships between 53 isolates, primarily derived from diseased lumpfish, but including a number of reference strains from diverse geographical origins and fish species, were reconstructed by Multi-Locus Sequence Analysis (MLSA) using nine housekeeping genes (rpoB, atpD, gyrB, rpoD, ileS, aroE, carA, glnS and recA). MLSA revealed a high degree of relatedness between the studied isolates, altough the seven genotypes identified formed three main phylogenetic lineages. While four genotypes were identified amongst Norwegian lumpfish isolates, a single genotype dominated, irrespective of geographic origin. This suggests the existence of a dominant genotype associated with disease in production of lumpfish in Norwegian aquaculture. Elucidation of the population structure of the bacterium has provided valuable information for potential future vaccine development.

Background Fish bones are common foreign bodies in the upper aero-digestive tract, but their clinical features in relation to fish species have not been confirmed. We aimed to clarify the clinical characteristics of fish-bone foreign bodies and their location and removal methods depending on the fish species. Study design Retrospective, observational, monocentric study. Methods From October 2015 to May 2020, 368 patients visited the Department of Otolaryngology-Head and Neck Surgery at Tohoku University Hospital complaining of dysphagia, sore throat, or pharyngeal discomfort after eating fish. We analyzed the patients’ sex and age distribution, foreign-body location, type of the fish, and the techniques used for removing the foreign body. Results Fish bones were confirmed in the upper aero-digestive tract in 270 cases (73.4%), of which 236 (87.4%) involved fish-bone foreign bodies in the mesopharynx. The most frequently involved site was the palatine tonsil (n = 170). Eel was the most frequently observed fish species (n = 39), followed by mackerel (n = 33), salmon (n = 33), horse mackerel (n = 30), and flounder (n = 30). Among the 240 cases in which the bones did not spontaneously dislocate, 109 (45.4%) were treated by endoscopic removal (103 cases) or surgery (6 cases). In pediatric cases ( Conclusion The characteristics of fish-bone foreign bodies differed depending on the fish species. Flounder bones were often stuck in the hypopharynx and esophagus and were likely to require more invasive removal methods. Confirming the species of the fish could facilitate appropriate diagnosis and treatment of fish-bone foreign bodies.

Background: We have recently developed a method to visualize the distribution of DNA in the cytoplasm of bacteria by analytical electron microscopy (EM), using the Phosphorus signal (dsDNA contains two phosphate groups per each nucleotide pair), that was detected and mapped onto the image of the cell (Danilova et al, 2020; Loiko et al, 2020). Here we applied this technique to study much smaller objects – the DNA packing inside bacteriophage heads. We studied phiEL, giant phiKZ-like bacteriophage of the Myoviridae family that infects Pseudomonas aeruginosa (Krylov et al, 2003). We have earlier demonstrated that this phage contains an ‘inner body’ inside its capsid, which is responsible for the specific DNA packing (Sokolova et al, 2014). Methods: The phage propagation was performed as described before (Sokolova et al, 2014). A 3 ul sample of purified bacteriophage phiEL was applied to the glow-discharged carbon-coated copper grid and stained with freshly prepared ammonium Molybdate 2% aquatic solution for 30 sec. Grids were loaded into Gatan cooling holder and the temperature of the specimen was kept at -180°C. EELS spectra and phosphorus elemental maps were obtained on JEOL2100 microscope, operating at 200 kV with the Gatan GIF Quantum ER spectrometer in STEM mode. Pixel size was set to 15-20 nm. STEM drift correction was applied after each 40-50 pixels. Each spectrum was obtained at a 6.0 mrad collection angle, 0.25 eV dispersion, and 132 eV energy shift. The spectra from different pixels were aligned to carbon K-edge. Results: Phosphorus mapping inside and outside the bacteriophage capsid was performed (Fig. 1). Outside the capsid, the phosphorus signal was practically absent, which corresponds to the presence of DNA only inside the capsid. The distribution of phosphorus inside the capsid was uneven: the rectangular area in the middle of the capsid contained a weak signal, while a more intense signal was detected on the periphery. This can be explained by the presence of an ‘inner body’ inside (Fig. 1C). Conclusion: Thus, our results justify the possibility of using the analytical EM technique to study the distribution of DNA by mapping Phosphorus in biological nano-objects at relatively low content of the element.

The effects of perinatal exposure to low, intermediate, or highly polluted eels on neonatal, postnatal, adult and middle-aged brain inflammation, and on cognitive performances of middle-aged offspring mice were compared to those of offspring controls. Inflammatory markers in microglia were assessed in offspring on the postnatal days–PNDs 1, 21, 100 and 330. Activated p38MAPK, ERK-1/2 and p65, and acetylcholine levels were assessed in the middle-aged hippocampus. Plasma myeloperoxidase and corticosterone levels were evaluated at PND 330. Learning and its retention, and working memory in middle-aged offspring were assessed using the Morris water maze, and Y-maze. Our results showed enhanced microglia production of inflammatory markers across the lifespan of male as well as female exposed offspring. Inflammation and increased p38 MAPK activation were detected in the exposed middle-aged hippocampus of both exposed sexes. Significant levels of MPO, but not corticosterone, were found in middle-aged males and females perinatally exposed to eels. However, decreases in ERK1/2 and p65 activation, and acetylcholine levels were only detected in female hippocampus exposed to either intermediately or highly polluted eels. Sex selective effects were also detected with regard to memory, the only altered cognitive function. Thus, middle-aged females, but not males, perinatally exposed to either intermediately or highly polluted eels take longer to locate the escape platform, spend considerably less time in the platform and perform less visit to the platform in the retention test. Our results suggest perinatal programming of hippocampal-dependent memory deficit by inflammation in middle-aged offspring, in sex and dose dependent manner.

Several eel species of the genus Anguilla are considered endangered due to a severe decline in recruitment. Up to now, the reasons for this threatening development are not fully understood. The eel's highly specialized biology can lead to explicitly high accumulation of globally distributed organic lipophilic contaminants during its continental life. Because of this and due the particular toxicological sensitivity of early life stages of oviparous organisms towards dioxin-like compounds, it is crucial to improve our understanding concerning toxicokinetics and maternal transfer of organic contaminants in eels. This study presents analytical data on maternal transfer of dioxin-like (dl) compounds in relevant tissue samples taken from artificially matured and non-matured European silver eels (Anguilla anguilla) from German inland waters using gas chromatography coupled with mass spectrometry (GC/MS) and high-resolution mass spectrometry (GC/HRMS). Detected concentrations revealed a lipid-driven transfer of targeted compounds from muscle-fat-reserves to gonads and eggs respectively, with no distinct preferences concerning the chlorination degree of targeted compounds. Dl-PCBs were shown to contribute the major share of toxicity equivalents found in analysed eel tissues. Maternal muscle tissue to egg concentration ratios in wet weight–based samples had a mean of 6.95 ± 1.49 in accordance with the differences in total lipid content in the respective body matrices. Dioxins and furans in analysed samples were (from a toxicological point of view) of less relevance. Furthermore it was shown that muscle concentrations in silver eels could be used in future assessments to make conservative predictions for expected egg concentrations in female eels.

Background The ricefield eel is a protogynous hermaphroditic Synbranchiform species that changes sex naturally from female to male, which offers an interesting model for studying gonadal (particularly ovarian) differentiation in vertebrates. In the present study, transcriptome sequencing of the gonad of ricefield eel larvae was performed to explore the molecular mechanisms underlying the ovarian differentiation and development. Results A total of 301,267,988 clean reads were generated from cDNA libraries of gonadal tissues of ricefield eel larvae at 6, 9, 12, and 20 days post hatching (dph), which contained undifferentiated gonads, differentiating ovaries, ovaries with oogonia, and ovaries with meiotic oocytes, respectively. De-novo assembly of all the clean reads generated a total of 265,896 unigenes with a mean size of 720 bp and a N50 of 1107 bp. RT-qPCR analysis of the developmental expression of 13 gonadal development-related functional genes indicated that RNA-seq data are reliable. Transcriptome data suggest that high expression of female development-related genes and low expression of male development-related genes in the early gonads of ricefield eel larvae participate in the cascade of sex differentiation leading to the final female phenotype. The contrasting expression patterns of genes involved in retinoid acid (RA) synthesis and degradation might result in peak production of RA at 12 dph in the gonad of ricefield eel larvae, and induce molecular events responsible for the initiation of meiosis before the meiotic signs could be observed at 20 dph. In addition, only stra6 but not stra8 could be identified in gonadal transcriptome data of ricefield eel larvae, and the expression pattern of stra6 paralleled those of genes involved in RA synthesis, suggesting that stra6 may be a downstream target of RA and play a role in RA metabolism and/or meiotic initiation in the gonad of ricefield eel larvae. Conclusions The present study depicted the first large-scale RNA sequencing of the gonad of ricefield eel larvae, and identified many important functional genes, GO terms and KEGG pathways involved in gonadal development and germ cell meiosis. Results of the present study will facilitate future study on the ovarian differentiation of ricefield eels and other teleosts as well. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3953-6) contains supplementary material, which is available to authorized users.

Silvering, the last metamorphosis in the eel life cycle induces morphological and physiological modifications in yellow eels (sedentary stage). It pre-adapts them to cope with the extreme conditions they will encounter during their 6000-km spawning migration. A previous study showed that silver eels are able to cope with reactive oxygen species (ROS) over-production linked to an increase in aerobic metabolism during sustained swimming, but the question remains as to whether this mechanism is associated with silvering. A sustained swimming session decreased red muscle in vitro mitochondrial oxygen consumption (MO 2 ) but increased ROS production in both eel stages. The swimming exercise used here was perhaps too intense to induce a stimulation of mitochondrial function or biogenesis even when antioxidant enzyme activities were unchanged. Pro-oxidant/antioxidant imbalance by lipid peroxidation increased in yellow but significantly decreased in silver eels. The silvering process therefore appears to allow a pre-adaptation of red muscle radical metabolism to the demands of spawning migration.

Climate change is leading to significant alterations to ecosystems all over the world and some of the resulting impacts on fish and fisheries are now becoming apparent. Estuaries, which are highly susceptible to climate change because they are relatively shallow and in close proximity to anthropogenic stressors, provide habitat to many fish species at a critical time in the life history, after transport and just prior to settlement in nurseries. Despite this, the long-term impacts of climate change on larval fish at this critical location/stage in the life history are not well documented. The larval fish assemblage of a coastal estuary was sampled once per week for twenty-six years at a fixed location in southern New Jersey, USA. We used ordination and regression analysis to evaluate the whole assemblage, individual species/family occurrence, and trends in total density and diversity over that time. The larval fish assemblage changed significantly in response to warming water temperatures. In addition, approximately one quarter of the species/families in the assemblage exhibited a statistically significant trend in individual occurrence over time. Of these, all five of the five northern-affiliated species decreased in occurrence while 18 of 21 southern-affiliated species increased in occurrence. Finally, total fish density and species diversity increased over the course of the study. The non-uniform response of the species/families in this larval assemblage is similar to what has been documented in other studies that evaluated the temporal trend of open ocean juvenile and adult fish assemblages.