Branchial Arches Research Articles

Myxozoan infection in thinlip mullet Chelon ramada (Mugiliformes: Mugilidae) in the Sea of Galilee

Mullets (Mugilidae) are economically important fish in Israel. Two species of mugilids (i.e., the thinlip mullet Chelon ramada and the flathead grey mullet Mugil cephalus) have been stocked in the Sea of Galilee (Lake Kinneret) in order to increase fishermen’s income and lake water quality. These catadromous species do not reproduce in the lake, consequently, fingerlings have been introduced every year since 1958. Few additional mugilid species have been introduced unintentionally together with these two species, including C. labrosus. Following a survey of myxozoan infections in the Sea of Galilee, we described Myxobolus pupkoi n. sp. infecting the gill arches of C. labrosus, and reported Myxobolus exiguus from visceral peritoneum and gall bladder of C. ramada. Our study indicates that the parasites infecting C. ramada and C. labrosus belong to a lineage of myxozoans infecting mugilids. This result suggests that the infection took place in the Mediterranean Sea, where the fingerlings were caught, before their introduction into the Sea of Galilee. Since 2018 only farm-raised fingerlings have been introduced. We thus recommend to closely monitor the presence of these parasites in the future to determine if the presence of parasites disappear with the introduction of farm-raised fingerlings.

Interindividual variation in maximum aerobic metabolism varies with gill morphology and myocardial bioenergetics in Gulf killifish.

This study asked whether interindividual variation in maximum and standard aerobic metabolic rates of the Gulf killifish, Fundulus grandis, correlates with gill morphology and cardiac mitochondrial bioenergetics, traits reflecting critical steps in the O2 transport cascade from the environment to the tissues. Maximum metabolic rate (MMR) was positively related to body mass, total gill filament length and myocardial oxygen consumption during maximum oxidative phosphorylation (multiple R2=0.836). Standard metabolic rate (SMR) was positively related to body mass, total gill filament length and myocardial oxygen consumption during maximum electron transport system activity (multiple R2=0.717). After controlling for body mass, individuals with longer gill filaments, summed over all gill arches, or greater cardiac respiratory capacity had higher whole-animal metabolic rates. The overall model fit and the explanatory power of individual predictor variables were better for MMR than for SMR, suggesting that gill morphology and myocardial bioenergetics are more important in determining active rather than resting metabolism. After accounting for body mass, heart ventricle mass was not related to variation in MMR or SMR, indicating that the quality of the heart (i.e. the capacity for mitochondrial metabolism) was more influential than heart size. Finally, the myocardial oxygen consumption required to offset the dissipation of the transmembrane proton gradient in the absence of ATP synthesis was not correlated with either MMR or SMR. The results support the idea that interindividual variation in aerobic metabolism, particularly MMR, is associated with variation in specific steps in the O2 transport cascade.

Mcrs1 is required for branchial arch and cranial cartilage development

Mcrs1 is a multifunctional protein that is critical for many cellular processes in a wide range of cell types. Previously, we showed that Mcrs1 binds to the Six1 transcription factor and reduces the ability of the Six1-Eya1 complex to upregulate transcription, and that Mcrs1 loss-of-function leads to the expansion of several neural plate genes, reduction of neural border and pre-placodal ectoderm (PPR) genes, and pleiotropic effects on various neural crest (NC) genes. Because the affected embryonic structures give rise to several of the cranial tissues affected in Branchio-otic/Branchio-oto-renal (BOR) syndrome, herein we tested whether these gene expression changes subsequently alter the development of the proximate precursors of BOR affected structures - the otic vesicles (OV) and branchial arches (BA). We found that Mcrs1 is required for the expression of several OV genes involved in inner ear formation, patterning and otic capsule cartilage formation. Mcrs1 knockdown also reduced the expression domains of many genes expressed in the larval BA, derived from either NC or PPR, except for emx2, which was expanded. Reduced Mcrs1 also diminished the length of the expression domain of tbx1 in BA1 and BA2 and interfered with cranial NC migration from the dorsal neural tube; this subsequently resulted in defects in the morphology of lower jaw cartilages derived from BA1 and BA2, including the infrarostral, Meckel's, and ceratohyal as well as the otic capsule. These results demonstrate that Mcrs1 plays an important role in processes that lead to the formation of craniofacial cartilages and its loss results in phenotypes consistent with reduced Six1 activity associated with BOR.

Expression analysis of nel during zebrafish embryonic development

Nel is a multimeric extracellular glycoprotein which predominantly expressed in the nervous system and play an important role in neural development and functions. There are three nel paralogues included nell2a, nell2b, and nell3 in zebrafish, while systematic expression analysis of the nel family is still lacking. In this study, we performed a phylogenetic analysis on 7 species, in different species the nell2a are highly conserved, as is nell2b. Then, the expression profiles of nell2a, nell2b and nell3 were detected by in situ hybridization in zebrafish embryo, and the result showed that nel genes highly enriched in the central nervous system, but distributed in different regions of the brain. In addition, nell2a is also expressed in the olfactory pit, spinal cord, otic vesicle and retina (ganglion cell layer), nell2b was detected to express in gill arches, olfactory epithelium, olfactory pit, spinal cord, photoreceptor and retina (ganglion cell layer), it should be noted that the expression of nell3 is special, was only detected at 96 hpf in the brain and spinal cord of zebrafish. Overall, our results indicate that nell2a and nell2b genes are expressed in the nervous system and eyes of zebrafish embryo, while nell3 is expressed in different regions in the nervous system. The phylogenetic analysis also shows that nell3 sequences are significantly different from nell2a and nell2b. This study provides new evidence to better understand the role of nel in zebrafish embryo development.

The evo-devo origins of the nasopharynx.

The process by which upper respiratory tract structures have changed over deep evolutionary time is, in part, reflected in the process of embryologic development. The nasopharynx in particular is a centrally located space bounded by components of the respiratory portion of the nasal cavity, cranial base, soft palate, and Eustachian tube. The development of these components can be understood both in terms of embryologic structures such as the branchial arches and paraxial mesoderm and through fossil evidence dating as far back as the earliest agnathan fish of the Cambrian Period. Understanding both the evolution and development of these structures has been an immeasurable benefit to the otolaryngologist seeking to model disease etiology of both common and rare conditions. This discussion is a primer for those who may be unfamiliar with the central importance of the nasopharynx both in terms of our evolutionary history and early embryological development of vital cranial and upper respiratory tract structures.

The Emergence of Embryonic Myosin Heavy Chain during Branchiomeric Muscle Development

A prerequisite for discovering the properties and therapeutic potential of branchiomeric muscles is an understanding of their fate determination, pattering and differentiation. Although the expression of differentiation markers such as myosin heavy chain (MyHC) during trunk myogenesis has been more intensively studied, little is known about its expression in the developing branchiomeric muscle anlagen. To shed light on this, we traced the onset of MyHC expression in the facial and neck muscle anlagen by using the whole-mount in situ hybridization between embryonic days E9.5 and E15.5 in the mouse. Unlike trunk muscle, the facial and neck muscle anlagen express MyHC at late stages. Within the branchiomeric muscles, our results showed variation in the emergence of MyHC expression. MyHC was first detected in the first arch-derived muscle anlagen, while its expression in the second arch-derived muscle and non-somitic neck muscle began at a later time point. Additionally, we show that non-ectomesenchymal neural crest invasion of the second branchial arch is delayed compared with that of the first brachial arch in chicken embryos. Thus, our findings reflect the timing underlying branchiomeric muscle differentiation.

Taxonomy and Systematics of Two New Species of Myxobolus (Cnidaria: Myxobolidae) Parasitizing the Gills of Mugil curema (Mugilidae) from the Brazilian Coast

We describe two new species of Myxobolus (Myxobolidae) found parasitizing Mugil curema from two locations in Brazil: Myxobolus curemae n. sp. from gill arch and rays and Myxobolus maceioensis n. sp. from gill lamellae. We based the descriptions on myxospore morphology, histology, and small-subunit ribosomal DNA sequences. Myxospores of the two new species had similar morphology and morphometry but differed in spore body width and length, and ssrDNA sequences differed by 10.5%. These data supported the diagnosis of the parasites as distinct and novel species. The phylogenetic analysis showed a subclade formed by species that parasitize Mugiliformes, with M. maceioensis n. sp. as a sister species of Myxobolus episquamalis and Myxobolus bizerti, while there is a group of six species that are sister related to M. curemae n. sp. Our analysis was consistent with previous studies suggesting that orders of the hosts are strongly correlated with phylogenetic signals in the Myxobolidae. Myxobolus curemae n. sp. and M. maceioensis n. sp. are new species identified parasitizing M. curema.

Silurichthys exortivus, a new catfish (Teleostei: Siluridae) from eastern Borneo, Indonesia.

Silurichthys exortivus, a new species of silurid catfish, is described from the Mahakam River drainage in eastern Borneo. The new species can be distinguished from congeners in lacking a dorsal fin, having 4 (vs. 67) principal rays on the upper caudal-fin lobe and a combination of: body depth at anus 14.0% SL, caudal peduncle depth 5.1% SL, pelvic fins absent, 54 anal-fin rays, caudal fin with asymmetrical lobes (upper lobe 1.1 times longer than lower), 48 vertebrae, 1 gill raker on the first branchial arch, and a mottled brown body. Based on the reduced number of principal caudal-fin rays, S. exortivus, S. ligneolus and S. sanguineus are hypothesized to form an exclusively Bornean clade.

Sequence of chondrocranial development in basal anurans\u2014Let\u2019s make a cranium

BackgroundThe craniofacial skeleton is an evolutionary innovation of vertebrates. Due to its complexity and importance to protect the brain and aid in essential functions (e.g., feeding), its development requires a precisely tuned sequence of chondrification and/or ossification events. The comparison of sequential patterns of cartilage formation bears important insights into the evolution of development. Discoglossus scovazzi is a basal anuran species. The comparison of its chondrocranium (cartilaginous neuro- & viscerocranium) development with other basal anurans (Xenopus laevis, Bombina orientalis) will help establishing the ancestral pattern of chondrification sequences in anurans and will serve as basis for further studies to reconstruct ancestral conditions in amphibians, tetrapods, and vertebrates. Furthermore, evolutionary patterns in anurans can be studied in the light of adaptations once the ancestral sequence is established.ResultsWe present a comprehensive overview on the chondrocranium development of D. scovazzi. With clearing and staining, histology and 3D reconstructions we tracked the chondrification of 44 elements from the first mesenchymal Anlagen to the premetamorphic cartilaginous head skeleton and illustrate the sequential changes of the skull. We identified several anuran and discoglossoid traits of cartilage development. In D. scovazzi the mandibular, hyoid, and first branchial arch Anlagen develop first followed by stepwise addition of the branchial arches II, III, and IV. Nonetheless, there is no strict anterior to posterior chondrification pattern within the viscerocranium of D. scovazzi. Single hyoid arch elements chondrify after elements of the branchial arch and mandibular arch elements chondrify after elements of the branchial arch I.ConclusionsIn Osteichthyes, neurocranial elements develop in anterior to posterior direction. In the anurans investigated so far, as well as in D. scovazzi, the posterior parts of the neurocranium extend anteriorly, while the anterior parts of the neurocranium, extend posteriorly until both parts meet and fuse. Anuran cartilaginous development differs in at least two crucial traits from other gnathostomes which further supports the urgent need for more developmental investigations among this clade to understand the evolution of cartilage development in vertebrates.

Investigating Zmym2 and Zmym4 as Putative Six1 Co‐Factors

Branchio‐oto‐renal syndrome (BOR) is a condition that presents with variable craniofacial, otic, and/or renal malformations. Half of the BOR patients have a mutation in SIX1or its co‐factor EYA1. As the other 50% of cases are of unknown cause, it is important to identify other putative co‐factors of SIX1 that may contribute to BOR. A screen of the fly interactome identified zinc‐finger MYM‐containing proteins, Zmym2 and Zmym4, as putative co‐factors of Six1. Recent studies have established that Zmym2 is a transcriptional repressor that interacts with Six4 during renal development. The function of Zmym4 has not yet been well characterized. In situ hybridization revealed that they are co‐expressed with six1and eya1 in the pre‐placodal ectoderm (PPE) and are later expressed in the otic vesicle (OV) and neural crest (NC) of Xenopus. Luciferase assays indicate that Zmym4 enhances Six1‐Eya1 transcriptional activity whereas Zmym2 has a mild repressive effect. Loss of either Zmym2 or Zmym4 affects neural border, NC, and PPE marker genes, suggesting that both genes are important for craniofacial development. At later stages, loss of either Zmym2 or Zmym4 results in a reduction in the size of the OV as well as the branchial arch NC; the later results in altered craniofacial cartilages. Current experiments aim to decipher whether Zmym2 and Zmym4 interact with Six1 and/or Eya1 through co‐immunoprecipitation experiments. Collectively, these data indicate that Zmym4 modulates Six1 transcriptional activity, Zmym2 and Zmym4 are required for craniofacial development, and suggests they may contribute to BOR phenotypes.

Tissue Interaction in Pharyngeal Arches

The occurrence of paired pharyngeal arches (PAs) during the embryonic development of vertebrates is an essential step for the formation of head and heart structures. In fish these arches are often called branchial arches. Each PA is very simple built. On the outside is a layer of ectodermal epithelium, on the inside a layer of endodermal epithelium, and in between is a core of mesenchyme formed by mesodermal and neural crest cells. Ectoderm will give rise to outer structures and contributes to few structures connected to the inside of the head (e.g., part of tympanic membrane in tetrapods), endodermal layer will form the lining of the foregut and contributes to formations of glands, the mesodermal cells will give rise to muscles, craniofacial skeleton, and vascularization, and the neural crest cells to craniofacial skeleton and connective tissue, among others. Each arch is associated with an arch‐specific cranial nerve (CN; e.g., PA1 – trigeminal nerve, CN V; PA2 – facial nerve, CN VII, etc.) which innervates the muscles derived from the mesoderm of the same arch. Considering that the PAs are repetitive swellings lateroventrally in the developing embryonic head region in vertebrates, it is fascinating how diverse heads (and hearts) are in these animals.Gene regulatory networks (GRNs) and communication between all tissues play a crucial role in giving each arch its own identity and during differentiation of arch specific cartilages, bones, muscles, and arteries. Well‐known examples are the distribution of homeobox genes along the antero‐posterior and dorso‐ventral axis determining the identity of PAs 1‐6 (7+ in several fishes) and their proximo‐distal orientation. PA1 is determined by Otx2, while the more posterior PAs are determined by overlap of Hox2 (PA2; Hunger & Prince 2002), Hox2 and Hox 3 (PA3), Hox2, Hox3, and Hox4 (PA4+) (Takio et al. 2007). Intrinsic to each arch is the dorso‐ventral axis which is patterned by Dlx genes with Dlx1 and Dlx2 being more dorsally expressed while Dlx5 and Dlx6 are more ventrally expressed (Qui et al. 1997). While these patterning mechanisms are important, the GRNs in the PAs and between tissues are still not well understood.Ectoderm and endoderm signal to the neural crest cells and mesodermal cells to differentiate, and the letter two tissues interact with each other to ensure differentiation in a highly coordinated manner. For example, the interaction of pharyngeal arch core expressed Pax9 and pharyngeal endoderm expressed Tbx1 controls the morphogenesis of the 4th pharyngeal arch artery (Phillips et al. 2019). Sonic hedgehog (Shh) is expressed in the pharyngeal ectoderm and endoderm and essential for the development of mandibular arch (1st PA)‐derived cartilages (jaw) (Billmyre & Klingensmith 2015). In recent years several other examples of tissue interactions were provided. Here, I aim to provide an overview of the most recent described GRNs and tissue interactions relevant for the differentiation of PA‐derived musculature and its dependence or independence on the development of cranial nerves innervating them.ReferencesBillmyre KK & Klingensmith J (2015). DevDyn 244, 564‐576.Phillips HM, et al. (2019). Development 146, dev177618.Qiu M, et al. (1997). DevBiol 185, 165‐184.Takio Y, et al. (2007). DevBiol 308, 606‐620.Trainor PA & Krumlauf R (2001). CurOpCellBiol 13, 698‐705.

Morphological Characterization and Molecular Phylogenetic Analysis of Kudoa iwatai from Large Yellow Croaker (Larimichthys crocea) as a New Host in China.

Simple SummaryLarimichthys crocea is the most important economic marine cultured fish in China. Kudoa parasites are critical pathogens that infect a wide range of marine and freshwater fish. Compared to the hundred marine Kudoa species recognized in wild and cultured fish worldwide, records of Kudoa are relatively few in China. In this report, large yellow croakers were found to be infected with Kudoa for the first time in China. Morphological observations and molecular techniques were combined for the final identification of Kudoa iwatai. Additionally, the morphological characterization and phylogenetic status of Kudoa iwatai have been described in detail. This study enriches knowledge about Kudoa iwatai and provides a direction for early disease prevention and monitoring of large yellow croakers.Kudoa (Myxosporea: Multivalvulida) parasites are critical pathogens in marine and freshwater fish associated with significant economic losses and reduced market prices caused by post-mortem myoliquefaction or numerous cysts on muscles. In the present study, large yellow croakers infected by Kudoa were found during fish disease surveillance in China in November 2020 and used for morphological observation and characterization using light DIC microscopy and electron microscopy. Numerous creamy-white oval plasmodia were observed in muscles and on the surface of brain cartilage, gill arches, and serosal surfaces. The spores were considerably longer and thicker than previously reported Kudoa, with protruding polar filaments (PFs) in the mature spores, fingertip-shaped apical projections (APs), and polar capsules. Phylogenetic analyses with SSU rDNA, LSU rDNA, and mitochondrial DNA showed that the Kudoa-infected sample (LcK-2020) had the highest similarity to Kudoa iwatai reported in Japan. Based on the morphological characterization and phylogenetic analysis, it could be concluded that the sample LcK-2020 was infected by Kudoa iwatai, which would be the first report of Kudoa iwatai infection in large yellow croaker in China.

Field evaluation of diagnostic sensitivity (DSe) and specificity (DSp) of common tests for amoebic gill disease (AGD) and complex gill disease (CGD) in cultured Atlantic salmon (Salmo salar) in Scotland using Bayesian latent class models

Amoebic gill disease (AGD) and complex gill disease (CGD) are the most significant marine gill diseases in salmon aquaculture in Scotland. Little is published about diagnostic performance of tests to detect these diseases, making it difficult to interpret test results. We estimated diagnostic sensitivity (DSe) and specificity (DSp) of common tests for AGD (gross AGD score, qPCR for Neoparamoeba perurans, histopathology) and CGD (gross proliferative gill disease (PGD) score, gross total gill score, histopathology). Because specifications in our sampling protocol implemented to encourage consistency across the farms might affect diagnostic performance of histopathology (historically the reference standard for gill diseases), we used Bayesian latent class models without reference standard. Cases and non-cases were based on less, medium, and severe stringent case definitions, representing different cut-off levels for the different tests. Gross gill scores for both diseases were excellent in designating non-diseased fish, DSps were generally around 1. To detect CGD, DSe of gross total gill score and gross PGD score were between respectively 0.81 (0.73 – 0.91 lower to upper 95% credible interval) and 0.53 (0.46 – 0.64) for medium stringent case definitions, and to detect AGD the DSe for the gross AGD score was between 0.53 (0.48–0.57) and 0.14 (0.07 – 0.22) for respectively the less and severe stringent case definition. Thus, gross gill scores were medium to good in designating truly diseased fish, implying some false negatives are expected. For CGD the DSe for gross total gill scores were the highest, for AGD it was the qPCR test at a DSe of 0.92 (0.86 – 0.99). For both diseases, DSe was lowest for histopathology, e.g. 0.23 (0.16 – 0.30) for AGD and 0.1 (0.07 – 0.14) for CGD under medium stringent case definitions, perhaps due to collecting the second gill arch on the right rather than the worst affected arch, whilst PCR sampling and gross gill scoring included multiple (PCR) or all (gross scoring) gill arches. The diagnostic goals of these tests differ; gross gill scoring provides a low-cost presumptive diagnosis, PCR a non-lethal confirmation of the presence of a specific pathogen and histopathology provides information on the underlying aetiology of gill damage as well as the extent, severity, and chronology of gill disease. An effective gill health surveillance strategy is likely to incorporate multiple diagnostic tools used in a complementary manner.

A Neural Crest-specific Overexpression Mouse Model Reveals the Transcriptional Regulatory Effects of Dlx2 During Maxillary Process Development.

Craniofacial morphogenesis is a complex process that requires precise regulation of cell proliferation, migration, and differentiation. Perturbations of this process cause a series of craniofacial deformities. Dlx2 is a critical transcription factor that regulates the development of the first branchial arch. However, the transcriptional regulatory functions of Dlx2 during craniofacial development have been poorly understood due to the lack of animal models in which the Dlx2 level can be precisely modulated. In this study, we constructed a Rosa26 site-directed Dlx2 gene knock-in mouse model Rosa26 CAG-LSL-Dlx2−3xFlag for conditionally overexpressing Dlx2. By breeding with wnt1 cre mice, we obtained wnt1 cre ; Rosa26 Dlx2/- mice, in which Dlx2 is overexpressed in neural crest lineage at approximately three times the endogenous level. The wnt1 cre ; Rosa26 Dlx2/- mice exhibited consistent phenotypes that include cleft palate across generations and individual animals. Using this model, we demonstrated that Dlx2 caused cleft palate by affecting maxillary growth and uplift in the early-stage development of maxillary prominences. By performing bulk RNA-sequencing, we demonstrated that Dlx2 overexpression induced significant changes in many genes associated with critical developmental pathways. In summary, our novel mouse model provides a reliable and consistent system for investigating Dlx2 functions during development and for elucidating the gene regulatory networks underlying craniofacial development.

Phenotypic study for embryonic and larval development of common carp (Cyprinus carpio L., 1758)

The early development of common carp (Cyprinus carpio L., 1758) was studied from fertilizing until juvenile stage. The series developmental staging was done using morphological characteristics. Results identified eight main periods of embryogenesis: zygote, morula, blastula, gastrula, neurella, segmentation, pharyngula and hatching period. Results also identified and described nine larval development stages: hatching larva stage, rudimentary - pectoral fin and gill arch stage, melanoid-eye with gas bladder emergence stage, one chamber gas bladder with yolk absorption stage, two chamber gas bladder stage, pelvic fin bud with dorsal fin formation stage, anal-caudal and pelvic fin formation stage, squamation stage and juvenile stage. Hatching occurred at 38h after egg fertilization. The fertilized egg was spherical, yellowish, transparent and 2.5 mm in diameter. The transition from larva to juvenile occurred in 30 days.

Morphology and Anatomy of Endemic Fish Leptobarbus melanopterus (Cyprinidae) in Danau Sentarum National Park Kapuas Hulu Regency

One of the endemic freshwater fishes in Danau Sentarum National Park (DSNP) is Leptobarbus melanopterus which has high economic value for both commercial and collection purpose. However, the overfishing of L. melanopterus running over decades with harmful catch tools is worried could contribute to the population decline in the future. At the same time, this species has never been cultured and fishermen catch directly in the habitat on a daily basis. This research was aimed to identify the morphological and anatomical characters of L. melanopterus. All samples were collected from three different sites in DSNP and measured its morphological and anatomical sizes manually. The results showed that the length of mandibula barbel was the distinguishing character between females and males, with loading score of 0.81. Most meristic variables showed no difference between two sexes. In terms of anatomical measurements, L. melanopterus females had larger gill sizes than males, including gill raker, gill arch and fill filament. Our findings signify the thorough morphological and anatomical sizes of L. melanopterus which are important in identifying fish stock, growth pattern and sexual dimorphism for future culture management.

Assessment of the ameliorative roles of vitamin e on the histopathology of Clarias Gariepinus (Burchell, 1822) fingerlings exposed to lead nitrate

Pollution of aquatic ecosystems is constantly increasing with the increase in anthropogenic activities all over the world with negative effects on the constituent biota. The current study addressed the possibility of remedying the effects posed to the tissues of Clarias gariepinus fingerlings (3-11g initial weight) exposed to lead nitrate over a 12 week period. The treatment groups were Pb only and PbVE (Pb+vitamin E) with T1-T4 and replicate in each case. The sub-lethal treatments of lead nitrate concentrations are as follow: 00 (control), 26mg/L (T1), 44mg/L (T2), 61mg/L (T3) and 79mg/L (T4). 26mg/L concentration of the vitamin was applied to every treatment and replicate of the PbVE group. At the end of the exposure period, gills, liver, and kidneys were excised from the samples and preserved in 10% formalin for histopathological analyses. From the results; the livers of the samples of C. gariepinus exposed to sub-lethal concentration of Pb only group displayed aggregation and lumping together of the hepatocytes, massive necrosis and shattering of the hepatocytes, vacoulation with greater severity as the concentration increased. The samples of PbVE treatment group showed preserved hepatocytes, reduced aggregation and vacoulation of the cells, gradual recovery of the cell nucleus and cytoplasm, normal tissue architecture, and hepatocytes similar to control samples in T1-T3. In the kidneys of Pb only group, there were massive necrosis and vacoulation, shattering of cells, tissue edema, and massive lumping of cells together, especially in higher concentrations. The PbVE treatments displayed reduced necrosis and cells aggregating together coupled with reduced vacoulation, preserved cells, and cells with cytoplasm returning to normal. But these were not sustained in the highest concentration. In the gills of the Pb only group, there was rarefied gill filament with ruptured lamellae, shattered gill arch, and filaments ruptured primary and secondary lamellae with greater severity in higher concentrations. The PbVE group displayed how the gill arch and filaments with the primary and secondary lamellae were gradually restored to a certain extent similar to the control. In all the organs the alteration and amelioration of the architecture were concentration-dependent. Therefore, a proportionate concentration of the vitamin can facilitate faster tissue damage recovery in heavy metal exposure.

P75 neurotrophin receptor positively regulates the odontogenic/osteogenic differentiation of ectomesenchymal stem cells via nuclear factor kappa-B signaling pathway

ABSTRACT p75NTR, a neural crest stem cell marker, is continuously expressed in mesenchymal cells during tooth development. Importantly, high expression of p75NTR in the late bell stage implicates its involvement in odontogenesis and mineralization. However, the regulatory mechanisms underlying p75NTR involvement in odonto/osteogenic differentiation remain unclear. Here, we investigate the effect and potential mechanisms underlying p75NTR involvement in odonto/osteogenic differentiation. We dissected EMSCs from the first branchial arches of mice embryo and compared the proliferation and migration of p75NTR+/+ and p75NTR−/−EMSCs by transwell, scratch and cell counting kit 8(CCK8)assays. The differentiation ability and the involvement of nuclear factor kappa-B (NF-κB) pathway were investigated through alkaline phosphatase and immunofluorescence assay, real-time PCR, and western blot. During induction of dental epithelium conditioned medium, p75NTR+/+ EMSCs exhibited deeper Alkaline phosphatase (ALP) staining and higher expression of odonto/osteogenic genes/proteins (e.g., dentin sialoprotein (DSPP) than p75NTR+/+ EMSCs. Moreover, p75NTR+/+ EMSCs exhibited higher nuclear P65 expression than p75NTR−/−EMSCs. Inhibition of NF-κB pathway with Bay11-7082 in p75NTR+/+EMSCs substantially decreased DSPP expression level. However, activation of NF-κB pathway with Bay11-7082 in p75NTR−/−EMSCs enhanced DSPP expression level. Thus, p75NTR possibly plays a paramount role in the proliferation and differentiation of EMSCs via NF-κB pathway.

Фауна моногенетических сосальщиков рода Dactylogyrus молоди карпа в прудах Оренбургской области

Monogenetic flukes, as a kind of the parasites with a direct development cycle, pose a particular danger to the fish farms. They adapt easier to new conditions due to the absence of intermediate hosts in their life cycle. Among the representatives of the class Monogenea flukes Dactylogyrus parasitize on carp’s gills. Dactylogyrosis are conditionally pathogenic ectoparasites that are dangerous for the young fish. The work presents the results of the parasitological studies of gill arches of carp juveniles grown in ponds of the Orenburg region. There are four species of dactylogyride found: Dactylogyrus vastator, Dactylogyrus extensus, Dactylogyrus achmerowi, Dactylogyrus anchoratus. Only two species of monogenetic flukes were found in fish most often at the early age: Dactylogyrus vastator and Dactylogyrus extensus. The comparison of the infestation of individual gill arches of carp juveniles with dactylogyrids showed that the helminths distribution is not the same in different areas of the gill apparatus. The dactylogyrids proportion on the gill petals of the second gill arc is greater than on the first and third arcs. The helminths proportion found on the petals of the first gill arc does not differ from the worm proportion on the third gill arc. When analyzing the distribution of dactylogyrids by gill sectors, it was found that from 58.9 to 66.0% of monogenetic flukes localize in the middle sector of the gill apparatus of fish, the most strongly washed area of gills. The worm proportions in the abdominal and dorsal sectors differ slightly, except for Dactylogyrus achmerowi, where the helminths proportion in the abdominal section of the gills is almost half less than in the dorsal sector, 14.0 and 27.0%, respectively.

Johnius sasakii, a new species of croaker (Perciformes: Sciaenidae) with a key to Johnius from East Malaysia, Borneo.

A new sciaenid fish, Johnius sasakii sp. nov. from the East Malaysian coastal waters of Sabah and Sarawak, Borneo is described herein. Johnius sasakii sp. nov. can be separated from the close congeners, Johnius heterolepis and Johnius carouna by having less gill rakers on the lower limb of the first gill arch (mode number 9 vs. 10 for J. heterolepis; 11 for J. carouna). It can be distinguished from J. heterolepis with the higher modal number of gill rakers on the upper limb of first gill arch (5 vs. 4), shorter anal-fin base length (9% vs. 10% of SL) and first anal-fin ray length (1012% vs. 1213% of SL) respectively. Furthermore, J. sasakii sp. nov. can be further differentiated from J. carouna by its shorter second anal-fin spine length 710% SL (usually 810%) vs. 1114% SL (usually 1112%) and slightly deeper body depth 2529% SL (usually 2628%) vs. 2328% SL (usually 2426%). Meanwhile, J. sasakii sp. nov. can be easily differentiated from J. macrorhynus by a present of molariform teeth on inner rows of jaws and stumpy gill rakers. Johnius (Johnius) sasakii sp. nov. can be clearly distinguished from species of the subgenus J. (Johnieops) by the lack of enlarged outer row teeth on upper jaw. A Kimura 2-parameter genetic distance comparison of 450 bp sequences of mitochondrial 16S rRNA and 488 bp nuclear gene S7 showed that J. sasakii sp. nov. are highly differentiated from J. heterolepis (16S: 10.4%, S7: 5.8%), J. carouna (16S:19.3%, S7:8.4%); and J. macrorhynus (16S: 16.7%, S7: 8.1%) respectively. The study highlights that the genetic approach from mtDNA and nDNA can contribute to the confirmation of taxonomic status of sympatric species in genus Johnius.