Identification,localization and morphology of APUD cells in gastroenteropancreatic system of stomach-containing teleosts

AIM To identify the type localization andmorphology of APUD endocrine cells in thegastroenteropancreatic(GEP)system ofstomach-containing teleosts,and study APUDendocrine system in the stomach,intestine andpancreas of fish species.METHODS Two kinds of immunocytochemical(ICC)techniques of the streptavidin biotin-peroxidase complex(SABC)and streptavidin-peroxidase(S-P)method were used.Theidentification,localization and morphology ofAPUD endocrine cells scattered in the mucosa ofdigestive tract,intermuscular nerve plexus andglandular body of northern snakehead(Channaargus),ricefield eel(Monopterus albus),yellow catfish(Pelteobagrus fulvidraco),mandarinfish(Siniperca chuatsi),largemouthbass(Micropterus salmoides),orientalsheatfish(Silurus asotus),freshwater pomfret(Colossoma brachypomum)and nile tilapia(Tilapia nilotica)were investigated with 8 kindsof antisera.RESULTS The positive reaction of 5-hydroxytryptamine(5-HT)immunoreactiveendocrine(IRE)cells was found in the digestive tract and glandular body of 8 fish species indifferent degree.Only a few gastrin(GAS)-IREcells were seen in C.argus,M.albus and P.fulvidraco.Glucagon(GLU)-IRE cells were notfound in the digestive tract and glandular bodybut existed in pancreatic island of most fishspecies.The positive reaction of growthhormone(GH)-IRE cells was found only inpancreatic island of S.Chuatsi and S.Asotus,no positive reaction in the other 6 fish species.Somatostatin(SOM)-,calcitonin(CAL)-,neurofilament(NF)-and insulin(INS)-IRE cellsin the stomach,intestine and pancreas of 8 kindsof fish were different in distribution and types.The distribution of all 8 APUD cells was the mostin gastrointestinal epithelium mucosa and then indigestive glands.The positive reaction of SOM-and 5-HT-IRE cells was found in intermuscularnerve plexus of intestine of P.fulvidraco andS.chuatsi.Only GH-IRE cells were denselyscattered in the pancreatic islands of S.chuatsiand S.asotus,and odd distribution in thepancreas of S.asotus,SOM-IRE cells weredistributed in the pancreatic islands of S.asotus,C.Brachypomum and T.nilotica.There were INS-IRE cells in the pancreaticislands of S.chuatsi and S.asolus.Eightkinds of APUD cells had longer cell body andcytoplasmic process when they were located inthe gastrointestinal epithelium,and had shortercell body and cytoplasmic process in the gastricgland,and irregular shape in the esophagus andpancreatic island.CONCLUSION Eight kinds of IRE cells were identified in the GEP system of stomach-containing teleosts. These endocrine cells were scattered in gastrointestinal mucosa, intermuscular nerve plexus, gland body, pancreatic gland and islands under APUD system. CAL- and GH-IRE cells in the pancreatic islands of fishes showed functional diversity for these two hormones. Their morphological feature provides evidence of endocrine-paracrine and endocrine-exocrine acting mode. This research can morphologically prove that the GEP endocrine system of fish ( the lowest vertebrate) is almost the same as of mammal and human.

鱼类非感染性肠炎模型及其病理研究概述

替代鱼粉的植物性蛋白源成分容易引起鱼类肠道屏障受损,不仅抑制鱼类生长性能,也增加病原入侵的机会,因此养殖鱼类经常出现由肠道炎症引起的大规模发病现象。建立鱼类非感染性肠炎模型极大方便了鱼类肠炎机理研究,近年来基于病理模型的相关研究已成为鱼类免疫学和营养学研究的前沿。本文通过阐述常见的模式鱼和经济鱼肠炎模型,从黏膜免疫、肠道结构、微生物组成等方面分析了肠炎的发病机理,以期为鱼类肠炎的防治及相关病理研究提供参考。

硬骨鱼类性别调控对大刺鳅性逆转的启示

鱼类的性别控制受遗传性别决定和环境性别决定两种机制的影响,对水产养殖具有重要意义。与其他脊椎动物相比,鱼类在性别分化和性腺发育方面可塑性强。硬骨鱼类雌雄个体的大小和生长速度存在显著的两性差异,培育和养殖体型大、生长速度快的单性群体有利于提高经济效益。大刺鳅是一种具有高营养价值和经济价值的淡水养殖鱼类,雄性个体比雌性生长速度更快、体型更大,因此培育全雄大刺鳅的经济效益更高。野生大刺鳅雌雄比例约为1∶1,但在人工养殖条件下易出现高雌性率的现象。目前尚不清楚何种因素引起大刺鳅的雌性化,也未见成功诱导大刺鳅生理雌鱼发生性逆转的报道,这极大制约了大刺鳅养殖产业的发展和经济效益的提高。目前关于大刺鳅的研究主要集中在形态学、生理学、繁殖生物学和遗传多样性等方面,关于大刺鳅性别决定与性别分化的研究较为薄弱,需从其他硬骨鱼类的性别决定机制、性别调控方式和性别控制育种技术中发掘思路。基于硬骨鱼类的性别决定机制,综述了硬骨鱼类性别控制的几种方式,主要包括遗传因素调控(如性染色体、常染色体上的性别决定基因)和环境因素调控(如温度、外源激素、饵料等)。旨在为解析人工养殖大刺鳅高雌化的原因及潜在作用机制提供思路,同时为大刺鳅单性种群的繁殖与保持、优良品种的选育和种质资源保护提供重要的理论依据,以期更好地了解大刺鳅性腺发育和生殖机制,解决现阶段养殖大刺鳅雄性率低的瓶颈,为大刺鳅养殖业可持续发展提供保障。

硬骨鱼类虹彩细胞的研究进展

虹彩细胞是硬骨鱼中一类常见的色素细胞,含有大量的虹彩小体,其内含有由鸟嘌呤晶体构成的高折射率的反射小板,反射小板与低折射率的细胞质交替排列形成交替层的结构,光被交替层反射后通过多层薄膜干涉,使细胞呈现出彩虹般的颜色。虹彩细胞能在激素、交感神经系统或外界环境刺激的作用下通过改变反射小板的间距来实现颜色的变化。鸟嘌呤是虹彩细胞呈色和颜色变化的基础,其合成途径已被详细解析。虹彩细胞由多能的神经嵴细胞分化而来,从神经嵴细胞分化为成熟的虹彩细胞的谱系特化过程受到多个基因的调控,目前已在模式生物斑马鱼中发现了一些关键基因,并通过对这些基因间相互作用的研究初步解析了控制虹彩细胞特化的核心基因调控网络,同时也发现了其他影响虹彩细胞特化、分化及存活的基因和信号通路。本文综述了硬骨鱼类虹彩细胞呈色及颜色变化的机制、鸟嘌呤合成途径及调控基因以及影响虹彩细胞发育和存活的基因和信号通路的研究进展,并对未来的研究方向进行了展望,期望能对虹彩细胞有更深入的认识,并为研究虹彩细胞发育过程的基因调控提供参考。

Involvement of gonadal soma-derived factor in the reproduction of teleosts

Gonadal soma-derived factor(Gsdf)is a member of the transforming growth factor beta(TGF-β)superfamily and a teleost-specific gene.Early studies suggested that Gsdf promotes spermatogonial proliferation;however recent reports have shed light on its role in sex differentiation based on expression profiles and gain-and loss-of-function studies.This paper discusses the involvement of Gsdf in gonadal sex differentiation and sex changes in teleosts.

Immunocytochemical identification and localization of APUD cells in the gut of seven stomachless teleost fishes

AIM To study the cell types,localization,distribution density and morphology of APUDcells in the intestinal mucosa of stomachlessteleost fishes.METHOD By using the peroxidase-antiperoxidase complex(PAP)immunocytochemical staining technique theidentification,localization and morphology ofimmunoreactive(IR)endocrine cells seattered inthe intestinal mucosa of grass carp(Cyenopharyngodon idellus),black carp(Mylopharyngodon piceus)and common carp(Cyprinus carpio)were investigated with 20kinds of antisera prepared against mammalianpeptide hormones of APUD cells,and likewise byusing avidin-biotin-peroxidase complex(ABC)method those of silver carp(Hypophthalmichthys molitrix),bighead(Aristichthys nobilis),silver crucian carp(Carassius gibelio)and bluntnose black bream(Megalobrama amblyocephala)were alsostudied with 5 different antisera.Thereplacement of the first antiserum by phosphatebuffered saline(PBS)was employed as a control.IR endocrine cells were counted with asquare-mesh ocular micrometer from 10 fieldsselected randomly in every section of each partof the intestine specimen.The average numberof IR endocrine cells per mm2 was counted toquantify their distribution density.RESULT Gastrin(GAS)-,Gastric inhibitorypeptide(GIP)-,glucagon(GLU)-,glucagon-likeimmunoreactants(GLI)-,bovine pancreaticpolypeptide(BPP)-,leucine-enkephalin(ENK)-and substance P(SP)-IR endocrine cells werefound in the gut of grass carp,black carp andcommon carp,and somatostatin(SOM)-IRendocrine cells were only seen in common carp.GAS-,GIP-and GLU-IR endocrine cells werefound in the intestinal mucosa of silver carp,bighead,silver crucian carp and bluntnose blackbream.Most of IR endocrine cells had the higherdistribution density in the foregut and midgut,and were longer in shape.They had a long apicalcytoplasmic process extended to the gut lumenand a basal process extended to adjacent cellsor basement membrane and touched with it.Sometimes,the basal cytoplasmic processformed an enlarged synapse-like structure in thecontiguous part with basement membrane.Thisphenomenon provided new morphologicalevidence for neuroendocrine and paracrinesecretory function of these enteroendocrinecells.CONCLUTION At least 8 kinds of IR endocrinecells were found in the gut of stomachlessteleost species for the first time in China.TheseIR endocrine cells scattering in the gut mucosabelong to the APUD system.Among them,thehormones secreted by SP-,ENK-,SOM-and GLU-IR endocrine cells belong to the peptides of dualdistribution in the brain and gut.This providednew evidence for the concept of brain-gutpeptide.According to the cell types,distribution density,morphologicalcharacteristics and variety in shape of APUDcells in the gut of stomachless teleost fishes,itis deemed that the digestive tract of fishes isalso an endocrine organ of great importance andcomplexity.

Specific function and modulation of teleost monocytes/macrophages: polarization and phagocytosis

Macrophages exist in most tissues and play a variety of functions in vertebrates.Teleost fish species are found in most aquatic environments throughout the world and are quite diverse for a group of vertebrate animals.Due to whole genome duplication and en vironme ntal adaptati on,teleost monocytes/macrophages possess a variety of different functions and modulations compared with those of mammals.A deeper understanding of teleost monocytes/macrophages in the immune system will not only help develop teleost-specific methods of disease prevention but will also help improve our understanding of the various immune mechanisms in mammals.In this review,we summarize the differences in polarizati on and phagocytosis of teleost and mammalian macrophages to improve our understanding of the various immune mechanisms in vertebrates.

Reduced Life Expectancy Model Analyses of Exposure Time Effects of Endocrine Disruptors to Teleost Fishes Based on Effect Concentration of Hepatic Biomarkers

In this current paper, the exposure time effects on four endocrine disruptors and teleost fishes were evaluated using the reduced life expectancy (RLE) model based on the effect concentration (EC50) of available literature published. The result on the regression analysis over different exposure times has demonstrated that the EC50 of hepatic biomarkers falls with increasing exposure times in a predictable manner. The slopes of the regression equations reflect the strength of the toxic effects on the various teleost fish. The EC50 reduction over time can be interpreted based on the bioconcentration process, which can be used to understand transfer routes of the compounds from water to fish body. RLE model also provides useful information in assessing the toxic effects on fish life expectancy as a result of the occurrence of compounds.

Role of Exogenous Reduced Glutathione on Time Dependent ^(203)Hg Distribution in Liver and Kidney of a Freshwater Teleost, Anabas testudineus

Time-dependent tissue distribution of mercury(Hg) was studied in a freshwater perch,Anabas testudineus which revealed that the liver and kidneys are the major sites of Hg reten tion. The role of reduced glutathione (GSH) in the clearance of Hg was also investigated to e valuate the ameliorative effect of this nucleophile. For this purpose, the perch was given GSH 15 min before or after they received 203Hg by injection. The fish were then sacrificed at 24 h and 48 h later. The results clearly indicate that exogenous GSH can significantly reduce Hg retention in both the liver and kidneys, demonstrating a direct role of this nucleophile in the amelioration of Hg-induced toxicity in the early phase of intoxication

Effect of Fertilizer Diammonium Phosphate on Liver,Kidney and Muscle 5-Nucleotidase Activity of Fresh Water Teleost Fish Clarias batrachus

The toxic effect of fertilizer Diammonium phosphate resulted in alterations of 5'-Nucleotidase activity of tissues liver, kidney and muscles offish C. batrachus at varying intervals and exposures. Alterations in 5'-Nuclcotidase activity of body organs gave an idea of the toxicity caused by the fertilizer. Thus the enzyme 5'-Nucleotidase can be used to monitor the pollution in aquatic ecosystem.

硬骨鱼类鳃黏膜免疫相关分子的研究进展

鳃为鱼类重要的呼吸器官,是鱼类进行离子交换、酸碱调节和含氮废物排泄的重要结构基础,也是鱼类重要的外周黏膜免疫器官之一,在抵御病原微生物侵染过程中发挥重要的免疫屏障作用。当前,硬骨鱼类鳃黏膜免疫反应是研究热点之一。本文首先对硬骨鱼类鳃的结构和特点进行分析,之后综述了抗菌肽、干扰素、白细胞介素、Toll样受体、补体等先天性免疫相关分子以及T细胞受体和免疫球蛋白等适应性免疫相关分子在硬骨鱼类鳃黏膜中的表达规律、分子功能,最后探讨了化学因素(重金属、杀虫剂等)、生物因素(细菌、病毒、真菌、和寄生虫等)以及营养物质和疫苗等对硬骨鱼类鳃黏膜结构的影响,以期为深入研究鳃在鱼类黏膜免疫反应中的角色和应答机制提供指导,为硬骨鱼类病原性疾病的免疫防控策略的制定提供理论基础。

基于单细胞水平的孕二烯酮诱导雌性西部食蚊鱼雄性化的研究

【目的】从单细胞转录组水平研究雌性西部食蚊鱼(Gambusia affinis)性别逆转过程中涉及到的性腺细胞分化发育和基因表达变化,探讨孕二烯酮(Gestodene,GES)作用下食蚊鱼性别反转的分子机制。【方法】将培养驯化2个月后的性成熟雌性食蚊鱼暴露于浓度为500 ng/L的孕二烯酮溶液中进行培养,于第4、8周取样观察其形态变化,并分别取正常雌性对照、雄性对照、暴露4周和8周样本的性腺制成单细胞悬液,进行单细胞转录组测序并分析。【结果】经孕二烯酮处理后的雌性食蚊鱼形态上出现臀鳍类生殖足现象。单细胞转录组测序结果发现,雄性食蚊鱼和雌性食蚊鱼的性腺具有完全不同的细胞构成。雄性食蚊鱼性腺主要由成纤维细胞、雄性生殖细胞、上皮细胞和原始生殖细胞构成,而雌性性腺主要由内皮细胞、成纤维细胞、卵母细胞和原始生殖细胞构成。暴露4、8周后雌性食蚊鱼性腺中出现少量的雄性生殖细胞,且原始生殖细胞数量明显上升。进一步分析发现,原始生殖细胞中性别决定关键基因出现差异化表达情况。细胞轨迹分析表明,部分原始生殖细胞出现向雄性分化的特征,其中有2477个基因在两个不同的分化方向表现出不同的表达模式。KEGG通路富集分析结果表明,Toll-like receptor、TGF-beta、Notch等信号通路参与原始生殖细胞向雄性化逆转的过程,甘氨酸,丝氨酸、苏氨酸、半胱氨酸、甲硫氨酸代谢、氨基糖和核苷酸糖代谢等途径也与该过程相关。【结论】雌性食蚊鱼经孕二烯酮诱导后,在形态学上出现臀鳍雄性化特征,性腺中有部分原始生殖细胞向雄性生殖细胞转化。原始生殖细胞中性别决定关键基因amh、fabp3、dmrt1、wt1a、wt1b、cyp19a1a和fgf16出现差异化表达情况。Toll-like receptor、TGF-beta、Notch和一些氨基酸代谢信号通路参与了原始生殖细胞向雄性化逆转的过程。

Antimicrobial roles of phagocytosis in teleost fish:Phagocytic B cells vs professional phagocytes

The defense system of teleost fish organized on innate and adaptive immunity protects them against a wide variety of pathogenic microorganisms in the aquatic environment.Phagocytosis is one of the most effective defense strategies against microbial challenge mainly performed by classical‘professional’phagocytes(including monocytes,macrophages and granulocytes).They contain,kill and process the internalized pathogens for antigen presentation by providing antigenic ligands to initiate activation and clonal expansion of T and B cells,which bridge the innate and adaptive immunity.The discovery of phagocytic B cells in teleost fish has broken the paradigm that primary vertebrate B cells are lack of phagocytosis of particulates,as well as led to the investigation of phagocytic activity of mammalian B-1 B cells.The active phagocytic,microbicidal capabilities and antigen presentation in teleost phagocytic B cell have demonstrated to be similar as professional phagocytes,providing a potential impact on development of new vaccination strategies to prevent and control infectious diseases.In this review,we aim to address current progress on the antimicrobial role of phagocytic B cells in teleost fish by comparing it with other professional phagocytes and mammalian B-1 B cells,and provide the application prospect of phagocytic B cells in developing vaccines as well as the prevention of fish diseases.

Purinergic signaling systems across comparative models of spinal cord injury

Within the last several decades,the scientific community has made substantial progress in elucidating the complex pathophysiology underlying spinal cord injury.However,despite the many advances using conventional mammalian models,both cellular and axonal regeneration following spinal cord injury have remained out of reach.In this sense,turning to non-mammalian,regenerative species presents a unique opportunity to identify pro-regenerative cues and characterize a spinal cord microenvironment permissive to re-growth.Among the signaling pathways hypothesized to be dysregulated during spinal cord injury is the purinergic signaling system.In addition to its well-known role as energy currency in cells,ATP and its metabolites are small molecule neurotransmitters that mediate many diverse cellular processes within the central nervous system.While our understanding of the roles of the purinergic system following spinal cord injury is limited,this signaling pathway has been implicated in all injury-induced secondary processes,including cellular death,inflammation,reactive gliosis,and neural regeneration.Given that the purinergic system is also evolutionarily conserved between mammalian and non-mammalian species,comparisons of these roles may provide important insights into conditions responsible for recovery success.Here,we compare the secondary processes between key model species and the influence of purinergic signaling in each context.As our understanding of this signaling system and pro-regenerative conditions continues to evolve,so does the potential for the development of novel therapeutic interventions for spinal cord injury.

Advances in chemokines of teleost fish species

In mammals,chemokines are a superfamily of cytokines that regulate cell migration or exert direct antimicrobial activity.The presence and organization of four invariant cysteine residues within the mature protein sequence can classify chemokines into four major subfamilies:CXC,CC,CX_(3)C,and XC.In teleost,a novel subfamily of chemokines named CX has been identified.Since the first report of a CC chemokine(CK1)in rainbow trout in 1998,the number of identified chemokine genes in different fish species has expanded dramatically.In this paper,we reviewed the chemokine genes that have been identified so far in teleost fish and their tissue expressions and responses post-stimulation.We also discussed the functions of fish chemokines based on currently available information and compared them to human chemokines.Additionally,we predicted the structures of trout chemokines for the first time,and we found that the structures of trout chemokines share significant similarities.Finally,the adjuvant effects of fish chemokines in aquaculture were also reviewed.Overall,this review will give us a better understanding of the chemokines of teleost fish.

Slc43a2^(+)T cell metastasis from spleen to brain in RGNNV infected teleost

The origin of T cells in the teleost's brain is unclear.While viewing the central nervous system(CNS)as immune privileged has been widely accepted,previous studies suggest that T cells residing in the thymus but not in the spleen of the teleost play an essential role in communicating with the peripheral organs.Here,we identified nine T cell subpopulations in the thymus and spleen of orange-spotted grouper(Epinephelus coioices)through single-cell RNA-sequencing analysis.After viral CNS infection with red-spotted grouper nervous necrosis virus(RGNNV),the number of slc43a2^(+)T cells synchronously increased in the spleen and brain.During the infection tests in asplenic zebrafish(tlx1^▲zebrafish model),no increase in the number of slc43a2^(+)T cells was observed in the brain.Single-cell transcriptomic analysis indicated that slc43a2^(+)T cells mature and functionally differentiate within the spleen and then migrate into the brain to trigger an immune response.This study suggests a novel route for T cell migration from the spleen to the brain during viral infection in fish.

低等真骨鱼类肌间骨的比较分析

对骨舌鱼总目、海鲢总目、鲱形总目和骨鳔总目等低等真骨鱼类肌间骨的数量、形态和分布进行了比较分析，结果如下：1．海鳗肌间骨的数目最多（409枚），其次是刀鲚（221枚），黄颡鱼肌间骨数最少（8枚），双须骨舌鱼次之（70枚），鲤科鱼类的肌间骨数目在99～133之间。2．从骨舌鱼总目到骨鳔总目，各种肌间骨可归纳为7种形态类型，从简单形态向复杂形态演化，然后出现退化现象。双须骨舌鱼只有形态最简单的“I”形髓弓小骨，没有脉弓小骨；海鲢总目的海鳗出现一端两分叉的形态，而鲱形总目的鲥和刀鲚出现一端多分叉的形态，到骨鳔总目的各种鱼类，开始出现两端两分叉，并在此基础上出现各种更复杂的形态；肌间骨形态在鲤科的鲒亚科最复杂，从雅罗鱼亚科开始退化，到鲇形目髓弓小骨完全消失，而脉弓小骨仅留少数简单的I形；脉弓小骨形态的复杂性要比髓弓小骨低。3．从前向后，髓弓小骨形态依照从复杂到简单的顺序排列，而脉弓小骨没有这种明显的排列顺序。根据低等真骨鱼类的系统发育关系，结合肌间骨形态及其在各肌间隔的分布规律，本文认为，目前鲤科鱼类的各种肌间骨是通过两个途径演化而来的：从“I”形-“卜”形-“Y”形-一端多叉形和从“I”形-“卜”形-“Y”形-两端两分叉形-两端多叉形-树枝形。

南海常见硬骨鱼类COⅠ条码序列

运用一对特异性引物扩增并测定了南海硬骨鱼类40个物种89个样本的线粒体DNA的细胞色素c氧化酶Ⅰ(COⅠ)约660bp的部分序列,即COⅠ条码序列。综合比较了《中国鱼类系统检索》、《海洋鱼类志》、FishBase鱼类形态学分类库、ITIS综合分类学信息系统和生物条码系统(The Barcode of Life Data System,BOLD)的相应形态学与DNA序列资料,在揭示完善我国鱼类检索系统必要性基础上,探讨了COⅠ条码序列在硬骨鱼类辅助物种鉴别和适用性,并对运用该条码序列库完善我国鱼类检索系统的可能途径进行了初步摸索。结果表明,COⅠ条码序列获取便捷,广泛适用硬骨鱼类物种鉴别,并可用于低级分类阶元的系统进化分析。本研究结果可为分子生物学辅助分类、市场监督、资源有序利用和保护提供参考。

硬骨鱼类渗透压的内分泌激素调节机制

在400多科20 000多种海淡水硬骨鱼类中,有些鱼类只能生活在淡水或海水中,有些鱼类则能自由出入海淡水。这些鱼类能够在盐度变化很大的环境中生存主要依靠鳃等渗透调节器官对盐分的调节。鱼类的鳃上皮组织绝大部分为扁平细胞,但具有离子调节功能的细胞却是那些为数不多的氯细胞。