1,720,979 research outputs found
Immune cells in the spiral intestine of Blackmouth catshark, Galeus melastomus: New insights into ancient gut defenders
No full textThis study aimed to describe the morphology and to characterize the immunohistochemistry of the gut-associated lymphoid tissue (GALT) in the spiral intestine of the Blackmouth catshark Galeus melastomus. In the catshark, the lympho-myeloid aggregate of the GALT was mainly confined to the central region of the spiral valve. A panel of eight immune molecular markers was applied to histological sections to show the cell types of the GALT using immunohistochemical and -fluorescence methods. Two main reactive cell types were identified: (i) a mast cell lineage positive to histamine, serotonin, and immunoglobulin E-like receptor antibodies, and (ii) a macrophage lineage positive to CD4, interleukin-6, lysozyme, toll-like receptor-2, and tumor necrosis factor-α antibodies. Confocal microscopy revealed which immune markers were co-localized in the same cell type. The presence of cells positive to the tested antibodies confirmed the defensive role against pathogens of the GALT in the spiral intestine of the catshark. Given the limited knowledge of the elasmobranch immune system, the current study provides new insights into the features of ancient defender cells of the spiral intestine
Mucosal Hallmarks in the Alimentary Canal of Northern Pike Esox lucius (Linnaeus)
No full textOn the basis of trophic behavior, fish are classified as herbivores, carnivores, omnivores, or detritivores. Epithelial mucous cells secrete mucin types specific to diet and digestive function. Mucus secretion is regulated mainly by molecular modulators produced by epithelial endocrine cells in response to luminal or tissue stimuli. These modulators are involved in control of food intake and digestive functions. Immunohistochemical and immunofluorescence studies were conducted on 10 adult northern pike (Esox lucius Linnaeus, 1758) from Lake Piediluco (Central Italy) to quantify distribution of sub-types of mucous and endocrine cells in alimentary mucosal epithelium. Neutral mucins predominated in the esophagus, and mixed and acidic mucins predominated in stomach and intestine. The gastric epithelium contained endocrine cells secreting somatostatin, tyrosine hydroxylase, and substance P. Mucous cells secreting neutral mucins increased in number from proximal to distal intestine, with endocrine cells containing substance P in the proximal intestine and those containing Leu-enkephalin throughout the intestine. Lectin histochemistry of gut sections revealed an abundance of N-acetyl-glucosamine and N-acetyl-galactosamine as carbohydrate residues on the mucin chain. The quantity and content of endocrine and mucous cells in the alimentary canal of E. lucius showed a direct relationship with its diet
Parasites and the neuroendocrine control of fish intestinal function: an ancient struggle between pathogens and host
No full textAbstractMost individual fish in wild and farmed populations can be infected with parasites. Fish intestines can harbour protozoans, myxozoans and helminths, which include several species of digeneans, cestodes, nematodes and acanthocephalans. Enteric parasites often induce inflammation of the intestine; the pathogen provokes changes in the host physiology, which will be genetically selected for if they benefit the parasite. The host response to intestinal parasites involves neural, endocrine and immune systems and interaction among these systems is coordinated by hormones, chemokines, cytokines and neurotransmitters including peptides. Intestinal fish parasites have effects on the components of the enteric nervous and endocrine systems; mechanical/chemical changes impair the activity of these systems, including gut motility and digestion. Investigations on the role of the neuroendocrine system in response to fish intestinal parasites are very few. This paper provides immunohistochemical and ultrastructural data on effects of parasites on the enteric nervous system and the enteric endocrine system in several fish–parasite systems. Emphasis is on the occurrence of 21 molecules including cholecystokinin-8, neuropeptide Y, enkephalins, galanin, vasoactive intestinal peptide and serotonin in infected tissues.</jats:p
Enteric neuromodulators and mucus discharge in a fish infected with the intestinal helminth Pomphorhynchus laevis
Full text linkAbstract Background In vertebrates, the presence of enteric worms can induce structural changes to the alimentary canal impacting on the neuroendocrine system, altering the proper functioning of the gastrointestinal tract and affecting the occurrence and relative density of endocrine cells (ECs). This account represents the first immunohistochemistry and ultrastructure-based study which documents the intimate relationship between the intestinal mucous cells and ECs in a fish-helminth system, investigating the potential effects of enteric neuromodulators on gut mucus secretion/discharge. Methods A modified dual immunohisto- and histochemical staining technique was applied on intestinal sections from both infected and uninfected fish. Sections were incubated in antisera to a range of neuromodulators (i.e. leu-enkephalin, met-enkephalin, galanin and serotonin) and the glycoconjugate histochemistry of the mucous cells was determined using a subsequent alcian blue – periodic acid Schiff staining step. Dual fluorescent staining on sections prepared for confocal laser scanning microscopy and transmission electron microscopy were also used to document the relationship between ECs and mucous cells. Results From a total of 26 specimens of Squalius cephalus sampled from the River Paglia, 16 (i.e. 62 %) specimens were found to harbour an infection of the acanthocephalan Pomphorhynchus laevis (average intensity of infection 9.2 ± 0.8 parasites host−1, mean ± standard error). When acanthocephalans were present, the numbers of mucous cells (most notably those containing acidic or mixed glycoconjugates) and ECs secreting leu-enkephalin, met-enkephalin, galanin, serotonin were significantly higher than those seen on sections from uninfected fish. The relationship between met-enkephalin-like or serotonin-like ECs and lectin DBA positive mucous cells was demonstrated through a dual fluorescent staining. The presence of tight connections and desmosomes between mucous and ECs in transmission electron micrographs provides further evidence of this intimate relationship. Conclusions The presence of P. laevis induces an increase in the number of enteric ECs that are immunoreactive to leu- and met-enkephalin, galanin, and serotonin anti-sera. The mucous cells hyperplasia and enhanced mucus secretion in the helminth-infected intestines could be elicited by the increase in the number of ECs which release these regulatory substances
Teleost innate immunity, an intricate game between immune cells and parasites of fish organs: who wins, who loses
No full textFish, comprising over 27,000 species, represent the oldest vertebrate group and possess both innate and adaptive immune systems. The susceptibility of most wild fish to parasitic infections and related diseases is well-established. Among all vertebrates, the digestive tract creates a remarkably favorable and nutrient-rich environment, which, in turn, renders it susceptible to microparasites and macroparasites. Consequently, metazoan parasites emerge as important disease agents, impacting both wild and farmed fish and resulting in substantial economic losses. Given their status as pathogenic organisms, these parasites warrant considerable attention. Helminths, a general term encompassing worms, constitute one of the most important groups of metazoan parasites in fish. This group includes various species of platyhelminthes (digeneans, cestodes), nematodes, and acanthocephalans. In addition, myxozoans, microscopic metazoan endoparasites, are found in water-dwelling invertebrates and vertebrate hosts. It is worth noting that several innate immune cells within the fish alimentary canal and certain visceral organs (e.g., liver, spleen, and gonads) play active roles in the immune response against parasites. These immune cells include macrophages, neutrophils, rodlet cells, and mast cells also known as eosinophilic granular cells. At the site of intestinal infection, helminths often impact mucous cells number and alter mucus composition. This paper presents an overview of the state of the art on the occurrence and characteristics of innate immune cells in the digestive tract and other visceral organs in different fish-parasite systems. The data, coming especially from studies employed immunohistochemical, histopathological, and ultrastructural analyses, provide evidence supporting the involvement of teleost innate immune cells in modulating inflammatory responses to metazoan and protozoan parasitic infections
Rodlet cells, fish immune cells and a sentinel of parasitic harm in teleost organs
No full textRodlet cells (RCs) are the enigmatic and distinctive pear-shaped cells had found in many tissues of marine and freshwater teleosts. They have a distinctive fibrous capsule or the cell cortex that envelopes conspicuous inclusions called rodlets, basally situated nucleus, and poorly developed mitochondria. The contraction of the cell cortex results in the expulsion of the cell contents through an apical opening. One hundred and thirty years since rodlet cells were first reported, many questions remain about their origin and a function. This review will present new evidence regarding the relationship between RCs and metazoan parasites, and a protozoan infecting organs of different fish species, and update the state of knowledge about the origin, structure and the function of these intriguing fish cells
The Leydig organ of elasmobranchs: Shed light on an active and mysterious defense center with immunological characterization of its cells
No full textIn elasmobranchs, blood cells originate from the thymus, spleen, and two organs associated with the gonads and esophagus: the epigonal and Leydig organs (LO), respectively. In the LO parenchyma, various granulocyte types, thrombocytes, and lymphocytes were observed, with notable species-specific diversity. Cells of the LO in the catshark Galeus melastomus were characterized using immunohistochemistry, immunofluorescence, and electron microscopy. Image analysis of sections treated with the anti-proliferative cell nuclear antigen antibody revealed that approximately 40 % of LO cells were in mitosis and approximately 15 % were myeloid progenitors positive for the anti-c-kit antibody. Additionally, a panel of 12 immunological markers revealed that 18.4 %, 17.8 %, 13.7 %, and 14.1 % of the LO section area was occupied by cells positive for anti-serotonin, interleukin-6, histamine, and immunoglobulin E-like receptor antibodies, respectively. Two main reactive cell types, mast cell and macrophage lineage, were revealed by co-localization image analysis using confocal microscopy. Ultrastructural observation identified granulocytes and macrophages as the main cell types. To our knowledge, this is the first report on the distinct patterns of LO cell populations and their morphological features, confirming granulopoietic role of the elasmobranch LO
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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