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PubMed2004

The genes for the helix-loop-helix proteins Id6a, Id6b, Id1 and Id2 are specifically expressed in the ventral and dorsal domains of the fish developing somites.

Muscle differentiation is inhibited by members of the Id family that block the transcriptional effect of myogenic bHLH regulators by forming inactive heterodimers with them. Also, Id proteins promote cell proliferation by interacting with key regulators of the cell cycle. In order to determine the role of Id-encoding genes during fish development and especially in early myogenesis, we examined the expression patterns of Id1, Id2 and two nonallelic Id6 (Id6a and Id6b)-encoding genes in developing trout embryos. These four Id paralogs were found to exhibit discrete expression in the developing nervous system and in the eye rudiment. During the segmentation process, Id6a, Id6b and Id1 were expressed in the tail bud, the paraxial mesoderm and the ventral and dorsal domains of neoformed somites. As the somite matured in a rostrocaudal progression, the labelling for Id1 transcripts rapidly faded whereas labelling for Id6 transcripts was found to persist until at least the completion of segmentation. By contrast, Id2 transcripts were visualised transiently only in dorsal domains of neoformed somites and strongly accumulated in the pronephros. The preferential localisation of Id6a, Id6b, Id1 and Id2 transcripts within ventral and/or dorsal extremes of the developing somites, suggests that these areas, which were the last ones to express muscle-specific genes, contain dividing cells involved in somite expansion.

Amino Acid Sequence↗
PubMed2002

cDNA cloning and expressions of cytochrome P450 1A in zebrafish embryos.

Cytochrome P450 1A (CYP1A) is well known for being induced by aromatic hydrocarbons, including 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD). We determined the complete cDNA sequence of a CYP1A open reading frame with both 5'- and 3'-ends in zebrafish (zfCYP1A), a useful model for environmental toxicology. zfCYP1A shows high percentage identity with CYP1As of mammals, domestic fowl and xenopus (51.9-60.4%), as well as the other fish species (63.8-89.2%). As revealed by in situ hybridization and immunohistochemistry, zfCYP1A was scarcely detected in control embryos but was markedly induced by TCDD especially in heart, vascular endothelial cells, intestinal epithelium, pronephros and outer integument in both prehatched and hatched embryos. These expression patterns are consistent with possible involvement of zfCYP1A in TCDD-induced toxicities.

Amino Acid Sequence↗
PubMed2005

Developmental expression of Pod 1 in Xenopus laevis.

The basic helix-loop-helix transcription factor, Pod 1, has been shown to be expressed in the mesenchyme of many developing mouse organs, including the heart, lungs and gut. In the kidneys of developing mice, Pod 1 is highly expressed in the condensing metanephric mesenchyme, differentiating and late stromal cells and in developing podocytes. We have obtained an EST (CF270487) which contains the Xenopus laevis Pod 1 sequence. Conceptual translation of the Xenopus laevis Pod 1 sequence shows approximately 85% similarity to other vertebrate homologues. RT-PCR indicates that expression is initiated at stage 13 and increases differentially in the developing pronephros compared to the whole embryo. RT-PCR of a kidney dissection at stage 42 shows higher expression in the glomus than in the tubule or duct. In situ hybridisation analysis at tail bud stages shows the anterior-most branchial arch and pronephric glomus are intensely stained. At stage 40, staining persists in the glomus and in the epicardium region of the heart. Adult organ analysis shows expression is highest in the rectum and the spleen, with significant expression in the duodenum, heart, kidney, lungs, pancreas, skin, liver and muscle.

Amino Acid Sequence↗
PubMed2000

[Terrestrial adaptation and diversity of the kidney functions in the evolution of vertebrates, Amphibia].

The Amphibia bridge the phyletic gap between the aquatic fishes and the terrestrial vertebrates. This transition has involved many interesting changes of metabolisms. In this short review, we have attempted to summarize the kidney structure and functions on the osmoregulations in the Amphibia. Amphibians excrete the water absorbed through their skin as a dilute urine. Pronephros of tadpoles may start to work in the hatching stages and metanephros is well developed and functions. Glomerular filtration rate is relatively large and glomerular intermittency is important to regulate urine production. The proximal tubule reabsorbs approximately 20-45% of filtered water and sodium. Absorption is driven by the basolateral Na+, K(+)-ATPase common to all tubular cells. The diluting segment, early parts of distal nephron, highly develops basolateral interdigitation and reabsorbs approximately 40% of filtered Na+, K+, and Cl-, but is impermeable to water, thus this part results in the formation of hypo-osmotic tubular fluid. In the late distal tubule, the primary mechanism of reabsorption may be via a luminal NaCl synporter, driven by the ubiquitous Na+, K(+)-ATPase on basolateral membrane. In collecting tubule, there are two types of cells, the principal cells and the intercalated cells. Many hormonal and nervous regulations are involved in the glomerular filtration rate and reabsorptions in the amphibian nephrons.

Adaptation, Biological↗
PubMed1996

Immunotoxic effects of copper and cadmium in the sea bass Dicentrarchus labrax.

Two phagocytes-mediated activities of the sea bass Dicentrarchus labrax were examined after exposure to sublethal concentrations of copper and cadmium: (a) phagocytosis (measured by phagocytotic index), and (b) the production of reactive oxygen intermediates (luminol-dependent chemiluminescence) in response to bacteria Aeromonas salmonicida. In vivo exposure for 48 h to each metal separately by intraperitoneal injection did not affect the quantity of phagocytes of pronephros and their viability but inhibited, in dose-dependent manner, phagocytosis and chemiluminescence of these cells. The half-inhibition value was 250 micrograms kg-1 for copper and 1 mg kg-1 for cadmium. In vitro exposure to copper for 30 min had the same immunomodulatory effect on macrophage chemiluminescence as that observed in vivo, whereas treatment with cadmium under the same conditions had a dose-dependent effect opposite to that observed in vivo. Assessment of these two macrophage-mediated functions could therefore be used as early bioindicators of the marine pollution.

Animals↗
PubMed1999

Rainbow trout leucocyte activity: influence on the ectoparasitic monogenean Gyrodactylus derjavini.

The ectoparasitic monogenean Gyrodactylus derjavini from rainbow trout Oncorhynchus mykiss was exposed in vitro to macrophages isolated as peritoneal exudate cells or as pronephros cells from the host. Cells colonized the parasite especially in the mannose-rich regions in the cephalic ducts where ciliated structures were abundant. Opsonization with fresh serum, in contrast to heat-inactivated serum, enhanced colonization also on other body parts. The adverse effect of the activated macrophages towards G. derjavini was associated with a heat-labile component released from these cells to the culture medium. Analysis of substances released from the cells showed reactivity for a number of enzymes, complement factor C3, interleukin (Il-1) and reactive oxygen metabolites. Chemotaxis assays with pronephric leucocytes showed chemoattractants in G. derjavini, and the respiratory burst level of macrophages was slightly elevated due to parasite exposure. It is suggested that skin leucocytes contribute to an increased level of complement factors in the trout skin during the host response, whereby a hostile microenvironment for the parasites is created. In addition, the IL-1 production could affect mucous cell secretion and hyperplasia and add to the antiparasitic action of the epithelium. Likewise, reactive oxygen metabolites and various enzymes are likely to be involved in the skin response.

Animals↗
PubMed1999

Comparative severity of experimentally induced mycobacteriosis in striped bass Morone saxatilis and hybrid tilapia Oreochromis spp.

Twenty striped bass Morone saxatilis and 20 hybrid tilapia Oreochromis niloticus x O. mossambicus x O. aureus each received a single intramuscular injection of 1.6 x 10(6) colony forming units per gram body weight of Mycobacterium marinum. Striped bass manifested significantly greater clinical and microscopic disease compared to tilapia. Whereas all the striped bass had died or were clinically ill by Day 8 post-infection, there was no apparent disruption of normal behaviour, physical appearance, or growth in any of the sacrificed or surviving tilapia. Histologically, granulomas in striped bass were generally larger and less discrete, with a higher proportion of heavily vacuolated macrophages, and large cores of necrotic cells. Visceral granulomas in tilapia were smaller, with a higher proportion of epithelioid macrophages, more pigment-containing cells, more peripheral lymphocytes, and virtually no central necrosis. Visceral granulomas were 18-fold more numerous in striped bass than in tilapia. Based upon histomorphometric data, mean proportions of acid-fast bacteria within pronephros granulomas were 4-fold greater in striped bass than tilapia, and striped bass granulomas averaged more than twice as large as tilapia granulomas. In the anterior kidney of striped bass, a positive correlation existed between mean mycobacterial proportions and mean necrosis scores. In tilapia, mean mycobacterial proportions correlated negatively with mean granuloma numbers, whereas there was no correlation between these parameters in striped bass. Results suggest that intrinsic functional differences in the immunologic systems of striped bass and hybrid tilapia may contribute to inter-species variation in mycobacteriosis susceptibility.

Animals↗
PubMed2004

Effect of hexavalent carcinogenic chromium on carp Cyprinus carpio immune cells.

Chromium is widely used in industrial processes, and is released into aquatic environments by electroplating, tannery and textile industries. Fishes in natural waters or in aquaculture facilities supplied with these waters are exposed to chromium waste and are presumed to be affected by deposits. Herein, we examine the effect of hexavalent chromium on carp Cyprinus carpio derived immune cells. In vitro exposure of carp leukocytes to hexavalent chromium induced cytotoxicity, decreased mitogen-induced lymphocyte activation and phagocyte functions at concentrations between 2 and 200 micromol Cr l(-1). Neutrophils responded to chromium challenge by changes in cell shape together with reduced nitric oxide and reactive oxygen production. This occurred at much lower concentrations than for the cytotoxic effects seen in leukocyte cultures derived from peripheral blood or pronephros. In a similar way, activation of carp lymphocytes by pokeweed mitogen was reduced in a dose-dependent manner, while cytotoxic effects on non-activated lymphocytes were observed at much higher doses of 200 micromol Cr l(-1). Altered lymphocyte and neutrophil functions are considered to be responsible for decreased resistance to pathogens observed in fishes under chronic chromium challenge.

Analysis of Variance↗
PubMed2006

Phenotypic and functional similarity of gut intraepithelial and systemic T cells in a teleost fish.

Gut-associated lymphocytes were described in fish, but their involvement in immune responses is still unknown. In rainbow trout, intraepithelial lymphocytes (IELs) are scattered between gut epithelial cells, but neither Peyer's patches nor mesenteric lymph nodes were identified. Rainbow trout IELs contain mainly T cells, because they expressed transcripts of T cell marker homologs of CD8, CD4, CD28, CD3epsilon, TCRzeta, TCRgamma, and TCRbeta and lacked IgM. However, trout IELs did not show specific homing to the gut mucosa, which in mammals defines IELs as a distinctive mucosal population. A detailed analysis of the TCRbeta repertoire of rainbow trout IELs was performed in both naive and virus-infected animals. TCRbeta transcripts of rainbow trout IELs were highly diverse and polyclonal in adult naive individuals, in sharp contrast with the restricted diversity of IEL oligoclonal repertoires described in birds and mammals. Significant modifications of the trout IEL TCRbeta repertoire were observed after a systemic infection with a fish rhabdovirus and were especially marked for Vbeta4-bearing receptors as previously reported for spleen cells. Thus, we could not find any specific properties of the trout IEL TCRbeta repertoire compared with the spleen and pronephros TCRbeta repertoire, which questions the reality of a distinct IEL compartment in teleosts. Our findings suggest that a highly diversified alphabeta TauCR repertoire is maintained in fish IELs in the absence of Peyer's patches and mesenteric lymph nodes, whereas the restricted diversity of mouse alphabeta IELs is attributed to multiple cycles of activation and recirculation, allowing a progressive narrowing of the repertoire.

Animals↗
PubMed2006

An amphioxus LIM-homeobox gene, AmphiLim1/5, expressed early in the invaginating organizer region and later in differentiating cells of the kidney and central nervous system.

A LIM-homeobox gene, AmphiLim1/5, from the Florida amphioxus (Branchiostoma floridae) encodes a protein that phylogenetic analysis positions at the base of a clade comprising vertebrate Lim1 and Lim5. Amphioxus AmphiLim1/5 is expressed in domains that are a composite of those of vertebrate Lim1 and Lim5, which evidently underwent subfunctionalization after duplication of an ancestral protochordate Lim1/5. During amphioxus development, transcription is first detected in the ectoderm of the blastula. Then, in the gastrula, a second expression domain appears in the mesendoderm just within the dorsal lip of the blastopore, a region known to have organizer properties in amphioxus. This mesendodermal expression corresponds to Lim1 expression in the Spemann organizer of vertebrates. At least one of the functions of vertebrate Lim1 in the organizer is to control the transcription of genes involved in cell and tissue movements during gastrulation, and a comparable early function seems likely for AmphiLim1/5 during gastrular invagination of amphioxus. Later embryos and larvae of amphioxus express AmphiLim1/5 in clusters of cells, probably motoneurons, in the anterior part of the central nervous system, in the hindgut, in Hatschek's right diverticulum (a rudiment of the rostral coelom), and in the wall of the first somite on the left side (a precursor of Hatschek's nephridium). In the early larva, expression continues in neural cells, in Hatschek's nephridium, in the wall of the rostral coelom, in the epidermis of the upper lip, and in mesoderm cells near the opening of the second gill slit. The developmental expression in Hatschek's nephridium is especially interesting because it helps support the homology between this amphioxus organ and the vertebrate pronephros.

Amino Acid Sequence↗
PubMed1999

Expression of the Xenopus laevis metallothionein gene during ontogeny.

Expression of the Xenopus laevis metallothionein (MT) gene was studied by in situ hybridization throughout development. MT mRNA was detected from the tailbud stage onwards. MT expression was observed in bucco-pharyngeal epithelium, pronephros and liver anlagen, aswell as in lens and periventricular areas of the encephalon. MT transcripts, in both larvae and adults, were detected in diverse regions of the central nervous system and in differentiating tissues implicated in detoxification processes: liver hepatocytes, small intestine epithelia and kidney tubules. These data are discussed in the context of MT functions and support a physiological role for MT in growth processes.

Animals↗
PubMed2001

In vitro induction systems for analyses of amphibian organogenesis and body patterning.

The discovery that some well-known growth factors have inducing activity in embryogenesis has accelerated our understanding of embryonic induction. Relevant receptors, signal transduction pathways and patterns of gene expression have been characterized over the past decade. Amphibian embryos have provided an excellent model for analysis of embryonic induction because they are easily surgically manipulated and cultured in vitro, and with the addition of treatment with various inducing factors we have been able to control organogenesis and body patterning during early development in vitro. Activin A, a TGF-beta family protein, has a potent mesoderm-inducing activity on the isolated ectoderm called the animal cap. Activin induces animal caps to differentiate into various mesodermal and endodermal tissues, including beating hearts, in a dose-dependent fashion. Activin, in combination with retinoic acid, also induces the formation of the pronephros, a primitive embryonic kidney. The in vitro induced kidney was confirmed to function in vivo in a transplantation experiment. Furthermore, the activin-induced animal caps organize heads or trunk-and-tails in exactly the same manner as the organizer. The potential use of in vitro induction systems to further our understanding of vertebrate organogenesis and body patterning will be discussed.

Activins↗
PubMed2001

Isolation and characterization of a Xenopus gene (XMLP) encoding a MARCKS-like protein.

We have identified a cDNA coding for a Xenopus MARCKS-like protein (XMLP) from a cDNA library prepared from activin-treated ectoderm. Using whole-mount in situ hybridization and RT-PCR, we found XMLP maternal transcripts during the cleavage stages. After MBT, the signals were restricted to the neural plate. Subsequently XMLP was expressed predominantly in the brain, somites and pronephros. Ectopic expression of XMLP resulted in eye and axis defects and in a change of the expression pattern of Krox 20, a neural marker for rhombomeres 3 and 5. Injected XMLP caused apoptosis. It was characterized by loss of intercellular adhesion contacts, transient plasma membrane ruffling at gastrula, and epithelial disruption attailbud stage. Overexpression of mutant XMLPs showed that this phenotype was correlated with its putative PSD domain and glycine at position 2. The embryos injected with a morpholino oligo complementaryto XMLPmRNA showed malformations of the anterior axis and eye defects. Extirpation experiments indicated that the phenotypes might be correlated with disturbed morphorgenetic movements rather than an inhibition of induction process. Overexpression of XCYP26 resulted in a shift of the expression pattern of XMLP. In the early tailbud stage (stage 20) the signal stripe in the XCYP26 injected half of the embryo got diffuse or even disappeared. This observation suggests that retinoic acid plays an important role in the regulation of XMLP. Our results suggest that XMLP might participate in pattern formation of the embryonic axis and the central nervous system.

Amino Acid Sequence↗
PubMed2003

Isolation and growth factor inducibility of the Xenopus laevis Lmx1b gene.

This paper reports the cloning of the full length Xenopus laevis Lmx1b gene, Xlmx1b. Xlmx1b is a LIM homeodomain protein with high conservation to homologues identified in human, mouse, hamster and chick. In situ hybridisation and RT-PCR analysis showed that Xlmx1b has a specific temporal expression pattern which can be separated into three main spatial domains. An Xlmx1b probe hybridized to regions of the nervous system from stage 13 onwards; these regions included the placodes and otic vesicles, the eye and specific sets of neurons. Sectioning of in situ hybridised embryos confirmed the location of transcripts as discreet regions of staining in ventrolateral regions of the neural tube. From stage 27, transcripts could be detected in the capsule of pronephric glomus. Finally, transcripts were detected by Northern blot analysis in the developing fore and hind limbs. Xlmx1b transcripts were also detected by Northern blot analysis in eye, brain, muscle and mesonephros tissue in metamorphosing tadpoles. RT-PCR analysis showed that zygotic expression of Xlmx1b is initiated at stage 10.5 and the temporal sequence of Xlmx1b expression is identical in both neural and presumptive pronephros regions. The effects of the growth factors activin A, retinoic acid (RA) and basic fibroblast growth factor (bFGF) on the regulation of Xlmx1b were also studied. Xlmx1b was found to be upregulated by activin A and RA inhibited this upregulation in a concentration dependant manner. In contrast, bFGF had no effect on the regulation of Xlmx1b.

Activins↗
PubMed2003

Immunomodulatory activity of the dimerized lysozyme KLP-602 after earlier suppression by atrazine in carp (Cyprinus carpio L.).

The purpose of this study was to determine the possibility of modulation of the cellular immune response with the dimer of lysozyme KLP-602 in fish after suppression induced by atrazine. In the in vivo studies fish were intoxicated with atrazine at a dose of 1/4 LD50, then after 48 hours the dimer of lysozyme KLP-602 was administerd at a dose of 0.02 mg/kg of body weight. After 2, 3, 5, 7 and 10 days after intoxication cells from the blood and pronephros of carp were isolated. In the study we determined the metabolic activity of phagocyte cells and the proliferative ability of T and B lymphocytes. This study showed that administration of the dimer of lysozyme KLP-602 stimulated and corrected the handicapped immunity.

Adjuvants, Immunologic↗
PubMed2003

Characterization of a gene respondent to clinorotation in Xenopus A6 cells.

The A6 epithelial cell line, derived from the kidney of Xenopus laevis, spontaneously form domes after it has reached confluence. In a previous study, we demonstrated that formation of domes is strongly inhibited in the cells cultured using a three-dimensional clinostat. In this study, we performed staining of filamentous actin and examination using electron microscopy to investigate morphological changes of A6 cells exposured to clinorotation for 10 days. Micrographs show that A6 cells in clinorotation lose cortical actin that is characteristic of epithelial cells. Therefore, we search for genes differentially expressed in A6 cells cultured in clinorotation and identified Xenopus laevis N-myc downstream-regulated gene-1 (xNDRG1) as a clinorotation respondent gene in A6 cells. In northern blots analysis, xNDRG1 mRNA significantly increased only in A6 cells cultured in clinorotation for 10 days, and maintained at a similar level in the cells cultured for 15 days. Centrifugations of A6 cells have no effect on expression of xNDRG1. We also aimed to characterize xNDRG1 during Xenopus laevis development by examining the temporal and spatial expression patterns of xNDRG1 transcripts in embryos. Our results suggest that xNDRG1 is necessary for pronephros development in Xenopus laevis.

Animals↗
PubMed2004

The developing kidney and environmental toxins.

The effects of environmental chemicals, drugs, and physical agents on the developing kidney are influenced by the state of renal development and maturation. The development of the kidney, the major excretory organ after birth, consists of 3 stages: the pronephros, or cervical kidney; mesonephros, or thoracic kidney; and metanephros, or abdominal kidney, the definitive kidney. In humans, nephrogenesis and organogenesis occur from the 6th to the 36th weeks of gestational age. After 36 weeks, nephrogenesis is complete and each kidney has a full complement of nephrons. The extent of chemical-induced renal toxicity is related, in part, to the efficiency in which the particular compound is transported by renal tubules. Because renal tubular transport capacities vary with maturation, the degree of nephrotoxicity may also vary with maturation. The signs and symptoms of nephrotoxicity can appear acutely or insidiously. Unexplained acute renal failure, chronic mild proteinuria, or even hypertension can be a manifestation of nephrotoxic agents. Species differences occur, thus the need for studies in humans.

Animals↗
PubMedDate not supplied

Relationship between specialized cells, capillaries and intermediary cytofibrillary elements. XIth note. Biological evolution of the emunctory subsystem and stereotype in vertebrates.

This note completes in vertebrates the study of the emunctory subsystem and stereotype in invertebrates (Xth note). The theory of systems (and of open biological systems) of Bertalanffy, the theory of internal laws and limits of each organizational level (Needham) and the theory of biological stereotypes and of their morphofunctional expression (Mârza, Repciuc and Eskenasy) are also corroborated. In this light there were studied: the characters of the emunctory stereotype in vertebrates, its similar formation mode by three links (extracting, conveying and excretory links) as in the coelomatous invertebrates, and the passage of the emunctory stereotype from invertebrates to vertebrates. The present-day Acraniata and their offsprings, the Protocraniata, Agnatha and aquatic Gnathostoma, have an emunctory stereotype identical in its essential characters, without discrepancies between its links. The passage does not occur, however, from the metanephridia to the pronephros, but to the mesonephros. This latter reaches its highest functional limits in Dipnoi and Amphibia. The author indicates the mechanisms which, in its opinion, play a role in the activation of organo-genetic capacities of the metanephros in the caudal nephrogenic area. The importance of the three nephrogenic areas of the vertebrates, their succession and interdependence are also discussed. The problem of the archi(holo)nephros is critically reviewed, and the author's hypothesis that the glomerular ultrafiltrate and the coelomic liquid of invertebrates with metanephridia had the same composition and underwent the same processes of reabsorption-secretion is dwelt upon. A conclusion is drawn from these two notes, according to which stability--directed by the stabilizing selection--plays a directional role in the evolution of the new organizational levels, in the maintenance and development of the characters of the emunctory stereotype within the emunctory subsystem (EMSS). Between variability and stability strong relations are established and hereditarily transmitted.

Adaptation, Biological↗