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C Falugi

Publications and source records attributed to C Falugi.

At least 37 records · Page 2Linked to original sources
PubMed1995

Localisation of two classes of acetylcholine receptor-like molecules in sperms of different animal species.

The distribution of different classes of acetylcholine (ACh) receptor-like molecules in sperms of different invertebrate and vertebrate species is described. ACh receptor molecules belong to one of two classes: muscarinic receptors (mAChRs), associated with signal transduction mechanisms in the inner domain of the cell, and nicotinic receptors (nAChRs), capable of opening Na+ channels when activated by the ligand. Molecules immunologically related to mAChRs and to ACh can be identified by specific antibodies, and revealed by immunofluorescent or immunogold staining; the nicotinic receptor-like molecules are localised as curare-sensitive affinity sites for alpha-bungarotoxin. In all species studied, both classes of receptors were found, with a similar distribution. Muscarinic-like molecules were found mainly in the sperm head regions of most species; such a localisation may be correlated to a function in sperm-egg interaction, for instance in the regulation of the block to polyspermy. Nicotinic-like molecules are present mainly in the tail and in the post-acrosomal region of most animals, thus confirming their function in the regulation of sperm propulsion, but are also present at the acrosomal region of most species. The distribution patterns of the different classes of molecules indicate that both may be involved in sperm-egg interactions, in addition to their known function in the regulation of sperm propulsion.

Acrosome↗
PubMed1994

Cholinesterase activity in sea urchin early embryos may be correlated to the intracellular ion content.

The possible correlation between cholinesterase (ChE) activity and ion channels antagonist drug effects was studied in sea urchin early development, showing that ChE activity is different when cation channels are affected: generally, drugs maintaining channels in the open state, such as nicotine, cause an increased ChE activity, while antagonist drugs to receptors (such as curare, butx, ttx), cause a decreased activity, showing a direct effect of membrane depolarization on the enzymic activity, also in these non-neuromuscular stages.

Animals↗
PubMed1993

The ionophore ETH 129 as Ca2+ translocator in artificial and natural membranes.

We have investigated the ability of the neutral ionophore ETH 129 to translocate Ca2+ across artificial and biological membranes. ETH 129 induces Ca2+ transport across planar lipid bilayer. The zero-current membrane potential in a gradient of Ca2+ concentration exhibits Nernst behavior. The dependence of the membrane conductance on ionophore and Ca2+ concentration indicates that three ionophore molecules are needed to transfer one Ca2+ across the hydrophobic region of the membrane. In mitochondria the neutral Ca2+ ionophore can move Ca2+ inside in response to a negative membrane potential under conditions in which the endogenous uniporter is blocked by ruthenium red. This electrophoretic transport of Ca2+ by ETH 129 occurs at a concentration much lower than the one previously reported with the neutral Ca2+ ionophore ETH 1001. Using sea urchin eggs, we have also shown that the efficiency of ETH 129 in inducing egg activation, as revealed by cortical granules exocytosis, is four orders of magnitude higher than that of the commonly used Ca2+ ionophore A21387. ETH 129 is a very efficient and useful tool for use in the investigation of Ca(2+)-dependent biological processes.

Animals↗
PubMed1993

Localization and possible role of molecules associated with the cholinergic system during "non-nervous" developmental events.

Data on the non-nervous location of cholinergic molecules are reviewed to give a general indication of their possible functions. Cholinergic or immunologically related molecules were detected and localized mainly in three classes of differentiative events supported by intracellular ion concentration changes. I: during gamete maturation, activation and interaction; II: during the early development of invertebrate and vertebrate embryos. In this case cholinergic molecules are located mainly in moving cells and tissues engaged in relevant morphogenetic events, such as gastrulation and limb bud differentiation, and are often codistributed with special extracellular matrix molecules (fibronectin); III: during inductive communications between mesenchyme and other tissues. The cholinergic system thus seems to be a multifunctional cell communication system. It appeared early during evolution as a regulator of intercellular communications mediated by ion dynamics, before becoming involved in highly specialized communication structures, such as synapses and nerve endings.

Animals↗
PubMed1992

Developmental regulation of lectin-binding patterns in Paracentrotus lividus gonads, gametes, and early embryos.

By use of several lectins (ConA, WGA, SBA, GS I, PNA), a study was carried on gametes and developing embryos of the sea urchin Paracentrotus lividus, to investigate developmental changes in cell surface, leading to changements in cell-environment interactions. ConA, WGA, and SBA, with high affinity, bind to the vitelline membrane of unfertilized eggs, while PNA labelling at the same site is weak; GS I-binding is only present in the cytoplasm and cortical region of the unfertilized eggs. Immediately after fertilization, no ConA-binding is present in the membrane, while WGA- and SBA-binding molecules are located in the fertilization layer. In zygotes, 40 min after fertilization, ConA affinity sites were again present in both cytoplasm and cortical region. During cleavages and gastrulation, ConA binds to the blastomere cytoplasm and cortical region, to the intercellular matrix, and to the cytoplasm of mesenchyme cells. WGA binds to the cortical region of cleaving blastomeres, including the hyaline layer, up to the unhatched blastula. Then it labels the gastrula inner and outer surfaces. SBA binds to the blastomere membranes; no GS I- and PNA-binding was detected during embryonic development. Sperms are bound by all the lectins, except GS I. Mannose and glucose conjugates are the most represented throughout the whole development of P. lividus, and their origin and locations are developmentally regulated. Galacto-residues are scarcely represented or are masked by other terminal sugars (e.g. sialic acid), and become functional during particular developmental events (cell movements).

Animals↗
PubMed1992

Effects of cholinergic drugs on cell interactions during fertilization and early development of the sea urchin Paracentrotus lividus.

In the present work we tested the effects of cholinergic drugs on the early development of P. lividus. Fertilization was performed in the presence of cholinergic drugs, and the embryos were fixed after 2 hours, when the controls (untreated) completed the second segmentation cleavage. We identified four classes of stages in the development of the embryos affected by the drugs, i.e.: unhatched zygotes, first cleaved stage, second cleaved stage (= unaffected), and anomalous embryos. Statistical analysis indicated that that drugs with analogous action mechanism caused similar alterations in the distribution of the treated embryos in these four classes. This finding supports the hypothesis of the presence of a complete "pre-nervous" cholinergic system, with a true cholinergic role. It is tempting to speculate that this system is involved in the first cell to cell interactions during early segmentation and possibly in the block to polyspermy.

Acetylcholine↗
PubMed1989

Effects of acetylcholinesterase specific inhibitors on the development of chick embryos.

The effects of specific inhibitors of cholinesterases on chick development were studied. Inhibitors were injected into the eggs, at final concentration ranging between 1 mM and 10 nM. Their effects were depending on inhibitor concentration, and detectable at stages as more advanced as more diluted were the inhibitors. The strongest teratogenic effects on gastrulation, neurulation and morphogenesis were caused by BW 284c51, specific inhibitor of acetylcholinesterase. Its effects were compared to those of ion channels blockers. The inhibitors action seems to be correlated to an altered cholinergic system and to consequently altered intercellular communications.

Animals↗
PubMed1989

Localization of putative nicotinic cholinoreceptors in the early development of Paracentrotus lividus.

Experiments are described, showing the presence of putative nicotinic cholinoreceptors in the egg after fertilization. The experiments were carried out on gametes and early embryos of the sea urchin Paracentrotus lividus, by using nicotinic agonists and antagonists. 1 mM Acetylcholine (ACh), 100 microM nicotine, 100 nM alpha-bungarotoxin (alpha-BuTx) and 100 microM curare inhibit sperm motility and fertilization, while they have no effect on unfertilized eggs. The drugs added within 1 min. after the raising of the fertilization layer had stronger effects on cleavage and development; when added more than 15 min. after the raising of the fertilization layer, they had lesser effects on further development up to pluteus stage. In all the experiments, nicotine was the most effective drug. The binding of fluorescein-labelled alpha-BuTx did not point out any affinity sites on unfertilized eggs, while they were localized on the sperms and on the eggs fertilized by sperms, but not on the eggs activated artificially. The binding was prevented by pretreatment of sperms and activated eggs with 10 nM native alpha-BuTx and 10 microM curare. We conclude that, in the fertilized egg, putative nicotinic cholinoreceptors are present, which are able to bind alpha-BuTx and curare. Fertilization by sperms is needed to trigger the formation of alpha-BuTx receptors.

Animals↗
PubMed1989

Effects of alpha-latrotoxin on the early developmental events of the sea urchin Paracentrotus lividus: a histochemical study.

The effects of the spider toxin alpha-latrotoxin (alpha-LTX) on gametes, zygotes, and early embryos of the sea urchin Paracentrotus lividus have been investigated by in vivo experiments and by histochemical studies of acetylcholinesterase (AChE) activity. Treatment of unfertilized eggs with nanomolar amounts (1 to 0.3 nmol/l) of alpha-LTX neither triggered cortical granule exocytosis, nor prevented the elevation of the fertilization layer by sperms. Instead, fertilized eggs exposed to alpha-LTX showed noticeable alterations in cell surface topography, including the appearance of prominent membrane-limited blebs. Moreover, the zygotes treated with 1 nmol/l alpha-LTX failed to cleave. The histochemical staining of treated zygotes revealed a very strong AChE activity in the cortical region, including blebs. An enzyme reaction was also found in the perivitellin space. Our results suggest the hypothesis that some alpha-LTX receptors may appear after fertilization, supporting the awareness that fertilized eggs display excitable cell features.

Acetylcholinesterase↗
PubMed1987

Effects of low-intensity pulsed electromagnetic fields on the early development of sea urchins.

The effects of weak electromagnetic signals on the early development of the sea urchin Paracentrotus lividus have been studied. The duration and repetition of the pulses were similar to those used for bone healing in clinical practice. A sequence of pulses, applied for a time ranging from 2 to 4 h, accelerates the cleavages of sea urchin embryo cells. This effect can be quantitatively assessed by determining the time shifts induced by the applied electromagnetic field on the completion of the first and second cleavages in a population of fertilized eggs. The exposed embryos were allowed to develop up to the pluteus stage, showing no abnormalities.

Animals↗
PubMed1986

Acetylcholinesterase in normal and malignant human cells.

Acetylcholinesterase (AChE) activity was determined in normal and malignant human cell lines by histochemical methods. In normal human fibroblasts, no AChE activity could be demonstrated by any histochemical technique or substrate. Enzymic activity was observed in HT-1080 human fibrosarcoma cells, RD 2 human rhabdomyosarcoma cells, and SW 311 human colon carcinoma cells. Activity was localized around the nuclear envelope, in the cytoplasm and associated with the cortical region of most cells. The specificity of the reaction was shown through the use of specific cholinesterase inhibitors.

Acetylcholinesterase↗
PubMed1985

Histochemical localization of acetylcholinesterase in blood cells.

Cholinesterase activity was detected by histochemical methods in normal human blood smears. In erythrocytes, acetylcholinesterase was found to be localized in the cortical region of the cells and, to a lesser degree, in the inner cytoplasm. In leucocytes, cholinesterase activity was found around the nuclear membrane and in the cytoplasm. The specificity of the enzymic activity was ascertained by using selective inhibitors.

Acetylcholinesterase↗
PubMed1985

Acetylcholinesterase (AChE) and pseudocholinesterase (BuChE) activity distribution pattern in early developing chick limbs.

The distribution of acetylcholinesterase (AChE) and pseudocholinesterase (BuChE) activities was studied by histochemical, quantitative and electrophoretical methods during the early development of chick limbs, from stage 16 to stage 32 H.H. (Hamburger & Hamilton, 1951). By quantitative methods, true AChE activity was found, and increased about threefold during the developmental period, together with a smaller amount of BuChE which increased more rapidly in comparison with the AChE activity from stage 25 to 32 H.H. Cholinesterase activity was histochemically localized mainly in interacting tissues, such as the ectoderm (including the apical ectodermal ridge) and the underlying mesenchyme. True AChE was histochemically localized around the nuclei and on the plasma membrane of ectodermal (including AER) and mesenchymal cells, and at the plasma membrane of mesenchymal cell processes reaching the basal lamina between the ectoderm and the mesenchyme. AChE together with BuChE activity was found in the basal lamina between the ectoderm and the mesenchyme, in underlying mesenchymal cells and in deeper mesenchymal cells, especially during their transformation into unexpressed chondrocytes. During limb morphogenesis, the cellular and regional localization of the enzyme activities showed variations depending on the stage of development and on the occurrence of interactions. The possibility of morphogenetic functions of the enzyme id discussed.

Acetylcholinesterase↗
PubMed1984

[Localization of embryonal acetylcholinesterase during the early development of the chick embryo].

The presence of "embryonic" acetylcholinesterase activity, as described by Drews (1975) was investigated during early chick embryonic development, mainly in the following systems: a) primitive streak and Hensen's node during gastrulation movements; b) area opaca during blood islets and vessels differentiation; c) mesoderma of lateral laminae, during delamination movements. The demonstration of enzymic activity was performed with slightly modified histochemical methods. The enzyme was thus localized around the nuclei, in the cytoplasm and associated to plasma membrane of cells engaged in morphogenetic movements. The enzyme activity localized at the plasma membrane was supposed to be involved in the regulation of membrane functions concerning intercellular communications, such as inductive message, perhaps mediated by ion fluxes.

Acetylcholinesterase↗
PubMed1984

[Histochemistry and ultrastructure of gastric glandular cells of the Raja asterias delaroche (Elasmobranchi)].

The presence of different kinds of cells in the gastric tubular glands of the Elasmobranchian Cartilaginous fish "Raja asterias" was investigated by histochemical and ultrastructural methods. Our study demonstrates that the gastric glands, unlike those of the other non-Mammalian Vertebrates, contain in the distal portion, near the neck zone, the oxyntic-like cells, and in the proximal portion the zymogenic-like cells. The former presents histochemical and ultrastructural patterns similar to the Mammalian oxyntic cells, the latter to the Mammalian peptic cells. Between these two types there are always cells with intermediate aspects. These features support the presence of two different stages in the secretory activity: at first the gastric tubular cell is implicated in the secretion of hydrochloric acid, later on, in the secretion of pepsinogen.

Animals↗