177 research outputs found
Spatiotemporal role of muscarinic signaling in early chick development: exposure to cholinomimetic agents by a mathematical model
No full textAwareness is growing that, besides several neurotoxic effects, cholinomimetic drugs able to interfere the cholinergic neurotransmitter system may exert a teratogen effect in developing embryos of vertebrate and invertebrate organisms. Cholinomimetic substances exert their toxic activity on organisms as they inhibit the functionality of the cholinergic system by completely or partially replacing the ACh molecule both at the level of the AChE active site and at the level of acetylcholine receptors. In this work, we focused the attention on the effects of muscarinic antagonist (atropine) and agonist (carbachol) drugs during the early development and ontogenesis of chick embryos. An unsteady-state mathematical model of the drug release and fate was developed, to synchronize exposure to a gradient of drug concentrations with the different developmental events. Since concentration measures in time and space cannot be taken without damaging the embryo itself, the diffusion model was the only way to establish at each time-step the exact concentration of drug at the different points of the embryo body (considered two-dimensional up to the 50 h stage). This concentration depends on the distance and position of the embryo with respect to the releasing source. The exposure to carbachol generally enhanced dimensions and stages of the embryos, while atropine mainly caused delay in development and small size of the embryos. Both the drugs were able to cause developmental anomalies, depending on the moment of development, in a time- and dose-dependent way, regardless the expression of genes driving each event
Induction of micronuclei by a new nonpeptidic mimetic farnesyltransferase inhibitor RPR-115135: role of gene mutations.
No full textTo investigate the relationship between oncogene activation and induction of micronuclei by a new non-peptidic mimetic farnesyltransferase inhibitor, RPR-115135, two isogenic cell lines, human colon cancer line HCT-116, which harbors a K-ras mutation, and spontaneously immortalized human breast epithelial cell line MCF-10A, were utilized. HCT-116 cells were transfected with an empty control pCMV vector (clone CMV-2) or with a dominant negative mutated p53 transgene (clone Mu-p53-2) to disrupt p53 function. In both clones RPR-115135 induced a significant increase in the frequency of micronucleation at concentrations that did not affect cell membrane integrity. RPR-115135 produced a significant increase in the ratio of CREST+ to CREST- micronuclei. MCF-10A cells were stably transfected with either c-Ha-ras or c-erbB-2 or both H-ras + c-erbB-2. No induction of micronuclei was observed. No induction of micronuclei was reported in human lymphocytes and in primary spinal cells obtained from 7-day chick embryos. In conclusion, RPR-115135 acts as an aneugenic agent in a complex manner, dependent upon the complement of mutations in cell regulatory genes in tumour cells and this activity may be independent of ras genotype
Cholinergic molecules and sperm functions
No full textMolecules acting on neurotransmitter systems are known to be present in sperms of several species: their presence was correlated to the regulation of sperm propulsion. To understand their function, a study was carried out on sperm activation, in the presence of cholinergic drugs (acetylcholine and drugs competitive at cholinergic receptors, agonist and antagonist, both muscarinic and nicotinic ones). The in vivo effects were also studied by demonstrating membrane depolarization with merocyanine, a potentiometric dye. Concentrated acetylcholine, up to 100 muM, inhibited both activation and membrane depolarization, while diluted to 10 muM, ACh enhanced it. The competitive drugs exerted on activation more or less the same effects as those on movement, reported in literature. 100 muM atropine reversibly prevented activation, while, more diluted, only delayed it. 1 muM nicotine and carbachol enhanced, and curare delayed activation and merocyanine staining. The results show the possibility that both nicotinic and muscarinic AChRs are involved in the mechanism of sperm activation. Further, the possibility that an ACh-like substance concentrated in the sperm liquid may be involved in maintaining the sperms in the quiescent state is discussed
Benthic assemblages and temperature effects on Paracentrotus lividus and Arbacia lixula larvae and settlement
No full textRecruitment is a principal controlling factor in population dynamics of marine species. In marine
invertebrates with a planktonic larval stage, such as echinoids, recruitment is assured by larval supply,
settlement and juvenile survival. Larval supply and juvenile survival are affected by a wide range of factors,
including temperature, presence of predators, quality and quantity of food. Echinoid larval settlement is
mainly conditioned by the finding of a suitable substrate to metamorphose. The sea urchins Arbacia lixula and
Paracentrotus lividus are considered key species of the Mediterranean infralittoral rocky shores. At high
densities, the grazing activity of both species can produce and maintain barren grounds, a particular habitat
condition characterized by extremely low cover values of erect algae with high presence of naked substrates
and encrusting corallinales, poor in biodiversity and ecosystem functions. We tested the role of different
settlement substrates on the metamorphosis competent larvae of the two species. Furthermore, from our
larval rearing trails we were able to identify strong temperature effects on larval development of the two
species. P. lividus and A. lixula larvae have been reared at 18 °C but for the second species it was necessary to
use higher temperatures (22 °C) to perform settlement experiments, as in the 18 °C set all larvae died in the
first week. Both species larvae have been fed Cricosphaera elongata. Metamorphosis of competent larvae has
been induced using different substrates: naked stones, Lithophyllum incrustans, Stypocaulon scoparium,
Corallina elongata, turf forming algae and Posidonia oceanica. For each species, two larval batches were used
for settlement experiments; for each larval batch two replicates/substrates were set up. No differences in the
rate of metamorphosis on any of the tested substrates were observed for P. lividus, while A. lixula showed to
prefer naked stones and encrusting coralline algae Considering that A. lixula population growth may trigger
barren extension on rocky shores, this may lead to a positive feedback between barren extension and A. lixula
population density. Furthermore, our results suggest that the predicted rise in seawater temperature may
favor A. lixula larval survival and inhibit P. lividus. Combining information on temperature tolerance with
other sources of information for these species in the Mediterranean, it is possible to develop a conceptual
model of the interaction between the two species and the alternative state of their habitats
Sea urchin coelomocytes cultured on nanoporous aluminium oxide as a potential tool for marine environmental monitoring
No full textOceans and seas are of paramount importance to the health of planet Earth and human kind. Marine ecosystems should be defended against attack of polluting agents by continuous monitoring; the means of such monitoring should be as green as possible, i.e. based on sensors manufactured by biocompatible and easily disposable raw materials. In this study, we lay the basis for the future development of biosensors of marine environment based on sea urchin cells cultured on nanoporous aluminium oxide. These cells are promising as in previous works they demonstrated high response to stressors, and the proposed substrates have low costs since fabricated by inexpensive anodization process from consumer quality aluminium foils. Coelomocytes of the Mediterranean sea urchin Paracentrotus lividus were cultured on the nanoporous alumina for up to 5days invitro. Then, a biochemical characterization was carried out, checking the cholinergic system pathway by means of serotonin autofluorescence induced by aldehyde exposure and by expression and functionality of neuroactive molecules, such as acetylcholinesterase and muscarinic acetylcholine receptors. Both living cell quality and system biochemistry were not affected after the culture, and both electrical modulation and non-self-reactivity were maintained. These findings sug- gest the possibility of using the sea urchin immune cells cultured on nanoporous alumina as tools for monitoring the marine water quality, based on their electrical response
Ultrastructural analysis of the spermatozoa of three antarctic fish species
No full textMale gametes of two icefishes, Chionodraco hamatus and Champsocephalus gunnari, family Channichthyidae were studied (with transmission and scanning electron microscopy), and a preliminary study was undertaken with scanning electron microscopy on Notothenia coriiceps, family Nototheniidae. Both families belong to the suborder Notorthenioidei, the perciform fish group endemic to Antarctic waters. At scanning electron microscopy level, all the three species show a rather similar morphology, common to most perciform species. At transmission electron microscopy, C. hamatus shows some differences: two nuclear fossae, and abundant membranous ornamentations of the head. While most Perciformes show anacrosomal spermatozoa, the portions of membrane of C. hamatus spermatozoa resemble acrosomoid vesicles, indicating a possible role in fertilization. In both C. gunnari and C. hamatus, the head membranes are bound, with different distribution, by PSA (Pisum sativum agglutinin), that generally presents affinity sites in acrosome membranes of mammalian spermatozoa
La tragedia del Cinquecento come “specchio de’ Principi”: la virtù, il principe e il tiranno nella 'Canace' di Giovanni Falugi
No full textThis essay deals with a tragedy written in the first half of the sixteenth century, the little-known Canace by Giovanni Falugi (1529 ca.), dedicated to Ippolito de’ Medici on the occasion of his election as cardinal; this tragedy, bound to be totally eclipsed in less than fifteen years by the far more renowned Canace by Sperone Speroni (1542), took up the ancient myth of the incestuous sons of Aeolus, Canace and Macareus, which had already become the subject of the lost Aeolus by Euripides and of the eleventh epistle of Ovid’s Heroides. In his own re-writing of the story, Falugi took into account the Ovidian source and was also fascinated by the Senecan tragedy, whose themes and motifs he abundantly resumed. The author’s classicism is also evident in the recovery of other ancient writers (such as Horace and Virgil), which have been highlighted when relevant to the present discussion. Starting from the definition of Renaissance tragedy as a ‘political’ literary genre and a brief historical contextualization of Giovanni Falugi and his work, this paper will focus on three aspects of Canace which can be related to the sixteenth-century theoretical koinè as regards political matters: 1) the idealised depiction of prince Macareus; 2) the tyrannical portrait of Aeolus; 3) the moral of the tragedy, which reveals the courtly gift made by the author to the dedicatee as the proposal of a model of virtue
Time-dependent expression of ryanodine receptors in sea urchin eggs, zygotes and early embryos
No full textIn this work, the presence of calcium-dependent calcium channels and their receptors (RyR) has been investigated in Paracentrotus lividus eggs and early embryos, from unfertilized egg to four-blastomere stages. Electrophysiological recordings of RyR single-channel current fluctuations showed that RyRs are functional during the first developmental events with a maximum at zygote stage, c. 40 min after fertilization, corresponding to the first cleavage. The nature of vertebrate-like RyRs active at this stage was established by specific activation/blockade experiments
- …
