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1.
Flatfish provide a natural paradigm to investigate adaptive changes in the central nervous system of vertebrates. During their metamorphosis, the animals undergo a 90 degrees tilt to one side or the other to become the bottom-adapted adult flatfish. The eye on the down side is pushed over to the up side. Thus, vestibular and oculomotor coordinate systems rotate 90 degrees relative to each other. As a result, during swimming movements different types of compensatory eye movements are produced before and after metamorphosis by the same vestibular stimulation. Intracellular staining of central neurons with horseradish peroxidase revealed that in postmetamorphic flatfish second-order horizontal canal neurons contact vertical eye muscle motoneuron pools on both sides of the brain via pathways that are absent in all other vertebrates studied. These unique connections provide the necessary and sufficient connectivity to adapt the flatfish's eye movement system to the animals' postmetamorphic existence. Although the adult fish has a bilaterally asymmetric appearance, the central nervous connectivity reestablishes symmetry in the vestibulo-oculomotor system. 相似文献
2.
Yamada T Donai H Okauchi M Tagawa M Araki K 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2011,160(4):174-180
Cortisol, the main glucocorticoid in fish, increases during flatfish metamorphosis and peaks before the surge of thyroxine. A large body of evidence indicates the essential role of thyroxine in flatfish metamorphosis, whereas information on cortisol is limited. We administered cortisol to spotted halibut Verasper variegatus larvae in order to examine the effect on pigmentation during metamorphosis. Administration of 10 μg cortisol per mL of water from before the onset of metamorphosis (stage E) to metamorphic climax (stage G) induced the development of adult type pigment cells on the blind side of the metamorphosed juveniles and increased the occurrence of ambicolored juveniles. When 10 μg/mL cortisol was administered during stage D, stages E–F, stage G or stage H, only the administration during stages E–F induced the development of adult type pigment cells on the blind side. In addition, the expression of the gene dopachrome tautomerase (dct), a marker of melanoblasts, was enhanced at Stage E by cortisol administration. These results clearly indicated, for the first time, the enhancement of pigmentation by exogenous high-dose cortisol. Since endogenous cortisol is secreted in response to various kinds of stress in rearing conditions, these results indicate a possible influence of stress conditions in the occurrence of ambicoloration in flatfish. 相似文献
3.
Cloning,tissue and ontogenetic expression of the taurine transporter in the flatfish Senegalese sole (Solea senegalensis) 总被引:1,自引:0,他引:1
Flatfish species seem to require dietary taurine for normal growth and development. Although dietary taurine supplementation
has been recommended for flatfish, little is known about the mechanisms of taurine absorption in the digestive tract of flatfish
throughout ontogeny. This study described the cloning and ontogenetic expression of the taurine transporter (TauT) in the
flatfish Senegalese sole (Solea senegalensis). Results showed a high similarity between TauT in Senegalese sole and other vertebrates, but a change in TauT amino acid
sequences indicates that taurine transport may differ between mammals and fish, reptiles or birds. Moreover, results showed
that Senegalese sole metamorphosis is an important developmental trigger to promote taurine transport in larvae, especially
in muscle tissues, which may be important for larval growth. Results also indicated that the capacity to uptake dietary taurine
in the digestive tract is already established in larvae at the onset of metamorphosis. In Senegalese sole juveniles, TauT
expression was highest in brain, heart and eye. These are organs where taurine is usually found in high concentrations and
is believed to play important biological roles. In the digestive tract of juveniles, TauT was more expressed in stomach and
hindgut, indicating that dietary taurine is quickly absorbed when digestion begins and taurine endogenously used for bile
salt conjugation may be recycled at the posterior end of the digestive tract. Therefore, these results suggest an enterohepatic
recycling pathway for taurine in Senegalese sole, a process that may be important for maintenance of the taurine body levels
in flatfish species. 相似文献
4.
R Collu 《Life sciences》1976,18(2):223-230
The daily intraventricular administration of Δ9-tetrahydrocannabinol (Δ9-THC) in microgram amounts for a week to prepuberal and adult rats had definite endocrine effects. Prostate weights were reduced and plasma and pituitary levels of growth hormone (GH) were increased in prepuberal rats. Pituitary levels of prolactin (PRL) were increased both in prepuberal and in adult animals while pituitary and adrenal weights and plasma corticosterone (B) levels were increased in adult rats. On the other hand, brain weights were significantly reduced by Δ9-THC in prepuberal and significantly increased in adult animals. No changes in brain levels of noradrenaline (NA), dopamine (DA) or serotonin (5-HT) were found in treated animals. These results indicate that Δ9-THC may modify some endocrine functions when injected directly into the brain in microgram amounts. They show on the other hand that young and adult animals may respond differently to the chronic administration of the psychoactive drug, although the difference may be due to a biphasic effect of different doses. 相似文献
5.
New neurons are born and integrated into functional circuits in the brains of many adult organisms. In virtually all of these systems, serotonin is a potent regulator of neuronal proliferation. Specific neural pathways underlying these serotonergic influences have not, however, been identified and manipulated. The goal of this study was to test whether adult neurogenesis in the crustacean brain is influenced by electrical activity in the serotonergic dorsal giant neurons (DGNs) innervating the primary olfactory processing areas, the olfactory lobes, and higher order centers, the accessory lobes. Adult‐born neurons occur in two interneuronal cell clusters that are part of the olfactory pathway. This study demonstrates that neurogenesis also continues in these areas in a dissected, perfused brain preparation, although the rate of neuronal production is lower than in brains from intact same‐sized animals. Inclusion of 10?9 M serotonin in the perfusate delivered to the dissected brain preparation restores the rate of neurogenesis to in vivo levels. Although subthreshold stimulation of the DGN does not significantly alter the rate of neurogenesis, electrical activation of a single DGN results in significant increases in neurogenesis in Cluster 10 on the same side of the brain, when compared with levels on the contralateral, unstimulated side. Measurements of serotonin levels in the perfusate using high‐performance liquid chromatography established that serotonin levels are elevated about 10‐fold during DGN stimulation, confirming that serotonin is released during DGN activity. This is the first identified neural pathway through which adult neurogenesis has been directly manipulated. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 2009 相似文献
6.
7.
The most remarkable developmental event during metamorphosis in flatfish (Pleuronectiformes) is the migration of their eyes; one eye migrates upwards, then passes through the dorsal midline, and finally stops on the other side. In this study, we determined that the ratio of the movable eye diameter on the transverse axis (DTA) to that on the vertical axis (DVA) increased during the metamorphosis of Paralichthys olivaceus and Solea senegalensis. Based on the recently proposed hypothesis that eye migration of flatfishes is caused by the push force from the proliferated tissue of the suborbital region, we postulated that the eye shape change is a result of the same force. Measurements of eye proportions in 20 species of adult flatfishes revealed that the DTA is constantly larger than the DVA, suggesting that the mechanisms of eye shape change and eye migration driven by proliferating cells in the suborbital tissue are universal among flatfishes. 相似文献
8.
Yann Planque Jrme Spitz Matthieu Authier Gaël Guillou Ccile Vincent Florence Caurant 《Ecology and evolution》2021,11(15):10004
Sympatric harbour (Phoca vitulina) and grey seals (Halichoerus grypus) are increasingly considered potential competitors, especially since recent local declines in harbour seal numbers while grey seal numbers remained stable or increased at their European core distributions. A better understanding of the interactions between these species is critical for conservation efforts. This study aimed to identify the trophic niche overlap between harbour and grey seals at the southern limit of their European range, in the Baie de Somme (BDS, Eastern English Channel, France), where numbers of resident harbour seals and visiting grey seals are increasing exponentially. Dietary overlap was identified from scat contents using hierarchical clustering. Isotopic niche overlap was quantified using δ13C and δ15N isotopic values from whiskers of 18 individuals, by estimating isotopic standard ellipses with a novel hierarchical model developed in a Bayesian framework to consider both intraindividual variability and interindividual variability. Foraging areas of these individuals were identified from telemetry data. The three independent approaches provided converging results, revealing a high trophic niche overlap due to consumption of benthic flatfish. Two diet clusters were dominated by either small or large benthic flatfish; these comprised 85.5% [CI95%: 80.3%–90.2%] of harbour seal scats and 46.8% [35.1%–58.4%] of grey seal scats. The narrower isotopic niche of harbour seals was nested within that of grey seals (58.2% [22.7%–100%] overlap). Grey seals with isotopic values similar to harbour seals foraged in coastal waters close to the BDS alike harbour seals did, suggesting the niche overlap may be due to individual grey seal strategies. Our findings therefore provide the basis for potential competition between both species (foraging on benthic flatfish close to the BDS). We suggest that a continued increase in seal numbers and/or a decrease in flatfish supply in this area could cause/amplify competitive interactions and have deleterious effects on harbour seal colonies. 相似文献
9.
Pigmentation development in hatchery-reared flatfishes 总被引:14,自引:0,他引:14
Malpigmentation is common in hatchery-reared flatfishes, decreasing the market value of whole fish, and increasing the risk of predation for juveniles released to enhance wild stocks. Pigmentation development in flatfishes occurs in two phases. First, during embryonic and larval stages pigment cells differentiate on both sides of the body. Second, at metamorphosis larval melanophores disappear, and adult melanophores differentiate on the ocular but not on the blind side. Malpigmentation seems to result from disruptions of the second phase, and may take the form of albinism on the ocular side or darkening of the blind side. Both types of aberration may be related to aspects of the hatchery environment such as lighting, substratum, and diet. Larval nutrition appears to be a key factor and enrichment of larval diets with fatty acids and Vitamin A can greatly reduce malpigmentation rates; however, levels suffcient to prevent pigmentation defects frequently cause other abnormalities. Two developmental explanations for albinism have been proposed. The first is that differentiation of ocular-side skin follows the normal blind-side pathway and adult melanophores therefore fail to develop on the ocular side. The second hypothesis suggests that dietary deficiencies inhibit retinal development and the resulting visual defects lead to failure of a hormonal signal required for melanophore differentiation. These hypotheses may well be complementary; as yet neither has been thoroughly tested. Definitive tests will require a combination of manipulative techniques such as tissue transplantation and cell culture with nutritional, behavioural and hormonal assays. Such integrative studies will further the understanding both of normal pigmentation development and of the environmental factors that contribute to high rates of albinism in hatchery-reared flatfish. 相似文献
10.
J. Keelan M. P. Brand T. E. Bates J. M. Land J. B. Clark S. J. R. Heales 《Neurochemical research》1996,21(8):923-927
Nitric oxide (NO) has been implicated in the process of cerebral ischemia/reperfusion injury. We have examined the production
of NO, as reflected by nitrite (NO2
−)+nitrate (NO3
−) accumulation, from synaptosomes isolated from neonatal or adult rat brain and subjected to a period of glucose and oxygen
deprivation. There was a significant increase in the amount of NO2
−+NO3
− production from adult synaptosomes under these conditions, whereas there was no difference compared to control in the production
of NO2
−+NO3
− from the neonatal synaptosomes. The total antioxidant status of the synaptosomes at these different stages of brain development
was found to be the same. These data suggest that the vulnerability of the adult brain to ischemia/reperfusion injury may
be associated with the production of NO from nerve terminals. The ratios of antioxidant capacity to NO production under such
conditions have been shown here to be different between the neonatal and adult nerve terminals. Thus the well documented resistance
of neonatal brain to ischemia/reperfusion injury may involve the neonatal nerve terminal being under less oxidative stress
than the adult. 相似文献
11.
I. C. Kokay A. R. Mercer 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,181(4):415-423
Changes in the levels of binding of 3H-SCH-23390, a vertebrate D1 dopamine receptor ligand, and 3H-spiperone, a vertebrate D2 dopamine receptor ligand were investigated in the brain of the worker honey bee during metamorphic
adult development and during the lifetime of the adult bee. Age-related fluctuations in binding levels were markedly different
for these two ligands. 3H-SCH-23390 and 3H-spiperone binding sites were present at low levels during metamorphic adult development. After adult emergence, however,
3H-SCH-23390 binding levels, in contrast to those of 3H-spiperone, increased significantly. Within the first 48 h of adult life 3H-SCH-23390 binding reached a level not significantly different from that detected in forager bees. No significant fluctuations
in the levels of 3H-spiperone binding were observed during the adult lifetime of the bee. Measurements of dopamine levels in the brains of pupal
and adult bees revealed no direct correlation between fluctuations in endogenous amine levels and the amount of binding of
either 3H-SCH-23390 or 3H-spiperone. These results provide evidence for subtype-specific patterns of expression of dopamine receptors in the insect
brain and show that D1- and D2-like receptors are expressed not only in the adult CNS, but also in the developing brain of
the bee.
Accepted: 4 June 1997 相似文献
12.
Abstract: We report the cloning and characterization of a cDNA encoding a cdc2-related protein kinase, named PFTAIRE, that is expressed primarily in the postnatal and adult nervous system. We have demonstrated by in situ hybridization and indirect immunofluorescence that several populations of terminally differentiated neurons and some neuroglia expressed PFTAIRE mRNA and protein. In neurons, PFTAIRE protein was localized in the nucleus and cytoplasm of cell bodies. The anatomical, cellular, and ontogenic patterns of PFTAIRE expression in the nervous system differed from those of p34cdc2 and cdk5, which are expressed in brain and several other mitotic tissues. Proteins of ~58–60 kDa coprecipitated specifically with PFTAIRE from cytosolic protein preparations of adult mouse brain and transfected cells. These proteins appeared to be the major endogenous substrates associated with this kinase activity. The temporal and spatial expression patterns of PFTAIRE in the postnatal and adult nervous system suggest that PFTAIRE kinase activity may be associated with the postmitotic and differentiated state of cells in the nervous system and that its function may be distinct from those of p34cdc2 and cdk5. 相似文献
13.
Transport of Iron in the Blood-Brain-Cerebrospinal Fluid System 总被引:10,自引:3,他引:7
M. W. B. Bradbury 《Journal of neurochemistry》1997,69(2):443-454
Abstract: Iron is an important constituent in brain and, in certain regions, e.g., the basal nuclei, reaches concentrations equivalent to those in liver. It has a role in electron transfer and is a cofactor for certain enzymes, including those involved in catecholamine and myelin synthesis. Iron in CSF is likely to be representative of that in interstitial fluid of brain. Transferrin in CSF is fully saturated, and the excess iron may be loosely bound as Fe(II). Brain iron is regulated in iron depletion, suggesting a role for the blood-brain barrier (BBB). Iron crosses the luminal membrane of the capillary endothelium by receptor-mediated endocytosis of ferric transferrin. This results in an initial linear uptake of radioactive iron into brain at an average rate relative to serum of about 3.3 × 10?3 ml·g of brain?1·h?1 in the adult rat. This corresponds to about 80 nmol·kg?1·h?1. Much higher rates occur in the postnatal rat. These increase during the first 15 days of life and decline thereafter. Within the endothelium, most of the iron is separated from transferrin, presumably by the general mechanism of acidification within the endosome. Iron appears to be absorbed from the vesicular system into cytoplasm and transported across the abluminal plasma membrane into interstitial fluid as one or more species of low molecular weight. There is some evidence that ionic Fe(II) is involved. Certainly Fe(II) ions presented on the luminal side rapidly cross the complete BBB, i.e., luminal and abluminal membranes. Within interstitial fluid, transported iron will bind with any unsaturated transferrin synthesized or transported into the brain-CSF system. Oligodendrocytes are one site of synthesis. From interstitial fluid, ferric transferrin is taken up by neurones and glial cells by the usual receptor-mediated endocytosis. Calculations of the amount of iron leaving the system with the bulk flow of CSF indicate that most iron entering brain across the capillary endothelium finally leaves the system with the bulk outflow of CSF through arachnoid villi and other channels. A system in which influx of iron into brain is by regulated receptor-mediated transport and in which efflux is by bulk flow is ideal for homeostasis of brain iron. 相似文献
14.
I?igo Martinez Emma G. Jones Sarah L. Davie Francis C. Neat Ben D. Wigham Imants G. Priede 《Hydrobiologia》2011,670(1):23-34
Baited underwater camera (BUC) systems to estimate demersal fish abundance are becoming increasingly considered as an alternative
to traditional survey methods, particularly in environments that contain sensitive habitats or protected species. Based on
27 replicate deployments of BUCs at 100 m depth in the northern North Sea, in rank order of abundance, hagfish (Myxine glutinosa), flatfish mainly dabs (Limanda limanda), whiting (Merlangius merlangus) and haddock (Melanogramus
aeglefinus) were observed consistently at baits. Higher maximum numbers (N
max) occurred during daytime in all species with the most significant effect in flatfish, 18 in daytime and 5 at night-time.
Bottom current had no significant effect on numbers of whiting, flatfish or haddock. The N
max of hagfish was strongly related to current speed in a non-linear way with an increase in numbers up to 10 cm s−1 and then decrease in N
max at higher water speeds. Understanding and accounting for such species-specific influences is important in the design of long
term monitoring surveys using baited cameras. 相似文献
15.
Ying Liu Ana Pocivavsek Vassilios Papadopoulos 《The Journal of steroid biochemistry and molecular biology》2009,115(3-5):86-90
Cytochrome P450 17α-hydroxylase/17, 20 lyase (CYP17) is a microsomal enzyme reported to have two distinct catalytic activities, 17α-hydroxylase and 17, 20 lyase, that are essential for the biosynthesis of peripheral androgens such as dehydroepiandrosterone (DHEA). Paradoxically, DHEA is present and plays a role in learning and memory in the adult rodent brain, while CYP17 activity and protein are undetectable. To determine if CYP17 is required for DHEA formation and function in the adult rodent brain, we generated CYP17 chimeric mice that had reduced circulating testosterone levels. There were no detectable differences in cognitive spatial learning between CYP17 chimeric and wild-type mice. In addition, while CYP17 mRNA levels were reduced in CYP17 chimeric compared to wild-type mouse brain, the levels of brain DHEA levels were comparable. To determine if adult brain DHEA is formed by an alternative Fe2+-dependent pathway, brain microsomes were isolated from wild-type and CYP17 chimeric mice and treated with FeSO4. Fe2+ caused comparable levels of DHEA production by both wild-type and CYP17 chimeric mouse brain microsomes; DHEA production was not reduced by a CYP17 inhibitor. Taken together these in vivo studies suggest that in the adult mouse brain DHEA is formed via a Fe2+-sensitive CYP17-independent pathway. 相似文献
16.
Hiroyuki Nozaki Kortaro Tanaka Shintaro Gomi Ban Mihara Shigeru Nogawa Eiichiro Nagata Taro Kondo Yasuo Fukuuchi 《Neurochemical research》1996,21(8):975-982
Alterations in ryanodine binding and local cerebral blood flow (LCBF) were examined at 30 minutes and 2 hours post-ischemia
in the gerbil brain in order to evaluate the influence of cerebral ischemia on the intracellular channels of Ca2+-induced Ca2+ release (CICR). Severe hemispheric cerebral ischemia was induced by occluding the right common carotid artery. LCBF was measured
at the end of the experiment using [14C]iodoantipyrine method, and the ryanodine binding was evaluated in vitro using [3H]ryanodine as a specific ligand for CICR channels. An autoradiographic method developed in our laboratory enabled us to determine
both parameters within the same brain. A group of gerbils who underwent a sham procedure served as controls. LCBF was found
to be significantly reduced in most of the cerebral regions on the occluded side at both 30 minutes as well as 2 hours post-ischemia.
In contrast, a significant reduction in ryanodine binding was noted only in the hippocampus CA1 on the occluded side at 30
minutes and 2 hours after the occlusion. These findings suggest that regionally specific changes of CICR may be the cause
of decreased ryanodine binding in the hippocampus CA1, and that these changes may be related to the pathophysiological mechanisms
that cause this region to be particularly vulnerable to ischemia. 相似文献
17.
Na+,K+-ATPase activity was determined in fetal guinea pig brain at 35, 40, 45, 50, 55, and 60 days of gestation. The activity remained at a constant level during the early periods (35–45 days) of gestation and increased significantly during 45–60 days. Following maternal hypoxia, the activity of Na+,K+-ATPase in the term (60 days) fetal brain was reduced by 50% whereas the preterm (50 days) brain activity was unaffected. Under identical hypoxic conditions, the enzymatic activity of adult brain was significantly reduced by 20%. Na+,K+-ATPase obtained from fetal brain (50 days of gestation) has both a low and a high affinity for ATP (K
m values =0.50 and 0.053 mM and correspondingV
max values =10.77 and 2.82 umoles Pi/mg protein/hr), whereas the enzyme in the adult brain has only a low affinity (K
m=1.67 mM andV
max=20.32 umoles Pi/mg protein/hr). The high and low affinity sites for ATP in the fetal brain suggests a mechanism essential for the maintenance of cellular ionic gradients at low concentrations of ATP and which would provide the fetal brain with a greater tolerance to hypoxia. The high sensitivity of Na+,K+-ATPase activity to hypoxia in guinea pig brain at term suggests that the cell membrane functions of the fetal brain may be more susceptible to hypoxia at term than it is earlier in gestation. 相似文献
18.
The histological visualization of choline acetyltransferase (CAT) and acetylcholinesterase (AChE) on frozen sections of prostomia of Nereis virens indicate a concentration of cholinergic activity in the anterior brain. Components are probably sensory epithelial cells with cholinergic axons entering the brain in cephalic nerves and efferent cholinergic axons to prostomial muscle leaving the brain in the same nerves. There are also subepidermal cholinergic cells that may be second order motor neurons serving epidermal mucous cells. The smaller, second lobe of the corpora pedunculata and its associated vertical fibre tract are CAT4 and appear continuous, on each side of the cerebral ganglion, with a dorsal and a ventral longitudinal bundle of AChE+ fibers. This system tapers to nothing at the level of the posterior eyes. There is a small AChE+ component to each optic nerve and AChE is present in the nuchal epithelium. These observations are discussed in relation to earlier studies on aminergic and neurosecretory activity in the same ganglion. 相似文献
19.
Taurine is an important modulator of neuronal activity in the immature brain. In kittens, taurine deficiency causes serious dysfunction in the cerebellar and cerebral visual cortex. The processes of taurine transport in vitro were now studied for the first time in different brain areas in developing and adult cats. The uptake of taurine consisted initially of two saturable components, high- and low-affinity, in synaptosomal preparations from the developing cerebral cortex and cerebellum, but the high-affinity uptake component completely disappeared during maturation. The release of both endogenous and preloaded labeled taurine from brain slices measured in a superfusion system was severalfold stimulated with a slow onset by depolarizing K+ (50 mM) concentrations. K+ stimulation released markedly more taurine from the cerebral cortex, cerebellum and brain stem in kittens than in adult cats. The responses were largest in the cerebellum. Both uptake and release of taurine are thus highly efficient in the brain of kittens and may be of significance in view of the vulnerability of cats to taurine deficiency. 相似文献
20.
CHRISTINE L. HUFFARD NORAH SAARMAN HEALY HAMILTON W. BRIAN SIMISON 《Biological journal of the Linnean Society. Linnean Society of London》2010,101(1):68-77
The ‘Mimic Octopus’Thaumoctopus mimicus Norman & Hochberg, 2005 exhibits a conspicuous primary defence mechanism (high‐contrast colour pattern during ‘flatfish swimming’) that may involve facultative imperfect mimicry of conspicuous and/or inconspicuous models, both toxic and non‐toxic (Soleidae and Bothidae). Here, we examine relationships between behavioural and morphological elements of conspicuous flatfish swimming in extant octopodids (Cephalopoda: Octopodidae), and reconstructed ancestral states, to examine potential influences on the evolution of this rare defence mechanism. We address the order of trait distribution to explore whether conspicuous flatfish swimming may be an exaptation that usurps a previously evolved form of locomotion for a new purpose. Contrary to our predictions, based on the relationships we examined, flatfish swimming appears to have evolved concurrently with extremely long arms, in a clade of sand‐dwelling species. The conspicuous body colour pattern displayed by swimming T. mimicus may represent a secondary adaptation potentially allowing for mimicry of a toxic sole, improved disruptive coloration, and/or aposematic coloration. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 68–77. 相似文献