共查询到20条相似文献，搜索用时 31 毫秒
1.
Experimental evidence suggests that olfactory imprinting by salmon occurs during a sensitive period associated with surges in plasma thyroxine (T4) levels during smolting. Life-history studies, however, suggest that imprinting may occur prior to smolting. A possible resolution of this paradox may lie in the finding that exposure of coho salmon, Oncorhynchus kisutch (Walbaum) smolts to novel water sources induced transient increases in plasma T4 levels. If novel water-induced T4 surges occur prior to smolting and T4 surges are required for olfactory imprinting, juvenile salmon experiencing novel water sources as they move through their watershed may learn olfactory waypoints (e.g. stream confluences). To test this hypothesis, we exposed subyearling coho salmon, Oncorhynchus kisutch (Walbaum), to novel odours or water sources at distinct developmental stages. Subyearlings did not demonstrate dramatic increases in plasma T4 levels during smolting and exposure to novel water sources also had no effect on basal T4 levels. Previous studies have indicated that such coho smolts successfully imprint to similar exposure paradigms and home accurately. These results suggest that surges in plasma T4 levels during smolting may not be necessary for olfactory imprinting and accurate homing. 相似文献
2.
Sara Ferrando Lorenzo Gallus Chiara Gambardella Emiliano Marchesotti Silvia Ravera Valeria Franceschini Maria Angela Masini 《Fish physiology and biochemistry》2014,40(6):1793-1800
Among vertebrates, the physiologically uremic Chondrichthyes are the only class which are not presenting the ciliated olfactory receptor neurons in the olfactory neuroepithelium. The only sequenced genome for this class revealed only three olfactory receptor genes and the immunohistochemical detection of G protein alpha subunit typically coupled to the olfactory receptors (Gαolf) failed in different species. Chronic renal disease can represent a cause of olfactory impairment in human. In this context, our present study focused on investigating potential effects of high urea concentration on the olfactory epithelium of vertebrates. Larvae of the teleost fish Danio rerio were exposed to urea in order to assess the effects on the olfactory signal transduction; in particular on both the olfactory receptors and the Gαolf. The endocytosis of neutral red dye in the olfactory mucosa was detected in control and urea-exposed larvae. The amount of neutral red dye uptake was used as a marker of binding and internalization of the Gαolf. The neutral red dye endocytosis was not affected by urea exposure, hence suggesting that the presence of the Gαolf and their binding to the odorants are not affected by urea treatment, either. The presence and distribution of Gαolf were investigated in the olfactory epithelium of control and urea-exposed larvae, using a commercial antibody. The immunoreactivity was increased after urea treatment, suggesting an effect of urea on the expression or degradation of this G protein alpha subunit. 相似文献
3.
Masafumi Amano Kataaki Okubo Takeshi Yamanome Yoshitaka Oka Shoji Kitamura Kazumasa Ikuta Akiyoshi Takahashi Katsumi Aida Kunio Yamamori 《Fish physiology and biochemistry》2003,28(1-4):19-22
Multiple forms of the gonadotropin-releasing hormone (GnRH) exist in teleost fish. A salmonid fish, masu salmon Oncorhynchus masou has salmon GnRH (sGnRH) and chicken GnRH-II (cGnRH-II). sGnRH neurons were scattered from the olfactory nerve through the ventral telencephalon (VT) and the preoptic area (POA). sGnRH but not cGnRH-II was detected in the pituitary. sGnRH mRNA levels in the VT and the POA increased during gonadal maturation, suggesting that sGnRH neurons in these areas are involved in gonadal maturation. sGnRH neurons were first detected in a cluster near the olfactory epithelium 40 days after fertilization. sGnRH neurons were not detected in the brain by the olfactory epithelia lesion, suggesting that sGnRH neurons are derived from the olfactory epithelium. A pleuronectiform fish, barfin flounder Verasper moseri has sGnRH, cGnRH-II and seabream GnRH (sbGnRH). sGnRH and cGnRH-II-immunoreactive fibers were observed throughout the brain, but not in the pituitary. sbGnRH neurons were located in the POA and sent fibers to the pituitary, indicating that sbGnRH is involved in GTH secretion. Judging from the location of neuronal somata and their projections, it is indicated that three GnRH systems exist in the barfin flounder; the TN-, the MT- and the POA-GnRH system. However, in masu salmon, clear anatomical identification of the TN- and the POA-GnRH system is difficult, because the GnRH neurons located in the ventral forebrain are consecutive and the GnRH form produced in these neurons is the same (sGnRH). Thus, it is suggested in masu salmon that sGnRH neurons are derived from the olfactory epithelium, migrate into the brain and play different roles according to the location in the brain. 相似文献
4.
5.
Olfactory receptor neurons (ORNs) in the olfactory epithelium (OE) and olfactory projection areas in the brain of sockeye salmon (Oncorhynchus nerka) were investigated by a newly developed odor-stimulated labeling methods using agmatine (AGB). The olfactory receptor cells (ORCs) in OE were immunocytochemically labeled by stimulation with AGB or AGB plus L-alanine. Immuno-electron microscopy demonstrated that the labeled ORCs were predominately microvillus ORCs. Moreover, AGB immunoreactivities were observed in mitral cells of the olfactory bulb and neurons of the telencephalon. These results reveal that AGB can be used as an activity-dependent label for ORNs in salmonid fishes. 相似文献
6.
Atlantic halibut juveniles, which have been fed Artemia during larval development, frequently demonstrate malpigmentation and impaired eye migration. This is in contrast to the high percentage of normally developed larvae fed copepods, reared under similar conditions. Nutrition is therefore an important component influencing larval development. Analyses of the nutrient composition of Artemia and copepods show that Atlantic halibut larvae fed Artemia probably receive sufficient amounts of vitamin A by converting canthaxanthin, while iodine may be deficient, possibly leading to interrupted thyroid hormone synthesis. An unbalanced fatty acid composition, such as high levels of arachidonic acid and low levels of docosahexaenoic acid, can be another limiting factor in Artemia. Vitamin A, fatty acids and thyroid hormones have all been shown to affect pigmentation in flatfish. They are ligands to nuclear receptors, thyroid hormone receptors, retinoic acid receptors, retinoic X receptors and peroxisomal proliferator‐activated receptors, which are members of the superfamily of steroid hormone receptors. The receptors interact with each other to promote gene expression that modulates proliferation and differentiation of cells. Our hypothesis is that these interactions are important for development during flatfish metamorphosis. Very little data exist on the topic of impaired eye migration. However, energy limitation, iodine deficiency and an unbalanced fatty acid composition have been proposed as possible explanations. Here, we review the literature on development of pigment cells and the possible mechanisms behind the effects of vitamin A, fatty acids and thyroid hormone on pigmentation and eye migration during development of Atlantic halibut larvae. 相似文献
7.
In teleosts, as in other vertebrates, the secretion of pituitary gonadotropin (GTH) is mediated by the hypothalamic decapeptide, gonadotropin-releasing hormone (GnRH). Recent findings in teleosts indicate that GnRH receptors are not restricted to the pituitary gonadotropes and are also associated with somatotropes as well as being present in a number of other tissues. In the present study, we provide novel information on GnRH binding in a number of extrapituitary tissues in goldfish. However, we do not intend to provide full characterization of GnRH binding sites in various extrapituitary tissues in goldfish as this would clearly be outside the scope of this paper. In this study we examined GnRH binding in a number of extrapituitary tissues in goldfish and observed specific binding in ovary, testis, brain, liver and kidney. No specific GnRH binding was observed in muscle, skin, gut, gill and heart. In general, the present findings together with the results of other studies carried out in our laboratory demonstrate that mature goldfish ovary and testis contain two classes of GnRH binding sites, high affinity/low capacity and low affinity/high capacity sites with binding characteristics similar to those of the pituitary GnRH receptors. The brain of goldfish was also found to contain two classes of GnRH binding sites, a super-high affinity/low capacity and a low affinity/high capacity sites. Furthermore, study of goldfish liver and kidney demonstrated the presence of a single class of GnRH binding sites with characteristics different from those of pituitary, ovary, testis and brain. Overall, it is evident that goldfish contains a family of GnRH binding sites which can be classified into four groups based on binding affinities: 1) A class of high affinity binding sites present in the pituitary, ovary and testis, 2) a class of super high affinity sites so far only detected in the brain, 3) a class of intermediate-affinity GnRH binding sites in the liver and kidney, and 4) a class of low affinity binding sites present in all the tissues containing specific GnRH binding sites except for liver and kidney. 相似文献
8.
A. Poli B. Pavan R. Lucchi P. G. Borasio E. Fabbri R. Rossi 《Fish physiology and biochemistry》1997,16(1):19-27
N6-cyclohexyl[3H]adenosine ([3H]CHA) was used to label adenosine A1 receptors in membranes prepared from male and female eel whole brain. The A1 receptor
agonist [3H]CHA bound saturably, reversibly and with high affinity (Kd = 0.91 ± 0.12 nM; Bmax = 120.36 ± 5.2 fmol mg−1 protein). In equilibrium competition experiments, the adenosine agonists and antagonists all displaced [3H]CHA from high-affinity binding sites with the rank order of potency in displacing, characteristics of an A1 adenosine receptor.
Mg2+ dramatically increased the affinity of [3H]CHA without modifying the maximal binding capacity. The specific binding was inhibited by guanosine 5′-triphosphate (Ki = 2.54 ± 0.98 μM). The [3H]CHA binding sites are ubiquitously distributed with a maximum in cerebellum and a minimum in olfactory bulb. No difference
was observed between male and female brain. In eel brain, synaptosomes (P2), stimulation of adenosine 3′,5′-monophosphate
(cyclic AMP) accumulation with 10−5 M forskolin was markedly reduced (45.5%) by treatment with the adenosine A1 receptor agonist CHA (10−4 M), and the reduction was reversed in presence of the selective A1 receptor antagonist 8-cyclopentyltheophylline (10−5 M). In superfused eel cerebellar synaptosomes, K+ stimulated the release of adenosine in a partially Ca2+-dependent manner. The findings, taken together, suggest the hypothesis that adenosine A1 receptors present in eel brain could
modulate synaptic transmission, as A1 receptors do in other vertebrates. 相似文献
9.
T. Kitani S. Matsumoto H. Yamada M. Amano M. Iwata H. Ueda 《Fish physiology and biochemistry》2003,28(1-4):269-270
Levels of two moleculer types of gonadotropin-releasing hormone (GnRH), salmon GnRH (sGnRH) and chicken GnRH–II (cGnRH–II) in the various brain regions and pituitary gland of sockeye salmon (Oncorhynchus nerka) and chum salmon (O. keta) during smoltification and spawning migration, respectively, were measured using specific time-resolved fluoroimmunoassay (TR-FIA) systems. Changes in sGnRH levels in different brain regions tended to be specifically synchronized with serum thyroid hormone or pituitary gonadotropin (GTH) levels during smoltification and spawning migration, respectively. In contrast, cGnRH–II levels did not show such synchronized changes. SGnRH and cGnRH–II in various brain regions might have different roles during smoltification and spawning migration of salmonid fishes. 相似文献
10.
11.
为了深入了解斑马鱼端脑的微细形态和超微结构,采用光镜和电镜技术对斑马鱼端脑进行观察研究。斑马鱼端脑由左、右嗅球和左、右大脑半球构成。嗅球前方有一对嗅神经,后端伸出嗅茎与大脑半球联系。光镜下,嗅球组织结构从外向内依次为上皮层、神经纤维层、小细胞层和内部细胞层。大脑半球外部覆盖很薄的大脑皮,基部为纹状体,两者之间的腔隙为公共脑室。纹状体由神经核团和神经纤维构成。神经核团分布于纹状体周缘,主要有连前核、背嗅核、侧嗅核、视前核和脚内核等。神经纤维包括横行的前连合,纵行和斜行的中央嗅束和侧嗅束。电镜下,嗅球分层明显,可观察到僧帽细胞、神经胶质细胞和众多突触。大脑半球中可见神经胶质细胞、突触以及血脑屏障系统等。斑马鱼端脑形态结构与大多数硬骨鱼相似,但有个别核团存在差异。实验结果可为斑马鱼神经生物学模型的建立与应用提供有效的理论基础。 相似文献
12.
Ky Xuan Pham Masafumi Amano Noriko Amiya Yutaka Kurita Kunio Yamamori 《Fish physiology and biochemistry》2006,32(3):241-248
To elucidate the role of gonadotropin-releasing hormone (GnRH) in gonadal maturation in wild female Japanese flounder Paralichthys olivaceus, we monitored changes in the levels of seabream GnRH (sbGnRH) in the olfactory bulb, telencephalon, hypothalamus, and pituitary during ovarian development together with changes in plasma levels of testosterone (T), estradiol-17β (E2), and 17α, 20β-dihydroxy-4-pregnen-3-one (DHP). Fish were caught offshore of the northern mainland of Japan in the Pacific Ocean at 3- to 4-week intervals between April and September by gill net. The netted fish were categorized into six groups based on ovarian stages: previtellogenic (April–early May), early yolk (April–late May), late yolk (late May–June), early spawning (June–August), late spawning (September), and termination (September) stages. The gonadosomatic index significantly increased from the previtellogenic to early spawning stages and decreased thereafter. In the olfactory bulb, no significant differences were observed in sbGnRH levels among the developmental stages. In contrast, sbGnRH levels in the telencephalon and hypothalamus were very high in the previtellogenic stage, lower in the early spawning stage, and relatively high in latter stages. sbGnRH levels in the pituitary were high in the previtellogenic stage and low in the early spawning stage. In addition, the relatively high levels of pituitary sbGnRH were found together with high plasma T, E2, and DHP levels in fish in the late yolk stage. These results indicate that sbGnRH in the telencephalon, hypothalamus, and pituitary is involved in ovarian maturation and that sbGnRH may play an important role in the initiation of ovarian recrudescence in wild Japanese flounder. 相似文献
13.
The sheepshead minnow is widely used in ecotoxicological studies that only recently have begun to focus on disruption of the thyroid axis by xenobiotics and endocrine disrupting compounds. However, reference levels of the thyroid prohormone thyroxine (T4) and biologically active hormone 3,5,3′-triiodothyronine (T3) and their developmental patterns are unknown. This study set out to describe the ontogeny and morphology of the thyroid gland in sheepshead minnow, and to correlate these with whole-body concentrations of thyroid hormones during early development and metamorphosis. Eggs were collected by natural spawning in our laboratory. T4 and T3 were extracted from embryos, larvae and juveniles and an enzyme-linked immunoassay was used to measure whole-body hormone levels. Length and body mass, hatching success, gross morphology, thyroid hormone levels and histology were measured. The onset of metamorphosis at 12-day post-hatching coincided with surges in whole-body T4 and T3 concentrations. Thyroid follicles were first observed in pre-metamorphic larvae at hatching and were detected exclusively in the subpharyngeal region, surrounding the ventral aorta. Follicle size and thyrocyte epithelial cell heights varied during development, indicating fluctuations in thyroid hormone synthesis activity. The increase in the whole-body T3/T4 ratio was indicative of an increase in outer ring deiodination activity. This study establishes a baseline for thyroid hormones in sheepshead minnows, which will be useful for the understanding of thyroid hormone functions and in future studies of thyroid toxicants in this species. 相似文献
14.
We propose a simple index of brain volume (D*L index), calculated using two-dimensional photographs of the brain, captured from the dorsal and lateral views. Here, D and L represent the dorsal and lateral brain areas in the images, respectively. Two distantly related species were assessed. The D*L indices of 11 Japanese eels, Anguilla japonica and 11 yellowfin gobies, Acanthogobius flavimanus were calculated. High correlation coefficients of D*L index with brain weights were obtained from both species, suggesting the validity and reliability of the index. The relative profiles of the olfactory bulb, telencephalon, optic tectum, and cerebellum were calculated using this index. Eels had a larger olfactory bulb and telencephalon, whereas gobies had a larger optic tectum. Principal component analysis showed two separate clusters for eels and gobies. Published images of two Anguilliformes species and four Gobiidae species were used to test the D*L index. Principal component analysis showed separate clusters for Anguilliformes and Gobiidae species. The D*L index is a suitable tool for data collection because it is simple, low-cost, and has reliability and validity.
相似文献15.
Monogenean worms are ectoparasites that are known to be infectious to a wide variety of fish. Few species of monogenean parasites have been reported in the olfactory chamber of fish in current peer‐reviewed literature. However, the impacts of these parasites on the olfactory system are not well understood. In this study, the effects of Gyrodactylus salmonis on the olfactory system structure and performance were investigated in rainbow trout (Oncorhynchus mykiss). The olfactory performance of the infected fish was examined using an electro‐olfactography (EOG) technique, while the ultrastructure of the olfactory rosette was studied using scanning electron microscopy (SEM) and light microscopy (LM). The infected rainbow trout displayed reduced responses to two standard olfactory cues (L‐alanine and TCA). The SEM micrographs revealed that many regions of the olfactory epithelium in the infected fish were heavily pitted and the LM examination of the olfactory epithelium showed local proliferation of mucous cells in the sensory regions as compared to the control group. The results of this study demonstrated that G. salmonis causes physical damage to the olfactory system of fish that lead to olfactory impairment. 相似文献
16.
Smolting and maturation of 2+ brown trout Salmo trutta L. were evaluated after exposing the groups of trout to different feeding regimes during the summers at 0+ and 1+ ages. The hypothesis tested was based on the theory of smolting of a congeneric species, Atlantic salmon Salmo salar L., in which the physiological smolting decision is expected to be taken at the end of July or beginning of August. During the first summer, the growth of the trout was restricted in two groups out of four by low feeding frequency. During the second summer, food was totally withheld for 3 weeks in June–July (i.e. before the expected sensitive period), in August or not at all (control). The proportion of sexually mature males in November was 5.2% in the groups fasted during August, but somewhat lower in the groups fasted in June–July (average 2.3%) or in control fish (3%). The tendency for smolting was evaluated during the following spring in an artificial stream with the help of PIT-tag technology, which allowed monitoring of the movements of individually tagged trout. Seawater challenge tests were also carried out in April and June. Differences in osmoregulatory ability in seawater indicated that feeding treatments had a slight effect on the timing of smolting, but no differences were observed in movement behaviour between treatment groups. Mature and maturing males moved less at the peak migration time (mid-May) but more in October than immature fishes. These results suggest that the smolting decision in brown trout may be taken at a different time than in Atlantic salmon and that periodic poor growth conditions during the summer will not prevent smolting of trout during the following spring. 相似文献
17.
A. Supriya K. Raghuveer I. Swapna M. K. Rasheeda T. Kobayashi Y. Nagahama Aparna Dutta Gupta K. C. Majumdar B. Senthilkumaran 《Fish physiology and biochemistry》2005,31(2-3):267-270
In the present study, thiourea-induced thyroid hormone depletion and thyroxine (T4) ‘overdose’ were used as a strategy to understand the influence of thyroid hormones on ovarian recrudescence of juvenile
(3-months-old), immature (8-months-old) and adult (1-year-old) air-breathing catfish, Clarias gariepinus. Thiourea-induced thyroid hormone depletion in juvenile catfish impaired ovarian development, but no significant effect was
observed in immature catfish and during late stage of ovarian recrudescence of mature catfish. T4 treatment in females undergoing late stages of ovarian recrudescence induced rapid oocyte growth by promoting its early entry
into maturational phase as evident from the presence of more number of vitellogenic and post-vitellogenic follicles, decrease
in aromatse immunoreactivity and reduced estradiol–17β levels. Hence, thyroid hormones have an important role to play during early stages of ovarian development and vitellogenesis
of catfish and also indicating that thyroid has a stage dependent effect on ovary. 相似文献
18.
Ky Xuan Pham Masafumi Amano Noriko Amiya Yutaka Kurita Akio Shimizu Kunio Yamamori 《Fisheries Science》2007,73(5):1113-1122
ABSTRACT: To clarify the possible roles of gonadotropin-releasing hormone (GnRH) in the reproduction of Japanese flounder Paralichthys olivaceus , localization of salmon GnRH (sGnRH), chicken GnRH-II (cGnRH-II), and sea bream GnRH (sbGnRH) immunoreactive (ir) cell bodies and fibers in the brain and pituitary were examined together with follicle stimulating hormone (FSH) and luteinizing hormone (LH)-ir cells in the pituitary by immunohistochemistry. sGnRH-ir cell bodies were localized in the ventromedial part of the rostral olfactory bulb and cGnRH-II-ir cell bodies were restricted to the midbrain tegmentum, while sbGnRH-ir cell bodies were evident in the preoptic area. sGnRH-ir fibers were distributed throughout the brain, especially abundant in the forebrain. cGnRH-II-ir fibers were also scattered in many areas of the brain with abundance in the midbrain, but sbGnRH-ir fibers were observed in the preoptic–hypothalamic area and innervated the pituitary. In the pituitary, neither sGnRH-ir fibers nor cGnRH-II-ir fibers were found, but sbGnRH-ir fibers were profuse in the neurohypophysis and invaded the proximal pars distalis, targeting FSH and LH cells. These results suggest that three GnRH systems can play different physiological roles in the brain of Japanese flounder. Among them, sbGnRH is considered to be involved in reproduction by stimulating gonadotropin secretion, while sGnRH and cGnRH-II can function as a neurotransmitter and/or neuromodulator within the brain in this species. 相似文献
19.
Pituitary gonadotropin-releasing hormone (GnRH) receptor activity in goldfish and catfish: seasonal and gonadal effects 总被引：3，自引：0，他引：3
H. R. Habibi R. De Leeuw C. S. Nahorniak H. J. Th Goos R. E. Peter 《Fish physiology and biochemistry》1989,7(1-6):109-118
The goldfish pituitary contains two classes of gonadotropin-releasing hormone (GnRH) binding sites, a high affinity/low capacity
site and a low affinity/high capacity site (Habibiet al. 1987a), whereas the catfish pituitary contains a single class of high affinity GnRH binding sites (De Leeuwet al. 1988a). Seasonal variations in pituitary GnRH receptor binding parameters, and the effect of castration on pituitary GnRH
receptor binding were investigated in goldfish and catfish, respectively. In goldfish, GnRH receptors undergo seasonal variation
with the highest pituitary content of both high and low affinity sites occurring during the late stages of gonadal recrudescence.
The observed changes in pituitary GnRH receptor content correlate closely with responsiveness to a GnRH agonistin vivo in terms of serum gonadotropin (GTH) levels. In catfish, castration results in a two-fold increase in pituitary GnRH receptor
content, which can be reversed by concomitant treatment with androstenedione, but not by the non-aromatizable androgen 11β-hydroxyandrostenedione;
changes observed in GnRH receptor content correlate with variations in serum GTH levels and responsiveness to a GnRH agonist.
In summary, the present study provides a clear evidence for seasonal variation in pituitary GnRH receptor activity in goldfish,
and demonstrates a gonadal feedback mechanism regulating GnRH receptor activity in the catfish pituitary. 相似文献
20.
甲状腺激素在鱼类的生长、发育、生殖等过程中均起着至关重要的作用,环境内分泌干扰物能够通过不同途径干扰硬骨鱼的甲状腺轴.本研究在介绍硬骨鱼下丘脑-垂体-甲状腺轴调控机制以及甲状腺激素在鱼体内动态变化过程的基础上,从甲状腺激素的合成、转运、转化、代谢以及清除等角度,总结了目前常用于指示鱼类甲状腺轴受干扰的指标,并从甲状腺轴生物标志物的研发、环境内分泌干扰物活体暴露时间和浓度选择、体外/体内相结合评价体系的建立以及微观水平指标与宏观水平指标相结合的角度,展望了该领域今后的研究重点和方向,以期为环境内分泌干扰物对鱼类甲状腺轴干扰作用研究提供更多的参考. 相似文献