The tilapia prolactin cell: A model for stimulus-secretion coupling     

E. Gordon Grau  Lisa M. H. Helms 《Fish physiology and biochemistry》1989,7(1-6):11-19

The tilapia prolactin (PRL) cell responds rapidly (10–20 min) to small physiological changes in medium osmotic pressure (OP), releasing increasing quantities of hormone as medium OP is reduced. This release is rapidly (≤ 10 min) inhibited by somatostatin (SRIF). There is now extensive evidence that tilapia PRL cell function is regulated through the second messengers Ca⁺⁺ and cAMP. Our studies have shown that PRL release is augmented by treatments that lead to increased levels of intracellular Ca⁺⁺ or cAMP. On the other hand, PRL release is blocked when tissues are incubated in Ca⁺⁺-depleted medium or upon the addition of Co⁺⁺, an inhibitor of Ca⁺⁺-mediated processes. The use of⁴⁵Ca⁺⁺ to characterize the movement of Ca⁺⁺ into PRL cells has provided evidence that an increase in the influx of extracellular Ca⁺⁺ may participate in PRL release upon exposure to hyposmotic medium. Our studies have also shown that SRIF suppresses the increase in⁴⁵Ca⁺⁺ accumulation that is brought about when OP is reduced. We have also examined the effects of OP and SRIF on cAMP levels. The reduction of medium OP did not alter cAMP metabolism during 20 min of incubation. By contrast, cAMP accumulation in the presence of IBMX was enhanced at 1 hr of incubation in reduced OP. Thus, an increase in cAMP turnover may play a role in maintaining PRL release under sustained stimulation. SRIF reduced the accumulation of cAMP during 10 min of incubation with IBMX and also reduced the forskolin-stimulated increase in cAMP. Thus, SRIF may suppress adenylate cyclase activity. Finally, our studies have revealed that the forskolin-stimulated increase in cAMP levels is not dependent upon medium Ca⁺⁺. The presence of Ca⁺⁺ in the medium is required, however, for PRL release even when the cAMP messenger system has been activated. Moreover, cAMP accumulation was augmented when intracellular Ca⁺⁺ was increased. This raises the possibility that reduced OP may stimulate an increase in cAMP turnover indirectly through its action(s) on cytosolic Ca⁺⁺.  相似文献   

Autonomic innervation of the ovary of the Atlantic cod,Gadus morhua     

Kazumasa Uematsu  Susanne Holmgren  Stefan Nilsson 《Fish physiology and biochemistry》1989,6(4):213-219

The autonomic innervation of the ovary of the Atlantic cod was investigated using histochemical and physiological/pharmacological methods. The paired ovary receives autonomic innervation via branches of the posterior splanchnic nerve (vesicular nerve).Histochemical studies demonstrated vasoactive intestinal polypeptide (VIP)-immunoreactive, 5-hydroxytryptamine-immunoreactive and adrenergic nerve fibers, but a number of antisera raised against other peptides failed to reveal any specific reaction in the tissue preparations. It is concluded that the cod ovary receives a double antagonistic autonomic innervation of excitatory cholinergic fibers and non-adrenergic inhibitory fibers. The nature of the inhibitory neurotransmitter is not known.  相似文献   

Regulation of cardiac output and gut blood flow in the sea raven,Hemitripterus americanus     

Michael Axelsson  William R. Driedzic  Anthony P. Farrell  Stefan Nilsson 《Fish physiology and biochemistry》1989,6(5):315-326

Coeliac artery blood flow (F_ca) before and after feeding was recorded in the sea raven. To obtain basic information about the scope of cardiovascular adjustment in the sea raven, a separate series of experiments was performed, in which ventral (P_va), and dorsal (P_da) aortic blood pressure, heart rate (HR) and cardiac output (jaz) were monitored during rest and encouraged exercise.Measurements of coeliac artery flow showed that visceral blood flow is substantial, particularly after feeding, and variations in the visceral vascular conductance affect P_da directly. Simultaneous recordings of intestinal and dorsal aortic blood pressures showed no measurable difference in the two arterial pressures, refuting the idea of a vascular control at the level of the main coeliac artery. Thus, in the sea raven, the adrenergic tonus affecting the visceral vasculature presumably acts at the arteriolar level.Sea ravens encouraged to exercise increased theirjaz by 64%; 32% through HR and 25% through stroke volume. The increase injaz during encouraged exercise was sufficient to produce an elevation of both P_va and P_da, despite an increase of systemic vascular conductance, -adrenoceptor blockade with sotalol, however, severely impaired the increase injaz during exercise, and the change in P_da was reversed.During rest there were both an adrenergic and a cholinergic tonus affecting the HR, as revealed by the effects of injected pharmacological antagonists. Swimming activity decreased the cholinergic tonus, while the adrenergic tonus increased.  相似文献   

TGF-β系统及其在硬骨鱼中的研究进展     

詹绪良  吴金英  李文笙 《南方水产》2013,9(3):90-96

TGF-β（transforming growth factor-β）是一类多效应细胞因子,在很多生理活动中发挥功能。TGF-β以前体形式合成,随后被切割活化形成成熟的TGF-β。TGF-β以二聚体的形式发挥作用,与受体TβRI（transforming growth factor-β receptor I）和TβRII（transforming growth factor-β receptor Ⅱ）形成一个大型复合物后,磷酸化胞内的Smad,激活下游信号通路。鱼类中,对TGF-β家族成员的研究主要集中在对TGF-β1的研究,包括TGF-β1与免疫相关和与生殖相关的功能,也有研究表明TGF-β1与肝功能相关。此外,有少量对TGF-β家族其他成员和TGF-β受体的研究。  相似文献   

The role of Toll‐like Receptors in innate immunity and infectious diseases of teleost          下载免费PDF全文

Mahmoud Tanekhy 《Aquaculture Research》2016,47(5):1369-1391

The immune defence mechanism depends mainly on germ‐line encoded pattern‐recognition receptors (PRRs). These PRRs respond to many exogenous pathogens and/or endogenous serious signals, by recognizing some highly conserved structures such as pathogen‐associated molecular patterns (PAMPs) and danger/damage associated molecular patterns (DAMPs). Till date, the most studied PRRs are Toll‐like receptors (TLRs). Upon activation of TLRs, there is production of inflammatory cytokines and type I interferons (IFNs) via myeloid differentiation primary response gene 88 (MyD88)‐dependent or ‐independent signalling, respectively, modulating innate and adaptive immunity, as well as inflammatory responses. In fish species studied to date, there are more than 17 TLRs that are identified with some showing homology to mammals, and some are unique for teleost. In the present review, more light are to be shed on the classification, structure and specific ligands of TLRs, with focuses on their signal pathways and different biological activities. Studies of TLRs and their role in the innate immune will potentially have implications for the prevention and treatment of fish diseases.  相似文献   

Histopathology associated with haptor attachment of the ectoparasitic monogenean Neobenedenia sp. (Capsalidae) to barramundi,Lates calcarifer (Bloch)          下载免费PDF全文

A Trujillo‐González  L K Johnson  C C Constantinoiu  K S Hutson 《Journal of fish diseases》2015,38(12):1063-1067

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The trend of lessepsian fish populations with an emphasis on temperature variations in Iskenderun Bay,the Northeastern Mediterranean          下载免费PDF全文

Sinan Mavruk  Fethi Bengil  Hacer Yeldan  Meltem Manasirli  Dursun Avsar 《Fisheries Oceanography》2017,26(5):542-554

The fish assemblages of the Eastern Mediterranean are highly variable owing to the Lessepsian migration. So far, there has been limited discussion about the temporal variation of Lessepsian populations, which may be a key to better understanding the establishment, persistence and spreading dynamics of these species. The objective of this study was, therefore, to develop an understanding of inter‐annual variations of Lessepsian fish populations through investigating the effects of climate conditions. For this purpose, we evaluated the data obtained from the seasonal bottom trawl surveys conducted over the course of 12 years, from 2004 to 2015, at the infra‐littoral zone of Iskenderun Bay. Our results indicated that Lessepsians constituted 27%, 62% and 85% of total teleost fishes in the number of species (LS‐%), biomass (LW‐%) and abundance (LN‐%), respectively. The linear trends showed that the dominance of Lessepsian fishes increased with annual rates of 1.9 (p < .01, LS‐%), 2.77 (p < .01, LW‐%) and 1.43% (p < .05, LN‐%) per year during the study period. In contrast, seasonal trend decomposition based on GAMMs revealed that the true shape of trends was non‐linear. The majority of the new Lessepsians entered the study area after 2009 when warmer conditions prevailed. Those new invaders such as Nemipterus randalli, Pomadasys stridens and Apogon smithi successfully settled in a short time and remarkably altered the composition of fish assemblages after 2010. We found that variations of lessepsian fish assemblages were correlated with the increase of annual minima and average values of sea surface temperature.  相似文献   

DIAGNOSTIC ULTRASOUND EXAMINATION AND ECHOCARDIOGRAPHY IN ATLANTIC SALMON (Salmo salar)     

Ronald D.  Sande  DVM  PhD  Trygve T.  Poppe  DVM  Dr. Scient 《Veterinary radiology & ultrasound》1995,36(6):551-558

Diagnostic ultrasound examination was performed on 53 mature, tranquillized, Atlantic salmon. Wild fish and farmed fish were equally represented. The purpose was to find a rapid method of examination that could be used to identify and separate fish with cardiomyopathy syndrome while fish are tranquillized for other procedures. Three methods of examination were studied. The non-elastic pericardium and absence of lungs results in cardiac function which is clearly different from that in mammals. M-mode echocardiography was complex, technical and time consuming and calculated fractional shortening was not reliable. Subjective evaluation of the heart and liver was valuable and easy to perform. Measurement of the transverse dimension of the atrium and ventricle on a ventro-dorsal axis through the cranial limit of the A-V valve gave acceptable objective data for comparison of the ventricular and atrial size. Diagnostic ultrasound is both practical and valuable for the clinical study of disease in fish.  相似文献   

Trauma-induced exophthalmia in vermilion snapper,Rhomboplites aurorubens (Cuvier 1829): Treatment and prevention     

Stacey Elizabeth Henderson  Shane Matthew Boylan 《Journal of fish diseases》2020,43(2):295-300

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Swim bladder tumor in the young adult scoliotic medaka (Oryzias latipes)     

Satoshi Furukawa  Yumiko Hoshikawa  Kota Irie  Yusuke Kuroda  Kazuya Takeuchi 《Journal of toxicologic pathology》2021,34(2):157

A swim bladder tumor was detected in one scoliotic medaka aged 22 weeks. The tumor was located in the dorsal abdominal cavity, with maximum dimension of 1,850 × 1,500 µm. No swim bladder lumen was identified, and the region where the swim bladder lumen would have been located, was replaced with adipose tissues. The tumor was a non-invasive, expansile, and encapsulated solid mass with a few cysts, and comprised a homogenous population of well-differentiated, densely packed, gas glandular epithelium-like cells. The tumor mass was connected to a rete mirabile that showed a hyperplastic capillary plexus; however, the tumor cells did not invade the rete mirabile, thereby revealing that the tumor was an adenoma originating from the gas glandular epithelium of the swim bladder. Since proliferative lesions in the swim bladder have been reported in some teleosts with skeletal deformations, including medaka, the occurrence of a spontaneous swim bladder tumor in teleosts is considered to be closely associated with various types of skeletal deformation, and spinal curvature in particular.  相似文献