鲫鱼尾部神经分泌系统显微和亚显微结构的季节性变化

鲫鱼尾部神经分泌系统的神经分泌细胞和它的轴突中可观察到各种不同电子密度的颗粒。在性腺各个不同的发育阶段,该系统的分泌物具有累积、充满、释放和恢复这样一种周期性变化,由此说明鲫鱼的尾部神经分泌系统和它的生殖有关。     

Modulation of connexon densities in gap junctions of horizontal cell perikarya and axon terminals in fish retina: effects of light/dark cycles,interruption of the optic nerve and application of dopamine

Summary In the fish retina, connexon densities of gap junctions in the outer horizontal cells are modulated in response to different light or dark adaptation times and wavelengths. We have examined whether the connexon density is a suitable parameter of gap junction coupling under in situ conditions. Short-term light adaptation evoked low connexon densities, regardless of whether white or red light was used. Short-term dark adaptation evoked high connexon densities; this was more pronounced in the axon terminal than in perikaryal gap junctions. Under a 12 h red light/12 h dark cycle, a significant difference in connexon densities between the light and the dark period could be established in the gap junctions of the perikarya and axon terminals. Under a white light/dark cycle, only the gap junctions of axon terminals showed a significant difference. Crushing of the optic nerve resulted in an increase in connexon densities; this was more pronounced in axon terminals than in perikarya. Dopamine injected into the right eye of white-light-adapted animals had no effect. However, dopamine prevented the effect of optic-nerve crushing on connexon density. The reaction of axon-terminal gap junctions to different conditions thus resembles that of perikaryal gap junctions, but is more intense. Axon terminals are therefore thought to play an important role in the adaptation process.     

雌核发育银鲫的受精生物学研究——天然雌核发育银鲫繁殖方式的讨论

本文研究了同源雌核发育银鲫精子在4种类型的雌核发育银鲫卵中的发育特征。初步揭示了天然雌核发育银鲫根据精子的来源不同而分别具有二种不同的繁殖方式,对其在维持雌核发育银鲫种群生存,促使克隆分化等方面的独特的生物学意义进行了讨论。     

A reinvestigation of the Gn-RH (gonadotrophin-releasing hormone) systems in the goldfish brain using antibodies to salmon Gn-RH

Summary The organization of Gn-RH systems in the brain of teleosts has been investigated previously by immunohistochemistry using antibodies against the mammalian decapeptide which differs from the teleostean factor. Here, we report the distribution of immunoreactive Gn-RH in the brain of goldfish using antibodies against synthetic teleost peptide.Immunoreactive structures are found along a column extending from the rostral olfactory bulbs to the pituitary stalk. Cell bodies are observed within the olfactory nerves and bulbs, along the ventromedial telencephalon, the ventrolateral preoptic area and the latero-basal hypothalamus. Large perikarya are detected in the dorsal midbrain tegmentum, immediately caudal to the posterior commissure. A prominent pathway was traced from the cells located in the olfactory nerves through the medial olfactory tract and along all the perikarya described above to the pituitary stalk. In the pituitary, projections are restricted to the proximal pars distalis. A second immunoreactive pathway ascends more dorsally in the telencephalon and arches to the periventricular regions of the diencephalon. Part of this pathway forms a periventricular network in the dorsal and posterior hypothalamus, whereas other projections continue caudally to the medulla oblongata and the spinal cord. Lesions of the ventral preoptic area demonstrate that most of the fibers detected in the pituitary originate from the preoptic region.     

The dopaminergic innervation of the goldfish pituitary

Summary The dopaminergic innervation of the goldfish pituitary gland was studied by immunocytochemistry at the electron-microscope level using highly specific antibodies against dopamine coupled to bovine serum albumin with glutaraldehyde. A satisfactory preservation of the tissue was achieved after immersion in 5% glutaraldehyde in phosphate buffer containing sodium metabisulfite to prevent oxidation of the endogenous dopamine. The immunocyto-chemical procedure was performed on Vibratome sections using the preembedding method. Immunoreactivity was restricted to part of the neurosecretory type-B fibers (diameter of the secretory vesicles lower than 100 nm) in which it was found to occupy the whole cytoplasm. Labeled fibers were observed within the neurohypophysis in the different parts of the gland and in the adenohypophyseal tissue where immunoreactive profiles were detected in close apposition to the different cell types. These data are in agreement with previous results obtained by means of radioautography and further support a role for dopamine in the neuroendocrine regulation of pituitary functions in teleosts.     

The effects of activators of G-proteins,mastoparan and compound 48/80, on the G-protein/adenylate cyclase system in cultured melanophores of the black-moor goldfish,Carassius auratus

 To investigate the functions of GTP-binding protein(s) in the melanosome-aggregating response in fish melanophores, the effects of activators of G-proteins, namely, mastoparan and compound 48/80, were examined in cultured melanophores of the balck-moor goldfish, Carassius auratus. Both mastoparan and compound 48/80 induced an approximately 40% increase in the GTP-hydrolyzing activity in the melanophore membranes compared to the basal level. In intact melanophores, these compounds inhibited the effect of 3-isobutyl-1-methylxanthine, which induced the accumulation of intracellular cAMP. Pretreatment of melanophores with pertussis toxin at 1 μg ⋅ ml^-1 for 15 h attenuated the inhibitory effect of mastoparan on the accumulation of cAMP. However, pretreatment with the toxin only slightly attenuated the inhibitory effect of compound 48/80 on the accumulation of cAMP. In addition, compound 48/80 at 1 mg ⋅ ml^-1 induced full aggregation of the melanosomes in melanophores, though mastoparan at 5 μmol ⋅ l^-1 induced only 10–20% aggregation of melanophores. These results suggest that mastoparan and compound 48/80 can each activate the inhibitory G-protein in goldfish melanophores, which results in inhibition of adenylate cyclase activity. This signal-transduction pathway is involved in the aggregation of melanosomes in these cells. Accepted: 3 June 1996     

The 65-kDa cytosolic protein associated with warm temperature acclimation in goldfish,Carassius auratus

Goldfish Carassius auratus were acclimated to either 10 or 30°C for a minimum of 5 weeks. A 65-kDa protein specific to warm-temperature-acclimated fish was extracted from the gel with 70% formic acid after two-dimensional electrophoresis of the muscle cytoplasmic protein fraction. The 65-kDa protein thus prepared to homogeneity was used to raise specific antibodies in rabbit by conventional methods. The antibody produced exhibited specific reaction with a protein having the same molecular weight from brain and liver tissue, suggesting that the 65-kDa protein is a ubiquitous cytosolic component in warm-acclimated goldfish. When water temperature was increased from 20 to 30°C over a 20-h period, a prominent amount of the 65-kDa protein was observed in muscle tissue extracts within 5 days of additional rearing; this was demonstrated by immunoblotting with the specific antibody. The N-terminal amino acid sequence of the 65-kDa protein was determined as Asp-Glu-Pro-Gln-Gly-His-Gln-His (or Asp)-Glu-Leu, differing from that of a family of known heat-shock proteins having about 70 kDa in molecular mass (hsp 70). No interaction between ATP and the 65-kDa protein revealed by ATP-agarose affinity chromatography further confirmed the different properties of the 65-kDa protein from those of hsp 70.Abbreviations ATP adenosine 5-triphosphate - hsp heat-shock protein(s) - IgG immunoglobulin G - mRNA messenger ribonucleic acid - PMSF phenylmethylsulphonyl fluoride - PVDF polyvinylidene difluoride - SDS sodium dodecyl sulphate - SDS-PAGE SDS-polyacrylamide gel electrophoresis     

大阪鲫鱼（Carassius Auratus cuvieri Temminck et．Schlegel）雌性特异血清蛋白生化特性及免疫细胞化学定位的研究

雌性特异血清蛋白存在于成熟雌性大阪鲫鱼血清中,雄鱼则无。注射雌二醇可诱导雄鱼及成熟雌鱼合成这种蛋白质并引起鱼肝细胞粗面内质网增加,糖元颗粒减少。从诱导的大阪鲫鱼血清中分离出电泳纯的雌性特异血清蛋白的分子量为４６６０００±４０００（ｎ＝１０）,电泳谱带有３条,用纯的雌性特异血海蛋白制备的兔抗鱼抗血清不与雄鱼血清发生免疫反应,而与正常成熟雌鱼及诱导鱼的血清形成１条免疫沉淀线。免疫细胞化学定位诱导及成熟雌鱼的肝细胞核外细胞质有阳性颗粒,在卵母细胞外围有成团的阳性颗粒分布。     

Synapse-like contacts between axons of the pineal tract and the subcommissural organ in Rana perezi (Anra) and their absence in Carassius auratus (Teleostei): ultrastructural tracer studies

The present study was designed to investigate the controversial subject of the existence of a neural input from the pineal organ via the pineal tract to the subcommissural organ (SCO) in teleosts and anurans. Horseradish peroxidase was injected into the pineal organ and pineal tract of Carassius auratus and Rana perezi. Within the pinealofugal fibers the tracer was visualized at the light-and electron-microscopic levels either by immunocytochemistry using an anti-peroxidase serum, or by revealing the enzymatic activity of peroxidase. In both species, labeled myelinated and unmyelinated fibers of the pineal tract were readily traced by means of electron microscopy. In R. perezi, numerous terminals contacting the SCO cells in a synapse-like (synaptoid, hemisynaptic) manner bore the label, whereas a different population of endings was devoid of the tracer, indicating that in this species the SCO receives a dual neural input, one of pineal origin, the other of unknown source and nature. In the SCO of C. auratus, neither labeled nor unlabeled synapse-like contacts were found. Thus, in this latter species, a direct neural input to the SCO is missing. It is concluded that the secretory activity of the SCO can be controlled by different mechanisms in different species, and that more than one neural input mechanism may operate in the same species.     

Intermediate stages in the disassembly of synaptic ribbons in cone photoreceptors of the crucian carp,Carassius carassius

Synaptic ribbons are trilaminated plate-shaped presynaptic densities of certain types of receptor cells and neurons. In cone photoreceptors, these structures dissassemble and reassemble in response to light and to a variety of other stimuli. We used the lithium-ionenhanced disassembly and reassembly of synaptic ribbons to characterize structural intermediates in these cyclic changes. A few minutes after exposure of isolated retinas from the crucian carp (Carassius carassius) to lithium, ribbons fragmented into 50-nm-sized dense globular structures. These small spheres were concentrically surrounded by synaptic vesicles attached to them by stalk-like fine bridging filaments. Disassembly always started at the free cytoplasmic edges of the ribbons and proceeded toward the membrane-associated edges. As the disassembly process never started at the membraneanchored site, synaptic ribbons appeared to be polarized structures with functionally different ends. Spheres were subjected to further depolymerization. They disintegrated into clusters of small granular material and disappeared after ca. 45 min of lithium treatment. Spheres were not observed during the reassembly of synaptic ribbons, indicating that the assembly of synaptic ribbons proceeds via smaller subunits.