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Eel Anguilla Japonica (eel + anguilla_japonica)
Kinds of Eel Anguilla Japonica Selected AbstractsAxoneme-dependent tubulin modifications in singlet microtubules of the Drosophila sperm tailCYTOSKELETON, Issue 4 2008Henry D. Hoyle Abstract Drosophila melanogaster sperm tubulins are posttranslationally glutamylated and glycylated. We show here that axonemes are the substrate for these tubulin C-terminal modifications. Axoneme architecture is required, but full length, motile axonemes are not necessary. Tubulin glutamylation occurs during or shortly after assembly into the axoneme; only glutamylated tubulins are glycylated. Tubulins in other testis microtubules are not modified. Only a small subset of total Drosophila sperm axoneme tubulins have these modifications. Biochemical fractionation of Drosophila sperm showed that central pair and accessory microtubules have the majority of poly-modified tubulins, whereas doublet microtubules have only small amounts of mono- and oligo-modified tubulins. Glutamylation patterns for different ,-tubulins experimentally assembled into axonemes were consistent with utilization of modification sites corresponding to those identified in other organisms, but surrounding sequence context was also important. We compared tubulin modifications in the 9 + 9 + 2 insect sperm tail axonemes of Drosophila with the canonical 9 + 2 axonemes of sperm of the sea urchin Lytichinus pictus and the 9 + 0 motile sperm axonemes of the eel Anguilla japonica. In contrast to Drosophila sperm, L. pictus sperm have equivalent levels of modified tubulins in both doublet and central pair microtubule fractions, whereas the doublets of A. japonica sperm exhibit little glutamylation but extensive glycylation. Tubulin C-terminal modifications are a prevalent feature of motile axonemes, but there is no conserved pattern for placement or amount of these modifications. We conclude their functions are likely species-specific. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source] Application of otolith microchemistry to estimate the migratory history of Japanese eel Anguilla japonica on the Sanriku Coast of JapanJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2004A. Kotake Summary The age and migratory history of the Japanese eel, Anguilla japonica Temminck & Schlegel, collected in Miyako Bay along the Sanriku coast of Japan, was examined using the otolith microstructure and analysis of strontium (Sr) and calcium (Ca) concentrations conducted with wavelength dispersive X-ray spectrometry by an electron microprobe. The line analysis of Sr : Ca ratios along the life history transect of each otolith showed a peak (ca. 15,17 × 10,3) which corresponded with the period of their leptocephalus and early glass eel stages in the ocean. The mean Sr : Ca ratios from the elver mark to the otolith edge indicated that there were eels with several general categories of migratory history, including sea eels that never entered freshwater (average Sr : Ca ratios, ,6.0 × 10,3), and others that entered freshwater for brief periods but returned to the estuary or bay. This evidence of the occurrence of sea eels in this northern area indicates that Japanese eels of the Sanriku coast do not necessarily migrate into freshwater rivers during recruitment as do glass eels at the beginning of their growth phase; even those that do enter freshwater may later return to the marine environment. Thus, anguillid eel migrations into freshwater are clearly not an obligatory migratory pathway, but rather a facultative catadromy with seawater or estuarine residents as an ecophenotype. [source] Oceanic migration and spawning of anguillid eelsJOURNAL OF FISH BIOLOGY, Issue 9 2009K. Tsukamoto Many aspects of the life histories of anguillid eels have been revealed in recent decades, but the spawning migrations of their silver eels in the open ocean still remains poorly understood. This paper overviews what is known about the migration and spawning of anguillid species in the ocean. The factors that determine exactly when anguillid eels will begin their migrations are not known, although environmental influences such as lunar cycle, rainfall and river discharge seem to affect their patterns of movement as they migrate towards the ocean. Once in the ocean on their way to the spawning area, silver eels probably migrate in the upper few hundred metres, while reproductive maturation continues. Although involvement of a magnetic sense or olfactory cues seems probable, how they navigate or what routes they take are still a matter of speculation. There are few landmarks in the open ocean to define their spawning areas, other than oceanographic or geological features such as oceanic fronts or seamounts in some cases. Spawning of silver eels in the ocean has never been observed, but artificially matured eels of several species have exhibited similar spawning behaviours in the laboratory. Recent collections of mature adults and newly spawned preleptocephali in the spawning area of the Japanese eel Anguilla japonica have shown that spawning occurs during new moon periods in the North Equatorial Current region near the West Mariana Ridge. These data, however, show that the latitude of the spawning events can change among months and years depending on oceanographic conditions. Changes in spawning location of this and other anguillid species may affect their larval transport and survival, and appear to have the potential to influence recruitment success. A greater understanding of the spawning migration and the choice of spawning locations by silver eels is needed to help conserve declining anguillid species. [source] Sympatric spawning of Anguilla marmorata and Anguilla japonica in the western North Pacific OceanJOURNAL OF FISH BIOLOGY, Issue 9 2009M. Kuroki Extensive collections were made of the larvae of the temperate Japanese eel Anguilla japonica and the tropical giant mottled eel Anguilla marmorata in an overlapping area of the North Equatorial Current region of the western North Pacific Ocean. Collections of 189 A. marmorata and > 2500 A. japonica larvae during nine surveys from 1991 to 2007 showed that these two anguillid eels have similar spawning areas just west of the southern West Mariana Ridge. In July to August 2006 and August 2007, morphologically and genetically identified A. marmorata preleptocephali were mainly collected between 14·5,15° N and 142,142·5° E, where A. japonica preleptocephali were also caught in some of the same net tows. Fewer A. marmorata preleptocephali, however, were collected (n = 31) compared to those of A. japonica (n = c. 165), and fewer small larvae of A. marmorata were collected per tow than A. japonica (n = 1,10 and 1,294, respectively), suggesting relatively smaller spawning aggregations of A. marmorata. The distribution of preleptocephali and small larvae was wider in longitude in A. marmorata (131, 143° E) than in A. japonica (137,143° E), while the latitudinal range was almost the same (12,17° N). Although spawning by these two species overlaps both spatially and temporally, the tropical eels of the North Pacific population of A. marmorata probably have a much longer spawning season with fewer spawners, at least in summer, and recruit to a much wider latitudinal range of growth habitats. [source] Medullary motor neurones associated with drinking behaviour of Japanese eelsJOURNAL OF FISH BIOLOGY, Issue 1 2003T. Mukuda A fluorescent dye, Evans blue (EB), was injected into the following seven drinking-associated muscles of the Japanese eel Anguilla japonica: the sternohyoid, third branchial, fourth branchial, opercular, pharyngeal, upper oesophageal sphincter and oesophageal body muscles. The sternohyoid muscle promotes ,ingestion', and the remaining muscles contribute to ,swallowing'. All neurones stained by EB were located ipsilaterally in the caudal medulla oblongata (MO) of the Japanese eel. Neurones projecting into the sternohyoid muscle were identified as those in the spino-occipital motor nucleus (NSO), and neurones projecting into the remaining muscles as those in the glossopharyngeal,vagal motor complex (GVC). Within the GVC, the neuronal arrangement was topological, and hence, ,swallowing' will be completed if the GVC neurones ,fire' progressively from rostral to caudal. These neurones in the NSO and GVC may use acetylcholine (ACh) as a neurotransmitter, as the EB-positive neurones in both nuclei were immunoreactive against anticholine acetyltransferase (anti-ChAT) antibody. Besides the MO, some somata in a ganglion of the vagal nerve were also stained by EB injected into the pharyngeal, the upper oesophageal sphincter and the oesophageal body muscles. The localization and the shape of the somata suggest that they are sensory neurones. These sensory neurones were not ChAT-immunoreactive. Combining these results, based on a model for ,swallowing' in mammals, a plausible model for central organization of ,drinking' in the Japanese eel is proposed, which suggests that ,drinking' in the fishes is regulated by the neuronal circuit for ,swallowing' in mammals. [source] Vitamin contents of eggs that produce larvae showing a high survival rate in the Japanese eel Anguilla japonicaAQUACULTURE RESEARCH, Issue 11 2009Hirofumi Furuita Abstract This paper describes the relationship between the egg vitamin concentrations and the egg quality in the Japanese eel Anguilla japonica. No notable relation was found between any vitamin and the fertilization rate. Hatching and survival rates of larvae, however, significantly increased with an elevated level of egg vitamin C (VC). In contrast to VC, the relation between vitamins E (VE) and A (VA) concentrations and survival rate showed a clear peak, with a reduced survival rate at both higher and lower vitamin concentrations. The ratio of VE to lipid or highly unsaturated fatty acid (HUFA) in eggs positively correlated with hatching and survival rates of larvae. High-quality (HQ) eggs were determined as eggs that produced larvae having a survival rate higher than 80% at 8 days post hatch, and low-quality (LQ) eggs were determined as eggs that did not hatch. The level of VC of HQ was significantly higher than LQ. The results of this study suggest that HQ eggs, which produce larvae having a high survival rate, must have high levels of VC and VE/HUFA ratio and contain optimum levels of VA and VE in Japanese eel. [source] | ||||||||||