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1.
Rhopalium development in Aurelia aurita ephyrae   总被引:4,自引:0,他引:4  
Rhopalia of developing ephyrae were examined using the SEM and TEM at 24 h intervals following strobilation induction. Kinocilia are shorter in the ephyra stage than in polyps. A few ephyra-type kinocilia are found in rhopalia as early as 24 h after induction, before a distinct rhopalium is seen. By 72 h, the shorter kinocilia predominate and are almost as numerous as in ephyrae (120 h). Many of the kinocilia are associated with mechanoreceptor cells (MR) found in the rhopalia. These MR cells are compared to those reported for medusae. Although newly released ephyrae lack a touch plate, the MR cells in their rhopalia along with the statocyst and neuromuscular system apparently enable these organisms to detect and respond to gravity.  相似文献   

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Radiochromatographic studies of 131I-treated Aurelia polypsrevealed synthesis of three compounds tentatively identifiedas monoiodotyrosine (MIT), diiodotyrosine (DIT), and thyroxine(T4). One compound, MIT, is found within 8 hr after 131I administration,before the detection of DIT or T4 which appear within 24 hr.T4 is not usually detected after 48 hr although MIT and DITwere found up to the segmentation period. None of the compoundswere detected in ephyrae treated with 131I for 24 hr. Administration of low dosages of the goitrogens, thiourea,,propylthiouracil, and potassium thiocyanate, in conjunctionwith iodide, prevented strobilation induction. Radiochromatographyof jellyfish given the goitrogens and 131I revealed a reduceduptake of iodide and an impairment of the synthesis of the iodinatedcompounds. Jellyfish use thyroxine directly for strobilatioa inductionas demonstrated by 131I - labeled T4 administration. The T4was detected in the polyps up to the 48-hr period of strobilationduring which time some of the T4 was excreted into the medium,as was some 131I. The fact that T4, synthesis has thus far been found only instrobilating forms of Aurelia suggests that T4 is involved primarilywith the differentiation of new structures which occurs duringstrobilation.  相似文献   

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《Current biology : CB》2014,24(3):263-273
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Matveev IV 《Tsitologiia》2005,47(5):431-435
The body of Aurelia aurita, as well as other diploblasts, consists of two epithelial layers: ectodermal and gastral epithelium. These two tissues are separated by mesoglea, or extracellular matrix. In most coelenterates mesoglea is acellular. In A. aurita mesogleal cells are scattered in mesoglea. Differential display PCR was used to compare mRNA pools from ectodermal epithelium, gastral epithelium and mesoglea. 4 novel gene fragments were cloned and sequenced. According to RTPCR results, one of these fragments is differentially expressed in the ectodermal epithelium.  相似文献   

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Grazing by the jellyfish, Aurelia aurita, on microzooplankton   总被引:1,自引:0,他引:1  
The medusa of the scyphozoan, Aurelia aurita, is a seasonallyimportant predator of copepods and fish larvae in coastal watersbut little is known about its grazing on microzooplanltton.Medusae preferentially remove large (  相似文献   

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Gut content analyses on field-caught Aurelia aurita showed bothquantitative and qualitative change in diet as a function ofmedusa size. Larger medusae tended towards greater numbersand diversity of prey (up to 1550 individual prey representingas many as 13 different prey groups). We also found that medusasize was a good predictor of prey diversity recovered from themedusa gut. While a shift toward greater prey diversity inlarger medusae might be explained by increased contact rateswith 'rare' prey taxa, we also found size-based prey selectivitychanges in A. aurita. We used in situ gut content data to describeselectivity by A. aurita for three prey types representing varyingdegrees of swimming or escape velocity. Fish eggs were usedas a non-swiming prey, and small (  相似文献   

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Protein composition of mesoglea of the scyphomedusa Aurelia aurita was revealed in SDS-PAGE. Some major bands are visible in mesoglea of a mature medusa: 30, 45-47, 85 kDa, three bands between 100-200 kDa, and several bands with molecular weights > 300 kDa. Polyclonal antisera RA45/47 against protein 45 kDa were raised. RA45/47 react with 45-47 kDa protein in mesogleal sample and protein 120 kDa in mesogleal cells on immunoblot. Immunohistochemical analysis of A. aurita histological sections of young and mature medusae showed antigen localization in mesogleal cell granules and in the apical part of ectodermal cells. In mature medusae, the antigen was localized also in elastic fibers. We can conclude that in A. aurita mesogleal cells, along with ectodermal cells, take part in the formation of extracellular matrix of mesoglea.  相似文献   

10.
The population dynamics of the scyphomedusa Aurelia aurita inSouthampton Water is characterized. Strobilation, indicatedby the presence of 1 mm ephyrae, occurred from the end of Januaryto the middle of March. Maximum abundances of up to 8.71 m–3occurred soon after ephyrae release, after which numbers declinedsteadily until the end of June, when the population was absentfrom Southampton Water. The residence time of 3–4 monthsis somewhat less than that reported in many other areas, includingKiel Bight and Gullmarfjord. The carbon biomass of A.auritaaccounted for 92–97% of the predominant gelatinous biomass(A.aurita, Pleurobrachia pileus and Phialidium hemisphericum)in the upper estuary, and this reached a maximum of 30.2 mgC m–3 in May 1990 and 27.6 mg C m–3 in June 1991.Coincident with increased water temperature and mesozooplanktonabundance during May, growth rates increased from 0.02–0.30mm day–1 to a peak of 4.8 mm day–1, with a maximumbell diameter of 120–140 mm reached in late May/earlyJune. Size to maturity was variable, although the smallest medusaobserved to be ‘ripe’, i.e. containing dividingeggs and planula larvae in the brood sacs on the oral arms,were 64–71 mm. Aurelia aurita is believed to be endemicto Southampton Water, but because of the double high water inthe area, short flushing rates of between 4.5 and 20 days maybe responsible for such short residence times of Aurelia medusae.The effects of strong NE winds were considered as factors governingthe distribution of medusae in years of atypical temporal abundance.  相似文献   

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The in situ behavior of three scyphomedusan species was videorecorded by scuba divers in natural daytime lighting with minimalinterference to the medusae. The mean percentage of time thatindividual medusae spent swimming ranged from 93 to 100%. Therewere no significant differences in the percent time spent swimmingbetween life stages of a species (ephyra, adult) or betweenspecies. The predominance of swimming activity by medusae indicatesthat swimming, and hence the creation of fluid motions responsiblefor prey entrainment and capture, plays a widespread functionalrole in feeding by scyphomedusae.  相似文献   

16.
The scyphozoan Aurelia aurita is recognized as a key player in marine ecosystems and a driver of ecosystem change. It is thus intensely studied to address ecological questions, although its associations with microorganisms remain so far undescribed. In the present study, the microbiota associated with A. aurita was visualized with fluorescence in situ hybridization (FISH) analysis, and community structure was analyzed with respect to different life stages, compartments, and populations of A. aurita by 16S rRNA gene amplicon sequencing. We demonstrate that the composition of the A. aurita microbiota is generally highly distinct from the composition of communities present in ambient water. Comparison of microbial communities from different developmental stages reveals evidence for life stage-specific community patterns. Significant restructuring of the microbiota during strobilation from benthic polyp to planktonic life stages is present, arguing for a restructuring during the course of metamorphosis. Furthermore, the microbiota present in different compartments of the adult medusa (exumbrella mucus and gastric cavity) display significant differences, indicating body part-specific colonization. A novel Mycoplasma strain was identified in both compartment-specific microbiota and is most likely present inside the epithelium as indicated by FISH analysis of polyps, indicating potential endosymbiosis. Finally, comparison of polyps of different populations kept under the same controlled laboratory conditions in the same ambient water showed population-specific community patterns, most likely due the genetic background of the host. In conclusion, the presented data indicate that the associated microbiota of A. aurita may play important functional roles, e.g., during the life cycle.  相似文献   

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Aurelia aurita is a cosmopolite species of scyphomedusae. Its anatomy and life cycle are well investigated. This work provides a detailed study on development and structure of A. aurita planula before and during its metamorphosis. Intravital observations and histology study during the settlement and metamorphosis of the planulae demonstrated that the inner manubrium lining of primary polyp (gastroderm) develops from the ectoderm of the planula posterior end. The spatial and temporal dynamics of serotonergic cells from the early embryonic stages until the formation of the primary polyp were studied for the first time. In addition, the distribution of tyrosinated tubulin and neuropeptide RF-amide at different stages of A. aurita development was traced.  相似文献   

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With the aid of the Aurelia metamorphosis test system, the acute and subtle developmental and behavioral effects of X irradiation in the presence and absence of thyroxine on the Norfolk Aurelia aurita were described. Radiation doses were 0 (control), 50, 100, 150, 200, and 400 Gy. Morphology of the ephyrae, and statolith and rhopalia numbers were recorded using the light microscope. Developmental abnormalities of the polyps and ephyrae were recorded with the scanning electron microscope and light microscope. Major findings from this investigation were the absence of rhopalia and statoliths in ephyrae at 150 and 200 Gy, a reduction in pulses per minute in the ephyrae at 100, 150, and 200 Gy, a reduction in ephyrae released at 150, 200, and 400 Gy, and the development of polyp monsters. There was a significantly higher frequency of polyp monsters in the group exposed to thyroxine prior to radiation than in the thyroxine-free group prior to radiation.  相似文献   

20.
Cathy H. Lucas 《Hydrobiologia》2001,451(1-3):229-246
The scyphozoan Aurelia aurita (Linnaeus) is a cosmopolitan species, having been reported from a variety of coastal and shelf sea environments around the world. It has been extensively studied over the last 100 years or so, and examination of the literature reveals three striking features: (1) the presence of populations in a wide range of environmental conditions; (2) large inter-population differences in abundance and life history patterns over large and small spatial scales; and (3) inter-annual variability in various aspects of its population dynamics. A. aurita is clearly a highly flexible species that can adapt to a wide range of environmental conditions. While various physiological and behavioural characteristics explain how A. aurita populations can take advantage of their surrounding environment, they do not explain what governs the observed temporal and spatial patterns of abundance, and the longevity or lifespan of populations. Understanding these features is necessary to predict how bloom populations might form. In a given habitat, the distribution and abundance of benthic marine invertebrates have been found to be maintained by four factors: larval recruitment (sexual reproduction), migration, mortality and asexual reproduction. The aims of this review are to determine the role of reproduction and life history strategies of the benthic and pelagic phases of A. aurita in governing populations of medusae, with special attention given to the dynamic interaction between A. aurita and its surrounding physical and biological environment.  相似文献   

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