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1.
What happens when an animal is injured and loses important structures? Some animals simply heal the wound, whereas others are able to regenerate lost parts. In this study, we report a previously unidentified strategy of self-repair, where moon jellyfish respond to injuries by reorganizing existing parts, and rebuilding essential body symmetry, without regenerating what is lost. Specifically, in response to arm amputation, the young jellyfish of Aurelia aurita rearrange their remaining arms, recenter their manubria, and rebuild their muscular networks, all completed within 12 hours to 4 days. We call this process symmetrization. We find that symmetrization is not driven by external cues, cell proliferation, cell death, and proceeded even when foreign arms were grafted on. Instead, we find that forces generated by the muscular network are essential. Inhibiting pulsation using muscle relaxants completely, and reversibly, blocked symmetrization. Furthermore, we observed that decreasing pulse frequency using muscle relaxants slowed symmetrization, whereas increasing pulse frequency by lowering the magnesium concentration in seawater accelerated symmetrization. A mathematical model that describes the compressive forces from the muscle contraction, within the context of the elastic response from the mesoglea and the ephyra geometry, can recapitulate the recovery of global symmetry. Thus, self-repair in Aurelia proceeds through the reorganization of existing parts, and is driven by forces generated by its own propulsion machinery. We find evidence for symmetrization across species of jellyfish (Chrysaora pacifica, Mastigias sp., and Cotylorhiza tuberculata).The moon jelly, Aurelia aurita, is one of the most plentiful jellyfish in oceans across the world (Fig. 1A). This translucent, saucer-shaped jelly is easily recognizable by the four crescent-shaped gonads on its umbrella. The moon jelly varies greatly in size, from a few inches to a foot (13). Ranging from tropical seas to subarctic regions, from the open ocean to brackish estuaries, the moon jelly occupies diverse habitats (46). It can even thrive in dirty, polluted, acidified, warm, and oxygen-poor waters (710). Presently, jelly blooms have been increasing in size and frequency worldwide, which has been interpreted as a troubling sign of a disturbed ocean ecosystem (11, 12).Open in a separate windowFig. 1.Life cycle and anatomy of Aurelia aurita. (A) Adult Aurelia. The blue color is due to lighting. Image courtesy of Wikimedia Commons/Hans Hillewaert. Image © Hans Hillewaert. (B) Aurelia life cycle. Fertilized eggs develop into larval planulae, which settle and develop into polyps. Seasonally, or in the right conditions, the polyps metamorphose into strobilae and release free-swimming, juvenile jellyfish (a process called strobilation). The young jellyfish, called ephyrae, grow into medusae in 3–4 wk. Reprinted with permission from ref. 13. (C) A juvenile green sea turtle preying on Aurelia at Playa Tamarindo, Puerto Rico. Image courtesy of R. P. van Dam. (D) An Aurelia ephyra has eight radially symmetrical arms, surrounding the manubrium at the center. At the end of each arm is a light- and gravity-sensing organ, called rhopalium. (E) The epithelium of ephyra is composed of two cell layers, the ectoderm-derived epidermis that faces the outer side and the endoderm-derived gastrodermis that lines the gastric cavity. Between the two layers is the gelatinous, viscoelastic mesoglea. Embedded in the subumbrellar side (mouth side) is the coronal muscle (green).Aurelia belongs to the class Scyphozoa, of the ancient phylum Cnidaria, which includes corals, hydras, siphonophores, and box jellyfish (13, 14). Cnidarians are unified by common characteristics, such as radial symmetry, dipoblasticity, diffuse nerve nets, mesoglea, and the stinging cells, or cnidocytes, which give the group its name. Aurelia, and many other Scyphozoan jellyfish, have a dimorphic life cycle with two adult forms: the sexually reproducing, free-swimming medusa, and the asexually reproducing, sessile polyp (Fig. 1B). Fertilized eggs develop into ciliated planulae that settle and mature into polyps. The polyps reproduce asexually through budding, or metamorphose and strobilate to produce juvenile jellyfish, called ephyrae. The ephyrae mature into medusae as bell tissues grow between the arms and reproductive structures develop. Transition into medusa may proceed over 1 mo in the laboratory (with abundant feeding), or longer in the wild. The ephyra stage is hardy and can withstand months of starvation (15).Injury is common in marine invertebrates. Examining 105 studies, Lindsay (16) showed that, at any given time, about 33–47% of the benthic fauna is injured. Some cited studies recorded entire starfish populations with at least one injured arm. Injury may be due to numerous factors, including partial predation, autotomy, cannibalism, competitive interaction, and human activities. Jellyfish have many known predators. A well-studied group of predators are the sea turtles (e.g., the leatherback and the loggerhead; Fig. 1C). Juvenile sea turtles have been observed biting into foot-wide jellyfish, and adults gorge on an average of 261 jellyfish per day (12). In addition, over 124 species of fish, 11 species of birds, several species of shrimps, sea anemones, corals, and crabs are reported to assail Aurelia (1720). Barnacles have been reported to catch and digest newly strobilated ephyrae (21).Here, we ask how Aurelia responds to injuries. Marine invertebrates are known for their regenerative ability. Reported cases of regenerating marine organisms include jellyfish, sponges, corals, ctenophores, sea anemones, clams, polychaetes, starfish, and brittlestars (14, 16, 2226). Isolated striated muscle from hydromedusae can transdifferentiate to regenerate various cell types (27). The polyps of Aurelia, and a number of other species, can regenerate tentacles, stolonts, and hydrants (2831), and an entire polyp can regrow from a single polyp tentacle (32). In this study, we investigated the repair capacity in the free-swimming forms of Aurelia and discovered that Aurelia have evolved a fast strategy of self-repair, one that does not involve regenerating lost body parts.  相似文献   
2.
水母蜇伤是最常见的海洋生物伤,其发生率随着近年来环境变化引起的水母爆发性增长在不断上升。水母毒素对心血管、血液、神经、肌肉等具有多种生物毒性,其作用机制不明确,水母蜇伤防治也以对症处理为主。注重水母蜇伤临床症状、救治措施与水母毒素纯化鉴定、作用机制之间的相互联系,将加速水母毒素研究的整体推进。  相似文献   
3.
Dermatitis caused by contact with tentacles of jellyfish was studied on 25 volunteers. Two tentacles cut from a living jellyfish, Carybdea rastonii, were applied on each of the forearms and skin reactions were observed. All volunteers complained of severe pain, which lasted from 10 min to 8 hrs. Erythema and wheal appeared within 3 to 4 min and enlarged for 15 to 20 min. Erythema subsided within 24 hrs to 3 days in all but two individuals. Seven to 13 days after the application, linear erythema and papulo-vesicular lesions with pruritus were observed on the forearms of 15 out of 25 volunteers tested. These flare-up lesions lasted for one week leaving slight pigmentation. Histological findings from the flare-up lesions corresponded to those of allergic contact dermatitis. The lymphocyte response to the jellyfish venom in the subjects who had recurring lesions was greater than that in either the subjects with no recurring lesions or the control group, who was never exposed to jellyfish.  相似文献   
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6.
Jellyfish stings have become more prevalent on account of larger commercial presence along coastal waterways. Stings are referred to as envenomations, due to the process of a neurotoxic venom being injected into the victim at the site of the sting. These events are usually mild, and for the most part, confined to local hypersensitivity reactions at the site of the injury. Certain species of jellyfish, however, have been associated with more severe, systemic insults including muscle cramping, respiratory distress, hypotension, circulatory collapse and death. One such example of a more potent venom is the Portuguese man-of-war. Most case reports of Portuguese man-of-war envenomations do not involve local soft tissue necrosis. The purpose of this case report is to present such a consequence after a jellyfish sting to the dorsum of the foot. A large area of skin necrosis developed after an envenomation that required extensive debridement and skin grafting.  相似文献   
7.
Two of the most abundant proteins found in the nematocysts of the box jellyfish Chironex fleckeri have been identified as C. fleckeri toxin-1 (CfTX-1) and toxin-2 (CfTX-2). The molecular masses of CfTX-1 and CfTX-2, as determined by SDS-PAGE, are approximately 43 and 45 kDa, respectively, and both proteins are strongly antigenic to commercially available box jellyfish antivenom and rabbit polyclonal antibodies raised against C. fleckeri nematocyst extracts. The amino acid sequences of mature CfTX-1 and CfTX-2 (436 and 445 residues, respectively) share significant homology with three known proteins: CqTX-A from Chiropsalmus quadrigatus, CrTXs from Carybdea rastoni and CaTX-A from Carybdea alata, all of which are lethal, haemolytic box jellyfish toxins. Multiple sequence alignment of the five jellyfish proteins has identified several short, but highly conserved regions of amino acids that coincide with a predicted transmembrane spanning region, referred to as TSR1, which may be involved in a pore-forming mechanism of action. Furthermore, remote protein homology predictions for CfTX-2 and CaTX-A suggest weak structural similarities to pore-forming insecticidal delta-endotoxins Cry1Aa, Cry3Bb and Cry3A.  相似文献   
8.
目的 初步分离发形霞水母触手提取物并探讨其生物学活性.方法采用自溶、离心的方法去除发形霞水母触手刺丝囊并获取触手提取物.通过阶段梯度阳离子交换色谱,应用0%.20%,40%,100%B液4种比例洗脱液将触手提取物分成4个组分,分别观察分离各组分的溶血、心血管等活性,并与触手提取物平行对比分析.结果成功分离到具有溶血、心血管活性的发形霞水母触手提取物,4个洗脱组分中,0%B液组分无上述3种活性,20%B液组分具有溶血活性、40%B液组分具有心血管活性,而100%B液组分则含有色素.结论通过阳离子交换色谱.初步将发形霞水母触手提取物中具有溶血活性、心血管活性以及色素等组分分离开来.为后续进一步纯化其单一活性组分打下基础.  相似文献   
9.
Despite the medical urgency presented by cubozoan envenomations, ineffective and contradictory first-aid management recommendations persist. A critical barrier to progress has been the lack of readily available and reproducible envenomation assays that (1) recapitulate live-tentacle stings; (2) allow quantitation and imaging of cnidae discharge; (3) allow primary quantitation of venom toxicity; and (4) employ rigorous controls. We report the implementation of an integrated array of three experimental approaches designed to meet the above-stated criteria. Mechanistically overlapping, yet distinct, the three approaches comprised (1) direct application of test solutions on live tentacles (termed tentacle solution assay, or TSA) with single image- and video-microscopy; (2) spontaneous stinging assay using freshly excised tentacles overlaid on substrate of live human red blood cells suspended in agarose (tentacle blood agarose assays, or TBAA); and (3) a “skin” covered adaptation of TBAA (tentacle skin blood agarose assay, or TSBAA). We report the use and results of these assays to evaluate the efficacy of topical first-aid approaches to inhibit tentacle firing and venom activity. TSA results included the potent stimulation of massive cnidae discharge by alcohols but only moderate induction by urine, freshwater, and “cola” (carbonated soft drink). Although vinegar, the 40-year field standard of first aid for the removal of adherent tentacles, completely inhibited cnidae firing in TSA and TSBAA ex vivo models, the most striking inhibition of both tentacle firing and subsequent venom-induced hemolysis was observed using newly-developed proprietary formulations (Sting No More™) containing copper gluconate, magnesium sulfate, and urea.  相似文献   
10.
Cartilage is a tissue with a very low capability of self‐repair and the search for suitable materials supporting the chondrogenic phenotype and thus avoiding fibrotic dedifferentiation for matrix‐associated chondrocyte transplantation (MACI) is ongoing. Jellyfish collagen was thought to be a suitable material mainly because of its good availability and easy handling. Collagen was extracted from jellyfish Rhopilema esculentum and the spreading of porcine chondrocytes on two (2D) and three dimensional (3D) collagen matrices examined in comparison with vertebrate collagens, placenta collagen and a commercially available matrix from porcine collagen type I (Optimaix®). In 2D, most chondrocytes kept their round shape on jellyfish collagen and vertebrate collagen type II compared with vertebrate collagen type I. This was also confirmed in 3D experiments, where chondrocytes preserved their phenotype on jellyfish collagen, as indicated by high collagen II/(II + I) ratios (≥54 % and ~92 % collagen type II in mRNA and protein, respectively) and no proliferation during 28 days of cultivation. These observations were discussed with a view to potential structural differences of jellyfish collagen, which might influence the integrin‐mediated adhesion mechanisms of vertebrate cells on jellyfish collagen. This probably results from a lack of integrin‐binding sites and the existence of an alternative binding mechanism such that cells kept their round shape on jellyfish collagen, preventing chondrocytes from dedifferentiation. Thus, collagen from R. esculentum is a very suitable and promising material for cartilage tissue engineering. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
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