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Paula José Ricardo Sun Derek Pissarra Vasco Narvaez Pauline Rosa Rui Grutter Alexandra S. Sikkel Paul C. 《Coral reefs (Online)》2021,40(2):535-542
Coral Reefs - Gnathiid isopods, common fish ectoparasites, can affect fish physiology, behaviour and survival. Gnathiid juveniles emerge from the benthos to feed on fish blood. In the Caribbean,... 相似文献
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Tropical labrids Hemigymnus melapterus sampled underwater had low plasma levels of cortisol, glucose, and lactate. Plasma cortisol levels were elevated by capture stress within 5–6 min, while glucose and lactate levels were not. Plasmalevels of cortisol and glucose increased after 2–4 h of handling and transport to the laboratory. Levels of cortisol and glucose fell with laboratory acclimation back to values similar to those found in wild fish. Parasitism by gnathiid isopods across an order of magnitude of isopod numbers had no effect on plasma levels of cortisol or glucose. Thus, H. melapterus has a stress response similar to that shown by temperate species, and relatively high parasite loads are not apparently stressful to fish in the wild. This may be related to the counterproductive effects of physiological stress responses on the immune system or behaviour-modulated processes that counter parasitic invasion. 相似文献
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Lucas Luthy Markus G Grutter Peer R E Mittl 《The Journal of biological chemistry》2002,277(12):10187-10193
Colonization of the gastric mucosa with the spiral-shaped Gram-negative proteobacterium Helicobacter pylori is probably the most common chronic infection in humans. The genomes of H. pylori strains J99 and 26695 have been completely sequenced. Functional and three-dimensional structural information is available for less than one third of all open reading frames. We investigated the function and three-dimensional structure of a member from a family of cysteine-rich hypothetical proteins that are unique to H. pylori and Campylobacter jejuni. The structure of H. pylori cysteine-rich protein (Hcp) B possesses a modular architecture consisting of four alpha/alpha-motifs that are cross-linked by disulfide bridges. The Hcp repeat is similar to the tetratricopeptide repeat, which is frequently found in protein/protein interactions. In contrast to the tetratricopeptide repeat, the Hcp repeat is 36 amino acids long. HcpB is capable of binding and hydrolyzing 6-amino penicillinic acid and 7-amino cephalosporanic acid derivatives. The HcpB fold is distinct from the fold of any known penicillin-binding protein, indicating that the Hcp proteins comprise a new family of penicillin-binding proteins. The putative penicillin binding site is located in an amphipathic groove on the concave side of the molecule. 相似文献
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Conor?M.?JonesEmail author Alexandra?S.?Grutter Thomas?H.?Cribb 《Coral reefs (Online)》2004,23(4):521-529
Adult bucephalid trematodes (Digenea) generally only occur in piscivorous fish. Within labrid fishes they are very rare, however, we have found them in labrid cleaner fish that feed on the ectoparasites of fish. We surveyed 969 labrid fishes from the tropical Pacific and found bucephalids only in cleaners (Labroides dimidiatus, L. bicolor, and Bodianus axillaris) and none in piscivores. The prevalences of bucephalids in L. dimidiatus at Lizard Island, Heron Island, Orpheus Island (all on the Great Barrier Reef), New Caledonia, and Moorea (French Polynesia) were 51, 47, 67, 56, and 67%, respectively. All of the L. bicolor examined from Moorea were infected. Bucephalids were highly prevalent in all size classes of L. dimidiatus from Lizard Island. Bucephalids were found in a 1.6-cm long juvenile L. dimidiatus, in which, piscivory is highly unlikely. We examined the literature on the worldwide bucephalid fauna in labrids and all hosts were found to be cleaners (Symphodus tinca, S. mediterraneus, L. dimidiatus, L. bicolor, and Bodianus axillaris) except Notolabrus parilus, whose ecology is unknown. We suggest that cleaners eat bucephalid metacercariae directly from the exterior surface of client fish during cleaning interactions. This is the first evidence of digeneans in the diet of L. dimidiatus, and the first study to show this novel form of parasite transmission where infective stages are eaten as a result of cleaning behaviour. Cleaning-mediated parasite transmission may result in behavioural modification of second intermediate hosts because clients and parasites both benefit from transmission. If the infection is costly to cleaners and acquired during cheating behaviour, then this parasite might regulate mutualism. Alternatively, if infective stages are targeted, infection by these bucephalids may be a negative consequence of an honest foraging strategy.Communicated by: P. F. Sale 相似文献
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Nilsson GE Ostlund-Nilsson S Penfold R Grutter AS 《Proceedings. Biological sciences / The Royal Society》2007,274(1606):79-85
The fastest swimming fishes in relation to size are found among coral reef fish larvae on their way to settle on reefs. By testing two damselfishes, Chromis atripectoralis and Pomacentrus amboinensis, we show that the high swimming speeds of the pre-settlement larvae are accompanied by the highest rates of oxygen uptake ever recorded in ectothermic vertebrates. As expected, these high rates of oxygen uptake occur at the cost of poor hypoxia tolerance. However, hypoxia tolerance is needed when coral reef fishes seek nocturnal shelter from predators within coral colonies, which can become severely hypoxic microhabitats at night. When the larvae settle on the reef, we found that they go through a striking respiratory transformation, i.e. the capacity for rapid oxygen uptake falls, while the ability for high-affinity oxygen uptake at low oxygen levels is increased. This transition to hypoxia tolerance is needed when they settle on the reef; this was strengthened by our finding that small resident larvae of Acanthochromis polyacanthus, a damselfish lacking a planktonic larval stage, do not display such a transition, being well adapted to hypoxia and showing relatively low maximum rates of oxygen uptake that change little with age. 相似文献
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Cleaning behaviour is deemed a mutualism, however the benefit of cleaning interactions to client individuals is unknown. Furthermore, mechanisms that may shift fish community structure in the presence of cleaning organisms are unclear. Here we show that on patch reefs (61–285 m2) which had all cleaner wrasse Labroides dimidiatus (Labridae) experimentally removed (1–5 adults reef−1) and which were then maintained cleaner-fish free over 8.5 years, individuals of two site-attached (resident) client damselfishes (Pomacentridae) were smaller compared to those on control reefs. Furthermore, resident fishes were 37% less abundant and 23% less species rich per reef, compared to control reefs. Such changes in site-attached fish may reflect lower fish growth rates and/or survivorship. Additionally, juveniles of visitors (fish likely to move between reefs) were 65% less abundant on removal reefs suggesting cleaners may also affect recruitment. This may, in part, explain the 23% lower abundance and 33% lower species richness of visitor fishes, and 66% lower abundance of visitor herbivores (Acanthuridae) on removal reefs that we also observed. This is the first study to demonstrate a benefit of cleaning behaviour to client individuals, in the form of increased size, and to elucidate potential mechanisms leading to community-wide effects on the fish population. Many of the fish groups affected may also indirectly affect other reef organisms, thus further impacting the reef community. The large-scale effect of the presence of the relatively small and uncommon fish, Labroides dimidiadus, on other fishes is unparalleled on coral reefs. 相似文献
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Normal mode analysis suggests a quaternary twist model for the nicotinic receptor gating mechanism 下载免费PDF全文
Taly A Delarue M Grutter T Nilges M Le Novère N Corringer PJ Changeux JP 《Biophysical journal》2005,88(6):3954-3965
We present a three-dimensional model of the homopentameric alpha7 nicotinic acetylcholine receptor (nAChR), that includes the extracellular and membrane domains, developed by comparative modeling on the basis of: 1), the x-ray crystal structure of the snail acetylcholine binding protein, an homolog of the extracellular domain of nAChRs; and 2), cryo-electron microscopy data of the membrane domain collected on Torpedo marmorata nAChRs. We performed normal mode analysis on the complete three-dimensional model to explore protein flexibility. Among the first 10 lowest frequency modes, only the first mode produces a structural reorganization compatible with channel gating: a wide opening of the channel pore caused by a concerted symmetrical quaternary twist motion of the protein with opposing rotations of the upper (extracellular) and lower (transmembrane) domains. Still, significant reorganizations are observed within each subunit, that involve their bending at the domain interface, an increase of angle between the two beta-sheets composing the extracellular domain, the internal beta-sheet being significantly correlated to the movement of the M2 alpha-helical segment. This global symmetrical twist motion of the pentameric protein complex, which resembles the opening transition of other multimeric ion channels, reasonably accounts for the available experimental data and thus likely describes the nAChR gating process. 相似文献
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