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Light Organ (light + organ)
Selected AbstractsGlowworms: a review of Arachnocampa spp. and kinLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 3 2007V. B. Meyer-Rochow Abstract The term ,glowworm' is used in connection with the flightless females of lampyrid fireflies and to describe the luminescent larvae of certain fungus gnats that belong to the subfamilies Arachnocampinae, Keroplatinae and Macrocerinae of the dipteran family Keroplatidae. This review focuses on the luminescent larval fungus gnats. The weakly luminescent species of the Holarctic feed mainly on fungal spores, but some, such as Orfelia fultoni, have turned to a carnivorous diet. Larval Australian and New Zealand Arachnocampa spp. produce brighter in vivo (but not necessarily in vitro) lights, live in cool, damp and dark places and are exclusively predatory. They lure their prey (usually small flying insects) with the help of their blue-green light emissions towards snares consisting of vertical silk threads coated with sticky mucus droplets. Fungus gnats with similar ,fishing lines' are found in the Neotropics, but they are not luminescent. The larval stage is longest in the life cycle of Arachnocampa, lasting up to a year, depending on climatic conditions such as temperature and humidity as well as food supply. In A. luminosa, but not the Australian A. flava, female pupae and even female imagines are luminescent. However, it remains to be demonstrated whether it is the light of the female, a pheromone or both that attract the males. Light organs and the chemical reactions to produce light differ between the holarctic and the Australian/New Zealand species. Prey is attracted only by the glowworm's light; odours of the fishing lines or the glowworms themselves are not involved. Recognition of the prey by the glowworm involves mechano- and chemoreception. The eyes of both larval and adult glowworms are large and functional over a spectral range covering UV to green wavelengths. Adults are poor fliers, live only for a few days, have degenerate mouth parts and do not feed. Maintenance of glowworms in captivity is possible and the impact of tourism on glowworms in natural settings can be minimized through appropriate precautions. Copyright © 2007 John Wiley & Sons, Ltd. [source] Confocal microscopy of the light organ crypts in juvenile Euprymna scolopes reveals their morphological complexity and dynamic function in symbiosisJOURNAL OF MORPHOLOGY, Issue 5 2006Laura K. Sycuro Abstract In the hours to days following hatching, the Hawaiian bobtail squid, Euprymna scolopes, obtains its light-emitting symbiont, Vibrio fischeri, from the surrounding environment and propagates the bacteria in the epithelial crypts of a specialized light organ. Three-dimensional analyses using confocal microscopy revealed that each of the three crypts on either side of the juvenile light organ is composed of four morphological regions. Progressing from the lateral pore to the medial blind end of each crypt, the regions consist of 1) a duct, 2) an antechamber, 3) a bottleneck, and 4) a deep region. Only the deep region houses a persistent bacterial population, whereas the duct, antechamber, and bottleneck serve as conduits through which the bacteria enter during initial colonization and exit during diel venting, a behavior in which ,90% of the symbionts are expelled each dawn. Our data suggest that, like the duct, the antechamber and bottleneck may function to promote and maintain the specificity of the symbiosis. Pronounced structural and functional differences among the deep regions of the three crypts, along with previously reported characterizations of embryogenesis, suggest a continued developmental progression in the first few days after hatching. Taken together, the results of this study reveal a high degree of complexity in the morphology of the crypts, as well as in the extent to which the three crypts and their constituent regions differ in function during the early stages of the symbiosis. J. Morphol. © 2006 Wiley-Liss, Inc. [source] Why bacteria matter in animal development and evolutionBIOESSAYS, Issue 7 2010Sebastian Fraune Abstract While largely studied because of their harmful effects on human health, there is growing appreciation that bacteria are important partners for invertebrates and vertebrates, including man. Epithelia in metazoans do not only select their microbiota; a coevolved consortium of microbes enables both invertebrates and vertebrates to expand the range of diet supply, to shape the complex immune system and to control pathogenic bacteria. Microbes in zebrafish and mice regulate gut epithelial homeostasis. In a squid, microbes control the development of the symbiotic light organ. These discoveries point to a key role for bacteria in any metazoan existence, and imply that beneficial bacteria-host interactions should be considered an integral part of development and evolution. [source] Missing link in firefly bioluminescence revealed: NO regulation of photocyte respirationBIOESSAYS, Issue 11 2001Michael D. Greenfield Sexual communication in most species of fireflies is a male,female dialogue of precisely timed flashes of bioluminescent light. The biochemical reactions underlying firefly bioluminescence have been known for 30 years and are now exploited in biomedical assays and other commercial applications. Several aspects of flash regulation are also understood: flash rhythm is controlled by a central pattern generator, and individual flashes are neurally triggered, with octopamine serving as the transmitter. The molecular oxygen needed by the biochemical reactants is delivered by a network of tracheal arborizations extending throughout the light organ (lantern). However, the actual means by which oxygen quickly reaches the reactants packaged within specialized photocytes and the specific event(s) triggered by neural action have not been identified; termination of axons away from the photocytes has exacerbated the latter problem. A recent paper(1) by a consortium of cell and evolutionary biologists, however, reports that nitric oxide (NO), manufactured and released in response to neuronal discharge, is the missing link by which neural action in the firefly lantern yields a sudden flash of light. BioEssays 23:992,995, 2001. © 2001 John Wiley & Sons, Inc. [source] Peptidoglycan induces loss of a nuclear peptidoglycan recognition protein during host tissue development in a beneficial animal-bacterial symbiosisCELLULAR MICROBIOLOGY, Issue 7 2009Joshua V. Troll Summary Peptidoglycan recognition proteins (PGRPs) are mediators of innate immunity and recently have been implicated in developmental regulation. To explore the interplay between these two roles, we characterized a PGRP in the host squid Euprymna scolopes (EsPGRP1) during colonization by the mutualistic bacterium Vibrio fischeri. Previous research on the squid-vibrio symbiosis had shown that, upon colonization of deep epithelium-lined crypts of the host light organ, symbiont-derived peptidoglycan monomers induce apoptosis-mediated regression of remote epithelial fields involved in the inoculation process. In this study, immunofluorescence microscopy revealed that EsPGRP1 localizes to the nuclei of epithelial cells, and symbiont colonization induces the loss of EsPGRP1 from apoptotic nuclei. The loss of nuclear EsPGRP1 occurred prior to DNA cleavage and breakdown of the nuclear membrane, but followed chromatin condensation, suggesting that it occurs during late-stage apoptosis. Experiments with purified peptidoglycan monomers and with V. fischeri mutants defective in peptidoglycan-monomer release provided evidence that these molecules trigger nuclear loss of EsPGRP1 and apoptosis. The demonstration of a nuclear PGRP is unprecedented, and the dynamics of EsPGRP1 during apoptosis provide a striking example of a connection between microbial recognition and developmental responses in the establishment of symbiosis. [source] The GacA global regulator of Vibrio fischeri is required for normal host tissue responses that limit subsequent bacterial colonizationCELLULAR MICROBIOLOGY, Issue 3 2007Cheryl A. Whistler Summary Harmful and beneficial bacterium,host interactions induce similar host-tissue changes that lead to contrasting outcomes of association. A life-long association between Vibrio fischeri and the light organ of its host Euprymna scolopes begins when the squid collects bacteria from the surrounding seawater using mucus secreted from ciliated epithelial appendages. Following colonization, the bacterium causes changes in host tissue including cessation of mucus shedding, and apoptosis and regression of the appendages that may limit additional bacterial interactions. We evaluated whether delivery of morphogenic signals is influenced by GacA, a virulence regulator in pathogens, which also influences squid-colonization by V. fischeri. Low-level colonization by a GacA mutant led to regression of the ciliated appendages. However, the GacA mutant did not induce cessation of mucus shedding, nor did it trigger apoptosis in the appendages, a phenotype that normally correlates with their regression. Because apoptosis is triggered by lipopolysaccharide, we examined the GacA mutant and determined that it had an altered lipopolysaccharide profile as well as an increased sensitivity to detergents. GacA-mutant-colonized animals were highly susceptible to invasion by secondary colonizers, suggesting that the GacA mutant's inability to signal the full programme of light-organ responses permitted the prolonged recruitment of additional symbionts. [source] | ||||||||||