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The Potent Respiratory System of Osedax mucofloris (Siboglinidae, Annelida) - A Prerequisite for the Origin of Bone-Eating Osedax?  [PDF]
Randi S. Huusgaard, Bent Vismann, Michael Kühl, Martin Macnaugton, Veronica Colmander, Greg W. Rouse, Adrian G. Glover, Thomas Dahlgren, Katrine Worsaae
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0035975
Abstract: Members of the conspicuous bone-eating genus, Osedax, are widely distributed on whale falls in the Pacific and Atlantic Oceans. These gutless annelids contain endosymbiotic heterotrophic bacteria in a branching root system embedded in the bones of vertebrates, whereas a trunk and anterior palps extend into the surrounding water. The unique life style within a bone environment is challenged by the high bacterial activity on, and within, the bone matrix possibly causing O2 depletion, and build-up of potentially toxic sulphide. We measured the O2 distribution around embedded Osedax and showed that the bone microenvironment is anoxic. Morphological studies showed that ventilation mechanisms in Osedax are restricted to the anterior palps, which are optimized for high O2 uptake by possessing a large surface area, large surface to volume ratio, and short diffusion distances. The blood vascular system comprises large vessels in the trunk, which facilitate an ample supply of oxygenated blood from the anterior crown to a highly vascularised root structure. Respirometry studies of O. mucofloris showed a high O2 consumption that exceeded the average O2 consumption of a broad line of resting annelids without endosymbionts. We regard this combination of features of the respiratory system of O. mucofloris as an adaptation to their unique nutrition strategy with roots embedded in anoxic bones and elevated O2 demand due to aerobic heterotrophic endosymbionts.
Temporal variation and lack of host specificity among bacterial endosymbionts of Osedax bone worms (Polychaeta: Siboglinidae)  [cached]
Salathé Rahel M,Vrijenhoek Robert C
BMC Evolutionary Biology , 2012, DOI: 10.1186/1471-2148-12-189
Abstract: Background Osedax worms use a proliferative root system to extract nutrients from the bones of sunken vertebrate carcasses. The roots contain bacterial endosymbionts that contribute to the nutrition of these mouthless and gutless worms. The worms acquire these essential endosymbionts locally from the environment in which their larvae settle. Here we report on the temporal dynamics of endosymbiont diversity hosted by nine Osedax species sampled during a three-year investigation of an experimental whale fall at 1820-m depth in the Monterey Bay, California. The host species were identified by their unique mitochondrial COI haplotypes. The endosymbionts were identified by ribotyping with PCR primers specifically designed to target Oceanospirillales. Results Thirty-two endosymbiont ribotypes associated with these worms clustered into two distinct bacterial ribospecies that together comprise a monophyletic group, mostly restricted to deep waters (>1000 m). Statistical analyses confirmed significant changes in the relative abundances of host species and the two dominant endosymbiont ribospecies during the three-year sampling period. Bone type (whale vs. cow) also had a significant effect on host species, but not on the two dominant symbiont ribospecies. No statistically significant association existed between the host species and endosymbiont ribospecies. Conclusions Standard PCR and direct sequencing proved to be an efficient method for ribotyping the numerically dominant endosymbiont strains infecting a large sample of host individuals; however, this method did not adequately represent the frequency of mixed infections, which appears to be the rule rather than an exception for Osedax individuals. Through cloning and the use of experimental dilution series, we determined that minority ribotypes constituting less than 30% of a mixture would not likely be detected, leading to underestimates of the frequency of multiple infections in host individuals.
A remarkable diversity of bone-eating worms (Osedax; Siboglinidae; Annelida)
Robert C Vrijenhoek, Shannon B Johnson, Greg W Rouse
BMC Biology , 2009, DOI: 10.1186/1741-7007-7-74
Abstract: Phylogenetic analyses identified 17 distinct evolutionary lineages. Levels of sequence divergence among the undescribed lineages were similar to those found among the named species. The 17 lineages clustered into five well-supported clades that also differed for a number of key morphological traits. Attempts to determine the evolutionary age of Osedax depended on prior assumptions about nucleotide substitution rates. According to one scenario involving a molecular clock calibrated for shallow marine invertebrates, Osedax split from its siboglinid relatives about 45 million years ago when archeocete cetaceans first appeared and then diversified during the late Oligocene and early Miocene when toothed and baleen whales appeared. Alternatively, the use of a slower clock calibrated for deep-sea annelids suggested that Osedax split from its siboglinid relatives during the Cretaceous and began to diversify during the Early Paleocene, at least 20 million years before the origin of large marine mammals.To help resolve uncertainties about the evolutionary age of Osedax, we suggest that the fossilized bones from Cretaceous marine reptiles and late Oligocene cetaceans be examined for possible trace fossils left by Osedax roots. Regardless of the outcome, the present molecular evidence for strong phylogenetic concordance across five separate genes suggests that the undescribed Osedax lineages comprise evolutionarily significant units that have been separate from one another for many millions of years. These data coupled with ongoing morphological analyses provide a solid foundation for their future descriptions as new species.Osedax, a recently discovered genus of bone-eating marine worms, are proving to be far more diverse and geographically widespread than initially realized. The genus was described from two newly discovered species found on whalebones recovered from 2,893 m depth in Monterey Bay, California [1]. Subsequently, three additional species were described from dept
Feeding behavior of the cirratulid Cirriformia filigera (Delle Chiaje, 1825) (Annelida: Polychaeta)
Pardo, E. V.;Amaral, A. C. Z.;
Brazilian Journal of Biology , 2004, DOI: 10.1590/S1519-69842004000200014
Abstract: observations of the feeding behavior of cirriformia filigera (delle chiaje, 1825) (annelida: polychaeta) from the intertidal zone of s?o francisco and engenho d'água beaches (s?o sebasti?o, state of s?o paulo) were made in the laboratory. this species, like other cirratulids, is a deposit feeder, feeding mainly on sediment surface with the aid of its grooved and ciliated palps, which are used to capture food particles. the worm lies just beneath the substrate surface in a j-shaped tube. when feeding, it extends up to 4 palps over the sediment surface, capturing food particles which pass down the groove of each palp directly to the mouth. only fine sand grains are ingested. the worm frequently extends 4 branchial filaments into the overlying water for aeration. when it moves with the prostomium sideways, it collects and transports sand grains that pass backwards along its ventral region until reaching the middle part of its body. next, the parapodia and palps move the sand grains to the dorsal posterior end of the animal, covering this area with sand. some sand grains are also ingested as the worm moves.
The worm in the world and the world in the worm
Mark Blaxter, Dee R Denver
BMC Biology , 2012, DOI: 10.1186/1741-7007-10-57
Abstract: See research article http://www.biomedcentral.com/1741-7007/10/59 webciteCaenorhabditis elegans, the free-living nematode tamed as a new model organism by Sydney Brenner in the 1960s [1], has become a keystone species in the ecology of scientific knowledge. The ease with which C. elegans can be grown, manipulated and observed has driven biomedical research into new areas and 'the worm' has been a silent collaborator in three Nobel prizes, and thousands of research articles over the past 50 years. While primarily chosen because of the ease of genetic analysis, interest in C. elegans was redoubled when it became the first animal to have its whole genome sequenced [2]. The genome revealed much about the basic machinery of being an animal, and the specifics of being a nematode. One of the greatest surprises was the discovery of over 1,280 putative chemoreceptor genes [3]. This exuberant repertoire (even dogs have only approximately 1,200 olfactory and chemoreceptor genes) suggests that the nematodes' wild environment must be extraordinarily complex. However, the true ecology of C. elegans has remained enigmatic. In the laboratory it is clearly a boom-and-bust 'r-strategist' - a single self-fertilizing hermaphrodite (with an occasional rare male), given enough agar plates, Escherichia coli food and willing lab assistants, could produce over a billion great-granddaughters in a month. But where does it live, feed and reproduce in the wild? And how has its wild environment shaped the biology now explored in high-throughput investigations in labs worldwide? Marie-Anne Félix and Fabien Duveau report in BMC Biology [4] new findings from nematode populations in orchards near Paris that provide some answers to these questions.While often called a 'soil nematode', C. elegans has rarely been isolated from soils [5]. Sydney Brenner's C. elegans, the iconic N2 strain, came from mushroom compost in Bristol, UK. Like many related nematodes, C. elegans can enter a facultative diapause
Polychaeta Organism Density in Na Thap Estuary  [cached]
Chokchai Lueangthuwapranit,Niwadee Saheem
International Journal of Biology , 2011, DOI: 10.5539/ijb.v3n4p30
Abstract: Polychaeta is a class of macrobenthic fauna found in marine and estuarine environments. As part of a larger study of environment health impacts associated with the operation of a thermal power plant in the Na Thap River in Songkhla, Thailand, we examined bi-monthly organism densities of Polychaeta measured at each of five sites along the river downstream from the power plant for before and after its operation began. These densities, after log-transformation to reduce skewness with appropriate handling of zeroes, were found to be related to salinity measured at the same sites on the same occasions. There was also a statistically significant trend in the Polychaeta densities over the whole period.
Analysis and geometry on worm domains  [PDF]
Steven G. Krantz,Marco M. Peloso
Mathematics , 2007,
Abstract: We describe recent work on the Bergman kernel of the (non-smooth) worm domain in several complex variables. An asymptotic expansion is obtained for the Bergman kernel. Mapping properties of the Bergman projection are studied. Irregularity properties of the kernal at the boundary are established. This is an expository paper, and considerable background is provided. Discussion of the smooth worm is also included.
Paradigmatic and Exploration of Blind Worm  [PDF]
Yellamandaiah Gogula, E.Jhansi Rani
International Journal of Engineering Trends and Technology , 2012,
Abstract: Active worms pose major security threats to the Internet. This is due to the ability of active worms to propagate in an automated fashion as they continuously compromise computers on the Internet. Active worms evolve during their propagation and thus pose great challenges to defend against them. In this paper, we investigate a new class of active worms, referred to as Tarnen Worm (C-Worm in short). The C-Worm is different from traditional worms because of its ability to intelligently manipulate its scan traffic volume over time. Thereby, the C-Worm camouflages its propagation from existing worm exploration systems based on analyzing the propagation traffic generated by worms. We analyze characteristics of the C-Worm and conduct a comprehensive comparison between its traffic and non-worm traffic (background traffic). We observe that these two types of traffic are barely distinguishable in the time domain. However, their distinction is clear in the frequency domain, due to the recurring manipulative nature of the C-Worm. Motivated by our observations, we design a novel spectrum-based scheme to detect the C-Worm. Our scheme uses the Power Spectral Density (PSD) distribution of the scan traffic volume and its corresponding Spectral Flatness Measure (SFM) to distinguish the C-Worm traffic from background traffic. Using a comprehensive set of exploration metric s and real-world traces as background traffic, we conduct extensive performance evaluations on our proposed spectrum-based exploration scheme. The performance data clearly demonstrates that our scheme can effectively detect the C-Worm propagation. Furthermore, we show the generality of our spectrum-based scheme in effectively detecting not only the C-Worm, but traditional worms as well.
Intelligent System for Worm Detection  [PDF]
Ibrahim Farag,Mohammed A. Shouman,Tarek S. Sobh,Heba El-Fiqi
International Arab Journal of e-Technology , 2009,
Abstract: Worms are on the top of malware threats attacking computer system although of the evolution of worms detectiontechniques. Early detection of unknown worms is still a problem. This paper produce a method for detecting unknown wormsbased on local victim information. The proposed system uses Artificial Neural Network (ANN) for classifying worm/ nonwormtraffic and predicting the percentage of infection in the infected network. This prediction can be used to support decisionmaking process for network administrator to respond quickly to worm propagation in an accurate procedure.
Regularity of dbar on worm domains  [PDF]
Dariush Ehsani
Mathematics , 2014,
Abstract: A solution operator to the $\bar{\partial}$-equation is constructed on unbounded worm domains, $D_{\beta}$. Regularity estimates are proven showing the operator preserves regularity of the data. The operator may be viewed as a continuous mapping among appropriate subpaces of $W^s(D_{\beta})$, which depend on a rotational invariance of the domains.
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