4,583 research outputs found
Merkel cell polyomavirus is prevalent in a subset of small cell lung cancer: a study of 31 patients
Progress On Research Regarding Ecology and Biodiversity of Coastal Fisheries and Nektonic Species and Their Habitats Within Coastal Landscapes
This paper aims to highlight the new research and significant advances in our understanding of links between coastal habitat quality/quantity/diversity and the diversity of fisheries species and other mobile aquatic species (hereafter nekton) that use them within coastal landscapes. This topic is quite diverse owing to the myriad of habitat types found in coastal marine waters and the va-riety of life history strategies fisheries species and nekton use in these environments. Thus, we focus our mini-review on five selective but relevant topics, habitat templates, essential fish habitat, habitat mosaics/habitat connectivity, transitory/ephemeral habitat, and the emerging/maturing approaches to the study of fish-habitat systems as a roadmap to its development. We have highlighted selected important contributions in the progress made on each topic to better identify and quantify landscape scale interactions between living biota and structured habitats set within a dynamic landscape
Intergalactic Globular Clusters
We confirm and extend our previous detection of a population of intergalactic
globular clusters in Abell 1185, and report the first discovery of an
intergalactic globular cluster in the nearby Virgo cluster of galaxies. The
numbers, colors and luminosities of these objects can place constraints on
their origin, which in turn may yield new insights to the evolution of galaxies
in dense environments.Comment: 2 pages, no figures. Talk presented at JD6, IAU General Assembly XXV,
Sydney, Australia, July 2003, to appear in Highlights of Astronomy, Vol. 1
Behavioral Analysis of Cuttlefish Traveling Waves and Its Implications for Neural Control
SummaryTraveling waves (from action potential propagation to swimming body motions or intestinal peristalsis) are ubiquitous phenomena in biological systems and yet are diverse in form, function, and mechanism. An interesting such phenomenon occurs in cephalopod skin, in the form of moving pigmentation patterns called âpassing cloudsâ [1]. These dynamic pigmentation patterns result from the coordinated activation of large chromatophore arrays [2]. Here, we introduce a new model system for the study of passing clouds, Metasepia tullbergi, in which wave displays are very frequent and thus amenable to laboratory investigations. The mantle of Metasepia contains four main regions of wave travel, each supporting a different propagation direction. The four regions are not always active simultaneously, but those that are show synchronized activity and maintain a constant wavelength and a period-independent duty cycle, despite a large range of possible periods (from 1.5Â s to 10 s). The wave patterns can be superposed on a variety of other ongoing textural and chromatic patterns of the skin. Finally, a traveling wave can even disappear transiently and reappear in a different position (âblinkâ), revealing ongoing but invisible propagation. Our findings provide useful clues about classes of likely mechanisms for the generation and propagation of these traveling waves. They rule out wave propagation mechanisms based on delayed excitation from a pacemaker [3] but are consistent with two other alternatives, such as coupled arrays of central pattern generators [3] and dynamic attractors on a network with circular topology [4]
Description of Three Species of \u3ci\u3eIsorchis\u3c/i\u3e (Digenea: Atractotrematidae) from Australia
Three species of Isorchis Durio and Manter, 1969 are described from Australian waters. Isorchis megas sp. nov. is described from the spotbanded scat, Selenotoca multifasciata (Richardson), off Western Australia (WA) and Northern Territory (NT); Isorchis currani sp. nov. is described from S. multifasciata off NT; and Isorchis anomalus sp. nov. is described from the milkfish, Chanos chanos ForsskĂ„l, off WA. Isorchis megas sp. nov. can be differentiated from the other species of Isorchis by possessing a single, large egg that is greater than 20% of the body length; having a shorter body (the largest specimen is less than 500 ÎŒm); and utilizing a scatophagid rather than a chanid host. Isorchis currani sp. nov. can be differentiated from all other species of Isorchis in possessing an irregular-shaped genital pore rather than one that is circular to oblong. A Bayesian inference analysis of partial 28S rDNA sequences of the three new species of Isorchis and 30 other haploporoids revealed (1) the monophyly of the Atractotrematidae Yamaguti, 1939, (2) the two species of Isorchis infecting S. multifasciata were each other\u27s closest relative, and (3) that Isorchis was most closely related to Pseudomegasolena Machida and and Komiya, 1976 rather than Atractotrema Goto and Ozaki, 1929 although sequence data are not yet available for a member of Pseudisorchis Ahmad, 1985
Endohelminth parasites of some midwater and benthopelagic stomiiform fishes from the northern Gulf of Mexico
: Mesopelagic fishes represent significant ecological links between mesozooplankton and the larger pelagic squids, fishes, and marine mammals. As such, these fishes also play a significant role as intermediate or paratenic hosts for parasites that require a crustacean intermediate host and mature in marine mammals or pelagic fishes. We examined a total of 208 individuals representing 5 species of Sternoptychidae and 88 individuals representing 2 species of Phosichthyidae from 20 locations in the northern Gulf of Mexico (nGOM). Six of the 7 species we examined are mesopelagic and one species was benthopelagic. We found the larval stages of Anisakis brevispiculata, A. typica, Hysterothylacium fortalezae (all Nematoda: Ascaridoidea); Bolbosoma sp. (Acanthocephala: Polymorphidae); and Tetraphyllidea (Cestoda) plus an immature specimen of Brachyphallus sp. (Digenea). Molecular sequencing was used to identify the ascaridoids and Bolbosoma sp. and to confirm the identification of 3 host sternoptychid species. The mesopelagic fishes hosted A. brevispiculata (that matures in pygmy and dwarf sperm whales) and H. fortalezae (that matures in pelagic fishes, primarily mackerels), whereas the benthopelagic species was parasitized by A. typica (that matures in dolphins). We suggest this pattern of infection indicates a pelagic life-cycle for A. brevispiculata and H. fortalezae and a demersal life-cycle for A. typica. Our study represents the first published sequences from the nGOM for the fishes Argyropelecus aculeatus, Maurolicus weitzmani, and Polyipnus clarus and the first molecular identification of larval ascaridoids from mesopelagic fishes in the nGOM
The Relative Ages of the Globular Cluster Subpopulations in M87
Relative ages for the globular cluster (GC) subpopulations in the Virgo giant
elliptical galaxy M87 (NGC 4486) have been determined from Stroemgren
photometry obtained with WFPC2 on board HST. Using a variety of population
synthesis models, and assuming the GC mass at the turnover of the luminosity
function is the same for both subpopulations, differential ages have been
determined from the observed magnitudes at the turnover of the globular cluster
luminosity function and from the mean color of each subpopulation. We measure
an age difference between the two subpopulations of 0.2 +/- 1.5 (systematic)
+/- 2 (random) Gyr, in the sense that the blue GCs are formally older. Thus, to
within our measurement errors, the two subpopulations are found to be coeval.
Combined with previous spectroscopic age determinations for M87 GCs, our
results favor a picture in which the GCs associated with this galaxy are formed
at high redshift, and within a period of a few Gyr.Comment: 5 pages, 2 postscript figures. Accepted for publication in ApJ
Letter
Temporal Dynamics of Lipid and Fatty Acid Characteristics of Gulf Menhaden, \u3ci\u3eBrevoortia patronus\u3c/i\u3e in the Northern Gulf of Mexico
Gulf Menhaden, Brevoortia patronus, in the northern Gulf of Mexico support a large commercial fishery and are thought to play an important trophic role in the coastal ecosystem. The temporal dynamics of both fatty acid and oil content have a direct impact on the value of Gulf Menhaden to predators and to the fishery. In this work, we describe how oil content of Gulf Menhaden varies with season, sex, age, condition, and tissue and investigate how fatty acid composition of mature (137.5 mm FL) female tissues varies with season, month, and tissue type. We found pronounced temporal (January to October) variation in mean oil content ranging from 0.062 to 0.579 mg gâ1 that exhibited a significant (p \u3c 0.001) seasonal pattern. We observed significant differences in oil content between tissue (muscle vs. ovary) of mature females and these exhibited a significant seasonal contrast, indicating that females were provisioning eggs in the fall. PERMANOVA analysis indicated the existence of significant differences (p \u3c 0.001) in the composition of fatty acids of muscle tissue collected in different months. Mean eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and long chain polyunsaturated fatty acid (LC-PUFA) levels exhibited significant seasonal differences (p \u3c 0.05), and in the case of DHA and LC-PUFA, both exhibited mean tissue-specific differences (p \u3c 0.05). This work indicates that the value of Gulf Menhaden as prey and a fishery resource in the region varies during the year and we propose that trophic models of the Gulf of Mexico ecosystem should account for this variation
Reproductive Dynamics of Gulf Menhaden (\u3ci\u3eBrevoortia patronus\u3c/i\u3e) in the Northern Gulf of Mexico: Effects On Stock Assessments
Gulf menhaden (Brevoortia patronus) produce one of the largest U.S. fisheries, yet information on reproductive dynamics of the stock is sparse. Males and females reach 50% maturity at 140.8 and 137.2 mm fork length, respectively and recruit into the commercial fishery at this size. Analysis of fishery-dependent data from 1964 through 2014 indicated that somatic condition was lower during the late 1980s and late 2000s and that reproductively active fish from 2014 were significantly larger and had greater gonadosomatic index values than those from 1964 through 1970. Histological analysis performed on fish from 2014 through 2016 revealed spawning-capable and actively spawning fish of both sexes from early October through midMarch. Females have indeterminate fecundity, are batch spawners, and spawn every 2.1-4.3 days, although oocyte recruitment shows some characteristics of determinate fecundity. Mean relative batch fecundity was 107.8 eggs/g ovary-free body weight (standard error 17.1). Estimates from age-structured assessment models based on updated fecundity and maturity measures resulted in a 100-1000x greater production of eggs than previous estimates. Model output, including the number-at-age, age-specific fishing-induced mortality, and spawners-per-recruit are sensitive to alterations in age-specific annual fecundity. Therefore, updated estimates of Gulf menhaden reproductive dynamics can affect assessments of the stock
Erection of the Haploporid Genus \u3ci\u3eLitosaccus\u3c/i\u3e n. g. and Its Phylogenetic Relationship within the Haploporidae Nicoll, 1914
Litosaccus n. g. is erected for Paralecithobotrys brisbanensis Martin, 1974 n. comb. for which an amended description is given. The new genus is morphologically similar to the haploporine Lecithobotrys Looss, 1902 but with a more elongate and cylindrical body; an infundibuliform oral sucker; a thin-walled hermaphroditic sac; a shallow genital atrium; and unequal, cylindrical, and elongated caeca. It also resembles Pseudolecithobotrys Blasco-Costa, Gibson, Balbuena, Raga & Kostadinova, 2009, but the only member of that genus has a hermaphroditic sac that is twice the length of the ventral sucker, a hermaphroditic duct with intensely staining cuboidal cells, an elongate testis, and single or paired caeca. A Bayesian inference analysis of partial 28S rDNA sequences of L. brisbanensis and 24 other haploporoids revealed that L. brisbanensis grouped with other haploporines and placed Intromugil Overstreet & Curran, 2005 in a clade with the chalcinotrematine Saccocoelioides Szidat, 1954 rather than the other seven tested waretrematine species. This analysis represents the first phylogenetic study of the Haploporidae Nicoll, 1914 that incorporates a haploporine from outside of the Mediterranean Sea
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