Application of fluorescent substance to the analysis of growth performance in Antarctic bivalve, Laternula elliptica

The shells of the Antarctic bivalve, Laternula elliptica, contain considerable information about their growth history and environmental changes. Growth rate determination in Laternula elliptica was attempted using a fluorescent substance, tetracycline, as a growth marker. The specimens were exposed to tetracycline solution of 200mg/ι for periods of 18 to 30h at about 0-2℃ without food. A distinct and narrow yellow fluorescent line was identified from the umbonal part to the ventral margin in all animals examined. This is the first success of fluorescent substance marking under the condition of low temperature and in Antarctic species. In the umbonal region, especially in the chondrophore, relatively rapid growth was observed. In the central part, a lower growth rate was observed. The growth rate of this species is not necessarily low in comparison with the temporal or tropical species. The combination of fluorescent marker and growth increment analyses will provide a powerful tool in estimating the benthic animal production, which is important information to understand the Antarctic ecosystem

The genus Boccardia (Polychaeta: Spionidae) associated with mollusc shells on the south coast of South Africa

Three species of Boccardia (B. polybranchia, B. pseudonatrix and B. proboscidea) were associated with mollusc shells on the south and south-east coasts of South Africa. Boccardia polybranchia was widely distributed along the coast and falls within the known distribution range of this species. Comparisons with material from other, international, locations showed that some specimens have been misidentified. No characters could be found to characterize distinct species for different regions within the range of B. polybranchia, as currently recognized. Boccardia pseudonatrix was found only at the most eastern site, increasing its known distribution range. Boccardia proboscidea, a non-indigenous species, was found only on abalone farms and was most abundant in the west

Morphological, Developmental, and Ecological Characteristics of the Suctorian Ciliate Ephelota gigantea (Ciliophora, Phyllopharyngea, Ephelotidae) Found on Cultured Wakame Seaweed in Northeastern Japan

Wakame seaweed is an important aquatic resource in Iwate Prefecture. However, a suctorian Ephelota gigantea sometimes causes great damage to wakame culture. Since little is known about the biological characteristics of E. gigantea, its detailed morphology and temporal change of biological characteristics during the 2010 culture season were investigated. Scanning electron microscope observations showed that E. gigantea had different striation patterns on the stalk; there was a swell made of cement by which the stalk was attached to wakame firmly; and the buds had cilia arranged in concentric circles about a ring in the center of the ventral side. A suctorian parasite was found to infect E. gigantea, and the infection seemed to have decreased drastically the attached density of E. gigantea on wakame. Cell size of parasite-infected E. gigantea individuals was larger than that of uninfected individuals, probably because larger E. gigantea has larger surface area for attachment of the parasite. Cyst formation or conjugating individuals were not observed

CK20 Positive Large-cell Neuroendocrine Carcinoma Presenting with Skin Metastases

We present a case of cytokeratin (CK) 20-positive large cell neuroendocrine carcinoma (LCNEC) presenting with multiple skin metastases as the primary manifestation. The patient was a 55-year-old man who presented with a one- month history of subcutaneous skin colored nodules of various sizes on his trunk. Pathologic examination of the skin revealed a nested and solid proliferation of large undifferentiated cells with vesicular nuclei and prominent nucleoli. Tumor cells were found to be immunohistochemically positive for CK 20, chromogranin A, synaptophysin, and CD56. Based on these features, the tumor was diagnosed as a large cell neuroendocrine carcinoma with multiple skin metastases. Computed tomographic (CT) imaging found metastatic foci in the liver, pleura, bone, and lymph nodes. We were unable to identify the primary site of origin. To the best of our knowledge, this is the first case of a large cell neuroendocrine carcinoma with a primary manifestation of multiple skin metastases

A Kennicutt-Schmidt Law for Intervening Absorption Line Systems

We argue that most strong intervening metal absorption line systems, where the rest equivalent width of the MgII 2796A line is >0.5A, are interstellar material in, and outflowing from, star-forming disks. We show that a version of the Kennicutt-Schmidt law is readily obtained if the MgII equivalent widths are interpreted as kinematic broadening from absorbing gas in outflowing winds originating from star-forming galaxies. Taking a phenomenological approach and using a set of observational constraints available for star-forming galaxies, we are able to account for the density distribution of strong MgII absorbers over cosmic time. The association of intervening material with star-forming disks naturally explains the metallicity and dust content of strong MgII systems as well as their high HI column densities, and does not require the advection of metals from compact star-forming regions into the galaxy halos to account for the observations. We find that galaxies with a broad range of luminosities can give rise to absorption of a given rest-equivalent width, and discuss possible observational strategies to better quantify true galaxy-absorber associations and further test our model. We show that the redshift evolution in the density of absorbers closely tracks the star formation history of the universe and that strong intervening systems can be used to directly probe the physics of both bright and faint galaxies over a broad redshift range. By identifying strong intervening systems with galaxy disks and quantifying a version of the Kennicutt-Schmidt law that applies to them, a new probe of the interstellar medium is found which provides complementary information to that obtained through emission studies of galaxies. Implications of our results for galaxy feedback and enrichment of the intergalactic medium are discussed. [abridged]Comment: 23 pages, 15 figure

Dissolution dominating calcification process in polar pteropods close to the point of aragonite undersaturation

Thecosome pteropods are abundant upper-ocean zooplankton that build aragonite shells. Ocean acidification results in the lowering of aragonite saturation levels in the surface layers, and several incubation studies have shown that rates of calcification in these organisms decrease as a result. This study provides a weight-specific net calcification rate function for thecosome pteropods that includes both rates of dissolution and calcification over a range of plausible future aragonite saturation states (Omega_Ar). We measured gross dissolution in the pteropod Limacina helicina antarctica in the Scotia Sea (Southern Ocean) by incubating living specimens across a range of aragonite saturation states for a maximum of 14 days. Specimens started dissolving almost immediately upon exposure to undersaturated conditions (Omega_Ar,0.8), losing 1.4% of shell mass per day. The observed rate of gross dissolution was different from that predicted by rate law kinetics of aragonite dissolution, in being higher at Var levels slightly above 1 and lower at Omega_Ar levels of between 1 and 0.8. This indicates that shell mass is affected by even transitional levels of saturation, but there is, nevertheless, some partial means of protection for shells when in undersaturated conditions. A function for gross dissolution against Var derived from the present observations was compared to a function for gross calcification derived by a different study, and showed that dissolution became the dominating process even at Omega_Ar levels close to 1, with net shell growth ceasing at an Omega_Ar of 1.03. Gross dissolution increasingly dominated net change in shell mass as saturation levels decreased below 1. As well as influencing their viability, such dissolution of pteropod shells in the surface layers will result in slower sinking velocities and decreased carbon and carbonate fluxes to the deep ocean

Shell structure characteristics of the thecosomatous pteropods in the Indian sector of the Antarctic Ocean

第2回極域科学シンポジウム　共通セッション「海氷圏の生物地球化学」 11月16日（水） 統計数理研究所 3階リフレッシュフロ

Biological strategy for the fabrication of highly ordered aragonite helices: The microstructure of the cavolinioidean gastropods

The Cavolinioidea are planktonic gastropods which construct their shells with the so-called aragonitic helical fibrous microstructure, consisting of a highly ordered arrangement of helically coiled interlocking continuous crystalline aragonite fibres. Our study reveals that, despite the high and continuous degree of interlocking between fibres, every fibre has a differentiated organic-rich thin external band, which is never invaded by neighbouring fibres. In this way, fibres avoid extinction. These intra-fibre organic-rich bands appear on the growth surface of the shell as minuscule elevations, which have to be secreted differentially by the outer mantle cells. We propose that, as the shell thickens during mineralization, fibre secretion proceeds by a mechanism of contact recognition and displacement of the tips along circular trajectories by the cells of the outer mantle surface. Given the sizes of the tips, this mechanism has to operate at the subcellular level. Accordingly, the fabrication of the helical microstructure is under strict biological control. This mechanism of fibre-by-fibre fabrication by the mantle cells is unlike that any other shell microstructure.Funding was provided by Research Projects CGL2013-48247-P of the Spanish Ministerio de Economía y Competitividad (MINECO) and Fondo Europeo de Desarrollo Regional (FEDER), and P10-RNM6433 of the Andalusian Consejería de Economía, Investigación, Ciencia y Empleo, of the Junta de Andalucía, and by the Research Group RNM363 (latter Institution)

Integrated frequency comb laser with narrow intrinsic optical linewidth based on a dielectric waveguide feedback circuit

We present an integrated hybrid semiconductor-dielectric (InP-Si$_3$N$_4$) waveguide laser that generates frequency combs at a wavelength around 1.5 $\mu$m with a record-low intrinsic optical linewidth of 34 kHz. This is achieved by extending the cavity photon lifetime using a low-loss dielectric waveguide circuit. In our experimental demonstration, the on-chip, effective optical path length of the laser cavity is extended to 6 cm. The resulting linewidth narrowing shows the high potential of on-chip, highly coherent frequency combs with direct electrical pumping, based on hybrid and heterogeneous integrated circuits making use of low-loss dielectric waveguides