Flexible seaward migration of Dolly Varden Salvelinus malma in the Shiretoko Peninsula, Hokkaido, Japan
The migratory history of Dolly Varden Salvelinus malma was investigated in 30 streams in the Shiretoko Peninsula, Hokkaido, Japan, which is in the southern part of their distribution. Captured Dolly Varden were classified into two categories by their body coloration: silvery fish were thought to be an anadromous form, and non-silvery fish a fluvial form that remains in freshwater throughout its life. Forty-seven of 1,739 Dolly Varden collected in the spring and ten of 2,126 Dolly Varden collected in the autumn were silvery fish. Twenty silvery fish and 120 non-silvery fish were examined by analysis of otolith Sr:Ca ratio. Three silvery fish from autumn and 15 non-silvery fish had migrated to salt water or brackish water. The other specimens of silvery fish were regarded as smolt or pre-smolt before seaward migration. The present study suggests that Dolly Varden in the Shiretoko Peninsula have a flexible migratory history, where some of the non-silvery fish utilize marine environments while some individuals follow an anadromous life history.
Salmincola edwardsii (Copepoda: Lernaeopodidae) Parasitic on Southern Asian Dolly Varden, Salvelinus malma krascheninnikova, from Hokkaido Island, Japan, with the Southernmost Distribution Record of the Copepod in Asia
Females of the lernaeopodid copepod Salmincola edwardsii (Olsson, 1869) were found parasitizing the gill area of southern Asian Dolly Varden, Salvelinus malma krascheninnikova Taranetz, 1933, from four rivers (Rusha River, Rausu River, Shari River, Shibetsu River) in and near the Shiretoko Peninsula, eastern Hokkaido Island, Japan. The females are briefly described as the first record of S. edwardsii from Hokkaido Island and the southernmost distribution record for the species in Asia. The branchial chamber was the most frequently used site for attachment by the females, followed by the gill filaments and the inner surface of the operculum. The overall prevalence of infection was 42.1%, and intensity ranged from 1 to 6 (mostly 1 or 2). The species was not collected from the central and western regions of Hokkaido Island, and the restriction of its distribution to eastern Hokkaido Island is discussed in terms of anadromy of the host species. The impact of global climatic warming on the Hokkaido populations of S. edwardsii is also discussed.
Chemical, biological, and immunological characterization of mono- and diiodothyrotropin releasing factor.
Abstract Iodination of thyrotropin releasing factor (TRF) with chloramine-T and NaI at pH 7.5 produces both mono- and diiodo-TRF as well as unreacted TRF and I − . The four compounds can be separated by ion-exchange chromatography on SP-Sephadex C-25, using a stepwise gradient of 0.01 m MH 4 OAc at pH 3.5, 5.2 and 7.2. The monoiodo-TRF was characterized by nuclear magnetic resonance, mass spectra, and elemental analysis as [Im-5-iodo-His 2 ]-TRF while the diiodo-TRF was similarly characterized as [Im-2,5-diiodo-His 2 ]-TRF. Both iodination products showed no thyrotropin releasing activity at doses up to 1 μg in the in vivo mouse bioassay. The specific binding of mono- and diiodo-TRF was measured against three different TRF antisera. In the absence of TRF, antisera A and C bound more diiodo-TRF than monoiodo-TRF while antiserum B seemed to bind both tracers equally. In all cases steeper curves were produced when diiodo-TRF was displaced by synthetic TRF.