Rotational viscosity in ferroelectric liquid crystals estimated from transient light scattering and dielectric properties

A new method for the estimation of rotational viscosity of ferroelectric liquid crystals using transient light scattering (TSM) is reported. The relation between rotational viscosity, spontaneous polarization, and dielectric dispersion frequency is studied as a function of the racemization. The rotational viscosity is almost independent of spontaneous polarization and there is no obvious correlation between rotational viscosity and dispersion frequency. The dispersion frequency is confirmed to be inversely proportional to the square of the helical pitch. The rotational viscosity calculated from this relation is consistent with that from the new TSM method.This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in M. Ozaki, T. Hatai, K. Nakao, and K. Yoshino, Journal of Applied Physics 65, 3602 (1989) and may be found at https://doi.org/10.1063/1.342639

Fungi isolated from cultured eggs, alevins and broodfish of brown trout in a hatchery affected by saprolegniosis

P. 510-518The aquatic fungi cultured from eggs, alevins and broodfish of brown trout Salmo trutta belonged to the genus Saprolegnia and were identified as S. diclina, S. australis, S. ferax, S. furcata, S. hypogyna, S. unispora and S. parasitica. The species obtained from infected eggs and alevins were different to those from infected fish. Several Saprolegnia species were isolated from eggs and alevins, whereas all the isolates obtained from broodfish were the pathogenic S. parasitica.S

Branchiostegite melanization and microsporidia-like infection in cultured Macrobrachium rosenbergii in Thailand

In Thailand, farming the giant freshwater prawn, Macrobrachium rosenbergii, is a viable aquaculture industry. In 1995-96, giant freshwater prawns collected from grow out ponds located in Supanburi Province, Thailand showed severe branchiostegite melanization associated with poor growth and high cumulative mortality in affected ponds. The objective this study was to report the histopathological features of branchiostegite melanization and associated lesions in affected giant freshwater prawns. The gross lesions displayed by the collected prawns were bilateral branchiostegite melanization in the medial surfaces with normal underlying gill lamellae. Histopathological examination revealed a massive number of sporonts in the gill tissue causing a hyperinfection. Enlargement of the sporonts occurred in the gills. High magnification using a light microscope revealed massive round microsporidia-like spores in the sporonts measuring 1-2 m in diameter. The muscles of collected prawns were normal showing no signs of opaque cottony or milky white coloration. The hepatopancreas, however, were yellow in color. Positive Giemsa and PAS stained spores were found in hemocytes and cytoplasm of hepatopancreas cells. Because these results do not include electron-micrographic data, more observation is needed before the spores can be identified as microsporidia

A note on the fossil marine fauna dredged from the Japanese Seas

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Haliphthoros milfordensis isolated from eggs and larvae of mud crab (Scylla tranquebarica) in Sabah, Malaysia

Fungal infection occurred during mud crab spawning in a hatchery and caused almost 100% mortality in mud crab larvae after 5 days post-hatching. A fungus was isolated from eggs and larvae using PYGS agar and named IPMB 1603. During morphological identification, the strain IPMB 1603 was observed to produce a fragment inside the hyphae and the zoospores swam away from the tips of the discharge tube on several occasions, this closely resembling the genus Haliphthoros. Following comparisons made on the nucleotide sequence of the ITS1 region, the strain IPMB 1603 was identified belonging to a cluster of Haliphthoros milfordensis sharing 97-100% similarity. In this study, the strain IPMB 1603 was found to be an euryhaline fungus as the strain was able to grow on PYG agar containing NaCl. Strain IPMB 1603 only grew at certain salinity ranges, in which on PYGS agar contained sea water higher than 10 ppt. The optimum temperature range for fungal growth of strain IPMB 1603 was 30-35cC. Different growth rates were demonstrated at pH ranging from 4 to 9, but optimum growth was observed at pH 6 to 8. This is the first record of Haliphthoros milfordensis infection in Malaysia

First report of Lagenidium thermophilum isolated from eggs and larvae of mud crab (Scylla tranquebarica) in Sabah, Malaysia

In April 2014, marine Oomycetes were first isolated from mud crab Scylla tranquebarica eggs and larvae at the University Malaysia Sabah shrimp hatchery. A fungus was isolated from infected eggs and larvae using PYGS agar. It was thought that the same fungus infected both eggs and larvae; therefore, strain IPMB 1401 was randomly selected for further characterization in this study. The isolated fungus produced a discharge tube from the mycelium, and a vesicle was formed at the tip. The zoospores swam away after the vesicle separated from the discharge tube. The strain IPMB 1401 was classified as a Lagenidium sp., closely related to L. thermophilum based on the mode of zoospore release. The differences between the strains IPMB 1401 and pathogenic Lagenidium spp. isolated from marine crustaceans were compared in nucleotide sequence of ITS 1 region. As a result, the IPMB 1401 showed high similarity of 99-100% and belonged to the same cluster with L. thermophilum. Therefore, the strain IPMB 1401 was identified as L. thermophilum. This is the first report of Lagenidium infection in Malaysia

Haliphthoros sabahensis sp. nov. isolated from mud crab Scylla tranquebarica eggs and larvae in Malaysia

Mass mortality of eggs and larvae of the mud crab Scylla tranquebarica occurred at a hatchery in Sabah, Malaysia in June 2014. The mortality of the larvae reached nearly 100% within 5 days post-hatching. We isolated a pathogenic Peronosporomycetes (Oomycota) from the mud crab eggs and larvae using peptone-yeast-glucose-seawater (PYGS) agar, and then randomly selected the strain IPMB 1402 from the isolates for further study. We observed the formation of fragments inside the hyphae, a characteristic of Haliphthoros species. The strain morphologically most resembled Haliphthoros milfordensis, but comparisons of DNA sequences of the ITS1 region confirmed that the strain was not identical to that species. We classified the strain into a clade with Haliphthoros sp. group 2 (comprising strains NJM 0440, NJM 0449 and NJM 0535) after determining 97-100% intraspecific similarity. Based on distinctive morphological and molecular characteristics, the strain IPMB 1402 is here assigned to the genus Haliphthoros and designated Haliphthoros sabahensis sp. nov. Like other recognized species of Haliphthoros, it is an obligate marine fungus; growth was observed in pH 4-9, and optimum growth temperature was 25-30°C. The strain was experimentally pathogenic to nauplii of the brine shrimp Artemia salina