ABSTRACT:In Vietnam, Cattle Egrets (Bubulcus ibis) are common in a variety of habitats, such as freshwater marshes, beaches, and paddy fields. They are also found associated with cattle (Bos spp.) and occasionally with pigs (Sus scrofa), goats (Capra hircus), and horses (Equus caballus) and are kept for insect control in households. In this study, six Cattle Egrets were experimentally infected intranasally with highly pathogenic avian influenza (AI) A/duck/Vietnam/40D/04 (H5N1) to investigate a possible epidemiologic role for Cattle Egrets in outbreaks of H5N1 AI in Vietnam. The Cattle Egrets were highly susceptible to the infection and either died within a week or had to be euthanized. Five uninfected chickens housed with the inoculated Cattle Egrets from day 1 to day 8 postinfection showed no signs of disease or mortality. This observation was most probably due to the low-level virus shedding by the Cattle Egrets. We concluded that Cattle Egrets are not significant reservoir hosts for H5N1 AI virus.

Rhododendron simsii Planch. is distributed in eastern Asia, such as Ryukyu Islands of Japan, southern China, Taiwan, and Vietnam. It is a semideciduous shrub with five-lobed red corollas and reddish-purple blotches on the upper petals. From microscopic observation, reddish-purple colored cells were distributed only in the adaxial subepidermis of blotch areas in the upper petals, while red colored cells were observed in the whole epidermis of both upper and lower petals. Even though the anthocyanin constitutions of upper and lower petals were the same, the λ max of absorbance of fresh upper petals was 514.9 nm, while it was 505.7 nm in the lower petals. In R. simsii flowers, cyanidin glycosides were major anthocyanins in whole petals. Quercetin glycosides were detected in reddish-purple blotch areas, but they were found only in trace amounts in lower petals. Anthocyanins and flavonols were extracted, and separated by column chromatography. Bathochromic shift (9.7 nm) was observed in mixed solution of anthocyanin and flavonol at a ratio of concentration of 1:7.5. These results were similar to the bathochromic shift obtained between upper and lower petals of intact flowers (9.2 nm). From these findings, co-pigmentation between anthocyanin and flavonol (quercetin glycosides) seems to be a key factor of reddish-purple color of the blotch area in the upper petals of R. simsii flowers.

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greenhouse. A part of fresh petals was used for microscopic observation of the cross-sections. The remaining was separated into upper and lower petals, and each part of petals was boiled at 100˚C for 5 seconds and immediately cooled in water. Then the samples were dried in the forced convention oven overnight at 50˚C . The dried samples were stored in a desiccator at 4˚C until using for pigment analysis.