酚红指示法检测长须白蛉肠道酸碱度的变化(英文)

PHENOL RED METHOD FOR MEASURING THE pH OF THE GUT CONTENTS IN LUTZOMYIA LONGIPALPIS (PSYCHODIDAE:DIPTERA)

目的：作者建立酚红指示法检测长须白蛉中肠酸碱度用于检测在中肠不受损伤的情况下其内含物酸碱度的变化。方法：用玻璃微管强迫长须白蛉Ｌｕｔｚｏｍｙｉａｌｏｎｇｉｐａｌｐｉｓ吸食少量５０％饱和酚红溶液至中肠。解剖后，观察肠道内各部位的颜色，用以显示其内含物的酸碱度。结果：饲糖组白蛉胸部中肠（ＴＭＧ）的酸碱度一般呈中性，ｐＨ７．０－７．３；腹部中肠（ＡＭＧ）呈弱碱性，ｐＨ７．１－８．４，并且从前往后逐渐增高。如果嗉囊中有糖残留，ＴＭＧ的ｐＨ可降至６．８。饲血组ＴＭＧ酸碱度在吸血后１—３ｄ内可达ｐＨ７．４，但随着血液的逐步消化，其ｐＨ则逐渐降至或低于６．８。此时期ｐＨ的降低，是利什曼感染型发生期。结论：本法可用于检测白蛉中肠的ｐＨ，具有简便准确等优点，通过对ｐＨ变化的检测，可间接反映肠道内利什曼感染型的发展变化。

AIM:To develop a method to estimate the pH of the gut contents of female sandflies using a microcapillary feeding technique.METHODS:Female Lutzomyia longipalpis were fed with a small quantity of phenol red solution (indicator range pH 6.8 8.4) before and after a bloodmeal.The colour patterns of the gut contents were recorded by video microscopy immediately after the alimentary canal was dissected out of the sandfly body,and used to determine the pH level.RESULTS:In unfed flies the thoracic mid gut (TMG)is normally neutral,with the pH ranging between 7.0 to 7.3;and the abdominal mid gut(AMG)is mildly alkaline from pH 7.1 to 8.4 with the maximum pH observed at the junction with the hind gut.The presence of sugar in the crop reduced the pH of the TMG to 6.8,and the presence of a recently ingested bloodmeal raised the pH of the TMG to 7.4.However,as bloodmeal digestion proceeded the pH of the TMG was reduced to acidic levels,pH 6.8 or below. CONCLUSION: The new method could be integrated with the investigation of metacyclogenesis of Leishmania parasites in vivo .