來自於Aspergillus parasiticus的aflR 基因與黃麴毒素的生化合成有關。為了探討aflR基因在不同種之間的存在及表達與否，４株非產毒性的A. flavus、5株產毒性的A. flavus、8株A. oryzae及４株A. sojae 選作為本文之材料。綜合南方點墨法及PCR反應的結果，aflR基因可以在以下菌株的染色體DNA中測得：75%的非產毒性A. flavus，100% 的產毒性A. flavus，75%的A. oryzae和50%的A. sojae。在誘發黃麴毒素生長的環境下，綜合反轉錄PCR(RT-PCR)及RNase protection assay (RPA)的結果，aflR的mRNA只在３株產毒性的A. flavus及１株A. oryzae的RNA樣品中被偵測到，而所有的非產毒性A. flavus及A. sojae則呈現陰性反應。所有的非產毒性A. flavus, A. oryzae及A. sojae在誘發黃麴毒素生長的培養環境下，皆沒有產生可偵測到之黃麴毒素濃度。
The aflR gene from Aspergillus parasiticus is involved in the regulation of aflatoxin biosynthesis. To investigate the presence and expression of aflR gene in species belonging to Aspergillus Section Flavi, twenty-four strains were examined, including three A. parasiticus strains serving as positive and negative controls, four nonaflatoxigenic A. flavus, five aflatoxigenic A. flavus, eight A. oryzae strains and four A. sojae strains. In combination of the results from Southern-hybridization analysis and polymerase chain reaction (PCR), the aflR-homolog gene was detected in the genomic DNAs obtained from 75% of non-alfatoxigenic A. flavus, 100% of aflatoxigenic A. flavus, 75% of A. oryzae and 50% of A. sojae strains. Growing under aflatoxin-inducing conditions, the aflR transcript was only found in the RNA preparations from three of the five aflatoxigenic A. flavus and one of the eight A. oryzae strains with the application of reverse transcriptase(RT)-PCR and RNase protection assay (RPA); no signal was detected in samples prepared from nonaflatoxigenic A. flavus and A. sojae. None of the nonaflatoxigenic A. flavus, A. oryzae and A. sojae isolates produced detectable levels of AFB1. Our results also suggest that the hybridization techniques, Southern analyses and RPA, are more sensitive and reliable than PCR for studying the existence of aflR homolog and transcript in various Aspergillus isolates.
