Molecular analysis of an inactive aflatoxin biosynthesis gene cluster in Aspergillus oryzae RIB strains.

To help assess the potential for aflatoxin production by Aspergillus oryzae, the structure of an aflatoxin biosynthesis gene homolog cluster in A. oryzae RIB 40 was analyzed. Although most genes in the corresponding cluster exhibited from 97 to 99% similarity to those of Aspergillus flavus, three genes shared 93% similarity or less. A 257-bp deletion in the aflT region, a frameshift mutation in norA, and a base pair substitution in verA were found in A. oryzae RIB 40. In the aflR promoter, two substitutions were found in one of the three putative AreA binding sites and in the FacB binding site. PCR primers were designed to amplify homologs of aflT, nor-1, aflR, norA, avnA, verB, and vbs and were used to detect these genes in 210 A. oryzae strains. Based on the PCR results, the A. oryzae RIB strains were classified into three groups, although most of them fell into two of the groups. Group 1, in which amplification of all seven genes was confirmed, contained 122 RIB strains (58.1% of examined strains), including RIB 40. Seventy-seven strains (36.7%) belonged to group 2, characterized by having only vbs, verB, and avnA in half of the cluster. Although slight expression of aflR was detected by reverse transcription-PCR in some group 1 strains, including RIB 40, other genes (avnA, vbs, verB, and omtA) related to aflatoxin production were not detected. aflR was not detected in group 2 strains by Southern analysis.

Relationship between the preference for sake (Japanese rice wine) and the movements of metabolic parameters coinciding with sake intake.

Selection of foods by animals largely depends on their physiological condition. In this paper, we reported how physiological changes in rats after ingestion of sake (Japanese rice wine) affected their preference for different kinds of sake. Rats could discriminate among various kinds of sakes in a two-bottle choice test, even after adjustment of the glucose concentration or alcohol concentration of the sake, suggesting that the choice of a sake by animals was based on more than one ingredient. To identify effect of a rat's physiological condition on the selection of sake, we monitored the levels of blood glucose, nonesterified fatty acids (NEFA), and ketone bodies in serum in mice after forced intragastric ingestion of sake that had previously been offered to the rats in a two-bottle choice test. Blood glucose levels in mice were not different between the rats fed the palatable and unpalatable sakes, and the NEFA level and ketone level were high in rats fed the unpalatable sake. To further clarify the relationship between physiological condition and preference for sake, rats were offered eight kinds of Junmai-syu, which is made with only rice and no sub-ingredient. Rats could still discriminate among Junmai-syu. Furthermore, with two exceptions, the preference for a sake was significantly correlated with the ketone level. The order in the ratio of blood insulin level to blood glucagon level, which is an indicator of metabolism, was correlated with the order in preference to sake. These results suggest that some physiological factors besides oral stimulation also are important factors in the selection of a sake.