ABSTRACT
Aurantiochytrium limacinum is a heterotrophic eukaryotic microorganism that can accumulate high levels of commercial products such as astaxanthin and docosahexaenoic acid. Due to its rapid growth and relatively simple extraction method, A. limacinum is considered a promising astaxanthin resource to replace the conventional microalgal production. However, the astaxanthin biosynthetic process in A. limacinum remains incompletely understood, especially in those catalysed by ß-carotene hydroxylase (CrtZ) and ketolase. In this study, we overexpressed a crtZ candidate gene to increase astaxanthin production and expand our understanding of the conversion from beta-carotene to astaxanthin. The resultant transformant AlcrtZ#10 cultivated for 5 days showed a significant increase in astaxanthin production per culture (2.8-fold) and per cell (4.5-fold) compared with that of the wild-type strain. Strikingly, longer light exposure increased astaxanthin production and decreased the beta-carotene content in the wild-type strain, suggesting that light exposure duration is important for astaxanthin production in A. limacinum. Among several predicted intermediates, furthermore, the cantaxanthin produced from ß-carotene by ketolase activity were enhanced in the transformant AlcrtZ#10. Although the further investigation is needed, this result suggested that the main route of astaxanthin was via cantaxanthin. Thus, our findings will be valuable not only for its application, but also for understanding the astaxanthin biosynthetic process in A. limacinum.
Subject(s)
Oxygenases , beta Carotene , Oxygenases/genetics , Mixed Function Oxygenases/geneticsABSTRACT
In the presence of triethylamine, (Z)-(2-acetoxy-1-alkenyl)phenyl-lambda(3)-iodanes react with thioureas or thioamides in MeOH to give 2,4-disubstituted thiazoles directly in good yields. The reaction probably involves generation of highly reactive alpha-lambda(3)-iodanyl ketones through ester exchange of the beta-acetoxy group with liberation of methyl acetate, followed by nucleophilic substitutions with thioureas or thioamides.
ABSTRACT
With the recognition that airway inflammation is present even in patients with mild bronchial asthma, therapy with inhaled corticosteroids is now indicated in various stages of patients. In the present article, we retrospectively examined the prescriptions for inhaled corticosteroids and other drugs for the treatment of outpatients with bronchial asthma at Tokushima University Hospital. We also analyzed asthma control in these patients, in terms of the incidence of emergency consultations and hospitalizations due to asthma exacerbations. To analyze the recent trend, the patients observed from 1998 to 2000 (recent years) were included, and for control purpose, those in 1990 and 1991 (earlier years) were also included. The percentage of patients treated with inhaled corticosteroids remarkably increased in recent years (mean; 81.3%) compared to earlier years (mean; 23.5%). In contrast, the usage of oral corticosteroids, oral xanthine derivatives, beta-adrenergic receptor agonists and anti-allergic agents tended to decrease in the 10 years period. After the introduction in 1995, considerable patients up to 25% have been treated with anti-leukotrienes. Emergency consultations decreased in recent years (mean; 0.18/patient/year) compared to earlier years (mean; 0.79/patient/year). Emergency hospitalizations also decreased in recent years (mean; 0.043/patient/year) compared to earlier years (mean; 0.23/patient/ year). In the present study, spread of inhaled corticosteroid therapy and decline in incidence of emergency consultation and hospitalization were simultaneously observed at Tokushima University Hospital, and the former has, at least in part, a contribution to the latter.
