Lamelloplasts and minichloroplasts in Begoniaceae: iridescence and photosynthetic functioning.

Iridoplasts (modified plastids in adaxial epidermal cells) reported from Begonia were originally hypothesized to cause iridescence, which was broadly accepted for decades. However, several species of Begonia with iridoplasts are not iridescent causing confusion. Here chloroplast ultrastructure was observed in 40 taxa of Begoniaceae to explore the phenomenon of iridescence. However, 22 Begonias and Hillebrandia were found to have iridoplasts, but only nine display visually iridescent blue to blue-green leaves. Unexpectedly, a new type of plastid, a 'minichloroplast,' was found in the abaxial epidermal cells of all taxa, but was present in adaxial epidermal cells only if iridoplasts were absent. Comparative ultrastructural study of iridoplasts and a shading experiment of selected taxa show that a taxon with iridoplasts does not inevitably have visual iridescence, but iridescence is greatly affected by the spacing between thylakoid lamellae (stoma spacing). Thus, we propose instead the name 'lamelloplast' for plastids filled entirely with regular lamellae to avoid prejudging their function. To evaluate photosynthetic performance, chlorophyll fluorescence (F v /F m ) was measured separately from the chloroplasts in the adaxial epidermis and lower leaf tissues by using leaf dermal peels. Lamelloplasts and minichloroplasts have much lower photosynthetic efficiency than mesophyll chloroplasts. Nevertheless, photosynthetic proteins (psbA protein of PSII, RuBisCo and ATPase) were detected in both plastids as well as mesophyll chloroplasts in an immunogold labeling. Spectrometry revealed additional blue to blue-green peaks in visually iridescent leaves. Micro-spectrometry detected a blue peak from single blue spots in adaxial epidermal cells confirming that the color is derived from lamelloplasts. Presence of lamelloplasts or minichloroplasts is species specific and exclusive. High prevalence of lamelloplasts in Begoniaceae, including the basal clade Hillebrandia, highlights a unique evolutionary development. These new findings clarify the association between iridescence and lamelloplasts, and with implications for new directions in the study of plastid morphogenesis.

Association between abnormal liver function and risk factors for metabolic syndrome among freshmen.

PURPOSE: The aim of this study was to investigate the prevalence of obesity and metabolic syndrome among freshmen and to find the association between abnormal liver function and risk factors for metabolic syndrome in Taiwan. METHODS: A total of 515 freshmen who were less than 22 years of age and negative for hepatitis B surface antigen marker from one general university in North Taiwan participated in this study during their school entry health examination in September 2004. Demographic characteristics, body height, body weight, biochemistry values such as alanine aminotransferase, and risk factors for metabolic syndrome such as blood pressure, fasting blood sugar, high-density lipoprotein cholesterol, triglycerides, and waist circumference were recorded for statistical analysis. Subjects with elevated serum alanine aminotransferase levels were considered to have abnormal liver function. RESULTS: The prevalence of overweight, obesity, and metabolic syndrome among freshmen in Taiwan was 18.5%, 6.0% and 1.4%, respectively. The prevalence of abnormal liver function test was 6.2%. In multivariate logistic regression analyses, patients of metabolic syndrome were 94.5 times more likely (95% confidence interval [CI] = 10.5-852.5) to be associated with abnormal liver function after adjusting for gender and age. Among the risk factors for metabolic syndrome, enlarged waist circumference (adjusted odds ratio [OR] = 10.1, 95% CI = 4.3-23.8), and elevated triglyceride (adjusted OR = 6.1, 95% CI = 1.6-23.5) were found to be statistically significantly associated with abnormal liver function. CONCLUSIONS: Central obesity and elevated triglyceride level were the two risk factors for metabolic syndrome associated with abnormal liver function among freshmen in Taiwan.