Retrotransposons Are the Major Contributors to the Expansion of the Drosophila ananassae Muller F Element.

The discordance between genome size and the complexity of eukaryotes can partly be attributed to differences in repeat density. The Muller F element (∼5.2 Mb) is the smallest chromosome in Drosophila melanogaster, but it is substantially larger (>18.7 Mb) in D. ananassae To identify the major contributors to the expansion of the F element and to assess their impact, we improved the genome sequence and annotated the genes in a 1.4-Mb region of the D. ananassae F element, and a 1.7-Mb region from the D element for comparison. We find that transposons (particularly LTR and LINE retrotransposons) are major contributors to this expansion (78.6%), while Wolbachia sequences integrated into the D. ananassae genome are minor contributors (0.02%). Both D. melanogaster and D. ananassae F-element genes exhibit distinct characteristics compared to D-element genes (e.g., larger coding spans, larger introns, more coding exons, and lower codon bias), but these differences are exaggerated in D. ananassae Compared to D. melanogaster, the codon bias observed in D. ananassae F-element genes can primarily be attributed to mutational biases instead of selection. The 5' ends of F-element genes in both species are enriched in dimethylation of lysine 4 on histone 3 (H3K4me2), while the coding spans are enriched in H3K9me2. Despite differences in repeat density and gene characteristics, D. ananassae F-element genes show a similar range of expression levels compared to genes in euchromatic domains. This study improves our understanding of how transposons can affect genome size and how genes can function within highly repetitive domains.

Effect of nutrition supplement education on nutrition supplement knowledge among high school students from a low-income community.

Research has shown that adolescents from low-income communities receive less educational resources and support and may possess insufficient knowledge of nutrition and sport supplements to make health conscious decisions. The purpose of this investigation was to determine the effectiveness of a nutrition supplement educational intervention in improving the nutrition supplement knowledge of adolescents from a low-income community. Thirty-nine high school students from a low-income community were separated into experimental (E) (n = 22) and control (C) (n = 17) groups. E received 5 nutrition lessons on various nutrition and sport supplement topics. C did not receive any nutrition education. E consisted of 5 freshmen, 5 sophomores, 6 juniors, and 6 seniors. The ethnic backgrounds of E were: 15 African-Americans, 3 Hispanic-Americans, and 4 "others." There were 14 females and 8 males in E. C consisted of 9 freshmen, 1 sophomore, 4 juniors, and 3 seniors. The ethnic backgrounds of C were: 14 African-Americans, 1 Hispanic-American, and 2 "others." There were 10 females and 7 males in C. Both groups were administered a validated nutrition and sport supplement questionnaire at baseline and post-intervention that consisted of 28 questions. Mean baseline knowledge scores for E and C were 5.73 +/- 3.34 and 8.18 +/- 3.82, respectively (p = 0.040). Post-intervention scores were: 14.45 +/- 4.81 and 7.82 +/- 4.79 for E and C, respectively (p = 0.0001). These results indicate that a short-term nutrition education program can significantly improve nutrition and sport supplement knowledge in high school students of low socioeconomic status.