Association between dietary knowledge and muscle mass in Chinese older adults: a cross-sectional and longitudinal study.

OBJECTIVES: This study aims to explore the possible association between dietary knowledge and muscle mass in a Chinese population aged 60 years and above. DESIGN: Cross-sectional and longitudinal studies. SETTING: Data from the 2006 and 2011 China Health and Nutrition Survey (CHNS) were used for this study. PARTICIPANTS: A total of 1487 Chinese participants (44.38% males) aged 60 and above in the 2006 survey were included in the cross-sectional study. From the same study population, a total of 1023 participants (46.82% males) with normal muscle mass on the interview date of 2006 were included in the longitudinal study. OUTCOME MEASURES: Dietary knowledge was accessed by a validated CHNS questionnaire. Appendicular skeletal muscle mass was calculated using a validated anthropometric equation derived from a representative Chinese population. Based on the 2021 Chinese consensus on sarcopenia, the appendicular skeletal muscle mass was categorised as 'normal' or 'low' using sex-specific cut-off values. RESULTS: The prevalence of low muscle mass in the study population was 31.20%, with a higher prevalence in females (34.22%). People with low muscle mass have a significantly lower dietary knowledge score (mean difference: -1.74, 95% CI -2.20 to -1.29). In the cross-sectional analysis, one score higher in dietary knowledge score was associated with a 4% lower odds of low muscle mass (OR=0.96, 95% CI 0.93 to 0.99). Compared with people in the lowest quartile of dietary knowledge, people in the highest quartile have a 44% lower odds of low muscle mass (OR=0.56, 95% CI 0.35 to 0.91). In the longitudinal analysis, no significant association was found between dietary knowledge and low muscle mass, yet the upper 95% CI was close to one (HR=0.97, 95% CI 0.93 to 1.01). CONCLUSIONS: Sufficient dietary knowledge may play a protective role in maintaining normal muscle mass in Chinese adults aged 60 or above.

A polyketide synthase, BbpksP, contributes to conidial cell wall structure and UV tolerance in Beauveria bassiana.

Conidial pigments of filamentous fungi play vital roles in fungal biotic/abiotic stress tolerance and are usually synthesized by polyketide synthases or other pigment synthesis proteins. Beauveria bassiana, an important insect pathogenic fungus used worldwide for pest biocontrol, produces white conidia on artificial media, while no conidial pigment has been observed or reported in it. However, real-time PCR and promoter-report analyses reveal a polyketide gene of B. bassiana (named BbpksP), homologous to melanin synthesis genes, is specifically expressed in aerial conidia. We show that deletion of BbpksP does not result in changes in conidial yield, germination rate or colony radial growth; however, the defect impairs conidial cell wall structure. A dense electron layer appears in the outer edge of the cell envelope in wild-type conidia, as observed by TEM, but this dense layer is absent in the ΔBbpksP mutant. The lack of BbpksP gene also reduces the UV-B tolerance of B. bassiana conidia. Bioassay reveals that deletion of BbpksP decreased virulence of B. bassiana against Galleria mellonella larvae via topical infection. These data indicate that the product(s) of BbpksP contributes to the integrity of the B. bassiana conidial cell wall and further affects the tolerance of UV-B stress and insecticidal activity.