Comparative Genomics Reveals Evolutionary Drivers of Sessile Life and Left-right Shell Asymmetry in Bivalves.

Bivalves are species-rich mollusks with prominent protective roles in coastal ecosystems. Across these ancient lineages, colony-founding larvae anchor themselves either by byssus production or by cemented attachment. The latter mode of sessile life is strongly molded by left-right shell asymmetry during larval development of Ostreoida oysters such as Crassostrea hongkongensis. Here, we sequenced the genome of C. hongkongensis in high resolution and compared it to reference bivalve genomes to unveil genomic determinants driving cemented attachment and shell asymmetry. Importantly, loss of the homeobox gene Antennapedia (Antp) and broad expansion of lineage-specific extracellular gene families are implicated in a shift from byssal to cemented attachment in bivalves. Comparative transcriptomic analysis shows a conspicuous divergence between left-right asymmetrical C. hongkongensis and symmetrical Pinctada fucata in their expression profiles. Especially, a couple of orthologous transcription factor genes and lineage-specific shell-related gene families including that encoding tyrosinases are elevated, and may cooperatively govern asymmetrical shell formation in Ostreoida oysters.

Probiotics: their action against pathogens can be turned around.

Probiotics when applied in complex evolving (micro-)ecosystems, might be selectively beneficial or detrimental to pathogens when their prophylactic efficacies are prone to ambient interactions. Here, we document a counter-intuitive phenomenon that probiotic-treated zebrafish (Danio rerio) were respectively healthy at higher but succumbed at lower level of challenge with a pathogenic Vibrio isolate. This was confirmed by prominent dissimilarities in fish survival and histology. Based upon the profiling of the zebrafish microbiome, and the probiotic and the pathogen shared gene orthogroups (genetic niche overlaps in genomes), this consequently might have modified the probiotic metabolome as well as the virulence of the pathogen. Although it did not reshuffle the architecture of the commensal microbiome of the vertebrate host, it might have altered the probiotic-pathogen inter-genus and intra-species communications. Such in-depth analyses are needed to avoid counteractive phenomena of probiotics and to optimise their efficacies to magnify human and animal well-being. Moreover, such studies will be valuable to improve the relevant guidelines published by organisations such as FAO, OIE and WHO.

Relationship Between Physical Performance and Mild Cognitive Impairment in Chinese Community-Dwelling Older Adults.

OBJECTIVE: This study aimed to examine the relationship between physical performance and mild cognitive impairment (MCI) in Chinese older adults. METHODS: The sample comprised 956 relatively healthy and aged ≥65 years old Chinese community-dwelling participants (mean age, 72.56 ± 5.43 years; 56.8% female), which did not include those with dementia, severe cognitive impairment, mental illness etc. The Mini-Mental State Examination (MMSE) and the Instrumental Activities of Daily Living (IADL) scale were used for the initial classification of patients with MCI. Physical performance was measured via hand grip, Timed Up and Go Test (TUGT), and 4-m walking speed. RESULTS: The physical performance (grip strength, TUGT, and 4-m walking speed) correlated with MCI. The grip strength [odds ratio (OR) = 0.96, 95% confidence interval (CI) = 0.93-0.99] and 4-m walking speed (OR = 0.25, 95% CI = 0.10-0.64) correlated negatively with MCI, while TUGT (OR = 1.08, 95% CI = 1.03-1.13) and MCI correlated positively. CONCLUSION: The physical performance (grip strength, TUGT, and 4-m walking speed) correlated with MCI. Further analysis showed that the grip strength was associated with overall cognition, time orientation, recall, and language, while TUGT and 4-m walking speed were associated with overall cognition and various cognitive domains, except recall.