Graphical abstract

Although attempts have been made to reveal the relationships between bacteria and human health, little is known about the species and function of the microbial community associated with oral diseases. In this study, we report the sequencing of 16 metagenomic samples collected from dental swabs and plaques representing four periodontal states. Insights into the microbial community structure and the metabolic variation associated with periodontal health and disease were obtained. We observed a strong correlation between community structure and disease status, and described a core disease-associated community. A number of functional genes and metabolic pathways including bacterial chemotaxis and glycan biosynthesis were over-represented in the microbiomes of periodontal disease. A significant amount of novel species and genes were identified in the metagenomic assemblies. Our study enriches the understanding of the oral microbiome and sheds light on the contribution of microorganisms to the formation and succession of dental plaques and oral diseases.

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The mid-Pleistocene transition (MPT) is widely recognized as a shift in paleoclimatic periodicity from 41- to 100-kyr cycles, which largely reflects integrated changes in global ice volume, sea level, and ocean temperature from the marine realm. However, much less is known about monsoon-induced terrestrial vegetation change across the MPT. Here, on the basis of a 1.7-million-year δ13C record of loess carbonates from the Chinese Loess Plateau, we document a unique MPT reflecting terrestrial vegetation changes from a dominant 23-kyr periodicity before 1.2 Ma to combined 100, 41, and 23-kyr cycles after 0.7 Ma, very different from the conventional MPT characteristics. Model simulations further reveal that the MPT transition likely reflects decreased sensitivity of monsoonal hydroclimate to insolation forcing as the Northern Hemisphere became increasingly glaciated through the MPT. Our proxy-model comparison suggests varied responses of temperature and precipitation to astronomical forcing under different ice/CO2 boundary conditions, which greatly improves our understanding of monsoon variability and dynamics from the natural past to the anthropogenic future.

Two phytoplankton blooms in the South China Sea (SCS), triggered by 2 typhoons with different intensities and translation speeds, were compared using remotely sensed chlorophyll a (chl a), sea surface temperature (SST), vector wind field, and best-track typhoon data. Typhoon LingLing in 2001 was strong, with a maximum sustained surface wind speed of 59 m s ) and 36% are slow-moving. We conservatively estimate that typhoon periods may account for 3.5% of the annual primary production in the oligotrophic SCS.

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The present study analyzed interannual variation of phytoplankton/Chlorophyll‐a (Chl‐a) distribution in the South China Sea (SCS) for the period from 1997 to 2005 using SeaWiFS‐derived Chl‐a data and other oceanographic data. The results show high spatial variation of Chl‐a concentrations in the SCS and revealed an anomalous event in 1998. High Chl‐a concentrations in the southwestern SCS in the summer season (June to August) may be related with strong Ekman Pumping and strong wind stress, whereas a jet‐shape high Chl‐a region offshore in western SCS was associated with coastal upwelling driven by offshore Ekman transport and Vietnamese offshore current. Chl‐a concentrations in 1998 summer in the SCS were the lowest among the 7 years and were particularly low in the western SCS. At the same season, the jet‐shape Chl‐a region offshore of southeast Vietnam almost disappeared, and southwesterly monsoon winds and offshore current were relatively weaker in 1998. This anomalous event of low phytoplankton biomass in the SCS coincided with an El Niño year in 1998.

Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) is a powerful technique for examining gene expression changes during tumorigenesis. Target gene expression is generally normalized by a stably expressed endogenous reference gene; however, reference gene expression may differ among tissues under various circumstances. Because no valid reference genes have been documented for human breast cancer cell lines containing different cancer subtypes treated with transient transfection, we identified appropriate and reliable reference genes from thirteen candidates in a panel of 10 normal and cancerous human breast cell lines under experimental conditions with/without transfection treatments with two transfection reagents. Reference gene expression stability was calculated using four algorithms (geNorm, NormFinder, BestKeeper and comparative delta Ct), and the recommended comprehensive ranking was provided using geometric means of the ranking values using the RefFinder tool. GeNorm analysis revealed that two reference genes should be sufficient for all cases in this study. A stability analysis suggests that 18S rRNA-ACTB is the best reference gene combination across all cell lines; ACTB-GAPDH is best for basal breast cancer cell lines; and HSPCB-ACTB is best for ER+ breast cancer cells. After transfection, the stability ranking of the reference gene fluctuated, especially with Lipofectamine 2000 transfection reagent in two subtypes of basal and ER+ breast cell lines. Comparisons of relative target gene (HER2) expression revealed different expressional patterns depending on the reference genes used for normalization. We suggest that identifying the most stable and suitable reference genes is critical for studying specific cell lines under certain circumstances.