Unveiling the evolution of phytoplankton communities: Decades-long insights into the southern Yellow Sea, China (1959-2023).

We obtained historical and observational data on phytoplankton communities from 1959 to 2023 to explore the responses of the phytoplankton community structure to long-term environmental changes in the southern Yellow Sea (SYS), China. The results revealed a decrease in the proportions of diatom cell abundance within the phytoplankton community by 8 %, accompanied by a corresponding increase in that of dinoflagellates. Dominant phytoplankton species were mainly chain-forming diatoms before 2000, and large dinoflagellate species from the genera Tripos and Noctiluca increased their dominance after 2000. Warm-water phytoplankton species have increased in dominance over the study period. Correlation analysis revealed that the ocean warming and alterations in nutrient structure (N/P and Si/N ratios) were mostly responsible for the long-term evolution trend, and these changes may result in an increase in dinoflagellate harmful algal blooms, reduced efficiency of the biological carbon pump, and heightened hypoxia in the future, which should draw our attention.

Isopycnal mixing of interhemispheric intermediate waters by subthermocline eddies east of the Philippines.

Both sporadic observations and modelling studies suggest that subthermocline eddies (SEs) exist east of the Philippines, where interhemispheric waters meet. However, effects of SEs on water mass mixing have never been observed. Here, using data from mooring and buoy deployed in the frontal region of the interhemispheric water masses, we show for the first time that the SEs act as an "underwater mixer" of intermediate waters from north and south Pacific oceans. The SEs have typical swirl speeds of 0.1~0.4 m s-1 between 200 and 800 m depth with a dominant period of ~90 days. Variation in intermediate water salinity also had a period of ~90 days, lagging eddy speed by ~8 days. Horizontal eddy diffusivity representative of eddy mixing rate was quantified using a mixing-length framework. Horizontal eddy diffusivity had both surface and subthermocline maxima. The vertically varying eddy diffusivity can be used to improve parameterization of eddy stirring in the tropical Pacific by coarse-resolution ocean climate models. The effect of the SEs on mixing of intermediate water masses seems not resolved by available eddy-resolving ocean models typically used for this region.

[Establishment of human neuroblastoma SH-SY5Y cell line stably silencing beclin1].

The pGenesil-1-Beclin1 eukaryotic expression vectors were constructed to establish an SH-SY5Y cell line stably expressing shRNA-Beclin1. The shRNA was connected to pGenesil-1 to construct the recombinant plasmid pGenesil-1-Beclin1, which was transformed into JM109 E. coli. Positive clones were identified by digestion with restriction endonuclease and DNA sequencing. SH-SY5Y cells were cultured by the conventional method. The pGenesil-1-Beclin1 and pGenesil-1 plasmids were transfected into SH-SY5Ycells, and the cells were screened by G418 until the stable G418-resistant monoclonal cells were acquired. Beclin1 mRNA and Beclin1 protein were detected by RT-PCR and Western blot analysis respectively. The results of restriction endonuclease analysis and DNA sequencing confirmed the correct construction of the eukaryotic expression vector pGenesil-1-Beclin1. Two SH-SY5Y transfected cell lines were successfully selected. Compared with the control group, RT-PCR and Western blot showed that the expression of Beclin1 mRNA and protein were down regulated 71.28% ± 1.45% (P < 0.05)and 75.50% ± 2.63% (P < 0.05), respectively. The results indicated that the eukaryotic expression vector pGenesil-1-Beclin1 was successfully constructed and the SH-SYSY cell lines with inhibited Beclin1 expression were established. It provides a useful cell model for studying the biological function of Beclin1.