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Near-inertial oscillations (NIOs) are widely observed dynamic motions in the global ocean, with a frequency related to earth’s rotation. Using a particle trajectory model, we found the combined influence of mesoscale eddies and NIOs could produce distinctive flower-like trajectories, which are a special case of near-inertial trajectories and were observed by surface drifters released within an anticyclone eddy in the South China Sea in 2021. The energy budget indicates that wind and geostrophic eddy currents are crucial in generating near-inertial energy during the flower-like trajectories. Furthermore, the particle trajectory model revealed variations in periods and widths of the near-inertial trajectory with latitudes. The width of near-inertial trajectories can exceed 8 km in the near-equatorial region and reach 3–6 km in the mid-latitude region (20°–50°). The ratios of near-inertial velocity to background velocity, defined as near-inertial trajectory shape index (NITSIs), lead to arc-shaped (0.5 < NITSI < 1.0), overlapping semi-circular (NITSI > 1.0), and near-circular trajectories (NITSI ≫ 1.0). Globally, approximately 1/3 of the drifters’ lifespan featured clear near-inertial trajectories, with a significant presence in most middle latitudes and the largest NITSI in the north Pacific westerly. These findings highlight the importance of NIOs and suggest their substantial impact on local surface matter distribution, trajectory prediction, and marine rescue operations.

The summer intraseasonal oscillation (ISO) is characterized by a northward-moving rainband in the Indo–western Pacific warm pool region. The physical origin of the ISO is not fully understood, as it is masked by strong interaction of convection and circulation. This study examines intraseasonal to interannual variability during June–August over the Indo–western Pacific warm pool region. The results show that the tropical northwest Pacific anomalous anticyclone (NWP-AAC) is a fundamental mode on both intraseasonal and interannual time scales, destabilized by the monsoon mean state, specifically through barotropic energy conversion and convective feedback in the low-level confluence between the monsoon westerlies and easterly trade winds. On the interannual time scale, the NWP-AAC shows a biennial tendency, reversing phase from the summer of El Niño to the summer that follows; the AAC in post–El Niño summer is excited indirectly through sea surface temperature anomalies in the Indo–NWP. On the intraseasonal time scale, the column-integrated moisture advection causes the NWP-AAC-related convection to propagate northward. Our results provide a unifying view of multiscale Asian summer monsoon variability, with important implications for subseasonal to seasonal prediction.

Tropical instability waves (TIWs) arise from shear instabilities of equatorial Pacific Ocean currents and are important for the tropical climate and the El Niño–Southern Oscillation. Yet the long-term evolution of TIW activity under climate change remains unclear due to the difficulty in estimating equatorial current velocity. Here we use in situ, satellite altimeter and sea surface temperature observations along with a realistic eddy-resolving ocean simulation to show that TIW activity has intensified in the central equatorial Pacific at ∼12 ± 6% per decade over the recent three decades. The extended satellite data and the ocean model simulation show that the increased TIW activity is probably caused by an enhanced cross-equatorial asymmetric warming in the eastern tropical Pacific. The intensified TIWs lead to increased eddy dynamic heating effects of ∼70% since the 1990s near the equator, with implications for predicting and projecting tropical Pacific climate changes. Tropical instability waves (TIWs) are an important component of the equatorial Pacific climate. Here the authors show that TIW activity has intensified in the central equatorial Pacific at ∼12 ± 6% per decade over the recent three decades.

Coexpression of multiple nif genes and stability of the nitrogenase components are essential for engineering nitrogen fixation in eukaryote.A reconstituted nitrogenase biosynthesis pathway comprising 13 genes (nifB nifH nifD nifK nifE nifN nifX hesA nifV groES groEL nifS nifU) (~40 kb) was successfully introduced into rice.Thirteen genes were transcribed, and 11 Nif proteins as well as NifDK tetramer were produced in F4 homozygous transgenic rice.NifH in rice cytosol was found to be unstable. NifH variants with Fe protein activity and resistance to endoproteinase cleavage were obtained. Engineering nitrogen fixation in cereals could reduce usage of chemical nitrogen fertilizers. Here, a nitrogenase biosynthesis pathway comprising 13 genes (nifB nifH nifD nifK nifE nifN nifX hesA nifV nifS nifU groES groEL) was introduced into rice by transforming multigene vectors and subsequently by sexual crossing between transgenic rice plants. Genome sequencing analysis revealed that 13 nif genes in F4 hybrid rice lines L12-13 and L8-17 were inserted at two loci on rice chromosome 1. Eleven nitrogen fixation (Nif) proteins were produced and stable NifDK tetramer was formed in rice cytosol. NifH in rice cytosol was unstable and NifH-S18 was found to be a key residue that conferred susceptibility to proteinase degradation. NifH variants with Fe protein activity and resistance to plant endoproteinase cleavage were obtained. This study provides an efficient approach for introducing multiple nif genes into plants and also helps to pre-evaluate the stability of prokaryotic proteins in plant cytosol. [Display omitted] This study demonstrates that a reconstituted nitrogenase biosynthesis pathway comprising 13 nif genes (~40 kb) was successfully introduced into rice by using an efficient multigene assembly and introduction system. The system includes Agrobacterium-mediated single transformation and co-transformation of multigene vectors and subsequently by sexual crossing between transgenic plants. Multigene vectors were constructed by Gibson Assembly. Multiple nif genes were transcribed and nitrogen fixation (Nif) proteins were accumulated in rice cytosol. This system has reached Technology Readiness Level (TRL) 5. This system can be applied to plant synthetic biology and metabolic engineering for creating new functionality and improving traits. Moreover, using molecular and tobacco transient expression methods, we discovered that a specific motif within NifH might be cleaved by plant cytosolic endoproteinase and have presented solutions using NifH substitution variants. These methods can also be used to identify the reason and to provide solutions to instability of other prokaryotic proteins in plant cytosol. We present the multigene assembly and introduction system for introducing a reconstituted nitrogenase biosynthesis pathway into rice. This approach provides significant potential for applications in introducing multiple genes into plants. Also, we provide an efficient way for identifying and overcoming instability of NifH and other prokaryotic proteins in plant cytosol.

Using an eastern tropical Pacific pacemaker experiment called the Pacific Ocean–Global Atmosphere (POGA) run, this study investigated the internal variability in sea surface salinity (SSS) and its impacts on the assessment of long-term trends. By constraining the eastern tropical Pacific sea surface temperature variability with observations, the POGA experiment successfully simulated the observed variability of SSS. The long-term trend in POGA SSS shows a general pattern of salty regions becoming saltier (e.g., the northern Atlantic) and fresh regions becoming fresher, which agrees with previous studies. The 1950–2012 long-term trend in SSS is modulated by the internal variability associated with the interdecadal Pacific oscillation (IPO). Due to this variability, there are some regional discrepancies in the SSS 1950–2012 long-term change between POGA and the free-running simulation forced with historical radiative forcing, especially for the western tropical Pacific and southeastern Indian Ocean. Our analysis shows that the tropical Pacific cooling and intensified Walker circulation caused the SSS to increase in the western tropical Pacific and decrease in the southeastern Indian Ocean during the 20-yr period of 1993–2012. This decadal variability has led to large uncertainties in the estimation of radiative-forced trends on a regional scale. For the 63-yr period of 1950–2012, the IPO caused an offset of ∼40% in the radiative-forced SSS trend in the western tropical Pacific and ∼170% enhancement in the trend in the southeastern Indian Ocean. Understanding and quantifying the contribution of internal variability to SSS trends helps improve the skill for estimates and prediction of salinity/water cycle changes.

Mesoscale activities over the equatorial Pacific Ocean are dominated by the Rossby and Yanai modes of tropical instability waves (TIWs). The TIW-induced surface velocity has not been accurately estimated in previous diagnostic models, especially for the meridional component across the equator. This study develops a diagnostic model that retains the acceleration terms to estimate the TIW surface velocity from the satellite-observed sea surface height. Validated against moored observations, the velocity across the equator is accurately estimated for the first time, much improved from existing products. The results identify the Rossby- and Yanai-mode TIWs as the northwest–southeastward (NW–SE) velocity oscillations north of the equator and the northeast–southwestward (NE–SW) velocity oscillations on the equator, respectively. Barotropic instability is the dominant energy source of the two TIW modes. The NE–SW velocity oscillation of the Yanai mode is associated with the counterclockwise shear of the South Equatorial Current on the equator. The two TIW modes induce different sea surface temperature patterns and vertical motions. Accurate estimates of TIW velocity are important for studying equatorial ocean dynamics and climate variability in the tropical Pacific Ocean.

This research investigated the eddy–mean flow interactions in the Agulhas leakage region by utilizing the Ocean General Circulation Model for the Earth Simulator (OFES) output and an energetic analysis tool called the multiscale energetics and vorticity analysis tool (MS-EVA). MS-EVA relies on multiscale window transform (MWT) functional analysis and canonical transfer. It is found that the climatological characteristics of the nonlinear interactions between the eddy and mean flow exhibit mixed canonical transfers, including both barotropic and baroclinic canonical transfers. These canonical transfers are related to barotropic and baroclinic instabilities, respectively. These transfers are highly inhomogeneous in space, reaching their maxima around 18°–22° E and 36°–42° S, where the Agulhas Ring forms. Besides, the barotropic canonical transfers from the mean flow to the eddy tend to dominate the entire Agulhas leakage region, with a contribution ratio of 1.55 between the barotropic and baroclinic canonical transfers. These results suggest that barotropic instability plays a more important role in producing eddy activities in this region.

Tropical instability waves (TIWs) are an important component of the equatorial Pacific climate. An analysis of satellite observations, in situ measurements and ocean circulation models indicates that TIW activity has intensified in the central equatorial Pacific by approximately 12 ± 6% per decade since the 1990s.

Melioidosis, a severe tropical illness caused by Burkholderia pseudomallei, poses significant treatment challenges due to limited therapeutic options and the absence of effective vaccines. The pathogen’s intrinsic resistance to numerous antibiotics and propensity to induce sepsis during acute infections further complicate management strategies. Thus, exploring alternative methods for prevention and treatment is crucial. Monoclonal antibodies (mAbs) have emerged as a promising strategy for the prevention and treatment of infectious diseases. This study focused on generating three mAbs (13F1, 14G11, and 15D9) targeting hemolysin-coregulated protein 1 (Hcp1), a protein involved in the type VI secretion system cluster 1 (T6SS1) of B. pseudomallei. Notably, pretreatment with 13F1 mAb significantly reduced the intracellular survival of B. pseudomallei and inhibited the formation of macrophage-derived multinucleated giant cells (MNGCs). This protective effect was also observed in vivo. We identified a sequence of amino acids (Asp95-Leu114) within Hcp1 as the likely binding site for 13F1 mAb. In summary, our findings reveal that 13F1 mAb counteracts infection by targeting Hcp1, offering potential new targets and insights for melioidosis prevention.

From 2015 to 2018, we continuously applied the diazotroph Paenibacillus triticisoli BJ-18 as an inoculant to soil cropped winter wheat under field condition. Based on 16S rRNA, nifH, ITS, and shotgun metagenome sequencing, we investigated the influences of diazotroph on the composition and function of the bacterial, diazotrophic, and fungal communities in the rhizosphere and root/shoot endosphere of wheat in 2018. P. triticisoli BJ-18 significantly increased soil total N, available P, organic matter, nitrogenase activity, and wheat yield. The diversities of the rhizospheric bacterial community were higher in the inoculation treatment than the non-inoculation treatment, while the relative abundances of rhizospheric fungal, endospheric bacterial, and diazotrophic communities were lower in the inoculation treatment. Paenibacillus became dominant in the rhizosphere and root, and also the relative abundance of indigenous diazotrophs was increased by inoculation. The microbial inoculation also significantly increased the relative abundances of indigenous plant growth-promoting microbes (Bacillus, Klebsiella, and Podospora) but decreased the relative abundances of indigenous pathogenic fungi (Alternaria). Notably, some nitrogenase gene abundances were significantly enriched by inoculation. These results demonstrated that P. triticisoli BJ-18, acting as a keystone species, can change (optimize) the composition and function of plant microbiome to promote plant growth and productivity.