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Although the trans-translation system is a promising target for antcibiotic development, its antibacterial mechanism in Klebsiella pneumoniae (KP) is unclear. Considering that tmRNA was the core component of trans-translation, this study firstly investigated phenotypic changes caused by various environmental stresses in KP lacking trans-translation activities (tmRNA-deleted), and then aimed to evaluate antibacterial activities of the trans-translation-targeting antibiotic combination (tobramycin/ciprofloxacin) in clinical KP isolates based on inhibition activities of aminoglycosides against trans-translation. We found that the tmRNA-deleted strain P4325/ΔssrA was significantly more susceptible than the wild-type KP strain P4325 under environments with hypertonicity (0.5 and 1 M NaCl), hydrogen peroxide (40 mM), and UV irradiation. No significant differences in biofilm formation and survivals under human serum were observed between P4325/ΔssrA and P4325. tmRNA deletion caused twofold lower MIC values for aminoglycosides. As for the membrane permeability, tmRNA deletion increased ethidium bromide (EtBr) uptake of KP in the presence or absence of verapamil and carbonyl cyanide-m-chlorophenylhydrazone (CCCP), decreased EtBr uptake in presence of reserpine in P4325/ΔssrA, and reduced EtBr efflux in P4325/ΔssrA in the presence of CCCP. The time-kill curve and in vitro experiments revealed significant bactericidal activities of the tmRNA-targeting aminoglycoside-based antibiotic combination (tobramycin/ciprofloxacin). Thus, the corresponding tmRNA-targeting antibiotic combinations (aminoglycoside-based) might be effective and promising treatment options against multi-drug resistant KP. [ABSTRACT FROM AUTHOR]

Large‐scale circulations are quite typical processes in the northern South China Sea (SCS) deep basin, yet their impacts on the variation of internal solitary waves (ISWs) remains poorly understood. We, here, focus on impacts of the upstream SCS western boundary current (SCSwbc) and three typical circulation patterns associated with different Kuroshio intruding paths on ISW propagation in this region. We show that the ISW modulated by the upstream SCSwbc gets a speedup, which is comparable to that induced by Coriolis effect, while the ISW amplitude shows an obvious reduction. Statistically, there is approximately one‐third time of 23 years (1993–2015) when circulation‐induced changes of wave speed exceed Coriolis‐induced changes. Specifically, the looping circulation pattern has the highest impact on significant speedup and amplitude reduction among the three patterns, while the leaping pattern has the lowest impact. These differences in wave characteristics caused by different circulation patterns result from the wave scattering, focusing and Doppler effects. Plain Language Summary: Oceanic internal solitary waves (ISWs) are ubiquitous features across the world's oceans. Most of previous studies during the past decades were devoted to the impact of the tidal forcing or Coriolis force on these waves, but the impact of typical oceanic circulations, primarily driven by wind forcing, was still not well understood. Here, by modeling and statistical analyses, we illustrate the impacts of the upstream branch of South China Sea (SCS) western boundary current and three typical oceanic circulation patterns associated with different paths of Kuroshio intrusion on the propagation of ISW fronts in the northern SCS deep basin. We show that the speedup of ISW induced by the upstream branch of western boundary current is comparable to that induced by Coriolis effect, while the amplitude shows an obvious reduction. The oceanic circulation‐induced relative change of speed has a quasi‐Gaussian behavior, which is similar to that of large‐scale oceanic turbulent motions retrieved from satellite altimetry measurements. Also, the looping circulation pattern has the largest probability to cause significant speedup of ISW propagation, while the leaping pattern displays the lowest probability. These differences in wave characteristics caused by different circulation patterns result from the wave scattering, focusing and Doppler effects. Key Points: The speedup of internal solitary wave (ISW) induced by upstream South China Sea western boundary current (SCSwbc) is comparable to that induced by Coriolis force, while the amplitude shows obvious reductionCirculation under Kuroshio intrusion of looping path has high impact on wave characteristics, while that of leaping path has low impactThere is approximately one‐third time of 23 years (1993–2015) when circulation‐induced changes of wave speed exceed Coriolis‐induced changes [ABSTRACT FROM AUTHOR]

The Conductivity–Temperature–Depth (CTD) and acoustic Doppler current profiler (ADCP) measurements along 18°N off the western Luzon in the South China Sea (SCS), collected during a cruise from August 12–14, 2012, were used to explore the vertical structure of an anticyclonic eddy (AE) during the observational period. Further, the French Archiving, Validation and Interpretation of Satellite Oceanographic data (AVISO) sea level anomaly (SLA) and corresponding anomalous surface geostrophic velocity were used to study the temporal evolution of the AE. The vertical structure of the AE along 18°N in August 2012 showed a trough located near 117.5°E. The AE extended vertically downward and its distinct feature was identifiable to 200 m depth. Seasonal variations of SLA indicate that the AE lasted for 5 months (June to early November), going through the growth and nearly stationary period from mid-June to late August and then propagating westward along 18°N with varying phase speeds and shapes to the continental slope off the southeastern Hainan Island during late September to November. Furthermore, T–S characteristics suggest that the AE was generated off the western Luzon. Interannual variations of the summer (July–September) SLA presented by Empirical Orthogonal Function analysis, indicates that the local circulation was enhanced by the anomalous anticyclonic eddy along 18°N in the years of 2008, 2010, 2012 and 2013 during the period from1993 to 2014. [ABSTRACT FROM AUTHOR]

Satellite observations of sea level anomalies (SLA) from January 1993 to December 2012 are used to investigate the interannual to decadal changes of the boreal spring high SLA in the western South China Sea (SCS) using the Empirical Orthogonal Function (EOF) method. We find that the SLA variability has two dominant modes. The Sea Level Changing Mode (SLCM) occurs mainly during La Niña years, with high SLA extension from west of Luzon to the eastern coast of Vietnam along the central basin of the SCS, and is likely induced by the increment of the ocean heat content. The Anticyclonic Eddy Mode (AEM) occurs mainly during El Niño years and appears to be triggered by the negative wind curl anomalies within the central SCS. In addition, the spring high SLA in the western SCS experienced a quasi-decadal change during 1993-2012; in other words, the AEM predominated during 1993-1998 and 2002-2005, while the La Niña-related SLCM prevailed during 1999-2001 and 2006-2012. Moreover, we suggest that the accelerated sea level rise in the SCS during 2005-2012 makes the SLCM the leading mode over the past two decades. [ABSTRACT FROM AUTHOR]

In situ hydrographic and current observations from cruises in 1998 and 1999, together with 20-year (1993–2012) sea level anomaly (SLA) data from satellite altermeter, have been used to study the vertical structure, seasonal development, and interannual variability of the anticyclonic circulation in the southern South China Sea (SCS). The relationship between the anticyclonic circulation and its northern flanking cyclonic eddy are described. Three associated circulation patterns are identified. The anticyclonic circulation is present for an average of 108 ± 30 days per year, while its northern flanking cyclonic eddy is present for an average of 54 ± 25 days per year. The intraseasonal variability of the anticyclonic circulation is intense as a result of advection with the flanking northern cyclone, which accompanies the gyre on average about 60% of the time. The vertical structure of the anticyclonic circulation in 1998 (1999) penetrated much deeper, and its horizontal scope became wider in June (July) than in April. The anticyclonic circulation shows some difference between 1998 and 1999, displaying earlier appearance, more northward position, and non-dipole pattern in 1998, suggesting that the interannual variability of the anticyclonic circulation is related to El Niño Southern Oscillation (ENSO) events. The effect of Sverdrup balance via westward propagating Rossby wave on the seasonal development of the anticyclonic circulation has been discussed. [ABSTRACT FROM AUTHOR]

Interannual variations of the eddy kinetic energy (EKE) related to two types of winter circulation events ("O" and "U") were investigated based on the outputs of the Ocean General Circulation Model (OGCM) for the Earth Simulator (OFES) and the corresponding energetic analyses. Results show that the EKE is strong and extends eastward to offshore the Vietnam coast about 2°, associated with the weaker South China Sea western boundary current (SCSwbc) in "O" type years, while the EKE is weak and high value that can be attained is narrowed along the coast, associated with the stronger SCSwbc in "U" type years. The energy budget shows that the wind stress and barotropic/baroclinic instability are important factors to regulate the EKE in "U" and "O" years. For "U" years, under a strong winter monsoon forcing, the SCSwbc strengthen, the directly wind work and barotropic conversion from the mean kinetic energy (MKE) to EKE are weak, thus the EKE decrease corresponding to the baroclinic conversion from the kinetic energy to potential energy. However, the situation is reversed in "O" years. Under the influence of El Niño events, wind stress forces can weaken SCSwbc and enhance EKE in pattern "O", whereas La Niña events have relatively weaker influences. The barotropic conversion rate in "O" type is nearly eight times of the "U" type. The pressure work and advection term are the main sources to greatly suppress EKE in the SCSwbc region. [ABSTRACT FROM AUTHOR]

Sub-inertial currents (SICs) over the continental shelf of the northern South China Sea (NSCS) are investigated using the in-situ current observations of acoustic Doppler current profiler (ADCP) mooring arrays off the Pearl River Estuary in 2006 and 2007. The survey was carried out in four separate time periods: summer, winter, spring (before the onset of the southwesterly monsoon), and fall (after the establishment of the northeasterly monsoon). The observations showed that the current directions were generally along the shelf, consistent with the directions of monsoonal winds. The currents were also affected by a few of mesoscale eddy events. In summer 2006, the volume transport was northeastward with a mean magnitude of 1.4 Sv through a cross-shelf section from the site of the depth of 135 m to the coast; in winter 2006/2007, spring 2007 and fall 2007, the volume transports were all southwestward with magnitudes of 2.0, 2.1, and 0.9 Sv, respectively, through a cross-shelf section from the site of the depth of 290 m to the coast. The standard deviations of the SICs were generally smaller than the velocities of the mean currents, and the variability of SICs showed significant correlation with the local sea surface winds. No persistent counter-wind currents were observed in the study area during the fall and winter observational periods. [ABSTRACT FROM AUTHOR]

Abstract: Satellite observations of sea surface height (SSH) from 1993 to 2010 reveal a decadal variability of summer circulation in the South China Sea (SCS) with three phase changes in 1998, 2001 and 2006, respectively. There appears to be a large rise during 2006–2010 contributing to unprecedented anomalous high sea levels in 2010. The first leading empirical orthogonal function (EOF) mode of SSH exhibits an anomalous anticyclonic circulation pattern in the western central SCS north of 11°N, thus weakening the northern cyclone of the summer dipole during 2006–2010. The negative phase of the Pacific decadal oscillation (PDO) may have contributed to the anomalous high sea levels and disappearance of the summer dipole pattern. These variations reflect a linkage between the circulations of the SCS and Pacific Ocean. [Copyright &y& Elsevier]

Abstract: Satellite observations of sea level anomalies (SLAs), sea surface temperature (SST) and surface winds are used to investigate the anomalous oceanic characteristics in the South China Sea (SCS) during the 2006–2009 ENSO events. Two different features appeared during the 2007–2009 La Niña events: The SST was colder than normal during winter of 2007–2008, which lasted until May 2008 and was mainly associated with the strong northerly wind anomalies; the SLAs from June 2008 to February 2009 were the highest for the period of 2006–2009, which is part of SLAs in the western tropical Pacific region during the 2007/2009 La Niña events. All the anomalous features during 2007–2009 were well captured by the interannual EOF modes of the SST and SLAs, indicating the impacts of large-scale atmospheric and oceanic forcing. [Copyright &y& Elsevier]

Using 10-year (January 1998-October 2007) dataset of Sea-viewing Wide Field-of-view Sensor (SeaWiFS), we extracted the dominant spatial patterns and temporal variations of the chlorophyll distribution in the central western South China Sea (SCS) through Empirical Orthogonal Function (EOF) analysis. The results show that the first EOF mode is characterized by a high chlorophyll concentration zone along the Vietnam coast. We found two peaks in summer (July-August) and in winter (December), respectively, in normal years. The second EOF mode is characterized by a jet-shaped tongue of high chlorophyll concentration extending seaward to the northeast in summer (July-August). To investigate the interannual variability of the chlorophyll concentration, we extracted the first non-seasonal (annual cycle removed) EOF mode, which shows high spatial variability off the southeast Vietnam coast. Both spatial pattern and time coefficients correspond well with those of sea surface temperature mode, and are closely correlated to ENSO events, with a lag of 7 months. [ABSTRACT FROM AUTHOR]

21-day in-situ ADCP current and CTD data from an anchored observational station by RN Shiyan 3 are used to investigate the characteristics of internal tide in the northern South China Sea continental slope. The results show that tide and internal tide are both mixed type in the observed region and dominated by diurnals; the maximum internal tidal major axes of K1, O1 were largest and reached 11 cm/s, 10 cm/s, respectively, and their current vectors rotate anticlockwise. The 300 m-deep internal tide presents obvious quasi-diurnal oscillation and its average amplitude reaches 50 m. Furthermore, internal tide carried high energy; in the upper layers above 140 m, the kinetic energy of internal tides accounts for 15%-37% of overall kinetic energy, most of internal tide energy concentrates around the thermodine. [ABSTRACT FROM AUTHOR]

11-year satellite altimeter sea surface height (SSH) anomaly data from January 1993 to December 2003 are used to present the dominant spatial patterns and temporal variations of the South China Sea (SCS) surface circulation through Empirical Orthogonal Function (EOF) analysis. The first three EOF modes show the obvious seasonal variations of SSH in the SCS. EOF mode one is generally characterized by a basin-wide circulation. Mode two describes the double-cell basin scale circulation structure. The two cells were located off west of the Luzon Island and southeast of Vietnam, respectively. EOF mode three presents the mesoscale eddy structure in the western SCS, which develops into a strong cyclonic eddy rapidly from July to September. EOF mode one and mode three are also embedded with interannual signals, indicating that the SCS surface circulation variation is influenced by El Niño events prominently. The strong El Niño of 1997/98 obviously changed the SCS circulation structure. This study also shows that there existed a series of mesoscale eddies in the western SCS, and their temporal variation indicates intra-seasonal and interannual signals. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate the characteristics of strong internal solitons at the southern edge of Dongsha Islands in the northern South China Sea (SCS) during May-June 1998, using in situ time series data from the conductivity temperature depth (CTD), acoustic Doppler current profiler (ADCP) and thermistor chain. Our measurements indicated that the strongest internal solitons were larger than 90 m in wave amplitude, and propagated approximately westward in traveling direction, with the maximum current speed of about 2 m/s and the period of 10-20 min. The strongest internal solitons occurred noticeably during May 14-16, 1998, which is consistent with the occurrence period of the diurnal-dominated spring internal tides. [ABSTRACT FROM AUTHOR]

Analyzes the distributions of temperature, salinity and geopotential anomaly in the southern South China Sea. Circulation structure; Eddy; Oceanic front; Classification of the circulation structure as a two-layer pattern; Factors affecting the main circulation of the upper layer.

This study is the first to depict typhoon-induced continental shelf wave (CSW) propagation in the eastern Taiwan Strait (TWS) during the passage of Typhoon Meranti in 2016 using tidal gauge data and along-track satellite altimeter data. The strong amplitude response of sea level oscillations (within the range of 0.30–0.54 m) as a free, barotropic CSW after Meranti, which impacted the TWS, was clearly detected in time and frequency (in bands of 64–81 h) using wavelet and cross-wavelet analyses. The measured group and phase speeds were consistent with the dispersion curves for CSW with the first-mode derived from the cross-shelf sections of the eastern TWS, with the mean speeds reaching 3 and 5.6±0.7 m/s, respectively. Coincidentally, the typhoon-induced sea level anomaly (SLA) was also captured by the satellite altimeter before this CSW entered into the TWS. Using the theoretical cross-shore CSW modes to fit the SLA data, the results indicated that the first three wave modes can interpret this CSW event appeared in the southern TWS very well, with the first mode being the dominant one. [ABSTRACT FROM AUTHOR]

• Passing eddy center (edge), ISW amplitude is damped to nearly 0 (increased by 50%). • Background current at the eddy center (edge) damps (amplifies) ISW amplitude. • Different effects caused by eddy near eddy edge make ISW amplitude change largely. Internal solitary waves (ISWs) were observed by mooring data in the South China Sea in August and September 2014. Normally the arrival pattern of ISWs is relatively regular and the ISW amplitudes have a positive correlation with the magnitude of semidiurnal tidal currents near the Luzon Strait. However, the ISW amplitudes observed in the second spring tide of September are significantly large when an anti-cyclonic eddy is passing the mooring. When an ISW passes the eddy center, its amplitude reduces to nearly zero, but when an ISW passes the eddy edge, its amplitude increases by 50%. A deepened thermocline always damps the ISW amplitudes, whilst the eddy-induced background currents at different locations may have varied effects on the ISW amplitudes, e.g., the background current at the eddy center tends to damp the ISW amplitude but that at the eddy edge amplifies the ISW amplitude. The different effects of a deepened thermocline and eddy-induced background currents near the eddy edge may damp or amplify the ISW amplitude. [ABSTRACT FROM AUTHOR]

A correction to the article concerning the articles in the Volume 35 Number 1 of the journal "Journal of Oceanology and Limnology" is presented.