Specific Impact of Tobamovirus Infection on the Arabidopsis Small RNA Profile

Tobamoviruses encode a silencing suppressor that binds small RNA (sRNA) duplexes in vitro and supposedly in vivo to counteract antiviral silencing. Here, we used sRNA deep-sequencing combined with transcriptome profiling to determine the global impact of tobamovirus infection on Arabidopsis sRNAs and their mRNA targets. We found that infection of Arabidopsis plants with Oilseed rape mosaic tobamovirus causes a global size-specific enrichment of miRNAs, ta-siRNAs, and other phased siRNAs. The observed patterns of sRNA enrichment suggest that in addition to a role of the viral silencing suppressor, the stabilization of sRNAs might also occur through association with unknown host effector complexes induced upon infection. Indeed, sRNA enrichment concerns primarily 21-nucleotide RNAs with a 5′-terminal guanine. Interestingly, ORMV infection also leads to accumulation of novel miRNA-like sRNAs from miRNA precursors. Thus, in addition to canonical miRNAs and miRNA*s, miRNA precursors can encode additional sRNAs that may be functional under specific conditions like pathogen infection. Virus-induced sRNA enrichment does not correlate with defects in miRNA-dependent ta-siRNA biogenesis nor with global changes in the levels of mRNA and ta-siRNA targets suggesting that the enriched sRNAs may not be able to significantly contribute to the normal activity of pre-loaded RISC complexes. We conclude that tobamovirus infection induces the stabilization of a specific sRNA pool by yet unknown effector complexes. These complexes may sequester viral and host sRNAs to engage them in yet unknown mechanisms involved in plant:virus interactions

Three-dimensional structure of a low salinity tongue in the southern Taiwan Strait observed in the summer of 2005

Cruise observations with CTD (conductivity-temperature-depth) profiler were carried out in the southern Taiwan Strait in the summer of 2005. Using the cruise data, two-dimensional maps of salinity and temperature distributions at depths of 5, 10, 15, 20, and 30 m were generated. The maps show a low salinity tongue sandwiched by low temperature and high salinity waters on the shallow water side and high temperature and high salinity waters on the deep water side. The further analysis indicates that the low salinity water has a nature of river-diluted water. A possible source of the diluted water is the Zhujiang (Pearl) Estuary. Meanwhile, the summer monsoon is judged as a possible driving force for this northeastward jet-like Current. The coastal upwelling and the South China Sea Warm Current confine the low salinity water to flow along the central line of the strait. Previous investigations and a numerical model are used to verify that the upstream of the low salinity current is the Zhujiang Estuary. Thus, the low salinity tongue is produced by four major elements: Zhujinag Estuary diluted water, monsoon wind driving, coastal upwelling and South China Sea Warm Current modifications.National Natural Science Foundation of China [40331004, 40576015, 40810069004, 40821063]; MEL Open Project [MEL0506]; ONR [N00014-05-1-0328, N00014-05-1-0606]; NSF [071003-9222

One new species of free-living marine nematode from the Yellow Sea, China

Hao, Yingdong, Hu, Quanan, Huang, Yong (2021): One new species of free-living marine nematode from the Yellow Sea, China. Zootaxa 4999 (3): 273-278, DOI: 10.11646/zootaxa.4999.3.

Validation of microtubule-associated Tobacco mosaic virus RNA movement and involvement of microtubule-aligned particle trafficking

Functional studies of Tobacco mosaic virus (TMV) infection using virus derivatives expressing functional,dysfunctional, and temperature-sensitive movement protein (MP) mutants indicated that the cell-to-celltransport of TMV RNA is functionally correlated with the association of MP with microtubules. However, therole of microtubules in the movement process during early infection remains unclear, since MP accumulates onmicrotubules rather late in infection and treatment of plants with microtubule-disrupting agents fails tostrongly interfere with cell-to-cell movement of TMV RNA. To further test the role of microtubules in TMV cellto-cell movement, we investigated TMV strain Ni2519, which is temperature-sensitive for movement. Wedemonstrate that the temperature-sensitive defect in movement is correlated with temperature-sensitivechanges in the localization of MP to microtubules. Furthermore, we show that during early phases of recoveryfrom non-permissive conditions, the MP localizes to microtubule-associated particles. Similar particles arefound in cells at the leading front of spreading TMV infection sites. Initially mobile, the particles becomeimmobile when MP starts to accumulate along the length of the particle-associated microtubules. Ourobservations confirm a role for microtubules in the spread of TMV infection and associate this role withmicrotubule-associated trafficking of MP-containing particles in cells engaged in the cell-to-cell movement ofthe TMV genome

Strong near-inertial oscillations in geostrophic shear in the northern South China Sea

National Basic Research Program of China [2009CB421208]; Natural Science Foundation of China [40976013, 40821063]; United States National Oceanic and Atmospheric Administration [05-01-11-000]With observational data from three Acoustic Doppler Current Profiler (ADCP) moorings, we detected strong near-inertial oscillations (NIO) in the continental shelf region of the northern South China Sea in July 2008. The amplitude of the near-inertial current velocity is much greater than that of diurnal and semi-diurnal tides. The power of the NIOs is strongest in the intermediate layer, relatively weak in the surface layer, and insignificant in the near-bottom layer. The spectral analysis indicates that the NIOs have a peak frequency of 0.0307 cph, which is 2% lower than the local inertial frequency, i.e., a red-shift. The near-inertial wave has an upward vertical phase velocity, which involves a downward group velocity and energy flux. The estimated vertical phase velocity is about 43 m day(-1), corresponding to a vertical wave length of about 58 m. The horizontal scale of the NIOs is at least hundreds of kilometers. This NIO event lasted for about 15 days after a typhoon's passage. Given the northeastward background flow with significant horizontal shear, both Doppler shift and shear flow modulation mechanisms may be responsible for the red-shift of the observed NIOs. For the shear flow mechanism, the observed negative background vorticity and the corresponding effective Coriolis frequency reduce the lower limit of admissible frequency band for the NIOs, causing the red-shift. Meanwhile, the mooring area with the broadened frequency band acts as a wave-guide. The trapping and amplification effects lead to the relatively long sustaining period of the observed NIOs

Penetration of nonlinear Rossby eddies into South China Sea evidenced by cruise data

From the analyses of the cruise conductivity-temperature-depth profiler and acoustic Doppler current profiler data combined with simultaneous satellite altimeter data and Argo float profiling data, this paper provides evidence for the nonlinear Rossby eddies (NREs) penetrating through the Kuroshio and the Luzon Strait and entering the South China Sea (SCS). A high-salinity water prism in the subsurface layer west of the Luzon Strait was observed in January 2010. The salty prism centered at around 21 degrees N and 118 degrees E has a salinity higher than 34.8 and co-locates with an anticyclonic eddy with a diameter of about 150 km. The water properties of the salty prism are close to those of the Northwest Pacific (NWP) water. The time series of altimeter data and Argo float profiling data indicate that the anticyclonic eddy originates from an NRE that propagates westward from the NWP. The eddy penetrates the Luzon Strait at a speed of about 0.6 m s(-1) because of the effects of the narrow strait and the Kuroshio-eddy interaction and carries the high-salinity subsurface water from the NWP into the northern SCS.National Basic Research Program of China [2009CB421208, 2007CB411803]; Natural Science Foundation of China [40976013, 41121091]; United States of America National Oceanic; Atmospheric Administration National Environmental Satellite, Data, and Information Service Ocean Remote Sensing [3000-11-03241

Winter-spring fronts in Taiwan Strait

[ 1] Fine structures of surface fronts during winter-spring in the Taiwan Strait and their evolution over time are studied using satellite and in situ data. At times, different water masses are interleaved into each other. The northward intruding warm water bifurcates into several branches, causing complicated multiple cross strait fronts with maximum surface temperature gradients at the fronts to be greater than 2 degrees C/km. The mean surface velocity of the fronts estimated from a sequence of satellite images is between 0.15 and 0.3 m/s during the February - March 2001 frontal event. The speed appears to have accelerated during the latter stages from 0.2 m/s during March 2 - 4 to 0.3 m/s during March 4 - 6. The total northward transport associated with the passage of the fronts is estimated to be 0.6 - 1 Sv between February 16 and March 6, 2001. The timescale of the passage of the fronts through the entire Taiwan Strait is therefore at least four weeks. Hydrographic observations in February - March of 1998 and 2000 also demonstrate similar frontal events with strong vertical gradients of water temperature and salinity on the western side of the strait. The 1998 data also show clearly that the low temperature and low salinity Zhemin Coastal Current separates from the coast and enters into the middle of the strait, a feature consistent with the satellite observations