Offspring Sex Is Not Determined by Gestation Temperature in a Viviparous Lizard(Eremias multiocellata) from the Desert Steppe of Inner Mongolia

Sex-determining systems show a striking diversity not only among species, but also among popula tions. In reptiles, sex-determina tion is a continuum, from tempera ture-dependent sex determination(TSD) to genetic sex determination(GSD).The multi-ocellated racerunner(Eremias multiocellata)is reported to be a cryptic ZZ/ZW chromosomal TSD species, with male-biased sex ratios at high temperatures in two Gansu populations. However, the generality of the sex-determining pattern in different populations of this species remains unclear. To investigate the mode of sex determina tion in a popula tion of E.multiocellata from the desert steppe of Inner Mongolia,we first identified sex chromosomes via comparative genomic hybridization(CGH). We then conducted a thermal manipulation experiment to determine the effect of gestation temperature on offspring sex ratios.From the CGH studies we found that lizards from the Inner Mongolia population possessed ZZ/ZW sex chromosomes. However, our thermal manipulation experiment showed that gestation temperature did not affect the sex ratio of neonates in this population. In combination, these results rule out TSD in the Inner Mongolia population of E. multiocellata, and suggest that there is widespread geographic variation in the sexdetermining system of this species.

Study on Antioxidant Enzyme Activity and Physiology and Biochemistry of Solanum nigrum L. under Glyphosate Stress

[Objectives] This study was conducted to investigate the scientific prevention and control of Solanum nigrum L. [Methods] Through experiments on S. nigrum from different sources, it was found that glyphosate stress had significant effects on antioxidant enzyme activity and oxidative damage of sensitive S. nigrum plants. [Results] Sensitive S. nigrum showed oxidative damage under glyphosate stress, while resistant S. nigrum responded to adversity damage by improving its antioxidant enzyme activity. The experimental results showed that the antioxidant enzymes and reduced glutathione of S. nigrum had certain metabolic detoxification effects under glyphosate stress. [Conclusions] This study provides a theoretical basis for scientific prevention and control of S. nigrum , and has a certain reference value for revealing the glyphosate resistance mechanism of S. nigrum .

Solution structure of the RNA recognition domain of METTL3-METTL14 N^6-methyladenosine methyltransferase

N^6-methyladenosine(m6A),a ubiquitous RNA modification,is installed by METTL3-METTL14 complex.The structure of the heterodimeric complex between the methyltransferase domains(MTDs)of METTL3 and METTL14 has been previously determined.However,the MTDs alone possess no enzymatic activity.Here we present the solution structure for the zinc finger domain(ZFD)of METTL3,the inclusion of which fulfills the methyltransferase activity of METTL3-METTL14.We show that the ZFD specifically binds to an RNA containing 5'-GGACU-3'consensus sequence,but does not to one without.The ZFD thus serves as the target recognition domain,a structural feature previously shown for DNA methyltransferases,and cooperates with the MTDs of METTL3-METTL14 for catalysis.However,the interaction between the ZFD and the specific RNA is extremely weak,with the binding affinity at several hundred micromolar under physiological conditions.The ZFD contains two CCCH-type zinc fingers connected by an anti-parallel P-sheet.Mutational analysis and NMR titrations have mapped the functional interface to a contiguous surface.As a division of labor,the RNA-binding interface comprises basic residues from zinc finger 1 and hydrophobic residues fromβ-sheet and zinc finger 2.Further we show that the linker between the ZFD and MTD of METTL3 is flexible but partially folded,which may permit the cooperation between the two domains during catalysis.Together,the structural characterization of METTL3 ZFD paves the way to elucidate the atomic details of the entire process of RNA m6A modification.

High-speed femtosecond laser plasmonic lithography and reduction of graphene oxide for anisotropic photoresponse

Micro/nanoprocessing of graphene surfaces has attracted significant interest for both science and applications due to its effective modulation of material properties,which,however,is usually restricted by the disadvantages of the current fabrication methods.Here,by exploiting cylindrical focusing of a femtosecond laser on graphene oxide(GO)films,we successfully produce uniform subwavelength grating structures at high speed along with a simultaneous in situ photoreduction process.Strikingly,the well-defined structures feature orientations parallel to the laser polarization and significant robustness against distinct perturbations.The proposed model and simulations reveal that the structure formation is based on the transverse electric(TE)surface plasmons triggered by the gradient reduction of the GO film from its surface to the interior,which eventually results in interference intensity fringes and spatially periodic interactions.Further experiments prove that such a regular structured surface can cause enhanced optical absorption(>20%)and an anisotropic photoresponse(~0.46 ratio)for the reduced GO film.Our work not only provides new insights into understanding the laser-GO interaction but also lays a solid foundation for practical usage of femtosecond laser plasmonic lithography,with the prospect of expansion to other two-dimensional materials for novel device applications.

Structural Insights into the Substrate Recognition Mechanism of Arabidopsis GPP-Bound NUDX1 for Noncanonical Monoterpene Biosynthesis

Dear Editor,In plants, monoterpenes are a large family of volatiles that play essential roles in communicating with the surrounding environment, including pollinator attraction, pathogen defense, and plant-plant interactions （Sun et al., 2016）.

Birefringent response of graphene oxide film structurized via femtosecond laser

In-plane birefringent materials present an effective modulation of the optical properties and more degrees of freedom for the signal detection in low dimension,and thus remain a hot topic in realizing the integrated,miniature,and flexible devices for multiple applications.Here,the artificial in-plane birefringence properties have been successfully achieved on a graphene oxide film by a novel femtosecond laser lithography method,which provides a high-speed,large-area,and regular subwavelength gratings(~380 nm)fabrication and photoreduction.The obtained sample manifests an evident optical birefringence(~0.18)and anisotropic photoresponse(~1.21)in the visible range,both of which can be significantly modulated by either the structural morphology or the degree of oxide reduction.Based on the analysis of effective-medium theory and measurements of angle-resolved polarized Raman spectroscopy,the artificial in-plane birefringence is originated from various optical responses of the periodic subwavelength structures for the incident light with different polarization states.This technique shows great advantages for the fabrication of integrated in-plane polarization-dependent devices,which is expected to solve the problems in this field,such as the deficient selection of materials,complex design of micro/nanostructure,and inflexible processing technology.

SERS study on the synergistic effects of electric field enhancement and charge transfer in an Ag2S quantum dots/plasmonic bowtie nanoantenna composite system

Localized surface plasmon resonance(LSPR)of nanostructures and the interfacial charge transfer(CT)of semiconductor materials play essential roles in the study of optical and photoelectronic properties.In this paper,a composite substrate of Ag2S quantum dots(QDs)coated plasmonic Au bowtie nanoantenna(BNA)arrays with a metalinsulator-metal(MIM)configuration was built to study the synergistic effect of LSPR and interfacial CT using surface-enhanced Raman scattering(SERS)in the near-infrared(NIR)region.The Au BNA array structure with a large enhancement of the localized electric field(E-field)strongly enhanced the Raman signal of adsorbed p-aminothiophenol(PATP)probe molecules.Meanwhile,the broad enhanced spectral region was achieved owing to the coupling of LSPR The as-prepared Au BNA array structure facilitated enhancements of the excitation as well as the emission of Raman signal simultaneously,which was established by finite-difference time-domain simulation.Moreover,Ag2S semiconductor QDs were introduced into the BNA/PATP system to further enhance Raman signals,which benefited from the interfacial CT resonance in the BNA/Ag2S-QDs/PATP system.As a result,the Raman signals of PATP in the BNA/Ag2S-QDs/PATP system were strongly enhanced under 785 nm laser excitation due to the synergistic effect of E-field enhancement and interfacial CT.Furthermore,the SERS polarization dependence effeas of the BNA/Ag2S-QDs/PATP system were also investigated.The SERS spectra indicated that the polarization dependence of the substrate increased with decreasing polarization angles(θpola)of excitation from p-polarized(θpola=90°)excitation to s-polarized(θpola=0°)excitation.This study provides a strategy using the synergistic effect of interfacial CT and E-field enhancement for SERS applications and provides a guidance for the development of SERS study on semiconductor QD-based plasmonic substrates,and can be farther extended to other material-nanostructure systems for various optoelectronic and sensing applications.

Specific RNA Recognition by Designer Pentatricopeptide Repeat Protein

Manipulation of gene expression through targeting specific DNA or RNA sequences is a significant challenge, tn the past decade, transcription activator-like （TAL） effectors and zinc fingers （ZFs） have been successfully developed into useful tools for DNA recognition （Bogdanove and Voytas, 2011; Deng et al., 2012a, 2012b）. However, little progress has been made in the realm of RNA targeting due to the lack of understanding about the modular RNA recognition mechanism.