La2Ti2O7 nanosheets modified by Pt quantum dots for efficient NO removal avoiding NO2 secondary pollutant.

Two-dimensional La2Ti2O7 nanosheets with regular morphology and good dispersion were prepared by the hydrothermal method under a magnetic field. Zero-dimensional Pt quantum dots (Pt-QDs) were loaded on the La2Ti2O7 nanosheets. The electron-hole separation and carrier transfer in the Pt-loaded La2Ti2O7 nanosheets were significantly enhanced. The La2Ti2O7 nanosheets loaded with 3 wt% Pt-QDs exhibit the largest NO removal efficiency of 51% and less than 3.2 ppb NO2 intermediate pollutant in 30 min. The high photocatalytic ability was attributed to the surface plasmon resonance in Pt-QDs and the enhanced electron-hole separation. A large number of e-, h+, •OH and •O2- active species were formed on the surface of Pt-loaded La2Ti2O7 nanosheets under light irradiation. The conversion pathway from NO to NO3- was verified by the in situ diffuse reflectance infrared Fourier-transform spectroscopy and DFT calculation. This work supplies a feasible approach to responsive photocatalysts for efficient, stable, and selective NO removal avoiding the NO2 secondary pollutant.

Direct observation of carrier migration in heterojunctions to discuss the p-n and direct Z-scheme heterojunctions.

Type II p-n heterojunction and direct Z-scheme heterojunction are identical staggered band alignments, but were reported ambiguously in many composite photocatalysts because their carriers migrate in opposite directions. In this research, metal oxides CuO, NiO and Co3O4-based heterojunctions with Na0.9Mg0.45Ti3.55O8(NMTO) were synthesized via a simple hydrothermal method. The CuO/NMTO heterojunction was demonstrated as a direct Z-scheme heterojunction, whereas the NiO/NMTO and Co3O4/NMTO heterojunctions showed type II p-n band alignment, distinguished by the direct observation of carrier migration under light illumination, and confirmed by the x-ray photoelectron spectroscopy, Mott-Schottky measurements, ultraviolet photoelectron spectra and capture experiments. These all heterojunctions enjoyed better photocatalytic performance to degrade methylene blue and antibiotics (Enrofloxacin, Metronidazole and tetracycline) than the pure NMTO, attributed to their effective separation of the photoinduced electron-hole pairs owing to the staggered band alignment. Prominently, the NiO/NMTO and Co3O4/NMTO p-n heterojunctions exhibited superior degradation ability to the CuO/NMTO Z-scheme heterojunction. The initial relative Fermi position of two semiconductors is the prerequisite to determine whether the p-n heterojunction or direct Z-scheme heterojunction is built because the electrons diffuse from one semiconductor with a higher Fermi level to another with a lower Fermi level while the holes diffuse reversely until a united Fermi level when they combine. The built-in electric field at the heterojunction interface is determined by the difference in the initial Fermi levels or work functions of two semiconductors, regulating the separation ability of photogenerated electrons and holes to affect the photocatalytic performance. Thus, the high difference in the initial Fermi levels of semiconductors is crucial in the development of heterojunctions with staggered band alignment to obtain high performance in photocatalytic reactions.

Development of novel K0.8Ni0.4Ti1.6O4 nano bamboo leaves, microstructural characterization, double absorption, and photocatalytic removal of organic pollutant.

Novel K0.8Ni0.4Ti1.6O4 (KNTO) nano bamboo leaves were prepared for the first time under a simple hydrothermal method with 3 M KOH at 320 °C over 80 min. Highly pure KNTO possessing layered structure was determined by X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM). Double absorption feature of KNTO semiconductor was revealed at band energies of 1.88 and 2.08 eV by the UV-vis diffuse reflectance spectra and confirmed by the photoluminescence (PL) spectra. The photocatalytic activity was explored by the photodegradation of MB organic dye. KNTO not only exhibits strong adsorptive ability on methylene blue (MB) in dark environment, but also possesses good photodegradation capability of 94% degradation in 60 min. Degradation mechanism revealed that the photogenerated holes play an essential role in the MB degradation process, which is confirmed by trapping experiments. The recycling experiments demonstrated very high recycling ability and durability of KNTO nano bamboo leaves, suggesting KNTO is a potential candidate for high efficiency organic pollutant removal in the wastewater treatment.

The E3 Ubiquitin Ligase CRL4 Regulates Proliferation and Progression Through Meiosis in Chinese Mitten Crab Eriocheir sinensis.

The Cullin-RING E3s are multisubunit ubiquitin ligases composed of a scaffold protein known as Cullin, a RING finger protein that regulates diverse cellular pathways; however, their contribution to male gonad development, especially the spermatogenesis of the Chinese mitten crab (Eriocheir sinensis), is not well understood. We identified five evolutionarily conserved Cullins from the transcriptome and genome ofE. sinensis that are potentially involved in regulating male gonad development. The aim of the current study was to determine the mechanisms of Cullin4's effects on spermatogenesis. We observed that Cullin4, p53, and proliferating cell nuclear antigen had a specific expression and localization in primary spermatocytes. We also investigated the accumulation of Cullin substrates by treatment with inhibitor of NEDD8-activating enzyme MLN4924 in vitro. Cell cycle inhibitors p27 and p21 accumulated significantly after 24 and 36 h, respectively. We speculated that p53-mediated spontaneous germ cell apoptosis acts as a quality control mechanism to eliminate defective germ cells and that the Cullin4 complex maintains p53, p21, and p27 homeostasis in primary spermatocytes to regulate spermatogenesis ofE. sinensis Given its widespread evolutionary conservation, Cullin4 may regulate germ line development similarly in other organisms.

Mps1 regulates spindle morphology through MCRS1 to promote chromosome alignment.

Accurate partitioning of chromosomes during mitosis is essential for genetic stability and requires the assembly of the dynamic mitotic spindle and proper kinetochore-microtubule attachment. The spindle assembly checkpoint (SAC) monitors the incompleteness and errors in kinetochore-microtubule attachment and delays anaphase. The SAC kinase Mps1 regulates the recruitment of downstream effectors to unattached kinetochores. Mps1 also actively promotes chromosome alignment during metaphase, but the underlying mechanism is not completely understood. Here, we show that Mps1 regulates chromosome alignment through MCRS1, a spindle assembly factor that controls the dynamics of the minus end of kinetochore microtubules. Mps1 binds and phosphorylates MCRS1. This mechanism enables KIF2A localization to the minus end of spindle microtubules. Thus, our study reveals a novel role of Mps1 in regulating the dynamics of the minus end of microtubules and expands the functions of Mps1 in genome maintenance.

Characterization of the Es-DDX52 involved in the spermatogonial mitosis and spermatid differentiation in Chinese mitten crab (Eriocheir sinensis).

Spermatogenesis involves a series of process including exiting from the mitotic cell cycle, entry into meiosis, completion of complex differentiation programs, and producing spermatozoa. Expression of various genes in an ordered manner, and interactions between various genes and their protein products, primarily controlled at the post-transcriptional level with DEAD-box RNA helicases playing a crucial role in germ cell development, are required for production of fertile sperm. Many members of this family have been deeply studied in spermatogenesis, such as DDX3X, DDX25 and DDX4, but few data are available on DDX52. In this study, we analyzed the expression patterns of Es-DDX52, Es-DDX6, Es-Vasa and Es-XRN1 both at mRNA and protein levels in different tissues and during gonadal development. It showed that Es-vasa, Es-DDX6 and Es-Xrn1, components of cytoplasmic foci P-bodies, have the similar transcriptional expression pattern, while Es-DDX52 has the reverse tendency. Furthermore, Es-DDX6 and Es-XRN1 proteins have the same localization in testicular tissues. Es-DDX52 mainly distributed in the cytoplasm of spermatogonia, only localized in the nucleus of early and middle spermatid and shifted to pre-acrosome vesicle (later developed into apical cap and acrosome tube) at both mRNA and protein levels. These results indicated that Es-DDX52 may participate in regulation of P-bodies and microtubules by Es-XRN1, and involved in the mitosis of spermatonia and spermatid differentiation.

FOXL2 down-regulates vitellogenin expression at mature stage in Eriocheir sinensis.

Ovarian development in crustaceans is characterized by rapid production of egg yolk protein in a process called vitellogenesis. In the present study, we investigated the involvement of a DEAD (Asp-Glu-Ala-Asp) box RNA helicase 20 (DDX20), forkhead transcription factor (FOXL)2 and fushi tarazu factor (FTZ-F)1 in the regulation of vitellogenesis. Based on ESTs from the testis and accessory gland of Eriocheir sinensis, we cloned the full-length cDNAs of foxl2 and fushitarazu factor 1 (ftz-f1), which include the conserved structural features of the forkhead family and nuclear receptor 5A (NR5A) family respectively. The expression of foxl2 mRNA surged at the mature stage of the ovary, when vtg mRNA swooped, suggesting that foxl2 negatively affects the vitellogenin (VTG) synthesis at this developmental stage. Etoposide (inducing germ cell apoptosis) treatment up-regulated FOXL2 and DDX20 at both the mRNA and the protein levels, primarily in the follicular cells as shown by immunofluorescence analysis. Furthermore, foxl2, ddx20 and ftz-f1 mRNA levels increased significantly with right-eyestalk ablation. Interactions between FOXL2 and DDX20 or FTZ-F1 were confirmed by co-immunoprecipitation and the forkhead domain of FOXL2 was identified as the specific structure interacting with FTZ-F1. In conclusion, FOXL2 down-regulates VTG expression by binding with DDX20 in regulation of follicular cell apoptosis and with FTZ-F1 to repress the synthesis of VTG at the mature stage. This report is the first to describe the molecular mechanism of VTG synthesis in E. sinensis and may shed new light on the regulation of cytochrome P450 enzyme by FOXL2 and FTZ-F1 in vitellogenesis.

Profiling microRNAs in the testis during sexual maturation stages in Eriocheir sinensis.

MicroRNAs (miRNAs) have been implicated in several cellular processes of reproductive tissues through post-transcriptional regulation of protein coding genes. The presence of miRNAs, their expression patterns and processing machinery genes in different stages of testicular and ovarian cellular development have demonstrated the potential role of miRNAs in testicular and ovarian physiology. The Chinese mitten crab (Eriocheir sinensis) is one of the most important aquaculture species in China and has high commercial value as a food source. The molecular mechanisms underlying testis development in these and other crustaceans, which migrate to a new habitat to breed, remain poorly understood. We focus on the gonad of E. sinensis and systematically examined the expression profile of miRNAs in testes during sexual maturation stages using the Illumina Solexa sequencing technology. We found that the microRNA transcriptome exhibited dynamic expression during crab testis development. Subsequent bioinformatic analysis on both conserved and 15 novel miRNAs illustrated that some miRNAs demonstrated a tissue-specific expression pattern and were associated with target genes involved in reproductive function. Our study illustrates how detailed profiling of miRNA expression during stages of sexual maturation and in different tissues can lead to elucidate the role of miRNAs in regulating the development and differentiation of reproductive organs.

A Catalog of Proteins Expressed in the AG Secreted Fluid during the Mature Phase of the Chinese Mitten Crabs (Eriocheir sinensis).

The accessory gland (AG) is an important component of the male reproductive system of arthropods, its secretions enhance fertility, some AG proteins bind to the spermatozoa and affect its function and properties. Here we report the first comprehensive catalog of the AG secreted fluid during the mature phase of the Chinese mitten crab (Eriocheir sinensis). AG proteins were separated by one-dimensional gel electrophoresis and analyzed by reverse phase high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). Altogether, the mass spectra of 1173 peptides were detected (1067 without decoy and contaminants) which allowed for the identification of 486 different proteins annotated upon the NCBI database (http://www.ncbi.nlm.nih.gov/) and our transcritptome dataset. The mass spectrometry proteomics data have been deposited at the ProteomeXchange with identifier PXD000700. An extensive description of the AG proteome will help provide the basis for a better understanding of a number of reproductive mechanisms, including potentially spermatophore breakdown, dynamic functional and morphological changes in sperm cells and sperm acrosin enzyme vitality. Thus, the comprehensive catalog of proteins presented here can serve as a valuable reference for future studies of sperm maturation and regulatory mechanisms involved in crustacean reproduction.

Identification of ADAM10 and ADAM17 with potential roles in the spermatogenesis of the Chinese mitten crab, Eriocheir sinensis.

The ADAM (a disintegrin and metalloprotease) family plays an important role in sperm and egg fusion, development, inflammation, adhesion and migration. ADAM10 and ADAM17 are involved in the spermatogenesis. To better understand the role of ADAM10 and ADAM17 in the Chinese mitten crab, Eriocheir sinensis, the full-length cDNAs of ADAM10 and ADAM17 were cloned, and named Es-ADAM10 and Es-ADAM17, respectively. Sequence and structural analysis showed that Es-ADAM10 and Es-ADAM17 have the typical structure of the ADAM family. Quantitative real-time reverse transcription polymerase chain reaction analysis showed that Es-ADAM10 and Es-ADAM17 mRNAs were distributed in the heart, hepatopancreas, intestines, brain, muscle, thoracic ganglia, hemolymph, stomach, testis, ovary, gill and accessory gland. Both mRNAs were highly expressed in the muscles, and relatively high in the testis, ovary and accessory gland. In addition, the Es-ADAM17 mRNA level was detected in every stage of testis development, being relatively high from July to September, the lowest during October and November, increasing from December to January, and reached a peak in January. By contrast, the expression of Es-ADAM10 mRNA was constant during testis development. Immunofluorescence further showed that Es-ADAM10 and Es-ADAM17 proteins were present in the cytoplasm and cytomembrane of spermatocytes, and both detected in the sperm. Furthermore, etoposide induced upregulation of Es-ADAM17 and Es-ADAM10 at both the mRNA and protein levels. This study first showed that Es-ADAM10 and Es-ADAM17 were also involved in the spermatogenesis and mainly participated in the later germ cell apoptosis in E. sinensis.

P38 participates in spermatogenesis and acrosome reaction prior to fertilization in Chinese mitten crab Eriocheir sinensis.

P38 mitogen-activated protein kinases (MAPKs) comprise a family of serine/threonine protein kinases that play important roles in cellular responses to inflammatory cytokines and environmental stresses. These kinases are involved in controlling cell division, differentiation and death in mammalian testes and therefore are critical to spermatogenesis. To explore their functions in male reproduction of Chinese mitten crabs, Eriocheir sinensis p38 (Es-p38) protein expression was determined in different tissues including testes at different developmental stages by Western blot. Es-p38 was expressed in various tissues, with higher levels in the heart, stomach, gills and testes. Total Es-p38 protein levels increased gradually during spermatogenesis, but phosphorylated Es-p38 was much higher in the spermatid (August-October) than the spermatocyte (July-August) and sperm (October-January) stages. Trypan blue staining and hematoxylin/eosin staining were both used to detect sperm motility and changes in sperm morphology during the acrosome reaction (AR) induced by pre-incubation with A23187 in vitro, activated Es-p38 proteins detected by fluorescent microscopy were translocated gradually to nuclear and apical cap regions, accumulating at the anterior of the acrosomal tubule. The results suggest the involvement of p38 MAPK in spermatogenesis and the AR in E. sinensis.

ERK is involved in the process of acrosome reaction in vitro of the Chinese mitten crab, Eriocheir sinensis.

Mitogen-activated protein kinases (MAPKs), also termed extracellular signal-regulated kinases (ERKs), are cytoplasmic and nuclear serine/threonine kinases involved in signal transduction of several extracellular effectors. In mammals, ERKs participate in the regulation of spermatogenesis, mature spermatozoa motility, hyperactivation, and the acrosome reaction. To investigate ERK functions in Eriocheir sinensis reproduction, we successfully cloned the full-length ERK from the testis of E. sinensis (ES-ERK). The 1098-nucleotide open reading frame encodes a 365-amino-acid protein with a predicted molecular weight of 42 kDa. Expressions of ES-ERK in different tissues and testis development stages were detected by the quantitative RT-PCR and Western blotting. ES-ERK is expressed relatively highly in the testis. The expression of ES-ERK protein gradually increased in the spermatid stage, reaching a peak in sperm stage. Western blotting showed a similar expression pattern for the total ES-ERK protein, but phospho-ERK (p-ERK) showed the higher expression in spermatid than sperm stage. We also used trypan blue and hematoxylin and eosin staining to identify structural changes in E. sinensis spermatozoa during the process of acrosome reaction (AR). After stimulating the process of AR, the ES-ERK has translocated from the nucleus to the acrosomal tubule. This result suggested that the ERK MAPK might be involved in the regulation of the E. sinensis acrosome reaction.