The R2R3-MYB transcription factor ZeMYB32 negatively regulates anthocyanin biosynthesis in Zinnia elegans.

KEY MESSAGE: This study identified an R2R3-MYB from Zinnia elegans, ZeMYB32, which negatively regulates anthocyanin biosynthesis.

The podoplanin-CLEC-2 interaction promotes platelet-mediated melanoma pulmonary metastasis.

BACKGROUND: Podoplanin (PDPN) expressed on tumour cells interacts with platelet C-type lectin-like receptor 2 (CLEC-2). This study aimed to investigate the role of the PDPN-platelet CLEC-2 interaction in melanoma pulmonary metastasis. METHODS: Murine melanoma B16-F0 cells, which have two populations that express podoplanin, were sorted by FACS with anti-podoplanin staining to obtain purified PDPN + and PDPN- B16-F0 cells. C57BL/6J mice transplanted with CLEC-2-deficient bone marrow cells were used for in vivo experiments. RESULTS: The in vivo data showed that the number of metastatic lung nodules in WT mice injected with PDPN + cells was significantly higher than that in WT mice injected with PDPN- cells and in WT or CLEC-2 KO mice injected with PDPN- cells. In addition, our results revealed that the platelet Syk-dependent signalling pathway contributed to platelet aggregation and melanoma metastasis. CONCLUSIONS: Our study indicates that the PDPN-CLEC-2 interaction promotes experimental pulmonary metastasis in a mouse melanoma model. Tumour cell-induced platelet aggregation mediated by the interaction between PDPN and CLEC-2 is a key factor in melanoma pulmonary metastasis.

Expression of ethylene biosynthetic genes during flower senescence and in response to ethephon and silver nitrate treatments in Osmanthus fragrans.

BACKGROUND: Sweet osmanthus (Osmanthus fragrans) is an ornamental evergreen tree species in China, whose flowers are sensitive to ethylene. The synthesis of ethylene is controlled by key enzymes and restriction enzymes, 1-aminocyclopropane-1-carboxylic acid synthase (ACS) and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO), which are encoded by multigene families. However, the key synthase responsible for ethylene regulation in O. fragrans is still unknown. OBJECTIVE: This study aims to screen the key ethylene synthase genes of sweet osmanthus flowers in response to ethylene regulation. METHODS: In this study, we used the ACO and ACS sequences of Arabidopsis thaliana to search for homologous genes in the O. fragrans petal transcriptome database. These genes were also analyzed bioinformatically. Finally, the expression levels of O. fragrans were compared before and after senescence, as well as after ethephon and silver nitrate treatments. RESULTS: The results showed that there are five ACO genes and one ACS gene in O. fragrans transcriptome database, and the phylogenetic tree revealed that the proteins encoded by these genes had high homology to the ACS and ACO proteins in plants. Sequence alignment shows that the OfACO1-5 proteins have the 2OG-Fe(II) oxygenase domain, while OfACS1 contains seven conserved domains, as well as conserved amino acids in transaminases and glutamate residues related to substrate specificity. Expression analysis revealed that the expression levels of OfACS1 and OfACO1-5 were significantly higher at the early senescence stage compared to the full flowering stage. The transcripts of the OfACS1, OfACO2, and OfACO5 genes were upregulated by treatment with ethephon. However, out of these three genes, only OfACO2 was significantly downregulated by treatment with AgNO3. CONCLUSION: Our study found that OfACO2 is an important synthase gene in response to ethylene regulation in sweet osmanthus, which would provide valuable data for further investigation into the mechanisms of ethylene-induced senescence in sweet osmanthus flowers.

Effect of internal fractures on mechanical properties and failure of sandstone under multi-physical fields.

Under deep mining conditions, rocks are subjected to complex multi-physical fields and can contain numerous pores and fractures. To explore the influence and correlation of these factors on the physical and mechanical properties of fractured rock samples, this study conducted triaxial compression tests on sandstone specimens under various physical conditions using a rock full stress multi-field coupling triaxial tester. Additionally, a random fracture model for multi-field coupling numerical simulation was established. This allowed the study to obtain the mechanical parameters, failure mode, and internal fracture development of rocks under multi-physical field conditions. By analyzing the complete stress-strain curve, mechanical characteristic points, and permeability, a combination of laboratory tests and numerical simulations was used to examine how temperature, seepage, and stress fields affect the development of pores and fractures in rocks. It was found that the temperature field, under conventional geothermal conditions, generates tensile force through thermal expansion and the presence of fluid, thereby promoting fracture development within the rocks. This mechanism is similar to that of seepage. The confining pressure caused by deep geo stress uniformly inhibits the expansion of pores and fissures within the rocks.

Land use function change and its driving force of the "production-living-ecological" space in Fenhe River Basin from 1980 to 2020.

It is of importance to analyze land use function change and driving factors of the production-living-ecological space of national territory to realize the coordinated development. Based on land use remote sensing data in 1980, 1990, 2000, 2010, and 2020, we used the methods of land use dynamics, transfer matrix, center of gravity shift and geographic detector to analyze the pattern of production-living-ecological space in Fenhe River Basin and explore the influencing factors. The results showed that the area proportion of production-living-ecological space in the basin was ecological space > production space > living space from 1980 to 2020. The ecological space and agricultural production land showed a decreasing trend, with a decrease of 72441.19 and 105882.96 hm2, respectively. The living space and industrial production land showed an upward trend, with an increase of 119503.02 and 58821.13 hm2, respectively. There was significant difference in the land use function change of production-living-ecological space. Agricultural production land had the largest transferred area, accounting for 47.9% of the total. The largest transfer area of industrial land was agricultural land, which accounted for 61.3% of the total from 2000 to 2010. The occupation of agricultural land by urban living land was mainly distributed in the marginal area of various urban areas of Taiyuan Basin. Among them, the increasing area of urban living land in Taiyuan City showed a trend of gradual southward expansion. The center of gravity migration of urban land for living and industrial production land was the most obvious, and that for living showed the trend of first moving south and then moving north, while industrial production land moved northward significantly. The influence of social-economic factors on the land use change was obviously stronger than that of natural factors, while the interaction between social-economic factors had a stronger explanatory power. The results would provide reference for clarifying the relationship between land function transformation and optimizing land use function of production-living-ecological space.

Mechanical Behavior and Crack Evolution of Goaf Surrounding Rock with Different Roof-Contacted Filling Rates.

The goaf formed by mining is filled and treated, which greatly improves the safety and stability of the surrounding rock. During the filling process, the roof-contacted filling rates (RCFR) of goaf were closely related to the stability control of the surrounding rock. The influence of the roof-contacted filling rate on the mechanical characteristics and crack propagation of the goaf surrounding rock (GSR) has been studied. Biaxial compression experiments and numerical simulation experiments were conducted on samples under different operating conditions. The results were as follows: (1) The peak stress, peak strain, and elastic modulus of the GSR are closely related to the RCFR and the goaf size; they increase with the increase of the RCFR, and decrease with the increase of the goaf size; (2) In the initial loading stage, a small number of cracks are generated, and the acoustic emission ringing count increases slowly. The mid-loading stage is the crack initiation and rapid expansion, and the cumulative ring count curve shows a "stepwise" growth. In the later loading stage, cracks continue to propagate and form macroscopic fractures, but the number of rings significantly decreases; (3) Shear cracks are prone to occur in the rock part of the GSR; tensile cracks are prone to occur in the backfill; and the crack propagation speed in the rock is faster than in the backfill. Stress concentration is the direct cause of GSR failure. The maximum concentrated stress of rock mass and backfill is 1~2.5 times and 0.17~0.7 times of the peak stress of the GSR, respectively.

An ultra-light sustainable sponge for elimination of microplastics and nanoplastics.

The currently established tools and materials for elimination of the emerging contaminants from environmental and food matrices, particularly micro- and nano-scale plastics, have been largely limited by complicated preparation/operation, high cost, and poor degradability. Here we show that, crosslinking naturally occurring corn starch and gelatin produces ultralight porous sponge upon freeze-drying that can be readily enzymatically decomposed to glucose; The sponge affords capture of micro- and nano-scale plastics into its pores by simple pressing in an efficiency up to 90% while preserving excellent mechanical strength. Heterogeneous diffusion was found to play a dominant role in the adsorption of microplastics by the starch-gelatin sponge. Investigations into the performance of the sponge in complex matrices including tap water, sea water, soil surfactant, and take-out dish soup, further reveal a considerably high removal efficiency (60%∼70%) for the microplastics in the real samples. It is also suggested tiny plastics in different sizes be removable using the sponge with controlled pore size. With combined merits of sustainability, cost-effectiveness, and simple operation without the need for professional background for this approach, industrial and even household removal of tiny plastic contaminants from environmental and food samples are within reach.

Microplastic-contaminated antibiotics as an emerging threat to mammalian liver: enhanced oxidative and inflammatory damages.

Poor management and disposal of plastic materials and the accumulation of microplatics in the environment and foods are an issue of increasing public concern. The current understanding of the implications of microplastics for human health has been limited to the bioeffect of individual exposure. In the bigger view of microplastic contamination, however, toxic compounds, including antibiotics, harbored on active microplastics can be collectively transported through food chains, raising questions about the effect of their combined exposure on human health. By employing a mouse model for human physiology, we discovered that a concurrent exposure to the major types of antibiotics and microplastics, namely sulfamethoxazole (SMZ) and polystyrene microplastics, respectively, would result in evident accumulation in detoxification organs; specifically, liver could amass 41.70 µg kg-1 of SMZ, while 3.83% of microplastics was accumulated in the kidney. Insights into the occurrence of liver histopathological changes (e.g., amyloidosis and necrocytosis) revealed that compared with the individual treatment of SMZ, treatment by microplastic-contaminated SMZ elicited increases in the levels of malonaldehyde and NF-κß by 174% and 104%, respectively; while the activities of antioxidases investigated were depressed by up to 22% upon co-exposure. It is suggested that SMZ enriched on active microplastic surfaces causes enhanced hepatic damage. Profiling of the gene expression clarified the correlation of the exacerbated oxidative and inflammatory damages in the liver with the overexpression of Nrf2 to dysregulate the Keap1-Nrf2 pathway. This study acts as a reminder about the complexity of contamination and raises awareness of health issues that microplastics could cause public health through liver diseases.

ZeMYB9 regulates cyanidin synthesis by activating the expression of flavonoid 3'-hydroxylase gene in Zinnia elegans.

Petal color in Zinnia elegans is characterized mainly by anthocyanin accumulation. The difference in the content of anthocyanins, especially cyanidins, affects petal coloration in Z. elegans, but the underlying regulatory mechanism remains elusive. Here, we report one R2R3-MYB transcription factor from subgroup 6, ZeMYB9, acting as a positive regulator of anthocyanin accumulation in Z. elegans. Up-regulated expression of ZeMYB9 and flavonoid 3'-hydroxylase gene (ZeF3'H) was detected in the cultivar with higher cyanidin content. ZeMYB9 could specifically activate the promoter of ZeF3'H, and over-expression of ZeMYB9 induces much greater anthocyanin accumulation and higher expression level of anthocyanin biosynthetic genes in both petunia and tobacco. And then, ZeMYB9 was demonstrated to interact with ZeGL3, a bHLH transcription factor belonging to IIIf subgroup. Promoter activity of ZeF3'H was significantly promoted by co-expressing ZeMYB9 and ZeGL3 compared with expressing ZeMYB9 alone. Moreover, transient co-expression of ZeMYB9 and ZeGL3 induced anthocyanin accumulation in tobacco leaves. Our results suggest that ZeMYB9 could enhance cyanidin synthesis and regulate petal color in Z. elegans though activating the expression of ZeF3'H, by itself or interacting with ZeGL3.

Microplastics exposure as an emerging threat to ancient lineage: A contaminant of concern for abnormal bending of amphioxus via neurotoxicity.

Growing inputs of microplastics into marine sediment have increased significantly the needs for assessment of their potential risks to the marine benthos. A knowledge gap remains with regard to the effect of microplastics on benthos, such as cephalochordates. By employing amphioxus as a model benthic chordate, here we show that exposure to microplastics for 96 h at doses of 1 mg/L and 100 mg/L results in evident accumulation of the polyethylene microplastics. The accumulated microplastics are as much as 0.027% of body weight upon high-dose exposure, causing an abnormal body-bending phenotype that limits the locomotion capability of amphioxus. Mechanistic insight reveals that microplastics can bring about histological damages in gill, intestine and hepatic cecum; In-depth assay of relevant biomarkers including superoxide dismutase, catalase, glutathione, pyruvic acid and total cholesterol indicates the occurrence of oxidative damage and metabolic disorder; Further, microplastics exposure depresses the activity of acetylcholinesterase while allowing the level of acetylcholine to rise in muscle, suggesting the emergence of neurotoxicity. These consequences eventually contribute to the muscle dysfunction of amphioxus. This study rationalizes the abnormal response of the vulnerable notochord to microplastics, signifying the dilemma suffered by the ancient lineage under the emerging threat. Given the enrichment of microplastics through marine food chains, this study also raises significant concerns on the impact of microplastics to other marine organisms, and eventually human beings.

Temperature regulation of carotenoid accumulation in the petals of sweet osmanthus via modulating expression of carotenoid biosynthesis and degradation genes.

BACKGROUND: Temperature is involved in the regulation of carotenoid accumulation in many plants. The floral color of sweet osmanthus (Osmanthus fragrans Lour.) which is mainly contributed by carotenoid content, is affected by temperature in autumn. However, the mechanism remains unknown. Here, to reveal how temperature regulates the floral color of sweet osmanthus, potted sweet osmanthus 'Jinqiu Gui' were treated by different temperatures (15 °C, 19 °C or 32 °C). The floral color, carotenoid content, and the expression level of carotenoid-related genes in petals of sweet osmanthus 'Jinqiu Gui' under different temperature treatments were investigated. RESULTS: Compared to the control (19 °C), high temperature (32 °C) changed the floral color from yellow to yellowish-white with higher lightness (L*) value and lower redness (a*) value, while low temperature (15 °C) turned the floral color from yellow to pale orange with decreased L* value and increased a* value. Total carotenoid content and the content of individual carotenoids (α-carotene, ß-carotene, α-cryptoxanthin, ß-cryptoxanthin, lutein and zeaxanthin) were inhibited by high temperature, but were enhanced by low temperature. Lower carotenoid accumulation under high temperature was probably attributed to transcriptional down-regulation of the biosynthesis gene OfPSY1, OfZ-ISO1 and OfLCYB1, and up-regulation of degradation genes OfNCED3, OfCCD1-1, OfCCD1-2, and OfCCD4-1. Up-regulation of OfLCYB1, and down-regulation of OfNCED3 and OfCCD4-1 were predicted to be involved in low-temperature-regulated carotenoid accumulation. Luciferase assays showed that the promoter activity of OfLCYB1 was activated by low temperature, and repressed by high temperature. However, the promoter activity of OfCCD4-1 was repressed by low temperature, and activated by high temperature. CONCLUSIONS: Our study revealed that high temperature suppressed the floral coloration by repressing the expression of carotenoid biosynthesis genes, and activating the expression of carotenoid degradation genes. However, the relative low temperature had opposite effects on floral coloration and carotenoid biosynthesis in sweet osmanthus. These results will help reveal the regulatory mechanism of temperature on carotenoid accumulation in the petals of sweet osmanthus.

Overexpression of c-Myc-dependent heterogeneous nuclear ribonucleoprotein A1 promotes proliferation and inhibits apoptosis in NOTCH1-mutated chronic lymphocytic leukemia cells.

BACKGROUND: NOTCH1 mutation is an essential molecular biologic aberration in chronic lymphocytic leukemia (CLL). CLL patients with NOTCH1 mutation have shown an unfavorable survival and a poor response to chemoimmunotherapy. This study aims to present the mechanisms of adverse prognosis caused by NOTCH1 mutation from the perspective of the splicing factor heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1). METHODS: The microarray data in Gene Expression Omnibus datasets were analyzed by bioinformatics and the function of hnRNPA1 was checked by testing the proliferation and apoptosis of CLL-like cell lines. Afterward, quantitative reverse transcription-polymerase chain reaction and Western blotting were applied to explore the relationship among NOTCH1, c-Myc, and hnRNPA1. RESULTS: RNA splicing was found to play a vital part in NOTCH1-mutated CLL cells; hence, hnRNPA1 was selected as the focus of this study. Higher expression of hnRNPA1 validated in primary NOTCH1-mutated CLL samples could promote proliferation and inhibit apoptosis in CLL. The expression of hnRNPA1 increased when NOTCH1 signaling was activated by transfection with NOTCH1 intracellular domain (NICD)-overexpressed adenovirus vector and declined after NOTCH1 signaling was inhibited by NOTCH1-shRNA. Higher expression of c-Myc was observed in NICD-overexpressed cells and hnRNPA1 expression was downregulated after applying c-Myc inhibitor 10058-F4. Moreover, in NICD-overexpressed cells, hnRNPA1 expression decreased through c-Myc inhibition. CONCLUSION: Overexpression of c-Myc-dependent hnRNPA1 could promote proliferation and inhibit apoptosis in NOTCH1-mutated CLL cells, which might partly account for the poor prognosis of patients with NOTCH1 mutation.

Genome-Wide Identification of Petunia HSF Genes and Potential Function of PhHSF19 in Benzenoid/Phenylpropanoid Biosynthesis.

Volatile benzenoids/phenylpropanoids are the main flower scent compounds in petunia (Petunia hybrida). Heat shock factors (HSFs), well known as the main regulator of heat stress response, have been found to be involved in the biosynthesis of benzenoid/phenylpropanoid and other secondary metabolites. In order to figure out the potential function of HSFs in the regulation of floral scent in petunia, we systematically identified the genome-wide petunia HSF genes and analyzed their expression and then the interaction between the key petunia HSF gene with target gene involved in benzenoid/phenylpropanoid biosynthesis. The results revealed that 34 HSF gene family members were obtained in petunia, and most petunia HSFs contained one intron. The phylogenetic analysis showed that 23 petunia HSFs were grouped into the largest subfamily HSFA, while only two petunia HSFs were in HSFC subfamily. The DBD domain and NLS motif were well conserved in most petunia HSFs. Most petunia HSF genes' promoters contained STRE motifs, the highest number of cis-acting element. PhHSF19 is highly expressed in petal tubes, followed by peduncles and petal limbs. During flower development, the expression level of PhHSF19 was dramatically higher at earlier flower opening stages than that at the bud stage, suggesting that PhHSF19 may have potential roles in regulating benzenoid/phenylpropanoid biosynthesis. The expression pattern of PhHSF19 is positively related with PhPAL2, which catalyzes the first committed step in the phenylpropanoid pathway. In addition, there are three STRE elements in the promoter of PhPAL2. PhHSF19 was proven to positively regulate the expression of PhPAL2 according to the yeast one hybrid and dual luciferase assays. These results lay a theoretical foundation for further studies of the regulation of HSFs on plant flower scent biosynthesis.

A peroxisomal heterodimeric enzyme is involved in benzaldehyde synthesis in plants.

Benzaldehyde, the simplest aromatic aldehyde, is one of the most wide-spread volatiles that serves as a pollinator attractant, flavor, and antifungal compound. However, the enzyme responsible for its formation in plants remains unknown. Using a combination of in vivo stable isotope labeling, classical biochemical, proteomics and genetic approaches, we show that in petunia benzaldehyde is synthesized via the ß-oxidative pathway in peroxisomes by a heterodimeric enzyme consisting of α and ß subunits, which belong to the NAD(P)-binding Rossmann-fold superfamily. Both subunits are alone catalytically inactive but, when mixed in equal amounts, form an active enzyme, which exhibits strict substrate specificity towards benzoyl-CoA and uses NADPH as a cofactor. Alpha subunits can form functional heterodimers with phylogenetically distant ß subunits, but not all ß subunits partner with α subunits, at least in Arabidopsis. Analysis of spatial, developmental and rhythmic expression of genes encoding α and ß subunits revealed that expression of the gene for the α subunit likely plays a key role in regulating benzaldehyde biosynthesis.

A microscopic survey on microplastics in beverages: the case of beer, mineral water and tea.

It has been reported that microplastics exist ubiquitously in aquatic and terrestrial environments. Microplastic surveys on diverse daily foods with high consumption possibly containing microplastics have essential implications in clarifying the contamination routes, health risk assessment, and thereby preventing food pollution. Given the dependence of microplastic pollution on the regional environment, production and transportation, it further remains an open question on the number, size distribution and type of microplastics in foods from different countries worldwide. Here, we show that daily drinks produced worldwide, including beer, mineral water and tea, are all polluted with microplastics without exception. The number of microplastics investigated in this work lies in the range of 20-80 mL-1 for the beers, 10 mL-1 for the bottled mineral water, and 200-500 g-1 for the tea leaves. Quasi-spherical particles and irregular fragments dominate the shape of microplastics in beer and mineral water, whereas tea leaves carry numerous microplastic fibers. By identification through Raman spectroscopy, we observed the presence of polystyrene (PS) and polypropylene (PP) microplastics in beers, PP in bottled mineral water, and polyethylene (PE) and polyethylene terephthalate (PET) in tea leaves. Possible contamination sources include raw materials, atmosphere, and tools and containers that release microplastics. Given the facile adsorption of heavy metals and antibiotics to microplastics in beverages, public concern may arise regarding the accumulation of microplastics through the food chain and their synergetic harmful effect. Thus, our results should inspire further efforts that may contribute to the elimination and removal of microplastics from foods.

[Spatial-temporal differentiation of mountain-water-forest-farmland-lake-grass system in Qinghai area of the Qilian Mountain National Park, China]. / ç¥è¿žå±±å›½å®¶å ¬å›­é’æµ·ç‰‡åŒºå±±æ°´æž—ç”°æ¹–è‰çš„æ—¶ç©ºåˆ†å¼‚.

Higher and more precise requirements are critically needed for the protection, regulation, and restoration of ecological environment in the Qilian Mountain National Park after it is classified as a national park system pilot in China. Based on remote sensing data in 1980-2018, the spatial pattern map of mountain-water-forest-farmland-lake-grass system was constructed to analyze its spatial-temporal variations in the general control area and core conservation area in Qinghai area of the Qilian Mountain National Park. The results showed that grasslands, with an area of 8174.93 km2, were the main landscape in the park, and that grassland area in the core conservation area was 1.2 times as that of the general control area. The bare exposed rocks, a major type of unused land, accounted for 86.7% and 79.4% of the unused land in the core conservation area and the general control area, respectively. Forest area in the general control area was larger than that in the core conservation area. Water area in the core conservation area was 4.9 times as large as that in the general control area, with 90.4% of which being dominated by permanent glaciers and snowfields. The drylands were mainly concentrated in the general control area. From 1980 to 2018, the water area was decreasing and had been reduced by 186.75 km2. The area of permanent glaciers and snowfields decreased the most, with a drop of 12.05 and 175.88 km2 in the general control area and the core conservation area, respectively. The area of forests and grasslands were enlarged constantly. The changes of high-, medium-, and low-coverage grasslands in the core conservation area were greater than that in the general control area, which were the most significant during 1990-2000. Moreover, the degradation of high- and medium-coverage grasslands in the general control area as well as high- and low-coverage grasslands in the core conservation area was observed from 1980 to 2018. The area of bare exposed rocks was on the rise, while the permanent glaciers and snowfields displayed a decreasing trend. The permanent glaciers and snowfields and the bare exposed rocks exhibited the most obvious changes in the park. The glaciers in the core conservation area retreated remarkably faster than those in the general control area, which were transformed into the bare exposed rocks mainly in 1980-1990 and 2000-2010.

Co-occurrence of KIT and NRAS mutations defines an adverse prognostic core-binding factor acute myeloid leukemia.

Molecular abnormalities are frequent in core-binding factor (CBF) AMLs, but their prognostic relevance is controversial. Sixty-two patients were retrospectively analyzed and 47 harbored at least one gene mutation with a next-generation-sequencing assay. The most common molecular mutation was KIT mutation (30.6%), followed by NRAS (24.2%) and ASXL1 (14.5%) mutations, which was associated with a higher number of bone marrow blasts (p = .049) and older age (p = .027). The survival analysis showed KIT mutation adversely affected the overall survival (OS) (p = .046). NRAS mutation was associated with inferior OS (p = .016) and RFS (p = .039). Eight patients carried co-mutations of KIT and NRAS and had worse OS (p = .012) and RFS (p = .034). The multivariate analysis showed age ≥60 years and additional chromosomal abnormalities were significant adverse factors for OS. Thus, co-mutations of KIT and NRAS were significantly associated with a poor prognosis and should be taken into account when assessing for prognostic stratification in patients with CBF-AML.

Slc35a1 deficiency causes thrombocytopenia due to impaired megakaryocytopoiesis and excessive platelet clearance in the liver.

Sialic acid is a common terminal residue of glycans on proteins and acidic sphingolipids such as gangliosides and has important biological functions. The sialylation process is controlled by more than 20 different sialyltransferases, many of which exhibit overlapping functions. Thus, it is difficult to determine the overall biological function of sialylation by targeted deletion of individual sialyltransferases. To address this issue, we established a mouse line with the Slc35a1 gene flanked by loxP sites. Slc35a1 encodes the cytidine-5'-monophosphate (CMP)-sialic acid transporter that transports CMP-sialic acid from the cytoplasm into the Golgi apparatus for sialylation. Here we report our study regarding the role of sialylation on megakaryocytes and platelets using a mouse line with significantly reduced sialylation in megakaryocytes and platelets (Plt Slc35a1­ /­). The major phenotype of Plt Slc35a1­/­ mice was thrombocytopenia. The number of bone marrow megakaryocytes in Plt Slc35a1­/­ mice was reduced, and megakaryocyte maturation was also impaired. In addition, an increased number of desialylated platelets was cleared by Küpffer cells in the liver of Plt Slc35a1­/­ mice. This study provides new insights into the role of sialylation in platelet homeostasis and the mechanisms of thrombocytopenia in diseases associated with platelet desialylation, such as immune thrombocytopenia and a rare congenital disorder of glycosylation (CDG), SLC35A1-CDG, which is caused by SLC35A1 mutations.

Transcriptomic analysis of flower opening response to relatively low temperatures in Osmanthus fragrans.

BACKGROUND: Sweet osmanthus (Osmanthus fragrans Lour.) is one of the top ten traditional ornamental flowers in China. The flowering time of once-flowering cultivars in O. fragrans is greatly affected by the relatively low temperature, but there are few reports on its molecular mechanism to date. A hypothesis had been raised that genes related with flower opening might be up-regulated in response to relatively low temperature in O. fragrans. Thus, our work was aimed to explore the underlying molecular mechanism of flower opening regulated by relatively low temperature in O. fragrans. RESULTS: The cell size of adaxial and abaxial petal epidermal cells and ultrastructural morphology of petal cells at different developmental stages were observed. The cell size of adaxial and abaxial petal epidermal cells increased gradually with the process of flower opening. Then the transcriptomic sequencing was employed to analyze the differentially expressed genes (DEGs) under different number of days' treatments with relatively low temperatures (19 °C) or 23 °C. Analysis of DEGs in Gene Ontology analysis showed that "metabolic process", "cellular process", "binding", "catalytic activity", "cell", "cell part", "membrane", "membrane part", "single-organism process", and "organelle" were highly enriched. In KEGG analysis, "metabolic pathways", "biosynthesis of secondary metabolites", "plant-pathogen interaction", "starch and sucrose metabolism", and "plant hormone signal transduction" were the top five pathways containing the greatest number of DEGs. The DEGs involved in cell wall metabolism, phytohormone signal transduction pathways, and eight kinds of transcription factors were analyzed in depth. CONCLUSIONS: Several unigenes involved in cell wall metabolism, phytohormone signal transduction pathway, and transcription factors with highly variable expression levels between different temperature treatments may be involved in petal cell expansion during flower opening process in response to the relatively low temperature. These results could improve our understanding of the molecular mechanism of relatively-low-temperature-regulated flower opening of O. fragrans, provide practical information for the prediction and regulation of flowering time in O. fragrans, and ultimately pave the way for genetic modification in O. fragrans.

[Changes of growing season NDVI at different elevations, slopes, slope aspects and its relationship with meteorological factors in the southern slope of the Qilian Mountains, China from 1998 to 2017]. / 1998­2017年祁连山南坡不同海拔、坡度和坡向生长季NDVIå˜åŒ–åŠå ¶ä¸Žæ°”è±¡å› å­çš„å ³ç³».

Qilian Mountains is an important water conservation area in Northwest China, which is the boundary between the first and second steps of China's topography and is sensitive to climate change. Based on the data of temperature, precipitation, normal difference vegetation index (NDVI), and digital elevation model (DEM) data, we analyzed NDVI change and its relationship with temperature and precipitation along the elevation, slope and slope aspect in the southern slope of Qilian Mountains using tendency analysis method, wavelet analysis and correlation analysis. The results showed that, from 1998 to 2017, NDVI value of the growing season presented increasing trend by a rate of 0.023·10 a-1. Changes of NDVI differed at different elevations, slopes and slope aspects. NDVI increased first and then decreased with elevation. The vegetation coverage at 2700-3700 m was good, and degraded in the area of >4700 m. NDVI reduced with the increases of slope, which showed little difference in different slope aspects but was better in sunny slope than in shade slope. NDVI of the growing season was closely related with temperature and precipitation. NDVI, temperature and precipitation in growing season all had a 14-year cycle. Vegetation at different elevations, slopes and slope aspects was differently affected by temperature and precipitation. Vegetation in areas with altitude <3700 m, >4700 m, slope <25° and each slope direction was more sensitive to precipitation.