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Genetic analysis revealed that CmCLV3 is a candidate gene for the variation in melon carpel number. Carpel number (CN) is an important trait in melon. Three-CN melon fruit is oval, while 5-CN melon fruit has a round or flat shape. Herein, a genetic analysis of a population in which the CN locus was segregated indicated that 3-CN is controlled by a major dominant effective gene. Bulked segregant analysis and initial linkage mapping placed the CN locus in a 6.67 Mb region on chromosome 12, and it was narrowed to 882.19 kb with molecular markers and recombinant plants. Fine mapping with a large F

Vitamin A deficiency is a worldwide public nutrition problem, and β-carotene is the precursor for vitamin A synthesis. Watermelon with golden flesh (gf, due to accumulated abundance of β-carotene) is an important germplasm resource. In this study, a genetic analysis of gf segregating populations indicated that gf was controlled by a single recessive gene. BSA-seq and an initial linkage analysis placed the gf locus in a 290-Kb region on watermelon chromosome 1. Further fine mapping in a large population with over 1,000 F2 plants narrowed this region to 39.08 Kb harboring two genes, Cla97C01G008760 and Cla97C01G008770, which encode phytoene synthase (ClPsy1) and GATA zinc finger domain-containing protein, respectively. Gene sequence alignment and expression analysis between parental lines revealed Cla97C01G008760 as the best possible candidate gene for gf trait. Nonsynonymous SNP mutations in the first exon of ClPsy1 between parental lines cosegregated with the gf trait only among individuals in the genetic population but were not related to flesh color in natural watermelon panels. Promoter sequence analysis of 26 watermelon accessions revealed two SNPs in the cis-acting element sequences corresponding to MYB and MYC2 transcription factors. RNA-seq data and qRT-PCR verification showed that two MYBs and one MYC2 exhibited expression trends similar as ClPsy1 in the parental lines, which may thus play roles in the regulation of ClPsy1 expression. Our research findings indicate that the gf trait is determined not only by ClPsy1 but also by ClLCYB, ClCRTISO and ClNCED7, which play important roles in β-carotene accumulation in watermelon flesh.

The mammalian Mediator complex consists of over 30 subunits and functions as a transcriptional hub integrating signaling for tissue-specific gene expression. Although the role of the Mediator complex in transcription has been extensively investigated, the functions of distinct Mediator subunits in development are not well understood. Here, we dissected the role of the Mediator subunit Med23 in mouse cardiovascular development. Endothelial-specific Med23 deletion caused embryonic lethality before embryonic day 13.5 (E13.5). The mutant embryos exhibited intracranial hemorrhage and diminished angiogenesis with dilated blood vessels in the head region, where the expression of Med23 was abundant at E10.5. Med23 deficiency impaired vasculogenesis in the head region and impeded retinal angiogenesis. Knocking down Med23 in human umbilical vein endothelial cells (HUVECs) resulted in angiogenic defects, recapitulating the vascular defects in Med23-mutant mice in a cell-autonomous manner. RNA sequencing in HUVECs indicated that Med23 deficiency resulted in the interruption of angiogenesis and the upregulation of angiopoietin2 (Ang2), an inducing factor for vascular network instability. Inhibition of Ang2 partially rescued angiogenic sprouting and lumen dilation defects in tube formation assays. Collectively, our findings demonstrate that Med23 promotes angiogenesis and maintains vascular integrity, in part by suppressing Ang2 signaling.

Somatic cell reprogramming by exogenous factors requires cooperation with transcriptional co-activators and co-repressors to effectively remodel the epigenetic environment. How this interplay is regulated remains poorly understood. Here, we demonstrate that NCoR/SMRT co-repressors bind to pluripotency loci to create a barrier to reprogramming with the four Yamanaka factors (OCT4, SOX2, KLF4 and c-MYC), and consequently, suppressing NCoR/SMRT significantly enhances reprogramming efficiency and kinetics. The core epigenetic subunit of the NCoR/SMRT complex, histone deacetylase 3 (HDAC3), contributes to the effects of NCoR/SMRT by inducing histone deacetylation at pluripotency loci. Among the Yamanaka factors, recruitment of NCoR/SMRT–HDAC3 to genomic loci is mostly facilitated by c-MYC. Hence, we describe how c-MYC is beneficial for the early phase of reprogramming but deleterious later. Overall, we uncover a role for NCoR/SMRT co-repressors in reprogramming and propose a dual function for c-MYC in this process. Zhuang et al. demonstrate that suppression of NCoR/SMRT enhances OSKM reprogramming efficiency, and that the barrier mechanism depends on the recruitment of HDAC3 to pluripotency loci by c-MYC.

With the increased availability of nanoparticle-based products, their releases to soil are undoubtedly inevitable. Among the nanoparticle-based products, potential risks of metal oxide nanoparticles (MO-ENPs) have attracted increasing concerns. However, their effects on soil and soil microorganisms remain largely unknown. In this study, four metal oxide nanoparticles, i.e., zinc oxide nanoparticles (nZnO), titanium dioxide nanoparticles (nTiO2), cerium dioxide nanoparticles (nCeO2), and magnetite nanoparticles (nFe3O4), were enrolled to evaluate their impact on soil enzyme activities (invertase, urease, catalase, and phosphatase) and bacterial communities in two typical soils from northeast China (black soil and saline-alkali soil). The community structure and size were analyzed using pyrosequencing and real-time polymerase chain reaction (RT-PCR). The soils were exposed to metal oxide nanoparticles at 0.5, 1.0, and 2.0 mg g−1 for 15 and 30 days. In general, nZnO had a stronger effect on soil enzymatic activities than nTiO2, nCeO2, and nFe3O4, and saline-alkali soil was more susceptible to metal oxide nanoparticles than black soil. In RT-PCR analysis, a significant decrease (41.66, 36.34, and 47.99%, respectively) on total bacteria population was only observed in saline-alkali soil treated by 0.5, 1.0, and 2.0 mg g−1 nZnO. Meanwhile, pyrosequencing analysis revealed that the samples of saline-alkali soil treated with nZnO showed high variance in their bacterial community composition, e.g., Bacilli, Alphaproteobacteria, and Gammaproteobacteria class. The results suggested that metal oxide nanoparticle incubation could influence soil enzyme activities and change soil bacterial community. Moreover, the soil type was a key component dictating the effect of metal oxide nanoparticles on the bacterial community composition and size. These findings are of great help towards building a comprehensive understanding of the potential environmental risks of metal oxide nanoparticles.

Hand, foot and mouth disease (HFMD) is a childhood disease causing large outbreaks frequently in Asia and occasionally in Europe and the US. The incubation period of HFMD was typically described as about 3-7 days but empirical evidence is lacking. In this study, we estimated the incubation period of HFMD from school outbreaks in Hong Kong, utilizing information on symptom onset and sick absence dates of students diagnosed with HFMD. A total of 99 HFMD cases from 12 schools were selected for analysis. We fitted parametric models accounting for interval censoring. Based on the best-fitted distributions, the estimated median incubation periods were 4.4 (95% CI 3.8-5.1) days, 4.7 (95% CI 4.5-5.1) days and 5.7 (95% CI 4.6-7.0) days for children in kindergartens, primary schools and secondary schools respectively. From the fitted distribution, the estimated incubation periods can be longer than 10 days for 8.8% and 23.2% of the HFMD cases in kindergarten and secondary schools respectively. Our results show that the incubation period of HFMD for secondary schools students can be longer than the ranges commonly described. An extended period of enhanced personal hygiene practice and disinfection of the environment may be needed to control outbreaks., published_or_final_version

3-Phosphoinositide-dependent protein kinase 1 (PDK1) is a pivotal regulator in the phosphoinositide 3-kinase (PI3K)-Akt signaling pathway that have been shown to play key roles in the functional development of B and T cells via activation of AGC protein kinases during hematopoiesis. However, the role of PDK1 in HSCs has not been fully defined. Here we specifically deleted the PDK1 gene in the hematopoietic system and found that PDK1-deficient HSCs exhibited impaired function and defective lineage commitment abilities. Lack of PDK1 caused HSCs to be less quiescent and to produce a higher number of phenotypic HSCs and fewer progenitors. PDK1-deficient HSCs were also unable to reconstitute the hematopoietic system. Notably, HSC function was more dependent on PDK1 than on mTORC2, which indicates that PDK1 plays a dominant role in the Akt-mediated regulation of HSC function. PDK1-deficient HSCs also exhibited reduced ROS levels, and treatment of PDK1-deficient HSCs with L-butathioninesulfoximine in vitro elevated the low ROS level and promoted colony formation. Therefore, PDK1 appears to contribute to HSC function partially via regulating ROS levels.

Gas vesicles are hollow, air-filled polyprotein structures that provide the buoyancy to cells. They are found in a variety of prokaryotes. In this study, we isolated a partial gas vesicle protein gene cluster containing gvpA and gvpC20Ψ from Planktothrix rubescens, and inserted it into an expression vector and expressed it in E. coli. The gas vesicle was developed in bacterial cells, which made bacterial cells to float on medium surface. We also amplified gvpA and gvpC20Ψ separately and synthesized an artificial operon by fusing these two genes with the standardized gene expression controlling elements of E. coli. The artificial operon was expressed in E. coli, forming gas vesicles and floating bacteria cells. Our findings verified that the whole set of genes and the overall structure of gas vesicle gene cluster are not necessary for developing gas vesicles in bacteria cells. Two genes, gvpA and gvpC20Ψ, of the gas vesicle gene cluster are sufficient for synthesizing an artificial operon that can develop gas vesicles in bacteria cells. Our findings provided a wide range of applications including easing the harvest of cultured microalgae and bacteria, as well as enriching and remediating aquatic pollutants by constructing gas vesicles in their cells.

Coronary arteries bring blood flow to the heart muscle. Understanding the developmental program of the coronary arteries provides insights into the treatment of coronary artery diseases. Multiple sources have been described as contributing to coronary arteries including the proepicardium, sinus venosus (SV), and endocardium. However, the developmental origins of coronary vessels are still under intense study. We have produced a new genetic tool for studying coronary development, an AplnCreER mouse line, which expresses an inducible Cre recombinase specifically in developing coronary vessels. Quantitative analysis of coronary development and timed induction of AplnCreER fate tracing showed that the progenies of subepicardial endothelial cells (ECs) both invade the compact myocardium to form coronary arteries and remain on the surface to produce veins. We found that these subepicardial ECs are the major sources of intramyocardial coronary vessels in the developing heart. In vitro explant assays indicate that the majority of these subepicardial ECs arise from endocardium of the SV and atrium, but not from ventricular endocardium. Clonal analysis of Apln-positive cells indicates that a single subepicardial EC contributes equally to both coronary arteries and veins. Collectively, these data suggested that subepicardial ECs are the major source of intramyocardial coronary arteries in the ventricle wall, and that coronary arteries and veins have a common origin in the developing heart.

In the version of this Article originally published, in Fig. 2c, the '+' sign and 'OSKM' were superimposed in the label '+OSKM'. In Fig. 4e, in the labels, all instances of 'Ant' should have been 'Anti-'. And, in Fig. 7a, the label '0.0' was misplaced; it should have been on the colour scale bar. These figures have now been corrected in the online versions.

Macrophages acquire distinct phenotypes during tissue stress and inflammatory responses, but the mechanisms that regulate the macrophage polarization are poorly defined. Here we show that tuberous sclerosis complex 1 (TSC1) is a critical regulator of M1 and M2 phenotypes of macrophages. Mice with myeloid-specific deletion of TSC1 exhibit enhanced M1 response and spontaneously develop M1-related inflammatory disorders. However, TSC1-deficient mice are highly resistant to M2-polarized allergic asthma. Inhibition of the mammalian target of rapamycin (mTOR) fails to reverse the hypersensitive M1 response of TSC1-deficient macrophages, but efficiently rescues the defective M2 polarization. Deletion of mTOR also fails to reverse the enhanced inflammatory response of TSC1-deficient macrophages. Molecular studies indicate that TSC1 inhibits M1 polarization by suppressing the Ras GTPase-Raf1-MEK-ERK pathway in mTOR-independent manner, whereas TSC1 promotes M2 properties by mTOR-dependent CCAAT/enhancer-binding protein-β pathways. Overall, these findings define a key role for TSC1 in orchestrating macrophage polarization via mTOR-dependent and independent pathways.

Hypertrophic cardiomyopathy (HCM) is a leading cause of heart failure and sudden death in adolescents and young adults. Recently, the role of the Hippo/YAP pathway has been investigated in the pathogenesis of HCM, although the detailed molecular mechanisms largely remain elusive. In this study, we demonstrated an up-regulation of YAP mRNA and protein levels in both HCM patient samples and transverse aortic constriction murine models as well as reduced phosphorylation of YAP at serine 127 accompanied by increased transcription of YAP-mediated genes in hypertrophic heart tissues. The cardiomyocyte-specific transgene of human YAP induced cardiac hypertrophy and increased fetal gene expression in the heart. In primary cultured murine cardiomyocytes, ectopic expression of YAP resulted in increased cellular size, whereas the knockdown of YAP reduced the cell size induced by phenylephrine treatment. Interestingly, both mRNA and protein levels of MST1, the kinase upstream of YAP, were dramatically decreased. Further experiments showed that transcription factor FOXO3 binds to the MST1 promoter and that the PI3 K/Akt/FOXO3 signaling pathway regulates MST1 expression. Our findings define the alteration of the Hippo/YAP pathway in the development of HCM. The exploitation of this pathway may provide a novel therapeutic avenue for this disease.

G-quadruplex (G4) DNA and G4 DNA resolvase are involved in a variety of biological processes. To understand the biological function of G4 DNA structures and their resolvases in spermatogenesis, we investigated the distribution of G4 structures in mouse testis and identified their alterations during spermatogenesis. Meanwhile, we studied the function of RNA helicase associated with AU-rich element (RHAU), a G4 DNA resolvase, in spermatogenesis with a germ-cell-specific knockout mouse model. The results showed that the ablation of RHAU in germ cells caused the increase of G4 structures and thus resulted in the decrease of spermatogonial differentiation. c-kit, a spermatogonia differentiation-related gene, contains two G4 DNA motifs on its promoter. We found its expression was significantly downregulated in RHAU conditional knockout testis. A further analysis demonstrated that RHAU directly bound to the G4 structures to activate c-kit expression. We concluded that RHAU regulates spermatogonia differentiation by promoting c-kit expression via directly binding to the G4 DNA motifs c-kit promoter.