Copine proteins are required for brassinosteroid signaling in maize and Arabidopsis.

Copine proteins are highly conserved and ubiquitously found in eukaryotes, and their indispensable roles in different species were proposed. However, their exact function remains unclear. The phytohormone brassinosteroids (BRs) play vital roles in plant growth, development and environmental responses. A key event in effective BR signaling is the formation of functional BRI1-SERK receptor complex and subsequent transphosphorylation upon ligand binding. Here, we demonstrate that BONZAI (BON) proteins, which are plasma membrane-associated copine proteins, are critical components of BR signaling in both the monocot maize and the dicot Arabidopsis. Biochemical and molecular analyses reveal that BON proteins directly interact with SERK kinases, thereby ensuring effective BRI1-SERK interaction and transphosphorylation. This study advances the knowledge on BR signaling and provides an important target for optimizing valuable agronomic traits, it also opens a way to study steroid hormone signaling and copine proteins of eukaryotes in a broader perspective.

Intra-ovarian inflammatory states and their associations with embryo quality in normal-BMI PCOS patients undergoing IVF treatment.

BACKGROUND: Polycystic ovary syndrome (PCOS) is the main cause of anovulatory infertility in women of reproductive age, and low-grade chronic inflammation plays a key role in the occurrence and development of PCOS. However, obesity, as a likely confounding factor, can affect the inflammatory state of PCOS patients. OBJECTIVE: The aim of this study was to comprehensively investigate intra-ovarian inflammatory states and their impact on embryo quality in PCOS patients with a normal BMI undergoing IVF treatment. METHODS: DIA-mass spectrometry-based proteomics and bioinformatic analysis were combined to comprehensively profile the protein expression of granulosa cells (GCs) from 5 normal-BMI PCOS patients and 5 controls. Thirty-four cytokines were further systematically detected in follicular fluid (FF) from 32 age- and BMI-matched normal-BMI patients using Luminex liquid chip suspension technology. Next, the differentially expressed cytokines were evaluated by enzyme-linked immunosorbent assay (ELISA) in 24 newly recruited subjects, and the relationship between these cytokines and embryo quality in PCOS patients was analysed. Finally, these cytokine levels were compared and evaluated in PCOS patients with different androgen levels. RESULTS: Proteomic analysis showed that the suppression of substance metabolism and steroid biosynthesis, more interestingly, resulted in an enhanced immune and inflammatory response in the GCs of normal-BMI PCOS patients and prompted the involvement of cytokines in this process. Luminex analysis further showed that FF macrophage inflammatory protein-1 beta (MIP-1ß) and stromal cell-derived factor-1 alpha (SDF-1α) levels were significantly increased in normal-BMI PCOS patients compared to controls (P = 0.005; P = 0.035, respectively), and the ELISA results were consistent with these findings. Besides, FF MIP-1ß showed an inverse correlation with the number of D3 good-quality embryos and the good-quality blastocyst rate in patients with PCOS (P = 0.006; P = 0.003, respectively), which remained significant after correction for multiple comparisons. Moreover, SDF-1α levels had no relationship with embryo development in PCOS patients. Additionally, SDF-1α levels were significantly lower in PCOS patients with high androgen levels than in controls (P = 0.031). CONCLUSIONS: Local ovarian inflammation was present in normal-BMI PCOS patients, affecting follicular development, and FF MIP-1ß may be a potential biomarker associated with embryo quality in normal-BMI PCOS patients.

Characterization and fine mapping of a maize lesion mimic mutant (Les8) with enhanced resistance to Curvularia leaf spot and southern leaf blight.

KEY MESSAGE: A novel light-dependent dominant lesion mimic mutant with enhanced multiple disease resistance was physiologically, biochemically, and genetically characterized; the causal gene was fine mapped to a 909 kb interval containing 38 genes. Identification of genes that confer multiple disease resistance (MDR) is crucial for the improvement of maize disease resistance. However, very limited genes are identified as MDR genes in maize. In this study, we characterized a dominant disease lesion mimics 8 (Les8) mutant that had chlorotic lesions on the leaves and showed enhanced resistance to both curvularia leaf spot and southern leaf blight. Major agronomic traits were not obviously altered, while decreased chlorophyll content was observed in the mutant, and the genetic effect of the Les8 mutation was stable in different genetic backgrounds. By BSR-seq analysis and map-based cloning, the LES8 gene was mapped into a 909 kb region containing 38 candidate genes on chromosome 9 wherein no lesion mimic or disease-resistance genes were previously reported. Using transcriptomics analysis, we found that genes involved in defense responses and secondary metabolite biosynthesis were enriched in the significantly up-regulated genes, while genes involved in photosynthesis and carbohydrate-related pathways were enriched in the significantly down-regulated genes in Les8. In addition, there was an overaccumulation of jasmonic acid and lignin but not salicylic acid in Les8. Taken together, this study revealed candidate genes and potential mechanism underlying Les8-conferred MDR in maize.

Comparative Transcriptome Analysis Reveals Common and Developmental Stage-Specific Genes That Respond to Low Nitrogen in Maize Leaves.

A growing leaf can be divided into three sections: division zone, elongation zone, and maturation zone. In previous studies, low nitrogen (LN) inhibited maize growth and development, especially leaf growth; however, the gene expression in response to LN in different regions in leaf were not clear. Here, using hydroponics and a transcriptome approach, we systematically analyzed the molecular responses of those zones and differentially expressed genes (DEG) in response to LN supply. Developmental stage-specific genes (SGs) were highly stage-specific and involved in distinct biological processes. SGs from division (SGs-DZ) and elongation zones (SGs-EZ) were more related to developmentally dependent processes, whereas SGs of the maturation zone (SGs-MZ) were more related to metabolic processes. The common genes (CGs) were overrepresented in carbon and N metabolism, suggesting that rebalancing carbon and N metabolism in maize leaves under LN condition was independent of developmental stage. Coexpression modules (CMs) were also constructed in our experiment and a total of eight CMs were detected. Most of SGs-DZ and SGs-EZ were classified into a set termed CM turquoise, which was mainly enriched in ribosome and DNA replication, whereas several genes from SGs-MZ and CGs were clustered into CM blue, which mainly focused on photosynthesis and carbon metabolism. Finally, a comprehensive coexpression network was extracted from CM blue, and several maize CONSTANS-LIKE(ZmCOL) genes seemed to participate in regulating photosynthesis in maize leaves under LN condition in a developmental stage-specific manner. With this study, we uncovered the LN-responsive CGs and SGs that are important for promoting plant growth and development under insufficient nitrogen supply.

Geographical resistome profiling in the honeybee microbiome reveals resistance gene transfer conferred by mobilizable plasmids.

BACKGROUND: The spread of antibiotic resistance genes (ARGs) has been of global concern as one of the greatest environmental threats. The gut microbiome of animals has been found to be a large reservoir of ARGs, which is also an indicator of the environmental antibiotic spectrum. The conserved microbiota makes the honeybee a tractable and confined ecosystem for studying the maintenance and transfer of ARGs across gut bacteria. Although it has been found that honeybee gut bacteria harbor diverse sets of ARGs, the influences of environmental variables and the mechanism driving their distribution remain unclear. RESULTS: We characterized the gut resistome of two closely related honeybee species, Apis cerana and Apis mellifera, domesticated in 14 geographic locations across China. The composition of the ARGs was more associated with host species rather than with geographical distribution, and A. mellifera had a higher content of ARGs in the gut. There was a moderate geographic pattern of resistome distribution, and several core ARG groups were found to be prevalent among A. cerana samples. These shared genes were mainly carried by the honeybee-specific gut members Gilliamella and Snodgrassella. Transferrable ARGs were frequently detected in honeybee guts, and the load was much higher in A. mellifera samples. Genomic loci of the bee gut symbionts containing a streptomycin resistance gene cluster were nearly identical to those of the broad-host-range IncQ plasmid, a proficient DNA delivery system in the environment. By in vitro conjugation experiments, we confirmed that the mobilizable plasmids could be transferred between honeybee gut symbionts by conjugation. Moreover, "satellite plasmids" with fragmented genes were identified in the integrated regions of different symbionts from multiple areas. CONCLUSIONS: Our study illustrates that the gut microbiota of different honeybee hosts varied in their antibiotic resistance structure, highlighting the role of the bee microbiome as a potential bioindicator and disseminator of antibiotic resistance. The difference in domestication history is highly influential in the structuring of the bee gut resistome. Notably, the evolution of plasmid-mediated antibiotic resistance is likely to promote the probability of its persistence and dissemination. Video Abstract.

Honeybee gut Lactobacillus modulates host learning and memory behaviors via regulating tryptophan metabolism.

Honeybees are highly social insects with a rich behavioral repertoire and are a versatile model for neurobiological research. Their gut microbiota comprises a limited number of host-restricted bacterial phylotypes that are important for honeybee health. However, it remains unclear how specific gut members affect honeybee behaviors. Here, we find that antibiotic exposure disturbs the gut community and influences honeybee phenotypes under field conditions. Using laboratory-generated gnotobiotic bees, we show that a normal gut microbiota is required for olfactory learning and memory abilities. Brain transcriptomic profiling reveals distinct brain gene expression patterns between microbiota-free and conventional bees. Subsequent metabolomic analyses of both hemolymph and gut samples show that the microbiota mainly regulates tryptophan metabolism. Our results indicate that host-specific Lactobacillus strains promote memory behavior by transforming tryptophan to indole derivatives that activate the host aryl hydrocarbon receptor. Our findings highlight the contributions of specific gut members to honeybee neurological processes, thus providing a promising model to understand host-microbe interactions.

Distinct Roles of Honeybee Gut Bacteria on Host Metabolism and Neurological Processes.

The honeybee possesses a limited number of bacterial phylotypes that play essential roles in host metabolism, hormonal signaling, and feeding behavior. However, the contribution of individual gut members in shaping honeybee brain profiles remains unclear. By generating gnotobiotic bees which were mono-colonized by a single gut bacterium, we revealed that different species regulated specific modules of metabolites in the hemolymph. Circulating metabolites involved in carbohydrate and glycerophospholipid metabolism pathways were mostly regulated by Gilliamella, while Lactobacillus Firm4 and Firm5 mainly altered amino acid metabolism pathways. We then analyzed the brain transcriptomes of bees mono-colonized with these three bacteria. These showed distinctive gene expression profiles, and genes related to olfactory functions and labor division were upregulated by Lactobacillus. Interestingly, differentially spliced genes in the brains of gnotobiotic bees largely overlapped with those of bees unresponsive to social stimuli. The differentially spliced genes were enriched in pathways involved in neural development and synaptic transmission. We showed that gut bacteria altered neurotransmitter levels in the brain. In particular, dopamine and serotonin, which show inhibitory effects on the sensory sensitivity of bees, were downregulated in bacteria-colonized bees. The proboscis extension response showed that a normal gut microbiota is essential for the taste-related behavior of honeybees, suggesting the contribution of potential interactions among different gut species to the host's physiology. Our findings provide fundamental insights into the diverse functions of gut bacteria which likely contribute to honeybee neurological processes. IMPORTANCE The honeybee possesses a simple and host-restricted gut community that contributes to the metabolic health of its host, while the effects of bacterial symbionts on host neural functions remain elusive. We found that the colonization of specific bee gut bacteria regulates distinct circulating metabolites enriched in carbohydrate, amino acid, and glycerophospholipid metabolic pathways. The brains of bees colonized with different gut members display distinct transcriptomic profiles of genes crucial for bee behaviors and division of labor. Alternative splicing of genes related to disordered bee behaviors is also mediated. The presence of gut bacteria promotes sucrose sensitivity with major neurotransmitters being regulated in the brain. Our findings demonstrate how individual bee gut species affect host behaviors, highlighting the gut-brain connections important for honeybee neurobiological and physiological states.

Underlying mechanism of accelerated cell death and multiple disease resistance in a maize lethal leaf spot 1 allele.

Multiple disease resistance (MDR) in maize has attracted increasing attention. However, the interplay between cell death and metabolite changes and their contributions to MDR remains elusive in maize. In this study, we identified a mutant named as lesion mimic 30 (les30) that showed 'suicidal' lesion formation in the absence of disease and had enhanced resistance to the fungal pathogen Curvularia lunata. Using map-based cloning, we identified the causal gene encoding pheophorbide a oxidase (PAO), which is known to be involved in chlorophyll degradation and MDR, and is encoded by LETHAL LEAF SPOT1 (LLS1). LLS1 was found to be induced by both biotic and abiotic stresses. Transcriptomics analysis showed that genes involved in defense responses and secondary metabolite biosynthesis were mildly activated in leaves of the les30 mutant without lesions, whilst they were strongly activated in leaves with lesions. In addition, in les30 leaves with lesions, there was overaccumulation of defense-associated phytohormones including jasmonic acid and salicylic acid, and of phytoalexins including phenylpropanoids, lignin, and flavonoids, suggesting that their biosynthesis was activated in a lesion-dependent manner. Taken together, our study implies the existence of an interactive amplification loop of interrupted chlorophyll degradation, cell death, expression of defense-related genes, and metabolite changes that results in suicidal lesion formation and MDR, and this has the potential to be exploited by genetic manipulation to improve maize disease resistance.

Honey bee genetics shape the strain-level structure of gut microbiota in social transmission.

BACKGROUND: Honey bee gut microbiota transmitted via social interactions are beneficial to the host health. Although the microbial community is relatively stable, individual variations and high strain-level diversity have been detected across honey bees. Although the bee gut microbiota structure is influenced by environmental factors, the heritability of the gut members and the contribution of the host genetics remains elusive. Considering bees within a colony are not readily genetically identical due to the polyandry of the queen, we hypothesize that the microbiota structure can be shaped by host genetics. RESULTS: We used shotgun metagenomics to simultaneously profile the microbiota and host genotypes of bees from hives of four different subspecies. Gut composition is more distant between genetically different bees at both phylotype- and "sequence-discrete population" levels. We then performed a successive passaging experiment within colonies of hybrid bees generated by artificial insemination, which revealed that the microbial composition dramatically shifts across batches of bees during the social transmission. Specifically, different strains from the phylotype of Snodgrassella alvi are preferentially selected by genetically varied hosts, and strains from different hosts show a remarkably biased distribution of single-nucleotide polymorphism in the Type IV pili loci. Genome-wide association analysis identified that the relative abundance of a cluster of Bifidobacterium strains is associated with the host glutamate receptor gene specifically expressed in the bee brain. Finally, mono-colonization of Bifidobacterium with a specific polysaccharide utilization locus impacts the alternative splicing of the gluR-B gene, which is associated with an increased GABA level in the brain. CONCLUSIONS: Our results indicated that host genetics influence the bee gut composition and suggest a gut-brain connection implicated in the gut bacterial strain preference. Honey bees have been used extensively as a model organism for social behaviors, genetics, and the gut microbiome. Further identification of host genetic function as a shaping force of microbial structure will advance our understanding of the host-microbe interactions. Video abstract.

Strain-level analysis reveals the vertical microbial transmission during the life cycle of bumblebee.

BACKGROUND: Microbial acquisition and development of the gut microbiota impact the establishment of a healthy host-microbes symbiosis. Compared with other animals, the eusocial bumblebees and honeybees possess a simple, recurring, and similar set of gut microbiota. However, all bee gut phylotypes have high strain-level diversity. Gut communities of different bee species are composed of host-specific groups of strains. The variable genomic regions among strains of the same species often confer critical functional differences, such as carbon source utilization, essential for the natural selection of specific strains. The annual bumblebee colony founded by solitary queens enables tracking the transmission routes of gut bacteria during development stages. RESULTS: Here, we first showed the changes in the microbiome of individual bumblebees across their holometabolous life cycle. Some core gut bacteria persist throughout different stages of development. Gut microbiota of newly emerged workers always resembles those of their queens, suggesting a vertical transmission of strains from queens to the newborn workers. We then follow the dynamic changes in the gut community by comparing strain-level metagenomic profiles of queen-worker pairs longitudinally collected across different stages of the nest development. Species composition of both queen and worker shifts with the colony's growth, and the queen-to-worker vertical inheritance of specific strains was identified. Finally, comparative metagenome analysis showed clear host-specificity for microbes across different bee hosts. Species from honeybees often possess a higher level of strain variation, and they also exhibited more complex gene repertoires linked to polysaccharide digestion. Our results demonstrate bacterial transmission events in bumblebee, highlighting the role of social interactions in driving the microbiota composition. CONCLUSIONS: By the community-wide metagenomic analysis based on the custom genomic database of bee gut bacteria, we reveal strain transmission events at high resolution and the dynamic changes in community structure along with the colony development. The social annual life cycle of bumblebees is key for the acquisition and development of the gut microbiota. Further studies using the bumblebee model will advance our understanding of the microbiome transmission and the underlying mechanisms, such as strain competition and niche selection. Video Abstract.

Commonly and Specifically Activated Defense Responses in Maize Disease Lesion Mimic Mutants Revealed by Integrated Transcriptomics and Metabolomics Analysis.

Disease lesion mimic (Les/les) mutants display disease-like spontaneous lesions in the absence of pathogen infection, implying the constitutive activation of defense responses. However, the genetic and biochemical bases underlying the activated defense responses in those mutants remain largely unknown. Here, we performed integrated transcriptomics and metabolomics analysis on three typical maize Les mutants Les4, Les10, and Les17 with large, medium, and small lesion size, respectively, thereby dissecting the activated defense responses at the transcriptional and metabolomic level. A total of 1,714, 4,887, and 1,625 differentially expressed genes (DEGs) were identified in Les4, Les10, and Les17, respectively. Among them, 570, 3,299, and 447 specific differentially expressed genes (SGs) were identified, implying a specific function of each LES gene. In addition, 480 common differentially expressed genes (CGs) and 42 common differentially accumulated metabolites (CMs) were identified in all Les mutants, suggesting the robust activation of shared signaling pathways. Intriguingly, substantial analysis of the CGs indicated that genes involved in the programmed cell death, defense responses, and phenylpropanoid and terpenoid biosynthesis were most commonly activated. Genes involved in photosynthetic biosynthesis, however, were generally repressed. Consistently, the dominant CMs identified were phenylpropanoids and flavonoids. In particular, lignin, the phenylpropanoid-based polymer, was significantly increased in all three mutants. These data collectively imply that transcriptional activation of defense-related gene expression; increase of phenylpropanoid, lignin, flavonoid, and terpenoid biosynthesis; and inhibition of photosynthesis are generalnatures associated with the lesion formation and constitutively activated defense responses in those mutants. Further studies on the identified SGs and CGs will shed new light on the function of each LES gene as well as the regulatory network of defense responses in maize.

High-Fat Diets with Differential Fatty Acids Induce Obesity and Perturb Gut Microbiota in Honey Bee.

HFD (high-fat diet) induces obesity and metabolic disorders, which is associated with the alteration in gut microbiota profiles. However, the underlying molecular mechanisms of the processes are poorly understood. In this study, we used the simple model organism honey bee to explore how different amounts and types of dietary fats affect the host metabolism and the gut microbiota. Excess dietary fat, especially palm oil, elicited higher weight gain, lower survival rates, hyperglycemic, and fat accumulation in honey bees. However, microbiota-free honey bees reared on high-fat diets did not significantly change their phenotypes. Different fatty acid compositions in palm and soybean oil altered the lipid profiles of the honey bee body. Remarkably, dietary fats regulated lipid metabolism and immune-related gene expression at the transcriptional level. Gene set enrichment analysis showed that biological processes, including transcription factors, insulin secretion, and Toll and Imd signaling pathways, were significantly different in the gut of bees on different dietary fats. Moreover, a high-fat diet increased the relative abundance of Gilliamella, while the level of Bartonella was significantly decreased in palm oil groups. This study establishes a novel honey bee model of studying the crosstalk between dietary fat, gut microbiota, and host metabolism.

The physiological response of photosynthesis to nitrogen deficiency.

Nitrogen (N), as a macro-element, plays a vital role in plant growth and development. N deficiency affects plant productivity by decreasing photosynthesis, leaf area and longevity of green leaf. To date, many studies have reported that the relationship between photosynthesis and N supply. Here, we summarized the physiological response of photosynthesis to N deficiency in leaf structure and N allocation within the leaf. In serious N stress, photosynthetic rate decreases for almost all plants. The reasons as follows:(1) reducing stomatal conductance of mesophyll cell (gs) and bundle sheath cells (gbs) which influences intercellular CO2 concentration; (2) reducing the content of bioenergetics and light-harvesting protein which inhibits electron transport rate and increase the light energy dissipated as heat; (3) reducing the content and/or activity of photosynthetic enzymes which reduces carboxylation rate. During reproductive stage, N stress induces plant senescence and N components degradation, especially photosynthetic enzymes and thylakoid N, and thus reduces photosynthesis. To keep high grain yield in low N deficiency, we should choose the genotype with higher N allocation within bioenergetics and lower degradation of photosynthetic enzymes. This review provides a generalized N allocation in response to N stress and gives a new prospect for breeding N-efficient genotypes.

Novel compound heterozygous mutation in WEE2 is associated with fertilization failure: case report of an infertile woman and literature review.

BACKGROUND: Fertilization failure after intracytoplasmic sperm injection continues to affect couples and the etiology is not well-understood. CASE PRESENTATION: We characterized a couple with 2-year history of primary unexplained infertility. Three different assisted reproduction attempts (IVF + rescue ICSI, ICSI and ICSI-AOA) showed repeated fertilization failure for MII oocyte retrieval after controlled ovarian hyperstimulation. After whole-exome sequencing and sanger sequencing of the couple and their family members, variant pathogenicity was assessed using SIFT, PolyPhen2, Mutation Taster, and Human Splicing Finder software. We identified novel compound heterozygous mutations, c.1535 + 3A > G and c.946C > T (p. Leu316Phe), in WEE2 in the female proband. Trios analysis of the variations revealed an autosomal recessive pattern. c.1535 + 3A > G in WEE2 was predicted to break the wild-type donor site and affect splicing, and the missense mutation c.946C > T (p. Leu316Phe) of WEE2 was predicted to be pathogenic. CONCLUSION: A novel compound heterozygous mutation in WEE2 was identified in an infertile female who experienced repeated fertilization failure even after ICSI-AOA. These novel mutations in WEE2 provided genetic evidence for fertilization failure.

Evolutionary analyses of NIN-like proteins in plants and their roles in nitrate signaling.

Nitrogen (N) is one of the most important essential macro-elements for plant growth and development, and nitrate represents the most abundant inorganic form of N in soils. The nitrate uptake and assimilation processes are finely tuned according to the available nitrate in the surroundings as well as by the internal finely coordinated signaling pathways. The NIN-like proteins (NLPs) harbor both RWP-RK, and Phox and Bem1 (PB1) domains, and they belong to the well-characterized plant-specific RWP-RK transcription factor gene family. NLPs are known to be involved in the nitrate signaling pathway by activating downstream target genes, and thus they are implicated in the primary nitrate response in the nucleus via their RWP-RK domains. The PB1 domain is a ubiquitous protein-protein interaction domain and it comprises another regulatory layer for NLPs via the protein interactions within NLPs or with other essential components. Recently, Ca2+-Ca2+ sensor protein kinase-NLP signaling cascades have been identified and they allow NLPs to have central roles in mediating the nitrate signaling pathway. NLPs play essential roles in many aspects of plant growth and development via the finely tuned nitrate signaling pathway. Furthermore, recent studies have highlighted the emerging roles played by NLPs in the N starvation response, nodule formation in legumes, N and P interactions, and root cap release in higher plants. In this review, we consider recent advances in the identification, evolution, molecular characteristics, and functions of the NLP gene family in plant growth and development.

[Role of Rictor in Hematopoietic Stem Cells during Fetal Liver Hematopoiesis].

OBJECTIVE: To investigate the effect of Rictor on the hematopoiesis of fetal liver by specific knock-out of Rictor in hematopoietic cells of Vav-Cre mice. METHODS: E12.5 0.08ee fetal liver cells from the experimental group Vav-Cre; Rictorf/f embryos and control group Rictor f/+ or Rictorf/f embryos were transplanted to recipients respectively to observe the effect of Rictor on reconstitution ability of hematopoietic stem cells. In the meantime, E14.5 0, 10, 20, 40, 60, 80 sorted hematopoietic stem cells from the Vav-Cre; Rictorf/f fetal liver of experimental group and Rictorf/+ or Rictorf/f fetal liver of control group were transplanted in to recipients to analyze the numbers of functional hematopoietic stem cells after Rictor was knocked-out. Furthermore, the self-renewal capacity was investigated by secondary transplantation of BM cells from primary recipients that had been successfully repopulated with E12.5 fetal liver-derived cells and by cell cycle analysis. RESULTS: All the recipients receiving E12.5 Rictorf/+ or Rictorf/f cells were repopulated (8/8, from 2 independent experiments) with an average chimerism of 77.2%±11.1% at 4 months post-transplantation, which resulted in 57 LT-RU per FL. In comparison, 8 out of 8 recipients receiving Vav-Cre; Rictorf/f cells were repopulated with significantly reduced chimerism (37.0%±16.3%) (P＜0.01), which was equivalent to 8 LT-RU per FL. The limiting dilution transplantation experiment showed that there was one functional hematopoietic stem cell out of 17 sorted SLAM cells in the control group, and one functional hematopoietic stem cell out of 39 sorted SLAM cells in the experimental group. The secondary transplantation experiments showed that 2 out of 4 recipients were reconstructed in the control group after 1 month, and 0 was reconstructed in the experimental group by transplanting 4×105 donor cells respectively. What＇s more, the percentage of S/G2/M cells in the experimental group increased when compared with controls. CONCLUSION: In the process of fetal liver hematopoiesis, the specifically knocking-out the Rictor in hematopoietic system can lead to defect of reconstitution ability, decrease of the functional hematopoietic stem cell numbers and reduction of self-renewal ability of hematopoietic stem cells.

Dynamic remobilization of leaf nitrogen components in relation to photosynthetic rate during grain filling in maize.

Remobilization of leaf nitrogen (N) contributes greatly to grain N in maize, but leads to low photosynthetic rate (Pn). Pn is determined by various N components involving in light harvest and CO2 reduction. However, it is less clear which N component is the major contributor for the reduction of photosynthesis in modern stay-green maize hybrids. In this study, we analyzed the relationship between remobilization of different N components and Pn during grain filling stage under low N (no N application) and high N (180 kg N ha-1) in a field experiment. The remobilization efficiency of photosynthetic enzymes (PEPc, PPDK and Rubisco) in the leaf was much higher than that of thylakoid N and other N components. Low N supply increased the remobilization efficiency of all the leaf N components. During grain filling stage, the amount of all the N components decreased together with Pn. The ratio of Pn to the N in the PEPc, PPDK and Rubisco kept increase in the whole grain filling stage, while the ratio of Pn to chlorophyll and thylakoid-N decreased. Correlation analysis indicated that Pn was more related to the content of photosynthetic enzymes than to chlorophyll and thylakoid N. It is concluded that photosynthetic enzymes serve as an N storage reservoir at early grain filling stage and their degradation is critical in the reduction of Pn during later grain filling stage. Future breeding targets may be focused on enhancing the efficiency of photosynthetic enzymes during late grain filling stage.

A RNA-Seq Analysis of the Response of Photosynthetic System to Low Nitrogen Supply in Maize Leaf.

Nitrogen is a major limiting factor for crop productivity. The relationship between photosynthesis and nitrogen nutrition has been widely studied. However, the molecular response of leaf photosynthesis to low nitrogen supply in crops is less clear. In this study, RNA sequencing technology (RNA-Seq) was used to investigate the gene expressions related to photosynthesis in maize in response to low nitrogen supply. It was found that low nitrogen supply down-regulated the expression of genes involved in photosystem I (PSI) and photosystem II (PSII). Thus, low nitrogen supply down-regulated the expression of genes related to the antenna system, reduced light absorption, light transport, and electron transport. Correspondingly, the parameters related to chlorophyll fluorescence were very sensitive to nitrogen deficiency. Under low nitrogen supply, leaf chlorophyll content, actual quantum yield of PSII photochemistry, photochemical quenching, and electron transport rate, were reduced. However, the thermal diffusion and chlorophyll fluorescence were increased. RNA-Seq was used to analyze the genes involved in the response of leaf photosynthesis to low nitrogen supply in maize. These results highlight the possibility of utilizing chlorophyll fluorescence parameters, and the related genes, as indicators for plant nitrogen nutrition. This could lead to the development of new tools to make precise nitrogen fertilizer recommendations and select nitrogen-efficient genotypes.

[CatSper in sperm hyperactivation and male infertility: Advances in studies].

The CatSper channel is known as one of the most important Ca²âº channels on the cell membrane of mammalian sperm and plays a key role in the motility, hyperactivation and fertilization function of sperm. The CatSper protein, expressed exclusively in the principal piece of the sperm tail, is composed of CatSper1-4 and 5 auxiliary unitsß,γ,δ and ε, and has an essential part in the functional and structural domains of Ca²âºas well as in the spatiotemporal regulation of the P-Tyr protein, sperm hyperactivation, efficient sperm migration in the oviduct, egg penetration, and normal fertility. Recent studies show that functional deficiency of CatSper seriously affects sperm function,and the loss of any one of its 9 subunits may lead to male reproductive dysfunction. This paper outlines recent advances in the studies of the CatSperprotein, focusing on its expression, location, structure, and regulation,as well as itsinfluence on sperm hyperactivation and male reproduction.

[Role of NF-κB inhibitor in Acute Myeloid Leukemia].

OBJECTIVE: To investigate the role of NF-κB inhibitor in occurence and development of AML. METHODS: AML and normal bone marrow samples were collected from 8 AML patients and 8 normal persons. The expression of NF-κB signaling pathway genes was detected by NF-κB PCR array. Then, AML mouse model was constructed to test the role of NF-κB inhibitor in AML. RESULTS: The NF-κB signal pathway was activated in AML patients. The up-regulated genes, EDARADD, TNFSF14, could activate the NF-κB signal pathway, IL6 could regulate the inflammatory signal. The down-regulated genes, TNFRSF 10B, TNFRSF1A, could lead to cell apoptosis. the AML mouse model was constructed successfully. Then administration of NF-κB inhibitor reduced the inhibition of leukemia niche to the normal hematopoietic stem cells (HSCs), promoted the HSC to enter into cell cycle. CONCLUSION: The NF-κB signal pathway is activated in AML cells. AML mouse model is constructed successfully. NF-κB inhibitor has a potential to treat AML and promotes the HSC to enrter into cell cycle.