No abstract

N-methyladenosine (mA) is an abundant modification in eukaryotic mRNA, regulating mRNA dynamics by influencing mRNA stability, splicing, export, and translation. However, the precise mA regulating machinery still remains incompletely understood. Here we demonstrate that ZC3H13, a zinc-finger protein, plays an important role in modulating RNA mA methylation in the nucleus. We show that knockdown of Zc3h13 in mouse embryonic stem cell significantly decreases global mA level on mRNA. Upon Zc3h13 knockdown, a great majority of WTAP, Virilizer, and Hakai translocate to the cytoplasm, suggesting that Zc3h13 is required for nuclear localization of the Zc3h13-WTAP-Virilizer-Hakai complex, which is important for RNA mA methylation. Finally, Zc3h13 depletion, as does WTAP, Virilizer, or Hakai, impairs self-renewal and triggers mESC differentiation. Taken together, our findings demonstrate that Zc3h13 plays a critical role in anchoring WTAP, Virilizer, and Hakai in the nucleus to facilitate mA methylation and to regulate mESC self-renewal.

Sea cucumbers are a seafood with high protein and low fat levels. The amino acid contents were similar but fatty acid profiles were different among species. The comparison showed that T. ananas, A. mauritiana and B. argus possessed higher nutritional values than other sea cucumber species.

All life forms on earth require a continuous input and monitoring of carbon and energy supplies. The AMP-activated kinase (AMPK) ⁄ sucrose nonfermenting1 (SNF1) ⁄ Snf1-related kinase1 (SnRK1) protein kinases are evolutionarily conserved metabolic sensors found in all eukaryotic organisms from simple unicellular fungi (yeast SNF1) to animals (AMPK) and plants (SnRK1). Activated by starvation and energy-depleting stress conditions, they enable energy homeostasis and survival by up-regulating energyconserving and energy-producing catabolic processes, and by limiting energy-consuming anabolic metabolism. In addition, they control normal growth and development as well as metabolic homeostasis at the organismal level. As such, the AMPK ⁄ SNF1 ⁄ SnRK1 kinases act in concert with other central signaling components to control carbohydrate uptake and metabolism, fatty acid and lipid biosynthesis and the storage of carbon energy reserves. Moreover, they have a tremendous impact on developmental processes that are triggered by environmental changes such as nutrient depletion or stress. Although intensive research by many groups has partly unveiled the factors that regulate AMPK ⁄ SNF1 ⁄ SnRK1 kinase activity as well as the pathways and substrates they control, several fundamental issues still await to be clarified. In this review, we will highlight these issues and focus on the structure, function and regulation of the AMPK ⁄ SNF1 ⁄ SnRK1 kinases.Abbreviations AAK, AMP-activated kinase in C. elegans; AIS, auto-inhibitory regulatory sequence; AMPK, AMP-activated kinase; ASC, association with 3 SNF1 complex; bZIP, basic leucine zipper domain; CaMKKbeta, Ca 2+ ⁄ calmodulin dependent protein kinase kinase beta; CBS, cystathioninebeta-synthase; CRTC2, cAMP response element-binding (CREB)-regulated transcription co-activator 2; Elm1, elongated morphology 1; GBD, glycogen-binding domain; Glc6P, glucose 6-phosphate; GRIK1 ⁄ 2, geminivirus replication interacting kinase 1 ⁄ 2; HNF4alpha, hepatic nuclear factor 4 alpha; ILS, insulin-like signaling; KIS, kinase interaction sequence; LKB1, liver kinase B1; Mig1, multicopy inhibitor of GAL gene expression; NES, nuclear export sequence; PP1 ⁄ 2A ⁄ 2C, protein phosphatase 1 ⁄ 2A ⁄ 2C; Sak1, Snf1 activating kinase 1; b-SID, b-subunit interaction domain; Sip1 ⁄ 2 ⁄ 4, Snf1 interacting protein 1 ⁄ 2 ⁄ 4; SnAK1 ⁄ 2, SnRK1 activating kinase 1 ⁄ 2; SNF1, sucrose nonfermenting1; SnRK1, Snf1-related kinase1; SRB, suppressor of RNA polymerase B; TAK1, transforming growth factor (TGF) beta activated kinase; Tos3, target of SBF (Swi4-Swi6) 3; TPS, Tre6P synthase; Tre6P, trehalose 6-phosphate.

No abstract

Flowering time adaptation is a major breeding goal in the allopolyploid species Brassica napus. To investigate the genetic architecture of flowering time, a genome-wide association study (GWAS) of flowering time was conducted with a diversity panel comprising 523 B. napus cultivars and inbred lines grown in eight different environments. Genotyping was performed with a Brassica 60K Illumina Infinium SNP array. A total of 41 single-nucleotide polymorphisms (SNPs) distributed on 14 chromosomes were found to be associated with flowering time, and 12 SNPs located in the confidence intervals of quantitative trait loci (QTL) identified in previous researches based on linkage analyses. Twenty-five candidate genes were orthologous to Arabidopsis thaliana flowering genes. To further our understanding of the genetic factors influencing flowering time in different environments, GWAS was performed on two derived traits, environment sensitivity and temperature sensitivity. The most significant SNPs were found near Bn-scaff_16362_1-p380982, just 13 kb away from BnaC09g41990D, which is orthologous to A. thaliana CONSTANS (CO), an important gene in the photoperiod flowering pathway. These results provide new insights into the genetic control of flowering time in B. napus and indicate that GWAS is an effective method by which to reveal natural variations of complex traits in B. napus.

Yellow seed is a desirable quality trait of the Brassica oilseed species. Previously, several seed coat color genes have been mapped in the Brassica species, but the molecular mechanism is still unknown. In the present investigation, map-based cloning method was used to identify a seed coat color gene, located on A9 in B. rapa. Blast analysis with the Arabidopsis genome showed that there were 22 Arabidopsis genes in this region including at4g09820 to at4g10620. Functional complementation test exhibited a phenotype reversion in the Arabidopsis thaliana tt8-1 mutant and yellow-seeded plant. These results suggested that the candidate gene was a homolog of TRANSPARENT TESTA8 (TT8) locus. BrTT8 regulated the accumulation of proanthocyanidins (PAs) in the seed coat. Sequence analysis of two alleles revealed a large insertion of a new class of transposable elements, Helitron in yellow sarson. In addition, no mRNA expression of BrTT8 was detected in the yellow-seeded line. It indicated that the natural transposon might have caused the loss in function of BrTT8. BrTT8 encodes a basic/helix-loop-helix (bHLH) protein that shares a high degree of similarity with other bHLH proteins in the Brassica. Further expression analysis also revealed that BrTT8 was involved in controlling the late biosynthetic genes (LBGs) of the flavonoid pathway. Our present findings provided with further studies could assist in understanding the molecular mechanism involved in seed coat color formation in Brassica species, which is an important oil yielding quality trait.

SUMMARYS45A, a double recessive mutant at both the BnMs1 and BnMs2 loci in Brassica napus, produces no pollen in mature anthers and no seeds by self-fertilization. The BnMs1 and BnMs2 genes, which have redundant functions in the control of male fertility, are positioned on linkage groups N7 and N16, respectively, and are located at the same locus on Arabidopsis chromosome 1 based on collinearity between Arabidopsis and Brassica. Complementation tests indicated that one candidate gene, BnCYP704B1, a member of the cytochrome P450 family, can rescue male sterility. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) of the developing anther showed that pollen-wall formation in the mutant was severely compromised, with a lack of sporopollenin or exine. The phenotype was first evident at the tetrad stage (stage 7) of anther development, coinciding with the maximum BnCYP704B1 mRNA accumulation observed in tapetal cells at stages 7-8 (haploid stage). TEM also suggested that development of the tapetum was seriously defective due to the disturbed lipid metabolism in the S45A mutant. A TUNEL assay indicated that the pattern of programmed cell death in the tapetum of the S45A mutant was defective. Lipid analysis showed that the total fatty acid content was reduced in the S45A mutant, indicating that BnCYP704B1 is involved in lipid metabolism. These data suggest that BnCYP704B1 participates in a vital tapetum-specific metabolic pathway that is not only involved in exine formation but is also required for basic tapetal cell development and function.