hnRNP I Inhibits Notch Signaling and Regulates Intestinal Epithelial Homeostasis in the Zebrafish

Regulated intestinal stem cell proliferation and differentiation are required for normal intestinal homeostasis and repair after injury. The Notch signaling pathway plays fundamental roles in the intestinal epithelium. Despite the fact that Notch signaling maintains intestinal stem cells in a proliferative state and promotes absorptive cell differentiation in most species, it remains largely unclear how Notch signaling itself is precisely controlled during intestinal homeostasis. We characterized the intestinal phenotypes of brom bones, a zebrafish mutant carrying a nonsense mutation in hnRNP I. We found that the brom bones mutant displays a number of intestinal defects, including compromised secretory goblet cell differentiation, hyperproliferation, and enhanced apoptosis. These phenotypes are accompanied by a markedly elevated Notch signaling activity in the intestinal epithelium. When overexpressed, hnRNP I destabilizes the Notch intracellular domain (NICD) and inhibits Notch signaling. This activity of hnRNP I is conserved from zebrafish to human. In addition, our biochemistry experiments demonstrate that the effect of hnRNP I on NICD turnover requires the C-terminal portion of the RAM domain of NICD. Our results demonstrate that hnRNP I is an evolutionarily conserved Notch inhibitor and plays an essential role in intestinal homeostasis

Simulating summer circulation and water exchange in the Beibu Gulf

346-354A cyclonic gyre and a semi-closed anti-cyclonic gyre exist respectively in the north and south of Beibu Gulf. Water exchange is calculated using tracer-tracking model in FVCOM via adding an imaginary conservative material as the tracer material. After circularly using the wind condition of August 2012 for 800days, we get spatial and temporal distribution of the tracer concentration of Beibu Gulf of summer in 2012. Forced by circulation, Qiongzhou Strait, Da Nang sea area and Sanya sea area are main mass transport galleries of Beibu Gulf. The half exchange period of the Beibu Gulf in summer is 518 days while the value of average residence time is 588 days. Considering that summer lasts for 3 months, water exchange rate of the whole gulf is 13.73%

Cloning and Functional Analysis of MADS-box Genes, TaAG-A and TaAG-B, from a Wheat K-type Cytoplasmic Male Sterile Line

Wheat (Triticum aestivum L.) is a major crop worldwide. The utilization of heterosis is a promising approach to improve the yield and quality of wheat. Although there have been many studies on wheat cytoplasmic male sterility, its mechanism remains unclear. In this study, we identified two MADS-box genes from a wheat K-type cytoplasmic male sterile (CMS) line using homology-based cloning. These genes were localized on wheat chromosomes 3A and 3B and named TaAG-A and TaAG-B, respectively. Analysis of TaAG-A and TaAG-B expression patterns in leaves, spikes, roots, and stems of Chinese Spring wheat determined using quantitative RT-PCR revealed different expression levels in different tissues. TaAG-A had relatively high expression levels in leaves and spikes, but low levels in roots, while TaAG-B had relatively high expression levels in spikes and lower expression in roots, stems, and leaves. Both genes showed downregulation during the mononucleate to trinucleate stages of pollen development in the maintainer line. In contrast, upregulation of TaAG-B was observed in the CMS line. The transcript levels of the two genes were clearly higher in the CMS line compared to the maintainer line at the trinucleate stage. Overexpression of TaAG-A and TaAG-B in Arabidopsis resulted in phenotypes with earlier reproductive development, premature mortality, and abnormal buds, stamens, and stigmas. Overexpression of TaAG-A and TaAG-B gives rise to mutants with many deformities. Silencing TaAG-A and TaAG-B in a fertile wheat line using the virus-induced gene silencing (VIGS) method resulted in plants with green and yellow striped leaves, emaciated spikes, and decreased selfing seed set rates. These results demonstrate that TaAG-A and TaAG-B may play a role in male sterility in the wheat CMS line

Assessing the Performance of GPS Precise Point Positioning Under Different Geomagnetic Storm Conditions during Solar Cycle 24

The geomagnetic storm, which is an abnormal space weather phenomenon, can sometimes severely affect GPS signal propagation, thereby impacting the performance of GPS precise point positioning (PPP). However, the investigation of GPS PPP accuracy over the global scale under different geomagnetic storm conditions is very limited. This paper for the first time presents the performance of GPS dual-frequency (DF) and single-frequency (SF) PPP under moderate, intense, and super storms conditions during solar cycle 24 using a large data set collected from about 500 international GNSS services (IGS) stations. The global root mean square (RMS) maps of GPS PPP results show that stations with degraded performance are mainly distributed at high-latitude, and the degradation level generally depends on the storm intensity. The three-dimensional (3D) RMS of GPS DF PPP for high-latitude during moderate, intense, and super storms are 0.393 m, 0.680 m and 1.051 m, respectively, with respect to only 0.163 m on quiet day. RMS errors of mid- and low-latitudes show less dependence on the storm intensities, with values less than 0.320 m, compared to 0.153 m on quiet day. Compared with DF PPP, the performance of GPS SF PPP is inferior regardless of quiet or disturbed conditions. The degraded performance of GPS positioning during geomagnetic storms is attributed to the increased ionospheric disturbances, which have been confirmed by our global rate of TEC index (ROTI) maps. Ionospheric disturbances not only lead to the deteriorated ionospheric correction but also to the frequent cycle-slip occurrence. Statistical results show that, compared with that on quiet day, the increased cycle-slip occurrence are 13.04%, 56.52%, and 69.57% under moderate, intense, and super storms conditions, respectively

The Carotenoid Cleavage Dioxygenase Gene <em>CCD7-B</em>, at Large, Is Associated with Tillering in Common Wheat

Wheat, an important cereal crop, is responsible for the livelihoods of many people, and a component of national food security. Tillering, which determines plant architecture and spike number, is a critical agronomic trait of wheat. The carotenoid cleavage dioxygenase 7 (CCD7) has an important effect on the growth of tillers or lateral branches and lateral roots of plants. In order to study the relationship between CCD7 and tillering in wheat, CCD7-B was isolated from 10 Chinese wheat varieties with different tiller numbers. Subsequently, bioinformatics, allelic variation analysis, and field experiments were performed. Wheat CCD7-B belongs to the retinal pigment epithelial membrane receptor (RPE65) superfamily; it displays the greatest homology with monocot CCD7 proteins. Phylogenetic analysis of wheat CCD7-B proteins indicated division into dicotyledonous and monocotyledonous clades. Allelic variation analysis of CCD7-B via SrgAI enzyme digestion (a marker of cleaved amplified polymorphic sequences) suggested that 262 Chinese wheat micro-core collections and 121 Chinese wheat major cultivars from the Yellow and Huai River Valley winter wheat region can be divided into two groups: CCD7-B1 (C/T/T) and CCD7-B2 (G/C/A). CCD7-B1 showed better allelic variation than did CCD7-B2 for increasing the number of effective tillers of wheat varieties in China. This study provides reference data for the application of CCD7-B alleles to wheat breeding and supports further research regarding the mechanism of tillering in common wheat

The 160 bp Insertion in the Promoter of Rht-B1i Plays a Vital Role in Increasing Wheat Height

The extensive use of two alleles (Rht-B1b and Rht-D1b) at the Rht-1 locus in wheat allowed dramatic increases in yields, triggering the so-called Green Revolution. Here, we found that a new natural allelic variation (Rht-B1i) containing a single missense SNP (A614G) in the coding region significantly increased plant height against the genetic background of both Rht-D1a (11.68%) and Rht-D1b (7.89%). To elucidate the molecular mechanism of Rht-B1i, we investigated the promoter region. Sequence analysis showed that the Rht-B1i promoter could be divided into two classes depending on the presence or absence of a specific 160 bp insertion: Rht-B1i-1 (with the 160 bp insertion) and Rht-B1i-2 (without the 160 bp insertion). The promoter of Rht-B1i-1 contained 32 more possible cis-acting elements than Rht-B1a, including a unique auxin response element AUXREPSIAA4. Quantitative RT-PCR analysis indicated that the 160 bp insertion is likely to promote the transcription of the Rht-B1i-1 gene. The coleoptile lengths of wheat varieties treated with IAA, GA3, and IAA/GA3, combined with the histochemical staining of transgenic Arabidopsis containing the Rht-B1i-1 promoter, showed that the height-increasing effect of Rht-B1i-1 may be due to the synergistic action of IAA and GA3. These results augment our understanding of the regulatory mechanisms of Rht-1 in wheat and provide new genetic resources for wheat improvement

Interaction among TaGID1, TaGID2, and RHT-1 in yeast cells.

<p>SLN1 and RHT-1s were used as preys, pBr-TaGID1A-TaGID2A was used as baits, and the AD and pBr constructs were co-transformed into the yeast strain HF7c, the transformants were grown on the SD/-Met-Leu-Trp media (control) and the SD/-Met-Leu-Trp-His media containing 20 mM 3-AT with or without 100 μM GA₃, all experiments were conducted three times, and five clones were used each time.</p

Molecular Characterization of Three <i>GIBBERELLIN-INSENSITIVE DWARF2</i> Homologous Genes in Common Wheat

<div><p>F-box protein is a core component of the ubiquitin E3 ligase SCF complex and is involved in the gibberellin (GA) signaling pathway. To elucidate the molecular mechanism of GA signaling in wheat, three homologous <i>GIBBERELLIN-INSENSITIVE DWARF2</i> genes, <i>TaGID2</i>s, were isolated from the Chinese Spring wheat variety. A subcellular localization assay in onion epidermal cells and <i>Arabidopsis</i> mesophyll protoplasts showed that <i>TaGID2</i>s are localized in the nuclei. The expression profiles using quantitative real-time polymerase chain reaction showed that <i>TaGID2</i>s were downregulated by GA₃. The interaction between TaGID2s and TSK1 (homologous to ASK1) in yeast indicated that TaGID2s might function as a component of an E3 ubiquitin-ligase SCF complex. Yeast two-hybrid assays showed that a GA-independent interaction occurred between three TaGID2s and RHT-A1a, RHT-B1a, and RHT-D1a. Furthermore, TaGID2s interact with most RHT-1s, such as RHT-B1h, RHT-B1i, RHT-D1e, RHT-D1f, etc., but cannot interact with RHT-B1b or RHT-B1e, which have a stop codon in the DELLA motif, resulting in a lack of a GRAS domain. In addition, RHT-B1k has a frame-shift mutation in the VHIID motif leading to loss of the LHRII motif in the GRAS domain and RHT-D1h has a missense mutation in the LHRII motif. These results indicate that TaGID2s, novel positive regulators of the GA response, recognize RHT-1s in the LHRII motif resulting in poly-ubiquitination and degradation of the DELLA protein.</p></div

Interactions among TaGID2 and TSK1 proteins in yeast cells.

<p>(A) Amino acid sequence alignment of TSK1 from Chinese Spring with AY316293 from Jingdong 1. (B) Yeast two hybrid assay between TaGID2 and TSK1, TSK1 was used as prey, and TaGID2-A1, TaGID2-B1, and TaGID2-D1 were used as baits, the AD and BK constructs were co-transformed into the yeast strain AH109, the transformants were grown on the SD/-Leu-Trp media (control) and the SD/-Leu-Trp-His-Ade media with or without 100 μM GA₃, all experiments were conducted three times, and five clones were used each time.</p