Validation of reference genes for quantitative RT-PCR normalization in Suaeda aralocaspica, an annual halophyte with heteromorphism and C4 pathway without Kranz anatomy

Reverse transcription quantitative real-time polymerase chain reaction (qRT-PCR) is a powerful analytical technique for the measurement of gene expression, which depends on the stability of the reference gene used for data normalization. Suaeda aralocaspica, an annual halophyte with heteromorphic seeds and possessing C4 photosynthesis pathway without Kranz anatomy, is an ideal plant species to identify stress tolerance-related genes and compare relative expression at transcriptional level. So far, no molecular information is available for this species. In the present study, six traditionally used reference genes were selected and their expression stability in two types of seeds of S. aralocaspica under different experimental conditions was evaluated. Three analytical programs, geNorm, NormFinder and BestKeeper, were used to assess and rank the stability of reference gene expression. Results revealed that although some reference genes may display different transcriptional profiles between the two types of seeds, β-TUB and GAPDH appeared to be the most suitable references under different developmental stages and tissues. GAPDH was the appropriate reference gene under different germination time points and salt stress conditions, and ACTIN was suitable for various abiotic stress treatments for the two types of seeds. For all the sample pools, β-TUB served as the most stable reference gene, whereas 18S rRNA and 28S rRNA performed poorly and presented as the least stable genes in our study. UBQ seemed to be unsuitable as internal control under different salt treatments. In addition, the expression of a photosynthesis-related gene (PPDK) of C4 pathway and a salt tolerance-related gene (SAT) of S. aralocaspica were used to validate the best performance reference genes. This is the first systematic comparison of reference gene selection for qRT-PCR work in S. aralocaspica and these data will facilitate further studies on gene expression in this species and other euhalophytes.

Edge multi-energy soft x-ray diagnostic in Experimental Advanced Superconducting Tokamak

A multi-energy soft x-ray (ME-SXR) diagnostic has been built for electron temperature profile in the edge plasma region in Experimental Advanced Superconducting Tokamak (EAST) after two rounds of campaigns. Originally, five preamplifiers were mounted inside the EAST vacuum vessel chamber attached to five vertically stacked compact diode arrays. A custom mechanical structure was designed to protect the detectors and electronics under constraints of the tangential field of view for plasma edge and the allocation of space. In the next experiment, the mechanical structure was redesigned with a barrel structure to absolutely isolate it from the vacuum vessel. Multiple shielding structures were mounted at the pinhole head to protect the metal foils from lithium coating. The pre-amplifiers were moved to the outside of the vacuum chamber to avoid introducing interference. Twisted copper cooling tube was embedded into the back-shell near the diode to limit the temperature of the preamplifiers and diode arrays during vacuum vessel baking when the temperature reached 150 °C. Electron temperature profiles were reconstructed from ME-SXR measurements using neural networks.

Cloning of PEPC-1 from a C4 halophyte Suaeda aralocaspica without Kranz anatomy and its recombinant enzymatic activity in responses to abiotic stresses

Phosphoenolpyruvate carboxylase (PEPC) is a key enzyme of C4 photosynthetic pathway and plays an important biochemical role in higher plants and micro organisms. To gain understanding of the role of PEPC in stress adaptation in plant, we cloned PEPC gene from Suaeda aralocaspica, a C4 species without Kranz anatomy, and performed a series of experiments with PEPC gene expressed in Escherichia coli under various abiotic stresses. Results showed that, based on the homology cloning and 5'-RACE technique, the full-length cDNA sequence of PEPC (2901 bp) from S. aralocaspica was obtained, which shares the typical conserved domains to documented PEPCs and was identified as PEPC-1 in accord to the reported partial sequence (ppc-1) in S. aralocaspica. qRT-PCR analysis revealed the expression patterns of PEPC-1 and PEPC-2 (known as ppc-2, another plant type of PEPC) in S. aralocaspica, suggesting that PEPC-1 was up-regulated during seed germination and under NaCl stress, and presented higher level in chlorenchyma than other tissues, which were significantly different with PEPC-2. Afterwards, PEPC-1 was recombinant in E. coli (pET-28a-PEPC) and expressed as an approximate 110 kDa protein. Under various abiotic stresses, the recombinant E. coli strain harboring with PEPC-1 showed significant advantage in growth at 400-800 mmol L(-1) NaCl, 10-20% PEG6000, 25 and 30 °C lower temperature, 50-200 μmol L(-1) methyl viologen, and pH 5.0 and 9.0 condition, compared to control. Further analysis of the enzymatic characteristics of the recombinant PEPC-1 suggests that it was the higher enzyme activity of PEPC-1 which might confer the stress tolerance to E. coli. We speculate that over expression of PEPC-1 is probably related to regulation of oxaloacetate (OAA) in tricarboxylic acid (TCA) cycle in E. coli, which may contribute to further understanding of the physiological function of PEPC in S. aralocaspica.

Characterization of OsPM19L1 encoding an AWPM-19-like family protein that is dramatically induced by osmotic stress in rice

The plant-specific AWPM-19-domain proteins play important roles in plant development and stress responses. In the current study, OsPM19L1 encoding Oryza sativa AWPM-19-like protein 1 was isolated from rice. Tissue-specific gene expression analysis revealed that OsPM19L1 was highly expressed in the leaf sheath of rice. Interestingly, expression of OsPM19L1 was high at the early stage of panicle development and decreased thereafter. qRT-PCR analysis indicated that OsPM19L1 was dramatically induced by 20% PEG stress (>600-fold), exogenous abscisic acid (>350-fold), salt and cold stress. Subcellular localization assay suggested that the OsPM19L1-GFP (green fluorescent protein) fusion protein was localized in the membrane system in rice cells. Moreover, under stress conditions, OsPM19L1 expression was enhanced in an ABI5-Like1 (ABL1) deficiency rice mutant, abl1, suggesting that ABL1 negatively regulates OsPM19L1 gene expression. Thus, OsPM19L1 appears to be closely associated with stress tolerance through ABA-dependent pathway in rice.

Ectopic overexpression of the aldehyde dehydrogenase ALDH21 from Syntrichia caninervis in tobacco confers salt and drought stress tolerance

Aldehyde dehydrogenases are important enzymes that play vital roles in mitigating oxidative/electrophilic stress when plants are exposed to environmental stress. An aldehyde dehydrogenase gene from Syntrichia caninervis, ScALDH21, was introduced into tobacco using Agrobacterium-mediated transformation to generate ScALDH21-overexpressing tobacco plants to investigate its effect on drought and salt resistance. Detached leaves from ScALDH21-overexpressing tobacco plants showed less water loss than those from nontransgenic plants. When subjected to drought and salt stress, transgenic plants displayed higher germination ratios, higher root lengths, greater fresh weight, higher proline accumulation, lower malondialdehyde (MDA) contents and stronger photosynthetic capacities, as well as higher activities of antioxidant enzymes, i.e., superoxide dismutase, catalase and peroxidase, compared with control plants. Therefore, ScALDH21 overexpression in transgenic tobacco plants can enhance drought and salt tolerance and can be used as a candidate gene for the molecular breeding of salt- and drought-tolerant plants.

Differentiation of the seed coat and composition of the mucilage of Lepidium perfoliatum L.: a desert annual with typical myxospermy

Myxospermy is an important feature in seeds of many plant species grown in desert region. Fertilization can initiate differentiation of the seed coat epidermis into a specialized cell type with mucilage production. In the present study, comprehensive analyses were performed on the seed coat differentiation, mucilage production and composition, and seed germination in Lepidium perfoliatum (Brassicaceae), a desert annual with typical myxospermy in China. First, results indicated that mucilage was secreted uniformly at the outer tangential wall, resulting in compression of the cytoplasm to the bottom of the epidermal cells. Secondly, the inner tangential wall and two radial walls of the subepidermal cells were apparently thickened by production of a secondary cell wall material, which resulted in a 'typical' palisade appearance. Thirdly, immunohistochemical staining combined with the enzymatic digestion and infrared spectrum analysis of the mucilage indicated that, while one important component of the seed coat mucilage in L. perfoliatum was pectin, it also contained β-1,3-d-glucan and xyloglucan. Finally, seed germination showed that seeds with mucilage displayed significantly higher germination percentage than that of demucilaged seeds in abundant or excess water conditions. These results suggest that the possible ecological role of mucilage in L. perfoliatum is in the adaptation to habitats with well-watered and water-logged conditions, rather than water stress.

Molecular alterations of the WWOX gene in nasopharyngeal carcinoma

The WW domain-containing oxidoreductase (WWOX) gene is a candidate tumor suppressor gene. However, its exact mechanism is unclear. This study aimed to investigate the role of the WWOX gene in the development of nasopharyngeal carcinoma (NPC). Tissues were collected from 65 NPC patients. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and immunohistochemistry were performed on NPC tissues to determine the expression of WWOX in NPC. The status of WWOX promoter methylation was analyzed by methylation-specific PCR. Moreover, a PCR-based loss of heterozygosity (LOH) assay was conducted to detect the presence of WWOX deletion in NPC. The expression of WWOX in NPC tissues was significantly downregulated compared with that in non-tumorous tissues (P<0.05). The low expression of WWOX was significantly correlated with clinical TNM stage (P<0.05). In addition, methylation of WWOX was detected in 27 (87%) of 31 WWOX protein negative tissues, suggesting that methylation of the WWOX promoter may regulate its expression. We found that a relatively high percentage of LOH was observed in NPC tissues. A significant inverse correlation between WWOX expression and methylation of its promoter was found in NPC tissue (rs=-0.582, P=0.001). However, LOH was not correlated with WWOX expression and methylation of its promoter. Our results show that WWOX gene alteration is an early genetic alteration and may contribute to tumorigenesis of NPC. WWOX may be an important prognostic marker in NPC.

The JAK2/STAT3 and mitochondrial pathways are essential for quercetin nanoliposome-induced C6 glioma cell death

The formulation of quercetin nanoliposomes (QUE-NLs) has been shown to enhance QUE antitumor activity in C6 glioma cells. At high concentrations, QUE-NLs induce necrotic cell death. In this study, we probed the molecular mechanisms of QUE-NL-induced C6 glioma cell death and examined whether QUE-NL-induced programmed cell death involved Bcl-2 family and mitochondrial pathway through STAT3 signal transduction pathway. Downregulation of Bcl-2 and the overexpression of Bax by QUE-NL supported the involvement of Bcl-2 family proteins upstream of C6 glioma cell death. In addition, the activation of JAK2 and STAT3 were altered following exposure to QUE-NLs in C6 glioma cells, suggesting that QUE-NLs downregulated Bcl-2 mRNAs expression and enhanced the expression of mitochondrial mRNAs through STAT3-mediated signaling pathways either via direct or indirect mechanisms. There are several components such as ROS, mitochondrial, and Bcl-2 family shared by the necrotic and apoptotic pathways. Our studies indicate that the signaling cross point of the mitochondrial pathway and the JAK2/STAT3 signaling pathway in C6 glioma cell death is modulated by QUE-NLs. In conclusion, regulation of JAK2/STAT3 and ROS-mediated mitochondrial pathway agonists alone or in combination with treatment by QUE-NLs could be a more effective method of treating chemical-resistant glioma.

Brachial artery waveforms for automatic blood pressure measurement

Theoretically the auscultatory method using Korotkoff sounds is more related to the maximum artery closure status, while the oscillometric method is more related to the overall artery closure status under the cuff. Therefore, the latter is less accurate than the former. This work introduces a new method, which is more accurate than the oscillometric method and suitable for automatic devices. To monitor the maximum artery closure status, a piezoelectric film sensor is attached to the skin just above the brachial artery and under the central section of the cuff where maximum cuff pressure is transferred to the arm. Using the waveform features obtained by this sensor, measurement errors of 0.7±2.5 and 1.27±4.53 mmHg were obtained for the systolic and diastolic pressure, respectively. These reflect small deviations from auscultatory clinical data.

Agonists at GPR119 mediate secretion of GLP-1 from mouse enteroendocrine cells through glucose-independent pathways

BACKGROUND AND PURPOSE

The G protein-coupled receptor 119 (GPR119) mediates insulin secretion from pancreatic β cells and glucagon-like peptide 1 (GLP-1) release from intestinal L cells. While GPR119-mediated insulin secretion is glucose dependent, it is not clear whether or not GPR119-mediated GLP-1 secretion similarly requires glucose. This study was designed to address the glucose-dependence of GPR119-mediated GLP-1 secretion, and to explore the cellular mechanisms of hormone secretion in L cells versus those in β cells.

EXPERIMENTAL APPROACH

GLP-1 secretion in response to GPR119 agonists and ion channel modulators, with and without glucose, was analysed in the intestinal L cell line GLUTag, in primary intestinal cell cultures and in vivo. Insulin secretion from Min6 cells, a pancreatic β cell line, was analysed for comparison.

KEY RESULTS

In GLUTag cells, GPR119 agonists stimulated GLP-1 secretion both in the presence and in the absence of glucose. In primary mouse colon cultures, GPR119 agonists stimulated GLP-1 secretion under glucose-free conditions. Moreover, a GPR119 agonist increased plasma GLP-1 in mice without a glucose load. However, in Min6 cells, GPR119-mediated insulin secretion was glucose-dependent. Among the pharmacological agents tested in this study, nitrendipine, an L-type voltage-dependent calcium channel blocker, dose-dependently reduced GLP-1 secretion from GLUTag cells, but had no effect in Min6 cells in the absence of glucose.

CONCLUSIONS AND IMPLICATIONS

Unlike that in pancreatic β cells, GPR119-mediated GLP-1 secretion from intestinal L cells was glucose-independent in vitro and in vivo, probably because of a higher basal calcium tone in the L cells.

Analysis of gene expression by ESTs from suppression subtractive hybridization library in Chenopodium album L. under salt stress

To identify genes expression in Chenopodium album exposed to NaCl stress and screen ESTs related to salt stress, a subtractive suppression hybridization (SSH) library of C. album under salt stress was constructed in the present study. Random EST sequencing produced 825 high-quality ESTs with GenBank ID GE746311-GE747007, which had 301 bp of average size and were clustered into 88 contigs and 550 singletons. They were classified into 12 categories according to their function annotations. 635 ESTs (76.97%) showed similarities to gene sequences in the non-redundancy database, while 190 ESTs (23.03%) showed low or no similarities. The transcriptional profiles of 56 ESTs randomly selected from 347 unknown or novel ESTs of SSH library under varying NaCl concentration and at different time points were analyzed. The results indicated that a high proportion of tested ESTs were activated by salt stress. Four in 56 ESTs responded to NaCl were also enhanced in expression level when exposed to ABA and PEG stresses. The above four ESTs were validated by northern blotting which was consistent with the results of RT-PCR. The results suggested that genes corresponded to these ESTs might be involved in stress response or regulation. The complete sequences and detailed function of these ESTs need to be further studied.

Variation of seed heteromorphism in Chenopodium album and the effect of salinity stress on the descendants

BACKGROUND AND AIMS

Chenopodium album is well-known as a serious weed and is a salt-tolerant species inhabiting semi-arid and light-saline environments in Xinjiang, China. It produces large amounts of heteromorphic (black and brown) seeds. The primary aims of the present study were to compare the germination characteristics of heteromorphic seeds, the diversity of plant growth and seed proliferation pattern of the resulting plants, and the correlation between NaCl stress and variation of seed heteromorphism.

METHODS

The phenotypic characters of heteromorphic seeds, e.g. seed morphology, seed mass and total seed protein were determined. The effects of dry storage at room temperature on dormancy behaviour, the germination response of seeds to salinity stress, and the effect of salinity on growth and seed proliferation with plants derived from different seed types were investigated.

KEY RESULTS

Black and brown seeds differed in seed morphology, mass, total seed protein, dormancy behaviour and salinity tolerance. Brown seeds were large, non-dormant and more salt tolerant, and could germinate rapidly to a high percentage in a wider range of environments; black seeds were salt-sensitive, and a large proportion of seeds were dormant. These characteristics varied between two populations. There was little difference in growth characteristics and seed output of plants produced from the two seed morphs except when plants were subjected to high salinity stress. Plants that suffered higher salinity stress produced more brown (salt-tolerant) seeds.

CONCLUSIONS

The two seed morphs of C. album exhibited distinct diversity in germination characteristics. There was a significant difference in plant development and seed proliferation pattern from the two types of seeds only when the parent plants were treated with high salinity. In addition, seed heteromorphism of C. album varied between the two populations, and such variation may be attributed, at least in part, to the salinity.

Human telomerase RNA gene (TERC) gain and polysomy of chromosome 3 in cervicovaginal liquid-based pap preparations: a fluorescence in situ hybridization study

PURPOSE. This study investigated human telomerase RNA gene (TERC) gain and polysomy of chromosome 3 in cervicovaginal liquid-based pap preparations in Guilin, China, and assessed the relationship between FISH findings and clinical diagnoses. METHODS. Slides prepared from 63 liquid-based preparations with cytologic diagnoses of negative for squamous intraepithelial lesion or malignancy (NILM n = 9), atypical squamous cells of undetermined significance (ASCUS, n = 18), low-grade squamous intraepithelial lesion (LSIL, n = 14), high-grade squamous intraepithelial lesion (HSIL, n = 9), and cervical squamous cell carcinoma (SCCA, n = 13) were analyzed for TERC gain and polysomy of chromosome 3 using a commercially available two-color FISH probe. The results of the cytologic analysis and those of concurrent or subsequent biopsies, when available, were compared with the FISH findings. The Mann-Whitney test was used to assess associations between FISH findings and diagnoses. RESULTS. TERC gain and polysomy of chromosome 3 were significantly associated with the cytologic diagnosis (p? 0.001). Patients with HSIL or SCCA cytology diagnoses had a significantly higher percentage of cells with TERC gain and polysomy of chromosome 3 than did patients with NILM, ASCUS or LSIL cytologic diagnoses. Those abnormal cases with CIN1 histological diagnosis had a significantly lower percentage of cells with TERC gain and polysomy of chromosome 3 than did patients with a CIN2, CIN3 and SCCA histological diagnosis. CONCLUSIONS. TERC gain and polysomy of chromosome 3 may be important associated genetic events in cervical intraepithelial neoplasia and carcinoma. FISH is a potential tool for the diagnoses of uterine cervix disease.

Polymorphisms in E-cadherin (CDH1) result in a mis-localised cytoplasmic protein that is associated with Crohn's disease

BACKGROUND

Patients with Crohn's disease have defects in intestinal epithelial permeability that are inadequately explained by known inflammatory bowel disease (IBD) susceptibility genes. E-cadherin (CDH1) plays a vital role in maintaining the integrity of the intestinal barrier and its cellular localisation is disrupted in patients with Crohn's disease.

AIM

To determine if polymorphisms in the CDH1 gene are associated with Crohn's disease and to determine the function associated with these polymorphisms.

METHODS

The hypothesis was tested using a candidate gene approach using 20 Tag SNPs derived from the HapMap and Crohn's disease trios. Functional studies were carried out using HapMap cell lines and polarised epithelial cell lines (MDCK-1 and Caco2).

RESULTS

Here we show that CDH1 is associated with Crohn's disease in 327 trios (rs10431923 excess transmission of "TT" genotype; p = 0.0020) and is replicated in the Wellcome Trust Case Control Consortium CD data set (TT risk allele; OR 1.2, p = 0.005). Patients with the Crohn's disease risk haplotype (rs12597188, rs10431923 and rs9935563; GTC allelic frequency 21%; p = 0.000016) exhibited increased E-cadherin cytoplasmic accumulation in their intestinal epithelium which may be explained by the presence of a novel truncated form of E-cadherin. Accordingly, expression of this truncated E-cadherin in cultured polarised epithelial cells resulted in abnormal intracellular accumulation and impaired plasma membrane localisation of both E-cadherin and beta-catenin.

CONCLUSION

The mis-localisation of E-cadherin and beta-catenin may explain the increased permeability seen in some patients with Crohn's disease. Thus, the polymorphisms identified in CDH1 are important for understanding the pathogenesis of Crohn's disease and point to a defect in barrier defence.

Endogenous and synthetic agonists of GPR119 differ in signalling pathways and their effects on insulin secretion in MIN6c4 insulinoma cells

Background and purpose:

GPR119 is a G protein-coupled receptor that is preferentially expressed in islet cells and mediates insulin secretion. Oleoyl-lysophosphatidylcholine and oleoylethanolamide (OEA) act as endogenous ligands for this receptor, whereas PSN375963 and PSN632408 are two recently reported synthetic agonists. In this study, we explored mechanisms underlying GPR119-induced insulin secretion. In addition, we assessed the potential utility of the synthetic agonists as tools for exploring GPR119 biology.

Experimental approach:

We examined natural and synthetic GPR119 agonist activity at GPR119 in MIN6c4 and RINm5f insulinoma cells. We evaluated insulin secretion, intracellular calcium [Ca²⁺]_i, ion channel involvement and levels of cAMP.

Key results:

We report that increases in insulin secretion induced by OEA were associated with increased cAMP and a potentiation of glucose-stimulated increases in [Ca²⁺]_i. We also demonstrate that ATP-sensitive K⁺ and voltage-dependent calcium channels were required for GPR119-mediated increases in glucose-stimulated insulin secretion. In contrast to OEA, the synthetic GPR119 agonist PSN375963 and PSN632408 have divergent effects on insulin secretion, cAMP and intracellular calcium in MIN6c4 cells.

Conclusions and implications:

The endogenous ligand OEA signals through GPR119 in a manner similar to glucagon-like peptide-1 (GLP-1) and its receptor with respect to insulin secretion, [Ca²⁺]_i and cAMP. In addition, PSN375963 and PSN632408 substantially differ from OEA and from one another. These studies suggest that the commercially available synthetic agonists, although they do activate GPR119, may also activate GPR119-independent pathways and are thus unsuitable as GPR119-specific pharmacological tools.

[Characterization of root nodule and rhizobium of a Leguminosae ephemeral plant--Trigonella arcuata C. A. Mey in Xinjiang]

OBJECTIVE

We studied root nodule proliferation, nodule microstructure, genetic cluster and stress resistance of the rhizobium of Trigonella arcuata.

METHODS

We characterized root nodule and rhizobium with various soil matrixes cultivation, paraffin section, resin semi-ultrathin section techniques, and 16S rRNA gene cluster analysis.

RESULTS

(1) Plants grew in mixed soil (nutritious garden soil: poplar zone soil: desert sands = l:1:1), had the most nodule proliferation and bore the most pods. The shapes of nodule were palm- or ginger-like; (2) Microstructure of the nodule revealed five different parts differentiated within the nodule: epidermis (E), cortex (C), vascular bundle (VB), infected cells (IC) and uninfected cells (UIC); (3) Genetic cluster analysis of the full length 16S rRNA gene sequence (1377 bp) indicated that the rhizobium isolated shared the highest identities with Sinorhizobium meliloti; (4) The rhizobium could grow between 4 and 60 degrees C (20 min), pH 6.0-12.0 and 0-2% NaCl. For the antibiotic sensitivity, the rhizobium could not grow normally in medium with 25 microg/mL Kanamycin, Streptomycin or Cephalothin, except for 100 microg/mL Ampicillin.

CONCLUSION

Good conditions of soil matrixes were important for nodulation of T. arcuata; A large quantity of cells in fascicular nodules were infected by rhizobia; 16S rRNA gene sequence of T. arcuata shared the highest identities with that of Sinorhizobium meliloti, and this strain was able to tolerate relatively higher temperature and alkalin.