Characterization of Sr9h,a wheat stem rust resistance allele effective to Ug99

Key message

Wheat stem rust resistance gene SrWeb is an allele at the Sr9 locus that confers resistance to Ug99.

Abstract

Race TTKSK (Ug99) of Puccinia graminis f. sp. tritici, the causal fungus of stem rust, threatens global wheat production because of its broad virulence to current wheat cultivars. A recently identified Ug99 resistance gene from cultivar Webster, temporarily designated as SrWeb, mapped near the stem rust resistance gene locus Sr9. We determined that SrWeb is also present in Ug99 resistant cultivar Gabo 56 by comparative mapping and an allelism test. Analysis of resistance in a population segregating for both Sr9e and SrWeb demonstrated that SrWeb is an allele at the Sr9 locus, which subsequently was designated as Sr9h. Webster and Gabo 56 were susceptible to the Ug99-related race TTKSF+ from South Africa. Race TTKSF+ possesses unique virulence to uncharacterized Ug99 resistance in cultivar Matlabas. This result validated that resistance to Ug99 in Webster and Gabo 56 is conferred by the same gene: Sr9h. The emergence of pathogen virulence to several resistance genes that are effective to the original Ug99 race TTKSK, including Sr9h, suggests that resistance genes should be used in combinations in order to increase resistance durability.     

Glutathione peroxidase3 of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> protects phospholipids during cadmium-induced oxidative stress

The present study was undertaken to determine the role of glutathione peroxidase3 (gpx3) in phospholipid protection in cells. Wild-type (WT) cells showed an overall increase in phospholipids upon 50 μM cadmium (Cd)-treatment, whereas an untreated gpx3Δ strain showed a drastic reduction in overall phospholipids which was further reduced with 50 μM Cd. In WT cells, Cd-exposure increased the short chain fatty acids and decreased the unsaturated fatty acids and the magnitude was high in Cd-treated gpx3Δ cells. Purified recombinant gpx3p showed higher activity with phospholipid hydroperoxides than shorter hydroperoxides. An increase in gpx activity was observed in Cd-treated WT cells and no such alteration was observed in gpx3Δ. WT cells treated with Cd showed an increase in MDA over untreated, while untreated gpx3Δ cells themselves showed a higher level of MDA which was further enhanced with Cd-treatment. Iron, zinc and calcium levels were significantly altered in WT and gpx3Δ cells during Cd-treatment.     

Development of transgenic strains for the biological control of the Mexican fruit fly, Anastrepha ludens

The Mexican fruit fly, Anastrepha ludens, is a highly significant agricultural pest species that has been genetically transformed with a piggyBac-based transposon vector system using independent vector and transposase helper plasmids. Minimum estimated germ-line transformation frequencies were approximately 13–21% per fertile G₀ individual, similar to previously reported frequencies using single vector-helper plasmids. Two vector constructs were tested with potential importance to transgenic strain development for mexfly biological control. The first allows post-integration stabilization of a transposon-vector by deletion of a terminal sequence necessary for mobilization. The complete pB[L1-EGFP-L2-DsRed-R1] vector was integrated into the Chiapas wild type strain with subsequent deletion of the L2-DsRed-R1 sub-vector carrying the piggyBac 3′ terminal sequence. Quality control tests for three of the stabilization vector lines (previous to stabilization) assessed viability at all life stages, fertility, adult flight ability, and adult male sexual competitiveness. All three transgenic lines were less fit compared to the wild strain by approximately 5–10% in most tests, however, there was no significant difference in sexual competitiveness which is the major prerequisite for optimal strain release. The second vector, pB[XL-EGFP, Asß2-tub-DsRed.T3], has the DsRed.T3 fluorescent protein reporter gene regulated by the A. suspensa Asß2-tubulin promoter, that resulted in testis and sperm-specific DsRed fluorescence in transgenic male mexflies. Fluorescent sperm bundles were unambiguously observed in the spermathecae of non-transgenic females mated to transgenic males. One transgenic line apparently had a male-specific Y-chromosome insertion, having potential use for sexing by fluorescent-embryo sorting. All transgenic lines expressed easily detectable and stable fluorescence in adults allowing their identification after trapping in the field.     

CENP-A is essential for cardiac progenitor cell proliferation

Centromere protein A (CENP-A) is a homolog of histone H3 that epigenetically marks the heterochromatin of chromosomes. CENP-A is a critical component of the cell cycle machinery that is necessary for proper assembly of the mitotic spindle. However, the role of CENP-A in the heart and cardiac progenitor cells (CPCs) has not been previously studied. This study shows that CENP-A is expressed in CPCs and declines with age. Silencing CENP-A results in a decreased CPC growth rate, reduced cell number in phase G₂/M of the cell cycle, and increased senescence associated β-galactosidase activity. Lineage commitment is not affected by CENP-A silencing, suggesting that cell cycle arrest induced by loss of CENP-A is a consequence of senescence and not differentiation. CENP-A knockdown does not exacerbate cell death in undifferentiated CPCs, but increases apoptosis upon lineage commitment. Taken together, these results indicate that CPCs maintain relatively high levels of CENP-A early in life, which is necessary for sustaining proliferation, inhibiting senescence, and promoting survival following differentiation of CPCs.     

Gastroesophageal Reflux in Relation to Adenocarcinomas of the Esophagus: A Pooled Analysis from the Barrett’s and Esophageal Adenocarcinoma Consortium (BEACON)

Background

Previous studies have evidenced an association between gastroesophageal reflux and esophageal adenocarcinoma (EA). It is unknown to what extent these associations vary by population, age, sex, body mass index, and cigarette smoking, or whether duration and frequency of symptoms interact in predicting risk. The Barrett’s and Esophageal Adenocarcinoma Consortium (BEACON) allowed an in-depth assessment of these issues.

Methods

Detailed information on heartburn and regurgitation symptoms and covariates were available from five BEACON case-control studies of EA and esophagogastric junction adenocarcinoma (EGJA). We conducted single-study multivariable logistic regressions followed by random-effects meta-analysis. Stratified analyses, meta-regressions, and sensitivity analyses were also conducted.

Results

Five studies provided 1,128 EA cases, 1,229 EGJA cases, and 4,057 controls for analysis. All summary estimates indicated positive, significant associations between heartburn/regurgitation symptoms and EA. Increasing heartburn duration was associated with increasing EA risk; odds ratios were 2.80, 3.85, and 6.24 for symptom durations of <10 years, 10 to <20 years, and ≥20 years. Associations with EGJA were slighter weaker, but still statistically significant for those with the highest exposure. Both frequency and duration of heartburn/regurgitation symptoms were independently associated with higher risk. We observed similar strengths of associations when stratified by age, sex, cigarette smoking, and body mass index.

Conclusions

This analysis indicates that the association between heartburn/regurgitation symptoms and EA is strong, increases with increased duration and/or frequency, and is consistent across major risk factors. Weaker associations for EGJA suggest that this cancer site has a dissimilar pathogenesis or represents a mixed population of patients.     

Differential Regulation of Cellular Senescence and Differentiation by Prolyl Isomerase Pin1 in Cardiac Progenitor Cells

Autologous c-kit⁺ cardiac progenitor cells (CPCs) are currently used in the clinic to treat heart disease. CPC-based regeneration may be further augmented by better understanding molecular mechanisms of endogenous cardiac repair and enhancement of pro-survival signaling pathways that antagonize senescence while also increasing differentiation. The prolyl isomerase Pin1 regulates multiple signaling cascades by modulating protein folding and thereby activity and stability of phosphoproteins. In this study, we examine the heretofore unexplored role of Pin1 in CPCs. Pin1 is expressed in CPCs in vitro and in vivo and is associated with increased proliferation. Pin1 is required for cell cycle progression and loss of Pin1 causes cell cycle arrest in the G₁ phase in CPCs, concomitantly associated with decreased expression of Cyclins D and B and increased expression of cell cycle inhibitors p53 and retinoblastoma (Rb). Pin1 deletion increases cellular senescence but not differentiation or cell death of CPCs. Pin1 is required for endogenous CPC response as Pin1 knock-out mice have a reduced number of proliferating CPCs after ischemic challenge. Pin1 overexpression also impairs proliferation and causes G₂/M phase cell cycle arrest with concurrent down-regulation of Cyclin B, p53, and Rb. Additionally, Pin1 overexpression inhibits replicative senescence, increases differentiation, and inhibits cell death of CPCs, indicating that cell cycle arrest caused by Pin1 overexpression is a consequence of differentiation and not senescence or cell death. In conclusion, Pin1 has pleiotropic roles in CPCs and may be a molecular target to promote survival, enhance repair, improve differentiation, and antagonize senescence.     

Mutations in the fumarate hydratase gene cause hereditary leiomyomatosis and renal cell cancer in families in North America

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is an autosomal dominant disorder characterized by smooth-muscle tumors of the skin and uterus and/or renal cancer. Although the identification of germline mutations in the fumarate hydratase (FH) gene in European families supports it as the susceptibility gene for HLRCC, its role in families in North America has not been studied. We screened for germline mutations in FH in 35 families with cutaneous leiomyomas. Sequence analysis revealed mutations in FH in 31 families (89%). Twenty different mutations in FH were identified, of which 18 were novel. Of these 20 mutations, 2 were insertions, 5 were small deletions that caused frameshifts leading to premature truncation of the protein, and 13 were missense mutations. Eleven unrelated families shared a common mutation: R190H. Eighty-one individuals (47 women and 34 men) had cutaneous leiomyomas. Ninety-eight percent (46/47) of women with cutaneous leiomyomas also had uterine leiomyomas. Eighty-nine percent (41/46) of women with cutaneous and uterine leiomyomas had a total hysterectomy, 44% at age < or =30 years. We identified 13 individuals in 5 families with unilateral and solitary renal tumors. Seven individuals from four families had papillary type II renal cell carcinoma, and another individual from one of these families had collecting duct carcinoma of the kidney. The present study shows that mutations in FH are associated with HLRCC in North America. HLRCC is associated with clinically significant uterine fibroids and aggressive renal tumors. The present study also expands the histologic spectrum of renal tumors and FH mutations associated with HLRCC.     

Specific effect of manganese on the allantoinase of Vigna Radiata

Vigna radiata seedlings germinated in the presence of Mn²⁺ show an unusual increase in allantoinase activity which is proportional to Mn²⁺ concentration up to 5 mM. Though Mn²⁺ is not an activator for V. radiata allantoinase, it specifically protects allantoinase against thermal as well as papain-catalysed inactivation. Evidence is presented to show that the primary effect of Mn²⁺ is a protective one, both in vitro and in vivo, and that this is reflected in the observed enhancement of allantoinase activity in Mn²⁺ grown seedlings. That this unusual effect of Mn²⁺ is a specific one is indicated by the lack of a similar effect with Mg²⁺. Cu²⁺ is shown to destabilize V. radiata allantoinase in vitro as well as in vivo.     

Conjugation of Multiple Copies of Polyethylene Glycol to Hemoglobin Facilitated Through Thiolation: Influence on Hemoglobin Structure and Function

PEGylation induced changes in molecular volume and solution properties of HbA have been implicated as potential modulators of its vasoconstrictive activity. However, our recent studies with PEGylated Hbs carrying two PEG chains/Hb, have demonstrated that the modulation of the vasoconstrictive activity of Hb is not a direct correlate of the molecular volume and solution properties of the PEGylated Hb and implicated a role for the surface charge and/or the pattern of surface decoration of Hb with PEG. HbA has now been modified by thiolation mediated maleimide chemistry based PEGylation that does not alter its surface charge and conjugates multiple copies of PEG5K chains. This protocol has been optimized to generate a PEGylated Hb, (SP-PEG5K)₆-Hb, that carries ~six PEG5K chains/Hb – HexaPEGylated Hb. PEGylation increased the O₂ affinity of Hb and desensitized the molecule for the influence of ionic strength, pH, and allosteric effectors, presumably a consequence of the hydrated PEG-shell generated around the protein. The total PEG mass in (SP-PEG5K)₆-Hb, its molecular volume, O₂ affinity and solution properties are similar to that of another PEGylated Hb, (SP-PEG20K)₂-Hb, that carries two PEG20K chains/Hb. However, (SP-PEG5K)₆-Hb exhibited significantly reduced vasoconstriction mediated response than (SP-PEG20K)₂-Hb. These results demonstrate that the enhanced molecular size and solution properties achieved through the conjugation of multiple copies of small PEG chains to Hb is more effective in decreasing its vasoconstrictive activity than that achieved through the conjugation of a comparable PEG mass using a small number of large PEG chains.