Seed viability, germination and seedling growth of canola (Brassica napus L.) as influenced by chemical mutagens

Mutation induction is considered as an effective way to enrich plant genetic variation, particularly for traits with a very low level of genetic variation. The objectives of this study were to evaluate the effect of different dosages of chemical mutagens on seed germination, seed viability and seedling growth characteristics and to identify optimum treatment conditions for chemical mutagens based on the LD50 criterion in canola (Brassica napus L.). Two pretreatment conditions of soaking in distilled water and non-soaking, different concentrations of chemical mutagens, and four treatment periods were investigated. The effect of mutagen dosage on seed viability was also assessed using the tetrazolium staining test. Results revealed the significant effects of mutagen dosages and treatment periods on seed viability and seed germination as well as on seedling characteristics for all the mutagens tested. Additionally, it was found that increased dosage and period in each treatment led to significant reductions in seed viability for the tested mutagens. Pretreatment did not significantly influence most of the studied characteristics. The 0.8% ethyl methanesulfonate (EMS) for 6 h, 12 mM N-nitroso-Nethylurea (ENU) and 6 mM sodium azide for 8 h and 9 mM N-nitroso-N-methylurea (NMU) for 4 h were considered as optimum treatment conditions.Key words: Brassica napus, canola, chemical mutagen, germination, seed viability, seedling growth

Lagrangian wall shear stress structures and near-wall transport in high-Schmidt-number aneurysmal flows

The wall shear stress (WSS) vector field provides a signature for near-wall convective transport, and can be scaled to obtain a first-order approximation of the near-wall fluid velocity. The near-wall flow field governs mass transfer problems in convection-dominated open flows with high Schmidt number, in which case a flux at the wall will lead to a thin concentration boundary layer. Such near-wall transport is of particular interest in cardiovascular flows whereby haemodynamics can initiate and progress biological events at the vessel wall. In this study we consider mass transfer processes in pulsatile blood flow of abdominal aortic aneurysms resulting from complex WSS patterns. Specifically, the Lagrangian surface transport of a species released at the vessel wall was advected in forward and backward time based on the near-wall velocity field. Exposure time and residence time measures were defined to quantify accumulation of trajectories, as well as the time required to escape the near-wall domain. The effect of diffusion and normal velocity was investigated. The trajectories induced by the WSS vector field were observed to form attracting and repelling coherent structures that delineated species distribution inside the boundary layer consistent with exposure and residence time measures. The results indicate that Lagrangian WSS structures can provide a template for near-wall transport.</jats:p

Repetitive Shaft Crack Failure Analysis On A Multistage Centrifugal Pump In Reactor Charge Service In A Nuclear Power Plant - Based On ODS And FEA

LectureTwo multistage barrel type pumps were installed in a nuclear power plant in reactor charge application. The pumps are driven by a 600 HP (447 kW) four-pole induction motor through double helical gear increasers. The overall vibration amplitude of the pump casing and the shaft were determined to be acceptable. However, one of the pumps was found with shaft repetitive cracking failures (MTBF = 7.3 years) initiated away from the key-way stress concentration area, under the later stage impellers, in a zone where fretting was occurring. Several attempts pursued by the plant and their supplier, over the years, did not find the root cause of this shaft cracking problem, in spite of the good troubleshooting procedures and careful installation practices pursued. Therefore, an exceptionally comprehensive root cause investigation was implemented, with specialty vibration testing at its core. Thorough vibration testing combining spectral and timetransient vibration testing on the pump casing and shaft, Experimental Modal Analysis (EMA) testing of the impeller and pump casing, and Operating Deflection Shape (ODS) testing revealed the dynamic behavior of the pump rotor and the entire pump system. The results identified unsuspected excessive axial shuttling of the pump shaft at the motor running speed frequency due to axial run-out of the helical gear set. Based on the test results and supported by non-linear FEA analysis, the authors identified the root cause of the crack initiation phase of the shaft failure. An additional transient FEA based fracture mechanics analysis approach was able to predict that the stresses in the shaft, underneath the impeller, were able to encourage initiation and propagation of the crack. This lecture demonstrates the effectiveness in machinery root cause investigations of thorough vibration testing including ODS, EMA, and FEA rather than traditional troubleshooting approaches, which had not detected a gear/pump inter-related problem, and would not have provided such clear visual evidence for decision makers

Assessment of rice genotypes for salt tolerance using microsatellite markers associated with the saltol QTL

A major quantitative trait locus (QTL) for salt tolerance named Saltol was mapped on chromosome 1 using F8 recombinant inbred lines (RILs) of Pokkali/IR29 cross, which is responsible for low Na+, highK+ uptake and maintaining Na+/K+ homeostasis in the rice shoots. To test the usefulness of microsatellite (SSR) markers associated with Saltol QTL, a collection of 36 diverse rice genotypes wereused. Phenotypic response of the genotypes to salt stress with EC=12 was assessed under controlled environmental conditions at seedling stage using a visual score of 1 to 9 scale. Thirty three polymorphic SSR markers located on chromosome 1 were also used to determine the impact of these markers associated with salt tolerance in rice. The results of phenotypic response of rice genotypes to salinity stress at the seedling stage indicated the varied genotypic responses. The genotypes were classified into five groups from highly tolerant (score 1) to highly sensitive (score 9). Number of alleles of the SSR markers ranged from 3 for RM10702 to 14 for RM8094. Polymorphic information content (PIC) value varied from 0.28 for RM8095 to 0.88 for RM8094 with an average of 0.73. The SSR marker, RM8094, was found to be superior for analysis of genetic diversity in this study. Cluster analysis of the rice genotypes based on SSR data divided the genotypes into three groups each of which having 12, 8 and 16 genotypes including highly salt-tolerant IRRI elite lines (cluster 1), salt tolerant and moderate tolerant genotypes as well as Pokkali and FL478 (cluster 2), sensitive and highly sensitive genotypes (cluster 3), respectively. The impact of chromosome 1 for tolerance to salinity at the seedling stage in rice was emphasized by the results. Thirty six rice genotypes divided into 18 different haplotypes based on Saltol QTL located on chromosome 1 using Pokkali cultivar as the reference. The haplotypespossessing RM8094 and RM10745 markers could discriminate the tolerant genotypes and hence could be useful for marker-assisted selection of Saltol QTL

Genetic analysis of some agronomic traits in flax.

Abstract A complete diallel cross using eight flax genotypes including four Iranian breeding lines and four Canadian genotypes was carried out to estimate genetic parameters for days to flowering, days to maturity, plant height, primary branches per plant, number of capsules per plant, number of seeds per capsule, seed yield per plant, 1000-seed weight, seed yield and harvest index. Analysis of variances for the studied traits indicated highly significant differences among the genotypes. Significant general combining ability (GCA), specific combining ability (SCA) and reciprocal effects revealed meaningful contributions of additive, non-additive type of gene actions and maternal influence in governing the traits. The results showed that additive gene actions had greater effects on inheritance of days to flowering, days to maturity, plant height, primary branches per plant and 1000-seed weight. However, number of capsules per plant and number of seeds per capsule were largely controlled by dominance genetic effects, whereas both additive and non-additive gene actions were important in genetic control of harvest index, seed yield per plant and seed yield. The parental lines KH124, KO37, AH92 and SE65 exhibited positive and significant GCA effect on both seed yield per plant and seed yield. Parent KO37 also had the highest negative GCA for early flowering, early maturity and plant height. A considerable heterosis was also observed for the studied traits in some cross combinations and the highest heterobeltiosis values of 64.1, 35.2, 21.6, 77.2 and 91.3% were obtained for number of capsules per plant, number of seeds per capsule, 1000-seed weight, seed yield per plant and seed yield, respectively. These results imply the potential of producing superior cultivars through selection in segregating populations or heterosis breeding, providing that the technical problems hampering economical production of hybrid seeds in flax could be overcome

A review of genetic epidemiology of head and neck cancer related to polymorphisms in metabolic genes, cell cycle control and alcohol metabolism

The purpose of this report is to review the relationship between genetic polymorphisms involved in carcinogen metabolism, alcohol metabolism and cell-cycle control with the risk of head and neck cancer. The review was performed on available studies on genetic polymorphisms and head and neck cancer (HNC) published in PubMed up to September 2011. 246 primary articles and 7 meta-analyses were published. Among these, a statistically significant association was reported for glutathione S-transferases (GSTM1), glutathione S-transferases (GSTT1) and human microsomal epoxide hydrolase (EPHX1) genes. An increased risk for HNC was also associated reported for P53 codon 72 Pro/Pro, ALDH2 and three variants of the ADH gene: ADH1B (rs1229984), ADH7 (rs1573496) and ADH1C (rs698)

Polymorphisms in metabolic genes, their combination and interaction with tobacco smoke and alcohol consumption and risk of gastric cancer: a case-control study in an Italian population.

BACKGROUND: The distribution and the potential gene-gene and gene-environment interaction of selected metabolic genetic polymorphisms was investigated in relation to gastric cancer risk in an Italian population. METHODS: One hundred and seven cases and 254 hospital controls, matched by age and gender, were genotyped for CYP1A1, CYP2E1, mEH, GSTM1, GSTT1, NAT2 and SULT1A1 polymorphisms. Haplotype analysis was performed for EPHX1 exons 3 and 4, as well as CYP2E1 RsaI (*5 alleles) and CYP2E1 DraI (*5A or *6 alleles). The effect modification by alcohol and cigarette smoking was tested with the heterogeneity test, while the attributable proportion (AP) was used to measure the biological interaction from the gene-gene interaction analysis. RESULTS: Gastric cancer risk was found to be associated with the inheritance of GSTT1 null genotype (OR = 2.10, 95%CI: 1.27-3.44) and the SULT1A1 His/His genotype (OR = 2.46, 95%CI: 1.03-5.90). No differences were observed for the haplotype distributions among cases and controls. For the first time an increased risk was detected among individuals carrying the *6 variant allele of CYP2E1 if ever-drinkers (OR = 3.70; 95%CI: 1.45-9.37) with respect to never-drinkers (OR = 0.18; 95% CI: 0.22-1.46) (p value of heterogeneity among the two estimates = 0.001). Similarly, the effect of SULT1A1 variant genotype resulted restricted to ever-smokers, with an OR of 2.58 (95%CI: 1.27-5.25) for the carriers of His allele among smokers, and an OR of 0.86 (95%CI: 0.45-1.64) among never-smokers (p value of heterogeneity among the two estimates = 0.03). The gene-gene interaction analyses demonstrated that individuals with combined GSTT1 null and NAT2 slow acetylators had an additional increased risk of gastric cancer, with an OR of 3.00 (95%CI: 1.52-5.93) and an AP of 52%. CONCLUSION: GSTT1, SULT1A1 and NAT2 polymorphisms appear to modulate individual's susceptibility to gastric cancer in this Italian population, particularly when more than one unfavourable genotype is present, or when combined with cigarette smoke. The increased risk for the carriers of CYP2E1*5A or *6 alleles among drinkers need to be confirmed by larger prospective studies

A case-control study on proinflammatory genetic polymorphisms on sudden sensorineural hearing loss.

OBJECTIVES/HYPOTHESIS: Sudden sensorineural hearing loss (SSNHL) is strictly related to inner ear vascular injuries and recently to some atherosclerotic risk factors. The pathogenic role of inflammatory molecules in atherosclerosis is well established. However, there is little knowledge about the potential role of inflammatory cytokines and adhesion molecules on SSNHL etiology. STUDY DESIGN: The aim of this study was to evaluate the role of proinflammatory genetic polymorphisms of the MCP-1 (CCL2), E-selectin, and interleukin (IL)-6 gene in SSNHL patients. METHODS: We evaluated the frequency and distribution of selected single nucleotide polymorphisms of the MCP-1 (CCL2), E-selectin, and IL-6 gene in 87 SSNHL patients and 107 healthy controls. RESULTS: Our results did not show significant difference between the compared groups for MCP-1 and E-selectin genes, whereas a significant difference was reported for the IL-6 gene (P &lt; .0001). CONCLUSIONS: The main finding of our study is that the 174G/G polymorphism (with a wider distribution of wt/wt genotype in SSNHL patients than in the healthy controls) of the IL-6 gene is significantly associated with the risk of SSNHL, which is consistent with a previous finding on serum levels of IL-6 in SSNHL. It is possible that the variant acts as a triggering agent of different lipidemia-related phenotypes. Both the -174G/G polymorphism and elevated IL-6 levels in SSNHL patients could suggest that IL-6 plays a role in the inner ear involvement by atherosclerotic inflammatory events