Purpose The purpose of this study was to carry out a metaanalysis for a comprehensive understanding and estimation of the association between sperm DNA Fragmentation Index (DFI) and pregnancy outcome after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) treatment. Methods Studies concerning the link of DFI with pregnancy outcome were included after literature search of database PUBMED, EMBASE, MEDLINE. Related information was extracted from the eligible studies by two independent authors and a meta-analysis was conducted by using STATA 12.0 software. Pregnancy outcomes consisted of biochemical pregnancy (BP), clinical pregnancy (CP) and pregnancy loss (PL). The studies included for meta-analysis were divided into three groups according to the DFI threshold value (DFI >27 %, 15-27 %, ≤15 % group). The odds ratio (OR ) and their 95 % confidence intervals (95 % CIs) were used to evaluate the association between DFI and pregnancy outcome. Results Twenty articles were included in our meta-analysis. The results indicated that infertile couples were more likely to get pregnant if DFI was less than threshold value (For threshold value > 27 % and 15-27 % group, combined overall OR (95 % CI) = 1.437 (1.186-1.742), 1.639 (1.093-2.459) respectively). However, when stratified by DFI detection methods, using sperm chromatin structure assay (SCSA) as the DFI test method, the results indicated a similar CP rate between groups with a high DFI or a lower DFI value (SCSA, For threshold value >27 % and 15-27 % group, combined overall OR (95 % CI) = 1.242(0.978-1.577), 1.480(0.921-2.377) respectively). The meta-analysis based on BP (overall OR (95 % CI) = 0.952 (0.697-1.302)) and PL((For DFI >27 %, 15-27 %, ≤15 % group, OR (95 % CI) = 0.786 (0.491-1.258), 1.509 (0.655-3.476), (0.538 (0.264-1.097) respectively) outcome yielded nonsignificant results. Conclusions The predication value of DFI for IVF or ICSI outcome is not confirmed in our meta-analysis. Further better designed studies with larger subjects involved are needed to better address this issue.
Dirigent super-family abounds throughout the plant kingdom, especially vascular plants. To elucidate the function of cotton (Gossypium hirsutum) DIR genes in lignification, two cDNAs (designated GhDIR1 and GhDIR2) encoding putative dirigent proteins were isolated from cotton cDNA libraries. Real-time quantitative reverse transcription-polymerase chain reaction analysis revealed that GhDIR1 transcript was preferentially accumulated in cotton hypocotyls, whereas GhDIR2 was predominantly expressed in cotton fibers. Overexpression of GhDIR1 gene resulted in an increase in lignin content in transgenic cotton plants, compared with that of wild type. Histochemical assay revealed that the transgenic plants displayed more widespread lignification than that of wild type in epidermis and vascular bundle. Furthermore, the transgenic cotton plants displayed more tolerance to the infection of Verticillium dahliae. Our data suggest that GhDIR1 may be involved in cotton lignification which can block the spread of fungal pathogen V. dahliae.
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