Breeding of high lipid producing strain of Geotrichum robustum by ion beam implantation

To obtain an industrial strain with high lipid yield, the wild strain G0 of Geotrichum robustum was mutated by means of nitrogen ions implantation. Mutagenic effects of strain G0 by low energy N+ ion implantation were studied. The experimental results indicated that the survival rate curve took a "saddle" shape, and the positive mutation rate was increased to 22.00% at the dose of nitrogen ions 2.0 x 1015 ions/cm2 when the survival rate was 28.60%. By repeated screening, a high lipid producing strain G9 was obtained. The biomass, lipid content and lipid yield of the mutant can reach 40.25 g/L, 71.14% and 28.63 g/L after cultured in a 5L fermenter for 8 days, increasing by 52.81%, 68.82% and 157.93% to those of wild strain, respectively. Analysis results on fatty acids composition and relative content by gas chromatography and mass spectrometry showed that the lipid in strain G9 was mainly composed of 16-carbon and 18-carbon fatty acids, including 37.360% oleic acid, 23.631% palmitic acid, 4.458% linoleic acid and 26.465% stearic acid. Such compositional features were quite similar to plant oil. Geotrichum robustum strain G9 may be an ideal high lipid producing strain for biodiesel production

Instability of chromosome number and DNA methylation variation induced by hybridization and amphidiploid formation between Raphanus sativus L. and Brassica alboglabra Bailey

<p>Abstract</p> <p>Background</p> <p>Distant hybridization can result genome duplication and allopolyploid formation which may play a significant role in the origin and evolution of many plant species. It is unclear how the two or more divergent genomes coordinate in one nucleus with a single parental cytoplasm within allopolyploids. We used cytological and molecular methods to investigate the genetic and epigenetic instabilities associated with the process of distant hybridization and allopolyploid formation, measuring changes in chromosome number and DNA methylation across multiple generations.</p> <p>Results</p> <p>F₁plants from intergeneric hybridization between <it>Raphanus sativus </it>L. (2n = 18, RR) and <it>Brassica alboglabra </it>Bailey (2n = 18, CC) were obtained by hand crosses and subsequent embryo rescue. Random amplification of polymorphic DNA (RAPD) markers were used to identify the F₁hybrid plants. The RAPD data indicated that the hybrids produced specific bands similar to those of parents and new bands that were not present in either parent. Chromosome number variation of somatic cells from allotetraploids in the F₄to F₁₀generations showed that intensive genetic changes occurred in the early generations of distant hybridization, leading to the formation of mixopolyploids with different chromosome numbers. DNA methylation variation was revealed using MSAP (methylation-sensitive amplification polymorphism), which showed that cytosine methylation patterns changed markedly in the process of hybridization and amphidiploid formation. Differences in cytosine methylation levels demonstrated an epigenetic instability of the allopolyploid of <it>Raphanobrassica </it>between the genetically stable and unstable generations.</p> <p>Conclusions</p> <p>Our results showed that chromosome instability occurred in the early generations of allopolyploidy and then the plants were reverted to largely euploidy in later generations. During this process, DNA methylation changed markedly. These results suggest that, epigenetic mechanisms play an important role in intergeneric distant hybridization, probably by maintaining a genetic balance through the modification of existing genetic materials.</p

Diagnostic value of cell-free DNA to biliary tract cancers: a meta-analysis

Objective·To comprehensively evaluate the diagnostic accuracy of cell-free DNA (cfDNA) to biliary tract cancer (BTC), and provide a basis for better clinical application.Methods·Clinical studies on the diagnostic value of cfDNA to BTC were collected by searching eight databases from inception to April 2023. The studies were selected according to the inclusion and exclusion criteria, and then data was extracted. The threshold effects were assessed with Spearman′s rank correlation analysis, and heterogeneity among the included studies was analyzed by using Cochran′s Q test and I2 test. A bivariate mixed-effects model was fitted, and statistics such as overall sensitivity, specificity, and area under the curve (AUC) were calculated to determine the diagnostic performance. The subgroup analyses were carried out based on the study type, sample size, detection method, sample source, and diagnostic reference standard.Results·A total of 28 diagnosis tests were included, all of which were evaluated as medium-high quality by using Diagnostic Accuracy Studies Tool Version 2 (QUADAS-2). The presence of threshold effects was found by using the Spearman rank correlation analysis. The pooled sensitivity was 0.80 (95%CI 0.67‒0.88), and specificity was 0.96 (95%CI 0.92‒0.98), positive likelihood ratio (PLR) was 22.7 (95%CI 9.4‒55.2), negative likelihood ratio (NLR) was 0.21 (95%CI 0.12‒0.36), and diagnostic odds ratio (DOR) was 108 (95%CI 31‒374), respectively. The AUC of the summary receiver operating characteristic (SROC) curve was 0.96 (95%CI 0.94‒0.98), demonstrating the high accuracy of cfDNA in the diagnosis of BTC. The results of subgroup analyses suggested that the accuracy and sensitivity of choosing different testing methods and sample sources varied.Conclusion·The detection of cfDNA has high sensitivity and specificity in diagnosing BTC, and is suitable for the patients suspected to be malignant after screening with imaging tests and conventional tumor markers. However, the standardization and uniformity of detection methods and sample sources still need to be further standardized by conducting clinical studies on a wider population

Effect of BRCA1 R1325K mutation on proliferation and apoptosis of gallbladder cancer cells

Objective·To investigate the effects of breast cancer susceptibility gene 1 (BRCA1) R1325K mutation [arginine (R) to lysine (K) mutation at amino acid 1325] on the proliferation and apoptosis of gallbladder cancer cell lines GBC-SD and NOZ.Methods·BRCA1 wild-type overexpression lentivirus, BRCA1 R1325K mutation overexpression lentivirus, and negative control lentivirus were used to construct the stable transgenic strains of gallbladder carcinoma, cell lines GBC-SD and NOZ. The cells were divided into the control group without the target gene, the BRCA1 wild-type group, and the BRCA1 R1325K mutation group. The expression of target protein was verified by Western blotting. The BRCA1 R1325K mutant gallbladder cancer cells were treated with 20 μmol/L Olaparib, a BRCA1 mutation inhibitor. Gallbladder cancer cell lines were divided into the control group, the BRCA1 wild-type group, the BRCA1 R1325K mutation group, and the BRCA1 R1325K mutation+Olaparib group according to the target gene expression and whether or not the inhibitor was added. The effect of BRCA1 R1325K mutation on proliferation and clonogenesis ability of gallbladder cancer cell lines GBC-SD and NOZ was observed by CCK8 assay and clonogenesis assay, respectively. The effect of BRCA1 R1325K mutation on apoptosis of gallbladder cancer cell lines GBC-SD and NOZ was observed by TUNEL assay. The expressions of apoptosis-related proteins, cleaved PARP, Bcl-2 and Bax, were detected by Western blotting. The inhibitor Olaparib was used to treat the BRCA1 R1325K mutant gallbladder cancer cell lines GBC-SD and NOZ. The phenotypic changes (promoting proliferation, enhancing clonogenesis and inhibiting apoptosis) induced by BRCA1 R1325K mutation were tested in the presence of Olaparib to determine whether the changes could be reversed by the inhibitor.Results·The results of CCK8 assay and clonogenesis assay showed that BRCA1 R1325K mutation could promote the proliferation of gallbladder cancer cell lines GBC-SD and NOZ, and improve their clonal formation ability, compared with the control group and the BRCA1 wild-type group. Olaparib inhibited the proliferation of gallbladder cancer cell lines overexpressing BRCA1 R1325K mutation (P<0.05). Through TUNEL and Western blotting, it was found that overexpression of wild-type BRCA1 could induce the apoptosis of gallbladder cancer cell lines GBC-SD and NOZ, compared with the control group. Compared with the control group and the BRCA1 wild-type group, the BRCA1 R1325K mutation group had anti-apoptotic effect, in which the expression of apoptosis-inhibiting protein Bcl-2 increased and the expression of pro-apoptotic protein Bax decreased (P<0.05).Conclusion·BRCA1 R1325K mutation can promote the proliferation of GBC-SD and NOZ cell lines and inhibit their apoptosis

Radiological Imaging for Assessing the Respectability of Hilar Cholangiocarcinoma: A Systematic Review and Meta-Analysis

Hilar cholangiocarcinoma (HCC) remains one of the most difficult tumors to stage and treat. The aim of the study was to assess the diagnostic efficiency of computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography/computer tomography (PET/CT) in evaluating the resectability of HCC. A systematic search was performed of the PubMed, EMBASE, and Cochrane databases. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were calculated for individual studies and pooled data as well as test for heterogeneity and public bias. Our data showed that CT had the highest pooled sensitivity at 95% (95% CI: 91-97), whereas PET/CT had the highest pooled specificity at 81% (95% CI: 69-90). The area under the curve (AUC) of CT, MRI, and PET/CT was 0.9269, 0.9194, and 0.9218, respectively. In conclusion, CT is the most frequently used imaging modality to assess HCC resectability with a good sensitivity and specificity. MRI was generally comparable with that of CT and can be used as an alternative imaging technique. PET/CT appears to be the best technique in detecting lymph node and distant metastasis in HCC but has no clear role in helping to evaluate issues of local resectability

Effect of Sialic Acid on Mammalian Cell Culture and Protein Expression: A Potential Productivity Enhancer for Biopharmaceutical Cell Culture Processes

Improved productivity of the two most commonly used cell lines in the biopharmaceutical industry, such as human embryonic kidney 293 (HEK293) and Chinese hamster ovary (CHO), could reduce production costs and increase manufacturing capacity. One method for increasing protein productivity is the addition of antioxidants during the cell culture process. In this study, we examined the effect of sialic acid (SA) on one HEK293 cell line and two CHO cell lines. The addition of SA to HEK293 cell led to a higher viable cell density (VCD), viability (Via), and a lower lactate content in the later stage of cultures. Further results showed that SA reduced the reactive oxygen species (ROS), improved cell viability, reduced lactate production, and increased antibody expression by more than 20% in the later stage of the two CHO cell lines cultures. Besides, an optimized dose of SA had no significant effect on acidic variants level aggregation level, N-linked glycosylation pattern, and SA content on antibodies. These results suggest that the addition of SA can improve the productivity of biopharmaceutical cell culture processes