Novel insertion mutation of ABCB1 gene in an ivermectin-sensitive Border Collie

한재익,Hyoung-Won Son,Seung-Cheol Park,Ki-Jeong Na 대한수의학회 2010 Journal of Veterinary Science Vol.11 No.4

P-glycoprotein (P-gp) is encoded by the ABCB1 gene and acts as an efflux pump for xenobiotics. In the Border Collie, a nonsense mutation caused by a 4-base pair deletion in the ABCB1 gene is associated with a premature stop to P-gp synthesis. In this study, we examined the fulllength coding sequence of the ABCB1 gene in an ivermectinsensitive Border Collie that lacked the aforementioned deletion mutation. The sequence was compared to the corresponding sequences of a wild-type Beagle and seven ivermectin-tolerant family members of the Border Collie. When compared to the wild-type Beagle sequence, that of the ivermectin-sensitive Border Collie was found to have one insertion mutation and eight single nucleotide polymorphisms (SNPs) in the coding sequence of the ABCB1 gene. While the eight SNPs were also found in the family members' sequences, the insertion mutation was found only in the ivermectin-sensitive dog. These results suggest the possibility that the SNPs are species-specific features of the ABCB1 gene in Border Collies, and that the insertion mutation may be related to ivermectin intolerance.

Clinical Outcomes of EGFR Exon 20 Insertion Mutations in Advanced Non-small Cell Lung Cancer in Korea

변성규,김유진,임성원,조장호,박세훈,이지윤,선종무,최윤라,이세훈,안진석,박근칠,안명주 대한암학회 2019 Cancer Research and Treatment Vol.51 No.2

Purpose Epidermal growth factor receptor (EGFR) exon 20 insertion mutations account for approximately 4% of all EGFRmutations. Given the rarity of this mutation, its clinical outcomes are not fully established. Materials and Methods Between 2009 and 2017, non-small cell lung cancer (NSCLC) patients who showed an exon 20 insertion were retrospectively reviewed for clinical characteristics and outcomes, including responses to chemotherapy (CTx) or targeted therapy. Results Of 3,539 NSCLC patients who harbored an activating EGFR mutation, 56 (1.6%) had an exon 20 insertion. Of the advanced NSCLC patients, 27 of 1,479 (1.8%) had an exon 20 insertion. The median overall survival was 29.4 months (95% confidence interval 9.3 to 49.6) for 27 advanced NSCLC patients. The 22 patients who received systemic CTx achieved a 50.0% response rate and a 77.2% disease control rate, with 4.2 months of progressionfree survival. Six patients received EGFR tyrosine kinase inhibitors (TKIs). Three of the four patients that had only an exon 20 insertion showed progressive disease, while one showed stable disease. The other two patients had an exon 20 insertion and another EGFRmutation and achieved a partial response. Conclusion The incidence of an exon 20 insertion mutation is rare in Korea and occasionally accompanied by other common EGFR mutations. Although the response to systemic CTx. in these patients is comparable to that of patients with other mutations, the response rate to firstor second-generation EGFR TKIs is quite low. Therefore, the development of a more efficient agent is urgently needed.

Genetic differentiation of Mutator insertion polymorphisms and association with agronomic traits in waxy and common maize

Rahul Vasudeo Ramekar,Kyu Jin Sa,Kyong‑Cheul Park,Jong Yeol Park,Ki Jin Park,Ju Kyong Lee 한국유전학회 2020 Genes & Genomics Vol.42 No.6

Background As waxy maize is considered a key economic crop in Korea, an understanding of its genetic variation and differentiation is fundamental for the selective plant breeding. The maize genome is primarily composed of transposable elements, for which large and stable insertions generate variations that reflect selection during evolution. Objectives This study was to elucidate the genetic diversity based on the contribution of TEs and to investigate the effect of Mu transposition on the genetic divergence of waxy and common maize. We also performed an association analysis on these inbred lines to determine the Mu insertions associated with agronomic traits. Methods In this study, we utilized a Mutator-based transposon display method to study the genetic diversity and population structure of 40 waxy and 40 common inbred lines of maize in the Gangwon Agricultural Research and Extension Services collection at the Maize Research Institute. Results We detected polymorphisms in 86.33% of 278 Mutator (Mu) anchored loci, reflecting the activity of the Mu element and its contribution to genetic variation. Common maize showed a substantial amount of genetic diversity, which was greater than that observed in waxy maize. Principal-coordinate and neighbor-joining cluster analyzes consistently supported the presence of two genetically distinct groups. However, the distribution of genetic variation within the populations was much higher than the genetic differentiation among the populations. To explore the contribution of the Mu element to phenotypic variation, we analyzed the associations with ten important agronomical traits. On the basis of the combined results from two models (QGLM and Q + KLM), we found significant associations between seven Mu loci and four different traits. Conclusions These results will assist waxy maize breeders in choosing parental lines and be useful for marker-assisted selection.

Insertional mutations exhibiting high cell-culture density HCD phenotypes are enriched through continuous subcultures in Chlamydomonas reinhardtii

Thung, Leena,He, Jing,Zhu, Qingling,Xu, Zhenyu,Liu, Jianhua,Chow, Yvonne The Korean Society of Phycology 2018 ALGAE Vol.33 No.1

Low efficiency in microalgal biomass production was largely attributed to the low density of algal cell cultures. Though mutations that reduced the level of chlorophyll or pigment content increased efficiency of photon usage and thus the cell-culture density under high-illumination growth conditions (e.g., >$500{\mu}mol\;photon\;m^{-2}\;s^{-1}$), it was unclear whether algae could increase cell-culture density under low-illumination conditions (e.g., ${\sim}50{\mu}mol\;photon\;m^{-2}\;s^{-1}$). To address this question, we performed forward genetic screening in Chlamydomonas reinhardtii. A pool of >1,000 insertional mutants was constructed and subjected to continuous subcultures in shaking flasks under low-illumination conditions. Complexity of restriction fragment length polymorphism (RFLP) pattern in cultures indicated the degree of heterogeneity of mutant populations. We showed that the levels of RFLP complexity decreased when cycles of subculture increased, suggesting that cultures were gradually populated by high cell-culture density (HCD) strains. Analysis of the 3 isolated HCD mutants after 30 cycles of subcultures confirmed that their maximal biomass production was 50-100% higher than that of wild type under low-illumination. Furthermore, levels of chlorophyll content in HCD mutant strains were similar to that of wild type. Inverse polymerase chain reaction analysis identified the locus of insertion in two of three HCD strains. Molecular and transcriptomic analyses suggested that two HCD mutants were a result of the gain-of-function phenotype, both linking to the abnormality of mitochondrial functions. Taken together, our results demonstrate that HCD strains can be obtained through continuous subcultures under low illumination conditions.

Insertional mutations exhibiting high cell-culture density HCD phenotypes are enriched through continuous subcultures in Chlamydomonas reinhardtii

Leena Thung,Jing He,Qingling Zhu,Zhenyu Xu,Jianhua Liu,Yvonne Chow 한국조류학회I 2018 ALGAE Vol.33 No.1

Low efficiency in microalgal biomass production was largely attributed to the low density of algal cell cultures. Though mutations that reduced the level of chlorophyll or pigment content increased efficiency of photon usage and thus the cell-culture density under high-illumination growth conditions (e.g., >500 µmol photon m-2 s-1), it was unclear whether algae could increase cell-culture density under low-illumination conditions (e.g., ~50 µmol photon m-2 s-1). To address this question, we performed forward genetic screening in Chlamydomonas reinhardtii. A pool of >1,000 insertional mutants was constructed and subjected to continuous subcultures in shaking flasks under low-illumination conditions. Complexity of restriction fragment length polymorphism (RFLP) pattern in cultures indicated the degree of heterogeneity of mutant populations. We showed that the levels of RFLP complexity decreased when cycles of subculture increased, suggesting that cultures were gradually populated by high cell-culture density (HCD) strains. Analysis of the 3 isolated HCD mutants after 30 cycles of subcultures confirmed that their maximal biomass production was 50-100% higher than that of wild type under low-illumination. Furthermore, levels of chlorophyll content in HCD mutant strains were similar to that of wild type. Inverse polymerase chain reaction analysis identified the locus of insertion in two of three HCD strains. Molecular and transcriptomic analyses suggested that two HCD mutants were a result of the gain-of-function phenotype, both linking to the abnormality of mitochondrial functions. Taken together, our results demonstrate that HCD strains can be obtained through continuous subcultures under low illumination conditions.