Aluminum (Al) is one of the most widely applied metals in various industries. Anthropogenic activities of industrial waste result in increased accumulation of Al in natural water resources and aqueous organisms, leading to increased heavy metal pollution in the environment. This will ultimately associate with health risks to all living beings including humans. The present study addresses the possible toxic effects of Al on the motility and regeneration of planarians, using Dugesia japonica as the experimental animal model. Planarians were exposed to varying concentrations of Al (50–1,200 mg/L) for 1 hr, and subsequently evaluated for their motility, seizure-like behaviors, regeneration and alterations of the cell-organelles in their body. Results of the study exhibit that increasing Al concentrations lead to decreased motility and increased seizure-like behaviors, especially the c-type and head bob behaviors in planarians (p<0.05). The regeneration ability in the tail segments was reduced by increased Al concentrations, and the eyespot and optic nerves were more clearly observed in the control groups than planarians exposed to Al. Organelle analysis revealed morphological abnormalities in the mitochondria, golgi apparatus, endoplasmic reticulum, and cilia in the head region of planarians, as compared to the control groups. Taken together, our results indicate that exposure to Al alters the behavior of planarians and delays the regeneration of amputated body parts. Therefore, we suggest that Al exposure adversely can affect the lives of aquatic organisms, and induce toxicity such as cell abnormalities in animals.

Lead (Pb) is a major heavy metal that augments environmental pollution and is a health risk to living organisms. This study was performed to investigate the effect of lead on characteristics of planarian, Dugesia japonica. Briefly, planarians were cultivated in water containing different concentrations (0–400 mg/L) of Pb, and incubated for varying durations (1, 3, and 5 hr). After termination of the incubation time, motility and seizure-like behaviors (c-like, head-bop, snake-like, and screw-like) of the planarians were counted in fresh water. Results showed that increasing Pb concentration and time resulted in decreased motility of the planarians (p<0.05). Increasing concentrations of Pb also resulted in significant increase in the seizure-like behavioral patterns, in particular the c-like and head-bop behaviors. In order to examine eye regeneration, the head region was cut, and rest of the body was incubated in water in the absence or presence of Pb, until emergence of the eye extrusion. Formation of eye spots was initiated in amputated fragments of the control group (without Pb) on day 4 after incubation, whereas appearance of the eye spots was delayed in planarian exposed to 200 mg/L Pb. Moreover, immunohistochemistry revealed that formation of the optic nerve was delayed in planarians exposed to Pb. Thus, our studies determined that planarians exposed to high concentrations of Pb resulted in decreasing motility and induction of seizure-like behaviors, as well as delayed eye regeneration. Results of the current study therefore validate that exposure to lead has a negative effect on the lifespan of aquatic organisms and can cause disturbance of the nervous system in animals, thereby implying the possibility of threatening health.

This study was undertaken to evaluate the toxic effect of cadmium sulfate (Cds) on planarians (Dugesia japonica), and the suitability of planarians as an alternative animal model for toxicity studies. Planarians were exposed to varying concentrations of experimental solutions containing 0.1–25 mg/L Cds, and incubated for 1, 3, and 5 hrs. Motility, seizure-like behaviors (c-like, head-bop, snake-like, and screw-like) and regeneration ability of the amputated fragment were subsequently evaluated. Results showed decreased motility with increasing concentrations of Cds (p<0.05), with the lowest motility being observed at the highest concentration of 25 mg/L Cds. Results also indicate that seizure-like behavior patterns were significantly affected by increments in the Cds concentrations, especially the c-like and head-bop behaviors were notably increased. Compared to the control, the regeneration ability of the planarians was decreased in the experimental solutions containing Cds. Planarians exposed to Cds showed either delayed eye formation or no eye regeneration during incubation. Moreover, increased concentrations of Cds resulted in failure to regenerate and death of the planarians. In conclusion, this study confirm that the heavy metal Cds exerts a toxic effect on planarians. Furthermore, the performances of the planarians in the experimental period exhibit their suitability as an alternative animal model for toxicity studies.

Nicotine is a component of tobacco products and is one of the most commonly abused substances that leads to addiction. Therefore, the present study was performed to investigate the behavioral pattern and toxicity by nicotine exposure in planarians. Basically, planarians were exposed to different concentration of nicotine for 5 min. To investigate detoxification effect, planarians were exposed to nicotine for 5 min, and treated glycyrrhizin for 5 min, then motility and seizure-like behavior were observed for 5 min. As a result, the motility of nicotine-exposed planarians decreased approximately more than 50% compared to freshwater control. However, the motility of glycyrrhizin-exposed planarians recovered than nicotineexposed planarians. In the assessment of seizure-like behavioral pattern, planarians exposed to nicotine showed head-bop or c-like type rather than screw-like or snake-like patterns. However, planarians exposed to glycyrrhizin showed no seizure-like behavior. To examine the oxidative stress response, planarians were cultured in fresh water containing 1 mM nicotine for 1 day. Planarians were homogenized and extracted to assay the contents of reactive oxygen species (ROS), lipid hydroperoxides (LH), glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD). The result showed that a significantly higher level of ROS, LH indicated in planarians exposed to nicotine, on the other hand, glycyrrhizin-exposed planarians were significantly decreased ROS, LH levels. In conclusion, the motility decreased when planarians were exposed to nicotine, in a dose-dependent manner, whereas seizurelike behavior increased. Nicotine induced behavioral disturbances and cell toxicity in planarians were recovered by glycyrrhizin, suggesting a candidate substance for nicotine addiction treatment.

The microstructure and mechanical properties of the hypereutectic prealloyed Al-Si powders prepared by the gas atomization process were described in this paper. With increasing the gas pressure of the atomization, the average powder size was decreased from about . The primary eutectic Si particles were uniformly distributed in the Al matrix and their size varied in the range of . The high densified specimens with above 96% of the theoretical density were fabricated the hot pressing process. The UTS mechanical properties of VN1 specimens were much higher than that of conventional hypoeutectic Al-Si alloys.

Eleutherococcus senticosus (Siberian ginseng) is an important medicinal tree found in northeast Asia. In this study, we analyzed the genome-wide distribution of microsatellites in E. senticosus. By sequencing 711 clones from an SSR-enriched genomic DNA library, we obtained 12 polymorphic SSR markers, which also revealed successful amplicons in E. senticosus accessions. Using the developed SSR markers, we estimated genetic diversity and population structure among 131 E. senticosus accessions in Korea and China. The number of alleles ranged from 2 to 11, with an average of 7.4 alleles. The mean values of observed heterozygosity (HO) and expected heterozygosity (HE) were 0.59 and 0.56, respectively. The average polymorphism information content (PIC) was 0.51 in all 131 E. senticosus accessions. E. senticosus accessions in Korea and China showed a close genetic similarity. Significantly low pairwise genetic divergence was observed between the two regions, suggesting a relatively narrow level of genetic basis among E. senticosus accessions. Our results not only provide molecular tools for genetic studies in E. senticosus but are also helpful for conservation and E. senticosus breeding programs.

In order to breakthrough upcoming challenges for the food production, the efficient use of rice germplasm would be a indispensible. These rice germplasm, adapted from diverse eco-systems, are undiscovered treasures for rice breeders/researchers, potentially providing a broad array of useful alleles that enrich gene pools of current cultivated rice varieties. Although growing ex-situ conservation efforts are an important for preserving diverse rice genetic resources, the activity on finding the novel and favorable genetic variants from the vast genebank collection is greatly challenging, requiring extensive screening processes. Therefore, rice core collection is a powerful solution to accelerate utilizations of the exotic germplasm of the entire population. In addition, The application of whole genome re-sequencing technology would establish a potent platform for fast forward genetic study, such as genome wide association study (GWAS). The GWAS has been implemented to efficiently identify candidate genes related to various useful agricultural traits in many crop species including rice. Given the significant associations between genetic variations and phenotypic diversity does not require prior knowledge, GWAS using high genome coverage of SNP markers provides a genomics platform to dissect previously unknown adaptive or other useful genetic variation accumulated in plant germplasm resources over the times. Once pinpointing candidate genes, GWAS allows informed choice of parents for QTL analysis based on the haplotype information, along with suggesting targets for following mutagenesis and transgenics. Here, we are to report our current achievements and perspectives from GWAS and post-GWAS undertaken to dissect and exploit useful alleles underlying many agricultural traits from Rice core set, including PHS (Pre-Harvest Sprouting), salt tolerance and disease resistance and so forth. Also, we will introduce the integrated Omics based GWAS case study using transcriptomes, proteomes, metabolomes and ionomes of our rice core set.

Genetic resources play a great role in crop breeding because of containing a broad array of useful genes. Currently, the harder are rice breeders trying to develop new rice cultivars with the improved traits, they are more often handicapped by the limited availability of germplasm resources. Thus, a desirable core or heuristic (HS) set of germplasm with maximum genetic diversity can be usefully exploited to breakthrough the present and future challenges of the rice breeding. As such we previously developed the rice HS sets of 166 diverse accessions out of a total 24,368 rice germplasms. Here, we report a large-scale analysis of the patterns of genome-wide genetic variations accumulated in the HS as well as Korean rice over the time. We characterized a total of about 11.8 millions of single nucleotide polymorphisms (SNPs) across the rice genome from resequencing a total of 295 rice genomes including 137 HS and 158 KB rice sets, with an average of approximately 10x depth and > 90% coverage. Using about 460,000 high-quality SNPs (HQSNPs), we specified the population structure, confirming our HS set covers all the rice sub-populations. We further traced the relative nucleotide variabilities of HQSNPs and found the level of the diversity was dynamically changing across the KB genome, which reveals the selection history of KB lines in the past and present. In addition, the results of our genome wide association study (GWAS) suggests that our HS can be also a good reservoir of valuable alleles, pinpointing those alleles underlying the important rice agronomical traits. Overall, the resequencing of our HS set re-illuminates the past, present of the germplasm utilization, which will support the Korean rice breeding in the future.

Sequence-tagged site (STS) markers tightly linked to the bacterial leaf blight (BLB) resistance genes, xa5, xa13 and Xa21, were used in this study. A survey was conducted to find polymorphisms between the resistant and susceptible germplasm in rice. 500 of Korean varieties and 100 of landraces were evaluated in this study. STS marker, RG207 was used to having xa5 resistance gene of rice germplasm. 27 varieties of Korean germplasm showed resistant for xa5 gene. The RG136 an xa-13 marker resulted in a single band of approximately 1kb in all the rice accessions studied. In order to detect polymorphism, digestion of the polymerase chain reaction (PCR) product was performed using a restriction enzyme Hinf Ⅰ. The resistant lines resulted in two bands 0.5kb on digestion with Hinf Ⅰ, while the same enzyme did not digest the PCR product of susceptible lines. No polymorphism was detected in Korean varieties and landraces, indicating that they probably do not contain xa13 gene. pTA248 an Xa-21 marker detected a band of 1kb in the resistant lines and bands of either 750bp or 700bp in the susceptible lines. Among germplasm tested, there are no varieties and landraces with Xa21 resistant gene. The results of the germplasm survey will be useful for the selection of parents in breeding programs aimed at transferring these bacterial blight resistance genes from one varietal background to another.

Genetic background and phylogenetic relationships among 20 Korean wheat cultivars were assessed using microsatellites after amplifying with 13 SSR primer pairs. Average allele number per primer pair was 3.36. Genetic similarities for every pair of cultivars ranged from 0.42 to 0.97, with 0.69 of overall average. Korean cultivars were divided into two major groups based on microsatellite DNA polymorphisms. Group I consisted of relatively old cultivars developed until 1970s, and group II contained the recent cultivars developed during 1980s and 1990s. Amongst old elite cultivars/lines, ‘Yukseung 3’, ‘Norin 12’ and ‘Norin 72’ contributed most to the genetic background of cultivars belonging to group I, and ‘Norin 4’, ‘Norin 12’, ‘Norin 43’ and ‘Norin 72’ to group II, respectively. The phylogenetic relationship of Korean wheat cultivars was in accordance with the genealogical data of each cultivar. The genetic background of each cultivar was assessed from the point of breeding and germplasm management such as variety identification and duplicated accessions for assisting in developing a system for the registration of new variety based on the molecular characterization in future.