• 음성과학
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• 제11권2호
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• pp.71-87
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• 2004

Korean has a pair of voiceless fricatives, whose laryngeal manifestation comes in parallel to stops and affricates with a three-way lexical contrast. Prior phonetic studies by Kagaya (1974), Iverson (1983), and Kang (1999, 2000) point out /s/ is associated with multiple characteristics of the larynx shared with not only the lax but also the aspirated series, whereas /s' / carries a laryngeal distinction typical of the tense consonants. The complex dual nature of /s/ is again supported by a psycholinguistic study by Kang (2004), as /s/ was found to interact with /$c^h$/ (17% of the time) as well as /c/ (57%) in speech errors. In addition, a recent work by Cho and Lee (2003) notes an interesting chain shift case in the acquisition of the fricatives. Although they observed a significant phonological pattern between child English and Korean, Cho and Lee's description of acquiring fricatives is far from being precise from the perspective of phonetics. From a longitudinal study of recorded tapes by two children at 1;7-3;8 and 1;7-2;1 respectively, I found that /s' / was usually substituted into tense noncontinuants in young children's early production as predicted, whereas /s/ having both lax and aspirated-like glottal properties revealed a complicated pattern of substitutions into lax, tense, and aspirated noncontinuants with a varying degree of preference relative to the subjects. The current acquisition study supports the previous claims concerning fricatives in other languages, showing that their acquisition comes after stops. Besides, it also notes that Korean fricatives are subject to a series of phonological processes called stopping, affricating, tensifying and palatalizing during the transitional period of phonological development by young children. Moreover, between the two voiceless types, /s/ was acquired earlier than /s'/ as the unmarked segment.

• Journal of Microbiology and Biotechnology
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• 제27권11호
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• pp.1999-2009
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• 2017

The secretion efficiency of a protein in a Sec-type secretion system is mainly determined by an N-terminal signal peptide and its combination with its cognate protein. Five signal peptides, namely, two synthetic Sec-type and three Bacillus licheniformis alpha-amylase-derived signal peptides, were compared for periplasmic expression of the human growth hormone (hGH) in E. coli. Based on in silico predictions on the signal peptides' cleavage efficiencies and their corresponding mRNA secondary structures, a number of amino acid substitutions and silent mutations were considered in the modified signal sequences. The two synthetic signal peptides, specifically designed for hGH secretion in E. coli, differ in their N-terminal positively charged residues and hydrophobic region lengths. According to the mRNA secondary structure predictions, combinations of the protein and each of the five signal sequences could lead to different outcomes, especially when accessibility of the initiator ATG and ribosome binding sites were considered. In the experimental stage, the two synthetic signal peptides displayed complete processing and resulted in efficient secretion of the mature hGH in periplasmic regions, as was demonstrated by protein analysis. The three alpha-amylase-derived signal peptides, however, were processed partially from their precursors. Therefore, to achieve efficient secretion of a protein in a heterologous system, designing a specific signal peptide by using a combined approach of optimizations of the mRNA secondary structure and the signal peptide H-domain and cleavage site is recommended.

• Clinical and Experimental Pediatrics
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• 제57권9호
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• pp.410-415
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• 2014

Purpose: Neurofibromatosis 1 (NF1) is an autosomal dominant condition caused by an NF1 gene mutation. NF1 is also a multisystem disorder that primarily affects the skin and nervous system. The goal of this study was to delineate the phenotypic characterization and assess the NF1 mutational spectrum in patients with NF1. Methods: A total of 42 patients, 14 females and 28 males, were enrolled in this study. Clinical manifestations and results of the genetic study were retrospectively reviewed. Results: Age of the patients at the time of NF1 diagnosis was $15.8{\pm}14.6$ years (range, 1-62 years). Twelve patients (28.6%) had a family history of NF1. Among the 42 patients, $Caf\acute{e}$-au-lait spots were shown in 42 (100%), neurofibroma in 31 (73.8%), freckling in 22 (52.4%), and Lisch nodules in seven (16.7%). The most common abnormal finding in the brain was hamartoma (20%). Mental retardation was observed in five patients (11.9%), seizures in one patient (2.4%), and plexiform neurofibromas (PNFs) in four patients (9.5%). One patient with PNFs died due to a malignant peripheral nerve sheath tumor in the chest cavity. Genetic analysis of seven patients identified six single base substitutions (three missense and three nonsense) and one small deletion. Among these mutations, five (71.4%) were novel (two missense mutations: p.Leu1773Pro, p.His1170Leu; two nonsense mutations: $p.Arg2517^*$, $p.Cys2371^*$; one small deletion: $p.Leu1944Phefs^*6$). Conclusion: The clinical characteristics of 42 Korean patients with NF1 were extremely variable and the mutations of the NF1 gene were genetically heterogeneous with a high mutation-detection rate.

• Clinical and Experimental Pediatrics
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• 제60권6호
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• pp.167-174
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• 2017

Mycoplasma pneumoniae pneumonia (MPP) is one of the most common forms of community-acquired pneumonia in children and adolescents. Outbreaks of MPP occur in 3- to 7-year cycles worldwide; recent epidemics in Korea occurred in 2006-2007, 2011, and 2015-2016. Although MPP is known to be a mild, self-limiting disease with a good response to macrolides, it can also progress into a severe and fulminant disease. Notably, since 2000, the prevalence of macrolide-resistant MPP has rapidly increased, especially in Asian countries, recently reaching up to 80%-90%. Macrolide-resistant Mycoplasma pneumoniae (MRMP) harbors a point mutation in domain V of 23S rRNA with substitutions mainly detected at positions 2063 and 2064 of the sequence. The excessive use of macrolides may contribute to these mutations. MRMP can lead to clinically refractory pneumonia, showing no clinical or radiological response to macrolides, and can progress to severe and complicated pneumonia. Refractory MPP is characterized by an excessive immune response against the pathogen as well as direct injury caused by an increasing bacterial load. A change of antibiotics is recommended to reduce the bacterial load. Tetracyclines or quinolones can be alternatives for treating MRMP. Otherwise, corticosteroid or intravenous immunoglobulin can be added to the treatment regimen as immunomodulators to downregulate an excessive host immune reaction and alleviate immune-mediated pulmonary injury. However, the exact starting time point, dose, or duration of immunomodulators has not been established. This review focuses on the mechanism of resistance acquisition and treatment options for MRMP pneumonia.

• Parasites, Hosts and Diseases
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• 제43권1호
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• pp.27-32
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• 2005

Toxoplasma gondii tachyzoites were isolated from an ocular patient in the Republic of Korea and maintained in the laboratory (designated KI-1). In the present study, its genotype was determined by analyzing dense granule antigen 6 (GRA6) gene and surface antigen 2 (SAG2) gene as typing markers. Digestion of the amplification products of GRA6 and of the 5' and 3' ends of SAG2, respectively, with Mse I, Sau3A I, and Hha I, revealed that KI-1 is included in the genotype I, which includes the worldwide virulent RH strain. In addition, when the whole sequences of the coding regions of SAG1, rhoptry antigen 1 (ROP1), and GRA8 genes of KI-1 were compared with those of RH, minor nucleotide polymorphisms and amino acid substitutions were identified. These results show that KI-1 is a new geographical strain of T. gondii that can be included in the genotype I.

• Parasites, Hosts and Diseases
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• 제53권3호
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• pp.341-344
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• 2015

Toxoplasma gondii is an opportunistic protozoan parasite that can infect almost all warm-blooded animals including humans with a worldwide distribution. Micronemes play an important role in invasion process of T. gondii, associated with the attachment, motility, and host cell recognition. In this research, sequence diversity in microneme protein 6 (MIC6) gene among 16 T. gondii isolates from different hosts and geographical regions and 1 reference strain was examined. The results showed that the sequence of all the examined T. gondii strains was 1,050 bp in length, and their A + T content was between 45.7% and 46.1%. Sequence analysis presented 33 nucleotide mutation positions (0-1.1%), resulting in 23 amino acid substitutions (0-2.3%) aligned with T. gondii RH strain. Moreover, T. gondii strains representing the 3 classical genotypes (Type I, II, and III) were separated into different clusters based on the locus of MIC6 using phylogenetic analyses by Bayesian inference (BI), maximum parsimony (MP), and maximum likelihood (ML), but T. gondii strains belonging to ToxoDB #9 were separated into different clusters. Our results suggested that MIC6 gene is not a suitable marker for T. gondii population genetic studies.

• The Plant Pathology Journal
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• 제30권2호
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• pp.195-199
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• 2014

Apple stem pitting virus (ASPV), of the Foveavirus genus in the family Betaflexiviridae, is one of the most common viruses of apple and pear trees. To examine variability of the coat protein (CP) gene from ASPV, eight isolates originating from 251 apple trees, which were collected from 22 apple orchards located in intensive apple growing areas of the North Gyeongsang and North Jeolla Provinces in Korea, were sequenced and compared. The nucleotide sequence identity of the CP gene of eight ASPV isolates ranged from 77.0 to 97.0%, while the amino acid sequence identity ranged from 87.7 to 98.5%. The N-terminal region of the viral CP gene was highly variable, whereas the C-terminal region was conserved. Genetic algorithm recombination detection (GARD) and single breakpoint recombination (SBP) analyses identified base substitutions between eight ASPV isolates at positions 54 and 57 and position 771, respectively. GABranch analysis was used to determine whether the eight isolates evolved due to positive selection. All values in the GABranch analysis showed a ratio of substitution rates at non-synonymous and synonymous sites (dNS/dS) below 1, suggestive of strong negative selection forces during ASPV CP history. Although negative selection dominated CP evolution in the eight ASPV isolates, SLAC and FEL tests identified four possible positive selection sites at codons 10, 22, 102, and 158. This is the first study of the ASPV genome in Korea.

• 한국식품과학회지
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• 제39권4호
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• pp.406-411
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• 2007

흑미가루 첨가비율(5-30%)에 따른 복합분의 이화학적 특성, 호화특성, mixograph 특성 및 스펀지 케이크의 제조적성을 측정하고, 이들 특성 간의 상관관계를 구명하고자 일련의 실험을 실시하였다. 흑미 가루 첨가량이 증가함에 따라서 alkaline water retention capacity, Pelshenke value, sedimentation value는 증가하였으나 water holding capacity는 감소하는 경향을 보였다. Mixograph peak time, height, width at peak와 Rapid Visco Analyser peak, minimum viscosity도 감소하였다. 스펀지 케이크 반죽의 pH와 비중은 증가하였지만 케이크의 부피는 감소하는 경향을 보였으며, 케이크의 경도는 증가하였다.

• 생명과학회지
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• 제21권6호
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• pp.788-795
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• 2011

병원균에 대한 정확한 동정은 임상 연구실에서 필수적인 요소의 하나이다. Chyseobacterium indologenes에 대한 동정을 포함한 분자생물학적 분석과 리보솜의 16S rRNA 유전자로 한국에서 추출한 17검체와 GenBank에서 Chyseobacterium속 검색을 통해 이들과 계통관계를 평가하였다. C. indologenes의 배당 서열은 1,176 nucleotides였다. C. indologenes 내의 서열 변이는 주로 염기 치환이었다. 한국의 C. indologenes 검체는 다른 나라의 동 종과 크게 다르지 않았다. 그런데 한국의 C. indologenes의 치환율은 GenBank에 있는 동종보다 높았다. C. indologenes는 C. isbiliense, C. hominis, C. hispanicum, C. molle, C. hungaricum, and C. pallidum과 자매종을 형성하였다.

• The Plant Pathology Journal
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• 제36권1호
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• pp.87-97
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• 2020

The development of reverse transcription-polymerase chain reaction using degenerate primers against conserved regions of most potyviral genomes enabled sampling of the potyvirome. However, these assays usually involve sampling potential host plants, but identifying infected plants when they are asymptomatic is challenging, and many plants, especially wild ones, contain inhibitors to DNA amplification. We used an alternative approach which utilized aphid vectors and indicator plants to identify potyviruses capable of infecting common bean (Phaseolus vulgaris). Aphids were collected from a range of asymptomatic leguminous weeds and trees in Iran, and transferred to bean seedlings under controlled conditions. Bean plants were tested serologically for potyvirus infections four-weeks postinoculation. The serological assay and symptomatology together indicated the presence of one potyvirus, and symptomology alone implied the presence of an unidentified virus. The partial genome of the potyvirus, encompassing the complete coat protein gene, was amplified using generic potyvirus primers. Sequence analysis of the amplicon confirmed the presence of an isolate of Wisteria vein mosaic virus (WVMV), a virus species not previously identified from Western Asia. Phylogenetic analyses of available WVMV sequences categorized them into five groups: East Asian-1 to 3, North American and World. The Iranian isolate clustered with those in the World group. Multiple sequence alignment indicated the presence of some genogroup-specific amino acid substitutions among the isolates studied. Chinese isolates were sister groups of other isolates and showed higher nucleotide distances as compared with the others, suggesting a possible Eastern-Asian origin of WVMV, the main region where Wisteria might have originated.