• 한국환경과학회지
• /
• 제21권11호
• /
• pp.1297-1305
• /
• 2012

Clonal plants combine sexual and clonal reproduction, which contribute differently to plant fitness. Reproductive analyses have highlighted the importance of clonal growth in shaping the spatial genetic structure in Potentilla conferta Bunge, a herbaceous rhizomatic clonal distributed in hot sand dunes. We investigated the reproduction system of P. conferta at two populations in Mongol and three natural populations in Uzbekistan. The measurements of 19 quantitative or qualitative morphological characters were taken on each of total individuals directly from their natural habitats. Some morphological characteristics between Mongolia and Uzbekistan populations showed a slight heterogeneity of variance. Especially, the length of internodes (LFI and LSI) and characteristics of root (LLR and NOR) were shown a significant difference between two countries (P<0.05). P. conferta of Uzbekistan has most ramets at short distance intervals 30~100 cm. In light conditions, P. conferta of Uzbekistan was significantly less resilience than P. conferta of Mogol. In drought conditions, although there was not shown significant difference, P. conferta in Uzbekistan was less resilience than that in Mogol. The core analysis indicates that P. conferta in Uzbekistan is the more resistant than that of Mongol and seems to do by sexual reproduction strategy during several strong environmental disadvantages such as drought events.

• ALGAE
• /
• 제20권1호
• /
• pp.1-13
• /
• 2005

The taxonomic status of three closely related species of the genus Sphacelaria, S. rigidula Kützing, S. fusca (Hudson) C.F Gray and S. didichotoma Saunders was reassessed on the basis of morphological observations from herbarium specimens and phylogenetic analysis of RUBISCO spacer sequences. Sphacelaria rigidula was characterized by having only 2-armed propagules and somewhat slender filaments. Culture experiments revealed that its propagules commonly formed secondary arms, even though they were rarely produced in the field. It is concluded that S. divaricata Montagne characterized by dichotomously branched arms in propagules shoud be synonymized with S. rigidula, based on propagule morphology and measurements. Sphacelaria fusca clearly be separated from S. rigidula by having 2-4 armed propagules. These morphological differences were highly supported by the differences in the RUBISCO spacer sequences. S. didichotoma resembles S. rigidula in having propagules with two dichotomously branched arms. However, it commonly produces the secondary arms in the field. Additionally, this species has shorter primary arms than S. rigidula. Phylogenetic analyses supported the distinction of S. didichotoma from S. rigidula. The northwestern Pacific plants, previously recorded as S. divaricata, were recognized as S. didichotoma.

• 한국해양학회지
• /
• 제4권1호
• /
• pp.17-35
• /
• 1969

This work concerns morphological studies of the Japaness jack mackerel, Trachurus japonicus(Temminck & Schlegel). A total of 48 random samples consisting of 2669 fish is examined, representing three geographic regions, namely, Kamakura, Nagasaki, and Tottori. Preservation affects length and weight of fish considerably, but the variability after 10 days is shown to be negligible. The variability in measuring the morphometric characters due to different measures and orders is found to be significant. They are relatively small, however, compared to the variability in mean length to be expected in samples drawn from the population. Two meristic characters, namely, anal and second dorsal fin rays and three morphometric characters, namely, head length, first and second dorsal insertion distances are chosen for the study. Results of the statistical analysis reveal that differences in the selected meristic characters among samples within and between regions are found to be significant. In general, it is reasonable to state that the jack mackerel collected in Nagasaki region, on the average, have greatest number of anal fin ray and second dorsal fin ray followed by Kamakura, and Tottori regions in that order. It is found that although no significant differences in the slope of regression line are noticed, the mean differences of the selected morphometric measurements in relation to fish length are found to be significant among samples within each region. Differences in the regression coefficients as well as the adjusted sample means are found to be significant between regions. The analysis suggests that samples from Nagasaki region, on the average, have longest head length and greatest distances from snout to the insertion of first dorsal and second dorsal fins followed by Kamakura, and Tottori regions in that order.

• Animal cells and systems
• /
• 제15권1호
• /
• pp.45-51
• /
• 2011

To clarify the taxonomic status of five specimens of Albula collected from Korea and Taiwan (Albula sp.), genetic differences among them and other congeneric species were investigated based on mitochondrial DNA cytochrome b sequences. All five specimens of Albula sp. showed identical haplotypes and strongly supported a monophyletic group on phylogenetic analysis. The genetic differences between Albula sp. and ten other species of Albula ranged from 0.100 to 0.164. These values were almost equal to or exceeded the interspecific differences among the latter ten species (0.038-0.206). Morphological comparisons of Albula sp. and another four Indo-Pacific species, A. argentea, A. glossodonta, A. oligolepis and A. virgata, are also presented. Albula sp. could be distinguished from the latter four species in their numbers of pored lateral-line scales, anal fin rays and vertebrae, as well as in several proportional measurements.

• Animal Systematics, Evolution and Diversity
• /
• 제36권3호
• /
• pp.251-257
• /
• 2020

The genus Plectus Bastian, 1865 represents a group of free-living freshwater nematodes belonging to the family Plectidae Örley, 1880. However, only one species has been reported thus far from Korea. Plectus aquatilis Andrássy, 1985 and Plectus cirratus Bastian, 1865 are reported for the first time from Korea, from sediments collected from the Nakdong River. Plectus aquatilis is distinguished from other Plectus species by its three longitudinal alae in the lateral field, thin and directed cephalic setae, continuous lip region (head not set-off), and rectangular shaped tail. Plectus cirratus is distinguished from other Plectus species by its large body, two longitudinal alae in the lateral field, larger stoma, and longer tail. Morphological characters and measurements of the specimens generally agree with the original descriptions of Plectus species. Here, the morphological characters (detailed morphometrics) of two species in the genus Plectus are fully redescribed and illustrated using optical microscopy. DNA barcode sequence information from the 18S rDNA gene is also provided for molecular species identification and compared with sequences from other Plectus species available on GenBank.

• International Journal of Oral Biology
• /
• 제44권3호
• /
• pp.108-114
• /
• 2019

In the present study, rutile phase titanium dioxide nanoparticles ($R-TiO_2$ NPs) were prepared by hydrolysis of titanium tetrachloride in an aqueous solution followed by calcination at $900^{\circ}C$. The composition of $R-TiO_2$ NPs was determined by the analysis of X-ray diffraction data, and the characteristic features of $R-TiO_2$ NPs such as the surface functional group, particle size, shape, surface topography, and morphological behavior were analyzed by Fourier-transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, transmission electron microscopy, dynamic light scattering, and zeta potential measurements. The average size of the prepared $R-TiO_2$ NPs was 76 nm, the surface area was $19m^2/g$, zeta potential was -20.8 mV, and average hydrodynamic diameter in dimethyl sulfoxide (DMSO)-$H_2O$ solution was 550 nm. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and morphological observations revealed that $R-TiO_2$ NPs were cytocompatible with oral cancer cells, with no inhibition of cell growth and proliferation. This suggests the efficacy of $R-TiO_2$ NPs for the aesthetic white pigmentation of teeth.

• Animal Systematics, Evolution and Diversity
• /
• 제37권3호
• /
• pp.205-211
• /
• 2021

This study investigates the morphological and skull characteristics of the Siberian weasel Mustela sibirica quelpartis from the Jeju Island, South Korea. A total of 26 roadkill specimens (22 males and 4 females) were collected from October 2012 to April 2016. All collected specimens were examined for morphological characteristics, but only 19 specimens (16 males and 3 females) were in a good enough condition to process for skull measurements. This study showed no significant differences in ear length between male and female (p>0.05), and significant differences were found in head-body length, tail length (TL), and hind-food length (p<0.05). Both the male and female of M. s. quelpartis were larger in its external characteristics except for TL than M. s. coreanus living in the mainland of South Korea. M. s. quelpartis males have a smaller skull size than their female counterparts. In general, both male and female M. s. quelpartis showed external characteristics in line with the Island Rule. The findings of this study are important in order to shed more light on the evolutionary mechanism of small mammals living on the Jeju Island.

• 한국지형학회지
• /
• 제27권2호
• /
• pp.19-28
• /
• 2020

Grain size analysis is the most basic procedure for identifying the origin, transport and sedimentation processes of sediments, and is widely used in geomorphology and sedimentology. Traditionally, grain size was determined by a sieve-pippette method, but the use of automated analyzers is increasing in recent years. These analyzers have many advantages over traditional techniques, but the measurement results are not always the same. It is still difficult to solve the pretreatment problem such as incomplete diffusion and residual organic matter, and inappropriate results may be obtained. This study compared image-based grain size analysis and sieve analysis to verify its statistical reliability, and conducted experiments to enhance the measurement accuracy using shape parameters. The results showed that the image-based analysis overestimated the grain size of sand dunes by about 7% compared to the sieve analysis, but the two measurements were not statistically different. In addition, by using shape parameters, such as aspect ratio, sphericity, and convexity, improved statistics were obtained compared to the original data. Using the morphological properties of the individual grains is a complementary method to the incomplete pretreatment of the grain size analysis process, and at the same time, it will contribute to improving the accuracy and reliability of the results.

• 한국작물학회지
• /
• 제52권1호
• /
• pp.1-11
• /
• 2007

일사 저하에 따른 벼의 형태적 변화와 광합성 특성 변화를 평가하기 위하여, 필리핀 소재 국제미작연구소(IRRI)에서 3품종을 이용하여 분얼기, 생식생장기, 등숙기에 약 40% 차광 처리하고 자연광 처리를 두어 비교한 결과는 다음과 같다. 1. 차광 조건에서 벼는 단위 엽면적 및 엽록소계(SPAD) 측정값 증가, 엽신으로의 건물중 분배비율 증가 등 일조 부족에 대한 적응 형태를 나타내었으나, 분얼이 지연되고 건물 생산량이 감소하는 특징을 보였다. 2. 차광 조건에서 생육한 벼는 자연광 조건에서 생육한 벼에 비하여 탄소동화속도가 늦었으나 조직 내 이산화탄소의 농도는 높게 유지되어, 차광 내 벼의 광합성이 낮았던 것은 광합성 기질인 이산화탄소의 제한이 아니고 photosystem의 전자전달 활성의 약화에 기인된 것으로 판단되었다. 3. 차광 조건에서 생육한 벼를 자연광에 1일간 노출시켜 순화한 후 측정한 최대 광합성과 photosynthetic photon flux density에 대한 광합성 반응은 자연광에서 생육한 벼의 광합성 반응과 차이를 보이지 않아, 차광 조건에서 생육한 벼는 자연광에서 생육한 벼 수준의 잠재 광합성 능력을 유지하고 있었으며, 차광에서의 광합성 저하는 단순하게 일사량 저하에 의한 현상이었다. 4. 분얼기간 동안 차광 조건에서 생육하고 유수형성기 이후 자연광에 노출되어 생육한 벼는 자연광 조건에서 생육한 벼에 비하여 유수형성기부터 출수기까지의 SPAD 값의 증가 정도가 적으며, 엽신 질소 함량의 감소 정도가 크고, $2,000\;{\mu}mol\;m^{-2}s^{-1}$ 이상으로 강한 광 조건에서는 광합성이 감소하는 경향을 보여, 일조 부족에 적응한 벼는 photoinhibition 정도가 큰 것으로 생각된다. 5. 벼 수량은 자연광 처리에 비하여 유수형성기$\sim$출수기 차광에서는 수당영화수와 포트당 영화수의 감소에 의하여, 출수기$\sim$성숙기 차광에서는 등숙비율의 저하에 의하여 감소하였다.

• Investigative Magnetic Resonance Imaging
• /
• 제15권1호
• /
• pp.48-56
• /
• 2011

목적 : 본 연구에서는 금 나노 입자를 통한 국소 가열과 MR 온도 영상 기법을 결합한 Theragnosis 개념에 대한 가초연구로 금 나노 입자의 특성 및 제조 조건에 따른 MR 변수의 변화를 연구하였다. 대상 및 방법 : 실험실에서 제조된 구형과 막대형 금 나노 입자를 사용하였다. 구형 입자는 합성방법과 교반속도(stirring speed: rpm)를 변수로 설정하였고, 막대형 입자눈 첨가된 구형 입자의 양을 변수로 하여 조건을 다양화하였다. 금 나노 입자를 2% 아가로즈 젤에 1:1 로 혼합하여 임상용 1.5T MRI 시스템에서 신호를 획득하였고, $T_1$과 $T_2$ 이완시간의 측정을 위해 TR과 TE를 조절하였다. 획득한 영상의 화소별 신호 강도플 이용하여 제작한 소프트웨어로 $T_1$과 $T_2$ 이완곡선을 추정하였고, 통계 분석으로 유의성을 검증하였다. 결과 : 구형 입자의 평균 $T_1$ 값은 $1.86{\pm}0.04$초, 막대형은 평균 $2.08{\pm}0.04$초로 막대형이 더 걸게 측정되었고, 반면 평균 $T_2$ 값은 구형과 막대형 각각 $57{\pm}2.4$ ms와 $35.45{\pm}0.1$ ms로 구형 나노 입자에서 더 길게 측정되었다. 결론 : 금 나노 입자의 형태적 특성 및 제조 조건에 따른 MR 영상 변수 $T_1$과 $T_2$ 이완시간의 변화를 확인하였다. 금 나노 입자를 이용한 MR 영상 연구의 수행 시 금 나노 입자의 형태와 제조 조건에 따른 적절한 TR과 TE로 최적화된 영상을 얻을 수 있을 것으로 기대된다.