• 한국해양학회지:바다
• /
• 제8권1호
• /
• pp.29-34
• /
• 2003

한국 서해의 곰소만에서 분리한 온대 해역 산 초유의 M. rubrum MR-MAL01 배양체가 확보되어, M. rubrum의 입자성 먹이 섭식 현상이 보고되었다. 100$\mu$mo1 photons m$^{-2}$ s$^{-1}$의 고광도(HL) 및 10 $\mu$mo1 photons m$^{-2}$ s$^{-1}$의 저광도(LL)에서 광 적응된 미동정 은편모조류 종주 CR-MAL01를 섭식한 M. rubrum의 HL및 LL적응 배양체의 흡광스펙트림을 분석하였다. LL에 적응된 은편모조류를 섭식하고 LL에 적응한 M. rubrum은 섭식 이전의 먹이 세포 흡광특성인 542nm부근의 황갈색 파장 범위에서 뚜렷한 흡광피크를 나타낸 반면, HL에 적응된 은편모조류를 섭식하고 HL에 적응한 M. rubrum은 이러한 흡광 피크를 보이지 않았다. 이는 M. rubrum세포가 자연환경에서 먹이로서 은편모조류 세포를 섭식하기 이전 이들의 광 적응 상태가 섭식 이후 M. rubrum의 광이용 효율 및 광흡수 특성 등을 결정짓는 주요 요인이 될 가능성을 시사한다. 본 연구 결과에 따라 예상되는 해양 미소생물 생태계 내에서 이들 섭식자 및 먹이생물 종의 역할에 대하여 논의하였다.

• 한국산학기술학회논문지
• /
• 제11권9호
• /
• pp.3610-3614
• /
• 2010

새만금 수역에서 2006년 5월부터 2007년 11월까지 8회의 조사를 통해 표영환경의 미소조류군집의 분류군 조성과 다양성지수 등을 연구하였다. 조사수역 미소조류군집의 출현종은 총 191종으로 규조류(Diatom) 94종, 녹조류(Chlorophyte) 31종, 와편모조류(Dinoflagellate) 24종, 남조류(Cyanophyte) 24종, 유글레나조류(Euglenophyte) 11종, 규질 편모류(Silicoflagellate) 3종, 크립토조류(Cryptophyte) 1종, 기타 미동정 미소편모조류 3종 등으로 구성되었다. 연구기간 동안 연구수역 미소조류군집의 다양성 지수는 시공간적으로 변화가 지속되어 일정한 변화의 규칙성을 찾기 어렵다. 이는 공사의 진행과 방조제 수문개폐에 따른 수질환경의 급변 등 인위적 요인이 부유성 미소조류에 스트레스로 작용한 것으로 보인다.

• ALGAE
• /
• 제26권1호
• /
• pp.87-96
• /
• 2011

Protein profiles of a common mixotrophic dinoflagellate, Prorocentrum micans, growing autotrophically and mixotrophically (fed on the cryptophyte Rhodomonas salina) were compared using two-dimensional gel electrophoresis (2-DE) to determine if they vary in different trophic modes. Approximately 2.3% of the detected proteins were differentially expressed in the different trophic modes. Twelve proteins observed only in the mixotrophic condition had lower pI value (<5) than the fifteen proteins observed only in the autotrophic condition (>5). When the internal amino acid sequences of five selected proteins differentially expressed between autotrophic and mixotrophic conditions were analyzed using matrix-assisted laser desorption time-of-flight (MALDI-TOF) mass spectrometry, two proteins that were specifically expressed in the autotrophic condition showed homology to glyceraldehyde-3-phosphatase dehydrogenase (GAPDH) and a bacterial catalase. Three mixotrophy-specific proteins showed homology to certain hypothetical proteins from an insect and bacteria. These results suggested the presence of certain gene groups that are switched on and off according to the trophic mode of P. micans.

• 한국수산과학회지
• /
• 제49권3호
• /
• pp.351-358
• /
• 2016

The aim of this study was to verify the performance of Teleaulax amphioxeia as prey for Brachionus plicatilis and for the larvae of the bivalves (Pacific oyster Crassostrea gigas and Manila clam Ruditapes philippinarum) to select the best of five T. amphioxeia strains. The five strains of T. amphioxeia were collected from the coasts of Korea, purecultured and then fed to the rotifer and bivalve larvae. The density and fecundity rate of the rotifer fed on strain 01 were the highest. The instantaneous growth rate of the rotifer fed strain 08-2 was the highest. The maximum density and fecundity rate of the rotifer fed strain 08-2 were significantly higher than those fed Chlorella ellipsoidea, while instantaneous growth rate showed the opposite pattern. Survival rates of the Manila clam larvae fed each strain of Teleaulax showed no significant difference between strains. Survival rates of the Pacific oyster fed Teleaulax were significantly higher than those fed Chaetoceros sp., but lower than those fed I. galbana. This study indicates that strain 08-2 showed better growth for B. plicatilis and better survival for the bivalve larvae than did the other strains, and that T. amphioxeia can also be used as a prey organism for rotifers or bivalve larvae.

• ALGAE
• /
• 제35권3호
• /
• pp.263-275
• /
• 2020

Water temperature is known to affect the growth and feeding of marine dinoflagellates. Each dinoflagellate species grows well at a certain optimal temperature but dies at very cold and hot temperatures. Thus, changes in water temperatures driven by global warming and extremely high or low temperatures can affect the distribution of dinoflagellates. Yihiella yeosuensis is a mixotrophic dinoflagellate that can feed on only the cryptophyte Teleaulax amphioxeia and the chlorophyte Pyramimonas sp. Furthermore, it grows fast mixotrophically but rarely grows photosynthetically. We explored the direct and indirect effects of water temperature on the growth and ingestion rates of Y. yeosuensis feeding on T. amphioxeia and the growth rates of T. amphioxeia and Pyramimonas sp. under 7 different water temperatures (5-35℃). Both the autotrophic and mixotrophic growth rates of Y. yeosuensis on T. amphioxeia were significantly affected by temperature. Under the mixotrophic and autotrophic conditions, Y. yeosuensis survived at 10-25℃, but died at 5℃ and ≥30℃. The maximum mixotrophic growth rate of Y. yeosuensis on T. amphioxeia (1.16 d^-1) was achieved at 25℃, whereas the maximum autotrophic growth rate (0.16 d^-1) was achieved at 15℃. The maximum ingestion rate of Y. yeosuensis on T. amphioxeia (0.24 ng C predator^-1 d^-1) was achieved at 25℃. The cells of T. amphioxeia survived at 10-25℃, but died at 5 and ≥30℃. The cells of Pyramimonas sp. survived at 5-25℃, but died at 30℃. The maximum growth rate of T. amphioxeia (0.72 d^-1) and Pyramimonas sp. (0.75 d^-1) was achieved at 25℃. The abundance of Y. yeosuensis is expected to be high at 25℃, at which its two prey species have their highest growth rates, whereas Y. yeosuensis is expected to be rare or absent at 5℃ or ≥30℃ at which its two prey species do not survive or grow. Therefore, temperature can directly or indirectly affect the population dynamics and distribution of Y. yeosuensis.

• Journal of the korean society of oceanography
• /
• 제32권1호
• /
• pp.46-55
• /
• 1997

The quantitative determination of carotenoids, chlorophylls and their degradation products from marine phytoplankton was performed by reverse-phase high performance liquid chromatography (HPLC). Separated and quantified chlorophylls and their degraded products are chlorophyll a, b, c, chlorophyllide a, phaeophytin a, b and phaeophorbide a. Concentrations of six carotenoids including fucoxanthin, 19'-butanoyloxyfucoxanthin, 19'-hexanoyloxyfucoxan-thin, prasinoxanthin, alloxanthin, zoaxanthin/lutein were also determined from natural field samples by absorbance. Results of pigment analysis of field samples collected from the southern waters of the East Sea on October 8th, 1996 were reported. Concentration of chi a ranged from 7.2 to 180.4 ng/1. Concentration of chi b and chi c ranged from 22.7 to 53.7 ng/1 and from 3.3 to 58.5 ng/1, respectively. Significant concentrations of phaeophytin a, and chlorophyllide a were also detected at different depths. Fucoxanthin, 19'-hexanoyloxyfucoxanthin and zoaxanthin/lutein were the most abundant carotenoids and 19'-butanoyloxyfucoxanthin, prasinoxanthin and alloxanthin were also detected relatively at low concentrations. These results of pigment analyses suggest predominance of diatom, prymnesiophytes and cyanobacteria and presence of crysophyte, green algae (prasinophyte and prochlorophyte), and cryptophyte in the study area on October 8th, 1996, We report prymnesiophyte for the first time as an important biomass component of marine phytoplankton in the study area. Vertical profiles for the concentration changes of the major pigments were also given.

• 환경생물
• /
• 제40권4호
• /
• pp.374-386
• /
• 2022

Phytoplankton communities, with emphasis on picoplankton and nanoplankton, were investigated in Gamak Bay, South Korea, where freshwater input and coastal water intrusion shape ecosystem functions. Shellfish farms and fish farms are located in the inner bay and outer bay, respectively, and tides translocate uneaten food and urine production from aquaculture farms toward the inner bay. Water masses were distinctly different based on a significantly different density between the surface and bottom layer and among three water masses, including the inner bay, outer bay, and Yeosu Harbor. Phytoplankton communities were quantified using flow cytometry and size-fractionated chlorophyll-a (chl-a) was measured. Salinity was a principal variable separating phytoplankton communities between the surface and bottom layer, whereas Si(OH)₄ controlled the communities in the inner bay, and NH₄⁺ and PO₄^3- governed the outer bay communities. While phycocyanin-containing (PC) cyanobacteria dominated in the outer bay, phycoerythrin-containing (PE) cyanobacteria dominance occurred with cryptophyte dominance, indicating that nutrients affected the distribution of pico- and nanoplankton and that cryptophytes potentially relied on a mixotrophic mode by feeding on PE cyanobacteria. Interestingly, picoeukaryotes and eukaryotes larger than 10 ㎛ were mostly responsible for the ecological niche in the western region of the bay. Given that chl-a levels have historically declined, our study highlights the potential importance of increased small phytoplankton in Gamak Bay. Particularly, we urge an examination of the ecological role of small phytoplankton in the food supply of cultivated marine organisms.

• Bulletin of the Korean Chemical Society
• /
• 제33권3호
• /
• pp.933-940
• /
• 2012

Recently, it has been shown that quantum coherence appears in energy transfers of various photosynthetic lightharvesting complexes at from cryogenic to even room temperatures. Because the photosynthetic systems are inherently complex, these findings have subsequently interested many researchers in the field of both experiment and theory. From the theoretical part, simplified dynamics or semiclassical approaches have been widely used. In these approaches, the quantum-classical Liouville equation (QCLE) is the fundamental starting point. Toward the semiclassical scheme, approximations are needed to simplify the equations of motion of various degrees of freedom. Here, we have adopted the Poisson bracket mapping equation (PBME) as an approximate form of QCLE and applied it to find the time evolution of the excitation in a photosynthetic complex from marine algae. The benefit of using PBME is its similarity to conventional Hamiltonian dynamics. Through this, we confirmed the coherent population transfer behaviors in short time domain as previously reported with a more accurate but more time-consuming iterative linearized density matrix approach. However, we find that the site populations do not behave according to the Boltzmann law in the long time limit. We also test the effect of adding spurious high frequency vibrations to the spectral density of the bath, and find that their existence does not alter the dynamics to any significant extent as long as the associated reorganization energy is changed not too drastically. This suggests that adopting classical trajectory based ensembles in semiclassical simulations should not influence the coherence dynamics in any practical manner, even though the classical trajectories often yield spurious high frequency vibrational features in the spectral density.

• Bulletin of the Korean Chemical Society
• /
• 제35권3호
• /
• pp.858-864
• /
• 2014

Recently, many researches have shown that even photosynthetic light-harvesting pigment-protein complexes can have quantum coherence in their excitonic energy transfer at cryogenic and physiological temperatures. Because the protein supplies such noisy environment around pigments that conventional wisdom expects very short lived quantum coherence, elucidating the mechanism and searching for an applicability of the coherence have become an interesting topic in both experiment and theory. We have previously studied the quantum coherence of a phycocyanin 645 complex in a marine algae harvesting light system, using Poisson mapping bracket equation (PBME). PBME is one of the applicable methods for solving quantum-classical Liouville equation, for following the dynamics of such pigment-protein complexes. However, it may suffer from many defects mostly from mapping quantum degrees of freedom into classical ones. To make improvements against such defects, benchmarking targets with more accurately described dynamics is highly needed. Here, we fall back to reduced hierarchical equation of motion (HEOM), for such a purpose. Even though HEOM is known to applicable only to simplified system that is coupled to a set of harmonic oscillators, it can provide ultimate accuracy within the regime of quantum-classical description, thus providing perfect benchmark targets for certain systems. We compare the evolution of the density matrix of pigment excited states by HEOM against the PBME results at physiological temperature, and observe more sophisticated changes of density matrix elements from HEOM. In PBME, the population of states with intermediate energies display only monotonically increasing behaviors. Most importantly, PBME suffers a serious issue of wrong population in the long time limit, likely generated by the zero-point energy leaking problem. Future prospects for developments are briefly discussed as a concluding remark.

• ALGAE
• /
• 제30권4호
• /
• pp.281-290
• /
• 2015

We explored phagotrophy of the phototrophic ciliate Mesodinium rubrum on the cyanobacterium Synechococcus. The ingestion and clearance rates of M. rubrum on Synechococcus as a function of prey concentration were measured. In addition, we calculated grazing coefficients by combining the field data on abundance of M. rubrum and co-occurring Synechococcus spp. with laboratory data on ingestion rates. The ingestion rate of M. rubrum on Synechococcus sp. linearly increased with increasing prey concentrations up to approximately 1.9 × 10⁶ cells mL^-1, to exhibit sigmoidal saturation at higher concentrations. The maximum ingestion and clearance rates of M. rubrum on Synechococcus were 2.1 cells predator^-1 h^-1 and 4.2 nL predator^-1 h^-1, respectively. The calculated grazing coefficients attributable to M. rubrum on cooccurring Synechococcus spp. reached 0.04 day^-1. M. rubrum could thus sometimes be an effective protistan grazer of Synechococcus in marine planktonic food webs. M. rubrum might also be able to form recurrent and massive blooms in diverse marine environments supported by the unique and complex mixotrophic arrays including phagotrphy on hetrotrophic bacteria and Synechococcus as well as digestion, kleptoplastidy and karyoklepty after the ingestion of cryptophyte prey.