• ALGAE
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• 제26권3호
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• pp.265-275
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• 2011

This study examined the bioaccumulation of the heavy metals copper (Cu) and zinc (Zn) by the giant kelp, Macrocystis pyrifera, by exposing meristematic kelp tissue to elevated metal concentrations in seawater within laboratory aquaria. Specifically, we carried out two different experiments. The first examined metal uptake under a single, ecologically-relevant elevation of each metal (30 ppb Cu and 100 ppb Zn), and the second examined the relationships between varying levels of the metals (i.e., 15, 39, 60, 120, 240, and 480 ppb Cu, and 50, 100, 200, 300, 500, and 600 ppb Zn). Both experiments were designed to contrast the uptake of the metals in isolation (i.e., when only one metal concentration was elevated) and in combination (i.e., when both metals' concentrations were elevated). Following three days of exposure to the elevated metal concentrations, we collected and analyzed the M. pyrifera tissues using inductively coupled plasma atomic emissions spectroscopy. Our results indicated that M. pyrifera bioaccumulated Cu in all treatments where Cu concentrations in the seawater were elevated, regardless of whether Zn concentrations were also elevated. Similarly, M. pyrifera bioaccumulated Zn in treatments where seawater Zn concentrations were elevated, but this occurred only when we increased Zn alone, and not when we simultaneously increased Cu concentrations. This suggests that elevated Cu concentrations inhibit Zn uptake, but not vice versa. Following this, our second experiment examined the relationships among varying seawater Cu and Zn concentrations and their bioaccumulation by M. pyrifera. Here, our results indicated that, as their concentrations in the seawater rise, Cu and Zn uptake by M. pyrifera tissue also rises. As with the first experiment, the presence of elevated Zn in the water did not appear to affect Cu uptake at any concentration examined. However, although it was not statistically significant, we observed that the presence of elevated Cu in seawater appeared to trend toward inhibiting Zn uptake, especially at higher levels of the metals. This study suggests that M. pyrifera may be useful as a bio-indicator species for monitoring heavy metal pollution in coastal environments.

• ALGAE
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• 제29권3호
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• pp.203-215
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• 2014

As global warming continues over the coming century, marine organisms will experience a warmer, more acidic ocean. Although these stressors may behave antagonistically or synergistically and will impact organisms both directly (i.e., physiologically) and indirectly (i.e., through altered species interactions), few studies have examined the complexities of these effects in combination. To address these uncertainties, we examined the independent and combined effects of elevated temperature and $pCO_2$ on the physiology of the adult sporophyte stage of giant kelp, Macrocystis pyrifera, and the grazing of the purple sea urchin Strongylocentrotus purpuratus. While elevating $pCO_2$ alone had no effect on M. pyrifera growth or photosynthetic carbon uptake, elevating temperature alone resulted in a significant reduction in both. However, when M. pyrifera was grown under elevated temperature and $pCO_2$ together, growth and photosynthetic carbon uptake significantly increased relative to ambient conditions, suggesting an interaction of these factors on photosynthetic physiology. S. purpuratus held under future conditions generally exhibited reduced growth, and smaller gonads than urchins held under present-day conditions. However, urchins fed kelp grown under future conditions showed higher growth rates, partially ameliorating this effect. Feeding rates were variable over the course of the experiment, with only the first feeding rate experiment showing significantly lower rates for urchins held under future conditions. Together, these data suggest that M. pyrifera may benefit physiologically from a warmer, more acidic (i.e., higher $pCO_2$) ocean while S. purpuratus will likely be impacted negatively. Given that kelp-urchin interactions can be important to kelp forest structure, changes to either of these populations may have serious consequences for many coastal environments.

• ALGAE
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• 제35권2호
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• pp.167-176
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• 2020

Iodine exists as a trace element in seawater, with total iodine being generally constant at about 0.45-0.55 μM. Almost all of this iodine occurs in two main forms: iodate and iodide. Iodate is the thermodynamically stable form under normal seawater conditions, and thus should be the only iodine-containing species in the water column. However, iodate concentrations are found to vary considerably, being generally greater at depth and lower at the surface, while iodide concentrations follow the reverse pattern, being anomalously accumulated in the euphotic zone and decreasing with depth. The fact that iodide concentrations follow a depth dependence corresponding to the euphotic zone suggests that biological activity is the source of the reduced iodine. Nonetheless, the nature and source of iodate reduction activity remains controversial. Here, using a combination of field and laboratory studies, we examine some of the questions raised in our and other previous studies, and seek further correlations between changes in iodine speciation and the presence of marine macro- and microalgae. The present results indicate that microalgal growth per se does not seem to be responsible for the reduction of iodate to iodide. However, there is some support for the hypothesis that iodate reduction can occur due to release of cellular reducing agents that accompany cell senescence during phytoplankton bloom declines. In addition, support is given to the concept that macroalgal species such as giant kelp (Macrocystis pyrifera) can take up both iodide and iodate from seawater (albeit on a slower time scale). We propose a mechanism whereby iodate is reduced to iodide at the cell surface by cell surface reductases and is taken up directly as such without reentering the bulk solution.

• ALGAE
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• 제35권3호
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• pp.237-252
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• 2020

Temperate rocky reefs dominated by the giant kelp, Macrocystis pyrifera, support diverse assemblages of benthic macroalgae that provide a suite of ecosystem services, including high rates of primary production in aquatic ecosystems. These forests and the benthic macroalgae that inhabit them are facing both short-term losses and long-term declines throughout much of their range in the eastern Pacific Ocean. Here, we quantified patterns of benthic macroalgal biomass and irradiance on rocky reefs that had intact kelp forests and nearby reefs where the benthic macroalgae had been lost due to deforestation at three sites along the California, USA and Baja California, MEX coasts during the springs and summers of 2017 and 2018. We then modeled how the loss of macroalgae from these reefs impacted net benthic productivity using species-specific, mass-dependent rates of photosynthesis and respiration that we measured in the laboratory. Our results show that the macroalgal assemblages at these sites were dominated by a few species of stipitate kelps and fleshy red algae whose relative abundances were spatially and temporally variable, and which exhibited variable rates of photosynthesis and respiration. Together, our model estimates that the dominant macroalgae on these reefs contribute 15 to 4,300 mg C m^-2 d^-1 to net benthic primary production, and that this is driven primarily by a few dominant taxa that have large biomasses and high rates of photosynthesis and / or respiration. Consequently, we propose that the loss of these macroalgae results in the loss of an important contribution to primary production and overall ecosystem function.

• Journal of Microbiology and Biotechnology
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• 제28권10호
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• pp.1671-1682
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• 2018

Alginate lyases (endo and exo-lyases) are required for the degradation of alginate into its constituting monomers. Efficient bioethanol production and extraction of bioactives from brown algae requires intensive use of these enzymes. Nonetheless, there are few commercial alginate lyase preparations, and their costs make them unsuitable for large scale experiments. A recombinant expression protocol has been developed in this study for producing seven endo-lyases and three exo-lyases as soluble and highly active preparations. Saccharification of alginate using 21 different endo/exo-lyase combinations shows that there is complementary enzymatic activity between some of the endo/exo pairs. This is probably due to favorable matching of their substrate biases for the different glycosidic bonds in the alginate molecule. Therefore, selection of enzymes for the best saccharification results for a given biomass should be based on screens comprising both types of lyases. Additionally, different incubation temperatures, enzyme load ratios, and enzyme loading strategies were assessed using the best four enzyme combinations for treating Macrocystis pyrifera biomass. It was shown that $30^{\circ}C$ with a 1:3 endo/exo loading ratio was suitable for all four combinations. Moreover, simultaneous loading of endo-and exo-lyases at the beginning of the reaction allowed maximum alginate saccharification in half the time than when the exo-lyases were added sequentially.

• ALGAE
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• 제34권2호
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• pp.141-151
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• 2019

The 1982-83, 1986-87, 1991-92, and 1997-98 El $Ni{\tilde{n}}o$-Southern Oscillations (ENSOs) were compared with regards to their strength and timing in the tropical Pacific Ocean, changes in ocean temperature and wave intensity, and their impacts to giant kelp populations in the Northeast Pacific. The Multivariate ENSO Index, oceanographic data, and kelp abundance data all show that the 1982-83 and 1997-98 ENSOs were stronger and resulted in greater losses of giant kelp than the 1986-87 and 1991-92 ENSOs, but that the 1982-83 and 1997-98 ENSOs differed with regard to the arrival of destructive waves relative to when the ocean waters warmed and cooled. The 1982-83 ENSO was more destructive to the giant kelp populations in central California, USA than the 1997-98 ENSO, but the 1997-98 ENSO was more destructive to the giant kelp in southern California. These events appeared similarly destructive to the populations in Baja California, Mexico. Recovery of the kelp populations also varied among the two strong ENSOs due to the ocean conditions following each ENSO. In southern and Baja California, recovery was slow following the 1982-83 ENSO, while recovery was more rapid following the 1997-98 ENSO. Unfortunately, the monitoring programs used to evaluate the kelp populations stopped shortly after the 1997-98 ENSO, resulting in a lack of data for comparisons with the more recent weak ENSOs that occurred between 2002 and 2010, or with the strong ENSO that occurred in 2014-2016. This supports the need for continued long-term monitoring programs to better understand how climate anomalies impact coastal ecosystems.

• 한국수산과학회지
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• 제31권1호
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• pp.82-89
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• 1998

미역과 큰 다시마 알긴산의 염산 부분가수분해에 의한 저분자화 조건을 구명하였으며, 저분자화가 알긴산의 점성, 용해도, 유화능, 흡유능, 담즙산결합능 및 금속이온결합능 등의 물성에 미치는 영향에 관하여 검토하였다. 미역에서 추출한 알긴산을 시료로 하여 저분자화의 조건을 검토한 결과, 염산에 의한 반응시간의 연장 및 염산의 농도증가와 더불어 구성 polyuronate의 중합도는 급격히 감소하였다. 그리고 0.3N HCl 부분가수분해에 의하여 분자량을 1/100로 감소시키는데 소요되는 반응시간은 약 50분이었고, 이 때 각각의 수율은 약 $75\%\~80\%$ 이었다. 각 알긴산의 M/G의 비는 저분자화에 의하여 증대하였으며, 알긴산 용액의 점성은 저분자화하므로서 급격히 저하하였고, 알긴산의 점도와 분자량은 밀접한 상관관계를 보였다($r^2=0.9890$). 온도단계별 ($5\~40^{\circ}C$)로 측정한 알긴산의 용해도는 수용성 알긴산이 산$\cdot$알칼리가용성 알긴산에 비하여 $7\~12\%$ 높았으며, 저분자화와 더불어 상승하였다. 한편, 저분자화는 유화능의 증가를 가져왔으며, 용해도와는 비슷한 관계를 보였다. 그러나 흡유능과 금속이온결합능은 저분자화에 의하여 감소하였으며, 특히 금속이온결합능에 있어서는 미역 알긴산은 $Pb^{2+},\;Cu^{2+},\;Zn^{2+},\;Co^{2+}$의 순으로, 그리고 큰 다시마 알긴산은 $Cu^{2+},\;Pb^{2+},\;Zn^{2+},\;Co^{2+}$의 순으로 각각 감소하였다. 담즙산결합능은 저분자화와 더불어 오히려 증가하는 특징을 보였다.

• 한국수산과학회지
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• 제31권3호
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• pp.399-408
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• 1998

미역과 큰다시마에서 추출한 수용성 알긴산 및 산$\cdot$알칼리가용성 알긴산과 그 염산부분가수분해에 의하여 얻어진 저분자화 알긴산 (저분자화 범위 : 미역 약 4,000 kDa$\to$약 38kDa; 큰다시마 약 1.283kDa$\to$약 341 kDa과 약 45kDa)을 함유한 실험사료를 횐쥐 (SD계, 4주령)에 4주간 급이했을 때의 혈청 및 간장지질 콜레스테롤 수준 및 지방산 조성에 미치는 영향을 실험$\cdot$검토하였다. 알긴산의 급이는 식이효율이 $0.37\~0.44$로서 기초식이군에 비하여 $0.03\~0.05$ 정도 낮은 값을 보였고, 콜레스테롤 급이에 의한 간의 중량 증가도 유의적으로 억제하였다. 수용성 알긴산은 산$\cdot$알칼리가용성 알긴산에 비하여 혈청 및 간장지질 중의 총콜레스테롤, 유리콜레스테롤, LDL-콜레스테롤, triglyceride및 인지질에 대하여 현저한저감효과를 보였다. 그리고 각각의 효과는 저분자화에 의하여 현저히 증대되었다(저분자화에 의한 저감효과 수용성 알긴산 - 혈청지질: 총콜레스테롤 $59\%$, 유리콜레스테롤 $65\%$, LDL-콜레스테롤 $96\%$, triglyceride $50\%$, 인지질 $36\%$, 간장지질: 총콜레스테롤 $42\%$, 유리콜레스테롤 $62\%$, LDL-콜레스테롤 $44\%$, triglyceride $33\%$, 인지질 $44\%$ 산$\cdot$알칼리가용성 알긴산 - 혈청지질: 총콜레스테롤 $52\%$, 유리콜레스테롤 $97\%$, LDL-콜레스테롤 $78\%$, triglyceride $32\%$, 인지질 $64\%$, 간장지질. 총콜레스테롤 $11\%$, 유리콜레스테롤 $12\%$, LDL-콜레스테롤 $10\%$, triglyceride $27\%$, 인지질 $21\%$) 저분자화 알긴산의 급이가 혈청 및 간장지질 구성지방산의 조성에 미치는 효과는 콜레스테롤 급이군에 비하여 polyene산의 함유비율을 혈청지질에 있어서는 약 $44\%$이상, 그리고, 간장지질에 있어서는 약 $70\%$ 이상으로 각각 증가시켰다. 이상의 결과에 비추어 저분자화 알긴산의 급이는 실험동물의 혈청 및 간장지질 조성을 생리적으로 개선하는데 그 효과가 현저함을 뒷받침하였다.