Optimization of Macroalgal Density and Salinity for Nutrient Removal by <i>Caulerpa lentillifera</i> from Aquaculture Effluent

Determining the optimum levels of macroalgal density and salinity for removing aquaculture effluent has gained increasing research interest in recent years because of the growing concerns over environmental sustainability. Here, we determined the effects of macroalgal density and salinity on the uptake of NO2&#8722;, NO3&#8722;, NH3, and PO43&#8722; by Caulerpa lentillifera from the effluent of Poecilia latipinna using spectrophotometry. Laboratory experiments were conducted to measure nutrient uptake at five different macroalgal density levels (10, 20, 30, 40, and 50 g/L) and three salinity levels (20, 30, and 40 ppt) with and without aeration. Quadratic regression analysis revealed significant nonlinear and linear effects of macroalgal density on the uptake of NO2&#8722;, NO3&#8722;, NH3, and PO43&#8722;, where the maximum uptake was predicted to occur at the macroalgal densities of 31.6, 33.3, 50.0, and 20.0 g/L, respectively. Likewise, the effects of salinity on the uptake of NO2&#8722;, NO3&#8722;, NH3, and PO43&#8722; were significant and nonlinear where the maximum uptake was predicted to occur at the salinity levels of 29.1, 30.7, 29.5, and 29.5 ppt, respectively. The result of the effects of aeration was mixed but somewhat indicated a positive effect on the nutrient uptake within the 24 h period. Our results could help aquaculturists to minimize the excessive nutrients by C. lentillifera from aquaculture effluent while achieving long-term sustainable aquaculture production

<span style="font-size:15.0pt;mso-bidi-font-family:"Times New Roman";mso-bidi-font-weight: bold" lang="EN-GB">Screening, phenotypic and genotypic identification of β-carotene producing strains of <i style="mso-bidi-font-style:normal">Dunaliella</i> <i style="mso-bidi-font-style:normal">salina</i> from Thailand </span>

2198-2216<i style="mso-bidi-font-style: normal">Dunaliella salina is a salt-loving microalga that accumulates high amounts of β-carotene when cultivated under unfavorable conditions. In this study we aimed to screen <span style="mso-bidi-font-weight:bold; mso-bidi-font-style:italic">β-carotene producing strains of D.salina <span style="mso-bidi-font-style: italic">from salt soil samples collected from 19 provinces in the northeastern part of Thailand. For preliminary screening 70 pure isolated strains were screened by using 18S rDNA conserved primers (MA1&MA2), only 15 isolates produced a band (~2100 bp) as that of <i style="mso-bidi-font-style: normal">D.salina.  For the o<span style="mso-bidi-font-style: italic">bservation of β-carotene production, these 15 isolates were grown on agar plate containing modified Ramaraj medium with 1.0 M NaCl under continuous illumination.  After a month only 3 isolates completely turned red. However, by using the banding pattern produced by 18S rDNA primers, the 15 isolates could not be differentiated between the β-carotene and non β-carotene producing strains. Comparing the above results we found that the <span style="mso-bidi-font-style: italic">observation of β-carotene production on agar plate is more easy and suitable method than molecular technique to screen β-carotene producing strains. Morphological characteristics of the 3 screened Thai isolates clearly delineated that it belongs to the genus Dunaliella. ITS-RFLP banding pattern, 18S rDNA, ITS and RuBisCo large subunit (rbcL) sequences were used to confirm at the species level. These results indicated that these 3 isolates are D.salina and were named <i style="mso-bidi-font-style: normal">D.salina strain KU07, D.salina strain KU11 and D.salina strain KU13. Under non-stress conditions these 3 strains had an ability to accumulate β-carotene up to 5.61±0.25, 7.58±0.19 and 6.73±0.32 pg/cell, respectively. </span

Inhibitory Effects of <i>Caulerpa racemosa</i>, <i>Ulva intestinalis</i>, and <i>Lobophora challengeriae</i> on Tyrosinase Activity and α-MSH-Induced Melanogenesis in B16F10 Melanoma Cells

Melanogenesis involves a synthesis of melanin pigment and is regulated by tyrosinase. The addition of whitening agents with tyrosinase-inhibiting properties in cosmetics is becoming increasingly important. In this study, the ethanolic extracts from twelve seaweeds were assessed for tyrosinase-inhibiting activity using mushroom tyrosinase and melanin synthesis in B16F10 melanoma cells. The highest mushroom tyrosinase inhibition (IC50) was observed with Lobophora challengeriae (0.15 ± 0.01 mg mL−1); treatment was more effective than kojic acid (IC50 = 0.35 ± 0.05 mg mL−1), a well-known tyrosinase inhibitor. Three seaweeds, Caulerpa racemosa, Ulva intestinalis, and L. challengeriae, were further investigated for their ability to reduce melanogenesis in B16F10 cells. The ethanolic extracts of C. racemosa, U. intestinalis, and L. challengeriae showed inhibitory effects by reducing melanin and intracellular tyrosinase levels in B16F10 cells treated with α-melanocyte stimulating hormone in a dose-dependent manner. C. racemosa (33.71%) and L. challengeriae (36.14%) at 25 µg mL−1 reduced melanin production comparable to that of kojic acid (36.18%). L. challengeriae showed a stronger inhibition of intracellular tyrosinase (decreased from 165.23% to 46.30%) than kojic acid (to 72.50%). Thus, ethanolic extracts from C. racemosa, U. intestinalis, and L. challengeriae can be good sources of natural tyrosinase inhibitors and therapeutic or cosmetic agents in the future

Homogeneous Population of the Brown Alga <i>Sargassum polycystum</i> in Southeast Asia: Possible Role of Recent Expansion and Asexual Propagation

<div><p>Southeast Asia has been known as one of the biodiversity hotspots in the world. Repeated glacial cycles during Pleistocene were believed to cause isolation of marine taxa in refugia, resulting in diversification among lineages. Recently, ocean current was also found to be another factor affecting gene flow by restricting larval dispersal in animals. Macroalgae are unique in having mode of reproduction that differs from that of animals. Our study on the phylogeographical pattern of the brown macroalga <i>Sargassum polycystum</i> using nuclear Internal Transcribed Spacer 2 (ITS2), plastidal RuBisCO spacer (Rub spacer) and mitochondrial cytochrome oxidase subunit-III (Cox3) as molecular markers revealed genetic homogeneity across 27 sites in Southeast Asia and western Pacific, in sharp contrast to that revealed from most animal studies. Our data suggested that <i>S. polycystum</i> persisted in single refugium during Pleistocene in a panmixia pattern. Expansion occurred more recently after the Last Glacial Maximum and recolonization of the newly flooded Sunda Shelf could have involved asexual propagation of the species. High dispersal ability through floating fronds carrying developing germlings may also contribute to the low genetic diversity of the species.</p> </div

Haplotype distribution and haplotype network of <i>Sargassum</i><i>polycystum</i> for ITS2, Rub spacer and Cox3.

<p>Pie chart size is proportional to sample size. Abbreviations for sample sites are given in Table S1 in File S1. Dominant currents are shown in solid lines [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077662#B13" target="_blank">13</a>] and seasonally reversing currents in dashed lines [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077662#B14" target="_blank">14</a>]. Light gray area shows the coastal outline during Pleistocene maximum low sea level of 120m [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077662#B1" target="_blank">1</a>]. SEC: South Equatorial Current, NEC: North Equatorial Current, NECC: North Equatorial Counter Current, NGCC: New Guinea Coastal Current, ME: Mindanao Eddy, HE: Halmahera Eddy.</p

Subregions of the study area defined for MIGRATE analysis.

<p>1: South China Sea and Gulf of Thailand; 2: West Coast of Malay Peninsula; 3: West Java; 4: Celebes Sea and Flores Sea; 5: Guam; 6: Pacific Islands. Directionality of gene flows between selected subregions based on Cox3 is shown with N_e, the mean number of effective migrants per generation. All values are within the range of 440 to 665. Other details of gene flow among subregions based on all three markers are listed in Tables S6-S8 in File S1 respectively.</p