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A drug delivery system (DDS) is a useful technology that efficiently delivers a target drug to a patient's specific diseased tissue with minimal side effects. DDS is a convergence of several areas of study, comprising pharmacy, medicine, biotechnology, and chemistry fields. In the traditional pharmacological concept, developing drugs for disease treatment has been the primary research field of pharmacology. The significance of DDS in delivering drugs with optimal formulation to target areas to increase bioavailability and minimize side effects has been recently highlighted. In addition, since the burst release found in various DDS platforms can reduce drug delivery efficiency due to unpredictable drug loss, many recent DDS studies have focused on developing carriers with a sustained release. Among various drug carriers, mesoporous silica DDS (MS-DDS) is applied to various drug administration routes, based on its sustained releases, nanosized porous structures, and excellent solubility for poorly soluble drugs. However, the synthesized MS-DDS has caused complications such as toxicity in the body, long-term accumulation, and poor excretion ability owing to acid treatment-centered manufacturing methods. Therefore, biosilica obtained from diatoms, as a natural MS-DDS, has recently emerged as an alternative to synthesized MS-DDS. This natural silica carrier is an optimal DDS platform because culturing diatoms is easy, and the silica can be separated from diatoms using a simple treatment. In this review, we discuss the manufacturing methods and applications to various disease models based on the advantages of biosilica. [ABSTRACT FROM AUTHOR]

Lagoons are natural bodies of water that are isolated from the sea due to the development of a sand bar or spit. Each lagoon has distinct ecological characteristics, and these sites also serve as popular tourist attractions because they are common habitats for migratory birds and are characterized by beautiful natural scenery. Lagoons also have distinct ecological characteristics from those of their associated estuaries, and there are active research efforts to classify, qualify, and quantify the high biodiversity of lagoons. The lagoons in Korea are primarily distributed in the East Sea, and are represented by Hwajinpo, Yeongrangho, and Gyeongpoho. Here, we report the discovery of 11 unrecorded diatom species (Diploneis didyma, Mastogloia elliptica, Cosmioneis citriformis, Haslea crucigera, Pinnularia bertrandii, Pinnularia nodosa var. percapitata, Gyrosigma sinense, Gomphonema guaraniarum, Gomphonema italicum, Navicula freesei, Trybionella littoralis var. tergestina) among samples collected from the Hwajinpo, Hyangho, Maeho, Gapyeongri wetland, Cheonjinho, and Gyeongpoho lagoons in Korea during a survey from 2018–2020. We present the taxonomic characteristics, ecological information, habitat environmental conditions, and references for these 11 species. [ABSTRACT FROM AUTHOR]

Suncheonman Bay, Korea's most representative estuary, is an invasive coastal wetland composed of 22.6 km2 of tidal flats surrounded by the Yeosu and Goheung Peninsulas. In January 2006, this region was registered in the Ramsar Convention list in Korea, representing the first registered wetland. Estuaries are generally known to have high species diversity. In particular, several studies have been conducted on planktonic and epipelic diatoms as primary producers. Suncheonman Bay has already been involved in many biological and geochemical studies, but fossil diatoms have not been evaluated. Therefore, we investigated fossil diatoms in Suncheonman Bay and introduced sub-fossil diatoms recorded in Korea. One sedimentary core has been extracted in 2018. We identified 87 diatom taxa from 52 genera in the SCW03 core sample. Of these, six species represent new records in Korea: Cymatonitzschia marina, Fallacia hodgeana, Navicula mannii, Metascolioneis tumida, Surirella recedens, and Thalassionema synedriforme. These six newly recorded diatom species were examined by light microscopy and scanning electron microscopy. The ecological habitats for all the investigated taxa are presented. [ABSTRACT FROM AUTHOR]

The dinoflagellate genus Scrippsiella is a common member of phytoplankton and their cysts are also frequently reported in coastal sediments worldwide. However, the diversity of Scrippsiella in Korean waters has not been fully investigated. Here, several isolates of Scrippsiella precaria collected from Korean waters and germinated from resting cysts were examined using light and scanning electron microscopy. The resting cysts were characterized by pointed calcareous spines and one or two red accumulation bodies, and the archeopyle was mesoepicystal, representing the loss of 2–4′ and 1–3a paraplates. Rounded resting cysts were found in culture, and an increase in spine length was observed until 8 days of development. Korean isolates of S. precaria had the plate formula of Po, X, 4′, 3a, 7″, 6C, 4S, 5‴, 2⁗. There were differences in the cell size and location of the red body between Korean isolates and previously described cells of S. precaria. In addition, the Korean isolates of S. precaria had two types of the 5″ plate that either contacted the 2a plate or not. Molecular phylogeny based on internal transcribed spacer (ITS) and large subunit (LSU) rDNA sequences revealed that the Korean isolates were nested within the subclade of PRE (S. precaria and related species) in the clade of Scrippsiella sensu lato, and that the PRE subclade had two ribotypes: ribotype 1 consisting of the isolates from Korea, China, and Australia, and ribotype 2 consisting of the isolates from Italy and Greece. Lineages between isolates of ribotype 1 were likely to be related to the dispersal by ocean currents and ballast waters from international shipping, and the two types of spine shapes and locations of the 5″ plates may be a distinct feature for ribotype 1. [ABSTRACT FROM AUTHOR]

The construction of weirs causes changes in the aquatic environment and affects several aquatic organisms. To understand the ecosystem in the Sangju Weir, Gyeongsangbuk-do Province, variations in the spatiotemporal distribution and composition of microalgae communities were analyzed. Microalgae were collected fortnightly from April to November 2018 from six sites in the Nakdonggang River. There was significant variation in environmental factors, microalgal community structure, and flora. Microalgae communities were dominated by diatoms (e.g., Fragilariacrotonensis, Ulnariaacus, and Aulacoseiraambigua), green algae (e.g., genera Eudorina and Desmodesmus), cyanobacteria (e.g., genera Anabaena and Microcystis). Multidimensional scaling indicated that species composition and diversity were generally similar among sites but varied between the bottom and the surface and middle water layers. Vertical migration of microalgae was difficult to investigate because of the thermocline in the study area and high turbidity in the lower layer. The distribution of microalgae was little affected by the construction of the weir, but the formation of thermocline changed microalgae communities in the water layer. [ABSTRACT FROM AUTHOR]

The effects of the addition of nutrients (nitrate: N; phosphate: P; and vitamin B1) and trace metals (iron: Fe; Copper: Cu; and selenium: Se) on the growth of Gymnodinium catenatum, which was isolated from Korean coastal waters, were investigated. The Korean isolate of G. catenatum grew under a wide range of concentrations of N and P. Whilst high concentrations of N (> N: P ratio of 23.5) did not stimulate the growth rate, an enhanced growth rate and cell density were observed with the addition of P. The experimental addition of vitamin B1 revealed that G. catenatum is not dependent on vitamin B1 for growth. Moreover, the addition of Fe and Cu resulted in no significant differences in the growth patterns and rates of G. catenatum between the controls and treatments. It is thus possible that growth of the Korean isolate of G. catenatum does not require high concentrations of Fe and Cu. However, the cell densities were enhanced in the stationary phases of treatments upon addition of Se, and the maximum cell densities were higher than those in the culture experiments upon additions of other nutrient and trace metals. Our findings indicate that G. catenatum prefers P and Se for proliferation, rather than other nutritional sources. [ABSTRACT FROM AUTHOR]