Microplastic Contamination of a Benthic Ecosystem in a Hydrothermal Vent.

Plastic contamination is a global pervasive issue, extending from coastal areas and open oceans to polar regions and even the deep sea. Microplastic (MP) contamination in hydrothermal vents, which are known for their high biodiversity even under extreme conditions, has remained largely unexplored. Here, we present, for the first time, MP pollution in a deep-sea hydrothermal vent at one of the biodiversity hotspots─the Central Indian Ridge. Not only the environment (seawater: 2.08 ± 1.04 MPs/L, surface sediments: 0.57 ± 0.19 MP/g) but also all six major benthic species investigated were polluted by MPs. MPs mainly consisted of polypropylene, polyethylene terephthalate, and polystyrene fragments ≤100 µm and were characterized as being either transparent or white in color. Remarkably, bioaccumulation and even biomagnification of microplastics were observed in the top predators of the ecosystem, such as squat lobsters (14.25 ± 4.65 MPs/individual) and vent crabs (14.00 ± 2.16 MPs/individual), since they contained more MPs than animals at lower trophic levels (e.g., mussels and snails, 1.75-6.00 average MPs/individuals). These findings reveal MP contamination of an ecosystem in a hydrothermal vent, thereby suggesting that their accumulation and magnification can occur in top-level animals, even within remote and extreme environments.

Haplotype diversity of Heterodera koreana (Tylenchida: Heteroderidae), affecting bamboo in Korea.

In a survey of plant-parasitic nematodes in agricultural fields, cyst-forming nematodes were found in soil planted bamboo in Korea. The aim of this study was to identify the cyst nematodes based on morphological and molecular characteristics. As the results, the morphology and morphometrics of cysts and second-stage juveniles (J2s) were consistent with those of previous descriptions of Heterodera koreana. In phylogenetic analyses based on DNA sequences, these cyst nematodes were clustered together with clade of H. koreana in internal transcribed spacer (ITS) region, and large subunit D2-D3 segments (LSU D2-D3). These nematodes were clustered together with clade of H. koreana in cytochrome c oxidase subunit I (COI) gene, but a haplotype was different when compared with previous reported haplotypes (haplotype A-C) in Japan. This study showed these cyst nematodes were identified as H. koreana, and a new haplotype of H. koreana is distributed in Korea. We suggest that the new haplotype of H. koreana name as haplotype D.

First Report of Stunt Nematode, Tylenchorhynchus zeae, on Corn in Republic of Korea.

Corn (Zea mays), one of the major food sources it contains rich in fiber and many vitamins, is one of the most widely consumed cereal grains in Republic of Korea. A survey of plant-parasitic nematodes (PPNs) was carried out in corn fields in Goesan, Republic of Korea from August in 2021. PPNs were extracted from the corn roots and soil using modified Baermann funnel methods and were identified using morphological and molecular analyses. Among the roots and soil samples of 21 fields, 5 fields (23.8%) were infected with stunt nematodes. Tylenchorhynchus zeae was originally described in India from soil around corn and is reported to dwarf plants, yellow leaves (Sethi and Swarup, 1968). Morphologically, characteristics of females were very similar to T. zeae with cylindrical body and slightly ventrally arcuated after fixation. Lip region slightly offset from body with four annuli. Stylet with anteriorly flattened knobs, the vulva was located in the center of the body, didelphic-amphidelphic reproductive system and tail conoid, tail terminus with obtuse smooth, with four incisures areolated throughout body. Bodies of males were similar to females but with shaper tails, with relatively strong bursa and spicules (Fig. S1). The morphology of Korean populations was in agreement with the described populations of India and China (Alvani et al., 2017; Xu et al., 2020). Measurements and micrographs with the light-microscope (DM5000; Leica[Germany]) and camera (DFC450; Leica[Germany]) were taken from females (n=10) for mean, standard deviation and range of body length: 553.2 ± 41.2 (492.7-643.6) µm, maximum body width: 19.4 ± 1.0 (17.6-21.0) µm, stylet length: 18.1 ± 0.4 (17.5-18.7) µm, percent of distance from anterior end to vulva / body length: 58.5 ± 1.3 (56.1-60.9), tail length: 31.7 ± 1.2 (30.3-34.0) µm, and distance of anterior to excretory pore: 96.5 ± 1.8 (94.1-99.4) µm. In addition, PCR was performed for the 28S rDNA D2-D3 segments using the primers D2A and D3B, and ITS region with the primers TW81 and AB28. The newly obtained sequences were submitted to GenBank database under accession numbers ON909086, ON909087 and ON909088 of 28S rDNA D2-D3 segments, and ON909123, ON909124 and ON909125 of ITS region. The resulting 28S rDNA D2-D3 segment sequences were 100% identical to KJ461565 and the BLASTn search of the ITS region sequences was most similar to T. zeae (KJ461599), which is the species isolated from corn in Spain. The identities of ITS region sequences on these populations were 99.89% (893/894), with no insertions/deletions. The phylogenetic relationships of the population strongly support T. zeae (Fig. S2). Phylogenetic relation analysis based on the two genes was constructed using PAUP version 4.0 and MrBayes 3.1.2 programs. To confirm pathogenicity, a modified version of Koch's postulates was conducted in the greenhouse by inoculating 100 females and males onto each of five pots of seedling corn (cv. Daehakchal) filled with the sterilized sandy soil and maintained for 60 days at 25℃ under the conditions. Tylenchorhynchus zeae reproduction factor was 2.21 ± 0.37 was observed at the end of the trial in soil on pots. The stunted and swollen roots and dwarfed and yellowing leaf shoots symptoms in the greenhouse pots trial were confirmed the same as those typical damage symptoms. To the best of our knowledge, this is the first report of T. zeae in Republic of Korea. The host range of T. zeae includes some economic crops such as cabbage, cauliflower, grapevine, and olive (Chen at al., 2007; Handoo et al., 2014). It is necessary to investigate the damage to economic crops in the Republic of Korea to this nematode.

Reducing CNOT count in quantum Fourier transform for the linear nearest-neighbor architecture.

Physical limitations of quantum hardware often necessitate nearest-neighbor (NN) architecture. When synthesizing quantum circuits using the basic gate library, which consists of CNOT and single-qubit gates, CNOT gates are required to convert a quantum circuit into one suitable for an NN architecture. In the basic gate library, CNOT gates are considered the primary cost of quantum circuits due to their higher error rates and longer execution times compared to single-qubit gates. In this paper, we propose a new linear NN (LNN) circuit design for quantum Fourier transform (QFT), one of the most versatile subroutines in quantum algorithms. Our LNN QFT circuit has only about 40% of the number of CNOT gates compared to previously known LNN QFT circuits. Subsequently, we input both our QFT circuits and conventional QFT circuits into the Qiskit transpiler to construct QFTs on IBM quantum computers, which necessitate NN architectures. Consequently, our QFT circuits demonstrate a substantial advantage over conventional QFT circuits in terms of the number of CNOT gates. This outcome implies that the proposed LNN QFT circuit design could serve as a novel foundation for developing QFT circuits implemented in quantum hardware that demands NN architecture.

Microplastics in large marine animals stranded in the Republic of Korea.

Microplastics (MPs) are found in every ocean and are frequently ingested by marine animals. This study analyzed MPs in the stomachs and intestines of 12 large marine animals comprising one fin whale (Balaenoptera physalus), seven finless porpoises (Neophocaena asiaeorientalis), two loggerhead turtles (Caretta caretta), one Indo-Pacific bottlenose dolphin (Tursiops aduncus), and one common dolphin (Delphinus delphis) that were stranded off the Republic of Korea between 2019 and 2021. MPs were detected with a mean abundance of 3.42 ± 3.2 items/g and were predominantly of transparent-white, fragment-shaped polypropylene smaller than 200 µm. The abundance of MPs found did not correlate with the biological information (maturity, body length) of the finless porpoises and there were no significant differences in the abundance of MPs between the stomachs and intestines. These results cannot accurately assess the impact of MPs on large marine animals, so further studies are necessary to understand how MPs can potentially affect them.

Possible link between derelict fishing gear and sea turtle strandings in coastal areas.

Ghost fishing via a derelict fishing gear (DFG) is a critical threat to marine organisms. To explore the effect of DFG on sea turtle strandings, the DFG distribution was compared at two sites on Jeju Island (South Korea) with a contrasting number of strandings. Coastal areas in northern Jeju Island were surveyed during dives with scuba equipment, and the DFG from two sites, Gwideok-ri and Sinchang-ri was collected and compared in terms of quantity and size of the items. Fishing line was more common, longer, and thicker in Gwideok-ri than in Sinchang-ri, while other types of DFG did not differ between the two sites. In addition, necropsies on two loggerhead sea turtles discovered on Jeju Island found fishing lines with fishing hooks in the oral cavity of both carcasses. This suggests that derelict recreational fishing lines may pose a significant threat to sea turtles in coastal areas.

Characterization of Heterodera sojae Virulence Phenotypes in Korea.

The white soybean cyst nematode Heterodera sojae, isolated from the roots of soybean in Korea, is widespread in most provinces of the country and has the potential to be as harmful to soybean as H. glycines. Determining the virulence phenotypes of H. sojae is essential to devising management strategies that use resistant cultivars. Consequently, virulence phenotypes of 15 H. sojae populations from Korea were determined on seven soybean lines and one susceptible check variety. Two different HS types were found to be present in Korea; the more common HS type 2.5.7, comprising 73.3% of the H. sojae populations and the less common HS type 0, constituting only 26.7% of the tested populations. Considering the high frequency of H. sojae adaptation to soybean indicator lines, the PI 88788 group may not be a possible source of resistance while PI 548402, PI 90763, PI 437654, and PI 89772 can be used as resistance sources for soybean breeding programs aimed at developing H. sojae-resistant soybean cultivars in Korea.

First Report of Pratylenchoides leiocauda parasitic on Perilla frutescenes in the Republic of Korea.

Perilla (Perilla frutescens (L.) Britton var. japonica) is an annual herbaceous crop belonging to Lamiaceae. It is one of the most important crops in Korea. A survey of plant parasitic nematodes was carried out in 70 perilla fields in Geumsan and Miryang, Korea in 2020. Migratory endo-parasitic nematodes were extracted from the perilla roots using modified root incubation methods (Mountain and Patrick, 1959). False root-lesion nematodes (Pratylenchoides) were recovered from 41.4% of the fields. They were identified using morphological and molecular analyses. Among the Pratylenchoides species, Pratylenchoides leiocauda was described in France from soil around non-identified grass and weeds. P. leiocauda is reported to weaken the root systems of tomato, potato and strawberry (Sher, 1970; Li et al., 2020). The morphological characteristics of males and females from the 2020 survey were very similar to P. leiocauda. The lateral field contained six incisures and the pharyngeal glands overlapped the intestine dorsally for 1-2 times the body width. Additionally, they had a second nucleus near the pharyngeal intestine valve, female tails with incisures, and a smooth conical tail with 18-23 annules. Measurements and micrographs with the light-microscope (DM5000, Leica, Germany) and camera (DFC450, Leica, Germany) were taken from females (n=23) for mean, standard deviation and range of body length: 824.5 ± 71.0 (657.7-993.8) µm, maximum body width: 28.4 ± 2.7 (24.8-36.2) µm, stylet length: 22.8 ± 0.7 (21.4-24.0) µm and percent of distance from anterior end to vulva / body length: 57.7 ± 1.4 (54.0-60.3). Males (n=5) were characterized by a body length: 653.5 ± 64.3 (555.3-714.7) µm, a stylet length: 20.9 ± 1.0 (19.7-22.0) µm and a spicule length: 26.1 ± 2.5 (22.3-28.5) µm. Morphological measurements and characteristics (Fig. 1A-F) were compared to previous descriptions of P. leiocauda. As a result, the Korean population was larger than that of the originally described population from France, and was more similar to the Chinese population (Sher, 1970; Azizi et al., 2016; Li et al., 2020). In addition, PCR was performed for the COⅠ, LSU rRNA D2-D3 and ITS region using the primers (Mwesige et al., 2020). The sequenced COⅠ, LSU rRNA D2-D3 segments and ITS region are 447, 776 and 777 bp, respectively. The newly obtained sequences were submitted to GenBank database under accession numbers MZ418130, MZ414163 and MZ418133 of ITS region. A BLASTn search of the LSU rRNA D2-D3 sequence was most similar to P. leiocauda (MN539650), which is the species isolated from tomato in China (Li et al., 2020). The identities of these two sequences were 99.9% (775/776), with no insertions/deletions. The phylogenetic relationships strongly support P. leiocauda (Fig. 1G). Symptoms of perilla associated with P. leiocauda under field conditions included small and curled leaves, chlorosis of leaf edges, dark brown root epidermis and root necrosis (Fig. 2A, B). Koch's postulates were completed by inoculating 100 P. leiocauda into ten 45-cm-in-diameter pots filled with sterilized sandy loam soil and planted with perilla cultivar 'Ipdeulkkae 1-ho'. The potted plants were maintained for 50 days at 25℃ under greenhouse conditions. A P. leiocauda reproduction factor was 1.45 ± 0.20 was observed at the end of the trial, with 106 ± 21.6 recovered from soil and 39 ± 6.7 from root tissue. The root and shoot symptoms in the greenhouse trial were the same as those observed under field conditions (Fig. 2C, D). This, therefore, is the first record of P. leiocauda associated with perilla in Korea and management is warranted.

Genetic marker gene, recQ, differentiating Bacillus subtilis and the closely related Bacillus species.

RecQ, which encodes a DNA helicase, was selected in searching for a marker gene of Bacillus subtilis and related species via genome mining. RecQ gene sequence similarity of type strains among Bacillus species used in this study ranged from 66.2% to 96.6%, whereas orthologous average nucleotide identity ranged from 72.6% to 95.8%. According to the phylogenetic tree based on recQ sequences, each type strain of all Bacillus species or subspecies used in this study was placed in a unique taxonomic position. Four B. subtilis subspecies, Bacillus tequilensis and Bacillus vallismortis were grouped in one cluster (cluster A). Strains of B. subtilis subsp. subtilis were classified into A1 cluster, and divided into subgroups. Isolates from Natto, Japanese fermented bean food, were classified into one subgroup, whereas those from Cheonggukjang, Korean fermented bean food, were divided into several subgroups within A1. Type strains of Bacillus halotolerans and Bacillus mojavensis were grouped into another cluster (cluster B), related to cluster A. Bacillus siamensis, Bacillus velezensis and Bacillus amyloliquefaciens were grouped into an independent cluster (cluster E). Sequencing of recQ was useful for the classification or differentiation of B. subtilis and closely related species. Therefore, recQ gene can be applied to the classification of these taxa.

Short-Term Effects of Low-Level Heavy Metal Contamination on Soil Health Analyzed by Nematode Community Structure.

The short-term effects of low-level contamination by heavy metals (As, Cd, Cu, and Pb) on the soil health were examined by analyzing soil nematode community in soils planted with tomatoes. For this, the soils were irrigated with five metal concentrations ([1, 1/4, 1/4(2), 1/4(3), and 0] × maximum concentrations [MC] detected in irrigation waters near abandoned mine sites) for 18 weeks. Heavy metal concentrations were significantly increased in soils irrigated with MC of heavy metals, among which As and Cu exceeded the maximum heavy metal residue contents of soil approved in Korea. In no heavy metal treatment controls, nematode abundances for all trophic groups (except omnivorous-predatory nematodes [OP]) and colonizer-persister (cp) values (except cp-4-5) were significantly increased, and all maturity indices (except maturity index [MI] of plant-parasitic nematodes) and structure index (SI) were significantly decreased, suggesting the soil environments might have been disturbed during 18 weeks of tomato growth. There were no concentration-dependent significant decreases in richness, abundance, or MI for most heavy metals; however, their significant decreases occurred in abundance and richness of OP and cp-4, MI2-5 (excluding cp-1) and SI, indicating disturbed soil ecosystems, at the higher concentrations (MC and MC/4) of Pb that had the most significant negative correlation coefficients for heavy metal concentrations and nematode community among the heavy metals. Therefore, the short-term effects of low-level heavy metal contamination on soil health can be analyzed by nematode community structures before the appearance of plant damages caused by the abiotic agents, heavy metals.