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Asperchalasine A (1), the first cytochalasan dimer featuring a unique decacyclic 5/6/11/5/5/6/5/11/6/5 ring system consisting of 20 chiral centers, was isolated from the culture broth of Aspergillus flavipes. Three biogenetically related intermediates, asperchalasines B-D (2-4), were also isolated. Their structures, including their absolute configurations, were elucidated using a combination of HRESIMS, NMR, ECD, molecular modeling, and single-crystal X-ray diffraction techniques. Compound 1, which possesses an unprecedented 13-oxatetracyclo[7.2.1.1(2,5).0(1,6)]tridec-8,12-dione core structure, is the first example of a dimeric cytochalasan alkaloid. The biogenetic pathways of 1-4 were described starting from the co-isolated compounds 5 and 6. More importantly, 1 induced significant G1-phase cell cycle arrest by selectively inhibiting cyclin A, CDK2 and CDK6 in cancerous, but not normal, cells, highlighting it as a potentially selective cell cycle regulator against cancer cells.

Hadal biosphere represents the deepest part of the ocean with water depth >6,000 m. Accumulating evidence suggests the existence of unique microbial communities dominated by heterotrophic processes in this environment. However, investigations of the microbial diversity and their metabolic potentials are limited because of technical constraints for sample collection. Here, we provide a detailed metagenomic analysis of three seawater samples at water depths 5,000–6,000 m below sea level (mbsl) and three surface sediment samples at water depths 4,435–6,578 mbsl at the Yap Trench of the western Pacific. Distinct microbial community compositions were observed with the dominance of Gammaproteobacteria in seawater and Thaumarchaeota in surface sediment. Comparative analysis of the genes involved in carbon, nitrogen and sulfur metabolisms revealed that heterotrophic processes (i.e., degradation of carbohydrates, hydrocarbons, and aromatics) are the most common microbial metabolisms in the seawater, while chemolithoautotrophic metabolisms such as ammonia oxidation with the HP/HB cycle for CO2 fixation probably dominated the surface sediment communities of the Yap Trench. Furthermore, abundant genes involved in stress response and metal resistance were both detected in the seawater and sediments, thus the enrichment of metal resistance genes is further hypothesized to be characteristic of the hadal microbial communities. Overall, this study sheds light on the metabolic versatility of microorganisms in the Yap Trench, their roles in carbon, nitrogen, and sulfur biogeochemical cycles, and how they have adapted to this unique hadal environment.

Knowledge about the presence and ecological significance of bacteria and archaea in the deep-sea environments has been well recognized, but the eukaryotic microorganisms, such as fungi, have rarely been reported. The present study investigated the composition and abundance of fungal community in the deep-sea sediments of the Pacific Ocean. In this study, a total of 1,947 internal transcribed spacer (ITS) regions of fungal rRNA gene clones were recovered from five sediment samples at the Pacific Ocean (water depths ranging from 5,017 to 6,986 m) using three different PCR primer sets. There were 16, 17, and 15 different operational taxonomic units (OTUs) identified from fungal-universal, Ascomycota-, and Basidiomycota-specific clone libraries, respectively. Majority of the recovered sequences belonged to diverse phylotypes of Ascomycota (25 phylotypes) and Basidiomycota (18 phylotypes). The multiple primer approach totally recovered 27 phylotypes which showed low similarities (≤97 %) with available fungal sequences in the GenBank, suggesting possible new fungal taxa occurring in the deep-sea environments or belonging to taxa not represented in the GenBank. Our results also recovered high fungal LSU rRNA gene copy numbers (3.52 × 10(6) to 5.23 × 10(7)copies/g wet sediment) from the Pacific Ocean sediment samples, suggesting that the fungi might be involved in important ecological functions in the deep-sea environments.

Hydrothermal vents release reduced compounds and small organic carbon compounds into the surrounding seawater, providing essential substrates for microbial growth and bioenergy transformations. Despite the wide distribution of the marine benthic group E archaea (referred to as Hydrothermarchaeota) in the hydrothermal environment, little is known about their genomic repertoires and biogeochemical significance. Here, we studied four highly complete (Ͼ80%) metagenomeassembled genomes (MAGs) from a black smoker chimney and the surrounding sulfur-rich sediments on the South Atlantic Mid-Ocean Ridge and publicly available data sets (the Integrated Microbial Genomes system of the U.S. Department of Energy-Joint Genome Institute and NCBI SRA data sets). Genomic analysis suggested a wide carbon metabolic diversity of Hydrothermarchaeota members, including the utilization of proteins, lactate, and acetate; the anaerobic degradation of aromatics; the oxidation of C 1 compounds (CO, formate, and formaldehyde); the utilization of methyl compounds; CO 2 incorporation by the tetrahydromethanopterin-based Wood-Ljungdahl pathway; and participation in the type III ribulose-1,5-bisphosphate carboxylase/oxygenase-based Calvin-Benson-Bassham cycle. These microbes also potentially oxidize sulfur, arsenic, and hydrogen and engage in anaerobic respiration based on sulfate reduction and denitrification. Among the 140 MAGs reconstructed from the black smoker chimney microbial community (including Hydrothermarchaeota MAGs), community-level metabolic predictions suggested a redundancy of carbon utilization and element cycling functions and interactive syntrophic and sequential utilization of substrates. These processes might make various carbon and energy sources widely accessible to the microorganisms. Further, the analysis suggested that Hydrothermarchaeota members contained important functional components obtained from the community via lateral gene transfer, becoming a distinctive clade. This might serve as a niche-adaptive strategy for metabolizing heavy metals, C 1 compounds, and reduced sulfur compounds. Collectively, the analysis provides comprehensive metabolic insights into the Hydrothermarchaeota. IMPORTANCE This study provides comprehensive metabolic insights into the Hydrothermarchaeota from comparative genomics, evolution, and community-level perspectives. Members of the Hydrothermarchaeota synergistically participate in a wide range of carbon-utilizing and element cycling processes with other microorganisms in the community. We expand the current understanding of community interactions within the hydrothermal sediment and chimney, suggesting that microbial interactions based on sequential substrate metabolism are essential to nutrient and element cycling.

Seven new alkaloids, N-methylhaemanthidine chloride (1), N-methyl-5,6-dihydroplicane (5), O-methylnerinine (6), N-ethoxycarbonylethylcrinasiadine (7), N-ethoxycarbonylpropylcrinasiadine (8), N-phenethylcrinasiadine (9) and N-isopentylcrinasiadine (10), together with eight known alkaloids, haemanthamin (2), 3-epimacronine (3), (+)-tazettine (4), N-methylcrinasiadine (11), trisphaeridine (12), 5,6-dihydrobicolorine (13), lycorine (14), and nigragillin (15), were isolated from the whole plants of Zephyranthes candida. The structures of the new compounds were established by spectroscopic data interpretation, with single-crystal X-ray diffraction analysis performed on 1. The absolute configuration of 3-epimacronine (3) was determined by single-crystal X-ray diffraction analysis with CuKα irradiation. Compounds 1–15 were evaluated for their in vitro cytotoxicity against five human cancer cell lines and the Beas-2B immortalized (non-cancerous) human bronchial epithelial cell line. Compounds 1, 2, 9, and 14 exhibited cytotoxicity with IC50 values ranging from 0.81 to 13 μM with selectivity indices as high as 10 when compared to the Beas-2B cell line.

Asperflavipines A (1) and B (2), two structurally complex merocytochalasans, were isolated from Aspergillus flavipes. Asperflavipine A (1), which contains two cytochalasan moieties and two epicoccine moieties, is the first cytochalasan heterotetramer to be discovered. It is uniquely defined by 5/6/11/5/6/5/6/5/6/5/5/11/6/5 fused tetradecacyclic rings with three continuous bridged ring systems. Asperflavipine B (2) is a cytochalasan heterotrimer containing a cytochalasan and two epicoccine moieties with a 5/6/11/5/5/6/5/6/5 nonacyclic ring system. The hypothetical biosynthesis of 1 and 2 is proposed to involve Diels-Alder and [3+2] cycloaddition reactions as key steps and reveals unparalleled plasticity in the biosynthesis of merocytochalasans. The existence of 1 adds a new dimension to the diversity of the cytochalasan family. Compound 1 showed moderate cytotoxicity and induced apoptosis in Jurkat, NB4, and HL60 cells through the activation of caspase-3 and degradation of poly(ADP-ribose) polymerase (PARP).

Two new functionalized ergostane-type steroids, phomopsterones A (1) and B (2), were isolated from the plant-derived Phomopsis sp. TJ507A. Their structures were determined on the basis of spectroscopic data, a modified Mosher's method, X-ray crystallographic analysis, and quantum chemical calculations. Compound 1 is an unprecedented ergosteroid featuring a rearranged bicyclo[3.3.1]nonane motif resulting from B-ring scission and a subsequent 180° rotation of the ring A during biosynthesis. Compound 2 exhibited anti-inflammatory activity.