Clinically approved antiviral drugs are currently available for only 10 of the more than 220 viruses known to infect humans. The SARS-CoV-2 outbreak has exposed the critical need for compounds that ...can be rapidly mobilised for the treatment of re-emerging or emerging viral diseases, while vaccine development is underway. We review the current status of antiviral therapies focusing on RNA viruses, highlighting strategies for antiviral drug discovery and discuss the challenges, solutions and options to accelerate drug discovery efforts.
Emerging viral diseases, most of which are zoonotic, pose a significant threat to global health. There is a critical need to identify potential new viral pathogens and the challenge is to identify ...the reservoirs from which these viruses might emerge. Deep sequencing of invertebrate transcriptomes has revealed a plethora of viruses, many of which represent novel lineages representing both plant and animal viruses and little is known about the potential threat that these viruses pose.
Providence virus, an insect virus, was used to establish a productive infection in Vigna unguiculata (cowpea) plants. Providence virus particles purified from these cowpea plants were used to infect two mammalian cell lines.
Here, we present evidence that Providence virus, a non-enveloped insect RNA virus, isolated from a lepidopteran midgut cell line can establish a productive infection in plants as well as in animal cells. The observation that Providence virus can readily infect both plants and mammalian cell culture lines demonstrates the ability of an insect RNA virus to establish productive infections across two kingdoms, in plants and invertebrate and vertebrate animal cell lines.
The study highlights the potential of phytophagous insects as reservoirs for viral re-assortment and that plants should be considered as reservoirs for emerging viruses that may be potentially pathogenic to humans.
Pyrroloiminoquinones are a group of cytotoxic alkaloids most commonly isolated from marine sponges. Structurally, they are based on a tricyclic pyrrolo4,3,2-dequinoline core and encompass marine ...natural products such as makaluvamines, tsitsikammamines and discorhabdins. These diverse compounds are known to exhibit a broad spectrum of biological activities including anticancer, antiplasmodial, antimicrobial, antifungal and antiviral activities as well as the inhibition of several key cellular enzymes. The resurgence of interest in pyrroloiminoquinones and the convoluted understanding regarding their biological activities have prompted this review. Herein, we provided a concise summary of key findings and recent developments pertaining to their structural diversity, distribution, biogenesis, and their potential as chemical probes for drug development, including a discussion of promising synthetic analogs.
Mesoscale variability and associated eddy fluxes play crucial roles in ocean circulation dynamics and the ecology of the upper ocean. In doing so, these features are biologically important, providing ...a mechanism for the mixing and exchange of nutrients and biota within the ocean. Transient mesoscale eddies in the Southern Ocean are known to relocate zooplankton communities across the Antarctic Circumpolar Current (ACC) and are important foraging grounds for marine top predators. In this study we investigated the role of cyclonic and anti-cyclonic eddies formed at the South-West Indian Ridge on the spatial variability and diversity of microbial communities. We focused on two contrasting adjacent eddies within the Antarctic Polar Frontal Zone to determine how these features may influence the microbial communities within this region. The water masses and microbiota of the two eddies, representative of a cyclonic cold core from the Antarctic zone and an anti-cyclonic warm-core from the Subantarctic zone, were compared. The data reveal that the two eddies entrain distinct microbial communities from their points of origin that are maintained for up to ten months. Our findings highlight the ecological impact that changes, brought by the translocation of eddies across the ACC, have on microbial diversity.
Lithified layers of complex microbial mats known as microbialites are ubiquitous in the fossil record, and modern forms are increasingly identified globally. A key challenge to developing an ...understanding of microbialite formation and environmental role is how to investigate complex and diverse communities in situ. We selected living, layered microbialites (stromatolites) in a peritidal environment near Schoenmakerskop, Eastern Cape, South Africa to conduct a spatial survey mapping the composition and small molecule production of the microbial communities from environmental samples. Substrate core samples were collected from nine sampling stations ranging from the upper point of the freshwater inflow to the lower marine interface where tidal overtopping takes place. Substrate cores provided material for parallel analyses of microbial community diversity by 16S rRNA gene amplicon sequencing and metabolomics using LC-MS2. Species and metabolite diversities were correlated, and prominent specialized metabolites were targeted for preliminary characterization. A new series of cyclic hexadepsipeptides, named ibhayipeptolides, was most abundant in substrate cores of submerged microbialites. These results demonstrate the detection and identification of metabolites from mass-limited environmental samples and contribute knowledge about microbialite chemistry and biology, which facilitates future targeted studies of specialized metabolite function and biosynthesis.
The fossil record indicates that the earliest evidence of extant marine sponges (phylum Porifera) existed during the Cambrian explosion and that their symbiosis with microbes may have begun in their ...extinct ancestors during the Precambrian period. Many symbionts have adapted to their sponge host, where they perform specific, specialized functions. There are also widely distributed bacterial taxa such as
,
, and
that are found in a broad range of invertebrate hosts. Here, we added 11 new genomes to the
order, identified a novel family, and show that functional potential differs between the three
families. We compare the
with the well-characterized
and show that these symbionts appear to preferentially associate with low-microbial abundance (LMA) and high-microbial abundance (HMA) sponges, respectively. Within these sponges, we show that these symbionts likely perform distinct functions and may have undergone multiple association events, rather than a single association event followed by coevolution.
Marine sponges often form symbiotic relationships with bacteria that fulfil a specific need within the sponge holobiont, and these symbionts are often conserved within a narrow range of related taxa. To date, there exist only three known bacterial taxa (
,
, and
) that are globally distributed and found in a broad range of sponge hosts, and little is known about the latter two. We show that the functional potential of broad-host range symbionts is conserved at a family level and that these symbionts have been acquired several times over evolutionary history. Finally, it appears that the
are associated primarily with high-microbial abundance sponges, while the
associate with low-microbial abundance sponges.
While anthropogenic pollution is a major threat to aquatic ecosystem health, our knowledge of the presence of xenobiotics in coastal Dissolved Organic Matter (DOM) is still relatively poor. This is ...especially true for water bodies in the Global South with limited information gained mostly from targeted studies that rely on comparison with authentic standards. In recent years, non-targeted tandem mass spectrometry has emerged as a powerful tool to collectively detect and identify pollutants and biogenic DOM components in the environment, but this approach has yet to be widely utilized for monitoring ecologically important aquatic systems. In this study we compared the DOM composition of Algoa Bay, Eastern Cape, South Africa, and its two estuaries. The Swartkops Estuary is highly urbanized and severely impacted by anthropogenic pollution, while the Sundays Estuary is impacted by commercial agriculture in its catchment. We employed solid-phase extraction followed by liquid chromatography tandem mass spectrometry to annotate more than 200 pharmaceuticals, pesticides, urban xenobiotics, and natural products based on spectral matching. The identification with authentic standards confirmed the presence of methamphetamine, carbamazepine, sulfamethoxazole, N-acetylsulfamethoxazole, imazapyr, caffeine and hexa(methoxymethyl)melamine, and allowed semi-quantitative estimations for annotated xenobiotics. The Swartkops Estuary DOM composition was strongly impacted by features annotated as urban pollutants including pharmaceuticals such as melamines and antiretrovirals. By contrast, the Sundays Estuary exhibited significant enrichment of molecules annotated as agrochemicals widely used in the citrus farming industry, with predicted concentrations for some of them exceeding predicted no-effect concentrations. This study provides new insight into anthropogenic impact on the Algoa Bay system and demonstrates the utility of non-targeted tandem mass spectrometry as a sensitive tool for assessing the health of ecologically important coastal ecosystems and will serve as a valuable foundation for strategizing long-term monitoring efforts.
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•Non-targeted liquid chromatography tandem mass spectrometry was used to investigate anthropogenic impacts in an ecologically important coastal ecosystem.•More than 200 small molecules were annotated in DOM from Algoa Bay, South Africa, and its estuaries.•Commercial fungicides were putatively identified in the agriculturally impacted Sundays Estuary and their predicted concentrations warrant concern.•Hexa(methoxymethyl)melamine levels in Swartkops Estuary exceed predicted no-effect concentrations, and likely so do the levels of the putatively identified antiviral drug lopinavir.•This study demonstrates the potential of non-targeted metabolomics to assess and monitor anthropogenic impacts in coastal systems.
The Southern Ocean accounts for ∼30% of the ocean's CO2 sink, partly due to its biological pump that transfers surface‐produced organic carbon to deeper waters. To estimate large‐scale Southern Ocean ...carbon export potential and characterize its drivers, we measured the carbon and nitrogen isotope ratios of surface suspended particulate matter (δ13CSPM, δ15NSPM) for samples collected in summer 2016/2017 during the Antarctic Circumnavigation Expedition (364 stations). Concurrent measurements of phytoplankton community composition revealed the dominance of large diatoms in the Antarctic and nano‐phytoplankton (mainly haptophytes) in open Subantarctic waters. As expected, δ13CSPM was strongly dependent on pCO2, with local deviations in this relationship explained by phytoplankton community dynamics. δ15NSPM reflected the nitrogen sources consumed by phytoplankton, with higher inferred nitrate (versus recycled ammonium) dependence generally coinciding with higher micro‐phytoplankton abundances. Using δ15NSPM and a two‐endmember isotope mixing model, we quantified the extent of nitrate‐ versus ammonium‐supported growth, which yields a measure of carbon export potential. We estimate that across the Southern Ocean, 41 ± 29% of the surface‐produced organic carbon was potentially exported below the seasonal mixed layer during the growth season, with maximum export potential (50%–99%) occurring in the Antarctic Circumpolar Current's southern Boundary Zone and near the (Sub)Antarctic islands, reaching a minimum in the Subtropical Zone (<33%). Alongside iron, phytoplankton community composition emerged as an important driver of the Southern Ocean's biological pump, with large diatoms dominating regions characterized by high nitrate dependence and elevated carbon export potential and smaller, mainly non‐diatom taxa proliferating in waters where recycled ammonium supported most productivity.
Plain Language Summary
The Southern Ocean plays a crucial role in regulating climate by transferring atmospheric CO2 to the deep ocean. This transfer is partly facilitated by the biological pump, which involves organic matter production by phytoplankton in surface waters and the subsequent sinking of some of this material into the deep ocean. To estimate the fraction of newly produced organic carbon potentially exported to depth (i.e., biological pump strength) and determine the drivers thereof, we measured the carbon and nitrogen isotope ratios of surface organic matter and characterized the phytoplankton community at high resolution around Antarctica in summer. We found that nearly half of the carbon produced by Southern Ocean phytoplankton during their growth season was potentially exported. The biological pump was strongest in the southernmost waters of the Antarctic Ocean and near the (Sub)Antarctic islands where local processes supplied iron to phytoplankton and large diatoms dominated the community. Export potential was weakest in open Southern Ocean waters where iron limitation was pervasive and smaller phytoplankton were dominant. While it is well known that iron exerts a strong control on the Southern Ocean's biological pump, our study highlights the complementary role of phytoplankton community composition in modulating carbon export.
Key Points
Phytoplankton community composition influences suspended particulate matter carbon and nitrogen isotope ratios across the Southern Ocean
The nitrogen isotopes of particulate matter and a two‐endmember isotope mixing model can be used to estimate carbon export potential
40% of summertime primary production is potentially exported, with a higher fraction exported near (Sub)Antarctic islands and melting ice
Sponges of the Latrunculiidae family produce bioactive pyrroloiminoquinone alkaloids including makaluvamines, discorhabdins, and tsitsikammamines. The aim of this study was to use LC-ESI-MS/MS-driven ...molecular networking to characterize the pyrroloiminoquinone secondary metabolites produced by six latrunculid species. These are
,
,
and
as well as the recently discovered species,
and
. Organic extracts of 43 sponges were analyzed, revealing distinct species-specific chemical profiles. More than 200 known and unknown putative pyrroloiminoquinones and related compounds were detected, including unprecedented makaluvamine-discorhabdin adducts and hydroxylated discorhabdin I derivatives. The chemical profiles of the new species
closely resembled those of the known
(chemotype I), but with a higher abundance of tsitsikammamines vs. discorhabdins.
sponges displayed two distinct chemical profiles, either producing mostly the same discorhabdins as
(chemotype I) or non- or monobrominated, hydroxylated discorhabdins.
and
produced similar pyrroloiminoquinone chemistry to one another, characterized by sulfur-containing discorhabdins and related adducts and oligomers. This study highlights the variability of pyrroloiminoquinone production by latrunculid species, identifies novel isolation targets, and offers fundamental insights into the collision-induced dissociation of pyrroloiminoquinones.
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