Cyanogenesis in the Sorghum Genus: From Genotype to Phenotype

Domestication has resulted in a loss of genetic diversity in our major food crops, leading to susceptibility to biotic and abiotic stresses linked with climate change. Crop wild relatives (CWR) may provide a source of novel genes potentially important for re-gaining climate resilience. Sorghum bicolor is an important cereal crop with wild relatives that are endemic to Australia. Sorghum bicolor is cyanogenic, but the cyanogenic status of wild Sorghum species is not well known. In this study, leaves of wild species endemic in Australia are screened for the presence of the cyanogenic glucoside dhurrin. The direct measurement of dhurrin content and the potential for dhurrin-derived HCN release (HCNp) showed that all the tested Australian wild species were essentially phenotypically acyanogenic. The unexpected low dhurrin content may reflect the variable and generally nutrient-poor environments in which they are growing in nature. Genome sequencing of six CWR and PCR amplification of the CYP79A1 gene from additional species showed that a high conservation of key amino acids is required for correct protein function and dhurrin synthesis, pointing to the transcriptional regulation of the cyanogenic phenotype in wild sorghum as previously shown in elite sorghum.

Structural Biology Illuminates Molecular Determinants of Broad Ebolavirus Neutralization by Human Antibodies for Pan-Ebolavirus Therapeutic Development

Monoclonal antibodies (mAbs) have proven effective for the treatment of ebolavirus infection in humans, with two mAb-based drugs Inmazeb™ and Ebanga™ receiving FDA approval in 2020. While these drugs represent a major advance in the field of filoviral therapeutics, they are composed of antibodies with single-species specificity for Zaire ebolavirus. The Ebolavirus genus includes five additional species, two of which, Bundibugyo ebolavirus and Sudan ebolavirus, have caused severe disease and significant outbreaks in the past. There are several recently identified broadly neutralizing ebolavirus antibodies, including some in the clinical development pipeline, that have demonstrated broad protection in preclinical studies. In this review, we describe how structural biology has illuminated the molecular basis of broad ebolavirus neutralization, including details of common antigenic sites of vulnerability on the glycoprotein surface. We begin with a discussion outlining the history of monoclonal antibody therapeutics for ebolaviruses, with an emphasis on how structural biology has contributed to these efforts. Next, we highlight key structural studies that have advanced our understanding of ebolavirus glycoprotein structures and mechanisms of antibody-mediated neutralization. Finally, we offer examples of how structural biology has contributed to advances in anti-viral medicines and discuss what opportunities the future holds, including rationally designed next-generation therapeutics with increased potency, breadth, and specificity against ebolaviruses.

Interspecific Analysis of Sea Urchin Adhesive Composition Emphasizes Variability of Glycans Conjugated With Putative Adhesive Proteins

Sea urchins possess specialized adhesive organs, tube feet. Although initially believed to function as suckers, it is currently accepted that they rely on adhesive and de-adhesive secretions to attach and detach repeatedly from the substrate. Given the biotechnological potential of their strong reversible adhesive, sea urchins are under investigation to identify the protein and glycan molecules responsible for its surface coupling, cohesion and polymerization properties. However, this characterization has only focused on a single species, Paracentrotus lividus. To provide a broader insight into sea urchins adhesion, a comparative study was performed using four species belonging to different taxa and habitats: Diadema africanum, Arbacia lixula, Paracentrotus lividus and Sphaerechinus granularis. Their tube feet external morphology and histology was studied, together with the ultrastructure of their adhesive secretory granules. In addition, one antibody and five lectins were used on tube foot histological sections and extracts, and on adhesive footprints to detect the presence of adhesion-related (glyco)proteins like those present in P. lividus in other species. Results confirmed that the antibody raised against P. lividus Nectin labels the adhesive organs and footprints in all species. This result was further confirmed by a bioinformatic analysis of Nectin-like sequences in ten additional species, increasing the comparison to seven families and three orders. The five tested lectins (GSL II, WGA, STL, LEL, and SBA) demonstrated that there is high interspecific variability of the glycans involved in sea urchin adhesion. However, there seems to be more conservation among taxonomically closer species, like P. lividus and S. granularis. In these species, lectin histochemistry and lectin blots indicated the presence of high molecular weight putative adhesive glycoproteins bearing N-acetylglucosamine residues in the form of chitobiose in the adhesive epidermis and footprints. Our results emphasize a high selective pressure for conservation of functional domains in large putative cohesive proteins and highlight the importance of glycosylation in sea urchin adhesion with indications of taxonomy-related conservation of the conjugated glycans.

Rediscovering the dancing semislug genus Cryptosemelus Collinge, 1902 (Eupulmonata, Ariophantidae) from Thailand with description of two new species

Knowledge of Thai semislugs remains scarce, especially the dancing semislug genus Cryptosemelus. Prior to the present study, only a single species has been recognized with little available information. To address this knowledge gap, we surveyed for semislugs in western and southern Thailand, which yielded three species belonging to the genus Cryptosemelus. The little-known type species C. gracilis is redescribed herein, including a comparison with the type specimens. Two additional species, C. betarmonsp. nov. and C. tigrinussp. nov., are described as new to science. All three species are characterized by differences in their genital anatomy, especially with respect to anatomical details of the penis, epiphallus, and spermatophore. In addition, C. tigrinussp. nov. differs from C. gracilis and C. betarmonsp. nov. in the mantle color pattern.

Community similarity and species overlap between habitats provide insight into the deep reef refuge hypothesis

The deep reef refuge hypothesis (DRRH) postulates that mesophotic coral ecosystems (MCEs) may provide a refuge for shallow coral reefs (SCRs). Understanding this process is an important conservation tool given increasing threats to coral reefs. To establish a better framework to analyze the DRRH, we analyzed stony coral communities in American Sāmoa across MCEs and SCRs to describe the community similarity and species overlap to test the foundational assumption of the DRRH. We suggest a different approach to determine species as depth specialists or generalists that changes the conceptual role of MCEs and emphasizes their importance in conservation planning regardless of their role as a refuge or not. This further encourages a reconsideration of a broader framework for the DRRH. We found 12 species of corals exclusively on MCEs and 183 exclusively on SCRs with another 63 species overlapping between depth zones. Of these, 19 appear to have the greatest potential to serve as reseeding species. Two additional species are listed under the U.S. Endangered Species Act, Acropora speciosa and Fimbriaphyllia paradivisa categorized as an occasional deep specialist and a deep exclusive species, respectively. Based on the community distinctiveness and minimal species overlap of SCR and MCE communities, we propose a broader framework by evaluating species overlap across coral reef habitats. This provides an opportunity to consider the opposite of the DRRH where SCRs support MCEs.

Acanthurus mata (Cuvier, 1829), Elongate Surgeonfish (Acanthuridae), newly recorded in the Tropical Eastern Pacifi

The reef-fish fauna of the Tropical Eastern Pacific (TEP) includes 12 species of surgeonfishes (Acanthuridae), five of them in the genus Acanthurus. Recent recreational scuba diving at Isla Darwin in the Galapagos archipelago produced photographs of adults of an additional species of Acanthurus, A. mata (Cuvier, 1829), for which there are no previous records in the TEP. This species may have escaped previous notice due to its semi-pelagic habitat preference and its resemblance to Acanthurus xanthopterus Valenciennes, 1835, which occurs throughout much of the Galapagos.

Integrative Descriptions of Two New Mesobiotus Species (Tardigrada, Eutardigrada, Macrobiotidae) from Vietnam

To date, 34 tardigrade taxa have been recorded from Vietnam and this includes only two macrobiotid species belonging to the genus Mesobiotus. In this paper, two additional species of this genus, one of the M. harmsworthi group and one of the M. furciger group, are reported and described as new for science (Mesobiotus imperialis sp. nov., Mesobiotus marmoreus sp. nov.). Both descriptions have an integrative character providing detailed morphological and morphometric data collected by phase contrast and scanning electron microscopy that are linked to genetic data. The latter constitute DNA sequences of molecular markers that are commonly used in tardigrade taxonomy. The genus phylogeny is also provided, elucidating the phylogenetic position of the newly discovered taxa.

Scoping the Line Up: A Comparison of Biomonitoring Methodologies for Surf Zone Fish Communities

Surf zones are highly dynamic marine ecosystems that are subject to increasing anthropogenic and climatic pressures, posing multiple challenges for biomonitoring. Traditional methods such as seines and hook and line surveys are often labor intensive, taxonomically biased, and can be physically hazardous. Emerging techniques, such as baited remote underwater video (BRUV) and environmental DNA (eDNA) are promising nondestructive tools for assessing marine biodiversity in surf zones of sandy beaches. Here we compare the relative performance of beach seines, BRUV, and eDNA in characterizing community composition of bony (teleost) and cartilaginous (elasmobranch) fishes of surf zones at 18 open coast sandy beaches in southern California. Seine and BRUV surveys captured overlapping, but distinct fish communities with 50% (18/36) of detected species shared. BRUV surveys more frequently detected larger species (e.g. sharks and rays) while seines more frequently detected one of the most abundant species, barred surfperch ( Amphistichus argenteus ). In contrast, eDNA metabarcoding captured 83.3% (30/36) of all fishes observed in seine and BRUV surveys plus 59 additional species, including 13 that frequent surf zone habitats. eDNA approaches showed significantly higher sensitivity than seine and BRUV methods and more consistently detected 29 of the 30 (96.7%) jointly observed species across beaches. The six species detected by BRUV/seines, but not eDNA either lacked reference sequences, were only resolved at higher taxonomic ranks (e.g. Embiotocidae surfperches), or were detected below occupancy thresholds. Low site-species overlap between methods limited comparisons of richness and abundance estimates, highlighting the challenge of comparing biomonitoring approaches. Despite potential for improvement, results overall demonstrate that eDNA can provide a cost-effective tool for long-term surf zone monitoring that complements data from seine and BRUV surveys, allowing more comprehensive surveys of vertebrate diversity in surf zone habitats.

The genus Entomophthora: bringing the insect destroyers into the twenty-first century

The fungal genus Entomophthora consists of highly host-specific pathogens that cause deadly epizootics in their various insect hosts. The most well-known among these is the “zombie fly” fungus E. muscae, which, like other Entomophthora species, elicits a series of dramatic behaviors in infected hosts to promote optimal spore dispersal. Despite having been first described more than 160 years ago, there are still many open questions about Entomophthora biology, including the molecular underpinnings of host behavior manipulation and host specificity. This review provides a comprehensive overview of our current understanding of the biology of Entomophthora fungi and enumerates the most pressing outstanding questions that should be addressed in the field. We briefly review the discovery of Entomophthora and provide a summary of the 21 recognized Entomophthora species, including their type hosts, methods of transmission (ejection of spores after or before host death), and for which molecular data are available. Further, we argue that this genus is globally distributed, based on a compilation of Entomophthora records in the literature and in online naturalist databases, and likely to contain additional species. Evidence for strain-level specificity of hosts is summarized and directly compared to phylogenies of Entomophthora and the class Insecta. A detailed description of Entomophthora’s life-cycle and observed manipulated behaviors is provided and used to summarize a consensus for ideal growth conditions. We discuss evidence for Entomophthora’s adaptation to growth exclusively inside insects, such as producing wall-less hyphal bodies and a unique set of subtilisin-like proteases to penetrate the insect cuticle. However, we are only starting to understand the functions of unusual molecular and genomic characteristics, such as having large > 1 Gb genomes full of repetitive elements and potential functional diploidy. We argue that the high host-specificity and obligate life-style of most Entomophthora species provides ample scope for having been shaped by close coevolution with insects despite the current general lack of such evidence. Finally, we propose six major directions for future Entomophthora research and in doing so hope to provide a foundation for future studies of these fungi and their interaction with insects.

New Species of Anthurium (Araceae) from Venezuela

A total of nine species of Anthurium Schott sect. Calomystrium Schott (Araceae) from Venezuela are treated. Most of the species have been confused with A. cartilagineum (Desf.) Kunth; a dichotomous key to distinguish them is provided. All but one of these species are endemic to the Cordillera de la Costa in northern Venezuela. Seven species are described as new: A. alfcardozoi Croat, A. coltovarense Croat, A. galipanense Croat, A. georgetatei Croat, A. guaicaipurense Croat & M. Hanson, A. hansonianum Croat, and A. ronliesneri Croat. One additional species, Anthurium species #1, is included in the key and is fully described but is not being formally published owing to inadequate material. In addition, A. cartilagineum (Desf.) Kunth is redescribed, and a more complete description is provided since it is a close relative to several of the species treated here.