ALBERT

Description: Nitrogen fixation — the reduction of dinitrogen (N2) gas to biologically available nitrogen (N) — is an important source of N for terrestrial and aquatic ecosystems. In terrestrial environments, N2-fixing symbioses involve multicellular plants, but in the marine environment these symbioses occur with unicellular planktonic algae. An unusual symbiosis between an uncultivated unicellular cyanobacterium (UCYN-A) and a haptophyte picoplankton alga was recently discovered in oligotrophic oceans. UCYN-A has a highly reduced genome, and exchanges fixed N for fixed carbon with its host. This symbiosis bears some resemblance to symbioses found in freshwater ecosystems. UCYN-A shares many core genes with the 'spheroid bodies' of Epithemia turgida and the endosymbionts of the amoeba Paulinella chromatophora. UCYN-A is widely distributed, and has diversified into a number of sublineages that could be ecotypes. Many questions remain regarding the physical and genetic mechanisms of the association, but UCYN-A is an intriguing model for contemplating the evolution of N2-fixing organelles.

Description: Natural products and their derivatives are mainstays of our antibiotic drugs, but they are increasingly in peril. The combination of widespread multidrug resistance in once susceptible bacterial pathogens, disenchantment with natural products as sources of new drugs, lack of success using synthetic compounds and target-based discovery methods, along with shifting economic and regulatory issues, conspire to move investment in research and development away from the antibiotics arena. The result is a growing crisis in antibiotic drug discovery that threatens modern medicine. 21st century natural product research is perfectly positioned to fill the antibiotic discovery gap and bring new drug candidates to the clinic. Innovations in genomics and techniques to explore new sources of antimicrobial chemical matter are revealing new chemistry. Increasing appreciation of the value of narrow-spectrum drugs and re-examination of once discarded chemical scaffolds coupled with synthetic biology methods to generate new compounds and improve yields offer new strategies to revitalize once moribund natural product programs. The increasing awareness that the combination of antibiotics with adjuvants, non-antibiotic compounds that overcome resistance and enhance drug activity, can rescue older chemical scaffolds, and concepts such as blocking pathogen virulence present orthogonal strategies to traditional antibiotics. In all these areas, natural products offer chemical matter, shaped by natural selection, that is privileged in this therapeutic area. Natural product research is poised to regain prominence in delivering new drugs to solve the antibiotic crisis.

Description: Cellulose nanocrystals, a class of fascinating bio-based nanoscale materials, have received a tremendous amount of interest both in industry and academia owing to its unique structural features and impressive physicochemical properties such as biocompatibility, biodegradability, renewability, low density, adaptable surface chemistry, optical transparency, and improved mechanical properties. This nanomaterial is a promising candidate for applications in fields such as biomedical, pharmaceuticals, electronics, barrier films, nanocomposites, membranes, supercapacitors, etc. New resources, new extraction procedures, and new treatments are currently under development to satisfy the increasing demand of manufacturing new types of cellulose nanocrystals-based materials on an industrial scale. Therefore, this review addresses the recent progress in the production methodologies of cellulose nanocrystals, covering principal cellulose resources and the main processes used for its isolation. A critical and analytical examination of the shortcomings of various approaches employed so far is made. Additionally, structural organization of cellulose and nomenclature of cellulose nanomaterials have also been discussed for beginners in this field.

Description: The co-existence of different microbial species in one habitat is prerequisite for many ecosystem processes. To facilitate co-habitation of ecological niches, intricate mechanisms have evolved that regulate the growth and the behaviour of microbes. A crucial aspect for the establishment and maintenance of a microbial population is the communication among species. Whereas intraspecies communication processes have been widely studied, little is known about the molecular mechanisms underlying interspecies interactions. Through the advance of modern analytical and sequencing technologies, we are now beginning to gain deeper insights into these complex processes. A key feature of microbe–microbe interaction is the secretion of chemical mediators to influence either the microbial partner or co-occurring higher organisms to shape the specific microenvironment. Here we summarize recent advances in understanding the role of natural products as regulators of microbial interaction in various ecological niches. Special attention is paid to mutualistic relationships with relevance for ecology and agriculture as well as medicine.

Description: Chemical mediation regulates behavioral interactions between species and thus affects population structure, community organization and ecosystem function. Among marine taxa that have developed chemical mediation strategies, gastropods belong to a diverse group of molluscs found worldwide, including species with a coiled, reduced or absent shell. Most gastropods use natural products to mediate a wide range of behaviors such as defense, prey location or interactions with con- and hetero-geners. Their chemically defended diet, such as cyanobacteria, algae, sponges, bryozoans and tunicates, provides them with a considerable opportunity either as shelter from predators, or as a means to enhance their own chemical defense. In addition to improving their defenses, molluscs also use prey secondary metabolites in complex chemical communication including settlement induction, prey detection and feeding preferences. The assimilation of prey secondary metabolites further provides the opportunity for interactions with conspecifics via diet-derived chemical cues or signals. This review intends to provide an overview on the sequestration, detoxification, and biotransformation of diet-derived natural products, as well as the role of these compounds as chemical mediators in gastropod-prey interactions.

Description: Low-level water measurements of geological materials are fundamental in understanding the volatile inventories of the Earth from the mantle to crustal reservoirs. Here we describe the development of microanalytical techniques using the new SHRIMP SI ion microprobe to measure the abundances of OH− (as a proxy for water) in volcanic glass and nominally anhydrous minerals (NAMs). Samples were first analysed at the Carnegie Institute of Washington (CIW) on their Cameca ims-6f with calibrations based on previous FTIR and manometry analyses. SHRIMP SI is a large geometry ion microprobe and is currently mainly used for O and S isotope analyses. The analytical protocol used here incorporates multiple collection of 16O− and 16O1H− allowing rapid measurements. A single calibration line incorporating all glasses and NAMs for the SHRIMP SI allows calibration of 16O1H−/16O− to H2O over a wide range in concentration (50 to 15 000 ppm H2O). This calibration line has around a 10% uncertainty, which appears to be limited only by sample heterogeneity. The current background for SHRIMP analysis is between 20–40 ppm but this is expected to improve with improved pumping on the source chamber. A current limitation to water analysis of NAM samples, by any technique, is having a range of standard materials to enable OH− calibration to absolute H2O concentrations. Data are presented for 7 NAM samples (2 olivines, 2 orthopyroxenes and 3 clinopyroxenes) that appear to be promising as potential standards for international laboratory H2O measurements. These NAM samples have been analysed and characterised here by SHRIMP SI, FTIR, EMP and the Cameca ims-6f ion microprobe at CIW. Four of these samples have previously been measured by manometry to determine absolute H2O concentrations.

Description: Recognition that evolution operates on the same timescale as ecological processes has motivated growing interest in eco-evolutionary dynamics. Nonetheless, generating sufficient data to test predictions about eco-evolutionary dynamics has proved challenging, particularly in natural contexts. Here we argue that genomic data can be integrated into the study of eco-evolutionary dynamics in ways that deepen our understanding of the interplay between ecology and evolution. Specifically, we outline five major questions in the study of eco-evolutionary dynamics for which genomic data may provide answers. Although genomic data alone will not be sufficient to resolve these challenges, integrating genomic data can provide a more mechanistic understanding of the causes of phenotypic change, help elucidate the mechanisms driving eco-evolutionary dynamics, and lead to more accurate evolutionary predictions of eco-evolutionary dynamics in nature.

Description: Actinomycetes have been, for decades, one of the most important sources for the discovery of new antibiotics with an important number of drugs and analogs successfully introduced in the market and still used today in clinical practice. The intensive antibacterial discovery effort that generated the large number of highly potent broad-spectrum antibiotics, has seen a dramatic decline in the large pharma industry in the last two decades resulting in a lack of new classes of antibiotics with novel mechanisms of action reaching the clinic. Whereas the decline in the number of new chemical scaffolds and the rediscovery problem of old known molecules has become a hurdle for industrial natural products discovery programs, new actinomycetes compounds and leads have continued to be discovered and developed to the preclinical stages. Actinomycetes are still one of the most important sources of chemical diversity and a reservoir to mine for novel structures that is requiring the integration of diverse disciplines. These can range from novel strategies to isolate species previously not cultivated, innovative whole cell screening approaches and on-site analytical detection and dereplication tools for novel compounds, to in silico biosynthetic predictions from whole gene sequences and novel engineered heterologous expression, that have inspired the isolation of new NPs and shown their potential application in the discovery of novel antibiotics. This review will address the discovery of antibiotics from actinomycetes from two different perspectives including: (1) an update of the most important antibiotics that have only reached the clinical development in the recent years despite their early discovery, and (2) an overview of the most recent classes of antibiotics described from 2006 to 2017 in the framework of the different strategies employed to untap novel compounds previously overlooked with traditional approaches.

Description: Decades of research on human microbiota have revealed much of their taxonomic diversity and established their direct link to health and disease. However, the breadth of bioactive natural products secreted by our microbial partners remains unknown. Of particular interest are antibiotics produced by our microbiota to ward off invasive pathogens. Members of the human microbiota exclusively produce evolved small molecules with selective antimicrobial activity against human pathogens. Herein, we expand upon the current knowledge concerning antibiotics derived from human microbiota and their distribution across body sites. We analyze, using our in-house chem-bioinformatic tools and natural products database, the encoded antibiotic potential of the human microbiome. This compilation of information may create a foundation for the continued exploration of this intriguing resource of chemical diversity and expose challenges and future perspectives to accelerate the discovery rate of small molecules from the human microbiota.

Description: The review summarizes results up to 2017 on chemosensory cues occurring in both aquatic and terrestrial environments. The chemicals are grouped by their physicochemical properties to compare their potential mobility in the different media. In contrast to what is widely asserted in the literature, the report emphasizes that living organisms encounter and sense molecules of various degrees of solubility and volatility both on land and in aquatic environments. The picture that emerges from the review suggests a substantial revision of the traditional definitions of the chemical senses based on their spatial range, which is currently orienting the literature on chemosensory signaling, in favor of a new vision based on the natural products that are the actual mediators of the chemosensory perceptions. According to this perspective, natural product chemistry is a powerful tool with which to explore the evolutionary history of the chemical senses.