RNA-Templated Peptide Bond Formation Promotes L-Homochirality.

The world in which we live is homochiral. The ribose units that form the backbone of DNA and RNA are all D-configured and the encoded amino acids that comprise the proteins of all living species feature an all-L-configuration at the α-carbon atoms. The homochirality of α-amino acids is essential for folding of the peptides into well-defined and functional 3D structures and the homochirality of D-ribose is crucial for helix formation and base-pairing. The question of why nature uses only encoded L-α-amino acids is not understood. Herein, we show that an RNA-peptide world, in which peptides grow on RNAs constructed from D-ribose, leads to the self-selection of homo-L-peptides, which provides a possible explanation for the homo-D-ribose and homo-L-amino acid combination seen in nature.

The fungus Clonostachys epichloë alters the influence of the Epichloë endophyte on seed germination and the biomass of Puccinellia distans grass.

The fungal grass endophyte Epichloë typhina (Pers.) Tul. & C. Tul. (Ascomycota: Clavicipitaceae) grows intercellulary in aerial plant parts and reproduces asexually by invading host seeds. In this phase, it enhances seed production and germination, which accelerates its vertical spread. This relationship may be distorted by other seed-born fungi, whose spread is not so directly dependent on the success of the grass. Recently, the fungus Clonostachys epichloë Schroers has been observed on Puccinellia distans (Jacq.) Parl seeds originating from grass clumps infested with stromata, sexual structures of Epichloë typhina that are formed in spring on some host culms, preventing flower and seed development ('choke disease'). C. epichloë shows mycoparasitic activity toward Epichloë stromata by reducing the production of ascospores, which are responsible for horizontal transmission of the fungus. The aim of this study was to investigate the effect of seed-borne C. epichloë on seed germination, as well as the size and weight of P. distans seedlings and to examine whether C. epichloë alters the influence of Epichloë in the early developmental stages of P. distans. The results showed that if C. epichloë acts on seeds together with E. typhina endophytes, the seeds were negatively affected due to the elimination of the positive effect of the latter in terms of both seed germination rate and seedling length. At the same time, C. epichloë increased the proportion of E. typhina-untreated germinated seeds. Additionally, only the joint action of the two fungi, E. typhina and C. epichloë, effectively stimulated seedling dry mass; the presence of E. typhina alone was not sufficient to noticeably affect seedling size. Based on the increasing commonality of C. epichloë on Epichloë stromata, as well as its potential to be used in biocontrol of 'choke disease', we should take a closer look at this fungus, not only in terms of its mycoparasitic ability, but also in terms of its cumulative impact on the whole Epichloë-grass system.

The use of social media in assessing the impact of war on cetaceans.

War has always brought millions of silent non-human victims but the scale of this suffering is often either unknown, neglected or difficult to quantify. Further, the complexities associated with long-term and large-scale monitoring of marine species make it difficult to assess the impacts of war and the mortality of cetaceans resulting from warfare has not been investigated. Here we propose the use of a modified form of citizen science, namely gathering the information from social media. Dolphin stranding is such a poignant incident for most people, that the probability of eyewitness posting information on social media appears high. We test this idea by collecting data on cetacean strandings along the Black Sea published on the Internet over the three months of Russia's invasion of Ukraine in 2022. We also validate this method with a small-scale scientific study on cetacean mortality during the same period of time, conducted in 'Tuzlivski lymany' Nature National Park in Ukraine. Our dual approach has produced similar results, indicating a dramatic increase in cetacean mortality due to war operations in the Black Sea. We advocate the future use of social media to bridge the knowledge gap on the impacts of war on animals, in particular cetaceans.

Loading of Amino Acids onto RNA in a Putative RNA-Peptide World.

RNA is a molecule that can both store genetic information and perform catalytic reactions. This observed dualism places RNA into the limelight of concepts about the origin of life. The RNA world concept argues that life started from self-replicating RNA molecules, which evolved toward increasingly complex structures. Recently, we demonstrated that RNA, with the help of conserved non-canonical nucleosides, which are also putative relics of an early RNA world, had the ability to grow peptides covalently connected to RNA nucleobases, creating RNA-peptide chimeras. It is conceivable that such molecules, which combined the information-coding properties of RNA with the catalytic potential of amino acid side chains, were once the structures from which life emerged. Herein, we report prebiotic chemistry that enabled the loading of both nucleosides and RNAs with amino acids as the first step toward RNA-based peptide synthesis in a putative RNA-peptide world.

A prebiotically plausible scenario of an RNA-peptide world.

The RNA world concept1 is one of the most fundamental pillars of the origin of life theory2-4. It predicts that life evolved from increasingly complex self-replicating RNA molecules1,2,4. The question of how this RNA world then advanced to the next stage, in which proteins became the catalysts of life and RNA reduced its function predominantly to information storage, is one of the most mysterious chicken-and-egg conundrums in evolution3-5. Here we show that non-canonical RNA bases, which are found today in transfer and ribosomal RNAs6,7, and which are considered to be relics of the RNA world8-12, are able to establish peptide synthesis directly on RNA. The discovered chemistry creates complex peptide-decorated RNA chimeric molecules, which suggests the early existence of an RNA-peptide world13 from which ribosomal peptide synthesis14 may have emerged15,16. The ability to grow peptides on RNA with the help of non-canonical vestige nucleosides offers the possibility of an early co-evolution of covalently connected RNAs and peptides13,17,18, which then could have dissociated at a higher level of sophistication to create the dualistic nucleic acid-protein world that is the hallmark of all life on Earth.

Contact calls in woodpeckers are individually distinctive, show significant sex differences and enable mate recognition.

Vocal communication of woodpeckers has been relatively little studied so far, mostly because majority of species use drumming to communicate. Our recent study on the Middle Spotted Woodpecker revealed that a call which is specific for floaters is individually distinctive and functions as a vocal signature of unpaired individuals. The aim of the current study is to investigate whether a contact call of paired territory owners of the same species enables discrimination of individuals and their sex. Acoustic analyses revealed that the call is individually distinctive and experimental approach confirmed that woodpeckers are able to distinguish between a contact call of their partner and a stranger. We also found that the contact call shows significant sex differences. Interestingly, the acoustic parameter enabling sex identification is different than the parameters coding individual variability of the call. The design of a call so that its first part would code the identity of an individual and the second part would code its sex presents an effective and fine-tuned communication system. The results of our study also suggest that the contact call of paired Middle Spotted Woodpeckers may be useful for conservation biologists as a tool supporting other census methods.

Equal division of parental care enhances nestling development in the Blackcap.

Because parental care is costly, conflict between mates over their roles in reproduction seems unavoidable unless they both benefit from parental labour split equally between partners. In the current paper we analyse the division of parental investment in the Blackcap (Sylvia atricapilla), a species that experiences high nest predation. We show that both sexes invest in the incubation of eggs as well as feeding and brooding nestlings at a similar level. We also found that pairs which divided feeding duties more equally produced nestlings that grew faster. Faster nestling development enables earlier fledging in case of predation attempts at the end of nesting period. Thus parents who more evenly participate in provisioning may benefit from higher breeding success. Our findings suggest that in species under high risk of nest predation disparity in parental investment may not provide much benefit to parent's residual reproductive value and that equality in parental duties constitutes a winning strategy.