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Elias, M.

Publications and source records attributed to Elias, M..

At least 37 records · Page 2Linked to original sources

Reduced palatability, fast flight, and tails: Decoding the defence arsenal of Eudaminae skipper butterflies in a Neotropical locality

O_LIPrey often relies on multiple defences to avoid predators, such as difficulty of capture, attack deflection, or unpleasant taste. Eudaminae skipper butterflies rely on behavioural (fast flight) and mechanical defences (hindwing tails), but other defences like unpalatability (consumption deterrence), and the interaction among defences, have not been assessed. C_LIO_LIWe test the palatability of 12 abundant Eudaminae species from a Neotropical locality, using training and feeding experiments with domestic chicks. Further, we approximate the difficulty of capture explained by flight speed and quantified by wing loading. To test how multiple defences are associated and explained by body size and habitat preference, we perform phylogenetic Bayesian regression analyses. C_LIO_LIWe found a broad range of palatability in Eudaminae, within and among species. Palatability was negatively correlated with wing loading, indicating that butterflies with higher flight speed tend to have lower palatability. C_LIO_LIThe presence or absence of tails did not explain the level of butterfly palatability, showing that attack deflection and consumption deterrence are not mutually exclusive defences. Habitat preference (open or forested environments) did not explain the level of palatability in Eudaminae, but it seems that butterflies with high wing loading (fast flight) tended to occupy semi-closed (e.g., hilltops) or closed habitats (e.g., secondary forest). C_LIO_LIFinally, the level of unpalatability in Eudaminae is size dependent, larger butterflies are less palatable, perhaps due to their more likely detectability/preference by predators. Altogether, our findings shed light on the contexts favouring the prevalence of single vs. multiple defensive strategies in prey. C_LI

ecology↗

Parallel on-chip micropipettes enabling quantitative multiplexed characterization of vesicle mechanics and cell aggregates rheology

Micropipette aspiration (MPA) is one of the gold standards to quantify biological samples mechanical properties, which are crucial from the cell membrane scale to the multicellular tissue. However, relying on the manipulation of individual home-made glass pipettes, MPA suffers from low throughput and difficult automation. Here, we introduce the sliding insert micropipette aspiration (SIMPA) method, that permits parallelization and automation, thanks to the insertion of tubular pipettes, obtained by photolithography, within microfluidic channels. We show its application both at the lipid bilayer level, by probing vesicles to measure membrane bending and stretching moduli, and at the tissue level by quantifying the viscoelasticity of 3D cell aggregates. This approach opens the way to high-throughput, quantitative mechanical testing of many types of biological samples, from vesicles and individual cells to cell aggregates and explants, under dynamic physico-chemical stimuli.

biophysics↗

Engineering Quorum Quenching Acylases with Improved Kinetic and Biochemical Properties

Many Gram-negative bacteria respond to N-acyl-L-homoserine lactone (AHL) signals to coordinate phenotypes such as biofilm formation and virulence factor production. Quorum-quenching enzymes, such as acylases, chemically degrade AHL signals, prevent signal reception by bacteria, and inhibit undesirable traits related to biofilm. These capabilities make these enzymes appealing candidates for controlling microbes. Yet, enzyme candidates with high activity levels, high substrate specificity for specific interference, and that are capable of being formulated into materials are needed. In this work, we undertook engineering efforts against two AHL acylases, PvdQ and MacQ, to obtain improved acylase variants. The engineering of acylase is complicated by low-throughput enzymatic assays. To alleviate this challenge, we report a time-course kinetic assay for AHL acylase that tracks the real-time production of homoserine lactone. Using the protein one-stop shop server (PROSS), we identified variants of PvdQ that were significantly stabilized, with melting point increases of up to 13.2 {degrees}C, which translated into high resistance against organic solvents and increased compatibility with material coatings. We also generated mutants of MacQ with considerably improved kinetic properties, with >10-fold increases against N-butyryl-L-homoserine lactone and N-hexanoyl-L-homoserine lactone. In fact, the variants presented here exhibit unique combinations of stability and activity levels. Accordingly, these changes resulted in increased quenching abilities using a biosensor model and greater inhibition of virulence factor production of Pseudomonas aeruginosa PA14. While the crystal structure of one of the MacQ variants, M1, did not reveal obvious structural determinants explaining the observed changes in kinetics, it allowed for the capture of an acyl-enzyme intermediate that confirms a previously hypothesized catalytic mechanism of AHL acylases. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=69 SRC="FIGDIR/small/555929v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@12393cdorg.highwire.dtl.DTLVardef@bc8cd4org.highwire.dtl.DTLVardef@c1e2e3org.highwire.dtl.DTLVardef@116bc09_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

Encyclopaedia of DNA polymerases localized in organelles: Contribution of genes from diverse bacteria including the proto-mitochondrion.

DNA polymerases (DNAPs) synthesize DNA from deoxyribonucleotides in a semi-conservative manner and serve as the core of DNA replication and repair machineries. In eukaryotic cells, there are two genome-containing organelles, mitochondria and plastids, that were derived from an -proteobacterium and a cyanobacterium, respectively. Except for rare cases of genome-lacking mitochondria and plastids, both organelles must be served by nucleus-encoded DNAPs that localize and work in them to maintain their genomes. The evolution of organellar DNAPs has yet to be fully understood because of two unsettled issues. First, the diversity of organellar DNAPs has not been elucidated in the full spectrum of eukaryotes. Second, it is unclear when the DNAPs that were used originally in the endosymbiotic bacteria giving rise to mitochondria and plastids were discarded, as the organellar DNAPs known to date show no phylogenetic affinity to those of the extant -proteobacteria or cyanobacteria. In this study, we identified from diverse eukaryotes 134 family A DNAP sequences, which were classified into 10 novel types, and explored their evolutionary origins. The subcellular localizations of selected DNAPs were further examined experimentally. The results presented here suggest that the diversity of organellar DNAPs has been shaped by multiple transfers of the PolI gene from phylogenetically broad bacteria, and their occurrence in eukaryotes was additionally impacted by secondary plastid endosymbioses. Finally, we propose that the last eukaryotic common ancestor may have possessed two mitochondrial DNAPs, POP and a candidate of the direct descendant of the proto-mitochondrial DNAP, rdxPolA, identified in this study.

evolutionary biology↗

Clearwing butterflies challenge the thermal melanism hypothesis

In contrast to most butterflies harboring opaque wing colorations, some species display large transparent patches on their wings. Wing transparency, which entails a dramatic reduction of pigmentation, raises the question of potential costs for vital functions, such as thermoregulation, especially along climatic gradients. The thermal melanism hypothesis posits that darker colorations should be favored in colder environments, which enables them to absorb more radiation and maintain a body temperature compatible with activity. This prediction extends to the near infrared (NIR) range, which represents a large proportion of solar radiation. Here we assess the implications of wing transparency for light absorption and thermal properties in 42 butterfly species from the neotropical tribe Ithomiini that range the extent of transparency, from fully opaque to highly transparent, and we test whether those species conform to the prediction of the thermal melanism hypothesis. We find that transparent wings are less efficient than opaque wings to absorb light across UV, Visible and NIR wavelength ranges, and are also less efficient to collect heat. Moreover, dark coloration occupies a lower proportion of wing area as altitude increases, and ithomiine species harbor more transparency at higher altitudes, where climatic conditions are colder, going strongly against the prediction of the thermal melanism hypothesis. We discuss these surprising results in light of recent studies suggesting that factors other than adaptation to cold, such as predation pressure, physiology or behavior, may have driven the evolution of wing patterns in Ithomiini. Significance StatementThe thermal melanism hypothesis predicts that organisms should be darker and absorb solar radiation more efficiently in colder environments. The Neotropical butterflies Ithomiini are unusual in that many species harbor large transparent patches on their wings, raising questions related to their efficacy of solar radiation absorption and heating capacities. We investigate optical and thermal properties of several ithomiine species along a climatic gradient. We find that transparent wings are less efficient at absorbing radiation and collecting heat. Unexpectedly, the proportion of transparent species increases with altitude, challenging the thermal melanism hypothesis and suggesting that factors other than adaptation to cold, such as predation pressure, may have driven the evolution of wing patterns in Ithomiini.

evolutionary biology↗

Changes in Active Site Loop Conformation Relate to the Transition toward a Novel Enzymatic Activity

Enzymatic promiscuity, the ability of enzymes to catalyze multiple, distinct chemical reactions, has been well documented and is hypothesized to be a major driver for the emergence of new enzymatic functions. Yet, the molecular mechanisms involved in the transition from one activity to another remain debated and elusive. Here, we evaluated the redesign of the active site binding cleft of the lactonase SsoPox using structure-based design and combinatorial libraries. We created variants with largely improved catalytic abilities against phosphotriesters, the best ones being > 1,000-fold better compared to the wild-type enzyme. The observed shifts in activity specificity are large, [~]1,000,000-fold and beyond, since some variants completely lost their initial activity. The selected combinations of mutations have considerably reshaped the active site cavity via side chain changes but mostly through large rearrangements of the active site loops, as revealed by a suite of crystal structures. This suggests that specific active site loop configuration is critical to the lactonase activity. Interestingly, analysis of high-resolution structures hints at the potential role of conformational sampling and its directionality in defining an enzyme activity profile.

biochemistry↗

A-ring-fused pyrazoles of dihydrotestosterone targeting prostate cancer cells via the downregulation of the androgen receptor

High expression of the androgen receptor (AR) and the disruption of its regulation are strongly responsible for the development of prostate cancer (PCa). Therapeutically relevant non-steroidal or steroidal antiandrogens are able to block the AR effect by eliminating AR-mediated signalling. Herein we report the synthesis of novel steroidal pyrazoles derived from the natural sex hormone 5-dihydrotestosterone (DHT). 2-Ethylidene or 2-(hetero)arylidene derivatives of DHT obtained by regioselective Claisen-Schmidt condensation with acetaldehyde or (hetero)aromatic aldehydes in alkaline ethanol were reacted with monosubstituted hydrazines to give A-ring-fused 1,5-disubstituted pyrazoles as main or exclusive products, depending on the reaction conditions applied. Spontaneous or 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ)-induced oxidation of the primarily formed pyrazolines resulted in the desired products in moderate to good yields, while 17-oxidation also occurred by using the Jones reagent as a strong oxidant. Transcriptional activity of the AR in a reporter cell line was examined for all novel compounds, and several previously synthesized similar DHT-based pyrazoles with differently substituted heteroring were also included to obtain information about the structure-activity relationship. Two specific regioisomeric groups of derivatives significantly diminished the transcriptional activity of AR in reporter cell line in 10 M concentration, and displayed reasonable antiproliferative activity in AR-positive PCa cell lines. Lead compound (3d) was found to be a potent AR antagonist (IC50 = 1.18 M), generally suppressed AR signalling in time and dose dependent manner, moreover, it also led to a sharp decrease in wt-AR protein level probably caused by proteasomal degradation. We confirmed the antiproliferative activity selective for AR-positive PCa cell lines (with GI50 in low micromolar ranges), cellular, biochemical and in silico binding of 3d in AR ligand-binding domain. Moreover, compound 3d was shown to be potent even ex vivo in patient-derived tissues, which highlights the therapeutic potential of A-ring-fused pyrazoles. Table of content graphic O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY HighlightsO_LIA-ring-fused pyrazoles of 5-dihydrotestosterone were introduced as AR modulators C_LIO_LISAR study of 55 differently substituted derivatives was discussed C_LIO_LICompound 3d suppressed the expression of AR targets in prostate cell lines C_LIO_LICompound 3d caused AR degradation in time-dependent manner C_LIO_LIEx vivo activity of 3d was demonstrated in patient-derived explants C_LI

pharmacology and toxicology↗

Field testing of an enzymatic quorum quencher coating additive to reduce biocorrosion of steel

Microbial colonization can be detrimental to the integrity of metal surfaces and lead to microbiologically influenced corrosion (MIC). Biocorrosion is a serious problem for aquatic and marine industries in the world and severely affects the maritime transportation industry by destroying port infrastructure and increasing fuel usage and the time and cost required for maintenance of transport vessels. Here, we evaluate the potential of a stable quorum quenching lactonase enzyme to reduce biocorrosion in the field. Over the course of 21 months, steel samples coated with lactonase-containing acrylic paint were submerged at two different sites and depths in the Duluth Superior Harbor (DSH; Lake Superior, MN, USA) and benchmarked against controls, including the biological biocide surfactin. In this experiment, the lactonase treatment outperformed the surfactin biocide treatment and significantly reduced the number of corrosion tubercles (37% (p<0.01)) and the corroded surface area (39% (p<0.01)) as compared to the acrylic-coated control coupons. In an attempt to evaluate the effects of signal disruption of surface microbial communities and the reasons for lower corrosion levels, 16S rRNA sequencing was performed and community populations were analyzed. Interestingly, surface communities were similar between all treatments, and only minor changes could be observed. Among these changes, several groups including sulfate-reducing bacteria (SRBs) appeared to correlate with corrosion levels, and more specifically, SRBs abundance levels were lower on lactonase treated steel coupons. We surmise that these minute community changes may have large impacts on corrosion rates. Overall, these results highlight the potential use of stable quorum quenching lactonases as an eco-friendly antifouling coating additive.

microbiology↗

Genomics of Preaxostyla Flagellates Illuminates Evolutionary Transitions and the Path Towards Mitochondrial Loss

The notion that mitochondria cannot be lost was shattered with the report of an oxymonad Monocercomonoides exilis, the first eukaryote arguably without any mitochondrion. Yet, questions remain about whether this extends beyond the single species and how this transition took place. The Oxymonadida is a group of gut endobionts taxonomically housed in the Preaxostyla which also contains free-living flagellates of the genera Trimastix and Paratrimastix. The latter two taxa harbour conspicuous mitochondrion-related organelles (MROs). Here we report high-quality genome and transcriptome assemblies of two Preaxostyla representatives, the free-living Paratrimastix pyriformis and the oxymonad Blattamonas nauphoetae. We performed thorough comparisons among all available genomic and transcriptomic data of Preaxostyla to further decipher the evolutionary changes towards amitochondriality, endobiosis, and unstacked Golgi. Our results provide insights into the metabolic and endomembrane evolution, but most strikingly the data confirm the complete loss of mitochondria for all three oxymonad species investigated (M. exilis, B. nauphoetae, and Streblomastix strix), suggesting the amitochondriate status is common to a large part if not whole group of Oxymonadida. This observation moves this unique loss to 100 MYA when oxymonad lineage diversified. Author summaryMitochondria are nearly ubiquitous components of eukaryotic cells that constitute bodies of animals, fungi, plants, algae, and a broad diversity of single-celled eukaryotes, aka protists. Many groups of protists have substantially reduced the complexity of their mitochondria because they live in oxygen-poor environments, so they are unable to utilize the most salient feature of mitochondria - their ATP-producing oxidative phosphorylation metabolism. However, for a long time, scientists thought that it is impossible to completely lose a mitochondrion because this organelle provides other essential services to the cell, e.g. synthesis of protein cofactors called iron-sulfur clusters. Detailed investigation of chinchilla symbiont M. exilis documented the first case of an organism without mitochondrion, and it also provided a scenario explaining how this unique evolutionary experiment might have happened. In this work, we expand on this discovery by exploring genomes of multiple relatives of M. exilis. We show that the loss of the mitochondrion is not limited to a single species but possibly extends to its entire group, the oxymonads. We also compare the predicted metabolic capabilities of oxymonads to their closest known mitochondrion-containing relatives and map out various changes that occurred during the transition to amitochondriality.

microbiology↗

The net-like heterotrophic amoeba Leukarachnion salinum sp. nov. (Ochrophyta, Stramenopiles) has a cryptic plastid

Complete plastid loss seems to be very rare among secondarily non-photosynthetic eukaryotes. Leukarachnion sp. PRA-24, an amoeboid colourless protist related to the photosynthetic algal class Synchromophyceae (Ochrophyta), is a candidate for such a case based on a previous investigation by transmission electron microscopy. Here we characterise this organism in further detail and describe it as Leucomyxa plasmidifera, gen. et sp. nov., additionally demonstrating it is the first known representative of a broader clade of non- photosynthetic ochrophytes. We recovered its complete plastid genome, exhibiting a reduced gene set similar to plastomes of other non-photosynthetic ochrophytes yet being even more extreme in sequence divergence. Identification of components of the plastid protein import machinery in the Leuc. plasmidifera transcriptome assembly corroborated the organism possesses a cryptic plastid organelle. According to our bioinformatic reconstruction the plastid contains a unique combination of biosynthetic pathways producing haem, a folate precursor, and tocotrienols. As another twist to its organellar biology, Leuc. plasmidifera turned out to contain an unusual long insertion in its mitogenome related to a newly discovered mitochondrial plasmid exhibiting unprecedented features in terms of its size and coding capacity. Combined, our work uncovered further striking outcomes of the evolutionary course of semiautonomous organelles in protists.

evolutionary biology↗

Evidence for complex interplay between quorum sensing and antibiotic resistance in Pseudomonas aeruginosa

Quorum sensing (QS) is a cell-density-dependent, intercellular communication system mediated by small diffusible signaling molecules. QS regulates a range of bacterial behaviors, including biofilm formation, virulence, drug resistance mechanisms, and antibiotic tolerance. Enzymes capable of degrading signaling molecules can interfere in QS - a process termed quorum quenching (QQ). Remarkably, previous work reported some cases where enzymatic interference in QS was synergistic to antibiotics against Pseudomonas aeruginosa. The premise of combination therapy is attractive to fight against multidrug-resistant bacteria, yet comprehensive studies are lacking. Here we evaluate the effects of QS signal disruption on the antibiotic resistance profile of P. aeruginosa by testing 222 antibiotics and antibacterial compounds from 15 different classes. We found compelling evidence that QS signal disruption does indeed affect antibiotic resistance (40% of all tested compounds; 89/222), albeit not always synergistically (not synergistic for 48% of compounds with an effect (43/89)). For some tested antibiotics, like sulfathiazole and trimethoprim, we were able to relate the changes in resistance caused by QS signal disruption to the modulation of the expression of key genes of the folate biosynthetic pathway. Moreover, using a P. aeruginosa-based Caenorhabditis elegans killing model, we confirm that enzymatic QQ modulates the effects of antibiotics on P. aeruginosas pathogenicity in vivo. Altogether, these results show that signal disruption has profound and complex effects on the antibiotic resistance profile of P. aeruginosa. This work suggests that combination therapy including QQ and antibiotics should not be discussed globally but rather in case-by-case studies. IMPORTANCEInterference in bacterial Quorum Sensing (QS) is a promising approach to control microbial behavior. Of particular interest is the potential of this strategy to reduce biofilms and virulence of antibiotic resistant strains. Interestingly, several studies report synergistic interactions between antibiotic treatments and interference in QS. However, it is unclear whether this is a generality, let alone the molecular mechanisms underlying the observed synergies. Here, we provide a comprehensive description of combination treatment in the model organism, opportunistic human pathogen P. aeruginosa. Screening > 200 antimicrobials, and combining them to QS signals and disruption strategies, we show that there is no systematic synergy between these approaches in vitro, as well as in vivo, in a C. elegans infection model. Altogether, this work show that QS has complex connections to the antibiotic resistance profile of P. aeruginosa, and that combination treatment should not be discussed globally, but rather in case-by-case studies.

microbiology↗

Phylogenomics Illuminates the Evolutionary History of Wild Silkmoths in Space and Time (Lepidoptera: Saturniidae)

AO_SCPLOWBSTRACTC_SCPLOWWild silkmoths (Saturniidae) are one of the most emblematic and most studied families of moths. Yet, the absence of a robust phylogenetic framework based on a comprehensive taxonomic sampling impedes our understanding of their evolutionary history. We analyzed 1,024 ultraconserved elements (UCEs) and their flanking regions to infer the relationships among 338 species of Saturniidae representing all described subfamilies, tribes, and genera. We investigated systematic biases in genomic data and performed dating and historical biogeographic analyses to reconstruct the evolutionary history of wild silkmoths in space and time. Using Gene Genealogy Interrogation, we showed that saturation of nucleotide sequence data blurred our understanding of early divergences and first biogeographic events. Our analyses support a Neotropical origin of saturniids, shortly after the Cretaceous-Paleogene extinction event (ca 64.0 [stem] - 52.0 [crown] Ma), and two independent colonization events of the Old World during the Eocene, presumably through the Bering Land Bridge. Early divergences strongly shaped the distribution of extant subfamilies as they showed very limited mobility across biogeographical regions, except for Saturniinae, a subfamily now present on all continents but Antarctica. Overall, our results provide a framework for in-depth investigations into the spatial and temporal dynamics of all saturniid lineages and for the integration of their evolutionary history into further global studies of biodiversity and conservation. Rather unexpectedly for a taxonomically well-known family such as Saturniidae, the proper alignment of taxonomic divisions and ranks with our phylogenetic results leads us to propose substantial rearrangements of the family classification, including the description of one new subfamily and two new tribes.

evolutionary biology↗

Improved basic cytogenetics challenges holocentricity of butterfly chromosomes

Mitotic chromosomes of butterflies, which look like dots or short filaments in most published data, are generally considered to lack localised centromeres and thus to be holokinetic. This particularity, observed in a number of other invertebrates, is associated with meiotic particularities known as "inverted meiosis", in which the first division is equational, i.e., centromere splitting-up and segregation of sister chromatids instead of that of homologous chromosomes. However, the accurate analysis of butterfly chromosomes is difficult. 1) Their size is very small, equivalent to a single band of a mammalian metaphase chromosome. 2) They lack satellite DNA/heterochromatin in putative centromere regions and therefore marked primary constrictions. Our improved conditions for chromosome preparations in six butterfly species belonging to the Nymphalidae and Pieridae families challenges the holocentricity of their chromosomes: in spite of the absence of primary constriction, sister chromatids are recurrently held together at definite positions during mitotic metaphase, which makes possible to establish karyotypes composed of acrocentric and sub-metacentric chromosomes. The total number of chromosomes per karyotype is roughly inversely proportional to that of non-acrocentric chromosomes, which suggests the occurrence of frequent Robertsonian-like fusions or fissions during evolution. Furthermore, the behaviour and morphological changes of chromosomes along the various phases of meiosis do not differ much from those of canonical meiosis. In particular at metaphase II, chromosomes clearly have two sister chromatids, which refutes that anaphase I was equational. Thus, we propose an alternative mechanism to holocentricity for explaining the large variations in chromosome numbers in butterflies: 1) in the ancestral karyotype, composed of about 60-62 acrocentric chromosomes, the centromeres, devoid of centromeric heterochromatin/satellite DNA, were located at contact with telomeric heterochromatin; 2) the instability of telomeric heterochromatin largely contributed to drive the multiple chromosome rearrangements, which occurred during butterfly evolution.

genetics↗

A new lineage of non-photosynthetic green algae with extreme organellar genomes

BackgroundThe plastid genomes of the green algal order Chlamydomonadales tend to expand their non-coding regions, but this phenomenon is poorly understood. Here we shed new light on organellar genome evolution in Chlamydomonadales by studying a previously unknown non-photosynthetic lineage. We established cultures of two new Polytoma-like flagellates, defined their basic characteristics and phylogenetic position, and obtained complete organellar genome sequences and a transcriptome assembly for one of them. ResultsWe discovered a novel deeply diverged chlamydomonadalean lineage that has no close photosynthetic relatives and represents an independent case of photosynthesis loss. To accommodate these organisms we establish the new genus Leontynka, with two species (L. pallida and L. elongata) distinguishable through both their morphological and molecular characteristics. Notable features of the colourless plastid of L. pallida deduced from the plastid genome (plastome) sequence and transcriptome assembly include the retention of ATP synthase, thylakoid-associated proteins, the carotenoid biosynthesis pathway, and a plastoquinone-based electron transport chain, the latter two modules having an obvious functional link to the eyespot present in Leontynka. Most strikingly, the ~362 kbp plastome of L. pallida is by far the largest among the non-photosynthetic eukaryotes investigated to date due to an extreme proliferation of sequence repeats. These repeats are also present in coding sequences, with one repeat type found in the exons of 11 out of 34 protein-coding genes, with up to 36 copies per gene, thus affecting the encoded proteins. The mitochondrial genome of L. pallida is likewise exceptionally large, with its >104 kbp surpassed only by the mitogenome of Haematococcus lacustris among all members of Chlamydomonadales hitherto studied. It is also bloated with repeats, though entirely different from those in the L. pallida plastome, which contrasts with the situation in H. lacustris where both the organellar genomes have accumulated related repeats. Furthermore, the L. pallida mitogenome exhibits an extremely high GC content in both coding and non-coding regions and, strikingly, a high number of predicted G-quadruplexes. ConclusionsWith its unprecedented combination of plastid and mitochondrial genome characteristics, Leontynka pushes the frontiers of organellar genome diversity and is an interesting model for studying organellar genome evolution.

evolutionary biology↗

Phylogenetic profiling and cellular analyses of ARL16 reveal roles in traffic of IFT140 and INPP5E

The ARF family of regulatory GTPases is ancient, with 16 members predicted to have been present in the last eukaryotic common ancestor. Our phylogenetic profiling of paralogs in diverse species identified four family members whose presence correlates with that of a cilium/flagellum: ARL3, ARL6, ARL13, and ARL16. No prior evidence links ARL16 to cilia or other cell functions, despite its presence throughout eukaryotes. Deletion of ARL16 in MEFs results in decreased ciliogenesis yet increased ciliary length. We also found Arl16 KO in MEFs to alter ciliary protein content, including loss of ARL13B, ARL3, INPP5E, and the IFT-A core component IFT140. Instead, both INPP5E and IFT140 accumulate at the Golgi in Arl16 KO lines, while other IFT proteins do not, suggesting a specific defect in traffic from Golgi to cilia. We propose that ARL16 regulates a Golgi-cilia traffic pathway and is required specifically in the export of IFT140 and INPP5E from the Golgi. SummaryPhylogenetic analyses of ARF family GTPases predict that ARL16 is linked to cilia. This was confirmed using MEFs deleted for ARL16, resulting in defects in Golgi to cilium traffic, with accumulation of IFT140 and INPP5E at Golgi.

cell biology↗

Hydrophobicity in clearwing butterflies and moths: impact of scale 2 micro and nanostructure, and trade-off with optical transparency

Living organisms are submitted to multiple developmental and selective constraints resulting in evolutionary compromises, one of the best examples being the integument (the outer protective layer of living organisms) which is fundamentally multifunctional. Integument anti-wetting or hydrophobicity - evolved in relation to complex and various structures - is a crucial property as it serves multiple functions like self-cleaning, locomotion, or defence against pathogens and may interfere with other functions like thermoregulation or communication. Elucidating the structure-property relationships and unravelling potential trade-offs is crucial to understand the evolution of the integument. In opaque Lepidoptera, wing scales actively contribute to anti-wetting. In clearwing Lepidoptera, wing scales are often reduced, raising the question of whether they can maintain similar hydrophobicity levels to those of opaque species and if not, whether wing microstructure (scale density, shape, insertion, and coloration) may mitigate the costs of a lower hydrophobicity. To answer these questions, we measure static contact angle (CA) of water droplets at different stages of evaporation in opaque and transparent patches of 23 Lepidoptera species that show a high diversity in wing microstructure. More specifically, we find that transparency is costly for hydrophobicity, and that such cost depends on wing microstructure. In general, transparent patches lose more hydrophobicity with water evaporation than opaque patches. Yet, this loss of hydrophobicity is attenuated for higher scale densities, erect scales compared to flat scales, coloured scales (for erect scales), multiple scale layers (for flat scales), or when combining two types of scales (piliform and lamellar) than having only one type of scale (piliform or lamellar). Nude membranes show the lowest hydrophobicity values. We find that wing hydrophobicity negatively relates to optical transparency, showing a trade-off between optics and hydrophobicity. Moreover, we find that tropical species have higher hydrophobicity in their transparent patches than temperate ones, suggesting transparent patches are under stronger selection for hydrophobicity in tropical than in temperate species. These novel findings, which are consistent with the physics of hydrophobicity, suggest that insect wings are evolutionary multifunctional compromises.

evolutionary biology↗

Monodopsis and Vischeria genomes elucidate the biology of eustigmatophyte algae

Members of eustigmatophyte algae, especially Nannochloropsis, have been tapped for biofuel production owing to their exceptionally high lipid content. While extensive genomic, transcriptomic, and synthetic biology toolkits have been made available for Nannochloropsis, very little is known about other eustigmatophytes. Here we present three near-chromosomal and gapless genome assemblies of Monodopsis (60 Mb) and Vischeria (106 Mb), which are the sister groups to Nannochloropsis. These genomes contain unusually high percentages of simple repeats, ranging from 12% to 21% of the total assembly size. Unlike Nannochloropsis, LINE repeats are abundant in Monodopsis and Vischeria and might constitute the centromeric regions. We found that both mevalonate and non-mevalonate pathways for terpenoid biosynthesis are present in Monodopsis and Vischeria, which is different from Nannochloropsis that has only the latter. Our analysis further revealed extensive spliced leader trans-splicing in Monodopsis and Vischeria at 36-61% of genes. Altogether, the high-quality genomes of Monodopsis and Vischeria not only serve as the much-needed outgroups to advance Nannochloropsis research, but also shed new light on the biology and evolution of eustigmatophyte algae.

genomics↗

Punctual ecological changes rather than global factors drive species diversification and the evolution of wing phenotypes in Morpho butterflies.

Assessing the relative importance of geographical and ecological drivers of evolution is paramount to understand the diversification of species and traits at the macroevolutionary scale. Here, we use an integrative approach, combining phylogenetics, biogeography, ecology, and quantified phenotypes to investigate the drivers of both species and phenotypic diversification of the iconic Neotropical butterfly genus Morpho. We generated a time-calibrated phylogeny for all known species and inferred historical biogeography. We fitted models of time-dependent (accounting for rate heterogeneity across the phylogeny) and paleoenvironment-dependent diversification (accounting for global effect on the phylogeny). We used geometric morphometrics to assess variation of wing size and shape across the tree, and investigated their dynamics of evolution. We found that the diversification of Morpho is best explained when considering multiple independent diversification dynamics across the tree, possibly associated with lineages occupying different microhabitat conditions. First, a shift from understory to canopy was characterized by an increased speciation rate partially coupled with an increasing rate of wing shape evolution. Second, the occupation of dense bamboo thickets accompanying a major host-plant shift from dicotyledons towards monocotyledons was associated with a simultaneous diversification rate shift and an evolutionary "jump" of wing size. Our study points to a diversification pattern driven by punctual ecological changes instead of a global driver or biogeographic history.

evolutionary biology↗