Short-term polystyrene nanoplastic exposure alters zebrafish male and female germline and reproductive outcomes, unveiling pollutant-impacted molecular pathways.

Nanoplastics pollution is a rising environmental concern whose impacts on biodiversity and human health are far from being understood. This is particularly salient in aquatic ecosystems, where the majority of species depend on external fertilization for reproduction. Here we evaluated the effects of a short-term exposure to engineered polystyrene nanoplastics (NPs) in the zebrafish germline to further explore their impact on reproduction.

Evolution of 3D Chromatin Folding.

Studies examining the evolution of genomes have focused mainly on sequence conservation. However, the inner working of a cell implies tightly regulated crosstalk between complex gene networks controlled by small dispersed regulatory elements of physically contacting DNA regions. How these different levels of chromatin organization crosstalk in different species underpins the potential for genome evolutionary plasticity.

De novo genome assemblies of two cryptodiran turtles with ZZ/ZW and XX/XY sex chromosomes provide insights into patterns of genome reshuffling and uncover novel 3D genome folding in amniotes.

Understanding the evolution of chromatin conformation among species is fundamental to elucidate the architecture and plasticity of genomes. Nonrandom interactions of linearly distant loci regulate gene function in species-specific patterns, affecting genome function, evolution, and, ultimately, speciation. Yet, data from nonmodel organisms are scarce.

Incomplete transcriptional dosage compensation of chicken and platypus sex chromosomes is balanced by post-transcriptional compensation.

Heteromorphic sex chromosomes (XY or ZW) present problems of gene dosage imbalance between sexes and with autosomes. A need for dosage compensation has long been thought to be critical in vertebrates. However, this was questioned by findings of unequal mRNA abundance measurements in monotreme mammals and birds.

Three-dimensional genome architecture persists in a 52,000-year-old woolly mammoth skin sample.

Analyses of ancient DNA typically involve sequencing the surviving short oligonucleotides and aligning to genome assemblies from related, modern species. Here, we report that skin from a female woolly mammoth (†Mammuthus primigenius) that died 52,000 years ago retained its ancient genome architecture. We use PaleoHi-C to map chromatin contacts and assemble its genome, yielding 28 chromosome-length scaffolds.

Extant and extinct bilby genomes combined with Indigenous knowledge improve conservation of a unique Australian marsupial.

Ninu (greater bilby, Macrotis lagotis) are desert-dwelling, culturally and ecologically important marsupials. In collaboration with Indigenous rangers and conservation managers, we generated the Ninu chromosome-level genome assembly (3.66 Gbp) and genome sequences for the extinct Yallara (lesser bilby, Macrotis leucura).

The pluripotency state of human embryonic stem cells derived from single blastomeres of eight-cell embryos.

Human embryonic stem cells (hESCs) derived from blastocyst stage embryos present a primed state of pluripotency, whereas mouse ESCs (mESCs) display naïve pluripotency. Their unique characteristics make naïve hESCs more suitable for particular applications in biomedical research. This work aimed to derive hESCs from single blastomeres and determine their pluripotency state, which is currently unclear.

Uncommon Large and Bilateral Fibrous Cephalic Plaques in a Patient with -Related Tuberous Sclerosis Complex.

Tuberous sclerosis complex (TSC) is a genetic disorder, frequently characterized by early dermatological manifestations. The recognition and adequate description of these dermatological manifestations are of utmost importance for early diagnosis, allowing for the implementation of therapeutic and preventive measures. Fibrous cephalic plaques (FCPs) are considered a major diagnostic criterion for TSC, as FCPs are the most specific skin lesions of TSC.

Blastomeres of 8-cell mouse embryos differ in their ability to generate embryonic stem cells and produce lines with different transcriptional signatures.

Embryonic stem cell (ESC) derivation from single blastomeres of 8-cell mouse embryos results in lower derivation rates than that from whole blastocysts, raising a biological question about the developmental potential of sister blastomeres. We aimed to assess the ability of 8-cell blastomeres to produce epiblast cells and ESC lines after isolation, and the properties of the resulting lines. Our results revealed unequal competence among sister blastomeres to produce ESC lines.

Divergent patterns of meiotic double strand breaks and synapsis initiation dynamics suggest an evolutionary shift in the meiosis program between American and Australian marsupials.

In eutherian mammals, hundreds of programmed DNA double-strand breaks (DSBs) are generated at the onset of meiosis. The DNA damage response is then triggered. Although the dynamics of this response is well studied in eutherian mammals, recent findings have revealed different patterns of DNA damage signaling and repair in marsupial mammals.

The role of the spatial topology in trophic metacommunities: Species with reduced mobility and total population size.

A central question in ecology is understanding the influence of the spatial topology on the dynamics of a metacommunity. This is not an easy task, as most fragmented ecosystems have trophic interactions involving many species and patches. Recent attempts to solve this challenge have introduced certain simplifying assumptions or focused on a limited set of examples.

Three dimensions of thermolabile sex determination.

The molecular mechanism of temperature-dependent sex determination (TSD) is a long-standing mystery. How is the thermal signal sensed, captured and transduced to regulate key sex genes? Although there is compelling evidence for pathways via which cells capture the temperature signal, there is no known mechanism by which cells transduce those thermal signals to affect gene expression. Here we propose a novel hypothesis we call 3D-TSD (the three dimensions of thermolabile sex determination).

Meiotic chromosome dynamics and double strand break formation in reptiles.

During meiotic prophase I, tightly regulated processes take place, from pairing and synapsis of homologous chromosomes to recombination, which are essential for the generation of genetically variable haploid gametes. These processes have canonical meiotic features conserved across different phylogenetic groups. However, the dynamics of meiotic prophase I in non-mammalian vertebrates are poorly known.

3D chromatin remodelling in the germ line modulates genome evolutionary plasticity.

Chromosome folding has profound impacts on gene regulation, whose evolutionary consequences are far from being understood. Here we explore the relationship between 3D chromatin remodelling in mouse germ cells and evolutionary changes in genome structure. Using a comprehensive integrative computational analysis, we (i) reconstruct seven ancestral rodent genomes analysing whole-genome sequences of 14 species representatives of the major phylogroups, (ii) detect lineage-specific chromosome rearrangements and (iii) identify the dynamics of the structural and epigenetic properties of evolutionary breakpoint regions (EBRs) throughout mouse spermatogenesis.

Fragile, unfaithful and persistent Ys-on how meiosis can shape sex chromosome evolution.

Sex-linked inheritance is a stark exception to Mendel's Laws of Heredity. Here we discuss how the evolution of heteromorphic sex chromosomes (mainly the Y) has been shaped by the intricacies of the meiotic programme. We propose that persistence of Y chromosomes in distantly related mammalian phylogroups can be explained in the context of pseudoautosomal region (PAR) size, meiotic pairing strategies, and the presence of Y-borne executioner genes that regulate meiotic sex chromosome inactivation.

Strategies for meiotic sex chromosome dynamics and telomeric elongation in Marsupials.

During meiotic prophase I, homologous chromosomes pair, synapse and recombine in a tightly regulated process that ensures the generation of genetically variable haploid gametes. Although the mechanisms underlying meiotic cell division have been well studied in model species, our understanding of the dynamics of meiotic prophase I in non-traditional model mammals remains in its infancy. Here, we reveal key meiotic features in previously uncharacterised marsupial species (the tammar wallaby and the fat-tailed dunnart), plus the fat-tailed mouse opossum, with a focus on sex chromosome pairing strategies, recombination and meiotic telomere homeostasis.

Microchromosomes are building blocks of bird, reptile, and mammal chromosomes.

Microchromosomes, once considered unimportant shreds of the chicken genome, are gene-rich elements with a high GC content and few transposable elements. Their origin has been debated for decades. We used cytological and whole-genome sequence comparisons, and chromosome conformation capture, to trace their origin and fate in genomes of reptiles, birds, and mammals.

The Role of Movement Patterns in Epidemic Models on Complex Networks.

In this paper, we analyze the influence of the usual movement variables on the spread of an epidemic. Specifically, given two spatial topologies, we can deduce which topology produces less infected individuals. In particular, we determine the topology that minimizes the overall number of infected individuals.