This extensive paper presents a comprehensive investigation into the ancestry and evolution of the extinct dire wolf (Aenocyon dirus), utilizing paleogenome analyses of two well-preserved specimens. The findings reveal that the dire wolf lineage arose from an admixture of two distinct ancestral lineages, one close to South American canids and another sister to the clade that includes the gray wolf, coyote, and dole. The study also identified genes that experienced diversifying selection in the dire wolf, possibly related to its large size and unique reproductive biology. Furthermore, an iterative methodology is described for reconstructing ancient paleogenomes, mitigating the reference bias inherent when working with degraded DNA and diverged species. Overall, the research clarifies the phylogenetic position of the dire wolf within the family Canidae and underscores the importance of post-speciation gene flow in canid evolution.

The study investigated the molecular basis of the convergent evolution of the chamber eye between octopuses and humans through comparative gene expression analysis. The researchers identified a significant number of genes commonly expressed in the eyes of both species, despite their independent evolution. Furthermore, they determined that a large proportion of these common genes existed in the common ancestor of bilaterians, suggesting that similarity in ancestral gene expression may be critical for the convergence of the chamber eye.

Ogura, A., Ikeo, K., & Gojobori, T. (2004). Comparative Analysis of Gene Expression for Convergent Evolution of Camera Eye Between Octopus and Human. Genome Research, 14(8), 1555-1561. https://doi.org/10.1101/gr.2268104

In this groundbreaking paper, Stanley B. Prusiner presents evidence that the causative agent of scrapie, a neurodegenerative disease in sheep and goats, is an infectious protein particle, which he calls a "prion." The resistance of the prion to procedures that modify nucleic acids, its heterogeneity in size and charge, and its partial purification are described. The hypothetical mechanisms of prion replication are discussed, considering the possibility that it lacks nucleic acid, and its possible involvement in other human neurodegenerative diseases is explored. The research proposes a new model for infectious agents, challenging the central dogma of molecular biology. Finally, the implications of understanding the structure and replication of prions for medicine are highlighted.

Prusiner, S. B. (1982). Novel proteinaceous infectious particles cause scrapie. Science, 216(4542), 136-144.

Polymerase chain reaction (PCR) would not be the same without the discovery of Taq polymerase, a thermostable enzyme crucial for its efficiency and specificity. The steps of PCR (denaturation, hybridization, and extension) are explained, the effect of temperature on each step, and the advantages and limitations of Taq polymerase with other polymerases are compared. Finally, the various applications of PCR in different fields, including molecular biology, medicine and forensic science, are presented.

The paper presents Celera Genomics' work on human genome sequencing, detailing its methods, including shotgun sequencing and genome assembly. The process of building DNA libraries, data analysis, and assembly strategy is described, using two independent approaches. The paper also discusses gene prediction, identification of single nucleotide polymorphisms (SNPs), and a comparison with other eukaryotic genomes, highlighting expansions of human-specific protein families. Finally, an overview of the predicted genes and their involvement in complex biological processes is offered.

Venter, J. C., Adams, M. D., Myers, E. W., Li, P. W., Mural, R. J., Sutton, G. G., ... & Waterston, R. H. (2001). The sequence of the human genome. Science, 291(5507), 1304-1351.

The sources analyze global contamination by PFAS, persistent chemicals that accumulate in the environment and pose a threat to human health and ecosystems. It is argued that the persistence of PFAS exceeds a new planetary limit, due to its levels in rainwater, soils and surface waters that exceed safety guidelines. Health impacts, such as immune suppression, are detailed and mitigation strategies are proposed, including restricting their use and developing safer alternatives. Finally, a timeline of key events related to the understanding and regulation of PFAS is presented.

Cousins, I. T., Johansson, J. H., Salter, M. E., Sha, B., & Scheringer, M. (2022). Fuera del Espacio Operativo Seguro de un Nuevo Límite Planetario para Sustancias Per- y Polifluoroalquiladas (PFAS). Environmental Science & Technology, 56(15), 11172–11179. https://doi.org/10.1021/acs.est.2c02765

The text features excerpts from the first edition of Charles Darwin's On the Origin of Species. Darwin expounded his theory of natural selection, arguing that species evolve through the gradual accumulation of favorable variations. The laws of variation are discussed, including the influence of external conditions, the use and disuse of organs, and the correlation of growth. Sexual selection and the imperfection of the geological record are also discussed, presenting examples of species variability and difficulties in classification. Finally, Darwin addresses the geographical distribution of species and the importance of migration.

Darwin, C. (1859). On the origin of species.

The article explores a new method for discovering new natural products from uncultivated soil microorganisms. It focuses on the concept of cloning the metagenome, that is, the set of genomes of the soil microflora, to access its biosynthetic machinery. This approach uses bacterial artificial chromosome (BAC) vectors to clone large fragments of DNA directly from the soil in E. coli, then the resulting clones are examined for biological activity. The authors argue that this technique overcomes the limitations of traditional farming methods and offers quick and efficient access to soil chemical diversity. Finally, the need for interdisciplinary collaboration between biologists and chemists to make the most of this potential is highlighted.

Handelsman, J., Rondon, M. R., Brady, S. F., Clardy, J., & Goodman, R. M. (1998). Molecular biological access to the chemistry of unknown soil microbes: A new frontier for natural products. Chemistry & Biology, 5(10), R245-R249. https://doi.org/10.1016/S1074-5521(98)90108-9