Reconstructing the Forest of Lineage Trees of Diverse Bacterial Communities Using Bio-inspired Image Analysis

Cell segmentation and tracking allow us to extract a plethora of cell attributes from bacterial time-lapse cell movies, thus promoting computational modeling and simulation of biological processes down to the single-cell level. However, to analyze successfully complex cell movies, imaging multiple interacting bacterial clones as they grow and merge to generate overcrowded bacterial communities with thousands of cells in the field of view, segmentation results should be near perfect to warrant good tracking results. We introduce here a fully automated closed-loop bio-inspired computational strategy that exploits prior knowledge about the expected structure of a colony's lineage tree to locate and correct segmentation errors in analyzed movie frames. We show that this correction strategy is effective, resulting in improved cell tracking and consequently trustworthy deep colony lineage trees. Our image analysis approach has the unique capability to keep tracking cells even after clonal subpopulations merge in the movie. This enables the reconstruction of the complete Forest of Lineage Trees (FLT) representation of evolving multi-clonal bacterial communities. Moreover, the percentage of valid cell trajectories extracted from the image analysis almost doubles after segmentation correction. This plethora of trustworthy data extracted from a complex cell movie analysis enables single-cell analytics as a tool for addressing compelling questions for human health, such as understanding the role of single-cell stochasticity in antibiotics resistance without losing site of the inter-cellular interactions and microenvironment effects that may shape it

Vaade inimese Y kromosoomile – fülogenees, populatsiooni dünaamika ja asutajasündmused

Väitekirja elektrooniline versioon ei sisalda publikatsiooneRahvastikusündmused on jätnud oma jälje iga inimese genoomi. Täna suudame neid ’lugeda’ nii praegu elavate kui juba ammu surnud inimeste geneetilisest materjalist. Y-kromosoom on eriline genoomi osa, mis pärandub edasi vaid mööda isaliini, kõikide maailma isaliinide omavahlelist sugulust näitab nende ‘sugupuu’. Täna saame ka Y-kromosoomilt ohtralt DNA-lugemeid, mis võimaldavad võrratult täpsemalt hinnata inimese isaliinide mitmekesisust ning harude lahknemisaegu isaliinide puul. Doktoritöös uuriti mineviku rahvastikusündmusi peamiselt inimese Y-kromosoomi andmeid analüüsides. Töö tulemused näitasid, et inimese kõikide teadaolevate isaliinide viimane ühine eellane elas Aafrikas umbes 250 tuhat aastat tagasi, paljude liinide arvukuse kasv toimus aga viimase 15 tuhande aasta sees. Üllatuslikult leidsime ka, et 4–8 tuhat aastat tagasi kahanes järsult järglasi saavate meeste suhteline arv, samas kui naistel see arv ei muutunud. Kuna sigivate meeste arvukus vähenes samal ajal, kui muutusid inimeste eluviisid – mindi üle küttimiselt ja koriluselt põlluharimisele, võisid need kultuurilised muutused mõjutada meeste reproduktiivkäitumist. Lisaks näitasime, et Lõuna-Siberist pärit Baikali-äärse 24 000 aasta vanuse ülempaleoliitilise Malta kultuuri esindaja ema- ja isaliin ei ole tüüpilised tänased seal piirkonnas levinud Ida-Euraasia liinid, näidates geneetilise pärandi olulist muutumist läbi aja. Asutajasündmused, mil uus rahvakild tekib mingi algse grupi väikesest alamhulgast, jätavad uue grupi geneetilisse pärandisse iseloomuliku jälje. Neid analüüsisime Euroopa romi ja aškenaasi leviidi meeste seas. Lõuna-Aasia päritolu H1a1-M82 tüüpi isaliin on levinud ka Euroopa romide seas, viidates nende algkodule. Romide liinidele kõige sarnasemad on Loode- ja Põhja-India meeste seas levinud variandid, viidates võimalikule Romide päritolupiirkonnale. Tüüpiline aškenaasi leviitide isaliin R1a-Y2619 on kõige tõenäolisemalt pärit Lähis-Idast. Näitasime, et see kuulus aškenaasi leviitide asutajaliinide hulka, kuid selle levik oli seotud pigem aškenaasi juutide populatsiooni üldise laienemisega.Demographic processes have left their traces into every human genome. Today we can ‘read’ them from the genetic material of people living now and those passed away long ago. Mitochondrial DNA and Y chromosome (chrY) are parts of the genome that pass on through maternal and paternal lines. The relationships of all these lineages in the world are captured in a global ‘family tree’ of maternal or paternal lineages. Just recently it became possible to attain high numbers of sequencing reads also from chrY. This enables to assess the variation of human paternal lineages and date their splits on the tree with unmatched precision. This thesis investigates the past demographic events mainly by analysing the sequencing datasets of human chrY. We showed that the most common ancestor of all known paternal lineages lived in Africa about 250 thousand years ago (kya) and many of the now widespread lineages started to expand 15 kya. Then, 4–8 kya the relative number of males who had offspring (Nm) decreased drastically, while in females it did not change. Since the decrease of Nm coincided with the changes of lifestyle from hunting and gathering to farming, the decrease in the number of breeding males could have been caused by cultural forces that influence the reproductive behaviour of men. The maternal and paternal lineages of a southern Siberian 24,000 years-old Upper Palaeolithic individual from near Lake Baikal are not typical East Eurasian lineages found in the area today. This testifies for population changes affecting the genetic make-up of the people living in that region. Founder events during which a new population forms as a small subset of an initial group, leave distinct traces into the genomic legacy of the newly formed group. We analysed these traces in the paternal gene pool of European Roma and Ashkenazi Levites. H1a1a-M82 is a paternal lineage carried by 12% of South Asian men. The same lineage is spread among European Roma whose variants have closest relations to men from north western and northern India, pointing to their potential place of origin. The main lineage among Ashkenazi Levites, R1a-Y2619, originates in the Near East and it was probably carried by the first founders of the Ashkenazi Levites. The increase in numbers of carriers of this lineage was not an event specific to Levites, but part of the general Ashkenazi Jewish expansion

Scientific drilling projects in ancient lakes: integrating geological and biological histories

Sedimentary sequences in ancient or long-lived lakes can reach several thousands of meters in thickness and often provide an unrivalled perspective of the lake's regional climatic, environmental, and biological history. Over the last few years, deep drilling projects in ancient lakes became increasingly multi- and interdisciplinary, as, among others, seismological, sedimentological, biogeochemical, climatic, environmental, paleontological, and evolutionary information can be obtained from sediment cores. However, these multi- and interdisciplinary projects pose several challenges. The scientists involved typically approach problems from different scientific perspectives and backgrounds, and setting up the program requires clear communication and the alignment of interests. One of the most challenging tasks, besides the actual drilling operation, is to link diverse datasets with varying resolution, data quality, and age uncertainties to answer interdisciplinary questions synthetically and coherently. These problems are especially relevant when secondary data, i.e., datasets obtained independently of the drilling operation, are incorporated in analyses. Nonetheless, the inclusion of secondary information, such as isotopic data from fossils found in outcrops or genetic data from extant species, may help to achieve synthetic answers. Recent technological and methodological advances in paleolimnology are likely to increase the possibilities of integrating secondary information, e.g., through molecular dating of molecular phylogenies. Some of the new approaches have started to revolutionize scientific drilling in ancient lakes, but at the same time, they also add a new layer of complexity to the generation and analysis of sediment core data. The enhanced opportunities presented by new scientific approaches to study the paleolimnological history of these lakes, therefore, come at the expense of higher logistic, communication, and analytical efforts. Here we review types of data that can be obtained in ancient lake drilling projects and the analytical approaches that can be applied to empirically and statistically link diverse datasets for creating an integrative perspective on geological and biological data. In doing so, we highlight strengths and potential weaknesses of new methods and analyses, and provide recommendations for future interdisciplinary deep drilling projects

White Paper 2: Origins, (Co)Evolution, Diversity & Synthesis Of Life

Publicado en Madrid, 185 p. ; 17 cm.How life appeared on Earth and how then it diversified into the different and currently existing forms of life are the unanswered questions that will be discussed this volume. These questions delve into the deep past of our planet, where biology intermingles with geology and chemistry, to explore the origin of life and understand its evolution, since “nothing makes sense in biology except in the light of evolution” (Dobzhansky, 1964). The eight challenges that compose this volume summarize our current knowledge and future research directions touching different aspects of the study of evolution, which can be considered a fundamental discipline of Life Science. The volume discusses recent theories on how the first molecules arouse, became organized and acquired their structure, enabling the first forms of life. It also attempts to explain how this life has changed over time, giving rise, from very similar molecular bases, to an immense biological diversity, and to understand what is the hylogenetic relationship among all the different life forms. The volume further analyzes human evolution, its relationship with the environment and its implications on human health and society. Closing the circle, the volume discusses the possibility of designing new biological machines, thus creating a cell prototype from its components and whether this knowledge can be applied to improve our ecosystem. With an effective coordination among its three main areas of knowledge, the CSIC can become an international benchmark for research in this field

ACARORUM CATALOGUS IX. Acariformes, Acaridida, Schizoglyphoidea (Schizoglyphidae), Histiostomatoidea (Histiostomatidae, Guanolichidae), Canestrinioidea (Canestriniidae, Chetochelacaridae, Lophonotacaridae, Heterocoptidae), Hemisarcoptoidea (Chaetodactylidae, Hyadesiidae, Algophagidae, Hemisarcoptidae, Carpoglyphidae, Winterschmidtiidae)

The 9th volume of the series Acarorum Catalogus contains lists of mites of 13 families, 225 genera and 1268 species of the superfamilies Schizoglyphoidea, Histiostomatoidea, Canestrinioidea and Hemisarcoptoidea. Most of these mites live on insects or other animals (as parasites, phoretic or commensals), some inhabit rotten plant material, dung or fungi. Mites of the families Chetochelacaridae and Lophonotacaridae are specialised to live with Myriapods (Diplopoda). The peculiar aquatic or intertidal mites of the families Hyadesidae and Algophagidae are also included.Publishe

Reticulate Evolution: Symbiogenesis, Lateral Gene Transfer, Hybridization and Infectious heredity

info:eu-repo/semantics/publishedVersio

Molecular biogeography of grasses and tropical grasslands

Les graminées (Poaceae) sont une très grande famille cosmopolite de plantes. Dans la thèse présentée ici, j'ai utilisé des méthodes moléculaires pour analyser leur histoire biogéographique. Le premier chapitre s'intéresse aux déterminants de la dispersion dans la sous-tribu tempérée Loliinae. La distance apparaît comme le facteur dominant. Le deuxième chapitre présente une analyse des origines des graminées de Madagascar. Les résultats montrent deux grandes radiations in situ de graminées C3 et une immigration répétée de graminées C4, soutenant l'existence de savanes malgaches avant la présence humaine. Le troisième chapitre résout la position d'une lignée C3 d'Asie à l'aide de la phylogénomique, avec des implications pour l'évolution de la photosynthèse C4 et des savanes tropicales. Le quatrième chapitre présente une méthode de méta-barcoding pour l'analyse des communautés d'endophytes fongiques associées aux graminées à Madagascar, démontrant des limitations méthodologiques.Grasses (Poaceae) are a large, cosmopolitan plant family. In this dissertation, I used molecular methods to study their biogeographic history. The first chapter focuses on determinants of lineage dispersal in the temperate subtribe Loliinae, with distance found to be the dominant factor. The second chapter analyses the origins of Madagascar's grass flora. Two large in situ radiations of C3 grasses were found while C4 grasses immigrated more frequently and support the pre-human presence of grasslands in Madagascar. The third chapter resolves relationships of an Asian C3 lineage using phylogenomic methods, with implications for C4 photosynthesis evolution and the assembly of tropical grasslands. The fourth and final chapter developed a metabarcoding method for the analysis of fungal endophyte communities associated to grasses in Madagascar, with results highlighting methodological limitations

The diversity of key anabolic genes in antarctic hypolithons

>Magister Scientiae - MScAntarctica is known for its pristine environments. A variety of unsuitable environmental conditions were once thought to render the continent unsuitable for sustaining life. However, metagenomic data have revealed a wealth of species diversity in a range of biotopes.Hypolithons, photosynthetic communities which live under translucent rocks in climatically extreme environments, are an important input source for both carbon (C) and nitrogen (N) in this hyperarid desert environment. Microbial contribution to biogeochemical cycling resulting in fixation of both C and N remains poorly understood. Moreover, there is a reported close interplay between both cycles, with nitrogen being reported to be a limiting factor in carbon assimilation.In this study the diversity of C and N fixing organisms was investigated by using the cbbL and nifH genes as phylogenetic and functional markers. High Molecular weight metagenomic DNA and RNA was extracted from hypolithons. PCR amplification was carried out using cbbL (800 bp for red-like, 1,100 bp for green-like) and nifH (360 bp) gene specific primers.Resultant PCR products were used to construct libraries which were screened for correct sized inserts. Restriction Fragment Length Polymorphism (RFLP) was used to de-replicate clones prior to sequencing. Phylogenetic positions from both clone libraries were established by aligning nucleotide sequences and constructing similarity trees using NJ clustering methods.BLASTn results indicated the presence of previously uncultured organisms which contain cbbL and nifH genes. BLASTn results were characterized by low percentages of maximum identity (typically <95%), a potential indicator of novel taxa. Sequences from respective libraries clustered with cyanobacteria such as Nostoc, Scytonema, and Tolypothrix and α-, β-, and γ-Proteobacteria such as Azotobacter, Agrobacterium and Mesorhizobium. Generally sequence results indicate a largely homogenous, being dominated by specific taxa. Each group may contain potential keystone species, essential for both biogeochemical cycling in oligotrophic environment