Paleoecology of a Late Pleistocene Small Mammal Community from Interior Alaska

The material was recovered from exposures, mostly mine cuts through the silt, to reach auriferous gravels at five localities near Fairbanks. The age range of the silts is mainly early Illinoian - present. The vole Microtus gregalis predominates in the fossil assemblage, indicating a habitat above tree line with welldrained soils. M. gregalis, Citellus undulatus and Dicrostonyx torquatus are not now found in the area however, and their extinction is attributed to a rapid reduction of a preferred habitat at the end of the Wisconsin glaciation. Evidence from large mammalian fossils indicates that tree line was lowered at least 300 m during the Wisconsin phase and that most of the mammals were grazers. This supports the small mammalian indications that welldrained alpine meadow expanded almost down to the river flats in interior Alaska during the last two glaciations. The distribution changes and extinction of the small mammals are discussed in relation to the intercontinental communities and interchanges within the Beringian refugium in eastern Siberia and Alaska. Paléoécologie d'un Petit Groupe de Mammifières du Pléistocène Récent de l'Intérieur de l'Alaska. De petits mammifères fossiles des sédiments du Pléistocène récent de l'Alaska intérieur ont servi à l'étude de la paléoécologie de cette région. L'élément dominant de cet assemblage fossile était Microtus gregalis, ce qui indiquerait que la région se trouvait au nord de la limite de la zone forestière et que la faune et la flore qui l'occupaient préféraient les sols bien drainés. Trois espèces fossiles sont maintents absentes de la région : Microtus gregalis, Citellus undulatus et Dicrostonyx torquatus. Leur extinction dans l'Alaska intérieur semble due à une régression rapide de leur habitat préféré, vers la fin de la glaciation wisconsinienne. Cette interprétation écologique du paléogroupe et de son extinction corcorde avec les interprétations que suggèrent les assemblages fossiles de grands mammifères de la même région

Neither warm and moist, nor cold and arid: the ecology of the Mid Upper Palaeolithic

Wetensch. publicatieFaculty of Archeolog

A noncanonical function of cGAMP in inflammasome priming and activation

Recognition of pathogen-associated molecular patterns and danger-associated molecular patterns by host cells is an important step in innate immune activation. The DNA sensor cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) synthase (cGAS) binds to DNA and produces cGAMP, which in turn binds to stimulator of interferon genes (STI N G) to activate IFN-I. Here we show that cGAMP has a noncanonical function in inflammasome activation in human and mouse cells. Inflammasome activation requires two signals, both of which are activated by cGAMP. cGAMP alone enhances expression of inflammasome components through IFN-I, providing the priming signal. Additionally, when combined with a priming signal, cGAMP activates the inflammasome through an AIM2, NLRP3, ASC, and caspase-1 dependent process. These two cGAMP-mediated functions, priming and activation, have differential requirements for STI N G. Temporally, cGAMP induction of IFN-I precedes inflammasome activation, which then occurs when IFN-I is waning. In mice, cGAS/cGAMP amplify both inflammasome and IFN-I to control murine cytomegalovirus. Thus, cGAMP activates the inflammasome in addition to IFN-I, and activation of both is needed to control infection by a DNA virus

Machine Learning in Automated Text Categorization

The automated categorization (or classification) of texts into predefined categories has witnessed a booming interest in the last ten years, due to the increased availability of documents in digital form and the ensuing need to organize them. In the research community the dominant approach to this problem is based on machine learning techniques: a general inductive process automatically builds a classifier by learning, from a set of preclassified documents, the characteristics of the categories. The advantages of this approach over the knowledge engineering approach (consisting in the manual definition of a classifier by domain experts) are a very good effectiveness, considerable savings in terms of expert manpower, and straightforward portability to different domains. This survey discusses the main approaches to text categorization that fall within the machine learning paradigm. We will discuss in detail issues pertaining to three different problems, namely document representation, classifier construction, and classifier evaluation.Comment: Accepted for publication on ACM Computing Survey

Yeast Two-Hybrid: State of the Art

Genome projects are approaching completion and are saturating sequence databases. This paper discusses the role of the two-hybrid system as a generator of hypotheses. Apart from this rather exhaustive, financially and labour intensive procedure, more refined functional studies can be undertaken. Indeed, by making hybrids of two-hybrid systems, customised approaches can be developed in order to attack specific function-related problems. For example, one could set-up a "differential" screen by combining a forward and a reverse approach in a three-hybrid set-up. Another very interesting project is the use of peptide libraries in two-hybrid approaches. This could enable the identification of peptides with very high specificity comparable to "real" antibodies. With the technology available, the only limitation is imagination

Neither warm and moist, nor cold and arid: the ecology of the Mid Upper Palaeolithic

Wetensch. publicatieFaculty of Archeolog