Project description:Sleeping tree selection and related behaviours of a family group and a solitary female siamang (Symphalangus syndactylus) were investigated over a 5-month period in northern Sumatra, Indonesia. We performed all day follows, sleeping tree surveys and forest plot enumerations in the field. We tested whether: (1) physical characteristics of sleeping trees and the surrounding trees, together with siamang behaviours, supported selection based on predation risk and access requirements; (2) the preferences of a solitary siamang were similar to those of a family group; and (3) sleeping site locations within home ranges were indicative of home range defence, scramble competition with other groups or other species, or food requirements. Our data showed that (1) sleeping trees were tall, emergent trees with some, albeit low, connectivity to the neighbouring canopy, and that they were surrounded by other tall trees. Siamangs showed early entry into and departure from sleeping trees, and slept at the ends of branches. These results indicate that the siamangs' choice of sleeping trees and related behaviours were strongly driven by predator avoidance. The observed regular reuse of sleeping sites, however, did not support anti-predation theory. (2) The solitary female displayed selection criteria for sleeping trees that were similar to those of the family group, but she slept more frequently in smaller trees than the latter. (3) Siamangs selected sleeping trees to avoid neighbouring groups, monopolise resources (competition), and to be near their last feeding tree. Our findings indicate selectivity in the siamangs' use of sleeping trees, with only a few trees in the study site being used for this purpose. Any reduction in the availability of such trees might make otherwise suitable habitat unsuitable for these highly arboreal small apes.
Project description:Chromosome rearrangements in small apes are up to 20 times more frequent than in most mammals. Because of their complexity, the full extent of chromosome evolution in these hominoids is not yet fully documented. However, previous work with array painting, BAC-FISH and selective sequencing in two of the four karyomorphs, has shown that high resolution methods can precisely define chromosome breakpoints and map the complex flow of evolutionary chromosome rearrangements. Here we use these tools to precisely define the rearrangements that have occurred in the remaining two karyomorphs, genera Symphalangus (2n=50), and Hoolock (2n=38). This research provides the most comprehensive insight into the evolutionary origins of chromosome rearrangements involved in transforming small apes genome. Bioinformatics analyses of the human-gibbon synteny breakpoints revealed association with transposable elements and segmental duplications providing some insight into the mechanisms that might have promoted rearrangements in small apes. In the near future, the comparison of gibbon genome sequences will provide novel insights to test hypotheses concerning the mechanisms of chromosome evolution. The precise definition of synteny block boundaries and orientation, chromosomal fusions, and centromere repositioning event presented here will facilitate genome sequence assembly for these close relatives of humans.
Project description:Primary objectives: The primary objective is to investigate circulating tumor DNA (ctDNA) via deep sequencing for mutation detection and by whole genome sequencing for copy number analyses before start (baseline) with regorafenib and at defined time points during administration of regorafenib for treatment efficacy in colorectal cancer patients in terms of overall survival (OS).
Primary endpoints: circulating tumor DNA (ctDNA) via deep sequencing for mutation detection and by whole genome sequencing for copy number analyses before start (baseline) with regorafenib and at defined time points during administration of regorafenib for treatment efficacy in colorectal cancer patients in terms of overall survival (OS).
Project description:Small apes (family Hylobatidae), encompassing gibbons and siamangs, occupy a pivotal evolutionary position within the hominoid lineage, bridging the gap between great apes and catarrhine monkeys. Although they possess distinctive genomic and phenotypic features—such as rapid chromosomal rearrangements and adaptations for brachiation—functional genomic studies on small apes have been hindered by the limited availability of biological samples and developmental models. Here, we address this gap by successfully reprogramming primary skin fibroblasts from three small ape species: lar gibbons (Hylobates lar), Abbott’s gray gibbons (Hylobates abbotti), and siamangs (Symphalangus syndactylus). Using Sendai virus-based stealth RNA vectors, we generated 31 reprogrammed cell lines, five of which were developed into transgene-free induced pluripotent stem cells (iPSCs). These iPSCs displayed canonical features of primed pluripotency, both morphologically and molecularly, consistent with other primate iPSCs. Directed differentiation experiments confirmed the capacity of small ape iPSCs to generate cells representing all three germ layers. Particularly, the successful differentiation into limb bud mesoderm cells underscores their utility in investigating the molecular and developmental mechanisms unique to small ape forelimb evolution. Transcriptomic profiling of small ape iPSCs revealed significant upregulation of pluripotency-associated genes, alongside elevated expression of transposable elements. Remarkably, LAVA retrotransposons—a class of elements specific to small apes—exhibited particularly high expression levels in these cells. Comparative transcriptomic analyses with iPSCs from humans, great apes, and macaques identified evolutionary trends and clade-specific gene expression signatures. These signatures highlighted processes linked to genomic stability and cell death, providing insights into small ape-specific adaptations. This study positions small ape iPSCs as a transformative tool for advancing functional genomics and evolutionary developmental biology. By facilitating detailed investigations into hominoid genome evolution and phenotypic diversification, this system bridges critical gaps in comparative research, enabling deeper exploration of the genetic and cellular underpinnings of small ape-specific traits.