We report here on the derivation of two hES cell lines presumed to be genetically normal (VUB01 and VUB02) and three hES cell lines carrying mutations for myotonic dystrophy type 1 (VUB03_DM1), cystic fibrosis (VUB04_CF) and Huntington disease (VUB05_HD).

An important share of building environmental impacts is embodied in load-bearing structures because of their large material mass and energy-intensive fabrication process. To reduce substantially material consumption and waste caused by the construction industry, structures can be designed and built with reused elements. Structural element reuse involves: element sourcing and deconstruction, reconditioning and transport. As these processes also generate environmental impacts, reuse might not always be preferred over new construction. This paper presents a method to design reticular structures with minimal environmental impact made from reused and new elements. The formulation given in this paper is based on a combination of Life Cycle Assessment (LCA) and discrete structural optimization. The LCA carried out in this work accounts for impacts generated from sourcing reclaimed elements to the assembly of the structure. Structural optimization is subject to stress constraints on element capacity and deflection limits for serviceability. Typical loading scenarios are considered. The method is applied to the design of three single-span steel trusses of different topology subject to 100 simulated stocks of reusable elements that have varying cross-sections and lengths. Benchmarks against minimum-weight solutions made solely from recycled steel show that this method produces structures with up to 56% lower environmental impact. Depending on stock availability, the lowest environmental impact is achieved through a combination of reused and new elements.

Imprinting is a non-Mendelian form of inheritance where epigenetic modifications control mono-allelic expression depending on the parental origin. Methylation of CpG-dinucleotides at differentially methylated regions (DMRs) is one of the best-studied mechanisms directing expression to one specific parental allele. We studied the methylation patterns of the intergenic (IG)-DMR of DLK1 and GTL2. The methylation marks of the IG-DMR were analysed in human gametes, preimplantation embryos, amniocytes and blood of babies born after intracytoplasmic sperm injection (ICSI) and blood from adults using a bisulphite sequencing technique. In oocytes, the IG-DMR was mainly unmethylated while in sperm cells a generally methylated pattern was detected. This germ-line specific methylation mark was maintained in the preimplantation embryos until the second cleavage stage. Afterwards in the preimplantation embryos, intermediate methylation patterns (26 -74% methylation) occurred, which may point to relaxation of the imprints. Intermediate patterns were also present in amniocytes, blood from ICSI babies and adults. We hypothesise that in the early cleavage stage embryo a strict differential methylation pattern is needed for the correct imprint establishment of surrounding imprinted genes. Once correct imprinting of the involved gene(s) is acquired, a more relaxed state of the IG-region is allowed.

The CTG repeat at the 3' untranslated region of the dystrophia myotonica protein kinase (DMPK) gene shows marked intergenerational and somatic instability in patients with myotonic dystrophy (DM1), when the repeat is expanded to more than approximately 55 repeats. Intensive research has yielded some insights into the timing and mechanism of these intergenerational changes: (1) increases in expansion sizes occur during gametogenesis but probably not during meiosis, (2) the marked somatic mosaicism becomes apparent from the 2nd trimester of development onward and increases during adult life, and (3) DNA repair mechanisms are involved. We have performed preimplantation genetic diagnosis for DM1 since 1995, which has given us the unique opportunity to study the expanded CTG repeat in affected embryos and in gametes from affected patients. We were able to demonstrate significant increases in the number of repeats in embryos from female patients with DM1 and in their immature and mature oocytes, whereas, in spermatozoa and embryos from male patients with DM1, smaller increases were detected. These data are in concordance with data on other tissues from adults and fetuses and fill a gap in our knowledge of the behavior of CTG triplet expansions in DM1.

Human embryonic stem cells (hESC) are considered to be an indefinite source of self-renewing cells that can differentiate into all types of cells of the human body and could be used in regenerative medicine, drug discovery and as a model for studying early developmental biology. hESC carrying disease-causing mutations hold promise as a tool to investigate mechanisms involved in the pathogenesis of the disease. In this report, we describe the behaviour of an expanded CTG repeat in the 3' untranslated region of the DMPK gene in VUB03_DM1, a hESC line carrying the myotonic dystrophy type 1 (DM1) mutation compared with the normal CTG repeat in two hESC lines VUB01 and VUB04_CF. Expanded CTG repeats were detected by small amount PCR, small pool PCR and Southern blot analysis in consecutive passages of VUB03_DM1. An important instability of the CTG repeat was detected during prolonged in vitro culture, showing stepwise increases of the repeat number in consecutive passages as well as a higher range of variability. This variability was present in cells of different colonies of the same passage and even within single colonies. The high repeat instability is in contrast to the previously observed stability of the repeat in preimplantation embryos and in fetuses during the first trimester of pregnancy. This in vitro culture of affected hESC represents a valuable model for studying the biology of repeat instability.