North Sea oil and genuine saving in the Scottish economy

The World Bank has published estimates of sustainability of consumption paths by adjusting saving rates to take account of the depletion of non-renewable resources. During the period of North Sea oil production Scotland has been in a fiscal union with the rest of the UK. The present paper adjusts the World Bank data to produce separate genuine saving estimates for Scotland and the rest of the UK for 1970-2009, based on a ‘derivation’ principle for oil revenues. The calculations indicate that Scotland has had a negative genuine saving rate for most of the period of exploitation of North Sea oil resources, with genuine saving being positive in the rest of the UK during this period

Molecular Genetic Changes During Tumour Progression in Mouse Skin

This thesis describes the development of a model to analyse the genetic changes associated with tumour progression in mouse skin. Tumours were induced in F1 hybrid mice, thereby permitting the use of heterozygous DNA markers (restriction fragment length polymorphisms) to determine the role of allele loss in papilloma and carcinoma development. Frequently, initiation of mouse skin carcinogenesis involves H-ras activation. This gene is located on mouse chromosome 7. The F1 hybrid tumour model was used to demonstrate that tumours with this mutation also show loss of heterozygosity (LOH) or imbalance of alleles on chromosome 7 at a very high frequency. Thus LOH may indicate the presence of an oncogene, although it is often equated with tumour suppressor gene loss. Most frequently the alterations involved non-disjunction, but in some cases mitotic recombination or deletion was detected. These gross chromosome changes were not observed in mouse skin tumours lacking activated H-ras. Thus, it is clear that the initiation event can influence the type of alterations which occur at later stages of tumour progression. In the majority of cases, gross chromosome 7 changes result in an increased copy number of mutant H-ras and under-representation or loss of the normal allele, indicating that mutant H-ras is involved in both the initiation and progression of mouse skin tumours. It may be that elevation of the mutant signal is required to overcome a suppressive effect of the normal allele. In addition, because elevation of mutant H-ras gene copy number occurs by gross chromosomal mechanisms, it is possible that another chromosome 7 gene is also involved in tumour progression. In support of this, mitotic recombination or deletion was detected distal to H-ras in 4/26 of the chemically induced tumours with activated H-ras. In addition, a chromosome 7 alteration was detected in a v-H-ras initiated tumour, further evidence that a gene other than H-ras on this chromosome is involved in tumour progression. Human tumours frequently demonstrate LOH at the chromosomal region 11p 15.5, which is syntenic with the part of mouse chromosome 7 that encompasses the H-ras locus. Thus, the homologue of a tumour suppressor gene in this region of human chromosome 11 may be involved in mouse skin tumour development. The Wilms' tumour locus, also on human 11p, is on mouse chromosome 2. RFLP analyses provided no evidence that this gene has a role in mouse skin tumorigenesis. The non-random nature of chromosome 7 changes was supported by the low frequency of alterations on chromosomes 2 and 11. Two carcinomas did show LOH of a marker on the latter. Interestingly, this chromosome contains a region homologous to human chromosome 17p, which is involved in colorectal cancer. Minisatellite analysis also supported the non-random nature of chromosome 7 changes. Loss or rearrangement of minisatellite bands tended to involve hypervariable loci, suggesting that these were random rearrangements at unstable loci. In some human cancers genomic imprinting influences the direction of allele loss on 11p. However, this did not appear to be the case with LOH on chromosome 7 in mouse skin carcinomas. The parental strain also did not influence which alleles were under-represented in these tumours. Some important differences were detected between the genetic changes associated with carcinomas induced by initiation/promotion and those seen in carcinomas obtained by repeated carcinogen treatment. A similar proportion of MNNG/TPA and MNNG/MNNG carcinomas were positive for mutant H-ras. However, whereas non-disjunction of chromosome 7 had also occurred in the former, no chromosome 7 changes were detected in carcinomas induced by repeated MNNG treatment. This carcinogen may remove the need for additional chromosome 7 changes by mutating the gene(s) affected by these events in TPA-promoted tumours, or by altering entirely separate loci. In contrast, tumours induced with repeated DMBA treatment which were positive for activated H-ras also had chromosome 7 changes. However, the frequency of events such as mitotic recombination or deletion was much higher in these tumours than in carcinomas induced by an initiation/promotion regime. The major difference between DMBA/DMBA carcinomas and DMBA/TPA carcinomas was that the latter contained a much higher proportion of tumours which lacked activated H-ras. Thus it appears that repeated DMBA treatment stimulates the growth of initiated cells which are insensitive to TPA. Analysis of papillomas showed that gross chromosome 7 changes occur at a premalignant stage of tumorigenesis. This may suggest a tumour promoter-related genetic effect

Retinoblastoma, an Inside Job

Why are some cell types more prone to transformation than others? In this issue, Xu et al. (2009) show that retinoblastoma cells co-opt several intrinsic features of cone photoreceptors for their survival and growth

Rb-Mediated Neuronal Differentiation through Cell-Cycle–Independent Regulation of E2f3a

It has long been known that loss of the retinoblastoma protein (Rb) perturbs neural differentiation, but the underlying mechanism has never been solved. Rb absence impairs cell cycle exit and triggers death of some neurons, so differentiation defects may well be indirect. Indeed, we show that abnormalities in both differentiation and light-evoked electrophysiological responses in Rb-deficient retinal cells are rescued when ectopic division and apoptosis are blocked specifically by deleting E2f transcription factor (E2f) 1. However, comprehensive cell-type analysis of the rescued double-null retina exposed cell-cycle–independent differentiation defects specifically in starburst amacrine cells (SACs), cholinergic interneurons critical in direction selectivity and developmentally important rhythmic bursts. Typically, Rb is thought to block division by repressing E2fs, but to promote differentiation by potentiating tissue-specific factors. Remarkably, however, Rb promotes SAC differentiation by inhibiting E2f3 activity. Two E2f3 isoforms exist, and we find both in the developing retina, although intriguingly they show distinct subcellular distribution. E2f3b is thought to mediate Rb function in quiescent cells. However, in what is to our knowledge the first work to dissect E2f isoform function in vivo we show that Rb promotes SAC differentiation through E2f3a. These data reveal a mechanism through which Rb regulates neural differentiation directly, and, unexpectedly, it involves inhibition of E2f3a, not potentiation of tissue-specific factors

CpG Island microarray probe sequences derived from a physical library are representative of CpG Islands annotated on the human genome

An effective tool for the global analysis of both DNA methylation status and protein–chromatin interactions is a microarray constructed with sequences containing regulatory elements. One type of array suited for this purpose takes advantage of the strong association between CpG Islands (CGIs) and gene regulatory regions. We have obtained 20 736 clones from a CGI Library and used these to construct CGI arrays. The utility of this library requires proper annotation and assessment of the clones, including CpG content, genomic origin and proximity to neighboring genes. Alignment of clone sequences to the human genome (UCSC hg17) identified 9595 distinct genomic loci; 64% were defined by a single clone while the remaining 36% were represented by multiple, redundant clones. Approximately 68% of the loci were located near a transcription start site. The distribution of these loci covered all 23 chromosomes, with 63% overlapping a bioinformatically identified CGI. The high representation of genomic CGI in this rich collection of clones supports the utilization of microarrays produced with this library for the study of global epigenetic mechanisms and protein–chromatin interactions. A browsable database is available on-line to facilitate exploration of the CGIs in this library and their association with annotated genes or promoter elements

Hypophosphorylated pRb knock-in mice exhibit hallmarks of aging and vitamin C-preventable diabetes

Despite extensive analysis of pRB phosphorylation in vitro, how this modification influences development and homeostasis in vivo is unclear. Here, we show that homozygous Rb∆K4 and Rb∆K7 knock-in mice, in which either four or all seven phosphorylation sites in the C-terminal region of pRb, respectively, have been abolished by Ser/Thr-to-Ala substitutions, undergo normal embryogenesis and early development, notwithstanding suppressed phosphorylation of additional upstream sites. Whereas Rb∆K4 mice exhibit telomere attrition but no other abnormalities, Rb∆K7 mice are smaller and display additional hallmarks of premature aging including infertility, kyphosis, and diabetes, indicating an accumulative effect of blocking pRb phosphorylation. Diabetes in Rb∆K7 mice is insulin-sensitive and associated with failure of quiescent pancreatic β-cells to re-enter the cell cycle in response to mitogens, resulting in induction of DNA damage response (DDR), senescence-associated secretory phenotype (SASP), and reduced pancreatic islet mass and circulating insulin level. Pre-treatment with the epigenetic regulator vitamin C reduces DDR, increases cell cycle re-entry, improves islet morphology, and attenuates diabetes. These results have direct implications for cell cycle regulation, CDK-inhibitor therapeutics, diabetes, and longevity

The NEMP family supports metazoan fertility and nuclear envelope stiffness.

Human genome-wide association studies have linked single-nucleotide polymorphisms (SNPs) in NEMP1 (nuclear envelope membrane protein 1) with early menopause; however, it is unclear whether NEMP1 has any role in fertility. We show that whole-animal loss of NEMP1 homologs in Drosophila, Caenorhabditis elegans, zebrafish, and mice leads to sterility or early loss of fertility. Loss of Nemp leads to nuclear shaping defects, most prominently in the germ line. Biochemical, biophysical, and genetic studies reveal that NEMP proteins support the mechanical stiffness of the germline nuclear envelope via formation of a NEMP-EMERIN complex. These data indicate that the germline nuclear envelope has specialized mechanical properties and that NEMP proteins play essential and conserved roles in fertility

Noninvasive, In Vivo Assessment of Mouse Retinal Structure Using Optical Coherence Tomography

BACKGROUND: Optical coherence tomography (OCT) is a novel method of retinal in vivo imaging. In this study, we assessed the potential of OCT to yield histology-analogue sections in mouse models of retinal degeneration. METHODOLOGY/PRINCIPAL FINDINGS: We achieved to adapt a commercial 3(rd) generation OCT system to obtain and quantify high-resolution morphological sections of the mouse retina which so far required in vitro histology. OCT and histology were compared in models with developmental defects, light damage, and inherited retinal degenerations. In conditional knockout mice deficient in retinal retinoblastoma protein Rb, the gradient of Cre expression from center to periphery, leading to a gradual reduction of retinal thickness, was clearly visible and well topographically quantifiable. In Nrl knockout mice, the layer involvement in the formation of rosette-like structures was similarly clear as in histology. OCT examination of focal light damage, well demarcated by the autofluorescence pattern, revealed a practically complete loss of photoreceptors with preservation of inner retinal layers, but also more subtle changes like edema formation. In Crb1 knockout mice (a model for Leber's congenital amaurosis), retinal vessels slipping through the outer nuclear layer towards the retinal pigment epithelium (RPE) due to the lack of adhesion in the subapical region of the photoreceptor inner segments could be well identified. CONCLUSIONS/SIGNIFICANCE: We found that with the OCT we were able to detect and analyze a wide range of mouse retinal pathology, and the results compared well to histological sections. In addition, the technique allows to follow individual animals over time, thereby reducing the numbers of study animals needed, and to assess dynamic processes like edema formation. The results clearly indicate that OCT has the potential to revolutionize the future design of respective short- and long-term studies, as well as the preclinical assessment of therapeutic strategies

Rod and cone degeneration in the rd mouse is p53 independent

Retinitis pigmentosa (RP) is a multigene disorder associated with the loss of photoreceptors Numerous RP genes have been identified, several of which participate in the visual transduction cascade RP related photoreceptor cell death occurs by apoptosis One gene that could mediate photoreceptor death is the pro-apoptotic transcription factor p53 METHODS Breeding and genotyping: This study was carried out in accordance with the requirements of the Animals for Research Act, the Guidelines and Policies of the Canadian Council on Animal Care as well as the Institutional (UHN) Animal Care Committee. rd mice and p53-/-mice, were obtained from Jackson laboratories. The rd mutation was on a C57BL/6J background. The p53-/-background was predominantly C57BL/ 6J, although a small percentage (<2%) was 129/SV. These mice were interbred to obtain double heterozygotes, which were further bred to obtain rd/rd; p53+/+, and rd/rd; p53-/-mice. Genotyping was performed on tail DNA using the polymerase chain reaction (PCR). The rdgenotype can be diagnosed either by a DdeI restriction digest that detects a nonsense codon [3], or by amplification of an integrated retrovirus [4]. W