Mats Lindeskog

Expression of human endogenous retroviral sequences in peripheral blood mononuclear cells of healthy individuals.

The polymerase chain reaction was used to detect expression of retroviral sequences with oligonucleotide primers derived from conserved regions of the retroviral genome. Four primer pairs derived from gag and one from pol were used in amplification of reverse-transcribed total RNA prepared from peripheral blood mononuclear cells of seven blood donors. The amplification pattern was the same from each of the seven samples. Sequencing of cloned amplification products revealed that at least three subclasses of sequences related to the human endogenous retroviruses (HERV) RTVL-H, HERV-E and HERV-K, are expressed in peripheral blood mononuclear cells of healthy individuals. This has not been previously reported.

Diversity of human endogenous retrovirus class II-like sequences.

Class II human endogenous retroviruses (HERVs), often referred to as mouse mammary tumour virus (MMTV)-like or HERV-K elements, have similarities to several animal infectious retroviruses. Single clones from each of nine class II HERV groups (NMWV 1 to NMWV 9), isolated from a human breast cancer cell genomic library, were sequenced over a 244 bp stretch of the conserved reverse transcriptase region. These sequences were aligned to related exogenous and endogenous retroviruses and a phylogenetic tree was constructed. Sequences with more than 80% identity were considered as members of one group and we report here that the class II HERV family consists of at least ten groups. Three of the sequenced clones, from groups NMWV 3, 7 and 9, could not be related to any other previously identified elements and constituted their own groups. NMWV 8 had no similarity to any retroviral sequences in the sequenced region and is so far considered to be non-retroviral.

Simulated carbon emissions from land-use change are substantially enhanced by accounting for agricultural management

It is over three decades since a large terrestrial carbon sink (S-T) was first reported. The magnitude of the net sink is now relatively well known, and its importance for dampening atmospheric CO2 accumulation, and hence climate change, widely recognised. But the contributions of underlying processes are not well defined, particularly the role of emissions from land-use change (E-LUC) versus the biospheric carbon uptake (S-L; S-T. = S-L - E-LUC). One key aspect of the interplay of E-LUC and SL is the role of agricultural processes in land-use change emissions, which has not yet been clearly quantified at the global scale. Here we assess the effect of representing agricultural land management in a dynamic global vegetation model. Accounting for harvest, grazing and tillage resulted in cumulative E-LUC since 1850 ca. 70% larger than in simulations ignoring these processes, but also changed the timescale over which these emissions occurred and led to underestimations of the carbon sequestered by possible future reforestation actions. The vast majority of Earth system models in the recent IPCC Fifth Assessment Report omit these processes, suggesting either an overestimation in their present-day ST, or an underestimation of SL, of up to 1.0 Pg Ca-1. Management processes influencing crop productivity per se are important for food supply, but were found to have little influence on E-LUC. (Less)

Effect of climate data on simulated carbon and nitrogen balances for Europe

In this study, we systematically assess the spatial variability in carbon and nitrogen balance simulations related to the choice of global circulation models (GCMs), representative concentration pathways (RCPs), spatial resolutions, and the downscaling methods used as calculated with LPJ-GUESS. We employed a complete factorial design and performed 24 simulations for Europe with different climate input data sets and different combinations of these four factors. Our results reveal that the variability in simulated output in Europe is moderate with 35.6%–93.5% of the total variability being common among all combinations of factors. The spatial resolution is the most important factor among the examined factors, explaining 1.5%–10.7% of the total variability followed by GCMs (0.3%–7.6%), RCPs (0%–6.3%), and downscaling methods (0.1%–4.6%). The higher-order interactions effect that captures nonlinear relations between the factors and random effects is pronounced and accounts for 1.6%–45.8% to the total variability. The most distinct hot spots of variability include the mountain ranges in North Scandinavia and the Alps, and the Iberian Peninsula. Based on our findings, we advise to conduct the application of models such as LPJ-GUESS at a reasonably high spatial resolution which is supported by the model structure. There is no notable gain in simulations of ecosystem carbon and nitrogen stocks and fluxes from using regionally downscaled climate in preference to bias-corrected, bilinearly interpolated CMIP5 projections. (Less)

Expression of human endogenous retroviral sequences: Differences between individuals and cell types. Increased expression in a human breast cancer

Interactions between the cyclin-dependent kinases (CDKs), CDK inhibitory proteins, the p53 tumor suppressor gene product, and the protein product of the retinoblastoma susceptability gene, pRbl, facilitate key cell cycle transitions or checkpoints at the Go/G1 and G1/S boundaries. The p53 protein plays a key role in controlling the G1/S checkpoint through its ability to activate transcription of the WAF1/CIP1 gene which encodes a protein of 21kDa (p21) that is a potent CDK inhibitor. Cells expressing SV40 large T antigen have been shown to bypass the G1/S checkpoint controlled by p53. In order to elucidate the molecular pathways involved in this bypass; stable cell lines carrying a hormone-inducible wild-type p53 cDNA transgene which constitutively express large T antigen were established. Large T antigen overcomes p53-induced G1 arrest in these cells even in the face of transactivation of the WAF1 gene, accumulation of nuclear p21 protein, and inhibition of cyclin E-CDK2 kinase activity. IP/Western blot analysis reveals that large T antigen is found in complexes with both p53 and the hypophosphorylated form of pRbl respectively. The large T antigen-mediated bypass is correlated with increased levels of mRNA transcripts of the E2F-regulated Bmyb gene. An increase in B-myb expression is necessary for large T antigen to overcome p53-induced G1 arrest. The data indicate that a key component in this bypass is the ability of large T antigen to sequester the hypophosphorylated form of pRbl protein and liberate bound E2F to facilitate transactivation Of downstream genes with E2F-dependent promoters such as B-myb.

Implications of accounting for management intensity on carbon and nitrogen balances of European grasslands

European managed grasslands are amongst the most productive in the world. Besides temperature and the amount and timing of precipitation, grass production is also highly controlled by applications of nitrogen fertilizers and land management to sustain a high productivity. Since management characteristics of pastures vary greatly across Europe, land-use intensity and their projections are critical input variables in earth system modeling when examining and predicting the effects of increasingly intensified agricultural and livestock systems on the environment. In this study, we aim to improve the representation of pastures in the dynamic global vegetation model LPJ-GUESS. This is done by incorporating daily carbon allocation for grasses as a foundation to further implement daily land management routines and land-use intensity data into the model to discriminate between intensively and extensively used regions. We further compare our new simulations with leaf area index observations, reported regional grassland productivity, and simulations conducted with the vegetation model ORCHIDEE-GM. Additionally, we analyze the implications of including pasture fertilization and daily management compared to the standard version of LPJ-GUESS. Our results demonstrate that grassland productivity cannot be adequately captured without including land-use intensity data in form of nitrogen applications. Using this type of information improved spatial patterns of grassland productivity significantly compared to standard LPJ-GUESS. In general, simulations for net primary productivity, net ecosystem carbon balance and nitrogen leaching were considerably increased in the extended version. Finally, the adapted version of LPJ-GUESS, driven with projections of climate and land-use intensity, simulated an increase in potential grassland productivity until 2050 for several agro-climatic regions, most notably for the Mediterranean North, the Mediterranean South, the Atlantic Central and the Atlantic South.