Proviral Integration Site for Moloney Murine Leukemia Virus (PIM) Kinases Promote Human T Helper 1 Cell Differentiation

The differentiation of human primary T helper 1 (Th1) cells from naïve precursor cells is regulated by a complex, interrelated signaling network. The identification of factors regulating the early steps of Th1 cell polarization can provide important insight in the development of therapeutics for many inflammatory and autoimmune diseases. The serine/threonine-specific proviral integration site for Moloney murine leukemia virus (PIM) kinases PIM1 and PIM2 have been implicated in the cytokine-dependent proliferation and survival of lymphocytes. We have established that the third member of this family, PIM3, is also expressed in human primary Th cells and identified a new function for the entire PIM kinase family in T lymphocytes. Although PIM kinases are expressed more in Th1 than Th2 cells, we demonstrate here that these kinases positively influence Th1 cell differentiation. Our RNA interference results from human primary Th cells also suggest that PIM kinases promote the production of IFNγ, the hallmark cytokine produced by Th1 cells. Consistent with this, they also seem to be important for the up-regulation of the critical Th1-driving factor, T box expressed in T cells (T-BET), and the IL-12/STAT4 signaling pathway during the early Th1 differentiation process. In summary, we have identified PIM kinases as new regulators of human primary Th1 cell differentiation, thus providing new insights into the mechanisms controlling the selective development of human Th cell subsets.     

Reproductive meristem fates in Gerbera

Flowering plants go through several phases between regular stem growth and the actual production of flower parts. The stepwise conversion of vegetative into inflorescence and floral meristems is usually unidirectional, but under certain environmental or genetic conditions, meristems can revert to an earlier developmental identity. Vegetative meristems are typically indeterminate, producing organs continuously, whereas flower meristems are determinate, shutting down their growth after reproductive organs are initiated. Inflorescence meristems can show either pattern. Flower and inflorescence development have been investigated in Gerbera hybrida, an ornamental plant in the sunflower family, Asteraceae. Unlike the common model species used to study flower development, Gerbera inflorescences bear a fixed number of flowers, and the architecture of the flowers differ in that Gerbera ovaries are inferior (borne below the perianth). This architectural difference has been exploited to show that floral meristem determinacy and identity are spatially and genetically distinct in Gerbera, and we have shown that a single SEPALLATA-like MADS domain factor controls both flower and inflorescence meristem fate in the plant. Although these phenomena have not been directly observed in Arabidopsis, the integrative role of the SEPALLATA function in reproductive meristem development may be general for all flowering plants.     

Characteristics of an Environmentally Monitored Prolonged Type 2 Vaccine Derived Poliovirus Shedding Episode that Stopped without Intervention

Vaccine derived poliovirus (VDPV) type 2 strains strongly divergent from the corresponding vaccine strain, Sabin 2, were repeatedly isolated from sewage in Slovakia over a period of 22 months in 2003–2005. Cell cultures of stool specimens from known immune deficient patients and from an identified putative source population of 500 people failed to identify the potential excretor(s) of the virus. The occurrence of VDPV in sewage stopped without any intervention. No paralytic cases were reported in Slovakia during the episode. According to a GenBank search and similarity plotting-analysis, the closest known relative of the first isolate PV2/03/SVK/E783 through all main sections of the genome was the type 2 poliovirus Sabin strain, with nucleotide identities in 5′UTR, P1, P2, P3, and 3′UTR parts of the genome of 88.6, 85.9, 87.3, 88.5, and 94.0 percent, respectively. Phenotypic properties of selected Slovakian aVDPV strains resembled those of VDPV strains isolated from immune deficient individuals with prolonged PV infection (iVDPV), including antigenic changes and moderate neurovirulence in the transgenic mouse model. One hundred and two unique VP1 coding sequences were determined from VDPV strains isolated from 34 sewage specimens. Nucleotide differences from Sabin 2 in the VP1 coding region ranged from 12.5 to 15.6 percent, and reached a maximum of 9.6 percent between the VDPV strains under study. Most of the nucleotide substitutions were synonymous but as many as 93 amino acid positions out of 301 in VP1 showed substitutions. We conclude that (1) individuals with prolonged poliovirus infection are not as rare as suggested by the studies on immune deficient patients known to the health care systems and (2) genetic divergence of VDPV strains may remain extensive during years long replication in humans.     

Carbon storage change and δ13C transitions of peat columns in a partially forestry-drained boreal bog

Background and aims

In forestry-drained peatlands, drying leads to changes in C cycling which could affect peat δ¹³C. Furthermore, the δ¹³C profile of the entire peat column may reveal effects of earlier climatic periods.

Methods

We measured peat δ¹³C and C inventories in adjacent peat profiles, two collected from undrained and two from the drained side of a bog that was partially ditch-drained 37 years earlier. The cores were sliced into 10-cm subsamples for analyses; matching of the profiles based on surface levelling, peat stratigraphic correlation and a horizontal ash layer found in both profiles.

Results

Surface subsidence of 30 cm was observed in the dried site and the uppermost 160 cm in the undrained site contained an excess of 5.9 kg m⁻² of C compared with the corresponding strata of the ditch-drained site. The δ¹³C values increased but markedly only in the thin surface layer of the drained site, indicating low δ¹³C of the missing C (ca. –30‰). In the deeper strata, dating to Mid-Holocene, high dry bulk density, C%, N%, humification index and low C/N ratio were connected to low δ¹³C of peat.

Conclusions

Drainage of 37 years increased δ¹³C values in the upper peat profile of the drained bog and led to the selective loss of ¹³C depleted C. Results indicate that C balance studies can be aided by C isotope analyses. Low δ¹³C values in the peat profile indicate the existence of a wet fen stage during the moist and warm period during Mid-Holocene.

     

Structural and thermodynamic characterization of metal ion binding in Streptococcus suis Dpr

The use of protein cages for the creation of novel inorganic nanomaterials has attracted considerable attention in recent years. Ferritins are among the most commonly used protein cages in nanoscience. Accordingly, the binding of various metals to ferritins has been studied extensively. Dps (DNA-binding protein from starved cells)-like proteins belong to the ferritin superfamily. In contrast to ferritins, Dps-like proteins form 12-mers instead of 24-mers, have a different ferroxidase center, and are able to store a smaller amount of iron atoms in a hollow cavity (up to ∼ 500, instead of the ∼ 4500 iron atoms found in ferritins). With the exception of iron, the binding of other metal cations to Dps proteins has not been studied in detail. Here, the binding of six divalent metal ions (Zn²⁺, Mn²⁺, Ni²⁺, Co²⁺, Cu²⁺, and Mg²⁺) to Streptococcus suisDps-like peroxide resistance protein (SsDpr) was characterized by X-ray crystallography and isothermal titration calorimetry (ITC). All metal cations, except for Mg²⁺, were found to bind to the ferroxidase center similarly to Fe²⁺, with moderate affinity (binding constants between 0.1 × 10⁵ M^− 1 and 5 × 10⁵ M^− 1). The stoichiometry of binding, as deduced by ITC data, suggested the presence of a dication ferroxidase site. No other metal binding sites were identified in the protein. The results presented here demonstrate the ability of SsDpr to bind various metals as substitutes for iron and will help in better understanding protein-metal interactions in the Dps family of proteins as potential metal nanocontainers.     

Can re-establishment of cattle grazing restore bryophyte diversity in abandoned mesic semi-natural grasslands?

Changes of agricultural practices have led to decline of semi-natural habitats sustained by traditional animal husbandry in many European regions. The abandonment of semi-natural pastures leads to increase of vascular plant biomass and subsequent decline of weak competitors such as bryophytes. Re-establishing traditional animal husbandry may potentially restore biodiversity but the success of such measures remains insufficiently known. In this study, we asked if re-establishing cattle grazing on previously abandoned grasslands will restore their bryophyte communities. The effect of cattle grazing on bryophyte communities of mesic semi-natural grasslands was studied in south-western Finland in a comparison of (i) continuously grazed pastures, (ii) previously abandoned pastures where grazing was re-established during 1990s, and (iii) abandoned pastures, where grazing had ceased during late 1960s to early 1980s. The average cover, species richness, species density and species diversity of bryophytes were significantly higher in the continuously grazed than in the abandoned grasslands. Ordination analyses revealed clear differences also in community structure between the management classes. Re-established grasslands were ecologically heterogeneous and situated in between the continuously grazed and abandoned grasslands in all characteristics, indicating variable effect of the restoration measure. Seventeen bryophyte species were recognized as significant indicators of the three grassland classes, four of which could be used as indicators of valuable grassland habitats. Although there was variation in the consequences of re-introduction of grazing, the results give evidence of positive effect of grazing on regaining bryophyte diversity of abandoned grasslands.     

Non-Cholesterol Sterol Levels Predict Hyperglycemia and Conversion to Type 2 Diabetes in Finnish Men

We investigated the levels of non-cholesterol sterols as predictors for the development of hyperglycemia (an increase in the glucose area under the curve in an oral glucose tolerance test) and incident type 2 diabetes in a 5-year follow-up study of a population-based cohort of Finnish men (METSIM Study, N = 1,050) having non-cholesterol sterols measured at baseline. Additionally we determined the association of 538,265 single nucleotide polymorphisms (SNP) with non-cholesterol sterol levels in a cross-sectional cohort of non-diabetic offspring of type 2 diabetes (the Kuopio cohort of the EUGENE2 Study, N = 273). We found that in a cross-sectional METSIM Study the levels of sterols indicating cholesterol absorption were reduced as a function of increasing fasting glucose levels, whereas the levels of sterols indicating cholesterol synthesis were increased as a function of increasing 2-hour glucose levels. A cholesterol synthesis marker desmosterol significantly predicted an increase, and two absorption markers (campesterol and avenasterol) a decrease in the risk of hyperglycemia and incident type 2 diabetes in a 5-year follow-up of the METSIM cohort, mainly attributable to insulin sensitivity. A SNP of ABCG8 was associated with fasting plasma glucose levels in a cross-sectional study but did not predict hyperglycemia or incident type 2 diabetes. In conclusion, the levels of some, but not all non-cholesterol sterols are markers of the worsening of hyperglycemia and type 2 diabetes.     

On the mechanism of apoplastic H<Subscript>2</Subscript>O<Subscript>2</Subscript> production during lignin formation and elicitation in cultured spruce cells—peroxidases after elicitation

A cell culture of Picea abies (L.) Karst. was used for studies of H₂O₂ generation during constitutive extracellular lignin formation and after elicitation by cell wall fragments of a pathogenic fungus, Heterobasidium parviporum. Stable, micromolar levels of H₂O₂ were present in the culture medium during lignin formation. Elicitation induced a burst of H₂O₂, peaking at ca. 90 min after elicitation. Of exogenous reducing substrates that may be responsible for the synthesis of H₂O₂ from O₂, NADH stimulated H₂O₂ production irrespective of elicitation. Cysteine (Cys) and glutathione (GSH) partially scavenged the constitutive H₂O₂, but usually increased or prolonged elicitor-induced H₂O₂ formation. Culture medium peroxidases were not able to generate H₂O₂ in vitro with Cys or GSH as reductants. These thiols, however, generated H₂O₂ non-enzymically at pH 4.5. [³⁵S]Sulphate feeding to spruce cells showed that endogenous sulphur-containing compounds (including GSH, GSSG and cysteic acid) existed in the culture medium. The apoplastic levels of these were, however, undetectable by the monobromobimane method suggesting that their contribution to apoplastic H₂O₂ formation is probably minor. Azide, an inhibitor of haem-containing enzymes, slightly inhibited constitutive H₂O₂ generation but strongly delayed the elicitor-induced H₂O₂ accumulation. Diphenylene iodonium, an inhibitor of flavin-containing enzymes, efficiently inhibited H₂O₂ production irrespective of elicitation. Elicitation led to downregulation of the expression of several peroxidase genes, and peroxidase activity in the culture medium was slightly reduced. Expression of three other peroxidase genes and a respiratory burst oxidase homologue (rboh) gene were upregulated. These data suggest that both peroxidases and rboh may contribute to H₂O₂ generation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.