The Tetrapod Ichnogenus Protochirotherium Fichter and Kunz 2004, a Characteristic Early Triassic Morphotype of Central Pangea

Early Triassic chirotherian footprint assemblages from Poland, Germany, and Morocco are important for understanding archosaur evolution in the aftermath of the Permian-Triassic crisis. However, their ichnotaxonomy is confusing because various authors have interpreted their diversity differently. After an analysis and ichnotaxonomic re-assessment, the presence of the ichnogenera Brachychirotherium, Isochirotherium, and Chirotherium in these assemblages is not supported. Distant similarities with these ichnotaxa are functions of extra morphological variation and substrate-related factors. Instead, Early Triassic chirotherian footprints described under these names are assigned here to the ichnogenus Protochirotherium and to a more slender morphotype identified as Synaptichnium. In particular, Protochirotherium appears to be more widely distributed in central Pangea as a characteristic morphotype reflecting a distinct stage in archosaur evolution. Trackmakers were nonarchosaurian archosauriforms or, alternatively, stem-group crocodylians. Morphologically and temporally these footprints match the hypothetical ancestor of the Chirotherium barthii trackmaker. Chirotherium barthii appears by the beginning of the Middle Triassic. Because of its restricted stratigraphic range, and its wider distribution in central Pangea, Protochirotherium also has biostratigraphic significance for this region and can be considered as an indicator of Early Triassic-aged strata.     

Charitable giving as a signal of trustworthiness: Disentangling the signaling benefits of altruistic acts

It has been shown that psychological predispositions to benefit others can motivate human cooperation and the evolution of such social preferences can be explained with kin or multi-level selection models. It has also been shown that cooperation can evolve as a costly signal of an unobservable quality that makes a person more attractive with regard to other types of social interactions. Here we show that if a proportion of individuals with social preferences is maintained in the population through kin or multi-level selection, cooperative acts that are truly altruistic can be a costly signal of social preferences and make altruistic individuals more trustworthy interaction partners in social exchange. In a computerized laboratory experiment, we test whether altruistic behavior in the form of charitable giving is indeed correlated with trustworthiness and whether a charitable donation increases the observing agents' trust in the donor. Our results support these hypotheses and show that, apart from trust, responses to altruistic acts can have a rewarding or outcome-equalizing purpose. Our findings corroborate that the signaling benefits of altruistic acts that accrue in social exchange can ease the conditions for the evolution of social preferences.     

Catabolic and anabolic periarticular bone changes in patients with rheumatoid arthritis: a computed tomography study on the role of age,disease duration and bone markers

Introduction

The aim of this study was to determine the factors, including markers of bone resorption and bone formation, which determine catabolic and anabolic periarticular bone changes in patients with rheumatoid arthritis (RA).

Methods

Forty RA patients received high-resolution peripheral quantitative computed tomography (HR-pQCT) analysis of the metacarpophalangeal joints II and III of the dominantly affected hand at two sequential time points (baseline, one year follow-up). Erosion counts and scores as well as osteophyte counts and scores were recorded. Simultaneously, serum markers of bone resorption (C-terminal telopeptide of type I collagen (CTX I), tartrate-resistant acid phosphatase 5b (TRAP5b)), bone formation (bone alkaline phosphatase (BAP), osteocalcin (OC)) and calcium homeostasis (parathyroid hormone (PTH), 25-hydroxyvitamin D3 (Vit D)) were assessed. Bone biomarkers were correlated to imaging data by partial correlation adjusting for various demographic and disease-specific parameters. Additionally, imaging data were analyzed by mixed linear model regression.

Results

Partial correlation analysis showed that TRAP5b levels correlate significantly with bone erosions, whereas BAP levels correlate with osteophytes at both time points. In the mixed linear model with erosions as the dependent variable, disease duration (P <0.001) was the key determinant for these catabolic bone changes. In contrast, BAP (P = 0.001) as well as age (P = 0.018), but not disease duration (P = 0.762), were the main determinants for the anabolic changes (osteophytes) of the periarticular bone in patients with RA.

Conclusions

This study shows that structural bone changes assessed with HR-pQCT are accompanied by alterations in systemic markers of bone resorption and bone formation. Besides, it can be shown that bone erosions in RA patients depend on disease duration, whereas osteophytes are associated with age as well as serum level of BAP. Therefore, these data not only suggest that different variables are involved in formation of bone erosions and osteophytes in RA patients, but also that periarticular bone changes correlate with alterations in systemic markers of bone metabolism, pointing out BAP as an important parameter.     

Modified Nucleosides. II.1 Economical Synthesis of 2′,3′-Dideoxycytidine

Abstract

An economical two pot synthesis of 2′,3′-dideoxycytidine (2) from N⁴-acetyl-cytidine (4) has been developed. The key feature of this sequence is the in situ reductive elimination of a mixture of 1-(3-bromo-3-deoxy-2,5-di-O-acetyl-β-D-xylofuranosyl)-N⁴-acetylcytosine (5) and 1-(2-bromo-3-deoxy-3,5-di-O-acetyl-β-D-arabinofuranosyl)-N⁴-acetylcytosine (6) and subsequent hydrogenation of the resultant olefin over palladised charcoal.     

A Bacterial Phosphatase-Like Enzyme of the Malaria Parasite Plasmodium falciparum Possesses Tyrosine Phosphatase Activity and Is Implicated in the Regulation of Band 3 Dynamics during Parasite Invasion

Eukaryotic parasites of the genus Plasmodium cause malaria by invading and developing within host erythrocytes. Here, we demonstrate that PfShelph2, a gene product of Plasmodium falciparum that belongs to the Shewanella-like phosphatase (Shelph) subfamily, selectively hydrolyzes phosphotyrosine, as shown for other previously studied Shelph family members. In the extracellular merozoite stage, PfShelph2 localizes to vesicles that appear to be distinct from those of rhoptry, dense granule, or microneme organelles. During invasion, PfShelph2 is released from these vesicles and exported to the host erythrocyte. In vitro, PfShelph2 shows tyrosine phosphatase activity against the host erythrocyte protein Band 3, which is the most abundant tyrosine-phosphorylated species of the erythrocyte. During P. falciparum invasion, Band 3 undergoes dynamic and rapid clearance from the invasion junction within 1 to 2 s of parasite attachment to the erythrocyte. Release of Pfshelph2 occurs after clearance of Band 3 from the parasite-host cell interface and when the parasite is nearly or completely enclosed in the nascent vacuole. We propose a model in which the phosphatase modifies Band 3 in time to restore its interaction with the cytoskeleton and thus reestablishes the erythrocyte cytoskeletal network at the end of the invasion process.     

Tidal downwelling and implications for the carbon biogeochemistry of cold‐water corals in relation to future ocean acidification and warming

Cold‐water coral (CWC) reefs are recognized as ecologically and biologically significant areas that generate habitats and diversity. The interaction between hydrodynamics and CWCs has been well studied at the Mingulay Reef Complex, a relatively shallow area of reefs found on the continental shelf off Scotland, UK. Within ‘Mingulay Area 01’ a rapid tidal downwelling of surface waters, brought about as an internal wave, is known to supply warmer, phytoplankton‐rich waters to corals growing on the northern flank of an east‐west trending seabed ridge. This study shows that this tidal downwelling also causes short‐term perturbations in the inorganic carbon (C_T) and nutrient dynamics through the water column and immediately above the reef. Over a 14 h period, corresponding to one semi‐diurnal tidal cycle, seawater pH overlying the reef varied by ca. 0.1 pH unit, while pCO₂ shifted by >60 μatm, a shift equivalent to a ca. 25 year jump into the future, with respect to atmospheric pCO₂. During the summer stratified period, these downwelling events result in the reef being washed over with surface water that has higher pH, is warmer, nutrient depleted, but rich in phytoplankton‐derived particles compared to the deeper waters in which the corals sit. Empirical observations, together with outputs from the European Regional Shelf Sea Ecosystem Model, demonstrate that the variability that the CWC reefs experience changes through the seasons and into the future. Hence, as ocean acidification and warming increase into the future, the downwelling event specific to this site could provide short‐term amelioration of corrosive conditions at certain times of the year; however, it could additionally result in enhanced detrimental impacts of warming on CWCs. Natural variability in the C_T and nutrient conditions, as well as local hydrodynamic regimes, must be accounted for in any future predictions concerning the responses of marine ecosystems to climate change.     

Identification of quantitative trait loci contributing to yield and seed quality parameters under terminal drought in barley advanced backcross lines

Drought is a major limiting factor for barley production, especially in the primary areas of its cultivation. Wild barley represents a major source of favourable alleles for increasing the genetic variation for multiple traits including resistance to both biotic and abiotic stresses. We used advanced backcross quantitative trait locus (AB-QTL) analysis of a BC3-doubled haploid population developed between the cultivated parent Brenda (Hordeum vulgare ssp. vulgare) and the wild accession HS584 (H. vulgare ssp. spontaneum) to study the contribution of wild barley in improving various agronomic and seed quality traits under post-anthesis drought. The experiment was carried out at two different locations (IPK, Gatersleben and Nordsaat, Böhnshausen) and terminal drought was imposed by withholding water or spraying with potassium iodide at 10 days after flowering under greenhouse or field conditions, respectively. QTL analysis indicated that wild barley contributed favourably to most of the traits studied under both control and drought conditions. A total of seven hot-spot QTL regions with co-localizing QTL for various traits harboured more than 80 % of the stable QTL detected in the present study. For yield and thousand-grain weight and their respective drought tolerance indices, most of the QTL were derived from Brenda. On the other hand, for traits like seed length and seed nitrogen content, all the QTL were contributed by HS584, the parent having higher trait value. A significantly reduced carbon/nitrogen (C/N) ratio in the selected contrasting inferior lines compared to superior ones suggests that C/N ratio could be a potential parameter for screening not just seed quality parameters but also grain weight performance under terminal drought.