Replication of the endosymbiotic bacterium Blochmannia floridanus is correlated with the developmental and reproductive stages of its ant host

The dynamics of replication of the intracellular endosymbiotic bacterium Blochmannia floridanus was determined during the larval development of its host ant Camponotus floridanus by real-time quantitative PCR. The bacteria were found to proliferate during pupation and immediately after the eclosion of the imagines (adult ants). In older workers the number of bacteria present in the midgut bacteriocytes decreased significantly. In contrast, the bacterial population in the ovaries was dependent on the reproductive state of the animal. An age-dependent degeneration of the midgut bacteriocytes was also investigated by microscopic techniques in males and female castes of the closely related ant species C. herculeanus and C. sericeiventris, respectively, with similar results and supports the concept of age-dependent degeneration of the midgut bacteriocytes in all castes.     

Agricultural breadbaskets shift poleward given adaptive farmer behavior under climate change

Modern food production is spatially concentrated in global “breadbaskets.” A major unresolved question is whether these peak production regions will shift poleward as the climate warms, allowing some recovery of potential climate-related losses. While agricultural impacts studies to date have focused on currently cultivated land, the Global Gridded Crop Model Intercomparison Project (GGCMI) Phase 2 experiment allows us to assess changes in both yields and the location of peak productivity regions under warming. We examine crop responses under projected end of century warming using seven process-based models simulating five major crops (maize, rice, soybeans, and spring and winter wheat) with a variety of adaptation strategies. We find that in no-adaptation cases, when planting date and cultivar choices are held fixed, regions of peak production remain stationary and yield losses can be severe, since growing seasons contract strongly with warming. When adaptations in management practices are allowed (cultivars that retain growing season length under warming and modified planting dates), peak productivity zones shift poleward and yield losses are largely recovered. While most growing-zone shifts are ultimately limited by geography, breadbaskets studied here move poleward over 600 km on average by end of the century under RCP 8.5. These results suggest that agricultural impacts assessments can be strongly biased if restricted in spatial area or in the scope of adaptive behavior considered. Accurate evaluation of food security under climate change requires global modeling and careful treatment of adaptation strategies.     

Potential influence of tubicolous worms on the bottom roughness length z0 in the south-western Baltic Sea

The influence of three different species of tubicolous worms (Pygospio elegans, Polydora ciliata and Lagis koreni) on the hydrodynamic bottom roughness length (z₀) was analysed in this study. Flume experiments and geospatial methods were combined to determine the potential interactions between worm tubes and the near-bed flow regime and the resulting effects on sediment transport in the south-western Baltic Sea. The three selected species are common in the area of interest (3539 km²). Their species-specific population densities were taken from existing macrozoobenthos datasets and transferred into a Geographic Information System (GIS). In analogy to the sediment roughness length, the hydrodynamic roughness lengths generated by the tubicolous worms were calculated and corresponding sediment transport values, derived from flume experiments with artificial tube lawns, were geospatially analysed using GIS. In order to show the direct influence of worm tubes on the surrounding sediment surface flume experiments were conducted at two given current velocities of 20 cm s^− 1 for sediment displacement effects and 5 cm s^− 1 for deposition effects. The roughness length was shown to increase by a factor of 2 to 30 in the presence of biogenic structures such as the worm tubes. The near-bed hydrodynamic conditions are significantly influenced at low roughness densities through independent or isolated flow conditions at 0.7 to 1.9% and at high roughness densities between 4.2 and 7.5%, resulting in unaffected sediment surfaces through “skimming flow”, as well. The GIS analysis revealed that this effect occurs over 4% (137 km²) of the area of investigation, whereas sediment displacement at roughness densities between 0.7 and 1.9% due to increased turbulence is the predominant effect over 33% (present on 1172 km²) of the area of investigation. These findings reveal the important influence of species-generated microtopography on sediment transport processes.     

Transforming growth factor-β1 immobilises dendritic cells within skin tumours and facilitates tumour escape from the immune system

Human skin tumours often regress spontaneously due to immune rejection. Murine skin tumours model this behaviour; some regress and others progress in syngeneic immunocompetent hosts. Previous studies have shown that progressor but not regressor skin tumours inhibit dendritic cell (DC) migration from the tumour to draining lymph nodes, and transforming growth factor-₁ (TGF-₁) has been identified as a responsible factor. To determine whether increased production of TGF-₁ in the absence of other differences inhibits DC migration from the tumour and enables it to evade immune destruction, a murine regressor squamous cell carcinoma clone was transfected with the gene for TGF-₁. This enhanced growth in vitro and in vivo, causing it to become a progressor. TGF-₁ transfection reduced the number of infiltrating DCs by about 25%. Quantitation of CD11c⁺ E-cadherin⁺ (epidermally derived) DCs in lymph nodes determined that TGF-₁ reduced the number of DCs that migrated from the tumour to undetectable levels. This was supported by showing that TGF-₁ reduced DC migration from cultured tumour explants by greater than tenfold. TGF-₁ transfection also reduced the number of infiltrating CD4 and CD8 T cells. Thus, TGF-₁ production by skin tumours is sufficient to immobilise DCs within the tumour, preventing their migration to lymph nodes. This reduces the number of T cells that infiltrate the tumour, preventing regression. Thus, TGF-₁ is a key regulator of whether skin tumours regress or progress.     

The carotid plaque imaging in acute stroke (CAPIAS) study: protocol and initial baseline data

Background

In up to 30% of patients with ischemic stroke no definite etiology can be established. A significant proportion of cryptogenic stroke cases may be due to non-stenosing atherosclerotic plaques or low grade carotid artery stenosis not fulfilling common criteria for atherothrombotic stroke. The aim of the CAPIAS study is to determine the frequency, characteristics, clinical and radiological long-term consequences of ipsilateral complicated American Heart Association lesion type VI (AHA-LT VI) carotid artery plaques in patients with cryptogenic stroke.

Methods/Design

300 patients (age >49 years) with unilateral DWI-positive lesions in the anterior circulation and non- or moderately stenosing (<70% NASCET) internal carotid artery plaques will be enrolled in the prospective multicenter study CAPIAS. Carotid plaque characteristics will be determined by high-resolution black-blood carotid MRI at baseline and 12 month follow up. Primary outcome is the prevalence of complicated AHA-LT VI plaques in cryptogenic stroke patients ipsilateral to the ischemic stroke compared to the contralateral side and to patients with defined stroke etiology. Secondary outcomes include the association of AHA-LT VI plaques with the recurrence rates of ischemic events up to 36 months, rates of new ischemic lesions on cerebral MRI (including clinically silent lesions) after 12 months and the influence of specific AHA-LT VI plaque features on the progression of atherosclerotic disease burden, on specific infarct patterns, biomarkers and aortic arch plaques.

Discussion

CAPIAS will provide important insights into the role of non-stenosing carotid artery plaques in cryptogenic stroke. The results might have implications for our understanding of stroke mechanism, offer new diagnostic options and provide the basis for the planning of targeted interventional studies.

Trial Registration

NCT01284933

     

Investigation of amino acid containing [FeFe] hydrogenase models concerning pendant base effects

The present investigations deal with the modeling of the peptide surrounding of [FeFe] hydrogenase using amine containing disulphides to simulate possible influences of the amino acid lysine (K237) on the electrochemical and electrocatalytic properties of biomimetic compounds based on [Fe2S2] moieties. Fe₃(CO)₁₂ was reacted with Boc-4-amino-1,2-dithiolane, Boc-Adt-OMe (Adt = 4-amino-1,2-dithiolane-4-carboxylic acid, Boc = tert-butoxycarbonyl) and Boc-Adp tert-butyl ester (Adp = (S)-2-amino-3-(1,2-dithiolan-4-yl)propionic acid) to elongate the FeN distance in comparison to the well known [Fe₂{(SCH₂)₂NR}(CO)₆] model complexes. Efforts to deprotect the complexes containing Boc-4-amino-1,2-dithiolane with trifluoroacetic acid result in the formation of [Fe₃(μ³-O)(μ-O₂C₂F₃)₆(OC₄H₈)₂(H₂O)]. The novel [2Fe2S] complexes are characterized using spectroscopic, electrochemical techniques and X-ray diffraction studies.     

HF-EPR, Raman, UV/VIS light spectroscopic, and DFT studies of the ribonucleotide reductase R2 tyrosyl radical from Epstein-Barr virus

Epstein-Barr virus (EBV) belongs to the gamma subfamily of herpes viruses, among the most common pathogenic viruses in humans worldwide. The viral ribonucleotide reductase small subunit (RNR R2) is involved in the biosynthesis of nucleotides, the DNA precursors necessary for viral replication, and is an important drug target for EBV. RNR R2 generates a stable tyrosyl radical required for enzymatic turnover. Here, the electronic and magnetic properties of the tyrosyl radical in EBV R2 have been determined by X-band and high-field/high-frequency electron paramagnetic resonance (EPR) spectroscopy recorded at cryogenic temperatures. The radical exhibits an unusually low g₁-tensor component at 2.0080, indicative of a positive charge in the vicinity of the radical. Consistent with these EPR results a relatively high C-O stretching frequency associated with the phenoxyl radical (at 1508 cm⁻¹) is observed with resonance Raman spectroscopy. In contrast to mouse R2, EBV R2 does not show a deuterium shift in the resonance Raman spectra. Thus, the presence of a water molecule as a hydrogen bond donor moiety could not be identified unequivocally. Theoretical simulations showed that a water molecule placed at a distance of 2.6 Å from the tyrosyl-oxygen does not result in a detectable deuterium shift in the calculated Raman spectra. UV/VIS light spectroscopic studies with metal chelators and tyrosyl radical scavengers are consistent with a more accessible dimetal binding/radical site and a lower affinity for Fe²⁺ in EBV R2 than in Escherichia coli R2. Comparison with previous studies of RNR R2s from mouse, bacteria, and herpes viruses, demonstrates that finely tuned electronic properties of the radical exist within the same RNR R2 Ia class.     

Local delivery of GM-CSF protects mice from lethal pneumococcal pneumonia

The growth factor GM-CSF has an important role in pulmonary surfactant metabolism and the regulation of antibacterial activities of lung sentinel cells. However, the potential of intra-alveolar GM-CSF to augment lung protective immunity against inhaled bacterial pathogens has not been defined in preclinical infection models. We hypothesized that transient overexpression of GM-CSF in the lungs of mice by adenoviral gene transfer (Ad-GM-CSF) would protect mice from subsequent lethal pneumococcal pneumonia. Our data show that intra-alveolar delivery of Ad-GM-CSF led to sustained increased pSTAT5 expression and PU.1 protein expression in alveolar macrophages during a 28-d observation period. Pulmonary Ad-GM-CSF delivery 2-4 wk prior to infection of mice with Streptococcus pneumoniae significantly reduced mortality rates relative to control vector-treated mice. This increased survival was accompanied by increased inducible NO synthase expression, antibacterial activity, and a significant reduction in caspase-3-dependent apoptosis and secondary necrosis of lung sentinel cells. Importantly, therapeutic treatment of mice with rGM-CSF improved lung protective immunity and accelerated bacterial clearance after pneumococcal challenge. We conclude that prophylactic delivery of GM-CSF triggers long-lasting immunostimulatory effects in the lung in vivo and rescues mice from lethal pneumococcal pneumonia by improving antibacterial immunity. These data support use of novel antibiotic-independent immunostimulatory therapies to protect patients against bacterial pneumonias.     

Microarray-based kinetic colorimetric detection for quantitative multiplex protein phosphorylation analysis

Commonly used colorimetric detection applied to protein microarrays with enzymatic signal amplification leads to non‐linear signal production upon increase in analyte concentration, thereby considerably limiting the range and accuracy of quantitative readout interpretation. To extend the detection range, we developed a kinetic colorimetric detection protocol for the analysis of ELISA microarrays designed to measure multiple phosphorylated proteins using the platforms ArrayTube? and ArrayStrip?. With our novel quantification approach, microarrays were calibrated over a broad concentration range spanning four orders of magnitude of analyte concentration with picomolar threshold. We used this design for the simultaneous quantitative measurement of 15 phosphorylated proteins on a single chip.     

Worker Personality and Its Association with Spatially Structured Division of Labor

Division of labor is a defining characteristic of social insects and fundamental to their ecological success. Many of the numerous tasks essential for the survival of the colony must be performed at a specific location. Consequently, spatial organization is an integral aspect of division of labor. The mechanisms organizing the spatial distribution of workers, separating inside and outside workers without central control, is an essential, but so far neglected aspect of division of labor. In this study, we investigate the behavioral mechanisms governing the spatial distribution of individual workers and its physiological underpinning in the ant Myrmica rubra. By investigating worker personalities we uncover position-associated behavioral syndromes. This context-independent and temporally stable set of correlated behaviors (positive association between movements and attraction towards light) could promote the basic separation between inside (brood tenders) and outside workers (foragers). These position-associated behavior syndromes are coupled with a high probability to perform tasks, located at the defined position, and a characteristic cuticular hydrocarbon profile. We discuss the potentially physiological causes for the observed behavioral syndromes and highlight how the study of animal personalities can provide new insights for the study of division of labor and self-organized processes in general.