Vegetation history and sea level variations during the last 13,500 years inferred from a pollen record at Chilika Lake,Orissa, India

Chilika Lake is the largest lagoon in Asia, situated in the state of Orissa in India. In the year 2000, many surface samples and cores were taken. Here the lithological results and especially those of the pollen analysis are shown. The oldest sediments of core CHI 9 were dated at about 13,500 cal years b.p. At this time the area of Chilika Lake was a river or a river delta with fresh water vegetation. With the increase in the sea level after about 9,500 cal years b.p. the area became an estuary with mangrove vegetation. Small variations in the sea level between about 5,000 and 2,500 cal years b.p. are not visible in our pollen profile. However the regression after about 2,000 cal years b.p. caused the formation of a barrier spit and sand ridges with the consequence that a big lagoon was formed, Chilika Lake. Marine influence diminished and the fresh water impact from the rivers increased. Mangrove vegetation disappeared and was replaced by fresh water vegetation. This paper is dedicated to Prof. Dr. Hans-Jürgen Beug on his 75th birthday.     

Implementation of a combined CDK inhibition and arginine-deprivation approach to target arginine-auxotrophic glioblastoma multiforme cells

Constitutive activation of cyclin-dependent kinases (CDKs) or arginine auxotrophy are hallmarks of Glioblastoma multiforme (GBM). The latter metabolic defect renders tumor cells vulnerable to arginine-depleting substances, such as arginine deiminase from Streptococcus pyogenes (SpyADI). Previously, we confirmed the susceptibility of patient-derived GBM cells towards SpyADI as well as CDK inhibitors (CDKis). To improve therapeutic effects, we here applied a combined approach based on SpyADI and CDKis (dinaciclib, abemaciclib). Three arginine-auxotrophic patient-derived GBM lines with different molecular characteristics were cultured in 2D and 3D and effects of this combined SpyADI/CDKi approach were analyzed in-depth. All CDKi/SpyADI combinations yielded synergistic antitumoral effects, especially when given sequentially (SEQ), i.e., CDKi in first-line and most pronounced in the 3D models. SEQ application demonstrated impaired cell proliferation, invasiveness, and viability. Mitochondrial impairment was demonstrated by increasing mitochondrial membrane potential and decreasing oxygen consumption rate and extracellular acidification rate after SpyADI/abemaciclib monotherapy or its combination regimens. The combined treatment even induced autophagy in target cells (abemaciclib/SpyADI > dinaciclib/SpyADI). By contrast, the unfolded protein response and p53/p21 induced senescence played a minor role. Transmission electron microscopy confirmed damaged mitochondria and endoplasmic reticulum together with increased vacuolization under CDKi mono- and combination therapy. SEQ-abemaciclib/SpyADI treatment suppressed the DSB repair system via NHEJ and HR, whereas SEQ-dinaciclib/SpyADI treatment increased γ-H2AX accumulation and induced Rad51/Ku80. The latter combination also activated the stress sensor GADD45 and β-catenin antagonist AXIN2 and induced expression changes of genes involved in cellular/cytoskeletal integrity. This study highlights the strong antitumoral potential of a combined arginine deprivation and CDK inhibition approach via complex effects on mitochondrial dysfunction, invasiveness as well as DNA-damage response. This provides a good starting point for further in vitro and in vivo proof-of-concept studies to move forward with this strategy.Subject terms: CNS cancer, DNA damage and repair, Cell death

The complex effects of combined CDki/SPyADI application on arginine-auxotrophic glioblastoma multiforme cells. CDki/SPyADI combination therapy impairs cell proliferation, invasiveness, gene expression, induces mitochondrial impairment, and vacuole formation. Abemaciclib-SPyADI-treatment suppresses DNA repair, dinaciclib-SpyADI-treatment enhances γ-H2AX accumulation and activates the stress sensor GADD45 and β-catenin antagonist AXIN2. Both CDKi/SpyADI combinations significantly boost cell death.     

Age-Dependent Effects of UCP2 Deficiency on Experimental Acute Pancreatitis in Mice

Reactive oxygen species (ROS) have been implicated in the pathogenesis of acute pancreatitis (AP) for many years but experimental evidence is still limited. Uncoupling protein 2 (UCP2)-deficient mice are an accepted model of age-related oxidative stress. Here, we have analysed how UCP2 deficiency affects the severity of experimental AP in young and older mice (3 and 12 months old, respectively) triggered by up to 7 injections of the secretagogue cerulein (50 μg/kg body weight) at hourly intervals. Disease severity was assessed at time points from 3 hours to 7 days based on pancreatic histopathology, serum levels of alpha-amylase, intrapancreatic trypsin activation and levels of myeloperoxidase (MPO) in lung and pancreatic tissue. Furthermore, in vitro studies with pancreatic acini were performed. At an age of 3 months, UCP2^-/- mice and wild-type (WT) C57BL/6 mice were virtually indistinguishable with respect to disease severity. In contrast, 12 months old UCP2^-/- mice developed a more severe pancreatic damage than WT mice at late time points after the induction of AP (24 h and 7 days, respectively), suggesting retarded regeneration. Furthermore, a higher peak level of alpha-amylase activity and gradually increased MPO levels in pancreatic and lung tissue were observed in UCP2^-/- mice. Interestingly, intrapancreatic trypsin activities (in vivo studies) and intraacinar trypsin and elastase activation in response to cerulein treatment (in vitro studies) were not enhanced but even diminished in the knockout strain. Finally, UCP2^-/- mice displayed a diminished ratio of reduced and oxidized glutathione in serum but no increased ROS levels in pancreatic acini. Together, our data indicate an aggravating effect of UCP2 deficiency on the severity of experimental AP in older but not in young mice. We suggest that increased severity of AP in 12 months old UCP2^-/- is caused by an imbalanced inflammatory response but is unrelated to acinar cell functions.     

NG-Acyl-argininamides as NPY Y1 receptor antagonists: Influence of structurally diverse acyl substituents on stability and affinity

N^G-Acylated argininamides, covering a broad range of lipophilicity (calculated log D values: ?1.8–12.5), were synthesized and investigated for NPY Y₁ receptor (Y₁R) antagonism, Y₁R affinity and stability in buffer (N^G-deacylation, yielding BIBP 3226). Broad structural variation of substituents was tolerated. The K_i (binding) and K_b values (Y₁R antagonism) varied from low nM to one-digit μM. Most of the compounds proved to be sufficiently stable at pH 7.4 over 90 min to determine reliable pharmacological data in vitro. Exceptionally high instability was detected when a succinyl moiety was attached to the guanidine, probably, due to an intramolecular cleavage mechanism.     

Virulence evolution of the human pathogen Neisseria meningitidis by recombination in the core and accessory genome

Background

Neisseria meningitidis is a naturally transformable, facultative pathogen colonizing the human nasopharynx. Here, we analyze on a genome-wide level the impact of recombination on gene-complement diversity and virulence evolution in N. meningitidis. We combined comparative genome hybridization using microarrays (mCGH) and multilocus sequence typing (MLST) of 29 meningococcal isolates with computational comparison of a subset of seven meningococcal genome sequences.

Principal Findings

We found that lateral gene transfer of minimal mobile elements as well as prophages are major forces shaping meningococcal population structure. Extensive gene content comparison revealed novel associations of virulence with genetic elements besides the recently discovered meningococcal disease associated (MDA) island. In particular, we identified an association of virulence with a recently described canonical genomic island termed IHT-E and a differential distribution of genes encoding RTX toxin- and two-partner secretion systems among hyperinvasive and non-hyperinvasive lineages. By computationally screening also the core genome for signs of recombination, we provided evidence that about 40% of the meningococcal core genes are affected by recombination primarily within metabolic genes as well as genes involved in DNA replication and repair. By comparison with the results of previous mCGH studies, our data indicated that genetic structuring as revealed by mCGH is stable over time and highly similar for isolates from different geographic origins.

Conclusions

Recombination comprising lateral transfer of entire genes as well as homologous intragenic recombination has a profound impact on meningococcal population structure and genome composition. Our data support the hypothesis that meningococcal virulence is polygenic in nature and that differences in metabolism might contribute to virulence.     

The structural and topological analysis of membrane-associated polypeptides by oriented solid-state NMR spectroscopy: established concepts and novel developments

Solid-state NMR spectroscopy is a powerful technique for the investigation of membrane-associated peptides and proteins as well as their interactions with lipids, and a variety of conceptually different approaches have been developed for their study. The technique is unique in allowing for the high-resolution investigation of liquid disordered lipid bilayers representing well the characteristics of natural membranes. Whereas magic angle solid-state NMR spectroscopy follows approaches that are related to those developed for solution NMR spectroscopy the use of static uniaxially oriented samples results in angular constraints which also provide information for the detailed analysis of polypeptide structures. This review introduces this latter concept theoretically and provides a number of examples. Furthermore, ongoing developments combining solid-state NMR spectroscopy with information from solution NMR spectroscopy and molecular modelling as well as exploratory studies using dynamic nuclear polarization solid-state NMR will be presented.     

DIATOMS LIVING INSIDE THE THALLUS OF THE GREEN ALGAL LICHEN COENOGONIUM LINKII IN NEOTROPICAL LOWLAND RAIN FORESTS1

Coenogonium linkii Ehrenb. is a very common filamentous lichen, growing on stems, hanging roots, and lianas in the understory of neotropical lowland rain forests. We investigated several thalli of this species from locations in Panama and French Guiana. All thalli were inhabited by various species of terrestrial diatoms, which were found between the thallus filaments on extracellular material of the mycobiont. We identified 18 species of diatoms belonging to nine genera: Diadesmis, Eunotia, Hantzschia, Luticola, Melosira, Nitzschia, Orthoseira, Pinnularia, and Stauroneis. The potential benefits both diatoms and lichens could derive from symbiosis in relation to water, irradiance, and nitrogen availability are discussed.