Genomic analysis reveals key aspects of prokaryotic symbiosis in the phototrophic consortium “Chlorochromatium aggregatum”

Background

‘Chlorochromatium aggregatum’ is a phototrophic consortium, a symbiosis that may represent the highest degree of mutual interdependence between two unrelated bacteria not associated with a eukaryotic host. ‘Chlorochromatium aggregatum’ is a motile, barrel-shaped aggregate formed from a single cell of ‘Candidatus Symbiobacter mobilis”, a polarly flagellated, non-pigmented, heterotrophic bacterium, which is surrounded by approximately 15 epibiont cells of Chlorobium chlorochromatii, a non-motile photolithoautotrophic green sulfur bacterium.

Results

We analyzed the complete genome sequences of both organisms to understand the basis for this symbiosis. Chl. chlorochromatii has acquired relatively few symbiosis-specific genes; most acquired genes are predicted to modify the cell wall or function in cell-cell adhesion. In striking contrast, ‘Ca. S. mobilis’ appears to have undergone massive gene loss, is probably no longer capable of independent growth, and thus may only reproduce when consortia divide. A detailed model for the energetic and metabolic bases of the dependency of ‘Ca. S. mobilis’ on Chl. chlorochromatii is described.

Conclusions

Genomic analyses suggest that three types of interactions lead to a highly sophisticated relationship between these two organisms. Firstly, extensive metabolic exchange, involving carbon, nitrogen, and sulfur sources as well as vitamins, occurs from the epibiont to the central bacterium. Secondly, ‘Ca. S. mobilis’ can sense and move towards light and sulfide, resources that only directly benefit the epibiont. Thirdly, electron cycling mechanisms, particularly those mediated by quinones and potentially involving shared protonmotive force, could provide an important basis for energy exchange in this and other symbiotic relationships.     

Hyperosmolarity alters micturition: a comparison of urinary bladder motor activity in hyperosmolar and cyclophosphamide-induced models of overactive bladder

Hyperosmolar factors induce the neurogenic inflammatory response, leading to bladder overactivity (OAB). The aim of the study was to compare the bladder motor activity in a hyperosmolar and acute cyclophosphamide (CYP)-induced model of OAB. Furthermore, we set our sights on defining the most physiological model of OAB in experimental practice. Forty-two female rats were divided randomly into 5 groups. All animals underwent cystometry with the usage of isotonic saline or saline of increasing concentration. Acute chemical cystitis was induced by CYP to elicit OAB. The following cystometric parameters were analyzed: basal pressure, threshold pressure, micturition voiding pressure, intercontraction interval, compliance, functional bladder capacity, motility index, and detrusor overactivity index. CYP and hypertonic saline solutions induced OAB. Having been compared with CYP OAB, none of the rats infused with hypertonic solution exhibited macroscopic signs of bladder inflammation. The comparison of CYP and hyperosmolar models of OAB revealed that the greatest similarity existed between the 2080 mOsm/L OAB model and the acute CYP-induced model. We postulate that the 2080 mOsm/L model of OAB can be established as being a less invasive and more physiological model when compared with the CYP-induced OAB model. Additionally, it may also be a more reliable experimental tool for evaluating novel therapeutics for OAB as compared with CYP-induced models.     

Stem cells as therapy for cardiac disease - a review

Acute myocardial infarction (AMI) is one of the most significant causes of morbidity and mortality worldwide. Stem cells represent an enormous chance to rebuild damaged heart tissue. Correct definition of the cardiac progenitors is necessary to understand heart development, and would pave the way for the use of cardiac progenitors in the treatment of heart disease. Identifying, purifying and differentiating native cardiac progenitor cells are indispensable if we are to overcome congenital and adult cardiac diseases. To understand their functions, physiology and action, cells are tested in animal models, and then in clinical trials. But because clinical trials yield variable results, questions about proper cardiac stem cells remain unanswered. Transplanted stem cells release soluble factors, acting in a paracrine fashion, which contributes to cardiac regeneration. Cytokines and growth factors have cytoprotective and neovascularizing functions, and may activate resident cardiac stem cells. Understanding all these mechanisms is crucial to overcoming heart diseases.     

Molecular biogeography of red deer Cervus elaphus from eastern Europe: insights from mitochondrial DNA sequences

European red deer are known to show a conspicuous phylogeographic pattern with three distinct mtDNA lineages (western, eastern and North-African/Sardinian). The western lineage, believed to be indicative of a southwestern glacial refuge in Iberia and southern France, nowadays covers large areas of the continent including the British Isles, Scandinavia and parts of central Europe, while the eastern lineage is primarily found in southeast-central Europe, the Carpathians and the Balkans. However, large parts of central Europe and the whole northeast of the continent were not covered by previous analyses. To close this gap, we produced mtDNA control region sequences from more than 500 red deer from Denmark, Germany, Poland, Lithuania, Belarus, Ukraine and western Russia and combined our data with sequences available from earlier studies to an overall sample size of almost 1,100. Our results show that the western lineage extends far into the European east and is prominent in all eastern countries except for the Polish Carpathians, Ukraine and Russia where only eastern haplotypes occurred. While the latter may actually reflect the natural northward expansion of the eastern lineage after the last ice age, the present distribution of the western lineage in eastern Europe may in large parts be artificial and a result of translocations and reintroduction of red deer into areas where the species became extinct in historical times.     

Batatasin‐III and the allelopathic capacity of Empetrum nigrum

Batatasin‐III (3,3‐dihydroxy‐5‐methoxybibenzyl) is a phenolic compound associated with the allelopathic effect of the evergreen dwarf shrub Empetrum nigrum, and has been referred to as the causal factor for the species being successful in dominating extensive ecosystems. Yet, only a few plant species have been tested for their response to batatasin‐III, and little is known about whether environmental factors modify this allelopathic effect. In this study, we tested the inhibitory effect of purified batatasin‐III through bioassays on 24 vascular plant species and, for certain species, we tested if this effect depended on growth substrate (mineral vs organic substrate), pH, and fertilization. Moreover, we tested if batatasin‐III predicted the allelopathic effect of E. nigrum by analyzing the inhibitory effect of E. nigrum leaves and humus in relation to their batatasin‐III content. Our results confirmed batatasin‐III as a stable compound capable of inhibiting germination and/or mean root elongation in all of the tested species, but this effect was modified by growth substrate. Surprisingly, the measured batatasin‐III content of E. nigrum leaves (mean value 19.7 ± 10.8 (SE) mg g^?1) and humus (mean value of 1 ± 1.5 (SE) μg g^?1) did not predict the inhibitory effect on mean root elongation. Although batatasin‐III was found to be phytotoxic to all the tested species, we conclude that this substance alone should not be used as a proxy for the allelopathic effect of E. nigrum.     

Genes of the extinct Caucasian bison still roam the Białowieża Forest and are the source of genetic discrepances between Polish and Belarusian populations of the European bison,Bison bonasus

European bison (Bison bonasus) populations from both the Polish (PL) and the Belarusian (BY) sides of the Bia?owie?a Forest represent the Lowland genetic line (LB line) – progeny of the Lowland bison (Bison bonasus bonasus) that inhabited western, central, and south‐eastern Europe in historical times. During the species recovery, one of the founders was a descendant of the extinct Caucasian bison (Bison bonasus caucasicus) and its descendants formed the other genetic line – Lowland–Caucasian (LC). There have been justified suspicions that LB European bison in the former Soviet Union had undergone cross‐mating with the LC line. We performed a comparative genetic analyses on European bison from the BY and PL parts of the Bia?owie?a Forest, the LC line and extinct Caucasian bison, based on a set of 19 microsatellite markers and 1512 bovine single nucleotide polymorphism (SNP) markers, polymorphic in at least one of the studied populations. Although genetic variability (mean allele number and expected heterozygosity) for both populations were similar, the F_ST jack‐knifing and principal component analyses PCA revealed highly significant differences between PL and BY bison from the Bia?owie?a Forest. Examining DNA of the extinct Caucasian bison revealed that at least part of the genetic variants found in the BY, but not the PL, population were of Caucasian origin. The results indicate that the contemporary population of European bison from the BY part of the Bia?owie?a Forest should not be regarded as a LB line. The results also suggest that the actual global population size of the LB line European bison is only a half of its official status. Consideration of the presented results are crucial in determining management actions and policy decisions in order to conserve LB line bison within the Bia?owie?a Forest – its natural refuge. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 752–763.     

Clonal Analysis in Recurrent Astrocytic, Oligoastrocytic and Oligodendroglial Tumors Implicates IDH1- Mutation as Common Tumor Initiating Event

Background

To investigate the dynamics of inter- and intratumoral molecular alterations during tumor progression in recurrent gliomas.

Methodology/Principal Findings

To address intertumoral heterogeneity we investigated non- microdissected tumor tissue of 106 gliomas representing 51 recurrent tumors. To address intratumoral heterogeneity a set of 16 gliomas representing 7 tumor pairs with at least one recurrence, and 4 single mixed gliomas were investigated by microdissection of distinct oligodendroglial and astrocytic tumor components. All tumors and tumor components were analyzed for allelic loss of 1p/19q (LOH 1p/19q), for TP53- mutations and for R132 mutations in the IDH1 gene. The investigation of non- microdissected tumor tissue revealed clonality in 75% (38/51). Aberrant molecular alterations upon recurrence were detected in 25% (13/51). 64% (9/14) of these were novel and associated with tumor progression. Loss of previously detected alterations was observed in 36% (5/14). One tumor pair (1/14; 7%) was significant for both. Intratumoral clonality was detected in 57% (4/7) of the microdissected tumor pairs and in 75% (3/4) of single microdissected tumors. 43% (3/7) of tumor pairs and one single tumor (25%) revealed intratumoral heterogeneity. While intratumoral heterogeneity affected both the TP53- mutational status and the LOH1p/19q status, all tumors with intratumoral heterogeneity shared the R132 IDH1- mutation as a common feature in both their microdissected components.

Conclusions/Significance

The majority of recurrent gliomas are of monoclonal origin. However, the detection of divertive tumor cell clones in morphological distinct tumor components sharing IDH1- mutations as early event may provide insight into the tumorigenesis of true mixed gliomas.     

The effect of hyperosmolar stimuli and cyclophosphamide on the culture of normal rat urothelial cells <Emphasis Type="Italic">in vitro</Emphasis>

Highly concentrated urine may induce a harmful effect on the urinary bladder. Therefore, we considered osmolarity of the urine as a basic pathomechanism of mucosal damage. The influence of both cyclophosphamide (CYP) and hyperosmolar stimuli (HS) on the urothelium are not well described. The purpose was to evaluate the effect of CYP and HS on rat urothelial cultured cells (RUCC). 15 Wistar rats were used for RUCC preparation. RUCC were exposed to HS (2080 and 3222 mOsm/l NaCl) for 15 min and CYP (1 mg/ml) for 4 hrs. APC-labelled annexin V was used to quantitatively determine the percentage of apoptotic cells and propidium iodide (PI) as a standard flow cytometric viability probe to distinguish necrotic cells from viable ones. Annexin V-APC (+), annexin V-APC and PI (+), and PI (+) cells were analysed as apoptotic, dead, and necrotic cells, respectively. The results were presented in percentage values. The flow cytometric analysis was done on a FACSCalibur Flow Cytometer using Cell-Quest software. Treatment with 2080 and 3222 mOsm/l HS resulted in 23.7 ± 3.9% and 26.0 ± 1.5% apoptotic cells, respectively, 14.3 ± 1.4% and 19.4 ± 2.7% necrotic cells, respectively and 60.5 ± 1.4% and 48.6 ± 5.3% dead cells, respectively. The effect of CYP on RUCC was similar to the effect of HS. After CYP the apoptotic and necrotic cells were 23.1 ± 0.3% and 17.9 ± 7.4%, respectively. The percentage of dead cells was 57.7 ± 10.8%. CYP and HS induced apoptosis and necrosis in RUCC. 3222 mOsm/l HS had the most harmful effect based on the percentage of necrotic and apoptotic cells.     

Ultrastructural characterization of the prokaryotic symbiosis in "Chlorochromatium aggregatum"

The phototrophic consortium "Chlorochromatium aggregatum" currently represents the most highly developed interspecific association of bacteria and consists of green sulfur bacteria, so-called epibionts, surrounding a central, motile, chemotrophic bacterium. In order to identify subcellular structures characteristic of this symbiosis, consortia were studied by a combination of high-resolution analytical scanning electron microscopy, transmission electron microscopy, and three-dimensional reconstruction and image analyses. Epibionts are interconnected and to a lesser extent are also connected with the central bacterium, by electron-dense, hair-like filaments. In addition, numerous periplasmic tubules extend from the outer membrane of the central bacterium and are in direct contact with the outer membrane of the epibionts. In each epibiont cell, the attachment site to the central bacterium is characterized by the absence of chlorosomes and an additional 17-nm-thick layer (epibiont contact layer [ECL]) attached to the inner side of the cytoplasmic membrane. The ECL is only occasionally observed in pure cultures of the epibiont, where it occurs in about 10 to 20% of the free-living cells. A striking feature of the central bacterium is the presence of one or two hexagonally packed flat crystals (central bacterium crystal [CBC]) per cell. The CBC reaches 1 microm in length, is 35 nm thick, and consists of bilayers of subunits with a spacing of 9 nm. A detailed model for consortia is presented, summarizing our conclusions regarding (i) cohesion of the cells, (ii) common periplasmic space between the central bacterium and the epibiont, (iii) ECL as a symbiosis-specific structure, and (iv) formation of the interior paracrystalline structures, central bacterium membrane layer, and CBC.