Genome sequence of Shigella flexneri serotype 5a strain M90T Sm

Bacteria of the genus Shigella are a major cause of death worldwide (L. von Seidlein et al., PLoS Med. 3:e353, 2006). We sequenced the genome of Shigella flexneri strain M90T Sm (serotype 5a) and compared it to the published genome sequence of S. flexneri strain 8401 (serotype 5b).     

Generalized arterial calcification of infancy and pseudoxanthoma elasticum can be caused by mutations in either ENPP1 or ABCC6

Spontaneous pathologic arterial calcifications in childhood can occur in generalized arterial calcification of infancy (GACI) or in pseudoxanthoma elasticum (PXE). GACI is associated with biallelic mutations in ENPP1 in the majority of cases, whereas mutations in ABCC6 are known to cause PXE. However, the genetic basis in subsets of both disease phenotypes remains elusive. We hypothesized that GACI and PXE are in a closely related spectrum of disease. We used a standardized questionnaire to retrospectively evaluate the phenotype of 92 probands with a clinical history of GACI. We obtained the ENPP1 genotype by conventional sequencing. In those patients with less than two disease-causing ENPP1 mutations, we sequenced ABCC6. We observed that three GACI patients who carried biallelic ENPP1 mutations developed typical signs of PXE between 5 and 8 years of age; these signs included angioid streaks and pseudoxanthomatous skin lesions. In 28 patients, no disease-causing ENPP1 mutation was found. In 14 of these patients, we detected pathogenic ABCC6 mutations (biallelic mutations in eight patients, monoallelic mutations in six patients). Thus, ABCC6 mutations account for a significant subset of GACI patients, and ENPP1 mutations can also be associated with PXE lesions in school-aged children. Based on the considerable overlap of genotype and phenotype of GACI and PXE, both entities appear to reflect two ends of a clinical spectrum of ectopic calcification and other organ pathologies, rather than two distinct disorders. ABCC6 and ENPP1 mutations might lead to alterations of the same physiological pathways in tissues beyond the artery.     

Cyclic enediyne–amino acid chimeras as new aminopeptidase N inhibitors

Enediyne–peptide conjugates were designed with the aim to inhibit aminopeptidase N, a widespread ectoenzyme with a variety of functions, like protein digestion, inactivation of cytokines in the immune system and endogenous opioid peptides in the central nervous system. Enediyne moiety was embedded within the 12-membered ring with hydrophobic amino acid alanine, valine, leucine or phenylalanine used as carriers. Aromatic part of the enediyne bridging unit and the amino acid side chains were considered as pharmacophores for the binding to the aminopeptidase N (APN) active site. Additionally, the fused enediyne–amino acid “heads” were bound through a flexible linker to the l-lysine, an amino group donor. The synthesis included building the aromatic enediyne core at the C-terminal of amino acids and subsequent intramolecular N-alkylation. APN inhibition test revealed that the alanine-based derivative 9a inhibits the APN with IC₅₀ of 34 ± 11 μM. Enediyne–alanine conjugate 12 missing the flexible linker was much less effective in the APN inhibition. These results show that enediyne-fused amino acids have potential as new pharmacophores in the design of APN inhibitors.     

Atomic force microscopy characterization of silver nanoparticles interactions with marine diatom cells and extracellular polymeric substance

This study highlights the capacity of atomic force microscopy (AFM) for investigating nanoparticle (NP) algal cell interaction with a subnanometer resolution. We designed a set of AFM experiments to characterize NP size, shape, and structure to visualize changes in the cell morphology induced by NPs and to characterize NP interaction with the extracellular polymeric substance (EPS). Samples for AFM imaging were prepared using the same protocol-drop deposition on mica and imaged in air. Here we address the interactions of Ag NPs with ubiquitous, lightly silicified marine diatoms Cylindrotheca fusiformis and Cylindrotheca closterium and their EPS. In natural seawater used throughout this study, the single Ag NPs adopted truncated tetrahedron morphology with particle heights of 10, 20, 30, and 40 nm. This size class Ag NPs penetrates the cell wall through the valve region built of silica NPs embedded in organic matrix. The Ag NPs cause a local damage inside the cell without disintegration of the cell wall. The EPS production has been shown to increase as a feedback response to Ag NP exposure and may contribute to detoxification mechanisms. Imaging EPS at high resolution revealed the incorporation of Ag NPs and their aggregates into the EPS-gel matrix, proving their detoxifying capacity.     

Evolution: sociality as a driver of unorthodox reproduction

An unusual reproductive system was discovered in desert ants, in which daughter queens are produced asexually via parthenogenesis, whereas workers develop from hybrid crosses between genetically divergent lineages. The system appears to be doomed to extinction.     

Fish migrate underground: the example of Delminichthys adspersus (Cyprinidae)

Complex aquatic systems of karst harbour a rich but little‐investigated biodiversity. In Croatia and Bosnia–Herzegovina karst, temporal springs are inhabited by a group of minnow‐like fishes that retreat to the associated ground water during dry seasons and spend several months underground. The most abundant species in this group is Delminichthys adspersus (Heckel 1843), which also has the most fragmented distribution range. To determine the population composition and dispersal patterns, and to detect potential underground migration, a large genetic data set comprising 544 specimens of D. adspersus covering most of its distribution area was analysed. Analysis of mitochondrial cytochrome b sequences (～1000 bp) and eight microsatellite loci showed that D. adspersus comprises at least three subpopulations with gene flow occurring among them. Coalescent‐based analysis revealed a complex migration pattern, with several unidirectional dispersal paths, including between temporal springs that share no surface connection. The results of this study suggest the existence of recurrent underground migration of fish in a karst environment and demonstrate the complexity of its hydrological network. The findings are relevant to conservation strategies for endemic karst organisms and karst ecosystems as a whole.     

Prenatal stress and balance of the child's cardiac autonomic nervous system at age 5-6 years

Objective

Autonomic nervous system (ANS) misbalance is a potential causal factor in the development of cardiovascular disease. The ANS may be programmed during pregnancy due to various maternal factors. Our aim is to study maternal prenatal psychosocial stress as a potential disruptor of cardiac ANS balance in the child.

Methods

Mothers from a prospective birth cohort (ABCD study) filled out a questionnaire at gestational week 16 [IQR 12–20], that included validated instruments for state anxiety, depressive symptoms, pregnancy-related anxiety, parenting daily hassles and job strain. A cumulative stress score was also calculated (based on 80^th percentiles). Indicators of cardiac ANS in the offspring at age 5–6 years are: pre-ejection period (PEP), heart rate (HR), respiratory sinus arrhythmia (RSA) and cardiac autonomic balance (CAB), measured with electrocardiography and impedance cardiography in resting supine and sitting positions.

Results

2,624 mother-child pairs, only single births, were available for analysis. The stress scales were not significantly associated with HR, PEP, RSA and CAB (p≥0.17). Accumulation of maternal stress was also not associated with HR, PEP, RSA and CAB (p≥0.07).

Conclusion

Results did not support the hypothesis that prenatal maternal psychosocial stress deregulates cardiac ANS balance in the offspring, at least in rest, and at the age of five-six years.     

Nanoscale distinction of membrane patches – a TERS study of Halobacterium salinarum

The structural organization of cellular membranes has an essential influence on their functionality. The membrane surfaces currently are considered to consist of various distinct patches, which play an important role in many processes, however, not all parameters such as size and distribution are fully determined. In this study, purple membrane (PM) patches isolated from Halobacterium salinarum were investigated in a first step using TERS (tip‐enhanced Raman spectroscopy). The characteristic Raman modes of the resonantly enhanced component of the purple membrane lattice, the retinal moiety of bacteriorhodopsin, were found to be suitable as PM markers. In a subsequent experiment a single Halobacterium salinarum was investigated with TERS. By means of the PM marker bands it was feasible to identify and localize PM patches on the bacterial surface. The size of these areas was determined to be a few hundred nanometers. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

<Emphasis Type="Italic">In vivo</Emphasis> and <Emphasis Type="Italic">in vitro</Emphasis> antioxidant effects of three Veronica species

The aim of the present study was to examine the antioxidant activity of three Veronica species (Plantaginaceae). The antioxidant potential of various extracts obtained from aerial flowering parts was evaluated by DPPH-free (1,1-diphenyl-2-picrylhydrazyl-free) radical scavenging activity and ferric-reducing antioxidant power assays. Considerable antioxidant activity was observed in the plant samples (FRAP values ranged from 0.97 to 4.85 mmol Fe²⁺/g, and DPPH IC₅₀ values from 12.58 to 66.34 μg/ml); however, these levels were lower than the activity of the control compound butylated hydroxytoluene (BHT) (FRAP: 10.58 mmol Fe²⁺/g; DPPH IC₅₀: 9.57 μg/ml). Also, the in vivo antioxidant effects were evaluated in several hepatic antioxidant systems in rats (activities of glutathione peroxidase, glutathione reductase, peroxidase, catalase, xanthine oxidase, glutathione content and level of thiobarbituric acid reactive substances) after treatment with different Veronica extracts, or in combination with carbon tetrachloride (CCl₄). Pretreatment with 100 mg/kg b.w. of Veronica extracts inhibited CCl₄-induced liver injury by decreasing TBA-RS level, increasing GSH content, and bringing the activities of CAT and Px to control levels. The present study suggests that the extracts analyzed could protect the liver cells from CCl₄-induced liver damage by their antioxidative effect on hepatocytes.