Hageman factor activation and tight junction disruption in mice challenged with attenuated endotoxin

Summary Endotoxin treated with chromium chloride is less toxic to mice than the parent molecule, but can disrupt intestinal permeability barriers and has an enhanced ability to activate Hageman factor.We wish to thank Drs M.W. Brightman and T.S. Reese from the Department of Neurocytology, National Institutes of Health for the use of their Balzers freeze-fracture instrument.     

Broad phylogenomic sampling improves resolution of the animal tree of life

Long-held ideas regarding the evolutionary relationships among animals have recently been upended by sometimes controversial hypotheses based largely on insights from molecular data. These new hypotheses include a clade of moulting animals (Ecdysozoa) and the close relationship of the lophophorates to molluscs and annelids (Lophotrochozoa). Many relationships remain disputed, including those that are required to polarize key features of character evolution, and support for deep nodes is often low. Phylogenomic approaches, which use data from many genes, have shown promise for resolving deep animal relationships, but are hindered by a lack of data from many important groups. Here we report a total of 39.9 Mb of expressed sequence tags from 29 animals belonging to 21 phyla, including 11 phyla previously lacking genomic or expressed-sequence-tag data. Analysed in combination with existing sequences, our data reinforce several previously identified clades that split deeply in the animal tree (including Protostomia, Ecdysozoa and Lophotrochozoa), unambiguously resolve multiple long-standing issues for which there was strong conflicting support in earlier studies with less data (such as velvet worms rather than tardigrades as the sister group of arthropods), and provide molecular support for the monophyly of molluscs, a group long recognized by morphologists. In addition, we find strong support for several new hypotheses. These include a clade that unites annelids (including sipunculans and echiurans) with nemerteans, phoronids and brachiopods, molluscs as sister to that assemblage, and the placement of ctenophores as the earliest diverging extant multicellular animals. A single origin of spiral cleavage (with subsequent losses) is inferred from well-supported nodes. Many relationships between a stable subset of taxa find strong support, and a diminishing number of lineages remain recalcitrant to placement on the tree.     

Agreement in endpoints from circadian rhythmometry on healthy human beings living on different continents

Zusammenfassung Circadiane Akrophasen — Gipfel der ungefähren 24-h-Periodik — von Blut- und Harnkortikosteroiden, Kalium im Harn, Körpertemperatur, Pulsrate und 2-min-Schätzung wurden mittels elektronischer Anpassung einer Kosinusfunktion vermöge der Methode der kleinsten Quadrate bestimmt. Solche Charakteristika circadianer Rhythmen empfehlen sich als Referenzstandarde dem Mediziner und Biologen durch ihre zufriedenstellende übereinstimmung in Daten von Untersuchungen auf verschiedenen Kontinenten mit zum Teil unterschiedlichen Methoden.     

Regulation of DNA methylation of Rasgrf1.

In mammals, DNA is methylated at cytosines within CpG dinucleotides. Properly regulated methylation is crucial for normal development. Inappropriate methylation may contribute to tumorigenesis by silencing tumor-suppressor genes or by activating growth-stimulating genes. Although many genes have been identified that acquire methylation and whose expression is methylation-sensitive, little is known about how DNA methylation is controlled. We have identified a DNA sequence that regulates establishment of DNA methylation in the male germ line at Rasgrf1. In mice, the imprinted Rasgrf1 locus is methylated on the paternal allele within a differentially methylated domain (DMD) 30 kbp 5' of the promoter. Expression is exclusively from the paternal allele in neonatal brain. Methylation is regulated by a repeated sequence, consisting of a 41-mer repeated 40 times, found immediately 3' of the DMD. This sequence is present in organisms in which Rasgrf1 is imprinted. In addition, DMD methylation is required for imprinted Rasgrf1 expression. Together the DMD and repeat element constitute a binary switch that regulates imprinting at the locus.     

The importance of radioactivity in geoscience and mining

Almost simultaneously with Roentgen rays, natural radioactivity was discovered. Its investigation led to important fundamentals of the geosciences: petrophysics, terrestrial heat flow, isotope geology, and absolute geological chronology. In applied geophysics and geology, exploration of radioactive ores and of tectonic faults, and radiometric well loggings, are used. Production of radioactive water and mining for uranium ores are discussed, including their development (especially in the Saxon ore mountains) and the consequences on health (radon in underground air and houses). Disposal of radioactive waste is touched on briefly.     

The genome sequence of Atlantic cod reveals a unique immune system

Atlantic cod (Gadus morhua) is a large, cold-adapted teleost that sustains long-standing commercial fisheries and incipient aquaculture. Here we present the genome sequence of Atlantic cod, showing evidence for complex thermal adaptations in its haemoglobin gene cluster and an unusual immune architecture compared to other sequenced vertebrates. The genome assembly was obtained exclusively by 454 sequencing of shotgun and paired-end libraries, and automated annotation identified 22,154 genes. The major histocompatibility complex (MHC)?II is a conserved feature of the adaptive immune system of jawed vertebrates, but we show that Atlantic cod has lost the genes for MHC?II, CD4 and invariant chain (Ii) that are essential for the function of this pathway. Nevertheless, Atlantic cod is not exceptionally susceptible to disease under natural conditions. We find a highly expanded number of MHC?I genes and a unique composition of its Toll-like receptor (TLR) families. This indicates how the Atlantic cod immune system has evolved compensatory mechanisms in both adaptive and innate immunity in the absence of MHC?II. These observations affect fundamental assumptions about the evolution of the adaptive immune system and its components in vertebrates.     

碳纤维织物增强混凝土薄板的界面粘结性能试验

为了研究碳纤维织物增强混凝土薄板中织物和混凝土界面间粘结性能,首先介绍了德国斯图加特大学提出的测试织物在薄板的混凝土基体中界面粘结性能的拉拨试验方法,并通过初步试验,讨论了试验方法中试件养护条件和试验机夹具夹持试件的尺寸2个因素对试验结果的影响.然后,进一步研究了复合材料中的织物在其使用前的预浸胶和复合材料薄板制作过程中在织物上施加预拉力2项工艺对提高织物和混凝土基体间界面粘结性能的影响.采用Ohno ＆ Hannant理论,分析和探讨了该试验方法的机理.最后,得出该试验方法能较准确地反映织物增强混凝土薄板中织物和混凝土界面间粘结性能的结论,并提出织物浸胶和施加预拉力可以提高其界面间粘结性能的建议.     

Revealing structure and assembly cues for Arabidopsis root-inhabiting bacterial microbiota

The plant root defines the interface between a multicellular eukaryote and soil, one of the richest microbial ecosystems on Earth. Notably, soil bacteria are able to multiply inside roots as benign endophytes and modulate plant growth and development, with implications ranging from enhanced crop productivity to phytoremediation. Endophytic colonization represents an apparent paradox of plant innate immunity because plant cells can detect an array of microbe-associated molecular patterns (also known as MAMPs) to initiate immune responses to terminate microbial multiplication. Several studies attempted to describe the structure of bacterial root endophytes; however, different sampling protocols and low-resolution profiling methods make it difficult to infer general principles. Here we describe methodology to characterize and compare soil- and root-inhabiting bacterial communities, which reveals not only a function for metabolically active plant cells but also for inert cell-wall features in the selection of soil bacteria for host colonization. We show that the roots of Arabidopsis thaliana, grown in different natural soils under controlled environmental conditions, are preferentially colonized by Proteobacteria, Bacteroidetes and Actinobacteria, and each bacterial phylum is represented by a dominating class or family. Soil type defines the composition of root-inhabiting bacterial communities and host genotype determines their ribotype profiles to a limited extent. The identification of soil-type-specific members within the root-inhabiting assemblies supports our conclusion that these represent soil-derived root endophytes. Surprisingly, plant cell-wall features of other tested plant species seem to provide a sufficient cue for the assembly of approximately 40% of the Arabidopsis bacterial root-inhabiting microbiota, with a bias for Betaproteobacteria. Thus, this root sub-community may not be Arabidopsis-specific but saprophytic bacteria that would naturally be found on any plant root or plant debris in the tested soils. By contrast, colonization of Arabidopsis roots by members of the Actinobacteria depends on other cues from metabolically active host cells.