Disentangling regional and local tree diversity in the Amazon

We analyzed the most extensive data set of tree inventory plots spread over the complete Amazon basin and Guiana shield. We aimed to separate the regional and local tree alpha-diversity to investigate the drivers of diversity at the relevant scale. Our results are consistent with the partitioning of total tree alpha-diversity into regional and local components, which are controlled by evolutionary- and ecological processes, respectively. Regional diversity is correlated with palaeo-climatic stability (31%), and long-term large-scale ecosystem dynamics (14%), as represented by the age of the geological formation. Both mechanisms contribute to high diversity in the central to western Amazon. Actual rainfall seasonality is correlated with regional tree diversity to a certain extent (19%), but we argue that this is of little consequence for the evolutionary drivers of the regional species pool. Frequency of disturbance is the main process driving local diversity, although its explanatory power is relatively small (17%).     

Effect of nerve compression on the morphogenesis of the cholinesterase containing structures of the rat myoneural junction

Summary The sciatic nerve of the newborn rat was unilaterally compressed to cause temporary denervation and subsequent re-innervation of immature myoneural junctions prior to the development of postsynaptic infoldings in the rat tibialis anterior muscle. Subsequent changes in the postsynaptic structure were followed by histochemical demonstration of acetylcholinesterase activity.It was found that postsynaptic infoldings into the myoneural junctions appeared between 16–21 days of age on the temporarily denervated side but already at 5 days of age on the contralateral unoperated side. Also further development on the operated side was delayed by 10–15 days as compared to the control side.The observations indicate that the nerve-ending exerts a stimulating influence on the development of the postsynaptic structures and, in addition, that this action is long-lasting, as compared to the more transitory induction of myoneural acetylcholinesterase activity shown earlier to take place in the rat embryo at the 18-day stage.     

Expression of the Somatostatin Receptor Subtype 4 in Intact and Inflamed Pulmonary Tissues

Somatostatin released from capsaicin-sensitive sensory nerves of the lung during endotoxin-induced murine pneumonitis inhibits inflammation and hyperresponsiveness, presumably via somatostatin receptor subtype 4 (sst₄). The goal of the present study was to identify sst₄ receptors in mouse and human lungs and to reveal its inflammation-induced alterations with real-time quantitative PCR, Western blot, and immunohistochemistry. In non-inflamed mouse and human lungs, mRNA expression and immunolocalization of sst₄ are very similar. They are present on bronchial epithelial, vascular endothelial, and smooth-muscle cells. The sst₄ receptor protein in the mouse lung significantly increases 24 hr after intranasal endotoxin administration as well as in response to 3 months of whole-body cigarette smoke exposure, owing to the infiltrating sst₄-positivite mononuclear cells and neutrophils. In the chronically inflamed human lung, the large number of activated macrophages markedly elevate sst₄ mRNA levels, although there is no change in acute purulent pneumonia, in which granulocytes accumulate. Despite mouse granulocytes, human neutrophils do not show sst₄ immunopositivity. We provide the first evidence for the expression, localization, and inflammation-induced alterations of sst₄ receptors in murine and human lungs. Inasmuch as tissue distribution of this receptor is highly similar, extrapolation of murine experimental results to human conditions might be possible. (J Histochem Cytochem 57:1127–1137, 2009)     

Enrichment of subgingival microflora on human serum leading to accumulation of Bacteroides species,Peptostreptococci and Fusobacteria

This study was undertaken to identify ecological factors that favour opportunistic pathogenic species in the subgingival microflora. In a first approach, human serum as a substitute for gingival exudate, was used for batch-wise enrichment of subgingival plaque. The microflora resulting after 5–6 enrichment steps consisted of black-pigmented and non-black-pigmented Bacteroides species, Peptostreptococcus micros and Fusobacterium nucleatum as the main organisms. It is noted that the same group of species was found to be enriched independent upon the origin of the subgingival plaque sample. It was suggested that these organisms are favoured by the increased flow of gingival exudate during inflammation.The consortium of organisms was capable of selective degradation of serum (glyco-)proteins. Four different types of degradation occurred. After a prolonged period of growth complete degradation of immunoglobulins, haptoglobin, transferrin and complement C3c was observed. Partial degradation of immunoglobulins, haptoglobin, transferrin, albumin, alpha₁-antitrypsin and complement C3c and C4 was generally observed after 48 h of growth. Besides, immunoglobulin protease activity yielding Fc and Fab fragments was found. The consortium was also capable of consuming carbohydrate side-chains as indicated by an altered electrophoretic mobility of the serum glycoproteins.     

Genes required for both gliding motility and development in Myxococcus xanthus

Myxococous xanthus cells can glide both as individual cells, dependent on A dventurous motility (A motility), and as groups of cells, dependent upon S ocial motility (S motility), Tn5-lac mutagenesis was used to generate 16 new A^- and nine new S^- mutations. In contrast with previous results, we find that subsets of A^- mutants are defective in fruiting body morphogenesis and/or myxospore differentiation. All S^- mutants are defective in fruiting body morphogenesis, consistent with previous results. Whereas some S^- mutants produce a wild-type complement of spores, others are defective in the differentiation of myxospores. Therefore, a subset of the A genes and all of the S genes are critical for fruiting body morphogenesis. Subsets of both A and S genes are essential for sporulation. Three S::Tn5–lac insertions result in surprising phenotypes. Colonies of two S^- mutants glide on ‘swim’ (0.35% agar) plates to form fractal patterns. These S^- mutants are the first examples of a bacterium in which mutations result in fractal patterns of colonial spreading. An otherwise wild-type strain with one S^- insertion resembles the frz^- sglA1^- mutants upon development, suggesting that this S^- gene defines a new chemotaxis component in M. xanthus.