Extremitätentransplantationen an Anuren

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Identification and characterization of intrinsic factor and cobalophilin from pig ileal and pyloric mucosa

Pig ileal mucosa was found to bind about 240 ng vitamin B₁₂/g and to contain two vitamin B₁₂-binding proteins. One was highly active in the Schilling test, behaved immunologically as intrinsic factor and was responsible for about half of the total vitamin B₁₂-binding capacity. The other binder was identified as cobalophilin (R-protein). Immunochemical purification of these proteins from pig ileum and pylorus was performed and the molecular characteristics (sedimentation and diffusion coefficients, Strokes radii, frictional ratios and molecular weights) of their vitamin B₁₂ complexes were estimated. Isoelectric focusing revealed differences between the ileal and pyloric intrinsic factors but not between the cobalophilins. The mean isoelectric points of the pyloric and ileal intrinsic factors were pH 5.79 and 5.30, respectively, whereas the corresponding figures for the cobalophilins were 4.13 and 4.10.     

Italian weedy rice—A case of de‐domestication?

Weedy rice is a representative of the extensive group of feral weeds that derive from crops, but has returned to the lifestyle of a wild species. These weeds develop either from a hybridization of crops with wild relatives (exoferality), or by mutation of crops to weedy forms (endoferality). Due to the close relation of weed and crop, the methods for weed‐targeted containment are limited to date. A deeper understanding of the development of such weeds might help to design more efficient and sustainable approaches for weed management. Weedy rice poses a serious threat to rice yields worldwide. It is widely accepted that weedy rice has originated independently in different regions all over the world. However, details of its evolution have remained elusive. In the current study, we investigated the history of weedy rice in northern Italy, the most important rice‐growing area in Europe. Our approach was to analyze genes related to weedy traits (SD1, sh4, Rc) in weedy rice accessions compared to cultivars, and to integrate these results with phenotypic and physiological data, as well as historical information about rice farming in Italy. We arrive at a working model for the timeline of evolution of weedy rice in Italy indicating that both exoferality and endoferality acted as forces driving the development of the diverse weedy rice populations found in the region today. Models of weed evolution can help to predict the direction which weed development might take and to develop new, sustainable methods to control feral weeds.     

Large vertical movements by a goosefish,Lophius americanus,suggests the potential of data storage tags for behavioral studies of benthic fishes

The extensive periodic vertical movements of up to 14 h and 209 m observed in this study for an individual goosefish, Lophius americanus, challenges previous assumptions about the benthic and highly sedentary behavior of the species as well as of other lophiids. Researchers should consider conducting similar data storage tagging studies with other benthic fishes to test assumptions of sedentary behavior.     

A New Method of Synthesis of Fluorescently Labelled Oligonucleotides and Their Application in DNA Sequencing

Abstract

A new approach to the chemical synthesis of oligonucleotides bearing reporter functional groups based on the modification of cytosine residues during the final deprotection step is reported. The application of the fluorescently labelled primer for the automated DNA sequencing is shown.     

Rational Methods of DNA Synthesis,Exemplified for the Preparation of Parts of the Human Proopiomelanocortin Gene

Abstract

Complete genes can now be prepared in single-batch procedures a) as one long oligonucleotide strand, b) as a number of simultaneously synthesized fragments. For further increase of overall efficiency DNA fragments terminated by a 3′-ribonucleoside can be joined by solid-phase single strand ligation using RNA ligase. This paper describes the application of these techniques to the preparation of parts of the human proopiomelanocortin gene.     

Cloning and Expression of Collagen-Derived Protein in E. Coli And Baculovirus System

Abstract

Using appropriately designed primers we amplified a 783 bp frag ment of the triple helical portion of human α1-collagen (I) by PCR methods. The expression of this biosynthetic collagen gene and a modified one containing cell adhesion sequences was carried out in a prokaryotic (E. coli) and a eukaryotic (baculovirus) system. The expression products were purified by affinity chromatography.     

Inhibition of Mitochondrial Complex III Blocks Neuronal Differentiation and Maintains Embryonic Stem Cell Pluripotency

The mitochondrion is emerging as a key organelle in stem cell biology, acting as a regulator of stem cell pluripotency and differentiation. In this study we sought to understand the effect of mitochondrial complex III inhibition during neuronal differentiation of mouse embryonic stem cells. When exposed to antimycin A, a specific complex III inhibitor, embryonic stem cells failed to differentiate into dopaminergic neurons, maintaining high Oct4 levels even when subjected to a specific differentiation protocol. Mitochondrial inhibition affected distinct populations of cells present in culture, inducing cell loss in differentiated cells, but not inducing apoptosis in mouse embryonic stem cells. A reduction in overall proliferation rate was observed, corresponding to a slight arrest in S phase. Moreover, antimycin A treatment induced a consistent increase in HIF-1α protein levels. The present work demonstrates that mitochondrial metabolism is critical for neuronal differentiation and emphasizes that modulation of mitochondrial functions through pharmacological approaches can be useful in the context of controlling stem cell maintenance/differentiation.     

Confronting the Paradox of Enrichment to the Metacommunity Perspective

Resource enrichment can potentially destabilize predator-prey dynamics. This phenomenon historically referred as the "paradox of enrichment" has mostly been explored in spatially homogenous environments. However, many predator-prey communities exchange organisms within spatially heterogeneous networks called metacommunities. This heterogeneity can result from uneven distribution of resources among communities and thus can lead to the spreading of local enrichment within metacommunities. Here, we adapted the original Rosenzweig-MacArthur predator-prey model, built to study the paradox of enrichment, to investigate the effect of regional enrichment and of its spatial distribution on predator-prey dynamics in metacommunities. We found that the potential for destabilization was depending on the connectivity among communities and the spatial distribution of enrichment. In one hand, we found that at low dispersal regional enrichment led to the destabilization of predator-prey dynamics. This destabilizing effect was more pronounced when the enrichment was uneven among communities. In the other hand, we found that high dispersal could stabilize the predator-prey dynamics when the enrichment was spatially heterogeneous. Our results illustrate that the destabilizing effect of enrichment can be dampened when the spatial scale of resource enrichment is lower than that of organismss movements (heterogeneous enrichment). From a conservation perspective, our results illustrate that spatial heterogeneity could decrease the regional extinction risk of species involved in specialized trophic interactions. From the perspective of biological control, our results show that the heterogeneous distribution of pest resource could favor or dampen outbreaks of pests and of their natural enemies, depending on the spatial scale of heterogeneity.