The G2/M checkpoint phosphatase cdc25C is located within centrosomes

cdc25C is a phosphatase which regulates the activity of the mitosis promoting factor cyclin B/cdk1 by dephosphorylation, thus triggering G(2)/M transition. The activity and the sub-cellular localisation of cdc25C are regulated by phosphorylation. It is well accepted that cdc25C has to enter the nucleus to activate the cyclin B/cdk1 complex at G(2)/M transition. Here, we will show that cdc25C is located in the cytoplasm at defined dense structures, which according to immunofluorescence analysis, electron microscopy as well as biochemical subfractionation, are proven to be the centrosomes. Since cyclin B and cdk1 are also located at the centrosomes, this subfraction of cdc25C might participate in the control of the onset of mitosis suggesting a further role for cdc25C at the centrosomes.     

Dynamics of agricultural use differentially affect soil properties and crop response in East African wetlands

Agricultural land use changes differentially affect soil fertility and crop production potential of wetlands. We studied East African wetlands with contrasting hydro-geological characteristics (high- and lowland floodplains and valley swamps). Land uses ranged from no use and grazing over crop production in flooded and drained fields to abandonment. We classified the dynamics of wetlands’ conversion into agricultural sites and assessed selected soil fertility attributes associated with land use changes, and their effect on the crop production potential in aerobic and anaerobic soils. A conversion of pristine wetlands, differing in soil physical and chemical attributes, into sites of production tended to negatively affect soil total C and N. Effects were stronger with soil drainage and in the coarse-textured soils of the lowland floodplain and the mid-hill valleys. Mineral P application in drained valleys significantly increased available soil P. Crop response followed these patterns with usually higher biomass accumulation and nutrient uptake in flooded than aerobic soils. Wetlands of fine soil texture in the highlands appeared more resilient than coarse-textured soils, particularly when drained. Enhanced crop performance in flooded soils indicates the possibility for partial recovery of the production potential and the rehabilitation of some wetlands.     

Affinity as a tool in life science

The use of affinity-based tools has become invaluable as a platform for basic research and in the development of drugs and diagnostics. Applications include affinity chromatography and affinity tag fusions for efficient purification of proteins as well as methods to probe the protein network interactions on a whole-proteome level. A variety of selection systems has been described for in vitro evolution of affinity reagents using combinatorial libraries, which make it possible to create high-affinity reagents to virtually all biomolecules, as exemplified by generation of therapeutic antibodies and new protein scaffold binders. The strategies for high-throughput generation of affinity reagents have also opened up the possibility of generating specific protein probes on a whole-proteome level. Recently, such affinity proteomics have allowed the detailed analysis of human protein expression in a comprehensive manner both in normal and disease tissue using tissue microarrays and confocal microscopy.     

Network-based diffusion analysis: a new method for detecting social learning

Social learning has been documented in a wide diversity of animals. In free-living animals, however, it has been difficult to discern whether animals learn socially by observing other group members or asocially by acquiring a new behaviour independently. We addressed this challenge by developing network-based diffusion analysis (NBDA), which analyses the spread of traits through animal groups and takes into account that social network structure directs social learning opportunities. NBDA fits agent-based models of social and asocial learning to the observed data using maximum-likelihood estimation. The underlying learning mechanism can then be identified using model selection based on the Akaike information criterion. We tested our method with artificially created learning data that are based on a real-world co-feeding network of macaques. NBDA is better able to discriminate between social and asocial learning in comparison with diffusion curve analysis, the main method that was previously applied in this context. NBDA thus offers a new, more reliable statistical test of learning mechanisms. In addition, it can be used to address a wide range of questions related to social learning, such as identifying behavioural strategies used by animals when deciding whom to copy.     

Detection of mutations in PCR products from clinical samples by surface plasmon resonance

Two different strategies for scanning and screening of mutations in polymerase chain reaction (PCR) products by hybridization analysis are described, employing real-time biospecific interaction analysis (BIA) for detection. Real-time BIA was used to detect differences in hybridization responses between PCR products and different 17-mer oligonucleotide probes. For the analysis using a biosensor instrument, two different experimental formats were investigated based on immobilization of either biotinylated PCR products or oligonucleotide probes onto a sensor chip. Applied on the human tumour suppressor p53 gene, differences in hybridization levels for full-match and mismatch situations employing both formats allowed the detection of point mutations in exon 6 PCR products, derived from a breast tumour biopsy sample. In addition, a mutant sample sequence could be detected in a 50/50 background of wild type exon 6 sequence. The suitability of the different formats for obtaining a regenerable system and a high throughput of samples is discussed. © 1997 John Wiley & Sons, Ltd.     

Protein encapsulation in liposomes: efficiency depends on interactions between protein and phospholipid bilayer.

Background  

We investigated the encapsulation mechanism of enzymes into liposomes. The existing protocols to achieve high encapsulation efficiencies are basically optimized for chemically stable molecules. Enzymes, however, are fragile and encapsulation requires in addition the preservation of their functionality. Using acetylcholinesterase as a model, we found that most protocols lead to a rapid denaturation of the enzyme with loss in the functionality and therefore inappropriate for such an application. The most appropriate method is based on lipid film hydration but had a very low efficiency.