Purification, cloning and characterization of a novel peroxidase isozyme from sweetpotatoes (Ipomoea batatas)

An anionic peroxidase from sweetpotato tubers is purified and characterized. The isozyme ibPrx15 is purified to homogeneity by affinity chromatography using a concanavalin A column. The isoelectric point was determined to pI 4.9. MALDI-MS detected a singly charged molecule with a mass of 42029 Da. Absorption spectra of ibPrx15 compounds I, II and III were obtained after treatment with H(2)O(2) at room temperature. Comparative data of ibPrx15 on substrate specificity to tobacco anionic peroxidase (TOP) and horseradish peroxidase (HRP) reveal similar specific activity towards a series of conventional substrates except for iodide, which is a two-electron donor interacting directly with the compound I derivative in the catalytic cycle. ibPrx15 exhibits a high specific activity towards iodide about 10(3)-fold to that of tobacco peroxidase. The amino acid sequence of the main isozyme ibPrx15 was determined by Edman degradation and by sequencing the amplified cDNA fragments. ibPrx15 has 86% identity to another Ipomoea sequence ibPrx05 and 72% identity with a sequence from Populus trichocarpa (PtPrx72).     

Light data from geolocation reveal patterns of nest visit frequency and suitable conditions for efficient nest site monitoring in Common Swifts Apus apus

ABSTRACT

Capsule: We developed a protocol for efficient monitoring of potential Common Swift Apus apus nest sites which considers variation in nest visit frequency across the breeding season and in relation to time of day and weather.

Aims: To investigate patterns of nest visit frequency in Common Swifts in order to improve the efficiency and reliability of the monitoring of nest sites threatened by building renovations.

Methods: We derived information on nest attendance from light data recorded by geolocators from ten adult Common Swifts during three breeding seasons (n?=?686 individual sampling days) and analysed how nest visit frequency varied across the breeding season and in relation to time of day and weather.

Results: The mean nest visit frequency was 5.63 visits per bird per day (0.32 visits per hour of daylight). The daily number of visits was highest at the beginning of July during chick-rearing. Moreover, it was positively correlated with temperature and negatively correlated with rainfall and wind speed. Nest visit frequency showed a distinct peak around sunset, while also being relatively high in the morning and around noon.

Conclusion: We recommend monitoring potential Common Swift nest sites in Central Europe between the end of June and mid-July during good weather between 0.50 and 7.75?h after sunrise or between 3.00?h before sunset and sunset, when observation bouts of 0.5–2.0?h provide an encounter probability greater than 90%. Our study shows that repurposing geolocator light data – usually used to study bird migration – for investigating nest attendance in cavity-breeding birds can provide important information for bird conservation.     

Complement Component C3 Is Highly Expressed in Human Pancreatic Islets and Prevents β Cell Death via ATG16L1 Interaction and Autophagy Regulation

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Repeated visitations of spermatophores and polyandry in females of eriophyoid mites

Eriophyoid females store sperm either asymmetrically in one spermatheca, or symmetrically in both spermathecae. Previous studies have suggested that species in which females store sperm asymmetrically pick up sperm from only one spermatophore, while those with symmetrical sperm storage pick up sperm from two or more spermatophores during their lifetime. The aim of this study was to examine spermatophore visitation behaviour and symmetry of sperm storage in Aculops allotrichus from the black locust tree and Cecidophyopsis hendersoni from the yucca. This would indicate monandry or polyandry in these species. In both eriophyoids, the spermatophore visitation consisted of three phases: mounting, lying on the spermatophore and dismounting. Aculops allotrichus stored sperm asymmetrically. However, nearly one-third of the observed females visited two spermatophores, rather than only one in their lives. When A. allotrichus females visited two spermatophores they spent a similar amount of time at the first and at the second visitation. Also, the times of visitation of the first of the two spermatophores and the single spermatophore in a female lifetime did not differ significantly. This would suggest that apart from monandry, double insemination also occurs in this species. By contrast, C. hendersoni females were polyandrous. They stored sperm symmetrically and visited several spermatophores, on average 1.54 (max 6) per day, and up to 33 spermatophores in their lives. The benefits of repeated spermatophore visitation and the possible mechanisms of sperm storage in both species are discussed.     

Species specific behavioural patterns (digging and swimming) and reaction to novel objects in wild type, Wistar, Sprague-Dawley and Brown Norway rats

Background

The purpose of the present study was to analyse species-specific forms of behaviour (digging and swimming) and response to novelty in laboratory rats and their wild type counterparts at a very early stage of laboratorization. Three behavioural phenomena were taken into account: burrowing, spontaneous swimming, and neophobic behaviour.

Principal Findings

Wild-type rats and three strains of laboratory rats were involved in experiments: Warsaw-Wild-Captive-Pisula-Stryjek (WWCPS), Wistar, Sprague-Dawley, and Brown Norway rats were compared in spontaneous swimming test, while WWCPS and Wistar rats were studied in burrowing and neophobia experiments. Wild rats were found to be faster at building tunnels than Wistar rats and at constructing more complex burrow systems. The experiment on neophobia showed that Wistar rats exhibited less neophobic responses and were more often trapped. WWCPS rats showed highly neophobic behaviour and were rarely trapped in this experiment. The experiment on swimming showed that WWCPS rats showed more complex water tank related activity than their laboratory counterparts. They swam and explored under surface environment.

Conclusions

The three experiments showed profound behavioural differences in quasi-natural forms of behaviour between wild type rats (WWCPS) and three laboratory strains frequently used in behavioural studies.     

Regulation of adherens junctions by Rho GTPases and p120-catenin

The molecular mechanisms leading to tumor progression and acquisition of a metastatic phenotype are highly complex and only partially understood. The spatiotemporal regulation of E-cadherin-mediated adherens junctions is essential for normal epithelia function and tissue integrity. Perturbation of the E-cadherin complex assembly is a key event in epithelial-mesenchymal transition and is directed by a huge number of mechanisms that differ greatly with regard to cell types and tissues. The reduction in intercellular adhesion interferes with tissue integrity and allows cancer cells to disseminate from the primary tumor thereby initiating cancer metastasis. In the present review we will summarize the current findings about the influence of Rho GTPases on the formation and maintenance of adherens junction and will then proceed to discuss the involvement of p120-catenin on cell-cell adhesion and tumor cell migration.     

Differential interference of chlorpromazine with the membrane interactions of oncogenic K-Ras and its effects on cell growth

Membrane anchorage of Ras proteins is important for their signaling and oncogenic potential. K-Ras4B (K-Ras), the Ras isoform most often mutated in human cancers, is the only Ras isoform where a polybasic motif contributes essential electrostatic interactions with the negatively charged cytoplasmic leaflet. Here we studied the effects of the cationic amphiphilic drug chlorpromazine (CPZ) on the membrane association of oncogenic K-Ras(G12V), cell proliferation, and apoptosis. Combining live cell microscopy, FRAP beam size analysis, and cell fractionation studies, we show that CPZ reduces the association of GFP-K-Ras(G12V) with the plasma membrane and increases its exchange between plasma membrane and cytoplasmic pools. These effects appear to depend on electrostatic interactions because the membrane association of another related protein that has a membrane-interacting polybasic cluster (Rac1(G12V)) was also affected, whereas that of H-Ras was not. The weakened association with the plasma membrane led to a higher fraction of GFP-K-Ras(G12V) in the cytoplasm and in internal membranes, accompanied by either cell cycle arrest (PANC-1 cells) or apoptosis (Rat-1 fibroblasts), the latter being in correlation with the targeting of K-Ras(G12V) to mitochondria. In accord with these results, CPZ compromised the transformed phenotype of PANC-1 cells, as indicated by inhibition of cell migration and growth in soft agar.     

Rac1 activation inhibits E-cadherin-mediated adherens junctions via binding to IQGAP1 in pancreatic carcinoma cells

Nck is a ubiquitously expressed adapter protein that is almost exclusively built of one SH2 domain and three SH3 domains. The two isoproteins of Nck are functionally redundant in many aspects and differ in only few amino acids that are mostly located in the linker regions between the interaction modules. Nck proteins connect receptor and non-receptor tyrosine kinases to the machinery of actin reorganisation. Thereby, Nck regulates activation-dependent processes during cell polarisation and migration and plays a crucial role in the signal transduction of a variety of receptors including for instance PDGF-, HGF-, VEGF- and Ephrin receptors. In most cases, the SH2 domain mediates binding to the phosphorylated receptor or associated phosphoproteins, while SH3 domain interactions lead to the formation of larger protein complexes. In T lymphocytes, Nck plays a pivotal role in the T cell receptor (TCR)-induced reorganisation of the actin cytoskeleton and the formation of the immunological synapse. However, in this context, two different mechanisms and adapter complexes are discussed. In the first scenario, dependent on an activation-induced conformational change in the CD3ε subunits, a direct binding of Nck to components of the TCR/CD3 complex was shown. In the second scenario, Nck is recruited to the TCR complex via phosphorylated Slp76, another central constituent of the membrane proximal activation complex. Over the past years, a large number of putative Nck interactors have been identified in different cellular systems that point to diverse additional functions of the adapter protein, e.g. in the control of gene expression and proliferation.