Chorioallantoic placentation in Galea spixii (Rodentia,Caviomorpha, Caviidae)

Background  

Placentas of guinea pig-related rodents are appropriate animal models for human placentation because of their striking similarities to those of humans. To optimize the pool of potential models in this context, it is essential to identify the occurrence of characters in close relatives.     

ABC: software for interactive browsing of genomic multiple sequence alignment data

Background  

Alignment and comparison of related genome sequences is a powerful method to identify regions likely to contain functional elements. Such analyses are data intensive, requiring the inclusion of genomic multiple sequence alignments, sequence annotations, and scores describing regional attributes of columns in the alignment. Visualization and browsing of results can be difficult, and there are currently limited software options for performing this task.     

Procathepsin and acid phosphatase are stored in Musca domestica yolk spheres

Yolk spheres present in mature invertebrate oocytes are composed of yolk proteins and proteolytic enzymes. In the fly Musca domestica, yolk proteins are degraded during embryogenesis by a cathepsin-like proteinase that is stored as a zymogen. An acid phosphatase is also active in the yolk spheres during Musca embryogenesis. In this paper we show that procathepsin and acid phosphatase are initially stored by a different pathway from the one followed by yolk protein precursors. Both enzymes are taken up by the oocytes and transitorily stored into small vesicles (lysosomes) surrounding the early yolk spheres. Fusion of both structures, the early yolk spheres and lysosomes, creates the mature yolk spheres.     

Optimization of the antimicrobial activity of magainin peptides by modification of charge

Investigation of magainin II amide analogs with cationic charges ranging between +3 and +7 showed that enhancement of the peptide charge up to a threshold value of +5 and conservation of appropriate hydrophobic properties optimized the antimicrobial activity and selectivity. High selectivity was the result of both enhanced antimicrobial and reduced hemolytic activity. Charge increase beyond +5 with retention of other structural motifs led to a dramatic increase of hemolytic activity and loss of antimicrobial selectivity. Selectivity could be restored by reduction of the hydrophobicity of the hydrophobic helix surface (H(hd)), a structural parameter not previously considered to modulate activity. Dye release experiments with lipid vesicles revealed that the potential of peptide charge to modulate membrane activity is limited: on highly negatively charged 1-palmitoyl-2-oleoylphosphatidyl-DL-glycerol bilayers, reinforcement of electrostatic interactions had an activity-reducing effect. On neutral 1-palmitoyl-2-oleoylphosphatidylcholine bilayers, the high activity was determined by H(hd). H(hd) values above a certain threshold led to effective permeabilization of all lipid systems and even compensated for the activity-reducing effect of charge increase on highly negatively charged membranes.     

Characteristics of antioxidant properties of 20-hydroxyecdysone in low density lipoproteins by kinetic parameters of chemiluminescence

20-Hydroxyecdysone is capable to terminate the lipid free-radical oxidation in low density lipoprotein in vitro as displayed by the kinetic chemiluminescence parameters. In concentrations interval from 2 x 10(-6) mol/l up to 8 x 10(-6) mol/l it statistically reliably reduces maximum of the first flash intensity of the low density lipoprotein Fe(2+)-initiated chemiluminescence. It testifies about Fe(2+)-initiated lipid peroxide process decomposition in low density lipoprotein slowing down by 20-hydroxyecdysone. In concentration of 20-hydroxyecdysone 8 x 10(-6) mol/l the statistically reliable reduction of angle tangent of an ascending branch of the second flash of low density lipoprotein Fe(2+)-initiated chemiluminescence was found. This is a result of free-radical lipid oxidation rate reduction in the low density lipoprotein at the 20-hydroxyeodysone presence. The equations of the kinetic parameters linear dependences Fe(2+)-initiated chemiluminescence in low density lipoprotein on the concentration of 20-hydroxyeodysone and hydroquinone have been received. The correlation factors in the interval from 0.8980 up to 0.6789 have been calculated. Thus, the assumption has been forwarded that 20-hydroxyeodysone has antioxidizing properties. However, its antioxidizing activity in free radical lipid oxidation of is low density lipoprotein is as less as for hydroquinone.     

A two-photon and second-harmonic microscope

Two-photon microscopy has revolutionized life sciences by enabling long-term imaging of living preparations in highly scattering tissue while minimizing photodamage. At the same time, commercial two-photon microscopes are expensive and this has prevented the widespread application of this technique to the biological community. As an alternative to commercial systems, we provide an update of our efforts designing custom-built two-photon instruments by modifying the Olympus FluoView laser scanning confocal microscope. With the newer version of our instrument we modulate the intensity of the laser beam in arbitrary spatiotemporal patterns using a Pockels cell and software control over the scanning. We can also perform simultaneous optical imaging and optical stimulation experiments and combine them with second harmonic generation measurements.     

Multiphoton stimulation of neurons

We pulsed the activation of neurons using a femtosecond laser. Pyramidal neurons are depolarized and fire action potentials when high intensity mode-locked infrared light irradiates somatic membranes and axon initial segments. This depolarization is reversible, does not occur with CW laser light, and appears to be due to multiphoton excitation. We describe two regimes of multiphoton optical stimulation. Low intensity, long duration laser irradiation produces a sustained depolarization, insensitive to sodium channel blockers yet sensitive to antioxidants. On the other hand, high intensity, short duration irradiation can induce fast depolarizations, which appear due to different mechanism. The combination of multiphoton stimulation and optical probing could enable systematic analysis of circuits.     

Behavioral impairments in Morris water maze in rats selectively bred for audiogenic seizure susceptibility (Krushinsky-Molodkina strain)

Krushinsky-Molodkina rats (KM strain) with genetically determined seizure susceptibility (clonic and tonic seizures in response to the sound of an electric bell, Krushinsky, 1960) were tested in two versions of Morris water maze and compared with normal albino rats (Sprague-Dawley and Wistar). The tests revealed a learning deficit in KM rats. They showed slow acquisition in both the spatial version of the test and the version with the platform, less efficient strategy of searching for target platform, and high scores of floating and thigmotaxis. However, males of KM rats (not females) did not differ significantly from Wistar strain in the probe trial in the spatial variant of the Morris test. No preference for searching for the platform at the place of its previous localization was observed in KM females. Together with our previous findings of the low scores in Revecz-Krushinsky test and data of other authors (Batuev et al., 1983) concerning a working memory deficit in the radial maze, the results suggest the of complex cognitive deficit combined with possible increased stress reactivity in KM rats.     

Differentiation of naive CD4<Superscript>+</Superscript> T cells towards T helper 2 cells is not impaired in rheumatoid arthritis patients

An impaired differentiation of naive CD4+ T cells towards Th2 cells may contribute to the chronic tissue-destructive T-cell activity in rheumatoid arthritis (RA). The differentiation of naive CD4+ T cells into memory Th2 cells by IL-7 in comparison with that by IL-4 was studied in RA patients and in healthy controls. Naive CD4+ T cells from peripheral blood were differentiated by CD3/CD28 costimulation in the absence of or in the presence of IL-7 and/or IL-4. The production of IFN-gamma and IL-4 was measured by ELISA and by single-cell FACS analysis to indicate Th1 and Th2 cell activity. CD3/CD28 costimulation and IL-7 were early inducers of IL-4 production, but primarily stimulated IFN-gamma production. In contrast, in short-term cultures exogenously added IL-4 did not prime for IL-4 production but suppressed IL-7-induced IFN-gamma production. Upon long-term stimulation of naive CD4+ T cells, IFN-gamma production was differentially regulated by IL-7 and IL-4, but IL-4 production was increased by both IL-7 and IL-4. IL-7 and IL-4 additively induced polarization towards a Th2 phenotype. This susceptibility of naive CD4+ T cells to become Th2 cells upon culture with IL-7 and IL-4 was increased in RA patients compared with that in healthy controls. These findings demonstrate that, in RA patients, differentiation of naive CD4+ T cells towards a Th2 phenotype by CD3/CD28 costimulation, IL-7 and IL-4 is not impaired. The perpetuation of arthritogenic T-cell activity in RA therefore seems not to be the result of intrinsic defects of naive CD4+ T cells to develop towards suppressive memory Th2 cells.