Protein kinase Cdelta signaling downstream of the EGF receptor mediates migration and invasiveness of prostate cancer cells

Tumor progression to the invasive phenotype occurs secondary to upregulated signaling from growth factor receptors that drive key cellular responses like proliferation, migration, and invasion. We hypothesized that Protein kinase Cdelta (PKCdelta)-mediated transcellular contractility is required for migration and invasion of prostate tumor cells. Two invasive human prostate cancer cell lines, DU145 cells overexpressing wildtype human EGFR (DU145WT) and PC3 cells, were studied. PKCdelta is overexpressed in these cells relative to normal prostate epithelial cells, and is activated downstream of EGFR leading to cell motility via modulation of myosin light chain activity. Abrogation of PKCdelta using Rottlerin and specific siRNA significantly decreased migration and invasion of both cell lines in vitro. Both PKCdelta and phosphorylated PKCdelta protein levels were higher in human prostate cancer tissue relative to normal donor prostate as assessed by Western blotting and immunohistochemistry. Thus, we conclude that PKCdelta inhibition can limit migration and invasion of prostate cancer cells.     

Scallop lens Omega-crystallin (ALDH1A9): a novel tetrameric aldehyde dehydrogenase

Scallop eye lens Omega-crystallin is an inactive aldehyde dehydrogenase (ALDH1A9) related to cytoplasmic ALDH1A1 and mitochondrial ALDH2 that migrates by gel filtration chromatography as a homodimer. Because mammalian ALDH1A1 and ALDH2 are homotetramers, we investigated the native molecular mass of scallop Omega-crystallin by multi-angle laser light scattering. The results indicate that the scallop Omega-crystallin is a tetrameric, not a dimeric protein. Moreover, phylogenetic tree analysis shows that scallop Omega-crystallin clusters with the mitochondrial ALDH2 and ALDH1B1 rather than the cytoplasmic ALDH1A, yet it lacks the mitochondrial N-terminal leader sequence characteristic of the mitochondrial ALDHs. The mitochondrial grouping, enzymatic inactivity, and anomalous gel filtration behavior make scallop cytoplasmic Omega-crystallin an interesting protein for structural studies of evolutionary adaptations to become an enzyme-crystallin.     

Effect of diastolic pressure on MLC2v phosphorylation in the rat left ventricle

The effect of passive muscle stretch on the extent of MLC2v phosphorylation was investigated. We used an isolated rat heart preparation and controlled the passive pressure of the left ventricle (LV) at 0 or 15 mmHg. The hearts were flash frozen and the LV free wall was split into epicardial and the endocardial halves. The samples were solubilized using a novel method that minimizes changes in the phosphate content of MLC2v under non-denaturing conditions. The proteins were separated by urea glycerol PAGE and identified by mass spectrometry and Western blots. At 0 mmHg passive pressure, the extent of MLC2v phosphorylation of the epicardium (34.1+/-1.7%) was the same as that of the endocardium (35.3+/-3.4%). At 15 mmHg passive pressure, we found a significant increase in MLC2v phosphorylation in the epicardium (to 41.5+/-2.0%) and a significant reduction in the endocardium (to 24.2+/-1.2%), giving rise to a gradient in the extent of MLC2v phosphorylation from epicardium (high) to endocardium (low). These changes in MLC2v phosphorylation that take place in response to increased diastolic pressure are likely to impact on the calcium sensitivity of actomyosin interaction (with an increased sensitivity towards the epicardium) and may play a role in the Frank-Starling mechanism of the heart.     

Photothermal model of plant development

The development of plants depends on the photoperiod length, light intensity, temperature, and length of light day integral. The reaction of a plant to the day length or daily light integral can depend on both the range of studied light intensities and photoperiod. Based on the data concerning the effects of light and thermal integrals on the developmental rate of plants of different photoperiodic groups, a photothermal model of plant development was proposed. The model was used to calculate the lengths of optimal photoperiods and ranges of daily temperature gradients ensuring the highest developmental rate of some plants, such as soybean, wheat, cucumber, and barley.     

In the presence of ferritin, visible light induces lipid peroxidation of the porcine photoreceptor outer segment

We studied the synergistic effect of visible light and ferritin on the lipid peroxidation on a fraction of porcine photoreceptor outer segment (POS). Reaction mixtures containing the POS fraction and horse spleen ferritin were irradiated under white fluorescent light mainly at 17,000 lx or incubated under dark conditions at 37°C. The lipid peroxidation was evaluated by both the thiobarbituric acid method and the ferrous oxidation/xylenol orange method. The irradiation-induced lipid peroxidation was affected by some experimental factors such as the irradiation dose and acidity of the material. When the irradiation was stopped, the lipid peroxidation was also stopped; thereafter, the re-irradiation induced lipid peroxidation. Moreover, this lipid peroxidation was inhibited by desferrioxamine, an iron chelator, or by dimethylthiourea, a hydroxyl radical scavenger, suggesting that the lipid peroxidation involves hydroxyl radicals generated via the Fenton reaction by iron ion released from ferritin. The lipid peroxidation did not take place under dark conditions or in the absence of ferritin. This study suggested the possibility that the visible light-induced lipid peroxidation of the POS fraction in the presence of ferritin may participate in the etiology of human retinal degenerative diseases as the human retina is exposed to light for life.     

Protein phosphatase activity is necessary for myofibrillogenesis

During myofibrillogenesis, myosin light-chain kinase (MLCK) phosphorylates the regulatory light chain (RLC) of myosin II, enabling patterned assembly of myosin thick filaments. A protein phosphatase (PP) has been shown to mediate RLC dephosphorylation in adult smooth and striated muscle. A role for PP activity in regulating myofibrillogenesis during embryonic development, however, has not been investigated. Tautomycin (TM) was used to inhibit both PP1 and PP2A activities, whereas okadaic acid (OA) and fostriecin (FOS) were used to inhibit PP2A. TM affected both actin and myosin assembly at 5nM; the IC50 value was 20 and 8.5nM, respectively. In contrast, OA applied at 10 times above its reported Ki for PP2A caused no significant disruption. There was also no disruption when FOS was applied at a concentration 30 times above its reported Ki for PP2A. Thus, our results suggest a primary role for PP1 isoforms during myofibrillogenesis. Although rho kinase (RK) regulates PP activity in embryonic smooth and cardiac muscle, application of the RK inhibitor Y27632 did not affect actin or myosin assembly in skeletal myocytes. Collectively, our pharmacological results suggest that PP1 is involved in dynamic regulation of RLC phosphorylation. To specifically test involvement of the myosin-targeted isoform (PP1M), we used a morpholino antisense approach to knock down the myosin targeting (M) subunit of PP1. Embryos injected with morpholino targeted to the 110-kDa M targeting subunit had fewer somites, and myosin organization was significantly perturbed. The combined pharmacological and molecular results suggest a dynamic equilibrium between MLCK and PP1M activities is required for proper myofibrillogenesis.     

The effect of kinetin on the photosynthetic apparatus of Sinapis alba

The influence of kinetin during the development of primary leaves of Sinapis alba was investigated. Kinetin treatment (6 ppm) induced an increase of dry weight, of soluble reducing sugars, soluble protein, chlorophylls, carotenoids and cytochrome f; a higher ratio of chlorophyll a to chlorophyll b, higher rates of CO₂ fixation per fresh weight and higher activity of nitrite reductase, were also found. These effects are comparable with strong and blue light adaptations. On the other hand, the Hill activity with ferricyanide as the electron acceptor, the rates of CO₂ fixation per chlorophyll, the ratios of chlorophyll to cytochrome f and of protein to chlorophyll did not change. Therefore we assume that the kinetin induced and the light induced adaptations are brought about by different causal reaction chains.

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Zusammenfassung Es wurde die Wirkung von Kinetin auf die Entwicklung von Primarblattern von Senfpflanzen untersucht. Die Behandlung mit Kinetin (6 ppm) bewirkte eine Erhöhung des Trochengewichtes, der Gehalte an löslichen, reduzierend wirkenden Zuckern, an löslichem Protein, Chlorophyllen, Karotinoiden und Cytochrom f, sowie eine Erhöhung des Quotienten von Chlorophyll a zu Chlorophyll b, eine verstärkten Einbau von CO₂ pro Frischgewicht und eine Erhöhung der Nitritreduktase-Aktivität. Diese Auswirkungen sind den durch Starklicht und Blaulicht hervorgerufenen Anpassungsreaktionen vergleichbar. Andererseits zeigten die Hill-Reaktion (gemessen als Reduktion von Ferricyanid), die CO₂ Fixierung pro Chlorophyll, der Quotient von Chlorophyll zu Cytochrom f und der Quotient von Protein zu Chlorophyll keire Veränderungen. Dies weist darauf hin, daß die durch Kinetin und durch Licht hervorgerufenen Anpassungsreaktionen durch verschiedene Kausalketten bedingt werden.

     

Anti-inflammatory properties of intestinal Bifidobacterium strains isolated from healthy infants

Certain Bifidobacterium strains have been shown to inhibit inflammatory responses in intestinal epithelial cells. However, the precise mechanisms of these effects, including the chemical nature of the active compounds, remain to be elucidated. Here partial characterization of the anti-inflammatory properties of Bifidobacterium strains isolated from feces of healthy infants is reported. It was found that conditioned media (CM) of all strains studied are capable of attenuating tumor necrosis factor-α (TNF-α) and lipopolysaccharide- (LPS) induced inflammatory responses in the HT-29 cell line. In contrast, neither killed bifidobacterial cells, nor cell-free extracts showed such activities. Further investigations resulted in attribution of this activity to heat-stable, non-lipophilic compound(s) resistant to protease and nuclease treatments and of molecular weight less than 3 kDa. The anti-inflammatory effects were dose- and time-dependent and associated with inhibition of IκB phosphorylation and nuclear factor-κ light chain enhancer of activated B cells (NF-κB)-dependent promoter activation. The combined treatments of cells with CMs and either LPS or TNF-α, but not with CMs alone, resulted in upregulation of transforming growth factor-β1, IκBζ, and p21(CIP) mRNAs. Our data suggest certain species-specificities of the anti-inflammatory properties of bifidobacteria. This observation should prompt additional validation studies using larger set of strains and employing the tools of comparative genomics.     

Co-adaptation of seed dormancy and flowering time in the arable weed Capsella bursa-pastoris (shepherd's purse)

Background and Aims

The duration of the plant life cycle is an important attribute that determines fitness and coexistence of weeds in arable fields. It depends on the timing of two key life-history traits: time from seed dispersal to germination and time from germination to flowering. These traits are components of the time to reproduction. Dormancy results in reduced and delayed germination, thus increasing time to reproduction. Genotypes in the arable seedbank predominantly have short time to flowering. Synergy between reduced seed dormancy and reduced flowering time would create stronger contrasts between genotypes, offering greater adaptation in-field. Therefore, we studied differences in seed dormancy between in-field flowering time genotypes of shepherd''s purse.

Methods

Genotypes with early, intermediate or late flowering time were grown in a glasshouse to provide seed stock for germination tests. Secondary dormancy was assessed by comparing germination before and after dark-incubation. Dormancy was characterized separately for seed myxospermy heteromorphs, observed in each genotype. Seed carbon and nitrogen content and seed mass were determined as indicators of seed filling and resource partitioning associated with dormancy.

Key Results

Although no differences were observed in primary dormancy, secondary dormancy was weaker among the seeds of early-flowering genotypes. On average, myxospermous seeds showed stronger secondary dormancy than non-myxospermous seeds in all genotypes. Seed filling was similar between the genotypes, but nitrogen partitioning was higher in early-flowering genotypes and in non-myxospermous seeds.

Conclusions

In shepherd''s purse, early flowering and reduced seed dormancy coincide and appear to be linked. The seed heteromorphism contributes to variation in dormancy. Three functional groups of seed dormancy were identified, varying in dormancy depth and nitrate response. One of these groups (FG-III) was distinct for early-flowering genotypes. The weaker secondary dormancy of early-flowering genotypes confers a selective advantage in arable fields.     

Seedlings of temperate rainforest conifer and angiosperm trees differ in leaf area display

Background and Aims

The contemporary relegation of conifers mainly to cold or infertile sites has been ascribed to low competitive ability, as a result of the hydraulic inefficiency of tracheids and their seedlings'' initial dependence on small foliage areas. Here it is hypothesized that, in temperate rainforests, the larger leaves of angiosperms also reduce self-shading and thus enable display of larger effective foliage areas than the numerous small leaves of conifers.

Methods

This hypothesis was tested using 3-D modelling of plant architecture and structural equation modelling to compare self-shading and light interception potential of seedlings of six conifers and 12 angiosperm trees from temperate rainforests. The ratio of displayed leaf area to plant mass (LAR_d) was used to indicate plant light interception potential: LAR_d is the product of specific leaf area, leaf mass fraction, self-shading and leaf angle.

Results

Angiosperm seedlings self-shaded less than conifers, mainly because of differences in leaf number (more than leaf size), and on average their LAR_d was about twice that of conifers. Although specific leaf area was the most pervasive influence on LAR_d, differences in self-shading also significantly influenced LAR_d of large seedlings.

Conclusions

The ability to deploy foliage in relatively few, large leaves is advantageous in minimizing self-shading and enhancing seedling light interception potential per unit of plant biomass. This study adds significantly to evidence that vegetative traits may be at least as important as reproductive innovations in explaining the success of angiosperms in productive environments where vegetation is structured by light competition.