The evolution of intermediate castration virulence and ant coexistence in a spatially structured environment

Theory suggests that spatial structuring should select for intermediate levels of virulence in parasites, but empirical tests are rare and have never been conducted with castration (sterilizing) parasites. To test this theory in a natural landscape, we construct a spatially explicit model of the symbiosis between the ant-plant Cordia nodosa and its two, protecting ant symbionts, Allomerus and Azteca . Allomerus is also a castration parasite, preventing fruiting to increase colony fecundity. Limiting the dispersal of Allomerus and host plant selects for intermediate castration virulence. Increasing the frequency of the mutualist, Azteca , selects for higher castration virulence in Allomerus , because seeds from Azteca -inhabited plants are a public good that Allomerus exploits. These results are consistent with field observations and, to our knowledge, provide the first empirical evidence supporting the hypothesis that spatial structure can reduce castration virulence and the first such evidence in a natural landscape for either mortality or castration virulence.     

Inhibition of oxidative hemolysis in erythrocytes by mitochondria-targeted antioxidants of SkQ series

In the present work we studied the effect of antioxidants of the SkQ1 family (10-(6′-plastoquinonyl)decyltriphenylphosphonium) on the oxidative hemolysis of erythrocytes induced by a lipophilic free radical initiator 2,2′-azobis(2,4-dimethylvaleronitrile) (AMVN) and a water-soluble free radical initiator 2,2′-azobis(2-methylpropionamidine) dihydrochloride (AAPH). SkQ1 was found to protect erythrocytes from hemolysis, 2 μM being the optimal concentration. Both the oxidized and reduced SkQ1 forms exhibited protective properties. Both forms of SkQ1 also inhibited lipid peroxidation in erythrocytes induced by the lipophilic free radical initiator AMVN as detected by accumulation of malondialdehyde. However, in the case of induction of erythrocyte oxidation by AAPH, the accumulation of malondialdehyde was not inhibited by SkQ1. In the case of AAPH-induced hemolysis, the rhodamine-containing analog SkQR1 exerted a comparable protective effect at the concentration of 0.2 μM. At higher SkQ1 and SkQR1 concentrations, the protective effect was smaller, which was attributed to the ability of these compounds to facilitate hemolysis in the absence of oxidative stress. We found that plastoquinone in the oxidized form of SkQ1 could be reduced by erythrocytes, which apparently accounted for its protective action. Thus, the protective effect of SkQ in erythrocytes, which lack mitochondria, proceeded at concentrations that are two to three orders of magnitude higher than those that were active in isolated mitochondria.     

Secondary biochemical and morphological consequences in lysosomal storage diseases

More than 50 hereditary lysosomal storage disorders (LSDs) are currently described. Most of these disorders are due to a deficiency of certain hydrolases/glycosidases and subsequent accumulation of nonhydrolyzable carbohydrate-containing compounds in lysosomes. Such accumulation causing hypertrophy of the lysosomal compartment is a characteristic feature of affected cells in LSDs. The investigation of biochemical and cellular parameters is of particular interest for understanding “life” of lysosomes in the normal state and in LSDs. This review highlights the wide spectrum of biochemical and morphological changes during developing LSDs that are extremely critical for many metabolic processes inside the various cells and tissues of affected persons. The data presented will help establish new complex strategies for metabolic correction of LSDs.     

The problem of determination of cause of laboratory animal’s death: A critical review of definitions of “fatal” and “incidental” lesions

The determination of the cause of a laboratory animal’s death in gerontological experiments has become extraordinarily urgent in connection with the appearance of ideas on the programmed death of organisms. Unfortunately, the past approach to diagnosis of fatal and incidental changes based only on data of autopsy and histopathology (according to the human pathology model) is not correct for laboratory rodents. Nevertheless, the exact determination of death causes is principally possible in the future under conditions of adequate experimental design (including a large set of clinical, physiological, biochemical, and morphological examinations). However, it seems that even in this case causes of some experimental animal’s death will remain unclear.     

Anti-coccidial and anti-apoptotic activities of palm pollen grains on Eimeria papillata-induced infection in mice

The present work aimed to study the effect of palm pollen extract (PPE) as an anticoccidial and anti-apoptotic modulator during the course of murine intestinal Eimeria papillata infection. The fact that PPE has an anticoccidial efficacy against intestinal E. papillata infection in mice has been clarified by the reduction of faecal output of oocysts on day five post infection from 49.5 × 10³ to 34 × 10³ oocyst/g. Moreover, the number of intracellular eimerian stages of zygots and developing oocysts decreased by about 89% and that of schizonts and gamonts to 42% and 72%, respectively. E. papillata infection also induced an increase in the number of apoptotic cells from 17.5 to 122.8 apoptotic nuclei/10 villous crypt units (VCU). In addition, it caused a state of systemic inflammatory response as revealed by an elevation in levels of the pro-inflammatory biomarkers, inducible nitric oxide synthase (iNOs) and tumor necrosis factor alpha (TNF-α) from 5.3 and 78.3 to 33 pmol ml^?1 and 96.3 pg ml^?1 in blood, respectively, with concurrent duplication in the total leucocytic number. Upon treatment of infected mice with the aqueous PPE, the activity of iNOs was reduced by 55% and the level of TNF-α was decreased by 30%. Moreover, the total leucocytic count was significantly reduced from 9.05 × 10³ to 7.8 × 10³ cells/mm³. Based on our results, PPE showed both anti-coccidial, anti-inflammatory and anti-apoptotic activities. So it can be used in developing new herbal medicine against animal coccidiosis and may be suitable agent for treating eimeriosis associated inflammatory response.     

Flow and Diffusion in Channel-Guided Cell Migration

Collective migration of mechanically coupled cell layers is a notable feature of wound healing, embryonic development, and cancer progression. In confluent epithelial sheets, the dynamics have been found to be highly heterogeneous, exhibiting spontaneous formation of swirls, long-range correlations, and glass-like dynamic arrest as a function of cell density. In contrast, the flow-like properties of one-sided cell-sheet expansion in confining geometries are not well understood. Here, we studied the short- and long-term flow of Madin-Darby canine kidney (MDCK) cells as they moved through microchannels. Using single-cell tracking and particle image velocimetry (PIV), we found that a defined averaged stationary cell current emerged that exhibited a velocity gradient in the direction of migration and a plug-flow-like profile across the advancing sheet. The observed flow velocity can be decomposed into a constant term of directed cell migration and a diffusion-like contribution that increases with density gradient. The diffusive component is consistent with the cell-density profile and front propagation speed predicted by the Fisher-Kolmogorov equation. To connect diffusion-mediated transport to underlying cellular motility, we studied single-cell trajectories and occurrence of vorticity. We discovered that the directed large-scale cell flow altered fluctuations in cellular motion at short length scales: vorticity maps showed a reduced frequency of swirl formation in channel flow compared with resting sheets of equal cell density. Furthermore, under flow, single-cell trajectories showed persistent long-range, random-walk behavior superimposed on drift, whereas cells in resting tissue did not show significant displacements with respect to neighboring cells. Our work thus suggests that active cell migration manifests itself in an underlying, spatially uniform drift as well as in randomized bursts of short-range correlated motion that lead to a diffusion-mediated transport.