Ytterbium increases transmembrane water transport in Zea mays roots via aquaporin modulation.

In our study, the rare earth element ytterbium (Yb3+) was demonstrated to affect water exchange in roots of Zea mays seedlings. Herewith, the overall membrane permeability (Pd) increased. The Pd increase was determined by aquaporin activity but not the membrane lipid component since the closure of aquaporin channels due to low intracellular pH abolished the positive effect of Yb3+ on Pd. Additionally, the expression level of aquaporin genes ZmPIP2;2, ZmPIP2;6 and ZmTIP2;2 was increased when plants were grown in the presence of Yb3+. Our results indicate that previously described positive influence of rare earth metals on plant growth and productivity may be mediated (at least partially) by the modification of the plant hydraulic system.

Characteristics of water and ion exchange of Elodea nuttallii cells at high concentrations of lanthanides.

Changes of diffusive permeability of membranes of Elodea nuttallii cells following a short-term (60 min) treatment with high concentrations of lanthanides were recorded by the 1H NMR-diffusometry and conductometry methods. The 1-h infiltration of segments of Elodea nuttallii internodes in 10 mM solutions of nitrates of La, Nd and Lu resulted in the increased leakage of electrolytes from cells, but has no effect on a water diffusive permeability of membranes. In samples subjected to a 30 min pretreatment with a water channel inhibitor HgCl2 the water diffusive permeability of membranes (Pd) drops down under the influence of lanthanides, as well as an outcome of electrolytes. To explain the observed effects the change of spontaneous curvature of membrane lipid layer has been taken into consideration. The interaction of lanthanides with lipids of plasmalemma leads to the negative spontaneous curvature of lipid layer at which membrane channels are unclosed. Blocking of the ionic and water channels by mercury ions compensate the effect of change of spontaneous curvature of lipid layer.

Dynamic properties of water in breast pathology depend on the histological compounds: distinguishing tissue malignancy by water diffusion coefficients.

BACKGROUND: The parameters that characterize the intricate water diffusion in tumors may also reveal their distinct pathology. Specifically, characterization of breast cancer could be aided by diffusion magnetic resonance.The present in vitro study aimed to discover connections between the NMR biexponential diffusion parameters [fast diffusion phase (D(FDP)), slow diffusion phase (D(SDP)), and spin population of fast diffusion phase (P1)] and the histological constituents of nonmalignant (control) and malignant human breast tissue. It also investigates whether the diffusion coefficients indicate tissue status. METHODS: Post-surgical specimens of control (mastopathy and peritumoral tissues) and malignant human breast tissue were placed in an NMR spectrometer and diffusion sequences were applied. The resulting decay curves were analyzed by a biexponential model, and slow and fast diffusion parameters as well as percentage signal were identified. The same samples were also histologically examined and their percentage composition of several tissue constituents were measured: parenchyma (P), stroma (St), adipose tissue (AT), vessels (V) , pericellular edema (PCE), and perivascular edema (PVE). Correlations between the biexponential model parameters and tissue types were evaluated for different specimens. The effects of tissue composition on the biexponential model parameters, and the effects of histological and model parameters on cancer probability, were determined by non-linear regression. RESULTS: Meaningful relationships were found among the in vitro data. The dynamic parameters of water in breast tissue are stipulated by the histological constituents of the tissues (P, St, AT, PCE, and V). High coefficients of determination (R2) were obtained in the non-linear regression analysis: D(FDP) (R2 = 0.92), D(SDP) (R2 = 0.81), and P1(R2 = 0.93).In the cancer probability analysis, the informative value (R2) of the obtained equations of cancer probability in distinguishing tissue malignancy depended on the parameters input to the model. In order of increasing value, these equations were: cancer probability (P, St, AT, PCE, V) (R2 = 0.66), cancer probability (D(FDP), D(SDP))(R2 = 0.69), cancer probability (D(FDP), D(SDP), P1) (R2 = 0.85). CONCLUSION: Histological tissue components are related to the diffusion biexponential model parameters. From these parameters, the relative probability of cancer in a given specimen can be determined with some certainty.

Quantitative permeability imaging of plant tissues.

A method for mapping tissue permeability based on time-dependent diffusion measurements is presented. A pulsed field gradient sequence to measure the diffusion encoding time dependence of the diffusion coefficients based on the detection of stimulated spin echoes to enable long diffusion times is combined with a turbo spin echo sequence for fast NMR imaging (MRI). A fitting function is suggested to describe the time dependence of the apparent diffusion constant in porous (bio-)materials, even if the time range of the apparent diffusion coefficient is limited due to relaxation of the magnetization. The method is demonstrated by characterizing anisotropic cell dimensions and permeability on a subpixel level of different tissues of a carrot (Daucus carota) taproot in the radial and axial directions.