Microsporidia are eukaryotic, obligate intracellular organisms defined by their small spores containing a single polar tube that coils around the interior of the spore. After appropriate stimuli the germination of spores occurs. Conditions that promote germination vary widely among species, presumably reflecting the organism’s adaptation to their host and external environment as well as preventing accidental discharge in the environment. It appears that calcium may be a key ion in this process. Regardless of the stimuli required for activation, all microsporidia exhibit the same response to the stimuli, that is, increasing the intrasporal osmotic pressure. This results in an influx of water into the spore accompanied by swelling of the polaroplasts and posterior vacuole. The polar tube then discharges from the anterior pole of the spore in an explosive reaction and is thought to form a hollow tube by a process of eversion. If the polar tube is discharged next to a cell, it can pierce the cell and transfer the sporoplasm into this cell. Polar tubes resist dissociation in detergents and acids but dissociate in dithiothreitol. We have developed a method for the purification of polar tube proteins (PTPs) using differential extraction followed by reverse phase high performance liquid chromatography (HPLC). This method was used to purify for subsequent characterization PTPs from Glugea americanus, Encephalitozoon cuniculit E. hellem and E. intestinalis. These proteins appear to be members of a protein family that demonstrate conserved characteristics in solubility, hydrophobicity, mass, proline content and immunologic epitopes. These characteristics are probably important in the function of this protein in its self assembly during the eversion of the polar tube and in providing elasticity and resiliency for sporoplasm passage.
The paper characterizes the evolution, structure and areal distribution of the large-scale background magnetic fields in the solar photosphere. The direction of the horizontal streaming of the solar photospheric plasma was found. Active regions are formed mainly in places where the global circulation displays maximum
velocity. Filaments occur in the areas with a high value of velocity gradient perpendicular to the filament axis. The relationship between the weak background and the strong local magnetic fields is documented.
Wheat plants were cultivated in a growth chamber at normál (35 Pa, C35 plants) and enhanced (70 Pa, C70 plants) CO2 partial pressure. In C35 plants the net photosynthetic rate (P^) of flag leaves and the concentrations of saccharides such as sucrose, glucose, fructose and starch were increased. The C70 plants possessed higher chlorophyll (Chl) a and Chl b contents. The CO2 response of Pn at saturating photosynthetically active radiation (PAR) was very similar for both variants. At the highest CO2 concentration saccharides accumulated in both variants as a consequence of decreased export rate. The response of to ^t saturating CO2 concentrations was similar in the two variants. On the other hand, the response of water vapour pressure conductance (gH2o) to PAR in C35 plants followed a hyperbolic response to PAR, while in the Cjq plants it was linearly related to PAR up to the mean PAR ušed for growth. In this variant ^^20 seemed to change parallelly to changes in the mesophyll demand for CO2 caused by PAR.
Here we consider the weak congruence lattice $C_{W}(A)$ of an algebra $A$ with the congruence extension property (the CEP for short) and the weak congruence intersection property (briefly the WCIP). In the first section we give necessary and sufficient conditions for the semimodularity of that lattice. In the second part we characterize algebras whose weak congruences form complemented lattices.