Anatomical Structures of the VA Mycorrhiza in the Apocynaceae (Gentianales)

Roots of 19 Apocynaceae species were studied anatomically with respect to their symbiosis with VAM-fungi. In plants collected from the field, VAM-fungi were established in the root cortex. Also, inoculations with different Glomus species on the cultured plants are very successful in the infection and colonization of the root cortex. After penetration of the rhizodermis, the special exodermal short cells become colonized by winding hyphae. Then, in the root cortex of many Apocynaceae species, the VAM-fungi produce intercellular running hyphae which leads to extensive colonization of the root. Arbuscules develop on intracellular running hyphae, whereas vesicles develop mainly on intercellular hyphae. Except for some special details, this is the most common type of colonization of VAM fungi in flowering plants. But in Amsonia tabernaemontana, Nerium oleander, and Thevetia peruviana, another type of colonization could be observed. In these species, the colonization of the hyphae within the root cortex is only possible by intracellular growth. Intercellular running hyphae in the root are lacking. Therefore, after penetration the colonization in the cortex is cluster-like and strictly limited. Only by additional penetrations from hyphae in the soil, will roots show heavy infestations. This type of growth of the VAM fungi in the root is well known from the Gentianaceae and was explained as a structural incompatibility. In Catharanthus roseus, Pachypodium lamerei, and Trachelospermum jasminoides, intermediate stages of both types of colonization could be described. The results are discussed in the search for possible stimulants for structural incompatibility.     

Cloning,Recombinant Expression and Characterization of Wild Type-105-Trp-Calmodulin of the Green Alga Mougeotia scalaris

The single calmodulin gene (CaM) of the green alga Mougeotia scalaris (Hassall) was cloned, sequenced and the CDNA inserted into the prokaryotic expression vector pGEX-2T. The recombinant calmodulin protein (CAM) was expressed as a fusion product together with glutathione S-transferase and isolated on glutathione sepharose. After cleavage and purification, the CaM was characterized by Ca²⁺-dependent shift in SDS-PAGE, by activation of cyclic 3′,5′nucleotide phosphodiesterase (PDE) and sensitivity to the inhibitors trifluoperazine and calmidazolium, with native Mougeotia CaM as control. Using Ca²⁺ buffers in the PDE test, affinity to Ca²⁺ of Mougeotia CaM was found to be diminished fivefold compared to maize or bovine brain CaMs. There was also a 20-fold increase of half maximal activation (K_act) in the PDE test for Mougeotia CaM relative to maize CaM, while the K_act of maize CaM to that of bovine brain CaM was almost the same. The derived amino acid sequences of CaM from Mougeotia and Zea mays revealed three major conservative amino acid exchanges, including unique 105-Trp (Mougeotia) → Leu (maize). In Mougeotia CaM the 105-Trp, including the neighbouring side chains of 92-Phe and 141-Phe, putatively form a hydrophobic ring interaction, as revealed by molecular modelling.     

Biosynthesis of beta-endorphin by the neurointermediate lobes from rats treated with morphine or alcohol

Rats were rendered tolerant to either morphine or alcohol, by 21- day drug treatment. The neurointermediate lobes (NIL) were removed and incubated with [³H]-phenylalanine for 3 hrs. The biosynthesized pro-opiomelanocortin (POMC), β-lipotropin (β-LPH) and β-endorphin- like peptides (β-EPLPs) were purified from the total protein extract of the NIL by immunoprecipitation with an antiserum to β-endorphin (β-EP), and analyzed by sodium dodecyl sulfate polyacrylamide disc gel elecrophoresis. The β-EPLPs were further characterized by extraction from the gel and microsequencing. The homology of rat POMC to authentic bovine POMC was established by extraction from the gel and peptide mapping of its tryptic digestion products. Furthermore, the β-endorphin like immunoreactivity (β-EPLI) was estimated in the incubation medium and in the NIL extract. The morphine treatment induced a decrease in the degree of incorporation of [³H]- phenylalanine into POMC, β-LPH and β-EPLPs, associated with a decrease in the content of β-EPLI in the NIL extract and in the incubation medium. Alcohol induced an increase in the degree of incorporation of [³H]-phenylalanine into POMC, β-LPH and β-EPLPs, and an increase in the β-EPLI content in the incubation medium, but no change in the β-EPLI in the NIL extract. These results indicate an effect of chronic morphine and alcohol treatment on the biosynthesis and release of β-EPLPs by the NIL.     

New method for quantitative determination of water potential of mesophyll cells’ apoplast in substomatal cavity of the leaf

A new method for quantitative determination of water potential of mesophyll cells’ apoplast in substomatal cavity of the leaves of herbaceous (maize, millet, wheat, amaranth, and seepweed) and woody (larch, pine, and birch) plants by means of modern instruments designed to assess photosynthetic(СО₂/Н₂О) gas exchange is described. The method consists in determination in the light of such a level of humidity above the leaf surface, which would nullify transpiration without a noticeable suppression of photosynthetic assimilation of СО₂; this makes it possible to calculate the value of water potential at the interface between aqueous and gaseous phases of mesophyll cells’ apoplast in the substomatal cavity.     

Cultivation of mercury resistent microorganisms

A strain of bacteria was isolated from soil samples. The resistance of these microorganisms to mercury ions was proved by means of discontinuous and continuous fermentations. Continuous fermentation was carried out also at a mercury ion concentration of 250 mg/l. A balance of mercury distributions demonstrates the capability of these bacteria to accumulate a great amount of mercury.