DPC played an important role in regulating the production, translocation and partítioning of i‘*C-assimilates in cotton {Gossypium hirsutum L.) plants. Seed soaking with DPC increased the partítioning of cotton assimilates into roots aitd main stem, and decreased the partítioning into seedling tip which was beneficial for the seedling. After the appearance of a square, spraying with DPC decreased the partítioning of assimilates into the main stem, branches and their growing points, and increased the partítioning into reproductíve organs and roots. This helped to avoid or reduce spindling, ensured a steady growth, coordination of the relatíon between vegetatíve and reproductíve organs, and improved the development of floral buds. From bloom to boll-setting,. sprayings with DPC greatly increased the partítioning of assimilates into reproductíve organs and decreased the partítioning into vegetatíve organs, which was usefiil for the growth and development of squares and bolls.
The effect of enhanced air CO2 concentrations (C520 and 0^50 = 520 and 650 cm^ m"^) on the growth of Lamium galeobdolon and Stellaria holostea and on the competition between the two species was examined. After five months growth imder CO2 enrichment the dry masses of both species increased when the plants were grown in monoculture, but the increase in biomass was much more pronounced in Stellaria. When the plants were grown together in competition, the measured shoot masses of Stellaria were again higher under C520 and 0^50 than at ambient CO2 concentration (C390 = 390 cm^ m'^), while the shoot masses of Lamium strongly decreased at Cgso- The effect of CO2 enrichment on the two plant species in monoculture differed significantly from that observed in mixed cultures. In terms of plant relative yield, Stellaria benefitted slightly but insignificantly from competition, while Lamium was significantly suppressed imder c^sq. Total community production of the mixed culture was optimum at C520, while that of the monocultures was highest at c^sq. At C390 and C520, growth of Stellaria depended strongly on irradiance in all types of culture. At C650 no such dependence could be demonstrated.
The effect of exposure to miracidia of Schistosoma mansoni Sambon on mortality rates of five different age-groups of Biomphalarìa pfeifferi (Krauss) was investigated under carefully controlled conditions in the laboratory. The per capita mortality rates were determined for each age-group and the mean life expectancy and mean snail mortalities per week calculated. It was demonstrated that the cohorts of snails exposed to three miracidia per snail at an age of one week suffered the highest mortalities during the prepatent period and had the shortest life-span. No significant differences could be indicated in these respects between cohorts of snails exposed at an age of three, four and five weeks to the same number of miracidia. The results of this investigation could make a significant contribution towards establishing and maintaining laboratory cultures of S. mansoni.
In morphological and biochemical studies we demonstrated that the development of eight-day old dark-grown beán seedlings was drastically influenced by prolonged irradiation with far red (FR) irradiation. The synthetic processes associated with leaf expansion were fiilly active, but the accumulation of chJorophyll (Chl) was very slow and the development of the photosynthetic apparatus was much prolonged. The capacity for oxygen evolution and photophosphorylation began at about the 2''‘* day. Low temperature spectroscopy showed the accumulation of three Chl a forms with absorption maxima at 670, 677 and 683 nm from the veiy beginning of the greening process and the appearance of two longer wavelength forms (with maxima at 690 and 698 nm) at the onset of photosynthetic activity. Electron microscopy showed unfiised stacks of primary thylakoids without grana formation. When the FR treated seedlings were subsequently placed in "white light", grana differentiated from these primary thylakoids.
After a S-d cultivatíon in Solutions of different concentrations of lead and copper, structiiral changes were established in the photosynthetic apparatus of Elodea canadensis Rich. Lead and low concentrations of copper (0.03, 0.06 and 0.25 g m’^) did not induce large structural transformations in the protoplast. Some of the changes were specific for the species; vacuolization of the cytoplasm, instability of the tonoplast, increased activity of the dictyosomes, abnormally active division of the mitochondria, and number of chloroplasts and mitochondria in definite cell zones. High concentrations of copper (0.5, 1 and 1.5 g m*^) induced within 5 d a generál destruction of the protoplast. The concentration of 0.5 g(Cu^0 threshold concentration for survival of this species. High quantities of both metals were accumulated in the treated plants.
10-d-old pea plants {Pisum sativum L. cv. Ran 1) were treated for 24 h with proline (10-6 M oř 10*5 M) before salinization with 50 mM NaCl for 2 d. Salt stress resulted in an increase of endogenous ffee proline content, CO2 compensation concentration, photorespiration and glycollate oxidase activity; net photosynthetic rate (P^) was inhibited, but dark respiration rate (Pp) was not affected. •‘♦CO2 fixation by protoplasts isolated from salt stressed plants was inhibited by 60 %, however, the *‘*C02 fixation by protoplasts, isolated firom plants treated with proline before salinization, was only slightly reduced by NaCl. Proline alleviated the inhibitory effect of NaCl in a concentration-depending manner. Pre-treatment with proline decreased Na+ and CP accumulation in the shoot; the root content of these ions was increased.
A technique based on the analysis of banding patterns obtained by SDS-PAGE Western-blotting of an oocyst wall antigen obtained from faeces has been evaluated to subtype Cryptosporidium parvum Tyzzer, 1912. This technique appears to have sufficient stability to recognise multiple types of this parasite. A similar Western-blotting technique has also been used to assess antibody responses to cryptosporidial antigens in human sera. Two systems were developed: one against three antigens of apparent molecular weights 6, 14 and 17 kDa; the second against oocyst wall antigens of apparent molecular weights 57, 69, 75, 89, 128, 151 and 173 kDa. Antibodies to three antigens of apparent molecular weights 6, 14 and 17 kDa were most successful as diagnostic markers in that they were found in >88% of convalescent phase sera from confirmed cryptosporidiosis patients and were uncommon (>7%) in control subjects. Faecal samples from human and animal sporadic cases yielded a wide range of cryptosporidial antigen banding patterns. Samples from patients in a water-borne outbreak in South Devon (England) in 1995 also yielded a wide range of banding patterns including members within individual household family groups. These results are in contrast with those from samples collected from other defined geographical areas, including some from a second water-borne outbreak where much more homogeneous banding patterns were obtained. Sera collected for other purposes from apparently uninfected individuals 9 months after the South Devon 1995 outbreak were examined. Antibodies to the three antigens of molecular weights 6, 14 and 17 kDa were detected in 32-49% of individuals resident in the outbreak water supply area, and in 15-21%) of those resident in an adjacent water supply area. The significance of these findings is discussed in relation to data obtained from epidemiological field studies.