Production of Potato Spindle Tuber Viroid (PSTV) by Large Scale Fermentation of PSTY-Infected Potato Cell Suspension Cultures

Berlin, J., Wray, V., Forche, E., Reng, H.–G , Schler,H, Luckinger, R. and Mhlbach, H.–P. 1985. Production ofpotato spindle tuber viroid (PSTV) by large scale fermentationof PSTV–infected potato cell suspension cultures.—J.exp. Bot 36: 1985–1995. Cell suspension cultures of Solatiumdemissum, infected with the potato spindle tuber viroid (PSTV),were scaled up to volumes of up to 800 dm³ to provide sufficientand uniform plant material for subsequent studies on viroidbiosynthesis. Here we describe the technological aspects ofproducing the required amounts of biomass and viroid. The cells,which had been maintained on a medium containing expensive coconutmilk, were first adapted to rapid growth on the less expensiveB5–medium. The physiological state of the cells was monitoredby in vivo ³¹P–NMR spectroscopy Under the chosen conditionsthe scale–up from 10 dm³ inoculum from shake flasks tothe harvest of the 800 dm³ stirred fermenter lasted 38 d andprovided 112 kg biomass. Growth characteristics and viroid productionin shake flasks and large bioreactors were rather similar. Gelelectrophoretic analysis of isolated nucleic acids using silverstaining and Northern blot hybridization revealed a PSTV–contentof approximately 700 µg PSTV per kg fresh mass of culturedcells. Key words: Solanum demissum, plant cell cultures, potato spindle tuber viroid, biomass production, fermentation, in vivo ³¹P-NMR     

An Electron Microscope Study of the Path of Water Movement in Transpiring Leaves of Cotton (Gossypium hirsulum L.)

Precipitation of ferrocyanide by ferric ions in cotton leavesproduced electron-opaque crystals visible with othe electronmicroscope and identifiable as Prussian blue by X-ray and electrondiffraction. These crystals were formed within the lumina andexposed primary walls of the tracheary elements but not withintheir secondary walls. The precipitation pattern indicated thatwater moved from the tracheary elements into the parenchymaof the bundle sheath and bundle sheath extensions. From thesecells water moved into the epidermis or through the mesophyllto the transpirational exits. Prussian blue accumulated in thewalls of cells lining the substomatal cavities and to a lesserextent between adjacent covering hairs. Ferrocyanide anionsdid not follow the water stream through the cuticle. In parenchymaand epidermal cells Prussian blue crystals were found withinthe primary wall, in the region between the plasma-lemma andthe cell wall, and within the protoplast.     

Covert Categories and Folk Taxonomies

Much of the recent work in ethnoscience has been concerned with the nature of folk taxonomies, an often stated definition of which requires that all folk taxa be monolexemically labeled. This paper offers evidence that unlabeled categories may also be of crucial taxonomic significance, and we feel that it is inappropriate to treat such categories apart from the named taxonomic entities of the system. More importantly, evidence presented indicates that by recognizing unnamed taxa one may gain an understanding of the structure of a particular semantic domain that is actually obscured if one focuses solely on lexically labeled units.     

Differential survival and reproduction in colour forms of Philaenus spumarius give new insights to the study of its balanced polymorphism

1. Colour polymorphisms are common across animals and are often the result of complex selection regimes. Philaenus spumarius (Linnaeus) (Hemiptera, Aphrophoridae) shows a widely studied dorsal colour polymorphism with several described phenotypes whose variation in their occurrence and frequency, as well as their maintenance across time, have been reported. Several selective influences have been suggested to play a role, but the mechanisms underlying the maintenance of this polymorphism are still poorly understood. 2. To explore the adaptive significance of the colour polymorphism of P. spumarius, an experiment was conducted in captivity under semi‐natural conditions to measure survival, reproductive success, and duration of egg maturation. 3. It was found that there was higher longevity, a higher number of oviposition events, and a higher number of eggs laid by trilineatus phenotype females than by typicus and marginellus, supporting previous reports of an increase in trilineatus frequency during the season. The duration of egg maturation did not differ among phenotypes. 4. The higher longevity and fertility of the trilineatus phenotype may compensate, for example, the higher rate of attack by parasitoids and/or higher solar radiation reflectance in this phenotype, which have already been reported in previous studies, constituting a possible mechanism for the maintenance of this polymorphism.     

Predicted warming and browning affect timing and magnitude of plankton phenological events in lakes: a mesocosm study

1. Aquatic ecosystems in Northern Europe are expected to face increases in temperature and water colour (TB) in future. While effects of these factors have been studied separately, it is unknown whether and how a combination of them might affect phenological events and trophic interactions. 2. In a mesocosm study, we combined both factors to create conditions expected to arise during the coming century. We focused on quantifying effects on timing and magnitude of plankton spring phenological events and identifying possible mismatches between resources (phytoplankton) and consumers (zooplankton). 3. We found that the increases in TB had important effects on timing and abundance of different plankton groups. While increased temperature led to an earlier peak in phytoplankton and zooplankton and a change in the relative timing of different zooplankton groups, increased water colour reduced chlorophyll‐a concentrations. 4. Increased TB together benefitted cladocerans and calanoid copepods and led to stronger top‐down control of algae by zooplankton. There was no sign of a mismatch between primary producers and grazers as reported from other studies. 5. Our results point towards an earlier onset of plankton spring growth in shallow lakes in future with a stronger top‐down control of phytoplankton by zooplankton grazers.     

The Effects of Hydroxyl Radical Attack on Dopa,Dopamine, 6-Hydroxydopa,and 6-Hydroxydopamine

High pressure liquid chromatography with electrochemical detection (HPLC-ED) was employed in conjugation with a sensitive and specific salicylate hydroxylation assay to evaluate the immediate effects of hydroxyl radical (·OH) attack on four catechol intermediates of eumelanin, dopamine (3,4-dihydroxyphenylethylamine), its precursor dopa (3,4-dihydroxyphenylalanine), and their respective neurotoxic trihydroxyphenyl derivatives, 6-hydroxydopamine (2,4,5-trihydroxyphenylethylamine,6-OHDA) and 6-hydroxydopa(2,4,5-trihydroxyphenylalanine, TOPA). Semiquinone and quinone species were identified as the initial products of the oxidation of these four catechol substrates. The enhanced oxidations of the catechols when exposed to ·OH attack was accompanied by marked decreases in the level of each semiquinone species. Quinone levels were elevated in reactions involving ·OH attack on dopamine and 6-OHDA, but absent in reactions involving radical attack on dopa or TOPA, suggesting that dopaquinone (DOQ) and TOPA p-quinone (TOPA p-Q) are oxidized more rapidly by‘OH than are the quinones of dopamine and 6-OHDA. The formation of 6-OHDA p-quinone (6-OHDA p-Q) in incubations involving DA and ·OH suggest that the ·OH-mediated hydroxylation of DA may be a mechanism for generating this potentially cytotoxic trihydroxyphenyl. The results of this study demonstrate for the first time that semiquinone and quinone intermediates of eumelanin are the initial products derived from the ·OH-mediated oxidations of dopa, DA, TOPA, and 6-OHDA. These observations suggest that if ·OH is generated beyond the capabilities of cytoprotective mechanisms, the radical can rapidly oxidize catechol precursors, augment melanogenesis, and generate additional cytotoxic quinoid intermediates of eumelanin.