Resistance of fully imbibed tomato seeds to very high salinities

Abstract Seeds of Lyeopersicon esculentum cv. VF36 (a salt-sensitive cultivar), L. esculentum var. Edkawi (which is fairly salt-resistant), and a wild relative, L. cheesmanii, were exposed to various concentrations of NaCl, up to 460 mol m^?3, either directly or following imbibition in non-saline nutrient solution. After 10 d exposure to salt, they were transferred to non-saline solution. All taxa showed some germination at the lowest salinity tested, 92 mol m^?3 NaCl, but virtually no germination occurred at 184 mol m^?3 NaCl or higher salinities. Within 2 d after removal of the salt stress, however, the seeds of L. esculentum reached control levels of germination, even if they had already been on the verge of germination when the stress was imposed. The seeds of L. cheesmanii were less resistant to NaCl. The physiological basis for the resistance of VF36 seeds is discussed.     

The Uptake of 63Ni by the Diatom Phaeodactylum tricornutum

Kinetic studies of the uptake of ⁶³Ni by cultures of the diatom Phaeodactylum tricornutum Bohlin revealed that the uptake capacity of the cells depended strongly on their metabolic state. Phosphate-starved cells gave saturation-type uptake curves and had low nickel-binding capacity. This was increased markedly by the addition of phosphate to the cultures. When nickel ions were added before or together with the phosphate, the increase in nickel-binding capacity of phosphate-starved cells failed to appear more or less completely. Uptake of phosphate and formation of polyphosphate by the cells were not affected by the addition of nickel to the growth medium. The phosphate dependent synthesis of the principle involved in nickel binding was induced 15–20 h after the addition of phosphate to starved cells. Whether phosphate was directly or indirectly involved in this process could not be established.     

Mutual Exclusion of ATP,ADP and g-Strophanthin Binding to NaK-ATPase

THE (Na⁺+K⁺)-activated ATPase found in cell membrane fragments is for many reasons thought to be part of the active sodium pump system of cells. One of the arguments is that cardiac glycosides specifically inhibit the ATPase as well as the sodium pump^1–3. It has been proposed that the inhibition is due to an interaction between the glycosides and some phosphorylated form of the ATPase system^4–6.     

Historical legacies in the geographical diversity patterns of New World palm (Arecaceae) subfamilies

The extent to which species richness patterns of the major palm subfamilies in the Americas are controlled by lineage history was studied. Based on the fossil record, we suggest that the subfamily Coryphoideae has followed a boreotropical dispersal route into Central and South America, whereas Calamoideae (tribe Lepidocaryeae), Ceroxyloideae and Arecoideae have Gondwana/South America-biased histories. However, Arecoideae has been present and diverse in both South and Central America at least since the early Tertiary. We used regression analyses to evaluate the relative importance of environmental factors and spatial variables (as substitutes for historical or other non-environmental factors) as determinants of geographical variation in species richness for each subfamily. Given the different lineage histories, we hypothesized that: (1) coryphoid richness should be least strongly controlled by the modern environment and exhibit a strong non-environmental bias towards Central and North America, reflecting its boreotropical invasion route, (2) calamoid species richness should exhibit a non-environmental bias towards South America, reflecting its long African–South American history, and (3) arecoid species richness should be most strongly environmentally determined, reflecting the long arecoid residency in both Central and South America. The regression analyses confirmed the hypothesized effects of lineage history on the geographical patterns in species richness. Hence, modern species richness patterns in the New World palm subfamilies strongly reflect their divergent biogeographical histories.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 113–125.     

Low night temperature and inhibition of gibberellin biosynthesis override phytochrome action and induce bud set and cold acclimation, but not dormancy in PHYA overexpressors and wild-type of hybrid aspen

Juvenile trees of temperate and boreal regions cease growth and set buds in autumn in response to short day-lengths (SD) detected by phytochrome. Growth cessation and bud set are prerequisites for the development of winter dormancy and full cold hardiness. In this study we show that the SD-requirement for bud set and cold hardening can be overcome in hybrid aspen (Populus tremula L. × tremuloides Michx.) by low night temperature and inhibition of gibberellin (GA) biosynthesis. Bud set and increased cold hardiness were observed under normally non-inductive long day-length (LD) in wild-type plants, when exposed to low night temperature and paclobutrazol. In addition, the effect of PHYA overexpression could be overcome in transgenic plants, producing bud set and cold acclimation by treatment with: SD, low night temperature and paclobutrazol. After cold acclimation, the degree of bud dormancy was lower for wild-type plants prior treated with LD and transgenic plants (overexpressing PHYA), than SD-treated, wild-type plants. Thus, low night temperature in combination with reduced GA content induced bud set and promoted cold hardiness under normally non-inductive photoperiods in hybrid aspen, but was unable to affect development of dormancy. This might suggest separate signalling pathways from phytochrome regulating the induction of cold/cold hardiness and bud dormancy in hybrid aspen or alternatively, there might be one pathway that fails to complete its action in the transgenic and paclobutrazol treated plants.     

A revision of the Siphonocryptidae (Diplopoda, Polyzoniida)

Siphonocryptus compactus Pocock, 1894 (Sumatra), is redescribed from type and fresh material. Siphonocryptus latior sp. n. (Malaya) is described. Hirudicryptus gen. n. (monotypic) is erected, type-species Siphonocryptus canariensis Loksa, 1967 (Canary Islands, Madeira). Arguments for monophyly of Siphonocryptidae (= Siphonocryptus + Hirudicryptus ) and for a sister-group relationship between Siphonocryptidae and all other Polyzoniida arc presented. The strongly disjunct distribution area of the family is compared with other disjunct distributions involving the Canary Islands and Madeira.