Ion Uptake in Higher Plants and KCl Stimulation of Plasmalemma Adenosine Triphosphatase: Comparison of Models

Criteria for the acceptance or rejection of the dual, the cooperative, and the multiphasic model of ion uptake are given and are used to evaluate the models on the basis of previously published analyses. In addition, mathematical representations of the models are fitted to concentration-dependence data for various ions and plant tissues by a general curve fitting program. The calculated parameters are evaluated for biological relevance, and the fit is compared by statistical analysis. The kinetics of ion uptake in higher plants are found to be consistent with the concept of multiphasic uptake mechanisms, while the dual and the cooperative model must be rejected. KCl stimulation of plasmalemma-bound ATPases is also shown to obey multiphasic kinetics, thus strengthening the correlation between ion uptake and membrane-bound ATPases.     

Classification of the family Plectonemertidae (Nemertea): a phenetic comparison

A phenetic classification based on overall morphological similarity between the species in the family Plectonemertidae (genera Plectonemertes, Campbellonemertes, Potamonemertes, Leptonemertes, Katechonemertes, Argonemertes, Anliponemertes, and Acteonemertes ) was undertaken and the result compared with a cladistic and an evolutionary classification. Similarity between species was computed by Gower's general coefficient of similarity and various techniques were used to find patterns in the similarity matrix: single-linkage, average-linkage, and complete-linkage clustering, together with principal coordinate analysis. Although the explicit aim of phenetics is not to estimate the phylogeny, the classification based on overall similarity still portrays phylogeny better than an intuitive assessment of morphological similarity, as judged by the cladistic analysis. The classification does not support the previously proposed hypothesis that the two freshwater genera Campbellonemertes and Potamonemertes have descended from a terrestrial ancestor.     

Mobility is related to species traits in noctuid moths

1. Mobility is important for the understanding of how species survive in fragmented landscapes and cope with increasing rates of habitat and climate change. However, mobility is a difficult trait to explore and is poorly known in most taxa. Species traits have been studied in relation to range shifts, extinction risks, and responses to habitat area and isolation, and have also been suggested as good estimators of mobility. Here we explore the relation between mobility and species traits in noctuid moths. 2. We sampled noctuid moths by an automatic light‐trap on an island far out in the Baltic Sea. We compared traits of the non‐resident species on the island with traits of a species pool of assumed potential migrants from the Swedish mainland. 3. Mobility was significantly related to adult activity period, length of flight period, and the interaction between host‐plant specificity and distribution area. Widely distributed host‐plant generalists were more mobile than host‐plant specialists with more restricted distribution, and species with an adult activity period in August to September moved to the island to a higher extent than species with an adult activity period in May to July. Our results remained qualitatively robust in additional analyses, after controlling for phylogeny and including all species recorded on the island, except for the trait ‘length of flight period’. 4. Our results highlight the importance of the relation between mobility and species traits. Noctuid moths with certain traits move over longer distances than earlier known. This finding is important to include when predicting range dynamics in fragmented and changing landscapes, and when conservation measures of species are devised.     

Locomotion in terrestrial mammals: the influence of body mass, limb length and bone proportions on speed

Traditionally a few limb proportions or total limb lengths have been regarded as indicative of peak running velocity. This is due to physical principles (inferred in- and outvelocities around the joints, stride lengths) and also the observation that fast-moving animals tend to share a number of purported key features which are either absent or not developed to near the same extent in slower moving forms. Previous studies have shown hind limb length and metatarsus/femur ratio to be correlated significantly, albeit modestly with running speed. These studies have nearly all been bivariate analyses. Based on the physical principles, there is reason to suppose that more variables than just m/f ratio could be important as adaptations for fast locomotion, and also that bivariate analyses are too simple. In this study a sample of 76 running mammals was used, with running speeds taken from literature. A number of osteological parameters were discovered to covary significantly with peak running speed, albeit only modestly. Using the information from phylogeny reduced all correlations, often significantly so. Multivariate analyses resulted in markedly higher correlation coefficients. Animals probably do not optimize their anatomy for the purpose of running very fast, which occurs only on rare occasions, but for reducing costs of locomotion.  © 2002 The Linnean Society of London, Zoological Journal of the Linnean Society , 2002, 136 , 685–714.     

Quantacorrected Spectrometer for Recording Different Types of Photobiological, Photochemical, and Spectrophotometric Measurements

An instrument is described which functions as a spectrophotometer, In addition it measures action spectra of photobiological processes, excitation and emission spectra of fluorescence, and gives data for calculation of action spectra of partial reactions of photosynthesis and photocontrolled enzymatic reactions. The instrument has a Bausch and Lomb 250 mm grating monochromator. Equal numbers of quanta at different wavelengths are adjusted electronically with control of the slit through a quantacorrected photocell and a servo motor which is programmed by a cam connected to the wavelength drive.     

Chemosensory Responses in Tetrahymena: The Involvement of Peptides and other Signal Substances1

Starved Tetrahymena thermophila (or cells growing in Holz's defined medium) are attracted by a chemosensory response to complex peptide mixtures as proteose peptone, yeast extract, and extracts of blood platelets containing platelet-derived growth factor. Starved cells are also significantly attracted by mixtures of amino acids and of nucleosides of Holz's defined medium; however, no individual amino acid or nucleoside could be identified as the major chemo-attractant. The positive chemosensory response can be abolished by cycloheximide (CHX) but is insensitive to actinomycin D and puromycin, possibly indicating that de novo RNA and protein synthesis are not necessary for a change in chemosensory behavior. Three mutants resistant to CHX show normal response in the presence of the drug. The possible role of peptides as naturally occurring food signals of Tetrahymena is discussed.