Observations on dividing plastids in the protonema of the moss Funaria hygrometrica Sibth.

The process of division was investigated in the different types of plastids found in the tip cell of the protonema of Funaria hygrometrica Sibth. There were no structural changes in the envelope membranes of any of the plastid types during the initial stage of division. As the process of constriction advanced, thylakoids were locally disintegrated and sometimes starch grains in the isthmus were locally dissolved. In the isthmus, tightly constricted plastids were characterized by an undulating envelope and an increasing number of vesicles. After three-dimensional reconstruction of electronmicrographs a distinct filamentous structure was observed in the plane of division outside the plastid but close to the envelope. At different stages of division the constricted regions were partly surrounded by one or a few filaments. The roundish plastids in the apical zone were accompanied by single microtubule bundles, and the spindle-shaped plastids in the cell base were surrounded by single microtubules and microtubule bundles. A model of co-operation between microtubules and the filamentous structure in the division process is discussed.A preliminary report was presented at the Tagung der Deutschen Botanischen Gesellschaft und der Vereinigung für Angewandte Botanik, Hamburg, September 1986     

Characterisation of a temperature-sensitive gametophore over-producing mutant of the moss, Physcomitrella patens

Summary A mutant of the moss, Physcomitrella patens, was isolated which was temperature-sensitive for the production of gametophores. At 17° C this mutant, designated ove 409, produced normal leafy shoots. At 24° C ove 409 produced many abnormal buds characteristic of bud-over-producing (ove) mutants. ove 409 produced an intermediate phenotype at 21° C. The cytokinin levels in the culture medium of this mutant, the wild-type and a cytokinin overproducing mutant, oveA78, were measured by combined gas chromatography mass spectrometry at the permissive and nonpermissive temperatures. Production of cytokinin was found to be affected by temperature in all strains; the change in phenotype of ove 409 correlated with the production of N⁶-(²-isopentenyl) adenine. Complementation analysis was performed using this mutant by protoplast fusion. ove 409 was found to be in the same complementation group as a previously isolated ove mutant, oveA78.     

Moss phosphofructokinase is less sensitive than other plant phosphofructokinases to inhibition by phosphoenolpyruvate

Phosphofructokinase was partially purified from the moss Brachythecium rutabulum (Hedw.) Bt. Eur. and found not to be inhibited by 400 μ M phosphoenolpyruvate, whereas spinach and Chlorella phosphofructokinases were inhibited over 80% by phosphoenolpyruvate at one-fifth of this, concentration. Mixing experiments indicated that the insensitivity of the moss phosphofructokinase was not an artifact of the extraction procedure. Other kinetic and regulatory properties of moss phosphofructokinase were similar to those reported for the enzyme from other plants.     

Promotion of Pylaisiella selwynii growth and gametophore formation by octopine and cytokinin

Growth, branching and gametophore formation by protonema developing from spores of the moss Pylaisiella selwynii were promoted by octopine, an unusual amino acid found in crown gall tumors. Cytokinin (0.01 μ M ) in combination with octopine (0.1 μ M to 1 m M ) increased the number of gametophores formed and decreased the time required for their development. The combined effect of these two compounds was similar to that obtained with virulent agrobacteria. At higher cytokinin concentrations, protonemal buds formed abnormal masses of cells rather than normal gametophores. Common amino acids and auxins, alone or in combination with cytokinin, had relatively little effect on the development of the moss.     

Temporal analysis of clonal structure in a moss bdelloid population

Clonal structure of a population of Macrotrachela quadricornifera (Rotifera, Bdelloidea) from a terrestrial moss in Northern Italy, was investigated over a 16 month period. Every month, 40–60 specimens of M. quadricornifera were collected from about 0.1 m² of moss. The individual animals were homogenized and their isozyme phenotypes analyzed by electrophoresis on vertical polyacrylamide gel. One enzyme, phosphoglucose isomerase (PGI), was used as a marker to distinguish the different clones present in the sample. A few clones were established from the rotifers sampled and patterns of esterases and , and malic enzyme were studied. Nine electrophoretic patterns for PGI were seen. One was dominant, a second was almost always present, but in lesser amounts. The remainder were present occasionally.There seemed to be no seasonal replacement of the clones and the composition of the population appeared to be unaffected by variations in temperature. Relative humidity seemed to be the more important factor in regulating the number of electromorphs of the rotifer population.     

The moss,Physcomitrella patens,transformed with apoaequorin cDNA responds to cold shock,mechanical perturbation and pH with transient increases in cytoplasmic calcium

The gene for apoaequorin has been used previously to indicate cytosolic calcium changes in higher plants. Here we report the transformation of the mossPhyscomitrella patens with the cDNA for apoaequorin. Stable transformants were obtained in the wild type which reconstitute the calcium-sensitive luminescent protein aequorinin vivo after incubation in coelenterazine, and continue to grow normally. The wild type responds to cold-shock (0–10°C) with increases in cytosolic calcium. Mechanical perturbation, in the form of touch, also induces transient increases in cytosolic calcium. A smaller response to pH, distinct from the touch response and exhibiting different kinetics, can also be detected.     

Coumarin and Euponin,Two Inhibitors for Insect Development from Leaves of Eupatorium japonicum

An ovicide and a larval growth inhibitor against Drosophila melanogaster were isolated from leaves of Eupatorium japonicum. The ovicide was identified as coumarin. The structure of the larval growth inhibitor, a new naturally occurring guaianolide named euponin, was elucidated on the basis of spectral and chemical evidence. The inhibitory effects of these agents on the egg and larva were also described.     

Nitrogen Inputs by Marine Vertebrates Drive Abundance and Richness in Antarctic Terrestrial Ecosystems

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Ubiquitous genetic diversity in ISSR markers between and within populations of the asexually producing moss <Emphasis Type="Italic">Pleurochaete squarrosa</Emphasis>

This paper provides an analysis of genetic variability in local populations of the clonal moss Pleurochaete squarrosa, a Mediterranean moss typical of post-fire recovery, and characterised by asexual reproduction. ISSR (Internal Simple Sequence Repeats) primers and trnL_UAA (intron of plastid gene for Leu tRNA) length polymorphism were employed to evaluate genetic structure in five southern Italy populations of this moss. Both molecular tools highlight high values of genetic diversity with geographic structure of sampled populations and a low gene flow among the investigated sites. Gene diversity is significant at every hierarchical level of sampling, and generally increases from lower to higher hierarchical levels. Among other factors, the ubiquitous genetic variability detected in P. squarrosa can be related to continuous, occasionally massive, short-range recruitment of propagules, and to the high degree of intermingling, both favoured by the modality of vegetative reproduction and growth occurring in the species.