Substrate-controlled succession of marine bacterioplankton populations induced by a phytoplankton bloom

Phytoplankton blooms characterize temperate ocean margin zones in spring. We investigated the bacterioplankton response to a diatom bloom in the North Sea and observed a dynamic succession of populations at genus-level resolution. Taxonomically distinct expressions of carbohydrate-active enzymes (transporters; in particular, TonB-dependent transporters) and phosphate acquisition strategies were found, indicating that distinct populations of Bacteroidetes, Gammaproteobacteria, and Alphaproteobacteria are specialized for successive decomposition of algal-derived organic matter. Our results suggest that algal substrate availability provided a series of ecological niches in which specialized populations could bloom. This reveals how planktonic species, despite their seemingly homogeneous habitat, can evade extinction by direct competition.     

Das Vorkommen von Mischzellen bei einer Gaterslebener Herkunft des Statusalbomaculatus vonAntirrhinum majus L.

Summary 1. A non-Mendelian variegation (statusalbomaculatus) spontaneously arose within the control strain 50 ofAntirrhinum majus L. Mixed cells containing two distinct kinds of plastids (green and pale) have been found in variegated leaves, according to Baur's theory of somatic segregation and sorting-out of plastids.2. Pale plastids clearly differ from normal green ones. They have only half the diameter of green plastids, and are not able to form typical grana of regular arrangement which can be seen under the light microscope as well as under the fluorescence microscope. From secondary changes within the pale plastids result macrograna (Fig. 3–5, 10); the degeneration process ends in vacuolisation (Fig. 8, 11) and in decay of the plastids.3. Mixed cells were found in cotyledons, foliage leaves (Fig. 3–8, 11), bracts (Fig. 2, 9, 10) and sepals.4. In younger foliage leaves mixed cells are present in all those leaf areas, where they are to be expected according to the theory of somatic plastid segregation. In mixed cells the green and pale plastids were found in any possible ratio. The frequency of these different ratios is nearly binomially distributed (Fig. 12).In old foliage leaves it is difficult to find mixed cells. The reason for this is, that pale plastids regularly degenerate and decay. Therefore the number of visible mixed cells is reduced with increasing age of the leaves. The same was observed in bracts and sepals; but here the difference between the younger and the old leaves is not so striking as in foliage leaves.5. Chlorophyll deficiencies inherited by the plastids (the plastome) exist; nevertheless mixed cells cannot be found in all those areas where one would expect them. The reasons for the failure, so far known, are compiled.

---

1. statusalbomaculatus 50Antirrhinum majus L. . , , ( ).2. . , , . . . (. 3–5 10); (. 8 11) .3. (Mischzellen) , (. 3–8 11), (. 2, 9 10) .4. , . . (. 12). . , . . , , .5. , , , . - .

     

Radiocarbon dating of a very large African baobab

In late 2004, Grootboom, probably the largest known African baobab (Adansonia digitata L.), collapsed unexpectedly in northeastern Namibia. Ten wood samples collected from different areas of the trunk were processed and investigated by accelerator mass spectrometry radiocarbon dating. The radiocarbon dates of three samples were greater than 1000 years BP (radiocarbon years before present, i.e., before AD 1950). The corresponding calibrated calendar age of the oldest sample was 1275 +/- 50 years, making Grootboom the oldest known angiosperm tree with reliable dating results. Variations in radiocarbon dates among the wood samples indicated that, morphologically, Grootboom was a quintuple tree, whereas genetically, it was a single individual. Ages of extreme lateral samples revealed that, over the past 500-600 years, Grootbooom had almost ceased growing, providing information about climate changes in central southern Africa. The sudden demise of Grootboom coincided with the spread of the poorly studied baobab disease, which has become epidemic in Namibia.     

Bose-Einstein condensation of cesium

Bose-Einstein condensation of cesium atoms is achieved by evaporative cooling using optical trapping techniques. The ability to tune the interactions between the ultracold atoms by an external magnetic field is crucial to obtain the condensate and offers intriguing features for potential applications. We explore various regimes of condensate self-interaction (attractive, repulsive, and null interaction strength) and demonstrate properties of imploding, exploding, and non-interacting quantum matter.     

Die Vermehrung der Pappeln durch Stecklinge

Ohne Zusammenfassung