Honeybees establish specific sites on the comb for their waggle dances

Successful honeybee foragers perform dances on the surface of the comb where they interact with nectar receivers and dance followers. We have recorded the sites at which dances take place in large ten-frame hives and in two-frame observation hives. We find that dancing bees are most commonly found on particular combs in large hives and in particular areas on the combs in the observation hives. Although the site where dances take place may change from day to day, dancers will keep to the same site during the foraging period in any one day. Furthermore, if an established dance site is artificially relocated in the hive during the day, dancers seek these sites out before commencing their dances. We conclude that the dance sites are labelled in some way and so promote the congregation of both dancers and dance followers at the same site. Accepted: 27 November 1996     

Identification of a Rapidly Labelled 350K Histidine-Rich Protein in Neonatal Mouse Epidermis

Abstract. The major histidine-rich protein (HRP) found in the stratum corneum of neonatal mouse epidermis (band 2 protein, molecular weight 27,000) is a relatively late product of epidermal differentiation and incorporates labelled amino acids in vivo only after a 6–9 h lag period. A number of putative precursor HRPs in the 70–300 K molecular weight range were initially identified using short pulse labelling times and our previously described methods for isolation of epidermis and extraction of proteins. However, when steps were taken to minimise proteolysis during preparation, a single species of approximately 350 K molecular weight was the most strongly labelled protein following a 1 h in vivo pulse of [³H]-histidine. This protein was stable in sodium dodecyl sulphate dithiothreitol at 100°C and in 4 M urea, suggesting a single covalently linked polypeptide. The kinetics of labelling and the localisation of the 350 K HRP in the lower granular layers suggest that it is a precursor of the stratum corneum HRP. The processing of the 350 K HRP to the stratum corneum species appears to involve a complex series of specific cleavage steps which give rise to a number of HRPs of intermediate molecular weight.     

Veränderungen des Gibberellingehaltes von Salatsamen nach Belichtung

Zusammenfassung Samen der obligat lichtkeimenden Salatsorte Tenax wurden auf ihren Gibberellingehalt untersucht. Sie enthalten bei Quellung im Dunkeln nur wenig gibberellinähnliche Substanzen. Nach Belichtung mit hellrotem Licht nimmt der Gibberellingehalt innerhalb 1 Std sehr stark zu. Es wird gefolgert, daß Lichtkeimer einen zu niedrigen Gibberellingehalt besitzen, um im Dunkeln keimen zu können, und daß unter dem Einfluß des Lichtes die zur Keimungsauslösung notwendige Gibberellinmenge entsteht.

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Changes in gibberellin-like substances of lettuce seeds after light exposure

Summary The contents of gibberellin-like substances in lettuce seeds were determined. In darkness the seeds contain only small amounts of gibberellin-like substances, but upon illumination with near red light there is a sharp increase in the gibberellin content within one hour. It is concluded that lettuce seeds in darkness do not contain the amounts of gibberellin necessary for germination and that under the influence of light these amounts are provided.

     

Downscaling screening cultures in a multifunctional bioreactor array-on-a-chip for speeding up optimization of yeast-based lactic acid bioproduction

A key challenge for bioprocess engineering is the identification of the optimum process conditions for the production of biochemical and biopharmaceutical compounds using prokaryotic as well as eukaryotic cell factories. Shake flasks and bench-scale bioreactor systems are still the golden standard in the early stage of bioprocess development, though they are known to be expensive, time-consuming, and labor-intensive as well as lacking the throughput for efficient production optimizations. To bridge the technological gap between bioprocess optimization and upscaling, we have developed a microfluidic bioreactor array to reduce time and costs, and to increase throughput compared with traditional lab-scale culture strategies. We present a multifunctional microfluidic device containing 12 individual bioreactors (V_t = 15 µl) in a 26 mm × 76 mm area with in-line biosensing of dissolved oxygen and biomass concentration. Following initial device characterization, the bioreactor lab-on-a-chip was used in a proof-of-principle study to identify the most productive cell line for lactic acid production out of two engineered yeast strains, evaluating whether it could reduce the time needed for collecting meaningful data compared with shake flasks cultures. Results of the study showed significant difference in the strains' productivity within 3 hr of operation exhibiting a 4- to 6-fold higher lactic acid production, thus pointing at the potential of microfluidic technology as effective screening tool for fast and parallelizable industrial bioprocess development.     

Number-Based Visual Generalisation in the Honeybee

Although the numerical abilities of many vertebrate species have been investigated in the scientific literature, there are few convincing accounts of invertebrate numerical competence. Honeybees, Apis mellifera, by virtue of their other impressive cognitive feats, are a prime candidate for investigations of this nature. We therefore used the well-established delayed match-to-sample paradigm, to test the limits of honeybees'' ability to match two visual patterns solely on the basis of the shared number of elements in the two patterns. Using a y-maze, we found that bees can not only differentiate between patterns containing two and three elements, but can also use this prior knowledge to differentiate three from four, without any additional training. However, bees trained on the two versus three task could not distinguish between higher numbers, such as four versus five, four versus six, or five versus six. Control experiments confirmed that the bees were not using cues such as the colour of the exact configuration of the visual elements, the combined area or edge length of the elements, or illusory contours formed by the elements. To our knowledge, this is the first report of number-based visual generalisation by an invertebrate.