Dr. Dagmar Malun

 Freie Universität Berlin 
 Institut für Biologie
 - Neurobiologie -
 Königin-Luise-Str. 28-30
 14195 Berlin / Germany

 phone:  ++49 30/838-56285
 e-mail: malun@zedat.fu-berlin.de
 personal homepage:

We are investigating mechanisms that underlie the formation of components of the insect nervous system during ontogeny. We also are trying to understand the functional relevance of certain neuropil structures in the adult animal. Research in the lab presently focuses on the mushroom bodies of the honeybee (Apis mellifera), prominent neuropil structures in the dorsal protocerebrum which are thought to represent centers of higher neuronal integration and are suggested to play a major role in learning and memory.

Two prominent populations of neurons contribute to the mushroom bodies: (1) intrinsic neurons, called Kenyon cells (170,000 per brain hemisphere) and (2) a group of extrinsic neurons (antennal lobe projection neurons) which receive olfactory input in the antennal (olfactory) lobes and project into the calyces of the mushroom bodies where they form synapses with Kenyon cells.

As a first step towards our goals we are investigating the temporal patterns of the mitotic activity of Kenyon precursor cells (Malun, 1998). Simultaneously, we are analyzing programmed cell death of Kenyon precursor cells during honey bee metamorphosis (Ganeshina, Schäfer, Malun, 2000). We found that obviously both processes, the end of mitotic activity as well as programmed cell death of Kenyon precursor cells, occur at mid pupal stage and determine the final number of Kenyon cells in the adult bee. We are also studying the formation of antennal lobes and mushroom bodies during metamorphosis by labeling olfactory projection neurons during consecutive developmental stages (Schröter, Malun, 2000).

In a second approach we are studying the effects of experimental ablation of Kenyon cell precursors on mushroom body development (by applying the mitotic blocker hydroxyurea to first instar larvae), and ultimately, on the behavior of the adult animal. Using this approach, we are able to generate adult honey bees with partial mushroom body ablations (see figure below). In discriminative conditioning experiments using the proboscis extension reflex paradigm we then examine the role of mushroom bodies in olfactory learning and (in cooperation with the group of Prof. J. Erber from the Technical University Berlin) in tactile antennal learning (Scheiner, Weiss, Malun Erber, 2001).

3-D-reconstructions of the honey bee brain in a control animal (left panel) and in a hydroxyurea-treated animal with partial mushroom body ablation (right panel). The mushroom bodies are indicated by red colour.

 

Applied methods:

 

In order to label neuron classes we use various histological and immunohistochemical techniques: Cell proliferation pattern of Kenyon cell neuroblasts are studied by BrdU incorporation and immunohistochemistry. Individual neurons are labeled intracellularly with fluorescent dyes. Subsequent morphological analysis is performed by laser scanning confocal microscopy and electron microscopy.

Publications:

(1) Malun D., Waldow U., Kraus D., Boeckh J. (1993) Connections between the deutocerebrum and the protocerebrum, and neuroanatomy of several classes of deutocerebral projection neurons in the brain of male Periplaneta americana. J. Comp. Neurol. 329: 143-162.

(2) Malun D., Oland L.A., Tolbert L.P. (1994) Uniglomerular projection neurons participate in early development of olfactory glomeruli in the moth Manduca sexta. J. Comp. Neurol. 350: 1-22.

(3) Malun D., Brunjes P.C. (1996) Development of olfactory glomeruli: Temporal and spatial interactions between olfactory receptor axons and mitral cells in opossums and rats. J. Comp. Neurol. 368:1-16.

 

(4) Cummings D.M, Malun D., Brunjes P.C. (1997) Development of the anterior commissure in the opossum: Midline extracellular space and glia coincide with early axon decussation. J. Neurobiol. 32:403-414.

 

(5) Malun D. (1998) Early development of mushroom bodies in the brain of the honeybee Apis mellifera as revealed by BrdU incorporation and ablation experiments. Learning & Memory 5:90-101.

 

(6) Ganeshina O., Schäfer S., Malun D. (2000) Proliferation and programmed cell death of neuronal precursors in the mushroom bodies of the honeybee. J. Comp. Neurol. 417:349-365.

 

(7) Schöter U., Malun D. (2000) Formation of antennal lobe and mushroom body neuropils during metamorphosis in the honeybee, Apis mellifera. J. Comp. Neurol. 422:229-245.

 

(8) Scheiner R., Weiss A., Malun D., Erber J. (2001) Learning in honey bees with brain lesions: How partial mushroom-body ablations affect sucrose responsiveness and tactile antennal learning. Animal Cognition (in press).

Reviews:

(1) Boeckh J., Distler P., Ernst K.-D., Hösl M., Malun D. (1990) Olfactory bulb and antennal lobe. In: Schild D. (ed) Chemosensory information processing. NATO ASI Series H39, Cell Biology. Springer, Berlin Heidelberg New York, pp 201-228.

(2) Salecker I., Malun D. Development of olfactory glomeruli. In: Hansson B.S. (ed) Insect olfaction. Springer, Berlin, Heidelberg, New York p 207-242.

Abstracts:

(1) Malun D., Oland L.A., Tolbert L.P. (1993) Do uniglomerular output neurons participate in forming the template for olfactory glomeruli in the moth? Soc. Neurosci. Abstr. 19:443.

(2) Malun D., Oland L.A., Tolbert L.P. (1994) Uniglomerular output neurons participate in early development of olfactory glomeruli in the moth Manduca sexta. In: Elsner N, Breer H (eds) Sensory transduction. Proceedings of the 22nd Göttingen Neurobiology Conference. Thieme: Stuttgart, New York.

(3) Malun D., Brunjes P.C. (1994) Differentiation of mitral cell dendrites in the olfactory bulb of the opossum Monodelphis domestica and the rat. Soc. Neurosci. Abstr. 20:240.

(4) Malun D., Brunjes P.C. (1995) Differentiation of mitral cell dendrites during glomerulus formation in the olfactory bulb of the opossum Monodelphis domestica and the rat. In: Elsner N, Menzel R (eds) Learning and memory. Proceedings of the 23rd Göttingen Neurobiology Conference. Thieme: Stuttgart, New York.

(5) Malun D. (1997) Postembryonic neurogenesis and development of the mushroom bodies in the honeybee. Proceedings of the 25th Neurobiolgy Conference Goettingen, Thieme: Stuttgart, New York

(6) Schröter U., Malun D. (1998) Morphogenesis of antennal lobe projection neurons in the honeybee. In N. Elsner and R. Wehner (eds). Proceedings of the 26th Göttingen Neurobiology Conference. Thieme: Stuttgart, New York.

(7) Ganeshina O., Malun D., Schäfer S. (1998) Development of mushroom bodies in the honeybee - proliferation and programmed cell death. European Journal of Neuroscience 10:9.

(8) Malun D., Gerber B. (1998) Mushroom body development and function in the honey bee. Proceedings of the13th Congress of the European Chemoreception Research Organization.

(9) Malun D., Ganeshina O., Schäfer S., Menzel R. (1998) Development of mushroom bodies in the honey bee and its experimental manipulation. Soc. Neurosci. Abstr. 703.

(10) Schröter U., Malun D. (1999) Compartmentation of neuropils in the olfactory pathway during pupation in honeybees. In: From Molecular Neurobiology to Clinical Neuroscience. Elsner N. and Eysel U. (eds), Proceedings of the 1st Göttingen Conference of the German Neuroscience Society 1999; 27th Göttingen Neurobiology Conference. Thieme: Stuttgart, New York.

(11) Malun D., Moseleit A. (1999) Hydroxyurea-induced morphological changes in the olfactory pathway of the honey bee Apis mellifera. In: From Molecular Neurobiology to Clinical Neuroscience. N. Elsner and U. Eysel (eds), Proceedings of the 1st Göttingen Conference of the German Neuroscience Society 1999; 27th Göttingen Neurobiology Conference. Thieme: Stuttgart, New York.

(12) Schröter U., Malun D. (1999) Differentiation of the olfactory pathway during metamorphosis of the honey bee Apis mellifera. Berlin Neuroscience Forum 1999.

(13) Malun D., Moseleit A. (1999) Chemical ablation of mushroom bodies causes structural changes in the olfactory pathway of the honey bee Apis mellifera. Berlin Neuroscience Forum 1999.

(14) Malun D., Wegerhoff R. (1999) Features in the development of the olfactory systems of vertebrates and invertebrates. In: Elsner N, Eysel U, editors. From Molecular Neurobiology to Clinical Neuroscience. Proceedings of the 1th Göttingen Conference of the German Neuroscience Society 1999; Volume I 27th Göttingen Neurobiology Conference. Thieme: Stuttgart, New York. p 240-246.

(15) Brandt R, Malun D., Steege A., Zöckler M, Menzel R. (1999) Three-dimensional reconstruction of honey bee mushroom bodies: Comparison between normal and hydroxyurea-treated bees. Soc. Neurosci. Abstr. 25. p.861.

(16) Scheiner R., Weiss A., Malun D., Erber J. (2000) Chemical mushroom body ablation, sucrose perception and positional antennal learning in the honey bee. Proceedings of the Forum of European Neuroscience (FENS) 2000. Eur. J. Neurosci. 12, Suppl. 11, p.92.

(17) Plath N., Malun D., Müller U. (2000) Chemical mushroom body ablation in the honeybee: Effects on various olfactory learning tasks and on protein amounts. Proceedings of the Forum of European Neuroscience (FENS) 2000. Eur. J. Neurosci. 12, Suppl. 11, p.92.

(18) Conzelmann S., Malun D., Breer H., Strotmann J. (2000) Development of axonal projections in the mouse olfactory system. Proceedings of the14th Congress of the European Chemoreception Research Organization.

(19) Malun D., Plath N., Müller U., Scheiner R., Weiss A. Erber J. (2000) Partial mushroom body ablation in the honey bee: Effects on olfactory and tactile antennal learning. Soc. Neurosci. Abstr. 26/1. p.726.

(20) Komischke B., Giurfa M., Lachnit H., Malun D. (2001) Reversal learning and differential olfactory conditioning in honeybees. Proceedings of the 4th Meeting of the German Neuroscience Society; 28th Göttingen Neurobiology Conference. Thieme: Stuttgart, New York. (in press).

(21) Giurfa M., Nierle P., Becker M., Malun D. (2001) Mechanosensory classical conditioning in the honeybee. Proceedings of the 4th Meeting of the German Neuroscience Society; 28th Göttingen Neurobiology Conference. Thieme: Stuttgart, New York. (in press).

(22) Guerrieri F., Krause G., Komischke B., Gerber B., Malun D., Giurfa M. (2001) Blocking and odour similarity in olfactory conditioning of honeybees. Proceedings of the 4th Meeting of the German Neuroscience Society; 28th Göttingen Neurobiology Conference. Thieme: Stuttgart, New York. (in press).