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The structures of the three Myb-related genes Hv1, Hv5 and Hv33 from barley were determined. They contain a single intron located in the second repeat unit of the Myb-related domain. By analogy to the animal MYB oncoproteins this conserved region of the gene product was shown by filter-binding experiments to exhibit nucleic acid-binding activity. Tobacco plants transgenic for chimeric Myb promoter/Gus genes express the enzyme in a developmentally controlled and tissue-specific manner. During germination and early stages of plant growth, GUS activity is seen in the root cap and adjacent meristematic tissue. At later stages of plant development, GUS activity is predominantly observed in the shoot apical meristem, the roots and the nodal regions of the stem. Within the stem at stages of secondary growth, Myb promoters are active in defined cell types. In the internode low GUS activity is displayed by the innermost cell layer of the cortex, the starch sheath, that surrounds the vascular cylinder of secondary xylem and phloem tissue, as well as in pith rays originating from vascular cambium initials. In the nodal region Myb promoter-controlled Gus expression is mainly confined to the abaxial starch sheath of the leaf trace, to the branch traces and to internal strands of primary phloem. It is suggested that in addition to their activity in meristematically active plant tissues Myb genes are expressed in conductive tissues that are closely associated with vascular bundles.

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Bumblebees (Bombus spp.) are social bees that must complete their colony cycle within a single season. Those in the arctic face a much shorter flowering season than more southerly species. Here we compare behavioral and physiological features between bumblebee queens founding colonies in Denali National Park, Alaska, and queens of species from New York and Vermont. Several features that allow the more northerly bees to gain a quick start in colony founding were identified. First, the Alaskan bees emerged almost immediately (within 1 or 2 days) after the first willow blossoms began to open (while the ground was still snow covered except for a few bare patches). Within 2 days after emerging from hibernation, the first queens were already nest hunting and (or) carrying pollen, and ovary masses were increasing markedly. In contrast, the temperate-zone queens showed no synchronous emergence in early spring, and although they achieved a ratio of ovary to body mass similar to that of the Alaskan queens, it took them longer to do so, and to initiate colony founding.

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