Do anthocyanins play a role in UV protection of the red juvenile leaves of Syzygium?

The biological function of juvenile leaves pigmented with anthocyanin is poorly understood. The role anthocyanins play in UV protection was assessed in juvenile leaves of two Syzygium species (S. luehmannii and S. wilsonii) which contain high anthocyanin concentrations. HPLC was used to separate UV-absorbing anthocyanins from other soluble UV-absorbing phenolic compounds. The isolated anthocyanins (predominantly malvidin-3,5-diglucoside) contributed little to the total absorbance of UV-A and UV-B radiation. This was because the non-acylated anthocyanins only effectively absorbed shortwave UV-B radiation and the strong absorbance by other compounds. These results suggest that the UV protection hypothesis is not valid for anthocyanins in juvenile Syzygium leaves

Contrasting leaf development within the genus Syzygium

Leaf developmental patterns were characterized in four rainforest tree species of Syzygium. Leaf optical properties, pigment changes, expansion characteristics, stomatal development, and photosynthetic rates were studied. In both S. luehmannii and S. wilsonii photosynthetic development was delayed until after full leaf expansion. Rates of O evolution were negative during expansion of S. luehmannii and S. wilsonii leaves and stomatal conductance was 10-20 mmol m s lower than for corresponding leaves of S. moorei. Stomatal conductance data and scanning electron microscopy showed that the development of functional stomata was delayed until after full leaf expansion in S. luehmannii and S. wilsonii, however, low stomatal conductance was not responsible for the lack of photosynthetic potential during leaf expansion in these species. Leaves of S. luehmannii and S. wilsonii required less than 10 d for full leaf expansion and contained anthocyanin during expansion. In contrast, leaves of S. moorei and S. corynanthum expanded slowly (20-40 d required for full leaf expansion), exhibited positive rates of O evolution and did not accumulate anthocyanin. In S. luehmannii and S. wilsonii anthocyanin was located in the vacuole of distinct cell layers just below the upper epidermis and the possible functions of anthocyanin accumulation are discussed. This is the first report where such variation in leaf development has been characterized in the one genus

The management of managers: A review and conceptual framework

The management of managers is an important contemporary concern, but the literature on the issue is not well integrated. This paper reviews key sources on the topic across organizational economics, human resource development and strategic human resource management. It presents a novel interdisciplinary framework for analysing how firms manage senior managers and for guiding future research, arguing that firms adopt different styles to attract–defend, develop–renew and motivate–harvest their senior managerial resource, depending on their contexts and choices that are made in the firm over time. The notion that some styles draw on early identification of élites while others treat management identification as more of an emergent problem is central to the typology. Within each of the styles identified, effectiveness in the management of managers hinges on recognizing and handling certain strategic tensions and problems