Glide angle in the genus Petaurus and a review of gliding in mammals

The gliding angle of the Mahogany Glider Petaurus gracilis and the Sugar Glider Petaurus breviceps was determined from field studies by measuring the height of launch and landing of glides and the distance travelled. This showed no significant difference between these two species in glide ratio, which averaged 1.91 and 1.82 m distance per 1 m loss in altitude, respectively, nor in glide angle which averaged 28.26° and 29.69° for the Mahogany Glider and Sugar Glider, respectively. Significant differences were found between them for height of launch (19.75 and 11.96 m, respectively), height of landing (4.48 and 1.95 m, respectively), diameter at breast height of landing tree (44.12 and 23.22 cm, respectively), and glide distance (29.71 and 20.42 m, respectively). An examination of the ratio of interorbital width to maximum skull width of gliding and nongliding possums was measured from museum skulls to examine whether gliders have eyes wider apart, to allow triangulation of distance in preparation for gliding. Gliding possums showed a trend toward having a larger interorbital width than nongliding possums, although there appear to be several factors acting on the interorbital width. Museum study skins of all gliding marsupials were measured to determine the relationship between patagium surface area and body mass which showed a clear relationship (r² = 0.9688). A comparison of gliding behaviour, patagium, development of limbs, tail morphology and mass was also made between gliding marsupials and other gliding mammals.     

Lack of correlation between overall protein synthesis and the onset of cell elongation in germinating embryos of Haplopappus gracilis

10⁻⁵M abscisic acid (ABA) completely inhibits germination or (if seeds deprived of integuments are used) embryo elongation in Haplopappus gracilis (Nutt.) Gray. Nevertheless, considerable rates of protein and RNA synthesis were found in embryos grown in abscisic acid, at least during the early hours after sowing. On the contrary, seeds grown in cycloheximide + fusicoccin (a powerful promoter of cell expansion), where protein synthesis is almost completely inhibited, show full protrusion of radicle, thus simulating a "germination" process. These results suggest that some of the most important events involved in seed germination, i.e. protein and RNA synthesis, and cell elongation which leads to radicle protrusion, may not necessarily be linked together and are possibly regulated by different control mechanisms. Moreover, when seeds or embryos are grown in abscisic acid + fusicoccin, protein synthesis is considerable, cell elongation is greater than in water controls at least for 12 h, and germination in its early stages appears to be normal; but DNA synthesis and cell division are not resumed, possibly since some other factor is required. All these findings propose a reevaluation of criteria for defining successful germination.     

Influence of waste water from the paper industry and UV-B radiation on the photosynthetic efficiency of Euglena gracilis

The green flagellate Euglena gracilis has been used as a model organism to elucidate the possible large-scale and short-term effects of waste substances from the pulp and paper industry on photosynthetic efficiency (PE). Different concentrations of waste substances before and after treatment in a cleaning system were studied. The uncleaned sample at concentrations up to 1:10 and the cleaned sample at concentrations up to 1:5 showed stimulating effects on the PE after 7 days of incubation compared to the control. The effects of waste substances on the PE of E. gracilis were also studied in combination with short-term studies (20 and 40 min) of ultraviolet-B radiation (UV-B, 280–320 nm). It was shown that increasing concentrations of the uncleaned sample had continuously stimulating effects on the PE and worked protectively against UV-B radiation. The cleaned sample exhibited no effects, or negative effects, on the PE of E. gracilis together with UV-B radiation compared to the experiments with only UV-B radiation. At the concentration 1:1 of the cleaned sample an increase in the PE was detected due to the high concentration of the coloured substances and a decrease in the UV-B penetration. PE revealed itself to be highly sensitive for detecting toxic effects on E. gracilis and is thus very promising for use in regular toxicity tests of waste water from pulp and paper industry. This revised version was published online in July 2006 with corrections to the Cover Date.     

Production of a thermal stress resistant mutant Euglena gracilis strain using Fe-ion beam irradiation

Euglena gracilis is a common phytoplankton species, which also has motile flagellate characteristics. Recent research and development has enabled the industrial use of E. gracilis and selective breeding of this species is expected to further expand its application. However, the production of E. gracilis nuclear mutants is difficult because of the robustness of its genome. To establish an efficient mutation induction procedure for E. gracilis, we employed Fe-ion beam irradiation in the RIKEN RI beam factory. A decrease in the survival rate was observed with the increase in irradiation dose, and the upper limit used for E. gracilis selective breeding was around 50 Gy. For a practical trial of Fe-ion irradiation, we conducted a screening to isolate high-temperature-tolerant mutants. The screening yielded mutants that proliferated faster than the wild-type strain at 32?°C. Our results demonstrate the effectiveness of heavy-ion irradiation on E. gracilis selective breeding.