Nutritional and Hormonal Requirements for the Growth of Vigna sinensis Callus in vitro

Nutritional and hormonal requirements for in vitro growth of callus tissue of Vigna sinensis Endl. were studied. Callus was formed on hypocotyl and root sections, when they were cultured on Linsmaier and Skoog's basal medium solidified with 10 g/1 agar and supplemented with only 0.5 mg/12,4-D or 2 mg/1 IAA. Further addition of 0.2 mg/1 kinetin and 1 g/l yeast extract resulted in more active callus formation. For unlimited vigorous growth of subcultured callus which was originally isolated from root sections, yeast extract was indispensable besides 2,4-D and kinetin. Such growth-promoting activity was observed also in malt extract and Ebios (dried cell powder of brewery yeast). Of known compounds tested, nicotinic acid, nicotinamide., methyl nicotinate and NAD were promotive to the growth of the callus, although much less effective than yeast extract. Other pyridine derivatives, vitamins and amino acids tested were ineffective or slightly effective. Sucrose was the most suitable carbon source. Fructose, glucose and maltose also supported the growth. Kinetin stimulated cell proliferation of the callus and cell differentiation to tracheary element.     

The composition and foraging behaviour of mixed-species flocks of forest-living birds in Madagascar

Mixed-species flocks of forest living birds were investigated in a rainforest at Perinet/ Analamazaotra (Andasibe), Madagascar. Most insectivorous birds in the area participated in mixed-species flocks. Flocks were composed of foliage gleaners, foliage-branch gleaners, trunk gleaners and flycatchers. Species whose foraging techniques and foraging locations in vegetation were similar were different from each other in foraging heights. The nuclear species often occurred in small conspecific flocks in and out of mixed-species flocks.     

Modelling the effects of dams on freshwater fish distributions in Hokkaido, Japan

1. We examined the effects of habitat fragmentation caused by dams on freshwater fish species using a database of 7848 fish presence/absence surveys, conducted between 1953–2003 in Hokkaido, Japan. 2. A series of generalised linear models showed that for 11 of 41 taxa examined, the probability of occurrence had been influenced either negatively (eight taxa) or positively (three taxa) by the presence of a dam downstream from their habitat. 3. Maps of modelled predictions revealed that dams had had widespread negative impacts on certain taxa, while for other taxa the impact was limited to specific basins. Two of the three taxa whose probability of occurrence was increased in areas above dams have long been transplanted into reservoirs in Japan. 4. For four of the eight taxa whose probability of occurrence was reduced above dams and all three taxa whose probability of occurrence increased above dams, the temporal length of habitat isolation (i.e. the number of years between dam construction and sampling) was also a significant predictor of the probability of occurrence. This pattern indicates that these taxa experienced a gradual rather than an instantaneous population impact as a result of dam construction. 5. The eight taxa whose probability of occurrence was reduced as a consequence of dams all exhibit migratory life cycles. Although migratory taxa are probably more susceptible to the negative effect of dams, we could not detect significant relationships between migration life histories and the effect of fragmentation by dams. 6. These analyses enable stream and fisheries managers to quantify the impacts of habitat fragmentation because of dams for individual species. The spatially explicit nature of our analyses also enables identification of the areas of the impact at broad geographical scales. Using our results, managers can take effective conservation and restoration measures to predict, mitigate or remove the impact of dams. For example, our results can be used to prioritise dams for removal or to predict losses of biodiversity and ecosystem services in advance of dam construction.     

Development and characterization of microsatellite markers in a clonal plant,Dioscorea japonica Thunb.

We developed 10 microsatellite loci from genomic DNA of a dioecious clonal plant, Dioscorea japonica. Out of 384 clones, 148 contained microsatellite repeats. Polymerase chain reaction primer pairs were designed for 95 of these clones from their sequence data, of which, 10 pairs produced successful amplification. Thirty‐eight individuals were genotyped for allelic diversity. We detected three to nine alleles per locus, and the expected heterozygosity ranged from 0.461 to 0.851.     

Calcium Inhibits Ion-Stimulated Stomatal Opening in Epidermal Strips of Commelina communis L.

Inoue, H. and Katoh, Y. 1987. Calcium inhibitsion-stimulatedstomatal opening in epidermal strips of Commelina communis L.—J.exp. Bot. 38: 142–149. Ca²⁺ suppressed both the ion-stimulated stomatal opening andH⁺ extrusion of pre-illuminated epidermal strips isolated fromCommelina communis L. In the absence of Ca²⁺, the rate of H⁺release was 18 nmol H⁺ cm^–2 h^–1 per epidermal stripunit area in 150 mol m^–3 KCL at pH 7?4. Half-maximum inhibitionof stomatal opening was observed with 220 mmol m^–3 ofCa²⁺. The hexavalent dye, ruthenium red, showed concentration-dependentprevention of the inhibition by Ca²⁺ of the ion-stimulated stomatalopening. The effect of ruthenium red was non-competitive, andthe K₁ for the calcium inhibition was found to be 3?6 mmol m^–3.The calcium inhibition of H⁺ extrusion was also prevented byruthenium red. These results suggest that Ca²⁺ inhibits theactivity of electrogenic H⁺ translocating ATPase of the guardcell plasma membrane and leads to the suppression of stomatalopening. Key words: Calcium, Commelina communis, ruthenium red, stomata     

Effects of temperature on the development of overwintering immature stages of the near‐threatened butterfly Leptalina unicolor (Bremer & Grey) (Lepidoptera: Hesperiidae)

Overwintering larvae of multivoltine and univoltine populations of Leptalina unicolor were reared under various constant and fluctuating temperatures superimposed on a photoperiod of either 12 h of light and 12 h of darkness (LD 12:12) or LD 15:9. Diapause of the larvae terminated in midwinter (by early February). All the larvae of both populations pupated after two molts without feeding and the head capsule width of the final instar larvae was smaller than that of the penultimate instar ones. The photoperiod did not significantly affect larval development, but long‐day conditions (LD 15:9) hastened pupal development. The thermoperiod had a significant effect on the development of the multivoltine population. When multivoltine population larvae were kept under a low fluctuating temperature regime (cryophase/thermophase = 14/20°C), the period until adult eclosion was shorter than that under a constant temperature of 17°C. On the contrary, when larvae were kept under a high fluctuating temperature regime (24/30°C), the period until adult eclosion was longer than that under a constant temperature of 27°C. However, the univoltine population did not show such a reaction to the fluctuating temperature. The durations of final instar larva and pupa of the multivoltine population were shorter than those of the univoltine population. The developmental zeros of penultimate and final instar larvae and pupae of the univoltine population were lower than those of the multivoltine population. The head capsule width of penultimate instar larvae and the forewing length of adults of the univoltine population were larger than those of the multivoltine population for both sexes.     

The Genesis and Transmission of Epidermal Potentials of Newt Embryonic Cells in Vivo and in Vitro

The genesis and transmission of action potentials in epidermal cells of a newt ( Cynops pyrrhogaster ) embryo were investigated quantitatively in vivo during development and in vitro in the absence of nerve cells. Typical action potentials, composed of a fast spike followed by a slow action potential, can be recorded from any of the epidermal cells from Stage 24/25 to 35/36. The potential is graded with current intensity, and only the slow component induces transmission to other epidermal cells. The fast spike is found in all epidermal cells from Stage 24/25 to Stage 50; it is abolished by Stage 52. The slow potential disappears at Stage 38 just before or after hatching. The cultured epithelioid explants (epithelioid aggregate) and cultured monolayer cells taken from the presumptive epidermal tissue of the ectoderm of the pregastrula, indicate that sequential changes in the genesis of the dual action potentials are similar to those of the intact embryo. In monolayer cell culture devoid of nerve cells, the epidermal cells, also generate a two-step action potential. Such two-step potentials are characteristic of both ciliated and non-ciliated epidermal cells and occur even during mitotic activity. In contrast, cultured neural plate cells isolated from the neurula generate typical spike-like action potentials.