Effect of fruit maturity on efficiency of 1-methylcyclopropene to delay the ripening of bananas

Three bunches of unripe ‘Williams’ banana fruit of different maturity, 173, 156 and 71 days from bunch emergence, were harvested. Fruit from the top, bottom and middle hands from each bunch were fumigated for 24 h with 1-methylcyclopropene (1-MCP) at 0, 5, 50 or 500 nl l⁻¹ at 20^oC. All fruit were then stored at 20^oC in air containing 0.1 μl l⁻¹ ethylene and the time taken for each fruit to ripen (green life) was noted. The green life of fruit treated with 500 nl l⁻¹ 1-MCP varied with fruit maturity. In the two most mature bunches it was 27.9±2.3 days, 4-fold longer than fruit fumigated with 0 nl l⁻¹ 1-MCP (6.7±0.6 days). In the least mature bunch, green life was 39.7±3.0 days, 1.5-fold longer than fruit fumigated with 0 nl l⁻¹ 1-MCP (25.7±2.5 days). Most fruit treated with 500 nl l⁻¹ 1-MCP showed an unacceptable uneven skin colouration when ripe. There was no significant effect on green life of 1-MCP at 50 nl l⁻¹ and 5 nl l⁻¹. Other fruit from these bunches were not exposed to 1-MCP and were held in ethylene-free air until ripe. In the two most mature bunches, these fruit had a significantly shorter green life (11.2±5.6 days in hand 1; 18.9±4.1 days in hands 4 and 6) than fruit that were fumigated with 500 nl l⁻¹ 1-MCP. In the least mature bunch, however, these fruit had a significantly longer green life (56.0±5.9 days) than 1-MCP treated fruit. Since the effectiveness of 1-MCP varied with fruit maturity and in any commercial consignment there is a mixture of fruit maturity, it is concluded that 1-MCP has limited commercial potential for the storage of unripe ‘Williams’ bananas.     

Hepatoprotection of Phyllanthus maderaspatensis against experimentally induced liver injury in rats

The hexane extract of Phyllanthus maderaspatensis (200 and 100 mg/kg) showed significant hepatoprotection on carbon tetrachloride and thioacetamide induced liver damage in rats. The protective effect was evident from serum biochemical parameters and histopathological analysis. Rats treated with P. maderaspatensis remarkably prevented the elevation of serum AST, ALT and LDH and liver lipid peroxides in CCl(4) and thioacetamide treated rats. Hepatic glutathione levels significantly increased by the treatment with the extracts. Histopathological changes induced by CCl(4) and thioacetamide were also significantly reduced by the extract treatment. The activity of hexane extracts of P. maderaspatensis was comparable to that of silymarin, the reference hepatoprotective drug.     

Microscopic Particle Motions in Strongly Coupled Dusty Plasmas

The microscopic particle motions from the crystal to the disordered state of a dusty plasma with micrometer-sized silicon dioxide particle suspensions in a radio-frequency glow discharge system were studied through an optical microimaging system. Small-amplitude random motion around the lattice sites of the crystal state, relative domain motion with varying boundaries, cooperative hopping in the liquid state, and highly disordered motion with increasing radio-frequency power were observed. Chaotic states with different spatial scales under the coherent and stochastic coupling between dust particles and self-organized background plasma fluctuations were also demonstrated.     

Equatorial X-ray Emissions: Implications for Jupiter's High Exospheric Temperatures

Observations with the High Resolution Imager on the Rontgensatellit reveal x-ray emissions from Jupiter's equatorial latitudes. The observed emissions probably result from the precipitation of energetic (>300 kiloelectron volts per atomic mass unit) sulfur and oxygen ions out of Jupiter's inner radiation belt. Model calculations of the energy deposition by such heavy ion precipitation and of the resulting atmospheric heating rates indicate that this energy source can contribute to the high exospheric temperatures(>800 kelvin at 0.01 microbar) measured by the Galileo probe's Atmospheric Structure Instrument. Low-latitude energetic particle precipitation must therefore be considered, in addition to other proposed mechanisms such as gravity waves and soft electron precipitation, as an important source of heat for Jupiter's thermosphere.     

Adaptation limits diversification of experimental bacterial populations

Adaptation to a specific niche theoretically constrains a population's ability to subsequently diversify into other niches. We tested this theory using the bacterium Pseudomonas fluorescens, which diversifies into niche specialists when propagated in laboratory microcosms. Numerically dominant genotypes were allowed to diversify in isolation. As predicted, populations increased in fitness through time but showed a greatly decreased ability to diversify. Subsequent experiments demonstrated that niche generalists and reductions in intrinsic evolvability were not responsible for our data. These results show that niche specialization may come with a cost of reduced potential to diversify.     

Metapopulation dynamics, abundance, and distribution in a microecosystem

The experimental fragmentation of landscapes of a natural ecosystem resulted in declines in the abundance and distribution of most species in the multispecies animal community inhabiting the landscapes and the extinction of many species. These declines caused the deterioration of the positive interspecific relation between local population abundance and distributional extent in this community. However, when patches were connected by habitat corridors, an immigration "rescue effect" arrested declines in both abundance and distribution and maintained the observed positive relation between them. These results demonstrate the importance of metapopulation dynamics and landscape connectivity for the persistence of populations in fragmented landscapes.     

Inter-specific hybrids of Lilium lankongense Franchet produced by embryo-culture

Summary Lilium lankongense crossed with some related species of Lilium produced seeds without endosperm and with very small embryos which would not germinate in soil. Hybrid plants have been obtained from a number of these crosses by culturing excised embryos on sterile nutrient medium. It is suggested that the technique may prove useful in the production of hybrids from other lily species-combinations which are not normally viable.