Surface of young Jupiter family comet 81P/Wild 2: view from the Stardust Spacecraft

Images taken by the Stardust mission during its flyby of 81P/Wild 2 show the comet to be a 5-kilometer oblate body covered with remarkable topographic features, including unusual circular features that appear to be impact craters. The presence of high-angle slopes shows that the surface is cohesive and self-supporting. The comet does not appear to be a rubble pile, and its rounded shape is not directly consistent with the comet being a fragment of a larger body. The surface is active and yet it retains ancient terrain. Wild 2 appears to be in the early stages of its degradation phase as a small volatile-rich body in the inner solar system.     

6-shogaol (alkanone from ginger) induces apoptotic cell death of human hepatoma p53 mutant Mahlavu subline via an oxidative stress-mediated caspase-dependent mechanism

Mahlavu cells, poorly differentiated and p53 mutants of a human hepatoma subline, are known to be highly refractory to a number of chemotherapeutic agents and radiotherapy due to their high expressions of multidrug resistance gene-1 (MDR-1) and Bcl-2 proteins. Thus, it is desirable to search for an alternative strategy for effective eradication of this type of cancer cells. We present evidence here for the first time that 6-shogaol (6-SG), an alkanone isolated from the rhizomes of ginger, can effectively induce apoptotic cell death of Mahlavu cells via an oxidative stress-mediated caspase-dependent mechanism. The cascade of events in 6-SG-induced apoptosis of these cells involved an initial overproduction of reactive oxygen species (ROS) followed by a severe depletion of intracellular glutathione (GSH) contents. Both events consequently entailed a significant drop in mitochondrial transmembrane potential (DeltaPsim), which ultimately activated the activities of caspases 3/7 resulting in the DNA fragmentation. Interestingly, we also found that N-acetylcysteine (NAC), an antioxidant and a precursor of GSH biosynthesis, could offer a near complete protection of apoptotic cell death exerted by 6-SG. Similarly, exogenously added GSH could also provide protection with an equal efficacy. However, it was paradoxical that both Boc-Asp(OMe)-fmk (a broad caspases inhibitor) and cyclosporin A (an mitochondrial permeability transition opening inhibitor) could only partially protect these cells from 6-SG-induced apoptosis. Taking these data into consideration, it is obvious that GSH depletion is the major contributing factor in arbitrating 6-SG-induced apoptosis of Mahlavu cells. In conclusion, we provide here a novel modality that can help to eradicate a p53 mutant of human hepatoma cells by using a natural consistent isolated form of ginger. These data also provide evidence to reaffirm the notion that consumption of certain foodstuffs can be beneficial to health because some of the constituents contained in them may be anticarcinogenic.     

Diurnal and Semidiurnal Variations in the Earth's Rotation Rate Induced by Oceanic Tides

Recent space-geodetic observations have revealed daily and subdaily variations in the Earth's rotation rate. Although spectral analysis suggests that the variations are primarily of tidal origin, comparisons to previous theoretical predictions based on various ocean models have been less than satisfactory. This disagreement is partly caused by deficiencies in physical modeling. Rotation predictions based on a reliable tidal-height model, with corresponding tidal currents inferred from a modified form of Laplace's momentum equations, yield predictions of tidal variations in Universal Time that agree with very long baseline interferometer observations to 2 microseconds. This agreement resolves a major discrepancy between theory and observation and establishes the dominant role of oceanic tides for inducing variation in the Earth's rotation at these frequencies.     

Lactic Acid Fermentation of β-Carotene Rich Sweet Potato (<Emphasis Type="Italic">Ipomoea batatas</Emphasis> L.) into Lacto-juice

Lacto-juices processed by lactic acid fermentation bring about a change in the beverage assortment for their high nutritive value, vitamins and minerals which are beneficial to human health when consumed. Sweet potato roots (non-boiled/ fully-boiled) were fermented with Lactobacillus plantarum MTCC 1407 at 28 ± 2°C for 48 h to make lacto- juice. During fermentation both analytical [pH, titratable acidity, lactic acid, starch, total sugar, reducing sugar (g/kg roots), total phenol and β-carotene (mg/kg roots)] and sensory (texture, taste, aroma, flavour and after taste) analyses of sweet potato lacto-juice were evaluated. The fermented juice was subjected to panelist evaluation for acceptability. There were no significant variations in biochemical constituents (pH, 2.2–3.3; lactic acid, 1.19–1.27 g/kg root; titratable acidity, 1.23–1.46 g/kg root, etc.) of lacto-juices prepared from non-boiled and fully-boiled sweet potato roots except β-carotene concentration [130 ± 7.5 mg/kg (fully-boiled roots) and 165 ± 8.1 mg/kg (non-boiled roots)]. The panelist evaluation scores ranged from 3–4.8 (in a hedonic scale of 1–5) from moderate liking to very much liking of sweet potato lacto-juice. Principal component analyses reduced the eight original analytical variables to three independent components (factors), which accounted for 99.9% of the total variations. Similarly, five original sensory variables were reduced to two independent components, which accounted for 83.1% of the total variations.     

Effects of long-term phosphorus fertilizer inputs and seasonal conditions on organic soil phosphorus cycling under grazed pasture

Soil microbes and phosphatase enzymes play a critical role in organic soil phosphorus (P) cycling. However, how long-term P inputs influence microbial P transformations and phosphatase enzyme activity under grazed pastures remains unclear. We collected top-soil (0–75 mm) from a grazed pasture receiving contrasting P inputs (control, 188 kg ha⁻¹ year⁻¹ of single super phosphate [SSP], and 376 kg ha⁻¹ year⁻¹ of SSP) for more than 65 years. Olsen P, microbial biomass P, and acid and alkaline phosphatase enzyme activities were measured regularly over a 2-year period. Pasture dry matter and soil chemical properties were also investigated. Results showed that long-term P inputs significantly increased pasture dry matter, total N, and the concentrations of ${\mathrm{NO}}_3^{–}$–N but significantly decreased soil pH and the concentrations of ${\mathrm{NH}}_4^{+}$–N. Total C was not affected by P fertilization. Although Olsen P significantly increased with increasing long-term P inputs, microbial biomass P was similar under P fertilized treatments. Long-term P inputs decreased acid phosphatase activity but increased alkaline phosphatase activity. Microbial biomass P was similar across seasons in the control but decreased in spring and autumn while increased in summer and winter under P fertilized treatments. Acid and alkaline phosphatase activities were significantly affected by season and followed similar seasonal trends being maximum in summer and minimum in winter regardless of P treatment. Correlation and principal component analysis revealed that acid and alkaline phosphatase activities were significantly positively correlated with soil temperature and significantly negatively correlated with soil moisture. In contrast, Olsen P and microbial biomass P were weakly correlated with environmental conditions. The findings of this study highlight the intertwined relationship between organic P cycling and the availability of C and N in soil systems and the need to integrate both soil moisture and temperature in models predicting organic P mineralization, especially in the context of global climate change.