Evidence for the formation of comet 67P/Churyumov-Gerasimenko through gravitational collapse of a bound clump of pebbles

The processes that led to the formation of the planetary bodies in the Solar System are still not fully understood. Using the results obtained with the comprehensive suite of instruments on-board ESA’s Rosetta mission, we present evidence that comet 67P/Churyumov-Gerasimenko likely formed through the gentle gravitational collapse of a bound clump of mm-sized dust aggregates (“pebbles”), intermixed with microscopic ice particles. This formation scenario leads to a cometary make-up that is simultaneously compatible with the global porosity, homogeneity, tensile strength, thermal inertia, vertical temperature profiles, sizes and porosities of emitted dust, and the steep increase in water-vapour production rate with decreasing heliocentric distance, measured by the instruments on-board the Rosetta spacecraft and the Philae lander. Our findings suggest that the pebbles observed to be abundant in protoplanetary discs around young stars provide the building material for comets and other minor bodies

The Comet Interceptor Mission

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA’s F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms−1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes – B1, provided by the Japanese space agency, JAXA, and B2 – that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission’s science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule

The effect of flaxseed on the growth and metastasis of human breast cancer cells in athymic nude mice

grantor: University of TorontoFlaxseed (FS), with high levels of the lignan, secoisolariciresinal diglycoside (SDG), and Ã-linolenic acid (ALA)-rich flaxseed oil (FSO), was tested for its ability to inhibit the growth and metastasis of MDA-MB-43 human breast cancer cells in athymic nude mice. FS (10% wt/wt) fed to CLR-nu/nu mice inhibited early tumour growth but not lung metastasis. In NCR-nu/nu mice, 5% and 10%FS had no significant effect on primary tumour growth, whereas 15%FS tended to be stimulatory. All FS diets reduced the number of recurrent tumours, but 10% and 15%FS yielded the smallest and largest mean tumour sizes, respectively. 10%FS produced the lowest number of total metastases, whereas in the lung, 5%FS increased all metastasis growth parameters and 15%FS increased the mean area per metastasis. FSO and SDG at the level found in 15%FS affected tumour growth and metastasis in an opposite manner to 15%FS. In NCR-nu/nu mice with established tumours, 10%FS suppressed lymph node metastasis. Overall, the effect of FS on MDA-MB-435 tumour growth and metastasis depends on the mouse strain, level of FS, and experimental design.M.Sc

Replacement of Dietary Saturated Fat by PUFA-Rich Pumpkin Seed Oil Attenuates Non-Alcoholic Fatty Liver Disease and Atherosclerosis Development, with Additional Health Effects of Virgin over Refined Oil.

As dietary saturated fatty acids are associated with metabolic and cardiovascular disease, a potentially interesting strategy to reduce disease risk is modification of the quality of fat consumed. Vegetable oils represent an attractive target for intervention, as they largely determine the intake of dietary fats. Furthermore, besides potential health effects conferred by the type of fatty acids in a vegetable oil, other minor components (e.g. phytochemicals) may also have health benefits. Here, we investigated the potential long-term health effects of isocaloric substitution of dietary fat (i.e. partial replacement of saturated by unsaturated fats), as well as putative additional effects of phytochemicals present in unrefined (virgin) oil on development of non-alcoholic fatty liver disease (NAFLD) and associated atherosclerosis. For this, we used pumpkin seed oil, because it is high in unsaturated fatty acids and a rich source of phytochemicals.ApoE*3Leiden mice were fed a Western-type diet (CON) containing cocoa butter (15% w/w) and cholesterol (1% w/w) for 20 weeks to induce risk factors and disease endpoints. In separate groups, cocoa butter was replaced by refined (REF) or virgin (VIR) pumpkin seed oil (comparable in fatty acid composition, but different in phytochemical content).Both oils improved dyslipidaemia, with decreased (V)LDL-cholesterol and triglyceride levels in comparison with CON, and additional cholesterol-lowering effects of VIR over REF. While REF did not affect plasma inflammatory markers, VIR reduced circulating serum amyloid A and soluble vascular adhesion molecule-1. NAFLD and atherosclerosis development was modestly reduced in REF, and VIR strongly decreased liver steatosis and inflammation as well as atherosclerotic lesion area and severity.Overall, we show that an isocaloric switch from a diet rich in saturated fat to a diet rich in unsaturated fat can attenuate NAFLD and atherosclerosis development. Phytochemical-rich virgin pumpkin seed oil exerts additional anti-inflammatory effects resulting in more pronounced health effects

Virgin pumpkin seed oil reduces circulating markers of inflammation in cholesterol-fed ApoE*3Leiden mice.

<p>Mice were fed a Western type control diet (CON) or CON diet containing 9% refined pumpkin seed oil (REF) or 9% virgin pumpkin seed oil (VIR) for 20 weeks. A: Plasma SAA levels were reduced by VIR. Liver damage marker B: ASAT and C: ALAT were reduced by VIR but not by REF. D: Plasma sVCAM-1 levels in VIR animals were lower throughout the duration of the study. Data are mean±SEM. * p≤0.05, ** p≤0.01 compared with CON. # p≤0.05 for VIR compared with REF.</p

Atherosclerosis development is reduced with virgin pumpkin seed oil.

<p>Mice were fed a Western type control diet (CON) or CON diet containing 9% refined pumpkin seed oil (REF) or 9% virgin pumpkin seed oil (VIR) for 20 weeks. A: representative photomicrographs of HPS-stained cross sections of the aortic root show pronounced development of atherosclerosis in CON animals, which was less pronounced in REF and strongly reduced by VIR. B: Morphometric analysis of lesion area revealed a significant decrease in atherosclerotic lesion area by REF and VIR. C: Anti-atherogenic effects of pumpkin seed oils are specific on severe lesion types. D: Average lesion size was reduced in REF and VIR. E: Immunohistochemical staining for MAC-3 (CD107b) followed by quantification of positively stained area showed that both REF and VIR reduced the macrophage content of type V lesions. Data are mean±SEM. * p≤0.05, ** p≤0.01 compared with CON.</p