I need some assistance with these assignment. article title Thank you in advance for the help! The article “Cancer Stem Cells Tracked” published in the Nature journal reveals how small groups of cancer cells in which the tumor initially originated were tracked with the help of genetic markers. This study would help in targeting the right set of cells during chemotherapy and also pave the way for the development of new cancer therapeutics and is based on the hypothesis that tumors develop from so-called abnormal cancer stem cells that give rise to similar cells. Earlier support for this hypothesis has been provided by studies in which cells from cancer biopsies were injected into healthy mice and the new tumors that developed within these mice had their lineage in the injected cancer cells. The article reveals three separate research studies conducted to track the origins of cancer cells in the brain, gut and skin using genetic markers as labels. The studies conducted by Luis Parada and Hans Clevers on brain and gut cancers respectively used genetic labels to mark healthy adult stem cells which had the potential to develop into tumors and analyzed whether the newly formed cancer cells contained the same labels as their predecessors. In the experiment conducted by Parada on glioblastoma, the tumors also contained some unlabelled cells which had also originated from the labeled cells which relapsed following chemotherapy. However, when the labeled cells were targeted using chemotherapy the glioblastoma underwent significant shrinkage. Clevers and his team used drug-inducible genetic markers which when activated caused the cells carrying the marker to fluoresce in one of the four colors. When a second dose of the drug was injected the initially fluorescing cells gave rise to a new set of cells that fluoresced with a different color thus supporting the hypothesis that cancer stem cells give rise to new tumor cells. In the experiment involving the skin tumor conducted by Cedric Blanpain, individual tumor cells were labeled and when tracked these either gave rise to a small cell lineage before diminishing or continued to produce more cells. Thus the study provided a strong experimental evidence for the existence of cancer stem cells and further research involved relating these tracked cells with those of the putative cells which have been found from transplantation studies.
The photosynthetic ability of aphids using the carotenoid pigment which they synthesize is explored in the Nature article, “Photosynthesis-like process found in insects”. Aphids and another possible creature namely the two-spotted spider mite, Tetranychus urticae, possess a unique ability to synthesize their own carotenoid pigments much like that of plants, algae and certain bacteria and fungi. Findings from previous research have concluded that high content of carotenoids are found in the insect which enthused entomologists Alain Robichon and his team who have related the high production of the chemical with the ability of the insects to capture sunlight and convert it into energy. A known fact is that these pigments are responsible for the color of the insect which varies depending on the environmental conditions. In cold and optimal temperatures the aphids were green and orange respectively while they turned white when the population increased and during lesser resources. The team subsequently measured the levels of ATP, which are the major energy molecules, produced in these insects and the findings correlated with the levels of carotenoid pigments present in these insects. While the ATP levels were high and moderate in green and orange aphids, their production was significantly lesser in the white population. The extracts obtained from the purification of the carotenoids further confirmed that these pigments were involved in the energy production process by absorbing sunlight. In addition, the anatomical presence of the pigments which form a layer under the cuticle of the insect is also indicative of the fact that they are in the right position to absorb the sun’s radiation. However, there are also unanswered questions that are concerned with the need for energy production by these insects as their normal diet itself is more than sufficient for their energy requirements. While there is a speculation about using the energy gained through the photosynthetic process during times of stress, this however, needs to be conclusively proven.
1. Baker, Monya. “Cancer stem cells tracked.” Nature 488 (2 Aug. 2012) : 13-14. Web. 29 Nov. 2012. http://www.nature.com/news/cancer-stem-cells-tracked-1.11087
2. Lougheed, Kathryn. “Photosynthesis-like process found in insects.” Nature (17 Aug. 2012) : doi: 10/1038/nature.2012.11214.