oringham's blog

Spinacia oleracea L., commonly known as spinach is widely used in the scientific world as a model organism for many areas of study such as DNA synthesis and cellular respiration. Spinach is a good model system due to its cheap price, accessibility, rich chloroplast content, and easiness to handle and maintain. Like all plants, spinach uses photosynthesis in order to create energy and sustain life.

Photosynthesis occurs in the chloroplast and has two sequential stages; light-dependent reactions and light independent reactions.  Light dependent reactions take place in the thylakoid membrane, and use the light energy photons from the sun to excite pigment in the cell and activate a high energy electron transport chain. ATP, O2, and NADPH are the products of the reactions that occur in the light-dependent stage of the photosystem. These products then are used in the light-independent stage, or the Calvin Cycle, which takes place in the stroma and creates GA3P and CO2.

Different types of plants and leaves experience different levels of chlorophyll. Because of this, it is thought that the amount of photosynthesis would increase in leaves with higher levels of chlorophyll, as chloroplasts are the main component of photosynthesis (Emerson, 1929). Spinach is a dark green leaf, containing high levels of chlorophyll. Conversely, Lactuca sativa L., romaine lettuce is a medium to light green leaf, containing medium to low levels of chlorophyll. Based on this knowledge, it can be predicted that spinach will photosynthesize faster than romaine lettuce. If this is correct, the data will show a higher change in absorbance over time in spinach than in romaine lettuce.

Figures 2-5 depict the amount of organisms in each vial by percent, separated by developmental stage. It is apparent that the control group yielded the highest percentage of pupae, at about 55%. Groups treated with precocene experienced a much lower percent yield of pupae, with 0.1 μM precocene yielding the lowest at 13.7%. The control yielded the lowest percentage of adults, at 30.6%, while 1 μM precocene yielded the highest percentage of adults at 55%. Most of the larval d. melanogaster were found in the 0.1 μM precocene group, with 45% of that group containing larvae. The control contained the least amount of larvae percentage, with only 14.3% making up that group.

The data below demonstrates the difference between growth and maturation of flies treated with different levels of precocene, and flies not treated with precocene. Table 1 displays the raw counts collected from the vials, where each organism was counted and grouped by developmental stage. Table 2 shows the measured fly lengths of 5 males and 5 females from each treatment group. Figure 1 displays the average fly lengths for males and females for each treatment group graphically. It is apparent that both males and females had the same average length within each treatment group, except for 1 μM precocene. Additionally, it is shown that 0.1 μM precocene treated flies have the longest average length, with an average length of 0.45 millimeters for both male and female. Male flies treated with 1 μM Precocene appear to have the shortest average fly length, with an average length of 0.32 millimeters.

Overall, differences in ruffle presence and motility rate between the two cell types are likely due to differences of the roles they play in their environment. Fibroblasts’ role in comprising connective tissue make cell motility necessary for proper function of tissues. B16 melanoma cells divide and spread uncontrollably, so relative rapid motility is not a necessary quality for these cells to have.

Melanoma (B16) and fibroblast cells (NIH 3T3) were placed on a heated plate at 37°C. Using phase contrast microscopy at 40X magnification, multi-D acquire in ImageJ was employed to create movies of snaps taken of the live cells every 5 seconds for 95 intervals, creating seven minute movies. Time-lapse data was then analyzed observationally and quantitatively.

The purpose of this study was to investigate the differences and similarities in membrane ruffling of fibroblast cells (NIH 3T3) and melanoma cells (B16). Membrane ruffling involves the formation of newly polymerized actin filaments at the cell surface creating lamellipodia, which extend and allow the cell to actively migrate. Examining differences in quantity and frequency of ruffle formation can provide rationale for differences in roles that each cell type plays.

Discrepancies between aspects of the original and replicate figures can be explained by a variety of factors that were not controlled for or described in the Methods section. These factors include photo angle, flower choice, font choice, and country selection.

    A possible explanation for the discrepancies between figures 1A and 2A could be that the replicated photo was taken of a different bloom on the tree. This could have happened because there was a lack of explicit detail explaining exactly which bloom was photographed in the original figure. Additionally, the angle was not specified in the methods whether is was to the right or left side of the ceiling of the conservatory.

Figures 1B and 2B are not drastically different from one another. There are discrepancies between the amount of leaves captured at the top of the tree, but many of the factors that could have resulted in major differences in the figure were controlled by the limited angle options due to the corner placement of the tree.

Differences between figures 1C and 2C are explained by the lack of explanation in how to create state borders on the figure map website. The default world map setting does not include state borders, so a box must be checked in order for the borders to be seen. With this box checked, each individual state can be highlighted and Florida can be colored in.These directions were not explicit in the methods section, and this step was missed in the execution of the map making for the replicate figure. Additionally, the type of font was not detailed in the methods, resulting in a different font used to label the figures on the replicate.  

Both figures differed across several aspects, despite attempting to control for factors to limit discrepancies. Both figures differed with respect to the particular flower that was captured photographically, as well the angle at which these blooms were captured. The angle at which the tree was captured also varied slightly. Additionally, the countries in which C. haematocephala are indigenous were labeled differently on the map portion of the figure, as well as font style of the figure labels.