mmaliha's blog

When one thinks of cancer research, one visualizes rows of petri dish, isolated cell cultures (of either humans or mice) and scientists hunched over benchtops pipetting chemicals. When I heard of my assignment for the LEE-SIP internship, I imagined the same. So, I was really surprised to learn that I would be working with fruit flies and mostly in-vivo. This past summer has taught me that the learning curve of doing research in a lab is exponential and continuous. I have already learned so much, yet there remains so much more to investigate. I have looked into the role of ABC transporters in effluxing chemotherapeutics and facilitating drug resistance. And, I want to understand more about the various regulatory defense mechanisms of our cells and their interaction with toxins. Not only does this research tie in with my current interest in genetics and cell and molecular biology, it also accommodates my future aspirations as an MDPhD candidate. The experiments I am conducting now has valuable implications for future usage of chemotherapeutics and the interaction of cell and molecular biology with environmental science and toxicology.  

I will not lie. Once I had known about my assignment for LEE-SIP internship, I was most excited at the prospect of cancer research. I expected working with petri dishes and isolated cell cultures, either human’s or mice’s. So, I was really surprised to learn that I would be working with fruit flies and mostly in-vivo. It seems as though the learning curve from working in the lab is exponential and continuous I have already learned so much, yet there is so much to run. I want to know the toxicology impacts. Not only does this research ties in with my current interest on genetics and cell and molecular biology, rather it facilitates my future interest and path as an MDPhD candidate. Experiments like what I am conducting now will dictate possible drug uses for chemotherapy patients. Or, at the very least, it will have impact on environmental science and toxicology.

11 mmol or 1.58 grams of isopentyl propionate was expected to be recovered from the acid-catalyzed reaction of 11 mmol of 3-methyl-1-butanol with 13 mmol of propionic acid. However, only 0.292 g of final ester product resulted in a low recovery rate: 18.5%. Low percent recovery could have been due to reflux reaction not going to completion (substantial amounts of unreacted alcohol and carboxylic acid remained in the rb flask after reflux) or loss of organic product during reaction work-up.

Isopentyl propionate had a sugary banana odor, compared to 3-methyl-1-butanol’s bittersweet licorice smell and propionic acid’s bitter vinegar smell. The odor test confirms formation of isopentyl propionate as it is known for its usage as a flavor extract: mainly fruity, ripe, banana smell.

The IR spectroscopy of isopentyl propionate also confirms the formation of an ester product, since it displays the characteristic carbonyl peak specific to esters: sharp, strong, 1740/cm. However, there is some unreacted alcohol product left in the final sample, as evidenced by the broad peak of medium intensity at 3300/cm.

The cooled contents of the flask were transferred to a centrifuge tube containing water (3 mL). The layers were mixed thoroughly, and the aqueous layer was removed. Sat. aq. sodium bicarbonate was added (1 mL) and the layers were mixed again. The aqueous layer was removed, and the process was repeated once more. Sat. aq. Sodium chloride (1 mL) was added to the ester and the layers were mixed. The lower aqueous layer was removed and added to the waste beaker. The organic layer was transferred to a clean vial and 5 spheres of anhydrous CaCl₂ were added as a drying agent. The spheres of CaCl₂ instantly fell apart and mixed with the liquid which indicated the presence of excess water in the ester product. Since product could not be recovered, experiment was halted and another student’s data on isopentyl propionate was used for the ‘results’ and ‘discussion’ portion of the lab report.

The n-propanol (0.82 mL, 11 mmol), propionic acid (0.97 mL, 13 mmol), and concentrated sulfuric acid (4 drops) were added to a 5 mL round-bottomed flask. Contents were mixed thoroughly, and a few boiling chips were added. A distillation apparatus was set up at a 45° angle and the rb flask was heated to a gentle boil on the hot plate. The heating was adjusted so that vapors condensed about ⅓ of the way up the reflux condenser, well above the side arm. After reaction refluxed for 15 minutes, two phases of liquid collected in the side arm, an upper organic phase and a lower water phase. At this point, the apparatus was raised from the heat and tipped so that most of the upper phase in the side arm dripped back into the reaction flask. This process was repeated after 15 minutes. The reaction mixture was allowed to reflux for another 15 minutes (for a total runtime of 45 minutes). Afterwards, the apparatus was allowed to cool for 15 minutes and the entire contents of the side arm were emptied into the flask.

We want to contrast two different periods of starvation (3-days vs. 7-days) and see the impact on spiders’ eating habits (feeding rate, feeding interval) and movement. We also want to observe the combined impact of various environmental stressors and starvation (heat and cold) on spiders’ morphology and behavior. Since a study on long-term starvation revealed that there was difference in the behavior of wolf male and wolf female spiders after food deprivation ( ), we want to observe any difference in behavior due to short-term food deprivation. We also want to observe the impact of competition on predatory behavior after food-deprivation.

    We hypothesize that there would be no difference in morphology after a short starvation period, since metabolism is adjusted and resources are reallocated over a long time (Wilson, 2014). However, we expect there to be significant behavioral change between the not-starved spider and the 7-day-starved spider in terms of feeding speed and feeding amount. We expect the environmental stressors to negatively impact web-building abilities and feeding for all groups of spiders. And, we expect female wolf spiders to feed in a more uniform pattern compared to their male counterparts (reference ). We also expect there to be more aggression present (in the competitive group) between the 7-day starved spiders compared to both the 3-day starved spiders and not-starved spiders.

These studies of long-term starvation also reveal two fundamental facts about spider metabolism. During starvation period, resources will be reallocated from reproductive potential and growth to maintenance and survival to ensure that reproduction can take place when conditions improve (Wilson, 2014; ). Spiders do not adjust metabolism to maintain a constant body weight, rather their lipid is stored efficiently and prepare them for long periods of food deprivation (Jensen et al., 2010).

    Although the effect of long-term starvation has been widely studied on spider morphology, behavior and movement, research is scarce about the impact of short-term food deprivation. This scenario is a much more likely one in the real world, especially for house spiders whose insect supply is limited. Due to our regular interaction with these kinds of spider much of our surrounding environment is shaped by their predatory behaviors. In this proposal, we aim to look into the impacts of short-term starvation on the morphology, behavior and movement of common spiders in Amherst: wolf spiders and cellar spiders.

The feeding behavior of any species can tell us a lot about its metabolism, movement patterns, predatory instincts, and overall ecological impact on its surrounding biomass. Most species of spiders (order: Araneae) are predators, who feed on insects and small invertebrates through the synthesis of sticky webs. Their feeding pattern is mainly influenced by the size and shape of the prey and whether the spider has enough strength to overpower it: preys are supposed to be smaller than the spider’s body but larger than its head. Web-weaver spiders can also survive a long time without food due to spending minimal energy (reference.)

    Due to their unique metabolism and ability to survive without food for extended periods of time, the effect of long-term starvation has been widely studied in spiders. And, the results indicate that starvation still affects various spiders’ morphology, feeding behavior and movement patterns without causing prompt death. Southwestern longlegs spider, Physocyclus mexicanus, exhibit smaller body size, reduced weight, and smaller testis size under severe dietary restrictions (Wilson, 2014). Running crab spider, Philodromus rufus, feed at a higher rate after being starved (Haines and Sisojevic , 2012). The wolf spider, Pardosa agrestis, is more susceptible to cannibalistic tendencies when hungry (Samu et al., 1999). Food-limited wolf spider, Tigrosa helluo, show more locomotive activity than their satiated counterparts (Walker et al., 1999). And, spiders of various species show distinct aeronautic dispersal and ballooning movements after starvation (Mestre and Bonte, 2012; Weyman and Sunderland, 1994).

The feeding pattern of spiders reveal a lot about their metabolism, locomotive behavior, predatory instincts, and ecological impact on surrounding biomass. Long-term starvation affects all of these variables to different extent in different species. However, it is not well-understood how short-term starvation may affect spiders’ feeding behavior and movement. In this proposal, we aim to assess the impact of short-term starvation on feeding behavior and movement of cellar spiders and wolf spiders, under various environmental stressors and in presence of competition. Spiders (n=3) will be placed in individual clear containers and starved for either a 3-day or 7-day period, and their behavior will be contrasted with their satiated counterparts. To understand the combined effect of environmental stressors and food deprivation, some cellar spiders will be placed in cold (18 C) or hot (30 C) environments. The difference in feeding pattern between male and female wolf spiders after short-term starvation will be recorded. And, to assess the impact of competition after starvation, multiple cellar spiders will receive a limited amount of food. All data should be collected in a qualitative manner, outside of feeding rate and mortality of spiders ,and will be analyzed in comparison to the control group of not-starved spiders. Understanding the impact of short-term starvation on spiders’ predatory and locomotive behavior will broaden our knowledge of their metabolic activities and will help us better utilize them for pest control.

Previous studies show that oxidative stress is both necessary and sufficient for triggering ISC proliferation. However, the mechanisms behind oxidative stress and mitogenic signals are relatively poorly understood. This figure displays that TRP1 and RyR genes are required for ISC self-renewal but not differentiation. MARCM clones are analyzed along with their control counterparts 10 d after clone induction. The bar graph represents number of cells per clone, 5 guts were analyzed per genotype, and data shows the average + SEM. MARCM, or mosaic analysis with a repressible cell marker, relies on recombination during mitosis  mediated by the Flp-FRT system. Flp-FRT is a site-directed recombination technology. (FRT= flippase recognition target). According to the researchers, the cells still proliferate but not a lot of them are stem cells. So, these genes TRP1 and RyR are recognized to be important for ISC self-renewal but not for differentiation.