A Deep Dive into a Graduate Student’s Research Experience

Josh Chastek

 

josh in the lab

My name is Josh Chastek. I am a native Spokanite, science enthusiast, and outdoor adventurer. I enjoy backpacking, photography, orchids, and airplanes. I am also interested in genetics, microscopy, and cell culture. I completed my undergraduate degree at EWU and continued at EWU because I was not (and am not) done learning about biology.

My initial focus in biology was with cryobiology, the study of the effects freezing temperatures on living tissues. That interest brought me into contact with Dr. Charlie Herr, with whom I now work. The Herr lab focuses on the development of technologies for endangered species preservation. The kinds of research I’ve been able to participate in have transformed my interest in biology into a love of cell culture systems and technology development. During my time as a graduate student, I have worked on freezing fish sperm and insect embryos. I have also worked on culture system development for growth of reproductive organs in fish, cats, dogs, Drosophila (fruit flies), and silkworms.

One of the coolest aspects of working at a university is getting undergraduates involved in real world research. Some of our research includes:

  • The development of reproductive cell culture technologies.

We have worked on optimizing cell culture systems to grow tissues of plants, vertebrates, and invertebrates. Our insect research has included using honey bees, Drosophila species, and silkworms as models. Prior to my arrival, Dr. Herr had developed technology for the long-term storage of honey bee semen. This technology (combined with the ability to artificially inseminate honey bees) gives researchers the ability to bring in bee semen from around the world and produce hives with greater genetic diversity.

  • The development of cell culture systems for the storage of insect gametes and reproductive tissues.

This is an important issue because at this time there are no genetic storage techniques for many species of insects. Drosophila have been an important research model for the last century (Jennings 2011). Current and future drosophila research depends on the maintenance of many, some 40,000 plus, different fly strains. No reliable cryogenic methods have been developed to store gametes or embryos and all of these stocks must be maintained alive. There are large resource and time costs associated with maintaining these stocks. Our lab has been using what was learned from freezing honey bee sperm to develop methods for freezing Drosophila gametes and embryos.

josh blog image 3

Live/dead cell stain of drosophila embryo

  • The optimization of cell culture systems for growing insect reproductive organs to use for in vitro fertilization experiments.

silmoth portrait

Another insect model we work with in our lab is the silkworm, Bombyx mori. Silkworms are important for the luxury resource they provide as well as their role as research model. They are specialized feeders who only eat the leaves of mulberry trees and can no longer be found in the wild. Due to their extended time in domestication (over 5000 years) silkworms are extremely susceptible to pathogens and environmental irregularities. Technologies to store their genetics would be beneficial to the world’s silk producers and researchers. We have reason to believe that because of their unique mating style, silkworms may be a good insect model to attempt in vitro fertilization with. In order to successfully produce progeny, in vitro, mature eggs and sperm must be collected and mixed together in media that will support them. Silkworms mate directly after emerging as moths, if they can find a mate, suggesting that the male and female gametes are mature and ready for fertilizing after emerging from their cocoon. Mating moths will connect for 12-24 hours and during this time the male will use a peristaltic pumping action to mix his sperm with all of the females eggs. The moths will separate after the sperm transfer which is followed by the female depositing all of the fertilized eggs. This is different than other insects like Drosophila who use individual sperm to fertilize eggs as they are produced and matured over the insects lifespan. Using information gained from research using honey bees and drosophila, we have been working to develop a cell culture system that allows for the survival of silkworm gametes and reproductive tissues. Optimizing a media to mix the sperm and eggs in has been the main focus of our silkworm research.

In the fall of 2018 we established a silkworm colony here at EWU. The goals of building the colony were to learn how maintain a population of silkworms, and also to be able to provide silkworms at all stages of their life cycle to do research with. We were successful in raising and mating silkworms. Undergraduate researcher Rachael Doty helped establish and maintain the colony (thanks Rachael)!

We were not able to attempt any in vitro fertilization trials last year, but we were able to keep silkworm testicular tissue alive in one of two of our selected cell culture media. We are starting another colony this spring and will use what we learned from the previous experiments to attempt in vitro fertilization this quarter. Once we have optimized a system to allow for fertilization we would like to begin working on freezing the sperm, eggs, and fertilized embryos.

If you, like me, have a passion for research that hasn’t been sated by an undergraduate degree, you should consider continuing your education. Acquiring an MS will not only give you new tools and some teaching experience, but will allow you to dive deep into a research experience.

Works cited:

1).B. H. Jennings, Drosophila – a versatile model in biology & medicine, Mater. Today, 2011, 14, 190–195

https://www.sciencedirect.com/science/article/pii/S1369702111701134

2).Hopkins, Brandon and Herr, Charles.(2010). Factors affecting the successful cryopreservation of honey bee spermatozoa. Apidologie 41: 548-556.

https://www.apidologie.org/articles/apido/full_html/2010/05/m09054/m09054.html

3).Hopkins, Brandon & Cobey, Susan & Herr, Charles & Sheppard, Walter. (2016). Gel-coated tubes extend above-freezing storage of honey bee (Apis mellifera) semen to 439 days with production of fertilised offspring. Reproduction, fertility, and development.

https://www.ncbi.nlm.nih.gov/pubmed/27977389

4).Stucky M., Hopkins BK, Mr. C. (2008) Cryopreservation of honey bee spermatozoa,     Reprod. Fert. Dev. 20, 127-128.

https://doi.org/10.1071/RDv20n1Ab94

5). Hopkins Brandon K., Herr Charles, Sheppard Walter S. (2012) Sequential generations of honey bee (Apis mellifera) queens produced using cryopreserved semen. Reproduction, Fertility and Development 24, 1079-1083.

http://www.publish.csiro.au/RD/RD11088

 

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