Parasitic Science


Houssam Nasser using a centrifuge. Photos by Brody Salazar.

Houssam Nasser using a centrifuge. Photos by Brody Salazar.

Although parasitoid wasps are multicellular organisms, they are so small some bacteria are larger than them. Intern Houssam Nasser currently assists the University of California, Riverside’s Department of Entomology in researching a species of parasitoid wasp, with molecular work being his focus.

Currently, the lab is studying a group in the Chalcidoidea superfamily, which is comprised of small parasitoid wasps. The group is known as the Mymaridae family, or fairyflies, and can be smaller than single cellular organisms, such as an amoeba. They are the world’s smallest multicellular organisms and can be as small as 0.0139 millimeters, or 139 micrometers in length.

Krissy Dominguez showing DNA sequences.

Krissy Dominguez showing DNA sequences.

Even though many people do not think of molecular information as being closely related to the topic of entomology, it occupies a good deal of the lab’s time. This is because the molecular work isolates and examines gene regions and can be used to properly identify the insects, especially in relation to others, and understand them.

“We’re taking specific gene regions,” says Nasser’s supervisor Krissy Dominguez, “and… we do PCR, we also do next generation sequencing techniques, and we build phylogenetic trees, so like trees of life. We learn how these really important biological control wasps are related to one another. And that gives us a heads up on their evolution and an understanding host associations, behavior, all of which are critically important to agriculture in California and releasing natural enemies to go after pest insects.”

Despite the development of molecular intonation, morphology is still a part of entomology, so the department employs both methods of study, albeit with less of an emphasis on morphology. Dominguez stated the emphasis for the internship was on the former rather than the latter because it would apply more to him.

A large parasitoid wasp.

A large parasitoid wasp.

Nasser’s interest in molecular work is of both personal and occupational. He describes his work with genetic material as being beneficial to him as both a biology major and someone interested in the medical field.

“We are made of cells, and our cells have DNA, right,” says Nasser. “So, I have to get familiar with how to use this DNA because there is a part of medicine called pathology…They look at the different cells, and they use DNA sometimes to diagnose either new diseases or a normal disease, but you can’t detect it unless you studied DNA. So DNA is everywhere in the medical field.”

Nasser’s work in the lab involves DNA extraction, cleaning and polymerase chain reaction, or PCR. PCR is a method of duplicating a segment of DNA and is a necessary step in examining DNA, as it helps the machines process the data.

Nasser incubating specimens.

Nasser incubating specimens.

“You use a bunch of different chemicals, I would say, or reagents, and one of them is polymerase,” says Nasser. “You have the original DNA template, right? So, what you do through this process is you make copies of this one single DNA...the reason why you do that is, when we do the sequencing they have to be amplified so the machine can handle them.”

Once the DNA sequences have been duplicated via PCR, it is sent to a different lab where it goes through the process of sequencing, which is used to identify what nucleotides are in the DNA. When the process is finished, the information is sent back, and the lab analyzes the genes of other insects for comparison.

Nasser describes the whole internship as being enjoyable, in part because he was given tasks that he enjoyed, and he finds PCR to be his favorite. He appreciates that he is learning new skills that he can use later in life, both at university and in his desired career.

“In general, overall, the internship is not difficult at all. It’s fun,” says Nasser.