In the past researchers have found polymorphisms associated with
the internal transcribed spacer (ITS) region in the DNA of certain
plant parasitic nematodes. Within DNA are regions that are coding
and which contain genes that are transcribed, while there are also
regions of non-coding DNA (like the internal transcribed spacers)
that theoretically do not hold any important information for transcription.
Non-coding DNA generally evolves much faster and is therefore more
appropriate for detecting sequence variations between and within individuals.
The purpose of this study will be to use the ITS region to screen
for polymorphisms in a diverse range of nematodes. This will help
me to establish a rough estimate of variation in other groups of nematodes
besides plant parasites. I have chosen the Botanic
Gardens as my site for collecting nematodes for a few reasons.
One reason is that with the diversity of plants inhabiting the different
gardens there should be an equal diversity of nematodes throughout
the different areas of the gardens as well. Also there should be a
wide variety of introduced species from all over the world within
the different habitats because of the various plants that have been
introduced. Finally, a fellow student is currently looking at the
diversity of nematodes throughout the Gardens so by the onset of my
project I will know which area will have the highest diversity of
nematodes.
My plan is to use five individual nematodes from ten different species
to obtain ITS sequence, and to check these sequences for multiple
peaks indicating intragenomic polymorphism, as well as for differences
between individuals of the same species. I will first collect 4 samples
of 500 ml soil in an area of the Botanic Gardens where the highest
nematode diversity is found. Five individuals each from ten different
species will be selected from the samples, i.e. a total of 50 nematodes.
All individual nematodes will be looked at using microscopy and video
captured for the purpose of making morphological observations. The
DNA of each individual will then be extracted and used for amplification
in Polymerase Chain Reaction (PCR). After PCR I will check the size
of the amplified DNA by electrophoresis and clean up the PCR products
by removing leftover primers and single nucleotides. The next step
will be to give the cleaned products to the Core Instrumentation Facility
of the UCR Genomics Institute
for sequencing. After completion of the sequencing I will align and
analyze the resulting data to look for polymorphisms in the ten nematode
species.