This study tested terrestrial isopods (woodlice) collected from Rice Creek Field Station for the presence of the Wolbachia bacterium and sex-linked genes. DNA was extracted from legs and tissue of male and female isopods and tested using PCR and gel electrophoresis. All 13 isopods tested positive for Wolbachia, suggesting it does not induce host feminization in this species as it does in others. Seven candidate sex-linked gene regions were eliminated. Further testing is needed to give conclusive results on Wolbachia's effects and the isopods' sex-linked genes. The project was funded by Rice Creek Field Station, Summer Scholars, and the Molecular Biology and Biochemistry Center.

1. • Test local populations to see what the prevalence of Wolbachia
is.
• Determine whether Wolbachia induces host feminization like it
does in other species.
• Test whether candidate gene regions identified in an earlier
genomic survey are sex-linked.
• Create preliminary data for further studies and grants proposals.
We thank the following for their assistance in this project:
• Rice Creek Field Station for granting access to the field sites, as well as funds for
preliminary genomic surveys.
• Summer Scholars for providing funds that made this project possible.
• Molecular Biology and Biochemistry Center for providing lab facilities and
supporting this project.
• Dr. Olori and her team (Zack Hall and Calee Wilson) for sharing their field sites
and transportation.
YaDong Wang, Dr. Christopher Chandler
Department Of Biological Sciences,
SUNY Oswego, Oswego, NY
Collect
Isopods
Dissection DNA
Extraction
PCR (Using
primers Wo16S,
Wsp, DM-A, DM-
B
Gel Electrophoresis
• 45 extracted DNA samples
remain for further use.
• Five out of five male samples
tested positive for Wolbachia.
• Eight out of eight female
samples tested positive for
Wolbachia.
• Eliminated seven candidates
from being sex-linked genes.
Figure 6. In the
abdomen, T. rathkei
contains five
tracheae (white dots
on the side of the
abdomen) instead of
two found in other
local species of
terrestrial isopods.
Figure 8. In this gel, lane number 1 is a ladder
(size standard), lane number 2 is a male T.
rathkei sample, lanes 3-6 are females, lane
number 7 is a positive control (Nasonia
vitripennis infected with Wolbachia), and lane 8
is a negative control. In this case, all five T.
rathkei specimens tested positive for Wolbachia.
• All individual specimens screened so far
have tested positive.
• This study suggests that Wolbachia does
not induce host feminization in T. rathkei
as it does in other isopods, because
Wolbachia infections were detected in
both male and female samples.
• Since only 13 out of 45 samples were
tested, it is possible further study is
required to give a conclusive result.
• Seven sex-linked gene primers
eliminated, narrowing the list of candidate
sex-linked genes.
Figure 1. Isopods are
collected from Rice Creek
Field Station and stored in a
container with bark and
leaves.
Figure 7. The exoskeleton of T. rathkei ranges
from light brown to dark brown/black with faint
spots running down both sides.
Tests for Wolbachia and sex-linked genes in
the terrestrial isopod Trachelipus rathkei
Restriction
Digest
Restriction digestion is
used only with DM-A and
DM-B primers. Restriction
enzymes will selectively
cut DNA from some
alleles, but not others. If
these sequences are sex-
linked, we expect PCR
products to be cut only in
males or only in females.
Figure 2. Each specimen
is dissected using forceps
under a dissection
microscope.
Figure 3. Each
specimen’s legs,
muscle tissue, and
gonads are used
for DNA extraction
using Qiagen DNA
kits.
Figure 4. Polymerase chain
reaction (PCR) is performed to
amplify the target sequence,
whether it is Wolbachia or
candidate sex-linked genes.
Figure 5. Gel
electrophoresis is
used to determine
sizes of PCR
products and whether
DNA was cut by
restriction enzymes.
The PCR products
are stained and
visualized using UV
light to see if the
PCR yielded
products.
Van Name, W. G. (1936). The American land and fresh-water isopod Crustacea. Bulletin of the
American Museum of Natural History, 71.
Cordaux, R., Bouchon, D., & Greve, P. (2011). The impact of endosymbionts on the evolution of host
sex- determination mechanisms.Trends In Genetics, 27(8), 332-341. http://dx.doi.org/
10.1016/ j.tig.2011.05.002
Schmidt, C. (2008). Phylogeny of the Terrestrial Isopoda (Oniscidea): a Review. Arthropod
Systematics & Phylogeny, 66(2), 191-226.
Terrestrial isopods are one of the most abundant groups of crustaceans worldwide (Van
Name 1936), and have over 3500 species described (Schmidt, 2008). However, very little is
known about these creatures, especially their genetic makeup. Terrestrial isopods are a
fascinating group of organisms because many species are known to be able to carry
Wolbachia, a microscopic parasite that is able to alter male host development and cause
them to develop as females, even if the host carries male sex chromosomes (Cordaux et al.
2011). Because of these interactions with Wolbachia, isopods’ sex chromosomes are
thought to be constant evolving. Therefore they make a good model system for studying how
sex chromosomes change.