Mathematical Biology and related seminars
|Hisashi Ohtsuki -- 3:00 pm in ESB 4127|
Dept of Evolutionary Studies of Biosystems, The Graduate University for Advanced Studies (SOKENDAI)
|Allele frequency spectrum in a cancer cell population |
A traditional population-genetics approach studies geneaologies in a population of a fixed size, which forms the basis of several spectral theories of finite samples. In contrast, a population of tumor cells typically experiences an exponential growth phase in its initial progression, which is far from constant population size. In this work, I develop two different numerical procedures, one of which is based on forward-in-time and the other is based on backward-in-time treatment, to derive allele frequency spectrum in such exponentially growing cancer cell populations. We find significance bias toward singletons both analytically and numerically, which reflects the fact that most observed mutations have recent origins in a growing population.
|Comment:||This work was done in collaboration with Prof. Hideki Innan|
|Caroline Colijn -- 3:00 pm in ESB 4127|
|Connecting genomic data with vaccine design through modelling|
While vaccines are available and are effective in protecting against
colonisation and disease with Streptococcus pneumoniae, their effectiveness
is limited by strain (serotype) replacement following widespread
vaccination. Understanding the post-vaccination balance of serotypes would
present the opportunity to achieve a final population composed of the most
benign (non-invasive) strains. However, the complex ecology of the
pneumococcus makes it difficult to predict the post-vaccination balance of
strains. Recently, Corander et al proposed that there is widespread
apparent negative frequency-dependent selection (NFDS) in the pneumococcus (Corander et al 2017 Nat. Ecol. Evol.).
Here, we use this principle to develop a deterministic model of
pneumococcal strain dynamics, and use the model to make predictions about
the ecological response of the pneumococcal population to new candidate
vaccine strategies. We find that we can identify formulations that
out-perform existing formulations in the model. Furthermore, it is possible
to obtain a final model population that scores as well as the currently
used formulation, using a vaccine strategy with fewer serotypes -- these
formulations would be much less costly to produce than current vaccines. We
suggest that this approach could provide a template for principled vaccine
design based on global surveillance data and genomics.
This is joint work with N. Croucher.
|Comment:||Dr. Colijn is a new C150 Chair holder at SFU, and is just recently arrived in BC.|
|Gerardo Ortigoza -- 3:00 pm in ESB 4127|
Universidad Veracruzana Mexico
|Mathematical modeling and simulation of the Chikungunya spread in Veracruz Mexico|
Chikungunya is a viral disease transmitted to humans by infected mosquitoes: Aedes aegypti and Aedes albopictus. It causes fever and severe joint pain. Other symptoms include muscle pain, headache, nausea, fatigue and rash. Joint pain is often debilitating and can vary in duration.
Some of the main mathematical methods to simulate Chikungunya
spread are set as ordinary differential equations over compartmental models, SEIR for host and sei for vectors. We propose a spatio-temporal description of chikungunya spread using a cellular automata over unstructured triangular meshes.
|Comment:||Prof. Ortigoza is a sabbatical visitor in the Department of Mathematics, hosted by Prof Fred Bruer|
|Geoff Wasteneys -- 3:00 pm in ESB 4127|
Dept of Botany, UBC
|Mechanisms modulating developmental transitions in plants|
Geoff plans to talk about the transition from
proliferation to differentiation, which is work following up on the paper
that his group recently published in Current Biology.
|Simon van Vliet -- 3:00 pm in ESB 4127|
|Sarafa Iyaniwura -- 3:00 pm in ESB 4127|
Department of Mathematics, UBC
|Instability triggered by a single defective cell among a group of cells in a two-dimensional domain|
We formulated and analyzed a class of coupled cell-bulk PDE-ODE model for describing communication between localized spatially segregated dynamically active signallying compartments of common small radius, which are coupled through a passive bulk diffusion in a two-dimensional domain. Each of these cells secret some chemical into the medium, and can also sense the concentration of this chemical around their boundary, which in turn leads to the activation of signaling pathways within the cells that enable them adjust their intracellular dynamics. In the limit where the bulk diffusion coefficient is asymptotically large, the method of matched asymptotic expansions is used to reduce the coupled PDE-ODE model into a system of ODEs. This system further studied to investigate the existence of instability through Hopf bifurcation that is triggered by a single defective cell among a group of identical cells. Furthermore, we studied the effect of the effective area of the domain on the synchronization of the intracellular dynamics of the cell.
|Alex Mogilner -- 4:00 pm in TBA|
NYU (Courant Institute)
|Self-polarization, rapid migration and turning of motile cells|
Cell migration is a fundamentally important phenomenon
underlying wound healing, tissue development, immune response
and cancer metastasis. Understanding basic physics of the
cell migration presented a great challenge until, in the last
three decades, a combination of biological, biophysical and
mathematical approaches shed light on basic mechanisms of
the cell migration. I will describe models, based on
nonlinear partial differential equations and free boundary problems,
which predicted that individual cells do not linger in a symmetric
stationary state for too long, but rather spontaneously break
symmetry and initiate motility. The cells can either crawl straight,
or turn, depending on mechanical parameters. I will show how
experimental data supported the models, and I will also review
current computational challenges.
|This seminar is part of the IAM Colloquium Series.|
|Comment:||This lecture is part of the IAM Distinguished Alumni Series|
|Joy Richman -- 3:00 pm in ESB 4127|
Dept of Dentistry, UBC
|Coordination of mesenchymal cell movements is required for facial morphogenesis|
|Paul Kulesa -- 3:00 pm in TBA|
Srowers Medical Institute
|This seminar is part of the IAM Colloquium Series.|
|Comment:||Distinguished IAM Colloquium|