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Jennifer Tenlen
Postdoc 2007-2012
now an Assistant Professor at Seattle Pacific University

Developing an RNAi protocol to disrupt gene function in water bears

How morphological diversity arises is a key question in evolutionary developmental biology. As a long-term approach to address this question, we are developing the water  bear Hypsibius dujardini (Phylum Tardigrada) as a model system. We expect that using a close relative of two well-studied models, Drosophila (Phylum Arthropoda) and Caenorhabditis elegans (Phylum Nematoda), will facilitate identifying genetic pathways relevant to understanding the evolution of development. Tardigrades are also valuable research subjects for investigating how organisms and biological materials can survive extreme conditions. Methods to disrupt gene activity are essential to each of these  efforts, but no such method yet existed for the Phylum Tardigrada. We developed a protocol to disrupt tardigrade gene functions by double-stranded RNA-mediated RNA interference (RNAi). We found that targeting tardigrade homologs of essential developmental genes by RNAi produced embryonic lethality, whereas targeting green fluorescent protein did not. Disruption of gene functions appeared to be relatively specific by two criteria: targeting distinct genes resulted in distinct phenotypes that were consistent with predicted gene functions (see movie for an example), and by RT-PCR, RNAi reduced the level of a target mRNA and not a control mRNA. These studies represent the first method for disrupting gene functions in the phylum Tardigrada. Our results form a platform for dissecting tardigrade gene functions for understanding the evolution of developmental mechanisms and survival in extreme environments.

Competition between cells to join the germline?

water bear tardigrade hypsibius dujardiniSexually-reproducing animals produce germ cells, totipotent cells able to give rise to entire organisms. A key question in germ cell research is how this totipotency is regulated.  In many animals, including mammals, germ cells are specified late in embryogenesis by cell-cell interactions, but the signals that specify germ cell fate in such cases are not understood.  We have developed the tardigrade Hypsibius dujardini (pictured at right) as a model system for comparative studies in germline development. Previous work in our lab has suggested that cells in an equivalence group may be germ cell precursors. These cells have the same potential cell fates, but only one cell is chosen stochastically to internalize and become a candidate germ cell, while the other divides at the embryo surface and adopts an alternate fate. These observations suggest that cells may compete to enter the germline. I am identifying and characterizing germ cells in H. dujardini, and I am working on developing methods to disrupt gene function by RNA interference to further address this issue.  These studies may provide insight into how cells can compete to enter the germline, and may provide a system for long-term study of the evolutionary consequences of such competition.

More about tardigrades

Honors and Awards:

2011: Jenny received a UNC postdoctoral mentoring award!

2010: Jenny was invited to author the Water Bear entry for World Book Encyclopedia!

2009: Jenny was awarded a UNC Postdoctoral Award for Excellence in Mentoring!

2008: Jenny was awarded a SPIRE postdoctoral fellowship!

2008: Jenny was selected as the postdoc speaker for the UNC Developmental Biology Symnposium!

2007: Jenny was awarded a slot on UNC's Developmental Biology Training Grant!

Jenny's papers:

Tenlen JR, S McCaskill and B Goldstein. RNA interference can be used to disrupt gene function in tardigrades. Development Genes and Evolution (in press).

Tenlen JR, Molk JN, London N, Page BD, Priess JR.
MEX-5 asymmetry in one-cell C. elegans embryos requires PAR-4- and PAR-1-dependent phosphorylation.
Development. 2008 135:3665-75

Rasmussen JP, English K, Tenlen JR, Priess JR.
Notch signaling and morphogenesis of single-cell tubes in the C. elegans digestive tract.
Dev Cell 2008 14:559-69

Page BD, Diede SJ, Tenlen JR, Ferguson EL.
EEL-1, a Hect E3 ubiquitin ligase, controls asymmetry and persistence of the SKN-1 transcription factor in the early C. elegans embryo.
Development 2007 134:2303-14

Tenlen JR, Schisa JA, Diede SJ, Page BD.
Reduced dosage of pos-1 suppresses Mex mutants and reveals complex interactions among CCCH zinc-finger proteins during Caenorhabditis elegans embryogenesis.
Genetics 2006 174:1933-45

Park FD, Tenlen JR, Priess JR.
C. elegans MOM-5/frizzled functions in MOM-2/Wnt-independent cell polarity and is localized asymmetrically prior to cell division.
Curr Biol 2004 14:2252-8