John Postlethwait

Professor, Department of Biology
Member, ION

Ph.D. Case Western Reserve
B.S. Stanford Univeristy


Research Interests: Genetic regulation of animal development including development of the nervous system, the mechanisms of sex determination, the origin of novel morphologies in evolution and the evolution of the vertebrate genome.

Overview: Our laboratory is interested in the genetic, genomic, and evolutionary principles that guide animal development. We investigate several aspects of this main problem: 

Genome Duplication: The evolution of gene functions in development after genome duplication, focusing on skeletal development.

Fanconi anemia: A small molecule screen for compounds to rescue zebrafish Fanconi Anemia mutants as a way to identify potential therapeutics for human FA patients and to understand disease mechanisms.

MicroRNAs: The roles of microRNAs in embryonic (especially skeletal) development, including evolving miRNA functions after genome duplication.

Icefish: The genetic basis for the evolution of osteopenia or osteoporosis in Antarctic icefish.

Sex determinaion:The developmental genetic basis for sex determination in zebrafish.

Speciation: The roles of genome duplication in lineage divergence, focusing on the evolution of cis and trans acting regulation in the radiation of the danio lineage, including zebrafish, and on variation among populations of stickleback.

Oikopleura: Retaining a chordate body plan as an adult, the larvacean urochordate Oikopleura dioica represents the sister lineage to the vertebrates, diverging before the R1 and R2 rounds of genome duplication that led to the origin of vertebrate innovations.

Perchlorate toxicity and sex determination: Perchlorate is a pervasive environmental contaminant that can cause partial sex reversal in stickleback. We are investigating the hypotheses that perchlorate alters sex development through the thyroid or a non-thyroidal mechanism.

Drosophila developmental genetics: Work on Drosophila homeotic mutants, pattern formation, and ovary development.


Characterization of a Y-specific duplication/insertion of the anti-Mullerian hormone type II receptor gene based on a chromosome-scale genome assembly of yellow perch, Perca flavescens.

Mol Ecol Resour. 2020 Jan 06;:

Authors: Feron R, Zahm M, Cabau C, Klopp C, Roques C, Bouchez O, Eché C, Valière S, Donnadieu C, Haffray P, Bestin A, Morvezen R, Acloque H, Euclide PT, Wen M, Jouano E, Schartl M, Postlethwait JH, Schraidt C, Christie MR, Larson WA, Herpin A, Guiguen Y

Yellow perch, Perca flavescens, is an ecologically and economically important species native to a large portion of the northern United States and southern Canada and is also a promising candidate species for aquaculture. No yellow perch reference genome, however, has been available to facilitate improvements in both fisheries and aquaculture management practices. By combining Oxford Nanopore Technologies long-reads, 10X genomics Illumina short linked reads and a chromosome contact map produced with Hi-C, we generated a high-continuity chromosome scale yellow perch genome assembly of 877.4 Mb. It contains, in agreement with the known diploid chromosome yellow perch count, 24 chromosome-size scaffolds covering 98.8% of the complete assembly (N50 = 37.4 Mb, L50 = 11). We also provide a first characterization of the yellow perch sex determination locus that contains a male-specific duplicate of the anti-Mullerian hormone type II receptor gene (amhr2by) inserted at the proximal end of the Y chromosome (chromosome 9). Using this sex-specific information, we developed a simple PCR genotyping assay which accurately differentiates XY genetic males (amhr2by+ ) from XX genetic females (amhr2by- ). Our high-quality genome assembly is an important genomic resource for future studies on yellow perch ecology, toxicology, fisheries, and aquaculture research. In addition, the characterization of the amhr2by gene as a candidate sex determining gene in yellow perch provides a new example of the recurrent implication of the transforming growth factor beta pathway in fish sex determination, and highlights gene duplication as an important genomic mechanism for the emergence of new master sex determination genes.

PMID: 31903688 [PubMed - as supplied by publisher]