Telomeres are protein‐nucleotide sequences at the ends of chromosomes that serve to prevent the loss of genetic information during cell replication. A telomerase ribonucleoprotein complex includes telomerase reverse transcriptase (TERT) and an RNA template (TER) and is responsible for adding telomeric DNA. Our lab has been studying the biogenesis of telomerase in the fungus Aspergillus nidulans. Previous research on TER indicated secondary structural similarities to both Saccharomyces cerevisiae and mammalian cells. However, it was previously unknown whether TER migrates into the cytoplasm during the assembly of telomerase, as in S. cerevisiae, or remains in the nucleus, as in mammalian cells. We now have employed a molecular tool, the unique multi‐nucleate state of A. nidulans termed heterokaryon, to deduce whether the RNA products for TER and TERT leave the nucleus. We knocked out the genes for TER and TERT, analyzed the results of the heterokaryon test, determined whether assembly occurs in the nucleus or cytoplasm, and verified those results with DAPI staining. Our results suggest assembly in the nucleus, a scenario that is similar to humans, but not to yeast. These results further suggest the strength of A. nidulans as a model organism in studying the localization of telomerase components.

Telomeres are protein‐nucleotide sequences at the ends of chromosomes that serve to prevent the loss of genetic information during cell replication. A telomerase ribonucleoprotein complex includes telomerase reverse transcriptase (TERT) and an RNA template (TER) and is responsible for adding telomeric DNA. Our lab has been studying the biogenesis of TER in Aspergillus nidulans, a molecule that is in part structurally similar to that of Saccharomyces cerevisiae and partly to that of mammalian cells. Research in S. cerevisiae has shown that the telomerase RNA appears to leave the nucleus and is potentially assembled in the cytoplasm. Whether TER migrates to the cytoplasm is not known in A. nidulans, but its ability to form a multi‐nucleate state known as a heterokaryon can be used to determine the localization of TER. We assay for the presence of two genetically distinct nuclei via the heterokaryon test, a molecular tool that has allowed us to deduce whether the RNA products for TER and TERT leave the nucleus. We knocked out the genes for TER and TERT, analyzed the results of the heterokaryon test, and determined if assembly of the active enzyme occurs in the nucleus or the cytoplasm. Our results suggest assembly in the nucleus, a scenario that is similar to humans but not to yeast. These results further suggest the potential of A. nidulans as a useful model organism to study the localization of telomerase components.