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L Crittenden

Publications and source records attributed to L Crittenden.

4 recordsLinked to original sources
PubMed1999

Evaluation of Japanese quail as a model system for avian transgenesis using avian leukosis viruses.

Vertical transmission of avian leukosis viruses (ALV) can occur genetically through the germline for both male and female chickens but only nongenetically or congenitally through the female. We had previously shown that tolerantly ALV-infected males, from ALV injection into fertile chicken eggs at day of set, can transmit proviral DNA to their progeny through the germline. An attempt was made to repeat this successful retroviral germline insertion technique of chickens in Japanese quail. After an initial difficulty of infecting quail chicks in ovo at day of set with high titer nonpathogenic recombinant and pathogenic ALV, adequate numbers of tolerantly ALV-infected quail were produced by injecting ALV-infected chicken embryo fibroblasts (CEF) at day of set. Tolerantly ALV-infected male and female quail were then mated to nonviremic quail and vertical transmission of ALV to progeny chicks was determined by analyzing blood for viral antigens and proviral DNA using standard techniques. Vertical transmission of ALV was only detected in the progeny of viremic females. Thus, little or no germline transmission of ALV to progeny occurred from viremic males. Tolerantly ALV-infected males and females from congenital ALV infection, which should infect the embryo and presumably the primordial germ cells (PGC) earlier than egg injection, were mated to nonviremic quails. Vertical transmission of ALV to progeny chicks was analyzed as before. Again, vertical transmission of ALV was only detected in the progeny of viremic females. We conclude that Japanese quail will not be useful in avian transgenic studies involving ALV retroviral vectors.

Animals↗
PubMed1997

Avian leukemias and lymphomas: interplay between retroviruses and herpesviruses.

Avian leukemias and lymphomas are caused primarily by retroviruses and herpesviruses. The protooncogenes activated by avian retroviral insertions in B & T-cell lymphomas will be summarized, with discussion on a new common insertion site, bravo, associated with RAV-O LTR insertion. Two novel interactions between avian retroviruses and Marek's disease herpesvirus (MDV) will be described: one involves direct interactions between putative viral oncoproteins and the other integrative recombination between these two viruses.

Alpharetrovirus↗
PubMed1988

Mechanism of c-erbB transduction: newly released transducing viruses retain poly(A) tracts of erbB transcripts and encode C-terminally intact erbB proteins.

We have previously shown that avian leukosis virus (ALV) induces erythroblastosis by insertional activation of the c-erbB gene. In 25% of the ALV-induced leukemic samples we have analyzed, acute retroviruses that have captured the activated erbB oncogene were released. The unusually high frequency at which erbB transduction occurs makes this an ideal system for studying the mechanism of oncogene transduction. In addition, these leukemic samples provide a rich source for the isolation of novel erbB-transducing viruses. We report here our characterization of several new erbB-transducing proviruses. The 5' recombination points of all these viruses mapped to the same intron in which proviral insertions cluster, supporting the hypothesis that transduction begins with proviral insertion near the oncogene. The 3' recombination points usually occurred within the 3' untranslated region downstream from the termination codon of the c-erbB gene. Three of the erbB-containing proviruses were molecularly cloned and analyzed in detail. Two of them were capable of releasing acute viruses, and interestingly, both retained poly(A) tracts of erbB messages in their genomes. A stretch of six adenosine residues in the ALV env gene appeared to mediate the 3' recombination events required for the generation of these viruses. These data provide further insight into the mechanism by which oncogenes are transduced into retroviral genomes.

Animals↗