Expression of the pupal determinant broad during metamorphic and neotenic development of the strepsipteran Xenos vesparum Rossi.
Derived members of the endoparasitic order Strepsiptera have acquired an extreme form of sexual dimorphism whereby males undergo metamorphosis and exist as free-living adults while females remain larviform, reaching sexual maturity within their hosts. Expression of the transcription factor, broad (br) has been shown to be required for pupal development in insects in which both sexes progress through metamorphosis. A surge of br expression appears in the last larval instar, as the epidermis begins pupal development. Here we ask if br is also up-regulated in the last larval instar of male Xenos vesparum Rossi (Stylopidae), and whether such expression is lost in neotenic larviform females. We clone three isoforms of br from X. vesparum (Xv'br), and show that they share greatest similarity to the Z1, Z3 and Z4 isoforms of other insect species. By monitoring Xv'br expression throughout development, we detect elevated levels of total br expression and the Xv'Z1, Xv'Z3, and Xv'Z4 isoforms in the last larval instar of males, but not females. By focusing on Xv'br expression in individual samples, we show that the levels of Xv'BTB and Xv'Z3 in the last larval instar of males are bimodal, with some males expressing 3X greater levels of Xv'br than fourth instar femlaes. Taken together, these data suggest that neoteny (and endoparasitism) in females of Strepsiptera Stylopidia could be linked to the suppression of pupal determination. Our work identifies a difference in metamorphic gene expression that is associated with neoteny, and thus provides insights into the relationship between metamorphic and neotenic development.
Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America.
Deniz F
DF
Erezyilmaz
Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala Biomedical Centre, Uppsala, Sweden.
Alex
A
Hayward
Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America.
Yan
Y
Huang
Department of Zoology, University of Oxford, Oxford, United Kingdom.
Jordi
J
Paps
Kaposvar University, Faculty of Animal Science, Kaposvar, Hungary.
Zoltan
Z
Acs
Departamento de Zoologia, Facultad de Biologia, Universidad de Murcia, Murcia, Spain.
Juan A
JA
Delgado
Departamento de Zoologia, Facultad de Biologia, Universidad de Murcia, Murcia, Spain.
Francisco
F
Collantes
Department of Zoology, University of Oxford, Oxford, United Kingdom.
Jeyaraney
J
Kathirithamby
D000818:Animals; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D019476:Insect Proteins / Q000096:biosynthesis* / Q000235:genetics; D007313:Insecta / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008675:Metamorphosis, Biological / Q000502:physiology*; D011679:Pupa / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics
D019476:Insect Proteins; D014157:Transcription Factors