Evolution of yolk protein genes in the Echinodermata

2012 ◽  
Vol 14 (2) ◽  
pp. 139-151 ◽  
Author(s):  
Thomas A. A. Prowse ◽  
Maria Byrne
Keyword(s):  
Yolk Protein ◽  
Yolk Protein Genes

VIEWPOINT. An hypothesis to explain the linkage between kakapo (Strigops habroptilus) breeding and the mast fruiting of their food trees

2008 ◽  
Vol 35 (1) ◽  
pp. 1 ◽  
Author(s):  
Andrew E. Fidler ◽  
Stephen B. Lawrence ◽  
Kenneth P. McNatty
Keyword(s):  
Egg Yolk ◽  
Ovarian Follicles ◽  
Yolk Protein ◽  
Egg Laying ◽  
Food Plants ◽  
Mast Seeding ◽  
Future Research ◽  
Yolk Protein Genes ◽  
Hypothetical Mechanism ◽  
Future Research Directions

An important goal in the intensive conservation management of New Zealand’s critically endangered nocturnal parrot, kakapo (Strigops habroptilus), is to increase the frequency of breeding attempts. Kakapo breeding does not occur annually but rather correlates with 3–5-year cycles in ‘mast’ seeding/fruiting of kakapo food plants, most notably podocarps such as rimu (Dacrydium cupressinum). Here we advance a hypothetical mechanism for the linking of kakapo breeding with such ‘mast’ seeding/fruiting. The essence of the hypothesis is that exposure to low levels of dietary phytochemicals may, in combination with hepatic gene ‘memory’, sensitise egg yolk protein genes, expressed in female kakapo livers, to oestrogens derived from developing ovarian follicles. Only in those years when the egg yolk protein genes have been sufficiently ‘pre-sensitised’ by dietary chemicals do kakapo ovarian follicles develop to ovulation and egg-laying occurs. While speculative, this hypothesis is both physiologically and evolutionarily plausible and suggests both future research directions and relatively simple interventions that may afford conservation workers some influence over kakapo breeding frequency.

The use of an inhibitor of protein synthesis to investigate the roles of ecdysteroids and sex-determination genes on the expression of the genes encoding the Drosophila yolk proteins

Development ◽  
1987 ◽  
Vol 101 (4) ◽  
pp. 931-941
Author(s):  
M. Bownes ◽  
A. Scott ◽  
M. Blair
Keyword(s):  
Protein Synthesis ◽  
Sex Determination ◽  
Fat Body ◽  
Yolk Protein ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Yolk Protein Genes ◽  
Fat Bodies ◽  
Inhibitor Of Protein Synthesis

The three yolk-protein genes of Drosophila are normally expressed only in adult female fat bodies and ovaries. 20-hydroxyecdysone can affect the transcription of these genes in males and females, as can mutations in the sex-determining genes tra, tra-2, ix and dsx. We have asked a number of basic questions about how these genes are regulated, using an inhibitor of protein synthesis (cycloheximide), labelling RNA in vivo, a temperature-sensitive sex-determination mutant (tra-2ts1), and 20-hydroxyecdysone. We have found that the yolk-protein genes are continuously transcribed in the fat bodies of adult females and that maintenance of this transcription requires protein synthesis. Hormone induction in males is also inhibited by cycloheximide, suggesting that the products of other genes are essential both for 20-hydroxyecdysone to be able to switch on the genes, and for their continuous transcription in the female fat body. The products of the tra-2 gene are also required for continuous transcription of the yolk-protein genes, suggesting that the pathway inhibited by the cycloheximide is that of the sex-determination hierarchy. 20-hydroxyecdysone can override the sex-determination system and induce yolk protein synthesis in normal males and tra-2ts reared and maintained at the restrictive temperature.

scholarly journals Regulation of Drosophila yolk protein genes by an ovary-specific GATA factor.

1995 ◽  
Vol 15 (12) ◽  
pp. 6943-6952 ◽  
Author(s):  
M Lossky ◽  
P C Wensink
Keyword(s):  
Fat Body ◽  
Regulatory Element ◽  
Ovarian Follicle ◽  
In Vitro Transcription ◽  
Yolk Protein ◽  
Follicle Cells ◽  
Gata Factor ◽  
Yolk Protein Genes

The divergently transcribed yolk protein genes (Yp1 and Yp2) of Drosophila melanogaster are expressed only in adult females, in fat body tissue and in ovarian follicle cells. Using an in vitro transcription assay, we have identified a single 12-bp DNA element that activates transcription from the promoters of both Yp genes. In vivo, this regulatory element is tissue specific: it activates transcription of Yp1 and Yp2 reporter genes in follicle cells but has no detectable effect in fat body or other tissues. The sequence of the element consists of two recognition sites for the GATA family of transcription factors. We show that among the Drosophila genes known to encode GATA factors, only dGATAb is expressed in ovaries. The single transcript that we detect in ovaries is alternatively spliced or initiated to produce an ovary-specific isoform of the protein. Bacterially expressed dGATAb binds to the 12-bp element; a similar binding activity is also present in the Kc0 nuclear extracts used for in vitro transcription assays. These in vitro and in vivo results lead us to propose that dGATAb makes several developmentally regulated products, one of which is a follicle cell-specific protein activating transcription of Yp1 and Yp2 from a known regulatory element.

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