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Tobback J.,Research Group of Insect Physiology and Molecular Ethology | Boerjan B.,Research Group of Functional Genomics and Proteomics | Vandersmissen H.P.,Research Group of Molecular Developmental Physiology and Signal Transduction | Huybrechts R.,Research Group of Insect Physiology and Molecular Ethology
Insect Biochemistry and Molecular Biology | Year: 2012

In all living organisms, behavior, metabolism and physiology are under the regulation of a circadian clock. The molecular machinery of this clock has been conserved throughout the animal kingdom. Besides regulating the circadian timing of a variety of processes through a central oscillating mechanism in the brain, these circadian clock genes were found to have a function in peripheral tissues in different insects. Here, we provide evidence that the circadian clock genes period (per) and timeless (tim) have a role in the male locust reproduction. A knockdown of either of the two genes has no effect on male sexual maturation or behavior, but progeny output in their untreated female copulation partners is affected. Indeed, the fertilization rates of the eggs are lower for females with a per or tim RNAi copulation partner as compared to the eggs deposited by females that mated with a control male. As the sperm content of the seminal vesicles is higher in per or tim knockdown males, we suggest that this phenotype could be caused by a disturbance of the circadian regulated sperm transfer in the male reproductive organs, or an insufficient maturation of the sperm after release from the testes. © 2011 Elsevier Ltd. Source


Tobback J.,Research Group of Insect Physiology and Molecular Ethology | Boerjan B.,Research Group of Functional Genomics and Proteomics | Vandersmissen H.P.,Research Group of Molecular Developmental Physiology and Signal Transduction | Huybrechts R.,Research Group of Insect Physiology and Molecular Ethology
Insect Biochemistry and Molecular Biology | Year: 2011

The circadian clocks govern many metabolic and behavioral processes in an organism. In insects, these clocks and their molecular machinery have been found to influence reproduction in many different ways. Reproductive behavior including courtship, copulation and egg deposition, is under strong influence of the daily rhythm. At the molecular level, the individual clock components also have their role in normal progress of oogenesis and spermatogenesis. In this study on the desert locust Schistocerca gregaria, three circadian clock genes were identified and their expression profiles were determined. High expression was predominantly found in reproductive tissues. Similar daily expression profiles were found for period (per) and timeless (tim), while the clock (clk) mRNA level is higher 12. h before the first per and tim peak. A knockdown of either per or tim resulted in a significant decrease in the progeny produced by dsRNA treated females confirming the role of clock genes in reproduction and providing evidence that both PER and TIM are needed in the ovaries for egg development. Since the knockdown of clk is lethal for the desert locust, its function remains yet to be elucidated. © 2011 Elsevier Ltd. Source


Boerjan B.,Research Group Functional Genomics and Proteomics | Tobback J.,Research Group of Insect Physiology and Molecular Ethology | De Loof A.,Research Group Functional Genomics and Proteomics | Schoofs L.,Research Group Functional Genomics and Proteomics | Huybrechts R.,Research Group of Insect Physiology and Molecular Ethology
Insect Biochemistry and Molecular Biology | Year: 2011

In Drosophila melanogaster, the male-specific splice isoform of the fruitless gene (Fru M) codes for a set of transcription factors that are involved in the regulation of male courtship and copulation. Fru M is expressed in an interconnected neuronal circuit containing central and sensory neurons as well as motor neurons. A partial sequence from the Schistocerca gregaria fru-gene from an EST database allowed quantitative real time analysis of fru-expression in adult locusts, and revealed the highest expression in the testes, accessory glands as well as the brain (and optic lobes). Starting fru specific RNAi knockdown in the third and fourth nymphal stage resulted in a significantly lower cumulative copulation frequency of the RNAi-treated animals compared to controls after 3 h of observation. In addition, the testes of RNAi-treated males weigh less. Analysis of the egg pods resulting from a successful copulation event revealed that egg pods from females that mated with an RNAi-treated male were smaller and contained less fertilized eggs compared to egg pods from females who mated with control males. Starting injections in the fifth nymphal stage showed the complete opposite for the cumulative copulation frequency and testes weight.We conclude that already in the early nymphal phases of male desert locusts, fruitless starts to play an important role in the regulation of successful copulation in the adult. The RNAi treatment in the male has also its effects on fertility and fecundity. It remains unknown whether this effect is coming from aberrant courtship behaviour or from an altered composition of the sperm or seminal fluids. © 2011 Elsevier Ltd. Source

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