Evolutionary Rate Covariation Identifies New Members of a Protein Network Required for Drosophila melanogaster Female Post-Mating Responses

Seminal fluid proteins transferred from males to females during copulation are required for full fertility and can exert dramatic effects on female physiology and behavior. In Drosophila melanogaster, the seminal protein sex peptide (SP) affects mated females by increasing egg production and decreasing receptivity to courtship. These behavioral changes persist for several days because SP binds to sperm that are stored in the female. SP is then gradually released, allowing it to interact with its female-expressed receptor. The binding of SP to sperm requires five additional seminal proteins, which act together in a network. Hundreds of uncharacterized male and female proteins have been identified in this species, but individually screening each protein for network function would present a logistical challenge. To prioritize the screening of these proteins for involvement in the SP network, we used a comparative genomic method to identify candidate proteins whose evolutionary rates across the Drosophila phylogeny co-vary with those of the SP network proteins. Subsequent functional testing of 18 co-varying candidates by RNA interference identified three male seminal proteins and three female reproductive tract proteins that are each required for the long-term persistence of SP responses in females. Molecular genetic analysis showed the three new male proteins are required for the transfer of other network proteins to females and for SP to become bound to sperm that are stored in mated females. The three female proteins, in contrast, act downstream of SP binding and sperm storage. These findings expand the number of seminal proteins required for SP's actions in the female and show that multiple female proteins are necessary for the SP response. Furthermore, our functional analyses demonstrate that evolutionary rate covariation is a valuable predictive tool for identifying candidate members of interacting protein networks. © 2014 Findlay et al

Neurokinin B and pre-eclampsia: a decade of discovery

ABSTRACT: At the start of the last decade, we provided evidence that levels of the peptide neurokinin B were highly elevated in pre-eclampsia. We hypothesized that elevated levels of neurokinin B may be an indicator of pre-eclampsia and that treatment with certain neurokinin receptor antagonists may be useful in alleviating the symptoms. At the time of the original hypothesis many questions remained outstanding. These included - Does neurokinin B have any diagnostic value in the detection and diagnosis of pre-eclampsia? - What is the cause of the elevated levels of neurokinin B during pre-eclampsia? - What is the physiological significance of neurokinin B in the placenta? This review discusses the answers to these questions taking into account the subsequent developments of the past ten years and analyzing the plethora of discoveries that have arisen from those initial observations

Tachykinin Family Genes and their Receptors are Differentially Expressed in the Hypothyroid Ovary and Pituitary

Plasma tachykinin levels are known to be altered with sexual acyclicity and loss of reproductive function. Ovulatory dysfunction, as seen in postmenopausal women, is also often encountered in hypothyroid patients. To know the involvement of different tachykinin genes in hypothyroidism-associated reproductive disorders, we performed DD-PCR with the pituitary RNA of control and hypothyroid rats to see the differentially expressed gene profile. Subsequently, we selected a few clones, tachykinin being one of them. Since its expression was up regulated in hypothyroidism as it does in the sexually acyclic females, we wanted to correlate these two phenomena with hypothyroidism associated reproductive disorders. We observed differential expression of tac2 along with other tk genes and their receptors in rat pituitary and ovary, which suggests that hypothyroidism affects the expression of these genes in these tissues. The experiments were repeated in ovarian tissue obtained at surgery from hypothyroid human patients, which showed similar expression pattern of TAC3 (equivalent to rat tac2) and their receptors as in rat ovary. Significant reduction of tac2 expression in reproductively less active rat ovary suggests the association of tac2 with reproductive senescence. Our results suggest that decline in reproductive function in hypothyroidism is associated with altered expression level of tac2 and its receptors. Further investigation in this area could elucidate the possible mechanism of tachykinins’ involvement in loss of sexual cyclicity and other reproductive disorders associated with hypothyroidism