Proteases and protease inhibitors have been identified in the ejaculates of animal taxa ranging from invertebrates to mammals and form a major protein class among Drosophila melanogaster seminal ...fluid proteins (SFPs). Other than a single protease cascade in mammals that regulates seminal clot liquefaction, no proteolytic cascades (i.e. pathways with at least two proteases acting in sequence) have been identified in seminal fluids. In Drosophila, SFPs are transferred to females during mating and, together with sperm, are necessary for the many post-mating responses elicited in females. Though several SFPs are proteolytically cleaved either during or after mating, virtually nothing is known about the proteases involved in these cleavage events or the physiological consequences of proteolytic activity in the seminal fluid on the female. Here, we present evidence that a protease cascade acts in the seminal fluid of Drosophila during and after mating. Using RNAi to knock down expression of the SFP CG10586, a predicted serine protease, we show that it acts upstream of the SFP CG11864, a predicted astacin protease, to process SFPs involved in ovulation and sperm entry into storage. We also show that knockdown of CG10586 leads to lower levels of egg laying, higher rates of sexual receptivity to subsequent males, and abnormal sperm usage patterns, processes that are independent of CG11864. The long-term phenotypes of females mated to CG10586 knockdown males are similar to those of females that fail to store sex peptide, an important elicitor of long-term post-mating responses, and indicate a role for CG10586 in regulating sex peptide. These results point to an important role for proteolysis among insect SFPs and suggest that protease cascades may be a mechanism for precise temporal regulation of multiple post-mating responses in females.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Seminal fluid proteins (SFPs) produced in reproductive tract tissues of male insects and transferred to females during mating induce numerous physiological and behavioral postmating changes in ...females. These changes include decreasing receptivity to remating; affecting sperm storage parameters; increasing egg production; and modulating sperm competition, feeding behaviors, and mating plug formation. In addition, SFPs also have antimicrobial functions and induce expression of antimicrobial peptides in at least some insects. Here, we review recent identification of insect SFPs and discuss the multiple roles these proteins play in the postmating processes of female insects.
Females and males of sexually reproducing animals must cooperate at the molecular and cellular level for fertilization to succeed, even though some aspects of reproductive molecular biology appear to ...involve antagonistic interactions. We previously reported the existence of a proteolytic cascade in Drosophila melanogaster seminal fluid that is initiated in the male and ends in the female. This proteolytic cascade, which processes at least two seminal fluid proteins (Sfps), is a useful model for understanding the regulation of Sfp activities, including proteolysis cascades in mammals. Here, we investigated the activation mechanism of the downstream protease in the cascade, the astacin-family metalloprotease Seminal metalloprotease-1 (Semp1, CG11864), focusing on the relative contribution of the male and female to its activation. We identified a naturally occurring semp1 null mutation within the Drosophila Genetic Reference Panel. By expressing mutant forms of Semp1 in males homozygous for the null mutation, we discovered that cleavage is required for the complete activation of Semp1, and we defined at least two sites that are essential for this activational cleavage. These amino acid residues suggest a two-step mechanism for Semp1 activation, involving the action of at least two male-derived proteases. Although the cascade's substrates potentially influence both fertility and sperm competition within the mated female, the role of female factors in the activation or activity of Semp1 is unknown. We show here that Semp1 can undergo its activational cleavage in male ejaculates, without female contributions, but that cleavage of Semp1's substrates does not proceed to completion in ejaculates, indicating an essential role for female factors in Semp1's full activity. In addition, we find that expression of Semp1 in virgin females demonstrates that females can activate this protease on their own, resulting in activity that is complete but substantially delayed.
Whether low-density lipoprotein (LDL) receptor (LDLR) residual activity influences the LDL-lowering effect of statins in heterozygous familial hypercholesterolemia (HeFH) remains unclear. The ...objective of this study was to investigate the relationship between the LDLR genotype and statin-induced LDL cholesterol (LDL-C) reductions in HeFH.
A total of 615 individuals with HeFH (receptor-defective RD genotype: n = 226; receptor-negative RN genotype: n = 389) from 7 lipid clinics across Canada who initiated statin monotherapy were included in this retrospective longitudinal study. Statin-induced reductions in LDL-C among individuals with RD and RN genotypes were compared with the use of linear models.
There were 334 women and 281 men with a mean untreated LDL-C concentrations of 6.97 ± 1.65 mmol/L. Untreated and on-statin LDL-C levels where higher among patients with an RN genotype: untreated: RN 7.24 (95% confidence interval CI 6.98-7.50) mmol/L vs RD 6.70 (95% CI 6.41-6.98) mmol/L (P = 0.0002); on-statin: RN 4.50 (95% CI 4.31-4.70) vs RD 4.05 (95% CI 3.84-4.26) mmol/L (P = 0.0004). After adjustments for age, sex, smoking status, untreated LDL-C concentrations, statin type and dose, as well as the clinic where the patients were treated, the LDL-C–lowering effect of statins was significantly weaker for individuals with an RN mutation than for individuals with an RD mutation: RN: −31.1% (95% CI −34.7% to −27.4) vs RD −36.5% (95% CI −40.4% to −32.6%); P < 0.0001. The LDLR genotype was the strongest nonmodifiable independent correlate of statin-induced LDL-C reductions (R2 = 2.3%; P = 0.0001).
The LDLR genotype is significantly associated with statin-induced reductions in LDL-C concentrations in HeFH.
On ne sait toujours pas si l'activité résiduelle du récepteur (R-LDL) des lipoprotéines de basse densité (LDL) influence l'effet hypolipidémiant des statines dans l'hypercholestérolémie familiale hétérozygote (HFHe). L'objectif de cette étude était d'examiner la relation entre le génotype R-LDL et les réductions du LDL-cholestérol (LDL-C) induites par les statines dans l'HFHe.
Un total de 615 personnes atteintes d'HFHe (génotype récepteur-déficient RD : n = 226; génotype récepteur-négatif RN : n = 389) provenant de sept cliniques de maladies lipidiques à travers le Canada et ayant commencé une monothérapie par statine ont été incluses dans cette étude longitudinale rétrospective. Les réductions du LDL-C induites par les statines chez les personnes de génotype RD et RN ont été comparées à l'aide de modèles linéaires.
Étaient inclus 334 femmes et 281 hommes avec une concentration moyenne de LDL-C non traité de 6,97 ± 1,65 mmol/l. Les taux de LDL-C pré-statine et sous traitement par statines étaient plus élevés chez les patients présentant un génotype RN : pré-statine : RN 7,24 (intervalle de confiance IC à 95 % 6,98-7,50) mmol/l vs RD 6,70 (IC à 95 % 6,41-6,98) mmol/l (P = 0,0002); sous statine : RN 4,50 (IC à 95 % 4,31-4,70) vs RD 4,05 (IC à 95 % 3,84-4,26) mmol/l (P = 0,0004). Après ajustement pour tenir compte de l'âge, du sexe, du tabagisme, des concentrations de LDL-C non traité, du type et de la dose de statine, ainsi que de la clinique où les patients étaient traités, l'effet des statines sur la réduction du LDL-C était significativement plus faible chez les personnes présentant une mutation RN que chez celles présentant une mutation RD : pour le groupe RN : 31,1 % (IC à 95 % –34,7 % à –27,4 %) vs RD 36,5 % (IC à 95 % –40,4 % à –32,6 %); P < 0,0001. Le génotype R-LDL représentait le facteur non modifiable le plus fortement corrélé avec les réductions du LDL-C induites par les statines (R2 = 2,3 %; P = 0,0001).
Le génotype R-LDL est associé de manière significative aux réductions des concentrations de LDL-C induites par les statines dans l'HFHe.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
The genetic basis of postzygotic isolation is a central puzzle in evolutionary biology. Evolutionary forces causing hybrid sterility or inviability act on the responsible genes while they still are ...polymorphic, thus we have to study these traits as they arise, before isolation is complete.
Isofemale strains of D. mojavensis vary significantly in their production of sterile F(1) sons when females are crossed to D. arizonae males. We took advantage of the intraspecific polymorphism, in a novel design, to perform quantitative trait locus (QTL) mapping analyses directly on F(1) hybrid male sterility itself. We found that the genetic architecture of the polymorphism for hybrid male sterility (HMS) in the F(1) is complex, involving multiple QTL, epistasis, and cytoplasmic effects.
The role of extensive intraspecific polymorphism, multiple QTL, and epistatic interactions in HMS in this young species pair shows that HMS is arising as a complex trait in this system. Directional selection alone would be unlikely to maintain polymorphism at multiple loci, thus we hypothesize that directional selection is unlikely to be the only evolutionary force influencing postzygotic isolation.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Fruit-flies of the genus
Drosophila are characterized by overwhelming variation in fertilization traits such as copulatory plug formation, sperm storage organ use, and nutritional ejaculatory ...donation. Despite extensive research on the genetic model
Drosophila melanogaster, little is known about the molecular underpinnings of these interspecific differences. This study employs a proteomic approach to pin-point candidate seminal fluid proteins in
Drosophila mojavensis, a cactophilic fruit-fly that exhibits divergent reproductive biology when compared to
D. melanogaster. We identify several classes of candidate seminal fluid proteins not previously documented in the
D. melanogaster male ejaculate, including metabolic enzymes, nutrient transport proteins, and clotting factors. Conversely, we also define 29 SFPs that are conserved despite >40 million years of
Drosophila evolution. We discuss our results in terms of universal processes in insect reproduction, as well as the specialized reproductive biology of
D. mojavensis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
Studies of social behavior generally focus on interactions between two or more individual animals. However, these interactions are not simply between whole animals, but also occur between molecules ...that were produced by the interacting individuals. Such "molecular social interactions" can both influence and be influenced by the organismal-level social interactions. We illustrate this by reviewing the roles played by seminal fluid proteins (Sfps) in molecular social interactions between males and females of the fruit fly Drosophila melanogaster. Sfps, which are produced by males and transferred to females during mating, are involved in inherently social interactions with female-derived molecules, and they influence social interactions between males and females and between a female's past and potential future mates. Here, we explore four examples of molecular social interactions involving D. melanogaster Sfps: processes that influence mating, sperm storage, ovulation, and ejaculate transfer. We consider the molecular and organismal players involved in each interaction and the consequences of their interplay for the reproductive success of both sexes. We conclude with a discussion of the ways in which Sfps can both shape and be shaped by (in an evolutionary sense) the molecular social interactions in which they are involved.
Predicting functional gene annotations remains a significant challenge, even in well-annotated genomes such as yeast and Drosophila. One promising, high-throughput method for gene annotation is to ...use correlated gene expression patterns to annotate target genes based on the known function of focal genes. The Drosophila melanogaster transcriptome varies genetically among wild-derived inbred lines, with strong genetic correlations among the transcripts. Here, we leveraged the genetic correlations in gene expression among known seminal fluid protein (SFP) genes and the rest of the genetically varying transcriptome to identify 176 novel candidate SFPs (cSFPs). We independently validated the correlation in gene expression between seven of the cSFPs and a known SFP gene, as well as expression in male reproductive tissues. We argue that this method can be extended to other systems for which information on genetic variation in gene expression is available.
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