Tissue remodeling: a mating-induced differentiation program for the Drosophila oviduct

<p>Abstract</p> <p>Background</p> <p>In both vertebrates and invertebrates, the oviduct is an epithelial tube surrounded by visceral muscles that serves as a conduit for gamete transport between the ovary and uterus. While <it>Drosophila </it>is a model system for tubular organ development, few studies have addressed the development of the fly's oviduct. Recent studies in <it>Drosophila </it>have identified mating-responsive genes and proteins whose levels in the oviduct are altered by mating. Since many of these molecules (e.g. Muscle LIM protein 84B, Coracle, Neuroglian) have known roles in the differentiation of muscle and epithelia of other organs, mating may trigger similar differentiation events in the oviduct. This led us to hypothesize that mating mediates the last stages of oviduct differentiation in which organ-specific specializations arise.</p> <p>Results</p> <p>Using electron- and confocal-microscopy we identified tissue-wide post-mating changes in the oviduct including differentiation of cellular junctions, remodeling of extracellular matrix, increased myofibril formation, and increased innervation. Analysis of once- and twice-mated females reveals that some mating-responsive proteins respond only to the first mating, while others respond to both matings.</p> <p>Conclusion</p> <p>We uncovered ultrastructural changes in the mated oviduct that are consistent with the roles that mating-responsive proteins play in muscle and epithelial differentiation elsewhere. This suggests that mating triggers the late differentiation of the oviduct. Furthermore, we suggest that mating-responsive proteins that respond only to the first mating are involved in the final maturation of the oviduct while proteins that remain responsive to later matings are also involved in maintenance and ongoing function of the oviduct. Taken together, our results establish the oviduct as an attractive system to address mechanisms that regulate the late stages of differentiation and maintenance of a tubular organ.</p

Long range transport of a quasi isolated chlorophyll patch by an Agulhas ring

International audienceUsing satellite retrievals of sea surface chlorophyll and geostrophic currents we study the evolution of a distinct chlorophyll patch transported by an Agulhas ring along a ˜1,500 km track. Throughout an ˜11 months period of the total 2 years eddy lifetime, the shape of the chlorophyll patch is consistently delimited by the horizontal transport barriers associated with the eddy. Analysis of Lagrangian time series of sea surface variables in and around the eddy suggests that the evolution of the chlorophyll patch is driven by two processes (i) slow lateral mixing with ambient waters mediated by horizontal stirring in filaments, and (ii) rapid events of wind induced vertical mixing. These results support the idea that mesoscale eddies shape biological production through the combination of horizontal and vertical dynamical processes, and emphasize the important role of horizontal eddy transport in sustaining biological production over the otherwise nutrient-depleted subtropical gyres

Long range transport of a quasi isolated chlorophyll patch by an agulhas ring

International audienceUsing satellite retrievals of sea surface chlorophyll and geostrophic currents we study the evolution of a distinct chlorophyll patch transported by an Agulhas ring along a ~1,500 km track. Throughout an ~11 months period of the total 2 years eddy lifetime, the shape of the chlorophyll patch is consistently delimited by the horizontal transport barriers associated with the eddy. Analysis of Lagrangian time series of sea surface variables in and around the eddy suggests that the evolution of the chlorophyll patch is driven by two processes (i) slow lateral mixing with ambient waters mediated by horizontal stirring in filaments, and (ii) rapid events of wind induced vertical mixing. These results support the idea that mesoscale eddies shape biological production through the combination of horizontal and vertical dynamical processes, and emphasize the important role of horizontal eddy transport in sustaining biological production over the otherwise nutrient-depleted subtropical gyres

Embryonic signals mediate extracellular vesicle biogenesis and trafficking at the embryo–maternal interface

Abstract Background Extracellular vesicles (EVs) are membrane-coated nanoparticles secreted by almost all cell types in living organisms. EVs, as paracrine mediators, are involved in intercellular communication, immune response, and several reproductive events, including the maintenance of pregnancy. Using a domestic animal model (Sus scrofa) with an epitheliochorial, superficial type of placentation, we focused on EV biogenesis pathway at the embryo–maternal interface, when the embryonic signaling occurs for maternal recognition and the maintenance of pregnancy. Results Transmission electron microscopy was used during early pregnancy to visualize EVs and apocrine and/or merocrine pathways of secretion. Immunofluorescent staining localized proteins responsible for EV biogenesis and cell polarization at the embryo–maternal interface. The expression profiles of genes involved in biogenesis and the secretion of EVs pointed to the possible modulation of endometrial expression by embryonic signals. Further in vitro studies showed that factors of embryonic origin can regulate the expression of the ESCRT-II complex and EV trafficking within endometrial luminal epithelial cells. Moreover, miRNA-mediated rapid negative regulation of gene expression was abolished by delivered embryonic signals. Conclusions Our findings demonstrated that embryonic signals are potent modulators of ESCRT-dependent EV-mediated secretory activity of the endometrium during the critical stages of early pregnancy. Video Abstrac

Three-dimensional correlative microscopy of the Drosophila female reproductive tract reveals modes of communication in seminal receptacle sperm storage

Abstract In many taxa, females store sperm in specialized storage organs. Most insect sperm storage organs have a tubular structure, typically consisting of a central lumen surrounded by epithelial cells. These specialized tubules perform the essential tasks of transporting sperm through the female reproductive tract and supporting long-term sperm survival and function. Little is known about the way in which female sperm storage organs provide an environment conducive to sperm survival. We address this using a combined light microscopy, micro computed tomography (microCT), and Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) approach for high-resolution correlative three-dimensional imaging to advance our understanding of sperm-female interactions in Drosophila melanogaster. Using this multimodal approach, we were able to scan the lower female reproductive tract and distal portion of the seminal receptacle at low magnification, and to subsequently zoom in for further analysis on an ultrastructural level. Our findings highlight aspects of the way in which the seminal receptacle keeps sperm viable in the lumen, and set the stage for further studies. The methods developed are suitable not only for Drosophila but also for other organisms with soft, delicate tissues

The Acp26Aa seminal fluid protein is a modulator of early egg-hatchability in Drosophila melanogaster.

Drosophila melanogaster male accessory gland proteins (Acps) that are transferred in the ejaculate with sperm mediate post–mating competition for fertilizations between males. The actions of Acps include effects on oviposition and ovulation, receptivity and sperm storage. Two Acps that modulate egg production are Acp26Aa (ovulin) and Acp70A (the sex peptide). Acp26Aa acts specifically on the process of ovulation (the release of mature eggs from the ovaries), which is initiated 1.5 h after mating. In contrast, sperm storage can take as long as 6–9 h to complete. Initial ovulations after matings by virgin females will therefore occur before all sperm are fully stored and the extra eggs initially laid as a result of Acp26Aa transfer are expected to be inefficiently fertilized. Acp26Aa–mediated release of existing eggs should not cause a significant energetic cost or lead to a decrease in female lifespan assuming, as seems likely, that the energetic cost of egg laying comes from de novo egg synthesis (oogenesis) rather than from ovulation. We tested these predictions using Acp26Aa1 mutant males that lack Acp26Aa but are normal for other Acps and Acp26Aa2 males that transfer a truncated but fully functional Acp26Aa protein. Females mating with Acp26Aa2 (truncation) males that received functional Acp26Aa produced significantly more eggs following their first matings than did mates of Acp26Aa1 (null) males. However, as predicted above, these extra eggs, which were laid as a result of Acp26Aa transfer to virgin females, showed significantly lower egg hatchability. Control experiments indicated that this lower hatchability was due to lower rates of fertilization at early post–mating times. There was no drop in egg hatchability in subsequent non–virgin matings. In addition, as predicted above, females that did or did not receive Acp26Aa did not differ in survival, lifetime fecundity or lifetime progeny, indicating that Acp26Aa transfer does not represent a significant energetic cost for females and does not contribute to the survival cost of mating. Acp26Aa appears to remove a block to oogenesis by causing the clearing out of existing mature eggs and, thus, indirectly allowing oogenesis to be initiated immediately after mating. The results show that subtle processes coordinate the stimulation of egg production and sperm storage in mating pairs

Additional file 1 of Embryonic signals mediate extracellular vesicle biogenesis and trafficking at the embryo–maternal interface

Additional file 1: Supplementary Figure 1. Control staining performed without primary antibodies. Supplementary Figure 2. mRNA expression in luminal epithelial cells. Supplementary Figure 3. Ultrastructural changes in luminal/glandular epithelium and trophectoderm on day 20 of pregnancy. Supplementary Figure 4. Overview of micrographs showing heterogeneous population of extracellular vesicles found in endometrial compartments on Day 12 and 16 of pregnancy. Supplementary Figure 5. CD63 appearance in the endocytic membrane transport pathway. Supplementary Figure 6. miRNA effect on target gene and protein abundance. Supplementary Table 1. List of primary and secondary antibodies used in immunofluorescent staining of endometrial/trophoblast tissue and luminal epithelial cells. Supplementary Table 2. List of mimics used in miRNA and hormone treatment experiment. Supplementary Table 3. List of genes and TaqMan gene expression assays used in real-time PCR

A standardized nomenclature and atlas of the female terminalia of <i>Drosophila melanogaster</i>

International audienceThe model organism Drosophila melanogaster has become a focal system for investigations of rapidly evolving genital morphology as well as the development and functions of insect reproductive structures. To follow up on a previous paper outlining unifying terminology for the structures of the male terminalia in this species, we offer here a detailed description of the female terminalia of D. melanogaster. Informative diagrams and micrographs are presented to provide a comprehensive overview of the external and internal reproductive structures of females. We propose a collection of terms and definitions to standardize the terminology associated with the female terminalia in D. melanogaster and we provide a correspondence table with the terms previously used. Unifying terminology for both males and females in this species will help to facilitate communication between various disciplines, as well as aid in synthesizing research across publications within a discipline that has historically focused principally on male features. Our efforts to refine and standardize the terminology should expand the utility of this important model system for addressing questions related to the development and evolution of animal genitalia, and morphology in general