Finding Sperm in the English Countryside—The 14th Biology of Spermatozoa Meeting
Most people wouldn't look to the rolling green hills of central England as the place to get a crash course on the latest in sperm biology. Yet, for the past quarter of a century, sperm biologists from around the world have congregated in the picturesque Peak District (near Sheffield) for Biology of Spermatozoa (BoS) Meetings - the most recent of which representing the 14th such gathering. BoS meetings are relatively small, typically consisting of 60-80 delegates, and attract a cadre of sperm enthusiasts who return year after year. As with previous meetings (e.g. Wolfner and Montgomerie 2016), the size and atmosphere of the event gives BoS meetings a special feel - part 'family' reunion, part meeting new colleagues, part solidifying and developing collaborations, and all cutting-edge science.
Spermatozoa in the Peak District
Conferences can be amixed bag. On the one hand, they are often invaluable for networking; for getting to, or staying at, the cutting edge; for getting helpful input from colleagues; for seeing friends and collaborators, old and new; and (occasionally) for getting to visit a new and exciting part of the world. Sometimes, unfortunately, scientific conferences are just too big; too expensive; too boring; too lonely, exhausting, and time consuming. Too often, delegates present old work that you already knew about, venues are hot and stuffy, and the chance of meeting old friends and making new ones is slim indeed. In September 2015, we attended a conference that epitomized all the positives (with none of the negatives) the biennialBiologyofSpermatozoa (BoS)meeting (http://www. bos.group.shef.ac.uk) in thegorgeousPeakDistrictofnorthern England. This small scientific meeting, run for the past 25 years by Tim Birkhead and Harry Moore, both at the University of Sheffield, focuses on the evolutionary biology ofspermatozoa,and reproduction ingeneral.Fourprinciples have guided the organizers from the start: (i) to keep the meeting small with no concurrent sessions; (ii) to require presenters to focus on unpublished research in progress or nearly finished; (iii) to invite 2-3 speakers from outside the core group of evolutionary biologists as a way of injecting new ideas and perspectives from other disciplines, such as physiology, imaging, proteomics/genomics; and (iv) to stay flexible, trying new approaches, replacing or modifying whateverdidnotworksowell in thepast.More thananything, this conference encourages and maximizes interaction and discussion whichmakesattending itsoproductiveand fun. To that end (and because there is only one presentation at a time) post-presentation questions and discussions are allowed to continue as long as they are interesting. Consequently, there isno rigidscheduleeachday except to finish in time for a drink before the sumptuous dinner served in an elegant dining room at the conference venue.
Integrated 3D view of postmating responses by the Drosophila melanogaster female reproductive tract, obtained by micro-computed tomography scanning
Significance Our high-resolution, multiscale micro-computed tomography scans of Drosophila provide the first 3D view, to our knowledge, of the in situ morphological changes that occur in a female insect’s reproductive tract (RT) during and after mating. By means of this holistic analysis, we determined how the postmating reproductive events of ovulation, egg movement, sperm storage, sperm release, and fertilization are coordinated. We observed and quantified phenomena not detected in prior studies of dissected materials. These phenomena included coordinated looping and unlooping of the uterus and oviducts, and a potential mating-induced trauma in the female RT. This new perspective allowed us to revisit experimentally, and newly define, the effects of male- and female-secreted molecules on female postmating physiology. Physiological changes in females during and after mating are triggered by seminal fluid components in conjunction with female-derived molecules. In insects, these changes include increased egg production, storage of sperm, and changes in muscle contraction within the reproductive tract (RT). Such postmating changes have been studied in dissected RT tissues, but understanding their coordination in vivo requires a holistic view of the tissues and their interrelationships. Here, we used high-resolution, multiscale micro-computed tomography (CT) scans to visualize and measure postmating changes in situ in the Drosophila female RT before, during, and after mating. These studies reveal previously unidentified dynamic changes in the conformation of the female RT that occur after mating. Our results also reveal how the reproductive organs temporally shift in concert within the confines of the abdomen. For example, we observed chiral loops in the uterus and in the upper common oviduct that relax and constrict throughout sperm storage and egg movement. We found that specific seminal fluid proteins or female secretions mediate some of the postmating changes in morphology. The morphological movements, in turn, can cause further changes due to the connections among organs. In addition, we observed apparent copulatory damage to the female intima, suggesting a mechanism for entry of seminal proteins, or other exogenous components, into the female’s circulatory system. The 3D reconstructions provided by high-resolution micro-CT scans reveal how male and female molecules and anatomy interface to carry out and coordinate mating-dependent changes in the female’s reproductive physiology.