NIH Postbac Poster Day is a time for our early career trainees to share their research projects with the NIH community. Each year, NICHD postdoctoral fellows select the top three posters, based on the postbac’s knowledge of the lab’s research, ability to describe the project, and poster design and layout. With the large amount of talent in our postbac population, it’s never an easy decision! This year, our three NICHD postbac winners include:
- Alessandro Albano (Delaney lab)
- Marci Rosenberg (Chitnis lab)
- Lauren Wooddell (Suomi lab)
To honor this achievement, The NICHD Connection invited the winning postbacs to submit a synopsis of their research. Read below to learn more about their award-winning studies.
Isolated GnRH Deficiency, a Problem with Puberty
By Alessandro Albano
Isolated Gonadotropin-Releasing Hormone (GnRH) Deficiency (IGD) is a family of rare disorders with a population frequency of about 1 in 50,000 individuals. In the brain, GnRH-expressing neurons control the release of several reproductive hormones from the pituitary, but this activity is completely or partially absent with IGD. Without treatment, these individuals have incomplete or absent puberty.
Researchers have already identified 37 pathogenic rare sequence variants (RSVs) in the DNA of patients with IGD. Most of the genes can be divided into two groups: neurodevelopmental genes and neuroendocrine genes.
Mutations in the neurodevelopmental genes affect GnRH neuron development and migration, which causes the Kallmann Syndrome (KS) form of IGD. Because the GnRH neurons develop within the olfactory bulbs, KS patients have absent or a decreased sense of smell. In contrast, mutations in neuroendocrine genes that affect the secretion or action of GnRH typically lead to a form of IGD called Normosmic Idiopathic Hypogonadotropic Hypogonadism. Like its name suggests, individuals with this form have a normal sense of smell.
IGD gene discovery has increased rapidly with the availability of Next Gen Sequencing, and we are using Exome Sequencing to identify RSVs in the known IGD genes in patients enrolled in our genetic study of GnRH-deficient individuals. We filtered the very large number of variants found in the exome data of our patients to determine which of the 37 genes linked to IGD were significant, and we sent those for confirmation by Sanger sequencing. We are also actively using the exome data with other genetic analyses to look for novel genes that may cause these disorders when mutated.
Characterizing a Cellular Collision
By Marci Rosenberg
In a period of a mere 24 hours, zebrafish embryos go from a single cell to something remarkably fish-like. During this stretch of rapid development, cells are engaging in all sorts of interesting behaviors, from division to deformation to migration, and ultimately forming tissues with unique shapes and structures. Of particular interest to our lab is a sensory system that is exclusive to aquatic organisms, called the lateral line. In the process of forming the lateral line system, a collection of about 100 cells, known as the posterior lateral line primordium (PLLp), migrates under the skin from head to tail down the trunk of the zebrafish during the second day of development. As it chugs along, the PLLp deposits sensory organs, called neuromasts. These neuromasts help the animal sense water movement over their body surface.
Recent work from our lab has revealed that cells of the PLLp dynamically interact with the overlying skin, which at this stage has two layers, an external layer with periderm cells, and an internal layer with basal cells. How the PLLp and overlying cells interact and what the significance of such interactions is were not known. By taking time-lapses of transgenic zebrafish with fluorescently labeled basal and PLLp cells with a confocal microscope, I visualized how overlying cells responded to passage of the underlying PLLp. In addition, I characterized how these interactions might be altered following various pharmacological and molecular perturbations.
We found that basal skin cells, and not the periderm, are in direct contact with the dorsal side of the migrating PLLp. Most intriguingly, as the PLLp tunnels underneath these stationary basal cells, the skin cells do not take this assault quietly; instead, they respond with an explosion of filopodial protrusions. Even when challenged with a barrage of perturbations in signaling systems known to be of importance in PLLp development and actin cytoskeleton remodeling, these filopodial protrusions have remained remarkably persistent. Thus far, the only manipulation we’ve found to quiet this behavior is a complete stalling of the PLLp’s migration. Going forward, we intend to determine if the response of the basal cells helps protect them and/or if it contributes to effective passage of the PLLp.
Who’s that? Facial preferences in tufted capuchins
By Lauren Wooddell
People are attracted to symmetrical faces. We find them attractive because they potentially indicate developmental stability and health; we should therefore select symmetrical individuals as sexual partners to ensure offspring survival. What about other animals? If there is an evolutionary advantage to symmetry, then they too should find facial symmetry attractive. We sought to investigate this by studying tufted capuchin monkeys, which display both female and male mate choice.
In our study, we displayed images of humans, capuchins, and sheep to tufted capuchins. Each individual stimulus had two components: a perfectly symmetrical version and the original, slightly asymmetrical version. We then examined how long the monkeys looked at each image, with the hypothesis that male capuchins should look longer at symmetrical female capuchins, and female capuchins should look longer at male symmetrical capuchins. We predicted no preferences for symmetrical human or sheep faces since these stimuli are not relevant to reproductive success.
Surprisingly, we found that female monkeys had no preference for symmetry in any species. Male monkeys only oriented towards the symmetrical faces for other male capuchins. How do we explain these findings?
Overall males were more vigilant and displayed threatening gestures to other male capuchins compared to any other species. Previous studies have shown that in macaques, symmetry relates to canine size and fighting abilities. We therefore speculate that male monkeys were orienting towards the male capuchins to assess their competitive ability, and facial symmetry may be an important indicator of body condition in male-male competition. As for the females, none were ovulating during the study, and preference for symmetry peaks during ovulation in humans.
Our research indicates that facial symmetry may be an important indicator of intrasexual selection, in addition to the previously studied intersexual selection. Facial symmetry may be attractive, but it can also be intimidating.