Neuromodulation and differential learning in mosquitoes with various host preferences
By: Dr. Gabriella Wolff (Riffell Lab)
Mosquito host preferences vary widely across species from human and other mammalian hosts to reptiles, birds. Some species do not blood-feed at all. Disease-vector mosquitoes have a significant impact on global ecosystems, epidemiology, and economies by their impact on human health and welfare, yet little is known about why they preferentially feed on humans and certain subpopulations in particular. One factor may be that mosquitoes can learn and remember sensory information such as chemical odors associated with the best (and worst) hosts. This learning and memory is heavily modulated by dopamine and serotonin. In order to understand why mosquitoes seek to bite their preferred hosts, we are comparing odor receptivity, ability to form associative olfactory memories of these odors, and expression patterns of dopamine and serotonin in olfactory brain centers across species. Results indicate a heterogeneity of neuromodulator expression in the antennal lobes which may have a relationship with differential ability to encode olfactory memories that are likely involved in host preference behaviors.
The evolution of savannas in Africa during the past 50 million years: new perspectives from micro-botanical (phytolith) analyses
By: Dr. Alice Novello (Strömberg lab)
Today, the savanna biome occupies ~50% of Africa’s land surface, and is associated with many mammal species specifically adapted to life in the savanna environment. My project aims to document the appearance and expansion of savannas in Africa’s geologic past, and to evaluate their relationship with the evolution of modern mammals during the last 50 million years. Precisely, it will assess grass evolution and savanna history in East Africa via phytoliths, microscopic particles of amorphous hydrated silica produced in plant tissues and conserved in paleosols and sediments after plants die and decay. Phytoliths are the best plant remain to document grasses in the paleo-records so far. A unique aspect of this study is that it will apply phytolith analyses for the first time to document paleoenvironments older than ~8 Ma in Africa, and to bring the great potential of phytoliths to bear on the question of savanna origins in Africa.
Macrophage relay for long-distance signaling during post embryonic tissue remodeling
By: Dr. Dae Seok Eom (Parichy Lab)
Macrophages have diverse functions in immunity as well as development and homeostasis. Here we identify a function for these cells in long distance communication during postembryonic tissue remodeling. Ablation of macrophages in zebrafish prevented melanophores from coalescing into adult pigment stripes. Melanophore organization depends on signals provided by cells of the yellow xanthophore lineage via airinemes, long filamentous projections with vesicles at their tips. We show that airineme extension from originating cells, and vesicle deposition on target cells, depend on interactions with macrophages. These findings identify a role for macrophages in relaying long range signals between nonimmune cells. It will be interesting to see if this signaling modality functions in the remodeling and homeostasis of other tissues during normal development and disease.
The chemical diversity of Piper scents
By: Dr. Ada Kaliszewska (Santana Lab)
Chemical signals are key mediators of many ecological interactions, and are important for fruit localization and selection by frugivores. Piper plants exhibit mutualistic interactions with bats in the Neotropical portion of their range. To study how Piper use scents attract bats to ripe fruits we quantified the chemical composition of scents produced by ripe fruits, unripe fruits and vegetation of 26 species of Neotropical Piper using dynamic headspace adsorption and gas chromatography-mass spectrometry techniques. We found that the fruits of most Piper species have distinct signatures defined by their most abundant volatile organic chemicals. These include sesquiterpenes and monoterpene hydrocarbons such as cubebene, caryophyllene and safrole, some of which are involved in diverse ecological processes such as pollination, herbivory and frugivory in other systems. The scents of ripe fruit, unripe fruit and vegetation are more similar within than among Piper species. However, scent bouquets of each plant part are also distinct.