The fruit fly, Drosophila melanogaster, has proven to be an excellent model organism for genetic, genomic and neurobiological studies. However, relatively little is known about the natural history of ...D. melanogaster. In particular, neither the natural predators faced by wild populations of D. melanogaster, nor the anti-predatory behaviors they may employ to escape and avoid their enemies have been documented. Here we observe and describe the influence of two predators that differ in their mode of hunting: zebra jumping spiders, Salticus scenicus (active hunters) and Chinese praying mantids, Tenodera sinensis (ambush predators) on the behavioral repertoire of Drosophila melanogaster. We documented three particularly interesting behaviors: abdominal lifting, stopping, and retreat-which were performed at higher frequency by D. melanogaster in the presence of predators. While mantids had only a modest influence on the locomotory activity of D. melanogaster, we observed a significant increase in the overall activity of D. melanogaster in the presence of jumping spiders. Finally, we observed considerable among-individual behavioral variation in response to both predators.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The hippocampus can be divided into distinct segments that make unique contributions to learning and memory. The dorsal segment supports cognitive processes like spatial learning and navigation while ...the ventral hippocampus regulates emotional behaviors related to fear, anxiety and reward. In the current study, we determined how pyramidal cells in ventral CA1 respond to spatial cues and aversive stimulation during a context fear conditioning task. We also examined the effects of high and low frequency stimulation of these neurons on defensive behavior. Similar to previous work in the dorsal hippocampus, we found that cells in ventral CA1 expressed high-levels of c-Fos in response to a novel spatial environment. Surprisingly, however, the number of activated neurons did not increase when the environment was paired with footshock. This was true even in the subpopulation of ventral CA1 pyramidal cells that send direct projections to the amygdala. When these cells were stimulated at high-frequencies (20 Hz) we observed feedforward inhibition of basal amygdala neurons and impaired expression of context fear. In contrast, low-frequency stimulation (4 Hz) did not inhibit principal cells in the basal amygdala and produced an increase in fear generalization. Similar results have been reported in dorsal CA1. Therefore, despite clear differences between the dorsal and ventral hippocampus, CA1 neurons in each segment appear to make similar contributions to context fear conditioning.
The phylogenetic position of the capped and golden langur (CG) lineage has been ambiguous owing to the discordance between phylogenies from multiple molecular markers. Previous molecular studies have ...hypothesised that this discordance likely arises from either a hybridization event that took place between the Indian genus
Semnopithecus
and the Southeast Asian genus
Trachypithecus
or from incomplete lineage sorting (ILS). Distinguishing between hybridization and ILS is challenging and these processes can lead to serious difficulties in inferring phylogenies. In this study, we used genetic markers (nine nuclear and eight mitochondrial) in conjunction with coalescent based species tree approach and a test for hybridization using posterior predictive checking to better understand the evolutionary origin of the CG lineage. Both the concatenated nuclear as well as the mitochondrial dataset recovered congruent relationships where CG lineage was sister to
Trachypithecus
. However, nuclear species tree estimated using different multispecies coalescent methods suggested an opposite result, i.e. CG lineage was sister to
Semnopithecus
. Hybridization analysis strongly indicates gene flow between
Semnopithecus
and
Trachypithecus
that likely gave rise to the hybrid CG lineage. Further, the CG lineage is morphologically intermediate between
Semnopithecus
and
Trachypithecus
with respect to skull and body measurements. In light of the above evidences, we argue that the CG lineage needs to be elevated to a new genus of its own. Taxonomic and conservation implications of these results are also discussed.
The cerebellum is emerging as a powerful regulator of cognitive and affective processing and memory in both humans and animals and has been implicated in affective disorders. How the cerebellum ...supports affective function remains poorly understood. The short-latency (just a few milliseconds) functional connections that were identified between the cerebellum and amygdala-a structure crucial for the processing of emotion and valence-more than four decades ago raise the exciting, yet untested, possibility that a cerebellum-amygdala pathway communicates information important for emotion. The major hurdle in rigorously testing this possibility is the lack of knowledge about the anatomy and functional connectivity of this pathway. Our initial anatomical tracing studies in mice excluded the existence of a direct monosynaptic connection between the cerebellum and amygdala. Using transneuronal tracing techniques, we have identified a novel disynaptic circuit between the cerebellar output nuclei and the basolateral amygdala. This circuit recruits the understudied intralaminar thalamus as a node. Using
optophysiology and super-resolution microscopy, we provide the first evidence for the functionality of the pathway, thus offering a missing mechanistic link between the cerebellum and amygdala. This discovery provides a connectivity blueprint between the cerebellum and a key structure of the limbic system. As such, it is the requisite first step toward obtaining new knowledge about cerebellar function in emotion, thus fundamentally advancing understanding of the neurobiology of emotion, which is perturbed in mental and autism spectrum disorders.
Standing genetic variation and the historical environment in which that variation arises (evolutionary history) are both potentially significant determinants of a population's capacity for ...evolutionary response to a changing environment. Using the open-ended digital evolution software Avida, we evaluated the relative importance of these two factors in influencing evolutionary trajectories in the face of sudden environmental change. We examined how historical exposure to predation pressures, different levels of genetic variation, and combinations of the two, affected the evolvability of anti-predator strategies and competitive abilities in the presence or absence of threats from new, invasive predator populations. We show that while standing genetic variation plays some role in determining evolutionary responses, evolutionary history has the greater influence on a population's capacity to evolve anti-predator traits, i.e. traits effective against novel predators. This adaptability likely reflects the relative ease of repurposing existing, relevant genes and traits, and the broader potential value of the generation and maintenance of adaptively flexible traits in evolving populations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Getting Started with LINCS Datasets and Tools Xie, Zhuorui; Kropiwnicki, Eryk; Wojciechowicz, Megan L. ...
Current protocols,
July 2022, 2022-Jul, 2022-07-00, 20220701, Letnik:
2, Številka:
7
Journal Article
The phylogenetic position of the capped and golden langur (CG) lineage has been ambiguous owing to the discordance between phylogenies from multiple molecular markers. Previous molecular studies have ...hypothesised that this discordance likely arises from either a hybridization event that took place between the Indian genus Semnopithecus and the Southeast Asian genus Trachypithecus or from incomplete lineage sorting (ILS). Distinguishing between hybridization and ILS is challenging and these processes can lead to serious difficulties in inferring phylogenies. In this study, we used genetic markers (nine nuclear and eight mitochondrial) in conjunction with coalescent based species tree approach and a test for hybridization using posterior predictive checking to better understand the evolutionary origin of the CG lineage. Both the concatenated nuclear as well as the mitochondrial dataset recovered congruent relationships where CG lineage was sister to Trachypithecus. However, nuclear species tree estimated using different multispecies coalescent methods suggested an opposite result, i.e. CG lineage was sister to Semnopithecus. Hybridization analysis strongly indicates gene flow between Semnopithecus and Trachypithecus that likely gave rise to the hybrid CG lineage. Further, the CG lineage is morphologically intermediate between Semnopithecus and Trachypithecus with respect to skull and body measurements. In light of the above evidences, we argue that the CG lineage needs to be elevated to a new genus of its own. Taxonomic and conservation implications of these results are also discussed.
Voltage-gated sodium ion channels (Nav) are transmembrane proteins responsible for initiating electrical signals in excitable cells. Because Nav channels play a crucial role in neuromuscular ...coordination, they are targeted by a diverse array of neurotoxins produced across the animal kingdom. Arizona bark scorpions (Centruroides sculpturatus) produce toxins that disrupt Nav channel function, causing pain, muscle paralysis and respiratory failure. Southern grasshopper mice ( Onychomys torridus) hunt bark scorpions. In response to selection by scorpion venom, grasshopper mice have evolved physiological resistance to toxins that cause pain and death. Although previous work identified modifications in one grasshopper mouse Nav channel (Nav1.8) that provide resistance to venom pain, mechanisms underlying resistance to muscle paralysis remain unknown. In skeletal muscle, Nav1.4 channels regulate muscle contraction. Previous studies showed that toxins in C. elegans and C. vittatus venoms disrupt Nav1.4 gating mechanisms. Thus, I tested the hypothesis that C. sculpturatus venom contains toxins that target Nav1.4, and that grasshopper mice are resistant to the effects of these toxins via molecular changes to their Na v1.4. Using molecular and electrophysiological analyses, I compared the structural and functional properties of grasshopper mice Na v1.4 channels to those of house mice and rats (rodents that are both sensitive to scorpion venom) and found that grasshopper mice Nav1.4 has evolved reduced sensitivity to C. sculpturatus venom. Further, I identified amino acid changes in the grasshopper mice Nav 1.4 protein that contribute to reduced toxin sensitivity. Finally, I show that the beta subunits (accessory proteins that modulate Nav1.4 channel gating kinetics) of grasshopper mice do not have species-specific effects on channel function in the presence or absence of venom. My results demonstrate that highly conserved proteins can be evolutionarily modified with minimal effects to their baseline functional properties.
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