Publications by authors named "Elena Ian"

9 Publications

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Distinct protocerebral neuropils associated with attractive and aversive female-produced odorants in the male moth brain.

Elife 2021 May 14;10. Epub 2021 May 14.

Chemosensory lab, Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway.

The pheromone system of heliothine moths is an optimal model for studying principles underlying higher-order olfactory processing. In , three male-specific glomeruli receive input about three female-produced signals, the primary pheromone component, serving as an attractant, and two minor constituents, serving a dual function, that is, attraction versus inhibition of attraction. From the antennal-lobe glomeruli, the information is conveyed to higher olfactory centers, including the lateral protocerebrum, via three main paths - of which the medial tract is the most prominent. In this study, we traced physiologically identified medial-tract projection neurons from each of the three male-specific glomeruli with the aim of mapping their terminal branches in the lateral protocerebrum. Our data suggest that the neurons' widespread projections are organized according to behavioral significance, including a spatial separation of signals representing attraction versus inhibition - however, with a unique capacity of switching behavioral consequence based on the amount of the minor components.
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http://dx.doi.org/10.7554/eLife.65683DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8154038PMC
May 2021

Antennal-lobe neurons in the moth Helicoverpa armigera: Morphological features of projection neurons, local interneurons, and centrifugal neurons.

J Comp Neurol 2021 May 5;529(7):1516-1540. Epub 2020 Oct 5.

Chemosensory lab, Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway.

The relatively large primary olfactory center of the insect brain, the antennal lobe (AL), contains several heterogeneous neuronal types. These include projection neurons (PNs), providing olfactory information to higher-order neuropils via parallel pathways, and local interneurons (LNs), which provide lateral processing within the AL. In addition, various types of centrifugal neurons (CNs) offer top-down modulation onto the other AL neurons. By performing iontophoretic intracellular staining, we collected a large number of AL neurons in the moth, Helicoverpa armigera, to examine the distinct morphological features of PNs, LNs, and CNs. We characterize 190 AL neurons. These were allocated to 25 distinct neuronal types or sub-types, which were reconstructed and placed into a reference brain. In addition to six PN types comprising 15 sub-types, three LN and seven CN types were identified. High-resolution confocal images allowed us to analyze AL innervations of the various reported neurons, which demonstrated that all PNs innervating ventroposterior glomeruli contact a protocerebral neuropil rarely targeted by other PNs, that is the posteriorlateral protocerebrum. We also discuss the functional roles of the distinct CNs, which included several previously uncharacterized types, likely involved in computations spanning from multisensory processing to olfactory feedback signalization into the AL.
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http://dx.doi.org/10.1002/cne.25034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8048870PMC
May 2021

A Novel Major Output Target for Pheromone-Sensitive Projection Neurons in Male Moths.

Front Cell Neurosci 2020 8;14:147. Epub 2020 Jun 8.

Chemosensory Laboratory, Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway.

Even though insects have comparably small brains, they achieve astoundingly complex behaviors. One example is flying moths tracking minute amounts of pheromones using olfactory circuits. The tracking distance can be up to 1 km, which makes it essential that male moths respond efficiently and reliably to very few pheromone molecules. The male-specific macroglomerular complex (MGC) in the moth antennal lobe contains circuitry dedicated to pheromone processing. Output neurons from this region project along three parallel pathways, the medial, mediolateral, and lateral tracts. The MGC-neurons of the lateral tract are least described and their functional significance is mainly unknown. We used mass staining, calcium imaging, and intracellular recording/staining to characterize the morphological and physiological properties of these neurons in the noctuid moth, . All lateral-tract MGC neurons targeted the column, a small region within the superior intermediate neuropil. We identified this region as a unique converging site for MGC lateral-tract neurons responsive to pheromones, as well as a dense congregating site for plant odor information since a substantial number of lateral-tract neurons from ordinary glomeruli (OG) also terminates in this region. The lateral-tract MGC-neurons responded with a shorter peak latency than the well-described neurons in the medial tract. Different from the medial-tract MGC neurons encoding odor quality important for species-specific signal identification, those in the lateral tract convey a more robust and rapid signal-potentially important for fast control of hard-wired behavior.
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http://dx.doi.org/10.3389/fncel.2020.00147DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7294775PMC
June 2020

Coincidence of pheromone and plant odor leads to sensory plasticity in the heliothine olfactory system.

PLoS One 2017 3;12(5):e0175513. Epub 2017 May 3.

Norwegian University of Science and Technology (NTNU), Department of Psychology, Trondheim, Norway.

Male moths possess a highly specialized olfactory system comprised of two segregated sub-arrangements dedicated to processing information about plant odors and pheromones, respectively. Communication between these two sub-systems has been described at the peripheral level, but relatively little is known about putative interactions at subsequent synaptic relays. The male moth faces the challenge of seeking out the conspecific female in a highly dynamic odor world. The female-produced pheromone blend, which is a limited resource serving as guidance for the male, will reach his antennae in intermittent pockets of odor filaments mixed with volatiles from various plants. In the present study we performed calcium imaging for measuring odor-evoked responses in the uni-glomerular antennal-lobe projection neurons (analog to mitral cells in the vertebrate olfactory bulb) of Helicoverpa armigera. In order to investigate putative interactions between the two sub-systems tuned to plant volatiles and pheromones, respectively, we performed repeated stimulations with a selection of biologically relevant odors. We found that paired stimulation with a plant odor and the pheromone led to suppressed responses in both sub-systems as compared to those evoked during initial stimulation including application of each odor stimulus alone. The fact that the suppression persisted also after pairing, indicates the existence of a Hebbian-like plasticity in the primary olfactory center established by temporal pairing of the two odor stimulation categories.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0175513PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5414983PMC
September 2017

Individual Neurons Confined to Distinct Antennal-Lobe Tracts in the Heliothine Moth: Morphological Characteristics and Global Projection Patterns.

Front Neuroanat 2016 24;10:101. Epub 2016 Oct 24.

Department of Psychology, Norwegian University of Science and Technology Trondheim, Norway.

To explore fundamental principles characterizing chemosensory information processing, we have identified antennal-lobe projection neurons in the heliothine moth, including several neuron types not previously described. Generally, odor information is conveyed from the primary olfactory center of the moth brain, the antennal lobe, to higher brain centers via projection neuron axons passing along several parallel pathways, of which the medial, mediolateral, and lateral antennal-lobe tract are considered the classical ones. Recent data have revealed the projections of the individual tracts more in detail demonstrating three main target regions in the protocerebrum; the calyces are innervated mainly by the medial tract, the superior intermediate protocerebrum by the lateral tract exclusively, and the lateral horn by all tracts. In the present study, we have identified, via iontophoretic intracellular staining combined with confocal microscopy, individual projection neurons confined to the tracts mentioned above, plus two additional ones. Further, using the visualization software AMIRA, we reconstructed the stained neurons and registered the models into a standard brain atlas, which allowed us to compare the termination areas of individual projection neurons both across and within distinct tracts. The data demonstrate a morphological diversity of the projection neurons within distinct tracts. Comparison of the output areas of the neurons confined to the three main tracts in the lateral horn showed overlapping terminal regions for the medial and mediolateral tracts; the lateral tract neurons, on the contrary, targeted mostly other output areas in the protocerebrum.
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http://dx.doi.org/10.3389/fnana.2016.00101DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5075568PMC
October 2016

Antennal-lobe tracts in the noctuid moth, Heliothis virescens: new anatomical findings.

Cell Tissue Res 2016 10 29;366(1):23-35. Epub 2016 Jun 29.

Department of Psychology, Norwegian University of Science and Technology, 7491, Trondheim, Norway.

As in other insects, three main tracts in the moth brain form parallel connections between the antennal lobe and the protocerebrum. These tracts, which consist of the antennal-lobe projection-neuron axons, target two main areas in the protocerebrum, the calyces of the mushroom bodies and the lateral horn. In spite of the solid neuroanatomical knowledge already established, there are still unresolved issues regarding the antennal-lobe tracts of the moth. One is the proportion of lateral-tract neurons targeting the calyces. In the study presented here, we have performed both retrograde and anterograde labeling of the antennal-lobe projection neurons in the brain of the moth, Heliothis virescens. The results from the retrograde staining, obtained by applying dye in the calyces, demonstrated that the direct connection between the antennal lobe and this neuropil is maintained primarily by the medial antennal-lobe tract; only a few axons confined to the lateral tract were found to innervate the calyces. In addition, these staining experiments, which allowed us to explore the arborization pattern of labeled neurons within the antennal lobe, resulted in new findings regarding anatomical arrangement of roots and cell body clusters linked to the medial tract. The results from the anterograde staining, obtained by applying dye into the antennal lobe, visualized the total assembly of axons passing along the antennal-lobe tracts. In addition to the three classical tracts, we found a transverse antennal-lobe tract not previously described in the moth. Also, these staining experiments revealed an organized neuropil in the lateral horn formed by terminals of the four antennal-lobe tracts.
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http://dx.doi.org/10.1007/s00441-016-2448-0DOI Listing
October 2016

Genomics of sponge-associated Streptomyces spp. closely related to Streptomyces albus J1074: insights into marine adaptation and secondary metabolite biosynthesis potential.

PLoS One 2014 12;9(5):e96719. Epub 2014 May 12.

Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway.

A total of 74 actinomycete isolates were cultivated from two marine sponges, Geodia barretti and Phakellia ventilabrum collected at the same spot at the bottom of the Trondheim fjord (Norway). Phylogenetic analyses of sponge-associated actinomycetes based on the 16S rRNA gene sequences demonstrated the presence of species belonging to the genera Streptomyces, Nocardiopsis, Rhodococcus, Pseudonocardia and Micromonospora. Most isolates required sea water for growth, suggesting them being adapted to the marine environment. Phylogenetic analysis of Streptomyces spp. revealed two isolates that originated from different sponges and had 99.7% identity in their 16S rRNA gene sequences, indicating that they represent very closely related strains. Sequencing, annotation, and analyses of the genomes of these Streptomyces isolates demonstrated that they are sister organisms closely related to terrestrial Streptomyces albus J1074. Unlike S. albus J1074, the two sponge streptomycetes grew and differentiated faster on the medium containing sea water. Comparative genomics revealed several genes presumably responsible for partial marine adaptation of these isolates. Genome mining targeted to secondary metabolite biosynthesis gene clusters identified several of those, which were not present in S. albus J1074, and likely to have been retained from a common ancestor, or acquired from other actinomycetes. Certain genes and gene clusters were shown to be differentially acquired or lost, supporting the hypothesis of divergent evolution of the two Streptomyces species in different sponge hosts.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0096719PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4018334PMC
January 2015

Sound-sensitive neurons innervate the ventro-lateral protocerebrum of the heliothine moth brain.

Cell Tissue Res 2014 Feb 10;355(2):289-302. Epub 2013 Dec 10.

Department of Psychology/Neuroscience Unit, MTFS, Norwegian University of Science and Technology (NTNU), 7489, Trondheim, Norway,

Many noctuid moth species perceive ultrasound via tympanic ears that are located at the metathorax. Whereas the neural processing of auditory information is well studied at the peripheral and first synaptic level, little is known about the features characterizing higher order sound-sensitive neurons in the moth brain. During intracellular recordings from the lateral protocerebrum in the brain of three noctuid moth species, Heliothis virescens, Helicoverpa armigera and Helicoverpa assulta, we found an assembly of neurons responding to transient sound pulses of broad bandwidth. The majority of the auditory neurons ascended from the ventral cord and ramified densely within the anterior region of the ventro-lateral protocerebrum. The physiological and morphological characteristics of these auditory neurons were similar. We detected one additional sound-sensitive neuron, a brain interneuron with its soma positioned near the calyces of mushroom bodies and with numerous neuronal processes in the ventro-lateral protocerebrum. Mass-staining of ventral-cord neurons supported the assumption that the ventro-lateral region of the moth brain was the main target for the auditory projections ascending from the ventral cord.
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http://dx.doi.org/10.1007/s00441-013-1749-9DOI Listing
February 2014

Characterization of Streptomyces spp. isolated from the sea surface microlayer in the Trondheim Fjord, Norway.

Mar Drugs 2008 1;6(4):620-35. Epub 2008 Dec 1.

Department of Biotechnology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.

The water surface microlayer is still poorly explored, although it has been shown to contain a high density of metabolically active bacteria, often called bacterioneuston. Actinomycetes from the surface microlayer in the Trondheim fjord, Norway, have been isolated and characterized. A total of 217 isolates from two separate samples morphologically resembling the genus Streptomyces have been further investigated in this study. Antimicrobial assays showed that about 80% of the isolates exhibited antagonistic activity against non-filamentous fungus, Gram-negative, and Gram-positive bacteria. Based on the macroscopic analyses and inhibition patterns from the antimicrobial assays, the sub-grouping of isolates was performed. Partial 16S rDNAs from the candidates from each subgroup were sequenced and phylogenetic analysis performed. 7 isolates with identical 16S rDNA sequences were further studied for the presence of PKS type I genes. Sequencing and phylogenetic analysis of the PKS gene fragments revealed that horizontal gene transfer between closely related species might have taken place. Identification of unique PKS genes in these isolates implies that de-replication can not be performed based solely on the 16S rDNA sequences. The results obtained in this study suggest that streptomycetes from the neuston population may be an interesting source for discovery of new antimicrobial agents.
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http://dx.doi.org/10.3390/md6040620DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2630845PMC
March 2009