Biology subjects

Costa, M.

Publications and source records attributed to Costa, M..

67 records · Page 4Linked to original sources

bioRxiv2020

Differential roles of pyramidal and fast-spiking, GABAergic neurons in the control of glioma cell proliferation

Recent studies have demonstrated an active role for neurons in glioma progression. Specifically, peritumoral neurons establish functional excitatory synapses with glioma cells, and optogenetic stimulation of cortical pyramidal neurons drives tumor progression. However, the specific role of different subsets of cortical neurons, such as GABAergic interneurons, remains unexplored. Here, we directly compared the effects of optogenetic stimulation of pyramidal cells vs. fast-spiking, GABAergic neurons. In mice inoculated with GL261 cells into the motor cortex, we show that optogenetic stimulation of pyramidal neurons enhances glioma cell proliferation. In contrast, optogenetic stimulation of fast-spiking, parvalbumin-positive interneurons reduces proliferation as measured by BrdU incorporation and Ki67 immunolabelling. Since both principal cells and fast-spiking interneurons are directly activated by sensory afferent input, we next placed tumors in the occipital cortex to test the impact of visual stimulation/deprivation. We report that total lack of visual input via dark rearing enhances the density of proliferating glioma cells, while daily visual stimulation by gratings of different spatial frequencies and contrast reduces tumor growth. The effects of sensory input are region-specific, as visual deprivation has no significant effect on tumor proliferation in mice with gliomas in the motor cortex. We also report that sensory stimulation combined with temozolomide administration delays the loss of visual responses in peritumoral neurons. Altogether, these data demonstrate complex effects of different neuronal subtypes in the control of glioma proliferation. HighlightsO_LIActivity of GABAergic neurons reduces glioma cell proliferation C_LIO_LILevels of sensory afferent input regulate tumor proliferation C_LIO_LIEffects of sensory input are region-specific C_LI

cancer biology↗

bioRxiv2020

Input connectivity reveals additional heterogeneity of dopaminergic reinforcement in Drosophila

Different types of Drosophila dopaminergic neurons (DANs) reinforce memories of unique valence and provide state-dependent motivational control [1]. Prior studies suggest that the compartment architecture of the mushroom body (MB) is the relevant resolution for distinct DAN functions [2, 3]. Here we used a recent electron microscope volume of the fly brain [4] to reconstruct the fine anatomy of individual DANs within three MB compartments. We find the 20 DANs of the {gamma}5 compartment, at least some of which provide reward teaching signals, can be clustered into 5 anatomical subtypes that innervate different regions within {gamma}5. Reconstructing 821 upstream neurons reveals input selectivity, supporting the functional relevance of DAN sub-classification. Only one PAM-{gamma}5 DAN subtype {gamma}5(fb) receives direct recurrent input from {gamma}5{beta}2a mushroom body output neurons (MBONs) and behavioral experiments distinguish a role for these DANs in memory revaluation from those reinforcing sugar memory. Other DAN subtypes receive major, and potentially reinforcing, inputs from putative gustatory interneurons or lateral horn neurons, which can also relay indirect feedback from MBONs. We similarly reconstructed the single aversively reinforcing PPL1-{gamma}1pedc DAN. The {gamma}1pedc DAN inputs mostly differ from those of {gamma}5 DANs and they cluster onto distinct dendritic branches, presumably separating its established roles in aversive reinforcement and appetitive motivation [5, 6]. Tracing also identified neurons that provide broad input to {gamma}5, {beta}2a and {gamma}1pedc DANs suggesting that distributed DAN populations can be coordinately regulated. These connectomic and behavioral analyses therefore reveal further complexity of dopaminergic reinforcement circuits between and within MB compartments. HighlightsO_LINanoscale anatomy reveals additional subtypes of rewarding dopaminergic neurons. C_LIO_LIConnectomics reveals extensive input specificity to subtypes of dopaminergic neurons. C_LIO_LIAxon morphology implies dopaminergic neurons provide subcompartment-level function. C_LIO_LIUnique dopaminergic subtypes serve aversive memory extinction and sugar learning. C_LI

neuroscience↗

bioRxiv2020

Connectomics analysis reveals first, second, and third order thermosensory and hygrosensory neurons in the adult Drosophila brain

Animals exhibit innate and learned preferences for temperature and humidity - conditions critical for their survival and reproduction. Here, we leveraged a whole adult brain electron microscopy volume to study the circuitry associated with antennal thermosensory and hygrosensory neurons, which target specific ventroposterior (VP) glomeruli in the Drosophila melanogaster antennal lobe. We have identified two new VP glomeruli, in addition to the five known ones, and the projection neurons (VP PNs) that relay VP information to higher brain centres, including the mushroom body and lateral horn, seats of learned and innate olfactory behaviours, respectively. Focussing on the mushroom body lateral accessory calyx (lACA), a known thermosensory neuropil, we present a comprehensive connectome by reconstructing neurons downstream of heating- and cooling-responsive VP PNs. We find that a few lACA-associated mushroom body intrinsic neurons (Kenyon cells) solely receive thermosensory inputs, while most receive additional olfactory and thermo- or hygrosensory PN inputs in the main calyx. Unexpectedly, we find several classes of lACA-associated neurons that form a local network with outputs to other brain neuropils, suggesting that the lACA serves as a general hub for thermosensory circuitry. For example, we find DN1 pacemaker neurons that link the lACA to the accessory medulla, likely mediating temperature-based entrainment of the circadian clock. Finally, we survey strongly connected downstream partners of VP PNs across the protocerebrum; these include a descending neuron that receives input mainly from dry-responsive VP PNs, meaning that just two synapses might separate hygrosensory inputs from motor neurons in the nerve cord. (249) HIGHLIGHTSO_LITwo novel thermo/hygrosensory glomeruli in the fly antennal lobe C_LIO_LIFirst complete set of thermosensory and hygrosensory projection neurons C_LIO_LIFirst connectome for a thermosensory centre, the lateral accessory calyx C_LIO_LINovel third order neurons, including a link to the circadian clock C_LI

neuroscience↗

bioRxiv2020

Complete connectomic reconstruction of olfactory projection neurons in the fly brain

Nervous systems contain sensory neurons, local neurons, projection neurons and motor neurons. To understand how these building blocks form whole circuits, we must distil these broad classes into neuronal cell types and describe their network connectivity. Using an electron micrograph dataset for an entire Drosophila melanogaster brain, we reconstruct the first complete inventory of olfactory projections connecting the antennal lobe, the insect analogue of the mammalian olfactory bulb, to higher-order brain regions in an adult animal brain. We then connect this inventory to extant data in the literature, providing synaptic-resolution holotypes both for heavily investigated and previously unknown cell types. Projection neurons are approximately twice as numerous as reported by light level studies; cell types are stereotyped, but not identical, in cell and synapse numbers between brain hemispheres. The lateral horn, the insect analogue of the mammalian cortical amygdala, is the main target for this olfactory information and has been shown to guide innate behaviour. Here, we find new connectivity motifs, including: axo-axonic connectivity between projection neurons; feedback and lateral inhibition of these axons by local neurons; and the convergence of different inputs, including non-olfactory inputs and memory-related feedback onto lateral horn neurons. This differs from the configuration of the second most prominent target for olfactory projection neurons: the mushroom body calyx, the insect analogue of the mammalian piriform cortex and a centre for associative memory. Our work provides a complete neuroanatomical platform for future studies of the adult Drosophila olfactory system. HighlightsO_LIFirst complete parts list for second-order neurons of an adult olfactory system C_LIO_LIQuantification of left-right stereotypy in cell and synapse number C_LIO_LIAxo-axonic connections form hierarchical communities in the lateral horn C_LIO_LILocal neurons and memory-related feedback target projection neuron axons C_LI

neuroscience↗

bioRxiv2019

d-Lysergic acid diethylamide has major potential as a cognitive enhancer

Psychedelic agonists of serotonin receptors induce neural plasticity and synaptogenesis, but their potential to enhance learning remains uncharted. Here we show that a single dose of d-LSD, a potent serotonergic agonist, increased novel object preference in young and adult rats several days after treatment. d-LSD alone did not increase preference in old animals, but could rescue it to young levels when followed by a 6-day exposure to enriched environment (EE). Mass spectrometry-based proteomics in human brain organoids treated with d-LSD showed upregulation of proteins from the presynaptic active zone. A computational model of synaptic connectivity in the hippocampus and prefrontal cortex suggests that d-LSD enhances novelty preference by combining local synaptic changes in mnemonic and executive regions, with alterations of long-range synapses. Better pattern separation within EE explained its synergy with d-LSD in rescuing novelty preference in old animals. These results advance the use of d-LSD in cognitive enhancement.

neuroscience↗

bioRxiv2019

Polyadenylation of Histone H3.1 mRNA Promotes Cell Transformation by Displacing H3.3 from Gene Regulatory Elements

Replication-dependent canonical histone messenger RNAs (mRNAs) do not terminate with a poly(A) tail at the 3 end. We previously demonstrated that exposure to arsenic, an environmental carcinogen, induces polyadenylation of canonical histone H3.1 mRNA. The addition of a poly(A) tail to the H3.1 mRNA caused transformation of human cells in vitro, but the underlying mechanisms are unknown. Here we report that polyadenylation of H3.1 mRNA increases H3.1 protein level, resulting in depletion of histone variant H3.3 at active promoters, enhancers, and insulator regions through its displacement. Cells underwent transcriptional deregulation, G2/M cell cycle arrest, chromosome aneuploidy and aberrations. Furthermore, knocking down the expression of H3.3 induced cell transformation, whereas ectopic expression of H3.3 attenuated arsenic-induced cell transformation, suggesting that H3.3 displacement might be central to tumorigenic effects of polyadenylated H3.1 mRNA. Our study provides novel insights into the importance of proper histone stoichiometry in maintaining genome integrity.\n\nHighlightsO_LIPolyadenylation of canonical histone H3.1 mRNA promotes tumor formation in nude mice\nC_LIO_LIHistone variant H3.3 is displaced from critical gene regulatory elements by overexpression of polyadenylated H3.1 mRNA\nC_LIO_LIIncreased polyadenylated H3.1 mRNA causes abnormal transcription, cell cycle arrest, and chromosomal instability\nC_LIO_LIArsenic induces polyadenylation of H3.1 mRNA in vivo\nC_LI

molecular biology↗

bioRxiv2019

3D-Cardiomics: A spatial transcriptional atlas of the mammalian heart

Understanding spatial gene expression and regulation is key to uncovering developmental and physiological processes, during homeostasis and disease. Numerous techniques exist to gain gene expression and regulation information, but very few utilise intuitive true-to-life three-dimensional representations to analyze and visualize results. Here we combined spatial transcriptomics with 3D modelling to represent and interrogate, transcriptome-wide, three-dimensional gene expression and location in the mouse adult heart. Our study has unveiled specific subsets of genes that display complex spatial expression in organ sub-compartments. Also, we created a web-based user interface for spatial transcriptome analysis and visualization. The application may be accessed from http://3d-cardiomics.erc.monash.edu/.

systems biology↗

bioRxiv2019

The cyanobacterial saxitoxin exacerbates neural cell death and brain malformations induced by Zika virus

The northeast (NE) region of Brazil commonly goes through drought periods, which favor cyanobacterial blooms, capable of producing neurotoxins with implications for human and animal health. The most severe dry spell in the history of Brazil occurred between 2012 and 2016. Coincidently, the highest incidence of microcephaly associated with the Zika virus (ZIKV) outbreak was described in the NE region of Brazil during the same years. In this work, we tested the hypothesis that saxitoxin (STX), a neurotoxin produced in South America by the freshwater cyanobacteria Raphidiopsis raciborskii, could have contributed to the most severe Congenital Zika Syndrome (CZS) profile described worldwide. Quality surveillance showed higher cyanobacteria amounts and STX occurrence in human drinking water supplies of NE compared to other regions of Brazil. Experimentally, we described that STX doubled the amount of ZIKV-induced neural cell death in progenitor areas of human brain organoids, while the chronic ingestion of water contaminated with STX before and during gestation caused brain abnormalities in offspring of ZIKV-infected immunocompetent C57BL/6J mice. Our data indicate that saxitoxin-producing cyanobacteria is overspread in water reservoirs of the NE and might have acted as a co-insult to ZIKV infection in Brazil. These results raise a public health concern regarding the consequences of arbovirus outbreaks happening in areas with droughts and/or frequent freshwater cyanobacterial blooms.\n\nAuthor summaryThe uncontrolled spreading of cyanobacteria in drinking water reservoirs has been the cause of serious public health problems worldwide. Toxin-producing cyanobacterial blooms commonly occur during drought periods in the northeast (NE) region of Brazil. During Zika Virus (ZIKV) outbreak in 2015-16, Brazilian NE showed disproportionately higher microcephaly incidence. Here, we test the hypothesis that the cyanotoxin saxitoxin (STX) may act as a co-insult for ZIKV. Water quality surveillance data showed increased cyanobacteria population and higher STX amount in NE region during 2014-2018. In vitro, we observed that neural progenitor cell death was doubled after STX exposure to ZIKV-infected brain organoids. In vivo, chronic ingestion of STX during gestational period potentiated ZIKV-derived brain abnormalities in newborn mice. Our study provides new insights that may explain the discrepancies among Brazilian regions regarding CZS severity. Moreover, the data highlight the importance of cyanobacteria and cyanotoxin freshwater monitoring for future arbovirus outbreaks.

neuroscience↗

bioRxiv2019

Postdoc X-ray in Europe 2017: work conditions, productivity, institutional support and career outlooks

1.Executive SummaryThis survey and data analysis were conducted by the European Network of Postdoctoral Associations (ENPA) with the aim of assessing the current research and work conditions, aspirations and support received by postdoctoral researchers working in Europe. The Results section is structured into three main parts. The first one describes the study sample of European postdoctoral researchers, including participants demographics, funding sources and income, research outputs, and teaching opportunities. The second section focuses on their professional aspirations and institutional support provided. The third part describes the level of engagement of postdoctoral researchers and their institutions in working towards better research conditions and career development, and what initiatives are emerging within this community. Our Conclusions section pulls together this comprehensive analysis, highlighting some of the most concerning issues currently affecting postdoctoral researchers in Europe. We also make a number of recommendations that would significantly improve the career expectations and aspirations of postdoctoral researchers. These are listed below. Conclusions and recommendationsO_LILonger postdoctoral periods in Southern Europe despite higher publication metrics Recommendation Institutions in Southern Europe should develop clear criteria to support postdoctoral researchers career progression. C_LIO_LISouthern and Eastern Europe pay the lowest salaries and have the lowest number of foreign postdoctoral researchers Recommendation The salary differences across European countries should be addressed as this could be a barrier to mobility and knowledge exchange from higher to lower pay regions. C_LIO_LILack of access to funding is a significant concern of postdoctoral researchers Recommendation Discrepancies in access to funding should be minimized across the different European areas. C_LIO_LIPostdoctoral researchers in Europe work longer hours than required by contract Recommendation The culture of overwork in the research environment should be addressed in order to protect researchers against the risks associated with long hours at work. C_LIO_LIThe majority of full-time postdoctoral work contracts includes an exclusivity clause Recommendation Inclusion of exclusivity clauses in contracts for postdoctoral researchers should be optional in order to allow them to enhance their employability outside academia. C_LIO_LIPostdoctoral researchers career development is poorly supported by their institutions Recommendation Postdoctoral researchers career prospects and career management should be much more supported by institutions in coordination with postdoctoral associations. C_LIO_LILack of postdoctoral representation in governance is linked to unclear institutional duties and rights Recommendation Institutional governance bodies should include postdoctoral researcher representatives. This would ensure that the views of this vital staff group are heard, as well as making postdoctoral researchers feel more engaged with their own institutions. A flexible and proactive communication strategy at the institution and research group level should be developed, taking into account the sometimes transient nature of postdoctoral researchers posts. C_LIO_LIResearchers show higher engagement with their local postdoctoral associations than with workers unions Recommendation Postdoctoral associations are an essential way to advocate for postdoctoral researchers at the governance level. Institutions should engage with, promote and support the work of postdoctoral associations. C_LI

scientific communication and education↗

bioRxiv2018

Neurogenetic dissection of the Drosophila innate olfactory processing center

Animals exhibit innate behaviours in response to a variety of sensory stimuli such as olfactory cues. In Drosophila, a higher olfactory centre called the lateral horn (LH) is implicated in innate behaviour. However, our knowledge of the structure and function of the LH is scant, due to the lack of sparse neurogenetic tools for this brain region. Here we generate a collection of split-GAL4 driver lines providing genetic access to 82 LH cell-types. We identify the neurotransmitter and axo-dendritic polarity for each cell-type. Using these lines were create an anatomical map of the LH. We found that [~]30% of LH projections converge with outputs from the mushroom body, the site of olfactory learning and memory. Finally, using optogenetic activation of small groups of LH neurons. We identify cell-types that drive changes in either valence or specific motor programs, such as turning and locomotion. In summary we have generated a resource for manipulating and mapping LH neurons in both light and electron microscopy and generated insights into the anatomy and function of the LH.

neuroscience↗

bioRxiv2018

Neural circuit basis of aversive odour processing in Drosophila from sensory input to descending output.

Evolution has shaped nervous systems to produce stereotyped behavioural responses to ethologically relevant stimuli. For example when laying eggs, female Drosophila avoid geosmin, an odorant produced by toxic moulds. Here we identify second, third, and fourth order neurons required for this innate olfactory aversion. Connectomics data place these neurons in a complete synaptic circuit from sensory input to descending output. We find multiple levels of valence-specific convergence, including a novel form of axo-axonic input onto second order neurons conveying another danger signal, the pheromone of parasitoid wasps. However, we also observe extensive divergence: second order geosmin neurons connect with a diverse array of 80 third order cell types. We find a pattern of convergence of aversive odour channels at this level. Crossing one more synaptic layer, we identified descending neurons critical for egg-laying aversion. Our data suggest a transition from a labelled line organisation in the periphery to a highly distributed central brain representation that is then coupled to distinct descending pathways.

neuroscience↗

bioRxiv2018

A congenital pain insensitivity mutation in the nerve growth factor gene uncouples nociception from affective pain in heterozygous humans and mice

Pain is an unpleasant but necessary sensory experience, which facilitates adaptive behaviours, such as fear. Despite recent advances, the question of how the pain experience influences learning of the fear response is still debated1,2. Genetic disorders rendering patients congenitally unable to feel pain have been described, and are usually explained by defects in peripheral nociceptors3-5. It is not known how growing up without pain affects central emotional and motivational responses to aversive stimuli. The rare autosomal recessive Hereditary Sensory and Autonomic Neuropathy type V (HSAN V) is caused by a mutation in the nerve growth factor (NGF) gene (R100W). HSAN V homozygous patients display a congenital indifference to painful events, with deficits in peripheral nociceptors but without overt cognitive impairment6. In contrast, heterozygous carriers do not present with pain-related deficits and have been identified only through pedigree and genetic screening7,8. We exploited this clinically silent population to dissociate nociceptive from affective features of pain. To address this we investigated both heterozygous knock-in mice bearing the R100W mutation (NGFR100W/m mice) and a cohort of HSAN V heterozygous human carriers. Surprisingly, we found that NGFR100W/m mice, despite normal responses to a noxious conditioning stimulus, show a deficit in learned fear while their social and innate fear responses are normal. The lack of pain-related fear response was linked to a reduced activation of anterior cingulate and motor cortices and of striatum, but not in primary somatosensory cortex. Likewise, human heterozygous R100W carriers, despite perceiving noxious stimuli and reporting subjective pain thresholds, show increased reaction latencies in response to painful stimulation, alongside a decreased subjective urgency to react. Functional magnetic resonance imaging (fMRI) revealed, comparably to the mouse data, an altered processing of painful stimuli in rostral anterior cingulate, medial premotor cortical regions and striatum. These findings from both human and mouse HSAN V carriers uncover behavioural and motivational consequences of a mild genetic pain insensitivity on the establishment of pain-dependent affective responses and memories.

neuroscience↗

bioRxiv2017

A Systematic Nomenclature for the Drosophila Ventral Nervous System

The fruit fly, Drosophila melanogaster, is an established and powerful model system for neuroscience research with wide relevance in biology and medicine. Until recently, research on the Drosophila brain was hindered by the lack of a complete and uniform nomenclature. Recognising this problem, the Insect Brain Name Working Group produced an authoritative hierarchical nomenclature system for the adult insect brain, using Drosophila melanogaster as the reference framework, with other taxa considered to ensure greater consistency and expandability (Ito et al., 2014). Here, we extend this nomenclature system to the sub-gnathal regions of the adult Drosophila nervous system, thus providing a systematic anatomical description of the ventral nervous system (VNS). This portion of the nervous system includes the thoracic and abdominal neuromeres that were not included in the original work and contains the motor circuits that play essential roles in most fly behaviours.

neuroscience↗