Publications by authors named "James E Jepson"

Evolutionary novelties are commonly identified as drivers of lineage diversification, with key innovations potentially triggering adaptive radiation. Nevertheless, testing hypotheses on the role of evolutionary novelties in promoting diversification through deep time has proven challenging. Here we unravel the role of the raptorial appendages, with evolutionary novelties for predation, in the macroevolution of a predatory insect lineage, the Superfamily Mantispoidea (mantidflies, beaded lacewings, thorny lacewings, and dipteromantispids), based on a new dated phylogeny and quantitative evolutionary analyses on modern and fossil species.

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  • * A study examined 28 patients from 18 families with loss of function (LOF) variants, revealing a spectrum of neurological and developmental issues including global developmental delay, intellectual disabilities, microcephaly, and behavioral abnormalities.
  • * Research using fruit flies showed that mutations in the RBF gene mirrored symptoms seen in patients, affecting brain morphology and movement, and highlighted the importance of ongoing RBL2 expression in mature neurons for normal locomotion, suggesting potential therapeutic avenues.
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The neuropterid (Neuroptera and Raphidioptera) fauna of the middle Eocene Coal Creek Member (Kishenehn Formation), U.S.A.

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  • Recent advancements in DNA sequencing have improved our understanding of insect phylogeny, but the relationships within the order Neuroptera remain poorly defined.
  • A new transcriptomic dataset was assembled to clarify these relationships and estimate divergence times, using various phylogenetic techniques for robustness.
  • The study’s findings suggest specific familial relationships within Neuropterida, with most families diversifying during the Jurassic period and predominantly terrestrial larvae as a key ancestral trait.
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In a recent paper (Jepson et al., 2018) a new genus of Mesomantispinae from Karatau, Kazakhstan was described. The name given to the genus, Longicollum, is unavailable, because it is preoccupied by a senior homonym, Longicollum Yamaguti, 1935 (Acanthocephala: Pomphorhynchidae).

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Two new genera and species, and one indeterminate genera and species of fossil Mantispidae, Mesomantispinae are described from the Upper Jurassic of Karatau, Kazakhstan: Longicollum benmaddoxi gen. et sp. nov.

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Sleep is a highly conserved and essential behaviour in many species, including the fruit fly Drosophila melanogaster. In the wild, sensory signalling encoding environmental information must be integrated with sleep drive to ensure that sleep is not initiated during detrimental conditions. However, the molecular and circuit mechanisms by which sleep timing is modulated by the environment are unclear.

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Two new genera and species of Megaloptera are described from the Lower Cretaceous Crato Formation of Brazil. Cratocorydalopsis brasiliensis gen. et sp.

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There are 32 individual specimens of Mantispidae (Insecta: Neuroptera) currently recorded from the fossil record, the oldest of which dates back to the Lower Jurassic. These include 19 described species (in 16 genera), 1 specimen described to genus level and 9 unnamed specimens The specimens have been assigned to the extant subfamilies Drepanicinae (4), Mantispinae (10), Symphrasinae (1), and the extinct subfamily Mesomantispinae (16), with one incertae sedis within Mantispidae. There are currently no known fossil representatives of the subfamily Calomantispinae.

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Sleep is an essential and conserved behavior whose regulation at the molecular and anatomical level remains to be elucidated. Here, we identify TARANIS (TARA), a Drosophila homolog of the Trip-Br (SERTAD) family of transcriptional coregulators, as a molecule that is required for normal sleep patterns. Through a forward-genetic screen, we isolated tara as a novel sleep gene associated with a marked reduction in sleep amount.

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Synaptic scaffold proteins control the localization of ion channels and receptors, and facilitate molecular associations between signaling components that modulate synaptic transmission and plasticity. Here, we define novel roles for a recently described scaffold protein, Dsychronic (DYSC), at the Drosophila larval neuromuscular junction. DYSC is the Drosophila homolog of whirlin/DFNB31, a PDZ domain protein linked to Usher syndrome, the most common form of human deaf-blindness.

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Heterochromatin formation drives epigenetic mechanisms associated with silenced gene expression. Repressive heterochromatin is established through the RNA interference pathway, triggered by double-stranded RNAs (dsRNAs) that can be modified via RNA editing. However, the biological consequences of such modifications remain enigmatic.

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X-ray computed tomography is used to identify a unique example of fossilized phoresy in 16 million-year-old Miocene Dominican amber involving a springtail being transported by a mayfly. It represents the first evidence (fossil or extant) of phoresy in adult Ephemeroptera and only the second record in Collembola (the first is also preserved in amber). This is the first record of Collembola using winged insects for dispersal.

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Many aspects of behavior and physiology are under circadian control. In Drosophila, the molecular clock that regulates rhythmic patterns of behavior has been extensively characterized. In contrast, genetic loci involved in linking the clock to alterations in motor activity have remained elusive.

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Auto-regulatory feedback loops are a common molecular strategy used to optimize protein function. In Drosophila, many messenger RNAs involved in neuro-transmission are re-coded at the RNA level by the RNA-editing enzyme, dADAR, leading to the incorporation of amino acids that are not directly encoded by the genome. dADAR also re-codes its own transcript, but the consequences of this auto-regulation in vivo are unclear.

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Informational recoding by adenosine-to-inosine RNA editing diversifies neuronal proteomes by chemically modifying structured mRNAs. However, techniques for analyzing editing activity on substrates in defined neurons in vivo are lacking. Guided by comparative genomics, here we reverse-engineered a fluorescent reporter sensitive to Drosophila melanogaster adenosine deaminase that acts on RNA (dADAR) activity and alterations in dADAR autoregulation.

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Loss of FMR1 gene function results in fragile X syndrome, the most common heritable form of intellectual disability. The protein encoded by this locus (FMRP) is an RNA-binding protein that is thought to primarily act as a translational regulator; however, recent studies have implicated FMRP in other mechanisms of gene regulation. We found that the Drosophila fragile X homolog (dFMR1) biochemically interacted with the adenosine-to-inosine RNA-editing enzyme dADAR.

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Evidence for the chemical conversion of adenosine-to-inosine (A-to-I) in messenger RNA (mRNA) has been detected in numerous metazoans, especially those "most successful" phyla: Arthropoda, Mollusca, and Chordata. The requisite enzymes for A-to-I editing, ADARs (adenosine deaminases acting on RNA) are highly conserved and are present in every higher metazoan genome sequenced to date. The fruit fly, Drosophila melanogaster, represents an ideal model organism for studying A-to-I editing, both in terms of fundamental biochemistry and in relation to determining adaptive downstream effects on physiology and behavior.

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In metazoan cells, transcripts that fold into double-strand RNA structures are endowed with the capacity to undergo A-to-I RNA editing, during which adenosines are catalytically deaminated to inosines by a class of enzymes known as ADARs (adenosine deaminases acting on RNA). In Drosophila, a wide range of coding mRNAs associated with signaling in the nervous system undergo A-to-I editing, and loss of editing results in extreme behavioral defects. Furthermore, there are indications that the precursors of endogenous small interfering RNAs also undergo editing.

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Adenosine deaminases acting on RNA (ADARs) catalyze the deamination of adenosine to inosine in double-stranded RNA templates, a process known as RNA editing. In Drosophila, multiple ADAR isoforms are generated from a single locus (dAdar) via post-transcriptional modifications. Collectively, these isoforms act to edit a wide range of transcripts involved in neuronal signaling, as well as the precursors of endogenous small interfering RNAs.

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Adenosine to inosine RNA editing, catalyzed by Adenosine Deaminases Acting on RNA (ADARs), represents an evolutionary conserved post-transcriptional mechanism which harnesses RNA structures to produce proteins that are not literally encoded in the genome. The species-specific alteration of functionally important residues in a multitude of neuronal ion channels and pre-synaptic proteins through RNA editing has been shown to have profound importance for normal nervous system function in a wide range of invertebrate and vertebrate model organisms. ADARs have also been shown to regulate neuronal gene expression through a remarkable variety of disparate processes, including modulation of the RNAi pathway, the creation of alternative splice sites, and the abolition of stop codons.

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Increasing proteomic diversity via the hydrolytic deamination of adenosine to inosine (A-to-I) in select mRNA templates appears crucial to the correct functioning of the nervous system in several model organisms, including Drosophila, Caenorabditis elegans, and mice. The genome of the fruitfly, Drosophila melanogaster, contains a single gene encoding the enzyme responsible for deamination, termed ADAR (for adenosine deaminase acting on RNA). The mRNAs that form the substrates for ADAR primarily function in neuronal signaling, and, correspondingly, deletion of ADAR leads to severe nervous system defects.

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The neonicotinoid insecticide imidacloprid is an agonist on insect nicotinic acetylcholine receptors (nAChRs). We utilised fura-2-based calcium imaging to investigate the actions of imidacloprid on cultured GFP-tagged cholinergic neurons from the third instar larvae of the genetic model organism Drosophila melanogaster. We demonstrate dose-dependent increases in intracellular calcium ([Ca2+]i) in cholinergic neurons upon application of imidacloprid (10 nM-100 muM) that are blocked by nAChR antagonists mecamylamine (10 microM) and alpha-bungarotoxin (alpha-BTX, 1 microM).

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