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  • 1
    Language: English
    In: Cellular and molecular life sciences : CMLS, 2021-03, Vol.78 (5), p.2095-2103
    Description: Chromosomal fragile sites are described as areas within the tightly packed mitotic chromatin that appear as breaks or gaps mostly tracing back to a loosened structure and not a real nicked break within the DNA molecule. Most facts about fragile sites result from studies in mitotic cells, mainly during metaphase and mainly in lymphocytes. Here, we synthesize facts about the genomic regions that are prone to form gaps and breaks on metaphase chromosomes in the context of interphase. We conclude that nuclear architecture shapes the activity profile of the cell, i.e. replication timing and transcriptional activity, thereby influencing genomic integrity during interphase with the potential to cause fragility in mitosis. We further propose fragile sites as examples of regions specifically positioned in the interphase nucleus with putative anchoring points at the nuclear lamina to enable a tightly regulated replication-transcription profile and diverse signalling functions in the cell. Consequently, fragility starts before the actual display as chromosomal breakage in metaphase to balance the initial contradiction of cellular overgrowth or malfunctioning and maintaining diversity in molecular evolution.
    Subject(s): DNA - genetics ; Chromosomal Instability - genetics ; Animals ; Cell Nucleus - metabolism ; Cell Nucleus - genetics ; Humans ; DNA Replication - genetics ; Chromosome Fragile Sites - genetics ; DNA - metabolism ; Interphase - genetics ; Mitosis - genetics ; Genome, Human - genetics ; Chromosomes ; Chromatin ; Genetic transcription ; Chromosome condensation ; Chromosome territory ; Replication-transcription conflicts ; Cell cycle ; Chromatin organization ; Review ; Cancer
    ISSN: 1420-682X
    E-ISSN: 1420-9071
    Source: Alma/SFX Local Collection
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  • 2
    Language: English
    In: Frontiers in physiology, 2019-03-28, Vol.10, p.343-343
    Description: Herbivorous insects mainly rely on their sense of taste to decode the chemical composition of potential hosts in close range. Beetles for example contact and scan leaves with their tarsi, mouthparts and antennal tips, i.e., appendages equipped with gustatory sensilla, among other sensillum types. Gustatory neurons residing in such uniporous sensilla detect mainly non-volatile compounds that contribute to the behavioral distinction between edible and toxic plants. However, the identification of gustatory sensilla is challenging, because an appendage often possesses many sensilla of distinct morphological and physiological types. Using the specialized poplar leaf beetle (Chrysomela populi, Chrysomelidae), here we show that cuticular autofluorescence scanning combined with electron microscopy facilitates the identification of antennal gustatory sensilla and their differentiation into two subtypes. The gustatory function of sensilla chaetica was confirmed by single sensillum tiprecordings using sucrose, salicin and salt. Sucrose and salicin were found at higher concentrations in methanolic leaf extracts of poplar (Populus nigra) as host plant compared to willow (Salix viminalis) as control, and were found to stimulate feeding in feeding choice assays. These compounds may thus contribute to the observed preference for poplar over willow leaves. Moreover, these gustatory cues benefited the beetle's performance since weight gain was significantly higher when C. populi were reared on leaves of poplar compared to willow. Overall, our approach facilitates the identification of insect gustatory sensilla by taking advantage of their distinct fluorescent properties. This study also shows that a specialist beetle selects the plant species that provides optimal development, which is partly by sensing some of its characteristic non-volatile metabolites via antennal gustatory sensilla.
    Subject(s): Life Sciences & Biomedicine ; Physiology ; Science & Technology ; Physiological aspects ; Fluorescence ; Beetles ; Taste ; cuticular autofluorescence ; antenna ; leaf beetle ; contact chemosensation ; sensilla chaetica ; gustation ; herbivory ; Chrysomela populi
    ISSN: 1664-042X
    E-ISSN: 1664-042X
    Source: Web of Science - Science Citation Index Expanded - 2019〈img src="http://exlibris-pub.s3.amazonaws.com/fromwos-v2.jpg" /〉
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 3
    Language: English
    In: Biológia, 2015-01, Vol.70 (1), p.141-149
    Description: During their staging at stopover sites, migrants compete with resident species over food resources. This ‘resource competition hypothesis’ has often been examined in breeding areas of songbirds, but little is known about resource competition between migrants and resident species at stopover sites. We studied foraging behaviour and microhabitat of the endemic resident species Cyprus Wheatear Oenanthe cypriaca in comparison to eleven migrating species of the same genus or of the same flycatching guild during spring migration on Cyprus, a Mediterranean stopover site. We characterized microhabitats of congeneric Oenanthe species by less cover overhead and low perches and distinguished them from migrating Ficedula hypoleuca, Ficedula albicollis and Phoenicurus phoenicurus, which preferred high cover overhead and medium perches. In a hierarchical cluster analysis, O. cypriaca clustered together with three shrike species Lanius and the flycatcher Muscicapa striata, with less cover overhead, but high perches. During foraging, hopping behaviour discriminated best among the Oenanthe species. Multidimensional scaling on foraging behaviour showed that O. cypriaca is clearly distinct from the other species. Direct competition (aggressive encounters) between the resident species and migrants was rarely observed. Our results provide support for niche partitioning and coexistence between migrants and a resident species at a stopover site.
    Subject(s): Life Sciences ; habitat ; Life Sciences, general ; Microbiology ; stopover sites ; Zoology ; foraging behaviour ; niche partitioning ; Plant Sciences ; bird migration ; Cell Biology ; Migratory birds ; Competition (Biology) ; Ornithological research ; Research ; Behavior ; Foraging
    ISSN: 0006-3088
    E-ISSN: 1336-9563
    Source: Alma/SFX Local Collection
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  • 4
    Language: English
    In: Scientific reports, 2016-03-04, Vol.6 (1), p.22407
    Description: Insects often release noxious substances for their defence. Larvae of Zygaena filipendulae (Lepidoptera) secrete viscous and cyanogenic glucoside-containing droplets, whose effectiveness was associated with their physical and chemical properties. The droplets glued mandibles and legs of potential predators together and immobilised them. Droplets were characterised by a matrix of an aqueous solution of glycine-rich peptides (H-WG11-NH2) with significant amounts of proteins and glucose. Among the proteins, defensive proteins such as protease inhibitors, proteases and oxidases were abundant. The neurotoxin β-cyanoalanine was also found in the droplets. Despite the presence of cyanogenic glucosides, which release toxic hydrogen cyanide after hydrolysis by a specific β-glucosidase, the only β-glucosidase identified in the droplets (ZfBGD1) was inactive against cyanogenic glucosides. Accordingly, droplets did not release hydrogen cyanide, unless they were mixed with specific β-glucosidases present in the Zygaena haemolymph. Droplets secreted onto the cuticle hardened and formed sharp crystalline-like precipitates that may act as mandible abrasives to chewing predators. Hardening followed water evaporation and formation of antiparallel β-sheets of the peptide oligomers. Consequently, after mild irritation, Zygaena larvae deter predators by viscous and hardening droplets that contain defence proteins and β-cyanoalanine. After severe injury, droplets may mix with exuding haemolymph to release hydrogen cyanide.
    Subject(s): Crystallins - metabolism ; Peptide Fragments - metabolism ; Glycosides - analysis ; Secretory Vesicles - chemistry ; Ants - physiology ; Lepidoptera - physiology ; Hemolymph - metabolism ; Alanine - analogs & derivatives ; Hydrogen Cyanide - metabolism ; Animals ; Larva ; Insect Proteins - chemistry ; beta-Glucosidase - metabolism ; Insect Proteins - metabolism ; Alanine - analysis ; Bodily Secretions ; Spiders - physiology ; Cyanide ; Mandible ; Hydrogen ; Hemolymph ; Proteinase inhibitors ; Evaporation ; Chewing ; Glycine ; Hydrolysis ; Proteins ; Hydrogen cyanide ; Predators ; Irritation ; Glucosides
    ISSN: 2045-2322
    E-ISSN: 2045-2322
    Source: Nature Open Access
    Source: Academic Search Ultimate
    Source: PubMed Central
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  • 5
    Language: English
    In: Ecology and evolution, 2018-08, Vol.8 (16), p.8055-8075
    Description: Due to its fundamental role in shaping host selection behavior, we have analyzed the chemosensory repertoire of Chrysomela lapponica. This specialized leaf beetle evolved distinct populations which shifted from the ancestral host plant, willow (Salix sp., Salicaceae), to birch (Betula rotundifolia, Betulaceae). We identified 114 chemosensory candidate genes in adult C. lapponica: 41 olfactory receptors (ORs), eight gustatory receptors, 17 ionotropic receptors, four sensory neuron membrane proteins, 32 odorant binding proteins (OBPs), and 12 chemosensory proteins (CSP) by RNA‐seq. Differential expression analyses in the antennae revealed significant upregulation of one minus‐C OBP (ClapOBP27) and one CSP (ClapCSP12) in the willow feeders. In contrast, one OR (ClapOR17), four minus‐C OBPs (ClapOBP02, 07, 13, 20), and one plus‐C OBP (ClapOBP32) were significantly upregulated in birch feeders. The differential expression pattern in the legs was more complex. To narrow down putative ligands acting as cues for host discrimination, the relative abundance and diversity of volatiles of the two host plant species were analyzed. In addition to salicylaldehyde (willow‐specific), both plant species differed mainly in their emission rate of terpenoids such as (E,E)‐α‐farnesene (high in willow) or 4,8‐dimethylnona‐1,3,7‐triene (high in birch). Qualitatively, the volatiles were similar between willow and birch leaves constituting an “olfactory bridge” for the beetles. Subsequent structural modeling of the three most differentially expressed OBPs and docking studies using 22 host volatiles indicated that ligands bind with varying affinity. We suggest that the evolution of particularly minus‐C OBPs and ORs in C. lapponica facilitated its host plant shift via chemosensation of the phytochemicals from birch as novel host plant. We test whether host plant shift of a specialist phytophagous beetle (Chrysomela lapponica) is accompanied by the modulation of its chemosensory repertoire. We present a comparative and tissue‐specific transcriptomic inventory of chemosensory genes (OR, OBP, CSP, GR, IR, and SNMP) from two distinct populations that differ in their preference for either willow or birch leaves. Combined with leaf volatile analyses and protein modeling, our results indicate that changes in the expression of mainly minus‐C OBPs and ORs are associated with host shift.
    Subject(s): transcriptomics ; host plant shift ; structural protein modeling ; chemosensory genes ; Chrysomela lapponica ; leaf volatile analysis ; Original Research
    ISSN: 2045-7758
    E-ISSN: 2045-7758
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
    Source: ProQuest Central
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  • 6
    Language: English
    In: Journal für Ornithologie, 2010-01, Vol.151 (1), p.113-121
    Description: Niche partitioning has been examined in breeding bird communities and in winter quarters, but has received less attention when comparing a resident breeder and migrants during spring. Here, such an assemblage of species of the same genus (Oenanthe) and guild were analysed on the Mediterranean island of Cyprus. Northern Wheatear O. oenanthe and Eastern Black-Eared Wheatear O. hispanica melanoleuca were migrants, while Cyprus Wheatear O. cypriaca was resident. Migrant wheatears were more common in open habitats without trees, with a lower proportion of vegetation in the 10 cm layer, less tree and bush cover, a higher proportion of herbaceous layer, and a higher amount of bare areas. By using a discriminant function, we found that O. oenanthe was least tolerant towards a high proportion of bush/tree cover, and O. cypriaca was most tolerant, with O. h. melanoleuca in between. Also, O. oenanthe tolerated the least proportion of vegetation in the lowest layer, and O. h. melanoleuca the highest. O. oenanthe hunted more often by hop-and-peck and O. cypriaca more often used sallying and perch-and-pounce. O. oenanthe was the most ground-dwelling species with low perch heights and highest number of hops per minute and hops per movement, while O. cypriaca was the most arboreal species with the highest perches. Mean foraging rate did not differ between the species. A principal component analysis followed by a discriminant function showed that O. cypriaca has a high amount of aerial sallying and perch-pounce hunting behaviour with fewer hops, while O. oenanthe represents the contrary with hop-and-peck movements on the ground and with fewer flights. The data further indicate a clearer separation between O. oenanthe and O. cypriaca while O. h. melanoleuca lies in between utilising both foraging modes.
    Subject(s): Life Sciences ; Foraging mode ; Breeder–migrant assemblage ; Breeding habitat preference ; Zoology ; Coexistence ; Evolutionary Biology ; Animal Ecology ; Niche partitioning ; Birds ; Universities and colleges ; Analysis ; Pharmacy ; Hunting ; Breeding ; Niche overlap ; Vegetation ; Predatory behavior ; Principal components analysis ; Species
    ISSN: 0021-8375
    ISSN: 2193-7192
    E-ISSN: 1439-0361
    E-ISSN: 2193-7206
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
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  • 7
    Language: English
    In: Royal Society open science, 2017-06, Vol.4 (6), p.170262-170262
    Description: Low molecular weight compounds are typically used by insects and plants for defence against predators. They are often stored as inactive β-glucosides and kept separate from activating β-glucosidases. When the two components are mixed, the β-glucosides are hydrolysed releasing toxic aglucones. Cyanogenic plants contain cyanogenic glucosides and release hydrogen cyanide due to such a well-characterized two-component system. Some arthropods are also cyanogenic, but comparatively little is known about their system. Here, we identify a specific β-glucosidase ( involved in cyanogenesis from larvae of (Lepidoptera, Zygaenidae), and analyse the spatial organization of cyanide release in this specialized insect. High levels of mRNA and protein were found in haemocytes by transcriptomic and proteomic profiling. Heterologous expression in insect cells showed that ZfBGD2 hydrolyses linamarin and lotaustralin, the two cyanogenic glucosides present in . Linamarin and lotaustralin as well as cyanide release were found exclusively in the haemoplasma. Phylogenetic analyses revealed that clusters with other insect β-glucosidases, and correspondingly, the ability to hydrolyse cyanogenic glucosides catalysed by a specific β-glucosidase evolved convergently in insects and plants. The spatial separation of the β-glucosidase ZfBGD2 and its cyanogenic substrates within the haemolymph provides the basis for cyanide release in . This spatial separation is similar to the compartmentalization of the two components found in cyanogenic plant species, and illustrates one similarity in cyanide-based defence in these two kingdoms of life.
    Subject(s): caterpillar ; cyanogenic glucoside ; β-glucosidase ; haemolymph ; cyanogenesis
    ISSN: 2054-5703
    E-ISSN: 2054-5703
    Source: PubMed Central
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  • 8
    Language: English
    In: Natural product reports, 2017-05-10, Vol.34 (5), p.478-483
    Description: Contact chemosensation, or tasting, is a complex process governed by nonvolatile phytochemicals that tell host-seeking insects whether they should accept or reject a plant. During this process, insect gustatory receptors (GRs) contribute to deciphering a host plant's metabolic code. GRs recognise many different classes of nonvolatile compounds; some GRs are likely to be narrowly tuned and others, broadly tuned. Although primary and/or secondary plant metabolites influence the insect's feeding choice, their decoding by GRs is challenging, because metabolites in planta occur in complex mixtures that have additive or inhibitory effects; in diverse forms composed of structurally unrelated molecules; and at different concentrations depending on the plant species, its tissue and developmental stage. Future studies of the mechanism of insect herbivore GRs will benefit from functional characterisation taking into account the spatio-temporal dynamics and diversity of the plant's metabolome. Metabolic information, in turn, will help to elucidate the impact of single ligands and complex natural mixtures on the insect's feeding choice. Contact chemosensation, or tasting, enables insect herbivores to identify nonvolatile metabolites in complex mixtures present in plants. The interplay of primary and secondary plant metabolites with gustatory receptors is outlined.
    Subject(s): Phytochemicals - chemistry ; Insecta - physiology ; Herbivory ; Molecular Structure ; Animals ; Phytochemicals - pharmacology ; Chemistry
    ISSN: 0265-0568
    E-ISSN: 1460-4752
    Source: Alma/SFX Local Collection
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  • 9
    Language: English
    In: PloS one, 2014, Vol.9 (3), p.e91337-e91337
    Description: Cyanogenic glucosides (CNglcs) are widespread plant defence compounds that release toxic hydrogen cyanide by plant β-glucosidase activity after tissue damage. Specialised insect herbivores have evolved counter strategies and some sequester CNglcs, but the underlying mechanisms to keep CNglcs intact during feeding and digestion are unknown. We show that CNglc-sequestering Zygaena filipendulae larvae combine behavioural, morphological, physiological and biochemical strategies at different time points during feeding and digestion to avoid toxic hydrolysis of the CNglcs present in their Lotus food plant, i.e. cyanogenesis. We found that a high feeding rate limits the time for plant β-glucosidases to hydrolyse CNglcs. Larvae performed leaf-snipping, a minimal disruptive feeding mode that prevents mixing of plant β-glucosidases and CNglcs. Saliva extracts did not inhibit plant cyanogenesis. However, a highly alkaline midgut lumen inhibited the activity of ingested plant β-glucosidases significantly. Moreover, insect β-glucosidases from the saliva and gut tissue did not hydrolyse the CNglcs present in Lotus. The strategies disclosed may also be used by other insect species to overcome CNglc-based plant defence and to sequester these compounds intact.
    Subject(s): Herbivory ; Saliva - enzymology ; Behavior, Animal ; Hydrolysis ; Animals ; Cellulases - metabolism ; Cyanides - chemistry ; Glucosides - chemistry ; Larva - enzymology ; Plants - chemistry ; Plant Leaves - enzymology ; Moths - enzymology ; Intestines - enzymology ; Physiological aspects ; Nitriles ; Defense industry ; Food processing plants ; Hydrogen ; Biology ; Enzymes ; Environmental science ; Laboratories ; Morphology ; Butterflies & moths ; Biochemistry ; Herbivores
    ISSN: 1932-6203
    E-ISSN: 1932-6203
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 10
    Language: English
    In: Journal of experimental biology, 2018-07-19, Vol.221
    Description: Optical imaging of gene expression by fluorescence hybridisation (FISH) in insects is often impeded by their pigmented cuticle. Since most chemical bleaching agents are incompatible with FISH, we developed a RNA interference-based method for clearing cuticular pigmentation which enables using whole-mount body appendages for RNA FISH. Silencing or in two leaf beetles species ( ) cleared their pigmented cuticle and decreased light absorbance. Subsequently, intact appendages (palps, antennae, legs) from RNAi-cleared individuals were used to image expression and spatial distribution of antisense mRNA of two chemosensory genes (gustatory receptor, odorant-binding protein). Imaging did neither work for RNAi-controls due to retained pigmentation, nor for FISH-controls (sense mRNA). Several bleaching agents were incompatible with FISH, either due to degradation of RNA, lack of clearing efficacy or long incubation times. Overall, silencing pigmentation genes is a significant improvement over bleaching agents enabling FISH in intact appendages.
    ISSN: 0022-0949
    E-ISSN: 1477-9145
    Source: HighWire Press (Free Journals)
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