The neuromuscular junction is the chemical synapse where motor neurons communicate with skeletal muscle fibers. Whereas vertebrates and many invertebrates use acetylcholine as transmitter at the ...neuromuscular junction, in those arthropods examined up to now, glutamate and GABA are used instead. With respect to taxon sampling in a phylogenetic context, there is, however, only a limited amount of data available, focusing mainly on crustaceans and hexapods, and neglecting other, arthropod groups. Here we investigate the neurotransmitter equipment of neuromuscular synapses of a myriapod,
, using immunofluorescence and histochemical staining methods.
Glutamate and GABA could be found colocalised with synapsin in synaptic boutons of body wall and leg muscles of
. Acetylcholinesterase activity as a marker for cholinergic synapses was found abundantly in the central nervous system and also in some peripheral nerves, but not at neuromuscular junctions. Furthermore, a large number of leg sensory neurons displayed GABA-immunofluorescence and was also labeled with an antiserum against the GABA-synthesizing enzyme, glutamate decarboxylase.
Our data indicate that glutamate and GABA are neurotransmitters at
neuromuscular junctions, whereas acetylcholine is very unlikely to play a role here. This is in line with the concept of glutamate as excitatory and GABA as the main inhibitory neuromuscular transmitters in euarthropods. Furthermore, we have, to our knowledge for the first time, localized GABA in euarthropod leg sensory neurons, indicating the possibility that neurotransmitter panel in arthropod sensory systems may be far more extensive than hitherto assumed.
Myriapoda of Canada Langor, David W; deWaard, Jeremy R; Snyder, Bruce A
ZooKeys,
2019, Volume:
819, Issue:
819
Journal Article
Peer reviewed
Open access
The currently documented fauna of described species of myriapods in Canada includes 54 Chilopoda, 66 Diplopoda, 23 Pauropoda, and two Symphyla, representing increases of 24, 23, 23, and one species, ...respectively, since 1979. Of the 145 myriapod species currently documented, 40 species are not native to Canada. The myriapods have not been well documented with DNA barcodes and no barcodes are available for Pauropoda. It is conservatively estimated that at least 93 additional myriapods species will be discovered in Canada: Chilopoda (40), Diplopoda (29), Pauropoda (17), and Symphyla (seven). In general, there is a serious dearth of knowledge about myriapods in Canada, and systematics research and surveys continue to be needed to help document the diversity and distribution of these groups in the country.
Soil food webs are particularly important in terrestrial systems, but studying them is difficult. Here we report on the first study to apply a molecular approach to identify species‐specific trophic ...interactions in below‐ground food webs. To identify the invertebrate predator guild of the garden chafer Phyllopertha horticola (Coleoptera, Scarabaeidae) whose root‐feeding larvae can be highly abundant in grasslands, a specific DNA marker was developed. It allowed detection of P. horticola egg and white grub meals within the gut content of Poecilus versicolor (Coleoptera, Carabidae) larvae for up to 24 h post‐feeding. Soil samples from an alpine grassland revealed a diverse below‐ground macro‐invertebrate community with earthworms, P. horticola larvae, and centipedes as well as beetle larvae as the most abundant detritivores, herbivores, and predators, respectively. Garden chafer DNA was detected in 18.6%, 4.1%, and 4.4% of field‐collected Geophilidae (n = 124), beetle larvae (n = 159), and Lithobiidae (n = 49), respectively. We conclude that most of the investigated predators actively preyed on P. horticola, as secondary predation is unlikely to be detected in below‐ground systems. Moreover, scavenging most likely contributes only to a small percentage of the revealed trophic links due to the low availability of carrion. Sampling date did not influence prey detection rates, indicating that both P. horticola eggs and larvae were preyed on. Only 2.7% of the below‐ground predators tested positive for earthworms, an alternative, highly abundant prey, suggesting that P. horticola represents an important prey source for centipedes and predatory beetle larvae during summer within the soil food web.
Haemocyanins (Hcs) are copper-containing, respiratory proteins that occur in the haemolymph of many arthropod species. Here, we report the presence of Hcs in the chilopode Myriapoda, demonstrating ...that these proteins are more widespread among the Arthropoda than previously thought. The analysis of transcriptome of
reveals the presence of two distinct subunits of Hc, where the signal peptide is present, and six of prophenoloxidase (PPO), where the signal peptide is absent, in the 75 kDa range. Size exclusion chromatography profiles indicate different quaternary organization for Hc of both species, which was corroborated by TEM analysis:
Hc is a 6 × 6-mer and
Hc is a 3 × 6-mer, which resembles the half-structure of the 6 × 6-mer but also includes the presence of phenoloxidases, since the 1 × 6-mer quaternary organization is commonly associated with hexamers of PPO. Studies with Chelicerata showed that PPO activity are exclusively associated with the Hcs. This study indicates that
may have different proteins playing oxygen transport (Hc) and PO function, both following the hexameric oligomerization observed in Hcs.
The invertebrates of the Macocha Abyss, Moravian Karst, Czech Republic, were collected in 2007–2008 and 222 species were identified in total. The relative abundance of individual taxa of land snails, ...harvestmen, pseudoscorpions, spiders, millipedes, centipedes, terrestrial isopods, beetles, and ants was evaluated. The cold-adapted mountain and subterranean species inhabit the bottom and lower part of the abyss, whereas the sun-exposed rocky margins were inhabited by thermophilous species. Macocha harbors several threatened species that are absent or very rare in the surrounding habitats. In the forest landscape, the Macocha Abyss represents a natural habitat with a distinct microclimatic gradient, and is an excellent refuge area for psychrophilous as well as thermophilous species, which significantly contributes to maintenance of landscape biodiversity. Key words: Ants, centipedes, beetles, biodiversity, harvestmen, land snails, light hole, millipedes, pseudoscorpions, terrestrial ispods, spiders. Nevretenčarji brezna Macoha (Moravski kras, Republika Češka) Med vzorčenjem v letih 2007 in 2008 smo v jami Macoha določili 222 vrst nevretenčarjev. Ovrednotili smo relativno pogostost posameznih taksonov polžev, suhih južin, paščipalcev, pajkov, stonog, kopenskih enakonožcev, hroščev in mravelj. Na mraz prilagojene gorske in podzemeljske vrste naseljujejo dno in spodnji del brezna, toploljubne vrste pa naseljujejo kamnite površine soncu izpostavljenega roba. V Macohi je več ogroženih vrst, ki jih sicer v okoliški pokrajini ne najdemo. Kot habitat s specifično mikroklimo je Macoha izjemno zatočišče za vlagoljubne in toploljubne vrste, ki pomembno prispevajo k vzdrževanju biotske raznovrstnosti v pokrajini. Ključne besede: Mravlje, stonoge, hrošči, suhe južine, kopenski polži, stonoge, psevdoškorpijoni, kopenski enakonožci, pajki, biotska raznovrstnost.
The salivary glands (mandibular epidermal glands) of adult males and females of Lithobius forficatus (Myriapoda, Chilopoda) were isolated during spring, summer and autumn. In addition, the organs ...were isolated at different times of the day – at about 12:00 (noon) and about 00:00 (midnight). The ultrastructure of these organs depending on seasonal and circadian rhythms was analyzed using transmission and scanning electron microscopy and histochemical methods. The paired salivary glands of L. forficatus are situated in the vicinity of the foregut and they are formed by numerous acini that are surrounded by the fat body, hemocytes and tracheolae. The salivary glands are composed of a terminal acinar component and a system of tubular ducts that are lined with a cuticle. The glandular part is composed of secretory epithelial cells that are at various stages of their secretory activity. The saliva that is produced by the secretory cells of the acini is secreted into the salivary ducts, which are lined with a simple epithelium that is based on the non-cellular basal lamina. The ultrastructural variations suggest that salivary glands function differently depending on seasonal rhythms and prepare the animal for overwintering. Therefore, the salivary glands of the centipedes that were analyzed participate in the accumulation of proteins, lipids and polysaccharides during the spring, summer and autumn. Subtle differences in the ultrastructure of the secretory cells of the salivary glands during the circadian cycle must be related to the physiological reactions of the organism. The salivary ducts showed no differences in the specimens that were analyzed during the day/night cycle or during the seasonal cycle.
•Salivary glands are formed by acini surrounded with the fat body, hemocytes and tracheole.•Acini are formed by the secretory cells which are at various stages of secretory activity.•Salivary glands function according to seasonal rhythms.•Subtle differences occur in the salivary glands during circadian cycle.•No differences appear between males and females.
The biodiversity crisis we live in, marked by high extinction rates, requires well-planned conservation efforts. To overcome this issue, red lists of threatened species are recognized as the main ...objective approach for evaluating the conservation status of species and therefore guiding conservation priorities. This work focuses on the Myriapoda (Chilopoda and Diplopoda) species listed in the Brazilian red list of fauna to enable discussion of the practical implications of red lists for conservation. Almost all myriapods assessed are endemic to Brazil (99 %) and 73 % are known from subterranean habitats only. Despite of 33 % being recorded from protected areas (PAs), downgrading, degazettement or downsizing of PAs and intense and unregulated ecotourism represent great threats. The PAs network in Brazil tends to fail in conserving myriapod species. The number of data deficient species (42 %) states the need of investing in ecological and taxonomic studies about the group, in order to fill in important knowledge gaps in species assessments nationally and globally. In this work we show that there is a lack of communication between national and global agencies concerning red lists, which results in a significant loss for science and for conservation. Despite investing in national and state red lists, individual countries must take the final step of submitting its data to IUCN global database, as significant international funding is available for IUCN red listed species conservation. Being one of the most diverse countries in the world, and facing the biggest cuts ever on national science funding, losing these important funding opportunities is a huge loss for Brazilian biodiversity conservation and for science. This study raises awareness on subterranean habitats conservation, due to its high endemism and fragility. Since the first edition of the Brazilian Red List in 1968, centipedes are now included for the first time, and millipedes for the second time. The presence of these myriapods in the list brings attention to the group, which usually receives little or no attention in conservation programs and environmental impact assessments. Rather than a specific case for Myriapoda and for Brazil, the points discussed here can be related to arthropods and the tropics, as the most biodiverse countries are emerging economies facing similar challenges in PAs network management, species extinction risks and science funding.
The Western Ghats (WG) of south India, a global biodiversity hotspot, has experienced complex geological history being part of Gondwana landmass and encountered extensive volcanic activity at the end ...of Cretaceous epoch. It also has a climatically and topographically heterogeneous landscape. Thus, the WG offer a unique setting to explore the influence of ecological and geological processes on the current diversity and distribution of its biota. To this end, three explicit biogeographical scenarios were hypothesized to evaluate the distribution and diversification of wet evergreen species of the WG – (1) southern WG was a refuge for the wet evergreen species during the Cretaceous volcanism, (2) phylogenetic breaks in the species phylogeny would correspond to geographic breaks (i.e., the Palghat gap) in the WG, and (3) species from each of the biogeographic subdivisions within the WG would form distinct clades. These hypotheses were tested on the centipede genus Digitipes from the WG which is known to be an ancient, endemic, and monophyletic group. The Digitipes molecular phylogeny was subjected to divergence date estimation using Bayesian approach, and ancestral areas were reconstructed using parsimony approach for each node in the phylogeny. Ancestral‐area reconstruction suggested 13 independent dispersal events to explain the current distribution of the Digitipes species in the WG. Among these 13 dispersals, two dispersal events were at higher level in the Digitipes phylogeny and were from the southern WG to the central and northern WG independently in the Early Paleocene, after the Cretaceous Volcanism. The remaining 11 dispersal events explained the species’ range expansions of which nine dispersals were from the southern WG to other biogeographic subdivisions in the Eocene‐Miocene in the post‐volcanic periods where species‐level diversifications occurred. Taken together, these results suggest that southern WG might have served as a refuge for Digitipes species during Cretaceous volcanism.
We suggest that the southern Western Ghats of India acted as a refuge during the Cretaceous Volcanism to a group of terrestrial predatory invertebrates inhabiting the tropical wet forests of the Western Ghats.
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