Synaptic dimorphism in Onychophoran cephalic ganglia

Peña-Contreras, Zulma; Mendoza-Briceño, Rosa Virginia; Miranda-Contreras, Leticia; Palacios-Prü, Ernesto

doi:10.15517/rbt.v55i1.6078

Cited by 4 publications

(5 citation statements)

References 23 publications

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“…With electron microscopy, some of the postsynaptic processes shown in figures look spine-like with little internal structure, but others have mitochondria or other organelles. Interestingly, it is common to find a postsynaptic, flat ER cistern (Schürmann 1978; Strausfeld et al 2006; Peña-Contreras et al 2007), as we noted earlier for some synapses in flies. In some unusual synapses, the postsynaptic process looks flattened and plate-like, with the PSD along the side (Strausfeld et al 2006); mitochondria may be present on the edges but are excluded from the center of the thinnest “plates.” They somewhat resemble half of a crest synapse (described later in this review).…”

Section: The Predominance Of the Non-invaginating Dendritic Spine Synsupporting

confidence: 78%

The Diversity of Spine Synapses in Animals

et al. 2016

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Here we examine the structure of the various types of spine synapses throughout the animal kingdom. Based on available evidence, we suggest that there are two major categories of spine synapses: invaginating and non-invaginating, with distributions that vary among different groups of animals. In the simplest living animals with definitive nerve cells and synapses, the cnidarians and ctenophores, most chemical synapses do not form spine synapses. But some cnidarians have invaginating spine synapses, especially in photoreceptor terminals of motile cnidarians with highly complex visual organs, and also in some mainly sessile cnidarians with rapid prey capture reflexes. This association of invaginating spine synapses with complex sensory inputs is retained in the evolution of higher animals in photoreceptor terminals and some mechanoreceptor synapses. In contrast to invaginating spine synapse, non-invaginating spine synapses have been described only in animals with bilateral symmetry, heads and brains, associated with greater complexity in neural connections. This is apparent already in the simplest bilaterians, the flatworms, which can have well-developed non-invaginating spine synapses in some cases. Non-invaginating spine synapses diversify in higher animal groups. We also discuss the functional advantages of having synapses on spines and more specifically, on invaginating spines. And finally we discuss pathologies associated with spine synapses, concentrating on those systems and diseases where invaginating spine synapses are involved.

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Section: The Predominance Of the Non-invaginating Dendritic Spine Synsupporting

confidence: 78%

The Diversity of Spine Synapses in Animals

et al. 2016

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“…To date, the functional Gray synapse concept is still in use to identify excitatory and inhibitory synapses in the central nervous system (CNS) of both vertebrates and invertebrates, the Type I/II and asymmetric/symmetric terminology being used interchangeable (e.g., Barbaresi, 2010; Cid‐Pellitero and Garzón, in press; Farb et al, 2010; Omelchenko and Sesack, 2010; Peña‐Contreras et al, 2007; Steward, 2000). However, Gray's concept has never been fully confirmed, and in recent years, due to the advancement of sophisticated approaches like ultrastructural immunocytochemistry, single cell electrophysiology, and proteomics, a wealth of new data have further clarified various aspects of the relation between synapse structure and function.…”

Section: Introductionmentioning

confidence: 99%

The gray area between synapse structure and function—Gray's synapse types I and II revisited

Klemann

Roubos

2011

Synapse

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On the basis of ultrastructural parameters, the concept was formulated that asymmetric Type I and symmetric Type II synapses are excitatory and inhibitory, respectively. This "functional Gray synapses concept" received strong support from the demonstration of the excitatory neurotransmitter glutamate in Type I synapses and of the inhibitory neurotransmitter γ-aminobutyric acid in Type II synapses, and is still frequently used in modern literature. However, morphological and functional evidence has accumulated that the concept is less tenable. Typical features of synapses like shape and size of presynaptic vesicles and synaptic cleft and presence of a postsynaptic density (PsD) do not always fit the postulated (excitatory/inhibitory) function of Gray's synapses. Furthermore, synapse function depends on postsynaptic receptors and associated signal transduction mechanisms rather than on presynaptic morphology and neurotransmitter type. Moreover, the notion that many synapses are difficult to classify as either asymmetric or symmetric has cast doubt on the assumption that the presence of a PsD is a sign of excitatory synaptic transmission. In view of the morphological similarities of the PsD in asymmetric synapses with membrane junctional structures such as the zonula adherens and the desmosome, asymmetric synapses may play a role as links between the postsynaptic and presynaptic membrane, thus ensuring long-term maintenance of interneuronal communication. Symmetric synapses, on the other hand, might be sites of transient communication as takes place during development, learning, memory formation, and pathogenesis of brain disorders. Confirmation of this idea might help to return the functional Gray synapse concept its central place in neuroscience.

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“…The membrane compartment is also present in myelin of the copepod ( Bestiolina similis ), in brain neurons of Drosophila , and in Onychophoran cephalic ganglia. 29-31 They are thought to function as smooth endoplasmic reticulum, and could play a role in responses to Ca 2+ influx, synthesis of transmembrane proteins, and neurotransmitter release during neuronal communication. 32 …”

Section: Discussionmentioning

confidence: 99%

Gliocyte and synapse analyses in cerebral ganglia of the Chinese mitten crab, Eriocheir sinensis: ultrastructural study

Zhang

Zhong

et al. 2016

Eur J Histochem

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The Chinese mitten crab Eriocheir sinensis is an economically important aquatic species in China. Many studies on gene structure, breeding, and diseases of the crab have been reported. However, knowledge about the organization of the nerve system of the crab remains largely unknown. To study the ultrastructure of the cerebral ganglia of E. sinensis and to compare the histological findings regarding the nerve systems of crustaceans, the cerebral ganglia were observed by transmission electron microscopy. The results showed that four types of gliocytes, including type I, II, III, and IV gliocytes were located in the cerebral ganglia. In addition, three types of synapses were present in the cerebral ganglia, including unidirectional synapses, bidirectional synapses, and combined type synapses.

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Synaptic dimorphism in Onychophoran cephalic ganglia

Cited by 4 publications

References 23 publications

The Diversity of Spine Synapses in Animals

The Diversity of Spine Synapses in Animals

The gray area between synapse structure and function—Gray's synapse types I and II revisited

Gliocyte and synapse analyses in cerebral ganglia of the Chinese mitten crab, Eriocheir sinensis: ultrastructural study

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