In the present study we further investigate functions of the neural cell adhesion molecule (NCAM) in the mature central nervous system and its implications for animal behaviour. To this end we generated transgenic mice expressing the major NCAM isoform with the largest cytoplasmic domain, NCAM180, under control of a promoter for the small form neurofilament gene. Transgenic mice were also bred with mice deficient in endogenous NCAM (Ncam-/- mice) so that effects of NCAM180 could be analysed in the presence and absence of endogenous NCAM. While overexpression of transgenic NCAM180 was without apparent behavioural or morphological effect, its expression in Ncam-/- mice counteracted NCAM ablation-induced aggressive, anxiety-like and antidepressant-like behaviour. It furthermore prevented a hypersensitivity of Ncam-/- mice to the anxiolytic serotonin1A (5-HT1A) receptor agonist buspirone. Such recovery of emotional behaviour and behavioural 5-HT1A response occurred in spite of misdevelopment of the olfactory bulb and hippocampus that is characteristic of Ncam-/- mice, and without an apparent change in the expression of 5-HT1A binding sites in the brain. Hippocampus- and amygdala-dependent learning, though disturbed in Ncam-/- mice, remained unaffected by the transgenic NCAM180. We suggest an involvement of NCAM180-mediated cell recognition processes in the serotonergic modulation of emotional behaviour in adult mice.
cProtein import into complex plastids of red algal origin is a multistep process including translocons of different evolutionary origins. The symbiont-derived ERAD-like machinery (SELMA), shown to be of red algal origin, is proposed to be the transport system for preprotein import across the periplastidal membrane of heterokontophytes, haptophytes, cryptophytes, and apicomplexans. In contrast to the canonical endoplasmic reticulum-associated degradation (ERAD) system, SELMA translocation is suggested to be uncoupled from proteasomal degradation. We investigated the distribution of known and newly identified SELMA components in organisms with complex plastids of red algal origin by intensive data mining, thereby defining a set of core components present in all examined organisms. These include putative pore-forming components, a ubiquitylation machinery, as well as a Cdc48 complex. Furthermore, the set of known 20S proteasomal components in the periplastidal compartment (PPC) of diatoms was expanded. These newly identified putative SELMA components, as well as proteasomal subunits, were in vivo localized as PPC proteins in the diatom Phaeodactylum tricornutum. The presented data allow us to speculate about the specific features of SELMA translocation in contrast to the canonical ERAD system, especially the uncoupling of translocation from degradation.O rganelles such as plastids, including those of secondary origin, almost completely rely on protein import from the host cytosol (46, 65). The structure of complex plastids, surrounded by three or four membranes required, in contrast to primary plastids, the evolution of several additional protein transport mechanisms. Complex plastids arose through secondary endosymbiosis, a process which describes the engulfment of a former free-living eukaryotic alga into a eukaryotic host cell (32, 33). During evolution, the symbiont was subsequently reduced in terms of compartmentalization and genome size to an organelle strictly dependent on the host cell (16,32). Different types of secondary plastids exist in a very broad range of algae and protists, which can be distinguished based on their evolutionary origin (e.g., a red or green alga derived symbiont), as well as on the amount of cellular reduction inside the host cell. Our understanding of the evolution of organisms harboring a secondary plastid of red algal origin has changed in the last few years. According to the chromalveolate hypothesis, six major lineages were grouped together to be of monophyletic origin: cryptophytes, haptophytes, heterokontophytes, peridinincontaining dinoflagellates, apicomplexans, and the non-plastidcontaining ciliates, as well as several smaller lineages related to some chromalveolate members (15, 41). However, recent phylogenetic analyses have given rise to extended theories about the evolution of the lineages with a red algal endosymbiont, including serial endosymbiotic events with secondary, as well as tertiary, endosymbioses (21,22,26,27,56,61,71,75).It has been shown that the lineages wi...
Algae with secondary plastids such as diatoms maintain two different eukaryotic cytoplasms. One of them, the so-called periplastidal compartment (PPC), is the naturally minimized cytoplasm of a eukaryotic endosymbiont. In order to investigate the protein composition of the PPC of diatoms, we applied knowledge of the targeting signals of PPC-directed proteins in searches of the genome data for proteins acting in the PPC and proved their in vivo localization via expressing green fluorescent protein (GFP) fusions. Our investigation increased the knowledge of the protein content of the PPC approximately 3-fold and thereby indicated that this narrow compartment was functionally reduced to some important cellular functions with nearly no housekeeping biochemical pathways.
In this study we describe changes of gene expression that occur in the basolateral complex of the mouse amygdala (BLA) during the formation of fear memory. Through the combination of a behavioral training scheme with polymerase chain reaction-based expression analysis (subtractive hybridization and virtual Northern analysis) we were able to identify various gene products that are increased in expression after Pavlovian fear conditioning and are of potential significance for neural plasticity and information storage in the amygdala. In particular, a key enzyme of monoamine metabolism, aldehyde reductase, and the protein sorting and ubiquitination factor Praja1, showed pronounced and learning-specific induction six hours after fear conditioning training. Aldehyde reductase and Praja1, including a novel alternatively spliced isoform termed Praja1a, were induced in the BLA depending on the emotional stimulus presented and showed different expression levels in response to associative conditioning, training stress, and experience of conditioned fear. Stress and fear were further found to induce various signal transduction factors (transthyretin, phosphodiesterase1, protein kinase inhibitor-␣) and structural reorganization factors (e.g., E2-ubiquitin conjugating enzyme, neuroligin1, actin, UDP-galactose transporter) during training. Our results show that the formation of Pavlovian fear memory is associated with changes of gene expression in the BLA, which may contribute to neural plasticity and the processing of information about both conditioned and unconditioned fear stimuli.[The Praja1a sequence has been deposited in GenBank data base under accession no. AF335250.]
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.