Abstract The hippocampus has a pivotal role in learning and in the formation and consolidation of memory and is critically involved in the regulation of emotion, fear, anxiety, and stress. Studies of ...the hippocampus have been central to the study of memory in humans and in recent years, the regional specialization and organization of hippocampal functions have been elucidated in experimental models and in human neurological and psychiatric diseases. The hippocampus has long been considered a classic model for the study of neuroplasticity as many examples of synaptic plasticity such as long-term potentiation and -depression have been identified and demonstrated in hippocampal circuits. Neuroplasticity is the ability to adapt and reorganize the structure or function to internal or external stimuli and occurs at the cellular, population, network or behavioral level and is reflected in the cytological and network architecture as well as in intrinsic properties of hippocampal neurons and circuits. The high degree of hippocampal neuroplasticity might, however, be also negatively reflected in the pronounced vulnerability of the hippocampus to deleterious conditions such as ischemia, epilepsy, chronic stress, neurodegeneration and aging targeting hippocampal structure and function and leading to cognitive deficits. Considering this framework of plasticity and vulnerability, we here review basic principles of hippocampal anatomy and neuroplasticity on various levels as well as recent findings regarding the functional organization of the hippocampus in light of the regional vulnerability in Alzheimer’s disease, ischemia, epilepsy, neuroinflammation and aging.
Diachasmimorpha longicaudata is a hymenopteran fruit fly endoparasitoid. Females of this species find their hosts for oviposition by using complex sensorial mechanisms in response to physical and ...chemical stimuli associated with the host and host habitat. Ecological and behavioral aspects related to host-seeking behavior for oviposition have been extensively studied in D. longicaudata, including the identification of volatile organic compounds acting as attractants to females. In this sense, molecular mechanisms of chemoreception have been explored in this species, including a preliminary characterization of odorant-binding proteins (OBPs), chemosensory proteins (CSPs) and odorant receptors (ORs), among other proteins. Functional assays on OBP and CSP have been conducted as a first approach to identify molecular mechanisms associated with the female host-seeking behavior for oviposition. The aims of the present study were to identify the D. longicaudata sensory gene repertoire expressed in the antenna of sexually mature and mated individuals of both sexes, and subsequently, characterize transcripts differentially expressed in the antennae of females to identify candidate genes associated with the female host-seeking behavior for oviposition.
A total of 33,745 predicted protein-coding sequences were obtained from a de novo antennal transcriptome assembly. Ten sensory-related gene families were annotated as follows: 222 ORs, 44 ionotropic receptors (IRs), 25 gustatory receptors (GRs), 9 CSPs, 13 OBPs, 2 ammonium transporters (AMTs), 8 pickpocket (PPKs) receptors, 16 transient receptor potential (TRP) channels, 12 CD36/SNMPs and 3 Niemann-Pick type C2 like proteins (NPC2-like). The differential expression analysis revealed 237 and 151 transcripts up- and downregulated, respectively, between the female and male antennae. Ninety-seven differentially expressed transcripts corresponded to sensory-related genes including 88 transcripts being upregulated (87 ORs and one TRP) and nine downregulated (six ORs, two CSPs and one OBP) in females compared to males.
The sensory gene repertoire of D. longicaudata was similar to that of other taxonomically related parasitoid wasps. We identified a high number of ORs upregulated in the female antenna. These results may indicate that this gene family has a central role in the chemoreception of sexually mature females during the search for hosts and host habitats for reproductive purposes.
The communication and reproduction of insects are driven by chemical sensing. During this process, chemical compounds are transported across the sensillum lymph to the sensory neurons assisted by ...different types of soluble binding proteins: odorant-binding proteins (OBPs); chemosensory proteins (CSPs); some members of ML-family proteins (MD-2 (myeloid differentiation factor-2)-related Lipid-recognition), also known as NPC2-like proteins. Potential transcripts involved in chemosensing were identified by an in silico analysis of whole-body female and male transcriptomes of the parasitic wasp Diachasmimorpha longicaudata. This analysis facilitated the characterization of fourteen OBPs (all belonging to the Classic type), seven CSPs (and two possible isoforms), and four NPC2-like proteins. A differential expression analysis by qPCR showed that eleven of these proteins (CSPs 2 and 8, OBPs 2, 3, 4, 5, 6, 9, 10, and 11, and NPC2b) were over-expressed in female antenna and two (CSP 1 and OBP 12) in the body without antennae. Foraging behavior trials (linked to RNA interference) suggest that OBPs 9, 10, and 11 are potentially involved in the female orientation to chemical cues associated with the host. OBP 12 seems to be related to physiological processes of female longevity regulation. In addition, transcriptional silencing of CSP 3 showed that this protein is potentially associated with the regulation of foraging behavior. This study supports the hypothesis that soluble binding proteins are potentially linked to fundamental physiological processes and behaviors in D. longicaudata. The results obtained here contribute useful information to increase the parasitoid performance as a biological control agent of fruit fly pest species.
Neuropeptides regulate many important physiological processes in animals. The G protein-coupled receptors of corresponding small neuropeptide ligands are considered promising targets for controlling ...arthropod pests. Pyrokinins (PKs) are pleiotropic neuropeptides that, in some insect species, stimulate muscle contraction and modulate pheromone biosynthesis, embryonic diapause, and feeding behavior. However, their function remains unknown in ticks. In this study, we reported the myotropic activity of tick endogenous PKs and a PK agonist analog, PK-PEG
(MSPEG
-YFTPRLa), on feeding tissues of two tick species representing the family Ixodidae lineages, namely, Prostriata (
) and Metastriata (
). First, we predicted the sequences of two periviscerokinins (PVK), one with a derived ending RNa and five PKs encoded by the CAPA peptide precursor from
and found the encoded PKs were identical to those of
identified previously. The pharynx-esophagus of both tick species responded with increased contractions to 10 μM of the endogenous PK as well as to PK-PEG
but not to the scrambled PK peptide, as expected. A dose-dependent myotropic activity of the PK-PEG
was found for both tick species, validating the analog activity previously found in the pyrokinin recombinant receptor assay. In agreement with the tissue activity elicited, we quantified the relative transcript abundance of
PK receptor in unfed female ticks and found it was the highest in the feeding tissues extracted from the capitulum and lowest in the reproductive tissue. This is the first report of the activity of pyrokinins in ticks. These findings strongly indicate the potential role of PKs in regulating tick blood feeding and therefore, making the tick PK receptor a potential target for interference.
Student competitions can act as potent enrichment measures and complement formal schooling in fostering students' motivation as well as promoting their skills. This article presents the German ...Physics Olympiad, the national precursor to the International Physics Olympiad, in the general context of student competitions in Germany and its integration with the so called Science Olympiads in Germany. To put the German Physics Olympiad into an international context its structure and some of its features are compared with data on Physics Olympiads in other countries. As an outlook we elaborate on some of the challenges the Physics Olympiad in Germany is facing and present two research projects that further support the development of the competition.
Rhipicephalusmicroplus is the vector of deadly cattle pathogens, especially Babesia spp., for which a recombinant vaccine is not available. Therefore, disease control depends on tick vector control. ...However, R.microplus populations worldwide have developed resistance to available acaricides, prompting the search for novel acaricide targets. G protein-coupled receptors (GPCRs) are involved in the regulation of many physiological processes and have been suggested as druggable targets for the control of arthropod vectors. Arthropod-specific signaling systems of small neuropeptides are being investigated for this purpose. The pyrokinin receptor (PKR) is a GPCR previously characterized in ticks. Myotropic activity of pyrokinins in feeding-related tissues of Rhipicephalussanguineus and Ixodesscapularis was recently reported. The R.microplus pyrokinin receptor (Rhimi-PKR) was silenced through RNA interference (RNAi) in female ticks. To optimize RNAi, a dual-luciferase assay was applied to determine the silencing efficiency of two Rhimi-PKR double-stranded RNAs (dsRNA) prior to injecting dsRNA in ticks to be placed on cattle. Phenotypic variables of female ticks obtained at the endpoint of the RNAi experiment were compared to those of control female ticks (non-injected and beta-lactamase dsRNA-injected). Rhimi-PKR silencing was verified by quantitative reverse-transcriptase PCR in whole females and dissected tissues. The Rhimi-PKR transcript was expressed in all developmental stages. Rhimi-PKR silencing was confirmed in whole ticks 4 days after injection, and in the tick carcass, ovary and synganglion 6 days after injection. Rhimi-PKR silencing was associated with an increased mortality and decreased weight of both surviving females and egg masses (P < 0.05). Delays in repletion, pre-oviposition and incubation periods were observed (P < 0.05). Rhimi-PKR silencing negatively affected female reproductive fitness. The PKR appears to be directly or indirectly associated with the regulation of female feeding and/or reproductive output in R.microplus. Antagonists of the pyrokinin signaling system could be explored for tick control.
Abstract
Background
The cattle fever tick,
Rhipicephalus
(
Boophilus
)
microplus
, is a vector of pathogens causative of babesiosis and anaplasmosis, both highly lethal bovine diseases that affect ...cattle worldwide. In Ecdysozoa, neuropeptides and their G-protein-coupled receptors play a critical integrative role in the regulation of all physiological processes. However, the physiological activity of many neuropeptides is still unknown in ticks. Periviscerokinins (CAP
2b
/PVKs) are neuropeptides associated with myotropic and diuretic activities in insects. These peptides have been identified only in a few tick species, such as
Ixodes ricinus
,
Ixodes scapularis
and
R. microplus,
and their cognate receptor only characterized for the last two.
Methods
Expression of the periviscerokinin receptor (
Rhimi-CAP
2b
R
) was investigated throughout the developmental stages of
R. microplus
and silenced by RNA interference (RNAi) in the females. In a first experiment, three double-stranded (ds) RNAs, named ds680-805, ds956-1109 and ds1102-1200, respectively, were tested in vivo. All three caused phenotypic effects, but only the last one was chosen for subsequent experiments. Resulting RNAi phenotypic variables were compared to those of negative controls, both non-injected and dsRNA beta-lactamase-injected ticks, and to positive controls injected with beta-actin dsRNA.
Rhimi-CAP
2b
R
silencing was verified by quantitative reverse-transcriptase PCR in whole females and dissected tissues.
Results
Rhimi-CAP
2b
R
transcript expression was detected throughout all developmental stages
. Rhimi-CAP
2b
R
silencing was associated with increased female mortality, decreased weight of surviving females and of egg masses, a delayed egg incubation period and decreased egg hatching (
P
< 0.05).
Conclusions
CAP
2b
/PVKs appear to be associated with the regulation of female feeding, reproduction and survival. Since the
Rhimi-CAP
2b
R
loss of function was detrimental to females, the discovery of antagonistic molecules of the CAP
2b
/PVK signaling system should cause similar effects. Our results point to this signaling system as a promising target for tick control.
Graphical Abstract
The outer areas of Jupiter and Saturn have multiple zonal winds, reaching the high latitudes, that penetrate deep into the planets' interiors, as suggested by gravity measurements. These ...characteristics are replicable in numerical simulations by including both a shallow stably stratified layer, below a convecting envelope, and increasing electrical conductivity. A dipolar magnetic field, assumed to be generated by a dynamo below our model, is imposed. We find that the winds' depth into the stratified layer depends on the local product of the squared magnetic field strength and electrical conductivity. The key for the drop‐off of the zonal winds is a meridional circulation which perturbs the density structure in the stable layer. In the stable region its dynamics is governed by a balance between Coriolis and electromagnetic forces. Our models suggest that a stable layer extending into weakly conducting regions could account for the observed deep zonal wind structures.
Plain Language Summary
Jupiter and Saturn's atmospheres display persistent east‐west zonal jets, similar to Earth. These jets, extending 2,500–3,000 km and 8,000–9,000 km into Jupiter and Saturn's interiors respectively, have been challenging to simulate. Current numerical models struggle to replicate multiple jets, spanning all latitudes and their decay at the depths inferred from gravity measurements. This study explores the hypothesis that a stably stratified layer, located at the transition to a semi‐conducting region, allows the generation of mid‐latitude zonal winds and their damping at depth. Using 3D numerical simulations, we model the outer 30% of the planets where the upper part convects and the lower part is stably stratified. We impose a dipolar magnetic field at the lower boundary and electrical conductivity increases with depth. We observe that the decay in jet amplitude in the stable region depends on the local strength of the magnetic forces. Deep within the stable region, these Lorentz forces are balanced by meridional flow, which leads to temperature perturbations and efficient zonal wind quenching.
Key Points
Our numerical models examine the conditions needed to form zonal winds in gas planets, complying with observed gravity and magnetic data
A stable layer and magnetic forces are key for strong surface winds at high latitudes that are damped at the inferred depths
The decay profile of the winds in the stable layer is controlled by the product of conductivity and squared magnetic field strength
gamma-Aminobutyric acid type A (GABA(A)) receptors, the major inhibitory neurotransmitter receptors responsible for fast inhibition in the basal ganglia, belong to the superfamily of "cys-cys loop" ...ligand-gated ion channels. GABA(A) receptors form as pentameric assemblies of subunits, with a central Cl(-) permeable pore. On binding of two GABA molecules to the extracellular receptor domain, a conformational change is induced in the oligomer and Cl(-), in most adult neurons, moves into the cell leading to an inhibitory hyperpolarization. Nineteen mammalian subunit genes have been identified, each showing distinct regional and cell-type-specific expression. The combinatorial assembly of the subunits generates considerable functional diversity. Here we place the focus on GABA(A) receptor expression in the basal ganglia: striatum, globus pallidus, substantia nigra and subthalamic nucleus, where, in addition to the standard alpha1beta2/3gamma2 receptor subtype, significant levels of other subunits (alpha2, alpha3, alpha4, gamma1, gamma3 and delta) are expressed in some nuclei.
In a linear analysis for brake squeal, an unwanted type of sound in the kHz‐range produced during the braking process of vehicles, usually only the stability of the system is examined. However, with ...the appearance of additional stochastic excitation, the vibration of a linear system with subcritical self‐excitation, i.e. having self‐excitation but due to damping still an asymptotically stable trivial solution, may be large enough to produce a squeal sound. In this paper, this hypothesis of stochastically reinforced self‐excitation is supported by a case study on a wobbling disk model for brake squeal, which includes both circulatory and gyroscopic forces. For this example, the Fokker‐Planck equation is solved and numerical integrations are performed. A short parameter study is carried out to examine the effect of damping and gyroscopic terms on these stochastically reinforced self‐excitation. The results suggest that this possibility should be considered additionally to classical explanations of brake squeal.
In a linear analysis for brake squeal, an unwanted type of sound in the kHz‐range produced during the braking process of vehicles, usually only the stability of the system is examined. However, with the appearance of additional stochastic excitation, the vibration of a linear system with subcritical self‐excitation, i.e. having self‐excitation but due to damping still an asymptotically stable trivial solution, may be large enough to produce a squeal sound….
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