Genomic variation in the vomeronasal receptor gene repertoires of inbred mice

ABSTRACT: BACKGROUND: Vomeronasal receptors (VRs), expressed in sensory neurons of the vomeronasal organ, are thought to bind pheromones and mediate innate behaviours. The mouse reference genome has over 360 functional VRs arranged in highly homologous clusters, but the vast majority are of unknown function. Differences in these receptors within and between closely related species of mice are likely to underpin a range of behavioural responses. To investigate these differences, we interrogated the VR gene repertoire from 17 inbred strains of mice using massively parallel sequencing. RESULTS: Approximately half of the 6222 VR genes that we investigated could be successfully resolved, and those that were unambiguously mapped resulted in an extremely accurate dataset. Collectively VRs have over twice the coding sequence variation of the genome average; but we identify striking non-random distribution of these variants within and between genes, clusters, clades and functional classes of VRs. We show that functional VR gene repertoires differ considerably between different Mus subspecies and species, suggesting these receptors may play a role in mediating behavioural adaptations. Finally, we provide evidence that widely-used, highly inbred laboratory-derived strains have a greatly reduced, but not entirely redundant capacity for differential pheromone-mediated behaviours. CONCLUSIONS: Together our results suggest that the unusually variable VR repertoires of mice have a significant role in encoding differences in olfactory-mediated responses and behaviours. Our dataset has expanded over nine fold the known number of mouse VR alleles, and will enable mechanistic analyses into the genetics of innate behavioural differences in mice.     

Genetic and immunologic characterization of a novel serotype 4, 15 strain of Neisseria meningitidis

The porin proteins of Neisseria meningitidis are important components of outer membrane protein (OMP) vaccines. The class 3 porin gene, porB, of a novel serogroup B, serotype 4, 15 isolate from Chile (Ch501) was found to be VR1-4, VR2-15, VR3-15 and VR4-15 by porB variable region (VR) typing. Rabbit immunization studies using outer membrane vesicles revealed immunodominance of individual PorB (class 3) VR epitopes. The predominant anti-Ch501 PorB response was directed to the VR1 epitope. Anti-PorB VR1 mediated killing was suggested by the bactericidal activity of Ch501 anti-sera against a type 4 strain not expressing PorA or class 5 OMPs. Studies that examine the molecular epidemiology of individual porB VRs, and the immune responses to PorB epitopes, may contribute to the development of broadly protective group B meningococcal vaccines.     

The p80 homology region of TEP1 is sufficient for its association with the telomerase and vault RNAs, and the vault particle

TEP1 is a protein component of two ribonucleoprotein complexes: vaults and telomerase. The vault-associated small RNA, termed vault RNA (VR), is dependent upon TEP1 for its stable association with vaults, while the association of telomerase RNA with the telomerase complex is independent of TEP1. Both of these small RNAs have been shown to interact with amino acids 1–871 of TEP1 in an indirect yeast three-hybrid assay. To understand the determinants of TEP1–RNA binding, we generated a series of TEP1 deletions and show by yeast three-hybrid assay that the entire Tetrahymena p80 homology region of TEP1 is required for its interaction with both telomerase and VRs. This region is also sufficient to target the protein to the vault particle. Electrophoretic mobility shift assays using the recombinant TEP1 RNA-binding domain (TEP1–RBD) demonstrate that it binds RNA directly, and that telomerase and VRs compete for binding. VR binds weakly to TEP1–RBD in vitro, but mutation of VR sequences predicted to disrupt helices near its central loop enhances binding. Antisense oligonucleotide-directed RNase H digestion of endogenous VR indicates that this region is largely single stranded, suggesting that TEP1 may require access to the VR central loop for efficient binding.     

Viewing DVM via general behaviors of zooplankton: a way bridging the success of individual and population

In this paper, we viewed the diel vertical migration (DVM) of copepod in the context of the animal's immediate behaviors of everyday concerns and constructed an instantaneous behavioral criterion effective for DVM and non-DVM behaviors. This criterion employed the function of 'venturous revenue' (VR), which is the product of the food intake and probability of the survival, to evaluate the gains and losses of the behaviors that the copepod could trade-off. The optimal behaviors are to find the optimal habitats to maximize VR. Two types of VRs are formulated and tested by the theoretical analysis and simulations. The sensed VR, monitoring the real-time changes of trade-offs and thereby determining the optimum habitat, is validated to be the effective objective function for the optimization of the behavior; whereas, the realized VR, quantifying the actual profit obtained by an optimal copepod in the sensed-VR-determined habitat, defines the life history of a specific age cohort. The achievement of a robust copepod overwintering stock through integrating the dynamics of the constituent age cohorts subjected to the instantaneous behavioral criterion for DVM clearly exemplified a possible way bridging the immediate pursuit of an individual and the end success of the population.     

An unexpected effect of capsaicin on spontaneous GABA-ergic IPSCS in hippocampal cell cultures

Vanilloid receptors 1 (VRs1) expressed in a subpopulation of sensory neurons and responsible for processing of chemical and thermal noxious stimuli were also shown to be expressed in several cerebral structures and to be involved in the regulation of glutamatergic synaptic transmission. In this study, we started to investigate the possibility that VRs1 are also involved in the regulation of GABA-ergic synaptic transmission. For this purpose, the effect of a VR1 agonist, capsaicin, on spontaneous GABA-ergic inhibitory postsynaptic currents (IPSCs) was studied in hippocampal cell cultures using a patch-clamp technique. It was found that capsaicin (10 μM) decreased both the frequency and amplitude of spontaneous IPSCs. This finding suggests the involvement of VRs1 in the regulation of neuronal firing in some GABA-ergic interneurons and in the modulation of the efficacy of GABA-ergic synaptic transmission. However, considering the direction of the effect (a decrease in the IPSC frequency) and lack of its desensitization, the involvement of other receptor(s) also cannot currently be ruled out. Neirofiziologiya/Neurophysiology, Vol. 38, No. 4, pp. 364–367, July–August, 2006.     

Effects of a brief sensorimotor training on the development of behavioral inhibition in the mouse

In the young C57Bl6 mouse, the hyperexcitability phase (`pop-corn' stage) which normally occurs around the 16–18th postnatal day and lasts 3–6 days, was greatly shortened by an intensive sensorimotor training when the `pop-corn' stage appeared. It was prevented when the animals were trained for 4 days before it appeared. This might suggest, at least in part, that an early short duration sensorimotor training increased the rate of maturation of the inhibitory systems that sustain the development of the motor behavior.     

Variable resistance versus constant resistance strength training in adult males

Changes in strength, body composition and anthropometric measures for groups training with constant resistance and variable resistance training procedures was compared. Thirty-six male volunteers were randomly assigned to one of three groups: Constant Resistance (CR), Variable Resistance (VR) and Control (C). Strength training was conducted 3 days per week, 45 min per day, for 10 weeks. The results demonstrated that both the CR and the VR groups increased muscular strength. The CR group demonstrated significant increases in strength over the VR group when strength was assessed by CR procedures. Conversely, the VR group demonstrated significant increases in strength over the CR group when strength was assessed by VR procedures. Neither group exhibited superiority over the other relative to changes in body composition and anthropometric measures. The significance of these results is discussed.     

alpha-Bungarotoxin-sensitive hippocampal nicotinic receptor channel has a high calcium permeability.

The hippocampal nicotinic acetylcholine receptor (nAChR) is a newly identified ligand-gated ion channel that is blocked by the snake toxin alpha-bungarotoxin (alpha-BGT) and that probably contains the alpha 7 nAChR subunit in its structure. Here its ion selectivity was characterized and compared with that of the N-methyl-D-aspartate (NMDA) receptor channel. The reversal potentials (VR) of acetylcholine- and NMDA-activated whole-cell currents were determined under various ionic conditions. Using ion activities and a Goldman-Hodgkin-Katz equation for VR shifts in the presence of Ca2+, permeability ratios were calculated. For the alpha-BGT-sensitive nAChR, PNa/PCs was close to 1 and Cl- did not contribute to the currents. Changing the [Ca2+]0 from 1 to 10 mM, the VRs of the nAChR and NMDA currents were shifted by +5.6 +/- 0.4 and +8.3 +/- 0.4 mV, respectively, and the nAChR current decay was accelerated. These shifts yielded PCa/PCss of 6.1 +/- 0.5 for the nAChR channel and 10.3 +/- 0.7 for the NMDA channel. Thus, the neuronal alpha-BGT-sensitive nAChR is a cation channel considerably selective to Ca2+ and may mediate a fast rise in intracellular Ca2+ that would increase in magnitude with membrane hyperpolarization.     

Do domestic pigs in controlled environments contrafreeload?

Many experiments report that animals will work (lever press) for food in the presence of freely available identical food. This phenomenon has attracted the attention of applied ethologists because it seems to prove that animals have a need to express appetitive behavior. If this is the case, then it has implications for the provision of environmental enrichment for animals in captivity. In this experiment, we maintained 6 pigs in closed economy environments for three 120-hr choice periods in which they had continuous free access to operant and identical free food. In the experiment, we tested pigs using 2 different operant schedules, fixed ratio (FR) 5 and variable ratio (VR) 5. We used a VR schedule because many enrichment studies claim that unpredictability is an important characteristic that makes an enrichment device attractive. The results show that pigs exhibited a negligible level of contrafreeloading (M ± standard error of the mean proportion = 0.05 × 0.01). Furthermore, there were no significant differences between FRs and VRs of reinforcement.     

Chloroplast biogenesis 92: In situ screening for divinyl chlorophyll(ide) a reductase mutants by spectrofluorometry

Chlorophyll biosynthetic heterogeneity is rooted mainly in parallel divinyl (DV) and monovinyl (MV) biosynthetic routes interconnected by 4-vinyl reductases (4VRs) that convert DV tetrapyrroles to MV tetrapyrroles by conversion of the vinyl group at position 4 of the macrocycle to ethyl. What is not clear at this stage is whether the various 4VR activities are catalyzed by one enzyme of broad specificity or by a family of enzymes encoded by one gene or multiple genes with each enzyme having narrow specificity. Additional research is needed to identify the various regulatory components of 4-vinyl reduction. In this undertaking, Arabidopsis mutants that accumulate DV chlorophyllide a and/or DV chlorophyll [Chl(ide)] a are likely to provide an appropriate resource. Because the Arabidopsis genome has been completely sequenced, the best strategy for identifying 4VR and/or putative regulatory 4VR genes is to screen Arabidopsis Chl mutants for DV Chl(ide) a accumulation. In wild-type Arabidopsis, a DV plant species, only MV chlorophyllide (Chlide) a is detectable. However in Chl mutants lacking 4VR activity, DV Chl(ide) a may accumulate in addition to MV Chl(ide) a. In the current work, an in situ assay of DV Chl(ide) a accumulation, suitable for screening a large number of mutants lacking 4-vinyl Chlide a reductase activity with minimal experimental handling, is described. The assay involves homogenization of the tissues in Tris-HCl:glycerol buffer and the recording of Soret excitation spectra at 77K. DV Chlide a formation is detected by a Soret excitation shoulder at 459 nm over a wide range of DV Chlide a/MV Chl a ratios. The DV Chlide a shoulder became undetectable at DV Chlide a/MV Chl a ratios less than 0.049, that is, at a DV Chlide a content of less than 5%.     

Virtual reality as a tool for evaluation of repetitive rhythmic movements in the elderly and Parkinson's disease patients

This work presents an immersive Virtual Reality (VR) system to evaluate, and potentially treat, the alterations in rhythmic hand movements seen in Parkinson's disease (PD) and the elderly (EC), by comparison with healthy young controls (YC). The system integrates the subjects into a VR environment by means of a Head Mounted Display, such that subjects perceive themselves in a virtual world consisting of a table within a room. In this experiment, subjects are presented in 1(st) person perspective, so that the avatar reproduces finger tapping movements performed by the subjects. The task, known as the finger tapping test (FT), was performed by all three subject groups, PD, EC and YC. FT was carried out by each subject on two different days (sessions), one week apart. In each FT session all subjects performed FT in the real world (FT(REAL)) and in the VR (FT(VR)); each mode was repeated three times in randomized order. During FT both the tapping frequency and the coefficient of variation of inter-tap interval were registered. FT(VR) was a valid test to detect differences in rhythm formation between the three groups. Intra-class correlation coefficients (ICC) and mean difference between days for FT(VR) (for each group) showed reliable results. Finally, the analysis of ICC and mean difference between FT(VR) vs FT(REAL), for each variable and group, also showed high reliability. This shows that FT evaluation in VR environments is valid as real world alternative, as VR evaluation did not distort movement execution and detects alteration in rhythm formation. These results support the use of VR as a promising tool to study alterations and the control of movement in different subject groups in unusual environments, such as during fMRI or other imaging studies.     

Capsaicin-sensitive afferents in the vagus nerve

Vanilloids were shown to interact with over 70% of vagal C-afferents first causing an excitation followed by desensitisation and a lasting destruction of nerve fibres. Capsaicin induces a secretion of some neuropeptides from 10-30% of vagal sensory terminals and therefore serves as a pharmacological tool for testing local "effector function" of primary afferents. Vagal afferents seem to have their own subtype of vanilloid receptors (VR), not completely identical with the VR receptors in the dorsal root ganglia. Considering potentiation of the capsaicin receptors sensitivity by some factors such as local heating, pH, free oxygen radicals, a possible role of the VRs as integrators of chemical and physical components of nociceptive stimuli, is discussed.     

The genomic basis of vomeronasal-mediated behaviour

The vomeronasal organ (VNO) is a chemosensory subsystem found in the nose of most mammals. It is principally tasked with detecting pheromones and other chemical signals that initiate innate behavioural responses. The VNO expresses subfamilies of vomeronasal receptors (VRs) in a cell-specific manner: each sensory neuron expresses just one or two receptors and silences all the other receptor genes. VR genes vary greatly in number within mammalian genomes, from no functional genes in some primates to many hundreds in rodents. They bind semiochemicals, some of which are also encoded in gene families that are coexpanded in species with correspondingly large VR repertoires. Protein and peptide cues that activate the VNO tend to be expressed in exocrine tissues in sexually dimorphic, and sometimes individually variable, patterns. Few chemical ligand–VR–behaviour relationships have been fully elucidated to date, largely due to technical difficulties in working with large, homologous gene families with high sequence identity. However, analysis of mouse lines with mutations in genes involved in ligand–VR signal transduction has revealed that the VNO mediates a range of social behaviours, including male–male and maternal aggression, sexual attraction, lordosis, and selective pregnancy termination, as well as interspecific responses such as avoidance and defensive behaviours. The unusual logic of VR expression now offers an opportunity to map the specific neural circuits that drive these behaviours.     

Assessment of repeatability of surface electromyography signals by singular value decomposition

Singular value decomposition (SVD) of full-wave rectified surface electromyography (sEMG) signals was investigated for repeatability indices of sEMG linear envelopes (LE) during biceps curl. The SVD based repeatability indices were compared with a well-known method, the variance ratio (VR). The usefulness of the offered indices was examined by a simulation and it was applied to the sEMG LEs. The results have shown that the VRs were correlated with the SVD based indices significantly. The usefulness of the offered indices on real world EMG signals practically comes from decreasing amplitudes of the first few singular values of EMG LE matrix. If repeatability is high, singular values decay fast and vice versa.If justified by further researches, the offered indices may be used practically for repeatability measurement of sEMG LEs.     

A Feasibility Study with Image-Based Rendered Virtual Reality in Patients with Mild Cognitive Impairment and Dementia

Virtual Reality (VR) has emerged as a promising tool in many domains of therapy and rehabilitation, and has recently attracted the attention of researchers and clinicians working with elderly people with MCI, Alzheimer’s disease and related disorders. Here we present a study testing the feasibility of using highly realistic image-based rendered VR with patients with MCI and dementia. We designed an attentional task to train selective and sustained attention, and we tested a VR and a paper version of this task in a single-session within-subjects design. Results showed that participants with MCI and dementia reported to be highly satisfied and interested in the task, and they reported high feelings of security, low discomfort, anxiety and fatigue. In addition, participants reported a preference for the VR condition compared to the paper condition, even if the task was more difficult. Interestingly, apathetic participants showed a preference for the VR condition stronger than that of non-apathetic participants. These findings suggest that VR-based training can be considered as an interesting tool to improve adherence to cognitive training in elderly people with cognitive impairment.     

Differential recruitment of the sensorimotor putamen and frontoparietal cortex during motor chunking in humans

Motor chunking facilitates movement production by combining motor elements into integrated units of behavior. Previous research suggests that chunking involves two processes: concatenation, aimed at the formation of motor-motor associations between elements or sets of elements, and segmentation, aimed at the parsing of multiple contiguous elements into shorter action sets. We used fMRI to measure the trial-wise recruitment of brain regions associated with these chunking processes as healthy subjects performed a cued-sequence production task. A dynamic network analysis identified chunking structure for a set of motor sequences acquired during fMRI and collected over 3?days of training. Activity in the bilateral sensorimotor putamen positively correlated with chunk concatenation, whereas?a left-hemisphere frontoparietal network was correlated with chunk segmentation. Across subjects, there was an aggregate increase in chunk strength (concatenation) with training, suggesting that subcortical circuits play a direct role in the creation of fluid transitions across chunks.     

Depression of ventilatory responses after daily, cyclic hypercapnic hypoxia in piglets.

Ventilatory responses (VRs) were measured via a sealed face mask and pneumotachograph in 30 unsedated, mixed-breed miniature piglets at 12.6 +/- 2.3 days of age (day 1) and then repeated after seven daily 24-min exposures to 10% O(2)-6% CO(2) [hypercapnic hypoxia (HH)]. Arterial blood was sampled at baseline, after 10 min of exposure, and after 10 min of recovery. VRs included hypoxia (10% O(2) in N(2)), hypercapnia (6% CO(2) in air), and HH (10% O(2)-6% CO(2)-balance N(2)). Treatment groups (n = 10 each) were exposed to 24 min of HH from day 2 to 8 as sustained HH (24 min of HH and then 24 min of air) or cyclic HH (4 min of HH alternating with 4 min of air). Day 1 and 9 data were compared in treatment and control groups. After cyclic HH, respiratory responses to CO(2) were reduced during hypercapnia and during HH (P < 0.001 vs. control for minute ventilation in both). In both treatment groups, time to peak minute ventilation was delayed in hypoxia (P = 0.02, ANOVA), and response amplitude was increased (P < 0.001 and P = 0.003, sustained and cyclic HH, respectively, vs. control). Respiratory pattern was also altered during the VRs and among treatment groups. Stimulus presentation characteristics exert effects on VRs that are independent of those elicited by daily HH.     

Comparison of molecular and biological characteristics of a modified live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine (ingelvac PRRS MLV), the parent strain of the vaccine (ATCC VR2332), ATCC VR2385, and two recent field isolates of PRRSV

The objectives of this study were to compare the molecular and biological characteristics of recent porcine reproductive and respiratory syndrome virus (PRRSV) field isolates to those of a modified live virus (MLV) PRRS vaccine and its parent strain. One hundred seventeen, 4-week-old pigs were randomly assigned to six groups. Group 1 (n = 20) served as sham-inoculated negative controls, group 2 (n = 19) was inoculated with Ingelvac PRRS MLV vaccine, group 3 (n = 20) was inoculated with the parent strain of the vaccine (ATCC VR2332), group 4 (n = 19) was inoculated with vaccine-like PRRSV field isolate 98-38803, group 5 (n = 19) was inoculated with PRRSV field isolate 98-37120, and group 6 (n = 20) was inoculated with known high-virulence PRRSV isolate ATCC VR2385. The levels of severity of gross lung lesions (0 to 100%) among the groups were significantly different at both 10 (P < 0.0001) and 28 days postinoculation (p.i.) (P = 0.002). At 10 days p.i., VR2332 (26.5% +/- 4.64%) and VR2385 (36.4% +/- 6.51%) induced gross lesions of significantly greater severity than 98-38803 (0.0% +/- 0.0%), 98-37120 (0.8% +/- 0.42%), Ingelvac PRRS MLV (0.9% +/- 0.46%), and negative controls (2.3% +/- 1.26%). At 28 days p.i., 98-37120 (17.2% +/- 6.51%) induced gross lesions of significantly greater severity than any of the other viruses. Analyses of the microscopic-interstitial-pneumonia-lesion scores (0 to 6) revealed that VR2332 (2.9 +/- 0.23) and VR2385 (3.1 +/- 0.35) induced significantly more severe lesions at 10 days p.i. At 28 days p.i., VR2385 (2.5 +/- 0.27), VR2332 (2.3 +/- 0.21), 98-38803 (2.6 +/- 0.29), and 98-37120 (3.0 +/- 0.41) induced significantly more severe lesions than Ingelvac PRRS MLV (0.7 +/- 0.17) and controls (0.7 +/- 0.15). The molecular analyses and biological characterizations suggest that the vaccine-like isolate 98-38803 (99.5% amino acid homology based on the ORF5 gene) induces microscopic pneumonia lesions similar in type to, but different in severity and time of onset from, those observed with virulent strains VR2385 and the parent strain of the vaccine. Our data strongly suggest that isolate 98-38803 is a derivative of Ingelvac PRRS MLV and that the isolate is pneumovirulent.     

Arginine-rich peptides are blockers of VR-1 channels with analgesic activity

Vanilloid receptors (VRs) play a fundamental role in the transduction of peripheral tissue injury and/or inflammation responses. Molecules that antagonize VR channel activity may act as selective and potent analgesics. We report that synthetic arginine-rich hexapeptides block heterologously expressed VR-1 channels with submicromolar efficacy in a weak voltage-dependent manner, consistent with a binding site located near/at the entryway of the aqueous pore. Dynorphins, natural arginine-rich peptides, also blocked VR-1 activity with micromolar affinity. Notably, synthetic and natural arginine-rich peptides attenuated the ocular irritation produced by topical capsaicin application onto the eyes of experimental animals. Taken together, our results imply that arginine-rich peptides are VR-1 channel blockers with analgesic activity. These findings may expand the development of novel analgesics by targeting receptor sites distinct from the capsaicin binding site.