Pyrazine Analogues Are Active Components of Wolf Urine That Induce Avoidance and Freezing Behaviours in Mice

Background

The common grey wolf (Canis lupus) is found throughout the entire Northern hemisphere and preys on many kinds of mammals. The urine of the wolf contains a number of volatile constituents that can potentially be used for predator–prey chemosignalling. Although wolf urine is put to practical use to keep rabbits, rodents, deer and so on at bay, we are unaware of any prior behavioural studies or chemical analyses regarding the fear-inducing impact of wolf urine on laboratory mice.

Methodology/Principal Findings

Three wolf urine samples harvested at different times were used in this study. All of them induced stereotypical fear-associated behaviors (i.e., avoidance and freezing) in female mice. The levels of certain urinary volatiles varied widely among the samples. To identify the volatiles that provoked avoidance and freezing, behavioural, chemical, and immunohistochemical analyses were performed. One of the urine samples (sample C) had higher levels of 2,6-dimethylpyrazine (DMP), trimethylpyrazine (TMP), and 3-ethyl-2,5-dimethyl pyrazine (EDMP) compared with the other two urine samples (samples A and B). In addition, sample C induced avoidance and freezing behaviours more effectively than samples A and B. Moreover, only sample C led to pronounced expression of Fos-immunoreactive cells in the accessory olfactory bulb (AOB) of female mice. Freezing behaviour and Fos immunoreactivity were markedly enhanced when the mice were confronted with a mixture of purified DMP, TMP, and EDMP vs. any one pyrazine alone.

Conclusions/Significance

The current results suggest that wolf urinary volatiles can engender aversive and fear-related responses in mice. Pyrazine analogues were identified as the predominant active components among these volatiles to induce avoidance and freezing behaviours via stimulation of the murine AOB.     

Human Leukocyte Antigen and Systemic Sclerosis in Japanese: The Sign of the Four Independent Protective Alleles,DRB1*13:02, DRB1*14:06, DQB1*03:01, and DPB1*02:01

ObjectiveSeveral studies on associations between human leukocyte antigen (HLA) allele frequencies and susceptibility to systemic sclerosis (SSc) have been reported. Anti-centromere antibodies (ACA) and anti-topoisomerase I antibodies (ATA) are found in SSc patients. Here, we sought to identify HLA alleles associated with SSc in Japanese, and explored their associations with SSc phenotypes including the presence of autoantibodies.MethodsAssociations of HLA-DRB1, DQB1, and DPB1 were analyzed in 463 Japanese SSc patients and 413 controls.ResultsWe found that DRB1*13:02 (P = 0.0011, Pc = 0.0319, odds ratio [OR] 0.46, 95% confidence interval [CI] 0.29–0.73), DRB1*14:06 (P = 6.60X10^-5, Pc = 0.0020, OR 0.05, 95%CI 0.01–0.41), DQB1*03:01 (P = 0.0009, Pc = 0.0150, OR 0.56, 95%CI 0.40–0.79), and DPB1*02:01 (P = 5.16X10^-6, Pc = 8.77X10^-5, OR 0.52, 95%CI 0.39–0.69) were protectively associated with SSc. In addition, these four alleles seemed to be independently associated with the protection against the susceptibility of SSc. On the other hand, we could not find predisposing alleles for overall SSc. With respect to SSc subsets, a tendency for these four alleles to be protectively associated was observed. However, there was a significant association between DRB1*01:01, DRB1*10:01, DQB1*05:01, and DPB1*04:02 and the susceptibility to SSc with ACA. On the other hand, the presence of DRB1*15:02, DQB1*06:01, DPB1*03:01, and DPB1*09:01 was associated with SSc with ATA.ConclusionThus, the present study has identified protective associations of the four HLA class II alleles with overall Japanese SSc and predisposing associations of HLA class II alleles with Japanese SSc subsets.     

The distribution of sugar chains on the vomeronasal epithelium observed with an atomic force microscope

The distribution of sugar chains on tissue sections of the rat vomeronasal epithelium, and the adhesive force between the sugar and its specific lectin were examined with an atomic force microscope (AFM). AFM tips were modified with a lectin, Vicia villosa agglutinin, which recognizes terminal N-acetyl-D-galactosamine (GalNAc). When a modified tip scanned the luminal surface of the sensory epithelium, adhesive interactions between the tip and the sample surface were observed. The final rupture force was calculated to be approximately 50 pN based on the spring constant of the AFM cantilever. Distribution patterns of sugar chains obtained from the force mapping image were very similar to those observed using fluorescence-labeled lectin staining. AFM also revealed distribution patterns of sugar chains at a higher resolution than those obtained with fluorescence microscopy. Most of the adhesive interactions disappeared when the scanning solution contained 1 mM GaINAc. The adhesive interactions were restored by removing the sugar from the solution. Findings suggest that the adhesion force observed are related to the binding force between the lectin and the sugars distributed across the vomeronasal epithelium.     

Microbiological activities contributing to nitrogen removal with methane: effects of methyl fluoride and tungstate

When methane (CH(4)) and O(2) are present, nitrogen can be removed from wastewater that does not contain other organic carbon sources. In this study, microbial activities during methane-dependent denitrification (MDD) were investigated by adding inhibitors of methane-oxidation and denitrification. Sludge susceptible to MDD showed methane oxidation activity in the presence of CH(4) and O(2), and denitrification activity with methanol and acetate under anoxic conditions. Methyl fluoride (CH(3)F) is known to inhibit methane oxidation. When CH(3)F was present, MDD did not occur, perhaps because methane oxidation was inhibited. Tungstate (WO(4)(2-)), a known inhibitor of nitrate reduction, also lowered denitrification activity in the sludge, and partly inhibited methane oxidation. When WO(4)(2-) was added to the medium, MDD almost ceased, perhaps because of a synergic inhibitory effect on denitrification and methane oxidation. These results show that both methane oxidation and denitrification contribute to MDD.