Three growth-based survival mechanisms were tested for multiple cohorts of Japanese anchovy (Engraulis japonicus) larvae in Sagami Bay. Through otolith microstructure analysis, growth trajectories ...and histories of samples of the survivors were compared with those of the original populations to examine size- and growth-selective mortality to test the “bigger is better” and “growth-selective predation” mechanisms, respectively. The effects of growth rates on the timing of metamorphosis were examined to test the “stage duration” mechanism. The bigger is better and growth-selective predation mechanisms were detected to be effective in two and six of eight seasonal cohorts, respectively. Results contrary to the bigger is better and growth-selective predation mechanisms were obtained from three and two of eight cohorts, respectively. The stage duration mechanism was evaluated to be effective for both of two cohorts that were testable. Overall, none of the three mechanisms were universally appropriate for all of the cohorts. The relative contributions of the three mechanisms were dynamic, although the growth-selective predation mechanism was identified to be the major one in anchovy larvae in the study site.
Some preclinical evidence suggests that the sigma receptor type 1, which plays several roles in learning and memory, may also be involved in the pathogenesis of Alzheimer disease (AD). The authors ...provide here genetic evidence that the sigma receptor type 1 (SIGMAR1) gene is involved in susceptibility to AD.
Two polymorphisms of the SIGMAR1 gene, G-241T/C-240T and Q2P, were analyzed in a Japanese sample of 239 patients with AD and 227 comparisons subjects. These two polymorphisms were in complete linkage disequilibrium with each other, resulting in only two haplotypes, GC-241-240Q2 and TT-241-240P2.
There was a significant association between AD and the TT-241-240P2 haplotype of the SIGMAR1 gene and its homozygote, found with late-onset, but not early-onset AD. After stratification by ε4 allele status of the apolipoprotein E gene, TT-241-240P2 homozygosity of the SIGMAR1 gene reduced the risk of AD in ε4 allele carriers by three-fourths.
The present study suggests that the TT-241-240P2 haplotype of the SIGMAR1 gene, which decreases expression of the gene, may have a protective role against susceptibility to AD.
Because methamphetamine (METH) is metabolized by CYP2D6 at the first step of hydroxylation and demethylation, it is possible that functional variants of CYP2D6 alter susceptibility to ...methamphetamine-induced dependence. We genotyped
CYP2D6*
1,
*4, *
5, *
10, and
*14 for 202 patients with METH dependence and 337 controls in a Japanese population and found a significant association of the
CYP2D6 gene with METH dependence (
p
=
0.0299). The patients had fewer *
10 and *
14 alleles, which are hypofunction alleles, than the controls.
CYP2D6 genotypes were divided into three phenotypes: extensive metabolizers, intermediate metabolizers, and poor metabolizers. There was no poor metabolizer among our Japanese subjects, and intermediate metabolizers of CYP2D6 were significantly fewer in methamphetamine-dependent subjects than in controls (
p
=
0.0212), with an odds ratio of 0.62 (95% confidence interval: 0.51–0.76). The present study demonstrated that reduced CYP2D6 activity was a negative risk factor for methamphetamine dependence.
The present study demonstrates a novel mixing approach for achieving a good dispersion of carbon nanotubes (CNTs) in a styrene–butadiene rubber (SBR), which leads to a significant improvement in ...electrical properties. Our mixing technique consists of (1) pretreatment by ultrasonication to disentangle the bundles of CNTs in organic solvent and (2) “rotation–revolution” mixing of the CNTs with SBR without mechanical shear, which prevents CNTs from collapsing during the mixing process. The present mixing method does not require the addition of any dispersing agents (amphiphilic molecules) or chemical modification of the CNTs to obtain a good dispersion. Compared with a conventional Banbury mixing technique, our method leads to a significant decrease in the percolation threshold (less than 1
phr), where the electrical conductivity suddenly increases due to the formation of percolation networks of CNTs in SBR. This is because the aspect ratio of the CNTs was maintained even after the mixing process, whereas CNTs were broken during the conventional Banbury mixing. The effect of using different types of CNTs on electrical conductivity was also investigated. The results show that the percolation threshold is largely related to the structural quality (graphitization) of the CNTs as well as their aspect ratio.
Several lines of evidence have supported possible roles of the sigma receptors in the etiology of schizophrenia and mechanisms of antipsychotic efficacy. An association study provided genetic ...evidence that the sigma receptor type 1 gene (SIGMAR1) was a possible susceptibility factor for schizophrenia, however, it was not replicated by a subsequent study. It is necessary to evaluate further the possibility that the SIGMAR1 gene is associated with susceptibility to schizophrenia.
A case-control association study between two polymorphisms of the SIGMAR1 gene, G-241T/C-240T and Gln2Pro, and schizophrenia in Japanese population, and meta-analysis including present and previous studies.
There was no significant association of any allele or genotype of the polymorphisms with schizophrenia. Neither significant association was observed with hebephrenic or paranoid subtype of schizophrenia. Furthermore, a meta-analysis including the present and previous studies comprising 779 controls and 636 schizophrenics also revealed no significant association between the SIGMAR1 gene and schizophrenia.
In view of this evidence, it is likely that the SIGMAR1 gene does not confer susceptibility to schizophrenia.
Brain-derived neurotrophic factor (BDNF) belongs to a family of neurotrophic factors and has been demonstrated to promote the survival, differentiation, and maintenance of a broad variety of central ...nervous system neurons. Several reports have suggested that the BDNF gene is a plausible functional candidate gene underlying the predisposition for developing bipolar disorder (BPD). In the present study, we investigated the possible role of the BDNF gene in the etiology of BPD using a matched case-control association design in a Japanese population. There was no evidence for an allelic or genotypic association of two polymorphisms (−1360C>T and 196G>A) of the BDNF gene with BPD. Furthermore, no significant association was observed between these polymorphisms and either of two diagnostic subtypes (bipolars I and II disorder). The results suggest that the BDNF gene is unlikely to confer susceptibility to BPD.
The dihydropyrimidinase-related protein (DRP) family, also called the collapsin response mediator protein, is implicated in the developmental process of the nervous system. Dysfunction of DRPs may ...result in neurodevelopmental abnormalities, which may be a factor in the pathogenesis of schizophrenia. The expression of one member of DRP-2 in humans has been reported to be decreased in the brains of people with schizophrenia. In addition, the DRP-2 gene (Dihydropyrimidinaselike 2; DPYSL2) is located on chromosome 8p21, a region that has been implicated in schizophrenia in genetic linkage studies.
We investigated a genetic association between five polymorphisms of the DRP-2 gene and schizophrenia in the Japanese population.
The *2236
T>C polymorphism in the 3′ untranslated region (3′UTR) exhibited significant differences with respect to the distribution of the genotype and allele in patients compared with control subjects. The frequency of the *2236C allele was significantly higher in control subjects than patients with schizophrenia (
p = .0097) and paranoid-type schizophrenia (
p = .0083).
Our results suggest that the *2236C allele in the 3′UTR of the DRP-2 gene, or an unknown mutation in linkage disequilibrium with this allele, may reduce the susceptibility to schizophrenia, especially the paranoid subtype.
Neurodevelopmental abnormalities have been reported in studies on the pathogenesis of schizophrenia. The Wnt-signaling pathway has been implicated in a variety of processes in neurodevelopment, and ...the frizzled proteins have been identified as receptors for Wnt ligands. Of the frizzled proteins, frizzled-3 (FZD3) is required for formation of the neural crest and for development of major fiber tracts in the CNS. The human
FZD3 gene is located on chromosome 8p21, a positive linkage locus for schizophrenia. We analyzed polymorphisms of the
FZD3 gene in patients with schizophrenia and control subjects in the Japanese population. We found a significant association between schizophrenia and the
FZD3 gene in single nucleotide polymorphisms and haplotype analyses. Our data suggest that dysregulation of the Wnt-signaling pathway may be involved in the susceptibility to schizophrenia.
Genetic contributions to the etiology of substance abuse and dependence are topics of major interest. Acute and chronic cannabis use can produce drug-induced psychosis resembling schizophrenia and ...worsen positive symptoms of schizophrenia. The endocannabinoid system is one of the most important neural signaling pathways implicated in substance abuse and dependence. The fatty acid amide hydrolase (FAAH) is a primary catabolic enzyme of endocannabinoids. To clarify a possible involvement of FAAH in the etiology of methamphetamine dependence/psychosis or schizophrenia, we examined the genetic association of a nonsynonymous polymorphism of the FAAH gene (Pro129Thr) by a case-control study. We found no significant association in allele and genotype frequencies of the polymorphism with either disorder. Because the Pro129Thr polymorphism reduces enzyme instability, it is unlikely that dysfunction of FAAH and enhanced endocannabinoid system induce susceptibility to either methamphetamine dependence/psychosis or schizophrenia.
Neprilysin (NEP), also known as neutral endopeptidase, enkephalinase, CD 10, and common acute lymphoblastic leukemia antigen, is a 97-kD protein. NEP can degrade amyloid β peptides, and its mRNA and ...protein levels are known to be reduced in the brains of patients with Alzheimer’s disease (AD), making the NEP gene a substantial candidate for an AD risk factor. We examined the genetic association of three NEP polymorphisms, a GT-repeat polymorphism and two single nucleotide polymorphisms (SNPs, –1075A>G and –1284G>C) in its promoter region, with AD in a Japanese case-control sample (240 patients and 163 controls). The GT-repeat polymorphism, but not the SNPs, was significantly associated with late-onset AD (p = 0.0007). Our findings suggest that the GT-repeat polymorphism in the promoter region of the NEP gene or some other unknown polymorphisms, which are in a linkage disequilibrium, confer a susceptibility to late-onset AD.
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