Testes Investment along a Vertical Depth Gradient in an Herbivorous Fish

Males are expected to adjust testes investment according to the varying level of sperm competition that they experience. Spatial and temporal variation in population density likely influences sperm competition. In herbivorous aquatic organisms, densities often decrease along a vertical depth gradient, because their food is photosynthetic and thus becomes less abundant in deeper regions where less light penetrates. This decrease should be dramatic on a steep slope, which allows testing of the association between density and testes investment at the within‐population level. We tested the effect in the socially monogamous herbivorous cichlid fish Variabilichromis moorii living on a steep slope in Lake Tanganyika. We examined competitor density and food abundance as ecological factors, territory defense behaviors and phenotypic traits (testes investment and somatic investment), and compared them between shallow (4–6 m depth) and deep habitats (10–13 m depth) separated by several dozen meters. We found that food availability drastically decreased with increasing depth and that V . moorii was much more abundant in shallower habitats. Males in shallower habitats were in better physical condition (based on fat and liver mass) despite experiencing greater costs in terms of territory defense. Testes investment differed in areas with different competitor density and food abundance along a vertical depth gradient, but competitor density was the most explanatory factor of the difference. This suggests that this herbivorous fish would change testes investment in response to population density.     

Effect of temperature on gelatinization and retrogradation in high hydrostatic pressure treatment of potato starch-water mixtures

The effect of temperature (20-70 °C) on the gelatinization and retrogradation of potato starch-water mixtures (10-70%, w/w) treated with high hydrostatic pressure (HHP) (400-1000 MPa) was investigated. Gelatinization enthalpy change (ΔH_gel) and re-gelatinization enthalpy change of retrograded crystalline part (ΔH_retro) of the HHP-treated starch were evaluated using differential scanning calorimetry. The value of ΔH_gel of 10-20% (w/w) mixtures decreased with increased pressure and temperature, while ΔH_gel of 30-50% (w/w) mixtures decreased to certain values with increased pressure and the values depended on treatment temperature. With higher temperature and pressure conditions, ΔH_gel of 10-40% (w/w) mixtures reached zero, but ΔH_gel of 50-70% (w/w) mixtures did not. Retrogradation was observed with HHP-treated 20-60% (w/w) mixtures and the value of ΔH_retro depended on the starch content, pressure, and temperature. The value of ΔH_retro trended to increase with increase in starch content. In addition, retrogradation was promoted by HHP treatment at low temperature. Gelatinizaiton and retrogradation behaviors of HHP-treated (400-1000 MPa) potato starch-water mixtures (10-70%, w/w) at 20-70 °C were summerized in a series of state diagrams.     

Nation-wide litter fall data from 21 forests of the Monitoring Sites 1000 Project in Japan

This data paper reports litter fall data collected in a network of 21 forest sites in Japan. This is the largest litter fall data set freely available in Japan to date. The network is a part of the Monitoring Sites 1000 Project launched by the Ministry of the Environment, Japan. It covers subarctic to subtropical climate zones and the four major forest types in Japan. Twenty-three permanent plots in which usually 25 litter traps were installed were established in old-growth or secondary natural forests. Litter falls were collected monthly from 2004, and sorted into leaves, branches, reproductive structures and miscellaneous. The data provide seasonal patterns and inter-annual dynamics of litter falls, and their geographical patterns, and offer good opportunities for meta-analyses and comparative studies among forests.     

Impact of the genome wide supported NRGN gene on anterior cingulate morphology in schizophrenia

Background

The rs12807809 single-nucleotide polymorphism in NRGN is a genetic risk variant with genome-wide significance for schizophrenia. The frequency of the T allele of rs12807809 is higher in individuals with schizophrenia than in those without the disorder. Reduced immunoreactivity of NRGN, which is expressed exclusively in the brain, has been observed in Brodmann areas (BA) 9 and 32 of the prefrontal cortex in postmortem brains from patients with schizophrenia compared with those in controls.

Methods

Genotype effects of rs12807809 were investigated on gray matter (GM) and white matter (WM) volumes using magnetic resonance imaging (MRI) with a voxel-based morphometry (VBM) technique in a sample of 99 Japanese patients with schizophrenia and 263 healthy controls.

Results

Although significant genotype-diagnosis interaction either on GM or WM volume was not observed, there was a trend of genotype-diagnosis interaction on GM volume in the left anterior cingulate cortex (ACC). Thus, the effects of NRGN genotype on GM volume of patients with schizophrenia and healthy controls were separately investigated. In patients with schizophrenia, carriers of the risk T allele had a smaller GM volume in the left ACC (BA32) than did carriers of the non-risk C allele. Significant genotype effect on other regions of the GM or WM was not observed for either the patients or controls.

Conclusions

Our findings suggest that the genome-wide associated genetic risk variant in the NRGN gene may be related to a small GM volume in the ACC in the left hemisphere in patients with schizophrenia.     

The p250GAP gene is associated with risk for schizophrenia and schizotypal personality traits

Background

Hypofunction of the glutamate N-Methyl-d-aspartate (NMDA) receptor has been implicated in the pathophysiology of schizophrenia. p250GAP is a brain-enriched NMDA receptor-interacting RhoGAP. p250GAP is involved in spine morphology, and spine morphology has been shown to be altered in the post-mortem brains of patients with schizophrenia. Schizotypal personality disorder has a strong familial relationship with schizophrenia. Several susceptibility genes for schizophrenia have been related to schizotypal traits.

Methods

We first investigated the association of eight linkage disequilibrium-tagging single-nucleotide polymorphisms (SNPs) that cover the p250GAP gene with schizophrenia in a Japanese sample of 431 schizophrenia patients and 572 controls. We then investigated the impact of the risk genetic variant in the p250GAP gene on schizotypal personality traits in 180 healthy subjects using the Schizotypal Personality Questionnaire.

Results

We found a significant difference in genotype frequency between the patients and the controls in rs2298599 (χ² = 17.6, p = 0.00015). The minor A/A genotype frequency of rs2298599 was higher in the patients (18%) than in the controls (9%) (χ² = 15.5, p = 0.000083). Moreover, we found that subjects with the rs2298599 risk A/A genotype, compared with G allele carriers, had higher scores of schizotypal traits (F_1,178 = 4.08, p = 0.045), particularly the interpersonal factor (F_1,178 = 5.85, p = 0.017).

Discussion

These results suggest that a genetic variation in the p250GAP gene might increase susceptibility not only for schizophrenia but also for schizotypal personality traits. We concluded that the p250GAP gene might be a new candidate gene for susceptibility to schizophrenia.     

The inositol 5-phosphatase SHIP2 is an effector of RhoA and is involved in cell polarity and migration

Cell migration is essential for various physiological and pathological processes. Polarization in motile cells requires the coordination of several key signaling molecules, including RhoA small GTPases and phosphoinositides. Although RhoA participates in a front-rear polarization in migrating cells, little is known about the functional interaction between RhoA and lipid turnover. We find here that src-homology 2-containing inositol-5-phosphatase 2 (SHIP2) interacts with RhoA in a GTP-dependent manner. The association between SHIP2 and RhoA is observed in spreading and migrating U251 glioma cells. The depletion of SHIP2 attenuates cell polarization and migration, which is rescued by wild-type SHIP2 but not by a mutant defective in RhoA binding. In addition, the depletion of SHIP2 impairs the proper localization of phosphatidylinositol 3,4,5-trisphosphate, which is not restored by a mutant defective in RhoA binding. These results suggest that RhoA associates with SHIP2 to regulate cell polarization and migration.     

Factors promoting maternal trophic egg provisioning in non-eusocial animals

The adaptive function of trophic egg-laying is generally regarded as extended parental investment to the offspring. However, the evolutionary factors promoting trophic egg-laying are still unclear, because the amount of maternal investment per offspring should be ideally equal between smaller offspring with trophic eggs and larger offspring without any additional investment. Several authors have suggested that trophic egg-laying should evolve only when egg size is constrained, but this hypothesis has not been evaluated. We investigated the evolutionary mechanisms of trophic egg-laying by two different approaches. First, we evaluated morphological constraints on egg size in two sibling ladybird species, Harmonia axyridis, which is known to produce trophic eggs, and H. yedoensis. Second, we theoretically predicted the optimal proportion of trophic eggs to total eggs and egg size in relation to environmental heterogeneity, predictability of environmental quality, and investment efficiency of trophic egg consumption. The intra- and interspecific morphological comparisons suggest that morphological constraints on the evolutionary determination of egg size are weak at best in the two ladybird species. Moreover, we theoretically showed that small egg size and trophic egg-laying are favoured in heterogeneous environments when mothers cannot adjust egg size plastically. We also showed that even a small reduction in investment efficiency makes a trophic egg strategy unlikely, despite relatively high environmental predictability. We conclude that trophic egg provisioning may be a flexible maternal adaptation to a highly heterogeneous environment rather than a response to a morphological constraint on egg size.     

Self-Enhancement of Hepatitis C Virus Replication by Promotion of Specific Sphingolipid Biosynthesis

Lipids are key components in the viral life cycle that affect host-pathogen interactions. In this study, we investigated the effect of HCV infection on sphingolipid metabolism, especially on endogenous SM levels, and the relationship between HCV replication and endogenous SM molecular species. We demonstrated that HCV induces the expression of the genes (SGMS1 and 2) encoding human SM synthases 1 and 2. We observed associated increases of both total and individual sphingolipid molecular species, as assessed in human hepatocytes and in the detergent-resistant membrane (DRM) fraction in which HCV replicates. SGMS1 expression had a correlation with HCV replication. Inhibition of sphingolipid biosynthesis with a hepatotropic serine palmitoyltransferase (SPT) inhibitor, NA808, suppressed HCV-RNA production while also interfering with sphingolipid metabolism. Further, we identified the SM molecular species that comprise the DRM fraction and demonstrated that these endogenous SM species interacted with HCV nonstructural 5B polymerase to enhance viral replication. Our results reveal that HCV alters sphingolipid metabolism to promote viral replication, providing new insights into the formation of the HCV replication complex and the involvement of host lipids in the HCV life cycle.     

Targeted analysis of ganglioside and sulfatide molecular species by LC/ESI-MS/MS with theoretically expanded multiple reaction monitoring

Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) has been applied primarily to the analysis of glycosphingolipids separated from other complex mixtures by TLC, but it is difficult to obtain quantitative profiling of each glycosphingolipid among the different spots on TLC by MALDI-MS. Thus, the development of a convenient approach that utilizes liquid chromatography/electrospray ionization (LC/ESI)-MS has received interest. However, previously reported methods have been insufficient to separate and distinguish each ganglioside class. Here we report an effective method for the targeted analysis of theoretically expected ganglioside molecular species by LC/ESI tandem mass spectrometry (LC/ESI-MS/MS) in combination with multiple reaction monitoring (MRM). MRM detection specific for sialic acid enabled us to analyze ganglioside standards such as GM1, GM2, GM3, GD1, and GT1 at picomolar to femtomolar levels. Furthermore, other gangliosides, such as GD2, GD3, GT2, GT3, and GQ1, were also detected in glycosphingolipid standard mixtures from porcine brain and acidic glycolipid extract from mouse brain by theoretically expanded MRM. We found that this approach was also applicable to sulfatides contained in the glycosphingolipid mixtures. In addition, we established a method to separate and distinguish regioisomeric gangliosides, such as GM1a and -1b, GD1a, -1b, and -1c, and GT1a, -1b, and -1c with diagnostic sugar chains in the MRM.