Bathymetric distribution of aquatic Oligochaeta in Lake Kizaki, Central Japan

Bathymetric distribution of aquatic oligochaetes was studied at 8 stations with different depths (mean depth 16.7 ± 9.4 m, min. 5.3 m, max. 29.4 m) in July 2012 in mesotrophic Lake Kizaki, Nagano Prefecture, Central Japan. The average density was 10424 ± 5346 individuals m-2. Oligochaetes were numerically dominant at all sampling stations. High density, sometimes more than 10000 individuals m-2,was recorded at 3 stations (St. 4, 5, and 6) deeper than 18 m. Maximum density was 20561 ± 13864 individuals m-2 at Station 4 (depth 29.4 m, ignition loss of sediment 13.5%, bottom water temperature 8.1 °C and DO of bottom water 0.12 mg l-1). We identified a total of 5 genera and 7 species belonging to three subfamilies: i.e., 1 species of Naidinae, 2 species of Rhyacodrilinae and 4 species of Tubificinae. Dominant species (in order of abundance) were Tubifex tubifex (Müller, 1774) (8550 ± 6317 individuals m-2; 82.0%) and Limnodrilus spp. (L. hoffmeisteri Claparède, 1862 and L. claparedeianus Ratzel, 1868) (1710 ± 1383 individuals m-2; 16.4%). Tubifex and Limnodrilus were obtained from every station, and the density of T. tubifex tended to be higher as the depth became greater, while Limnodrilus spp. was also widely distributed, but with a peak value at a depth of 5.3 m in the shallowest station. From the submerged plant zone, Ophidonais serpentina (Müller, 1773) was collected. An earlier study by Hirabayashi & Hayashi (1994) showed that in 1985 the average density of aquatic oligochaetes was 435 ± 428 individuals m-2, oligochaetes dominated in only four locations and were distributed over the whole lake approximately equally. Comparisons of our data with the earlier studies have shown that oligochaete density has increased greatly according to Hirabayashi & Hayashi (1994). We suggest that a decrease in dissolved oxygen concentration of bottom water was due to an increase in organic matter content of the sediment. As a result, T. tubifex could expand their habitats in the profundal zone.ArticleZoosymposia. 9:36-43 (2014)journal articl

A long-term eutrophication process observed from the changes in the horizontal distribution of profundal oligochaete fauna in mesotrophic-eutrophic Lake Kawaguchi, Japan

The purpose of this study was to record the oligochaete fauna in Lake Kawaguchi and clarify their horizontal distribution. In addition, annual changes in the lake were recorded. Samples were collected between 5 March 1993 and 7 March 2006 by using a standard Ekman-Birge sampler at 22 stations, and multipoint sampling surveys were carried out. As a result of the study, a total of 8 species belonging to 6 genera and 3 subfamilies were identified. The average density of oligochaetes for the entire lake was 5247 +/- 3873 ind m(-2) and the average wet weight of oligochaetes was 25.5 +/- 23.4 g m(-2) in 1993, compared to 1075 +/- 676 ind m(-2) and 2.7 +/- 1.7 g m(-2), respectively, in 2006. Tubifex tubifex had inhabited the entire lake bottom in 1993, but Limnodrilus spp. inhabited only the center of the lake in 2006. In recent years, the total number of oligochaetes has shown a tendency to increase, compared with the past record from the 1970s, suggesting that eutrophication is an ongoing process.ArticleTURKISH JOURNAL OF ZOOLOGY. 36(1):39-46 (2012)journal articl

Abnormal axon guidance signals and reduced interhemispheric connection via anterior commissure in neonates of marmoset ASD model

In autism spectrum disorder (ASD), disrupted functional and structural connectivity in the social brain has been suggested as the core biological mechanism underlying the social recognition deficits of this neurodevelopmental disorder. In this study, we aimed to identify genetic and neurostructural abnormalities at birth in a non-human primate model of ASD, the common marmoset with maternal exposure to valproic acid (VPA), which has been reported to display social recognition deficit in adulthood. Using a comprehensive gene expression analysis, we found that 20 genes were significantly downregulated in VPA-exposed neonates. Of these, Frizzled3 (FZD3) and PIK3CA were identified in an axon guidance signaling pathway. FZD3 is essential for the normal development of the anterior commissure (AC) and corpus callosum (CC); hence, we performed diffusion tensor magnetic resonance imaging with a 7-Tesla scanner to measure the midsagittal sizes of these structures. We found that the AC size in VPA-exposed neonates was significantly smaller than that in age-matched controls, while the CC size did not differ. These results suggest that downregulation of the genes related to axon guidance and decreased AC size in neonatal primates may be linked to social brain dysfunctions that can happen later in life

<strong>Bathymetric distribution of aquatic Oligochaeta in Lake Kizaki, Central Japan</strong>

Bathymetric distribution of aquatic oligochaetes was studied at 8 stations with different depths (mean depth 16.7 ± 9.4 m, min. 5.3 m, max. 29.4 m) in July 2012 in mesotrophic Lake Kizaki, Nagano Prefecture, Central Japan. The average density was 10424 ± 5346 individuals m-2. Oligochaetes were numerically dominant at all sampling stations. High density, sometimes more than 10000 individuals m-2,was recorded at 3 stations (St. 4, 5, and 6) deeper than 18 m. Maximum density was 20561 ± 13864 individuals m-2 at Station 4 (depth 29.4 m, ignition loss of sediment 13.5%, bottom water temperature 8.1 °C and DO of bottom water 0.12 mg l-1). We identified a total of 5 genera and 7 species belonging to three subfamilies: i.e., 1 species of Naidinae, 2 species of Rhyacodrilinae and 4 species of Tubificinae. Dominant species (in order of abundance) were Tubifex tubifex (Müller, 1774) (8550 ± 6317 individuals m-2; 82.0%) and Limnodrilus spp. (L. hoffmeisteri Claparède, 1862 and L. claparedeianus Ratzel, 1868) (1710 ± 1383 individuals m-2; 16.4%). Tubifex and Limnodrilus were obtained from every station, and the density of T. tubifex tended to be higher as the depth became greater, while Limnodrilus spp. was also widely distributed, but with a peak value at a depth of 5.3 m in the shallowest station. From the submerged plant zone, Ophidonais serpentina (Müller, 1773) was collected. An earlier study by Hirabayashi & Hayashi (1994) showed that in 1985 the average density of aquatic oligochaetes was 435 ± 428 individuals m-2, oligochaetes dominated in only four locations and were distributed over the whole lake approximately equally. Comparisons of our data with the earlier studies have shown that oligochaete density has increased greatly according to Hirabayashi & Hayashi (1994). We suggest that a decrease in dissolved oxygen concentration of bottom water was due to an increase in organic matter content of the sediment. As a result, T. tubifex could expand their habitats in the profundal zone.ArticleZoosymposia. 9:36-43 (2014)journal articl

Abnormal axon guidance signals and reduced interhemispheric connection via anterior commissure in neonates of marmoset ASD model.

In autism spectrum disorder (ASD), disrupted functional and structural connectivity in the social brain has been suggested as the core biological mechanism underlying the social recognition deficits of this neurodevelopmental disorder. In this study, we aimed to identify genetic and neurostructural abnormalities at birth in a non-human primate model of ASD, the common marmoset with maternal exposure to valproic acid (VPA), which has been reported to display social recognition deficit in adulthood. Using a comprehensive gene expression analysis, we found that 20 genes were significantly downregulated in VPA-exposed neonates. Of these, Frizzled3 (FZD3) and PIK3CA were identified in an axon guidance signaling pathway. FZD3 is essential for the normal development of the anterior commissure (AC) and corpus callosum (CC); hence, we performed diffusion tensor magnetic resonance imaging with a 7-Tesla scanner to measure the midsagittal sizes of these structures. We found that the AC size in VPA-exposed neonates was significantly smaller than that in age-matched controls, while the CC size did not differ. These results suggest that downregulation of the genes related to axon guidance and decreased AC size in neonatal primates may be linked to social brain dysfunctions that can happen later in life

Mutated G-protein-coupled receptor GPR10 is responsible for the hyperphagia/dyslipidaemia/obesity locus of Dmo1 in the OLETF rat.

1. We have confirmed the Diabetes Mellitus OLETF type I (Dmo1) effect on hyperphagia, dyslipidaemia and obesity in the Otsuka Long-Evans Tokushima Fatty (OLETF) strain. The critical interval was narrowed down to 570 kb between D1Got258 to p162CA1 by segregation analyses using congenic lines. 2. Within the critical 570 kb region of the Dmo1 locus, we identified the G-protein-coupled receptor gene GPR10 as the causative gene mutated in the OLETF strain. The ATG translation initiation codon of GPR10 is changed into ATA in this strain and, so, is unavailable for the initiation of translation. 3. The GPR10 protein has a cognate ligand, namely prolactin-releasing peptide (PrRP). Centrally administered PrRP suppressed the food intake of congenic rats that have a Brown Norway derived Dmo1 region (i.e. with wild-type GPR10), but did not suppress that of the OLETF strain, indicating that GPR10 is without function and could explain hyperphagia in the OLETF strain. 4. Moreover, when restricted in food volume to the same level consumed by the congenic strain, OLETF rats showed few differences in the parameters of dyslipidaemia and obesity compared with congenic strains. 5. Taken together, these results demonstrate that the mutated GPR10 receptor is responsible for the hyperphagia leading to obesity and dyslipidaemia in the obese diabetic strain rat

Functional and molecular characterization of a non-human primate model of autism spectrum disorder shows similarity with the human disease

Autism spectrum disorder (ASD) is a multifactorial disorder with characteristic synaptic and gene expression changes. Early intervention during childhood is thought to benefit prognosis. Here, we examined the changes in cortical synaptogenesis, synaptic function, and gene expression from birth to the juvenile stage in a marmoset model of ASD induced by valproic acid (VPA) treatment. Early postnatally, synaptogenesis was reduced in this model, while juvenile-age VPA-treated marmosets showed increased synaptogenesis, similar to observations in human tissue. During infancy, synaptic plasticity transiently increased and was associated with altered vocalization. Synaptogenesis-related genes were downregulated early postnatally. At three months of age, the differentially expressed genes were associated with circuit remodeling, similar to the expression changes observed in humans. In summary, we provide a functional and molecular characterization of a non-human primate model of ASD, highlighting its similarity to features observed in human ASD