Genetic Obesity Affects Neural Ketone Body Utilization in the Rat Brain

Obesity causes various physiological disorders between the central nervous system and peripheral tissues. Ketone bodies have a neuro‐protective role and are strongly affected by obesity‐related metabolic disorders. To clarify the effects of obesity on ketone body utilization in brain, we examined the mRNA localization of acetoacetyl‐CoA synthetase (AACS), which activates ketone bodies for the synthesis of fatty acid and cholesterol, in various brain regions of Zucker fatty rats by in situ hybridization. The AACS mRNA level was increased in the paraventricular thalamic nucleus (PVT) but not affected in the cerebrum and hippocampus in Zucker fatty rats. In contrast, the AACS mRNA level was reduced in the arcuate hypothalamic nucleus (Arc) and ventromedial hypothalamic nucleus (VMH) in the hypothalamus. Succinyl‐CoA:3‐oxoacid CoA‐transferase (SCOT) mRNA level was decreased only in the PVT but not affected in the Arc and VMH. These data raise the possibility that AACS is regulated by the leptin signaling pathway in the hypothalamus but not in the PVT. As AACS was expressed in neural‐like cells, ketone bodies are assumed to be utilized for the synthesis of lipidic substances and to cause metabolic disorders in the nervous system.     

Social Distance Evaluation in Human Parietal Cortex

Across cultures, social relationships are often thought of, described, and acted out in terms of physical space (e.g. “close friends” “high lord”). Does this cognitive mapping of social concepts arise from shared brain resources for processing social and physical relationships? Using fMRI, we found that the tasks of evaluating social compatibility and of evaluating physical distances engage a common brain substrate in the parietal cortex. The present study shows the possibility of an analytic brain mechanism to process and represent complex networks of social relationships. Given parietal cortex''s known role in constructing egocentric maps of physical space, our present findings may help to explain the linguistic, psychological and behavioural links between social and physical space.     

Genetic population structure and morphological characters of Japanese psychrolutids of genus <Emphasis Type="Italic">Malacocottus</Emphasis> (Scorpaeniformes: Psychrolutidae)

The genetic population structure and the diagnostic characters of Malacocottus gibber from the Japan Sea and Malacocottus zonurus from the Okhotsk Sea and the northwestern Pacific were compared. Analysis of the nucleotide sequences of the mitochondrial control region revealed no genetic differences between the populations of M. gibber and M. zonurus, even though most individuals of both the species were found to be morphologically distinct. Most of the Malacocottus gibber specimens had the typical morphological characters of this species, namely the absence of an accessory spine on the preopercle of both sides and the absence of modified body scales above the lateral line. All the specimens of M. zonurus had accessory spines on both sides, and most of them had modified body scales. The results of this study suggest that M. gibber should be treated as a subspecies or a synonym of M. zonurus. The nested clade analysis and the analysis of molecular variance (AMOVA) showed that the Japanese Malacocottus fishes are genetically homogenous over their geographical range. The mismatch distribution of the Japanese Malacocottus fishes indicated that a sudden population expansion had occurred recently. The contrast in phylogeographic structures between the Malacocottus fish and the zoarcid Bothrocara hollandi—the most dominant deep-sea demersal fish in the Japan Sea—might be attributed to the differences in the depths of the habitats and larval ecology between these two fishes.     

In situ release of coral mucus by <Emphasis Type="Italic">Acropora</Emphasis> and its influence on the heterotrophic bacteria

In situ mucus release by Acropora nobilis and degradation of mucus from A. nobilis and Acropora formosa, by heterotrophic bacteria were investigated at Bidong and Tioman Island, Malaysia. Mucus release rate for A. nobilis was on average 38.7 ± 35.2 mg C m⁻² h⁻¹, of which ca. 70% consisted of dissolved organic carbon (DOC) and 30% particulate organic carbon (POC). In the mucus degradation experiment, seawater-mucus mixtures were incubated and compared with control runs for 24 h. Bacterial abundance in the seawater-mucus mixture increased significantly and coincided with a decline in DOC concentration. In controls, bacteria and DOC did not significantly change. The coral mucus had a high content of inorganic phosphate. It is suggested that the coral mucus rich in DOC and phosphate can induce the high bacterial growth.     

Membrane-bound acid pyrophosphatase from Sulfolobus tokodaii, a thermoacidophilic archaeon: heterologous expression of the gene and characterization of the product

Membranes of Sulfolobus tokodaii, a thermoacidophilic archaeon that grows optimally at pH 2–3, 75–80°C, show the ability to hydrolyze PPi with an optimum pH of 2–3. This acid PPase is proposed to be a dolicholpyrophosphatase that participates in glycoprotein biosynthesis. In the present study, the archaeal membranes hydrolyzed isopentenylpyrophosphate and geranylpyrophosphate, compounds related to dolicholpyrophosphate, at pH 3. However, the dolicholpyrophosphate-binding antibiotic bacitracin failed to inhibit the acid PPase. To investigate further the function and structure of the acid PPase, the gene was cloned and heterologously expressed in Escherichia coli. The membranes from recombinant E. coli showed PPase activity with similar pH and temperature dependence, substrate specificity, and kinetic parameters to those reported for Sulfolobus membranes. The acid PPase was solubilized and purified to electrophoretic homogeneity from the recombinant E. coli. The purified enzyme showed similar K _m values for PPi, ATP, and ADP to the membrane-bound enzyme. Lipids from the Sulfolobus membranes enhanced the activity to about threefold. Studies involving deletion mutants indicated that basic amino acids in the N-terminal (Arg2 and Lys3), as well as the residues (4th–69th) possibly twice-spanning the membrane, are essential for integration of the enzyme into membranes.     

Desert hedgehog‐patched 2 expression in peripheral nerves during Wallerian degeneration and regeneration

Hedgehog proteins are important in the development of the nervous system. As Desert hedgehog (Dhh) is involved in the development of peripheral nerves and is expressed in adult nerves, it may play a role in the maintenance of adult nerves and degeneration and regeneration after injury. We firstly investigated the Dhh‐receptors, which are expressed in mouse adult nerves. The Dhh receptor patched(ptc)2 was detected in adult sciatic nerves using RT‐PCR, however, ptc1 was undetectable under the same experimental condition. Using RT‐PCR in purified cultures of mouse Schwann cells and fibroblasts, we found ptc2 mRNA in Schwann cells, and at much lower levels, in fibroblasts. By immunohistochemistry, Ptc2 protein was seen on unmyelinated nerve fibers. Then we induced crush injury to the sciatic nerves of wild‐type (WT) and dhh‐null mice and the distal stumps of injured nerves were analyzed morphologically at different time points and expression of dhh and related receptors was also measured by RT‐PCR in WT mice. In dhh‐null mice, degeneration of myelinated fibers was more severe than in WT mice. Furthermore, in regenerated nerves of dhh‐null mice, minifascicular formation was even more extensive than in dhh‐null intact nerves. Both dhh and ptc2 mRNA levels were down‐regulated during the degenerative phase postinjury in WT mice, while levels rose again during the phase of nerve regeneration. These results suggest that the Dhh‐Ptc2 signaling pathway may be involved in the maintenance of adult nerves and may be one of the factors that directly or indirectly determines the response of peripheral nerves to injury. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2006     

Cytoplasmic expression of the JM403 antigen GlcA-GlcNH 3 + on heparan sulfate glycosaminoglycan in mammary carcinomas—a novel proliferative biomarker for breast cancers with high malignancy

The expressions of heparan sulfate glycosaminoglycans (HSGAGs) in breast carcinoma specimens from 60 patients were immunohistochemically investigated using monoclonal antibodies (mAbs) that recognized different epitopes of the glycan structure. Cytoplasmic expression of GlcA-GlcNH ₃ ⁺ on HSGAG was detected in carcinomas at high frequency (58.3%) using mAb JM403, whereas it was almost undetectable in normal breast ducts. This cytoplasmic expression was confirmed using confocal laser scanning microscopy. The expression of JM403 antigen in invasive carcinomas significantly correlated with nuclear atypia score (p?=?0.0004), mitotic counts score (p?=?0.0018), nuclear grade (p?=?0.0061) and the incidence of metastasis to axillary lymph nodes (p?=?0.0061). Furthermore, its expression was significantly correlated with the Ki67-labeling index in 55 invasive carcinomas (p?p? ₃ ⁺ was also expressed in the cytoplasm of normal crypt epithelial cells where Ki67 protein was expressed in the cell nuclei in the proliferative compartment of the human small intestines. To date, HSGAGs have generally been found to exist on cell surface membranes and in extracellular matrices as components of HS proteoglycans, and the negatively-charged sulfated domains on HSGAGs are considered to be important for their functions. However, our present findings indicate that the cytoplasmic expression of the JM403 antigen GlcA-GlcNH ₃ ⁺ on positively charged, non-sulfated HSGAG may be involved in cell proliferation and associated with increased degrees of malignancy. The unordinary carbohydrate antigen of GlcA-GlcNH ₃ ⁺ on HSGAGs recognized by mAb JM403 may represent a novel proliferative biomarker for highly malignant mammary carcinomas.     

TGF-β superfamily regulates a switch that mediates differentiation either into adipocytes or myocytes in left atrium derived pluripotent cells (LA-PCS)

Many stem cell studies have focused on the subject of cell fate and the signal molecules that modulate the regulatory switches for a given differentiation pathway. Genome-wide screens for cell fate determination signals require a cell source that differentiates purely into a single cell type. From adult rat left atrium, we established LA-PCs that differentiates into cardiac/skeletal myocytes or adipocytes with almost 100% purity. In this study, we compared gene expression profiles of undifferentiated LA-PCs with those of differentiated cells [adipocytes (Adi) or cardiac/skeletal myocytes (Myo)] to identify the signals that set the regulatory switch for adipocyte or myocyte differentiation. Microarray analysis verified the feasibility of genome-wide screening by this method. Using a pathway analysis screen, we found that members of the TGF-β superfamily signal transduction pathways modulate the adipocyte/myocyte differentiation switch. Further analysis determined that recombinant TGF-β inhibits adipogenesis and induces myogenesis simultaneously in a dose-dependent manner. Moreover, noggin induces differentiation into fully developed beating cardiac myocytes in vitro. These results provided new insight into the molecules that modulate the differentiation switch and validated a screening method for their identification.     

Pancreatic stellate cells promote epithelial-mesenchymal transition in pancreatic cancer cells

The interaction between pancreatic cancer cells and pancreatic stellate cells (PSCs), a major profibrogenic cell type in the pancreas, is receiving increasing attention. There is accumulating evidence that PSCs promote the progression of pancreatic cancer by increasing cancer cell proliferation and invasion as well as by protecting them from radiation- and gemcitabine-induced apoptosis. Because epithelial-mesenchymal transition (EMT) plays a critical role in the progression of pancreatic cancer, we hypothesized that PSCs promote EMT in pancreatic cancer cells. Panc-1 and SUIT-2 pancreatic cancer cells were indirectly co-cultured with human PSCs isolated from patients undergoing operation for pancreatic cancer. The expression of epithelial and mesenchymal markers was examined by real-time PCR and immunofluorescent staining. The migration of pancreatic cancer cells was examined by scratch and two-chamber assays. Pancreatic cancer cells co-cultured with PSCs showed loose cell contacts and a scattered, fibroblast-like appearance. The expression of E-cadherin, cytokeratin 19, and membrane-associated β-catenin was decreased, whereas vimentin and Snail (Snai-1) expression was increased more in cancer cells co-cultured with PSCs than in mono-cultured cells. The migration of pancreatic cancer cells was increased by co-culture with PSCs. The PSC-induced decrease of E-cadherin expression was not altered by treatment with anti-TGF-β-neutralizing antibody, excluding a central role of TGF-β in this process. In conclusion, PSCs promoted EMT in pancreatic cancer cells suggesting a novel mechanism by which PSCs contribute to the aggressive behavior of pancreatic cancer cells.