Megathrust earthquake drives drastic organic carbon supply to the hadal trench.

The giant 2011 Tohoku-oki earthquake has been inferred to remobilise fine-grained, young surface sediment enriched in organic matter from the slope into the >7 km deep Japan Trench. Yet, this hypothesis and assessment of its significance for the carbon cycle has been hindered by limited data density and resolution in the hadal zone. Here we combine new high-resolution bathymetry data with sub-bottom profiler images and sediment cores taken during 2012-2016 in order to map for the first time the spatial extent of the earthquake-triggered event deposit along the hadal Japan Trench. We quantify a sediment volume of ~0.2 km3 deposited from spatially-widespread remobilisation of young surficial seafloor slope sediments triggered by the 2011 earthquake and its aftershock sequence. The mapped volume and organic carbon content in sediment cores encompassing the 2011 event reveals that this single tectonic event delivered >1 Tg of organic carbon to the hadal trench. This carbon supply is comparable to high carbon fluxes described for other Earth system processes, shedding new light on the impact of large earthquakes on long-term carbon cycling in the deep-sea.

Archaeology of Archaea: geomicrobiological record of Pleistocene thermal events concealed in a deep-sea subseafloor environment.

A record of the history of the Earth is hidden in the Earth's crust, like the annual rings of an old tree. From very limited records retrieved from deep underground, one can infer the geographical, geological, and biological events that occurred throughout Earth's history. Here we report the discovery of vertically shifted community structures of Archaea in a typical oceanic subseafloor core sample (1410 cm long) recovered from the West Philippine Basin at a depth of 5719 m. Beneath a surface community of ubiquitous deep-sea archaea (marine crenarchaeotic group I; MGI), an unusual archaeal community consisting of extremophilic archaea, such as extreme halophiles and hyperthermophiles, was present. These organisms could not be cultivated, and may be microbial relicts more than 2 million years old. Our discovery of archaeal rDNA in this core sample, probably associated with the past terrestrial volcanic and submarine hydrothermal activities surrounding the West Philippine Basin, serves as potential geomicrobiological evidence reflecting novel records of geologic thermal events in the Pleistocene period concealed in the deep-sea subseafloor.

Temperature monitoring of internal body heating induced by decoupling pulses in animal (13)C-MRS experiments.

A temperature monitoring method to promote safety with regard to tissue heating induced by RF irradiation during MRI procedures, especially carbon-13 magnetic resonance spectroscopy ((13)C-MRS), is proposed. The method is based on the temperature dependence of the water proton chemical shift (-0.01 ppm/ degrees C) combined with phase mapping. Using this method, temperature changes were measured in rats (n = 4) employing practical (1)H-decoupled (13)C-MRS pulse sequences for 1D projections (TR = 1000 ms, acquisition time = 15 ms, matrix = 256, spatial resolution = 0.2 mm) and 2D images (TR = 1500 ms, acquisition time = 840 ms, matrix = 128x32, spatial resolution = 0.8x1.5 mm). Measurement error was 0.18 degrees C (SD) for 1D acquisition and 0.39 degrees C (SD) for 2D acquisition, demonstrating the feasibility of this temperature mapping method. Further studies should be conducted in human subjects to monitor patient safety and to optimize the pulse sequences employed. Magn Reson Med 43:796-803, 2000.

Human brain glucose metabolism mapping using multislice 2D (1)H-(13)C correlation HSQC spectroscopy.

A method for multivolume 2D (1)H-(13)C correlation spectroscopy, multislice heteronuclear single quantum coherence (HSQC), is proposed. This permits human brain metabolism from glucose to amino acids to be followed using a 2-T whole-body scanner. The modifications from the conventional HSQC are that the 180 degrees ((13)C) and 180 degrees ((1)H) pulses are separated in time in the preparation period and that the 180 degrees ((13)C) pulse is applied at 1/(4J(CH)) before the 90 degrees ((1)H) polarization transfer (PT) pulse. The preparation (echo) time can be set longer than 1/(2J(CH)) so that, even in a whole-body system, slice-selective pulses and gradients can be applied. Another modification is that the 90 degrees ((1)H) reverse PT pulses after the creation of 2I(z)S(z) are used as multislice pulses. The time-course of glutamate C4 could be followed with 15-min temporal resolution from the HSQC spectra obtained from the brains of volunteers after the oral administration of glucose C1, and the maximum S/N was 3.

3D localized 1H-13C heteronuclear single-quantum coherence correlation spectroscopy in vivo.

A method for spatially three-dimensional (3D) localized two-dimensional (2D) 1H-13C correlation spectroscopy, localized HSQC, is proposed. This method has the following special feature in the preparation period. The 180 degrees (13C) and 180 degrees (1H) pulses are separated in time, and the 180 degrees (13C) pulse is applied at 1/4 1JCH) before the 90 degrees (1H) polarization transfer pulse. The preparation (echo) period 2tau can then be set substantially longer than 1/(2 1JCH), so that even in a whole-body system, slice-selective 90 degrees (1H) pulses and gradient pulses can be applied in that period. The localization capabilities of this method were confirmed in a phantom experiment. The 3D localized 2D 1H-13C correlation spectra from a monkey brain in vivo were obtained after [1-13C]glucose injection, and amino acid metabolism was detected; that is, [4-13C]glutamate appeared immediately after the injection, followed by the appearance of [2-13C]glutamate, [3-13C]glutamate, and [4-13C]glutamine.

Effects of ammonia on the anaplerotic pathway and amino acid metabolism in the brain: an ex vivo 13C NMR spectroscopic study of rats after administering [2-13C]] glucose with or without ammonium acetate.

The 13C-label incorporation into glutamate, glutamine, aspartate and gamma-aminobutyric acid (GABA) from [2-13C] glucose was measured by 13C nuclear magnetic resonance (NMR) spectroscopy to directly examine the effects of ammonia on the activity of pyruvate carboxylase (i.e., the anaplerotic pathway) and the amino acid metabolism in the rat brain in vivo. Rats were sacrificed by exposure to microwaves at 7.5, 15, 30, and 60 min after an i.v. injection of [2-13C] glucose with or without ammonium acetate. After the injection of ammonium acetate, the brain contents of glutamate, aspartate and GABA had decreased, however, the percentage of 13C enrichment of C3 of glutamine, glutamate and GABA, and C2 and C3 of aspartate had increased. The 13C entered the TCA cycle via pyruvate carboxylase from [2-13C] glucose, labeling the C2 or C3 positions of aspartate, the C2 or C3 positions of glutamate and glutamine, and the C3 or C4 positions of GABA first and second turns of the tricarboxylic acid (TCA) cycle. The C4/C3 labeling ratio in GABA was lower than the analogous ratio in glutamate (C2/C3) and higher than that of glutamine (C2/C3). The order of these ratios (glutamate > GABA > glutamine) was not altered by the injection of ammonium acetate. These findings directly indicate that ammonia increases the anaplerotic pathway and that the 13C-skeletons entered glial glutamine through the anaplerotic pathway flow from glia to neuron. A fraction of the glutamine is used in the direct synthesis of GABA via glutamate, whereas the remaining fraction of glutamine passed through the neuronal TCA cycle before synthesizing GABA.

Neurotransmitter release from the medial hyperstriatum ventrale of the chick forebrain accompanying filial imprinting behavior, measured by in vivo microdialysis.

The imprinting behavior of chicks was quantified as a preference score (correct response ratio) achieved in a running wheel apparatus. A total of 249 chicks were exposed to an imprinting stimulus and tested for stimulus-approaching behavior. The chicks were then classified as good learners (imprinted), poor learners (non-imprinted) and a gray-zone group, those were 46%, 31% and 23% of the total chicks respectively. Using the classified chicks, the acetylcholine (ACh) and glutamate releases from the medial hyperstriatum ventrale (MHV) of the chick forebrains were determined by in vivo microdialysis. The non-imprinted chicks were used as yoked controls. Increases of ACh and glutamate released were observed in the imprinted chicks during exposure to the imprinting stimulus, whereas there were no changes in the release of these neurotransmitters in the non-imprinted chicks during the imprinting exposure. These results might be indicated that cholinergic and glutamatergic synapses which are newly formed as functioning synapses with imprinting stimulus in the MHV are involved in the performance of imprinting behavior.

In vivo investigation of glutamate-glutamine metabolism in hyperammonemic monkey brain using 13C-magnetic resonance spectroscopy.

To investigate the metabolism of glutamate and glutamine in living monkey brain, a system of in vivo 13C magnetic resonance spectroscopy (MRS) using 1H-decoupled 13C spectroscopy combined with monitoring temperature changes in the brain by MR phase mapping was developed. Serial 13C-NMR spectra of the amino acids glutamate and glutamine were acquired non-invasively over 4 h from anesthetized monkey brain after the intravenous administration of [1-13C]glucose (0.5-1.0 g/kg). In the acute hyperammonemic state induced by the administration of ammonium acetate (77 mg/kg bolus), it was observed that 13C incorporation into glutamine-4 was clearly accelerated, without changes of 13C incorporation into glutamate-4. During hyperammonemia, it was shown directly by [2-13C]glucose administration that the anaplerotic pathway for the TCA cycle was also augmented, contributing to the formation of glutamine in the astroglia.

In vivo 3D localized 13C spectroscopy using modified INEPT and DEPT.

The 3D localized 13C spectroscopy methods LINEPT and LODEPT, which are modifications of INEPT and DEPT, are proposed. As long as a 13C inversion pulse (180-degree pulse) is applied at 1/(4J) before the proton echo time in LINEPT and a 13C excitation pulse (90-degree pulse) is applied at 1/(2J) before the proton echo time in LODEPT, the proton echo time can be set to any value longer than 1/(2J) in LINEPT and longer than 1/J in LODEPT. As a result, the proton and the 13C pulses can be applied separately and these proton pulses can be made slice-selective pulses. These localization features of LINEPT and LODEPT were evaluated using a phantom consisting of a cylinder filled with ethanol placed inside another cylinder filled with oil, and localized ethanol spectra could be obtained. In vivo 3D localized 13C spectra from the brain of a monkey could be obtained using decoupled LINEPT, and glutamate C-4 appeared directly after the administration of glucose C-1, followed by the appearance of glutamate C-2, C-3 and glutamine C-2, C-3, C-4.

Measurement of amino acid metabolism derived from [1-13C]glucose in the rat brain using 13C magnetic resonance spectroscopy.

To clarify the unique characteristics of amino acid metabolism derived from glucose in the central nervous system (CNS), we injected [1-13C]glucose intraperitoneally to the rat, and extracted the free amino acids from several kinds of tissues and measured the amount of incorporation of 13C derived from [1-13C]glucose into each amino acid using 13C-magnetic resonance spectroscopy (NMR). In the adult rat brain, the intensities of resonances from 13C-amino acids were observed in the following order: glutamate, glutamine, aspartate, gamma-aminobutyrate (GABA) and alanine. There seemed no regional difference on this labeling pattern in the brain. However, only in the striatum and thalamus, the intensities of resonances from [2-13C]GABA were larger than that from [2,3-13C]aspartate. In the other tissues, such as heart, kidney, liver, spleen, muscle, lung and small intestine, the resonances from GABA were not detected and every intensity of resonances from 13C-amino acids, except 13C-alanine, was much smaller than those in the brain and spinal cord. In the serum, 13C-amino acid was not detected at all. When the rats were decapitated, in the brain, the resonances from [1-13C]glucose greatly reduced and the intensities of resonances from [3-13C]lactate, [3-13C]alanine, [2, 3, 4-13C]GABA and [2-13C]glutamine became larger as compared with those in the case that the rats were sacrificed with microwave. In other tissues, the resonances from [1-13C]glucose were clearly detected even after the decapitation. In the glioma induced by nitrosoethylurea in the spinal cord, the large resonances from glutamine and alanine were observed; however, the intensities of resonances from glutamate were considerably reduced and the resonances from GABA and aspartate were not detected. These results show that the pattern of 13C label incorporation into amino acids is unique in the central nervous tissues and also suggest that the metabolic compartmentalization could exist in the CNS through the metabolic trafficking between neurons and astroglia.

Origin of brain 2',3'-cyclic-nucleotide 3'-phosphodiesterase doublet.

The present study established that 2',3'-cyclic-nucleotide 3'-phosphodiesterase doublet common to mammalian brain originates from an alternative splicing. Peptides specific to the predicted larger translation product were synthesized and antisera against these peptides were prepared. Immunostaining of SDS/PAGE blots showed that the antisera react with the larger protein, but not with the smaller protein, of 2',3'-cyclic-nucleotide 3'-phosphodiesterase doublet in all mammals studied.

Immunohistochemical study of pancreatic cystadenocarcinoma.

Seven cases of pancreatic cystadenocarcinoma were studied clinicopathologically and immunohistochemically. Four patients died of the disease or recurrence with metastasis to the liver and peritoneum within 2 yr after surgery. The remaining three patients are well after surgery. To distinguish the cystoadenocarcinoma with excellent prognosis from that with poor prognosis, we performed immunohistochemical staining with monoclonal antibodies directed against tumor markers. Five specimens were strongly and diffusely reactive with tumor marker antibodies, whereas two were reactive with the apical portion of lining epithelial cells. With the findings of the immunohistochemical examination, the diagnosis of two patients could be revised from cystadenocarcinoma to premalignancy. Thus, immunohistochemical examination with tumor markers could correlate with the clinical outcome of the patients and is useful in distinguishing two distinct populations of mucinous cystic tumor.

Presence of a insulin-like growth factor I (somatomedin C) immunoreactive substance in GH producing cells in the bovine anterior pituitary.

Using a double immunoenzyme labelling method with avidin-biotin-horseradish peroxidase and -alkaline phosphatase complexes, we clearly demonstrated that recombinant human IGF-I immunoreactive substance was found in the GH producing cells of the bovine anterior pituitary.

Factors contributing to cerebral hypomyelination in the growth hormone-deficient little mouse.

We attempted to delineate the events leading to hypomyelination in the brain of the little mouse, a promising murine model of isolated growth hormone deficiency. At 20 days of age, the mutant mouse brain weighed less than its normal counterpart, and this difference in brain weight persisted. Increase in CNPase activity was found to be suppressed in the cerebrum throughout the developmental stage, but not in the other parts of the brain. Differences in cerebral DNA content between the little and normal mice first became apparent on the 10th day of age. Thereafter, the rate of increase in the little brain consistently lagged behind the normal. [3H]Thymidine incorporation into the DNA fraction in vivo on the 7th day of age, when glial cell proliferation in the normal cerebrum is most active, was approximately half that of the controls in all parts of the little brain. These findings indicate that the hypomyelination of the mutant cerebrum might result from reduced oligodendroglial proliferation due to growth hormone deficiency.

Differences in ME-LI and VIP-LI in discrete brain regions of seizure-naive and seizure-experienced El mice.

In an attempt to elucidate the relationship between endogenous methionine-enkephalin (ME) and vasoactive intestinal polypeptide (VIP) with generalized seizures, we determined regional brain levels of ME-like and VIP-like immunoreactivity (ME-LI and VIP-LI) in El mice during and after seizures induced by repeated tossing stimulation. The levels of ME-LI in the striatum and hippocampus of seizure-naive El mice (El-) were lower than those of the control ddY mice, the mother strain of El mice. Conversely, the level of VIP-LI in the medulla oblongata and pons of El- was higher than that of ddY mice. The level of ME-LI in the striatum of seizure-experienced El mice (El+) killed 96 hours after three consecutive seizures was high, while levels of VIP-LI in the striatum and hypothalamus were low, in comparison to those of El- mice. A detailed time-course study revealed that seizures in El mice caused (1) significant decreases in levels of ME-LI in the striatum and hippocampus during seizures, (2) a significant decrease of VIP-LI content in the striatum 3 hours after seizures, and (3) a significant increase in hypothalamic VIP-LI 9 hours after seizures. These observations suggest that ME and VIP may play some role in El mouse seizures.

Reduced vasoactive intestinal polypeptide immunoreactivity in the pituitaries of hormone-deficient mutant mice.

The prolactin-producing cells of the bovine anterior pituitary were found to contain a vasoactive intestinal polypeptide (VIP) immunoreactive substance, thus suggesting a role for VIP in the regulation of prolactin release. The pituitaries of the dw and lit strains of mutant mice, congenitally deficient in prolactin-producing cells, and hyt mice, which were found to have reduced numbers of prolactin-producing cells, showed a markedly reduced VIP immunoreactivity. Hypothalamic VIP immunoreactivity, however, was found to be unchanged in the three strains of mutant mice, indicating that the high concentration of VIP in the hypothalamus does not derive from the adenohypophysis through retrograde flow. The deficiency in the mutant mice seems to be due to the lack of prolactin target cells in the pituitary.

Seizure-induced alterations in the metabolism of hippocampal opioid peptides suggest opioid modulation of seizure-related behaviors.

The evidence accumulated so far indicates that seizure activity exerts profound changes on the metabolism of opioid peptides in the hippocampus. Our data consistently show a large transient decrease in dynorphin and a modest decrease in enkephalin in the hippocampus following either a single ECS or KA injection. These initial reductions, which are indicative of increased release, may trigger the biosynthetic process of hippocampal opioids and result in an overproduction of the peptides seen in the rebound phase. However, the amount and timing of the rebound in enkephalin and dynorphin levels in response to repeated ECS, amygdaloid kindling, or KA differ drastically: a rapid and sustained increase in ME-LI follows all three treatments, in contrast to a slow recovery after a large and sustained decrease in DN-LI induced by repeated ECS and amygdaloid kindling. These results, which are unique to the hippocampus, suggest that differential mechanisms are operative in regulating the metabolism of these two opioid peptides in the hippocampus. It is likely that a well-coordinated regulation of hippocampal function can be achieved through the differential release of enkephalin and dynorphin and their subsequent interactions at different subtypes of opioid receptors following seizure activities. From a functional point of view, our data provide a neurochemical correlate of previous reports that brain opioid peptides may mediate ECS-induced behavioral alterations, such as changes in seizure threshold, postictal depression, and retrograde amnesia. The robust changes in the levels of opioid peptides in kindled rats, plus shortening of the kindling process by pretreatment with mu opioid antagonists, strongly suggest the involvement of brain opioid peptides in the development of kindling. Finally, these studies show clear evidence that enkephalin in the hippocampus is important in KA-induced WDS, a component of the opiate withdrawal syndrome in rodents (Isaacson and Lanthorn 1981). Further studies should help distinguish the regulatory mechanisms responsible for changes in opioid peptide metabolism during states of hyperexcitability in the hippocampal formation.

Kainic acid as a tool to study the regulation and function of opioid peptides in the hippocampus.

Kainic acid (KA), an excitatory neurotoxin, was used as a tool to study the metabolism of hippocampal opioid peptides and their functional role in the expression of wet-dog shakes (WDS). A single intracerebral injection of KA (1 microgram/rat) caused recurrent motor seizures lasting 3-6 h. During the convulsive period, native Met5-enkephalin-like (ME-LI) and dynorphin A(1-8)-like (DYN-LI) immunoreactivities in hippocampus decreased by 31 and 63%, respectively. By 24 h after dosing, the hippocampal opioid peptides had returned to control levels, and by 48 h ME-LI had increased 270% and DYN-LI 150%. Immunocytochemical analysis revealed that ME-LI and Leu5-enkephalin-like (LE-LI) immunostaining in the mossy fibers of dentate granule cells and the perforant-temporoammonic pathway had decreased visibly by 6 h and had increased markedly by 48 h following KA. A visible decrease in DYN-LI in mossy fiber axons within 6 h was followed by a substantial increase at 48 h. To determine whether the increases in hippocampal ME-LI reflected changes in ME biosynthesis, levels of mRNA coding for preproenkephalin (mRNAenk) and cryptic ME-LI cleaved by enzyme digestion from preproenkephalin were measured. Following the convulsive period (6 h), mRNAenk was 400% of control, and by 24 h, cryptic ME-LI was 300% of control. Increases in native and cryptic ME-LI and in mRNAenk were also noted in entorhinal cortex, but not in hypothalamus or uninjected striatum. Our data suggest that KA-induced seizures cause an increase in ME release, followed by a compensatory increase in ME biosynthesis in the hippocampus and entorhinal cortex. Several lines of evidence from this study have suggested that hippocampal enkephalins are intimately related to KA-elicited WDS. The shaking behavior was attenuated by pretreatment with naloxone or antisera against [Met5]-enkephalin. We also observed that KA-induced WDS can be mimicked by intrahippocampal injection of enkephalin-related peptides. Furthermore, this study demonstrated that intact dentate granule cells are essential for KA- and enkephalin-induced WDS, since a colchicine injection into the ventral hippocampus, which selectively destroys granule cells, abolished this behavior.

Alteration of cerebral ganglioside metabolism in developing Snell dwarf mice.

The ganglioside metabolism of the Snell dwarf cerebrum was examined on postnatal days 15 and 20, by monitoring the rate of incorporation of radioactivity into each ganglioside species from tritiated N-acetyl-D-mannosamine. It was found that the turnover rate of the GM3 ganglioside was reduced throughout the entire period of development, resulting in retardation of A pathway metabolism which becomes abundant during late cerebral development. In addition, the turnover rate of the GM4 species, which is considered related to myelin formation, was also found to be reduced throughout the entire period of cerebral development.