The characteristics of vegetative cell growth and akinete formation in the cyanobacterium Dolichospermum planctonicum were examined using three different media (WC, CB, and CT media), and two ...different methods for the recovery of akinetes, i.e. the lysozyme method and the sedimentation-separation method, were compared to evaluate which way was efficient. The equilibrium vegetative cell and akinete density were higher for the WC medium than those for the CB and CT media (p < 0.05), exhibiting ca. 1.23 × 107 ± 1.58 × 106 cells・mL－1 and 1.60 × 104 ± 3.46 × 103 akinetes・mL－1, respectively. These results suggest that the WC medium was appropriate for the cultivation of D. planctonicum. The lysozyme method and the sedimentation-separation method using a separatory funnel were compared to recover the akinetes of D. planctonicum. The results showed that the former method was found to be more successful in separating the akinetes from the vegetative cells, and the recovery rate was also higher (the lysozyme method: 66.7%, the sedimentation-separation method: 55.0%). The results obtained in the present study would be useful to elucidate the mechanisms of akinete germination and/or akinete recruitment from sediment, which could contribute to suppress the cyanobacterial bloom occurrence in the eutrophic lakes.
Amide proton transfer (APT) imaging is a novel molecular MRI technique to detect endogenous mobile proteins and peptides through chemical exchange saturation transfer. We prospectively assessed the ...usefulness of APT imaging in predicting the histological grade of adult diffuse gliomas.
Thirty-six consecutive patients with histopathologically proven diffuse glioma (48.1 ± 14.7 y old, 16 males and 20 females) were included in the study. APT MRI was conducted on a 3T clinical scanner and was obtained with 2 s saturation at 25 saturation frequency offsets ω = -6 to +6 ppm (step 0.5 ppm). δB0 maps were acquired separately for a point-by-point δB0 correction. APT signal intensity (SI) was defined as magnetization transfer asymmetry at 3.5 ppm: magnetization transfer ratio (MTR)asym = (S-3.5 ppm - S+3.5 ppm)/S0. Regions of interest were carefully placed by 2 neuroradiologists in solid parts within brain tumors. The APT SI was compared with World Health Organization grade, Ki-67 labeling index (LI), and cell density.
The mean APT SI values were 2.1 ± 0.4% in grade II gliomas (n = 8), 3.2 ± 0.9% in grade III gliomas (n = 10), and 4.1 ± 1.0% in grade IV gliomas (n = 18). Significant differences in APT intensity were observed between grades II and III (P < .05) and grades III and IV (P < .05), as well as between grades II and IV (P < .001). There were positive correlations between APT SI and Ki-67 LI (P = .01, R = 0.43) and between APT SI and cell density (P < .05, R = 0.38). The gliomas with microscopic necrosis showed higher APT SI than those without necrosis (P < .001).
APT imaging can predict the histopathological grades of adult diffuse gliomas.
Crater morphology and surface age of asteroid (162173) Ryugu are characterized using the high‐resolution images obtained by the Hayabusa2 spacecraft. Our observations reveal that the abundant ...boulders on and under the surface of the rubble‐pile asteroid affect crater morphology. Most of the craters on Ryugu exhibit well‐defined circular depressions, unlike those observed on asteroid Itokawa. The craters are typically outlined by boulders remaining on the rim. Large craters (diameter > 100 m) host abundant and sometimes unproportionally large boulders on their floors. Small craters (<20 m) are characterized by smooth circular floors distinguishable from the boulder‐rich exterior. Such small craters tend to have dark centers of unclear origin. The correlation between crater size and boulder number density suggests that some processes sort the size of boulders in the shallow (<30 m) subsurface. Furthermore, the crater size‐frequency distributions (CSFDs) of different regions on Ryugu record multiple geologic events, revealing the diverse geologic history on this 1‐km asteroid. Our crater‐counting analyses indicate that the equatorial ridge is the oldest structure of Ryugu and was formed 23–30 Myr ago. Then, Ryugu was partially resurfaced, possibly by the impact that formed the Urashima crater 5–12 Myr ago. Subsequently, a large‐scale resurfacing event formed the western bulge and the fossae 2–9 Myr ago. Following this process, the spin of Ryugu slowed down plausibly due to the YORP effect. The transition of isochrons in a CSFD suggests that Ryugu was decoupled from the main belt and transferred to a near‐Earth orbit 0.2–7 Myr ago.
Plain Language Summary
Japan's asteroid explorer Hayabusa2 visited the carbon‐rich, 1‐km asteroid named Ryugu. One of the onboard cameras took many pictures of asteroid's surface. In order to know the history of this asteroid, we estimate the age of different geologic units by counting craters. We also documented how the craters on this asteroid look, to help understand the geology of the carbon‐rich world. We found that the mountain range running along the equator formed 23‐30 million years ago. About 5–12 million years ago, the meteorite impact that formed the biggest crater on this asteroid likely scattered soil around, erasing nearby craters that existed before. Then, about 2–9 million years ago, the western half of this asteroid was wiped out by a large‐scale movement of rocks and pebbles that build this asteroid, because the asteroid was spinning fast and unstable at that time. Then, sometime between 0.2 and 7 million years ago, this asteroid left the home of asteroids located between Mars and Jupiter orbits, and came to the orbit passing near the Earth. During its journey to the near‐Earth orbit, the spin of the asteroid slowed down because of the very weak but effective force by heat radiation from surface rocks.
Key Points
Craters on asteroid Ryugu are documented and counted based on the high‐resolution images obtained with Hayabusa2's telescopic camera
Crater morphology on Ryugu ranges from distinct >100‐m circular depressions to <10 m smooth texture outlined by boulders
Crater chronology reveals multiple resurfacing events on each hemisphere 2–12 Myr ago and Ryugu's departure from the main belt <7 Myr ago
Background and purpose:
The mechanism for the development of post‐haemorrhagic cerebral vasospasm after subarachnoid haemorrhage (SAH) still remains unknown.
Experimental approach:
We investigated ...the role of thrombin and its receptor PAR1 in the development of hyper‐contractility of the basilar artery in a rabbit double haemorrhage model, which received two injections of autologous blood into the cisterna magna.
Key results:
In the basilar artery isolated from the control rabbits, thrombin, only at 10 units ml−1, induced a transient endothelium‐dependent relaxation and a slight smooth muscle contraction. In SAH, the contractile response to thrombin was markedly enhanced, while the endothelium‐dependent relaxant effect of thrombin remained unchanged. The enhancement of the contractile responses was also observed in the absence of endothelium and thrombin induced an enhanced contraction at concentrations higher than 0.3 units ml−1. The contractile response to PAR1‐activating peptide was also enhanced after SAH. However, the contractile responses to high K+ and endothelin‐1, and the myofilament Ca2+‐sensitivity remained unchanged after SAH. An immunoblot analysis suggested the up‐regulation of PAR1 in the smooth muscle of the basilar artery. The heparinization of blood before injection prevented the enhancement of the contractile responses to thrombin and PAR1‐activating peptide.
Conclusions and implications:
The present study demonstrated, for the first time, that the contractile response of the basilar artery to thrombin was markedly enhanced after SAH. Mechanistically, our findings suggested that the activation of thrombin following hemorrhage up‐regulated the expression of PAR1, thereby inducing the hyper‐responsiveness to thrombin.
British Journal of Pharmacology (2007) 152, 1131–1139; doi:10.1038/sj.bjp.0707435; published online 3 September 2007
The recently cloned epithelial Ca2+ channel (ECaC), which is expressed primarily in 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3))-responsive Ca2+ -transporting epithelia, is postulated to constitute ...the rate-limiting step in active Ca2+ reabsorption. In the present study, the effect of 1,25(OH)(2)D(3) was investigated on ECaC mRNA and protein levels in kidneys of rats that were raised on a vitamin D-depleting diet. This diet decreased the serum 1,25(OH)(2)D(3) concentration significantly, which was accompanied by a marked drop in serum Ca2+ level. Both 1,25(OH)(2)D(3) and Ca2+ levels were normalized within 48 h after 1,25(OH)(2)D(3) administration. In 1,25(OH)(2)D(3)-deficient rats, ECaC mRNA and protein levels of the kidney cortex were significantly decreased compared with the repleted animals, suggesting that 1,25(OH)(2)D(3) exerts its stimulatory effect on Ca2+ reabsorption via increased ECaC expression. In agreement with this observation, the elucidated human ECaC promoter contains several consensus vitamin D-responsive elements. ECaC was restricted to the apical membrane of the distal part of the distal convoluted and the connecting tubule. This conclusion was based on only minor overlap with the localization of the thiazide-sensitive NaCl co-transporter and complete co-localization with the 1,25(OH)(2)D(3)-dependent Ca2+ binding protein, calbindin-D(28K). In conclusion, ECaC, present in the distal part of the nephron, is an important target for 1,25(OH)(2)D(3)-mediated Ca2+ reabsorption.
Ejecta morphologies of many Martian craters indicate fluidized emplacement which differs from ballistic emplacement in dry, airless environments. Double Layered Ejecta craters possess particularly ...interesting ejecta morphologies: two lobes and radial lineations on their surface, which probably result from gas‐dominated radial flow during the emplacement. To examine how a radial flow interacts with surface particles to generate some of the observed morphologies on Mars, we have conducted water tank experiments in which a vortex ring encounters a particle layer. The threshold of particle motion and three interaction modes are described by two dimensionless numbers: particle Shields' parameter and particle Reynolds number. Our results show that gas‐dominated flows are possible during cratering and could be used to constrain the ancient Martian environment from observations.
Emotional stimuli have been shown to preferentially engage initial attention but their sustained effects on neural processing remain largely unknown. The present study evaluated whether emotional ...faces engage sustained neural processing by examining the attenuation of neural repetition suppression to repeated emotional faces. Repetition suppression of neural function refers to the general reduction of neural activity when processing a repeated stimulus. Preferential processing of emotional face stimuli, however, should elicit sustained neural processing such that repetition suppression to repeated emotional faces is attenuated relative to faces with no emotional content. We measured the reduction of functional magnetic resonance imaging signals associated with immediate repetition of neutral, angry and happy faces. Whereas neutral faces elicited the greatest suppression in ventral visual cortex, followed by angry faces, repetition suppression was the most attenuated for happy faces. Indeed, happy faces showed almost no repetition suppression in part of the right-inferior occipital and fusiform gyri, which play an important role in face-identity processing. Our findings suggest that happy faces are associated with sustained visual encoding of face identity and thereby assist in the formation of more elaborate representations of the faces, congruent with findings in the behavioral literature.
alpha-Synuclein is presynaptic nerve terminal protein and its immunoreactivity has been observed in such neurodegenerative structures as senile plaques of Alzheimer's disease or Lewy bodies of ...Parkinson's disease. The physiological role of alpha-synuclein is still unknown. It is speculated that alpha-synuclein may be expressed in brain tumors, especially in those showing neuronal differentiation. We examined the immunohistochemical localization of alpha-synuclein in 77 human brain tumors. alpha-Synuclein was widely distributed in the brain tumors showing neuronal differentiation. As a result, positive immunostaining for alpha-synuclein was observed in ganglioglioma, medulloblastoma, neuroblastoma, primitive neuroectodermal tumor, pineocytoma/pineoblastoma, and central neurocytoma. Compared with other neuronal markers, the positive ratio of alpha-synuclein was not as high as synaptophysin, microtubule-associated protein 2, neuron-specific enolase and tau, but it was higher than neurofilament and chromogranin A. The expression of synaptophysin was diffusely observed in the cytoplasm, cellular processes and nucleus in tumors showing neuronal differentiation; however, the expression of alpha-synuclein was predominantly observed in the cytoplasm of the tumors as well as in the cellular processes. On the other hand, non-neuronal brain tumors such as astrocytic tumors or meningiomas were totally negative for alpha-synuclein. In conclusion, the appearance of an alpha-synuclein-positive structure was not limited to neurodegenerative diseases, but could also be detected in neoplastic cells showing neuronal differentiation.
Thirteen children with moyamoya disease who had no apparent cerebral infarction or hemorrhage were examined pre- and postoperatively by means of positron emission tomography (PET) to investigate the ...underlying cerebral circulation and metabolism and the effect of bypass surgery. The preoperative regional cerebral blood flow (rCBF) and mean transit time were significantly decreased and increased, respectively, in the cerebral cortex of these patients compared to control values. The regional cerebral blood volume (rCBV) and the regional oxygen extraction fraction (rOEF) had significantly increased to compensate for the reduced rCBF and perfusion pressure and also to maintain the regional cerebral metabolic rate of oxygen (rCMRO2). In the basal ganglia, rCBV elevation was more prominent than that in the cerebral cortex, although changes in rCBF, rOEF, and rCMRO2 were relatively minor. Postoperative improvements were observed predominantly near the cortex where bypass surgery had been performed and in the basal ganglia. Direct and combined indirect bypass procedures improved cerebral circulation more effectively than single indirect bypass surgery. Although the angiographic findings were not always compatible with the clinical results, the postoperative improvements on PET scans correlated with the disappearance of transient ischemic attacks. In addition to the clinical courses and angiographic findings, PET analysis was indispensable in evaluating the cerebral circulation and metabolism in childhood moyamoya disease.
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