Does alternative exon usage contribute to serotonin receptor heterogeneity?

We have previously isolated serotonin 5-HT_1C receptor cDNA clones. In contrast to most other receptors coupled to GTP binding proteins, the 5-HT_1C receptor gene contains several introns in its coding region. A similar exon-intron distribution is found in the 5-HT₂ receptor gene. The presence of large introns tempted us to test whether exchange of exons contributes to serotonin receptor heterogeneity. Therefore, blots with RNAs from different regions of the brain and brain slices were hybridized in situ with probes representing individual exons. We did not find any evidence for the exchange of exons which should result in an unequal distribution of hybridization signals found with the exon-specific probes. With the methodology used we should be able to see differential splicing in the form where individual exons are used alternatively resulting in mRNAs coding for different serotonin receptor types. We would not, however, see if a given exon can be modified by the alternative use of several splice-junctions.     

A rapid method for determination of Proteus vulgaris with a piezoelectric quartz crystal sensor coated with a thin liquid film

A rapid method for microorganism detection using a piezoelectric quartz crystal sensor (PQC) coated with a thin liquid culture medium film was developed and applied to detect the cell number of Proteus vulgaris. This method employed the viscosity and density response of PQC and utilized the coagulation of gelatine medium solution in which the microorganisms had grown to determine the microorganism indirectly. Three time points (TT₁, DT, TT₂) were obtained from the coagulation curve and were found to be in good linear relationship with the logarithm of the initial number of P. vulgaris in the range 1·3 × 10²−1·3 × 10⁵ cells/ml. The detection was rapid and accurate because the coagulation of the thin liquid culture medium film was quick and the time points in the response curve were sharp and so were easy to determine accurately. The detection time was less than 4 h and only a micro sample was needed. A 5 h preincubation was needed before detection. Some experimental conditions are discussed in detail.     

New insights on the molecular features and electrophysiological properties of dinotefuran, imidacloprid and acetamiprid neonicotinoid insecticides

Structural features and hydrogen-bond interactions of dinotefuran (DIN), imidacoloprid (IMI) and acetamiprid (ACE) have been investigated experimentally through analyses of new crystal structures and observations in structural databases, as well as by Density Functional Theory quantum chemical calculations. Several conformations are observed experimentally in the solid state, highlighting the large flexibility of these compounds. This feature is confirmed by the theoretical calculations in the gas phase, the numerous and different energetic minima of the three neonicotinoids being located within a 10kJ/mol range. Comparisons of the observed and simulated data sheds light on the hydrogen-bond (HB) strength of the functional group at the tip of the electronegative fragment of each pharmacophore (NO(2) for DIN and IMI and CN for ACE). This effect originates in the 'push-pull' nature of these fragments and the related extensive electron delocalization. Molecular electrostatic potential calculations provide a ranking of the two fragments of the three neonicotinoid in terms of HB strength. Thus, the NO(2) group of DIN is the strongest HB acceptor of the electronegative fragment, closely followed by the cyano group of ACE. These two groups are significantly more potent than the NO(2) group of IMI. With respect to the other fragments of the three neonicotinoids, the nitrogen atom of the pyridine of IMI and ACE are stronger HB acceptors than the oxygen atom of the furanyl moiety of DIN. Finally, compared to electrophysiological studies obtained from cockroach synaptic and extrasynaptic receptors, DIN appears more effective than IMI and ACE because it strongly increases dose-dependently the ganglionic depolarisation and the currents amplitudes. These data suggest that DIN, IMI and ACE belong to two subgroups which act differently as agonists of insect nicotinic receptors.     

Renal mitochondrial dysfunction in spontaneously hypertensive rats is attenuated by losartan but not by amlodipine

Mitochondrial dysfunction is associated with cardiovascular damage; however, data on a possible association with kidney damage are scarce. Here, we aimed at investigating whether 1) kidney impairment is related to mitochondrial dysfunction; and 2) ANG II blockade, compared with Ca2+ channel blockade, can reverse potential mitochondrial changes in hypertension. Eight-week-old male spontaneously hypertensive rats (SHR) received water containing losartan (40 mg.kg-1.day-1, SHR+Los), amlodipine (3 mg.kg-1.day-1, SHR+Amlo), or no additions (SHR) for 6 mo. Wistar-Kyoto rats (WKY) were normotensive controls. Glomerular and tubulointerstitial damage, systolic blood pressure, and proteinuria were higher, and creatinine clearance was lower in SHR vs. SHR+Los and WKY. In SHR+Amlo, blood pressure was similar to WKY, kidney function was similar to SHR, and renal lesions were lower than in SHR, but higher than in SHR+Los. In kidney mitochondria from SHR and SHR+Amlo, membrane potential, nitric oxide synthase, manganese-superoxide dismutase and cytochrome oxidase activities, and uncoupling protein-2 content were lower than in SHR+Los and WKY. In SHR and SHR+Amlo, mitochondrial H2O2 production was higher than in SHR+Los and WKY. Renal glutathione content was lower in SHR+Amlo relative to SHR, SHR+Los, and WKY. In SHR and SHR+Amlo, glutathione was relatively more oxidized than in SHR+Los and WKY. Tubulointerstitial alpha-smooth muscle actin labeling was inversely related to manganese-superoxide dismutase activity and uncoupling protein-2 content. These findings suggest that oxidant stress is associated with renal mitochondrial dysfunction in SHR. The mitochondrial-antioxidant actions of losartan may be an additional or alternative way to explain some of the beneficial effects of AT1-receptor antagonists.     

EXO5-DNA structure and BLM interactions direct DNA resection critical for ATR-dependent replication restart

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2020年邳州市草地贪夜蛾初迁虫源的迁入路径及气象背景

2020年江苏省邳州市于3月31日发现草地贪夜蛾Spodoptera frugiperda成虫,远早于该地区2019年草地贪夜蛾的始见期6月份。为明确该地区草地贪夜蛾种群性质,利用昆虫轨迹分析方法,模拟分析了2020年江苏省邳州市早期发现的草地贪夜蛾的迁飞路径及天气背景场。结果表明：邳州市2019年12月-2020年2月温度低,草地贪夜蛾无法在此地越冬存活,2020年3月31日所诱捕的草地贪夜蛾为外地迁入,其虫源来自广西和广东西部的周年繁殖区;虽然邳州市3月份常年盛行北风和西北风,西南风发生概率低导致草地贪夜蛾迁入邳州市概率较小,但2020年3月底850 hPa的强西南气流为草地贪夜蛾从我国华南地区迁入邳州市提供了条件。本研究结果阐明了在极端条件下草地贪夜蛾从华南地区迁入江苏省的可能性,丰富了江苏省草地贪夜蛾春季早期迁入的理论依据。     

Mfd Dynamically Regulates Transcription via a Release and Catch-Up Mechanism

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5′-Nucleotidase in spinal meningeal compartments in the rat

Summary The distribution of 5-nucleotidase (5-Nu) is reported in spinal meninges of the rat on the basis of an immunohistochemical and enzyme histochemical investigation. Strong immunoreactivity was found in the arachnoid membrane and in the sheaths of the spinal roots as well as in septa subdividing the roots. Also the superficial layer of the ligamentum denticulatum showed enzyme staining. No immunoreactivity could be detected in the pia mater or along the spinal nerve roots outside the subarachnoid space. Within the arachnoid mater the immunoreactivity was concentrated in the basal zone of the arachnoid membrane, thus appearing as a narrow fluorescent band near the border of the dura. An accentuation of immunoreactivity could be observed in areas where small dural blood vessels approach the subarachnoid space. It is well known that adenine nucleotides released from neural and glial cells of the central nervous system finally reach the cerebrospinal fluid. We presume that 5-Nu in the arachnoid membrane and spinal root sheaths is responsible for the conversion of adenine nucleotides into adenosine and that this conversion is associated with the reabsorption process of cerebrospinal fluid which most probably also takes place in spinal meninges. Adenosine, the product of 5-nucleotidase, could play a role in the reabsorption process by its vasodilatatory effect on dural and epidural vessels.     

The permeability transition pore triggers Bax translocation to mitochondria during neuronal apoptosis

Cerebellar granule neurons (CGNs) require depolarization for their survival in culture. When deprived of this stimulus, CGNs die via an intrinsic apoptotic cascade involving Bim induction, Bax translocation, cytochrome c release, and caspase-9 and -3 activation. Opening of the mitochondrial permeability transition pore (mPTP) is an early event during intrinsic apoptosis; however, the precise role of mPTP opening in neuronal apoptosis is presently unclear. Here, we show that mPTP opening acts as an initiating event to stimulate Bax translocation to mitochondria. A C-terminal (alpha9 helix) GFP-Bax point mutant (T182A) that constitutively localizes to mitochondria circumvents the requirement for mPTP opening and is entirely sufficient to induce CGN apoptosis. Collectively, these data indicate that the major role of mPTP opening in CGN apoptosis is to trigger Bax translocation to mitochondria, ultimately leading to cytochrome c release and caspase activation.