Indian-Ink Perfusion Based Method for Reconstructing Continuous Vascular Networks in Whole Mouse Brain

The topology of the cerebral vasculature, which is the energy transport corridor of the brain, can be used to study cerebral circulatory pathways. Limited by the restrictions of the vascular markers and imaging methods, studies on cerebral vascular structure now mainly focus on either observation of the macro vessels in a whole brain or imaging of the micro vessels in a small region. Simultaneous vascular studies of arteries, veins and capillaries have not been achieved in the whole brain of mammals. Here, we have combined the improved gelatin-Indian ink vessel perfusion process with Micro-Optical Sectioning Tomography for imaging the vessel network of an entire mouse brain. With 17 days of work, an integral dataset for the entire cerebral vessels was acquired. The voxel resolution is 0.35×0.4×2.0 µm³ for the whole brain. Besides the observations of fine and complex vascular networks in the reconstructed slices and entire brain views, a representative continuous vascular tracking has been demonstrated in the deep thalamus. This study provided an effective method for studying the entire macro and micro vascular networks of mouse brain simultaneously.     

SUSP1 antagonizes formation of highly SUMO2/3-conjugated species

Small ubiquitin-related modifier (SUMO) processing and deconjugation are mediated by sentrin-specific proteases/ubiquitin-like proteases (SENP/Ulps). We show that SUMO-specific protease 1 (SUSP1), a mammalian SENP/Ulp, localizes within the nucleoplasm. SUSP1 depletion within cell lines expressing enhanced green fluorescent protein (EGFP) fusions to individual SUMO paralogues caused redistribution of EGFP-SUMO2 and -SUMO3, particularly into promyelocytic leukemia (PML) bodies. Further analysis suggested that this change resulted primarily from a deficit of SUMO2/3-deconjugation activity. Under these circumstances, PML bodies became enlarged and increased in number. We did not observe a comparable redistribution of EGFP-SUMO1. We have investigated the specificity of SUSP1 using vinyl sulfone inhibitors and model substrates. We found that SUSP1 has a strong paralogue bias toward SUMO2/3 and that it acts preferentially on substrates containing three or more SUMO2/3 moieties. Together, our findings argue that SUSP1 may play a specialized role in dismantling highly conjugated SUMO2 and -3 species that is critical for PML body maintenance.     

Acetaminophen-induced antinociception via central 5-HT2A receptors

Acetaminophen is one of the most widely used analgesic drugs. Although the mechanism of analgesic action of acetaminophen is still not known, the involvement of the central serotonin (5-hydroxytryptamine: 5-HT) system is one possibility. In the present study, we examined the antinociceptive effect of acute and chronic intraperitoneally (i.p.) administered acetaminophen by tail flick latency measurements in the rat. A significantly increased tail flick latency was observed in acute and 15-day acetaminophen-treated rats, but not in 30-day acetaminophen-treated rats, at a dose of 400 mg/kg/day. To investigate the plasticity of receptors at postsynaptic membrane, we conducted a series of experiments by radioligand binding method on frontal cortex and brainstem membrane. The technique involved radioligand binding with [phenyl-4-³H]spiperone and ketanserin for studying 5-HT_2A receptor characteristics. A significant decrease in the maximum number of 5-HT_2A binding sites (B_max) was demonstrated in all treatment groups with acetaminophen 300 and 400 mg/kg on frontal cortex membrane, whereas the value of the dissociation equilibrium constant (K_d) remained unchanged. The down-regulation of 5-HT_2A binding sites in frontal cortex was of a lesser magnitude after 30 days of treatment and the tail flick latency was as in the control animals. These results suggest that down-regulation of 5-HT_2A receptor in response to 5-HT release is a major step in the mechanism underlying analgesia produced by this agent. On the contrary, chronic use of acetaminophen may result in 5-HT depletion, which in turn produces re-adaptation of postsynaptic 5-HT_2A receptors. These data provide further evidence for a central 5-HT-dependent antinociceptive effect of acetaminophen.     

Some Thoughts about Bond Energies,Bond Lengths,and Force Constants

The bond energy (BE) of a polyatomic molecule cannot be measured and, therefore, determination of BEs can only be done within a model using a set of assumptions. The bond strength is reflected by the intrinsic BE (IBE), which is related to the intrinsic atomization energy (IAE) and which represents the energy of dissociation under the provision that the degree of hybridization is maintained for all atoms of the molecule. IBE and BE differ in the case of CC and CH bonds by the promotion, the hybridization, and the charge reorganization energy of carbon. Since the latter terms differ from molecule to molecule, IBE and BE are not necessarily parallel and the use of BEs from thermochemical models can be misleading. The stretching force constant is a dynamical quantity and, therefore, it is related to the bond dissociation energy (BDE). Calculation and interpretation of stretching force constants for local internal coordinate modes are discussed and it is demonstrated that the best relationship between BDEs and stretching force constants is obtained within the model of adiabatic internal modes. The valence stretching force constants are less suitable since they are related to an artificial bond dissociation process with geometrical relaxation effects suppressed, which leads to an intrinsic BDE (IBDE). In the case of AX_n molecules, symmetric coordinates can be used to get an appropriate stretching force constant that is related to the BE. However, in general stretching force constants determined for symmetry coordinates do not reflect the strength of a particular bond since the related dissociation processes are strongly influenced by the stability of the products formed.     

Analysis of the spatial organization of the XL chromosome attachment site in nurse cell nuclei of the malaria mosquito <Emphasis Type="Italic">Anopheles atroparvus</Emphasis>

The spatial position of the site of XL chromosome attachment to the nuclear envelope of ovarian nurse cells relative to the oocyte has been analyzed in the malaria mosquito Anopheles atroparvus van Thiel. The XL chromosome attachment sites in the oocyte-nurse cell system of this species have been demonstrated to be orderly arranged, with the attachment sites in two out of three nurse cells in the same layer identically oriented relative to the oocyte.     

Constructing the rodent stereotaxic brain atlas: a survey

Science China Life Sciences - The stereotaxic brain atlas is a fundamental reference tool commonly used in the field of neuroscience. Here we provide a brief history of brain atlas development and...