Distribution of vasopressin and oxytocin in rat brain

Arginine-vasopressin and oxytocin in various portions of rat brain were determined by radioimmunoassays. The hormones were extracted from tissue samples into 0.1 N HCl and then purified partially with acetone-petroleum ether extraction. The non-equilibration method was used for the assays. In this method recovery rates of arginine-vasopressin and oxytocin were 73.0 +/- 4.4% and 75.0 +/- 3.8%, respectively. Sensitivities of the assays were 1 pg of arginine-vasopressin and 0.75 pg (0.3 microU) of oxytocin per assay tube. The higher concentrations of arginine-vasopressin and oxytocin were confirmed in the hypothalamo-neurohypophyseal system, where these hormones are synthesized, transported and stored. Relatively high concentrations of these hormones, especially oxytocin, were detected in spinal cord. Amygdala, hippocampus, limbic forebrain and pineal body contained a certain amount of arginine-vasopressin (2-20 pg/mg protein). Oxytocin (1-7 pg/mg protein) was also detected in amygdala, pons and medulla oblongata, pineal body and midbrain. The low concentrations of these hormones were also found in cerebral cortex and cerebellum.     

Visual interneurons in the lobula complex of the fleshfly,Boettcherisca peregrina

Summary The physiology and morphology of visual interneurons in the lobula complex of the fleshfly,Boettcherisca peregrina, were studied using intracellular recordings and intracellular cobalt stainings, respectively. Using responses to movements of a spot of light and on-off stimuli at single positions, we classified the interneurons into five physiological groups ON, OFF, ON-OFF, nondirectional motion sensitive (NDM) and directional motion sensitive (DM) neurons. They could be further divided into four morphological types, depending on the location and extent of their dendrites and terminal branches.     

Dam Methylation Participates in the Regulation of PmrA/PmrB and RcsC/RcsD/RcsB Two Component Regulatory Systems in Salmonella enterica Serovar Enteritidis

The absence of Dam in Salmonella enterica serovar Enteritidis causes a defect in lipopolysaccharide (LPS) pattern associated to a reduced expression of wzz gene. Wzz is the chain length regulator of the LPS O-antigen. Here we investigated whether Dam regulates wzz gene expression through its two known regulators, PmrA and RcsB. Thus, the expression of rcsB and pmrA was monitored by quantitative real-time RT-PCR and Western blotting using fusions with 3×FLAG tag in wild type (wt) and dam strains of S. Enteritidis. Dam regulated the expression of both rcsB and pmrA genes; nevertheless, the defect in LPS pattern was only related to a diminished expression of RcsB. Interestingly, regulation of wzz in serovar Enteritidis differed from that reported earlier for serovar Typhimurium; RcsB induces wzz expression in both serovars, whereas PmrA induces wzz in S. Typhimurium but represses it in serovar Enteritidis. Moreover, we found that in S. Enteritidis there is an interaction between both wzz regulators: RcsB stimulates the expression of pmrA and PmrA represses the expression of rcsB. Our results would be an example of differential regulation of orthologous genes expression, providing differences in phenotypic traits between closely related bacterial serovars.     

Placental Mammals Acquired Functional Sequences in NRK for Regulating the CK2–PTEN–AKT Pathway and Placental Cell Proliferation

The molecular evolution processes underlying the acquisition of the placenta in eutherian ancestors are not fully understood. Mouse NCK-interacting kinase (NIK)-related kinase (NRK) is expressed highly in the placenta and plays a role in preventing placental hyperplasia. Here, we show the molecular evolution of NRK, which confers its function for inhibiting placental cell proliferation. Comparative genome analysis identified NRK orthologs across vertebrates, which share the kinase and citron homology (CNH) domains. Evolutionary analysis revealed that NRK underwent extensive amino acid substitutions in the ancestor of placental mammals and has been since conserved. Biochemical analysis of mouse NRK revealed that the CNH domain binds to phospholipids, and a region in NRK binds to and inhibits casein kinase-2 (CK2), which we named the CK2-inhibitory region (CIR). Cell culture experiments suggest the following: 1) Mouse NRK is localized at the plasma membrane via the CNH domain, where the CIR inhibits CK2. 2) This mitigates CK2-dependent phosphorylation and inhibition of PTEN and 3) leads to the inhibition of AKT signaling and cell proliferation. Nrk deficiency increased phosphorylation levels of PTEN and AKT in mouse placenta, supporting our hypothesis. Unlike mouse NRK, chicken NRK did not bind to phospholipids and CK2, decrease phosphorylation of AKT, or inhibit cell proliferation. Both the CNH domain and CIR have evolved under purifying selection in placental mammals. Taken together, our study suggests that placental mammals acquired the phospholipid-binding CNH domain and CIR in NRK for regulating the CK2–PTEN–AKT pathway and placental cell proliferation.     

Smell-induced gamma oscillations in human olfactory cortex are required for accurate perception of odor identity

Studies of neuronal oscillations have contributed substantial insight into the mechanisms of visual, auditory, and somatosensory perception. However, progress in such research in the human olfactory system has lagged behind. As a result, the electrophysiological properties of the human olfactory system are poorly understood, and, in particular, whether stimulus-driven high-frequency oscillations play a role in odor processing is unknown. Here, we used direct intracranial recordings from human piriform cortex during an odor identification task to show that 3 key oscillatory rhythms are an integral part of the human olfactory cortical response to smell: Odor induces theta, beta, and gamma rhythms in human piriform cortex. We further show that these rhythms have distinct relationships with perceptual behavior. Odor-elicited gamma oscillations occur only during trials in which the odor is accurately perceived, and features of gamma oscillations predict odor identification accuracy, suggesting that they are critical for odor identity perception in humans. We also found that the amplitude of high-frequency oscillations is organized by the phase of low-frequency signals shortly following sniff onset, only when odor is present. Our findings reinforce previous work on theta oscillations, suggest that gamma oscillations in human piriform cortex are important for perception of odor identity, and constitute a robust identification of the characteristic electrophysiological response to smell in the human brain. Future work will determine whether the distinct oscillations we identified reflect distinct perceptual features of odor stimuli.

Intracranial recordings from human olfactory cortex reveal a characteristic spectrotemporal response to odors, including theta, beta and gamma oscillations, and show that high-frequency responses are critical for accurate perception of odors.     

Optimal covalent immobilization of glucose oxidase-containing liposomes for highly stable biocatalyst in bioreactor

The glucose oxidase-containing liposomes (GOL) were prepared by entrapping glucose oxidase (GO) in the liposomes composed of phosphatidylcholine (PC), dimyristoyl L-alpha-phosphatidylethanolamine (DMPE), and cholesterol (Chol) and then covalently immobilized in the glutaraldehyde-activated chitosan gel beads. The immobilized GOL gel beads (IGOL) were characterized to obtain a highly stable biocatalyst applicable to bioreactor. At first, the glutaraldehyde concentration used in the gel beads activation as well as the immobilizing temperature and time were optimized to enhance the immobilization yield of the GOL to the highest extent. The liposome membrane composition and liposome size were then optimized to obtain the greatest possible immobilization yield of the GOL, the highest possible activity efficiency of the IGOL, and the lowest possible leakage of the entrapped GO during the GOL immobilization. As a result, the optimal immobilization conditions were found to be as follows: the liposome composition, PC/DMPE/Chol = 65/5/30 (molar percentage); the liposome size, 100 nm; the glutaraldehyde concentration, 2% (w/v); the immobilizing temperature, 4 degrees C; and the immobilizing time, 10 h. Furthermore, the optimal IGOL prepared were characterized by its rapidly increasing effective GO activity to the externally added substrate (glucose) with increasing temperature from 20 to 40 degrees C, and also by its high stability at 40 degrees C against not only the thermal denaturation in a long-term (7 days) incubation but also the bubbling stress in a bubble column. Finally, compared to the conventionally immobilized glucose oxidase (IGO), the higher operational stability of the optimal IGOL was verified by using it either repeatedly (4 times) or for a long time (7 days) to catalyze the glucose oxidation in a small-scale airlift bioreactor.     

Developmentally regulated extrachromosomal circular DNA formation in the mesozoan <Emphasis Type="Italic">Dicyema japonicum</Emphasis>

The dicyemid mesozoans are simple multicellular parasites with a long cylindrical axial cell surrounded by a single outer layer of 20 to 30 ciliated peripheral somatic cells. Their larval development proceeds within the axial cell. Here we demonstrate the appearance of extrachromosomal circular DNAs and their fate during early embryogenesis in Dicyema japonicum. These DNAs are highly heterogeneous in sequence, suggesting that they consist of unique--not repetitive--elements. Potential open reading frames were not evident in the elements, so these DNAs are unlikely to have a protein-encoding function. In situ hybridization revealed that the circular DNA elements were restricted to the early embryonic larvae and gradually faded out as larvae approached maturity. Furthermore Southern blot analysis and polymerase chain reaction analysis using a high molecular weight DNA as a template provided evidence that the extrachromosomal DNA circles are originally present in chromosomes. These observations suggest DNA elimination--or selective replication--of the elements from chromosomes during early embryogenesis in dicyemid mesozoans.     

Nrk, an X-linked protein kinase in the germinal center kinase family, is required for placental development and fetoplacental induction of labor

The complete mechanism of labor induction in eutherian mammals remains unclear. Although important roles for the fetus and placenta in triggering labor have been proposed, no gene has been shown to be required in the fetus/placenta for labor induction. Here we show that Nrk, an X-linked gene encoding a Ser/Thr kinase of the germinal center kinase family, is essential in the fetus/placenta for labor in mice. Nrk was specifically expressed in the spongiotrophoblast layer, a fetus-derived region of the placenta, and Nrk disruption caused dysregulated overgrowth of the layer. Due to preferential inactivation of the paternally derived X chromosome in placenta, Nrk heterozygous mutant placentas exhibited a similar defect to that in Nrk-null tissues when the wild-type allele was paternally derived. However, the phenotype was weaker than in Nrk-null placentas due to leaky Nrk expression from the inactivated X chromosome. Crossing of Nrk-null females to wild-type and Nrk-null males, as well as uterine transfer of Nrk-null fetuses to wild-type females, revealed that pregnant mice exhibit a severe defect in delivery when all fetuses/placentas are Nrk-null. In addition, Nrk was not expressed in female reproductive tissues such as the uterus and ovary, as well as the fetal amnion and yolk sac, in pregnant mice. Progesterone and estrogen levels in the maternal circulation and placenta, which control the timing of labor, were unaffected upon Nrk disruption. We thus provide evidence for a novel labor-inducing fetoplacental signal that depends on the X chromosome and possibly arises from the placenta.