Electroencephalographic changes with age in male mice.

Electroencephalographic (EEG) changes, as measured by the awake state, slow-wave sleep (SWS), rapid-eye movement (REM) patterns and ratio of REM/total sleep, were recorded in aging male mice of DBA/2J and C57BL/6J strains. Results indicate that there is a significant increase in the awake state accompanied by significant decrease in SWS with advancing age for both strains, although these changes appear more pronounced in DBA/2J mice than C57BL/6J mice. Of considerable significance is the finding that REM sleep is absent in mice of DBA/2J strain at 23.5 months of age. Based on these findings, the conclusion was reached that strain DBA/2J ages significantly faster than C57BL/6J. The difference in aging between the two strains emphasizes the need for additional studies dealing with genetic aspects of aging.     

Reconstitution of an active calcium pump in sarcoplasmic reticulum.

Recovery of calcium transport and calcium-activated ATPase activity was studied in relation to the retention of protein components in sarcoplasmic reticulum reconstituted after solubilization with deoxycholate and centrifugation, followed by removal of the detergent from the supernatant by dialysis. Control sarcoplasmic reticulum was similarly treated except for omission of deoxycholate. Maximum capacity for oxalate- and phosphate-supported calcium uptake was increased 2- to 3-fold in reconstituted sarcoplasmic reticulum compared to original and control. Calcium uptake velocity of the reconstituted sarcoplasmic reticulum was approximately 80% that of original and 90% of control sarcoplasmic reticulum. Calcium uptake/ATP hydrolysis ratio was approximately 2 in the original sarcoplasmic reticulum and decreased to approximately 1 in the control and reconstituted sarcoplasmic reticulum. Calcium storage in the absence of calcium-precipitating anion was approximately 85% in control and 70% in reconstituted sarcoplasmic reticulum, compared to the original sarcoplasmic reticulum. Ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid-induced calcium release after phosphate-supported calcium uptake was slower in reconstituted sarcoplasmic reticulum than in original or control sarcoplasmic reticulum. Polyacrylamide gel electrophoresis of original and control sarcoplasmic reticulum showed similar amounts of protein components of approximately 93,000, 59,000, 50,000, 30,000 to 37,000, and 20,000 to 26,000 daltons. Reconstituted sarcoplasmic reticulum, however, lost over 85% of the 50,000- and 20,000- to 26,000-dalton proteins while retaining most of its calcium transport functions.     

Antispacer peptide nucleic acids for sequence-specific CRISPR-Cas9 modulation

Despite the rapid and broad implementation of CRISPR-Cas9-based technologies, convenient tools to modulate dose, timing, and precision remain limited. Building on methods using synthetic peptide nucleic acids (PNAs) to bind RNA with unusually high affinity, we describe guide RNA (gRNA) spacer-targeted, or ‘antispacer’, PNAs as a tool to modulate Cas9 binding and activity in cells in a sequence-specific manner. We demonstrate that PNAs rapidly and efficiently target complexed gRNA spacer sequences at low doses and without design restriction for sequence-selective Cas9 inhibition. We further show that short PAM-proximal antispacer PNAs achieve potent cleavage inhibition (over 2000-fold reduction) and that PAM-distal PNAs modify gRNA affinity to promote on-target specificity. Finally, we apply antispacer PNAs for temporal regulation of two dCas9-fusion systems. These results present a novel rational approach to nucleoprotein engineering and describe a rapidly implementable antisense platform for CRISPR-Cas9 modulation to improve spatiotemporal versatility and safety across applications.     

Hapten-specific IgE antibody responses in mice. VII. Conversion of IgE "non-responder" strains to IgE "responders" by elimination of suppressor T cell activity.

Mice of the inbred strains SJL (H-2s) and AKR (H-2k) are "non-responders" and "low-responders," respectively, in terms of their capacity to develop antibody responses of the IgE class when immunized with conventional proteins and hapten-protein conjugates under conditions optimal for eliciting IgE responses in "high-responder" mice, such as BALB/c (H-2d), to these same antigens. For example, BALB/c mice preimmunized with ASC and then challenged 7 days later with DNP-ASC develop peak augmented primary IgE anti-DNP antibody responses of 320 PCA units, whereas SJL and AKR mice develop responses which are 16-fold and 4-fold lower, respectively. However, pretreatment of the latter two strains with appropriate doses of either x-irradiation (150 R), cyclophosphamide (100 mg/kg) or ALS (150 mul) before carrier-preimmunization strikingly enhances the magnitude of IgE antibody responses in such mice to levels as high as 64-fold above those of untreated control mice of the same strains. Evidence obtained in these experiments indicates that the capacity of such maneuvers to to convert poor IgE responders to high responder status reflects elimination of nonantigen-specific suppressor T lymphocytes which are naturally present and normally function to suppress or "dampen" the IgE antibody response in a relatively selective manner. It appears that these cells modulate IgE responses by acting at least at two distinct points: 1) The most effective activity seems to be at the level of induction of carrier-specific helper T cells; 2) A second locus of inhibitory activity is more distal in the response, either impeding helper T cell-B cell cooperative interactions or suppressing B cell differentiation and/or function directly. Taken collectively, these observations demonstrate that the state of poor responsiveness of the SJL and AKR strains for the IgE antibody class is not a reflection of a genetic inability to develop IgE responses but rather a manifestation of a genetic capability to actively inhibit IgE antibody synthesis.     

The cytoplasmic and transmembrane domains of the vaccinia virus B5R protein target a chimeric human immunodeficiency virus type 1 glycoprotein to the outer envelope of nascent vaccinia virions.

The outer envelope of the extracellular form of vaccinia virus (EEV) is derived from the Golgi membrane and contains at least six viral proteins. Transfection studies indicated that the EEV protein encoded by the B5R gene associates with Golgi membranes when synthesized in the absence of other viral products. A domain swapping strategy was then used to investigate the possibility that the B5R protein contains an EEV targeting signal. We constructed chimeric genes encoding the human immunodeficiency virus (HIV) type 1 glycoprotein with the cytoplasmic and transmembrane domains replaced by the corresponding 42-amino-acid C-terminal segment of the B5R protein. Recombinant vaccinia viruses that stably express a chimeric B5R-HIV protein or a control HIV envelope protein with the original cytoplasmic and transmembrane domains were isolated. Cells infected with recombinant vaccinia viruses that expressed either the unmodified or the chimeric HIV envelope protein formed syncytia with cells expressing the CD4 receptor for HIV. However, biochemical and microscopic studies demonstrated that the HIV envelope proteins with the B5R cytoplasmic and transmembrane domains were preferentially targeted to the EEV. These data are consistent with the presence of EEV localization signals in the cytoplasmic and transmembrane domains of the B5R protein.     

The influence of cultivation methods on Shewanella oneidensis physiology and proteome expression

High-throughput analyses that are central to microbial systems biology and ecophysiology research benefit from highly homogeneous and physiologically well-defined cell cultures. While attention has focused on the technical variation associated with high-throughput technologies, biological variation introduced as a function of cell cultivation methods has been largely overlooked. This study evaluated the impact of cultivation methods, controlled batch or continuous culture in bioreactors versus shake flasks, on the reproducibility of global proteome measurements in Shewanella oneidensis MR-1. Variability in dissolved oxygen concentration and consumption rate, metabolite profiles, and proteome was greater in shake flask than controlled batch or chemostat cultures. Proteins indicative of suboxic and anaerobic growth (e.g., fumarate reductase and decaheme c-type cytochromes) were more abundant in cells from shake flasks compared to bioreactor cultures, a finding consistent with data demonstrating that “aerobic” flask cultures were O₂ deficient due to poor mass transfer kinetics. The work described herein establishes the necessity of controlled cultivation for ensuring highly reproducible and homogenous microbial cultures. By decreasing cell to cell variability, higher quality samples will allow for the interpretive accuracy necessary for drawing conclusions relevant to microbial systems biology research.     

Identification and characterization of the niddamycin polyketide synthase genes from Streptomyces caelestis.

The genes encoding the polyketide synthase (PKS) portion of the niddamycin biosynthetic pathway were isolated from a library of Streptomyces caelestis NRRL-2821 chromosomal DNA. Analysis of 40 kb of DNA revealed the presence of five large open reading frames (ORFs) encoding the seven modular sets of enzymatic activities required for the synthesis of a 16-membered lactone ring. The enzymatic motifs identified within each module were consistent with those predicted from the structure of niddamycin. Disruption of the second ORF of the PKS coding region eliminated niddamycin production, demonstrating that the cloned genes are involved in the biosynthesis of this compound.     

Synthesis,semipreparative HPLC separation,biological evaluation,and 3D-QSAR of hydrazothiazole derivatives as human monoamine oxidase B inhibitors

The present study reports on synthesis in high yields (70–99%), HPLC enantioseparation, inhibitory activity against human monoamino oxidases, and molecular modeling including 3D-QSAR studies, of a large series of (4-aryl-thiazol-2-yl)hydrazones (1–45). Most of the synthesized compounds proved to be potent and selective inhibitors of hMAO-B isoform in the micromolar or nanomolar range, thus demonstrating that hydrazothiazole could be considered a good pharmacophore to design new hMAO-B inhibitors. Due to the presence in some derivatives of a chiral center, we also performed a semipreparative chromatographic enantioseparation of these compounds obtained by a stereoconservative pattern. The separated enantiomers were submitted to in vitro biological evaluation to point out the stereorecognition of the active site of the enzyme towards these structures. Finally, a 3D-QSAR study was carried out using Comparative Molecular Field Analysis (CoMFA), aiming to deduce rational guidelines for the further structural modification of these lead compounds.