A balance of protein synthesis and proteasome-dependent degradation determines the maintenance of LTP

Long-lasting changes in synaptic strength are thought to play a pivotal role in activity-dependent plasticity and memory. There is ample evidence indicating that in hippocampal long-term potentiation (LTP) the synthesis of new proteins is crucial for enduring changes. However, whether protein degradation also plays a role in this process has only recently begun to receive attention. Here, we examine the effects of blocking protein degradation on LTP. We show that pharmacological inhibition of proteasome-dependent protein degradation, just like inhibition of protein synthesis, disrupts expression of late (L-)LTP. However, when protein degradation and protein synthesis are inhibited at the same time, LTP is restored to control levels, calling into question the commonly held hypothesis that synthesis of new proteins is indispensable for L-LTP. Instead, these findings point to a more facetted model, in which L-LTP is determined by the combined action of synthesis and degradation of plasticity proteins.     

New model of tertiary structure of plant 5S rRNA is confirmed by digestions with alpha-sarcin

The cytotoxin alpha-sarcin was employed to test the model of secondary and tertiary structures of plant 5S rRNAs, which we recently proposed [(1990) Int. J. Biol. Macromol. (in press)]. alpha-Sarcin is a novel ribonuclease that hydrolyzes phosphodiester bonds adjacent to purines in nucleic acids. The digestion pattern obtained for lupin and wheat germ 5S rRNAs strongly suggests the existence of tertiary interactions between residues C34, C35, C36, A37 and G85, G86, G87, U88 as previously proposed. The results on the secondary structure of plant 5S rRNA are in line with a previously proposed model.     

Protein-catalysed protein folding.

A number of proteins, termed chaperonins, have been identified as part of the mechanism of folding other proteins into their biologically active forms. The role of chaperonins appears to be twofold--to prevent illegitimate interactions with other proteins and to facilitate folding, possibly through an energy-dependent, catalytic function. Controlled overexpression of chaperonins may be of therapeutic value in manipulating human immune response and rescuing certain inherited human mutations.     

Real‐time augmented reality for delineation of surgical margins during neurosurgery using autofluorescence lifetime contrast

Current clinical brain imaging techniques used for surgical planning of tumor resection lack intraoperative and real‐time feedback; hence surgeons ultimately rely on subjective evaluation to identify tumor areas and margins. We report a fluorescence lifetime imaging (FLIm) instrument (excitation: 355 nm; emission spectral bands: 390/40 nm, 470/28 nm, 542/50 nm and 629/53 nm) that integrates with surgical microscopes to provide real‐time intraoperative augmentation of the surgical field of view with fluorescent derived parameters encoding diagnostic information. We show the functionality and safety features of this instrument during neurosurgical procedures in patients undergoing craniotomy for the resection of brain tumors and/or tissue with radiation damage. We demonstrate in three case studies the ability of this instrument to resolve distinct tissue types and pathology including cortex, white matter, tumor and radiation‐induced necrosis. In particular, two patients with effects of radiation‐induced necrosis exhibited longer fluorescence lifetimes and increased optical redox ratio on the necrotic tissue with respect to non‐affected cortex, and an oligodendroglioma resected from a third patient reported shorter fluorescence lifetime and a decrease in optical redox ratio than the surrounding white matter. These results encourage the use of FLIm as a label‐free and non‐invasive intraoperative tool for neurosurgical guidance.     

Hiding Behaviour of Longtailed Macaques (Macaca fascicularis). I. Theoretical Background and Data on Mating

During an observational study of captive longtailed macaques (Macaca fascicularis), the ability to hide was analysed within the social context of mating. Low- and middle-ranking males and their female partners chose places for mating where they were partly or entirely concealed more often than easily visible places. These places were not the preferred places of either sex in general, although it was also observed that lower-ranking animals of both sexes lead a more inconspicuous life than high-ranking animals. The probable mechanisms of this phenomenon are discussed: trial-and-error learning or a simple rule of thumb seem to be the appropriate explanations since the choice between different structures of hiding places is not as sharply defined as would be expected if ‘perspective taking’ were the mechanism.     

Specific subsets of immune cells in human decidua differ between normal pregnancy and preeclampsia - a prospective observational study

Background  

Changes in the balance of decidual leucocyte populations may lead to an unfavourable uterine microenvironment which may be associated with the development of preeclampsia (PE). In this study, we therefore investigated the leucocyte subpopulations in decidual tissues of 33 women with preeclampsia and 66 control patients.     

Analysis of residuals from enzyme kinetic and protein folding experiments in the presence of correlated experimental noise

Experimental data from continuous enzyme assays or protein folding experiments often contain hundreds, or even thousands, of densely spaced data points. When the sampling interval is extremely short, the experimental data points might not be statistically independent. The resulting neighborhood correlation invalidates important theoretical assumptions of nonlinear regression analysis. As a consequence, certain goodness-of-fit criteria, such as the runs-of-signs test and the autocorrelation function, might indicate a systematic lack of fit even if the experiment does agree very well with the underlying theoretical model. A solution to this problem is to analyze only a subset of the residuals of fit, such that any excessive neighborhood correlation is eliminated. Substrate kinetics of the HIV protease and the unfolding kinetics of UMP/CMP kinase, a globular protein from Dictyostelium discoideum, serve as two illustrative examples. A suitable data-reduction algorithm has been incorporated into software DYNAFIT [P. Kuzmi?, Anal. Biochem. 237 (1996) 260-273], freely available to all academic researchers from http://www.biokin.com.