Reduced [3H]IP3 binding but unchanged IP3 receptor levels in the rat hippocampus CA1 region following transient global ischemia and tolerance induction

Changes in inositol (1,4,5)-trisphosphate (IP3) binding properties and the protein level of the IP3 receptor have been reported in different pathological conditions in the brain, e.g. cerebral ischemia, Alzheimer's disease, and Huntingtons disease. We used the 4-vessel occlusion model in rat brain to investigate the effect of transient ischemia insults on the IP3 receptor mRNA level, the IP3 receptor protein level and [3H]IP3 binding. Recirculation periods were limited (1-72 h) to avoid the development of delayed neuronal death. We found that the IP3 receptor mRNA levels were decreased after damage-inducing ischemia (9 min) in the hippocampus CA1 and CA3 regions. The mRNA levels were unaltered after tolerance-inducing ischemia (3 min). However, [3H]IP3 binding was significantly reduced after both damage- and tolerance-inducing ischemia in the hippocampus CA1 region. Furthermore, all investigated brain areas showed a decreased [3H]IP3 binding when tolerance-inducing ischemia was followed by a second ischemic insult (3 + 8.5 min ischemia). The IP3 receptor protein levels remained constant in all investigated brain areas. These results indicate that a reduced [3H]IP3 binding capability in the particularly vulnerable areas occurs as an early consequence of cerebral ischemia, before IP3 receptor protein levels are reduced in these areas. Structural or conformational changes altering IP3 binding may be of necessity on the pathway leading to down-regulation of IP3 receptor protein levels, as observed by others.     

Topologic distribution of different types of neurons in the human putamen

OBJECTIVE: To test the assumption that the various types of neuron in the human putamen appear to be randomly distributed and to quantify the way in which they are arranged, stochastic geometry, multivariate analysis and the interactive evaluation technique were employed. STUDY DESIGN: Twenty-seven human putamina without demonstrable signs of neurologic change were dissected out, fixed in 4% formalin and embedded in paraffin. The 20-micron paraffin sections were stained in an aldehyde-fuchsin and cresyl-violet solution, which makes it possible to distinguish between seven different neuron populations in the putamen. The gravity centers, size and form factors of these neurons were determined morphometrically under a light microscope. The data obtained were used to calculate the spatial distribution of the neurons by interactive and structure analytical methods. RESULTS: Visual point field analysis revealed an irregular arrangement of the different types of neurons. Point process analysis detected a significant hard core process of type 1 and a cluster process of type 6 neurons. With nearest neighborhood analysis, significant differences were found between certain populations of neurons and Poisson processes. Comparison of the results of multivariate cluster analysis with the investigator-dependent results of visual point field analysis showed clear differences. CONCLUSION: By means of structure analytical methods, the arrangement of different populations of neurons can be demonstrated. Some neuronal distributions are detectable only by using one of these techniques. The question of random or nonrandom distribution of the neurons in the human putamen can now be answered definitively: arrangement of the different populations of neurons is structured.     

Biosynthesis of alginate. 3. Tritium incorporation with polymannuronic acid 5-epimerase from Azotobacter vinelandii

Incubation of polymannuronic acid in tritiated water with the polymannuronic acid C-5-epimerase isolated from Azotobacter vinelandii led to incorporation of tritium into the glycuronan. Hydrolysis of the labelled glycuronan and separation of the uronic acids demonstrated that 92% of the activity was present in the guluronic acid produced by the epimerase. There was also a small, but significant, incorporation into the mannuronic acid. The results are discussed in relation to the present knowledge of the enzymic epimerisations, and it is suggested that the first step in the reaction is an abstraction of H-5.     

Penicillin acylase from E. coli: unique gene-protein relation.

The nucleotide sequence of the gene (pac) coding for penicillin G acylase from E. coli ATCC 11105 was determined and correlated with the primary structure of the two constituent subunits of this enzyme. The pac gene open reading frame consists of four structural domains: Nucleotide positions 1-78 coding for a signal peptide, positions 79-705 coding for the alpha subunit, positions 706-867 coding for a spacer peptide, and positions 868-2538 coding for the beta subunit. Plasmids were constructed which direct the synthesis of a pac gene product lacking the signal peptide, and the synthesis of the alpha subunit or the beta subunit. The following results were obtained: The two dissimilar subunits are processing products of a single precursor polypeptide; the spacer peptide is removed during processing; the precursor polypeptide lacking the signal sequence is accumulated in the cytoplasm; it is not processed proteolytically in the cytoplasm and it does not display enzyme activity. Processing, therefore, requires translocation through the cytoplasmic membrane; processing follows a distinct sequential pathway in vitro.     

A cationic electron spin resonance probe used to analyze cation interactions with lipopolysaccharide

The partitioning of a cationic electron spin resonance probe, 4-(dodecyl dimethyl ammonium)-1-oxyl-2,2,6,6,-tetramethyl piperidine bromide, into lipopolysaccharide from $\text{Escherichia}\text{coli}$ W1485 was shown to increase markedly above approximately 15°C, presumably reflecting a thermal transition. Partitioning was also highly dependent on probe and lipopolysaccharide concentrations, and Scatchard analysis of electrodialyzed lipopolysaccharide revealed a single non-interactive binding site for the probe. Several cations were able to displace probe bound to this site. At concentrations above 30 μM, Ca²⁺ and Mg²⁺ displaced probe bound to electrodialyzed lipopolysaccharide while various polyamines and other cations were less effective. Since this probe is very sensitive to the environment of the lipopolysaccharide, it should prove to be a valuable tool in analyzing lipopolysaccharide structure and interactions with other molecules.     

Age/size relations and food of two snailfishes,Liparis gibbus and Careproctus reinhardii (Teleostei,Liparididae) from Spitsbergen coastal waters

Summary The snailfish family Liparididae was well represented in bottom trawl hauls (205–370 m) from the Spitsbergen area, with Liparis gibbus being the dominant species. Careproctus reinhardti was less numerous. The present paper is based on 539 specimens of C. gibbus (size range 6–25cm) and 120 specimens of L. reinhardti (size range 5–26 cm). Both species showed a rather similar size and age distribution. The stomach contents reveal that both snailfish species feed both benthically and pelagically. Crustaceans, especially amphipods and decapods, were the most common prey items. With increasing size of the fish, the decapod Pandalus borealis becomes more important, particularly for L. gibbus. Juvenile Liparis (1.3–4.3 cm in length) were found pelagically (35–200 m), and their diet mainly consisted of copepods and young hyperiid amphipods.     

Design and Investigation of PolyFermS In Vitro Continuous Fermentation Models Inoculated with Immobilized Fecal Microbiota Mimicking the Elderly Colon

In vitro gut modeling is a useful approach to investigate some factors and mechanisms of the gut microbiota independent of the effects of the host. This study tested the use of immobilized fecal microbiota to develop different designs of continuous colonic fermentation models mimicking elderly gut fermentation. Model 1 was a three-stage fermentation mimicking the proximal, transverse and distal colon. Models 2 and 3 were based on the new PolyFermS platform composed of an inoculum reactor seeded with immobilized fecal microbiota and used to continuously inoculate with the same microbiota different second-stage reactors mounted in parallel. The main gut bacterial groups, microbial diversity and metabolite production were monitored in effluents of all reactors using quantitative PCR, 16S rRNA gene 454-pyrosequencing, and HPLC, respectively. In all models, a diverse microbiota resembling the one tested in donor’s fecal sample was established. Metabolic stability in inoculum reactors seeded with immobilized fecal microbiota was shown for operation times of up to 80 days. A high microbial and metabolic reproducibility was demonstrated for downstream control and experimental reactors of a PolyFermS model. The PolyFermS models tested here are particularly suited to investigate the effects of environmental factors, such as diet and drugs, in a controlled setting with the same microbiota source.