Measurement of Acetylcholine Release in Freely Moving Rats by Means of Automated Intracerebral Dialysis

The present study demonstrates the feasibility of measuring acetylcholine in perfusion samples collected by means of in vivo brain dialysis in the striata of freely moving rats. The output of the dialysis device was directly connected to an automated sample valve of a HPLC-assay system that comprises a cation exchanger, a post-column enzyme reactor, and an electrochemical detector. The presence of an acetylcholinesterase inhibitor (neostigmine) in the perfusion fluid was required for the detection of acetylcholine in the perfusate. Increasing concentrations of neostigmine induced increasing amounts of acetylcholine. Continuous perfusion with a fixed concentration (2 microM) of neostigmine resulted in gradually increasing amounts of collected acetylcholine over time although a considerable variation between successive samples exists. The brain dialysis technique was further validated by studying the effect of various drugs. Systemically administered atropine increased the output of acetylcholine, whereas the addition of tetrodotoxin to the perfusion fluid resulted in a complete disappearance of the neurotransmitter.     

Determination of small quantities of sulfate (0-12 nmol) in serum, urine, and cartilage of the mouse

The colorimetric benzidine method of K. S. Dodgson and B. Spencer (1953, Biochem. J. 55, 436-440) for the measurement of inorganic sulfate can be scaled down about 100 times by using disposable 96-well microplates instead of individual cuvettes. Ten-microliter samples of serum and urine, derived from mice, can be analyzed in a simple, rapid, and reliable way without sacrificing the animals. Without prior isolation of sulfated glycosaminoglycans, ester sulfate in mouse patellar cartilage is liberated quantitatively as inorganic sulfate upon acid hydrolysis in 3 M HCl for 16 h at 80 degrees C. To this end the articular cartilage layer of the patella must be separated in toto from the underlying bone. Subsequent hydrolysis in polypropylene tubes gives accurate results. In contrast, hydrolysis in borosilicate glass vials is useless, since nanomoles of sulfate added cannot be recovered adequately. The thin patellar cartilage layer obtained from 10-week-old male mice contains about 5 nmol of sulfate, an amount easily measured with the developed microplate benzidine method.     

Intracellular transport and degradation of chylomicron remnants in rat liver cells after in vivo endocytosis

The intracellular transport and degradation of in vivo endocytosed chylomicron remnants labelled with 125I in the protein moiety was studied in rat liver cells by means of subcellular fractionation in Nycodenz and sucrose density gradients. Initially, the radioactivity was located in low-density endosomes and was sequentially transferred to light and dense lysosomes. Data from gel filtration of the light and dense lysosomal fractions showed radioactive material with a molecular weight of about 1000-2000, representing short peptide fragments or amino acids which remain attached to iodinated tyramine cellobiose. In addition, undegraded apoproteins accumulated in both types of lysosome. Our data suggest that endocytosed chylomicron remnant apoproteins are first located in low-density endosomes and are sequentially transferred to light and dense lysosomes. Furthermore, the degradation process starts in the light lysosomes.     

Presence of nucleosomes inPenicillium chrysogenum

We have studied the chromatin structure ofPenicillium chrysogenum. This fungus presents the typical nucleosomal repeat and the core DNA size characteristic of all the eukaryotes. The repeat length (about 180 base pairs) is in the range of those obtained for most fungi (160–180 base pairs) and shorter than in higher eukaryotes. Knowledge aboutP. chrysogenum chromatin structure opens the way to the study of the mechanisms of genetic regulation in this filamentous fungus.     

Further antigenic analyses of the fish pathogenic bacteriumVibrio anguillarum

TenVibrio anguillarum strains were selected for an immunoelectrophoretic study. Evidence was provided for existence of two new K antigens which displayed cross-reactivity. The importance of an exact characterization of surface antigens inV. anguillarum is considered.     

A complex balanced chromosomal rearrangement in repeated abortions

Summary A double balanced reciprocal translocation involving four chromosomes, t(1;19;6;14) (1p11; 19p11; 6q25; 14q21), was found in the phenotypically normal husband in a couple referred because of repeated abortions. Reciprocal translocations, t(6;14), had been transmitted by his mother, his father being apparently homozygous for a translocation comprising pairs 1 and 19-t(1;19)(1;19). The genetic consequences of this complex chromosomal rearrangement are analyzed.     

Fragile sites,chromosome evolution,and human neoplasia

Summary In a study of the possible relationship between human fragile sites, chromosomal rearrangements related to neoplasia, and chromosome regions involved in evolutionary changes, we have found that 17 fragile sites related to cancer, 15 fragile sites not related to cancer, and 17 non-fragile regions also related to human malignancy correspond or are close to bands involved in rearrangements that have taken place during chromosomal evolution in primates.     

Linkage relationship between the genes for adenosine deaminase and S-adenosyl-homocysteine hydrolase on human chromosome 20

Summary The genes for adenosine deaminase (ADA) and Sadenosyl homocysteine hydrolase (AHCY or SAHH) are known to be syntenic and within measurable distance from each other, on chromosome 20 in man. In the present study an informative family is described in which the recombination fraction (θ) between the respective genes is estimated to be about 0.18. Together with the published finding of θ=0.15 (Eiberg and Mohr 1985) in informative Danish families, the recombination fraction for the pooled data is calculated to be θ=0.14 (in men), (in women) and (both sexes taken together).     

Effect of HCO - 3 concentration in the absorption solution on the energetic coupling of H+-cotransports in roots of Zea mays L.

The effect of HCO ₃ ^- on ion absorption by young corn roots was studied in conditions allowing the independent control of both the pH of uptake solution and the CO₂ partial pressure in air bubbled through the solution. The surface pH shift in the vicinity of the outer surface of the plasmalemma induced by active H⁺ excretion was estimated using the initial uptake rate of acetic acid as a pH probe (Sentenac and Grignon (1987) Plant Physiol. 84, 1367). Acetic acid and orthophosphate uptake rates and NO ₃ ^- accumulation were slowed down, while ⁸⁶Rb⁺ uptake and K⁺ accumulation rates were increased by HCO ₃ ^- . These effects were similar to those induced by 4-(2-hydroxyethyl)-1-piperazineethane sulfonic acid/2-amino-2-(hydroxymethyl)-1,3-propanediol (Hepes-Tris). They were more pronounced when the H⁺ excretion was strong, were rapidly reversible and were not additive to those of Hepes-Tris. The hypothesis is advanced that the buffering system CO₂/H₂CO₃/HCO ₃ ^- accelerated the diffusion of equivalent H⁺ inside the cell wall towards the medium. This attenuated the surface pH shift in the vicinity the plasma membrane and affected the coupling between the proton pump and cotransport systems.Abbreviations FW fresh weight - Hepes 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid - J_aa acetic acid influx - J_K ⁺ K⁺ influx - J_Pi orthophosphate influx - Mes 2-(N-morpholino)ethanesulfonic acid - pCO₂ CO₂ partial pressure - Tris 2-amino-2-(hydroxymethyl)-1,3-propanediol     

A major histocompatibility locus in fish: serological identification and segregation of transplantation antigens in the common carp (Cyprinus carpio L.)

In this study, experiments are described that were designed to investigate whether fish have an immune regulatory systems similar to the major histocompatibility complex (MHC) in higher vertebrate species. From combinations of gynogenetic carp showing either slow of fast rejection of skin transplants, the latter were chosen for alloantiserum production by hyperimmunization with peripheral blood leucocytes. The resulting alloantisera were analyzed for hemagglutinating reactivity with gynogenetic siblings and proved to be operationally monoscpecific in absorption experiments. The serologically determined carp erythrocyte specificites were shown to correspond to two codominantly expressed allelic products of a single locus and were designated K1 and K2, respectively. Flow cytometer analysis revealed that the same products are also present on leucocytes from peripheral blood, thymus, spleen, and pronephros.K1-andK2-homozygous second-generation gynogenetic siblings were used to study the histocompatibiligy nature of the K locus products. Skin transplants between K-allogeneic gynogenetic siblings were rejected significantly faster than within K-syngeneic combinations. Taken together, these data suggest that theK locus incorporates MHC class I-like characteristics.