The stimulatory effect of beta-endorphin on the plasma prolactin levels was diminished in the rats treated with 6-hydroxydopamine

Intraventicular injection of beta-endorphin (beta LPH_61^?91) in urethane anesthetized male rats led to a dose dependent increase of plasma prolactin levels. Intravenous injection of apomorphine completely abolished the stimulatory effect of beta-endorphin. Animals treated with 6-hydroxydopamine (6-OHDA) and 6-OHDA plus desmethylimipramine showed inhibition of beta-endorphin induced prolactin release. These results suggest that beta-endorphin presynaptically inhibits the activity of dopaminergic neurones, leading to the stimulation of plasma prolactin levels.     

Structural characterization and dynamics of globotetraosylceramide in vascular endothelial cells under TNF-α stimulation

In several vascular inflammatory reactions (i.e. immunity and thrombosis) inflammatory mediators lead to the activation of vascular endothelial cells (EC). To date, a number of functional molecules induced on the surface of activated-EC have been identified. We report here that Globotetraosylceramide (Gb4), a glycosphingolipid expressed in EC, is a novel inducible molecule on EC activated by TNF-α. The cell surface expression of Gb4 is increased in a time-dependent manner under TNF-α stimulation, which shows distinct expression kinetics of major proteins induced by TNF-α on EC. MALDI-TOF-MS analysis revealed that the enhanced Gb4 predominantly contains C24:0 fatty acid in the ceramide moiety. Isolated caveolae/lipid raft-enriched detergent insoluble membrane domains in activated-EC predominantly contain this molecular species of Gb4. Gb4 containing C16:0 fatty acid in the ceramide moiety, which is known to constitute the major species of Gb4 in plasma, is also found as a major molecular species in EC. These observations indicate that Gb4, especially with very long fatty acid, is enhanced in EC during its inflammatory reaction, and suggest the potential utility of Gb4 as a biomarker for monitoring inflammation status of EC involving its related diseases.     

Identification of 57 conventional RFLP and 6 VNTR systems with 32 DNA clones on chromosome 11p15

Fifty-four clones containing human inserts were selected from a cosmid library constructed from a somatic cell hybrid containing chromosome 11p15.3-p15.5 as its only human complement. In 32 of these clones, 63 polymorphic systems were identified with a panel of restriction enzymes: 57 conventional RFLP systems and 6 highly polymorphic VNTR systems. Although we examined the cosmid with only seven enzymes, 18 clones (including 6 VNTRs) were polymorphic with three or more enzymes. The results suggested that DNA sequences on the peritelomeric region of chromosome 11p tend to be highly variable. Because these markers are highly informative, they will be excellent resources for investigations of hereditary diseases and tumor suppressor genes in this region of chromosome 11.     

Characterization and Intracellular Distribution of Pea Phytochrome I Polypeptides Expressed in E. coli

The pea phytochrome I (PI) cDNA clone, pPP1001, was expressedin E. coli. The plasmid pPP1001 contains pea PI cDNA which coversthe entire coding region with the Shine-Dalgarno consensus sequencejoined upstream of the cDNA in an expression vector pNUT6. ThepPP1001 transformants formed typical inclusion bodies when culturedat 32?C. However, when cultured at 37?C or in the presence ofisopropyl-ß-D-thiogalactopyranoside (IPTG) at 32?C,the bacteria lysed before inclusion body formation. Immuno-stainingwith anti-PI monoclonal antibody, mAP5, of transformants fixedby cold methanol showed that stainable materials were distributedin whole cytoplasmic region. When the inclusion bodies wereobserved clearly, the regions corresponding to the inclusionbodies became difficult to stain. Western blot analysis, however,showed that a ca. 100 kDa PI polypeptide was detected in thefraction from inclusion bodies and a ca. 90 kDa PI polypeptidefrom the soluble fraction. The amino acid sequence analysisof purified 100 kDa PI sample indicated that its amino terminusis blocked. However, minor signals in one experiment yieldeda sequence corresponding to the expected amino terminus of peaPI except for the initiation methionine. One of the anti-peaPI monoclonal antibodies, mAP9, that recognizes the near N-terminusof pea phytochrome was reactive to the 100 kDa polypeptide. (Received June 22, 1990; Accepted November 18, 1990)     

On the glutamate transport through cell envelope vesicles of Halobacterium halobium

Glutamate uptake by envelope vesicles of Halobacterium halobium was measured. Previous authors showed that the glutamate uptake needs the illumination as well as Na+ gradient across the membrane. The latter is considered to be the driving force for the uptake. No satisfactory explanation for the necessity of the illumination has not been given. We found that in the absence of Cl- in the medium, only Na+ gradient was enough to induce the glutamate uptake, i.e. no illumination was needed. Glutamate uptake was measured with various strains of H. halobium. We found that the envelope vesicles prepared from strains containing no bacteriorhodopsin showed the glutamate uptake in the dark and in the presence of Cl- in the medium provided only that Na+ gradient is imposed.     

Determination of membrane potential with lipophilic cations: correction of probe binding

The binding of lipophilic ions to the membrane of envelope vesicles from Halobacterium halobium was examined in the absence and presence of membrane potential. The lipophilic ions used constitute a homologous series of (Phe)₃-P⁺-(CH₂)_n-CH₃ (n = 0–4) and tetraphenylphosphonium (TPP⁺). In the absence of membrane potential, the amounts of binding were proportional to the probe concentration in the medium when the concentration is dilute. Upon illumination, interior negative membrane potential is generated which induces the uptake of phosphonium cation probe. 2 μM were employed as the initial probe concentration. The real membrane potential was evaluated by means of extrapolation to the state of no binding: The values of for various probes are plotted against the binding coefficient. Here, C_i^app is the apparent intra-vesicular concentration of the probes which is calculated without consideration of bound probes. The ordinate intercept of the plot gives the true concentration ratio, and from this the membrane potential is evaluated. The membrane potential-dependent binding was analysed with a model: the membrane is split into two halves, outer and inner half, and the amounts of bound probes in each region are governed by the concentration in the contiguous solution. We obtained a formula which describes amounts of binding as a function of the membrane potential.     

A photosystem other than PS370 also mediates the negative phototaxis of Halobacterium halobium

Abstract It was found that a photorepellent system other than photosystem 370 (PS370) also controls the behavior of Halobacterium halobium . Both the dependence of background illumination and wavelength where the response showed maximum action distinguished that photosystem from PS370 whose photoreceptor pigment is thought to be an intermediate of s-rhodopsin (sR). A mutant strain that has no detectable activity in PS370 and in photoattractant response was isolated. This mutant strain showed the repellent response due to the new photosystem.     

Receptive field mechanisms of ganglion cells in the cat retina

On the basis of anatomical and physiological results of the vertebrate retina, a method is proposed for analysing the respective fields of ganglion cells in the cat retina. In the model, we assume the following: (a) Ganglion cells receive their input from bipolar and/or amacrine cells. (b) The nonlinearity of ganglion cell responses is due to the activities of transient type amacrine cells. The method has been proved to be effective. According to the results of this investigation, the receptive field properties of X type and Y type ganglion cells are heterogeneous. Thus, it may be considered that their receptive fields consist of center and surround mechanisms. The receptive field properties of X-cells are almost linear and the X-cells seem to receive most of their input from bipolar cells. On the other hand, the ones of Y-cells are highly nonlinear. Consequently, it is conceivable that the Y-cells receive their input mainly from transient type amacrine cells.     

Restriction fragment length polymorphism detected by human salivary amylase cDNA

Summary The plasmid clone which contains human salivary amylase cDNA was used to detect restriction fragment length polymorphisms (RFLPs). After double digestion with Pst 1 and Bam H1, a polymorphism with two alleles was observed. In Japanese, frequencies of these alleles, tentatively called 5.7kb and 6.5kb fragment alleles, are 0.55 and 0.45, respectively.