Synthesis of (+)-(R)- and (−)-(S)-5-hydroxy-2-methyl-2-dipropylaminotetralin: Effects on rat hippocampal output of 5-HT, 5-HIAA,and DOPAC as determined by in vivo microdialysis

Racemic 5-methoxy-2-methyl-2-dipropylaminotetralin ( 3 ) has been prepared by a short synthetic route, in which the N,N-dipropyliminium perchlorate of 5-methoxy-2-tetralone ( 4 ) is a key intermediate. Racemic 3 was resolved by crystallization of the corresponding diastereomeric di-p-toluoyltartrates. The enantiomeric excess (%ee) of the phenolic derivatives of (+)-(R)- and (?)-(S)-3 [(+)-(R)- and (?)-(S)-2] was determined by ¹HNMR spectroscopic analysis of the corresponding diastereomeric (?)-(R)-1,1′-binaphthyl-2,2′-diylphosphoric acid salts utilizing ¹³C satellites. X-ray crystallography established the absolute configuration of (?)-(S)-2 · HCl. The enantiomers of 2 were tested for hippocampal output of 5-hydroxytryptamine, 5-hydroxyindoleacetic acid, and dihydroxyphenylacetic acid in rats by use of in vivo microdialysis. The (?)-(S)-enantiomer appeared to affect 5-HT-turnover, whereas (+)-(R)- 2 was inactive. Results obtained provide support for the previously reported hypothesis that the inactivity of (?)-(S)- 2 at central DA receptors is caused by the steric bulk of the C(2)-methyl group. This makes it possible to define a “DA D2 receptor essential volume.” © 1993 Wiley-Liss, Inc.     

Between-population variation in size-dependent reproduction and reproductive allocation in Pinguiculavulgaris (Lentibulariaceae) and its environmental correlates

Several important fitness components in herbaceous perennial plants are commonly related to plant size: flowering probability, reproductive allocation and fecundity. However, evidence for such size-dependence of fitness components is mostly anecdotal and unconnected to other life history traits. Here we report size-dependence for flowering probability and reproductive allocation in 11 populations of Pinguicula vulgaris and relate it to environmental factors. Flowering probability was size-dependent in all populations of P. vulgaris , and indicated the existence of a threshold size for reproduction. Populations at low altitudes and in wet soils showed a significantly higher threshold size for reproduction. Reproductive mass was also size-dependent in all populations. We found considerable between-population differences in the slope and the intercept of the regression between plant size and reproductive mass. This variation was weakly related to the environmental factors measured. In general, relationships between different size-dependent fitness components were low. Instead of showing a covariation of traits, in line with interpretations in terms of life history "tactics", P. vulgaris seemed to independently vary each size-dependent fitness component in each locality. In particular, no significant relationship was found between threshold size for reproduction and the slope of size-dependent reproductive allocation, as predicted by previous authors. Neither we found a significant influence of somatic cost of reproduction on size-dependent fitness components.     

Growth Hormone Treatment of Hypophysectomized Rats Increases Catecholamine-induced Lipolysis and the Number of β-Adrenergic Receptors in Adipocytes: No Differences in the Effects of Growth Hormone on Different Fat Depots

Growth hormone (GH) has a lipolytic effect in adipose tissue but this effect may differ in adipose tissue from various fat depots. This latter possibility was investigated in the present study, in which the effects of GH in vivo on catecholamine-induced lipolysis and the number of β-adrenergic receptors in isolated adipocytes from different fat depots of hypophysectomized rats were investigated. Female and male Sprague-Dawley rats were hypophysectomized or sham-operated at 45 days of age. One week after the operation, hormonal replacement therapy with L-thyroxine and hydrocortisone acetate was given. In addition, groups of rats were treated with GH (1.33 mg/kg per day, given as two daily subcutaneous injections). After 1 week of hormonal treatment, adipocytes were isolated from the parametrial, epididymal and inguinal fat pads, and glycerol release after catecholamine-stimulation and ¹²⁵I-cyanopindolol binding were measured. Hypophysectomy resulted in a marked decrease in the lipolytic response to catecholamines. GH treatment significantly increased catecholamine-induced lipolysis with similar effects in adipocytes from parametrial or epididymal and inguinal fat depots in both female and male rats. There were no differences between norepinephrine compared with isoproterenol-induced responses. ¹²⁵I-cyanopindolol binding was reduced after hypophysectomy and normalized by GH treatment, without differences between parametrial and inguinal adipose tissue regions. We conclude that the lipolytic effects of GH in the rat may partly be mediated by a stimulatory effect on β-adrenergic receptors in adipocytes. In addition, GH exerted similar effect on catecholamine-induced lipolysis and β-adrenergic receptors in adipocytes from parametrial, epididymal and inguinal fat depots.     

Effects of peptide YY and its analogues on chloride ion secretion in fed and fasted rat jejunum

The aim of our study was to determine whether a meal modifies the antisecretory response induced by PYY and the structural requirements to elicit antisecretory effects of analogue PYY(22–36) for potential antidiarrhea therapy. The variations in short-circuit current (Isc) due to the modification of ionic transport across the rat intestine were assessed in vitro, using Ussing chambers. In fasted rats, PYY induced a dose- and time-dependent reduction in Isc, with a sensitivity threshold at 5 × 10⁻¹¹ M (ΔIsc −2 ± 0.5 μA/cm²). The reduction was maximal at 10⁻⁷ M (Isc −23 ± 2 μA/cm²), and the concentration producing half-maximal inhibition was 10⁻⁹ M. At 10⁻⁷ M, reduction of Isc by PYY reached 90% of response to 5 × 10⁻⁵ M bumetanide. The PYY effect was partly reversed by 10⁻⁵ M forskolin (Isc +13.43 ± 2.91 μA/h·cm², p < 0.05) or 10⁻³ M dibutyryl adenosine 3′,5′ cyclic monophosphate (Isc +12 ± 1.69 μA/cm², p < 0.05). Naloxone and tetrodotoxin did not alter the effect of PYY. In addition, PYY and its analogue P915 reduced net chloride ion secretion to 2.85 and 2.29 μEq/cm² (p < 0.05), respectively. The antisecretory effect of PYY was accompanied by dose- and time-dependent desensitization when jejunum was prestimulated by a lower dose of peptide. The antisecretory potencies exhibited by PYY analogues required both a C-terminal fragment (22–36) and an aromatic amino acid residue (Trp or Phe) at position 27. At 10⁻⁷ M the biological activity of PYY was lower in fed than fasted rats (p < 0.001). Our results confirm the antisecretory effect of PYY, but show that the fed period is accompanied by desensitization, similar to the transient desensitization observed in the fasted period with cumulative doses. This suggests that PYY may act as a physiological mediator that reduces intestinal secretion.     

Analysis of amino acid phenylthiohydantoins by high-performance liquid chromatography using gradient elution with ethanol

The use of gradient elution with acetate-buffered ethanol for high-performance liquid chromatographic analysis of phenylthiohydantoins (PTHs) is described. The system separates all commonly encountered PTH derivatives in a total analysis time of 20 min on columns of Spherisorb 5 S ODS (4.6 × 250 mm) packed in the laboratory at moderate expense. Experience with routine operation of the method, particularly with regard to column stability is discussed. Ethanol is considerably cheaper and less toxic than previously described solvent systems.     

Isolation and characterization of DNA repetitions carrying the chromosomal beta-lactamase gene of Escherichia coli K-12.

Summary A ColE1 hybrid plasmid, pNU1, carrying the amp operon coding for chromsomal -lactamase was isolated from the Clarke and Carbon collection and physically mapped. The physical location of ampC within this plasmid was further deduced by in vitro cloning.By reciprocal recombination between pNU1 and chromosome of two unstable -lactamase hyperproducing E. coli K-12 mutants a large plasmid from each mutant was obtained. The respective plasmid was physically mapped and found to contain five and two repeated DNA segments. The repetitions within each plasmid were equal in size, 9,800 bp and 11,900 bp respectively and were organized in tandem. The end points of the repeats were different in the two plasmids but shared a DNA segment carrying the ampC gene. The chromosomal DNA of the -lactamase hyperproducing E. coli mutants were found to contain an amplified DNA segment equal in size to the repeated unit found in the respective plasmid. The data shows that up to 10 identical repeats organized in tandem can be generated by a normal mutation frequency in E. coli.     

Comparison of the protective ability of O and K immunity in mice after immunization withEscherichia coli

The protective abilities ofEscherichia coli O and K immunity against intraperitoneal infection was compared in CBA mice immunized with formalin-killed bacteria. The K13 immunity achieved seemed somewhat more effective than the O6 immunity. This was also reflected in a slightly more rapid clearance of a liveE. coli O6K13 bacteria in K13-immunized animals than in those immunized with O6. However, the protection achieved afterE. coli O6K2 and O2K1 immunization was related more to O immunity than to K immunity.     

Exploration of long and short repetitive sequence relationships in the sea urchin genome.

Long and short repetitive sequences of sea urchin DNA were prepared by reassociation of 2000 nucleotide long fragments to Cot 4 and digestion with the single strand specific nuclease S1. The S1 resistant duplexes were separated into long repetitive and short repetitive fractions on Agarose A50. The extent of shared sequences was studied by reassociating a labeled preparation of short repetitive DNA with an excess of unlabeled long repetitive DNA. Less than 10% of the long repetitive DNA preparation was able to reassociate with the short repetitive DNA. Thus the long and short repetitive elements appear to be principally independent sequence classes in sea urchin DNA. Precisely reassociating repetitive DNA was prepared by four successive steps of reassociation and thermal chromatography on hydroxyapatite. This fraction (3% of the genome) was reassociated by itself or with a great excess of total sea urchin DNA. The thermal stability of the products was identical in both cases (Tm=81 degrees C), indicating that precisely repeated sequences do not have many imprecise copies in sea urchin DNA.     

Mapping of the seed storage protein locus Sec-2 in rye

The segregation of the 75K gamma secalin locus (Sec-2) in combination with five interchanges (reciprocal translocations) and two marker genes was analyzed. The translocations involved chromosome arms 1RL, 1RS, 2RL, 2RS, 4RL, 5RL, 5RS, 6RL and 6RS. The gene loci were both on 2R, but the arm was not known. Although the Sec-2 locus was expected to be on chromosome 2RS, no linkage between Sec-2 and any of the markers was found. This is concluded to be the result of exceptionally frequent recombination between Sec-2 and the break point of one of the translocations, which is the only marker in 2RS.