the frooxidant-induced and spontaneous mitochondrial calcium release: Inhibition by meta-iodo-benzylguanidine (mibg), a substrate for mono (adpribosylation)

The norepinephrine analogue meta-iodo-benzylguanidine (MIBG). a substrate for mono(ADP-ribosylation) and inhibitor of eukaryotic ADP-ribosyltransferases. inhibits the prooxidant-induced and spontaneous calcium release from intact rat liver mitochondria without affecting pyridine nucleotide oxidation and hydrolysis. This finding strongly suggests regulation of calcium release by ADP-ribosylation in mitochondria. and may be relevant for the cellular and pharmacological effects of MIBG     

Chromosomal variation in the southern short-tailed shrew (Blarina carolinensis)

Chromosomal polymorphism was assessed in the southern short-tailed shrew (Blarina carolinensis) using standard metaphase chromosome and G-banding techniques. Twenty-one animals (11 males, 10 females) from the Meeman Biological Station in Shelby Co., Tennessee, were examined for diploid number. Results showed diploid numbers of 35, 36, 37, 38, 39, 40 and 41 and fundamental numbers of 41, 42, 43, 44 and 45. No diploid numbers or fundamental numbers were unique to a specific collecting locality. The first G-banded karyotypes are reported for the species. These results indicate that Robertsonian polymorphisms, inversions, and possibly other events are responsible for chromosomal variation in B. carolinensis.     

Induction of accessory cell function of human alveolar macrophages by inhalation of human natural interleukin-2

 Accessory function allows antigen-presenting cells to produce sufficient secondary signals for optimum T cell proliferation and interleukin-2 (IL-2) production. Alveolar macrophages are inferior accessory cells compared to monocytes (PBM). We report here that the accessory index (AI) of alveolar macrophages and PBM of patients with lung metastases of solid tumors treated with inhalations of human natural IL-2 (hnIL-2) increased following its administration (P<0.005). The accessory index was significantly elevated from baseline values after 2 weeks of inhalation of 300 000 IU hnIL-2/day (8.2±10.2 compared to 1.1±1; P<0.001). The inhalation of 150 000 IU also induced increases in the index (AI = 2.3±1.9), however, without reaching statistical significance. In addition at 300 000 IU IL-2/day a significant increase in the accessory index was observed for PBM (4±2.5; P<0.05). The indices of PBM and alveolar macrophages prior to inhalation showed a significant negative correlation with the age of the patients (r _s =  – 0.5; r _s =  – 0.8, respectively; P<0.03 for all comparisons). Our data demonstrate that the inhalational application of hnIL-2 enhances the accessory function of alveolar macrophages and, to lesser extent, the accessory index of PBM, indicating the occurrence of pharmacological immunostimulation. Received: 16 August 1995 / Accepted: 4 January 1996     

Generation of rhythmic and arrhythmic behaviour of Crassulacean acid metabolism in Kalanchoë daigremontiana under continuous light by varying the irradiance or temperature: Measurements in vivo and model simulations

Leaves of Kalanchoë daigremontiana Hamet et Perr. at a photon flux density (PFD) above 220 mol·m^–2s^–1 (400–700 nm) or at leaf temperatures above 27.0 °C showed a rapid loss of rhythmicity, and a more or less pronounced damping-out of the endogenous circadian rhythm of CO₂ exchange under continuous illumination. This rhythm was reinitiated after reduction of the PFD by 90–120 mol·m^–2·s^–1 or reduction of leaf temperature by 3.5–11.0 °C under otherwise unchanged external conditions. The reduction in the magnitude of the external control parameter of the Crassulacean acid metabolism (CAM) rhythm (i.e. PFD or leaf temperature) set the phase of the new rhythm. The maxima of CO₂ uptake occurred about 5, 28, 51, 75 h after the reduction. Simulations with a CAM model under comparable conditions showed a similar behaviour. The influence of temperature on the endogenous CAM rhythm observed in K. daigremontiana in vivo could be simulated by incorporating into the model temperature-dependent switch modes for passive efflux of malate from the vacuole to the cytoplasm. Thus, the model indicates that tonoplast function plays an important role in regulation of the endogenous CAM rhythm in K. daigremontiana.Abbreviations CAM Crassulacean acid metabolism - PAR photosynthetically active radiation - PFD photon flux density This work was supported by a grant to F.B. and U.L. from Teilprojekt B5 in the Sonderforschungsbereich 199 of the Deutsche Forschungsgemeinschaft (Bonn, Germany) and by a grant to T. E. E. G. from the Sudienstiftung des deutschen Volkes (Bonn, Germany). Erika Ball is thanked for processing of time-course data for the analysis of Fourier spectra.     

Antisense oligonucleotide containing an internal, non-nucleotide-based linker promote site-specific cleavage of RNA.

We have designed and synthesized a series of novel antisense methylphosphonate oligonucleotide (MPO) cleaving agents that promote site-specific cleavage on a complementary RNA target. These MPOs contain a non- nucleotide-based linking moiety near the middle of the sequence in place of one of the nucleotide bases. The region surrounding the unpaired base on the RNA strand (i.e. the one directly opposite the non-nucleotide-linker) is sensitive to hydrolytic cleavage catalyzed by ethylenediamine hydrochloride. Furthermore, the regions of the RNA comprising hydrogen bonded domains are resistant to cleavage compared with single-stranded RNA alone. Several catalytic moieties capable of supporting acid/base hydrolysis were coupled to the non-nucleotide-based linker via simple aqueous coupling chemistries. When tethered to the MPO in this manner these moieties are shown to catalyze site-specific cleavage on the RNA target without any additional catalyst.     

Metabolism of halogenated compounds in the white rot fungus Bjerkandera adusta studied by membrane inlet mass spectrometry and tandem mass spectrometry

Membrane inlet mass spectrometry has been used for the characterization of halogenated organic compounds produced by the fungus Bjerkandera adusta. Using this technique we obtained electron impact-, chemical ionization-, electron capture negative chemical ionization-mass spectra and tandem mass spectra directly from the growth medium. Through this direct analysis of the samples we identified novel bioconversion products and confirmed recently published data on the production of both chlorinated and brominated methoxybenzaldehyde metabolites. Growth profiles of the culture grown on a defined medium showed that the production of secondary metabolites starts after approximately 6 days and reaches maximal concentrations of 25-250 muM after 15-20 days. Although delayed, the production of secondary metabolites paralleled a depletion of glucose from the medium and stopped shortly after all glucose had been consumed. Experiments in which fluoro- and bromo-labeled 4-methoxybenzaldehydes were added to the medium at day 8 showed biotransformation of these compounds into chloro-3-fluoro-4-methoxy-benzaldehyde and chloro-3-bromo-4-methoxybenzaldehyde, respectively. No dichlorinated products were observed, suggesting that halogenation takes place only at the meta position on the 4-methoxybenzaldehydes. These experiments are the first to bring direct evidence of a halogenation mechanism, where the enzymatic attack takes place directly on the 4-methoxybenzaldehyde intermediates. (c) John Wiley & Sons, Inc.     

Lipase-Catalyzed Regioselective Acylation and Deacylation of Glucose Derivatives

In the development of an efficient synthesis of 1-O-decanoyl-2,3,4,6-tetra-O-acetyl-β-D-glucose (β-2) several lipase-based approaches have been explored. Among five immobilized Upases tested, the lipase from Candida antarctica proved particularly efficient for catalyzing selective hydrolysis in the 1-position of 1,2,3,4,6-penta-O-acetyl-β-D-glucose (β-1). Using triethylamine as catalyst, the hydrolysis product 2,3,4,6-tetra-O-acetyl-D-glucose (3) can be esterified with decanoyl chloride to form β-2 selectively, thereby providing an efficient chemo-enzymatic synthesis starting from readily available raw materials. Attempts to produce β-2 from β-1 by lipase-catalyzed interesterification or to esterify 3 with decanoic acid using a lipase as catalyst were unsuccessful. The latter finding was explained by the hemiacetal OH group of glucose being unable to act as nucleophile in the lysis of the lipase acyl-enzyme intermediate. Furthermore, β-2 was found to bee a too bulky substrate to fit into the active site of any of the lipases tested.