Screening of white-rot fungi on (14C)lignin-labelled and (14C)whole-labelled wheat straw

Summary 74 Basidiomycetes have been tested for ligninolytic capability on (¹⁴C)lignin-labelled wheat straw. Fifteen strains were selected and rested more accurately for ligninolytic activity and the capacity to degrade wheat straw. The asymptote, inflexion point and degradation rate were determined using a model approach. The fungi exhibited very different responses with respect to lignin biodegradation: high asymptote for Pleurotus ostreatus (77%), low inflexion points for Sporotrichum pulverulentum Nov. (6.1 days) and Pycnoporus spp. (2.7 to 4.7 days) with high and slow degradation rates, respectively (0.91% and 0.45% of ¹⁴CO₂ release/day). Degradation values for (¹⁴C)whole-labelled wheat straw exhibited less variation. Finally, the strains Pleurotus ostreatus, Dichomitus squalens and Bjerkandera adusta showed the highest selectivity of lignin removal.     

Occurrence of a microcanalicular system within the ossicles and dermal tissue of Asterias rubens and Marthasterias glacialis (Echinodermata: Asteroidea)

Summary A microcanalicular network is demonstrated within the ossicle stroma and the dermal tissue of two asteroid species. Microcanaliculi are presumed to be mesodermal structures. They consist of convoluted tubular ducts lined by epithelial cells associated with scattered basiepithelial nervous processes. Such a microcanalicular system has not been reported previously from any echinoderm species. Its discovery in asteroids entails some conceptual changes, especially considering the physiology of the body wall.Research assistants of the National Fund for Scientific Research (NFSR, Belgium)     

Stimulation par la lumière rouge lointain de la synthèse de la δ-aminolévulinate déshydratase des cotylédons de radis

Stimulation of de novo synthesis of δ-aminolevulinate dehydralasc of radishes grown under far-red light .
Density labelling studies of δ-aminolevulinate dehydratase (ALAD) in cotyledons of radish ( Raphanus sativus L. cv. Longue Rave Saumonée) seedlings demonstrate that far-red light stimulates de novo synthesis of ALAD and that the turn-over of this enzyme is very poor. Cycloheximide reduces considerably both the increase of ALAD activity and the incorporation of deuterium in ALAD, which indicates that ALAD synthesis depends upon cytoplasmic ribosomes.     

A chromatin core particle obtained by selective cleavage of histones by clostripain.

Rat liver chromatin core particles digested with clostripain yield a structurally well-defined nucleoprotein particle with an octameric core made up of fragmented histone species (designated H'2A, H'2B, H'3 and H'4, respectively) after selective loss of a sequence segment located in the N-terminal region of each core histone. Sequential Edman degradation and carboxypeptidase digestion unambiguously establish that histones H2A, H2B, H3 and H4 are selectively cleaved at the carboxyl side of Arg 11, Lys 20, Arg 26 and Arg 19 respectively and that the C-terminal sequences remain unaffected. Despite the loss of the highly basic N-terminal regions, including approximately 17% of the total amino acids, the characteristic structural organization of the nucleosome core particle appears to be fully retained in the proteolyzed core particle, as judged by physicochemical and biochemical evidence. Binding of spermidine to native and proteolyzed core particles shows that DNA accessibility differs markedly in both structures. As expected the proteolyzed particle, which has lost all the in vivo acetylation sites, is not enzymatically acetylated, in contrast to the native particle. However, proteolyzed histones act as substrates of the acetyltransferase in the absence of DNA, as a consequence of the occurrence of potential acetylation sites in the core histones thus rendered accessible. The possible role of the histone N-terminal regions on chromatin structure and function is discussed in the light of the present observations with the new core particle obtained by clostripain proteolysis.     

Mesenchymal-epithelial conversions induced by 5-Azacytidine: Appearance of cytokeratin Endo-A messenger RNA

When mouse-teratocarcinoma-derived fibroblasts (1246 cell line) are subjected to treatment with the inhibitor of DNA methylation, 5-Azacytidine (5 AzaC), they transiently express at 55-kilodalton intermediate-filament protein recognized by the epithelial-specific monoclonal antibody, TROMA-1, although they retain a fibroblastic morphology. However, rare clones (e.g., the 1339 cell line) that permanently express the antigen recognized by TROMA-1 can be derived from the 5 AzaC-treated 1246 population, and these clones have an epithelial phenotype. In the present study, we used cloned DNA probes to demonstrate that, in 1246 fibroblasts, 5 AzaC induces the appearance of Endo-A mRNA. High levels of Endo-A mRNA were also detected in the epithelial derivative, cell line 1339. In both cases, the capping site of the Endo-A mRNA was found to be the same as that in epithelial cells which normally express this RNA.     

Buspirone: A potential atypical neuroleptic

Buspirone produces a dose-dependent but short-lived elevation in striatal dopamine (DA) metabolites in the rat. $\text{In}$$\text{vitro}$, buspirone possesses an affinity similar to sulpiride for DA receptors (3H-spiperone). A moderate affinity for α₁ receptors was also observed while buspirone was inactive at α₂, β, muscarinic and serotonin₂ receptors. This pharmacological profile as well as previous behavioral data indicate that buspirone may be a potential “atypical” neuroleptic.     

Age-Related Changes in Aldehyde Dehydrogenase Activity of Rat Brain, Liver, and Heart

Abstract: Aldehyde dehydrogenase (ALDH) activity was measured in brains, livers, and hearts of 23–26-month-old and 3-month-old rats. A significant increase of ALDH activity was found in whole brain of old rats with both acetaldehyde (39%) and propionylaldehyde (15%) used as substrates. In different brain areas of old rats, with acetaldehyde used as substrate, a significant increase of ALDH activity was found in striatum (30–50%) and cerebral cortex (37%). However, no significant difference in ALDH activity was found in livers and hearts of young and old rats. Preliminary experiments showed a significant increase of aldehyde reductase activity (52%) with p -nitrobenzaldehyde used as substrate in whole brain of old rats compared with young rats. The present work indicates that an increase of ALDH activity in brain of old rats may be an adaptive phenomenon.     

A cDNA clone containing the entire coding sequence of a mouse H-2Kd histocompatibility antigen

We have isolated a cDNA clone carrying a 1560 bp long insert which contains the entire coding and 3' untranslated regions of an H-2K(d) mouse histocompatibility antigen. Its sequence and overal features are described. They point to the existence of unique properties of DNA sequences associated with the H-2K(d) antigen.