Taphonomy and diagenesis in diatom assemblages; a Late Pleistocene palaeoecological study from Lake Magadi,Kenya

During these investigations the following species of Anostraca have been found: Chirocephalus diaphanus Prevost 1803, Chirocephalus brevipalpis (Orghidan, 1953), Streptocephalus torvicornis Waga 1892, Branchipus serbicus Marinek & Petrov 1988, Branchipus stagnalis L. (1758) and Branchipus sp. Thus, the total number of species discovered in Yugoslavia is 13.The shape of the frontal shield and the degree of flexure of the distal articles of antennae II in males are of no relevance to taxonomy in the genus Branchipus Schaeffer 1776. However, the apophyses on antennae II in males, shape of antennae II and of the ovisac in females, structure of eggs, and of appendages appear species-specific. We conclude that the differentiation of B. stagnalis into two forms (forma typica and forma visnyai) as well as the separation of B. visnyai Kertész 1956 as a distinct species are unfounded.     

Optimization of culture medium for aroma production byCeratocystis fimbriata

Summary The fungusCeratocystis fimbriata is known to produce among others a banana-like aroma. With a fractional factorial experimental design a culture medium was optimized to produce characteristic volatile metabolites of this aroma. HPLC was used to separate and quantify some of the metabolites. This showed the influence of the composition of the basal culture medium. It is not yet possible to correlate these results with sensorial evaluation.     

Immunoperoxidase localization of albumin and fibrinogen in rat liver fixed by perfusion or immersion: effect of saponin on the intracellular penetration of labeled antibodies

Immunoperoxidase localization of albumin and fibrinogen in rat liver was tested with perfusion or immersion fixation and saponin as a membrane permeabilizing agent. The distribution of albumin- or fibrinogen-containing hepatocytes was examined by light microscopy. Labeled antibody penetration was assessed by electron microscopy on transversely cut cryostat sections. Paraformaldehyde liver fixation by perfusion, followed by incubation of the sections with labeled antibodies together with saponin, demonstrated that albumin and fibrinogen were present in all hepatocytes; mainly in the Golgi apparatus and rarely in the endoplasmic reticulum, the ultrathin sections being labeled throughout their entire thickness. A constant labeling of the endoplasmic reticulum was obtained when saponin was added from the beginning of fixation. In the absence of saponin, albumin was seen in most of the hepatocytes but only at the periphery of the transverse sections, in a few Golgi apparatus, and in some parts of the endoplasmic reticulum; under this condition, fibrinogen was not visualized in the hepatocytes. Paraformaldehyde liver fixation by immersion showed the presence of albumin or fibrinogen in a few hepatocytes only, with irregular labeled antibody penetration. The use of saponin did not improve albumin and fibrinogen localization, except when the liver was poorly fixed. These results show that liver fixation by perfusion gives a homogeneous labeling of all the hepatocytes, whereas fixation by immersion leads to a heterogeneous labeling. Satisfactory results are obtained with saponin, which must be used to improve the penetration of labeled antibodies when the liver is fixed by perfusion. Saponin does not work when immersion is employed, at least under the conditions tested.     

Photosynthesis in Panicum milioides, a Species with Reduced Photorespiration

The capacity for C₄ photosynthesis in Panicum milioides, a specieshaving reduced levels of photorespiration, was investigatedby examining the activity of certain key enzymes of the C₄ pathwayand by pulse-chase experiments with ¹⁴CO₂. The ATP$P₁ dependentactivity of pyruvate,P₁ dikinase in the species was extremelylow (0.14–0.18 µmol mg chlorophyll^–1 min^–1).Low activity of the enzyme was also found in Panicum decipiensand Panicum hians (related species with reduced photorespiration)and in Panicum laxum (a C₃ species). The antibody to pyruvate,P₁dikinase caused about 70% inhibition of the ATP$P₁ dependentactivity of the enzyme in P. milioides. The activity of NAD-malicenzyme and NADP-malic enzyme in ^P. ^milioides was equally low(approximately 0.1–0.2 µmol mg chlorophyll^–1min^–1) and similar to the activity in P. decipiens, P.hians and P. laxum. Photosynthetic pulse-chase experiments underatmospheric conditions showed a typical C₃-like pattern of carbonassimilation including the labelling of glycine and serine asexpected during photorespiration. During the pulse with ¹⁴CO₂only about 1% of the labelled products appeared in malate and2–3% in aspartate. During a chase in atmospheric levelsof CO₂ for up to 6 min there was a slight increase in labellingin the C₄ acids. The amount of label in carbon 4 of aspartatedid not change during the chase, indicating little or no turnoverof the C₄ acid via decarboxylation. The results indicate thatunder atmospheric conditions P. milioides assimilates carbondirectly through the C₃ pathway. Photorespiration as indicatedby the CO₂ compensation point may be repressed in the speciesby a more efficient recycling of photorespired CO₂. (Received June 8, 1982; Accepted July 22, 1982)     

Tryptophan and indole-3-acetic acid accumulation in Acer cell cultures and its relationship with cell autolysis

The accumulation and decline of free indole-3-acetic acid (IAA) and tryptophan has been monitored in cells of Acer pseudoplatanus L. grown in batch suspension cultures. The period of maximal IAA accumulation per cell or per unit dry weight of tissue was found to precede the peak of tryptophan accumulation by several days. A study of cell viability throughout a growth passage indicated the presence of a basal level of non-viable cells of 5–7%, with only minor increases occurring during the first week of the three-week growth passage. The results suggest that IAA biosynthesis is not regulated by substrate availability arising from proteolysis in dead cells.Abbreviation GC-MS Gas chromatography-mass spectrometry - IAA indole-3-acetic acid - 5-MT 5-methyltryptophan - TLC thin-layer chromatography     

Inhibition of C4 photosynthesis by (benzamidooxy)acetic acid

(Benzamidooxy)acetic acid (common name benzadox) which has herbicidal properties was evaluated as a potential inhibitor of photosynthesis in C₄ plants. Among enzymes of the C₄ pathway, it was a relatively strong inhibitor of alanine aminotransferase in in vitro experiments at concentrations of 5mM. In benzadox treated leaves of Panicum miliaceum, a NAD-malic enzyme type C₄ species, there was strong inhibition of both alanine and aspartate aminotransferase and of photosynthetic O₂ evolution within one hour. Consistent with the inhibition of these enzymes of the C₄ cycle, the pool sizes of metabolites of the cycle was altered: the aspartate level was increased two fold, while the levels of other metabolites such as pyruvate, alanine, oxalacetate and malate were decreased. Kinetic studies with partially purified alanine aminotransferase showed that benzadox is a competitive inhibitor with respect to alanine and a noncompetitive inhibitor with respect to 2-oxoglutarate. Comparisons between the structures and inhibitory actions of benzadox and (aminooxy)acetic acid, the latter a potent inhibitor of alanine and aspartate aminotransferases, suggest that in vivo, benzadox may exert its effect through metabolism to (aminooxy)acetic acid.Abbreviations benzadox (benzamidooxy)acetic acid - DTE dithioerythritol This research was supported in part by gift funds from Monsanto Agricultural Products Company. St. Louis, Missouri, and by NSF Grant PCM-8107953.     

Continuous Determination by a Chemiluminescent Method of Acetylcholine Release and Compartmentation in Torpedo Electric Organ Synaptosomes

Abstract: The detection of acetylcholine (ACh) with a chemiluminescent procedure enables one to follow continuously the release of transmitter from stimulated synaptosomes and to study the compartmentation of ACh in resting and active nerve terminals. A compartment of ACh liberated almost entirely by a single freezing and thawing could be directly measured and compared with a compartment of ACh resistant to several cycles of freezing and thawing but liberated by a detergent (60–70% of the total). It is the compartment liberated by freezing and thawing that is reduced when synaptosomes are stimulated. Up to half the total synaptosomal ACh content is readily releasable provided the calcium entry is maintained, or if a strong releasing agent such as the venom of Glycera convoluta is used. In addition, it is shown that synaptosomes contain only negligible amounts of choline, and that the proportion of the two ACh compartments is not influenced by changing extracellular calcium just before their determination.     

Immunological and Chemical Identification of Intracellular Forms of Adenovirus Type 2 Terminal Protein

Highly purified adenovirus type 2 terminal protein (TP) with an apparent M_r of 55,000 (55K) was prepared in quantities of 10 to 30 μg from guanidine hydrochloride- or sodium dodecyl sulfate-disrupted virions (60 to 120 mg). Guinea pigs were immunized with 14 to 20 injections of TP in amounts of 1 to 2 μg. Antiserum to TP was used to study the intracellular polypeptides related to adenovirus type 2 TP. By immunoprecipitation with anti-TP serum, we identified 80K and 76K polypeptides in the nucleoplasmic and cytoplasmic S100 fractions of [³⁵S]methionine-labeled cells early and late after infection with Ad2. By immunoautoradiographic analysis which eliminates coprecipitation of unrelated proteins, we identified an 80K polypeptide (probably an 80K-76K doublet) in unlabeled, late infected cells, using anti-TP serum and ¹²⁵I-labeled staphylococcal protein A. About two- to threefold-higher levels of the 80K and 76K polypeptides were present in the nucleoplasm than in the S100 fraction, and two- to threefold-higher levels were found in late infected cells than in early infected cells (cycloheximide enhanced, arabinofuranosylcytosine treated). We did not detect the 80K or 76K polypeptide in uninfected cells, indicating that these polypeptides are virus coded. Tryptic peptide map analysis showed that the 80K and 76K polypeptides are very closely related and that they share peptides with the DNA-bound 55K TP. Our data provide the first direct demonstration of intracellular 80K and 76K forms of TP. The intracellular 80K and 76K polypeptides are closely related or identical to the 80K polypeptide that Challberg and co-workers (Proc. Natl. Acad. Sci. U.S.A. 77:5105-5109, 1980) detected at the termini of adenovirus DNA synthesized in vitro and to the 87K polypeptide that Stillman and co-workers (Cell 23:497-508, 1981) translated in vitro. We did not detect the 55K TP in early or late infected cells, consistent with the proposal by Challberg and co-workers that the 80K polypeptide is a precursor to the virion-bound TP and that the conversion of the 80K polypeptide to the 55K TP occurs during virus maturation. The 80K and 76K polypeptides have many more methionine-containing tryptic peptides than does the 55K TP, and most of the tryptic peptides unique to the 80K and 76K polypeptides are very hydrophobic. Thus, the conversion of the 80K and 76K polypeptides to the 55K TP may involve the removal of a specific hydrophobic protein region.     

Enhancement by Gangliosides of the Binding of Serotonin to Serotonin Binding Protein

Abstract: Several gangliosides, especially G_D3 (disialosyllactosyl ceramide) in the presence of another lipid (lecithin) were found to enhance the binding of serotonin to serotonin binding protein (SBP) severalfold. In our conditions, this enhancement was linear to a concentration of 2.7 × 10⁻⁶I G_D3 and a three- to fivefold increase in binding capacity of SBP was obtained with 8.8 × 10⁻⁶ M. The addition of this ganglioside led to an increase of serotonin binding sites, but not to an increase in the affinity of SBP to serotonin. Optimal binding capacity was found with a ratio of lecithin to ganglioside of 6: 1 (w/w). No binding was found in the absence of either SBP or Fe²⁺ (binding of serotonin to SBP is dependent on Fe²⁺). Other glycosphingolipids (sulfatide, G_D1a, G_D1b, G_M1) showed lesser effects at low concentration, whereas asialo-G_M1, cytolipin H, galactocerebroside and G_M3 had insignificant effects. Since earlier studies suggested a storage role for serotonin binding protein, the interaction of gangliosides with this protein may regulate the concentration of the biogenic amine in the synapse.     

Miospores in middle-upper Frasnian to Famennian sediments partly dated by conodonts (Boulonnais,France)

The middle-upper part of the Formation de Beaulieu exposed in the new railroad trench at Caffiers-Ferques and the Formation de Ferques exposed in the Tartinskal quarries contain well-preserved miospore assemblages. They are here restudied in comparison with new conodont data ranging from the middle asymmeyricus to the Ancyrognathus triangularis Zone. The conodonts allow precise correlations with the type Frasnian area as well as with the Russian Platform and Timan-Pechora provinces. The miospore assemblages of the Formation d'Hydrequent are also considered and their age discussed in term of the Frasnian/Famennian boundary.In the systematic part, two new combinations are proposed: Ancyrospora lysii (Taugourdeau-Lantz, 1960) nov. comb., and Pustulatisporites rugulatus (Taugourdeau-Lantz, 1967) nov. comb.