Growth kinetics of Rhizopus arrhizus in solid state fermentation of treated cassava

Summary Growth kinetics of Rhizopus arrhizus MUCL 28168 were determined for different treatments of cassava during solid state fermentation. The best case gave a specific growth rate () of 0.24 h^-1, a yield calculated on a basis that oxygen consumption (Y_x/o) was 2.9 g biomass. g^-1 O₂ consumed and the maintenance coefficient (m) was 0.004 g O₂ consumed. g^-1 biomass. h^-1.     

IDENTIFICATION OF CYTOKININS IN SARGASSUM MUTICUM (PHAEOPHYTA) AND PORPHYRA PERFORATA (RHODOPHYTA)1

Combined gas chromatography-mass spectrometry (GCMS) was used to identify and quantify specific cytokinins from Porphyra perforate J. Ag. and Sargassum muticum (Yendo) Fensh. The level of isopentenyladenosine was estimated to be 0.6 μ·kg^?1 fresh weight in Porphyra and 0.9 μ·kg^?1 fresh weight in Sargassum. The level of cis-zeatin riboside was estimated to be 0.2 μ·kg^?1 fresh weight in Sargassum. This is the first definitive identification of a cytokinin from a red alga, and the second report from a brown alga.     

Vigilant Behaviour: Predictability or Randomness? Spectral Analysis of Series of Scan Durations and their Relationship with Inter-scan Intervals

While feeding, many animals frequently look up and visually scan their environment. Using spectral analysis of continuous series of scan durations from a purple sandpiper Calidris maritima and Barbary doves Streptopelia risoria, we show that there are sequential non-random patterns and significant periodicities in all the examined series such that the birds cycled regularly between short and long scans. The cycles are comparable to those for the continuous series of inter-scan intervals of the same behavioural sequences. We suggest a re-examination of the functional costs and benefits of instantaneous randomness versus sequential predictability in alternating between feeding and scanning and a revision of the models of the way animals alternate between these behaviour patterns.     

Dose dependent accretion of docosahexaenoic acid (DHA) in cardiac membranes of rats fed egg yolk powder enriched in DHA.

We tested the hypothesis that enrichment of the diet with docosahexaenoic acid (DHA) enriched egg yolk powder could modify specifically the (n-3) fatty acids content of rat plasma, red blood cells and heart membranes. Dose-dependent effect of DHA was studied in rats supplemented during 4 weeks. Three groups of adult male rats, DHA10, DHA35 and DHA60 (n = 5 each), had their diet supplemented with 10 mg, 35 mg or 60 mg DHA/kg body weight/day, respectively. Fatty acid composition of membranes and plasma lipids were determined. A significant dose-dependent increase in DHA was observed in all three types of samples. Arachidonic acid (AA) levels did not change in heart and red blood cell membranes whereas it increased significantly in plasma with the DHA35 diet. These results contrast with that previously reported for fish oil supplementation where a decrease in AA levels was reported. Hence, DHA enriched egg yolk supplementation leads to a specific accretion of DHA without competition on AA status.     

The use of NMR chemical shifts to analyse the MD trajectories: simulation of bovine pancreatic trypsin inhibitor dynamics in water as a test case for solvent influences.

In this paper the NMR secondary chemical shifts, that are estimated from a set of 3D-structures, are compared with the observed ones to appraise the behaviour of a known x-ray diffraction structure (of the bovine pancreatic trypsin inhibitor protein) when various molecular dynamics are applied. The results of a 200 ps molecular dynamics under various conditions are analysed and different ways to modify the molecular dynamics are considered. With the purpose of avoiding the time-consuming explicit representation of the solvent (water) molecules, an attempt was made to understand the role of the solvent and to develop an implicit representation, which may be refined. A simulation of hydrophobic effects in an aqueous environment is also proposed which seems to provide a better approximation of the observed solution structure of the protein.     

Production of 6-Phenylacetylene Picolinic Acid from Diphenylacetylene by a Toluene-Degrading Acinetobacter Strain

Several strategies for using enzymes to catalyze reactions leading to the synthesis of relatively simple substituted picolinic acids have been described. The goal of the work described here was to synthesize a more complex molecule, 6-phenylacetylene picolinic acid [6-(2-phenylethynyl)pyridine-2-carboxylic acid], for use as a potential endcapping agent for aerospace polymers. We screened 139 toluene-degrading strains that use a variety of catabolic pathways for the ability to catalyze oxidative transformation of diphenylacetylene. Acinetobacter sp. strain F4 catalyzed the overall conversion of diphenylacetylene to a yellow metabolite, which was identified as a putative meta ring fission product (2-hydroxy-8-phenyl-6-oxoocta-2,4-dien-7-ynoic acid [RFP]). The activity could be sustained by addition of toluene at a flow rate determined empirically so that the transformations were sustained in spite of the fact that toluene is a competitive inhibitor of the enzymes. The overall rate of transformation was limited by the instability of RFP. The RFP was chemically converted to 6-phenylacetylene picolinic acid by treatment with ammonium hydroxide. The results show the potential for using the normal growth substrate to provide energy and to maintain induction of the enzymes involved in biotransformation during preliminary stages of biocatalyst development.     

Body Position,Age and Mass Effect of Adiposity on Adipose Tissue Red Cell Flux in Morbid Obesity

Objective: To measure red cell flux of adipose tissue in morbidly obese patients' pannus in the upright and supine position to determine factors which would render the lower pannus susceptible to ischemic necrosis. Design: A cohort study of morbidly obese subjects without ischemic necrosis. Setting: University teaching hospital. Patients: Twenty-three consecutive morbidly obese patients referred for gastroplasty. Measurements: Red cell flux, measured as RMS voltage by a laser Doppler velocimeter. An optical fiber with a tip diameter of 250μ was inserted into the upper and lower pannus and output recorded in the upright and supine positions. Other variables recorded were age, BMI, blood pressure and serum lipids. Results: Adipose tissue red cell flux demonstrates considerable spatial and temporal heterogeneity from subject to subject and in various locations in the pannus. No differences in red cell flux were detected in response to change in position. However, regression analysis demonstrated that the gradient between the upper and lower abdomen in the supine position was increasingly positive with age and in the upright position it was increasingly positive with increasing weight or BMI. Conclusions: These data suggest that red cell flux is heterogeneously distributed in the abdominal pannus and is not greatly influenced by body position. However, with increasing age and adiposity there is a gradient for decreased red cell flux to the lower portion of the pannus. This may be a factor in rendering this part of the pannus prone to ischemic fat necrosis.     

Cleavage of double-stranded DNA by manganese tris(methylpyridiniumyl)porphyrin linked to 3′-spermine oligonucleotides

 Cleavage of double-stranded DNA was performed with cationic manganese porphyrin complexes linked via a spermine tether to the 3′- or 5′-side of triple-helix-forming oligonucleotides (cleaver-TFO conjugates). The targeted sequence was a 15-polypurine sequence present in the env gene of HIV-1 (positions 7301–7315). The presently used TFOs contain only thymine and 5-methylcytosine residues and one adenine at the 3′-end in order to be able to easily introduce a 3′-polyamine linker by reductive amination of the corresponding 3′-apurinic polypyrimidine oligonucleotides. With this method we prepared these TFO-cleaver conjugates in 45% yield with only two equivalents of the Mn-TrisMPyP-COOH precursor. These new metalloporphyrin-TFO conjugates were able to cleave a complementary 45-mer duplex at 10 nM concentration with only ten equivalents of TFO-cleaver. Conjugates without spermine, without 5-methylcytosine, with a random sequence or with the managanese porphyrin-spermine entity on the 5′-end of TFOs were synthesized for comparative studies. Received: 6 December 1995 / Accepted: 5 February 1996