Postnatal Changes in the Activity Ratio of Specific and Nonspecific Cholinesterases from Neuronal Perikarya

Abstract: A soluble fraction from rat brain neuronal perikarya was shown to contain both the specific and nonspecific forms of the enzyme acetylcholines-terase (EC's 3.1.1.7. and 3.1.1.8., respectively). The ratio of the enzyme activities varied along the course of brain development: the nonspecific form being predominant from 1 to 15 days of age and the specific one showing the pattern of rising activity from day 15 onward. We suggest a possible relationship between this changing in cholinesterase activities and the establishment of synapses within the rat cerebral cortex.     

Photosynthetic preparation and characterization of 13C-labeled carbohydrates in agmenellum quadruplicatum

The blue-green alga Agmenellum quadruplicatum (strain PR6) has been used to prepare photobiosynthetically ¹³C-labeled d-glucose, 2-O-(α-d-glucopyranosyl)-glyceric acid (glucosylglycerate), 2-hydroxy-1-(hydroxymethyl)ethyl α-d-gluco-pyranoside (glucosylglycerol), and α-d-glueopyranosyl β-d-fructofuranoside (sucrose). When grown to a cell density of 4.4 g.L^-1 (dry weight) under nitrate-nitrogen limiting growth conditions for 120 h, the algal cells contained 38% of the dry-cell weight as(1 → 4)-α-d-glucan (amylose). About 1% of the dry-cell weight was glucosylglycerol, glucosylglycerate, and sucrose. Glutamate was obtained, together with carbohydrates of low molecular weight, when the cells were extracted with chloroform-methanol; d-glucose was recovered from the extracted cells by acid hydrolysis of the starch. The algae were grown by using 20 mol% [¹³C] carbon dioxide for preparation of labeled carbohydrates and for cellular component identification by whole-cell n.m.r. spectroscopy.     

External mass transfer in a biological film reactor

A method for calculating the mass transfer coefficient in a biological film system, under turbulent flow conditions, is presented. It is experimentally found that fluid velocity has a positive effect on the rate of substrate utilization when the system is operated in other than the kinetic regime. A correlation is developed which indicates a dependence of the mass transfer coefficient on the fluid velocity raised to the 0.7 power.     

Alcohol:NAD oxidoreductase in brain of rats from a colony fed dilute ethanol for many generations.

—Alcohol:NAD oxidoreductase (EC 1.1.1.1) was studied in brain cortex, hypothalamus, cerebellum and midbrain of adult and immature rats, and in the whole encephalon of neonatal rats. The rats used in this study were (i) from a colony which has been given 12% (v/v) aqueous ethanol as the only fluid for 54 generations (‘E.F.’ rats); (ii) rats removed from this colony after the forty-eighth generation and thereafter fed water instead of the alcohol solution (‘E.F./H₂O’ rats); and (iii) normal rats. Enzyme activity in the 20,000 g supernatant of tissue homogenates was measured by the method of Raskin and Sokoloff. Activity was found to be highest in neonatal rat brain and to decrease as the age increased. Activity in the hypothalamus of adult E.F. rats was significantly higher than that found in the same region of adult E.F./H₂O rats. Immature rat cerebellum alcohol:NAD oxidoreductase activity was higher both in ‘E.F.’ and ‘E.F./H₂O’ suggesting a possible genetic change be involved in this CNS region. It may be concluded that, with the exception of neonatal rats, ethanol consumption induces an increase in rat CNS alcohol :NAD oxidoreductase activity.     

Social grooming between squirrel monkeys and uakaris in a seminatural environment

Young squirrel monkeys (Saimiri sciureus) were reported grooming an adult female uakari (Cacajao calvus rubicundus) on four different occasions. Furthermore, the uakari was noted grooming two squirrel monkeys in separate instances. These observations took place in a seminatural rainforest (The Monkey Jungle; Goulds, Florida, U.S.A.) where provisions are provided. Some possible hypostheses tendered to account for this unusual behavior included (a) the unaverted interaction of food-seeking and fur-cleaning behavior, and (b) the compatibility of play-curiosity activities by squirrel monkeys with the uakaris' need for social contact.     

The relevance of imidazole tautomerism for the hormonal activity of histidine-containing peptides

Substitution of 5-nitro- -histidine for -histidine is proposed as a useful tool to study the relationships among tautomerism, acid-base properties, and biological activity of peptide hormones. This approach is illustrated by an analog of the tripeptide thyroliberin, [5-nitro- -histidine]²-thyroliberin, which has been prepared by solid-phase peptide synthesis. The acid-base properties of the hormone analog and the position of the imidazole ring tautomeric equilibrium have been investigated by spectroscopic methods. Correlation of these properties with the biological activity of the nitrated tripeptide strongly supports the idea that imidazole ring tautomerism is a key factor for hormonal activity and that the N^τ-H tautomer must be considered the biologically active form of thyroliberin.     

Hydrolysis of polyethyleneterephthalate by p‐nitrobenzylesterase from Bacillus subtilis

From a screening on agar plates with bis(benzoyloxyethyl) terephthalate (3PET), a Bacillus subtilis p‐nitrobenzylesterase (BsEstB) was isolated and demonstrated to hydrolyze polyethyleneterephthalate (PET). PET‐hydrolase active strains produced clearing zones and led to the release of the 3PET hydrolysis products terephthalic acid (TA), benzoic acid (BA), 2‐hydroxyethyl benzoate (HEB), and mono‐(2‐hydroxyethyl) terephthalate (MHET) in 3PET supplemented liquid cultures. The 3PET‐hydrolase was isolated from non‐denaturating polyacrylamide gels using fluorescein diacetate (FDA) and identified as BsEstB by LC‐MS/MS analysis. BsEstB was expressed in Escherichia coli with C‐terminally fused StrepTag II for purification. The tagged enzyme had a molecular mass of 55.2 kDa and a specific activity of 77 U/mg on p‐nitrophenyl acetate and 108 U/mg on p‐nitrophenyl butyrate. BsEstB was most active at 40°C and pH 7.0 and stable for several days at pH 7.0 and 37°C while the half‐life times decreased to 3 days at 40°C and only 6 h at 45°C. From 3PET, BsEstB released TA, MHET, and BA, but neither bis(2‐hydroxyethyl) terephthalate (BHET) nor hydroxyethylbenzoate (HEB). The k_cat values decreased with increasing complexity of the substrate from 6 and 8 (s?1) for p‐nitrophenyl‐acetate (4NPA) and p‐nitrophenyl‐butyrate (4NPB), respectively, to 0.14 (s?1) for bis(2‐hydroxyethyl) terephthalate (BHET). The enzyme hydrolyzed PET films releasing TA and MHET with a concomitant decrease of the water‐contact angle (WCA) from 68.2° ± 1.7° to 62.6° ± 1.1° due to formation of novel hydroxyl and carboxyl groups. These data correlated with a fluorescence emission intensity increase seen for the enzyme treated sample after derivatization with 2‐(bromomethyl)naphthalene. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011     

A comparison of the phenotypic and genetic stability of recombinant Trichoderma spp. generated by protoplast- and Agrobacterium-mediated transformation

Four different Trichoderma strains, T. harzianum CECT 2413, T. asperellum T53, T. atroviride T11 and T. longibrachiatum T52, which represent three of the four sections contained in this genus, were transformed by two different techniques: a protocol based on the isolation of protoplasts and a protocol based on Agrobacterium-mediated transformation. Both methods were set up using hygromycin B or phleomycin resistance as the selection markers. Using these techniques, we obtained phenotypically stable transformants of these four different strains. The highest transformation efficiencies were obtained with the T. longibrachiatum T52 strain: 65-70 transformants/microg DNA when transformed with the plasmid pAN7-1 (hygromycin B resistance) and 280 transformants/107 spores when the Agrobacterium-mediated transformation was performed with the plasmid pUR5750 (hygromycin B resistance). Overall, the genetic analysis of the transformants showed that some of the strains integrated and maintained the transforming DNA in their genome throughout the entire transformation and selection process. In other cases, the integrated DNA was lost.