Catecholamine and MHPG plasma levels,platelet MAO activity,and3H-imipramine binding in heroin and cocaine addicts

This work evaluated in a population of heroin and heroin plus cocaine human addicts:

1. Norepinephrine (NE), epinephrine (Epi), and 3-methoxy-4-hydroxyphenylglycol (MHPG) (the principal metabolite of brain NE) plasma levels;
2. Monoamine oxidase (MAO) activity; and
3. ³H-imipramine specific binding to the amine carrier in platelets.

NE plasma levels were significantly lower in the short-term heroin user groups (1–3 and 4–6 yr), a finding not observed in both the long-term heroin user (>6 yr) and heroin plus cocaine user (>6 yr) groups. Epi levels changed in a similar manner, except that a significant increase was noted in heroin plus cocaine abusers. Conversely, dopamine and MHPG plasma levels increased with the duration of heroin use, and even more with cocaine abuse. Platelet MAO activity increased in all groups. Specific³H-imipramine binding sites showed an increase after 3 yr of heroin abuse and in all heroin plus cocaine addicts. In conclusion, short-term use of heroin decreases NE or Epi release, but with prolonged use, a slow adpatation occurs. In contrast, cocaine inhibits the neuronal Epi uptake, even in a situation of long duration of abuse. Probably the amine levels additionally regulate the amine carrier, resulting in changes that show a different pattern from major depression. These drugs of abuse may also influence directly or indirectly related enzymatic systems.     

Nitrogen-fixing cyanobacteria as source of phycobiliprotein pigments. Composition and growth performance of ten filamentous heterocystous strains

Ten strains of filamentous, heterocystous nitrogen-fixing blue-green algae (cyanobacteria) were screened for growth performance and tolerance to temperature, pH, irradiance and salinity, together with their potential as producers of phycobiliprotein pigments. Phycobiliproteins typically accounted for about 50% total cell protein, the prevalent type being C-phycocyanin, followed by alloppycocyanin, with levels of 17 and 11% d.wt, respectively, in some strains of Anabaena and Nostoc. C-phycoerythrin was the major pigment in several Nostoc strains, reaching 10% d.wt. Some strains represent, therefore, excellent sources of one or more phycobiliproteins. All strains tolerated an irradiance of ca 2000 μmol photon m^-2 s^-1. Anabaena sp. ATCC 33047 and Nostoc sp. (Albufera) exhibited the widest optimum range of both temperature (30–45 and 25–40 °C) and pH (6.5–9.5 and 6.0–9.0) for growth, the former also showing significant salt tolerance. In an outdoor open system, productivity of cultures of two phycoerythrin-rich strains of Nostoc was over 20 g (d.wt) m^-2 d^-1 during summer. The growth performance of the allophycocyanin-rich Anabaena sp. ATCC 33047 in outdoor semi-continuous culture has been assessed throughout the year. Productivity values under optimized conditions ranged from 9 (winter) to 24 (summer) g (d.wt) m^-2 d^-1.     

Seasonal fluctuations of the mineral concentration of alder (Alnus glutinosa (L.) Gaertn.) from the field

Summary The seasonal fluctuation of N, P, K, Ca, Mg, Fe, Mn, Mo, and Co, in leaves, roots and nodules of 40–50 year oldAlnus glutinosa trees growing at four different locations along the banks of the Tormes river, in the province of Salamanca, was studied. Also, the evolution of the soil organic matter under the trees sampled was evaluated. The data obtained for the various nutrient elements in the three plant parts are statistically treated at the significance levels of 99–95 per cent, and some remarks as to the nutritional status of the European alder in respect to the nutrients and its contribution to soil nutrient-cycling are provided. A positive correlation was found between N–P, N–K, N–Mg, and N–Mo, in leaves, and between N–P, N–K, N–Fe, N–Mn, and N–Mo in root nodules. In roots only, no significance at any level was obtained between N and any of the elements analyzed.     

Single-cell protein low in nucleic acids by alkaline treatment

Summary The effect of alkaline treatment on nucleic acid content and in vitro dry matter digestibility of C. utilis NRRL Y-660 has been evaluated using sodium and ammonium hydroxides for the treatment and finding the former preferable. Total dry matter and true protein recovery are also reported.     

Anoxic survival of the isolated cerebellum of the turtle Pseudemis scripta elegans

Intact turtle brain provides a useful model for the study of anoxia and potential survival strategies, since this tissue maintains transmembrane ion gradients and ATP levels during prolonged anoxia and recovers functional activity afterwards. Since isolated tissues offer experimental advantages, the present study sought to determine effects of anoxia on the isolated turtle cerebellum and to define relationships between anoxia survival and glucose supply. In normoxia, the extracellular potassium ([K+]o) activity and evoked potentials were maintained with 5 mM glucose, but 20 mM glucose was required to maintain adenosine triphosphate (ATP) levels and prevent significant increases in [K+]o during anoxia. Inhibition of glycolysis by iodoacetic acid (IAA) during anoxia provoked large increases in [K+]o at all glucose levels. These results demonstrate the usefulness of the isolated turtle cerebellum for studies of anoxic survival since this tissue can maintain ATP levels and [K+]o during prolonged anoxia with 20 mM glucose in the artificial cerebrospinal fluid medium. They also suggest the presence of a Pasteur effect at least during the transition to a hypometabolic state.     

Characterizing the Interaction between Root-knot Nematodes and Soil-borne Fungi which are Pathogenic to Passion Fruit (Passiflora Edulis)

For decades there have been anecdotal claims of synergistic interactions between plant-parasitic nematodes and soil-borne fungi causing decline of productivity of passion fruit (Passiflora edulis) orchards. An empirical confirmation of these disease complexes would impact disease management and plant breeding for resistance. To test those claims, we subjected passion fruit plants to single or concomitant parasitism by Meloidogyne javanica or M. incognita and Fusarium nirenbergiae or Neocosmospora sp. under controlled conditions. Non-inoculated plants served as control for the assays. The severity of shoot symptoms and variables related to plant growth, the extent of fungal lesions, and nematode reproduction were assessed to characterize the interactions. The shoot symptoms and effect on plant growth induced by the pathogens varied, but no synergy between the pathogens was observed. Moreover, the volume of tissue lesioned by the fungi was not affected by co-parasitism of the nematodes. Conversely, plant resistance to the nematodes was not affected by co-parasitism of the fungi. The interactions M. incognita-F. nirenbergiae, M. incognita-Neocosmospora sp., M. javanica-F. nirenbergiae, and M. javanica-Neocosmospora sp. were not synergistic as previously claimed, but instead neutral.     

Treatment with cholesterol-loaded methyl-β-cyclodextrin increased the cholesterol in rabbit oocytes,but did not improve developmental competence of cryopreserved oocytes

Membrane cholesterol:phospholipids ratio is an important determinant of cell chilling sensitivity. At low temperatures, major membrane destabilisation occurs when the membrane undergoes a phase transition. To increase membrane fluidity and stability during cooling and thus increase oocyte cryoresistance, cholesterol has been added to the plasma membrane. This study was conducted to determine if cholesterol could be incorporated into rabbit oocytes by incubation with cholesterol-loaded methyl-β-cyclodextrin (CLC) and if added cholesterol could improve the developmental ability of cryopreserved oocytes after parthenogenetic activation or intracytoplasmic sperm injection. Fresh, frozen and vitrified oocytes incubated with CLC containing 20% NBD-labelled cholesterol (NBD-CLC) were evaluated using confocal microscopy. Fluorescence intensity was higher in fresh oocytes than in cryopreserved ones. Pre-treating rabbit oocytes with 1 mg of NBD-CLC/mL did not improve cleavage and developmental rates after cryopreservation. Results showed that treatment with CLC increased the cytoplasmic cholesterol content, but did not improve cleavage rate and developmental competence of cryopreserved oocytes.     

The Crystal Structure and Small-Angle X-Ray Analysis of CsdL/TcdA Reveal a New tRNA Binding Motif in the MoeB/E1 Superfamily

Cyclic N⁶-threonylcarbamoyladenosine (‘cyclic t⁶A’, ct⁶A) is a non-thiolated hypermodification found in transfer RNAs (tRNAs) in bacteria, protists, fungi and plants. In bacteria and yeast cells ct⁶A has been shown to enhance translation fidelity and efficiency of ANN codons by improving the faithful discrimination of aminoacylated tRNAs by the ribosome. To further the understanding of ct⁶A biology we have determined the high-resolution crystal structures of CsdL/TcdA in complex with AMP and ATP, an E1-like activating enzyme from Escherichia coli, which catalyzes the ATP-dependent dehydration of t⁶A to form ct⁶A. CsdL/TcdA is a dimer whose structural integrity and dimer interface depend critically on strongly bound K⁺ and Na⁺ cations. By using biochemical assays and small-angle X-ray scattering we show that CsdL/TcdA can associate with tRNA with a 1:1 stoichiometry and with the proper position and orientation for the cyclization of t⁶A. Furthermore, we show by nuclear magnetic resonance that CsdL/TcdA engages in transient interactions with CsdA and CsdE, which, in the latter case, involve catalytically important residues. These short-lived interactions may underpin the precise channeling of sulfur atoms from cysteine to CsdL/TcdA as previously characterized. In summary, the combination of structural, biophysical and biochemical methods applied to CsdL/TcdA has afforded a more thorough understanding of how the structure of this E1-like enzyme has been fine tuned to accomplish ct⁶A synthesis on tRNAs while providing support for the notion that CsdA and CsdE are able to functionally interact with CsdL/TcdA.