Effect of butaclamol enantiomers on hypothalamic tyrosine hydroxylase in the rat brain

The authors demonstrate stereospecificity of the action of butaclamol enantiomers on substrate inhibition of hypothalamic tyrosine hydroxylase (TH) and regulation of the tyrosine hydroxylase response by the presynaptic membrane (presynaptic receptors) of rat hypothalamus synaptosomes under membrane activation with dopamine. The effect of (+)-butaclamol on the substrate inhibition of TH was noticeable at a concentration of 10(-8)M, reaching a maximum at 10(-5)M. (-)-Butaclamol administered at the same concentrations did not influence the substrate inhibition of the enzyme. (+)-Butaclamol added to the incubation medium containing hypothalamic synaptosomes concurrently with dopamine (10(-5)M) completely blocked the regulatory action of the latter on TH, with this action mediated via presynaptic receptors. (-)-Butaclamol (10(-5)M) antagonized the action of dopamine under the same conditions. The data obtained indicate high stereo-specificity of butaclamol enantiomers as regards their effect on presynaptic regulation of TH, suggesting that elimination of the substrate inhibition of hypothalamic TH is a stereoselective effect of neuroleptics and can be a prognostically important criterion in the appraisal of compounds with potential neuroleptic activity.     

Semen cryopreservation in golden‐headed lion tamarin,Leontopithecus chrysomelas

Wild animal genetic resource banking (GRB) represents a valuable tool in conservation breeding programs, particularly in cases involving endangered species such as the golden‐headed lion tamarin (Leontopithecus chrysomelas). Thus, we aimed to assess a sperm freezing protocol for golden‐headed lion tamarins using two different exenders: BotuBOV® (BB) and Test Yolk Buffer® (TYB). Ejaculates were collected by penile vibrostimulation from animals housed at São Paulo Zoological Park Foundation, São Paulo, Brazil, and after immediate analysis, two aliquots were diluted in BB and TYB. Postthawing samples were evaluated for total and progressive motility, plasma membrane and acrosome integrities, mitochondrial activity, susceptibility to oxidative stress, and sperm–egg‐binding. No differences between BB and TYB were found for most seminal parameters, except for acrosome integrity and susceptibility to oxidative stress (in both cases BB showed higher values). However, in spite of these differences and regardless of the extender used, postthaw sperm motility and viability with the described protocol were encouraging (on average >50% and >80%, respectively), indicating that sperm cryopreservation may be a short‐term measure for the conservation of golden‐headed lion tamarins.     

Interaction of ethanol with opiate receptors

Addition of ethanol to rat brain homogenate containing opiate receptors inhibits at a concentration of 50 mM the stereospecific binding of 3H-naloxone at 37 degrees C but not at 0 degree C, with the ID50 being 462 mM under these conditions. The temperature-dependent inhibition of the ligand binding suggests that ethanol does not compete with naloxone for specific binding sites of opiate receptors and changes the structure of lipids in biological membranes. Scatchard's analysis has demonstrated that apart from a decrease in the number of highly affinity binding sites of 3H-naloxone, the total amount of the binding sites remains unchanged both in the presence and absence of ethanol and constitutes 453 and 549 fmol/mg protein. It is assumed that ethanol might interconvert highly and low-affinity binding sites. Analysis of the effect of ethanol on 3H-naloxone binding with opiate receptors contained by synaptic membranes obtained from animals with varying predisposition to voluntary alcoholization has shown that ethanol inhibits to a greater degree ligand binding with membranes obtained from rats predisposed to alcoholization. The possibility of the involvement of receptors in the biochemical mechanisms by which the initial alcoholic motivation is effected is under discussion.     

Effect of adrenaline on kidney lysosome function in rats during prolonged soft tissue crushing

The total and unsedimentable activity of acid DNase, RNase, phosphatase and arylsulfatases A and B was examined in the rat kidneys during long-term compression of soft tissues in the presence of high excitability of the sympathoadrenal system. Injection of adrenalin to rats with trauma reduced the total activity of DNase, acid phosphatase and arylsulfatases A and B, particularly at the late periods of soft tissue compression, whereas the total activity of acid RNase slightly increased as compared with control. Compression of soft tissues after adrenalin preinjection was accompanied by a substantial rise of unsedimentable activity of the lysosomal enzymes under study in the kidneys. The activity of the enzymes in cytosol progressively ascended as the time of soft tissue injury increased.     

Late Glacial and Holocene environmental and climatic changes from a limnological transect through Colombia, northern South America

We present a synthesis of the palaeolimnological and palaeoclimatic reconstructions of four sites in Colombia. The record from Lake El Caimito, the westernmost site on the Pacific Coast, dates from the Late Holocene and shows lacustrine sedimentation frequently interrupted by fluvial pulses. These pulses probably reflect periods of increased precipitation related to La Niña phases. East of El Caimito site is the Patía swamp, situated between the Western and Central Andean Cordilleras. The Patía records the dynamics of forest expansion/reduction and changes in water levels. Although the climatic signal of the Patia core is difficult to reconstruct, there is a clear increase in humidity in the Mid-Holocene. The Fúquene Lake record, on the Eastern Andean Cordillera, records dry and cold conditions during the Late Pleistocene, very humid conditions for the early Mid-Holocene, and dry conditions during the mid-Late Holocene. Las Margaritas site, on the eastern savannas, records dry conditions during the Early Holocene and overall humid conditions for the Mid- and Late Holocene. Climate conditions from the Fuquene and Las Margaritas sites seem to reflect the Holocene movements of the Intertropical Convergence Zone (ITCZ); the latter site being more affected by humidity coming from the Amazon region.     

Simultaneous Display of Multiple Foreign Peptides in the FliD Capping and FliC Filament Proteins of the Escherichia coli Flagellum

The bacterial flagellum is composed of more than 20 different proteins. The filament, which constitutes the major extracellular part of the flagellum, is built up of approximately 20,000 FliC molecules that assemble at the growing distal end of the filament. A capping structure composed of five FliD molecules located at the tip of the filament promotes polymerization of FliC. Lack of FliD leads to release of the subunits into the growth medium. We show here that FliD can be successfully used in bacterial surface display. We tested various insertion sites in the capping protein, and the optimal region for display was at the variable region in FliD. Deletion and/or insertion at other sites resulted in decreased formation of flagella. We further developed the technique into a multihybrid display system in which three foreign peptides are simultaneously expressed within the same flagellum, i.e., D repeats of FnBPA from Staphylococcus aureus at the tip and fragments of YadA from Yersinia enterocolitica as well as SlpA from Lactobacillus crispatus along the filament. This technology can have biotechnological applications, e.g., in simultaneous delivery of several effector molecules.     

Characteristics of the conditioned reaction of passive avoidance in rats after destruction of the terminal dopaminergic fields in the amygdaloid complex

Character of conditioned reaction of passive avoidance was analyzed in Wistar line male rats after neurochemical destruction of terminal dopaminergic fields of the amygdalar complex. 6-hydroxydopamine was bilaterally administered to the central nucleus of the amygdalar complex after preliminary treating with desmethylimipramine for selective destruction of dopaminergic terminals. Lowering of dopamine level in the amygdalar complex led to a weakening of reproduction and to prolongation of spontaneous extinction of conditioned reaction. Features of conditioned reaction are highly similar to the effect of latent inhibition connected with attention deficit. It is suggested that activity of terminal fields of the amygdalar complex is one of the mechanisms providing for attention and intensifying selection of information in learning.