Sensory characteristics of the cortical input of the hippocampus, the dentate fascia]

Investigation of sensory reactions of the neurones of the dentate fascia was performed in unanaesthetized rabbits. Spontaneous activity usually consisted of long aperiodic high-frequency bursts with silent periods between them. Multimodal convergence was observed in 76% of records. Responses to sensory stimuli constituted three nearly equal groups: 1 -- tonic inhibitory reactions; 2--phasic (equal to stimulus duration) activatory responses; 3--simple "specific" responses of on-type, sometimes with secondary phasic components. In one microelectrode track, perpendicular to the double lamina of granular cells, all neurones usually responded in the same fashion.     

Effects of medium viscosity on kinetics of the enzymatic reaction catalyzed by bacterial RNase

Effects of medium viscosity on kinetic parameters of poly(U) hydrolysis catalyzed by RNase from Bac. intermedius 7P (binase) were studied in solutions of sucrose (4-50 wt. %) and glycerol (35-62 wt. %) in Tris--sodium acetate buffer (pH 7.5) at 25 degreesC. The rate constant of reaction kcat was practically unchanged over a wide range of viscosities (1-15 cP for sucrose and 2.5-3 cP for glycerol). In glycerol solutions, kcat slightly increased with viscosity increase from 4 to 10 cP. Addition of NaCl to the buffer medium resulted in an inhibitory effect of Na+ on kcat, prevented by 50% sucrose or 60% glycerol. It is concluded that binase-catalyzed poly(U) cleavage occurs through a "tense"-substrate mechanism, similarly to reactions catalyzed by alpha-chymotrypsin, trypsin, and laccase.     

Separation of dissociated thyroid follicular and parfollicular cells: association of serotonin binding protein with parafollicular cells

Parafollicular cells (PC) of the sheep thyroid gland are neural crest derivatives that synthesize and release the biogenic amine serotonin (5-HT) as well as the hormone calcitonin. The thyroid also contains a highly specific serotonin-binding protein (SBP). Separation of dissociated thyroid cells was done to study the cellular localization of SBP and to develop a means of isolating PC for study. Various methods were used to obtain an enriched and purified population of PC. Minced thyroid glands were enzymatically dissociated and the cells were layered on a Ficoll linear density gradient. Fractions obtained from the gradient were examined for cell number, viability, 5-HT concentration, SBP activity, and morphology by electron microscopy. One of the fractions was found to be enriched in PC. High levels of 5-HT and SBP were also found in this fraction, whereas these levels were low where the majority of cells were found. This PC-rich fraction, however, contained numerous follicular cells (FC); therefore, additional approaches to cell separation were used. FC can be stimulated in vitro with thyroid stimulating hormone (TSH) to become intensely phagocytic. When stimulated cells were incubated in the presence of silica microspheres, the FC engulfed the microspheres, which were toxic to them. PC did not become phagocytic and were unharmed by the microspheres. Suspended cells, after incubation with microspheres, were centrifuged on a discontinuous gradient, and a PC-rich fraction was obtained. Silica, however, interfered with analysis of SBP. Another method to take advantage of the phagocytic potential of FC was therefore used. TSH-stimulated cell suspensions were passed through a column of sepharose to which thyroglobulin had been coupled. Stimulated FC apparently adhered to the beads and were retained by the columns. Fractions eluting from the columns were greatly enriched with PC. These fractions contained high levels of 5-HT and SBP, and considerably reduced FC contamination was found by quantitative electron microscopy. It is concluded that SBP is localized to PC in the sheep thyroid. The idea that these cells resemble serotonergic neurons in their mechanisms of 5-HT storage is supported.     

Granule-bound starch synthase: structure, function, and phylogenetic utility

Interest in the use of low-copy nuclear genes for phylogenetic analyses of plants has grown rapidly, because highly repetitive genes such as those commonly used are limited in number. Furthermore, because low- copy genes are subject to different evolutionary processes than are plastid genes or highly repetitive nuclear markers, they provide a valuable source of independent phylogenetic evidence. The gene for granule-bound starch synthase (GBSSI or waxy) exists in a single copy in nearly all plants examined so far. Our study of GBSSI had three parts: (1) Amino acid sequences were compared across a broad taxonomic range, including grasses, four dicotyledons, and the microbial homologs of GBSSI. Inferred structural information was used to aid in the alignment of these very divergent sequences. The informed alignments highlight amino acids that are conserved across all sequences, and demonstrate that structural motifs can be highly conserved in spite of marked divergence in amino acid sequence. (2) Maximum-likelihood (ML) analyses were used to examine exon sequence evolution throughout grasses. Differences in probabilities among substitution types and marked among-site rate variation contributed to the observed pattern of variation. Of the parameters examined in our set of likelihood models, the inclusion of among-site rate variation following a gamma distribution caused the greatest improvement in likelihood score. (3) We performed cladistic parsimony analyses of GBSSI sequences throughout grasses, within tribes, and within genera to examine the phylogenetic utility of the gene. Introns provide useful information among very closely related species, but quickly become difficult to align among more divergent taxa. Exons are variable enough to provide extensive resolution within the family, but with low bootstrap support. The combined results of amino acid sequence comparisons, maximum-likelihood analyses, and phylogenetic studies underscore factors that might affect phylogenetic reconstruction. In this case, accommodation of the variable rate of evolution among sites might be the first step in maximizing the phylogenetic utility of GBSSI.      

Morphological characteristics of boreal radiolarians from the Triassic and Late Cretaceous: Comparative analysis

When comparing boreal radiolarian assemblages of the Triassic and Late Cretaceous, significant differences in their morphotypic composition are recognized. In particular, Triassic assemblages are dominated by spherical morphotypes, including pylomate forms of the genus Glomeropyle, while Late Cretaceous assemblages are dominated by prunoid morphotypes without polar spines (genera Prunobrachium and Amphibrachium). It is concluded that, in the course of evolution, high-latitude radiolarian assemblages considerably changed both taxonomically and morphologically. Therefore, it is impossible to determine the uniform morphological and taxonomic characters describing boreal assemblages of the entire Mesozoic. Features of boreal radiolarian assemblages are unique to each geological epoch.     

Palatability and feeding preferences of Uresiphita maorialis (Lepidoptera: Crambidae) for three Sophora species

In a three-hour bioassay, we tested the palatability and feeding preferences of Uresiphita maorialis (kōwhai moth) for Sophora tetraptera, Sophora microphylla and Sophora prostrata. Palatability tests showed no differences among the Sophora species. Feeding preferences, on the other hand, showed that S. tetraptera and S. microphylla leaves are preferred over S. prostrata leaves. Our results support our field observations in Wellington city parks and gardens showing that S. tetraptera and S. microphylla plants frequently have higher densities of larvae than S. prostrata.     

Neuronal septal activity during hippocampal seizure discharges generation in acute model of epilepsy

The activity of the neurones of the medial septal region (MS) and the hippocampal EEG in control and during the appearance of seizure discharges provoked by electrical stimulation of the perforant path were investigated in the awake rabbit. During afterdischarge generation in the hippocampus the dense neuronal bursts separated by periods of inhibition were recorded in the MS. In one group of neurons the bursts of spikes coincided with the discharges in the hippocampus, in other group-occured during inhibitory periods. When the afterdischarge stopped, in the septal neurons with theta activity the disruption of theta pattern was recorded, which have been correlated with the occurrence of low amplitude high frequency (20-25 Hz) waves in the hippocampal EEG. As a rule, the neuronal activivity of the MS recovered much quickly than EEG of the hippocampus; in some cases the increasing of the theta regularity was observed. The definite accordance of the electrical activity of the hippocampus and MS during seizure discharges suggests that the septohippocampal system operate as integral nervous circuit in these conditions. Diverse in the temporal interrelations between the discharges of MS neurones and ictal discharges in the hippocampus in the different cells possible indicate that various groups of the septal nervous elements have different participation in the seizure development. Appearance of the high frequency bursts in the MS is a possible "precursor" of the seizure onsets.     

Plasminogen activator and collagenase production by cultured capillary endothelial cells

Cultured bovine capillary endothelial (BCE) cells produce low levels of collagenolytic activity and significant amounts of the serine protease plasminogen activator (PA). When grown in the presence of nanomolar quantities of the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), BCE cells produced 5-15 times more collagenolytic activity and 2-10 times more PA than untreated cells. The enhanced production of these enzymes was dependent on the dose of TPA used, with maximal response at 10(-7) to 10(-8) M. Phorbol didecanoate (PDD), an analog of TPA which is an active tumor promoter, also increased protease production. 4-O-methyl-TPA and 4α-PDD, two analogs of TPA which are inactive as tumor promoters, had no effect on protease production. Increased PA and collagenase activities were detected within 7.5 and 19 h, respectively, after the addition of TPA. The TPA-stimulated BCE cells synthesized a urokinase-type PA and a typical vertebrate collagenase. BCE cells were compared with bovine aortic endothelial (BAE) cells and bovine embryonic skin (BES) fibroblasts with respect to their production of protease in response to TPA. Under normal growth conditions, low levels of collagenolyic activity were detected in the culture fluids from BCE, BAE, and BES cells. BCE cells produced 5-13 times the basal levels of collagenolytic activity in response to TPA, whereas BAE cells and BES fibroblasts showed a minimal response to TPA. Both BCE and BAE cells exhibited relatively high basal levels of PA, the production of which was stimulated approximately threefold by the addition of TPA. The observation that BCE cells and not BAE cells produced high levels of both PA and collagenase activities in response to TPA demonstrates a significant difference between these two types of endothelial cells and suggests that the enhanced detectable activities are a property unique to bovine capillary and microvessel and endothelial cells.     

A new role for PGRP-S (Tag7) in immune defense: lymphocyte migration is induced by a chemoattractant complex of Tag7 with Mts1

PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7–Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target. Cells of either innate immunity (neutrophils and monocytes) or acquired immunity (CD4⁺ and CD8⁺ lymphocytes) can produce this complex, which confirms the close connection between components of the 2 branches of immune response.     

The use of DNA fingerprinting to estimate annual survival rates in the Saker Falcon(Falco cherrug)

Summary DNA fingerprinting of nestlings ofFalco cherrug was used to determine indirectly the survival of the corresponding adult parent birds, which are difficult to catch in sufficient numbers. This approach is possible because Saker falcons show a high degree of site and mate tenacity. DNA profiles of nestlings from the same territory but from different years were compared. Three patterns of band-sharing coefficients between broods from the same territory were found: if band-sharing coefficients within and between broods from consecutive years were similar but significantly different from those of unrelated birds, it indicated that all young were full sibs and that neither adult was replaced between years. If band-sharing coefficients between broods at the same site indicated no relatedness across years and were equal to those of unrelated birds, then both breeding partners apparently had changed. If the band-sharing coefficients between broods of the same territory and consecutive years were significantly lower than those of full sibs, but higher than those of unrelated birds, the loss of one adult bird was indicated. The analysis of 32 broods (years 1993 to 1997) provided a minimal estimate for annual adult survival of 82% for a wild population of Saker Falcons in Kazakhstan.

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Abschätzung der jährlichen Überlebensraten des Sakerfalken(Falco cherrug) mittels DNA-Fingerprinting

Zusammenfassung Um die Gefährdung und Populationsdynamik des Sakerfalken (Falco cherrug) beurteilen zu können, benötigen wir genaue Angaben zu Mortalität und Überlebensraten. Während es bei dieser Art relativ einfach ist, Nestlinge zu fangen, ist es nahezu unmöglich, eine ausreichend große Zahl an Altvögeln zu markieren, um durch Wiederfang oder Ringfundmeldungen die jährliche Überlebensrate zu ermitteln. Durch DNA-Fingerprinting von Jungfalken haben wir versucht, die minimale Überlebensrate von Altfalken indirekt zu bestimmen. Dieser Forschungsansatz wird dadurch möglich, daß die Sakerfalken eine hohe Philopatrie aufweisen und jedes Jahr im selben Revier brüten. Wenn man mehrere Jahre lang Blutproben der Jungvögel aus denselben Revieren sammelt, so kann man mittels DNA Fingerprinting indirekt ermitteln, ob die jeweiligen Altvögel identisch waren oder gewechselt haben: Vergleicht man die Band-Sharing-Koeffizienten (BSK) von Jungvögeln von zwei oder mehr Jahren aus demselben Revier, so ergeben sich drei Muster: Wenn die BSK-Werte innerhalb der Bruten und zwischen den Bruten identisch aber signifikant verschieden von denen nicht verwandter Vögel sind, so handelt es sich bei den Jungvögeln um Vollgeschwister; demnach sind die Altvögel identisch geblieben, d. h. sie haben von einem Jahr zum nächsten überlebt. Wenn die BSK-Werte zwischen zwei Bruten aus demselben Revier einen Wert annehmen, wie man ihn für unverwandte Tiere ermittelt, so müssen die Eltern gewechselt haben. Liegen die Werte zwischen zwei Bruten signifikant höher als die von nicht verwandten Tieren, aber niedriger als diejenigen von Vollgeschwistern, so ist vermutlich 1 Altvogel gewechselt worden. Die Analyse von 32 Bruten des Sakerfalken aus Kasachstan zeigt, daß die minimale jährliche Adultüberlebensrate bei 82% liegt.