Cortical Plasticity Induced by Spike-Triggered Microstimulation in Primate Somatosensory Cortex

Electrical stimulation of the nervous system for therapeutic purposes, such as deep brain stimulation in the treatment of Parkinson’s disease, has been used for decades. Recently, increased attention has focused on using microstimulation to restore functions as diverse as somatosensation and memory. However, how microstimulation changes the neural substrate is still not fully understood. Microstimulation may cause cortical changes that could either compete with or complement natural neural processes, and could result in neuroplastic changes rendering the region dysfunctional or even epileptic. As part of our efforts to produce neuroprosthetic devices and to further study the effects of microstimulation on the cortex, we stimulated and recorded from microelectrode arrays in the hand area of the primary somatosensory cortex (area 1) in two awake macaque monkeys. We applied a simple neuroprosthetic microstimulation protocol to a pair of electrodes in the area 1 array, using either random pulses or pulses time-locked to the recorded spiking activity of a reference neuron. This setup was replicated using a computer model of the thalamocortical system, which consisted of 1980 spiking neurons distributed among six cortical layers and two thalamic nuclei. Experimentally, we found that spike-triggered microstimulation induced cortical plasticity, as shown by increased unit-pair mutual information, while random microstimulation did not. In addition, there was an increased response to touch following spike-triggered microstimulation, along with decreased neural variability. The computer model successfully reproduced both qualitative and quantitative aspects of the experimental findings. The physiological findings of this study suggest that even simple microstimulation protocols can be used to increase somatosensory information flow.     

The Influence of pH and Temperature on Cellulolytic and Pectolytic Activity of Cylindrocarpon destructans (Zins.) Scholt.

In studies on the effect of pH and temperature on cellulolytic and pectolytic activity of C. destructans, it was found that the isolates used produced only endoglucanases. The temperature and pH affected the synthesis of these enzymes. Fungi cultured at 26°C produced more of these enzymes than those grown at the two other temperatures. At 10°C, only one isolate produced minute amounts of endoglucanases. None of fungi studied exhibited cellulolytic activity in cultures grown at 20°C. Cellulolytic activity was found only in acidic media (pH 5.0). The fungi studied exhibited higher pectolytic than cellulolytic activity. In the post culture liquids of these organisms, both types of pectolytic enzymes (exo- and endo-PMG) were detected. Different temperature and pH values affected the production of these enzymes differently in various isolates.     

X-ray crystal structure of galabiose, O-alpha-D-galactopyranosyl-(1---4)-D-galactopyranose

O-alpha-D-Galactopyranosyl-(1---4)-D-galactopyranose, C12H22O11, Mr = 342.30, crystallises in the orthorhombic space group P2(1)2(1)2(1), and has alpha = 5.826(1), b = 13.904(3), c = 17.772(4) A, Z = 4, and Dx = 1.579 g.cm-3. Intensity data were collected with a CAD4 diffractometer. The structure was solved by direct methods and refined to R = 0.063 and Rw = 0.084 for 2758 independent reflections. The glycosidic linkage is of the type 1-axial-4-axial with torsion angles phi O-5' (O-5'-C-1'-O-1'-C-4) = 98.1(2) degrees, psi C-3 (C-3-C-4-O-1'-C-1') = -81.9(3) degrees, phi H (H-1'-C-1'-O-1'-C-4) = -18 degrees, and psi H (H-4-C-4-O-1'-C-1') = 35 degrees. The conformation is stabilised by an O-3 . . . O-5' intramolecular hydrogen-bond with length 2.787(3) A and O-3-H . . . O-5' = 162 degrees. The glycosidic linkage causes a folding of the molecule with an angle of 117 degrees between the least-square planes through the pyranosidic rings. The crystal investigated contained 56(1)% of alpha- and 44(1)% of beta-galabiose as well as approximately 70% of the gauche-trans and approximately 30% of the trans-gauche conformers about the exocyclic C-5'-C-6' and C-5-C-6 bonds. The crystal packing is governed by hydrogen bonding that engages all oxygen atoms except the intramolecular acceptor O-5' and the glycosidic O-1' oxygen atoms.     

2-Bromoethyl glycosides in glycoside synthesis: preparation of glycoproteins containing alpha-L-Fuc-(1----2)-D-Gal and beta-D-Gal-(1----4)-D-GlcNAc

The applicability of 2-bromoethyl glycosides in carbohydrate synthesis is demonstrated by the synthesis of glycosides of alpha-L-Fuc-(1----2)-D-Gal and beta-D-Gal-(1----4)-D-GlcNAc. The bromoethyl aglycon was transformed into the methoxycarbonylethylthioethyl spacer, which allowed coupling of the sugars to proteins (BSA and KLH).     

Die Brutzeiten einiger Gänsearten und ihrer Bastarde in identischen Bedingungen

Zusammenfassung An Hand von 229 Brutbeginn-Daten von freilebenden Gänsen, die während der Jahre 1956–1966 in Seewiesen (Obb.) (48°N, 11°11E) brüteten, wurden die mittleren Brutbeginn-Daten von 5 Gänsearten und von Artbastarden bestimmt. Es zeigte sich, daß die untersuchten Arten unter diesen Bedingungen in derselben Reihenfolge brüteten, wie ihre Artgenossen in freier Wildbahn. Die mittleren Brutbeginn-Termine wurden allerdings um so mehr vorverlegt, je später die Art normalerweise brütet (Abb. 1). , die mit artfremden verpaart waren, brüteten zur selben Zeit wie ihre Artgenossen, die mit artgleichen verpaart waren (Abb. 1). GraugansxSchneegans-Bastard-, die mit Schneegantern verpaart waren, begannen meist nach den Graugänsen, aber stets vor den Schneegänsen zu brüten (Abb. 1, 2). Das intermediäre Brüten dieser wird als starkes Argument für die Richtigkeit der Hypothese gewertet, nach welcher die artspezifisch verschiedenen Brutzeiten wenigstens zum Teil genetisch bedingt sind. In der Diskussion wird die Frage kritisch erörtert, wie weit schon allein die Tatsache, daß die verschiedenen Arten über Generationen hinweg in derselben Reihenfolge wie ihre wildlebenden Artgenossen zu brüten beginnen, als Beweis für derartige genetische Unterschiede angesehen werden kann.

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Summary In 229 cases onset of breeding was recorded from free-living geese of 5 species and of some hybrids of these species, kept in Seewiesen/Obb. (48° N, 11° 11E) from 1956 to 1966. It was found that the species under these conditions bred in the same seasonal sequence as did wild birds. The mean breeding times, however, were found to be advanced in relation to the onset of breeding in the wild (Fig. 1). This was especially evident in the case of late-breeding species. paired with of another species came into breeding condition at the same time as paired with of the same species (Fig. 1). GraylegxSnowgoose hybrid paired with Snowgoose in most cases started to breed later than Greyleg geese but always earlier than the mean breeding time for Snowgeese (Fig. 1, 2). This intermediate breeding time is taken as a strong argument for the hypothesis that the species specific differences in breeding times are, at least in part, genetic in origin. The question as to the extent to which the differences in breeding times alone, persisting for generations in the same sequence as those of wild birds, can be attributed to genetic differences between the species, is critically discussed.

     

Volume-sensitive taurine efflux from mammary tissue is not obliged to utilize volume-activated anion channels

Cell-swelling, induced by a hyposmotic shock, activates the release of taurine from lactating rat mammary tissue expiants. The degree of stimulation of taurine efflux was dependent upon the extent of cell-swelling. Volume-sensitive taurine release was attenuated by the anion transport inhibitors NPPB, DIOA, DIDS, niflumate, flufenamate, mefenamate and diiodosalicylate but not by salicylate. Cell-swelling, following a hyposmotic challenge, did not increase the unidirectional efflux of radiolabelled I^– or D-asparate from mammary tissue expiants. The results suggest that although mammary tissue expresses a volume-sensitive amino acid transport system which is inhibited by anion transport blockers the pathway has no identity with volume-activated anion channels.     

An Ecosystem View of the Restoration of the Kissimmee River

Restoration of the Kissimmee River and floodplain ultimately will involve restoring 70 km of river channel and riparian zone and 11,000 ha of wetland over a period of two decades. Restoring ecosystem integrity is a crucial goal of the project, and the evaluation program is designed to assess the success of this endeavor. Major components of the riverine and floodplain ecosystem will be evaluated, guided by conceptual models of their structure and function. These studies will be referenced to historic conditions of the past and to present-day conditions in the channelized system. Enhanced connectivity and interactions between the river and floodplain, the interplay of abiotic and biotic variables, and interactions between trophic levels will restructure the channelized river and the largely drained floodplain that now exist. The key to evaluating the success of this ambitious project will be selecting measurements of the structure and function of the river and floodplain ecosystems that are responsive to this large-scale manipulation. The timing and duration of floodplain inundation, improved dissolved oxygen conditions, germination and establishment of wetland vegetation, and enhancement and expansion of rheophilic benthic invertebrate populations are critical initial elements of restoration. Further expected outcomes are an increase in the primary productivity of the ecosystem, expansion of the fish community into the reopened channels and onto the reflooded floodplain, and improved visitation and use by waterbirds in the restored regions. We highlight predictions of some of these key linkages and primary structural and functional attributes of the restored river and floodplain that should be measured.     

Partial characterization of allatinhibin,a neurohormone of Manduca sexta

During the last larval stage, corpora allata (CA) of Manduca sexta are inactivated by a factor from the brain. Apparently the same factor (allatinhibin, Al) is secreted by day 4 Vth instar brains kept overnight in Grace's medium. Al is rapidly inactivated by heat or acid but withstands exposure to alkali and can be recovered after freezing and lyophilization. Exposure to pronase, chymotrypsin, carboxypeptidases-A and-Y, as well as leucine aminopeptidase eliminated Al activity completely, whereas after exposure to trypsin and protease XVII-S, some residual activity remained. Inactivation by pyroglutamate aminopeptidase is interprefed as being due to prolinase activity of this enzyme. Incubation of CA with gentamicin, an aminoglycoside antibiotic, affects neither their ability to produce JH in vitro nor their viability in implantation assays. However, Al did not inactivate CA in the presence of low concentrations of gentamicin. This effect was used to guard against false positive assay results possibly produced by allatotoxic contamination. Al was purified by chromatography on Sephadex G-25. All activity recovered emerged from the columns in intermediate fractions with an apparent Mr of 1,000–2,000. © 1993 Wiley-Liss, Inc.