Nippostrongylus brasiliensis: Female incubation,release of pheromone,fractionation of incubates

The release of pheromone by female Nippostrongylus brasiliensis as a crude incubate was linear for the first 2 hr, but declined after this period. Pheromone release in solution increased with temperature elevations until a 37 C incubation temperature was reached. Higher temperatures of incubation apparently caused diminished pheromone release. Gel filtration of female pheromone that was prepared as a crude incubate revealed biologically active elutions at K_av, 0.64 and 1.0. The timed release of female pheromone activity at these two elution regions coincided additively with the production of activity as a crude incubate. Each individual Chromatographic fraction from females accounted for about 50% of the pheromone activity of the crude, nonfractionated incubate, based on the male's bioassay response. Recombination of the K_av 0.64 and 1.0 elutions enabled recovery of pheromone activity that was similar to crude incubate. The gel filtration elution of 260-nm absorbance from male- or female-produced incubate was qualitatively similar, but a range of quantitative differences were evident. The fractionation of incubate from several female densities revealed only quantitative differences.     

Osmolarity of osmium tetroxide and glutaraldehyde fixatives

Synopsis The evidence available to date for the importance of fixative osmolarity is considered together with some observations on the volume changes of crab axons after fixation by osmium tetroxide and glutaraldehyde. The results obtained are compared with those obtained from crab axons and from amphioxus skin cells which had been processed and examined with the electron microscope after initial fixation in fixatives of different composition. It is concluded that the osmolarity of the fixative vehicle is of considerable importance when the fixing agent is glutaraldehyde but is of less importance when the fixing agent is osmium tetroxide or a mixture of the two agents.Preliminary observations upon crab axons fixed with glutaraldehyde in a vehicle approximating to the internal composition of the cells suggest that this approach to the design of fixative vehicles may be useful.     

Electrophysiological indices of degree of functional integration between gratified neural tissue and the host brain

Neocortex from 17–18-day rat embryos was transplanted into the barrel-field cortical area in adult rats. Neuronal response to deflecting the vibrissae was tested in the graft 3–8 months afterwards. Nine out of 11 grafts showed a response to sensory stimulation. Irregular and asynchronous discharges predominated in neuronal background firing activity in these grafts. Generalized slow-wave activity had much in common with that occurring on the diametrically opposite site on the intact host brain cortex. Hypersynchronous volleys were detected in neurons of unresponsive grafts. A predominance of waves within the delta range while other rhythms remained only faint, together with epileptiform sharp spikes were seen in generalized activity. Histological treatment of responding grafts revealed close fusion between tissue and host brain. Non-responsive grafts were surronded by a thick glial scar.Institute of Biophysics, Academy of Sciences of the USSR, Pushchino-on-Oka. Institute of Neurobiology and Brain Research, E. German Academy of Sciences, Magdeburg, E. Germany. Translated from Neirofiziologiya, Vol. 19, No. 4, pp. 498–504, July–August, 1987.     

Submerged cultivation of edible white-rot fungi on tree bark

Summary Three white-rot fungi,Phanerochaete chrysosporium, Polyporus anceps, andPleurotus sapidus, were grown in shake flasks on maple and cedar bark. The barks for growth were extracted with 1% NaOH and microbial growth was estimated by biuret protein. The maximum yields were 136 and 116 mg protein/gm of bark forPhanerochaete chrysosporium andPolyporus anceps and occurred at 4 days. These two fungi were active cellulase producers and were shown to exhibit an extensive linear phase during batch growth.Pleurotus sapidus produced laccase but negligible growth. A non-linear relationship between bark concentration and protein yield was found.     

Bean tumbling as a control measure for the common bean weevil, Acanthoscelides obtectus

Recognizing that it takes Acanthoscelides obtectus (Say)(Coleoptera: Bruchidae) larvae over 24 h to bore into a dry red kidney bean (Phaseolus vulgaris L.) and that boring can occur only at particular sites where a bean abuts some other surface, we postulated that this pest might be controlled by periodic tumbling of beans so as to place initiated holes out of register with requisite touching surfaces. Larvae repeatedly forced to initiate holes might die of exhaustion, if not smashed by tumbling beans. Indeed, brief daily tumbling of beans held in half-filled jars, buckets, and gunny sacks reduced A. obtectus populations by 97% relative to stationary controls. We recommend that small lots of beans can be protected indefinitely from the bean weevil when stored in <75% filled cylinders rolled ca 1 circumference every morning and evening. This control method should be immediately useful, particularly among subsistence families, since the only external input is knowledge. Also, this control principle might be broadly applicable to other bean and grain pests having strict spatial and temporal requirements for seed penetration.     

Food-associated cues alter forebrain functional connectivity as assessed with immediate early gene and proenkephalin expression

Background  

Cues predictive of food availability are powerful modulators of appetite as well as food-seeking and ingestive behaviors. The neurobiological underpinnings of these conditioned responses are not well understood. Monitoring regional immediate early gene expression is a method used to assess alterations in neuronal metabolism resulting from upstream intracellular and extracellular signaling. Furthermore, assessing the expression of multiple immediate early genes offers a window onto the possible sequelae of exposure to food cues, since the function of each gene differs. We used immediate early gene and proenkephalin expression as a means of assessing food cue-elicited regional activation and alterations in functional connectivity within the forebrain.     

Identification of the Cationic Amino Acid Transporter (System y+) of the Rat Blood-Brain Barrier

Abstract: Cationic amino acids are transported from blood into brain by a saturable carrier at the blood-brain barrier (BBB). The transport properties of this carrier were examined in the rat using an in situ brain perfusion technique. Influx into brain via this system was found to be sodium independent and followed Michaelis-Men-ten kinetics with half-saturation constants (K_m) of 50–100 μM and maximal transport rates of 22–26 nmol/min/g for L-lysine, L-arginine, and L-ornithine. The kinetic properties matched that of System y⁺, the sodium-independent cationic amino acid transporter, the cDNA for which has been cloned from the mouse. To determine if the cloned receptor is expressed at the BBB, we assayed RNA from rat cerebral microvessels and choroid plexus for the presence of the cloned transporter mRNA by RNase protection. The mRNA was present in both cerebral microvessels and choroid plexus and was enriched in microvessels 38-fold as compared with whole brain. The results indicate that System y⁺ is present at the BBB and that its mRNA is more densely expressed at cerebral microvessels than in whole brain.     

Riverscape genetics in brook lamprey: genetic diversity is less influenced by river fragmentation than by gene flow with the anadromous ecotype

Understanding the effect of human-induced landscape fragmentation on gene flow and evolutionary potential of wild populations has become a major concern. Here, we investigated the effect of riverscape fragmentation on patterns of genetic diversity in the freshwater resident European brook lamprey (Lampetra planeri) that has a low ability to pass obstacles to migration. We tested the hypotheses of (i) asymmetric gene flow following water current and (ii) an effect of gene flow with the closely related anadromous river lamprey (L. fluviatilis) ecotype on L. planeri genetic diversity. We genotyped 2472 individuals, including 225 L. fluviatilis, sampled from 81 sites upstream and downstream barriers to migration, in 29 western European rivers. Linear modelling revealed a strong positive relationship between genetic diversity and the distance from the river source, consistent with expected patterns of decreased gene flow into upstream populations. However, the presence of anthropogenic barriers had a moderate effect on spatial genetic structure. Accordingly, we found evidence for downstream-directed gene flow, supporting the hypothesis that barriers do not limit dispersal mediated by water flow. Downstream L. planeri populations in sympatry with L. fluviatilis displayed consistently higher genetic diversity. We conclude that genetic drift and slight downstream gene flow drive the genetic make-up of upstream L. planeri populations whereas gene flow between ecotypes maintains higher levels of genetic diversity in L. planeri populations sympatric with L. fluviatilis. We discuss the implications of these results for the design of conservation strategies of lamprey, and other freshwater organisms with several ecotypes, in fragmented dendritic river networks.Subject terms: Conservation biology, Ecological genetics, Evolutionary genetics, Genetic variation