A model for the dynamic properties of integrating fibers: Target localization in a three-dimensional space—II. Computer simulation

• 1.1. The stimulation sequence provoked by a luminous point moving in front of a column of ommatidia was simulated for the eye of Squilla mantis.
• 2.2. The output from the ommatidia is transferred to one tangential, integrating fiber as graded potentials. These potentials follow a gaussian-shaped angular sensitivity function for each ommatidium.
• 3.3. The tangential fiber sums the inputs as they arrive and generates a spike if the sum is above threshold at one instant of time and at one point of the fiber.
• 4.4. The histograms of instantaneous frequencies of spike discharge resemble the input-pattern histograms.
• 5.5. The discharge pattern changes with distance and speed of the moving spot as well for the simulations as in electrophysiological recordings, and is adapted to the size of the animal.
• 6.6. The shape of the histograms (i.e. the pattern of spike discharge) is assumed to transmit the information on the position, speed and size of a moving target.

     

Electric organ discharge frequency modulation evoked by water vibration in Gymnotus carapo

• 1.1. The electric organ discharge (EOD) frequency modulations evoked by brief water vibration were analysed in the pulse-type fish Gymnotus carapo.
• 2.2. The response consisted of a transient increase of the EOD frequency at short latency (30 msec). Response profiles were characteristic of the specimen and relatively independent on stimulus intensity.
• 3.3. Conversely, they were dependent on stimulation sequence, showing a rapid decrement along successive stimuli and high temporal discrimination.
• 4.4. The brief latencies indicate a relatively simple neural circuit.
• 5.5. The response may be an electrolocation enhancement strategy for the detection of moving objects based on “sampling” the periphery at a higher frequency.

     

Relationship between ecg,eeg and sps responses during arousal in the goldfish (Carassius auratus)

• 1.1. Goldfish (Carassius auratus) were fitted with ECG electrodes and intra-cranial stainless steel electrodes to monitor cardiac, EEG and SPS responses, during minimal restraint, to presentation of environmental stimuli (light-on, moving shadow, tap).
• 2.2. All three stimuli evoked a bradycardia and increases in the EEG frequency; correlates of arousal responses in fish.
• 3.3. EEG frequency changes were most evident in the fore- and midbrain regions; in the hindbrain smaller responses nevertheless showed discrimination between stimuli.
• 4.4. EEG amplitude changes were more site- and stimulus-specific than frequency changes.
• 5.5. SPSs occurred on stimulus presentations which were negative in polarity in the midbrain and positive in the forebrain and hindbrain, though the latter were smaller and less consistent.
• 6.6. Principal components analyses and regression analyses were used to examine detailed associations between peripheral and central physiological changes.
• 7.7. It was found that increases in the EEG frequency of fore- and midbrain regions were related to cardiac deceleration on early stimulus presentations.
• 8.8. This was also shown for the negative SPS of the midbrain to the presentation of the tap stimulus.
• 9.9. Positive SPSs of the forebrain were related to the bradycardia on later stimulus presentation i.e. during habituation of the arousal response.
• 10.10. The results indicate that in fish, as in other vertebrates, negative SPSs in the midbrain are associated with arousal and implicate the forebrain in the modulation of arousal by its habituation.

     

Adaptation in Helix pomatia neurons

• 1.1. Spike frequency adaptation has been studied on neurons of Helix pomatia subesophageal ganglia and interpreted by means of a behavioural model describing the phenomenon in neurons either silent or autorhythmic at rest.
• 2.2. At low stimulating currents the initial discharge frequency F(0) is linearly related to the current strength G.
• 3.3. In the linearity range F(0)/G each neuron was characterized by means of four model parameters: the proportionality constant between F(0) and G, the decay constant of the frequency, the inhibitory current from a single nerve impulse and the decay time constant of the inhibitory current.
• 4.4. The four parameters varied in different cells with a range of 0.18–4.98 Hz/nA, 1.02–3.85 sec, 0.05–0.95 nA and 1.74–22.33 see, respectively.
• 5.5. Experimental results have been analyzed considering inhibitory current, electrogenie sodium pump and other proposed adaptation parameters.

     

Allozyme variation in the stingless bee Trigona fuscobalteata (hymenoptera,apidae) from Peninsular Malaysia

• 1.1. A population of Trigona fuscobalteata from Peninsular Malaysia was analysed for genetic variation at 9 gene-enzyme systems comprising 13 loci.
• 2.2. Two gene-enzyme systems (phosphoglucomutase and isocitrate dehydrogenase) were polymorphic in the 20 colonies studied.
• 3.3. Isocitrate dehydrogenase was represented by duplicate genes.
• 4.4. The number of loci for several enzyme systems appeared to be different from that reported for the Australian stingless bees.

     

An electrophysiological study of the topographical organization of the multisensory torus semicircularis of the rainbow trout

• 1.1. The recorcling sites of 68 acoustical (A), 86 visual (V) sensitive units and 36 bimodal units, predominantly encountered within the torus semicircularis, have been examined with respect to their response characteristics.
• 2.2. Bimodal units are located more rostrally than A units, but no topographic preference has been found for the V units. The response signs of the three modality types (excitatory, inhibitory for the A modality; On, Off for the V modality) also show no topographic organization.
• 3.3. The spontaneous spike rate of the V type is smaller than that of the A and bimodal type. Many bimodal cells showed spontaneous activity (76%). Non-spontaneous units are more numerous in the rostral torus.
• 4.4. The frequency sensitivity of the A units can be divided into H (high frequency) and B (broadband) units.
• 5.5. B units, which frequently show a more complex excitatory-inhibitory behaviour are located in the middle and caudal part, whereas the H units are mainly found in the rostral part of the torus.
• 6.6. Phase-locking is restricted to spontaneous, monomodal B units.
• 7.7. Clusters of neurons can be found in the torus, which contain either A or V units. In the dorso-ventral direction the A clusters are about half the size of the V clusters.

     

Complement-like protein from the phylogenetically primitive vertebrate,Eptatretus Stouti,is a Humoral Opsonin

• 1.1. Serum from the Pacific hagfish,Eptatretus stouti,contains a complement-like protein (CLP).
• 2.2. CLP from unfractionated hagfish serum and from affinity-purified preparations binds to yeast cell surfaces.
• 3.3. Incubation with CLP enhances the phagocytosis of yeast by hagfish leukocytes.
• 4.4. CLP-mediated opsonization can be inhibited by anti-CLP antibody, EDTA, d(+)mannose and l(+)rhamnose.
• 5.5. Additional opsomic factors are also in hagfish serum.

     

Monoclonal antibodies for radioimmunoscintigraphy of breast cancer

Breast cancer is the leading cause of cancer deaths among females, and it is estimated that each year, one in ten American women will be newly diagnosed as having the disease. It is therefore not surprising, that a great deal of effort has been made to better understand the biology of breast cancer, and that investigators keep up the search for new tools to better characterize, diagnose and treat these tumours. In this regard, the introduction of the hybridoma technique in 1975 by Kohler and Milstein has lead to an extensive work in the characterization of monoclonal and polyclonal antibodies against breast cancers. A large number of antibodies has been raised to different epitopes present in normal and neoplastic breast tissue; but unfortunately we have yet to find a highly sensitive and specific monoclonal antibody for breast cancer that can successfully be used for scintigraphic detection of nodal metastases and for radioimmunotherapy treatment of this disease.As possible radioimmunodiagnostics, antibodies are known which react with the following antigens:

• 1.(1) cytoskeletal proteins
• 2.(2) breast cell products
• 3.(3) steroid receptors
• 4.(4) putative tumor-associated antigens
• 5.(5) oncogene products
• 6.(6) pregnancy-related products
• 7.(7) basement membrane antigens
• 8.(8) degradative enzymes
• 9.(9) cell receptors for extracellular matrix molecules
• 10.(10) multidrug resistance gene product (p-glycoprotein)
• 11.(11) proliferative markers.

     

Characterization of glutathione S-transferases in a solitary bee,Megachile rotundata (Fab.) (hymenoptera: megachilidae) and inhibition by chalcones,flavone, quercetin and tridiphane-diol

• 1.1. The glutathione S-transferases of Megachile rotundata (Fab.) were characterized eletrophoretically and spectrophotometrically.
• 2.2. Differences were found between sexes with respect to number of isozymes and activity with age.
• 3.3. Inhibition patterns of chalcone, seven of its synthetic derivatives, flavone, quercetin, and tridiphanediol differed with respect to sex and substrate.
• 4.4. Comparisons are made with the honey bee, Apis mellifera L.

     

Temperature acclimation in respiratory and cytochrome c oxidase activity in common carp (Cyprinus carpio)

• 1.1. Common carp (Cyprinus carpio) exposed to experimental temperatures of 12, 18, 24, 30 or 36°C for a 4-week period were used to investigate the effect of temperature acclimation on the frequency of opercular movement (FOM), growth and cytochrome c oxidase (CCO) activity in heart, liver and muscle.
• 2.2. An exponential relationship between FOM and temperature after the first week (10₁₀ =1.76) disappeared after the second week.
• 3.3. The initially high FOM at temperatures of 30 or 36°C and the low FOM at 18 or 12°C changed over 4 weeks to approach the FOM of fish at 24°C.
• 4.4. This change in the relationship of FOM to temperature from highly dependent to independent appeared to be thermal compensation.
• 5.5. Heart and liver CCO activities were significantly affected by temperature, with the lowest activity at the approximate optimum temperature for growth, 24°C.
• 6.6. Highest CCO activities for heart and liver occurred at both the highest and lowest temperatures.
• 7.7. Among the three tissues, heart CCO activity was generally the highest and most affected by acclimation temperature.
• 8.8. Muscle tissue had the lowest CCO activity and was unaffected by temperature.
• 9.9. The high CCO activity at a cold acclimation of temperature 12°C was probably due to thermal compensation and the high activity at 36°C may have been a result of thermal stress.

     

Lipoxygenase of Thermoactinomyces vulgaris,purification and characterization of reaction products

• 1.1. A lipoxygenase preparation was obtained from Thermoactinomyces vulgaris and was purified by affinity chromatography on a linoleyl aminoethyl sepharose column.
• 2.2. Two active fractions were obtained.
• 3.3. The fraction obtained by elution with 100 mM borate buffer pH 9.0 was used in the subsequent work.
• 4.4. Th. vulgaris lipoxygenase oxidized linoleic acid into two products: 13-HPOD and 9-HPOD at a ratio of 44 to 56, respectively.
• 5.5. The identification and characterization of the isomers was done by HPLC, I.R. and mass spectrometry.
• 6.6. When arachidonic acid was used as substrate, 15-HPETE and 15-HETE were found to be the main enzymatic products.

     

The pattern and influential factors of aquatic pharyngeal movements of Trionyx sinensis

• 1.1. The pharyngeal movements of Trionyx sinensis during submersion where recorded with physiological instruments.
• 2.2. Anoxia or hypercapnia caused a marked increase in breathing rate of tested turtles during voluntary diving, and in anoxia there was a significant increase in the frequency of aquatic pharyngeal movements while hypercapnia had a slight or no effect on the frequency of these movements.
• 3.3. During voluntary diving when turtles could easily extend their heads out of water to breathe air, the frequency of rhythmic pharyngeal movements was lower; but during forced submersion, the frequency was higher and the movements were continuous.
• 4.4. The frequency increased more rapidly and greatly when turtles were in forced submersion than when they dived freely and could easily surface to breathe in N₂.
• 5.5. The frequency of pharyngeal movements of T. sinensis during diving in an aquarium with water depth of 30 or 45 cm was markedly higher than that at a water depth of 15 cm. Disturbing stimuli also influenced the aquatic rhythmic pharyngeal movements of T. sinensis.

     

An alkaline phosphatase from Thermus sp strain Rt41A

• 1.1. A thermostable orthophosphoric monoester phosphohydrolase (EC 3.1.3.1) from Thermus sp strain Rt41A has been purified 400-fold to give a specific activity of 25 U/mg at 60°C in IM diethanolamine (pH 11.1).
• 2.2. The enzyme has a M_r of 160,000 and is trimeric.
• 3.3. The half-life of the enzyme is 5 min at 85°C.
• 4.4. The enzyme has a wide specificity for a number of phosphate monoesters.
• 5.5. The H_m of the enzyme is pH dependent, so the pH optimum of the enzyme is affected by the substrate concentration.
• 6.6. The enzyme is inhibited 50% by 20 mM Ca²⁺ or Mg²⁺.
• 7.7. The K_i for phosphate, EDTA-di sodium salt and arsenate (in 1 M diethanolamine, pH 11.1) is approx 1.2, 1.6 and 4mM respectively.
• 8.8. Urea (200 mM) is not inhibitory.

     

Isolation of dna and rna from Streptococcus sobrinus OMZ176 using CsTFA gradients

• 1.1. A simple procedure for isolation of high molecular weight genomic DNA, and RNA, from Streptococcus sobrinus OMZ176 is described.
• 2.2. Cell cultures were grown aerobically for 10 hr.
• 3.3. Spheroplast formation and lysis was achieved by mutanolysin/lysozyme-dependent digestion of the cell wall, followed by N-lauroylsarcosinate-mediated lysis.
• 4.4. Nucleic acids were isolated directly from cell-lysates using cesium-trifluoroacetate (CsTFA) densitygradient centrifugation.
• 5.5. Three different centrifugation regimes were tested: self-generated density gradients in a fixed angle rotor; self-generated density-gradients in a swinging-bucket rotor; pre-formed density-gradients in a swinging-bucket rotor.
• 6.6. Genomic DNA isolated by the CsTFA-procedure was found to have higher purity as compared to genomic DNA isolated in a conventional CsCl gradient.
• 7.7. Isolated DNA was shown to be of a quality suitable for applications in molecular biology.

     

Locust vitellogenin receptor: an acidic glycoprotein with N- and O-linked oligosaccharides

• 1.1. The locust vitellogenin (VTG) receptor which is embedded in oocyte plasma membranes is a glycoprotein.
• 2.2. With various lectins oligosaccharide units have been identified, among them neuraminic acid linked to Gal or GalNAc, mannose chains, Gal linked to GalNAc or GlcNAc and fucose linked to GlcNAc.
• 3.3. With specific enzymes it could be shown that mannose and most other oligosaccharides are O-linked while others like fucose are N-linked.
• 4.4. Enzymatic removal of all O-linked carbohydrates resulted in a drop of the molecular mass of the receptor protein from 200,000 to 110,000.
• 5.5. A total of N- and O-linked oligosaccharides of 54% was calculated.
• 6.6. The isoelectric point of the receptor was found to be at pH 3.4 increasing slightly after removal of neuraminic acid.
• 7.7. Removal of neuraminic acids destroyed the binding ability for VTG.

     

Monoclonal antibodies prepared against heparin lyase I and their reactivity toward heparin lyase I,II and III

• 1.1. Six different monoclonal IgG mouse antibodies to heparin lyase I from Flavobacterium heparinum were prepared.
• 2.2. The monoclonal antibodies were used to detect heparin lyases I, II and III by dot-blotting immunoassay and by Western blotting.
• 3.3. Individual antibodies showed different reactivity toward the three heparin lyases.
• 4.4. The reactivity of two of the monoclonal antibodies was destroyed by exposing heparin lyases to sodium dodecyl sulfate.
• 5.5. The antibodies can be used to rapidly distinguish between the three heparin lyases.

     

Light-induced effects of several enzymes of carbohydrate metabolism in Phycomyces blakesleeanus

• 1.1. The photoregulation shown by glyceraldehyde 3-phosphate dehydrogenase and glucose 6-phosphate dehydrogenase appears to be independent of the mad gene product(s) and also independent of carotene biosynthesis regulation.
• 2.2. The photoregulation of malate dehydrogenase appeared to be dependent on the mutation of the mad and car S genes.
• 3.3. Pyruvate kinase and lactate dehydrogenase may be classified as light-independent.
• 4.4. The action of ATP and fructose 1,6-bisphosphate on the enzymes studied was generally independent of light/dark grown conditions.
• 5.5. However, the effect of fructose 1,6-bisphosphate on Phycomyces pyruvate kinase appears to be light-dependent.

     

Changes in high-energy phosphate metabolism in the water scorpion,Ranatra chinensis,under cold water-warm water stress

• 1.1. To evaluate changes in high-energy phosphate metabolism in the water scorpion (Ranatra chinensis) under restraint and cold water-warm water stresses, in vivo [³¹P]NMR spectra were obtained.
• 2.2. Under restraint stress, arginine phosphate (Arg-P) decreased by 10% after 1 hr and remained at that level thereafter, while β-ATP showed negligible changes over 6 hr.
• 3.3. As the water temperature gradually increased or decreased, the relative concentration of Arg-P decreased due to enzyme regulation.
• 4.4. Repeated cold water-warm water stress, which consisted of repeated 15 min exposures to cold water (5°C) followed by 15 min exposures to warm water (30°C) caused distinct decreases in Arg-P and β-ATP concentration. These decreases were dependent on the frequency of exposure.
• 5.5. Phosphomonoesters (PME) increased not only with restraint stress but also with cold water-warm water stress.
• 6.6. The effect of cold water-warm water stress on high-energy phosphate metabolism was greater than that of restraint stress.

     

Characteristics of Crassostrea virginica crystalline style chitin digestion

• 1.1. Fundamental chitin digestion characteristics of Crassostrea virginica crystalline style were investigated.
• 2.2. Optimum temperature and pH were 34°C and 4.8. respectively.
• 3.3. The colloidal regenerated chitin (0.56mol/0.5 ml: GlcNAc equivalents) was saturating under all enzyme levels encountered.
• 4.4. There was no evidence of end product inhibition, even after 100 hr incubation.
• 5.5. Calculated K_m for the chitinase complex was 1.19mM when determined using a 30 min assay, but was only 0.70 mM when determined using a 4.6 hr assay.
• 6.6. Both K_m values are lower than reported for similar assays in other molluscs and for most bacteria.
• 7.7. Effect of substrate preparation on the kinetics are discussed.
• 8.8. Eight peaks of chitinase activity were resolved by DEAE-Fractogel ion exchange chromatography.