Spectrophotometric Measurements of Phytochrome in vivo and Their Correlation with Photomorphogenic Responses of Phaseolus

Direct in vivo measurements of phytochrome have been made in Phaseolus vulgaris by 2-filter difference spectrophotometry (Ratiospect). All measurements were made at 730 versus 800 nm and it is assumed that the Δ (ΔOD) is directly proportional to the PFR concentration of phytochrome present. Dose response curves were determined for both physiological and spectrophotometric responses for red induction and far-red photoinactivation. For induction, saturation occurs at 100 mj/cm² and for inactivation at 30 mj/cm². The rate of hook opening and the physiological response measured 20 hours after induction are both shown to be directly proportional to the initial amount of PFR present spectrophotometrically. The sensitivity of the tissue correlates well with the absolute amount of phytochrome present, the inner portion of the hook having the maximum concentration of 0.042 Δ (ΔOD)/g fresh weight. If the total reversible phytochrome concentration is reduced by exposure to red light and allowing PFR to decay out of the system the remaining sensitivity of the tissue is shown to be directly correlated with the amount of PR remaining in the tissue. PFR disappears rapidly in the dark at 25°, and is not detectable after 6 hours. There is no indication that PFR reverts in the system to PR. At 4°, PFR does not disappear measurably up to 1 hour and is nearly totally reversible to PR.     

The ecology of symphyla. Part II. Seasonal soil migrations

The seasonal changes in vertical distribution of Scutigerella immaculata Newport in the soil were studied. In bare soil outdoors there were high surface numbers in spring, low in summer, with a second increase in autumn. The distribution pattern was similar in bare greenhouse soil, except that spring migrations to the surface soil occurred earlier, the summer exodus was more marked, and the autumn increase much reduced. Growing plants attracted Scutigerella immaculata to the surface even under adverse soil conditions but had no influence on Symphylella vulgaris Silvestri. The results are discussed in relation to other work.

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Zusammenfassung Symphyliden dringen sehr tief in den Boden ein. Es wurden die jahreszeitlichen Vertikalwanderungen von zwei Arten durch Entnahme einer Anzahl von Tiefenproben in monatlichen Abständen untersucht. Dies waren Scutigerella immaculata, die phytophag ist, und Symphylella vulgaris, die saprophag lebt. Die Fortpflanzung findet das ganze Jahr über statt, doch traten Maximalpopulationen im Gewächshausboden im Frühjahr und im Freiland im Frühsommer auf. Im Freiland wanderten auf offenen Böden große Zahlen beider Arten im Frühling und Frühsommer an die Bodenoberfläche, kehrten im Hochsommer in geringere Tiefen zurück, und im Herbst entstand ein zweiter kleinerer Gipfel der Oberflächenzahlen.Ein ähnlicher jahreszeitlicher Verlauf zeigte sich in nacktem Gewächshausboden, außer daß die Frühjahrswanderung zur Bodenoberfläche zeitiger stattfand, der Sommerrückzug stärker betont war und im Herbst nur relativ wenige zur Bodenoberfläche zurückkehrten. Proben unter Pflanzen in Gewächshaus- und Feldböden zeigten größere Zahlen von Scutigerella immaculata zu den Zeiten, in denen die Pflanzen die größte Anzahl junger Wurzeln entwickelten. Das trat bei Sympbylella vulgaris nich auf. Es wird geschlossen, daß eine warme, feuchte Bodenoberfläche für hohe Oberflächenzahlen beider Arten am meisten geeignet ist, doch kommt Scutigerella immaculata sogar bei ungünstigen Bedingungen an die Oberfläche, wenn Nahrung vorhanden ist.

     

The Fine Structure of a Multiterminal Innervation of an Insect Muscle

The detailed structure of nerve branches, neuromuscular junctions, and muscle fibers of a multiterminal innervation of cockroach abdominal muscle has been studied with the electron microscope. The muscle fiber is of the banded myofibril type; with paired mitochondria and abundant endoplasmic reticulum. The peripheral nerve branches are multiaxonal with large central axon and several small peripheral tunicated axons. Tracheoblasts closely accompany the nerve branches. The multiple neuromuscular junctions show typical axonal vesicles, muscle aposynaptic granules, and close plasma membrane apposition with no interposition of basement membrane material.     

Fine Structure of Thiobacillus thiooxidans

Mahoney, Robert P. (Skidmore College, Saratoga Springs, N.Y.), and Mercedes R. Edwards. Fine structure of Thiobacillus thiooxidans. J. Bacteriol. 92: 487-495. 1966.-Thin section analysis of the chemosynthetic autotroph Thiobacillus thiooxidans revealed structures comparable to gram-negative heterotrophic bacteria. Although this species is unique in that it oxidizes elemental sulfur for energy, uses carbon dioxide as its sole source of carbon, and can withstand a pH of less than 1, thin sections revealed a profile of the cell envelope (cell wall and plasmalemma) similar to other gram-negative species which have more common physiological traits. The cell wall is composed of five layers with an overall width of approximately 200 A, and the plasmalemma appears as a conventional "unit membrane" with a width of about 85 A. Volutin granules and less-dense bodies of similar shape and size were frequently observed in close association with the nucleoplasm. The nature and function of these bodies are unknown at this time.     

Quantification of concentration changes in neonatal human cerebral oxidized cytochrome oxidase.

The oxygenation of cerebral cytochrome oxidase in vivo was investigated in eight newborn preterm infants. Near-infrared spectroscopy was used to quantify changes in the concentration of oxidized cytochrome oxidase ([CytO2]) observed during alterations in arterial oxygen saturation (SaO2) in the range of 85-99% and of carbon dioxide tension (PaCO2) in the range of 4.3-9.6 kPa. No relation was found between changes in SaO2 and [CytO2]. Alterations in PaCO2 were positively related both to changes in [CytO2] and total cerebral hemoglobin concentration [( Hb]t). The changes in [CytO2] ranged from 0.09 to 0.33 (median 0.21) mumol.l-1.kPa-1. The ratio [CytO2]/[Hb]t ranged from 0.06 to 0.12 (median 0.08). The relation of delta [CytO2] to the change in cerebral blood volume (delta CBV) was calculated: delta [CytO2]/delta CBV ranged from 0.09 to 0.18 (median 0.11) mumol/ml. These results define a fraction of cerebral cytochrome oxidase in the newborn infant that is oxidized after an increase in PaCO2 but demonstrate that a change in SaO2 in the range studied was not sufficient by itself to change [CytO2]. They differ from results of studies in adults; this may reflect significant differences between adult and neonatal brain.     

Teratogenicity of combinations of sodium dichromate, sodium arsenate and copper sulphate in the rat

1. The teratogenicity of sodium dichromate (2 mg Cr/kg), sodium arsenate (5 mg As/kg) and copper sulphate (2 mg Cu/kg) in female Wistar rats was studied following the administration of the test compounds separately and in their various combinations on gestation day 8. 2. The test compounds administered separately and the combination of dichromate plus Cu2+ were non-fetotoxic and either non- or weakly teratogenic, whereas arsenate/Cu2+ was both weakly fetotoxic and teratogenic. 3. Dichromate/arsenate and dichromate/arsenate/Cu2+ caused a marked decrease in mean fetal weight and an increased incidence of fetal resorption and abnormality formation.