Purification and some properties of a soluble cytochrome (cytochrome c-551) from Erythrobacter species strain OCh 114

A soluble cytochrome, cytochrome c-551 was purified from an aerobic photosynthetic bacterium Erythrobacter species strain OCh 114 (ATCC No. 33942) by ammonium sulfate fractionation, ion-exchange chromatography and gel-filtration. The cytochrome had absorption maxima at 277, 410, and 524–525 nm in the oxidized form, and at 415, 522, and 550.5 nm in the reduced form. At 77 K, the -band of the absorption spectrum of the reduced form split in two at 547 and 549 nm. The millimolar absorption coefficient at 550.5 nm was 26.8 mM^-1 cm^-1 in the reduced form. This cytochrome was an acidic protein with an isoelectric point of 4.9. Its molecular weight was determined to be 15,000 by gel-filtration on Sephadex G-100 and 14,500 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The midpoint potential of this cytochrome was +250 mV at pH 7.0. This cytochrome did not bind CO.     

Sexual dimorphism of motorneurons: Timbal muscle innervation in male periodical cicadas and homologous structures in females

Summary Treatment of cultured goldfish xanthophores by hormone (ACTH) or c-AMP induces not only pigment dispersion, but subsequent outgrowth of processes, and pigment translocation into these processes. These latter effects are shown to proceed as follows: First the edge of the cytoplasmic lamellae takes on a scalloped contour with numerous protrusions. These presumably serve as nucleation centers where short microfilament bundles are assembled, Later, the microfilament bundles elongate (grow), often resulting in an extension of the protrusions to become filopodia while the proximal end of the microfilaments penetrates into the thicker portion of the cellular process which now houses the pigment, i.e., the carotenoid droplets. Carotenoid droplets appear to migrate along the microfilament bundles, or cytoplasmic channels associated with them, into the filopodia. Finally, some of the filopodia become broader, thicker and laden with carotenoid droplets and are then recognized by light microscopy as pigmented cellular processes. The microfilaments have been shown to be actin filaments by their thickness, the size of their subunits, and decoration by heavy meromyosin. Evidence is presented which suggests that the growth of these actin filaments may come about by recruitment from short F-actin strands found in random orientation in adjacent areas.     

A systematic approach to the simulation of short-term processes in the plant-environment complex

Abstract. A conceptual framework is presented for modelling short-term processes in the plant and its environment as an integrated system. Flows of water, water vapour, heat, momentum, CO₂, soluble carbohydrate and phosphorus are all described by equations of the same general type, i.e. in terms of diffusivity-type parameters, capacities and potential gradients. A representative volume of the crop is divided horizontally into layers and vertically between crop and environment for treatment by a finite-difference method. Vertical flow occurs in the atmosphere, soil, stems and larger roots, andilateral flow between leaves and air, and between finer roots and soil. The interception of direct sunlight and the flux densities of downward and upward diffuse radiation within layers are calculated by a step-wise procedure.
The conversions of materials within the plant are treated as functions of appropriate state variables. Schemes for carbon and phosphorus provide for flow to and from the translocation system, and for photosynthesis, respiration and growth.
A model of a fully-established lucerne crop is described and the sensitivity of model performance to changes in a number of parameter values explored. Simulation runs under varying conditions indicate realistic prediction of diurnal trends.     

Gynandromorphs of the pycnogonid Anoplodactylus portus

A large sample of the pycriogonid Anoplodactylus portus , collected from the Pacific side of the Panama Canal Zone, contains a high percentage of gynandromorphs. The literature on aquatic arthropod gynandromorphs is outlined. The nature and variations of the sexual mosaic population are described and discussed. The several morphological differences between normal and mosaic members of the population are illustrated, and the possible origin of these gynandromorphs is discussed.     

Chemical mobility and bioavailabity of sediment-bound heavy metals influenced by salinity

The transfer of metals from contaminated sediments to algal cell walls (Scenedesmus quadricauda) and organisms from various trophic levels (euryhaline osmoconform hydroid Cordylophora caspia and algae Brachiomonas submarina) was studied with a multichamber device. The system consists of a central chamber which contained the mud suspension and six external chambers containing the different biological indicators. The solids in the central and external chambers are separated by 0.45 m-diameter membranes which allow diffusion of the mobilized, dissolved metal compounds. Experiments were performed with dredged sediments at various salinities (0.5, 1.0, 1.5, and 2.0 percent, respectively) and the kinetic of re-adsorption was obtained by taking samples after different time intervals. High enrichment of Cd was found in the living alga Brachiomonas submarina, but on the other side only a weak influence of salinity on re-adsorption could be observed. Model experiments with ionic Cd showed a clear dependency on Cd-sorption on the algae, Cd-concentration in solution, and salinity. These results indicate that the transfer of metals mainly depends on the specific surface properties of the substrates and on the specific chemical form of the dissolved mobilized metal.     

Stir-up effect of wind on a more-or-less stratified shallow lake phytoplankton community,Lake Balaton,Hungary

Microstratification of phytoplankton in the large shallow Lake Balaton (Hungary) was studied during a 24 h period. Dissolved O₂ showed biological stratification; flagellates exhibited a definite circadian rhythm. In the middle of the investigation a heavy storm broke out which was followed by the disappearance of differences between different layers of water. Storm-induced destratification is described by cluster-analysis. Abundances of dominant species changed differently in connection with the storm. Numbers of Nitzschia sp. increased due to stirring up from the sediment surface. Numbers of single-celled or colony-forming species (Cyclotella comta, Crucigenia quadrata, Coelosphaerium kuetzingianum) practically did not change. Numbers of all the three dominant filamentous species (Aphanizomenon fos-aquae f. klebahnii, Lyngbya limnetica, Planctonema lauterbornii) significantly decreased, which might be attributed to an unknown loss process and was followed by a competitive displacement by algae of small cell size.     

Ultracytochemistry of cholera-toxin binding sites in ciliary processes

Summary Cholera toxin reduces the rate of formation of aqueous humor in concentrations (10^–11 M) that do not disturb the morphology of the aqueoushumor forming epithelial cells of the ciliary processes of the rabbit eye. The search for an endogenous mediator of aqueous-humor formation comparable to cholera toxin in its mode of operation prompted us to map the distribution of cell surface receptors for cholera toxin in the ciliary processes of the eyes of rabbits. Cytochemical studies were carried out with the use of conjugates of cholera toxin to fluorescein isothiocyanate (CT-FITC) and to horseradish peroxidase (CT-HRP), and of the B subunit of cholera toxin to horseradish peroxidase (B-HRP). Multiple fluorescent CT-FITC binding sites were observed on the outer nonpigmented epithelial layer near the crests of the processes. Processes incubated with CT-HRP in vitro showed surface staining of 30–40% of the nonpigmented epithelial cells. A prominent reaction product was observed along the basal and lateral plasma membranes of these cells. In vivo studies carried out after arterial infusion of B-HRP showed a reproducible dense reaction product between the apical surfaces of the pigmented epithelium (PE) and of the nonpigmented epithelium (NPE) facing each other. Aggregations of reaction product were observed with the electron microscope in the extracellular space between the apices of PE and NPE. The apical plasma membrane of the endothelium of the blood vessels near the crests of the ciliary processes was stained after either in vivo or in vitro exposure to peroxidase conjugates. These findings indicate that the cell-surface receptors which mediate the action of cholera toxin on aqueous humor formation are very likely localized in the apical plasma membranes of the epithelium of the ciliary processes.Supported in part by USPHS grant # EY-00237, the Connecticut Lions Eye Research Foundation, Inc., and Research to Prevent Blindness, Inc.     

Nitrogen mineralization in acid sulfate soils

Summary Mineralization of soil nitrogen studies with two acid sulfate soils under anaerobic and aerobic incubation at 30°C for 2 weeks showed that the mineral N was released and accumulated entirely as NH ₄ ⁺ in both soils. Nitrification did not occur in either of the soils under conditions that stimulate nitrification. The acid sulfate soils studied release good amounts of mineralizable N, and, because of lack of nitrifying activity, denitrification may not be a serious problem in these soils.     

连栽第1代和第2代杉木近熟林水文过程养分动态比较

利用小集水区径流场技术和定位研究方法,在获得连栽两代杉木近熟林的大气降水、穿透林冠水、地表、地下径流量等水文学数据,并测定其养分含量的基础上,研究了连栽两代杉木近熟林水文过程的营养动态特征。结果表明:降水中养分浓度第2代林比第1代林高20.30%—39.64%,养分的输入量比第1代多38.52%;穿透水中养分浓度,第1代和第2代林分别比大气降水中高4.149—4.895 g/kg和4.271—5.605g/kg,雨水对冠层营养物质的淋溶,第2代比第1代高2.94%—21.37%;地表径流中的养分浓度两代林差异不大,地下径流中的养分浓度第2代林比第1代高48.06%—78.87%,径流输出的养分量第2代林是第1代林的1.58—2.61倍;养分地球化学循环中,第1代林养分地球化学循环速率26.75%—29.95%,第2代林37.24%—47.43%,养分地球化学循环的周期第1代林3.3—3.7a,第2代林2.1—2.7a,养分地球化学循环中第2代林的养分流失率是第1代林的1.30—1.72倍,养分的净积累率只有第1代林的73.57%—87.14%。系统持留与利用由外界输入的养分功能上,第2代林低于第1代林。