Showing papers by "University of Hohenheim published in 1988"

Human skin fibroblasts in vitro differentiate along a terminal cell lineage.

Abstract: Secondary mitotic human skin fibroblast populations in vitro underwent 53 +/- 6 cumulative population doublings (CPD) in 302 +/- 27 days. When the growth capacity of the mitotic fibroblasts is exhausted, and if appropriate methods are applied, the fibroblasts differentiate spontaneously into postmitotic fibroblast populations, which were kept in stationary culture for up to 305 +/- 41 additional days. Mitotic and postmitotic fibroblast populations are heterogeneous populations with reproducible changes in the proportions of mitotic fibroblasts F I, F II, and F III, and postmitotic fibroblasts F IV, F V, F VI, and F VII. This process makes it evident that the fibroblasts differentiate spontaneously along a seven-stage terminal cell lineage F I-F II-F III-F IV-F V-F VI-F VII. Shifts in the frequencies of the mitotic and postmitotic fibroblasts in mass populations are accompanied by alterations in the [35S]methionine polypeptide pattern of the developing mass populations. The [35S]methionine polypeptide patterns of homogeneous subpopulations of F I, F II, F III, F IV, F V, and F VI isolated from heterogeneous mass populations reveal that the six fibroblast morphotypes studied express their cell-type-specific [35S]methionine polypeptide pattern in the heterogeneous mass populations.

Effects of fruit set sequence and defoliation on cell number, cell size and hormone levels of tomato fruits (Lycopersicon esculentum Mill.) within a truss

Abstract: Fruit size within a tomato (Lycopersicon esculentum Mill.) truss depends on both fruit position in the truss and the time of pollination among fruits. In the natural pollination sequence a difference of 5 days in the pollination of proximal and distal flowers results in significant final size differences between proximal and distal fruits. These final size differences were eliminated when all flowers were pollinated simultaneously. At anthesis proximal ovaries have higher cell numbers than distal ovaries but the cell division activity and cell enlargement in both positions was similar in the first 10 days of fruit growth. Simultaneous pollination resulted in lower cell numbers in proximal but higher cell numbers in distal fruits compared to control fruits.

Availability of amino acids supplied intravenously in healthy man as synthetic dipeptides: kinetic evaluation of L-alanyl-L-glutamine and glycyl-L-tyrosine

Abstract: 1. For the first time utilization of intravenously administered L-alanyl-L-glutamine and glycyl-L-tyrosine was investigated by means of their kinetic behaviour after bolus injection in 10 and 11 apparently healthy male subjects (age 26.6 +/- 5.7 years), respectively. 2. The injection of the synthetic dipeptides was not accompanied by any side effects or complaints. 3. The synthetic dipeptides L-alanyl-L-glutamine and glycyl-L-tyrosine were rapidly cleared from plasma. By applying a monoexponential model the elimination half-lives were found to have very similar values (3.8 +/- 0.5 and 3.4 +/- 0.3 min) whether alanine or glycine was occupying the N-terminal position. The estimated volume of distribution was approximately that of the extracellular space. 4. Peptide disappearance was accompanied by a prompt equimolar increase in the concentrations of the constituent amino acids alanine and glutamine as well as glycine and tyrosine. 5. The study provides firm evidence that L-alanyl-L-glutamine and glycyl-L-tyrosine are rapidly (quantitatively) hydrolysed. The results of this study may indicate a safe and efficient parenteral use of the investigated peptides as sources of free glutamine and free tyrosine.

Differentiation of fibroblast stem cells.

Abstract: Summary Primary human skin fibroblasts derived from the abdomen of 45 female donors of the four age groups 1–20, 20–40, 40–60, and 60–80 years were studied in primary explant, in primary low-density mass cultures, and in primary clonal populations in vitro . As a function of the age of the donor, primary mitotic and postmitotic fibroblasts in the three primary cell systems analysed represent heterogeneous populations with reproducible changes in the proportions of the mitotic fibroblasts MF I, MF II, MF III, and postmitotic fibroblasts PMF IV, PMF V, PMF VI, and PMF VII. These findings make it very likely that equivalent cell types exist in the connective tissue of skin in vivo , and that these cells undergo reproducible changes in the proportions of the mitotic and postmitotic counterparts in vivo as a function of the age of the donor. Secondary mitotic human skin fibroblast populations of the cell line HH-8 in vitro underwent 53.6 ± 6.0 cumulative population doublings (CPD) in 302 ± 27 days. If appropriate methods are applied, mitotic fibroblasts differentiate spontaneously into postmitotic fibroblasts which are kept in stationary cultures for up to 305 ± 41 additional days. As a function of the CPD level and of the duration of stationary culture, secondary mitotic and postmitotic fibroblast populations are heterogeneous populations with reproducible changes in the proportions of mitotic fibroblasts MF I, MF II, and MF III, and postmitotic fibroblasts PMF IV, PMF V, PMF VI, and PMF VII. The seven secondary fibroblast cell types show differentiation-dependent and cell-type specific patterns of [ 35 S]methionine polypeptides in total soluble cytoplasmic and nuclear proteins, in secreted proteins, and in membrane bound proteins. These findings make it very likely that the morphologically recognizable primary and secondary fibroblasts differentiate spontaneously along a seven stage terminal cell lineage MF I – MF II – MF III – PMF IV – PMF V – PMF VI – PMF VII in three compartments of the fibroblast stem cell system.

Extracellular ligninase of Phanerochaete chrysosporium Burdsall has no role in the degradation of DDT

Abstract: The white rot fungus Phanerochaete chrysosporium Burdsall degraded DDT [1,1-bis(4-chlorophenyl)-2, 2,2-trichloroethane] in submerged agitated cultures. The ability of the fungus to metabolize this persistent environmental pollutant is not dependent on the formation of its extracellular lignin-degrading enzyme system.

Photoisomerization of sterically hindered azobenzenes

Abstract: The photoisomerization yields of a homologous series of o , o , o ′, o ′-substituted azobenzenes have been determined by excitation of the low lying 1 (n,π*) and the higher lying 1 (π,π*) states. For more severe steric hindrance, i.e. with substituents more bulky than methyl, the E → Z quantum yields are independent of the excitation wavelength, which is in contrast with those for unsubstituted azobenzene, and they seem to decrease with increasing volume of the substituents. This provides further support for our hypothesis of photoisomerization of normal azo compounds: inversion in the lowest states and rotation in the higher states.

Purification and characterization of a heat-stable esterase from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius.

Abstract: A heat-stable esterase has been purified 1080-fold to electrophoretic homogeneity from Sulfolobus acidocaldarius, a thermoacidophilic archaebacterium; 20% of the starting activity is recovered. The purified enzyme shows a specific activity of 158 units/mg, based on the hydrolysis of p-nitrophenyl acetate. The esterase hydrolyses short-chain p-nitrophenyl esters, aliphatic esters and triacylglycerols. It is strongly inhibited by paraoxon and phenylmethanesulphonyl fluoride, but only weakly by eserine. From sedimentation-equilibrium data and molecular sieving in polyacrylamide gels, the Mr of the esterase is estimated to be 117000-128000. SDS/polyacrylamide-gel electrophoresis reveals a single band of protein, of Mr 32000. The purified esterase crystallizes in the presence of poly(ethylene glycol) in short rods. The enzyme is inactivated only on prolonged storage at temperature above 90 degrees C.

Influence of nitrogen on the number of N2-fixing and total bacteria in the rhizosphere

Abstract: Various grass and herbaceous plant species (e.g. Arrhenatherum elatius L., Phleum pratense L., Planlago media L., Taraxacum officinale WEB.) were cultivated in a freshly collected soil from an unfertilized grassland area with its natural population of N2-fixing bacteria. Diazotrophs and total bacteria at the root surface (at outer plus “inner” surface as recovered in root homogenate) and bacteria in the rhizosphere soil (0–3 mm from root surface) were counted by the most probable number (MPN) method. Addition of mineral N (NH4NO3) to the soil decreased its nitrogenase activity (assayed by acetylene reduction) and also the proportion of diazotrophs among the heterotrophs. The result was similar when N was supplied via the leaves, probably owing to an increased release of N-containing compounds with lower C:N ratios from the root. The decrease in the proportion of diazotrophs suggests a competitive suppression by non-diazotrophs in the presence of combined N. Correspondingly, the increase in the MPN of N2-fixing bacteria found during plant development is interpreted as the result of a decrease in N in the soil, particularly in the rhizosphere, by uptake and in addition, a decrease in the N-concentration of the plant with a concomitant change in the C:N ratio of compounds released from the root. The proportion of diazotrophs among total bacteria varied greatly but was lower for bacteria living on or within the roots than for bacteria in the rhizosphere soil. Most of the N2-fixing bacteria were members of the genera Klebsiella and Enterobacter. Species of Azospirillum represented only a small proportion of the total counts.

Production of volatile aroma substances by ‘Golden Delicious’ apple fruits after storage for various times in different CO2 and O2 concentrations

Abstract: Summary‘Golden Delicious’ apple fruits were stored for 3–9 months at 11 combinations of CO2/O2 concentrations at 1°C. The production of volatiles by the stored fruits was measured by gas chromatography during a post-storage shelf-life period at 20°C. The reduction in the production of volatiles largely resembled the general inhibition of ripening under the various controlled-atmosphere (CA) conditions. With increasing CO2- and decreasing O2-concentrations, aroma volatile production was reduced, especially if both gas treatments were simultaneously applied. However, there was neither a simple additive or synergistic, nor a linear relationship between changes in storage atmosphere composition and aroma volatile production. Decreasing the O2 concentration to 3% had little effect on volatile production, but a further decrease to 1% significantly reduced it. At O2 concentrations above 3%, higher CO2 concentration became decisive in diminishing volatile production. After an extended storage, a clear residual CA...

Purification, crystallisation and characterization of quinoprotein ethanol dehydrogenase from Pseudomonas aeruginosa.

Abstract: Pseudomonas aeruginosa ATCC 17933 when grown on ethanol produces high levels of a quinoprotein ethanol dehydrogenase, which amounts to 7% of the soluble protein. The enzyme has been purified to homogeneity and it crystallizes readily in the presence of polyethylene glycol 1550 or 6000. The ethanol dehydrogenase (Km(ethanol) = 14 microM) resembles the dye-dependent quinoprotein methanol dehydrogenases of methylotrophic bacteria, but has a low affinity for methanol (Km (methanol) = 94mM). In addition the enzyme oxidizes secondary alcohols. With its catalytic properties the ethanol dehydrogenase is similar to the enzyme isolated from P. aeruginosa LMD 80.53 (Groen, B., Frank, J. Jzn. & Duine, J.A. (1984) Biochem. J. 223, 921-924). In contrast to this enzyme from P. aeruginosa LMD 80.53, which is a monomer, the ethanol dehydrogenase isolated from P. aeruginosa ATCC 17933 is a dimer of identical subunits of relative molecular mass 60,000. The N-terminal amino acid is lysine. Inactivation with cyclopropanone ethylhemiketal reveals one molecule of pyrroloquinoline quinone per subunit. As shown by active enzyme sedimentation, the dimer is the enzymatically active form.

Effect of cellulose and straw incorporation in soil on total denitrification and nitrogen immobilization at initially aerobic and permanent anaerobic conditions

Abstract: Laboratory experiments were used to examine the influence of cellulose and straw on denitrification and N immobilization in a sandy loam soil. The soil was mixed with 300 μg nitrate-N/g and incubated in a special vessel under conditions that changed from aerobic to anaerobic or in the permanent absence of O2. Gases (O2, CO2, N2, N2O, NO and CH4) were analysed by gas chromatography at regular intervals and the soil was examined for nitrate, nitrite, ammonium and cellulose. Compared with controls, the application of straw and cellulose (0.5% and 1.0%, respectively) enhanced nitrate immobilization and decreased denitrification, under both anaerobic and originally aerobic (PO2 = 20 vol%) conditions. However, a comparison of results from the aerobic and the anaerobic incubations shows that an increase in denitrification and N immobilization was apparent at an original O2 concentration of 20 vol%. N2 was the major product of denitrification in all experiments. Free methane was apparent as soon as nitrate was respired. The stimulating effect of O2 on total denitrification in the presence of relatively high amounts of easily decomposable cellulose is ascribed to a higher turnover and an intensified mineralization rate (CO2 production), which increased the total demand for electron acceptors.

Effect of hematin on the activities of nitrite reductase and catalase in lactobacilli

Abstract: The effect of the addition of hematin on the activities of nitrite reductase and catalase was studied with cell suspensions of strains of lactobacillus species. In cells of Lactobacillus plantarum grown under aerobic or anaerobic conditions nitrite reductase was present. This activity was not exhibited by cells of L. curvatus and only rarely by L. sake. In addition, catalase activity was detected in aerobically grown cells only, with all strains of L. plantarum and L. sake; again L. curvatus was devoid of this activity. Ammonia was formed as the main product of nitrite reduction by L. plantarum. With lactate as the electron donor, the end products of carbohydrate catabolism were carbon dioxide, acetoin and acetate. The activities of nitrite reductase and catalase in strains of lactobacillus species may be used for optimizing the quality of starter cultures applied for the production of raw sausages.

Mobilization of ferric iron from a calcareous soil by plant‐borne chelators (Phytosiderophores)

Abstract: After labelling a calcareous soil with 59Fe, the mobilization of labelled Fe by root exudates of Fe‐deficient barley plants (Hordeum vulgare L.) was studied in vitro at pH 7.4 in short term experiments of up to 48 h. These root exudates contain chelators (phytosiderophores) which form stable FeIII chelates (ferrated phytosiderophores) . Compared to the control (CaSO4), the mobilization rate of labelled Fe within the first 16 h. was increased by phytosiderophores (10‐5M) by a factor between 10 and 20. At chelator concentrations of 10‐5M, the microbial siderophore, Desferal (ferrioxamine B methane sulfonate), was somewhat more effective than phytosiderophores in mobilization of labelled Fe, whereas the synthetic chelator DTPA (diethylenetriamine pentaacetic acid) was ineffective under these conditions. Decreasing the accessibility of 59FeIII at the soil surface by shaking the labelled soil with increasing phosphate concentrations substantially decreased the amount of labelled Fe mobilized by phytos...

Analysis of cold and warm receptor activity in vampire bats and mice

Abstract: The response characteristics of facial thermoreceptors of the common vampire bat and of the mouse have been quantitatively studied. Cold receptors were identified in bat and mouse; warm receptors were only established in the bat. Cold and warm receptor populations of the two species share most of their properties with facial thermoreceptor populations of various mammalian species investigated so far. The temporal pattern of activity of cold receptors of the mouse corresponded to that observed in cats, dogs and monkeys: impulse groups at lower, and beating activity at higher temperatures. At maintained temperature, no impulse groups were initiated in cold receptors of the bat. However, cooling steps from various initial temperatures induced a transient grouped discharge in both cold receptor populations. A discharge in regular groups of impulses was occasionally generated in warm receptors of the bat at maintained temperatures and following warming steps. The data indicate that the temperature dependence of periodic activity in warm receptors is not as uniform as it is in cold receptors. It is concluded that cyclic processes are involved in sensory transduction of both warm and cold receptors, and that this cyclic behavior seems to be a general property of thermoreceptors of presumably all vertebrate species.

Cranial kinesis in the late Cretaceous birds Hesperornis and Parahesperornis

Abstract: -A recently discovered skull of the Cretaceous toothed diving bird Hesperornis permits evaluation of previous descriptions of the skull, analysis of cranial kinesis in hesperornithid birds, and discussion of the evolution of avian cranial kinesis. We found no evidence in hesperornithids for mesokinesis, a system that in lizards involves relative movement of the frontals and parietals. "Maxillokinesis," the fore-aft movements of the palatomaxillary arcade, was also rejected. Evidence for cranial kinesis in hesperornithid birds involves the presence of a streptostylic quadrate bone of virtually modern morphology, three types of flexion zones at the posterior end of the upper jaw, and a hiatus in the nasalinterorbital septum. Among the forms of kinesis found in modern birds, prokinesis, in which the upper jaw moves as a unit, was the dominant type of cranial kinesis in hesperornithids as indicated by the rigid construction of the upper jaw, the position of the holorhinal nostril, and the anteriorly truncate mesethmoid bone; rhynchokinesis and amphikinesis were not possible. Prokinesis is considered primitive for at least the group including Hesperornithiformes and later birds. Discovery of prokinesis in Hesperornis represents the first time all of the morphological correlates of prokinesis have been identified in a bird plesiomorphically lacking pterygoid segmentation. Received 23 April 1987, accepted 5 October 1987. THE skulls of birds have long been recognized as being capable of intracranial mobility (Herissant 1748). After Nitzsch's (1816-1817) analysis, study of avian cranial kinesis received little attention until the beginning of the 20th century (Versluys 1910, 1912). The general patterns of avian kinesis, prokinesis and rhynchokinesis, have been described for modern birds (e.g. Hofer 1949, Bock 1964, Biihler 1981, Zusi 1984). The analyses of the evolution of cranial kinesis in birds, however, have been largely theoretical. In part this is due to lack of sufficient fossil data on the early stages of avian cranial anatomy. A newly discovered fossil bird from the Triassic of Texas was examined by two of us (LDM and LMW) and, although streptostylic, was found to lack the morphological features characteristic of modern avian cranial kinesis. Before the discovery of Triassic birds, the late Jurassic bird Archaeopteryx was the oldest and most primitive known member of the Aves. The anatomy of Archaeopteryx has been the focus of previous studies involving the evolution of cra3 Present address: Department of Cell Biology and Anatomy, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205 USA. nial kinesis in birds (Bock 1964, Wellnhofer 1974, Whetstone 1983, Biihler 1985). Unfortunately, only three specimens of Archaeopteryx preserve cranial material, and all have important details obscured by crushing. Thus, interpretation of the osteological features associated with kinesis is difficult. One aspect of cranial kinesis in Archaeopteryx, namely mesokinesis, can be assessed because of new preparation of the "London" cranium (Whybrow 1982). These findings are discussed below. Although preservational problems prevent detailed analysis of kinesis in Archaeopteryx, one group of Mesozoic birds, the Hesperornithiformes, has sufficiently preserved fossil material. Marsh (1880) described the nominative form Hesperornis. Fossils of hesperornithiform birds are currently restricted to Cretaceous strata. These birds had lost the capacity for flight and became such highly specialized foot-propelled divers that they could not bring their legs under their bodies and stand upright (despite Marsh's oft-repeated restoration; Heilmann 1926, Martin 1980). Teeth are associated with all of the cranial specimens, some of which have teeth still implanted in the jaws. There are four described genera of Hesperornithiformes and others as yet undescribed (Martin MS). Presently, three families are rec111 The Auk 105: 111-122. January 1988 This content downloaded from 157.55.39.255 on Wed, 25 May 2016 06:05:03 UTC All use subject to http://about.jstor.org/terms 112 BUJHLER, MARTIN, AND WITMER [Auk, Vol. 105 ognized: the early Cretaceous Enaliornithidae, including only Enaliornis (Seeley 1876); the late Cretaceous Baptornithidae, including only Baptornis (Marsh 1880, Martin and Tate 1976); and the late Cretaceous Hesperornithidae, including Hesperornis and Parahesperornis (Marsh 1880, Martin 1984). Cranial materials of Baptornis and Enaliornis are fragmentary and are insufficient to address kinesis. Thus, we restrict the following discussion of cranial kinesis to data derived from the hesperornithids Parahesperornis and, in particular, Hesperornis. Kinematics of the hesperornithid skull were ignored by Marsh (1880). Shufeldt (1915) and Heilmann (1926) did not study the original specimens but restored the palate of Hesperornis as being similar to that of a loon. These reconstructions are inaccurate, however, and the hesperornithid palate is unique (Witmer and Martin 1987). Gingerich (1973, 1976) studied the actual fossils described by Marsh (1880), provided a reconstruction (in reality a composite of Hesperornis and Parahesperornis), and discussed cranial kinesis. Our investigations of hesperornithid birds provide detailed positive evidence for prokinesis in a Mesozoic bird and give insight into the evolution of cranial kinesis in birds.

Somatic fusion for breeding of tetraploid potatoes

Abstract: From two tetraploid, one Transformed tetraploid, one triploid and 11 dihaploid clones of Solanum tuberosum somatic hybrids were produced by polyethylene glycol mediated somatic fusion. The inter-dihaploid clones comprised clones of agronomic value, homozygous doubled monohaploids, and in vitro selected clones resistant t0 Fusarium or Phytophthora toxins. Presumptive hybrids were enriched at the callus Stage in vitro by using differentiating media and by growth characteristics; further identification was performed by chromosome counting in vitro shoots and by isozyme analysis of in vitro plants. Final analysis was made from morphological characteristic of plant and tuber phenotypes. From 15 different combinations, 6009 plantlets have been regenerated. From five combinations, 310 reentrants were checked for hybrid nature by morphology and cytology and 88 by peroxidase and esterase isozyme analyses. Amongst these, from two combinations, a total of 17 different hybrids were confirmed by all methods. The procedures described are general enough to allow genome combination of interdihaploids resulting in tetraploids of practical breeding value.