bluuebunny/crossref_metadata_2025 huggingface dataset:
The aetiopathogenesis of acne vulgaris – what's new?
Authors: Bergler‐Czop B.
Published: February 2014

Synopsis

Acne vulgaris is the most frequently diagnosed dermatosis in patients between 11 and 30. It is believed that it affects about 80% of persons in this age group or even, taking into account lesions of low intensity, 100% of young people. The aetiopathogenesis of acne is multifactorial. In all patients with acne, the following symptoms occur: excessive sebum production, excessive keratosis of excretory ducts and openings of sebaceous glands, development of bacterial flora and release of inflammatory mediators in the skin. Development of molecular biology, genetics and immunology contributed to a significant progress in studies on the pathogenesis of acne.
Evaluating the effects of preoperative fasting and fluid limitation
Authors: Tosun Betül , Yava Ayla , Açıkel Cengizhan
Published: February 2014

The aim of the study was to evaluate the effects of preoperative fasting and fluid limitation in patients undergoing laparoscopic cholecystectomy. Although traditional long‐term fasting is not recommended in current preoperative guidelines, this is still a common intervention. Visual analogue scale was used to assess hunger, thirst, sleepiness, exhaustion, nausea and pain; State and Trait Anxiety Inventory was used to assess the preoperative anxiety of 99 patients undergoing elective laparoscopic cholecystectomy. Mean time of preoperative fasting and fluid limitation were, respectively, 14.70 ± 3.14 and 11.25 ± 3.74 h. Preoperatively, 58.60% of the patients experienced moderate anxiety. Patients fasting 12 h or longer had higher hunger, thirst, nausea and pain scores. The mean trait anxiety score of patients fasting 12 h or longer was statistically significantly higher. Receiving nothing by mouth after midnight preoperatively is a persisted intervention and results in discomfort of patients. Clinical protocols should be revised and nurses should be trained in current fasting protocols.
Therapeutic engagement between consumers in suicidal crisis and mental health nurses
Authors: Lees David , Procter Nicholas , Fassett Denise
Published: February 2014

Registered nurses within public mental health services play crucial roles in helping people recover from suicidal crisis. However, there is a lack of understanding of how care is experienced in this context, and available evidence suggests that nurses and consumers are often dissatisfied with the quality of care. There is thus an imperative to generate understanding of needs and experiences of both groups with a view to informing practice development. This article summarizes qualitative findings from a multimethod study undertaken inAustralia, which surveyed and interviewed mental health nurses who had recent experience of caring for consumers in suicidal crisis in a hospital setting, and interviewed consumers who had recovered from a recent suicidal crisis. A framework was developed to guide the study and support ethical imperatives; in particular, the promotion of consumer well‐being. The findings highlight that therapeutic interpersonal engagement between nurses and consumers was central to quality care. This was particularly noted, as engagement could help reduce consumer isolation, loss of control, distress, and objectification of the delivery of potentially‐objectifying common interventions. Of concern, the results indicate a lack of therapeutic engagement from the perspective of both consumers and nurses. Recommendations to promote fuller therapeutic engagement are presented.
The Existence of Chlorophyll c in the Chl b‐Containing, Light‐Harvesting Complex of the Green Alga Mantoniella squamata (Prasinophyceae)
Authors: Wilhelm Chr
Published: February 2014

The prasinophycean alga Mantoniella contains, in addition to Chl a and b, at least a third green pigment which is functionally active in the light‐harvesting antenna. This third Chl was isolated in order to elucidate its chemical structure. The absorption and fluorescence spectra were measured not only from the purified pigment but also from its pheophytin and its methylpheophorbide. The spectra were compared with those of authentic Chl c‐1 and c‐2, which were isolated from the diatom Nitzschia sp. and with Mg‐DVPP (purified from Rhodobacter).

The results show that the pigment from Mantoniella compares best with Chl c‐1. In order to clarify the spectral data, Chl c‐1 and c‐2, Mg‐DVPP, and the pigment from Mantoniella were subjected to a chromatographic system that is able to separate these porphyrins. The chromatographic analysis clearly shows that the pigment from Mantoniella co‐migrates with Chl c‐1 and not with the bacterial pigment. Mantoniella is the first organism which has been demonstrated to contain Chl a, b, and authentic c.
Potassium Transport and Regulation of Intracellular pH in Elodea densa Leaves
Authors: Marrè E. , Beffagna N. , Romani G.
Published: February 2014

The effects of extracellular K+ concentration ([K+]o) on the pH of cell sap, “bulk cytoplasm” and vacuole have been investigated in Elodea densa leaves under conditions of either low or high activity of the plasmalemma electrogenic H+ pump. Cell sap pH was evaluated directly in the cell sap expressed after freezing and thawing. Cytoplasmic and vacuolar pH were calculated by the weak base and weak acid distribution method, DMO and benzylamine appearing to be a suitable acid and base, respectively, for this purpose in this material.

When added to the basal medium (no rapidly permeating ions present), 5 mM K+ induced an increase in intracellular pH, larger for the cell sap and the vacuole (about 0.2 units), and smaller but still significant for the cytoplasm (0.07 units). This alkalinizing effect of K+ was thus associated with a significant decrease in the pH difference across the tonoplast. The alkalinizing effect of K+ was markedly and synergistically enhanced by the presence of fusicoccin, a condition inducing a marked activation of H+ extrusion and of K+ uptake.

The correlation between these effects of [K+]o on intracellular pH and those on H+ extrusion indicates that changes in extracellular K+ concentration, and thus in K+ influx, can influence cytoplasmic and vacuolar pH by modulating the rate of H+ extrusion by the plasmalemma H+ pump.
A Five‐Base‐Pair‐Deletion in the Gene for the Large Subunit Causes the Lesion in the Ribulose Bisphosphate Carboxylase/Oxygenase‐Deficient Plastome Mutant Sigma of Oenothera hookeri
Authors: Winter P. , Herrmann R. G.
Published: February 2014

The gene for the large subunit of ribulose bisphosphate carboxylase/oxygenase (rbcL) has been mapped on the Oenothera hookeri plastid chromosome. It is located close to the gene for the herbicide‐binding “32 kd” protein of the photosystem II reaction center (psbA), at a position different from that found in the ancestral angiosperm type of plastid chromosomes, due to an inversion in the large single‐copy region. The gene codes for a polypeptide of 475 amino acid residues corresponding to a molecular mass of 52.7 kd. The deduced amino acid composition diverges by 4.8% from the amino acid sequence of the spinach protein and by 8.2% from that of maize. The corresponding nucleotide sequences differ by 8.5 % and 15 % from each other. The rbcL gene of the RuBPcase/oase‐deficient Oenothera plastome mutant sigma contains a TTAAC deletion at amino acid residues 270/271 which introduces a frame shift and an amber stop codon seven triplets later. This lesion which probably arose by slipped mispairing is consistent with the previously observed, virtually full‐length mRNA that is decoded into a truncated large subunit polypeptide of approximately 30 kd in vitro and in vivo.
Chemotaxis: Old and New
Authors: Adler J.
Published: February 2014

After describing briefly the work of Engelmann and Pfeffer about 100 years ago, the author presents the early history of bacterial chemotaxis in his laboratory since 1960. Then the report is brought up to the present by review of research in many laboratories including the author's.
Signaling Pathways in Bacterial Chemotaxis
Authors: Taylor B. L. , Johnson M. S. , Smith J. M.
Published: February 2014

The sensory transduction pathways between the transducing proteins and the switch on the flagellar motors have been investigated in Escherichia coli and Salmonella typhimurium. ATP, not GTP, is required for normal chemotaxis. A site of ATP action appears to be the conversion of an inactive form of the CheY protein to an active form, designated CheY*, that binds to the motor switch and initiates clockwise rotation. The methylation‐dependent and methylation‐independent pathways for chemotaxis have a common requirement for the CheA, CheW, and CheY proteins in addition to the switch and flagellar motor. It is concluded that the receptor/transducing proteins and the adaptation mechanism differ in the two types of pathway, but that other components of the transduction pathway are common to the methylation‐dependent and methylation‐independent pathways.
Changes in Carotenoid Composition and Function of the Photosynthetic Apparatus during Light‐dependent Chloroplast Differentiation in Mutant C‐6D of Scenedesmus obliquus*
Authors: Humbeck K. , Römer S. , Senger H.
Published: February 2014

Changes in pigment composition during light‐dependent chloroplast differentiation in mutant C‐6D of Scenedesmus obliquus were followed by HPLC. The system used enables the separation and quantitative determination of five xanthophylls (neoxanthin, violaxanthin, antheraxanthin, lutein and zeaxanthin), α‐ and β‐carotene and chlorophyll a and b (and their epimeric forms).

Dark‐grown cells of the mutant contain only chlorophyll a, traces of chlorophyll b and acyclic precursors of carotenoids. During subsequent illumination, precursors decrease and high amounts of xanthophylls, carotenes and chlorophyll a and b are formed.

Dark‐grown cultures of mutant C‐6D show high photosystem I‐activity and contain the photosystem I‐complex CP I, but lack photosystem II‐activity, the photosystem II‐complex CPa and the LHCP. Immediately after transfer to light, photosystem II‐activity increases rapidly, as also do the amounts of CPa and lutein. Under anaerobiosis no lutein and PS II‐activity can be detected. This indicates a role of lutein in the assembly of an active photosystem II‐complex. All other xanthophylls and the LHCP exhibit high rates of synthesis only after a delay of about 1 hour. Thus, our results reveal an asynchronous fashion of formation of CPa and LHCP.
The Occurrence of the Glucose‐inducible Transport Systems for Glucose, Proline, and Arginine in Different Species of Chlorella
Authors: Komor E. , Cho B.‐H. , Kraus M.
Published: February 2014

Incubation of the green alga Chlorella vulgaris (strain K, Tanner and Kandler, 1967) with glucose leads to the induction of a glucose transport system and of two amino acid transport systems. Because it was not clear whether the regulation of 3 different transport systems by glucose is specific to our strain of Chlorella or whether it is a general property of the genus Chlorella, 11 other free living and symbiotic Chlorella species and strains were tested for glucose‐inducible glucose, arginine and proline transport. It was found that nearly all Chlorella species possess glucose and amino acid uptake systems. Often they were constitutive, although in some species they were induced or stimulated by glucose. According to the transport activities of the different Chlorella species and strains, a physiological classification of Chlorella was constructed, resulting in 3 groups: the C. fusca vacuolata, the C. vulgaris and the symbiotic Chlorella group. Our Chlorella (strain K) obviously belongs to the C. vulgaris group and forms a link to symbiotic Chlorella strains. This suggests that the possession of the glucose‐regulated transport systems is of advantage for Chlorella in symbiotic situations, whereas the constitutive systems are useful for free living Chlorella.
Effects of Salinity on the Extensibility and Ca Availability in the Expanding Region of Growing Barley Leaves
Authors: Lynch J. , Thiel G. , Läuchli A.
Published: February 2014

The growth of barley (Hordeum vulgare L.) leaves is reduced by salinity. We used the Instron extensometric technique to measure the reversible and irreversible compliance of the expanding regions of growing barley leaves from plants exposed to 1, 40, 80 and 120 mM NaCl in nutrient solution. Two barley cultivars differing in salinity resistance (cv ‘Arivat’ and cv ‘Briggs’) were compared over 5d of leaf growth. During the period of most active leaf expansion, salinity reduced reversible compliance and increased compliance in the leaf segments, although responses to salinity were complex and changed over the course of leaf expansion. Salinity increased irreversible compliance more in the salt‐sensitive cultivar Arivat than in the more salt‐tolerant cultivar Briggs.

Elemental analysis of the basal leaf segments used for extensometry revealed an accumulation of Na and a depletion of Ca in segments from salinized plants, resulting in very high Na: Ca ratios in salinized expanding tissue. The concentrations of K and Mg in basal leaf tissue were elevated by salinity.

Our data do support the hypothesis that the inhibition of leaf expansion by salinity stress is mediated by a decline in irreversible extensibility. We suggest that reduced Ca availability in expanding leaf tissue may contribute to growth reduction in salt‐stressed barley seedlings.
The Ubiquitin System in Higher and Lower Plants — Pathways in Protein Metabolism
Authors: Pollmann Lutz , Wettern Michael
Published: February 2014

The multiple biological functions of the small polypeptide ubiquitin are mirrored by its unparalleled conservation on the amino acid and gene organization level.

During the last years, it has become widely accepted that ubiquitin is an essential component in the ATP‐dependent nonlysosomal protein degradation pathway occurring in all eukaryotic organisms. As turnover, consisting of protein synthesis and disassembly, is a central and vital process for each living cell, ubiquitin‐mediated proteolysis is of enormous physiological value. The components of the ubiquitin ligation system have been characterized skillfully in plant and animal cells, but at the moment many questions remain as to how the high degree of specificity that is necessary for the regulation of intracellular breakdown is ensured. The recent hypotheses and models proposed for the basic mechanisms of protein recognition, conjugation and degradation will be discussed in detail.

The existence of ubiquitin‐protein conjugates which are not rapidly degraded clearly suggested that the role of ubiquitin is not restricted in its implication for protein turnover. Alterations of DNA structure, specific cell recognition mechanisms and cytoskeletal variations were observed as further ubiquitin‐dependent processes which are not directly coupled to protein degradation.
Ultrastructural Observations on CTC‐Induced Callose Formation in Riella helicophylla
Authors: Lerchl Daniela , Hillmer Stefan , Grotha R. , Robinson D. G.
Published: February 2014

The Ca2+‐chelator CTC binds to a specific site on both outer surfaces of all non‐meristematic cells of the unistratose thallus of Riella, known to be rich in anionic wall components and calcium, and induces there the deposition of callose. Structural changes in this region during prolonged CTC treatment have been followed by light and transmission electron microscopy. With fluorescence microscopy punctate structures can be detected after 10 min, which upon longer incubation in CTC develop into large vesicular bodies, surrounded by a circular structure. The aniline blue‐derived fluorescence intensity of these structures is highest in cells of the extension growth zone.

At the ultrastructural level a mosaic of numerous smooth‐surfaced vesicles, presumably containing callose, initially appears subjacent to the plasma membrane. These vesicles swell and fuse with each other, forming ultimately a circular fusion profile with the plasma membrane. This complex of callose‐forming vesicles is thought to develop from elements of the partially coated reticulum (PCR), based on the presence of coated vesiculation profiles on the callose vesicles and numerous aggregates of coated vesicles in their immediate vicinity.

After 30 min in CTC osmiophilic particles appear around these callose vesicles and at the cytoplasmic face of mitochondria. They are later (after 60 min) deposited in the periplasmic space between wall and plasma membrane and are also released into the surrounding medium. As judged by their reaction with FeCl3, the osmiophilic particles appear to be phenolic in nature. We propose that upon binding of CTC a local increase of cytoplasmic calcium triggers callose synthesis in PCR‐like compartments beneath the plasma membrane. However it remains to be shown as to why callose is synthesized exclusively in these intracellular compartments and not at the plasma membrane.
Oil‐Gathering Bees Visit Flowers of Eglandular Morphs of the Oil‐Producing Malpighiaceae1
Authors: Sazima M. Sazima and I.
Published: February 2014

The visiting behaviour of oil‐gathering, anthophorid bees on eglandular morphs of two Malpighiaceae species was observed in southeastern Brazil. The bees landed on eglandular flowers apparently by mistake, as suggested by their making one to a few scraping movements on landing, and behaving in the same way as they scrape oil glands on glandular flowers. After perceiving their mistake the bees either left the flower, making one to a few additional visits to other eglandular flowers before leaving the plant, or switched to pollen collecting. Large and medium‐sized species ofCentris, and someEpicharis, left the flowers after mistake visits, thus wasting time and energy, whereas smallCentrisand largerEpicharisswitched to pollen harvesting, thus turning a mistake into a rewarding visit. Eglandular flowers of bothBanisteriopsis muricataandHeteropterys aceroidesattracted oil‐gathering bees by deceit and probably acted as mimics of glandular flowers of their own species (automimicry). The pollination of eglandular morphs of these two Malpighiaceae species seems dependent mainly on the opportunistic, mixed oil‐pollen gathering behaviour of deceived bees such asEpicharis schrottkyi. We suggest that some showy, eglandular species such asBanisteriopsis luteamay act as general mimics of other, oil‐rewarding Malpighiaceae species.
Induction of Actin‐Based Cytoplasmic Contraction in the Siphonous Green Alga Acetabularia (Chlorophyceae) by Locally Restricted Calcium Influx
Authors: Menzel D. , Elsner‐Menzel C.
Published: February 2014

Perfused cell segments dissected from the stalk or from detached cap ray chambers of Acetabularia were used as an experimental system to study the induction of cytoplasmic contractions and concurrent cytoskeletal changes in plant cells. Immunofluorescence microscopy revealed that the actin cytoskeleton quickly rearranges upon induction of contraction by forming bundles oriented circumferentially around the affected area, whereas microtubules were not detected. Contraction is blocked by cytochalasin D or N‐ethylmaleimide but is unaffected by microtubule specific inhibitors. Contraction requires external Ca2+ at concentrations of 1 μM or more, but fails to occur below 0.1 μM. Higher concentrations of Ca2+ up to 10 mM have no adverse effect. Contraction is prevented in the presence of micromolar Ca2+ by either 1 mM of the calcium channel blocker LaCl3 or 10 μM of the calmodulin inhibitor fluphenazine. Calcium ionophore A 23187 (1 μM) does not perturb wound contraction per se but causes the entire cytoplasm of wounded or unwounded cells to contract slowly. These data suggest that a localized influx of calcium ions at the wound edge causes major rearrangements in the distribution of cytoskeletal actin prior to contraction in Acetabularia. An involvement of calmodulin in calcium signaling is proposed.
Determination of the Apparent Km of Nitrate Reductase from Spinach Leaves for NADH by a Coupled Assay
Authors: Sanchez J. , Heldt H. W.
Published: February 2014

Using a novel coupled enzyme activity assay, with a partially purified preparation of spinach leaf nitrate reductase, the apparent Km for NADH was determined as 1.4 μM. These measurements were carried out in the presence of 0.5 mM NAD, which is within the physiological range found in the cytosol of a leaf cell. The results show that an NADH/NAD ratio of 3 × 10−3 is sufficient for a half maximal rate of nitrate reductase.
Geographical and Ecological Differentiation of Roadside Vegetation in Temperate Europe*
Authors: Ullmann I. , Heindl B.
Published: February 2014

A first attempt is made towards a synopsis of the general features and differentiation of roadside phytocoenoses in temperate Europe. The evident similarity between synchorological variation of roadside vegetation and the general chorology of Europe is demonstrated with plant communities dominated by species of Poaceae, Apiaceae, and Asteraceae. A more detailed differentiation along the geographical‐ecological cline between the North Sea and the Mediterranean Sea is represented in modifications of the sequence of coenoses within the roadside profile.
Nematode‐Capturing Hyphomycetes from Soils over Xerophytic Calcareous Rock in Upper Bavaria*
Authors: Fritsch Anne‐Ruth , Lysek G.
Published: February 2014

Nematode‐capturing hyphomycetes were isolated from soil and plant debris on the south slope of a hill in the Jurassic of Upper Bavaria. The following species were found: Arthrobotrys arthrobotryoides, A. dactyloides, A. oligospora, A. superba, Dactylella astenopaga, Monacrosporium cionopagum, M. psychrophilum. Endozoic fungal parasites of nematodes were not isolated. With one fungal propagule of nematode‐destroying fungi in 1.7 g soil, the density is only slightly lower than values given for agricultural soils.
Permeability and Ultrastructure of Bundle Sheath Cells Isolated from C4 Plants: Structure‐Function Studies and the Role of Plasmodesmata
Authors: Valle E. M. , Craig S. , Hatch M. D. , Heldt H. W.
Published: February 2014

Bundle sheath cells from leaves of C4 plants can be isolated as strands surrounding vascular tissue. In this form these cells are highly permeable to metabolites and, as a consequence, they have a variety of experimental uses. The present paper reports on anatomical and ultrastructural features of isolated bundle sheath cell strands in relation to their integrity and permeability. This analysis shows that the cells retain a high degree of structural integrity during isolation. The plasmodesmata that originally connected the bundle sheath cytosol with mesophyll cells are apparently also retained in their entirety. However, at the external surface (mesophyll side) a membranous sac was commonly observed protruding from the end of plasmodesmata. The functional integrity of cells and the molecular weight exclusion limit for entry of compounds was assessed by following plasmolysis and cytorrhysis induced by polyethylene glycol solutions of varying molecular weights. Other evidence for the retention of cell compartment semipermeability is also provided.
Dithionite‐Induced Fluorescence Quenching does not Reflect Reductive Activation in Spinach Chloroplasts*
Authors: Neubauer Christian , Schreiber Ulrich
Published: February 2014

Dithionite is found to cause substantial quenching of chlorophyll fluorescence in intact spinach chloroplasts. In a light‐on induction curve, the I‐P fluorescence rise is selectively suppressed, with a half‐maximal effect at 1.7 × 10−5 M dithionite. Quenching analysis by the saturation pulse method reveals that the dithionite‐induced quenching is photochemical, in analogy to the effect of a Hill reagent. The quenching is suppressed by catalase, KCN and by O2 removal before dithionite addition. These observations, in combination with recent findings on H2O2‐induced photochemical quenching (Neubauer and Schreiber, 1989), lead to the conclusion that H2O2 is formed from reduction products of O2 by dithionite and that it is this H2O2 which, via the action of the ascorbate peroxidase, sustains Hill activity. The results are discussed with reference to the concept of reductive activation of the ferredoxin: NADP oxidoreductase put forward by Satoh (Satoh, 1982). It is concluded that such activation is unlikely to play an essential role in spinach chloroplasts. This conclusion is supported by the observation of suppression of the I‐P fluorescence rise by oxidized NADP in dark‐adapted spinach chloroplasts.
Abscisic Acid Content of Algae under Stress*
Authors: Hirsch R. , Hartung W. , Gimmler H.
Published: February 2014

The distribution of the phytohormone, abscisic acid (ABA), within the phylum of Phycophyta was investigated by an enzyme‐linked immunoassay (ELISA). Of 64 algal species tested (originating from 9 divisions, 20 classes and 36 orders, including procaryotes) all species contained ABA, whereas no ABA could be detected in the bacteria Escherichia coli, Rhodospirillum rubrum, and Halobacterium halobium. It is concluded that ABA is universally distributed within the algal kingdom and is not restricted to cormophytes. The ability to synthesize ABA must have been developed even within the procaryotes. The physiological role of ABA in some selected algae was studied by investigating 1. the distribution of ABA between the cells and the culture medium, 2. the responses of endogenous ABA to stress, 3. the synthesis of 14C‐ABA from externally applied 14C‐mevalonic acid, 4. the metabolism of ABA, 5. the effect of externally applied ABA on various physiological reactions of the algae, and the effect of norflurazon on ABA content. 14C‐mevalonic acid served as precursor of 14C‐ABA synthesis in Dunaliella cells and ABA was metabolised to the same products which have been observed in higher plants. In D. parva the internal ABA level increased upon hyperosmotic salt shocks, and in D. acidophila upon alkalization of the medium. Norflurazon caused an increase of ABA content in Dunaliella. Externally applied ABA did not affect photosynthesis, respiration and K+ content of the cells. The permeability of the plasma membrane of D. acidophila to water was slightly decreased by ABA. The possible physiological function of ABA in algae is discussed.
On the Mechanisms of Secondary Pollen Presentation in the Campanulales‐Asterales‐Complex1
Authors: Leins P. , Erbar Claudia
Published: February 2014

Families of the Campanulales‐Asterales‐complex are characterized by special mechanisms for secondary pollen presentation: pump mechanism, brushing mechanism, deposition mechanism, cup mechanism and combination of cup mechanism with brushing mechanism. These different mechanisms are based on three successive events: elongation of the filaments, opening of the anthers, elongation of the style. The diversity of the mechanisms arises through different auxiliary structures such as an indusium, hairs or an anther tube, and the relative rate and time of filament and style growth. An advantage of secondary pollen presentation lies in the prolongation of the male phase of anthesis through portioned pollen release. A probable phylogeny of the different mechanisms of secondary pollen presentation is proposed (Fig. 7).
C3‐ and C4‐Plants of the Xerophilic Vegetation in the Loess Hills of the Yellow River, Gansu‐Province, NW‐China*
Authors: Wang X.‐C. , Lüttge U. , Ziegler H.
Published: February 2014

The climate of the loess‐hill area near Lanzhou, on the Yellow River, Gansu‐Province, NW‐China is arid throughout the year. The vegetation is xerophilic and mainly dominated by species of Zygophyllaceae, Chenopodiaceae, Plumbaginaceae, Tamaricaceae, Asclepiadaceae and Asteraceae. Among 11 species sampled of these families, δ13C‐analyses only indicated C4‐photosynthesis for 2 species. This relatively low frequency of C4‐plants may be due to elevation (1978 m a.s.l.) and the relatively cold temperatures (annual mean 5.9°C).
Flagellar Development During the Cell Cycle in Chlamydomonas reinhardtii
Authors: Madey P. , Melkonian M.
Published: February 2014

Flagellar development during the asexual synchronous cell cycle of Chlamydomonas reinhardtii (11.32 aM) was studied by light microscopy. Cell walls of sporangia of different developmental status were dissolved using gamete lysin (g‐lysin) enabling direct observation of flagellar development. Flagellar growth in progeny cells exhibits a linear kinetic with a growth rate of 28 nm/min at 30°C leading to a flagellar length of 7–7.5 μm in 4–4.5 h. After this time the flagellar growth rate drops to 2.8 nm/min (as in interphase). Both flagella of a single cell and all flagella within a sporangium grow out at the same time and with the same rate. Cycloheximide (10 μg/ml) completely blocks flagellar development. If cycloheximide is removed flagellar growth resumes at the normal rate with no lag‐phase.

Flagellar development during the cell cycle in C. reinhardtii differs considerably from the well‐studied model system of flagellar regeneration following amputation in the same species.
Die Ontogenese der Salzdrüsen von Limonium (Plumbaginaceae); The Ontogenesis of the Salt Glands of Limonium (Plumbaginaceae)
Authors: Wiehe W. , Breckle S.‐W.
Published: February 2014

Die Salzdrüsen der Gattung Limonium leiten sich ontogenetisch von einer einzelnen epidermalen Zelle ab, die sich in fünf Teilungsschritten zu einem 20‐zelligen Drüsenkomplex differenziert. Die Cutinisierung des Drüsenkomplexes erfolgt bereits nach dem vierten Teilungsschritt bei der Bildung der vier Sammel‐ und der vier Bechermutterzellen. Diese werden durch den fünften Teilungsschritt in innere und äußere Becherzellen geteilt.

The Limonium‐salt gland develops from only one epidermal cell in five steps of cell‐division to a gland complex of 20 cells. Cutinisation on the gland complex starts after the fourth step of cell‐division, when four collecting cells and four mother cells of the cup cells are formed. In the last step the mother cup cells divide into four inner cup cells and four outer cup cells.
Biochemical Taxonomy of Symbiotic Chlorella Strains from Paramecium and Acanthocystis*
Authors: Kessler E. , Huss V. A. R.
Published: February 2014

Biochemical and physiological characters of 5 symbiotic Chlorella strains, 4 of them from Paramecium (Ciliata) and one from Acanthocystis (Rhizopoda, Heliozoa), were studied. Four strains (3 from Paramecium and one from Acanthocystis) belong to the same species. This is characterized by the presence of hydrogenase, no formation of secondary carotenoids, no growth on mannitol, requirements for thiamine and vitamin B12, and a G + C content of the DNA of 66.4–68.4 mol%; the limits of growth are at pH 5.5, at up to 1% NaCl, and at 26–30°C. The strains are somewhat heterogeneous in their utilization of inorganic nitrogen sources: only two of them are able to use nitrate, whereas all can grow with nitrite and ammonium. Thus, in two strains the nitrate‐reducing system — in contrast to nitrite reductase — seems to be defective. Another strain, which has been claimed to be from Paramecium, belongs to C. protothecoides.
Hypersensitive Reaction of Nodule Cells in the Glycine sp./Bradyrhizobium japonicum‐Symbiosis Occurs at the Genotype‐Specific Level*
Authors: Parniske M. , Zimmermann Christa , Cregan P. B. , Werner D.
Published: February 2014

Three Glycine genotypes, G. max cv. Williams, G. soja PI 468397, and G. soja PI 342434 in combination with the two rhizobial strains Bradyrhizobium japonicum USDA 123 and Rhizobium fredii USDA 193 were analysed for phytoalexin concentration in the nodules. In the nodules of PI 468397/B. japonicum USDA 123 a very strong glyceollin I accumulation occurred around 30 d.p.i. Ultrastructural analysis of these nodules revealed several symptoms of a severe plant defense response associated with plant cell death (hypersensitive reaction): The cytoplasm of the infected cells was degraded and organelles had vanished. The cell walls of the infected cells showed remarkable thickening. This plant defense response could only be observed in this strain/genotype interaction. The same strain did not elicit a phytoalexin accumulation in the other plant genotypes tested, indicating that this response occurs at the genotype‐specific level. This special character of G. soja PI 468397 is heritable as indicated by glyceollin I analysis of the nodules formed by F1 hybrids of PI 468397xWilliams inoculated with B. japonicum USDA 123. The genotype/strain specific occurrence of the hypersensitive response in root nodules resembles the race/cultivar specific incompatibility of several plant‐pathogen interactions. This specificity, together with the phenomenon of the HR itself, points out the close physiological relationship between the late stages of the root nodule symbiosis and a plant/pathogen interaction.
Neutral Red as a Redox Dye Induces K+ Efflux and Current‐Voltage Changes in Eremosphaera, Lemna, and Guard Cells*
Authors: Ullrich C. I. , Köhler K. , Baier M. , Förster B. , Hartung W.
Published: February 2014

Membrane effects of the redox and pH indicator neutral red were studied with the chlorococcal alga Eremosphaera viridis, with Lemna gibba, and with “isolated” guard cells in epidermal peels of Valerianella locusta. Neutral red was extracellularly reduced and caused transmembrane current‐voltage changes, an increase in membrane conductance by about 14 nS, an apparent K+ net efflux of up to 120 μmol g−1 FW in 5 min, and an intracellular acidification by up to 0.7 pH units. Neutral red‐triggered K+ net efflux was most pronounced at low pH, at an Eo more positive than −200 mV, and without extracellular Ca2+. From the experimental data it is concluded that, due to the redox function of the phenazine molecule, extracellular neutral red triggers a trans‐plasmalemma e− transfer, leading to strong membrane depolarization and charge compensating K+ net efflux, in addition to some unspecific ion release. As a consequence the intracellular concentration of strong cations relative to strong anions (SID) decreases, resulting in intracellular acidification.
The Distribution of a Phytochrome‐Like Protein in the Fern Psilotum nudum.; An Immunoblotting Analysis of an Early Ancestor of all Vascular Plants
Authors: Schneider‐Poetsch H. A. W. , John Gabriele , Braun Birgit
Published: February 2014

The distribution of a 125 kg . mol−1 protein recognized by a monoclonal antibody raised against phytochrome of maize was analyzed in the sporophyte of the fern Psilotum nudum. Highest amounts (up to 5 μg per fresh weight) of this protein were found in the tips of expanding shoots. Green sporangia as well as the pale tips of the rhizome contained this 125 kg . mol−1 protein, too. In the brown parts of the rhizome it was more rarely contained. Unlike phytochrome from etiolated higher plants, the Psilotum protein appeared to be scarcely degraded by the illuminated plants. In this respect the protein of Psilotum seems to resemble the small fraction of phytochrome contained in green and illuminated higher plants. Moreover, after illuminating the Psilotum rhizome for 3 d, higher amounts of this protein were detected therein as before.
Temporal Pattern of Gene Expression in Cotyledons of Mustard (Sinapis alba L.) Seedlings
Authors: Wenng A. , Batschauer A. , Ehmann B. , Schäfer E.
Published: February 2014

The time course of appearance of competence to phytochrome (Pfr) was studied in cotyledons of mustard (Sinapis alba L.) with regard to the light‐mediated accumulation of mRNAs encoding for SSU, CAB and the 23 kDa protein of the oxygen evolving complex of photosystem II (OEC). For each gene family a specific starting point of Pfr‐induced mRNA accumulation was observed (SSU: 42 h; CAB: 36 h; OEC: 30 h). An increase of SSU‐mRNA levels can be detected 24 h after sowing in dark‐grown seedlings whereas for OEC the time points for the increase of mRNA are the same whether the seedlings are kept in darkness or induced by light via Pfr. For all gene families a responsiveness to Pfr (coupling point) could be demonstrated before the starting points. The coupling points are also gene specific (SSU: ca. 12 h; CAB and 23 kDa peptide of OEC: ca. 24 h). The responsiveness to light before the starting point indicates that the light‐induced signal must be stored.
The Supramolecular Structure of Photosystem II — Phycobilisome‐Complexes of Porphyridium cruentum
Authors: Lange W. , Wilhelm C. , Wehrmeyer W. , Mörschel E.
Published: February 2014

The structure and arrangement of phycobilisomes of the unicellular red alga Porphyridium cruentum is compared with the organization of the thylakoid freeze‐fracture particles in order to determine the relationship between phycobilisomes and photosystem II. The hemi‐ellipsoidal phycobilisomes, 20 nm thick, are predominantly organized into rows; their centre to centre periodicity is 30–40 nm, so that they are well separated by a gap of 10–20 nm. The phycobilisomes are cleaved by a central faint furrow, parallel to the long axis from top to base.

The organization of the exoplasmic particles in rows is similar to the arrangement of the phycobilisomes so that a structural relationship between both systems, previously demonstrated in cyanobacteria, is evident. Within the rows, the 10 nm EF‐particles are grouped in tetrameric complexes separated by distances similar to those observed for phycobilisomes. We propose that the tetrameric EF‐particle complexes correspond to tetrameric photosystem II complexes which bind one hemi‐ellipsoidal phycobilisome on the stroma exposed surface of the thylakoid. A hypothetical model of this photosystem II‐phycobilisome complex is presented.
Characterization of CF1 from the Diatom Odontella sinensis
Authors: Päncic P. G. , Kowallik K. V. , Strotmann H.
Published: February 2014

The CF1 moiety of the chloroplast ATPase of the diatom Odontella sinensis was solubilized from isolated thylakoids by chloroform extraction. Further purification was achieved by HPLC on a Superose‐6 column. The resulting four‐subunit complex was identified as CF1 lacking subunit δ. The larger two subunits, α and β, showed cross‐reactivity with antisera raised against the homologous subunits of spinach‐CF1. Western blot analysis further revealed that — contrary to other ATPases — migration in SDS‐PAGE of α was faster than migration of β, suggesting a deletion of 40 to 50 amino acids in subunit α of Odontella. The assumed deletion does not involve the N‐terminal side of the protein, as was established by protein sequencing. The N‐terminal sequences of subunits α and γ showed highest homologies with the equivalent subunits of blue‐green algae. According to SDS‐PAGE, the apparent molecular weights of the four Odontella subunits were 53.2 (β), 51.2 (α), 39.3 (γ) and 16.2 (ε) kD. ATPase activity of isolated Odontella‐CF1 could be induced by trypsin or octylglucoside, and to a lesser extent by sulfite or by alcohols such as methanol or ethanol.
Light/Dark Modulation: Regulation of Chloroplast Metabolism in a New Light
Authors: Scheibe Renate
Published: February 2014

Light‐dark modulation of chloroplast enzymes is achieved by covalent redox‐modification of protein thiols/disulfides mediated by ferredoxin/thioredoxin reductase and thioredoxins. Light‐dependent electron flow leads to reduction of particular chloroplast proteins, while photosynthetically evolved oxygen effects their continuous reoxidation. The oxidized and the reduced forms, respectively, differ greatly in their catalytic properties. The rate of reduction of each target enzyme is specifically fine‐controlled by metabolites. By this combined mode of producing a defined ratio of active to inactive enzyme during steady‐state each of the enzymes is adjusted to the immediate requirements of the chloroplast. Upon changes of the metabolic situation the system can respond in a flexible manner as is known from comparable regulatory mechanisms such as protein phosphorylation/dephosphorylation in animals and bacteria. From sequence comparisons between various light‐dark modulated chloroplast enzymes and their non‐regulated counterparts from other organelles or non‐photosynthetic organisms, the presence of extra‐peptides in the otherwise highly homologous sequences has been estabüshed for the chloroplast enzymes. However, no general pattern in the primary structure of those extra‐sequences can be recognized. By the acquisition of “regulatory peptides” during evolution a new type of metabolic control was created in a compartment uniquely occurring in organisms performing oxygenic photosynthesis.
Outward Extension of Spinules in Exine of Centrolepis aristata (Centrolepidaceae)
Authors: Rowley J. R. , Dunbar Anita
Published: February 2014

Spinules extend outwards 0.2 to 0.3 μm into the plasmodial tapetum during periods of rapid growth of microspores of Centrolepis. Before and after these intervals spinules commonly protrude only ca 0.05 μm above the surface of the tectum. The extended spinules have a rod shaped core ca 40 nm in diameter. The surface of the core is surrounded by loops ca 30 nm in diameter arranged in a regular pattern.
Karyological Differentiation in Sapindaceae with Special Reference to Serjania and Cardiospermum
Authors: Hemmer W. , Morawetz W.
Published: February 2014

New chromosome counts for 9 species and 2 genera of Sapindaceae are presented and compared with a review of all available chromosome numbers of the family. In 4 species diploid numbers differing from previous reports are found. In 4 species of the tribe Paullinieae (S. diversiflora, S. subdentata, C. grandiflorum and C. halicacabum) detailed studies on interphase nucleus structure, condensing behaviour and chromosome banding patterns are presented. The karyological differentiation of Paullinieae is generally characterized by dysploid reduction of chromosome numbers and the increase of chromosome size. Sequential staining of nuclei with CMA/DAPI and Giemsa‐C‐banding demonstrates diversification of constitutive heterochromatin (= hc) and different types of chromatin organization in Serjania and Cardiospermum. The obvious lack of polyploid series and the karyological evolution within the family is discussed. The outstanding small genome size found in Cardiospermum halicacabum is considered to be due to a secondary loss of DNA in the course of the change to herbaceous growth.
Developmental Aspects of Ultrastructure and Histochemistry of the Stylar Transmitting Tissue of Nicotiana sylvestris
Authors: Kandasamy M. K. , Kristen U.
Published: February 2014

The structure and histochemistry of the solid style of Nicotiana sylvestris Speg. and Comes have been studied by light and electron microscopy. The transmitting tissue develops large intercellular spaces filled with secretions rich in proteins and carbohydrates during maturation. The cells possess large nuclei, numerous plastids with starch grains, mitochondria, ribosomes and well developed endoplasmic reticulum and golgi apparatus. The plastids in the stylar region immediately below the stigma produce electron‐dense osmiophilic substances which are probably transferred into the cytoplasm by a process resembling budding‐off of vesicles. The Golgi apparatus may use the starch grains as a source of sugars for the synthesis and secretion of extracellular polysaccharides. The structural and cytochemical differences between the glandular cells of the stigma and the stylar transmitting tissue are discussed.
Subcellular Distribution of Free Amino Acids in Relation to Protein Synthesis in Cells of Chara corallina
Authors: Mimura T. , Sakano K. , Moriyasu Y. , Tazawa M.
Published: February 2014

The influence of protein‐synthesis inhibitors on the subcellular distribution of free amino acids was studied in internodal cells of Chara corallina. Use of an intracellular perfusion technique allowed separate measurements of amino acids in the vacuole, in the flowing sol endoplasm and in the gel layer. The sol endoplasm predominantly represents the cytosol, while the gel layer is occupied, for the most part, by chloroplasts.

When cells were treated with 0.5 mM chloramphenicol (CRP) in the dark, both the total concentration of amino acids and the subcellular distribution were almost the same as in cells without treatment. In the light, however, the subcellular distribution changed dramatically, although the total concentration of amino acids was unchanged. The vacuolar concentration of amino acids was 3 times greater in CRP‐treated cells than in the control. The concentrations of amino acids in the sol endoplasm and in the gel layer were only half of those in the control. Amino acid permeability of the chloroplast envelope, measured using the perfused internodal cells, slightly increased after the CRP treatment in the light.

Time‐dependent changes in concentrations of amino acids in the CRP‐treated cells were also measured in the light. The total concentration of amino acids in the cytoplasm gradually decreased, while that in the vacuole increased commensurately. The concentration and/or subcellular distribution of alanine, glutamine, glutamate and glycine changed dramatically. The concentration of alanine increased considerably both in the vacuole and in the cytoplasm. The cytoplasmic concentration of glutamine increased transiently within 1 −2 h after treatment with CRP. The cytoplasmic concentrations of glutamate and glycine decreased. Although the concentrations of some amino acids changed so markedly both in the vacuole and cytoplasm, only small differences in the activities of glutamic‐pyruvic transaminase, glutamic‐oxaloacetic transaminase and glutamine synthetase were detected between the control and the CRP‐treated cells.
Ein Beitrag zur Systematik und Entwicklungsbiologie höherer Pilze: Hefe‐Typen der Basidiomyceten. Teil II: Microbotryum‐Typ
Authors: Prillinger H. , Deml G. , Dörfler Ch. , Laaser G. , Lockau W.
Published: February 2014

In this and three further papers 205 yeasts and yeast states of Basidiomycetes and presumed relatives were investigated comparatively on the basis of the carbohydrate (neutral sugars) pattern of purified cell walls, urease‐activity, diazonium blue B reaction on the production of extracellular amyloid compounds (EAS), fermentation of carbohydrates, and ubiquinone data. A clustering leading to the Protomyces‐, the Microbotryum‐, the Ustilago‐, the Dacrymyces‐, and the Tremella‐type became apparent, especially from the qualitative and quantitative cell wall carbohydrate pattern.

The different yeast types correspond well with 5S rRNA clusters known from the literature. 31 strains clustering within the Microbotryum‐type comprise the phragmobasidial smut fungi of dicotyledonous hosts (Microbotryum. Sphacelotheca), the phragmobasidial Rhodosporidium‐ and Leucosporidium‐species including some anamorph Rhodotorula‐species, which lack an oxidative degradation of myo‐inositol, the genera Sporobolomyces and Sporidiobolus, the Septobasidiales and some simple septate Auriculariales e.g. Agaricostilbum, Platygloea. Main characteristics of the Microbotryum‐type are: 1. The absence of extracellular amyloid compounds. 2. The dominance of mannose and the presence of fucose as cell wall constituents. 3. A positive DBB‐reaction and splitting of urea. Four Ustilago species parasitic on dicotyledonous hosts were transfered to Microbotryum (M. scabiosae, M. scorzonerae, M. cordae, M. vinosum) as a consequence from cell wall carbohydrate composition, production of rhodotorulic acid, and 5S rRNA sequence data from the literature.

The predominance of mannose in the cell wall — otherwise only known from ascomycetous yeasts –, a type A secondary structure of 5S rRNA, a simple unifactorial mating system in all parasitic smut species suggest that the Microbotryum‐type might be ancestral to the Ustilago‐type. An evolution of simple (“siphonal”) holobasidia from “pseudotrichal” phragmobasidia will be discussed.