39. Erika Müller und Klaus Müller: Beobachtungen über das Verhalten einiger bisher kritischer Kompaßpflanzen1

Es wurden an Achillea clavenae, A. clypeolata, A. millefolium, A. ptarmica, A. serbica und A. sibirica, besonders aber an Tanacetum vulgare und Achillea filipendulina Untersuchungen angestellt. Alle genannten Arten wiesen äquifazialen Blattbau auf. Mit Hilfe von Messungen konnte statistisch abgesichert werden, daß T. vulgare und A. filipendulina unter ?geeigneten” Bedingungen Kompaßstellung einnehmen (Tab. 1 und 2). Die von Linstow (18) erwähnte Kompaßstellung von A. clypeolata konnte bestätigt werden. Die Blätter von A. ptarmica scheinen nur unter widernatürlichen Bedingungen zur Kompaßstellung befähigt zu sein. A. clavenae wies regelmäßig Vertikalstellung mit einer Tendenz zur Nord-Süd-Orientierung auf. Bei A. serbica und A. sibirica konnte ähnliches nicht gefunden werden, die Fiederchen von A. millefolium nehmen oft eine bemerkenswerte Schutzstellung ein. Für die ungerichteten Blatttorsionen der A. filipendulina ist offenbar ein endogener Faktor verantwortlich, wie durch Versuche am Klinostaten nachgewiesen wurde. Ein solcher scheint bei T. vulgare zu fehlen. Durch Laborversuche wurde gezeigt, daß für die Ausrichtung der Blätter von T. vulgare und A. filipendulina die Wärmestrahlung als exogener Faktor verantwortlich ist. Von den beiden zuletzt genannten Arten wurden 427 Blätter in Zwangslagen gebracht; es ergab sich eine Zunahme der Blattdicke (vor allem der Palisadenschichten) in Abhängigkeit von der Intensität der Sonnenstrahlung, der Dauer sowie der Art und Weise des Festhaltens in der Zwangslage (Tab. 3 und 4). Nur bei sehr jungen Blättern wurde ein Absterben beobachtet, was vermutlich auf Verbrennung zurückging.     

Length–weight relationship of Rhinobatos horkelii Müller & Henle, 1841 and Zapteryx brevirostris (Müller & Henle, 1841) off Brazil,southwestern Atlantic Ocean

This study reports the length–weight relationships (LWRs) for two elasmobranch species, Rhinobatos horkelii Müller & Henle, 1841 and Zapteryx brevirostris (Müller & Henle, 1841) collected from the southwestern Atlantic, off Brazil. Both are considered endangered species. The LWR data can be taken into consideration for further management and conservation plans.     

Hydrogen peroxide modulates energy metabolism and oxidative stress in cultures of permanent human Müller cells MIO‐M1

In this study the influence of hydrogen peroxide (H₂O₂) on the redox state, NADH protein binding, and mitochondrial membrane potential in Müller cells is investigated. Cultures of permanent human Müller cells MIO‐M1 were exposed to H₂O₂ in 75 µM and 150 µM concentration for two hours. Fluorescence emission spectra and lifetimes were measured by two‐photon microscopy (excitation wavelength: 740 nm) at the mitochondria which were identified in the microscopic images by their fluorescence properties (spectra and intensity). Two hours of H₂O₂ exposure did not impair viability of MIO‐M1 cells in culture. Whereas the ratio of flavine‐ to NADH fluorescence intensity did not change under either H₂O₂ concentration, the mean lifetime was significantly different between controls, not exposed to H₂O₂, and the 150 µM H₂O₂ exposure (972 ± 63 ps vs. 1152 ± 64 ps, p = 0.014). One hour after cessation of the H₂O₂ exposure, the value retuned to that of the control (983 ± 36 ps). A hyperpolarization of the mitochondrial membrane under 150 µM H₂O₂ was found. These findings suggest a shift form free to protein‐bound NADH in mitochondria as well as a hyperpolarization of their inner membrane which could be related to an impairment of Müller cell function despite their preserved viability.

Exposure of human Müller cells to hydrogen peroxide for two hours results in a reversible change of protein binding of mitochondrial NADH upon unchanged redox ratio. The mitochondrial membrane potential is increased during exposure.     

Murine dopaminergic Müller cells restore motor function in a model of Parkinson's disease

Müller cells constitute the main glial cell type in the retina where it interacts with virtually all cells displaying relevant functions to retinal physiology. Under appropriate stimuli, Müller cells may undergo dedifferentiation, being able to generate other neural cell types. Here, we show that purified mouse Müller cells in culture express a group of proteins related to the dopaminergic phenotype, including the nuclear receptor‐related 1 protein, required for dopaminergic differentiation, as well the enzyme tyrosine hydroxylase. These dopaminergic components are active, since Müller cells are able to synthesize and release dopamine to the extracellular medium. Moreover, Müller‐derived tyrosine hydroxylase can be regulated, increasing its activity because of phosphorylation of serine residues in response to agents that increase intracellular cAMP levels. These observations were extended to glial cells obtained from adult monkey retinas with essentially the same results. To address the potential use of dopaminergic Müller cells as a source of dopamine in cell therapy procedures, we used a mouse model of Parkinson's disease, in which mouse Müller cells with the dopaminergic phenotype were transplanted into the striatum of hemi‐parkinsonian mice generated by unilateral injection of 6‐hydroxydopamine. These cells fully decreased the apomorphine‐induced rotational behavior and restored motor functions in these animals, as measured by the rotarod and the forelimb‐use asymmetry (cylinder) tests. The data indicate local restoration of dopaminergic signaling in hemi‐parkinsonian mice confirmed by measurement of striatal dopamine after Müller cell grafting.

     

膜转运蛋白ABCA1的结构与功能

膜转运蛋白ABCA1可以将包括胆固醇、磷脂在内的多种物质由细胞内转运至胞外,发挥抗动脉硬化的功能,它的突变可以导致严重的HDL缺乏综合征。该就ABCA1的结构与功能关系,作用机制,调控等方面做一简要介绍。     

Macroscopic and histological investigation of guanaco footpads (Lama guanicoe,Müller 1776)

The surface of guanaco footpads is characterized by hairless skin with up to 4‐mm‐thick stratum corneum that protects from abrasion. The horny layer is pliable and elastic, and ensures firm contact with irregular ground. It is padded with a particular structure of the subcutaneous layer, the digital cushion. The flat cushions of each of the two digits are of elongated ovate shape, each about 45‐mm long, up to 20‐mm wide, and 8‐mm thick. The cushions are lined by a 1–2‐mm‐thick capsule that resembles a tunica albuginea. The capsule consists of coarse collagen fibers, with elastic fibers absent. The cushion capsule and dermis approach each other, and fuse along a line that runs parallel to the longitudinal axes of cushion and digit. Loose connective tissue rich in elastic fibers and acidic glycosaminoglycans separates dermis and cushion capsule lateral to the narrow interconnecting zone. The cushion capsule encloses cloudy yellowish, gelatinous material. Microscopy shows bundles of elastic fibers in abundant mucinous matrix. Tightly gathered elastic bundles adjoin the inner surface of the capsule. Rough cords of elastic fibers branch out from there and traverse to the opposite side. The cushion is pressed flat, and elastic fibers are stretched when bearing weight. With relief of load, elastic fibers contract and reset the cushion's shape. Contractile cells are absent. A resistant capsule and easily malleable mucinous contents establish the functioning as a gel pad. Mucinous connective tissue between elastic fiber bundles contains abundant basophilic matrix. Hyaluronan, chondroitin sulfate, and dermatan sulfate are main matrix constituents. Spindle‐shaped or stellate fibroblasts contain vimentin, S100 protein, and neuron specific enolase. Moprhology, staining characteristics and synthesis activities of these cells meet the criteria to be classified as myxoid cells. The connective tissue in guanaco digital cushions represents myxoid tissue. J. Morphol. 276:331–341, 2015. © 2014 Wiley Periodicals, Inc.     

The structure of the cutaneous pedal glands in the banded snail Cepaea hortensis (Müller, 1774)

Although gastropods have been crawling through the ocean and on the land for 60 million years, we still know very little about the sticky mucus produced in their foot. Most research has been focused on marine species in particular and, to a lesser extent, on the well‐known terrestrial species Arion vulgaris and Cornu aspersum. Within this study, we aim to characterize the foot anatomy of a smaller representative of the family Helicidae, the banded snail Cepaea hortensis. We are particularly interested in the microanatomy of the foot glands, their position, and the histochemical nature of their secretory content. Characterization of the dorsal foot region of Cepaea hortensis reveals four glands, differing in their size and in the granules produced. Histochemically, three of them react positively for sugars (PAS staining and lectin affinity tests for mannose, glucose and N‐acetyl‐d ‐glucosamine) and acidic proteins (positive Alcian blue and Toluidine blue staining), indicating the presence of acidic glycosaminoglycans. The fourth gland type does not react to any of these dyes. The ventral pedal region includes two different gland types, which are positive for the presence of acidic glycoproteins, with a lectin affinity for mannose only. A comparison with Helix pomatia indicates differences regarding the number of glands and their contents. In Helix, only three gland types are described in the dorsal region of the foot, which show a similar granular appearance but nevertheless differ in their chemical composition. Congruently, there are two gland types in the ventral region in both species, whereas in Helix an additional sugar moiety is found. This raises the question whether these differences between the pedal glandular systems of both helicid species are the result of protection or size‐related adaptations, as they occur in the same habitat.     

The neck region of the spermatozoon of Discus rotundatus (Müller) (Pulmonata,Stylommatophora)

The neck region of the mature spermatozoon of Discus rotundatus is described. No evidence for a centriole or centriolar derivative is obtained. Nine striated coarse fibres and the two central fibres of the axoneme extend into the base of the implantation fossa. The axonemal doublet system is disrupted in the neck region. There are two fibrous accessory structures located between the central doublet and the striated coarse fibres.     

The effect of constant and changing temperatures on the thermal resistance of Lymnaea peregra (Müller)

The effect of constant and changing temperatures on both high and low lethal temperatures of Lymnaea peregra and the time course of acclimation were investigated. Snails acclimated to 6.5°, 11.5° and 16.5°C showed paradoxical ‘adaptation’ of their high letal temperature and reasonable ‘adaptation’ of the lowlethal temperature. This combination is thus observed for the first time in molluscs. Seasonal variation in the upper lethal temperature showed parallel changes and the snails became less resistant to heat during spring and summer. Acclimation to changing temperature conditions did not extend their temperature tolerance range. During the course of acclimation of 6.5°C snails to 16.5°C, about 70% of the acclimation was completed within the first 24 h and the rest was completed within 360 h at 16.5°C.     

Growth of Tubifex tubifex Müller (Oligochaeta,Tubificidae) under Various Trophic Conditions

Growth of Tubifex tubifex on highly caloric activated sludge and poor in organic matter natural silt was experimentally studied. The relationship between oxygen consumption rate, weight, and caloric value of T. tubifex body in culture on activated sludge was determined to calculate the growth efficiency (K₂ = P/P + R). The growth rate has been determined, and models of T. tubifex growth are given under various trophic conditions conforming to results of the experiment. Somatic growth, generative growth and life span of this species were compared on the basis of the experiments and literature. Acceleration of growth and prolongation of life under conditions of caloric food and delay of these processes in silt poor in organic matter have been established and measured. T. tubifex was found to have advantages as compared to other tubificid species in response to increasing amounts of nutrient food in waters polluted by organic matter and, therefore, to produce abundant populations under these conditions.