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1.
Denise Risch Nicholas J. Gales Jason Gedamke Lars Kindermann Douglas P. Nowacek Andrew J. Read Ursula Siebert Ilse C. Van Opzeeland Sofie M. Van Parijs Ari S. Friedlaender 《Biology letters》2014,10(4)
For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action. 相似文献
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The protein synthesis-stimulating activity of the cytosolic fraction from regenerating rat liver was tested in a cell-free system using washed polysomes from normal rat liver. This activity undergoes significant changes during liver regeneration after partial hepatectomy (p.h.). An initial decrease until 16 h after p.h. is followed by a significant increase until 24 h after p.h. Beyond 32 h after p.h. the activity begins to decline again. Evidence is presented that these changes of the cytosolic activity may not be due to alterations in the distribution of protein synthesis-stimulating factors between the microsomal and the cytosolic fraction. The Met-tRNAf-binding activity of the cytosolic fraction changes during liver regeneration analogously to the protein synthesis-stimulating activity measured in the polysomal assay. This indicates that initiation factor eIF-2 is involved in the observed changes of the cytosolic activity. This conclusion could be confirmed by addition of purified eIF-2 to the polysomal assay system. Addition of eIF-2 to cytosolic fractions of low endogenous protein synthesis-stimulating activity (16 h after p.h.) enhances amino-acid incorporation to a significantly higher extent than addition to highly active cytosolic fractions (24 h and 32 h after p.h.). From these results it is concluded that changes in eIF-2 plays an essential role in the described alterations of the cytosolic activities during liver regeneration. 相似文献
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Calli of P. argentatum were grown on a newly designed liquid nutrient flow-through system which facilitated the subculturing of calli and delayed
browning for 6 weeks. Friable calli were obtained on half-strength Gamborg B5-medium supplemented with 0.05 mgl−1 2,4-dichlorophenoxyacetic acid. Shoots developed on media supplemented with 0.2 mgl−1 benzylaminopurine but lacking 2,4-dichlorophenocyacetic acid. 相似文献
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The effects of solar and artifical ultraviolet radiation on the marine cryptoflagellate, Cryptomonas maculata, were studied. Even after short exposure to UV the accessory photosynthetic pigment phycoerythrin is bleached; likewise the fluorescence undergoes significant changes both in amplitude and in the maximal peak wavelength. In parallel, the photosynthetic oxygen production decreases rapidly during exposure. Gel electrophoresis and FPLC of membrane proteins show a significant decrease in chromoproteins after 2 h UV, which is confirmed by fluorescence excitation and emission spectra of the FPLC fractions.Abbreviations APS
ammonium persulfate
- DCMU
3-(3,4dichlorophenyl)1,1-dimethylurea; Emulphogen, polyoxyethylene 10 tridecyl ether
- FPLC
fast protein liquid chromatography
- PMSF
phenylmethylsulfonyl fluoride
- SDS
sodium dodecylsulfate
- SDS PAGE
sodium dodecylsulfate polyacrylamide gel electrophoresis
- TEMED
NN NNtetramethylethylene diamine
- UV-A
wavelength range between 320 nm and 400 nm
- UV-B
wavelength range between 280 nm and 320 nm
Dedicated to the 60th birthday of Professor Dr. W. Wehrmeyer 相似文献
7.
In Avena coleoptile segments a decrease of cytoplasmic pH activates energy-dependent H+ extrusion into the apoplast, thereby triggering extension growth. This sequence of events cannot be inhibited by cycloheximide and is induced by the following conditions and compounds. (i) A short anaerobic treatment of coleoptile segments results in the formation of lactic acid and an intracellular decrease of pH. For a period of 20 min after transfer to normal air, the growth rate is up to six times higher than the rate before anaerobiosis. (ii) Similarly, incubation of segments with CN– (0.1 mM) in the presence of oxygen causes and accumulation of lactic acid and a fall in cell-sap pH. After removing CN– a growth burst occurs. (iii) Higher concentrations of permeable acids (10 mM in buffer pH 5.8) induce extension growth. This growth is O2-dependent and therefore differs from the acid growth, which can be triggered under anaerobic conditions by acid buffers of pH5 via the direct increase of cell-wall plasticity. (iv) A short application of CO2-saturated buffer (pH 5.8) causes CO2-induced elongation growth; after a 3-min pulse the growth rate is enhanced for about 15 min. (v) Lipophilic esters of acetic acid or propionic acid, such as naphthylacetate, naphthylpropionate, phenylacetate, benzylacetate induce elongation growth. These compounds, when taken up into the cell, are hydrolized by esterases; the acids released lower the cytoplasmic pH (shown by the pH indicator, fluorescein). The highest esterase activity was found in a microsomal membrane fraction of coleoptiles. While the carboxyester-induced extension growth is completely inhibited under anoxia, the initial acidification of the bathing solution can still be observed. This decrease in external pH is obviously the result of ester hydrolysis, caused by damaged cells, and is not the result of pH changes within the cell-wall compartment. It is suggested that a fast uptake of carboxyesters and the shift in equilibrium caused by their internal hydrolysis leads to a continuous formation of acids which lowers the cytoplasmic pH and activates the ATP-dependent H+ extrusion. In most experiments fusicoccin (a diacetic acid ester) acts similarly to naphthylacetate and the other carboxyesters, although quantitative differences exist. Therefore, it is possible that fusicoccin is effective partly on the basis of its ester characteristic. The effects observed are discussed with regard to the very narrow pH optimum of plasma-membrane H+-ATPases exhibiting their highest levels of activity at pH 6.5 (Hager and Biber 1984, Z. Naturforsch. C 39, 927–937).Abbreviations CHM
cycloheximide
- DMO
dimethadione (5.5-dimethyl-2,4-oxazolidinedione)
- FC
fusicoccin
- IAA
indole-3-acetic acid
- Mes
2-(N-morpholino)ethanesulfonic acid
- NA
(or )-naphthylacetate (acetic acid-1(or-2-)naphthylester)
- NAA
(or )-naphthaleneacetic acid
- PA
phenylacetate (acetic acid phenylester) 相似文献
8.
Ilse B. Barthelmess 《Molecular & general genetics : MGG》1984,194(1-2):318-321
Summary A lethal allele at the putative regulatory locus, cpc-1, of cross-pathway control in Neurospora crassa was discovered by genetic analysis. cpc-1
j-5 is viable only in the presence of a second mutation, slo, causing slow growth. The detection of a lethal allele at a regulatory locus is a rare event and points to the physiological importance of the regulatory circuit concerned, namely the cross-pathway or general control of amino acid biosynthetic enzymes in lower eukaryotes. 相似文献
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Zusammenfassung Am Beispiel der Larven von Chironomus thummi piger werden die Zellen, die die peritrophische Membran abscheiden, licht- und elektronenmikroskopisch untersucht. Es liegen zwei Zelltypen vor, die einerseits durch ihren Reichtum an granulären E.R.-Schläuchen (ER-Zellen), andererseits durch ihren hohen Gehalt an Mitochondrien (M-Zellen) charakterisiert sind. Die ER-Zellen zeigen Veränderungen, die in vielerlei Hinsicht der klassischen Auffassung der apokrinen Sekretion entsprechen und sich nicht in ein modernes Schema der Sekretionsmorphologie einordnen lassen. Die Zellen gehen im Verlauf der Sekretabgabe weder völlig zugrunde, noch bleiben sie vollständig erhalten. Die M-Zellen, die im Gegensatz zu den ER-Zellen keine Sekretionsgranula besitzen, weisen ähnliche Umwandlungen auf. Das fertige Sekretionsprodukt — die peritrophische Membran — entstammt einmal vorgeformten Sekretionsgranula, zum anderen der umgewandelten, abgeschnürten oberen Zellhälfte. Die peritrophische Membran besteht aus zwei Schichten, wovon die lumenseitige, auf Längsschnitten quergestreifte Lage (Wabentextur) vermutlich aus den Sekretionsgranula hervorgeht und die andere längsgefaserte Lage auf die Umwandlung von Zytoplasma zurückzuführen sein dürfte. Die Mikrovilli der Sekretionszellen sind in keiner Weise für die Strukturierung der Wabentextur verantwortlich.
On the apocrine secretion in the formation of the peritrophic membrane of chironomus thummi piger Str
Summary Taking the larvae of Chironomus thummi piger as an example, the cells secreting the peritrophic membrane have been investigated with the light- and electron-microscope. Two cell-types can be distinguished which in one case are characterized by abundant rough E.R.-tubules (ER-cells) and in the other case by large quantities of mitochondria (M-cells). The ER-cells undergo changes which in many respects correspond to the individual stages of the classic apocrine secretion, and thus do not fit into a modern scheme of the morphology of secretion. In the course of the discharge of the secretory product the cell neither becomes completely necrotic nor remains totally intact. The M-cells, which do not contain secretion granules like the ER-cells, show similar changes. The final product — the peritrophic membrane — is formed on the one hand by membrane bound secretion granules and on the other hand by the transformed and pinched off upper half of the cell. The peritrophic membrane consists of two layers, the one of which, facing the lumen of the midgut and exhibiting a honey-comb-texture, presumably is formed by the secretion granules, whereas the other layer arises from transformed cytoplasm. The microvilli of the secretory cells are not responsible for the formation of the honey-comb-pattern.
Die Untersuchungen wurden mit Unterstützung durch die Max-Planck-Gesellschaft und die Deutsche Forschungsgemeinschaft durchgeführt. 相似文献