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The endoplasmic reticulum (ER), called "the mother of all
membranes," is spotlighted in this timely new book. The work
presented here is especially exciting since GFP-technology has
provided new ways of looking at the dynamics of the ER and its
relationship to other organelles, particularly the Golgi apparatus
and peroxisomes. This book provides in-depth knowledge of the ER
and the diverse roles it plays, for instance, in protein
trafficking, homeostasis of cellular calcium, plant hormone and
lipid synthesis. These manifold activities are reflected in the
great plasticity of the ER as a structure, with more than a dozen
specialized domains recognized for this organelle.
A personal invitation to walk with God through one of the great
classics of Christian spirituality. This book of daily devotions is
based upon The Cloud of Unknowing. In this edition Robinson sought
to remain as true as possible to the voice of this medieval
classic. Cloud Devotion follows the original Middle English text
sentence by sentence, with Robinson's own translation and
paraphrase, divided work into 366 small portions, with a Scripture
passage related to the theme from each daily reading. "My heart has
yearned for this book. I wanted a guide to help me savor and
reflect on the spiritual classic The Cloud of Unknowing. David has
insightfully discerned how we might do this. The partnership of
this unknown, ancient writer and this known, living pastor is
masterful. I invite you into the clouds with the slow reading of
this book." -Dr. MaryKate Morse, author and mentor-professor of
formation and leadership
Algae have become the favoured object for a whole range of studies
in various areas of biology. This first volume in the new series
Experimental Phycology comprises 16 contributions presented at the
Gottingen algal symposium in September 1989. The articles are
centered around several major themes of current interest to
algologists and cell biologists. Topics reviewed cover: - "cell
walls and " "surfaces" cellulose biosynthesis, scale structures,
algal symbionts in ciliates and lichens, cell wall autolysins,
marine biofouling, - "reproduction" cell differentiation in
"Volvox," the polyspermy block, mitosis in diatoms, nuclear
behaviour and cytokinesis in green algae, - "algal evolution"
ribosomal RNA sequences, chloroplast evolution, and -
"photosynthesis: " phycobilisomes, chlororespiration, thylakoid
architecture, electron transfer."
In 1939, when the electron optics laboratory of Siemens &
Halske Inc. began to manufacture the first electron microscopes,
the biological and medical profes sions had an unexpected
instrument at their disposal which exceeded the reso lution of the
light microscope by more than a hundredfold. The immediate and
broad application of this new tool was complicated by the
overwhelming prob lems inherent in specimen preparation for the
investigation of cellular struc tures. The microtechniques applied
in light microscopy were no longer appli cable, since even the
thinnest paraffin layers could not be penetrated by electrons. Many
competent biological and medical research workers expressed their
anxiety that objects in high vacuum would be modified due to
complete dehydration and the absorbed electron energy would
eventually cause degrada tion to rudimentary carbon backbones. It
also seemed questionable as to whether it would be possible to
prepare thin sections of approximately 0. 5 11m from heterogeneous
biological specimens. Thus one was suddenly in posses sion of a
completely unique instrument which, when compared with the light
microscope, allowed a 10-100-fold higher resolution, yet a suitable
preparation methodology was lacking. This sceptical attitude
towards the application of electron microscopy in bi ology and
medicine was supported simultaneously by the general opinion of
colloid chemists, who postulated that in the submicroscopic region
of living structures no stable building blocks existed which could
be revealed with this apparatus."
Als im Jahre 1939 in Berlin im Laboratorium fur Elektronenoptik der
Siemens & Halske AG die ersten Elektronenmikroskope
serienmassig fabriziert wurden, stan- den den Biologen und
Medizinern unerwartet Gerate zur Verfugung, welche das
Aufloesungsvermoegen der Lichtmikroskope um das 100fache
ubertrafen. Der sofor- tigen und breiten Anwendung dieses neuen
Verfahrens in der Erforschung der zel- lularen Strukturen standen
aber fast unuberwindliche praparative Schwierigkeiten im Wege. Die
bisher in der Lichtmikroskopie verwendete Mikrotechnik konnte nicht
ubernommen werden, weil selbst die feinsten Paraffinschnitte von
den Elek- tronen nicht durchstrahlt werden konnten. Viele damals
kompetente Biologen und Mediziner ausserten auch die Befurchtung,
dass die im Hochvakuum befindlichen Objekte durch die vollstandige
Entwasserung verandert und schliesslich durch die absorbierte
Elektronenenergie bis zu einem rudimentaren Kohlenstoffskelett
abge- baut werden wurden. Es schien auch zweifelhaft, ob es
gelingen wurde, Dunn- schnitte in der Groessenordnung von 0,5 j. Lm
aus den heterogen zusammengesetzten biologischen Praparaten
herzustellen. Man besass ploetzlich ein voellig neuartiges In-
strument, das gegenuber dem Lichtmikroskop eine um zwei
Zehnerpotenzen hoehe- re Aufloesung ermoeglichte, aber keine dafur
geeignete Praparationstechnik I Diese skeptische Einstellung zur
Anwendung des Elektronenmikroskopes in der Biologie und Medizin
wurde gleichzeitig auch durch die Lehrmeinung der damals aktuellen
Kolloidchemie unterstutzt, in der postuliert wurde, dass es im
amikrosko- pischen Bereich der lebenden Strukturen keine stabilen
Bauelemente gebe, die man mit diesem Gerat abbilden koennte. Man
stellte sich damals das Cytoplasma, die Kernmatrix, den Inhalt der
Mitochondrien und Plastiden als ein amorphes, homo- genes Gelgerust
ohne definierte Strukturhierarchie vor.
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