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SOLID POTENTIOMETRIC PH-ELECTRODE
No full textPotentiometric pH-glass electrodes are among the most reliable so far
known. Most remaining disadvantages (e.g. limited operating temperature,
minimum size) stem from their aqueous component (reference buffer). The
purpose of this investigation is therefore to maintain glass as a menbrane
with outstandingly good sensing properties but to replace the
reference buffer, including the Ag/AgCl electrode, by a solid contact
providing a reversible transition from the ionic to the electronic part
of the sensor The problems in making such a contact are discussed in
terms of thermodynamic and kinetic parameters. The properties of glass
electrodes contacted with the materials belonging to the Li, Ag, I
ternary system are presented. They are compared with those of conventional
pH-electrodes and pH-FETs. The advantages arising from the
chemical stability of the contact with the glass membrane are outlined
BIOSPEZIFISCHE ADSORPTION HOCHMOLEKULARER SUBSTANZEN
No full textIn der Biotechnologie gewinnt die Isolierung und Reinigung von Bioprodukten - Downstreamprocessing
genannt - immer mehr an Bedeutung, insbesondere dann, wenn Produkte
höchster Reinheit hergestellt werden müssen. Eine Fermentationslösung enthält in unterschiedlichen
Anteilen eine Vielzahl verschiedenster Substanzen, die sich in der
Ladung, im Molekulargewicht, in der Löslichkeit und in anderen physikalischen und/oder
chemischen Parametern voneinander unterscheiden. Produkte mit deutlich unterschiedlichen
physikalischen und/oder chemischen Eigenschaften lassen sich relativ leicht trennen,
während z. B. die Trennung einander sehr ähnlicher Produkte, wie z. B. Proteine
oder Enzyme, insbesondere Isoenzyme, meistens den Einsatz spezieller Technologien erforderlich
macht. Eine solche Technologie zur Trennung hochmolekularer Substanzen ist
die biospezifische Adsorption
Introduction, Program, List of Participants
No full textThe participants of the very stimulating first symposium on myxobacteria
last year in Cold Spring Harbour pronounced unaminously the opinion that
repeated meetings of this kind would be of great help for their research.
Therefore it was decided to have a second symposium on myxobacteria in
1975 at a place in Germany. This place later turned out to be Braunschweig.
The Gesellschaft fiir Biotechnologische Forschung, one of the Research Centres
of the Federal Government of Germany, was kind enough to be host to the
symposium.
Fortunately again many of the investigators working in the field of myxobacteria
were able to assemble. The many fascinating discussions which
developed in the course of the meeting fully justified all efforts made
in arranging this symposium and encouraged the participants to continue
with this kind of communication.
The booklet presented here gives the summaries of all the lectures and a
record of the technical discussions held at the end of the meeting. It
is intended to pass the information to all those colleagues who were kept
from participating personally in the symposium
CONTROL OF FRUITING BODY DIFFERENTIATION IN CHONDROMYCES APICULATUS BY ENVIRONMENTAL FACTORS
No full textChondromyces apiculatus, strain Cm a2, isolated in Minneapolis from decaying
wood, was grown as a pure culture on yeast agar for years without
ever producing fruiting bodies. When agar blocks with fractions of
the swarm edge were punched from the culture plate and transferred to a
salt solution containing Ca’ and Mg**, well differentiated fruiting
bodies developed. Fruiting body production was found to be under strict
control by a number of environmental factors:
1)The temperature must not exceed 30°C, although good arowth occurs still
several degrees higher.
2) The surface of the agar block must not be submerged under the surface
of the salt solution.
3) The cultures must be illuminated during induction. The quality of the
light has no influence, at least in the visible range, even red light
being fully effective. In red light the fruiting bodies remain pale,however,
because carotenoid synthesis is at dark level under this condition.
Light has to be present during the whole developmental process, as cell
accumulation as well as fruiting body morphogenesis depend on licht.
4) The relative proportion of the Ca** and Mg** concentrations has a
striking effect on the shape of the developing fruiting bodies.
5) Addition of nutrients to the salt solution, e.g. of a little Casitone
solution, suppresses fruiting body formation completely; neither are fruiting
bodies obtained by induction in deionized water. Finally,
6) if the initial population density is too low, no fruiting bodies can
be formed even if all other conditions are right. The induction system
worked out for Cm a2, seems to be specific for this one strain: no fruiting
bodies were obtained under identical conditions with a number of
other strains of Cm. apiculatus, nor with Cm. pediculatus, let alone
myxobacteria of other genera
STUDIES ON FIBRILS PRODUCED BY MYXOCOCCUS XANTHUS
No full text4 - 5 rm diameter fibrils were originally observed in 2% phosphotungstate-
negatively stained, 10* x g supernatant fractions of French Pressure
Cell-disruptedM. xanthus FB vegetative cells. The fibrils are also
present in the periplasmic fraction prepared by osmotic shock; treatment
of cells with pronase (100 jig/ml; 30 min.) prior to osmotic shock increases
the number of fibrils observed. They are also present in 10° Xie
pellets of culture medium in which logarithmic phase cells had been
growing. Aggregates of fibrils are observed in association with gliding
cells on filmed electron microscope grids which have been pressed on the
edges of colonies. Cells of at least one non-motile mutant also produce
these structures.
One hypothesis concerning the nature of the fibrils is that they are
comparable to eukaryotic actin. This was based on their structure and on
the presence of a major protein constituent (molecular weight of approximately
50,000) recovered in a procedure designed to extract actin from
™. xanthus. However, attempts to decorate the fibrils with rabbit heavy
meromyosin have been unsuccessful.
Not all fibrils are sedimented by centrifugation at 150,000 x g for 90
min. Fibrils are restitant to digestion by pronase and by lysozyme;
treatment with sodium dedecyl] sulfate (1 %; 70 3 does not alter their
morphology.
We hypothesize that fibrils, produced by vegetative cells, serve as
tracks on which cells glide. These tracks may account for the phase-bright
trails left by gliders on agar
Biotechnologie und Information : Bedürfnisse aus Forschung und Dokumentation
No full textDas Arbeiten mit dem Fundus der Literatur ist für den Wissenschaftler,
der in einer klassisch definierten Fachdisziplin arbeitet,
eine geregelte Selbstverständlichkeit, wenn auch der Übergang zu
neuen EDV-orientierten Informationsformen und -wegen noch nicht
überall problemlos vollzogen ist.
In einem interdisziplinären Arbeitsfeld wie der Biotechnologie
ergeben sich jedoch nachweislich Probleme:
- Allein auf dem Gebiet der Literatur gibt es keine eindeutige
Zuordnung (im Speichern wie im Suchen) zu einer der Fachdisziplinen
Chemie, Biologie, Medizin, Verfahrenstechnik; um nur die
wichtigsten zu nennen.
- Neben den Literaturdatenbanken sind umfangreiche Faktendatenbanken
zu berücksichtigen, die teilweise erst noch im Entstehen
sind.
- Aufgrund der wirtschaftlichen Bedeutung der Biotechnologie - oder
der Hoffnung darauf - sind wissenschaftliche Informationsquellen
(Nachrichtenblätter) häufig schneller mit einer wichtigen
Neuigkeit "am Markt" als eine typische Zeitschrift. |
Hier einen Weg zu einer schnellen und dabei möglichst vollständigen |
aktuellen Information zu finden, wird auch in Zukunft keine leichte
Aufgabe sein.
Mit ihrem Workshop zum Thema
"Biotechnologie und Information"
möchte die GBF einen Beitrag zur Lésung des Informationsproblems in
Wissenschaft und Industrie leisten. Die Ergebnisse des 1. Workshops
(3./4. Oktober 1985) werden nun mit dieser Schrift allen Teilnehmern
und weiteren Interessenten zugänglich gemacht.
Darüber hinaus wurden konkrete Schritte zur Etablierung des
"Informationsknotens Biotechnologie" in der GBF unternommen in
Verfolgung einer wichtigen Anregung des 1. Workshops.
Mein besonderer Dank gilt allen, die zur Gestaltung und zum Erfolg
des 1. Workshops beigetragen und somit die Grundlage zu dem
2. Workshop geschaffen haben, zu dem wir kürzlich eingeladen haben
TAXONOMIC STUDIES ON HIGH G+C % FLAVOBACTERIA
No full textUsing uv resistance and routine methods for preliminary screening, a total of 94
presumptive high GC % flavobacteria have been isolated from a wide variety of environments.
These isolates, together with 8 high GC % reference cultures, form the
strains being studied. Following detailed morphological, cultural, biochemical and
nutritional studies four major groups have been provisionally delineated: group 1,
oxidase positive and peritrichous (54 isolates); group 2, oxidase positive and nonmotile
(4 isolates); group 3, oxidase negative and peritrichous (7 isolates); group
4, oxidase negative and non-motile (29 isolates)
PRELIMINARY STUDIES OF THE PIGMENTS OF FLAVOBACTERIUM BREVE NCTC 11099 AND FLAVOBACTERIUM ODORATUM NCTC 11036
No full textThe pigments of Flavobacterium breve NCTC 11099 and Flavobacterium odoratum NCTC
11036 are extractable with acetone and each consists of a major constituent and
three or more minor pigments. The electronic absorption spectrum of the major pigment
of each species shows a single maximum absorption and lack of fine structure.
The principal pigment of F. breve shows maximum absorption at 435 nm in diethyl
ether or 442 nm in ethanol. That of F. odoratum occurs at 437 nm in diethyl ether
or 450 nm in ethanol. Each pigment demonstrates an alkaline-catalyzed bathochromic
spectral shift which is completely reversed by acid. F. breve shows a bathochromic
shift of 36 nm and F. odoratum, 28 nm. The pigments are not carotenoid in nature
SULFONOLIPIDS NOVEL IN PROCARYOTES ARE SIGNIFICANT CELLULAR COMPONENTS OF MANY GLIDING BACTERIA
No full textAt least two different sulfonolipids, of chemical structure not heretofore
recognized to occur in procaryotes, have been isolated, characterized and shown to
be present in several genera of non-fruiting gliding bacteria. One of the lipids,
capnine, is 2-amino-3-hydroxy-isoheptadecane-1l-sulfonic acid. Capnine and N-acylcapnine
(the acyl group(s) of which appear to be C-15, C-16, and C-17 3-hydroxy
moieties in the one organism studied) constitute 10% to 20% of the lipids of
Capnocytophaga, Cytophaga, Beggiatoa, Flexibacter, Vitreoscilla and Sporocytophaga,
and up to 3% of the cell dry weight. These quantitatively significant cell
components may represent an important chemotaxonomic marker of non-fruiting gliding
bacteria, for they appear to be absent from the fruiting myxobacters thus far
examined, as they are also from E. coli and other bacteria which are either nonmotile,
or motile as a result of flagellar action. The prospect that they may be
associated with, or responsible for, motility in non-fruiting, gliding bacteria
is raised
BASIC SUGAR DERIVATIVES, TOOLS FOR MAPPING THE ACTIVE SITE OF GLYCOSIDASES AND FOR THE STUDY OF GLYCOPROTEIN BIOSYNTHESIS
No full textMost glycoside hydrolases are strongly inhibited by sugar derivatives
with a basic nitrogen adjacent to their C-1. This is assumed
to be due to the formation of an ion pair at the catalytic site
consisting of the protonated inhibitor and a negatively charged
group essential for catalysis. While glycosylamines and their N-alkylderivatives
are useful for kinetic studies to characterize the active
site with respect to charge distribution, hydrophobic properties and
solvent accessibility,their life-time in aqueous solution is too
short for long term studies. Stable sugar derivatives with suitable
properties are 5-amino-5-deoxyhexopyranoses and 1,5-dideoxy-1,5-imino
hexitols. The basic principle of their synthesis is the oxidation of
a protected furanoid monosaccharide at C-5 and conversion of the
resulting ketone to the epimeric amines by reduction of its oxime.
Deprotection provides the pyranoid sugar derivative with the basic
nitrogen in the ring. In glycoprotein biochemistry these inhibitors
have been used to specifically inhibit the 'trimming' glycosidases
that catalyze essential steps in the conversion of the primary
asparagine linked Gle Man (GlcNAc) unit to complex type or high
mannose type glycans. Interference with these steps is expected to
provide insight into the role of glycan structure in surface expression,
secretion and receptor binding. Another application is the
construction of affinity ligands for the purification of these
enzymes