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Registration fees, sponsoring societies, registration, cancellation
policy, commercial exhibits, important events during the meeting, pre-meeting
events, MSA Center, business and committee meetings, awards, future
Microscopy and Microanalysis meetings, and poster instructions.
Mouse oocyte microfilaments (MF) were perturbed by depolymerization
(cytochalasin B) or stabilization (jasplakinolide) and correlated
meiotic defects examined by confocal microscopy. MF, microtubules, and
mitochondria were vitally stained; centrosomes (γ-tubulin), after
fixation. MF depolymerization by cytochalasin in culture medium did not
affect central migration of centrosomes, mitochondria, or nuclear
breakdown (GVBD); some MF signal was localized around the germinal
vesicle (GV). In maturation-blocking medium (containing IBMX), central
movement was curtailed and cortical MF aggregations made the plasma
membrane wavy. Occasional long MF suggested that not all MF were
depolymerized. MF stabilization by jasplakinolide led to MF
aggregations throughout the cytoplasm. GVBD occurred (unless IBMX was
present) but no spindle formed. Over time, most oocytes constricted
creating a dumbbell shape with MF concentrated under one-half of the
oocyte cortex and on either side of the constriction. In IBMX medium,
the MF-containing half of the dumbbell over time sequestered the GV,
MF, mitochondria, and one to two large cortical centrosomes; the non-MF
half appeared empty. Cumulus processes contacted the oocyte surface
(detected by microtubule content) and mirrored MF distribution. Results
demonstrated that MF play an essential role in meiosis, primarily
through cortically mediated events, including centrosome localization,
spindle (or GV) movement to the periphery, activation of (polar body)
constriction, and establishment of oocyte polarity. The presence of a
cortical “organizing pole” is hypothesized.
Advances in Ultrastructural Studies at Low Temperatures for Cryo TEM and SEM
Progress in structural biology very much depends upon the development
of new high-resolution techniques and tools. Despite decades of study of
viruses, bacteria and bacterial spores and their pressing importance in
human medicine and biodefense, many of their structural properties are
poorly understood. Thus, characterization and understanding of the
architecture of protein surface and internal structures of pathogens is
critical to elucidating mechanisms of disease, immune response,
physicochemical properties, environmental resistance and development of
countermeasures against bioterrorist agents. Furthermore, even though
complete genome sequences are available for various pathogens, the
structure-function relationships are not understood. Because of their
lack of symmetry and heterogeneity, large human pathogens are often
refractory to X-ray crystallographic analysis or reconstruction by
cryo-electron microscopy (cryo-EM). An alternative high-resolution
method to examine native structure of pathogens is atomic force
microscopy (AFM), which allows direct visualization of macromolecular
assemblies at near-molecular resolution. The capability to image single
pathogen surfaces at nanometer scale in vitro would profoundly impact
mechanistic and structural studies of Progress in structural biology
very much depends upon the development of new high-resolution techniques
and tools. Despite decades of study of viruses, bacteria and bacterial
spores and their pressing importance in human medicine and biodefense,
many of their structural properties are poorly understood. Thus,
characterization and understanding of the architecture of protein
surface and internal structures of pathogens is critical to elucidating
mechanisms of disease, immune response, physicochemical properties,
environmental resistance and development of countermeasures against
bioterrorist agents. Furthermore, even though complete genome sequences
are available for various pathogens, the structure-function
relationships are not understood. Because of their lack of symmetry and
heterogeneity, large human pathogens are often refractory to X-ray
crystallographic analysis or reconstruction by cryo-electron microscopy
(cryo-EM). An alternative high-resolution method to examine native
structure of pathogens is atomic force microscopy (AFM), which allows
direct visualization of macromolecular assemblies at near-molecular
resolution. The capability to image single pathogen surfaces at
nanometer scale in vitro would profoundly impact mechanistic and
structural studies of pathogenesis, immunobiology, specific cellular
processes, environmental dynamics and biotransformation.
The M&M 2005 meeting will begin on Saturday, July 30, with a
pre-meeting congress entitled “Biophotonics and Live Cell
Imaging.” The pre-meeting congress will continue on Sunday along
with a number of topical Short Courses addressing digital imaging,
image analysis and specimen preparation. Examples of biological topics
that will be addressed during the week of the meeting include Tracking
and Tagging of Stem Cells, Use of Green and Other Fluorescent Proteins,
Cell Communication and Pathology, and the use of microscopy in the
study of Viruses, Infectious Diseases and Their Associated Pathologies.
Topical symposia in the physical sciences will examine the role of
microscopy and microanalysis in the study of Extraterrestrial
Materials, Catalysts, and Metallographic Techniques, Applications and
Failure Analysis. In joint sessions for biological and materials
scientists, several symposia will address the development and imaging
of a variety of Nanoparticles, Biopolymers and Biomembranes.
Instrumentation and Techniques Development sessions will also address a
number of state-of the-art instruments and techniques including
Aberration Corrected Electron Microscopy, ESEM, FIB, Advanced
Detectors, Spectral Imaging Techniques, FRET, and Tomography. Of
special interest will be the Presidential Symposium, “The Golden
Anniversary of Imaging Atoms” commemorating the 50th anniversary
of the first atomic images using field-ion microscopy, which will
provide keynote addresses concerning the historical and advanced
technology that has grown from the first application of atomic imaging.
This year we will also have a series of topical sessions organized by
the Focused Interest Groups of MSA. Supplementing the topical sessions
will be a number of Tutorials and Ask the-Experts sessions that will
provide the opportunity to learn the basics behind many popular
techniques. As always, the commercial exhibits will provide the unique
opportunity for hands-on learning with the largest variety of
state-of-the-art instrumentation found at any microscopy meeting
worldwide. The poster sessions will again provide the best venue for
discussions and exchange of scientific information. To facilitate
communication, we have made arrangements to have appropriate kegs of
beverages available on the exhibit floor during the 3:30–5:00 PM
afternoon poster sessions. To promote this interaction, posters should
be put up Monday morning and not removed until after the Wednesday
afternoon Poster Session ends. It is the sincere hope of the Executive
Program Committee that the Scientific Program will be of interest to
all microscopists in the Pacific Rim countries. We look forward to
meeting and interacting with as many of you as possible in Hawaii.
The gap junction (GJ) is an aggregate of intercellular channels that
facilitates cytoplasmic interchange of ions, second messengers, and other
molecules of less than 1000 Da between cells. In excitable organs such as
heart and brain, GJs configure extended intercellular pathways for stable
and long-term propagation of action potential. In a previous study in
adult rat heart, we have shown that the Drosophila disks-large related
protein ZO-1 shows low to moderate colocalization at myocyte borders with
the GJ protein Cx43. In the present study, we detail a protocol for
characterizing the pattern and level of colocalization of ZO-1 with Cx43
in cultures of neonatal myocytes at the level of individual GJ plaques.
The data indicate that ZO-1 shows on average a partial 26.6% overlap
(SD = 11.3%) with Cx43 GJ plaques. There is a strong positive
correlation between GJ plaque size and area of ZO-1 colocalization,
indicating that the level of associated ZO-1 scales with the area of the
GJ plaque. Qualitatively, the most prominent colocalization occurs at the
plaque perimeter. These studies may provide insight into the presently
unknown biological function of ZO-1 interaction with Cx43.
Advances in Ultrastructural Studies at Low Temperatures for Cryo TEM and SEM
Spores of the biocontrol agent, Streptomyces
melanosporofaciens EF-76, were entrapped by complex coacervation
in beads composed of a macromolecular complex (MC) of chitosan and
polyphosphate. A proportion of spores entrapped in beads survived the
entrapment procedure as shown by treating spores from chitosan beads
with a dye allowing the differentiation of live and dead cells. The
spore-loaded chitosan beads could be digested by a chitosanase,
suggesting that, once introduced in soil, the beads would be degraded
to release the biocontrol agent. Spore-loaded beads were examined by
optical and scanning electron microscopy because the release of the
biological agent depends on the spore distribution in the chitosan
beads. The microscopic examination revealed that the beads had a porous
surface and contained a network of inner microfibrils. Spores were
entrapped in both the chitosan microfibrils and the bead lacuna.
This work demonstrates the possibility of using the Duane–Hunt
limit of the bremsstrahlung to determine E2 values
of Si3N4 and AlN ceramics. The
EDHL versus E0 graph
demonstrates that for conductive materials, the experimental curve is
parallel to the theoretical (EDHL =
E0), but both curves cross in the case of
insulators. The intersection points (E2 value), are
3.01 keV for Si3N4 and 2.67 keV for AlN. Imaging
of ceramic grain structure at high magnification was performed to
demonstrate the validity of the calculated E2
values.
Physical, chemical, and isotopic analyses of individual radioactive
and other particles in the micron-size range, key tools in environmental
research and in nuclear forensics, require the ability to precisely
relocate particles of interest (POIs) in the secondary ion mass
spectrometer (SIMS) or in another instrument, after having been located,
identified, and characterized in the scanning electron microscope (SEM).
This article describes the implementation, testing, and evaluation of the
triangulation POIs re-location method, based on microscopic reference
marks imprinted on or attached to the sample holder, serving as an
inherent coordinate system. In SEM-to-SEM and SEM-to-SIMS experiments
re-location precision better than 10 μm and 20 μm, respectively,
is readily attainable for instruments using standard specimen stages. The
method is fast, easy to apply, and facilitates repeated analyses of
individual particles in different instruments and laboratories.
Papers from the European Microbeam Analysis Society Regional
Workshop in Bled, Slovenia
The surfaces of crystalline samples of 3d-metals (Mn, Fe, Co, Ni, and
Cu) and their stoichiometric oxides have been studied by Auger
spectroscopy. A correlation between the change in the LVV (L-inner
level-valence-valence electron transition) Auger intensities and the
change of the squares of the corresponding atomic-magnetic moments has
been observed. This is because of the complicated nature of the Auger
process. That is, the Auger electron emission is a result of the inner
atomic level excitation by electron impact and Auger annihilation of the
inner-level hole. Therefore, the Auger process has been considered a
second-order process, and spin polarization of the valence states has been
taken into account for the LMM (L-inner level-M-inner level-M-inner level
electron transition) Auger spectra of 3d-metals.
Special Issue: Frontiers of Electron Microscopy in Materials
Science
Analytical transmission electron microscopy (TEM) and scanning
electron microscopy (SEM) have been applied for the characterization of
evolution, lateral arrangements, orientations, and the microscopic nature
of nanostructures formed during the early stages of ultrahigh vacuum
electron beam evaporation of Cu onto surfaces of VSe2 layered
crystals. Linear nanostructure of relatively large lateral dimension
(100–500 nm) and networks of smaller nanostructures (lateral
dimension: 15–30 nm; mesh sizes: 500–2000 nm) are subsequently
formed on the substrate surfaces. Both types of nanostructures are not Cu
nanowires but are composed of two strands of crystalline substrate
material elevating above the substrate surface. For the large
nanostructures a symmetric roof structure with an inclination angle of
∼30° with respect to the substrate surface could be deduced from
detailed diffraction contrast experiments. In addition to the
nanostructure networks a thin layer of a Cu-VSe2 intercalation
phase of 3R polytype is observed at the substrate surface. A dense network
of interface dislocations indicates that the phase formation is
accompanied by in-plane strain. We present a model that explains the
formation of large and small nanostructures as consequences of compressive
layer strains that are relaxed by the formation of rooflike
nanostructures, finally evolving into the observed networks with
increasing deposition time. The dominating contributions to the
compressive layer strains are considered to be an electronic charge
transfer from the Cu adsorbate to the substrate and the formation of a
Cu-VSe2 intercalation compound in a thin surface layer.
diFiore's Atlas of Histology with Functional
Correlations. Victor P. Eroschenko. Lippincott Williams and Wilkins,
Philadelphia, PA; 10th edition, 2005, 448 pages (Softbound and Software CD
(interactive), $57.95), ISBN 0-7817-5021-0
Histology (or microscopic anatomy) is an important discipline of the
biological sciences that is concerned with the structure of tissues of
organisms. Light microscopy and electron microscopy in conjunction with
various histochemical and immunocytochemical staining techniques are
typically used today by histologists to visualize, describe, and identify
tissues. Histology is a fundamental discipline in the curriculum for
medical, dental, and veterinary students as well as for allied health
students and scholars interested in the field of biomedical research. All
these students need to have a thorough knowledge of the structure and
function of cells, tissues, and organs. Recently, I came across a
histology book (diFiore's Atlas of Histology) that I believe
is worth the investment. This book provides a selection of high-quality,
full-color illustrations of various tissues of the human body and is
supplemented with sections of structural/functional correlations. This
10th edition is unique in that it includes a CD that contains an
interactive electronic version of the histology atlas.
In this article, the secondary electron-emission properties of both
vertically and laterally inhomogeneous samples are discussed. To study the
effect of surface coverage, the total electron-emission yield of tungsten
and niobium samples was measured as a function of primary electron energy
and oxide thickness. A method is suggested to avoid charging difficulties
during AES measurements of samples that consist of both metal and various
insulator parts.
A method for automatic classification of the shape of graphite
particles in cast iron is proposed. In a typical supervised classification
procedure, the standard charts from the ISO-945 standard are used as a
training and validation population. Several shape and size parameters are
described and used as discriminants. A new parameter, the average internal
angle, is proposed and is shown to be relevant for accurate
classification. The ideal parameter sets are determined, leading to
validation success rates above 90%. The classifier is then applied to real
cast iron samples and provides results that are consistent with visual
examination. The method provides classification results per
particle, different from the traditional per field chart
comparison methods. The full procedure can run automatically without user
interference.
Cardiac myocytes and fibroblasts are essential elements of myocardial
tissue structure and function. In vivo, myocytes constitute the
majority of cardiac tissue volume, whereas fibroblasts dominate in
numbers. In vitro, cardiac cell cultures are usually designed to
exclude fibroblasts, which, because of their maintained proliferative
potential, tend to overgrow the myocytes. Recent advances in
microstructuring of cultures and cell growth on elastic membranes have
greatly enhanced in vitro preservation of tissue properties and
offer a novel platform technology for producing more in vivo-like
models of myocardium. We used microfluidic techniques to grow
two-dimensional structured cardiac tissue models, containing both myocytes
and fibroblasts, and characterized cell morphology, distribution, and
coupling using immunohistochemical techniques. In vitro findings
were compared with in vivo ventricular cyto-architecture. Cardiac
myocytes and fibroblasts, cultured on intersecting 30-μm-wide collagen
tracks, acquire an in vivo-like phenotype. Their spatial
arrangement closely resembles that observed in native tissue: Strands of
highly aligned myocytes are surrounded by parallel threads of fibroblasts.
In this in vitro system, fibroblasts form contacts with other
fibroblasts and myocytes, which can support homogeneous and heterogeneous
gap junctional coupling, as observed in vivo. We conclude that
structured cocultures of cardiomyocytes and fibroblasts mimic in
vivo ventricular tissue organization and provide a novel tool for
in vitro research into cardiac electromechanical function.
Formal definitions of nanotechnological devices for drug delivery
typically feature the requirements that the device itself or its
essential components be man-made, and in the 1-1000 nm range in at least
one dimension [1]. The known nanovectors or nanostructures can be filled
with drugs for different therapies and for diagnostical aims. Targeting
moieties can also be attached to their surface. Polymeric nanovectors
are generally made from biodegradable polymers such as polyesters, for
example, poly-e-caprolactone (PCL). The drug delivery system known as
nanocapsules (NCs) can be defined as a complex nanovector that is
composed by a polymeric wall surrounding an oil core, where lipophilic
drugs can be encapsulated. The advantages of NCs compared to other
nanovectors are the high entrapment efficiencies of lipophilic drugs,
low polymer content and low inherent toxicity. On the other hand,
because of its complex blend of components NCs suspension allow several
forms of nanovectors to be present at the same time, such as
nanospheres, liposomes and nanoemulsions [2]. These ‘contaminants’ would
be present in accordance with the type of formulation and method of
preparation. Atomic force microscopy (AFM) has been used as a method for
imaging the surfaces of liposomes [3] and nanospheres [4] allowing
information in nanoscaled dimensions. In the present work, the NCs were
prepared loading two different drugs, the antifungal albaconazole (ABZ),
showing a crystalline drug structure and the antimalarial halofantrine
(Hf) free base, having an amorphous form. These drugs possess high
lipophilic character, which favours the association of the drug with the
oily core, with drug loadings above 94%. Herein we studied the behavior
of ABZ-loaded and Hf-loaded NCs through the AFM technique, searching to
analyze and understand possible alterations induced by the drug
inclusion in these nanostructures.
Off-axis electron holography is used to measure electrostatic
potential profiles across a silicon p-n junction,
which has been prepared for examination in the transmission electron
microscope (TEM) in two different specimen geometries using focused ion
beam (FIB) milling. Results are obtained both from a conventional
unbiased FIB-milled sample and using a novel sample geometry that
allows a reverse bias to be applied to an FIB-milled sample in
situ in the TEM. Computer simulations are fitted to the results to
assess the effect of TEM specimen preparation on the charge density and
the electrostatic potential in the thin sample.