Electron microscopic study of the influence of fullerene on the formation of amyloid fibrils by A beta(25-35) peptide

The anti-amyloidogenic capacity of hydrated fullerene C60 HyFn was revealed by the use of electron microscopy. We first showed that when, connecting with growing amyloid fibrils formed by A beta(25-35)-peptide, fullerene prevented their subsequent growth and interfered with the formation of new fibrils. Instead of long helically twisted ribbons formed by A beta(25-35)-peptide in the absence of fullerene, short narrow protofibrils were found in the presence of fullerene . These results allow one to suppose that fullerene can be useful for the therapy of Alzheimer's disease.     

Community structure of the epipelagic zooplankton community under the sea-ice of the northern Weddell Sea

Summary The present paper describes the composition, abundance, biomass and diversity of the meso- and macrozooplankton in the epipelagic zone of the open water and under the ice of the northern Weddell Sea. Samples were collected in October/November 1988 with a multiple RMT1+8 net during the European Polarstern Study (EPOS). Multivariate analysis resulted in two distinct site clusters, a northern one mainly located in the open water/marginal ice zone and a southern one extending from the marginal ice zone into the consolidated pack-ice. Clusters were, however, faunistically coherent with a high degree in positive covariation of species. There was no basis for the separation into communities, but differences occurred on the population level in numerical abundances, biomass (wet weight) and in a shift in species dominance. Different ice zones and vertical layers were tested among each other with regard to their relative species abundance. Significant differences were found between the upper 60 m layer of the open sea, the upper 60 m layer of the closed pack-ice and the so called transitional zone. Species richness and diversity was lowest directly under the closed pack-ice. Abundance and biomass was highest in the surface layer of the open water, while both variablès decreased dramatically under the ice. Copepods dominated numerically in open water, while salps dominated in biomass. Euphausia superba and Thysanoessa macrura were the dominant species in the upper water column of the closed pack-ice zone. Krill was the only species with increasing abundance in the sub-ice area and a dominance in biomass of more than 91% demonstrated its unique importance for the sub-ice habitat.Data presented here were collected during the European Polarstern Study (EPOS) sponsored by the European Science Foundation     

古尔班通古特沙漠南缘草本层对积雪变化的响应

草本层是古尔班通古特沙漠植物群落下层层片的构建者, 冬季积雪提供了其生长发育所需要的主要水分, 积雪的增加或减少对草本植物数量和生物量会产生显著的影响。该研究利用人工增减积雪的方法, 在古尔班通古特沙漠南缘设置了5个不同厚度的积雪处理: 0积雪、50%积雪、100%积雪、150%积雪和200%积雪, 其中100%积雪为自然积雪。采用1 m × 1 m的样方, 对草本层片的物种数、盖度、密度、高度进行了调查, 还采用收获法测定了草本层片的地上生物量和优势种小花荆芥(Nepeta micrantha)的单株地上生物量。对研究区内13个科29种草本植物的研究表明: 1)单位面积出土幼苗数量跟积雪厚度呈显著正相关关系, 草本层片的盖度、密度对积雪的变化响应显著, 随着积雪增加, 草本层片的密度和盖度呈递增趋势, 而草本层片的平均高度呈递减趋势, 但不同积雪处理间的物种数和总地上生物量没有显著差异; 2)积雪厚度与优势种的株高和地上生物量呈显著负相关关系, 积雪的增加导致优势种的单株生物量和株高显著降低; 3)积雪厚度的变化主要影响了草本层片植物种子萌发的数量, 但对物种数量没有显著影响。这表明: 虽然积雪是草本植物的主要水分来源之一, 但荒漠植物群落的草本植物对积雪的变化具有很强的缓冲能力, 即使积雪很少, 草本层片的物种构成也不会发生显著变化, 草本层片的净初级生产力也保持相对稳定。     

Structure and elasticity of desmin protofibrils explored with scanning force microscopy

Desmin filaments form the intermediate filament system of muscle cells where they play important role in maintaining mechanical integrity and elasticity. Although the importance of desmin elasticity and assembly-disassembly dynamics in cellular mechanics is being increasingly recognized, the molecular basis of neither desmin's elasticity nor its disassembly pathway is well understood. In the present work, we explored the topographical structure of purified and reconstituted desmin filaments by using scanning force microscopy. With the addition of divalent cation chelators ethyleneglycoltetraacetic acid or ethylenediaminetetraacetic acid, the filaments disassembled on a time scale of hours to days into stable, thin fibrillar components with variable (up to micrometer) length, smooth surface and uniform thickness, which are identified as protofibrils. Desmin protofibrils appear as elastic structures with a persistence length of 51.5 nm, and their Young's modulus (10.6 MPa) far exceeds that of the mature filament (3.7 MPa). Protofibrillar bundling within the desmin filament results in high longitudinal tensile strength at a large bending flexibility. The stability of protofibrils suggests that desmin may disassemble along a pathway quite distinct from its assembly.     

Biotic Assemblages and Ecological Controls on Reefs and Banks of the Northwest Gulf of Mexico

This paper summarizes the results of investigations of the ecologyof reefs and banks in the northwestern Gulf of Mexico. Nearshoresurface waters are turbid out to approximately the 10 m isobath.A turbid nepheloid layer up to 20 m in thickness exists beyondthis depth. Seasonal temperature and salinity variability ishigh in nearshore waters. At the shelf edge, the temperatureto 50 m depth remains above 19°C. Topographic prominencesare common in the region. Most are surface expressions of thediapirism of underlying salt domes derived from deeply buriedJurassic salt deposits. Biotic zonation on the banks is primarilydepth related. Zones of major reef-building include the Diploria-Montastrea-Porites Zone (15–36 m), the Madracis Zone (28–46m), the Stephanocoenia-Millepora Zone (36–52 m), and theAlgal-Sponge Zone (45–98 m). A zone of minor reefbuildingon some banks is the Millepora Zone (18–52 m). An AntipatharianTransitional Zone exists from 56 to over 100 m on some banks.The Nepheloid Zone near the base of the banks is a zone of noreef-building. Not all zones are present on all banks. The communitystructure and depths of these zones depend on and are modifiedby the regional current regime, depth of the bank crests, substratecharacteristics, winter temperature minima, river influences,and the relative depth and thickness of the nepheloid layer.Nearshore communities are warm temperate in nature, though tropicalorganisms are occasionally abundant. Progressing offshore, thebenthos becomes increasingly tropical. The northerly locationand isolated nature of the Flower Gardens have lead to reducedcommunity diversity (e.g., only 18 of the 55 Western Atlantichermatypic coral species exist), but not reduced abundancesor growth rates of the species present. Assemblages on otherbanks exist below the tolerance limits of thriving tropicalreefs due to their frequent immersion in turbid water, excessivecrest depths, or lower minimum winter temperatures.     

Rauber's sickle and not the caudal marginal zone induces a primitive streak, blood vessels, blood cell formation and coelomic vesicles in avian blastoderms

By using the quail-chicken chimera technique, we studied the reactivity and the eventual developmental or inducing capacities of the avian caudal marginal zone (in comparison with Rauber's sickle), when associated in vitro with different avian blastoderm components. If a fragment of quail sickle endoblast is placed on the caudal marginal zone of a whole unincubated chicken blastoderm, then a secondary miniature embryo will develop in this caudal marginal zone. The primitive streak and accompanying neural plate of the secondary embryo are directed peripherally into the caudal germ wall, away from Rauber's sickle. Thus, the 'mirror image development' indicates that the upper layer of the caudal marginal zone can react in the same way as the upper layer of the area centralis, because of the presence of sickle endoblast. A quail Rauber's sickle fragment placed on an isolated anti-sickle region always induces a primitive streak directed centrally. After prolonged culture, blood vessels and associated coelomic vesicles are formed. By contrast if a quail caudal marginal zone is placed on an isolated chicken anti-sickle region, the primitive streak, blood vessels and coelomic vesicles do not form. Thus, in contrast to the inducing effect of Rauber's sickle, the caudal marginal zone has no inducing effect by itself, even in the absence of the dominating effect of Rauber's sickle.     

Thickness and elasticity of gram-negative murein sacculi measured by atomic force microscopy

Atomic force microscopy was used to measure the thickness of air-dried, collapsed murein sacculi from Escherichia coli K-12 and Pseudomonas aeruginosa PAO1. Air-dried sacculi from E. coli had a thickness of 3.0 nm, whereas those from P. aeruginosa were 1.5 nm thick. When rehydrated, the sacculi of both bacteria swelled to double their anhydrous thickness. Computer simulation of a section of a model single-layer peptidoglycan network in an aqueous solution with a Debye shielding length of 0.3 nm gave a mass distribution full width at half height of 2.4 nm, in essential agreement with these results. When E. coli sacculi were suspended over a narrow groove that had been etched into a silicon surface and the tip of the atomic force microscope used to depress and stretch the peptidoglycan, an elastic modulus of 2.5 x 10(7) N/m(2) was determined for hydrated sacculi; they were perfectly elastic, springing back to their original position when the tip was removed. Dried sacculi were more rigid with a modulus of 3 x 10(8) to 4 x 10(8) N/m(2) and at times could be broken by the atomic force microscope tip. Sacculi aligned over the groove with their long axis at right angles to the channel axis were more deformable than those with their long axis parallel to the groove axis, as would be expected if the peptidoglycan strands in the sacculus were oriented at right angles to the long cell axis of this gram-negative rod. Polar caps were not found to be more rigid structures but collapsed to the same thickness as the cylindrical portions of the sacculi. The elasticity of intact E. coli sacculi is such that, if the peptidoglycan strands are aligned in unison, the interstrand spacing should increase by 12% with every 1 atm increase in (turgor) pressure. Assuming an unstressed hydrated interstrand spacing of 1.3 nm (R. E. Burge, A. G. Fowler, and D. A. Reaveley, J. Mol. Biol. 117:927-953, 1977) and an internal turgor pressure of 3 to 5 atm (or 304 to 507 kPa) (A. L. Koch, Adv. Microbial Physiol. 24:301-366, 1983), the natural interstrand spacing in cells would be 1.6 to 2.0 nm. Clearly, if large macromolecules of a diameter greater than these spacings are secreted through this layer, the local ordering of the peptidoglycan must somehow be disrupted.     

Regeneration of the goldfish retina after exposure to different doses of ouabain

Summary After ouabain-induced degeneration, the retina of the goldfish shows a remarkable regeneration capacity. The extent of the damage depends on the dose of ouabain used in the experiment. After intraocular injection of 7l 10^–5 M ouabain, the ganglion cells and the cells of the inner nuclear layer (INL) become necrotic except for most of the outer horizontal cells, some bipolar cells, and Müller cells. The outer nuclear layer (ONL) and the marginal growth zone at the ora serrata remain intact; the plexiform layers become spongy. The degenerated material is removed by the proliferated reactive macroglial cells and invading macrophages. The degenerated cellular elements of the retina are replaced by mitosis of neuroblasts in the marginal growth zone and of cells in the ONL.After intraocular injection of a 5-fold higher dose of ouabain (7 l 5·10^–5M), the degeneration of the retina proceeds more rapidly and completely. In this experiment, the ONL is destroyed and the receptor outer segments are phagocytosed by cells of the pigment epithelium. In contrast to the regeneration of the amphibian retina, in the goldfish cells of the pigment epithelium do not participate by metaplastic transformation in the regeneration of the retina. The only source of cellular regeneration of the retina after complete destruction of its differentiated neural elements is the marginal growth zone, which is highly resistant to ouabain. The rate of mitoses in this region is strongly increased. The derivatives of these cells spread out tangentially over the entire fundus of the eye in a concentric manner. In this regenerate, mitotic processes continue in a radial direction, resulting in thickening and layering of the new retinal formation.     

Lungs of Polypterus and Erpetoichthys

The wall of the asymmetrical saclike lungs of the fishes Polypterus and Erpetoichthys consists of several functionally different tissue layers. Their lumen is lined by a surface epithelium composed of (1) highly attenuated cells, termed pneumocytes I; (2) pneumocytes II with lamellar bodies, presumably indicating surfactant production; (3) mucous cells; and (4) ciliated cells. Underlying the pneumocytes I is a dense capillary net. The thin continuous endothelium of this net, together with the pneumocytes I, constitute the very thin blood-air barrier. The basement membrane of epithelium and endothelium fuse in the area of the blood-air barrier (thickness 210 m?m). Secretory and ciliary cells form longitudinal rows in the epithelium. Below the zone with a gas-exchanging tissue, a layer of connective tissue containing collagen and special elastic fibers occurs. The blood vessels that give rise to or drain the superficial capillary plexus are located in this connective tissue. The outermost layer of the lung consists of muscle cells, a narrow inner zone with smooth muscle cells, and an outer, broader zone with cross-striated muscle cells. The lung is innervated by myelinated and nonmyelinated nerve fibers. The morphology of the gas-exchange tissue in the lungs of these primitive bony fish is fundamentally very similar to that of the lungs of tetrapod vertebrates. The morphologic observations are in close agreement with physiologic data, disclosing well-developed respiratory capacities. Structural simplicity can be regarded as a model from which the lungs of the higher vertebrates derived. In addition to respiratory function, the lungs seem also to have hydrostatic tasks.     

Growth of beta-amyloid(1-40) protofibrils by monomer elongation and lateral association. Characterization of distinct products by light scattering and atomic force microscopy

Amyloid plaques in brain tissue are a hallmark of Alzheimer's disease. Primary components of these plaques are 40- and 42-residue peptides, denoted A beta(1-40) and A beta(1-42), that are derived by proteolysis of cellular amyloid precursor protein. Synthetic A beta(1-40) and A beta(1-42) form amyloid fibrils in vitro that share many features with the amyloid in plaques. Soluble intermediates in A beta fibrillogenesis, termed protofibrils, have been identified previously, and here we describe the in vitro formation and isolation of A beta(1-40) protofibrils by size exclusion chromatography. In some experiments, the A beta(1-40) was radiomethylated to better quantify various A beta species. Mechanistic studies clarified two separate modes of protofibril growth, elongation by monomer deposition and protofibril-protofibril association, that could be resolved by varying the NaCl concentration. Small isolated protofibrils in dilute Tris-HCl buffers were directed along the elongation pathway by addition of A beta(1-40) monomer or along the association pathway by addition of NaCl. Multi-angle light scattering analysis revealed that protofibrils with initial molecular masses M(w) of (7-30) x 10(3) kDa grew to M(w) values of up to 250 x 10(3) kDa by these two growth processes. However, the mass per unit length of the associated protofibrils was about 2-3 times that of the elongated protofibrils. Rate constants for further elongation by monomer deposition with the elongated, associated, and initial protofibril pools were identical when equal number concentrations of original protofibrils were compared, indicating that the original number of protofibril ends had not been altered by the elongation or association processes. Atomic force microscopy revealed heterogeneous initial protofibrils that became more rodlike following the elongation reaction. Our data indicate that protofibril elongation in the absence of NaCl results from monomer deposition only at the ends of protofibrils and proceeds without an increase in protofibril diameter. In contrast, protofibril association occurs in the absence of monomer when NaCl is introduced, but this association involves lateral interactions that result in a relatively disordered fibril structure.     

Fluoroalcohol-induced modulation of the pathway of amyloid protofibril formation by barstar

To understand how the conformational heterogeneity of protofibrils formed by any protein, as well as the mechanisms of their formation, are modulated by a change in aggregation conditions, we studied the formation of amyloid protofibrils by barstar at low pH by multiple structural probes in the presence of hexafluoroisopropanol (HFIP). In the presence of 10% HFIP, aggregation proceeds with the transient formation of spherical oligomers and leads to the formation of both protofibrils and fibrils. Curly short protofibrils and fibrils are seen to form early during the aggregation reaction, and both are seen to grow gradually in length during the course of the reaction. Atomic force microscopy images reveal that the HFIP-induced protofibrils are long (～300 nm in length), curly, and beaded and appear to be composed primarily of β-sheet bilayers, with heights of ～2.4 nm. The protofibrils formed in the presence of HFIP differ in both their structures and their stabilities from the protofibrils formed either in the absence of alcohol or in the presence of a related alcohol, trifluoroethanol (TFE). Aggregation appears to proceed via an isodesmic polymerization mechanism. Internal structure in the growing aggregates changes in two stages during protofibril formation. In the first stage, an α-helix-rich oligomeric intermediate is formed. In the second stage, the level of β-sheet structure increases at the expense of some α-helical structure. The second stage itself appears to occur in two distinct steps. The creation of thioflavin T binding sites occurs concomitantly with aggregate elongation and is seen to precede the change in secondary structure. The long straight fibrils with characteristic heights of 8-10 nm, which form in the course of the HFIP-induced aggregation reaction, have not been observed to form either in the absence of alcohol or in the presence of TFE.     

Self‐assembly of regenerated silk fibroin from random coil nanostructures to antiparallel β‐sheet nanostructures

In this work, we studied the effects of incubation concentration and time on the self‐assembly behaviors of regenerated silk fibroin (RSF). Our results showed the assembly ways of RSF were concentration‐dependent and there were four self‐assembly ways of RSF: (i) At relatively low concentration (≤0.015%), RSF molecules assembled into protofilaments (random coil), and then the thickness decreased and the secondary conformation changed to antiparallel β‐sheet; (ii) at the concentration of 0.015%, RSF molecules assembled into protofilaments (random coil), and then assembled into protofibrils (antiparallel β‐sheet). The protofibrils experienced the appearance and disappearance of phase periodic intervals in turn; (iii) at the concentration of 0.03%, RSF molecules assembled into bead‐like oligomers (random coil), and then assembled into protofibrils (antiparallel β‐sheet), and finally the height and phase periodic intervals of RSF protofibrils disappeared in turn; and (iv) at the relatively high concentration (≥0.15%), RSF molecules assembled into protofilaments (random coil), then aggregated into blurry cuboid‐like micelles (random coil), and finally self‐arranged to form smooth and clear cuboid‐like micelles (antiparallel β‐sheet). These results provide useful insights into the process by which the RSF molecules self‐assemble into protofilaments, protofibrils and micelles. Furthermore, our work will be beneficial to basic understanding of the nanoscale structure formations in different silk‐based biomaterials. © 2014 Wiley Periodicals, Inc. Biopolymers 101: 1181–1192, 2014.     

Development of β-sheet structure in Aβ aggregation intermediates diminishes exposed hydrophobic surface area and enhances proinflammatory activity

Three decades of research, both in vitro and in vivo, have demonstrated the conformational heterogeneity that is displayed by the amyloid β peptide (Aβ) in Alzheimer's disease (AD). Understanding the distinct properties between Aβ conformations and how conformation may impact cellular activity remain open questions, yet still continue to provide new insights into protein misfolding and aggregation. In particular, there is interest in the group of soluble oligomeric prefibrillar Aβ species comprising lower molecular weight oligomers up to larger protofibrils. In the current study, a number of strategies were utilized to separate Aβ protofibrils and oligomers and show that the smaller Aβ oligomers have a much different conformation than Aβ protofibrils. The differences were consistent for both Aβ40 and Aβ42. Protofibrils bound thioflavin T to a greater extent than oligomers, and were highly enriched in β-sheet secondary structure. Aβ oligomers possessed a more open structure with significant solvent exposure of hydrophobic domains as determined by tryptophan fluorescence and bis-ANS binding, respectively. The protofibril-selective antibody AbSL readily discerned conformational differences between protofibrils and oligomers. The more developed structure for Aβ protofibrils ultimately proved critical for provoking the release of tumor necrosis factor α from microglial cells. The findings demonstrated a dependency on β-sheet structure for soluble Aβ aggregates to cause a microglial inflammatory response. The Aβ aggregation process yields many conformationally-varied species with different levels of β-structure and exposed hydrophobicity. The conformation elements likely determine biological activity and pathogenicity.     

Research on the early stages of spore germination in Bacillus subtilis using dynamic phase microscopy

The changes in the state of Bacillus subtilis spores that occur during germination were analyzed using dynamic phase microscopy (DPM). DPM is based on monitoring and analyzing the interference image of a specimen in a coherent laser beam. The optical path difference (the phase thickness of the specimen, PT) depends on the geometrical height of the specimen and its refractive index. We demonstrated that the maximum PT value is a convenient criterion of the physiological state of the organism involved: PT is > or = 80 nm, 40-50 nm, and < or = 0 in dormant, developing (initiated), and heat-killed spores, respectively. We established that (i) heating a spore suspension to 40 degrees C results in a reversible twofold decrease (from 80 to 40 nm) in their PT under conditions that do not promote the development of the bacteria; this decrease is irreversible under growth-promoting conditions; (ii) the PT values of germinating spores oscillate with a considerable fluctuation amplitude (up to 7 nm), in contrast to the limited fluctuation amplitude (within 1 nm) in dormant spores; (iii) activated spores were heterogenous with respect to the PT pattern: a majority of the spores exhibited a usual spatial profile (with a maximum thickness in the center), whereas a minor fraction of them were characterized by an erythrocyte-like profile with a concave center; this implies that the central zone of the spore was more rapidly hydrated (with a decrease in refractive index) than the peripheral zone.     

In Vitro Study of α-Synuclein Protofibrils by Cryo-EM Suggests a Cu-Dependent Aggregation Pathway

The aggregation of α-synuclein is thought to play a role in the death of dopamine neurons in Parkinson’s disease (PD). Alpha-synuclein transitions itself through an aggregation pathway consisting of pathogenic species referred to as protofibrils (or oligomer), which ultimately convert to mature fibrils. The structural heterogeneity and instability of protofibrils has significantly impeded advance related to the understanding of their structural characteristics and the amyloid aggregation mystery. Here, we report, to our knowledge for the first time, on α-synuclein protofibril structural characteristics with cryo-electron microscopy. Statistical analysis of annular protofibrils revealed a constant wall thickness as a common feature. The visualization of the assembly steps enabled us to propose a novel, to our knowledge, mechanisms for α-synuclein aggregation involving ring-opening and protofibril-protofibril interaction events. The ion channel-like protofibrils and their membrane permeability have also been found in other amyloid diseases, suggesting a common molecular mechanism of pathological aggregation. Our direct visualization of the aggregation pathway of α-synuclein opens up fresh opportunities to advance the understanding of protein aggregation mechanisms relevant to many amyloid diseases. In turn, this information would enable the development of additional therapeutic strategies aimed at suppressing toxic protofibrils of amyloid proteins involved in neurological disorders.     

Prenatal ontogenesis of the human brain cortex temporal area

Prenatal ontogenesis of temporal areas of the human cortex was studied. In the fetal cortex at the gestational age of 16-18 weeks three zones can be distinguished: marginal zone (eI layer), cortex plate and subplate. At 20-26 weeks cortex plate is divided into following layers: eII, eIII, eIV, eV and eVI, with "efferent" complex of layers being wider than "associative" one. The subplate neurons are eliminated in the fetus at 27-33 weeks, when "associative" complex composes over 50 per cent of the cortex thickness. The subplate has been identified by positive correlation between layer eII and the upper subplate layer spu cell density.     

Alpha-synuclein,especially the Parkinson's disease-associated mutants,forms pore-like annular and tubular protofibrils

Two mutations in the alpha-synuclein gene (A30P and A53T) have been linked to autosomal dominant early-onset Parkinson's disease (PD). Both mutations promote the formation of transient protofibrils (prefibrillar oligomers), suggesting that protofibrils are linked to cytotoxicity. In this work, the effect of these mutations on the structure of alpha-synuclein oligomers was investigated using electron microscopy and digital image processing. The PD-linked mutations (A30P and A53T) were observed to affect both the morphology and the size distribution of alpha-synuclein protofibrils (measured by analytical ultracentrifugation and scanning transmission electron microscopy). The A30P variant was observed to promote the formation of annular, pore-like protofibrils, whereas A53T promotes formation of annular and tubular protofibrillar structures. Wild-type alpha-synuclein also formed annular protofibrils, but only after extended incubation. The formation of pore-like oligomeric structures may explain the membrane permeabilization activity of alpha-synuclein protofibrils. These structures may contribute to the pathogenesis of PD.     

Research on the early stages of spore germination in <Emphasis Type="Italic">Bacillus licheniformis</Emphasis> using dynamic phase microscopy

The changes in the state of Bacillus subtilis spores that occur during germination were analyzed using dynamic phase microscopy (DPM). DPM is based on monitoring and analyzing the interference image of a specimen in a coherent laser beam. The optical path difference (the phase thickness of the specimen, PT) depends on the geometrical height of the specimen and its refractive index. We demonstrated that the maximum PT value is a convenient criterion of the physiological state of the organism involved: PT is ≥ 80 nm, ～40–50 nm, and ≤ 20 in dormant, developing (initiated), and heat-killed spores, respectively. We established that (i) heating a spore suspension to 40°C results in a reversible twofold decrease (from 80 to 40 nm) in their PT under conditions that do not promote the development of the bacteria; this decrease is irreversible under growth-promoting conditions; (ii) the PT values of germinating spores oscillate with a considerable fluctuation amplitude (up to 7 nm), in contrast to the limited fluctuation amplitude (within 1 nm) in dormant spores; (iii) activated spores were heterogenous with respect to the PT pattern: a majority of the spores exhibited a usual spatial profile (with a maximum thickness in the center), whereas a minor fraction of them were characterized by an erythrocyte-like profile with a concave center; this implies that the central zone of the spore was more rapidly hydrated (with a decrease in refractive index) than the peripheral zone.     

Subsurface near‐infrared laser stimulation of the periprostatic cavernous nerves

Successful identification and preservation of the cavernous nerves (CN), which are responsible for sexual function and vulnerable to damage during prostate cancer surgery, will require subsurface detection of the CN's beneath a thin fascia layer. This study explores the feasibility of optical nerve stimulation (ONS) in the rat with a fascia layer placed over the CN. Two near‐infrared diode lasers with wavelengths of 1455 and 1550 nm were operated in continuous‐wave mode for stimulation of the CN in 8 rats, in vivo. Successful ONS was confirmed by an intracavernous pressure (ICP) response in the rat penis at 1455 nm through fascia with a thickness up to 110 μm and at 1550 nm through fascia with a thickness up to 450 μm. Higher incident laser power was required to produce an ICP response as fascia thickness was increased. Also, weaker and slower ICP responses were observed as fascia thickness was increased. Subsurface ONS of the rat CN at a depth of 450 μm using a 1550 nm laser is feasible as an intermediate step towards developing ONS as an intra‐operative diagnostic tool for identification and preservation of the cavernous nerves during prostate cancer surgery. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)