Biology Commons^™

Seed Coat Structure In Some Species Of Trigonella, Mohini Gupta

Scanning Microscopy

Seed coats of nine species of Trigonella, members of Trifolieae, were studied using light and scanning electron microscopy to assess seed coat characters taxonomically. In all species, the testa is of the papillose type except T. geminiflora in which it is of the multi-reticulate type. Based on some of the seed characters such as their shape, size, surface, position of hilum and the features of papillae, a key has been developed to identify different species of this genus. Further, in a highly evolved group like section Bucerates, it has been found that the surface is either papillose without …

Influence Of Ageing, Ph And Various Additives On Crystal Formation In Artificial Urine, A. L. Rodgers, M. A. E. Wandt

Scanning Microscopy

In order to investigate the effect of various factors on urinary crystallization processes, a series of five experiments was carried out using an artificial urine (AU) in a rotary evaporator. The influence of ageing, pH and organic, inorganic and potential inhibitory additives formed the basis of the study. Precipitates were characterized by X-ray powder diffraction, scanning electron microscopy and energy dispersive X-ray analysis. In the ageing experiment, AU aliquots, adjusted to various pH values, were allowed to stand for several days and were not evaporated. Calcium oxalate monohydrate (COM) was formed at low pH, while whitlockite, apatite and struvite occurred …

Digitized Cathodoluminescence Imaging Of Minerals, Ian M. Steele

Scanning Microscopy

Digital imaging with cathodoluminescence (CL) capability, provides an additional, quantitative imaging perspective. While CL images can be useful by themselves, most microbeam instruments allow simultaneous acquisition of other signals including backscattered electron (BSE), secondary electron (SE), and X-ray images providing a powerful set of data for interpretation. Digital panchromatic images allow the use of standard and advanced image processing now available on laboratory computers to enhance single images or provide a means of combining information from two or more images. Other advantages of digital CL images include: 1) selective scan rates to avoid image distortion; 2) adjustable dwell times at …

High-Resolution, Real-Space Imaging Of Conformational Structures Of Poly-L-Proline Helixes, N. J. Zheng, G. Rau, C. F. Hazlewood, C. Rau

Scanning Microscopy

In 1954, Edsall postulated that the imino-acid proline, which is a frequently found constituent of protein molecules, is a key determinant to the three-dimensional architecture of proteins. It not only should play a fundamental role in stabilizing helical structures of polypeptides, it should allow for sharp bends and even for a complete reversal of the direction of a helix looping back on itself. No direct evidence has yet been published to prove this prediction. Using scanning tunneling microscopy, we have presented high-resolution, real-space images of two conformations of poly-L-proline, where one structure clearly exhibits the predicted 180° back-folding behavior. The …

Localisation Of Putative Mechanoelectrical Transducer Channels In Cochlear Hair Cells By Immunoelectron Microscopy, Carole M. Hackney, David N. Furness, Dale J. Benos

Scanning Microscopy

Displacement of the apical stereociliary bundle of cochlear hair cells mechanically gates transducer channels. Knowing the position of the channels with regard to the apical structures of the hair cell could indicate how this mechanism operates. At present, there is conflicting evidence regarding their precise location; the channels have been suggested to be located either towards the base of the stereocilia or at the tips where they could be operated by extracellular links running from the top of shorter stereocilia to the sides of adjacent taller ones. The channels have been shown to be reversibly blocked by amiloride. This has …

Terminal Differentiation Of Human Fibroblasts Is Induced By Radiation, H. Peter Rodemann, Hans-Peter Peterson, Karla Schwenke, K. -Hartmut Von Wangenheim

Scanning Microscopy

In order to analyze the effect of various kinds of radiation on the terminal differentiation processes of fibroblasts in culture, both human skin and lung fibroblasts were irradiated with electromagnetic non ionizing as well as ionizing radiation in clonal and sparse mass culture systems. As analyzed by cell biological (cell type frequencies), biochemical (collagen synthesis) and molecular markers (expression of protein PIVa) human skin and lung fibroblasts are induced to differentiate prematurely into terminal postmitotic cells. Thus, both electromagnetic and ionizing radiation induce terminal differentiation in cultured cells. These data add some new aspects for the interpretation of radiation effects …

Effect Of A Platinum Chemotherapy Drug On Intracellular Elements During The Cell Cycle, Using X-Ray Microanalysis, P. G. Edwards, M. D. Kendall, I. W. Morris

Scanning Microscopy

Intracellular elemental concentrations were measured in the cytoplasm, nucleus and nucleolus of cultured Chinese hamster ovary (CHO) cells, using energy dispersive electron probe X-ray microanalysis and transmission electron microscopy. Synchronous CHO cell populations were analyzed at different times during the growth cycle. The elements K, P, Mg and Zn were all more concentrated in the nucleus and nucleolus than in the cytoplasm, while no specific subcellular compartmentalization was evident for the elements Na, Cl, Ca, Fe and S. Significant changes in intracellular elemental concentrations were associated with the progression of cells from G₁ phase to S phase of the …

Band Positions Used For On-Line Crystallographic Orientation Determination From Electron Back Scattering Patterns, N. H. Schmidt, J. B. Bilde-Sørensen, D. Juul Jensen

Scanning Microscopy

A computer procedure for on-line analysis of electron back scattering patterns (EBSP) has been developed. An experimental EBSP is computer recorded and displayed on a computer monitor. The user identifies the positions of at least two bands in the EBSP with a cursor. Based on this input the computer calculates possible crystallographic orientations. The corresponding EBSPs are simulated and superimposed on the experimental EBSP. The correct crystallographic orientation is determined from a comparison between the experimental and simulated EBSPs. Typically, the analysis takes a 10-30 seconds per pattern. Advantages with the present procedure are that it can be applied for …

Low Voltage Scanning Electron Microscopy Cathodoluminescence Observations Of Gallium Arsenide, S. Myhajlenko

Scanning Microscopy

A series of low voltage ( < 5 keV) and low temperature ( < 20K) cathodoluminescence (CL) measurements were performed on epitaxial gallium arsenide. The purpose of these measurements was to ascertain which factors were important in furthering the development of low voltage scanning electron microscopy (LVSEM) CL. LVSEM CL potentially offers great improvement in spatial resolution and the ability to probe the optical properties of surface states. Anomalous CL effects resulting from contamination at beam voltages below 3.5 keV have been interpreted in terms of cross-over potential phenomena. Luminescence dead layers were reduced to near zero in this regime. Excitonic processes were found to be particularly sensitive to injection level and surface conditions. Very weak free-to-bound transitions persisted down to 200 eV beam voltage.

The Role Of Tamm-Horsfall Glycoprotein And Nephrocalcin In Calcium Oxalate Monohydrate Crystallization Processes, B. Hess

Scanning Microscopy

Theoretical considerations as well as clinical observations suggest that the aggregation of nucleated crystals is the most dangerous step in the formation of calcium oxalate (CaOx) renal stones. The effects of 2 major urinary glycoproteins, Tamm-Horsfall glycoprotein (THP) and Nephrocalcin (NC), on calcium oxalate monohydrate (COM) crystal aggregation in vitro are studied. At low ionic strength (IS) and high pH (within urinary limits), THP is a powerful crystal aggregation inhibitor (90% inhibition at 40 mg/l). Decreasing pH to 5.7 and raising IS to 0.21 increases THP viscosity, thereby lowering THP crystal aggregation inhibition. Upon addition of calcium …

Prerequisites Of High Resolution Scanning Electron Microscopy, René Hermann, Martin Müller

Scanning Microscopy

Cryotechniques must be employed throughout all preparation and observation steps in order to extract high resolution scanning electron microscopical information from biological material.

Cryoimmobilization, followed by freeze-drying and metal-shadowing at low temperature, yields optimal structural information of T4 polyheads used as a test specimen. Freeze-substitution of frozen T4 polyheads and subsequent freeze-drying renders the substructures recognizable but less crisp than freeze-drying from aequous solutions. Critical point drying of ethanol dehydrated chemically fixed, or freeze-substituted test specimens results in complete loss of discrete polyhead structure.

In-lens field-emission scanning electron microscopes and highly sensitive electron detectors are instrumental prerequisites in achieving transmission …

Beam Sensitivity Of Globoid Crystals Within Seed Protein Bodies And Commercially Prepared Phytates During X-Ray Microanalysis, Irene Ockenden, John N. A. Lott

Scanning Microscopy

Magnesium, potassium, calcium and phosphorus are stored in seed tissues in spherical particles called globoid crystals. The main component of globoid crystals is phytin, a salt of myo-inositol hexaphosphoric acid. Based on chemical similarity, commercially available phytates may be suitable standards for quantitative energy dispersive X-ray (EDX) microanalysis of globoid crystals. The stability of globoid crystals and commercial phytates was different when analyzed under identical conditions. Phytates in globoid crystals from Cucurbita maxima cotyledons, were relatively stable in the electron beam during EDX microanalysis at room temperature, but there was a loss of potassium. No loss of potassium occurred during …

The Vestibular Epithelia In Experimental Hydrops, K. C. Horner, S. Rydmarker

Scanning Microscopy

Morpho-pathological features, observed by scanning electron microscopy, in guinea pigs with endolymphatic hydrops of 4-14 months included shortening of the hair cell tufts, loss of tufts, retraction of sensory hair cells away from the surrounding tissue and hair cell loss. After 22 months of hydrops, there was complete loss of hair cells with indifferentiation of the epithelium. The loss of ciliary tufts involved loss of both stereocilia and kinocilia identified as short stubs and holes respectively. Control macular epithelia showed no hair tuft loss although ampullae in control ears could show some loss.

Retention Of Calcium Oxalate Crystals In Renal Tubules, Saeed R. Khan, Raymond L. Hackett

Scanning Microscopy

Crystal retention within the renal tubules is essential for nephrolithiasis and the development of urinary stone disease. We studied the mechanisms involved in this process by inducing calcium oxalate crystal deposition within the rat renal tubules and examining them using various microscopic techniques. Crystals appeared to be retained either by attachment to the tubular epithelium or by aggregating with other crystals thus becoming large enough to be retained by their collective size.

Morphological Study Of Calcospherites In Rat And Rabbit Incisor Dentin, H. Mishima, T. Sakae, Y. Kozawa

Scanning Microscopy

Calcospherites from incisors of rats and rabbits were studied, by means of secondary and backscattered electron images, using scanning electron microscopy. Part of each incisor specimen was made anorganic to allow observation of the surface of the mineralization front by scanning electron microscopy; the other part was ground on one side for observation by scanning electron microscopy with a backscattered electron image detector. In both species the labial mineralization front was wavy and the image showed fused calcospherites, whereas the lingual mineralization front appeared to consist of a combination of linear and globular forms. In rat labial dentin the calcospherites …

Seed Coat Surface Patterns And Structures Of Oxytropis Riparia, Oxytropis Campestris, Medicago Sativa, And Astragalus Cicer, D. J. Solum, R. H. Lockerman

Scanning Microscopy

Scanning electron microscopy was used to examine external and internal seed coat structures of Oxytropis riparia Litv., Oxytropis campestris L., Medicago sativa L., and Astragalus cicer L. for characteristics useful in taxonomic classification and to identify hard seed coat components which affect permeability. Seed coat surfaces of the four species were distinctly different. Palisade and hourglass cell lengths and parenchyma and endosperm cell layer thicknesses were similar among species with the exception of O. campestris seeds which lacked an identifiable endosperm layer. Surface pattern differences and the presence of a distinct endosperm layer are useful in separating these genera and …

Scanning Electron Microscopy Of Corrosion Casting In Medicine, M. A. Konerding

Scanning Microscopy

The aims of this review are: 1. to provide a bibliography of the publications that have used the corrosion casting technique; 2. to describe the advantages and limitations of the methodology; 3. to illustrate possible applications in the field of medicine, and 4. to highlight the significance of this method in the teaching of medical students. Thus, this paper is primarily focused on the scanning electron microscopical examination of vascular corrosion casts.

The unsurpassed three-dimensionality of the corrosion casting technique compared to any other means stands out in particular. This can be especially useful when complex vascular-anatomical relationships are present. …

A Technique For Correlative Scanning And Transmission Electron Microscopy Of Individual Human Placental Villi: An Example Demonstrating Syncytial Sprouts In Early Gestation, G. J. Burton, K. W. Thurley, J. N. Skepper

Scanning Microscopy

Correlating the surface appearances of certain features with their internal structure is made particularly difficult in the human placenta by the complex three-dimensional branching pattern of the villous tree. This places a possible limitation on the use of the scanning electron microscope in this field, both for basic research purposes and as a tool in pathological diagnosis. To help overcome this problem, a technique for handling individual placental villi has been devised. By attaching single villi to glass pipette tips it has proved possible to scan the villi, embed them in resin and then section them in a known pre-determined …

Preparation Of Inner Ear Sensory Hair Bundles For High Resolution Scanning Electron Microscopy, M. P. Osborne, S. D. Comis

Scanning Microscopy

Chemical fixation techniques for preservation of sensory hair bundles in the mammalian inner ear for scanning electron microscopy (SEM) are reviewed. Fixatives employed were glutaraldehyde, glutaraldehyde-picrate, glutaraldehyde-tannic acid, glutaraldehyde-formaldehyde, glutaraldehyde followed by postfixation with osmium tetroxide and the osmium thiocarbohydrazide (OTOTO) method. Dehydration was routinely accomplished with ascending grades of acetone followed by critical point drying with liquid CO₂ or fluorocarbon sublimation. Specimens other than those prepared by the OTOTO method were metal coated with gold, gold-palladium or platinum. Material was viewed at high resolution (2-3 nm) in a transmission electron microscope (TEM) fitted with a scanning system and …

Thin Sectioning Of Carbonaceous Adsorbent Spheres For Visualization By Light Microscopy And Scanning Electron Microscopy, Samuel H. Cohen, Ronald A. Segars

Scanning Microscopy

Three different types of Rohm and Haas carbonaceous adsorbent spheres (XE-340, XE-347 and XE-348) were prepared for light and scanning electron microscopy by embedding in resin and by thin sectioning. Spurr's low viscosity resin, because of its penetrating and wetting ability, contributed to the production of the most uniform and artifact free thin sections. In addition to thin sectioning, gas adsorption surface area measurements were made on batches of each type of sphere.

There was an apparent relationship between the surface area measurements of 417.8 m²/g for XE-340, 583.4 m²/g for XE-347 and 752.9 m^{2 …}

Scanning Electron Microscopic Analysis Of Dental Wear On The Heavily Worn Second Molars Of The Wild Japanese Monkey (Macaca Fuscata), Teruyuki Hojo

Scanning Microscopy

Microscopic features on scanning electron micro-graphs of epoxy-replicas of the second molars of nine wild-caught adult female Japanese monkeys, Macaca fuscata, from Oita Takasakiyama, Kyushu, were measured using a digitizer. These monkeys had been fed a monkey-diet during three or four days of captivity before replicas were made. Six of these specimens showed such heavily worn second molars that narrow peripheral enamel bands surrounded large dentin exposures and the cusps of the others had been worn off. Microwear measurements from sites near facet 9 were compared with those of facet 9 of three kinds of hard-object feeding primates from …

Elemental Mapping Of Cryosections From Cnidarian Nematocytes, Karl Zierold, Pierre Tardent, Sergey V. Buravkov

Scanning Microscopy

The distribution of elements in stinging capsules containing cells called nematocytes is shown by pseudocoloured maps representing the X-ray intensity collected from freeze-dried cryosections. This method provides a distinct overview in addition to the quantitative evaluation of single X-ray spectra. Selected examples illustrate the elemental compartmentation in various cnidarian animals. In particular the matrix of capsules in Hydra vulgaris contains high amounts of K in comparison to the tubule, the surrounding capsule wall and the cytoplasm, whereas in Actinia eguina capsules have either high concentration of Ca or Mg, the latter accompanied by S.

Backscattered Electron Imaging For High Resolution Surface Scanning Electron Microscopy With A New Type Yag-Detector, Paul Walther, Rudolf Autrata, Ya Chen, James B. Pawley

Scanning Microscopy

Double Layer Coating for backscattered electron imaging is a coating and imaging method especially suitable for high resolution scanning electron microscopy (SEM) of large biological samples. Since the backscattered electron (BSE) signal from thin metal coating layers is quite low, field emission SEM's and very sensitive BSE-detectors are required for this method. In this study an improved BSE-detector of the YAG type was used with an in-lens type field emission SEM. Two samples were investigated in order to demonstrate and to improve the potential of this new approach: (1) cryo-prepared cultured kidney cells were shadowed by electron beam evaporation with …

The Study Of The Surface Geometry Of Renal Stone Fragments After Shock Wave And Ultrasound Disintegration, Roch Thibert, Rashad Tawashi

Scanning Microscopy

Computerized image analysis was used for characterizing the irregular boundaries of calcium oxalate stone fragments resulting from shock wave and ultrasound disintegration. The complexity of the contour of the fragments was determined to evaluate the surface roughness of the rugged profile of the samples. Crack propagation on the crystal surface of the mineral phase was studied using fractal geometry. A significant difference was observed in the boundary variation of the calcium oxalate stone fragments treated by shock wave and ultrasound. Crack propagation in the mineral phase crystal was found to depend on the method of fragmentation used. There is also …

Scanning Tunneling Microscopy Imaging Of Synthetic Oligonucleotides And Oligonucleotide-Metal Complexes, Yun Kim, Charles M. Lieber

Scanning Microscopy

Scanning tunneling microscopy (STM) has been used to image 12-and 24-base pair (bp) synthetic oligonucleotide duplexes alone or with intercalatively-bound metal complexes with submolecular resolution. The sizes of the 12-and 24-bp oligonucleotides determined from STM images are close to expected values, and images of isolated duplexes resolve the two nucleotide strands of these molecules. The variation of duplex size in our images demonstrates that these features are not due to surface artifacts. In addition, images of the 12-bp duplex in the presence of bis(9, 10-phenanthrenequinone diimine)(2, 2'-bipyridyl) rhodium(III) exhibit a new structural feature at 14 ± 2 Å from the …

Error Voltage Components In Quantitative Voltage Contrast Measurement Systems, D. S. H. Chan, T. S. Low, J. C. H. Phang

Scanning Microscopy

This paper presents the results of computer simulation studies into the respective contributions of the potential barrier, the off-normal incidence injection of secondary electrons (SEs) into the retarding field and analyser geometry on Types I and II local field error voltages for a practical 20 mm wide planar retarding field energy analyser. Results show that the error voltage component due to the off-normal incidence injection effect of SEs into the retarding field dominates the Type I local field error. For type II LFE, the error voltage component due to analyser geometry effect is the higher contributing factor. The presence of …

Factors Affecting Seeds In A Sagebrush-Steppe Ecosystem And Implications For The Dispersion Of An Annual Plant Species, Cheatgrass (Bromus Tectorum L.), Michael Ira Kelrick

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

I investigated how shrub-induced spatial heterogeneity influenced and was manifested by a representative ground-story plant species at a sagebrush-steppe site in southwestern Wyoming. The dispersion of cheatgrass (Bromus tectorum) reflected differences between undershrub (higher plant densities) and interspace (between shrubs, supporting lower densities) microenvironments, hence the population ecology of this annual species served as a biological probe of shrub-associated patch structure in this community. Since cheatgrass is an annual, factors affecting the seed portion of its life cycle were of special interest. First, attributes of the above- and below-ground seed pool were characterized. The environment-wide seed depositional pattern …

Reproductive Strategies Of Northern Goshawks And Cooper's Hawks In North-Central New Mexico, Patricia L. Kennedy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

I assumed that the reproductive strategies of the two Accipiter species investigated in this study, the northern Goshawk (A. gentilis) and the Cooper's hawk (A. cooperii), would be similar to the strategies of other monogamous raptors with sex role partitioning. Any differences in the species' reproductive strategies, particularly hunting strategies, were expected to be a function of their size differences. Contrary to predictions, results indicated that, in north-central New Mexico during brood rearing, both species had similar hunting strategies and utilized similar prey species. These results also indicated that the reproductive strategies of the Cooper's hawk …

Study Of Ferredoxin And Flavodoxin From Tobacco Leaves And Roots Under Normal And Iron-Stressed Conditions, I-Jen Huang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

I purified tobacco leaf ferredoxin from normal and iron-stressed leaves. The oxidized form of ferredoxin from normal leaves had absorption maxima at 268, 327, and 422 nm and a shoulder at 463 nm. The oxidized form of ferredoxin from iron-stressed leaves had absorption maxima at 268 and 329 nm but no absorption maxima in the 400-nm range. Higher ferredoxin content was found with higher chlorophyll content in leaves of the same age.

A protein in tobacco root extract was isolated and found to serve as an electron carrier for ferredoxin-requiring nitrite reduction. This protein had a molecular weight and antigenic …

The Hepatic Microcirculation In Experimental Cirrhosis A Scanning Electron Microscopy Study Of Microcorrosion Casts, E. Gaudio, L. Pannarale, M. Ripani, P. Onori, O. Riggio

Scanning Microscopy

The experimental model of liver cirrhosis induced by intragastric administration of CCl₄ reproduces not only the histological picture of the postnecrotic cirrhosis but also its pathophysiological features.

Corrosion casts of livers affected by CCl₄-induced cirrhosis show the loss of the lobular pattern. Once the cirrhosis has completely developed, the whole microvascular bed appears to be composed of groups of sinusoid nodules of diameters varying between 0.3 and 1.5 mm.. Pre- and post-sinusoidal vessels and anastomoses between the former and the latter are mainly located at the perinodular spaces.

This microvascular situation modifies the normal perfusion gradient within …