scholarly journals A "MICROTUBULE" IN A BACTERIUM

1967 ◽  
Vol 32 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Woutera van Iterson ◽  
Judith F. M. Hoeniger ◽  
Eva Nijman van Zanten
Keyword(s):  
Proteus Mirabilis ◽  
Normal Cell ◽  
Osmotic Shock ◽  
Hollow Core ◽  
Cylindrical Wall ◽  
Thin Sections ◽  
Whole Mount ◽  
Potassium Phosphotungstate ◽  
First Time ◽  
Cell Constituent

A study of the anchorage of the flagella in swarmers of Proteus mirabilis led to the incidental observation of microtubules. These microtubules were found in thin sections and in whole mount preparations of cells from which most of the content had been released by osmotic shock before staining negatively with potassium phosphotungstate (PTA). The microtubules are in negatively stained preparations about 200 A wide, i.e. somewhat thicker than the flagella (approximately 130 A). They are thus somewhat thinner than most microtubules recorded for other cells. They are referred to as microtubules because of their smooth cylindrical wall, or cortex, surrounding a hollow core which is readily filled with PTA when stained negatively. Since this is probably the first time that such a structure is described inside a bacterium, we do not know for certain whether it represents a normal cell constituent or an abnormality, for instance of the type of "polysheaths" (16).

scholarly journals Isolation of microtubule coils from normal human platelets

Blood ◽  
1985 ◽  
Vol 65 (4) ◽  
pp. 1028-1032
Author(s):  
JG White ◽  
M Krumwiede
Keyword(s):  
Blood Platelet ◽  
Human Platelets ◽  
Thin Sections ◽  
New Approaches ◽  
Negative Stain ◽  
Activated Platelets ◽  
Whole Mount ◽  
Detergent Extraction ◽  
Normal Human ◽  
First Time

The blood platelet is the only human cell known to have a circumferential band of microtubules. However, the mechanisms involved in assembly of the multi-looped coil, its interaction with the cell membrane to support discoid shape, and constriction into tight rings around centrally concentrated organelles in activated platelets are unknown. Separation of the microtubule rings from intact platelets would permit new approaches to solution of these questions. The present study has used simultaneous detergent extraction and fixation to isolate intact microtubule coils in significant numbers from suspended platelets for the first time. Isolated coils closely resembled the circumferential band observed in thin sections of plastic embedded platelets and in platelets prepared by the negative-stain whole-mount method. Enough microtubule coils could be recovered from suspensions of concentrated platelets to permit counting and quantitation on microscope grids. Results of this study will permit new approaches to clarification of the structural physiology of platelet microtubule coils.

scholarly journals BASAL BODIES OF BACTERIAL FLAGELLA IN PROTEUS MIRABILIS

1966 ◽  
Vol 31 (3) ◽  
pp. 585-602 ◽  
Author(s):  
Woutera van Iterson ◽  
Judith F. M. Hoeniger ◽  
Eva Nijman van Zanten
Keyword(s):  
Proteus Mirabilis ◽  
Cell Walls ◽  
Basal Bodies ◽  
Distilled Water ◽  
Proteus Vulgaris ◽  
Fixation Technique ◽  
Previous Suggestion ◽  
Thin Sections ◽  
Bacterial Flagella ◽  
Whole Mount

Years ago (16, 18, 19), in a study of shadowed preparations of Proteus vulgaris that had been autolyzed in the cold, the observation was made that the flagella arose from basal bodies. However, recently (3, 7, 24, 33) doubt has been cast on the conclusion that the flagella of bacteria emerge from sizable basal bodies. This problem has, therefore, been reinvestigated with actively developing cultures of Proteus mirabilis, the cell walls of which had been expanded slightly by exposure to penicillin. Two techniques were applied: ultramicrotomy, and negative staining of whole mount preparations. This paper deals with the thin sections of bacteria after the usual fixation technique had been altered slightly: the cells were embedded in agar prior to their fixation and further processing. The flagella then remained attached to the cells and were seen to extend between the cell wall and the plasma membrane. Occasionally, the flagella appeared to be anchored in the cell by means of a hook-shaped ending. In sections of cells rich in cytoplasm, the basal bodies are particularly difficult to visualize due to their small size (25 to 45 mµ) and the lack of properties that would enable one to distinguish them from the ribonucleoprotein structures; in addition, their boundary appears to be delicate. However, when the cytoplasm is sparse in the cells, either naturally or as a result of osmotic shocking in distilled water, the flagella can be observed to emerge from rounded structures approximately 25 to 45 mµ wide. Contrary to a previous suggestion (21), the flagella do not terminate in the peripheral sites of reduced tellurite, i.e. the chondrioids. The observations in this part of the study agree with those described in the following paper (15) dealing with negatively stained preparations.

scholarly journals Isolation of microtubule coils from normal human platelets

Blood ◽  
1985 ◽  
Vol 65 (4) ◽  
pp. 1028-1032 ◽  
Author(s):  
JG White ◽  
M Krumwiede
Keyword(s):  
Blood Platelet ◽  
Human Platelets ◽  
Thin Sections ◽  
New Approaches ◽  
Negative Stain ◽  
Activated Platelets ◽  
Whole Mount ◽  
Detergent Extraction ◽  
Normal Human ◽  
First Time

Abstract The blood platelet is the only human cell known to have a circumferential band of microtubules. However, the mechanisms involved in assembly of the multi-looped coil, its interaction with the cell membrane to support discoid shape, and constriction into tight rings around centrally concentrated organelles in activated platelets are unknown. Separation of the microtubule rings from intact platelets would permit new approaches to solution of these questions. The present study has used simultaneous detergent extraction and fixation to isolate intact microtubule coils in significant numbers from suspended platelets for the first time. Isolated coils closely resembled the circumferential band observed in thin sections of plastic embedded platelets and in platelets prepared by the negative-stain whole-mount method. Enough microtubule coils could be recovered from suspensions of concentrated platelets to permit counting and quantitation on microscope grids. Results of this study will permit new approaches to clarification of the structural physiology of platelet microtubule coils.

scholarly journals Observations on early fungal infections with relevance for replant disease in fine roots of the rose rootstock Rosa corymbifera 'Laxa'

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
G. Grunewaldt-Stöcker ◽  
C. Popp ◽  
A. Baumann ◽  
S. Fricke ◽  
M. Menssen ◽  
...  
Keyword(s):  
Fine Roots ◽  
Woody Plant ◽  
Fine Root ◽  
Fungal Infections ◽  
Thin Sections ◽  
Replant Disease ◽  
Pot Trials ◽  
Worldwide Phenomenon ◽  
First Time ◽  
The Rose

AbstractReplant disease is a worldwide phenomenon affecting various woody plant genera and species, especially within the Rosaceae. Compared to decades of intensive studies regarding replant disease of apple (ARD), the replant disease of roses (RRD) has hardly been investigated. The etiology of RRD is also still unclear and a remedy desperately needed. In greenhouse pot trials with seedlings of the RRD-sensitive rootstock Rosa corymbifera ‘Laxa’ cultured in replant disease affected soils from two different locations, early RRD symptom development was studied in fine roots. In microscopic analyses we found similarities to ARD symptoms with regards to structural damages, impairment in the root hair status, and necroses and blackening in the cortex tissue. Examinations of both whole mounts and thin sections of fine root segments revealed frequent conspicuous fungal infections in association with the cellular disorders. Particularly striking were fungal intracellular structures with pathogenic characteristics that are described for the first time. Isolated fungi from these tissue areas were identified by means of ITS primers, and many of them were members of the Nectriaceae. In a next step, 35 of these isolates were subjected to a multi-locus sequence analysis and the results revealed that several genera and species were involved in the development of RRD within a single rose plant. Inoculations with selected single isolates (Rugonectria rugulosa and Ilyonectria robusta) in a Perlite assay confirmed their pathogenic relationship to early necrotic host plant reactions, and symptoms were similar to those exhibited in ARD.

Bronze Age Cremation Cemeteries in the East Midlands

1987 ◽  
Vol 53 (1) ◽  
pp. 187-221 ◽  
Author(s):  
Carol S. M. Allen ◽  
Mary Harman ◽  
Hazel Wheeler
Keyword(s):  
Bronze Age ◽  
Direct Relationship ◽  
Small Cluster ◽  
Linear Arrangement ◽  
Thin Sections ◽  
Probable Function ◽  
East Midlands ◽  
Materials Used ◽  
First Time ◽  
Organic Remains

Two Bronze Age cremation cemeteries excavated between 1968 and 1975 are reported and discussed. At Coneygre Farm, Notts., fifty-one cremations were excavated, thirty-one in pots, six in cists, and fourteen uncontained. Cremations were deposited in a roughly linear arrangement and no barrow was found. At Pasture Lodge Farm, Lincs., twenty-seven pots were found, of which twenty-five had associated cremations, and fifteen further sherds could represent burials. Vessels in this cemetery form a small cluster. Pottery from these two cemeteries is broadly similar to Deverel-Rimbury ware and with vessels from other sites in the region is considered to form an East Midlands group of Bronze Age pottery. Vessels of this type from Frieston and Grantham, Lincs., are illustrated for the first time. Examination of thin sections of the pottery from the two cemeteries suggests that most, although not all, of the materials used could have been found locally. Organic remains found in thin sections provide environmental information. The effect of soils on durability of pots and their probable function is discussed. A direct relationship is noticed for the first time between the age of the cremated individual and the capacity of the pot in which the cremation was deposited.

Membranes in lupin root nodules. II. Preparation and properties of peribacteroid membranes and bacteroid envelope inner membranes from developing lupin nodules

1978 ◽  
Vol 30 (1) ◽  
pp. 151-174
Author(s):  
J.G. Robertson ◽  
M.P. Warburton ◽  
P. Lyttleton ◽  
A.M. Fordyce ◽  
S. Bullivant
Keyword(s):  
Sucrose Gradient ◽  
Phosphotungstic Acid ◽  
Nadh Oxidase ◽  
Osmotic Shock ◽  
Root Nodules ◽  
Freeze Fracture ◽  
Electrophoretic Analysis ◽  
Thin Sections ◽  
Peribacteroid Space ◽  
Gradient Fractionation

Peribacteroid membranes and bacteroid envelope inner membranes have been isolated from developing lupin nodules. Isolation of the peribacteroid membranes was achieved by first preparing membrane-enclosed bacteroids free from other plant organelles or membranes. The peribacteroid membranes were then released by osmotic shock and purified by centrifugation to equilibrium on sucrose gradients. The bacteroids were broken in a pressure cell and the bacteroid envelope inner membranes were isolated using sucrose gradient fractionation of the bacteroid total envelope preparation. The density of the peribacteroid membranes decreased during the period of development of N2-fixation in lupin nodules from 1.148 g/ml for nodules from 12-day plants to 1.137 g/ml for nodules from 18-day plants. The density of the bacteroid envelope inner membranes from nodules from 18-day plants was 1–153 g/ml. The identity and homogeneity of the isolated membranes was established, by comparison with membranes in intact nodules, using phosphotungstic acid and silver staining of thin sections and particle densitites on faces of freeze-fracture replicas of the membranes. Analyses for NADH oxidase and succinate dehydrogenase, spectral analyses and gel-electrophoretic analysis of proteins were also used to characterize the membrane and soluble protein fractions from the nodules. The ratio of lipid to protein was 6.1 for the peribacteroid membranes and 2.5 for the bacteroid envelope inner membranes. Leghaemoglobin was localized in the plant cytoplasm in lupin nodules and not in the peribacteroid space.

scholarly journals Comparative and functional morphology of the mouthparts in larvae of Parasitengona (Acariformes)*

Zoosymposia ◽  
2011 ◽  
Vol 6 (1) ◽  
pp. 14-23 ◽  
Author(s):  
ANDREY B. SHATROV
Keyword(s):  
Functional Morphology ◽  
Ultrastructural Organization ◽  
Functional Specialization ◽  
Evolutionary Trends ◽  
Water Mites ◽  
Dorsal Shield ◽  
Water Mite ◽  
Thin Sections ◽  
Whole Mount

Anatomy and ultrastructural organization of the larval mouthparts in representatives of terrestrial (Trombiculidae parasitizing vertebrates and Microtrombidiidae parasitizing arthropods) as well as aquatic (Pionidae and Hydrodromidae parasitizing arthropods) families from the cohort Parasitengona were studied using whole-mount preparations, semi-thin sections and TEM and SEM methods. In these groups, the organization of the mouth apparatus differs significantly especially with regard to their particular functional specialization and adaptations reflecting evolutionary trends in these groups. In trombiculid larvae, the mouthparts reveal the simplest organization. The gnathosoma is totally free, the infracapitulum and the basal cheliceral segments are short and wide, and the latter are separated from each other. The flexible lateral lips form a temporary sucker, distinguishable when the larva feeds, and the pharynx is totally fused with the bottom of the infracapitulum. In microtrombidiid larvae, the gnathosoma is covered by the arched dorsal shield, the chelicerae are comparatively long and separated, and the lateral lips form a permanent sucker provided with an internal sclerite. Conversely, in water mite larvae, the chelicerae are fused together and either partially (Piona carnea) or totally (Hydrodroma despiciens) free from the overhanging idiosomal fold. The lateral lips are flexible and organized freely, and the pharynx is totally separated from the bottom of the infracapitulum. In general, water mite larvae show significant variations and specializations but at the same time seem to possess the most plesiomorphic characters in organization of the mouth apparatus. The ancestral parasitengone may have given rise to divergent groups of water mites as such, as well as to trombiculids with the secondary simplification of the mouth apparatus and to microtrombidiids with their particular additional adaptations and specialization in organization of the mouthparts.

Muscle and tendon morphogenesis in the avian hind limb

Development ◽  
1998 ◽  
Vol 125 (20) ◽  
pp. 4019-4032 ◽  
Author(s):  
G. Kardon
Keyword(s):  
Hind Limb ◽  
Muscle Development ◽  
Coordinated Development ◽  
Reciprocal Interactions ◽  
Tissue Interactions ◽  
Whole Mount ◽  
Initial Appearance ◽  
First Time ◽  
Ventral Muscle ◽  
And Cartilage

The proper development of the musculoskeletal system in the tetrapod limb requires the coordinated development of muscle, tendon and cartilage. This paper examines the morphogenesis of muscle and tendon in the developing avian hind limb. Based on a developmental series of embryos labeled with myosin and tenascin antibodies in whole mount, an integrative description of the temporal sequence and spatial pattern of muscle and tendon morphogenesis and their relationship to cartilage throughout the chick hind limb is presented for the first time. Anatomically distinct muscles arise by the progressive segregation of muscle: differentiated myotubes first appear as a pair of dorsal and ventral muscle masses; these masses subdivide into dorsal and ventral thigh, shank and foot muscle masses; and finally these six masses segregate into individual muscles. From their initial appearance, most myotubes are precisely oriented and their pattern presages the pattern of future, individual muscles. Anatomically distinct tendons emerge from three tendon primordia associated with the major joints of the limb. Contrary to previous reports, comparison of muscle and tendon reveals that much of their morphogenesis is temporally and spatially closely associated. To test whether reciprocal muscle-tendon interactions are necessary for correct muscle-tendon patterning or whether morphogenesis of each of these tissues is autonomous, two sets of experiments were conducted: (1) tendon development was examined in muscleless limbs produced by coelomic grafting of early limb buds and (2) muscle development was analyzed in limbs where tendon had been surgically altered. These experiments demonstrate that in the avian hind limb the initial morphogenetic events, formation of tendon primordia and initial differentiation of myogenic precursors, occur autonomously with respect to one another. However, later morphogenetic events, such as subdivision of muscle masses and segregation of tendon primordia into individual tendons, do require to various degrees reciprocal interactions between muscle and tendon. The dependence of these later morphogenetic events on tissue interactions differs between different proximodistal regions of the limb.

Biodiversity of the Silurian osteostracans of the East Baltic

2014 ◽  
Vol 105 (2) ◽  
pp. 73-148 ◽  
Author(s):  
T. Märss ◽  
O. Afanassieva ◽  
H. Blom
Keyword(s):  
New Taxa ◽  
Thin Sections ◽  
Histological Characteristics ◽  
First Time ◽  
Drill Cores

ABSTRACTThe sculpture and histology of osteostracan head shields and trunk squamations from the Silurian of Estonia are described, illustrated and used for the identification of disarticulated microremains collected from outcrop sections and numerous drill cores in Estonia and Latvia over the last 40 years. The scattered osteostracan material contains thousands of specimens of scales and shield fragments. The sculpture and histology of species of the previously identified eight genera in the region (Tremataspis, Dartmuthia, Saaremaaspis, Oeselaspis, Aestiaspis, Thyestes, Procephalaspis, Witaaspis) are redescribed, together with Ateleaspis, found in Estonia for the first time. The sculpture on the cornua of several taxa is described for the first time. The new taxa Tremataspis perforata sp. nov., Dartmuthia procera sp. nov., Eldaaspis miklii gen. et sp. nov., Tahulaspis ordinata gen. et sp. nov., Tahulaspis praevia gen. et sp. nov., Meelaidaspis gennadii gen. et sp. nov. and Ohesaareaspis ponticulata gen. et sp. nov. are established, based upon sculpture and histological characteristics of the exoskeleton. The supraoral field with denticles of that field are described for the first time in Oeselaspis pustulata, as is the supraoral plate with buccal denticles in Meelaidaspis gennadii gen. et sp. nov. Thin sections of all taxa (except of Witaaspis) have been studied. This work sheds light on East Baltic osteostracan biodiversity from the Maasi Beds of the Jaagarahu Stage, Sheinwoodian, lower Wenlock up to the Ohesaare Stage, upper Přidoli, Silurian.

5 PARTHENOGENETIC EMBRYONIC STEM CELLS ARE CONNECTED BY FUNCTIONAL INTERCELLULAR BRIDGES

2012 ◽  
Vol 24 (1) ◽  
pp. 114
Author(s):  
G. Pennarossa ◽  
G. Tettamanti ◽  
F. Gandolfi ◽  
M. deEguileor ◽  
T. A. L. Brevini
Keyword(s):  
Electron Microscopy ◽  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Normal Cell ◽  
Embryonic Stem ◽  
Osmic Acid ◽  
Self Renewal ◽  
Thin Sections ◽  
Intercellular Bridges ◽  
Cell Functions

We previously reported that parthenogenetic stem cells display abnormal centrosome and spindle formation that results in severe chromosome missegregation, with a high incidence of hypoploid karyotypes. Unexpectedly, this is not accompanied by a correspondingly high rate of apoptosis and, by contrast, parthenogenetic cells share the pluripotency, self-renewal and in vitro differentiation properties of their bi-parental counterparts. We hypothesise that this is possible through a series of adaptive mechanisms that include the presence of intercellular bridges similar to those that connect germ cells during spermatogenesis. This would provide a way for mutual exchange of missing cell products, thus alleviating the unbalanced chromosome distribution that would otherwise hamper normal cell functions. The presence of intercellular bridges was investigated in pig parthenogenetic embryonic stem cells (PESC) by transmission electron microscopy (TEM). Cultured cells were fixed in 2% glutaraldehyde and post-fixed in 1% osmic acid. After standard dehydration in ethanol series, samples were embedded in an Epon-Araldite 812 mixture and sectioned with a Reichert Ultracut S ultratome (Leica). Thin sections were stained and observed with a Jeol 1010 electron microscope. Pig PESC were also subjected to scanning electron microscopy (SEM). To this purpose, they were fixed and dehydrated as described above, covered with a 9-nm gold film by flash evaporation of carbon in an Emitech K 250 sputter coater (Emitech) and examined with an SEM-FEG Philips XL-30 microscope. To demonstrate functional trafficking activity through intercellular canals, fluorescent 10-kDa dextran was injected into the cytoplasm of a single cell with FemtoJet Microinjector (Eppendorf). Movement of the molecule from the injected cell to others was observed with a Nikon Eclipse TE200 microscope. Ultra-structural analysis of PESC demonstrated the existence of intercellular bridges that ensured cytoplasmic continuity among cells. These canals appeared variable in size and were characterised by the presence of stabilising actin patches. Furthermore, extensive movement of 10-kDa dextran among cells demonstrated functional intercellular trafficking through these communication canals, suggesting their use for transfer of mRNA, proteins and ribosomes among cells. Our results demonstrate that PESC present a wide network of functional intercellular bridges that may constitute an adaptive mechanism to support normal cell functions. This process is commonly observed in transformed cells and gives further support to the recent hypothesis that suggests the existence of common features and links between oncogenesis and self-renewal in pluripotent cell lines. Supported by AIRC IG 10376. PG was supported by INGM.

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