Zoospore ultrastructure in the genus Rhizophydium (Chytridiales)

1978 ◽  
Vol 56 (19) ◽  
pp. 2380-2404 ◽  
Author(s):  
D. J. S. Barr ◽  
V. E. Hadland-Hartmann
Keyword(s):  
Membrane System ◽  
Double Membrane ◽  
Lipid Globule ◽  
Lateral Posterior ◽  
Membrane Bound ◽  
Relationship Of ◽  
The Relationship ◽  
Posterior Position ◽  
Compact Cluster ◽  
Peripheral Cytoplasm

The zoospore ultrastructure of 12 species of Rhizophydium is described. Species include the following: R. chlorogonii (Serbinow) Jaczewski; R. constantineani Saccardo; R. haynaldii (Schaarschmidt) Fischer; R. capillaceum Barr; two morphologically and cytologically different species, each previously identified as R. sphaerotheca Zopf; R. patellarium Scholz; R. biporosum (Couch) Barr; R. subangulosum (Braun) Rabenhorst; R. laterale (Braun) Rabenhorst; R. sphaerocarpum (Zopf) Fischer var. spirogyrae Barr; and two isolates of R. pollinis-pini (Braun) Zopf. The Rhizophydium zoospore is basically similar to the Chytridium zoospore having (1) the nucleus, a compact cluster of ribosomes, one or more mitochondria, and a microbody – lipid globule complex compartmentalized into the core of the zoospore by a double membrane system and (2) two to five microtubules connecting one side of the kinetosome to the rumposome on the lipid globule surface and thus anchoring the lipid globule in a lateral–posterior position in the zoospore. Rhizophydium patellarium does not have kinetosome-associated microtubules or a rumposome but does have the membrane-bound core area. In all species, a microbody and mitochondrion are associated with the lipid globule. The number of mitochondria varies from 1 in some species to several or to over 30 in other species. In one isolate of R. pollinis-pini, there is 1 large mitochondrion and in the other there were 30–35 small mitochondria. The peripheral cytoplasm of all species contains clusters of vesicles or endoplasmic reticulum which bud from the double membrane system, vesicles of moderate electron density, and vacuoles of various sizes; R. capillaceum, R. patellarium, and R. subangulosum have in addition vesicles which contain very electron-dense material. Rhizophydium capillaceum and R. sphaerocarpum zoospores have virus-like particles and the R. biporosum zoospore contains a paracrystalline body. The taxonomic significance of the observations and the relationship of Rhizophydium to other chytrids are stressed in the Discussion.

Inhibition of Na+-K+-activated ATPase activity following experimental spinal cord trauma

1978 ◽  
Vol 49 (4) ◽  
pp. 563-568 ◽  
Author(s):  
Nancy R. Clendenon ◽  
Norman Allen ◽  
Wanda A. Gordon ◽  
W. George Bingham
Keyword(s):  
Spinal Cord ◽  
Specific Activity ◽  
Early Time ◽  
Central Core ◽  
Content Type ◽  
Membrane Bound ◽  
And Control ◽  
Relationship Of ◽  
Impact Injury ◽  
The Relationship

✓ The specific activity of the membrane-bound enzyme, Na+-K+-activated adenosine triphosphatase (ATPase), has been shown to be decreased following experimental impact injury (400 gm-cm) to the spinal cord in dogs. The prompt and significant (p < 0.01) fall in activity was evident as early as 5 minutes after injury, and remained at 56% to 67% of control for the 1-hour period studied. This decrease was most prominent in the central core of the traumatized segments of spinal cord. Central core samples, excised immediately adjacent to the trauma site, gave values for the Na+-K+-activated enzyme intermediate to those of the trauma and control sites. For these same samples, the activity of the Mg+2-dependent ATPase did not change appreciably. No alterations were observed in the tissue surrounding the zone of maximum injury at these early time periods. The relationship of membrane-bound enzyme alterations to blood flow, clotting mechanisms, and abnormal free radical reactions are briefly discussed.

The Relationship of the Axillary Nerve to Arthroscopically Placed Capsulolabral Sutures

1998 ◽  
Vol 26 (4) ◽  
pp. 505-509 ◽  
Author(s):  
Colin L. Eakin ◽  
Paul Dvirnak ◽  
Chris M. Miller ◽  
Richard J. Hawkins
Keyword(s):  
Glenohumeral Joint ◽  
Average Distance ◽  
Axillary Nerve ◽  
Knot Tying ◽  
Arthroscopic Reconstruction ◽  
Anterior Position ◽  
Arthroscopic Knot ◽  
Relationship Of ◽  
The Relationship ◽  
Posterior Position

Ten cadaveric shoulders (mean donor age, 60.5 years) underwent arthroscopic placement of capsulolabral sutures as performed during arthroscopic reconstruction for shoulder instability. In relation to the glenoid face, the sutures were placed anterior, anteroinferior, inferior, posteroinferior, and posterior. All sutures entered the capsule approximately 1 cm away from the glenoid and exited beneath the labrum, and were tied using arthroscopic knot-tying techniques. The shoulders were frozen in the lateral arthroscopic position of approximately 45° of abduction and 20° of flexion and sectioned in the plane of the glenohumeral joint. The axillary nerve was then dissected, and the average distance from the nerve to each suture was found to be 16.7 mm at the anterior position, 12.5 mm at the anteroinferior position, 14.4 mm at the inferior position, 24.1 mm at the posteroinferior position, and 32.3 mm at the posterior position. In no specimen was any suture closer to the axillary nerve than 7 mm. We noted a statistically significant trend for the nerve to lie closest to the anteroinferior suture and gradually recede from the remaining sutures lying more posteriorly. This anatomic study is the first to demonstrate a relatively safe margin for arthroscopic suture placement between the capsule and axillary nerve when these sutures are placed approximately 1 cm from the glenoid rim.

The Influence of Coagulant on the Membrane System

2012 ◽  
Vol 610-613 ◽  
pp. 2144-2148
Author(s):  
Chun Bo Zhang ◽  
Jiu Sheng Wang ◽  
Tian Li Sun
Keyword(s):  
Membrane Fouling ◽  
Metal Ion ◽  
Membrane System ◽  
Ion Content ◽  
Water Turbidity ◽  
Coagulant Dosage ◽  
Material Component ◽  
Relationship Of ◽  
The Relationship

On the beaker test of Laboratory coagulation sedimentation for low turbidity water, through the relationship of water turbidity, residual metal ion content and type of coagulant dosage, and membrane fouling material component within the system, the cause of coagulant fouling membrane system is coagulant sedimentation occurs once again, and put forward to measures of reduce membrane fouling because of coagulant, these will be benefit for adjustment of coagulation sedimentation treatment.

On the Head of the Liopelmid Frog, Ascaphus Truei

1943 ◽  
Vol s2-84 (334) ◽  
pp. 105-185
Author(s):  
H. K. PUSEY
Keyword(s):  
Full Agreement ◽  
Ascaphus Truei ◽  
Discoglossus Pictus ◽  
Frog Tadpole ◽  
Relationship Of ◽  
The Relationship ◽  
Auditory Capsule ◽  
Posterior Position ◽  
Frog Larva ◽  
Head Muscles

This paper gives the first account of the larval cranial anatomy of either of the genera of Liopelmid frogs. A single, partly grown larva of Ascaphus truei, Stejneger, has been studied in transverse sections and in two-dimensional reconstructions. Its chondrocranium, jaws, gill arches, and head muscles are described and figured. Comparisons are made throughout with similar structures of Urodeles and certain other frogs, particularly Discoglossus pictus and Kana temporaria. A summary of the characters which Ascaphus shares with the Urodeles is given on pp. 175-7 and with Discoglossus on pp. 177-8. The reader is referred to these lists as an important part of this summary. Noble (1931, &c.) considers Ascaphus (with Liopelma) to be one of the two most primitive living frogs. The findings of this paper are in full agreement with this view. Thus larval Ascaphus is shown to be a persistently primitive ‘link-animal’ whose cranial structures, in almost every case, differ from those of other frogs--often radically--and throw much light on the evolution of the modern-type frog tadpole from the unknown (larval) ancestor. Ascaphus is shown to have more characters in common with the Urodeles than any other frog larva yet described. Most of these are probably a simple retention of an ancestral Amphibian plan which led on to the frogs and Urodeles (contrast the writings of Holmgren and Säve-Söderbergh). Others seem to link these two orders even more closely together. Such are: (1) The presence of ‘urobranchial’ prongs on the basibranchial copula and the attachment to them of Subarcuales obliqui and Eecti cervicis muscles; (2) the presence of a pair of Branchio-hyoideus externus muscles and other similarities of the musculature. The relationship of Ascaphus to the Gymnophiona is far less marked. Ascaphus, however, has remained more primitive than the present-day Urodeles by retaining: (1) a? Vth gill bar, with its Subarcualis rectus and S. obliquus muscles, and (2) four pairs of S. obliqui muscles instead of two. In these points it is, in fact, the most primitive living tetrapod. Ascaphus is, however, somewhat specialized in relation to a sucker mechanism and to a peculiar method of larval progression which it employs. These have led to an exaggerated autostyly of the palatoquadrate which has developed an additional fusion to the anterior tip of the auditory capsule; to a rigid fusion of the central part of the supra-rostral system to the skull; to the general heavy build of the head cartilages and to the great size of several of the mandibular and hyoid muscles; to a general consolidation and widening of parts of the hyobranchial apparatus; to a widening of the posterior jaw cartilages and the development from them of unique posterior spurs. A pre-oral mouth cavity and a long ‘posterior narial tube’ to the inner nostril are also parts of this specialization. Among the frogs Ascaphus is shown to be most nearly related to the Discoglossidae, which appear to have been derived from an ancestor with many Ascaphus-like characters. This is in further agreement with Noble's classification and is particularly true of Discoglossus pictus. Ascaphus is unique among frogs in the posterior position of its splanchnic head structures; see the list on p. 147. A forecast is made of the probable evolution of the moderntype tadpole's jaw system from that of the unknown ancestor and this is diagrammatically summed up in Text-fig. 7, pp. 158-9. Evidence is collected to show that the ‘anterior basal process’ (= commissura quadrato-cranialis anterior) is not an ethmoidal structure by origin, as has been held up to now, and consequently Säve-Söderbergh's use of it to explain an ethmoidal structure in a Stegocephalian Amphibian is criticized. An account of the muscles has been given in summary form on pp. 126 to 146 and cannot be further condensed here. But it may be noted that Edgeworth's theories (1935) of the primitive muscular content of a single branchial segment break down when applied to Ascaphus. It is now probable that a single segment could simultaneously contain a Subarcualis rectus, a S. obliquus, and a Transversus ventralis muscle. Further, Edgeworth's term ‘Transversus ventralis II’ must be changed to ‘S. obliquus II’ in the frogs and his ‘S. rectus IV’ must probably be changed to ‘S. recti IV, III, and II’ in the Urodeles.

A New Reference to Evaluate Syndesmosis in Sagittal Plane Radiographs of the Ankle: The Lateral Posterior Ankle Ratio

2019 ◽  
Vol 109 (6) ◽  
pp. 426-430
Author(s):  
Ali Turgut ◽  
Emre Bilgin ◽  
Mert Filibeli ◽  
İbrahim Kuşak ◽  
Mert Kumbaracı ◽  
...  
Keyword(s):  
Sagittal Plane ◽  
Functional Results ◽  
Anatomical Reduction ◽  
Lateral Ankle ◽  
Significant Difference ◽  
Lateral Posterior ◽  
History Of ◽  
Measured Line ◽  
Relationship Of ◽  
The Relationship

Background: Confirmation of anatomical reduction of ankle syndesmosis is mandatory because improper reduction leads to poor functional results. Coronal plane evaluation of syndesmosis is well described in the literature, but there is little information about sagittal plane evaluation. We sought to evaluate the relationship of fibula and tibia in the sagittal plane and create a new reference that can be applied easily and reliably. Methods: Lateral ankle radiographs of 337 individuals with no history of ankle fracture were evaluated. A line was drawn between the anterior and posterior cortices of the distal lateral tibia, and the length of this line was measured (line 1). The distance between the anterior and posterior cortices of the fibula on this line was measured, and the center of this second distance was identified and marked. The posterior half of the fibular width was divided by line 1 and was named the lateral posterior ankle ratio (LPAR). Statistical analysis was performed by side and sex. Results: Mean patient age was 38.6 years; mean LPAR was 0.48. There was a significant difference between men and women by age (P &lt; .001) and LPAR (P = .01). There was no significant difference between right and left ankles by age (P = .63) and LPAR (P = .64). The LPAR was less than 0.40 in 6.8% of the radiographs, 0.40 to 0.50 in 57.9%, and greater than 0.50 to 0.60 in 32.9%. Conclusions: The LPAR should approximate 50% in normal lateral ankle images and, by extrapolation, after syndesmotic reduction.

scholarly journals Characterization of Thylakoid Division Using Chloroplast Dividing Mutants in Arabidopsis

2017 ◽  
Author(s):  
Jonathan Ho ◽  
Warren Kwan ◽  
Vivian Li ◽  
Steven M. Theg
Keyword(s):  
Thylakoid Membrane ◽  
Membrane System ◽  
Chloroplast Division ◽  
Membrane Structures ◽  
Double Membrane ◽  
Organelle Division ◽  
Membrane Bound

AbstractChloroplasts are double membrane bound organelles that are found in plants and algae. Their division requires a number of proteins to assemble into rings along the center of the organelle and to constrict in synchrony. Chloroplasts possess a third membrane system, the thylakoids, which house the majority of proteins responsible for the light-dependent reactions. The mechanism that allows chloroplasts to sort out and separate the intricate thylakoid membrane structures during organelle division remain unknown. By characterizing the sizes of thylakoids found in a number of different chloroplast division mutants in Arabidopsis, we show that thylakoids do not divide independently of the chloroplast division cycle. More specifically, we show that thylakoid division requires the formation of both the inner and the outer contractile rings of the chloroplast.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Studies on Leukemogenic and Sarcomagenic Viruses

1970 ◽  
Vol 28 ◽  
pp. 156-157
Author(s):  
Leon Dmochowski
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Morphological Properties ◽  
Mode Of Development ◽  
Relationship Of ◽  
The Relationship

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.

The relationship of IGE receptor topography to signaling activity in RBL-2H3 mast cells

1991 ◽  
Vol 49 ◽  
pp. 236-237
Author(s):  
J.R. Pfeiffer ◽  
J.C. Seagrave ◽  
C. Wofsy ◽  
J.M. Oliver
Keyword(s):  
Mast Cells ◽  
Protein A ◽  
Scattered Electron ◽  
Ige Receptor ◽  
Receptor Complexes ◽  
Ige Binding ◽  
Electron Imaging ◽  
Small Clusters ◽  
Relationship Of ◽  
The Relationship

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.

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