Developmental sequence of the syncarpous gynoecium of Sarracenia purpurea (Sarraceniaceae) with flattened and broadened carpels and an umbrella-shaped style

Botany ◽  
2020 ◽  
Vol 98 (8) ◽  
pp. 401-423
Author(s):  
Jinyan Guo ◽  
Chad T. Halson
Keyword(s):  
Temporal Pattern ◽  
Distal Region ◽  
Sarracenia Purpurea ◽  
Developmental Sequence ◽  
Abaxial Surface ◽  
Distal Half ◽  
Proximal Half ◽  
Secretory Glands ◽  
Postgenital Fusion ◽  
Marginal Meristem

The umbrella-shaped style of Sarracenia has a flattened and broadened distal half forming an umbrella canopy, and a slender cylindrical proximal half forming an umbrella stalk. The developmental sequence that gives rise to this unique structure has never been studied in detail. Data from light microscopy and scanning electron microscopy showed that the five carpels are initiated as discrete primordia, which then undergo congenital fusion and conduplicate folding and become a pentagonal syncarpous gynoecium. The distal region of the carpel then bends abaxially and undergoes significant expansion via a marginal meristem, forming the umbrella shape. Carpel closure is achieved via postgenital fusion at both transverse and longitudinal slits. Each of the five pollen tube transmitting tracts is enclosed by the adaxial surface of the carpel, and the inner epidermis of the umbrella canopy represents the expanded abaxial surface of the carpels, whereas the outer epidermis represents the expanded distal region of the fused carpellary margins. Epidermal trichomes develop first, then secretory glands and stomata appear later at the same stage on the umbrella canopy. This study provides insights into the evolution of the umbrella-shaped style utilizing both common and specialized carpel developmental programs with a novel spatial and temporal pattern.

scholarly journals Commitment during nematocyte differentiation in Hydra

1981 ◽  
Vol 48 (1) ◽  
pp. 207-222 ◽  
Author(s):  
T. Fujisawa ◽  
C.N. David
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Distal Region ◽  
The Body ◽  
Distal Half ◽  
Proximal Half ◽  
Dissociated Cells ◽  
Time Required ◽  
Kinetics Of ◽  
Body Column

Nematocytes in Hydra differentiate from interstitial stem cells. Desmonemes differentiate mainly in the distal half of the body column while stenoteles differentiate predominantly in the proximal half. This difference was used to determine the timing of nematocyte-type commitment in the differentiation pathway. Cells were transferred from distal or proximal regions to all positions in the body column to test when the proportion of stenotele and desmoneme differentiation changed to reflect the new environment. In the first experiment, the distal region of the body column was isolated and permitted to regenerate a whole Hydra. In the second experiment, dissociated cells from distal or proximal regions were transplanted into regenerating aggregates of Hydra tissue. Both experiments effectively transferred cells from distal or proximal positions to positions throughout the body column. By comparing the kinetics of stenotele and differentiation with the time required for distal or proximal cells to differentiate stenoteles and desmonemes in accord with their new environment, it was possible to conclude that stenotele and desmoneme commitment occurs during the terminal cell cycle prior to nematocyte differentiation and not at the stem cell. Additional experiments indicated that the number of rounds of cell division preceding differentiation is fixed at the time stem cells enter the nematocyte pathway.

Microtubules in the Heliozoan Axopodium

1971 ◽  
Vol 8 (1) ◽  
pp. 127-151
Author(s):  
Y. SHIGENAKA ◽  
L. E. ROTH ◽  
D. J. PIHLAJA
Keyword(s):  
Microscopic Study ◽  
Distal Portion ◽  
Distilled Water ◽  
Electron Microscopic ◽  
Reduced Order ◽  
Distal Half ◽  
Microtubule Array ◽  
Proximal Half ◽  
Microtubule Stability ◽  
High Lability

The precise microtubule array present in the heliozoan axopodium has been studied by experimental degradation by using the protein denaturing agent urea. Since concentrations used in typical applications were found to destroy the whole organism immediately, very dilute solutions, usually 0.15 M, were used to study axopodial retraction, which was shown to occur in 2 stages: the distal half reacts immediately and is lost in very few minutes, largely by release of segments, while retraction of the proximal half may extend over an hour. Recovery of axopodial length by removal of organisms to distilled water is possible if treatment is not carried to full axopodium loss, though organisms must be treated with solutions more dilute than 0.1 M to avoid lysis. Electron-microscopic study of retracting axopodia showed degradation of microtubules at innumerable points even in the proximal regions. Similar studies of untreated organisms showed that the typical microtubule array is found throughout the proximal portion but is progressively imprecise in the distal portion as the tip is approached. High lability to urea is therefore correlated with reduced order and reduced numbers of long linkage elements in the microtubule array. An intra-microtubule metastability is proposed and is discussed with regard to the formation of axonemes, the use of dilute urea to test microtubule stability differences, and the gradion hypothesis presented in previous work.

scholarly journals Genetic definition of two functional elements in a bacteriophage T4 host-range "cassette".

Genetics ◽  
1989 ◽  
Vol 122 (3) ◽  
pp. 471-479
Author(s):  
M Snyder ◽  
W B Wood
Keyword(s):  
Host Range ◽  
Bacteriophage T4 ◽  
Temperature Sensitive ◽  
Tail Fiber ◽  
Neighboring Gene ◽  
Distal Half ◽  
Bacterial Surface ◽  
Fiber Assembly ◽  
Proximal Half ◽  
Carboxy Terminal

Abstract Gene 37 of T4 encodes the major subunit of the distal half of the tail fiber. The distal tip of the fiber, comprised of the carboxy-terminal ends of two molecules of gene 37 product (gp37), carries the principal determinant of the phage host range. The gp37 carboxyl termini recognize the bacterial surface during infection, and, in addition, include a site required for interaction with the product of gp38 during distal half-fiber assembly. In the absence of interaction with gp38, gp37 polypeptides do not dimerize. Eleven temperature-sensitive mutants with defects located near the promoter-distal end of gene 37 were tested at nonpermissive temperatures for production of an antigen that is diagnostic of distal half-fiber assembly. Six of the mutations prevent distal half-fiber assembly. The other five allow assembly of distal half fibers, which combine with proximal half fibers and attach to phage particles, but the resulting phage do not adsorb to bacteria. These two classes of mutations define two adjacent but separate genetic regions, corresponding to two different functional domains in gp37. These two regions and the neighboring gene 38 comprise a functional unit that can be considered as a host-range "cassette," with features that are strikingly similar to corresponding functional units in other unrelated as well as related phages.

scholarly journals ANALYSIS ON THE EFFECT OF HALF ANGLE ON THE DISPLACEMENT OF PEDICLE SCREW DURING AXIAL PULL-OUT TEST IN CANCELLOUS BONE USING 2D AXISYMMETRIC FE MODEL

2021 ◽  
Vol 57 (2) ◽  
pp. 153-158
Author(s):  
Harikrishna Makaram ◽  
◽  
Ramakrishnan Swaminathan ◽  
Keyword(s):  
Pedicle Screw ◽  
High Stress ◽  
Pedicle Screws ◽  
Stress Transfer ◽  
Von Mises Stress ◽  
Fe Model ◽  
Distal Half ◽  
Proximal Half ◽  
Pull Out ◽  
Half Angle

Pedicle screw fixations are commonly used in the treatment of spinal pathologies. For effective treatment, stable anchorage between the screw and bone is necessary. In this study, the influence of proximal and distal half angle of the screw, on the displacement of fixation and stress transfer are simulated using a 2D axisymmetric finite element model. A parametric study was performed by varying the proximal half-angle between 0° and 60° in steps of 10° and the distal half angles are considered as 30° and 40°. The material properties and boundary conditions are applied based on previous studies. Frictional contact is considered between the bone and screw. Results show that, displacement of fixation is observed to be minimum at a proximal half angle of 0° and maximum at an angle of 60°. High stress concentration is observed in first few threads with highest maximum von Mises stress at an angle of 60°. High stress transfer was obtained for proximal half-angles of 40° and 50°. It is observed that, this method might aid to develop better pedicle screws for treatment of Scoliosis.

scholarly journals Comparative study of safety and efficacy of electrocautery blade with cold scalpel blade for skin opening during fixation of fracture of forearm bone with plate and screws

2017 ◽  
Vol 13 (2) ◽  
pp. 43-49
Author(s):  
Rosan Shah Kalawar ◽  
GP Khanal ◽  
P Chaudhary ◽  
R Rijal ◽  
R Maharjan ◽  
...  
Keyword(s):  
Care Center ◽  
Tertiary Care ◽  
Wound Complication ◽  
Skin Incision ◽  
Complication Rates ◽  
Distal Half ◽  
Proximal Half ◽  
Forearm Skin ◽  
Forearm Bones ◽  
Scalpel Blade

Background: Skin incisions have usually been made using a scalpel. Electrocautery, a more recent alternative, is thought to increase the risk of infection, impair healing and decrease cosmesis. Recent studies suggest that electrocautery may offer potential advantages with respect to blood loss, incision time and postoperative pain.Objective: The aim of this study was to compare the efficacy and safety of electrocautery incisions versus conventional scalpel incisions in orthopedic surgeries using internal implants.Method: The study was conducted as a prospective one in a tertiary care center in the Department of Orthopaedics, BPKIHS, Dharan, Nepal. Patients with closed fracture of the forearm bones admitted for surgery from April 2014 to September 2014 was included in the study. Each incision was divided into two halves, proximal half to be opened by steel scalpel blades and the distal half to be opened by an electrocautery blade. Proximal half and distal half of incision were compared on operating day and on days 2, 14 and again on 6 weeks and 3 month.Result: A total of 60 patients were enrolled in the study. Forearm skin incisions using electrocautery were significantly quicker than scalpel incisions (p<0.05). Postoperative wound complication rates did not differ significantly between the Scalpel and Electrocautery groups (p>0.05).Conclusion: There is no difference in healing of two halves of skin incision made by electrocautery and scalpel in orthopedic surgeries using internal implants.Health Renaissance 2015;13(2): 43-49

scholarly journals Flagellar microtubule dynamics in Chlamydomonas: cytochalasin D induces periods of microtubule shortening and elongation; and colchicine induces disassembly of the distal, but not proximal, half of the flagellum

1992 ◽  
Vol 117 (6) ◽  
pp. 1289-1298 ◽  
Author(s):  
WL Dentler ◽  
C Adams
Keyword(s):  
Average Rate ◽  
Cytochalasin D ◽  
Initial Length ◽  
Wild Type ◽  
Drug Induced ◽  
Distal Half ◽  
Proximal Half ◽  
Flagellar Assembly ◽  
Cytoplasmic Microtubules

To study the mechanisms responsible for the regulation of flagellar length, we examined the effects of colchicine and Cytochalasin D (CD) on the growth and maintenance of Chlamydomonas flagella on motile wild type cells as well as on pf 18 cells, whose flagella lack the central microtubules and are immobile. CD had no effect on the regeneration of flagella after deflagellation but it induced fully assembled flagella to shorten at an average rate of 0.03 microns-min. Cells remained fully motile in CD and even stubby flagella continued to move, indicating that flagellar shortening did not selectively disrupt machinery necessary for motility. To observe the effects of the drug on individual cells, pf 18 cells were treated with CD and flagella on cells were monitored by direct observation over a 5-hour period. Flagella on control pf 18 cells maintained their initial lengths throughout the experiment but flagella on CD-treated cells exhibited periods of elongation, shortening, and regrowth suggestive of the dynamic behavior of cytoplasmic microtubules observed in vitro and in vitro. Cells behaved individually, with no two cells exhibiting the same flagellar behavior at any given time although both flagella on any single cell behaved identically. The rate of drug-induced flagellar shortening and elongation in pf 18 cells varied from 0.08 to 0.17 microns-min-1, with each event occurring over 10-60-min periods. Addition of colchicine to wild type and pf 18 cells induced flagella to shorten at an average rate of 0.06 microns-min-1 until the flagella reached an average of 73% of their initial length, after which they exhibited no further shortening or elongation. Cells treated with colchicine and CD exhibited nearly complete flagellar resorption, with little variation in flagellar length among cells. The effects of these drugs were reversible and flagella grew to normal stable lengths after drug removal. Taken together, these results show that the distal half to one-third of the Chlamydomonas flagellum is relatively unstable in the presence of colchicine but that the proximal half to two-thirds of the flagellum is stable to this drug. In contrast to colchicine, CD can induce nearly complete flagellar microtubule disassembly as well as flagellar assembly. Flagellar microtubules must, therefore, be inherently unstable, and flagellar length is stabilized by factors that are sensitive, either directly or indirectly, to the effects of CD.

Lesions of rat skeletal muscle after local block of acetylcholinesterase and neuromuscular stimulation

2003 ◽  
Vol 94 (6) ◽  
pp. 2494-2501 ◽  
Author(s):  
S. Mense ◽  
D. G. Simons ◽  
U. Hoheisel ◽  
B. Quenzer
Keyword(s):  
Skeletal Muscle ◽  
Morphological Changes ◽  
Acetylcholinesterase Inhibitor ◽  
Trigger Points ◽  
Myofascial Trigger Points ◽  
Distal Half ◽  
Proximal Half ◽  
Starting Point ◽  
Muscle Nerve ◽  
Local Block

In skeletal muscle, a local increase of acetylcholine (ACh) in a few end plates has been hypothesized to cause the formation of contraction knots that can be found in myofascial trigger points. To test this hypothesis in rats, small amounts of an acetylcholinesterase inhibitor [diisopropylfluorophosphate (DFP)] were injected into the proximal half of the gastrocnemius muscle, and the muscle nerve was electrically stimulated for 30–60 min for induction of muscle twitches. The distal half of the muscle, which performed the same contractions, served as a control to assess the effects of the twitches without DFP. Sections of the muscle were evaluated for morphological changes in relation to the location of blocked end plates. Compared with the distal half of the muscle, the DFP-injected proximal half exhibited significantly higher numbers of abnormally contracted fibers (local contractures), torn fibers, and longitudinal stripes. DFP-injected animals in which the muscle nerve was not stimulated and that were allowed to survive for 24 h exhibited the same lesions but in smaller numbers. The data indicate that an increased concentration of ACh in a few end plates causes damage to muscle fibers. The results support the assumption that a dysfunctional end plate exhibiting increased release of ACh may be the starting point for regional abnormal contractions, which are thought to be essential for the formation of myofascial trigger points.

Effect of embryo orientation on the developmental sequence of adventitious organogenesis in jack pine (Pinus banksiana Lamb.)

2000 ◽  
Vol 78 (10) ◽  
pp. 1348-1360 ◽  
Author(s):  
Gervais Pelletier ◽  
Sylvie Laliberté
Keyword(s):  
Electron Microscopy ◽  
Pinus Banksiana ◽  
Light And Electron Microscopy ◽  
Jack Pine ◽  
Time Sequence ◽  
Developmental Sequence ◽  
Culture Initiation ◽  
Abaxial Surface ◽  
Half Strength ◽  
Apical Area

The developmental sequence of adventitious organogenesis in jack pine (Pinus banksiana Lamb.) embryos was analysed depending on two explant orientations. Embryos were placed vertically (cotyledons downward) or horizontally on half-strength Schenk and Hildebrandt medium containing 10 µM 6-benzylaminopurine. Samples were harvested at 2- to 3-day intervals for a 21-day period and observed using light and electron microscopy. In vertically placed embryos, cotyledons were inserted into the medium and became necrotic, while buds and phylloids developed on the upper part of the hypocotyl and in the apical area, 14 and 9 days after culture initiation respectively. In horizontally cultured embryos, organogenesis started in the intercotyledonary areas (day 11) and spread to the abaxial surface of cotyledonary margins outside the medium (day 14). A few buds also developed on the adaxial surface of cotyledons, starting on day 16. In the apical area, phylloid formation started on day 18. Nodules were induced in tissues in contact with the medium for both orientations, but in distinct sites. Embryo orientation influenced the localization of induction sites and the time sequence of organogenesis. The pattern for the mobilization of proteins, lipids, and polysaccharides prior to organogenesis was similar for both orientations. A depletion in proteins and polysaccharides did not occur in tissues in contact with the culture medium.Key words: adventitious organogenesis, embryo culture, explant orientation, jack pine, microscopy, Pinus banksiana.

scholarly journals Nonprogressive sperm motility is characteristic of most complete t haplotypes in the mouse

1983 ◽  
Vol 42 (2) ◽  
pp. 151-157 ◽  
Author(s):  
Patricia Olds-Clarke
Keyword(s):  
Sperm Motility ◽  
Distal Region ◽  
Complementation Group ◽  
Motile Sperm ◽  
Male Mice ◽  
Wild Type ◽  
Epididymal Sperm ◽  
Distal Half ◽  
The Mean

SUMMARYEpididymal sperm from male mice carrying tw32 (t12 complementation group) exhibit a peculiar nonprogressive type of motility called ‘dancing’; sperm from congenie wild-type mice do not. To determine whether this effect was unique to tw32 or common to all t haplotypes, sperm from mice carrying other t haplotypes were examined. A male was considered to have nonprogressive sperm if more than 20% of the motile sperm had nonprogressive trajectories. The mean percentage of nonprogressive but motile sperm for 33 wild-type and Brachyury males of various genetic backgrounds was 4. All males carrying tw12 (tw1 complementation group), tw5 or tw73, and 56% of males carrying t0 or tLub1 had nonprogressive motile sperm. Five per cent of males carrying t chromatin or a deletion in the proximal (to the centromere) half of the t complex had nonprogressive motile sperm, but all males carrying t chromatin in the distal half of the t complex had nonprogressive motile sperm. These observations suggest that the factor or factors causing nonprogressive sperm motility may be common to all complete t haplotypes, and located in the distal region of the t complex.

Salvinia leaves. II. Morphogenesis of the floating leaf

1979 ◽  
Vol 57 (19) ◽  
pp. 1951-1959 ◽  
Author(s):  
Judith G. Croxdale
Keyword(s):  
Leaf Surface ◽  
Apical Cell ◽  
Longitudinal Direction ◽  
Abaxial Surface ◽  
Leaf Morphogenesis ◽  
Meristematic Activity ◽  
Cell Layers ◽  
Leaf Differentiation ◽  
Marginal Meristem ◽  
Floating Leaf

The floating leaves of Salvinia arise in a manner not previously described in plants. Leaf morphogenesis is the result of meristematic activity in the leaf apical cell and two abaxial meristems. These abaxial meristems originate in the dorsal sectors of the primordium and are separated from one another by a notch which runs the length of the primordial blade region. Each meristem consists of a single longitudinal file of cells which increases the width of the blade panel by strict anticlinal divisions. These anticlinal derivatives divide periclinally to establish the cell layers of the lamina. Unlike most dorsiventral leaves in which the blade is produced by a marginal meristem. Salvinia floating leaf blade panels increase radially by the action of these abaxial meristems. Thus, the leaf surface exposed to the air is morphologically the abaxial surface and that in contact with the water is the adaxial surface. Leaf differentiation and maturation are acropetal in the longitudinal direction and from the midvein to the margins in the horizontal direction.

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