scholarly journals NUCLEOLAR AGING IN TETRAHYMENA DURING THE CULTURAL GROWTH CYCLE

1971 ◽  
Vol 48 (1) ◽  
pp. 143-154 ◽  
Author(s):  
Birgit Satir ◽  
Ellen Roter Dirksen
Keyword(s):  
Stationary Phase ◽  
Actinomycin D ◽  
Nuclear Periphery ◽  
Tetrahymena Pyriformis ◽  
Growth Cycle ◽  
Growth Phases ◽  
Stage 4 ◽  
The Individual ◽  
Stage 1 ◽  
Logarithmic Growth

Nucelolar morphology was studied by electron microscopy in control and actinomycin D-treated populations of Tetrahymena pyriformis (W) during the cultural growth cycle. Nucleoli exhibit an "aging" cycle concomitant with the cultural growth cycle, but independent of the individual cell cycle. Four different stages in the course of this aging process have been defined. Stage 1 occurs upon inoculation (low number of cells per milliliter) and lasts through lag and accelerating growth phases. In this stage, many small nucleoli are found at the nuclear periphery. In stages 2 and 3, nucleolar fusion begins. Stage 2 dominates the first half of logarithmic growth, and stage 3 dominates the second half. In late decelerating growth phase, the nucleoli enter stage 4. In this stage, only a few large nucleoli are present and these are apparently inactive in ribosome production. In stationary phase, where total RNA remains constant, only stage 4 nucleoli are present. The relative preponderance of granular vs. fibrous components in the nucleoli changes during this cycle, the granular component dominating stage 1 nucleoli and the fibrillar, stage 4 nucleoli. There is a shortening of the intermediate nucleolar stages in the treated cultures; fusion occurs early and is now pronounced. Not enough ribosomes accumulate to carry the treated cultures through the number of generations equivalent to those of the control, which produces a premature stationary phase.

Die Bildung von Thymidintriphosphat bei Tetrahymena pyriformis (EHRENBERG) in statistischen und hitzesynchronisierten Kulturen / Formation of Thymidine Triphosphate in statistical and heat synchronized cultures of Tetrahymena pyriformis (EHRENBERG)

1970 ◽  
Vol 25 (5) ◽  
pp. 517-521 ◽  
Author(s):  
Manfred K. Grieshaber ◽  
Franz Duspiva
Keyword(s):  
Heat Treatment ◽  
Enzyme Activity ◽  
Stationary Phase ◽  
Dna Synthesis ◽  
Tetrahymena Pyriformis ◽  
Thymidylate Kinase ◽  
Proteose Peptone ◽  
Thymidine Triphosphate ◽  
Logarithmic Growth ◽  
Synchronized Cultures

The activity of thymidylate kinase is correlated with DNA-synthesis in Tetrahymena. During logarithmic growth it is twice as high as in the stationary phase; in cultures synchronized by heat treatment, the activity of the enzyme increases with the onset of DNA-synthesis. After application of 5 x 10-6 ᴍ Methotrexate, the activity of thymidylate kinase remains unchanged. There is, however, a dramatic increase in enzyme activity when the inhibition of transmethylations is circumvened by adding thymidine and proteose-peptone.

scholarly journals THE FATE OF MITOCHONDRIA DURING AGING IN TETRAHYMENA PYRIFORMIS

1964 ◽  
Vol 20 (1) ◽  
pp. 113-129 ◽  
Author(s):  
Alfred M. Elliott ◽  
Il Jin Bak
Keyword(s):  
Growth Phase ◽  
Tetrahymena Pyriformis ◽  
Growth Cycle ◽  
Stationary Growth Phase ◽  
Stationary Growth ◽  
Logarithmic Growth Phase ◽  
Cytoplasmic Structures ◽  
Hydrolysis Of ◽  
Logarithmic Growth ◽  
Single Mitochondrion

During the growth cycle of Tetrahymena pyriformis the mitochondria undergo changes in position, number, and structure. Ciliates in the logarithmic growth phase possess elongated mitochondria which are aligned along the plasma membrane and are closely associated with the kinetosomes and kinetodesmata. Mitochondria appear to divide across the long axis at this time, resulting in two or more products. Throughout this phase of growth mitochondrial divisions keep pace with cytokinesis so that the population of mitochondria remains at essentially the minimal level. As the ciliates enter the stationary growth phase the mitochondria increase in number, become oval to spherical in shape, and some migrate into the cytoplasm. Intramitochondrial masses of various configurations appear at this time. Some of the mitochondria lying in the cytoplasm become incorporated into vacuoles. Within these vacuoles either a single mitochondrion appears or several mitochondria may be seen along with other cytoplasmic structures. Later in the stationary growth phase the contained mitochondria are dense and the tubules are more compact than normal. Various stages in disorganization of the mitochondria are observed in a single large vacuole. Cytochemical tests reveal the presence of acid phosphatase, suggesting that hydrolysis of the vacuolar contents occurs. Lipid droplets increase in number during the middle and late stationary phase of growth. These events are interpreted as being associated with the normal process of aging in T. pyriformis.

Floral Initiation and Development in Helipterum roseum (Hook.) Benth. And Helichrysum bracteatum (Vent.) Andrews (Asteraceae)

1988 ◽  
Vol 36 (5) ◽  
pp. 575 ◽  
Author(s):  
KV Sharman ◽  
M Sedgley
Keyword(s):  
Apical Meristem ◽  
Developmental Stages ◽  
Involucral Bract ◽  
Floral Initiation ◽  
Naked Eye ◽  
Sequence Of Events ◽  
Stage 4 ◽  
The Individual ◽  
Stage 1 ◽  
Helichrysum Bracteatum

Floral initiation and development in Helichrysum bracteatum and Helipterum roseum were investigated by scanning electron microscopy. The sequence of events in these two species was similar and occurred rapidly. Seven stages in apical development were identified, which were distinctive in both appearance and size. Stage 1 was a small vegetative meristem with 2-4 leaf primordia. Stage 2 (also vegetative) was characterized by a doubling in both height and diameter. A doming of the apical meristem signified the commencement of stage 3, and at the appearance of the first involucral bracts (stage 4) the apex had further tripled in height and doubled in diameter. This was followed by the appearance of floret primordia (stage 5). By the time the inflorescence buds were visible to the naked eye (stage 6) several rows of florets were present, and at anthesis (stage 7) the capitulum was covered with florets. During the transition from stage 4 to stage 5 a few developing primordia appeared to divide. The lower portion developed into a small involucral bract and the upper portion into a floret. The florets developed centripetally such that a range of developmental stages was present on the capitulum. The development of the individual florets involved the differentiation of perianth, anther, pistil and pappus hairs. Stage 4 was considered the point at which the apex was committed to flower.

scholarly journals Temporal Expression of Pertussis Toxin and Ptl Secretion Proteins by Bordetella pertussis

2004 ◽  
Vol 186 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Amy A. Rambow-Larsen ◽  
Alison A. Weiss
Keyword(s):  
Pertussis Toxin ◽  
Time Course ◽  
Growth Cycle ◽  
Lag Phase ◽  
Logarithmic Growth Phase ◽  
Type Iv ◽  
Constant Rate ◽  
Toxin Secretion ◽  
The Individual ◽  
Logarithmic Growth

ABSTRACT Pertussis toxin is an AB5 toxin comprised of protein subunits S1 through S5. The individual subunits are secreted by a Sec-dependent mechanism into the periplasm, where the toxin is assembled. The Ptl type IV secretion system mediates secretion of assembled toxin past the outer membrane. In this study, we examined the time course of protein expression, toxin assembly, and secretion as a function of the bacterial growth cycle. Logarithmic growth was observed after a 1-h lag phase. Secreted toxin was first observed at 3 h. Secretion continued throughout the logarithmic growth phase and decreased as the culture entered the stationary phase after about 24 h. On a per cell basis, toxin secretion occurred at a constant rate of 3 molecules/min/cell from 2 to 18 h. More of toxin subunits S1, S2, and S3 were produced than were secreted, resulting in periplasmic accumulation. Periplasmic S1, S2, and S3 were found to be soluble in the periplasm, as well as membrane associated. About one-half of the periplasmic S1, S2 and S3 subunits were incorporated into holotoxin. Secretion component PtlF was present at a low level at time zero, and the level increased between 2 and 24 h from 30 to 1,000 molecules per cell; however, the initial level of PtlF, 30 molecules per cell, supported maximal secretion. The accumulation of both periplasmic toxin and secretion components suggests that translation rates exceed the rate of secretion and that secretion, not toxin and Ptl complex assembly, is rate limiting.

Teaching undergraduates the process of peer review: learning by doing

2010 ◽  
Vol 34 (3) ◽  
pp. 137-144 ◽  
Author(s):  
P. K. Rangachari
Keyword(s):  
Peer Review ◽  
Review Process ◽  
Peer Review Process ◽  
Learning By Doing ◽  
Student Responses ◽  
Active Approach ◽  
Stage 4 ◽  
Stage Process ◽  
The Individual ◽  
Stage 1

An active approach allowed undergraduates in Health Sciences to learn the dynamics of peer review at first hand. A four-stage process was used. In stage 1, students formed self-selected groups to explore specific issues. In stage 2, each group posted their interim reports online on a specific date. Each student read all the other reports and prepared detailed critiques. In stage 3, each report was discussed at sessions where the lead discussant was selected at random. All students participated in the peer review process. The written critiques were collated and returned to each group, who were asked to resubmit their revised reports within 2 wk. In stage 4, final submissions accompanied by rebuttals were graded. Student responses to a questionnaire were highly positive. They recognized the individual steps in the standard peer review, appreciated the complexities involved, and got a first-hand experience of some of the inherent variabilities involved. The absence of formal presentations and the opportunity to read each other's reports permitted them to study issues in greater depth.

scholarly journals Changes in the transport of mitochondrial Ca2+ during the culture growth cycle of Tetrahymena pyriformis

1985 ◽  
Vol 77 (1) ◽  
pp. 47-56
Author(s):  
Y.V. Kim ◽  
LYu Kudzina ◽  
V.P. Zinchenko ◽  
Y.V. Evtodienko
Keyword(s):  
Stationary Phase ◽  
Morphological Changes ◽  
Stationary Phases ◽  
Mitochondrial Protein ◽  
Tetrahymena Pyriformis ◽  
Growth Cycle ◽  
Lag Phase ◽  
Rapid Release ◽  
Culture Growth ◽  
Energy Dependent

The properties of the Ca2+ transport system of mitochondria, isolated in various phases of growth of static cultures of Tetrahymena pyriformis, were studied. A large increase in the endogenous energy-dependent Ca2+ content of mitochondria was observed as cultures of T. pyriformis passed through the exponential and stationary phases of growth (approx. 0.25 and 50 nmol Ca2+ per mg mitochondrial protein, respectively). Simultaneously, the mitochondria dramatically lost their ability to withstand large concentrations of Ca2+ and ADP. However, in the latter case they were able to phosphorylate a large amount of ADP if the strong Ca2+ chelator, ethylene glycol bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, was initially present in the incubation medium. Furthermore, all the changes observed in mitochondria from the stationary phase cells were completely reversed when cell proliferation was re-activated after the lag phase, either by reseeding the stationery cells in fresh growth medium or by oxygenation of the old medium. In aerobic conditions even a small addition of Ca2+ was able to induce rapid release of Ca2+ from mitochondria isolated during the stationary phase of growth. It is suggested that the redistribution of Ca2+ between the mitochondria and the cytoplasm at the onset of the lag phase may serve as the main trigger for the subsequent biochemical and morphological changes observed in T. pyriformis.

Morphological Characterization of Mycobacteriophage R1

1974 ◽  
Vol 32 ◽  
pp. 254-255
Author(s):  
B. L. Soloff ◽  
T. A. Rado
Keyword(s):  
Carbon Source ◽  
Stationary Phase ◽  
Growth Phase ◽  
Minimal Medium ◽  
Morphological Characterization ◽  
Logarithmic Growth Phase ◽  
Complete Lysis ◽  
Lysogenic Culture ◽  
Logarithmic Growth

Mycobacteriophage R1 was originally isolated from a lysogenic culture of M. butyricum. The virus was propagated on a leucine-requiring derivative of M. smegmatis, 607 leu−, isolated by nitrosoguanidine mutagenesis of typestrain ATCC 607. Growth was accomplished in a minimal medium containing glycerol and glucose as carbon source and enriched by the addition of 80 μg/ ml L-leucine. Bacteria in early logarithmic growth phase were infected with virus at a multiplicity of 5, and incubated with aeration for 8 hours. The partially lysed suspension was diluted 1:10 in growth medium and incubated for a further 8 hours. This permitted stationary phase cells to re-enter logarithmic growth and resulted in complete lysis of the culture.

Alterations in the number of motoneurons containing immunoreactive calcitonin gene-related peptide(CGRP)& choline acetyltransferase(ChAT) in the cervical spinal cord of the wobbler mouse during the development of the motoneuron disease

1995 ◽  
Vol 53 ◽  
pp. 970-971
Author(s):  
L. Vacca-Galloway ◽  
Y.Q. Zhang ◽  
P. Bose ◽  
S.H. Zhang
Keyword(s):  
Spinal Cord ◽  
Early Stage ◽  
Cervical Spinal Cord ◽  
Wild Type Mouse ◽  
Reflex Response ◽  
Mouse Strains ◽  
Behavioral Tests ◽  
Wobbler Mouse ◽  
Stage 4 ◽  
Stage 1

The Wobbler mouse (wr) has been studied as a model for inherited human motoneuron diseases (MNDs). Using behavioral tests for forelimb power, walking, climbing, and the “clasp-like reflex” response, the progress of the MND can be categorized into early (Stage 1, age 21 days) and late (Stage 4, age 3 months) stages. Age-and sex-matched normal phenotype littermates (NFR/wr) were used as controls (Stage 0), as well as mice from two related wild-type mouse strains: NFR/N and a C57BI/6N. Using behavioral tests, we also detected pre-symptomatic Wobblers at postnatal ages 7 and 14 days. The mice were anesthetized and perfusion-fixed for immunocytochemical (ICC) of CGRP and ChAT in the spinal cord (C3 to C5).Using computerized morphomety (Vidas, Zeiss), the numbers of IR-CGRP labelled motoneurons were significantly lower in 14 day old Wobbler specimens compared with the controls (Fig. 1). The same trend was observed at 21 days (Stage 1) and 3 months (Stage 4). The IR-CGRP-containing motoneurons in the Wobbler specimens declined progressively with age.

Novel staging classification of primary mitral regurgitation based on the presence of cardiac damage

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
A.L Van Wijngaarden ◽  
Y.L Hiemstra ◽  
P Van Der Bijl ◽  
V Delgado ◽  
N Ajmone Marsan ◽  
...  
Keyword(s):  
Mitral Regurgitation ◽  
Kidney Function ◽  
Left Ventricular ◽  
Prognostic Impact ◽  
Cardiac Damage ◽  
Stage 4 ◽  
All Cause Mortality ◽  
Primary Mitral Regurgitation ◽  
Stage 1 ◽  
Staging Classification

Abstract Background The indication for surgery in patients with severe primary mitral regurgitation (MR) is currently based on the presence of symptoms, left ventricular (LV) dilatation and dysfunction, atrial fibrillation and pulmonary hypertension. The aim of this study was to evaluate the prognostic impact of a new staging classification based on cardiac damage including the known risk factors but also including global longitudinal strain (GLS), severe left atrial (LA) dilatation and right ventricular (RV) dysfunction. Methods In total 614 patients who underwent surgery for severe primary MR with available baseline transthoracic echocardiograms were included. Patients were classified according to the extent of cardiac damage (Figure): Stage 0-no cardiac damage, Stage 1-LV damage, Stage 2-LA damage, Stage 3-pulmonary vasculature or tricuspid valve damage and Stage 4-RV damage. Patients were followed for all-cause mortality. Results Based on the proposed classification, 172 (28%) patients were classified as Stage 0, 102 (17%) as Stage 1, 134 (21%) as Stage 2, 135 (22%) as Stage 3 and 71 (11%) as Stage 4. The more advanced the stage, the older the patients were with worse kidney function, more symptoms and higher EuroScore. Kaplan-Meier curve analysis revealed that patients with more advanced stages of cardiac damage had a significantly worse survival (log-rank chi-square 35.2; p<0.001) (Figure). On multivariable analysis, age, male, chronic obstructive pulmonary disease, kidney function, and stage of cardiac damage were independently associated with all-cause mortality. For each stage increase, a 22% higher risk for all-cause mortality was observed (95% CI: 1.064–1.395; p=0.004). Conclusion In patients with severe primary MR, a novel staging classification based on the extent of cardiac damage, may help refining risk stratification, particularly including also GLS, LA dilatation and RV dysfunction in the assessment. Funding Acknowledgement Type of funding source: None

A Description of Middle School Male Singers’ Voice Change and Voice Part Assignment

2021 ◽  
pp. 875512332110182
Author(s):  
Ryan Austin Fisher ◽  
Nancy L. Summitt ◽  
Ellen B. Koziel
Keyword(s):  
Middle School ◽  
Sixth Grade ◽  
Eighth Grade ◽  
Voice Change ◽  
Stage 4 ◽  
Public Middle School ◽  
Middle School Choir ◽  
Choral Programs ◽  
Stage 1 ◽  
The Voice

The purpose of this study was to describe the voice change and voice part assignment of male middle school choir members. Volunteers ( N = 92) were recruited from three public middle school choral programs (Grades 6-8). Participants were audio-recorded performing simple vocal tasks in order to assess vocal range and asked to share the music they were currently singing in class. Results revealed 23.91% of participants’ voices could be categorized as unchanged, 14.13% as Stage 1, 3.26% as Stage 2, 10.87% as Stage 3, 26.09% as Stage 4, and 21.74% as Stage 5. The majority of sixth-grade participants were classified as unchanged or in Stage 1 of the voice change and the majority of eighth-grade participants were classified in Stages 4 to 5 of the voice change. Of the participants labeled “tenors” in their choir, over 60% were classified as either unchanged voices or in Stage 1 of the voice change.

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