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.

Floral Initiation and Development in Relation to the Time of Flowering in Banksia coccinea R.Br and B. menziesii R.Br (Proteaceae)

1990 ◽  
Vol 38 (5) ◽  
pp. 487 ◽  
Author(s):  
AM Fuss ◽  
M Sedgley
Keyword(s):  
Floral Development ◽  
Floral Initiation ◽  
Anther Dehiscence ◽  
Reproductive State ◽  
Vegetative Shoot ◽  
Stage 4 ◽  
Floral Bracts ◽  
Stage 1 ◽  
Characteristic Colour ◽  
Scanning Electron

Floral initiation and development in Banksia coccinea and B. menziesii were investigated using scanning electron microscopy in relation to the time of flowering. Floral initiation in both species occurred in late spring. The sequence of floral development was similar for both species but the timing was different. Ten stages of floral development were identified. Stage 1 was a vegetative meristem. Stage 2 signified the transition to the reproductive state, and was characterised by a broadening of the meristem with the production of involucral bracts. There were increases in both height and diameter of the meristem as common bracts (stage 3), floral bracts (stage 4) and florets (stage 5) were initiated. At stage 6 the developing inflorescences were macroscopically visible. This was followed by appearance (stage 7) and subsequent extension of the florets (stage 8). The styles continued to extend once floret extension had ceased causing the perianth to split and the styles to protrude (stage 9), thus imparting to the inflorescences their characteristic colour. Anther dehiscence occurred prior to anthesis of the floret, and the pollen was deposited on the pollen presenter, a distal modified region of the style. At anthesis (stage 10) styles were released from the perianth limb, presenting pollen to foraging insects and birds. Phyllotaxy was spiral throughout development, with a transition from a single genetic spiral in the vegetative shoot to 13 spirals initiating simultaneously in the developing inflorescence. Floral development was slow, taking from 6 to 8 months in B. menziesii prior to peak anthesis between April and July. In B. coccinea macroscopic inflorescences were not observed until May, with peak anthesis occurring between August and November, 9-12 months after initiation. Inflorescence colour showed wide variation in both species, with red and pink being the dominant colours in B. coccinea and B. menziesii respectively.

scholarly journals Source-Sink Relationship and Protea Postharvest Leaf Blackening

1995 ◽  
Vol 120 (3) ◽  
pp. 475-480 ◽  
Author(s):  
Jingwei Dai ◽  
Robert E. Paull
Keyword(s):  
Respiration Rate ◽  
Developmental Stages ◽  
Sucrose Solution ◽  
Soluble Solids ◽  
Fresh Weight ◽  
Nectar Production ◽  
Total Soluble Solids ◽  
Stage 4 ◽  
Stage 1 ◽  
Source Sink

The inflorescence of Protea neriifolia B. Br. was two-thirds of the total cut floral stem fresh weight and significantly influenced blackening of the attached 20 to 30 leaves. Floral stems harvested at five developmental stages were characterized for inflorescence diameter, fresh and dry weights, respiration, and nectar production. Inflorescence diameter and fresh and dry weights increased from stage 1 (very tight bud) to stage 5 (bracts reflexed). Respiration rate was high in stages 1 and 3. Nectar production began at stage 4 (open, cylindrical flower) and increased from 2.7 to 9.8 ml per flower with 15% to 23.5% total soluble solids as the flower opened. Postharvest inflorescence diameter, respiration rate, and nectar production increased and leaf blackening decreased when floral stems were placed in 5% (w/v) sucrose solution. Application of 14C-sucrose to a leaf subtending the inflorescence lead to >50% of the radioactivity being found in the nectar within 24 hours. These data indicate that leaf blackening in protea is the result of depletion of carbohydrate by the inflorescence, and that this depletion is primarily due to the sugar demand for nectar production.

scholarly journals Crop Injury from Sublethal Rates of Herbicide. II. Cucumber

HortScience ◽  
2001 ◽  
Vol 36 (4) ◽  
pp. 674-676 ◽  
Author(s):  
James P. Gilreath ◽  
Carlene A. Chase ◽  
Salvadore J. Locascio
Keyword(s):  
Developmental Stages ◽  
Total Yield ◽  
Field Studies ◽  
Growth And Yield ◽  
Fresh Weight ◽  
Stages Of Development ◽  
Plant Vigor ◽  
Stage 4 ◽  
Stage 1 ◽  
Dichlorophenoxy Acetic Acid

Cucumber (Cucumis sativus L.) growth and yield in response to application of sublethal rates of 2,4-D at several developmental stages were evaluated in field studies during two seasons. In Expt. 1, prebloom applications of 2,4-D amine reduced plant vigor and increased foliar epinasty as rates increased from 0 to 112 g·ha-1. Early and total fruit yields also declined linearly as 2,4-D rates increased; 112 g·ha-1 2,4-D reduced early yield by 25% and total yield by 20%. In Expt. 2, plant vigor declined with increasing rates of 2,4-D applied at all four stages of development from first true leaf to early fruit enlargement; however, response at stage 1 differed with time after application. Epinasty increased with 2,4-D rate when applied at all developmental stages; however the severity of the response varied with time after application for stages 1, 2, and 3, but not for stage 4. Averaged over all developmental stages, vine length, fresh weight, and yield decreased linearly as rates increased. Early and total yields with 112 g·ha-1 were 22% and 19% lower than those of nontreated plants, respectively. Growth inhibition and yield decline, pooled across 2,4-D rates, were greater when exposure occurred at the earlier stages of development. Chemical name used: (2,4-dichlorophenoxy)acetic acid (2,4-D).

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.

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.

Detection of floral initiation in broccoli (Brassica oleracea L. var. italica Plenck) based on electron micrograph standards of shoot apices

1998 ◽  
Vol 38 (3) ◽  
pp. 313 ◽  
Author(s):  
D. K. Y. Tan ◽  
A. H. Wearing ◽  
K. G. Rickert ◽  
C. J. Birch
Keyword(s):  
Brassica Oleracea ◽  
Apical Meristem ◽  
Scanning Electron Micrographs ◽  
Floral Initiation ◽  
Floral Primordia ◽  
Initiation Stage ◽  
Stage 1 ◽  
Future Work ◽  
Brassica Oleracea L ◽  
Stage Stage

Summary. Detecting floral initiation is fundamental to predicting the ontogeny of broccoli (Brassica oleracea L. var. italica Plenck). Scanning electron micrographs of the apical meristem of broccoli (cv. ‘Fiesta’) were made for the transition from the vegetative to advanced reproductive stage. Seven identifiable stages were observed. During the early vegetative stage (stage 1), the apical meristem was a small, pointed, shoot tip surrounded by leaf primordia. The transitional stage (stage 2) was marked by a widening and flattening to form a dome-shaped apical meristem. In the floral initiation stage (stage 3), the 1st-order floral primordia were observed in the axils of the developing bracts. Further work from a field experiment showed that apex diameter at floral initiation averaged 500 ± 3 m when examined under a light microscope. Apex diameter was not affected by photoperiod, planting time or cultivar. These descriptions and micrographs will enhance broccoli research by standardising the descriptions of floral development in broccoli, and will also be used as the basis of future work in the field identification of floral initiation and the prediction of the timing of phenological events in broccoli.

Morphological indicators and the time of transition to flower in Ptilotus nobilis (Amaranthaceae)

2012 ◽  
Vol 60 (7) ◽  
pp. 625
Author(s):  
Sybille Orzek ◽  
Richard R. Williams ◽  
Margaret E. Johnston
Keyword(s):  
Leaf Area ◽  
Apical Meristem ◽  
Developmental Stages ◽  
Floral Initiation ◽  
Total Leaf Area ◽  
Node Number ◽  
Total Leaf ◽  
Leaf Area Expansion ◽  
Electron And Light Microscopy ◽  
Area Expansion

Floral initiation of Ptilotus nobilis (Lindl.) F.Muell. was investigated by both scanning electron and light microscopy to develop a template for the transition from vegetative to reproductive growth. Four developmental stages were identified, including two vegetative and two reproductive stages. Bract initiation was accompanied by a significant increase in meristem area and diameter, and was defined as the onset of flowering. At the transition, meristem diameters and areas increased 1.5 and 2.3 times, respectively. Most morphological traits, including leaf number, mean leaf area and total leaf area, increased gradually at the time of transition and were further investigated in a subsequent glasshouse trial. Floral initiation occurred very early and at 25 days after sowing all plants had entered the reproductive phase. At the onset of flowering leaf and node number increased significantly with 3.6 and 4.2, respectively. Branching and leaf area expansion were identified as post-initiation processes, and increased by 2.8 (total foliage area), 3.3 (total leaf area) and 1.8 (mean leaf area). During the vegetative phase a discolouration of the shoot apical meristem was noted and underlying reasons are discussed.

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

scholarly journals Probing the floral developmental stages, bisexuality and sex reversions in castor (Ricinus communis L.)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sujatha Thankeswaran Parvathy ◽  
Amala Joseph Prabakaran ◽  
Thadakamalla Jayakrishna
Keyword(s):  
Developmental Stages ◽  
Ricinus Communis ◽  
Sex Expression ◽  
Pistil Abortion ◽  
Ricinus Communis L ◽  
Sex Reversion ◽  
Stage 4 ◽  
Meristem Development ◽  
Male Specific ◽  
First Time

AbstractCastor (Ricinus communis L) is an ideal model species for sex mechanism studies in monoecious angiosperms, due to wide variations in sex expression. Sex reversion to monoecy in pistillate lines, along with labile sex expression, negatively influences hybrid seed purity. The study focuses on understanding the mechanisms of unisexual flower development, sex reversions and sex variations in castor, using various genotypes with distinct sex expression pattern. Male and female flowers had 8 and 12 developmental stages respectively, were morphologically similar till stage 4, with an intermediate bisexual state and were intermediate between type 1 and type 2 flowers. Pistil abortion was earlier than stamen inhibition. Sex alterations occurred at floral and inflorescence level. While sex-reversion was unidirectional towards maleness via bisexual stage, at high day temperatures (Tmax > 38 °C), femaleness was restored with subsequent drop in temperatures. Temperature existing for 2–3 weeks during floral meristem development, influences sexuality of the flower. We report for first time that unisexuality is preceded by bisexuality in castor flowers which alters with genotype and temperature, and sex reversions as well as high sexual polymorphisms in castor are due to alterations in floral developmental pathways. Differentially expressed (male-abundant or male-specific) genes Short chain dehydrogenase reductase 2a (SDR) and WUSCHEL are possibly involved in sex determination of castor.

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