Studies on the rosette plant Hieracium floribundum.: I. Observations related to flowering and axillary bud development

1972 ◽  
Vol 50 (1) ◽  
pp. 73-78 ◽  
Author(s):  
Edward C. Yeung ◽  
R. L. Peterson
Keyword(s):  
Structural Changes ◽  
Seed Set ◽  
Flower Induction ◽  
Flower Stalk ◽  
Histochemical Change ◽  
Physiological Basis ◽  
Bud Development ◽  
Histological Studies ◽  
Experimental Approaches ◽  
Rosette Plant

Hieracium floribundum is a rosette species requiring a number of long days for flower induction. Histological studies of vegetative, transition, and floral apices showed the structural changes associated with flower induction in this species. One striking histochemical change observed was the absence of starch in vegetative apices and the accumulation and retention of quantities of starch in prefloral and floral apices. A study of initiation and development of axillary buds at the time of flowering revealed that there was a gradient in the potential to flower shown by these buds along the developing flower stalk to the base of the plant. The buds in the axils of upper peduncle bracts always develop as capitula while the apices of the buds in the axils of the next few bracts assume the shape of floral buds but fail to develop unless the upper developing inflorescences are removed. Buds in the axils of the lowest bracts and upper (youngest) leaves have the potential to form rosettes, stolons, or inflorescences depending on the environmental conditions in which the plants are grown. Buds formed in the lower (oldest) leaf axils normally fail to grow out until after seed set when a few may develop as rosettes. Possible explanations for these results are discussed, and some experimental approaches being used to elucidate the physiological basis for bud expression are indicated.

The Plant-Physiological Basis of Flower Induction in the Control of Fruit Production

2008 ◽  
pp. 110-119 ◽  
Author(s):  
Martin Hegele ◽  
Fritz Bangerth ◽  
Daruni Naphrom ◽  
Pawin Manochai ◽  
Pittaya Sruamsiri ◽  
...  
Keyword(s):  
Fruit Production ◽  
Flower Induction ◽  
Physiological Basis

Reproductive ecology of Dryas integrifolia in the high Arctic semi-desert

1996 ◽  
Vol 74 (9) ◽  
pp. 1451-1460 ◽  
Author(s):  
P. G. Krannitz
Keyword(s):  
Seed Dispersal ◽  
Seed Set ◽  
High Arctic ◽  
The Arctic ◽  
Bet Hedging ◽  
Crop Failure ◽  
Flower Stalk ◽  
Insect Visitation ◽  
Solar Noon ◽  
Seed Data

Flowering and fruiting of Dryas integrifolia were studied at Igloolik and Pangnirtung to analyse the importance of variation in heliotropy and flower size to seed set and weight. In addition, peduncle elongation and seed plume length were also studied to analyse variation in seed dispersal characters. At both Igloolik and Pangnirtung, most Dryas flowers were not heliotropic throughout the course of the day, but in general, pointed towards the solar noon sun. Benefits to orienting toward the sun were warmer gynoecial temperatures, heavier seeds, and more insect visitation (though not percent seed set). Flowers varied in size from 1.2 to 2.7 cm in diameter and differed in size between plants. Even though larger flowers did not point towards the solar noon sun more than smaller flowers, they had heavier and proportionally more seeds. Variation in peduncle elongation suggests the potential for conservative dispersion when a flower has produced only a few propagules: flowers with fewer or no seeds had shorter stalks. Similarly, with good seed production, a bet hedging strategy is apparent: seeds located at the centre of the receptacle had much longer plumes than those at the perimeter of the seed head. All seed data were from Pangnirtung; the cold summer in 1986 at Igloolik resulted in a complete seed crop failure. Despite the adversity of the arctic climate, there are moderate summers during the lifetime of perennial plants such as D. integrifolia in which adaptations like those described in this study benefit the production of sexual offspring. Keywords: heliotropism, flower stalk elongation, basking insects, seed dispersal, insolation, bet hedging.

scholarly journals EFFECT OF LEAD ON STRUCTURAL CHANGES IN LIVER OF WISTAR RATS UNDER THE CONDITIONS OF ACUTE EXPERIM

2021 ◽  
Vol 11 (2) ◽  
pp. 17-19
Author(s):  
Oleg Zayko ◽  
Vadim Astashov ◽  
Anna Sindireva ◽  
Karina Basnakyan ◽  
Arina Lukyanchikova
Keyword(s):  
Lead Acetate ◽  
Wistar Rats ◽  
Structural Changes ◽  
Structural Transformations ◽  
Acute Experiment ◽  
Acetate Solution ◽  
Hydropic Degeneration ◽  
Histological Studies ◽  
Lead Salts ◽  
Lead Acetate Solution

The purpose of this study was to evaluate the structural transformations of Wistar rats liver after oral administration of lead salts. Under the conditions of acute experiment during 5 days the Wistar rats were orally administered the lead acetate solution in the amount of 3 mg/kg. Histological studies were carried out at OSMU upon the completion of the experiment. Effect of toxic doses of lead causes symptoms of both steatosis and hydropic degeneration of the liver. It is assumed that the appearance of hepatic steatosis reflects the reaction of hepatocytes to hemic hypoxia caused by the action of lead, while the signs of hydropic degeneration expressed in varying degrees reflect its direct toxic effect.

Flower Induction and Flower Bud Development in Apple and Sweet Cherry

2010 ◽  
Vol 24 (1) ◽  
pp. 1549-1558 ◽  
Author(s):  
Nikolaos Koutinas ◽  
Gueno Pepelyankov ◽  
Valentin Lichev
Keyword(s):  
Sweet Cherry ◽  
Flower Induction ◽  
Flower Bud ◽  
Bud Development ◽  
Flower Bud Development

scholarly journals Structural insights into the mechanism of oxidative activation of heme-free H-NOX from Vibrio cholerae

2020 ◽  
Vol 477 (6) ◽  
pp. 1123-1136
Author(s):  
Roma Mukhopadhyay ◽  
Kelly N. Chacón ◽  
Jacqueline M. Jarvis ◽  
Marat R. Talipov ◽  
Erik T. Yukl
Keyword(s):  
Nitric Oxide ◽  
Vibrio Cholerae ◽  
Disulfide Bonds ◽  
Structural Changes ◽  
Redox Sensor ◽  
Zinc Binding Site ◽  
Oxidative Activation ◽  
Experimental Approaches ◽  
Heme Cofactor ◽  
Structural Insights

Bacterial heme nitric oxide/oxygen (H-NOX) domains are nitric oxide (NO) or oxygen sensors. This activity is mediated through binding of the ligand to a heme cofactor. However, H-NOX from Vibrio cholerae (Vc H-NOX) can be easily purified in a heme-free state that is capable of reversibly responding to oxidation, suggesting a heme-independent function as a redox sensor. This occurs by oxidation of Cys residues at a zinc-binding site conserved in a subset of H-NOX homologs. Remarkably, zinc is not lost from the protein upon oxidation, although its ligation environment is significantly altered. Using a combination of computational and experimental approaches, we have characterized localized structural changes that accompany the formation of specific disulfide bonds between Cys residues upon oxidation. Furthermore, the larger-scale structural changes accompanying oxidation appear to mimic those changes observed upon NO binding to the heme-bound form. Thus, Vc H-NOX and its homologs may act as both redox and NO sensors by completely separate mechanisms.

Bud-autogamy in the velvet-leaf blueberry, Vaccinium myrtilloides Michx.

2006 ◽  
Vol 86 (1) ◽  
pp. 245-250 ◽  
Author(s):  
Merrit Noormets ◽  
A. Randall Olson
Keyword(s):  
Reproductive Success ◽  
Key Words ◽  
Seed Set ◽  
Full Bloom ◽  
Flower Buds ◽  
Bud Development ◽  
Self Pollination ◽  
Lowbush Blueberry ◽  
Pollen Tetrad ◽  
Vaccinium Myrtilloides

In velvet-leaf blueberry, Vaccinium myrtilloides Michx., flower buds at different stages of development were collected from managed, lowbush blueberry populations and examined microscopically for evidence of autodeposition of selfpollen. During late bud development, anther pores opened for pollen tetrad release and remained relatively close to the stigma. Just prior to full bloom, at petal separation, 18% of the flower buds were pollinated. Self-pollination prior to anthesis may either ensure some reproductive success or enhance the seed set from subsequent cross pollinations. Key words: Vaccinium, autogamy, self-pollination

scholarly journals Impairment and Compensation in Dexterous Upper-Limb Function After Stroke. From the Direct Consequences of Pyramidal Tract Lesions to Behavioral Involvement of Both Upper-Limbs in Daily Activities

2021 ◽  
Vol 15 ◽  
Author(s):  
Agnès Roby-Brami ◽  
Nathanaël Jarrassé ◽  
Ross Parry
Keyword(s):  
Upper Limb ◽  
Structural Changes ◽  
Motor Behavior ◽  
Pyramidal Tract ◽  
Individual Performance ◽  
Compensatory Mechanism ◽  
Personal Factors ◽  
Limb Function ◽  
Physiological Basis ◽  
Upper Limb Function

Impairments in dexterous upper limb function are a significant cause of disability following stroke. While the physiological basis of movement deficits consequent to a lesion in the pyramidal tract is well demonstrated, specific mechanisms contributing to optimal recovery are less apparent. Various upper limb interventions (motor learning methods, neurostimulation techniques, robotics, virtual reality, and serious games) are associated with improvements in motor performance, but many patients continue to experience significant limitations with object handling in everyday activities. Exactly how we go about consolidating adaptive motor behaviors through the rehabilitation process thus remains a considerable challenge. An important part of this problem is the ability to successfully distinguish the extent to which a given gesture is determined by the neuromotor impairment and that which is determined by a compensatory mechanism. This question is particularly complicated in tasks involving manual dexterity where prehensile movements are contingent upon the task (individual digit movement, grasping, and manipulation…) and its objective (placing, two step actions…), as well as personal factors (motivation, acquired skills, and life habits…) and contextual cues related to the environment (presence of tools or assistive devices…). Presently, there remains a lack of integrative studies which differentiate processes related to structural changes associated with the neurological lesion and those related to behavioral change in response to situational constraints. In this text, we shall question the link between impairments, motor strategies and individual performance in object handling tasks. This scoping review will be based on clinical studies, and discussed in relation to more general findings about hand and upper limb function (manipulation of objects, tool use in daily life activity). We shall discuss how further quantitative studies on human manipulation in ecological contexts may provide greater insight into compensatory motor behavior in patients with a neurological impairment of dexterous upper-limb function.

scholarly journals Immunomorphologic transformation of the appendix of rabbits after antigenic loading using anti-pneumococcal prophylactic preparation «Pneumo-Pro»

2018 ◽  
Vol 20 (83) ◽  
pp. 235-239
Author(s):  
Ya.V. Kisera ◽  
D.M. Levkivsky ◽  
Yu.G. Storchak
Keyword(s):  
Immune System ◽  
Structural Changes ◽  
Morphological Changes ◽  
Abdominal Cavity ◽  
Vermiform Appendix ◽  
Lymphoid Cells ◽  
High Concentration ◽  
Peripheral Part ◽  
Protective Function ◽  
Histological Studies

Despite a widespread introduction of immunoprophylaxis, the national scientific literature doesn’t frequently deal with the data containing a detailed description of the morphological state of the immune system’s central and peripheral organs, as well as their immunomorphological rearrangement after the use of vaccines and the effects of immunostimulants. It is also worth noting that such organ of the peripheral immune system as a vermiform appendix was mainly ignored by the domestic scientists. The vermiform appendix is a lymphoepithelial organ that performs a protective function and relates to the peripheral part of the immune system. The development, proliferation and differentiation of immunocompetent cells occurs inside this important formation, first and foremost, of B-cell subpopulations. Vermiform appendix is sometimes called the tonsils of the abdominal cavity due to the high concentration of lymphoid cells in it. We did not find a detailed description of the morphological changes of the rabbits’ vermiform appendix that occur after the introduction of immunobiological drugs. We conducted the histological studies of the vermiform appendix of rabbits after performing an antigenic stress using the vaccine against streptococcal and staphylococcal infections of animals along with the preventive agent «Pneumo-Pro» separately and combined with Selefer, a selenium-containing immunostimulant. Histological studies of the rabbits’ vermiform appendix performed after the parenteral introduction of immunoprophylactic drugs revealed significant structural changes in the lymphoid apparatus: there is a significant amount of lymphoblasts in the center of submucosal lymphoid nodes; mitosis of lymphocytes is often visualized; large, medium and small lymphocytes as well as macrophages locate in the dome of submucosal lymphoid nodes; there are numerous volumetric clusters of lymphoid tissue that form submucosal clusters of lymphoid nodes in the plate and submucosal basis of the appendix; the peripheral part of the lymphoid nodes and the interfollicular area contain a significant number of T-lymphocytes; the vast majority of secondary lymphoid follicles are cone-shaped; appendix crypts contain a large number of exocrinocysts.

Relationship in annual species of Medicago. II. Interspecific crosses between M. tornato (L.) Mill. and M. littoralis Rhode.

1965 ◽  
Vol 16 (1) ◽  
pp. 51 ◽  
Author(s):  
JP Simon
Keyword(s):  
Pollen Fertility ◽  
Structural Changes ◽  
Seed Set ◽  
Morphological Characteristics ◽  
Pollen Sterility ◽  
Interspecific Crosses ◽  
Annual Species ◽  
Reciprocal Crosses ◽  
Meiotic Irregularities ◽  
Early Seedling

Six hybrids were obtained from 212 reciprocal crosses between M. littoralis Rhode and M. tornata (L.) Mill. The hybrids were chlorophyll-deficient in the early seedling stage but later development was normal although growth was retarded. The morphological characteristics were intermediate between those of the parents. Pollen fertility and seed set amounted to 7 and 10% respectively. Meiotic irregularities indicate that M. littoralis is differentiated from M. tornata by at least one translocation. The contribution of the structural changes in the chromosomes accounted for about 60% of the observed pollen sterility.

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