scholarly journals 559 Preferential Allocation and Inducible Calcium Sinks in Leaf Primordia of Dracaena sanderiana Hort. Sander ex M.T. Mast (Dracaenaceae)

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 492B-492
Author(s):  
Svoboda V. Pennisi ◽  
Dennis B. McConnell ◽  
Michael E. Kane
Keyword(s):  
Potassium Nitrate ◽  
Leaf Primordia ◽  
Crystal Formation ◽  
Limited Capacity ◽  
Nucleation Sites ◽  
Immature Leaf ◽  
Integral Role ◽  
Intracellular Ca ◽  
Leaf Tissues ◽  
Limited Induction

We induced preferential allocation of Ca to two calcium oxalate (CO) sinks in immature leaf tissues of D. sanderiana: subepidermal extracellular deposits and intracellular raphides. Allocation was affected by exogenous Ca levels. Two groups of rooted cuttings were termed Ca-deficient and non-deficient. The first group consisted of cuttings that had been deprived of Ca for 18 months, and, the second, cuttings rooted under standard horticultural conditions. All plants were grown in liquid medium supplemented with 100 ppm of potassium nitrate and subjected to 0, 3, or 7mm Ca from calcium acetate. The most striking feature of Ca-deficient plants grown in 0 mm Ca was the absence of intracellular raphides in the leaf primordia. The largest number of intracellular raphides developed in Ca-deficient plants grown in 7 mm Ca. The number of extracellular crystals in Ca-deficient plants grown in Ca-supplemented solutions versus non-supplemented were similar, but crystals were considerably smaller in non-supplemented plants. Total number of extracellular crystals per epidermal cell did not differ significantly between plants in all treatments. This implies that nucleation sites are pre-determined and finite in number. In contrast, the number of intracellular raphides was highly variable. In terms of Ca prioritization, the extracellular crystals took precedence over intracellular raphides, and this was most obvious in Ca-deficient plants. The significance of this research is that the extracellular crystals represent Ca sinks with limited induction capacity compared to intracellular Ca sinks. Plants with genetic predisposition for intracellular CO crystal formation may be able to respond favorably to root environments with low Ca levels compared to species with limited capacity for intracellular CO deposition. Intracellular CO crystals, therefore, play an integral role in plant nutrition as Ca storage sinks.

Shell regeneration in Helix: shell matrix composition and crystal formation

1969 ◽  
Vol 47 (6) ◽  
pp. 1107-1111 ◽  
Author(s):  
A. S. M. Saleuddin ◽  
Wilson Chan
Keyword(s):  
Chemical Nature ◽  
Early Stage ◽  
Organic Matrix ◽  
Matrix Composition ◽  
Crystal Formation ◽  
Shell Matrix ◽  
Nucleation Sites ◽  
Small Crystals ◽  
Short Period ◽  
Shell Regeneration

The chemical nature of the electron-dense areas appearing on the organic matrix during the early stage of shell regeneration in Helix has been ascertained. These areas of 500–5000 Å are made up mainly of acid mucopolysaccharides as detected by thorium staining. When treated by 1% phosphotungstic acid (PTA) for a short period, these electron-dense areas took up the stain, suggesting the presence of mucoprotein and glycoproteins, and are probably the nucleation sites for calcification because small crystals of CaCO3 appear with them. The small crystals join to form larger ones. Crystals grow presumably by dendritic growth, and eventually form a calcified layer. Electron diffraction studies on these crystals show the presence of aragonite (type present in the normal shell) and calcite.

scholarly journals Inducible Calcium Sinks and Preferential Calcium Allocation in Leaf Primordia of Dracaena sanderiana Hort. Sander ex M.T. Mast. (Dracaenaceae)

HortScience ◽  
2001 ◽  
Vol 36 (7) ◽  
pp. 1187-1191 ◽  
Author(s):  
Svoboda V. Pennisi ◽  
Dennis B. McConnell
Keyword(s):  
Calcium Oxalate ◽  
Epidermal Cell ◽  
Leaf Primordia ◽  
Deionized Water ◽  
Crystal Nucleation ◽  
Rooted Cuttings ◽  
Nucleation Sites ◽  
Dracaena Sanderiana

The effect of 0, 3, and 7 mm Ca2+ on the allocation and deposition of Ca2+ into intracellular and sub-cuticular periplasmic calcium oxalate (CO) crystals was examined in leaf primordia of rooted cuttings of Dracaena sanderiana Hort. Sander ex M.T. Mast. Crystal development was monitored in two types of cuttings, those rooted in deionized water for 18 months and those rooted in Metro Mix 500 for 6 weeks. Response differed remarkably depending on the type of cutting. Cuttings rooted in deionized water deposited sub-cuticular crystals at the expense of intracellular crystals (raphides). The number of sub-cuticular crystals in leaf primordia of cuttings rooted in deionized water grown in solutions supplemented with either 0, 3, or 7 mm Ca2+ was similar, but crystals were considerably smaller in plants grown in 0 mm Ca2+. Sub-cuticular crystals appeared developmentally earlier in leaf primordia of all cuttings grown in either 3 mm or 7 mm Ca2+ than in cuttings rooted in deionized water grown in 0 mm Ca2+. This finding supports the premise that deposition of sub-cuticular crystals is modulated by Ca2+ levels and could be induced at an earlier ontogenetical stage by raising rhizospheric Ca2+ levels or delayed by lowering rhizospheric Ca2+ levels. The total number of sub-cuticular crystals per epidermal cell did not differ significantly between treatments implying that crystal nucleation sites are predetermined and finite in number. In contrast, the formation of intracellular raphides was highly variable and depended on Ca2+ concentrations. In terms of Ca2+ prioritization, sub-cuticular CO crystals took precedence over intracellular CO raphides.

Self-Organized Metal Oxide Exhibiting Enhanced Bioactivity

2006 ◽  
Vol 53 ◽  
pp. 17-21
Author(s):  
Robert L. Karlinsey ◽  
Anderson T. Hara ◽  
Clif W. Duhn
Keyword(s):  
Self Assembly ◽  
Salt Content ◽  
Crystal Formation ◽  
Nucleation Kinetics ◽  
Self Organized ◽  
Nucleation Sites ◽  
Organization Process ◽  
Prior Hypothesis ◽  
Supersaturated Solutions

Self-assembled niobium oxide microcones produced by potentiostatic anodization with varied NaF content (between 100 and 250 mg) in an HF electrolyte are shown to nucleate mineral when immersed in supersaturated solutions emulating mineral content in saliva and blood. The most extensive mineral coverage in 100 mL of 2.5 wt. % HF electrolyte occurs when NaF content is about 100 mg with substantial mineral formation occurring within 24 hours. Higher salt content apparently alters the conditions favoring mineral nucleation by generating smaller nucleation centers that ultimately diminish the extent of mineral coverage. Additionally, nucleation kinetics and morphological contrasts between mineral formed from saliva and blood is briefly discussed in terms of the relative degree of supersaturation with respect to hydroxyapatite. Finally, we show that the integrity of the microcone shape is not critical for mineral nucleation, an observation that builds on our prior hypothesis by promoting the importance of self-assembly and crystal formation. Based on these results, we demonstrate the influence of NaF and stress the role of the self-organization process in producing effective mineral nucleation sites.

Capacity for somatic embryogenesis of adult oil palm genitors (Elaeis guineensis, var. Pisifera) from immature leaf tissues

2020 ◽  
Vol 131 ◽  
pp. 229-239 ◽  
Author(s):  
Raphael Ferreira Almeida ◽  
Filipe Sathler Meira ◽  
Hugo Teixeira Gomes ◽  
Talita Aparecida Balzon ◽  
Patrícia Monah Cunha Bartos ◽  
...  
Keyword(s):  
Somatic Embryogenesis ◽  
Oil Palm ◽  
Elaeis Guineensis ◽  
Immature Leaf ◽  
Leaf Tissues

Enhancing Techniques for Studying Mitotic Peanut Chromosomes1

1994 ◽  
Vol 21 (2) ◽  
pp. 92-94 ◽  
Author(s):  
J. S. Dhesi ◽  
H. T. Stalker
Keyword(s):  
Chromosome Numbers ◽  
Chromosome Counts ◽  
Ploidy Levels ◽  
Immature Leaf ◽  
Dividing Cells ◽  
Leaf Tissues ◽  
Root Tissues ◽  
Mitotic Cells

Abstract Peanut chromosomes are small and preparations of well-spread, darkly stained mitotic cells can be difficult to obtain. Techniques developed for wheat were adapted to peanut. The results are highly reproducible and many dividing cells with darkly stained chromosomes can usually be observed when root tissues are used for preparation. Applications also can be made for determining ploidy levels and chromosome numbers of plants by using immature leaf tissues. The technique has application for both diploids and polyploids and is suitable for both chromosome counts and karyotyping studies.

scholarly journals Concomitant genetic ablation of L-type Cav1.3 (α1D) and T-type Cav3.1 (α1G) Ca2+ channels disrupts heart automaticity

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Matthias Baudot ◽  
Eleonora Torre ◽  
Isabelle Bidaud ◽  
Julien Louradour ◽  
Angelo G. Torrente ◽  
...  
Keyword(s):  
Sinus Node ◽  
Atrioventricular Node ◽  
Pacemaker Activity ◽  
Genetic Ablation ◽  
Voltage Gated ◽  
Integral Role ◽  
Intracellular Ca ◽  
Cardiac Automaticity ◽  
Ca2 Channels

Abstract Cardiac automaticity is set by pacemaker activity of the sinus node (SAN). In addition to the ubiquitously expressed cardiac voltage-gated L-type Cav1.2 Ca2+ channel isoform, pacemaker cells within the SAN and the atrioventricular node co-express voltage-gated L-type Cav1.3 and T-type Cav3.1 Ca2+ channels (SAN-VGCCs). The role of SAN-VGCCs in automaticity is incompletely understood. We used knockout mice carrying individual genetic ablation of Cav1.3 (Cav1.3−/−) or Cav3.1 (Cav3.1−/−) channels and double mutant Cav1.3−/−/Cav3.1−/− mice expressing only Cav1.2 channels. We show that concomitant loss of SAN-VGCCs prevents physiological SAN automaticity, blocks impulse conduction and compromises ventricular rhythmicity. Coexpression of SAN-VGCCs is necessary for impulse formation in the central SAN. In mice lacking SAN-VGCCs, residual pacemaker activity is predominantly generated in peripheral nodal and extranodal sites by f-channels and TTX-sensitive Na+ channels. In beating SAN cells, ablation of SAN-VGCCs disrupted late diastolic local intracellular Ca2+ release, which demonstrates an important role for these channels in supporting the sarcoplasmic reticulum based “Ca2+clock” mechanism during normal pacemaking. These data implicate an underappreciated role for co-expression of SAN-VGCCs in heart automaticity and define an integral role for these channels in mechanisms that control the heartbeat.

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