scholarly journals Internodal elongation in the grapevine (Vitis vinifera L.) : leaf influences and role of the shoot apex

OENO One ◽  
1996 ◽  
Vol 30 (4) ◽  
pp. 171
Author(s):  
Jean-Claude Fournioux
Keyword(s):  
Shoot Apex ◽  
Compensatory Growth ◽  
Longitudinal Growth ◽  
Adult Size ◽  
Apical Bud ◽  
Internodal Elongation ◽  
Terminal Bud ◽  
Young Leaves ◽  
Stimulation Of

<p style="text-align: justify;">The respective influences of the leaves and shoot apex on stimulation of internodal elongation were studied in the grapevine. Various defoliation or decapitation treatments were applied to the shoot of rooted hardwood cuttings grown in a controlled environment chamber.</p><p style="text-align: justify;">Concerning the foliar influences, the role of three sorts of leaves, in relation to their nodal position relative to the internode was analysed ; its own leaves, the leaves located below it and the young leaves neoformed above. The effects produced by excision of these different leaves show that the two adjacent leaves (below and above) of the internode play an essential role in the stimulation of its elongation. Among the subjacent leaves, these only at a position at least 6 nodes below promote internode growth. On the other hand, the young leaves neoformed in the upper part of the shoot have not influence.</p><p style="text-align: justify;">The results of decapitation experiments indicate that terminal bud contributes also to the stimulation of internodal elongation. However this influence appears only if an increment to the size (« compensatory growth ») of the leaves below the level of decapitation is not induced by the removal of the shoot tip. The leaves which realize this « compensatory growth » have indeed the ability to compensate for the laking apical bud stimulus.</p><p style="text-align: justify;">The influences vary with the stage of internode length. The longitudinal growth of very young internode (5 - 10 mm long) is stimulated by its own leaves, the terminal bud and leaves situated at least 6 nodes below. When the internode has reached at least 50 p. cent of its adult size, its elongation depends only on its own leaves and the apex. At the end of grown, only its own leaves stimulate lengthening.</p><p style="text-align: justify;">Exogenous applications of IAA, NAA and gibberellic acid (GA3) at different concentrations were also tested. GA3 at 100 mg.l<sup>-1</sup> and 1 g.l<sup>-1</sup> (incorporated to lanolin paste) applied to the cut surface of the petiole of the two adjacent leaves of young internode permits a normal elongation providing that apical bud is maintained. If the shoot is decapited the same treatment has almost the same effect only by supplying NAA at 1 g.l<sup>-1</sup> to the shoot section.</p><p style="text-align: justify;">The functions of the three elements contributing to internodal elongation are discussed, taking in consideration both the experimental results of exogenous applications of IAA, NAA and GA3, and the possible trophic role of the leaves. It is proposed that the two adjacent leaves of the internode stimulate its longitudinal growth through a production of diffusible gibberellic substances and also, probably of nutrient elements. The role of subjacent leaves is certainly of trophic nature. Terminal bud being an auxin source, we can expect that its stimulating influence is due to the supply of this growth regulator.</p>

scholarly journals New contribution to the survey of the acrotony theory on the branch of one year grapevine: III - Role of buds and leaves in development, application in the vineyard of results obtained in laboratory and greenhouse

OENO One ◽  
2001 ◽  
Vol 35 (1) ◽  
pp. 1
Author(s):  
Béchir Ezzili ◽  
M. Bejaoui
Keyword(s):  
Second Phase ◽  
Second Stage ◽  
Apical Bud ◽  
Apical Buds ◽  
Stage Of Development ◽  
Cytokinin Treatment ◽  
Young Leaves ◽  
One Year ◽  
Development Application

<p style="text-align: justify;">The respective influences of the bud and leaves on stimulation of acrotony phenomenon was studied. Defoliation (all leaves at the stage budbursted + 30 days) and various bud ablation were made : buds 9, 10 ; 7, 8, 9, 10 ; 5, 6, 7, 8, 9, 10 ; 3, 4, 5, 6, 7, 8, 9, 10.</p><p style="text-align: justify;">Concerning the phenomen of acrotony, the role of apical bud and leaves developped on at 10 and 30 days after budburst were determined.</p><p style="text-align: justify;">The effect produced by excision of the apical buds shows that the two subadjacent buds were developped. All decapitation did not increase the percentage of budbreak.</p><p style="text-align: justify;">In all decapitations, the subadjacent buds were developped however, buds below were inhibed. The effect produced by excision of leaves in the second stage of development did not promote budbreak.</p><p style="text-align: justify;">On 10 bud canes, auxins synthesized in the developing young leaves seem to exercise their inhibiting effect on the budbreak of the subjacent buds.</p><p style="text-align: justify;">Cytokinins managed by the means of our operatory mode seem to reach the subjacents buds, modify the expression of the ramification of the canes with regard to the system usual acrotony and limit the inhibition basipetally. The budburst of the canes at a temperature of 18°C seems to be more important than that at 30°C day/ 20°night. Thus, the acrotony phenomenon decreases. When the apical branches are in second phase of growth, the size of the leaves become large. It seems that the leaves would exercise their inhibitions on the subjacent buds by the slant of the synthesized gibberillins and auxins. Cytokinins have no further role to play during this phase of growth and do not thwart anymore the inhibition. In the vineyard, the ANA treatment is totally inhibiting at 20 and 50 mg/l doses. In contrast, the 6BAP treatment at 20 mg/l shortly before budburst increases the budburst percentage for Muscatel of Italy.</p><p style="text-align: justify;">When the last treatment is performed during 25 days followed by a cytokinin treatment we notice budburst. The mechanism of these different growth regulators on the acrotony phenomenon has been discussed .</p>

Demonstration of a correlation between young leaves, apex and young bunches specific to a young grapevine cutting in the first period of its development

OENO One ◽  
2001 ◽  
Vol 35 (3) ◽  
pp. 117
Author(s):  
Jean-Claude Fournioux
Keyword(s):  
Phase I ◽  
Phase Ii ◽  
Inhibitory Effect ◽  
Phase Iii ◽  
Apical Bud ◽  
Terminal Bud ◽  
Young Leaves ◽  
Hardwood Cutting ◽  
In The Beginning ◽  
Phase Iv

<p style="text-align: justify;">The development of hardwood cutting of grapevine comprise 4 succesive phases. Phase I: first period of shoot extension. Phase II: characterized by a slow growth due to a very low activity of the terminal bud. Phase III: reactivation of the growth consecutive to a resumption of the apical activity. Phase IV: when the growth becomes maximal.</p><p style="text-align: justify;">The objective of this work has been to identify the cause of the slowdown of the activity of apical bud during the phase II.</p><p style="text-align: justify;">In a first experiment, we have compared the effects of three modes of defoliation applied from the beginning of the phase II on the apical activity: total defoliation, defoliation to have two adult leaves at the base of the shoot and defoliation to have two young leaves near the apex. The results of this experiment showed that only treatments depriving the shoot of young leaves induced an activation of the plastochronic activity. So, it appeared that young leaves exercises an inhibitory effect on the apex. The same experiment has been carried out during the phase IV of cuttings development, when the apical activity was maximal. In this condition, no treatments modified the apical activity. This suggests that the inhibition of the apex by young leaves is specifie to the phase II of the develop¬ ment of a grapevine cutting. In a third experiment, we have demonstrated that the foliar inhibition persisted during the all period of the laminart growth. Cytokinins are probably implied in this competition because exogenous applications of these growth regulators during the phase II produced a stimulation of the activity of apical bud. Results of a last experiment showed that, in cuttings prerooted before budburst, the apical activity was not decreased after the phase I. In other words, in this condition, the growth of the shoot was regular without phase II. We explain this resuit as follows. The roots preformed on the cuttings produced cytokinins in sufficient quantity for provide for needs of both foliar growth and apical activity.</p><p style="text-align: justify;">In previous studies, MULLINS showed that abortion of the young bunches on cuttings of grapevine was due to an inhibition by deficiency in cytokinins exercised by young leaves.The present work reveales the existence of an exactly similar correlation between the young leaves and the apex. So, in the beginning of the development of a grapevine cutting, young leaves, apical bud and young bunches are implied in a common correlative process which results on the one hand from a small availability of cytokinins due to the lack of roots and, on the other hand from a more efficient sink effect towards the cytokinins for the young leaves than for the apex and young bunches.</p>

Foliar influences on the vegetative development of grapevine

OENO One ◽  
1997 ◽  
Vol 31 (4) ◽  
pp. 165
Author(s):  
Jean-Claude Fournioux
Keyword(s):  
Growth Arrest ◽  
Nutrient Deficiency ◽  
Growth Period ◽  
Vegetative Development ◽  
Single Leaf ◽  
Apical Bud ◽  
Terminal Bud ◽  
Young Leaves ◽  
The One ◽  
Apical Senescence

<p style="text-align: justify;">Various defoliation treatments were applied to grapevine shoots during the whole duration of the growth period: full defoliation of every shoot of vine, defoliations retaining a various number of adult leaves to the base of every shoot and defoliations retaining a various number of young leaves to the top. The effects of these treatments allow to identify the major foliar influences on the vegetative development. Total defoliation induced a lesser intemodal elongation. This result is probably due, in part, to a carbohydrates deficiency consecutive to this drastic treatment. The defoliations with variation of the number of young leaves showed that the length of internodes increased when this number was greater. This result indicates that young leaves seems exercise a morphogenetical influence on the longitudinal growth of intemodes. For the three defoliation modalities, the rythm of leaves initiation was unchanged. So, it appears that, contrary to many other species, the leaves exercise no control on the plastochronic activity of terminal bud. The results of experiments with variation of the number of leaves maintained on the shoots permit to clarify the relation between foliage and "cane ripening". The already known positive correlation between the length of the suberized part of the shoot and the number of adult leaves has been confirmed. However, the effects of these treatments indicated that this correlation was not linear. Moreover, it seems that every shoot has specific " cane ripening " potentialities determined by other factors that their foliage. The leaves seem act only as revelators of these potentialities. These same experiments retaining adult leaves showed also that such treatments induced a more growth of the not removed leaves. Their laminar extension was increased. The thickness of their lamina and so the one of their palisade parenchyma were more important that in leaves of the control. These observations confirm and explain the compensatory phenomena consecutive to a reduction of the foliar apparatus already described in previous works by other autors. The two mean results of this study consists in the demonstration of the role played by adult leaves both in growth arrest and in apical senescence towards the end of the growing season. A single leaf retained in the upper or lower part of the shoot was sufficient to cause the growth arrest. On the other hand, only old leaves inserted at the base of the shoot can produce the death of the apex. These two last results are analysed and discussed taking in consideration both our experimental results and bibliographical elements. The growth arrest is probably not only determined by the foliar influence. We can expect that a decreasing production of cytokinins by the roots contributes also to this stopping of the apical bud activity. With regard the question of the apical senescence, some results showed that this phenomenom is not caused by a nutrient deficiency. Therefore, it is a question of a correlative process in which the adult leaves inserted to the base ofthe shoot are implicated. This last foliar influence was, so far, completely unknown.</p>

Stimulation of Ca(2+)-dependent exocytosis of the sperm acrosome by cAMP acting downstream of phospholipase A2

Reproduction ◽  
2000 ◽  
pp. 57-68 ◽  
Author(s):  
J Garde ◽  
ER Roldan
Keyword(s):  
Arachidonic Acid ◽  
Phospholipase A2 ◽  
Phospholipase C ◽  
Phosphodiesterase Inhibitors ◽  
Dibutyryl Camp ◽  
Camp Phosphodiesterase ◽  
Ram Sperm ◽  
Camp Formation ◽  
Stimulation Of

Spermatozoa undergo exocytosis in response to agonists that induce Ca2+ influx and, in turn, activation of phosphoinositidase C, phospholipase C, phospholipase A2, and cAMP formation. Since the role of cAMP downstream of Ca2+ influx is unknown, this study investigated whether cAMP modulates phospholipase C or phospholipase A2 using a ram sperm model stimulated with A23187 and Ca2+. Exposure to dibutyryl-cAMP, phosphodiesterase inhibitors or forskolin resulted in enhancement of exocytosis. However, the effect was not due to stimulation of phospholipase C or phospholipase A2: in spermatozoa prelabelled with [3H]palmitic acid or [14C]arachidonic acid, these reagents did not enhance [3H]diacylglycerol formation or [14C]arachidonic acid release. Spermatozoa were treated with the phospholipase A2 inhibitor aristolochic acid, and dibutyryl-cAMP to test whether cAMP acts downstream of phospholipase A2. Under these conditions, exocytosis did not occur in response to A23187 and Ca2+. However, inclusion of dibutyryl-cAMP and the phospholipase A2 metabolite lysophosphatidylcholine did result in exocytosis (at an extent similar to that seen when cells were treated with A23187/Ca2+ and without the inhibitor). Inclusion of lysophosphatidylcholine alone, without dibutyryl-cAMP, enhanced exocytosis to a lesser extent, demonstrating that cAMP requires a phospholipase A2 metabolite to stimulate the final stages of exocytosis. These results indicate that cAMP may act downstream of phospholipase A2, exerting a regulatory role in the exocytosis triggered by physiological agonists.

scholarly journals Pre-motor versus motor cerebral cortex neuromodulation for chronic neuropathic pain

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Igor Lavrov ◽  
Timur Latypov ◽  
Elvira Mukhametova ◽  
Brian Lundstrom ◽  
Paola Sandroni ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Cerebral Cortex ◽  
Motor Cortex ◽  
Initial Assessment ◽  
Motor Cortex Stimulation ◽  
Chronic Neuropathic Pain ◽  
Long Term Effect ◽  
Stimulation Of

AbstractElectrical stimulation of the cerebral cortex (ESCC) has been used to treat intractable neuropathic pain for nearly two decades, however, no standardized approach for this technique has been developed. In order to optimize targeting and validate the effect of ESCC before placing the permanent grid, we introduced initial assessment with trial stimulation, using a temporary grid of subdural electrodes. In this retrospective study we evaluate the role of electrode location on cerebral cortex in control of neuropathic pain and the role of trial stimulation in target-optimization for ESCC. Location of the temporary grid electrodes and location of permanent electrodes were evaluated in correlation with the long-term efficacy of ESCC. The results of this study demonstrate that the long-term effect of subdural pre-motor cortex stimulation is at least the same or higher compare to effect of subdural motor or combined pre-motor and motor cortex stimulation. These results also demonstrate that the initial trial stimulation helps to optimize permanent electrode positions in relation to the optimal functional target that is critical in cases when brain shift is expected. Proposed methodology and novel results open a new direction for development of neuromodulation techniques to control chronic neuropathic pain.

scholarly journals The Role of BMP Signaling in Osteoclast Regulation

2021 ◽  
Vol 9 (3) ◽  
pp. 24
Author(s):  
Brian Heubel ◽  
Anja Nohe
Keyword(s):  
Bone Formation ◽  
Bone Morphogenetic Proteins ◽  
Bone Diseases ◽  
Bmp Signaling ◽  
Bone Homeostasis ◽  
Direct Stimulation ◽  
Federal Drug Administration ◽  
Bmp Pathway ◽  
Stimulation Of

The osteogenic effects of Bone Morphogenetic Proteins (BMPs) were delineated in 1965 when Urist et al. showed that BMPs could induce ectopic bone formation. In subsequent decades, the effects of BMPs on bone formation and maintenance were established. BMPs induce proliferation in osteoprogenitor cells and increase mineralization activity in osteoblasts. The role of BMPs in bone homeostasis and repair led to the approval of BMP2 by the Federal Drug Administration (FDA) for anterior lumbar interbody fusion (ALIF) to increase the bone formation in the treated area. However, the use of BMP2 for treatment of degenerative bone diseases such as osteoporosis is still uncertain as patients treated with BMP2 results in the stimulation of not only osteoblast mineralization, but also osteoclast absorption, leading to early bone graft subsidence. The increase in absorption activity is the result of direct stimulation of osteoclasts by BMP2 working synergistically with the RANK signaling pathway. The dual effect of BMPs on bone resorption and mineralization highlights the essential role of BMP-signaling in bone homeostasis, making it a putative therapeutic target for diseases like osteoporosis. Before the BMP pathway can be utilized in the treatment of osteoporosis a better understanding of how BMP-signaling regulates osteoclasts must be established.

scholarly journals Biofilm Lithography enables high-resolution cell patterning via optogenetic adhesin expression

2018 ◽  
Vol 115 (14) ◽  
pp. 3698-3703 ◽  
Author(s):  
Xiaofan Jin ◽  
Ingmar H. Riedel-Kruse
Keyword(s):  
Escherichia Coli ◽  
Cell Patterning ◽  
Biophysical Model ◽  
Microbial Consortia ◽  
Bacterial Biofilms ◽  
Surface Pretreatment ◽  
Resolution Cell ◽  
Stimulation Of

Bacterial biofilms represent a promising opportunity for engineering of microbial communities. However, our ability to control spatial structure in biofilms remains limited. Here we engineerEscherichia coliwith a light-activated transcriptional promoter (pDawn) to optically regulate expression of an adhesin gene (Ag43). When illuminated with patterned blue light, long-term viable biofilms with spatial resolution down to 25 μm can be formed on a variety of substrates and inside enclosed culture chambers without the need for surface pretreatment. A biophysical model suggests that the patterning mechanism involves stimulation of transiently surface-adsorbed cells, lending evidence to a previously proposed role of adhesin expression during natural biofilm maturation. Overall, this tool—termed “Biofilm Lithography”—has distinct advantages over existing cell-depositing/patterning methods and provides the ability to grow structured biofilms, with applications toward an improved understanding of natural biofilm communities, as well as the engineering of living biomaterials and bottom–up approaches to microbial consortia design.

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