Differences In Regeneration Rate Research Articles

In vitro culture initiation and regeneration of two highly productive clones of poplar

In vitro shoot regeneration is a fast and reliable method for propagation of valuable tree genotypes and important step in genetic manipulations. This study aimed to establish an optimal in vitro culture initiation and regeneration protocol for highly productive poplar clones ‘Novoberlinska-3’ (Populus pyramidalis × P. laurifolia) and ‘Volosystoplidna’ (P. trichocarpa). In vitro culture was initiated either on MS (IM-MS) or WPM (IM-WPM) medium both containing BAP (0.2 mg.L-1) and IBA (0.1 mg.L-1). Results demonstrated that the best initiation medium for the clone ‘Volosystoplidna’ was IM-WPM on which 93.3 % of explants survived, while explants from ‘Novoberlinska-3’ better survived on IM-MS. After establishing both genotypes into aseptic culture, regeneration experiments were started using two types of explants, leaf and petioles, planted on callus induction medium containing 2iP (1.02 mg.L-1) and NAA (1.86 mg.L-1). Furthermore, microshoots were placed on shoot induction medium supplemented with 0.04 mg.L-1 thidiazuron, and then transferred on shoot elongation medium with 0.2 mg.L-1 BAP. Regeneration protocol showed better performance of poplar ‘Novoberlinska-3’, but it was also efficient for ‘Volosystoplidna’. Plant regeneration from leaf explants in the clone ‘Novoberlinska-3’ showed the highest regeneration percentage (92.3 %) and the number of shoots per explant (3.1), which significantly exceeded other explants. Our results showed a significant difference between the survivability of two clones during culture initiation. The differences in regeneration rates between the clones as well as leaf and petiole explants were also determined. Obtained aseptic cultures of highly productive poplar hybrids will be used in our further studies, especially for genetic transformation.

Tissue and spine regeneration in the temperate sea urchin Psammechinus miliaris

The tissue regenerative capabilities of echinoderms are well known at the morphogenic level, yet significant knowledge gaps remain concerning the molecular control of these processes. This pilot study assayed two pharmacological agents (vincristine sulphate and DAPT) injected directly into the body cavity of specimens of the temperate echinoid Psammechinus miliaris which had had their spines and tube feet deliberately amputated. Vincristine sulphate, which is a generalised mitotic inhibitor, was used as a positive control, whereas DAPT is a y-secretase inhibitor known to block sea urchin embryo development and suppress echinoid regeneration by interfering with Notch signalling pathways. Significant differences in regeneration rate became apparent in both treatments 29 days post amputation with both inhibitors slowing regeneration of tube feet (0.6 μg/g vincristine sulphate by 44.4% relative to controls; 4 μg/g DAPT by 55.6% relative to controls) and spines (0.6 μg/g vincristine sulphate by 53.3% relative to controls; 4 μg/g DAPT by 66.7% relative to controls). Vincristine sulphate was more clearly dose-dependent than DAPT. This initial inhibition-based approach allows inferences to be made concerning possible molecular pathways controlling regeneration within P. miliaris and adds further support to the hypothesis that Notch signalling plays a major role in regulating regeneration in echinoids.

Exploring Relationships of Exposure, Pharmacodynamic Changes and Gene Expression to Clinical Outcome in Adults with Acute Lymphoblastic Leukemia Receiving Inotuzumab Ozogamicin

▪BackgroundInotuzumab ozogamicin (InO) is a targeted antibody-drug conjugate (ADC) under development for treatment of patients with relapsed or refractory CD22-positive acute lymphoblastic leukemia (ALL) and non-Hodgkin's Lymphoma. Correlative analyses from an open-label, Phase 1/2 study (B1931010) included exploring the relationship between InO pharmacokinetic exposure, hematologic measures, and gene expression to treatment response.MethodsPatients received 2 to 3 weekly intravenous doses of InO by 1 hour infusion over a 28-day cycle for ≤ 6 cycles (table).Blood samples were drawn during Days 1 and 15 of Cycles 1 and 2 (at 0, 1 and 3 h), and Day 1 of Cycle 4 (at 0 and 1 h) for concentration determination of InO and unconjugated calicheamicin in serum. Samples were analyzed using a validated LC/MS/MS procedure. InO levels were correlated to CD22 protein expression on CD19+ B-lymphocytes in blood and bone marrow, and to minimum residual disease. Lymphocyte regeneration was described using a linear mixed-effects model. To explore the relationship between clinical outcome and expression of genes such as those involved in DNA damage response and apoptosis, optional blood samples for gene expression analysis were collected on Cycle 1 Day 1 and Cycle 1 Day 15 [each at pre- and post-dose time-points]. These samples were assessed for baseline gene expression and gene expression changes using 96-gene TaqMan Low Density Array cards.ResultsUnconjugated calicheamicin levels were below the limit of quantitation (50 pg/mL) for most patients and time points. Treatment-related decreases in CD22 antigen expression on lymphocytes were rapid but unrelated to InO concentration. Lymphocyte depletion in blood was also rapid, consistently observed regardless of InO dose, and followed by slow regeneration with substantial inter-patient differences in regeneration rate. Percentage of bone marrow blasts was directly related to InO elimination rate. With treatment, as blast percentage decreased, InO elimination rate decreased by approximately 50% by Cycle 4 (ie, after 10 dosing events) compared to the first dose. In bone marrow, lower disease burden at baseline tended to be associated with faster regeneration of lymphocytes during the follow-up period. Patients achieving minimal residual disease (MRD)-negativity tended to have higher peak and trough serum concentrations of InO throughout each cycle compared to patients not achieving MRD-negativity. There was no observed correlation between percentage of blasts at baseline and MRD-negativity. CD22 mRNA levels in blood decreased approximately 10-fold by Day 15 relative to baseline, consistent with selective killing of CD22-positive leukemic blasts by InO. This decrease was more pronounced in subjects who exhibited complete response with/without incomplete platelet count recovery with no evidence of MRD than in subjects who did not exhibit clinical response (p=0.001 using Wilcoxon Rank Sum Test). In addition, multiple other transcripts exhibited decreases following InO administration, including mRNAs encoded by genes regulating proliferation (cyclin-dependent kinase 2), DNA repair (XRCC2), and cell death (death-associated protein kinase 1).ConclusionIn patients with ALL receiving InO, CD22 protein expression and lymphocyte count decreased rapidly, followed by slow and variable regeneration, as patients with low disease blast counts at baseline exhibited faster recovery of their counts than those with higher levels. While CD22 expression is not a significant determinant of InO concentration, the number of doses administered did influence drug elimination rate; an effect thought to be associated with target-mediated drug clearance. In related fashion, patients achieving MRD-negativity tended to have higher InO concentrations following InO treatment. Changes in mRNA profiles in blood consistent with the mechanism of action of InO were evident. The extent of reduction in CD22 mRNA was associated with clinical outcome. Study is ongoing for long term follow up. [Display omitted] DisclosuresFostvedt:Pfizer Inc: Employment, Other: stock ownership. Laird:Pfizer Inc: Employment, Other: Stock ownership. Marshall:Pfizer Inc: Employment, Other: Stock ownership. Li:Pfizer Inc: Employment, Other: Stock ownership. Boni:Pfizer Inc: Employment, Other: Stock ownership.

Hamstring Tendon Regeneration After Harvesting

Background: Hamstring tendons are often used as autografts for anterior cruciate ligament (ACL) reconstruction. However, no systematic review has been performed describing consequences such as hamstring tendon regeneration rate and determinants of hamstring tendon regeneration. Purpose: To summarize the current literature regarding hamstring tendon rate regeneration, the time course of regeneration, and determinants of hamstring regeneration. Study design: Systematic review. Methods: A search was performed in the Embase, Medline (OvidSP), Web of Science, Cochrane, PubMed, and Google Scholar databases up to June 2014 to identify relevant articles. A study was eligible if it met the following inclusion criteria: tendons were harvested, regeneration at harvest site was assessed, population size was at least 10 human subjects, full-text article was available, and the study design was either a randomized controlled trial, prospective cohort study, retrospective cohort study, or case control study. A risk of bias assessment of the eligible articles was determined. Data describing hamstring tendon regeneration rates were pooled per time period. Results: A total of 18 publications met the inclusion criteria. The mean regeneration rate for the semitendinosus and gracilis tendons was, in all cases, 70% or higher. More than 1 year after harvesting, 79% (median [IQR], 80 [75.5-90]) of the semitendinosus tendons and 72% (median [IQR], 80 [61-88.5]) of the gracilis tendons were regenerated. No significant differences in regeneration rate could be found considering patient sex, age, height, weight, or duration of immobilization. Results did not clearly show whether absence of regeneration disadvantages the subsequent hamstring function. Five studies measured the regeneration rate at different moments in time. Conclusion: Hamstring tendons regenerated in the majority of patients after ACL reconstruction. The majority of the hamstring tendon regeneration was found to occur between 1 month and 1 year after harvest. No significant determinants for hamstring tendon regeneration could be identified because of a lack of research. The function and strength of the regenerated hamstring remained unclear.

Size‐dependence of growth and mortality influence the shade tolerance of trees in a lowland temperate rain forest

Summary 1. A trade-off between growth in high-light and survival in low-light of species is often proposed as a key mechanism underpinning the dynamics of trees in forest communities. Yet, growth and survival are known to depend on plant size and few studies have analysed how this trade-off can vary between juvenile life stages and the potential consequences of the trade-off for the differences in regeneration rate between species in mixed forests. 2. We quantified growth and mortality for two different juvenile life stages ‐ seedlings and saplings ‐ of seven tree species common in temperate rain forests in New Zealand using data from field studies. We found strong evidence that the ranking of species for survival in shade and growth in full light was affected by size. There was a trade-off between seedling survival in low light and sapling height growth in high light, but no trade-offs were observed when considering other combinations of life stages (seedling growth vs. seedling survival, seedling growth vs. sapling survival, or sapling growth vs. sapling survival). 3. We ran simulations with an individual-based forest dynamics model ‐ SORTIE/NZ ‐ to explore how the trade-off drives the differences in tree species regeneration success in gaps vs. under closed forest conditions. These simulations indicate that because species’ ranks in shade tolerance varied with life stage, regeneration success was not predicted from knowledge of tree performance at a single life stage. For instance, high-light sapling growth was a strong determinant of regeneration success in forest gaps, but seedling growth was also influential. Under closed forest, regeneration success was primarily limited by low-light mortality at the seedling stage, but seedling growth and sapling survival were also influential. 4. Synthesis. Growth-survival trade-offs can be strongly affected by the size of the individual analysed, resulting in completely different rankings of the shade tolerance of species across different juvenile life stages. Performance of both seedlings and saplings influenced regeneration success, highlighting the need to consider growth-survival trade-offs and the shade-tolerance strategies of tree species over a large range of juvenile sizes.

Lesion regeneration in the branching coral Acropora palmata:effects of colonization, colony size, lesion size, and lesion shape

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 197:209-215 (2000) - doi:10.3354/meps197209 Lesion regeneration in the branching coral Acropora palmata: effects of colonization, colony size, lesion size, and lesion shape Diego Lirman* Center for Marine and Environmental Analyses, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Cswy, Miami, Florida 33149, USA *E-mail: dlirman@rsmas.miami.edu ABSTRACT: The regeneration of lesions caused by the fragmentation of Acropora palmata colonies was examined in the northern Florida Reef Tract, USA. The recovery of A. palmata lesions followed a negative exponential model. Lesion regeneration was influenced by the initial size and perimeter of lesions, but was not affected by the presence of colonizers or the size of the colonies or fragments bearing the lesions. Significant differences in regeneration rates were found among small (0-5 cm2), medium (5-10 cm2), and large (10-20 cm2) lesions. The largest lesions (>20 cm2) did not show a significant recovery over time. When the total area recovered during the first 30 d was normalized to initial perimeter length, both small and large lesions regenerated similar amounts of tissue. However, closure rates (the rate of movement of the growing lip towards the center of the lesion) were significantly faster for small lesions (7.3 [SE = 1.3] mm mo-1) compared to medium (4.9 [0.4] mm mo-1) and large (4.3 [0.3] mm mo-1) lesions. Results of this study support previous studies suggesting that the regeneration process is sustained by a limited, initial amount of energy that may be determined by the extent of damage experienced by the colony. KEY WORDS: Coral lesions · Lesion regeneration · Acropora palmata · Coral fragmentation · Lesion size and shape Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 197. Publication date: May 12, 2000 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 2000 Inter-Research.

Correlation of axonal regeneration and slow component B in two branches of a single axon

We investigated the relationship between slow axonal transport and axonal regeneration in the rat dorsal root ganglion (DRG) cell. The DRG cell sends out a single axon which bifurcates within the ganglion; one axon proceeds centrally into the spinal cord and the other proceeds peripherally. The rate of axonal regeneration is approximately 2 times faster for the peripheral processes (4.6 +/- 0.9 mm/day) than for the central processes (2.1 +/- 0.5 mm/day). The peripheral and central processes regenerate through dissimilar environments (sciatic nerve and dorsal root, respectively); thus, environmental factors may account for the differences in regeneration rates. We tested this possibility by measuring the regeneration of motoneuron axons within the ventral root (histologically similar to the dorsal root). The motoneuron regeneration rate within the ventral root is similar to the motoneuron regeneration rate within the sciatic nerve, suggesting that factors within the DRG cell produce the differences in regeneration rate. Slow axonal transport is classified into two distinct components: slow component a (SCa), corresponding to the microtubule/neurofilament network of the axonal cytoskeleton, and slow component b (SCb), corresponding to the microfilament complex/axoplasmic matrix. The transport rate of SCa and SCb in the peripheral sensory axons is approximately 2 times faster than their counterparts in the central sensory axons. SCa moves at 1.0 to 3.0 mm/day in the peripheral processes and 0.5 to 1.0 mm/day in the central processes; SCb moves at 3.5 to 6.5 mm/day in the peripheral processes and 2.0 to 3.5 mm/day in the central processes. In each branch of the DRG cell, the rate of axonal regeneration is similar to the rate of SCb transport. These results support the hypothesis that SCb is a rate-limiting factor in axonal regeneration because of its role in providing the cytoskeletal elements which are directly involved in the motility of the growth cone and elongation of the axon.

Studies on Limb Regeneration in the Anomurans Pagurus Longicarpus and Emerita Talpoida

ABSTRACT After autotomy of 1 to 4 appendages, Pagurus longicarpus regenerated and molted rapidly. There was no significant difference in regeneration rate or time to ecdysis in crabs with differing numbers of limbs removed. This is different from many brachyurans studied in which regeneration rate and ecdysis are accelerated by multiple autotomy. Emeritatalpoida exhibited a very weak autotomy reflex and very poor regenerative ability. The few crabs which developed limb buds did so after molting. These findings are discussed with reference to adaptive value of autotomy and regeneration, and likelihood of limb loss in nature.

The effect of light on forelimb regeneration in the newt

The forelimb of the newt, Triturus (Notophthalamus) viridescens, was bilaterally amputated and the animals subjected to different photoperiods during the period of regeneration, namely (1) continuous light, (2) 15 hours of light/day and (3) total darkness. Animals exposed to continuous light reached the palette regeneration stage four to five days before those kept in total darkness with the 15 hours of light/day animals being intermediate. The difference in regeneration rate was first evident in the moderate early stage (blastema accumulation stage); it then increased during subsequent stages and the difference persisted during the observation period. In an attempt to determine whether the retina was the receptor of light affected, some animals were blinded at the time of amputation and subjected to continuous light. Their rate of regeneration was similar to sighted animals subjected to continuous light but greater than sighted animals in total darkness. The pineal is discussed as the likely mediator of the photo effect.

Influence of Temperature on Rate of Regeneration in the Time-graded Regeneration Field in Planarians

ABSTRACT The aim of the experiments was to see how different levels in the time-graded head-regeneration field of two species, differing strongly as to the characteristics of the field, might behave at different temperatures. As was expected, regeneration was retarded for all levels by lowering the temperature. Regeneration of heads was retarded relatively more strongly at posterior levels of the field. Some characteristic differences in regeneration rates of the two species were found, leading to certain suggestions as to the possible nature of the field. By lowering the temperature regeneration may be separated into two main components : formation of the blastema and differentiation of the cells. Formation of the blastema is not seriously impeded at temperatures below 5–6° C., whereas the differentiation processes are nearly brought to a stop at these low temperatures. Doubt is therefore cast on the hypothesis of an adaptive value of regenera-tion in view of the fact that several planarian species actually live and reproduce at temperatures well below those necessary for regeneration.