Objectives and motivations of small-scale forest owners : theoretical modelling and qualitative assessment

Abstract

Long-term impacts of forest harvesting related soil disturbance on log product yields and economic potential in a New Zealand forest

Abstract

Cambium dynamics of Pinus sylvestris and Betula spp. in the northern boreal forest in Finland

Abstract

Testing a large-scale forestry scenario model by means of successive inventories on a forest property

Abstract

Study of inner ear and lateral line hair cell regeneration

Death of sensory hair cells in the inner ear results in two global health problems that millions of people around the world suffer: hearing loss and balance disorders. Hair cells convert sound vibrations and head movements into electrical signals that are conveyed to the brain, and as a result of aging, exposure to noise, modern drugs or genetic predisposition, hair cells die. In mammals, the great majority of hair cells are produced during embryogenesis, and hair cells that are lost after birth are not replaceable. However, in the last decades, researches have shown some model organisms that retain the ability to regenerate hair cells damaged after embryogenesis, such as Zebrafish and chicken, providing clues as to the cellular and molecular mechanisms that may block hair cell regeneration in mammals. This discovery initiated a search for methods to stimulate regeneration or replacement of hair cells in mammals, a search that, if fruitful, will revolutionize the treatment of hearing loss and balance disorders. One aim of my project is to study the role of retinoic acid in adult Zebrafish and in mice, which is a metabolite of vitamin A known as an essential molecule to activate hair cell regeneration after cells damaged in Zebrafish embryo. We want to study important genes involved in retinoic acid pathway, such as Aldh1a3 and RARs genes, to check what their role is in the inner ear of adult Zebrafish and compare result obtained in the inner ear of mice. On the other hand, Zebrafish lateral line contains neuromast, which are formed by the same structure than the inner ear: hair cells surrounded by supporting cells and neurons. The lateral line is a structure below the skin's surface that makes easier to damage hair cells to study their regeneration. For that reason, another aim of my project is to study how Sox2 and Atoh1, essential genes during the inner ear development, change their expression during hair cell regeneration in the lateral line. In my project, the most important concepts related to Zebrafish world are explained in order to understand why we have studied this animal and these essential genes. Then, techniques that we used are explained, with their protocol attached in the annexes. Finally, results of my project are shown, but many of them were not expected and they would be needed to follow studying.

Logging versus fire : how does disturbance type influence the abundance of Pinus strobus regeneration?

Abstract

Somatic embryogenesis and the effect of particle bombardment on banana Maçã regeneration

A plant regeneration method with cell suspension cultures of banana, and the effect of biobalistic on regeneration potential are described in this report. Somatic embryos of banana were obtained from indirect embryogenesis of male inflorescence of banana cultivar Maçã (AAB group). Part of the calluses formed (40%) showed embryogenic characteristics (nonfriable, compact and yellow color). The cell suspension, originated from embryogenic calluses, contained clusters of small tightly packed cells with dense cytoplasms, relatively large nuclei and very dense nucleoli. After four months of culture, somatic embryos started to regenerate. The maximum number of regenerated plants was observed between 45 and 60 days after embryo formation.In the first experiment, 401 plants were regenerated from approximately 10 mL of packed cells. In the second experiment, 399 plants were regenerated from a cell suspension six months older than that of the first experiment. Cell transformation using particle bombardment with three different plasmid constructions, containing the uid-A gene, resulted in a strong GUS expression five days after bombardment; however, plant regeneration from bombarded cells was much lower than nonbombarded ones.

In-vivo performance of high-density collagen gel tubes for urethral regeneration in a rabbit model.

Congenital malformations or injuries of the urethra can be treated using existing autologous tissue, but these procedures are sometimes associated with severe complications. Therefore, tissue engineering may be advantageous for generating urethral grafts. We evaluated engineered high-density collagen gel tubes as urethral grafts in 16 male New Zealand white rabbits. The constructs were either acellular or seeded with autologous smooth muscle cells, isolated from an open bladder biopsy. After the formation of a urethral defect by excision, the tissue-engineered grafts were interposed between the remaining urethral ends. No catheter was placed postoperatively. The animals were evaluated at 1 or 3 months by contrast urethrography and histological examination. Comparing the graft caliber to the control urethra at 3 months, a larger caliber was found in the cell-seeded grafts (96.6% of the normal caliber) than in the acellular grafts (42.3%). Histology of acellular and cell-seeded grafts did not show any sign of inflammation, and spontaneous regrowth of urothelium could be demonstrated in all grafts. Urethral fistulae, sometimes associated with stenosis, were observed, which might be prevented by urethral catheter application. High-density collagen gel tubes may be clinically useful as an effective treatment of congenital and acquired urethral pathologies.

TWEAK, via its receptor Fn14, is a novel regulator of mesenchymal progenitor cells and skeletal muscle regeneration.

Inflammation participates in tissue repair through multiple mechanisms including directly regulating the cell fate of resident progenitor cells critical for successful regeneration. Upon surveying target cell types of the TNF ligand TWEAK, we observed that TWEAK binds to all progenitor cells of the mesenchymal lineage and induces NF-kappaB activation and the expression of pro-survival, pro-proliferative and homing receptor genes in the mesenchymal stem cells, suggesting that this pro-inflammatory cytokine may play an important role in controlling progenitor cell biology. We explored this potential using both the established C2C12 cell line and primary mouse muscle myoblasts, and demonstrated that TWEAK promoted their proliferation and inhibited their terminal differentiation. By generating mice deficient in the TWEAK receptor Fn14, we further showed that Fn14-deficient primary myoblasts displayed significantly reduced proliferative capacity and altered myotube formation. Following cardiotoxin injection, a known trigger for satellite cell-driven skeletal muscle regeneration, Fn14-deficient mice exhibited reduced inflammatory response and delayed muscle fiber regeneration compared with wild-type mice. These results indicate that the TWEAK/Fn14 pathway is a novel regulator of skeletal muscle precursor cells and illustrate an important mechanism by which inflammatory cytokines influence tissue regeneration and repair. Coupled with our recent demonstration that TWEAK potentiates liver progenitor cell proliferation, the expression of Fn14 on all mesenchymal lineage progenitor cells supports a broad involvement of this pathway in other tissue injury and disease settings.

Somatic embryogenesis and in vitro plant regeneration from pejibaye adult plant leaf primordia

The aim of this work was to evaluate a protocol for plant regeneration by means of somatic embryos obtained from isolated adult pejibaye leaf primordia, and to describe histological origin of embryos and morphogenetic response. Explants were cultivated in modified MS medium. Mesophyll parenchymatous cells originated meristemoids (preembryonic complex formation) induced with 7.1 µM BAP in the first two subculture periods. After polarized structures with 12.9 µM NAA and 3.55 µM BAP were formed in the third subculture, somatic embryos developed and regenerated normal plants. The mesophyll parenchymatous cells display high capacity of direct response to the auxin and cytokinin.

Extracellular deposition of matrilin-2 controls the timing of the myogenic program during muscle regeneration.

Here, we identify a role for the matrilin-2 (Matn2) extracellular matrix protein in controlling the early stages of myogenic differentiation. We observed Matn2 deposition around proliferating, differentiating and fusing myoblasts in culture and during muscle regeneration in vivo. Silencing of Matn2 delayed the expression of the Cdk inhibitor p21 and of the myogenic genes Nfix, MyoD and Myog, explaining the retarded cell cycle exit and myoblast differentiation. Rescue of Matn2 expression restored differentiation and the expression of p21 and of the myogenic genes. TGF-β1 inhibited myogenic differentiation at least in part by repressing Matn2 expression, which inhibited the onset of a positive-feedback loop whereby Matn2 and Nfix activate the expression of one another and activate myoblast differentiation. In vivo, myoblast cell cycle arrest and muscle regeneration was delayed in Matn2(-/-) relative to wild-type mice. The expression levels of Trf3 and myogenic genes were robustly reduced in Matn2(-/-) fetal limbs and in differentiating primary myoblast cultures, establishing Matn2 as a key modulator of the regulatory cascade that initiates terminal myogenic differentiation. Our data thus identify Matn2 as a crucial component of a genetic switch that modulates the onset of tissue repair.

Public Art, strategies for the regeneration of public space

This paper discusses some of the key concepts in the consideration of public art as a central element in urban regeneration processes, especially in reference to its role in the processes of citizen participation.

A new heuristic method for solving spatially constrained forest planning problems based on mitigation of infeasibilities radiating outward from a forced choice

[Abstract]