Restoration of Cymodocea nodosa (Uchria) Ascherson seagrass prairies through seed propagation. Germination in vitro, plantlet acclimation and transplanting to natural meadows.

[EN] The seagrass Cymodocea nodosa (Ucria) Ascherson is the most abundant seagrass species in the Canary Islands (Spain), where it forms dense submerged, ecologically relevant communities as stable and protected habitats. As with other seagrasses, concern has arisen due to a decline in the number and extension of the communities as the result of adverse activities in coastal areas. Seed germination and planting are assumed as cost-effective method for restoration. In the frame of the restoration of natural populations of Cymodocea nodosa, pilot experiences not tested so far in the Canary Islands have been carried out to developed in vitro techniques to produce viable seedlings and its transference to the natural environment.

Influence of pollination and seed dispersal on the genetic population structure of two Commiphora species in Madagascar and South Africa

Pollination and seed dispersal are important ecological processes for the regeneration of plant populations and both vectors for gene exchange between plant populations. For my thesis, I studied the pollination ecology of the South African tree Commiphora harveyi (Burseraceae) and compared it with C. guillauminii from Madagascar. Both species have low visitation rates and a low number of pollinating insect species, resulting in a low fruit set. While their pollination ecology is very similar, they differ in their seed dispersal with a low seed dispersal rate in the Malagasy and a high seed dispersal rate in the South African species. This should be reflected in a stronger genetic differentiation among populations in the Malagasy than in the South African species. My results, based on AFLP markers, contradict these expectations, the overall differentiation was lower in the Malagasy (FST = 0.05) than in the South African species (FST = 0.16). However, at a smaller spatial scale (below 3 km), the Malagasy species was genetically more strongly differentiated than the South African species, which was reflected by the high inter-population variance within the sample site (C. guillauminii: 72.2 - 85.5 %; C. harveyi: 8.4 - 14.5 %). This strong differentiation could arise from limited gene flow, which was confirmed by spatial autocorrelation analyses. The shape of the autocorrelogram suggested that gene exchange between individuals occurred only up to 3 km in the Malagasy species, whereas up to 30 km in the South African species. These results on the genetic structure correspond to the expectations based on seed dispersal data. Thus, seed dispersal seems to be a key factor for the genetic structure in plant populations on a local scale.

Expression profiling in developing peach seed and mesocarp as affected by growth regulators

Jasmonates (JAs) and spermidine (Sd) influence fruit (and seed) development and ripening. In order to unravel their effects in peach fruit, at molecular level, field applications of methyl jasmonate (MJ) and propyl dihydrojasmonate (PDJ), and Sd were performed at an early developmental stage (late S1). At commercial harvest, JA-treated fruit were less ripe than controls. Realtime RT-PCR analyses confirmed a down-regulation of ethylene biosynthetic, perception and signaling genes, and flesh softening-related genes. The expression of cell wall-related genes, of a sugar-transporter and hormone-related transcript levels was also affected by JAs. Seeds from JA-treated fruit showed a shift in the expression of developmental marker genes suggesting that the developmental program was probably slowed down, in agreement with the contention that JAs divert resources from growth to defense. JAs also affected phenolic content and biosynthetic gene expression in the mesocarp. Levels of hydroxycinnamic acids, as well as those of flavan-3-ols, were enhanced, mainly by MJ, in S2. Transcript levels of phenylpropanoid pathway genes were up-regulated by MJ, in agreement with phenolic content. Sd-treated fruits at harvest showed reduced ethylene production and flesh softening. Sd induced a short-term and long-term response patterns in endogenous polyamines. At ripening the up-regulation of the ethylene biosynthetic genes was dramatically counteracted by Sd, leading to a down-regulation of softening-related genes. Hormone-related gene expression was also altered both in the short- and long-term. Gene expression analyses suggest that Sd interfered with fruit development/ripening by interacting with multiple hormonal pathways and that fruit developmental marker gene expression was shifted ahead in accord with a developmental slowing down. 24-Epibrassinolide was applied to Flaminia peaches under field conditions early (S1) or later (S3) during development. Preliminary results showed that, at harvest, treated fruit tended to be larger and less mature though quality parameters did not change relative to controls.

Frugivores, seed dispersal and tree regeneration along a human disturbance gradient in East African tropical rainforests

Samenausbreitung und Regeneration von Bäumen sind wichtig für den langfristigen Bestand von Baum- und Frugivorengemeinschaften in tropischen Regenwäldern. Zunehmende Rohdung und Degradation gefährden den Ablauf dieser mutualistischen Prozesse in diesem Ökosystem. Um den Einfluss von kleinräumiger menschlicher Störung auf die Frugivorengemeinschaft und die zentralen Ökosystemprozesse Samenausbreitung und Regeneration zu erforschen, habe ich 1) die Frugivorengemeinschaft und die Samenausbreitungsrate von Celtis durandii (Ulmaceae) und 2) den Zusammenhang zwischen Baumarten mit fleischigen Früchten, Frugivoren und der Etablierung von Keimlingen dieser Baumarten in unterschiedlich stark gestörten Flächen dreier ostafrikanischer tropischer Regenwälder untersucht. Insgesamt konnte ich 40 frugivore Vogel- und Primatenarten in den drei untersuchten Waldgebieten nachweisen. Auf gering gestörten Flächen wurden mehr Frugivore als auf stark gestörten Flächen aufgenommen. Auch die Beobachtungen an C. durandii ergaben mehr frugivore Besucher in Bäumen auf gering gestörten als auf stark gestörten Flächen. Dies führte zu einer marginal signifikant höheren Samenausbreitungsrate auf den gering gestörten Flächen. Diese Ergebnisse waren auf regionaler Ebene in allen drei untersuchten Wäldern konsistent. Dies zeigt, dass kleinräumige Störung einen umfassenderen negativen Einfluss auf Frugivore und ihre Funktion als Samenausbreiter hat als zuvor angenommen. Bei der Vegetationserfassung nahm ich 131 verschiedene Baumarten mit fleischigen Früchten in den drei Regenwäldern auf. Kleinräumige menschliche Störung erhöhte den Artenreichtum dieser Baumarten marginal signifikant, hatte jedoch keinen direkten Einfluss auf die Frugivorendichte und den Artenreichtum von Keimlingen dieser Baumarten. Der Artenreichtum von Baumarten mit fleischigen Früchten zeigte einen marginal signifikant positiven Einfluss auf die Frugivorendichte, allerdings nicht auf die Keimlinge. Allerdings führte die Dichte der Frugivoren zu signifikant erhöhtem Artenreichtum der Keimlinge. Folglich scheint kleinräumige Störung die Keimlingsetablierung indirekt durch erhöhten Baumartenreichtum und erhöhte Frugivorendichte zu beeinflussen. Die Frugivorendichte hatte einen größeren Einfluss auf die Waldregeneration als kleinräumige Störung und Baumartenreichtum. Demnach scheint kleinräumige menschliche Störung sowohl positive als auch negative Effekte auf Samenausbreitung und Regeneration zu haben. Somit sind weitere Studien notwendig, die den Einfluss von kleinräumiger menschlicher Störung auf Mutualismen tropischer Regenwälder aufklären.

Isolamento, variabilità ed espressione del gene PIMT in Girasole

Il vigore è un aspetto rilevante della qualità delle sementi, strettamente connesso al loro status fisiologico, al genotipo e alle condizioni di stoccaggio. Stress ossidativi e danni alle macromolecole sono alla base del deterioramento del seme, che è equipaggiato con sistemi protettivi e di riparazione. Uno di questi coinvolge l’L-isoaspartil metiltransferasi (PIMT) che ripara i misfolding proteici catalizzando la riconversione in aspartato dell’isoaspartile anomalo accumulato. Scopo di questo studio era valutare il possibile ruolo del meccanismo di riparazione di PIMT nel vigore del seme in girasole. Per questo il relativo gene è stato isolato e caratterizzato, la variabilità allelica determinata su un campione di linee inbred e l’espressione genica misurata in risposta all’invecchiamento accelerato (aging) e al priming. La sequenza codificante ottenuta è costituita da 4 esoni e contiene i 5 domini caratteristici delle metiltransferasi. Il gene mostra elevata similarità con gli ortologhi vegetali e scarsa diversità nucleotidica nei genotipi coltivati rappresentativi della variabilità della specie. Nella sequenza aminoacidica, comunque, sono state rinvenute tre sostituzioni che potrebbero influenzare la funzionalità enzimatica. Dal punto di vista fisiologico i genotipi considerati hanno esibito notevole variabilità di risposte ai trattamenti, sia in termini di vigore che di espressione genica. Aging e priming hanno prodotto generalmente gli effetti attesi, rispettivamente negativi e positivi, sulla germinabilità e sulla sua velocità. In generale l’espressione di PIMT è risultata massima nel seme secco, come riportato altrove, e ridotta dall’aging. Anche il priming ha diminuito l’espressione rispetto al seme quiescente, mentre il suo effetto dopo l’aging è risultato genotipo-dipendente. Tuttavia, nelle condizioni descritte, non si sono evidenziate correlazioni significative tra vigore ed espressione di PIMT, tali da suggerire un chiaro ruolo di questo meccanismo nella qualità fisiologica del seme.

Controlled reproduction in Anguilla anguilla (L.): advanced studies on broodstock management, spawning techniques and system design for artificial seed production.

The thesis aims to expose the advances achieved in the practices of captive breeding of the European eel (Anguilla anguilla). Aspects investigated concern both approaches livestock (breeding selection, response to hormonal stimulation, reproductive performance, incubation of eggs) and physiological aspects (endocrine plasma profiles of players), as well as engineering aspects. Studies conducted on various populations of wild eel have shown that the main determining factor in the selection of wild females destined to captive breeding must be the Silver Index which may determine the stage of pubertal development. The hormonal induction protocol adopted, with increasing doses of carp pituitary extract, it has proven useful to ovarian development, with a synchronization effect that is positively reflected on egg production. The studies on the effects of photoperiod show how the condition of total darkness can positively influence practices of reproductions in captivity. The effects of photoperiod were also investigated at the physiological level, observing the plasma levels of steroids ( E2, T) and thyroid hormones (T3 and T4) and the expression in the liver of vitellogenin (vtg1 and vtg2) and estradiol membrane receptor (ESR1). From the comparison between spontaneous deposition and insemination techniques through the stripping is inferred as the first ports to a better qualitative and quantitative yield in the production of eggs capable of being fertilized, also the presence of a percentage of oocytes completely transparent can be used to obtain eggs at a good rate of fertility. Finally, the design and implementation of a system for recirculating aquaculture suited to meet the needs of species-specific eel showed how to improve the reproductive results, it would be preferable to adopt low-flow and low density incubation.

Seed fate and seedling dynamics after masting in two African rain forest trees

How the effects of biotic factors are moderated by abiotic factors, and their consequences for species interactions, is generally understudied in ecology. A key abiotic feature of forests is regular canopy disturbances that create temporary patches, or “gaps,” of above-average light availability. Co-occurring in lowland primary forest of Korup National Park (Cameroon), Microberlinia bisulcata and Tetraberlinia bifoliolata are locally dominant, ectomycorrhizal trees whose seeds share predator guilds in masting years. Here, we experimentally tested the impact of small mammal predators upon seedling abundance, growth, and survivorship. In 2007, we added a fixed density of seeds of each species to exclosures at 48 gap–understory locations across 82.5 ha within a large Microberlinia grove, and at 15 locations outside it. For both species, small mammals removed more seeds in gaps than in understory, whereas this was reversed for seeds killed by invertebrates. Nonetheless, Microberlinia lost twice as many seeds to small mammals, and more to invertebrates in exclosures, than Tetraberlinia, which was more prone to a pathogenic white fungus. After six weeks, both species had greater seedling establishment in gaps than understory, and in exclosures outside compared to exclosures inside the grove. In the subsequent two-year period, seedling growth and survivorship peaked in exclosures in gaps, but Microberlinia had more seedlings' stems clipped by animals than Tetraberlinia, and more than twice the percentage of leaf area damaged. Whereas Microberlinia seedling performance in gaps was inferior to Tetraberlinia inside the grove, outside it Microberlinia had reduced leaf damage, grew taller, and had many more leaves than Tetraberlinia. No evidence was found for “apparent mutualism” in the understory as seedling establishment of both species increased away from (>25 m) large stems of either species, pointing to “apparent competition” instead. In gaps, Microberlinia seedling establishment was lower near Tetraberlinia than conspecific adults because of context-dependent small mammal satiation. Stage-matrix analysis suggested that protecting Microberlinia from small mammals could increase its population growth rate by 0.06. In the light of prior research we conclude that small mammals and canopy gaps play an important role in promoting species coexistence in this forest, and that their strong interaction contributes to Microberlinia's currently very poor regeneration.

Quantification of network perfusion in ASL cerebral blood flow data with seed based and ICA approaches

Independent component analysis (ICA) or seed based approaches (SBA) in functional magnetic resonance imaging blood oxygenation level dependent (BOLD) data became widely applied tools to identify functionally connected, large scale brain networks. Differences between task conditions as well as specific alterations of the networks in patients as compared to healthy controls were reported. However, BOLD lacks the possibility of quantifying absolute network metabolic activity, which is of particular interest in the case of pathological alterations. In contrast, arterial spin labeling (ASL) techniques allow quantifying absolute cerebral blood flow (CBF) in rest and in task-related conditions. In this study, we explored the ability of identifying networks in ASL data using ICA and to quantify network activity in terms of absolute CBF values. Moreover, we compared the results to SBA and performed a test-retest analysis. Twelve healthy young subjects performed a fingertapping block-design experiment. During the task pseudo-continuous ASL was measured. After CBF quantification the individual datasets were concatenated and subjected to the ICA algorithm. ICA proved capable to identify the somato-motor and the default mode network. Moreover, absolute network CBF within the separate networks during either condition could be quantified. We could demonstrate that using ICA and SBA functional connectivity analysis is feasible and robust in ASL-CBF data. CBF functional connectivity is a novel approach that opens a new strategy to evaluate differences of network activity in terms of absolute network CBF and thus allows quantifying inter-individual differences in the resting state and task-related activations and deactivations.