Orientador: Tânia Marcia Costa / Banca: Rodrigo Egydio Barreto / Banca: Ronaldo Adriano Christofoletti / Resumo: O presente trabalho teve como objetivo avaliar parâmetros comportamentais e químicos entre o caranguejo-aranha Libinia spinosa e sua anêmona Calliactis tricolor. Três hipóteses foram testadas através de experimentos laboratoriais. O experimento 01 testou qual sexo e estágio de maturidade de L. spinosa interage de maneira mais eficiente com C. tricolor. Foram utilizados 10 réplicas de cada grupo demográfico do caranguejo (a exceção de fêmeas jovens, com apenas 06 réplicas) e 3 anêmonas (previamente fixadas em uma pedra) para cada réplica. Os resultados indicam que os caranguejos adultos fixam mais anêmonas (G=4,7596;p=0,0291) e são mais rápidos para encontrá-las (F=5,03970;p=0,031814), e as fêmeas ovigeras fixam mais anêmonas (G=5,3002;p=0,0213) quando comparadas as fêmeas não ovigeras. O experimento 2 avaliou se o reconhecimento entre os parceiros depende de estímulo visual ou químico. Foram utilizadas apenas fêmeas ovígeras para os demais experimentos, baseado nos resultados do experimento 1. Dois tratamentos foram utilizados: 1) uma anêmona atrás de uma placa preta opaca; 2) uma anêmona atrás de uma placa transparente. Não foram observadas diferenças entre os tratamentos (T=0,978763;p=0,347018), o que nos indica que os caranguejos encontram as anêmonas por pistas químicas. No experimento 3 foi testado o tempo e a duração do reconhecimento e aclimatação entre L. spinosa e C. tricolor. Em uma primeira fase todos os exemplares (21) de L. spinosa fixaram uma anêmona; após 3h de fixação foram separados. Na seqüência, 4 tratamentos se seguiram: Tratamento 1 e 2: 3h de separação e novo contato com a mesma anêmona, e com outra anêmona, respectivamente; Tratamento 3 e 4: 4 dias de separação e novo contato com a mesma anêmona, e com outra anêmona, respectivamente. Não houve diferença em nenhum dos tratamentos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present research aimed to assess behavioral and chemical parameters between spider-crab Libinia spinosa and its symbiotic sea anemone Calliactis tricolor. Three hypotheses were tested through laboratorial experiments. The experiment 1 tested which genre and age of L. spinosa interacts more efficiently with C. tricolor. Were used 10 replications of each demographic group of spider-crabs (except young females, only with 6 replications) and 3 anemones (previously placed in one rock) for each replication. The results suggested that adult spider-crabs placed more (G=4,7596;p=0,0291) and readily find anemones (F=5,03970;p=0,031814) and the ovigerous females placed more anemones (G=5,3002;p=0,0213) compared with non-ovigerous. The experiment 2 evaluated if reconnaissance between partners depends on visual or chemical cues. The other experiments used only ovigerous females, based on results of experiment 1. Two treatments were used: 1) one anemone behind opaque black plate; 2) one anemone behind translucid plate. There were no differences between treats (T=0,978763;p=0,347018), indicating that crabs find anemones through chemical cues. The experiment 3 tested the time and duration of reconnaissance and acclimation between L. spinosa and C. tricolor. In the first phase all specimens (21) of L. spinosa placed one anemone; and were separated after 3 hours of placement. Further, 4 treatments followed: Treatment 1 and 2: 3 hours separated and new contact with the same and other anemone, respectively; Treatment 3 and 4: 4 days separated and new contact with the same and other anemone, respectively. There were no difference among treats (Treatment 1: T=0,236853;p=0,816202; Treatment 2: T=0,856921;p=0,402754; Treatment 3: T=0,743289;p=0,478564; Treatment 4: T=-1,52701;p=0,157747), indicating that acclimation period do not persist when partners were separated... (Complete abstract click electronic access below) / Mestre

Nitrogen (N) is present in proteins, enzymes, cell structures, purines and pyrimidines in DNA and RNA molecules, photosynthetic pigments, and several other types of molecules in all living organisms. Nonetheless, even though N makes up more than 78% of the atmosphere, it is reported to be the most frequent deficient nutrient in plants. Nitrate (NO3-) and ammonium (NH4+) are the N forms absorbed by plants from soil, but legume crops can establish symbiotic relationships with rhizobia bacteria, and fix N2 from the atmosphere. In soybean, increasing yield and protein content are raising the crop's N requirement; therefore, enhanced N2 fixation is seen as a reliable path to avoid the use of N fertilizers. In this study, the objective was to perform a comprehensive screening in greenhouse and field conditions of soybean genotypes for traits related to N2 fixation. The purpose was to identify among the soybean genotypes different N2 fixation profiles at early and late stages, as well as to investigate their capacity to accumulate above-ground N and supply carry-over N to following crops. The results showed different profiles among the soybean genotypes for early and late N2 fixation capacity, both in greenhouse and field evaluations. Different traits were correlated to either early or late N2 fixation activity. Soybean and winter-rye shoot dry mass were evaluated in the field to assess above-ground N accumulation and carry-over N, respectively. Soybean genotypes were identified with specific capacities to accumulate N in above-ground biomass or supply N to winter-rye. The patterns of N2 fixation identified in this study, as well as the different abilities to accumulate N above-ground or supply N to following crops, could assist in the selection of superior lines with improved N2 fixation capacity.

Current bioinformatic methods such as molecular phylogenetics and phylogenomics provide us with good insight to symbiont evolution. Though modern science evolves rapidly, accelerates speed of acquiring novel discoveries and improves their quality, there is still endless row of questions waiting to be answered. This thesis focuses on origins of symbiosis between insects and Enterobacteria, and the mechanisms promoting association of bacteria with arthropods. The main emphasis is put on the secondary symbionts of the genus Sodalis (Enterobacteriaceae) and the pathogenic Anaplasma phagocytophilum (Anaplasmataceae) that seems to be undergoing first steps to become hereditary mutualist.

No description available.

1. Convoluta roscoffensis is an intertidel flatworm symbiotic with the green alga, Platymonas convolutae. Field studies of a population of Convoluta on Shell Beach, Herm, Channel Islands, involved the measurement of seasonal changes in numbers of Convoluta and in environmental conditions. Features of the habitat were measured, including the nutrient levels in the beach run-off water flowing over Convoluta colonies and the light energy available. 2. The position of the colonies on the beach meant that they received about 60% of available PAR (photosynthetically active radiation) i.e. 4883 E m-2 in 1977. The spacing of worms in the colonies (mean density 9.3 x 10 to the power 5 worms m-2) was such that they did not haye to shade each other. 3. Nutrient analyses revealed that the beach run-off water is rich in nutrients, and dominated by nitrate (mean concentration 6-16υg atoms N03-N 1to the power -1). Uptake of nutrients from the run-off water by Convoluta was not apparent. 4. The Convoluta population was most abundant in September and numbers were lowest in May and June. This pattern of fluctuation in numbers showed some relation to seasonal changes in light intensity but not to changes in nutrient levels. 5. Primary productivity measurements (using the 14C technique) of symbiotic and free-living Platymonas showed that both types of algae achieved assimilation numbers (mg carbon fixed (mg chlorophyll 'a')-1 h-1) which were in the range 1-3. Photosynthetic rate was higher in worms incubated in Herm run-off water than in offshore seawater. Comparisons between symbiotic and free-living Platymonas were made with respect to photoinhibiting light levels and the amounts of dark carbon fixation. 6. Extrapolation of primary productivity values to Convoluta in the field gave an estimated annual production of 872.9 g carbon m to the power -2 of colony for 1977. This is comparable with values for rich ocean waters and coral reefs. 7. Primary production measurements were also made on a tropical algal-invertebrate system, Zoanthus sociatus, at Discovery Bay, Jamaica. The oxygen technique was used, so the values of assimilation number were not directly comparable with those obtained for Convoluta, but the symbionts of Zoanthus (Gymnodinium microadriaticum) achieved assimilation numbers similar to those published for other free-living species of Gymnodinium. The symbionts isolated from Zoanthus were of similar size to and contained similar amounts of chlorophyll 'a' to the Platymonas symbionts of Convoluta. 8. Structural studies of the development of symbiosis in Convoluta showed that the host and symbiont are in very intimate contact. There was evidence for the controlled and integrated growth of host and symbiont in the distribution and orientation of the 20,000-70,000 algae inside Convoluta. The ratios of algal to host protein and cell volume were measured and compared with values for other algal-invertebrate systems to discover whether any general statements may be made regarding the proportions of algal to host tissue in established symbioses.

The arbuscular mycorrhizal (AM) symbiosis is a mutualistic relationship between plants and AM fungi that increases global plant nutrition. Although the benefits of forming the AM symbiosis is significant for around 80% of terrestrial plants, little is known about the molecular pathways involved in facilitating the interaction. In this thesis, we sought to understand the involvement of plant defence-associated genes in regulating the beneficial arbuscular mycorrhizal (AM) symbiosis. Based on GeneChip and RNA sequencing data, we identified four genes in the model legume Medicago truncatula with increased expression during AM symbiosis that are predicted to encode proteins associated with host defence pathways. We hypothesized that these proteins are involved in regulating AM symbiosis, either by: a) mediating the suppression of defence pathways to enable fungal colonization of root cells, or alternatively: b) by restricting the growth of the symbiont to prevent over-proliferation in host tissues. Two of the four genes encode putative Toll/inkerleukin-1 nucleotide-binding leucine rich repeat (TIR-NB-LRR) receptors, a group of intracellular receptors that allow plants to identify non-self-microorganisms (Zhai et al., 2011). One gene encodes a leucine-rich repeat (LRR) receptor kinase, a transmembrane receptor that activates signal transduction pathways upon perception of microbe associated antigens (Torii, 2004). The fourth gene encodes an enhanced disease susceptibility-like (EDS1-like) defence protein that mediates signals involved in resistance (Wang et al., 2014). To screen the involvement of these defence genes of interest, we used a reverse genetics approach to compare the mean root length colonized of mutant knockout Medicago truncatula plants inoculated with Rhizophagus irregularis to wildtype plants. Results showed that the TIR-NB-LRRs had no consistent role in the AM symbiosis, while the the EDS1-like gene and the LRR-kinase displayed promising preliminary results for a potential role in regulating the mutualism

An analysis of Glycine max homologs of the symbiosis genes DOES NOT MAKE INFECTIONS (DMI) DMI1, DMI2 and DMI3 was carried out as it relates to the defense response to Heterodera glycines parasitism. Transgenic analyses of the DMI1, DMI2 and DMI3 for overexpression showed decreased H. glycines parasitism while the analyses for RNAi showed increased H. glycines parasitism. The combination of decreased parasitism in the H. glycines-susceptible genotype G. max [Williams 82/PI 518671] and increased parasitism in the H. glycines resistant genotype G. max [Peking/PI 548402] is taken as the genes function in the defense process at some level. Prior analyses have shown that mitogen activated protein kinases (MAPKs) function in the defense response that has to H. glycines. A preliminary RNA seq analysis of MAPK3-1 and MAPK3-2 overexpressing roots reveal increased relative transcript abundance of DMI3, but only in the MAPK3-1 overexpressing roots. Additionally, examination of the expression profiles of two G. max MAPK3-1 and MAPK3-2 showed that their relative transcript abundances in some cases are influenced by DMI1, DMI2 and DMI3 expression. Taken together, the results show that the G. max DMI1, DMI2 and DMI3 function in the defense response to H. glycines and appear to involve MAPKs.

Thesis (MScAgric)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Biochar (charcoal) is lauded by many scientists as an effective way to remove carbon dioxide from the atmosphere and storing it in a very stable form in the soil for hundreds to thousands of years, whilst promoting soil fertility and productivity. Considering that no significant amounts of charcoal are presently accumulating in the environment, despite considerable amounts produced globally in natural and man-made fires, this study focuses on understanding the degradation of biochar and its interactions with plants and soil organisms. The following experiments were conducted to achieve this goal. Controlled chemical oxidation of biochar, using different concentrations of hydrogen peroxide, was conducted in an attempt to mimic the enzymatic degradation of biochar by basidiomycetes. The changes occurring in biochars structure and chemistry were assessed afterwards. Furthermore, aerobic and anaerobic digestion of biochar was conducted in vitro, and in vivo to investigate the changes occurring in biochar‘s elemental composition and chemistry during oxidation and factors that play a determining role in the rate of biochar degradation. The influence of biochar in soil on free-living and symbiotic microbial communities as well as its impact on total plant biomass production and root development was assessed in three greenhouse pot trials using wheat and green beans as test plants It was proven that biochar is almost fully H2O2-degradable, mostly through hydroxylation and carboxylation reactions which led to the formation of various short chained carboxylic acids, surface saturation with acidic functional groups as determined by the surface acidity measurements and proven by the increase in the intensity of FT-IR peaks associated with carboxyl and phenolic C-O groups. Furthermore, hydrogen peroxide treatment resulted in preferential removal of volatile organic carbons and led to the purification of biochar as evident by the new, more intense and sharper peaks in the region of 1600-1000 cm-1. These FT-IR peaks are considered as the more recalcitrant fraction of biochar and were shown to be mostly associated with transformation products of lignin and cellulose formed during pyrolysis. The incubation trial confirmed that biochar cannot be utilized as a sole carbon source without the addition of nutrients or glucose, to activate microbial activity within the columns. Furthermore, abiotic oxidation can be facilitated by oxidative soil minerals such as birnessite, but oxidation with atmospheric oxygen did not result in the evolution of CO2 from biochar. The average CO2 production in pot trials without plants in both the fertilized and unfertilized treatments increased linearly (R2= 0.80; 0.79 respectively) with increasing biochar application rates when biochar was the main carbon sources. Anaerobic degradation of biochar by a methanogenic consortium was much more efficient in utilizing biochar as a carbon source, compared to aerobic digestion. The anaerobic digesters maintained a chemical oxygen demand (COD) removal efficiency of 30% per week with continuous production of CO2, whilst methane production was very erratic. We proposed that better control over pH and alkalinity as well as an increase in hydraulic retention time would improve both the COD removal efficiency and methane production. Field incubations resulted in various degrees of oxidation at different incubation sites. An increase in the oxygen content and a decreased in the carbon content of biochar‘s elemental composition and also an increase in the surface acidity due to a larger amount of carboxyl acid groups on the surface as seen in the increase in the FT-IR peak at 1700 cm-1 confirmed that biochar are susceptible to oxidation under field conditions. We came to the conclusion that oxidation and mineralization of biochar in this trial occurred at a faster rate in soils with a higher microbial activity. The pot trials, confirmed that biochar does not serve as a fertilizer even though it did increase total biomass production between biochar application rates of 0.05-2.5 % (w/w). For agricultural purposes the addition of biochar should always be applied together with NPK fertilizer. In both the wheat and green bean trials it was confirmed that biochar application rates of 0.05-0.5% (w/w) on the sandy, slightly acidic soil used in this trial resulted in the greatest biomass production and fertilizer use efficiency. Biochar additions resulted in considerable increases in soil pH and C/N ratios which were considered as the main reasons for the decrease in microbial biomass in the unfertilized green bean treatments as it made the uptake of N more limited. The addition of fertilizer however, alleviated N-supply constraints and as a result promoted microbial growth at all biochar application rates of pot trial 1. However, biochar did not promote mycorrhyzal colonization and caused a decrease in the mycorrhizal colonization of roots with increasing biochar application rates and within biochar layers. Biological nitrogen fixation, however, reacted positively to the addition of biochar. High biochar application rates significantly enhanced the plants reliance on these symbiotic relationships. We hypothesized that biochar physically immobilized N into its microvoids through capillary suction and then served as a physical barrier between plant roots and absorbed N. However, immobilzation of N by microbes could also have contributed to the decrease in N uptake if one takes into account that microbial activity was higher (respiration data) at the higher biochar application rates. Further investigations are needed to warrant this hypothesizes. / AFRIKAANSE OPSOMMING: Biochar (houtskool) is deur talle wetenskaplikes die lof toegeswaai as ‘n doeltreffende manier om koolstofdioksied uit die atmosfeer te verwyder en in ‘n baie stabiele vorm in die grond vir honderde tot duisende jare te stoor, terwyl dit die grondvrugbaarheid en produktiwiteit bevorder. As daar in ag geneem word dat geen beduidende hoeveelheid houtskool in die omgewing opgaar nie ondanks groot hoeveelhede wat wêreldwyd deur natuurlike en mensgemaakte brande gevorm word, is die doel van hierdie studie om die afbraak en die interaksie van biochar met plante en grondmikrobes beter te verstaan. Om hierdie doel te bereik is die volgende eksperimente uitgevoer: Beheerde chemiese oksidasie is op die biochar toegepas deur gebruik te maak van verskillende konsentrasies waterstofperoksied in 'n poging om die ensiematiese afbraak van biochar deur basidiomysete na te maak. Die veranderinge wat plaasvind in die struktuur en chemie van biochar is daarna bestudeer. Daarbenewens is die aerobiese and anearobiese afbraak van biochar toegepas beide in vitro- en in vivo-, om die veranderinge wat in biochar se elementele samestelling en chemie plaasvind gedurende oksidasie en ook die faktore wat 'n bepalende rol in die tempo waarteen biochar afbreek, te ondersoek. Die invloed van biochar in die grond op vrylewende en simbiotiese mikrobiese populasies, sowel as die impak daarvan op die totale plant biomassa produksie en ontwikkeling van plantwortels, is vasgestel tydens drie groeitonnel potproewe waarby koring en boontjies as planttoetsspesies gebruik is Dit is bewys dat biochar byna volledig deur H2O2 afgebreek kan word, meestal deur hidroksilasie en karboksilasie reaksies wat gelei het tot die vorming van 'n verskeidenheid kort ketting karboksielsure, 'n biochar oppervlak versadig met suurvormende funksionele groepe soos bepaal en bewys deur die toename in intensiteit van die FT-IR (Fourier Transvorm Infrarooi Spektroskopie) pieke geassosieer met karboksiel en fenoliese C-O groepe. Die behandeling van biochar met H2O2 het by voorkeur die vlugtige organise koolstof verwyder wat gelei het tot suiwering van die biochar, wat bevestig is deur die nuwe, meer intens en skerper FT-IR pieke in die area tussen 1600-1000 cm-1. Die FT-IR pieke word beskou as die meer weerstandbiedende fraksie van biochar en daar is bewys dat die pieke meestal met getransformeerde produkte van lignien en sellulose wat tydens pirolise gevorm is, geassosieer word. Die inkubasie proef het bevestig dat biochar nie deur mikrobes benut kan word as enigste bron van koolstof sonder die byvoeging van nutriente of glukose nie, om die mikrobes binne die inkubasie kolom te aktiveer. Daarbenewens kan abiotiese oksidasie van biochar deur oksidatiewe grondminerale soos birnessite (δ-MnO2) gefasiliteer word, terwyl oksidasie van biochar deur atmosferiese suurstof nie tot enige CO2 produksie gelei het nie. Nogtans het die gemiddelde CO2 produksie in die boontjie potproef, sonder die plante, in beide die onbemeste en bemeste behandelings linieer toegeneem (R2= 0.80; 0.79 onderskeidelik) met toenemende aanwendingskoers van biochar, toe biochar die dominante bron van koolstof was. Anaerobiese afbraak van biochar deur 'n metanogeniese konsortium was heelwat meer effektief in die benutting van biochar as enigste koolstofbron in vergelyking met aerobiese afbraak. Die anaerobiese verteertoestel het konstant 30% van die chemiese suurstof behoefte (CSB) weekliks verwyder, gepaardegaande met die voortdurende produksie van CO2, terwyl metaangasproduksie baie onegalig was. Dit word voorgestel dat met beter beheer oor pH en alkaliniteit en ook 'n langer hidrouliese retensie tyd, kan beide die CSB verwyderingseffektiwiteit en metaangasproduksie verbeter kan word. Veld inkubasies het verskeie mates van oksidasie meegebring tussen die verskillende inkubasie liggings. 'n Toename in die suurstofinhoud en 'n afname in die koolstof inhoud van biochar se elementele samestelling sowel as 'n toename in die oppervlak suurheid weens die groter hoeveelheid karboksielsure aan die oppervlak soos blyk uit die FT-IR piek by 1700 cm-1, het bevestig dat biochar wel vatbaar is vir oksidasie onder veld kondisies. Die gevolgtrekking was dat biochar oksidasie en mineralisasie in hierdie proef teen 'n vinniger tempo plaasgevind het in die gronde met hoer mikrobiese aktiwiteit. Die potproewe het bevestig dat biochar nie as bemestingsstof sal dien nie, alhoewel dit tot 'n toename in die biomassa produksie gelei het tussen die biochar aanwendingskoerse van 0.05-2.5% (w/w). Vir landbou doeleindes moet die aanwending van biochar altyd gepaardgaan met NPK bemesting. Beide die koring- en boontjie proewe het bevestig dat die biochar aanwendingskoerse tussen 0.05-0.5% (w/w) op die sanderig, effens suur grond wat gebruik is in die proef, gelei het tot die hoogste biomassa produksie en bemestingseffektiwiteit. Die toediening van biochar het gelei tot merkbare toenames in grond pH en C/N verhoudings en hierdie toestande was beskou as die hoof redes vir die afname in mikrobiese biomassa in die onbemeste boontjie behandelings omdat dit die opname van N meer beperk. Die toediening van bemesting het egter die beperkings op N voorsiening opgehef en as gevolg hiervan die mikrobiese biomassa bevorder by alle biochar aanwendingskoerse. Biochar het egter nie mikorrisa kolonisasie bevorder nie en het gelei tot =n afname in die mikorrisa kolonisasie van die wortels met toenemende biochar aanwendingskoerse en binne in die biochar lae van potproef 1. Biologiese stikstof vaslegging het egter positief reageer op die toediening van biochar. Hoë biochar aanwendingskoerse het beduidend die plant se afhanklikheid op hierdie simbiotiese verhouding verhoog. Ons hipotese is dat die biochar fisies N immobiliseer binne in die mikro-ruimtes deur kapillêre suigaksie en dan as 'n fisiese versperring dien tussen die plantwortels en die geabsorbeerde N. Die immobilisasie van minerale N deur mikrobes kon egter ook grootliks bygedra het tot die afname in N opname as daar in ag geneem word dat mikrobiese aktiwiteit (respirasie data) hoër was by die hoër biochar aanwendingskoerse. Verdere ondersoeke moet daarom uitgevoer word om hierdie hipotese te bevestig.

Pour synthétiser, cette thèse vise trois objectifs : 1- Evaluer si l'éducation à l'environnement telle qu'elle est pratiquée permet effectivement aux enfants de connaitre et d'essayer de protéger la biodiversité locale au même titre que les espèces charismatiques. 2- Mesurer l'importance de l'expérience de terrain avec la nature, ici via la découverte des serpents dans leur milieu, sur le développement d'attitudes concrètes et favorables à la biodiversité. 3- Evaluer les tendances du statut de populations de serpents, identifier les principales menaces et des moyens pour permettre leur conservation. Notamment en utilisant l'éducation pour la préservation de la biodiversité.

Hereditary bacterial symbiosis is a common mechanism by which eukaryotic hosts can acquire traits beneficial for their fitness. Many insects have symbiotic associations with bacteria that trace back millions of years, whose function and evolution are well characterized. Insects can also possess more recently derived symbionts that are closely related to free-living bacteria, and often play a role in host defense. Serratia symbiotica is a recently derived symbiont that infects aphids and provides protection against heat stress, and possibly also plays a nutritional role. Many aspects of the biology of recent symbionts are less well studied, including the diversity of functional roles and evolution among hosts for single lineages of symbionts, the molecular mechanisms that contribute to defense, the early stages of symbiont genome evolution, and interactions with hosts. This dissertation focuses upon S. symbiotica to contribute research addressing each of these themes. Functional studies revealed that S. symbiotica lysis during heat-shock is correlated with protection of the nutritional symbiont Buchnera , and that S. symbiotica has a large effect upon aphid metabolite pools. Despite this large metabolic effect, S. symbiotica does not seem to dramatically influence expression of aphid genes, including those involved in immunity. Analysis of the evolution of S. symbiotica lineages in different aphid hosts revealed this symbiont is common in the aphid subfamily Lachninae, but did not support the obligate nutritional role hypothesized in the literature for this group. Finally, comparison of the S. symbiotica genome to close free-living relatives revealed a genome undergoing massive decay, and provided a rare opportunity to examine the evolution of a recently acquired symbiont.