Impacts des mammifères néotropicaux sur les graines

Seeds dispersal and predation by mammals are two key processes affecting the dynamics of plant communities. Neotropical rainforests, which are of great complexity, have many different relationships involving plant propagules and mammals. Dispersal allows the seed to escape competition and predation, to colonize new sites and to establish in favorable micro-sites. Seed predation reduces the number of seeds able to germinate, can affect dispersal of the remaining seeds and is one of the mecanisms that maintain a high plant species diversity in tropical rainforests. Didelphimorphs and chiropteras are very good dispersers that have a primary role in forest regeneration. Seed predation is very rare in these taxons. Primates, the most studied group on this subject, are also very good dispersers, sometimes predators, and possess an extremely diverse diet. Ungulates can be either dispersers, predators, or both. Their importance is due to their ability to consume generally larger seeds than other mammals. Rodents do not show a net profile and are distinctive by their synzoochore behaviour, consisting of hiding seeds and feeding on them later. An important part of cached seeds can be forgotten and later germinate. The role of carnivores in seed predation or dispersal is poorly known but a few studies show that they could be effective dispersers. Key words: dispersal, mammal, neotropical, predation, seed, zoochory.La dispersion et la prédation des graines par les mammifères sont deux processus-clés de la dynamique des communautés végétales. Les forêts humides néotropicales, dont la grande complexité est reconnue, présentent un éventail très vaste de relations mammifèrespropagules des plantes. La dispersion permet aux graines d’échapper à la compétition, à la prédation, de coloniser de nouveaux sites et de s’établir dans des micro-sites favorables. La prédation diminue le nombre de graines candidates à la germination, peut affecter la dispersion des graines restantes et constitue un mécanisme de maintien de la grande diversité végétale en forêt tropicale. Les didelphimorphes et les chiroptères sont de très bons disperseurs qui ont un rôle primordial dans la régénération de la forêt. Les cas de prédation des graines dans ces deux taxons sont très rares. Les primates, taxon le plus étudié à ce jour sur le sujet, sont également de très bons disperseurs, parfois prédateurs, qui possèdent une diète extrêmement variée. Les ongulés peuvent être disperseurs ou prédateurs, l’un n’excluant pas l’autre. Leur importance se situe dans leur habilité à consommer des graines en général plus grosses que les autres mammifères. Les rongeurs ne présentent pas un profil net et se distinguent par leur comportement de synzoochorie, consistant à cacher des graines afin de s’en nourrir plus tard. Une part importante de ses graines sera cependant oubliée et candidate à la germination. Le rôle des membre de l’ordre des carnivores est très peu connu, mais quelques études effectuées montrent qu’ils peuvent être d’efficaces disperseurs. Mots-cles: dispersion, graine, mammifère, néotropical, prédation, zoochorie

Impacts des mammifères néotropicaux sur les graines

Seeds dispersal and predation by mammals are two key processes affecting the dynamics of plant communities. Neotropical rainforests, which are of great complexity, have many different relationships involving plant propagules and mammals. Dispersal allows the seed to escape competition and predation, to colonize new sites and to establish in favorable micro-sites. Seed predation reduces the number of seeds able to germinate, can affect dispersal of the remaining seeds and is one of the mecanisms that maintain a high plant species diversity in tropical rainforests. Didelphimorphs and chiropteras are very good dispersers that have a primary role in forest regeneration. Seed predation is very rare in these taxons. Primates, the most studied group on this subject, are also very good dispersers, sometimes predators, and possess an extremely diverse diet. Ungulates can be either dispersers, predators, or both. Their importance is due to their ability to consume generally larger seeds than other mammals. Rodents do not show a net profile and are distinctive by their synzoochore behaviour, consisting of hiding seeds and feeding on them later. An important part of cached seeds can be forgotten and later germinate. The role of carnivores in seed predation or dispersal is poorly known but a few studies show that they could be effective dispersers. Key words: dispersal, mammal, neotropical, predation, seed, zoochory.La dispersion et la prédation des graines par les mammifères sont deux processus-clés de la dynamique des communautés végétales. Les forêts humides néotropicales, dont la grande complexité est reconnue, présentent un éventail très vaste de relations mammifèrespropagules des plantes. La dispersion permet aux graines d’échapper à la compétition, à la prédation, de coloniser de nouveaux sites et de s’établir dans des micro-sites favorables. La prédation diminue le nombre de graines candidates à la germination, peut affecter la dispersion des graines restantes et constitue un mécanisme de maintien de la grande diversité végétale en forêt tropicale. Les didelphimorphes et les chiroptères sont de très bons disperseurs qui ont un rôle primordial dans la régénération de la forêt. Les cas de prédation des graines dans ces deux taxons sont très rares. Les primates, taxon le plus étudié à ce jour sur le sujet, sont également de très bons disperseurs, parfois prédateurs, qui possèdent une diète extrêmement variée. Les ongulés peuvent être disperseurs ou prédateurs, l’un n’excluant pas l’autre. Leur importance se situe dans leur habilité à consommer des graines en général plus grosses que les autres mammifères. Les rongeurs ne présentent pas un profil net et se distinguent par leur comportement de synzoochorie, consistant à cacher des graines afin de s’en nourrir plus tard. Une part importante de ses graines sera cependant oubliée et candidate à la germination. Le rôle des membre de l’ordre des carnivores est très peu connu, mais quelques études effectuées montrent qu’ils peuvent être d’efficaces disperseurs. Mots-cles: dispersion, graine, mammifère, néotropical, prédation, zoochorie

Clinical and molecular characterization of diffuse large B-cell lymphomas with 13q14.3 deletion.

Background: Deletions at 13q14.3 are common in chronic lymphocytic leukemia and are also present in diffuse large B-cell lymphomas (DLBCL) but never in immunodeficiency-related DLBCL. To characterize DLBCL with 13q14.3 deletions, we combined genome-wide DNA profiling, gene expression and clinical data in a large DLBCL series treated with rituximab, cyclophosphamide, doxorubicine, vincristine and prednisone repeated every 21 days (R-CHOP21). Patients and methods: Affymetrix GeneChip Human Mapping 250K NspI and U133 plus 2.0 gene were used. MicroRNA (miRNA) expression was studied were by real-time PCR. Median follow-up of patients was 4.9 years. Results: Deletions at 13q14.3, comprising DLEU2/MIR15A/MIR16, occurred in 22/166 (13%) cases. The deletion was wider, including also RB1, in 19/22 cases. Samples with del(13q14.3) had concomitant specific aberrations. No reduced MIR15A/MIR16 expression was observed, but 172 transcripts were significantly differential expressed. Among the deregulated genes, there were RB1 and FAS, both commonly deleted at genomic level. No differences in outcome were observed in patients treated with R-CHOP21. Conclusions: Cases with 13q14.3 deletions appear as group of DLBCL characterized by common genetic and biologic features. Deletions at 13q14.3 might contribute to DLBCL pathogenesis by two mechanisms: deregulating the cell cycle control mainly due RB1 loss and contributing to immune escape, due to FAS down-regulation

Clinical and molecular characterization of diffuse large B-cell lymphomas with 13q14.3 deletion

Background: Deletions at 13q14.3 are common in chronic lymphocytic leukemia and are also present in diffuse large B-cell lymphomas (DLBCL) but never in immunodeficiency-related DLBCL. To characterize DLBCL with 13q14.3 deletions, we combined genome-wide DNA profiling, gene expression and clinical data in a large DLBCL series treated with rituximab, cyclophosphamide, doxorubicine, vincristine and prednisone repeated every 21 days (R-CHOP21). Patients and methods: Affymetrix GeneChip Human Mapping 250K NspI and U133 plus 2.0 gene were used. MicroRNA (miRNA) expression was studied were by real-time PCR. Median follow-up of patients was 4.9 years. Results: Deletions at 13q14.3, comprising DLEU2/MIR15A/MIR16, occurred in 22/166 (13%) cases. The deletion was wider, including also RB1, in 19/22 cases. Samples with del(13q14.3) had concomitant specific aberrations. No reduced MIR15A/MIR16 expression was observed, but 172 transcripts were significantly differential expressed. Among the deregulated genes, there were RB1 and FAS, both commonly deleted at genomic level. No differences in outcome were observed in patients treated with R-CHOP21. Conclusions: Cases with 13q14.3 deletions appear as group of DLBCL characterized by common genetic and biologic features. Deletions at 13q14.3 might contribute to DLBCL pathogenesis by two mechanisms: deregulating the cell cycle control mainly due RB1 loss and contributing to immune escape, due to FAS down-regulatio

Autocatalytic Activation of the Furin Zymogen Requires Removal of the Emerging Enzyme's N-Terminus from the Active Site

Before furin can act on protein substrates, it must go through an ordered process of activation. Similar to many other proteinases, furin is synthesized as a zymogen (profurin) which becomes active only after the autocatalytic removal of its auto-inhibitory prodomain. We hypothesized that to activate profurin its prodomain had to be removed and, in addition, the emerging enzyme's N-terminus had to be ejected from the catalytic cleft.We constructed and analyzed the profurin mutants in which the egress of the emerging enzyme's N-terminus from the catalytic cleft was restricted. Mutants were autocatalytically processed at only the primary cleavage site Arg-Thr-Lys-Arg(107) downward arrowAsp(108), but not at both the primary and the secondary (Arg-Gly-Val-Thr-Lys-Arg(75) downward arrowSer(76)) cleavage sites, yielding, as a result, the full-length prodomain and mature furins commencing from the N-terminal Asp108. These correctly processed furin mutants, however, remained self-inhibited by the constrained N-terminal sequence which continuously occupied the S' sub-sites of the catalytic cleft and interfered with the functional activity. Further, using the in vitro cleavage of the purified prodomain and the analyses of colon carcinoma LoVo cells with the reconstituted expression of the wild-type and mutant furins, we demonstrated that a three-step autocatalytic processing including the cleavage of the prodomain at the previously unidentified Arg-Leu-Gln-Arg(89) downward arrowGlu(90) site, is required for the efficient activation of furin.Collectively, our results show the restrictive role of the enzyme's N-terminal region in the autocatalytic activation mechanisms. In a conceptual form, our data apply not only to profurin alone but also to a range of self-activated proteinases

A maritime decision support system to assess risk in the presence of environmental uncertainties: the REP10 experiment

The aim of this work is to report on an activity carried out during the 2010 Recognized Environmental Picture experiment, held in the Ligurian Sea during summer 2010. The activity was the first at-sea test of the recently developed decision support system (DSS) for operation planning, which had previously been tested in an artificial experiment. The DSS assesses the impact of both environmental conditions (meteorological and oceanographic) and non-environmental conditions (such as traffic density maps) on people and assets involved in the operation and helps in deciding a course of action that allows safer operation. More precisely, the environmental variables (such as wind speed, current speed and significant wave height) taken as input by the DSS are the ones forecasted by a super-ensemble model, which fuses the forecasts provided by multiple forecasting centres. The uncertainties associated with the DSS's inputs (generally due to disagreement between forecasts) are propagated through the DSS's output by using the unscented transform. In this way, the system is not only able to provide a traffic light map (run/not run the operation), but also to specify the confidence level associated with each action. This feature was tested on a particular type of operation with underwater gliders: the glider surfacing for data transmission. It is also shown how the availability of a glider path prediction tool provides surfacing options along the predicted path. The applicability to different operations is demonstrated by applying the same system to support diver operations

Dominant Glint Based Prey Localization in Horseshoe Bats: A Possible Strategy for Noise Rejection

Rhinolophidae or Horseshoe bats emit long and narrowband calls. Fluttering insect prey generates echoes in which amplitude and frequency shifts are present, i.e. glints. These glints are reliable cues about the presence of prey and also encode certain properties of the prey. In this paper, we propose that these glints, i.e. the dominant glints, are also reliable signals upon which to base prey localization. In contrast to the spectral cues used by many other bats, the localization cues in Rhinolophidae are most likely provided by self-induced amplitude modulations generated by pinnae movement. Amplitude variations in the echo not introduced by the moving pinnae can be considered as noise interfering with the localization process. The amplitude of the dominant glints is very stable. Therefore, these parts of the echoes contain very little noise. However, using only the dominant glints potentially comes at a cost. Depending on the flutter rate of the insect, a limited number of dominant glints will be present in each echo giving the bat a limited number of sample points on which to base localization. We evaluate the feasibility of a strategy under which Rhinolophidae use only dominant glints. We use a computational model of the echolocation task faced by Rhinolophidae. Our model includes the spatial filtering of the echoes by the morphology of the sonar apparatus of Rhinolophus rouxii as well as the amplitude modulations introduced by pinnae movements. Using this model, we evaluate whether the dominant glints provide Rhinolophidae with enough information to perform localization. Our simulations show that Rhinolophidae can use dominant glints in the echoes as carriers for self-induced amplitude modulations serving as localization cues. In particular, it is shown that the reduction in noise achieved by using only the dominant glints outweighs the information loss that occurs by sampling the echo