Shifts in species and phylogenetic diversity between sapling and tree communities indicate negative density dependence in a lowland rain forest

1. As trees in a given cohort progress through ontogeny, many individuals die. This risk of mortality is unevenly distributed across species because of many processes such as habitat filtering, interspecific competition and negative density dependence. Here, we predict and test the patterns that such ecological processes should inscribe on both species and phylogenetic diversity as plants recruit from saplings to the canopy. 2. We compared species and phylogenetic diversity of sapling and tree communities at two sites in French Guiana. We surveyed 2084 adult trees in four 1-ha tree plots and 943 saplings in sixteen 16-m2 subplots nested within the tree plots. Species diversity was measured using Fisher's alpha (species richness) and Simpson's index (species evenness). Phylogenetic diversity was measured using Faith's phylogenetic diversity (phylogenetic richness) and Rao's quadratic entropy index (phylogenetic evenness). The phylogenetic diversity indices were inferred using four phylogenetic hypotheses: two based on rbcLa plastid DNA sequences obtained from the inventoried individuals with different branch lengths, a global phylogeny available from the Angiosperm Phylogeny Group, and a combination of both. 3. Taxonomic identification of the saplings was performed by combining morphological and DNA barcoding techniques using three plant DNA barcodes (psbA-trnH, rpoC1 and rbcLa). DNA barcoding enabled us to increase species assignment and to assign unidentified saplings to molecular operational taxonomic units. 4. Species richness was similar between saplings and trees, but in about half of our comparisons, species evenness was higher in trees than in saplings. This suggests that negative density dependence plays an important role during the sapling-to-tree transition. 5. Phylogenetic richness increased between saplings and trees in about half of the comparisons. Phylogenetic evenness increased significantly between saplings and trees in a few cases (4 out of 16) and only with the most resolved phylogeny. These results suggest that negative density dependence operates largely independently of the phylogenetic structure of communities. 6. Synthesis. By contrasting species richness and evenness across size classes, we suggest that negative density dependence drives shifts in composition during the sapling-to-tree transition. In addition, we found little evidence for a change in phylogenetic diversity across age classes, suggesting that the observed patterns are not phylogenetically constrained.

Dual functions of DP1 promote biphasic Wnt-on and Wnt-off states during anteroposterior neural patterning.

DP1, a dimerization partner protein of the transcription factor E2F, is known to inhibit Wnt/β-catenin signalling along with E2F, although the function of DP1 itself was not well characterized. Here, we present a novel dual regulatory mechanism of Wnt/β-catenin signalling by DP1 independent from E2F. DP1 negatively regulates Wnt/β-catenin signalling by inhibiting Dvl-Axin interaction and by enhancing poly-ubiquitination of β-catenin. In contrast, DP1 positively modulates the signalling upon Wnt stimulation, via increasing cytosolic β-catenin and antagonizing the kinase activity of NLK. In Xenopus embryos, DP1 exerts both positive and negative roles in Wnt/β-catenin signalling during anteroposterior neural patterning. From subcellular localization analyses, we suggest that the dual roles of DP1 in Wnt/β-catenin signalling are endowed by differential nucleocytoplasmic localizations. We propose that these dual functions of DP1 can promote and stabilize biphasic Wnt-on and Wnt-off states in response to a gradual gradient of Wnt/β-catenin signalling to determine differential cell fates.

A Comparison of the Management Models of Protected Areas between China and the Southern African Region

A Comparison of the Management Models of Protected Areas between China and the African South Region allows reading and evaluating the similarities and differences in the use of management model as a management tool for protected areas in China and South African Region. Specifically, some positive and negative features of the management approaches for the two regions. Secondary data was collected from various related literature such as policy documents, students‟ dissertations/thesis, scientific articles and magazines. Based on the method above, the study found out that China's first nature reserve was the Dingus Mountain Nature Reserve in Zhaoqing, Guangdong province established in 1956. By the end of 2005, about 2,349 nature reserves of various kinds were set up throughout the country, covering a total area of 149.95 million ha and accounting for 15 percent of the total land territory. The study further found that Southern Africa has approximately 4,390 protected areas out of 11487920 total land areas and Eastern Africa has approximately 1838144 protected areas, which is equivalent to 15.0% of the total land areas. South Africa in this region had its first declared natural park in 1926 after Paul Kruger (a war hero) had alerted the authorities of the extinguishing threat of some animal species of region.

Alpha rhythm and hypofrontality in schizophrenia

OBJECTIVE: To reveal the EEG correlates of resting hypofrontality in schizophrenia (SZ). METHOD: We analyzed the whole-head EEG topography in 14 patients compared to 14 matched controls by applying a new parameterization of the multichannel EEG. We used a combination of power measures tuned for regional surface mapping with power measures that allow evaluation of global effects. RESULTS: The SZ-related EEG abnormalities include i) a global decrease in absolute EEG power robustly manifested in the alpha and beta frequency bands, and ii) a relative increase in the alpha power over the prefrontal brain regions against its reduction over the posterior regions. In the alpha band both effects are linked to the SZ symptoms measured with Positive and Negative Symptom Scales and to chronicity. CONCLUSION: As alpha activity is related to regional deactivation, our findings support the concept of hypofrontality in SZ and expose the alpha rhythm as a sensitive indicator of it.

Quetiapine affects neuropeptide Y and corticotropin-releasing hormone in cerebrospinal fluid from schizophrenia patients: relationship to depression and anxiety symptoms and to treatment response.

Cumulative evidence indicates that neuropeptides play a role in the pathophysiology of schizophrenia. Early data showed increased neuropeptide Y (NPY) in cerebrospinal fluid (CSF) from schizophrenia patients and data from rodents show that antipsychotic drugs modulate NPY levels in and release from selected rat brain regions. In view of these findings we investigated whether the atypical antipsychotic quetiapine, originally used as an antipsychotic but subsequently shown to be efficient also in major depressive disorder and in both poles of bipolar disorder, would affect NPY-like immunoreactivity (-LI), and corticotropin-releasing hormone (CRH)-LI levels in CSF of schizophrenia patients. NPY-LI and CRH-LI in CSF were determined in 22 patients with schizophrenia. Lumbar puncture was performed at baseline and again after 4 wk of quetiapine treatment (600 mg/d). Patients were assessed with the Positive and Negative Syndrome Scale (PANSS) at baseline and at weekly intervals. Quetiapine treatment was associated with a significant increase in NPY-LI (p<0.001) and decrease in CRH-LI (p<0.01). Stepwise multiple regression analysis revealed that ΔNPY-LI and ΔCRH-LI levels predicted 63% (p<0.001) of the variability of the ΔPANSS total score, ΔNPY-LI 42% (p<0.05) of the ΔPANSS anxiety items (G2) and ΔCRH-LI 40% (p=0.05) of the ΔPANSS depression items (G6). These results suggest that while quetiapine's effects on monoamines are probably related to its antipsychotic properties, the modulation of NPY and CRH accounts for its antidepressant and anxiolytic effects and can be markers of response.

Comparative genomics of chemosensory protein genes reveals rapid evolution and positive selection in ant-specific duplicates.

Gene duplications can have a major role in adaptation, and gene families underlying chemosensation are particularly interesting due to their essential role in chemical recognition of mates, predators and food resources. Social insects add yet another dimension to the study of chemosensory genomics, as the key components of their social life rely on chemical communication. Still, chemosensory gene families are little studied in social insects. Here we annotated chemosensory protein (CSP) genes from seven ant genomes and studied their evolution. The number of functional CSP genes ranges from 11 to 21 depending on species, and the estimated rates of gene birth and death indicate high turnover of genes. Ant CSP genes include seven conservative orthologous groups present in all the ants, and a group of genes that has expanded independently in different ant lineages. Interestingly, the expanded group of genes has a differing mode of evolution from the orthologous groups. The expanded group shows rapid evolution as indicated by a high dN/dS (nonsynonymous to synonymous changes) ratio, several sites under positive selection and many pseudogenes, whereas the genes in the seven orthologous groups evolve slowly under purifying selection and include only one pseudogene. These results show that adaptive changes have played a role in ant CSP evolution. The expanded group of ant-specific genes is phylogenetically close to a conservative orthologous group CSP7, which includes genes known to be involved in ant nestmate recognition, raising an interesting possibility that the expanded CSPs function in ant chemical communication.

Prediction of postnatal outcome in fetuses with pulmonary hypoplasia by fetal-MRI: Comparison between lung volumetry and pulmonary signal intensity values

Purpose: Pulmonary hypoplasia is a determinant parameter for extra-uterine life. In the last years, MRI appears as a complement to US in order to evaluate the degree of pulmonary hypoplasia in foetuses with congenital anomalies, by using different methods - fetal lung volumetry (FLV), lung-to-liver signal intensity ratio (LLSIR)-. But until now, information about the correlation between the MRI prediction and the real postnatal outcome is limited. Methods and materials: We retrospectively reviewed the fetal MRI performed at our Institution in the last 8 years and selected the cases with suspicion of fetal pulmonary hypoplasia (n = 30). The pulmonary volumetry data of these foetuses were collected and the lung-to-liver signal intensity ratio (LLSIR) measures performed. These data were compared with those obtained from a control group of 25 foetuses considered as normal at MRI. The data of the study group were also correlated with the autopsy records or the post-natal clinical information of the patients. Results: As expected, the control group showed higher FLV and LLSIR values than the problem group at all gestational ages. Higher values of FLV and LLSIR were associated with a better post-natal outcome. Sensitivity, specificity, positive and negative predictive values and accuracy for the relative LLSIR and the relative FLV showed no significant differences. Conclusion: Our data show that not only the FLV but also the relative LLSIR inform about the degree of fetal lung development. This information may help to predict the fetal outcome and to evaluate the need for neonatal intensive care.

Credit constraints, firms' precautionary investment and the business cycle

This paper studies the macroeconomic implications of firms' investment composition choices in the presence of credit constraints. Following a negative andpersistent aggregate productivity shock, firms shift into short-term investments because they produce more pledgeable output and because they help alleviate futureborrowing constraints. This produces a short-run dampening of the effects of theshock, at the expense of lower long-term investment and future output, relativeto an economy with no credit market imperfections. The effects are exacerbatedby a steepening of the term structure of interest rates that further encourages ashift towards short-term investments in the short-run. Small temporary shocks tothe severity of financing frictions generate large and long-lasting effects on outputthrough their impact on the composition of investment. A positive financial shockproduces much stronger effects than an identical negative shock, while the responsesto positive and negative shocks to aggregate productivity are roughly symmetric.Finally, the paper introduces a novel explanation for the countercyclicality of financing constraints of firms.

Quetiapine and norquetiapine in plasma and cerebrospinal fluid of schizophrenic patients treated with quetiapine: correlations to clinical outcome and HVA, 5-HIAA, and MHPG in CSF.

This study investigated concentrations of quetiapine and norquetiapine in plasma and cerebrospinal fluid (CSF) in 22 schizophrenic patients after 4-week treatment with quetiapine (600 mg/d), which was preceded by a 3-week washout period. Blood and CSF samples were obtained on days 1 and 28, and CSF levels of homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) concentrations were measured at baseline and after 4 weeks of quetiapine, allowing calculations of differences in HVA (ΔHVA), 5-HIAA (Δ5-HIAA), and MHPG (ΔMHPG) concentrations. Patients were assessed clinically, using the Positive and Negative Syndrome Scale (PANSS) and Clinical Global Impression Scale at baseline and then at weekly intervals. Plasma levels of quetiapine and norquetiapine were 1110 ± 608 and 444 ± 226 ng/mL, and the corresponding CSF levels were 29 ± 18 and 5 ± 2 ng/mL, respectively. After the treatment, the levels of HVA, 5-HIAA, and MHPG were increased by 33%, 35%, and 33%, respectively (P < 0.001). A negative correlation was found between the decrease in PANSS positive subscale scores and CSF ΔHVA (r(rho) = -0.690, P < 0.01), and the decrease in PANSS negative subscale scores both with CSF Δ5-HIAA (r(rho) = -0.619, P = 0.02) and ΔMHPG (r(rho) = -0.484, P = 0.038). Because, unfortunately, schizophrenic patients experience relapses even with the best available treatments, monitoring of CSF drug and metabolite levels might prove to be useful in tailoring individually adjusted treatments.

Economic shocks and civil conflict: A comment

Miguel, Satyanath, and Sergenti (2004) argue that lowerrainfall levels and negative rainfall shocks increase conflictrisk in Sub-Saharan Africa. This conclusion rests on theirfinding of a negative correlation between conflict in t andrainfall growth between t-1 and t-2. I argue that this findingis driven by a positive correlation between conflict in t andrainfall levels in t-2. If lower rainfall levels or negativerainfall shocks increased conflict, one might have expectedMSS s finding to reflect a negative correlation betweenconflict in t and rainfall levels in t-1. In the latest data,conflict is unrelated to rainfall.

Correlation between placental bacterial culture results and histological chorioamnionitis: a prospective study on 376 placentas.

OBJECTIVE: To study the correlation between the bacteriological and histopathological findings in placentas from women with suspected or proven chorioamnionitis (CA). METHODS: Over a 1-year period, 376 placentas were prospectively collected and processed for bacteriological and pathological studies in cases of confirmed or suspected maternal or neonatal infection. RESULTS: Histological CA was diagnosed in 26.9% of placentas (101/376), and 27.7% (28/101) of these placentas had positive bacteriological cultures. A monomicrobial culture, mainly represented by Gram-positive cocci and Gram-negative bacilli, was identified in 27% of the positive bacterial cultures. The proportion of positive cultures was higher (p=0.03) when CA was associated with funisitis, as compared with placental samples with early CA. In placentas without histological CA, bacteriological cultures were mostly negative (230/275), although pathogenic bacteria were identified in 16.3% of them (45/275). CONCLUSIONS: The histological and bacteriological results were concordant in about 70% of the examined placentas, with 61.1% negative cases (CA absent and negative bacterial cultures), and only 7.4% placentas with positive histological and bacteriological results. Discordant results (positive histology with negative bacteriology) were obtained in placentas with early CA documented by histology although possibly in relation with antibiotic prophylaxis and the presence of fastidious bacteria. Conversely, negative histology with positive bacteriology could be explained by the presence of an early-stage bacterial infection that has not yet led to detectable microscopic lesions.

Petrography and geochemistry of accreted oceanic fragments below the Western Cordillera of Ecuador

The Western Cordillera of Ecuador consists of Cretaceous crustal fragments of oceanic plateaux and superimposed insular arcs, which were accreted to the northwestern South American margin during the Late Cretaceous and Paleocene. Slices of high-grade metabasites, ultramafic rocks, gabbros and basalts, unmetamorphosed radiolarian cherts and scarce garnet-bearing metasediments were randomly exhumed along Miocene to Recent transcurrent faults crosscutting the Western Cordillera. The basalts show geochemical characteristics of oceanic plateau basalts (flat REE patterns, La/Nb = 0.85). The gabbros differ from the basalts in having lower REE levels, positive Eu anomalies, and negative Nb and Ta anomalies; they are interpreted as resulting from arc magmatism. The amphibolites and banded amphibolites have major and trace element chemistry similar to that of oceanic plateau basalts (flat REE patterns, La/Nb = 0.86) or to cumulate gabbros. The granulite shares with oceanic plateaus similar trace element chemistry (flat REE patterns, La/Nb < 1) and epsilon(Ndi) values (+7.6). Continent-derived metasediments are depleted in heavy REE (La/Y = 4.8) and have a negative Eu anomaly. Foliated Iherzolites, melagabbronorites and pyroxenites consist of serpentinized olivine + cpx + opx +/- Ca-plagioclase. Lherzolites, melagabbronorites and pyroxenites are LREE depleted with positive Eu anomalies, while the harzburgite displays a U-shaped REE pattern. The trace element abundances of the ultramafic rocks are very low (0.1 to 1 times the chonctritic and primitive mantle values). The ultramafic rocks represent fragments of depleted mantle, deformed cpx-rich cumulate, and continental lithospheric mantle or mantle contaminated by subduction-fluid. Except the scarce quartz-rich metasediments, all these rocks likely represent remnants of accreted oceanic crustal fragments and associated depleted mantle. Since these samples were randomly sampled at depth by the fault, we propose that the Western Cordillera and its crustal root are mainly of oceanic nature.

Differential regulation of the expression of two high-affinity sulfate transporters, SULTR1.1 and SULTR1.2, in Arabidopsis

The molecular mechanisms regulating the initial uptake of inorganic sulfate in plants are still largely unknown. The current model for the regulation of sulfate uptake and assimilation attributes positive and negative regulatory roles to O-acetyl-serine (O-acetyl-Ser) and glutathione, respectively. This model seems to suffer from exceptions and it has not yet been clearly validated whether intracellular O-acetyl-Ser and glutathione levels have impacts on regulation. The transcript level of the two high-affinity sulfate transporters SULTR1.1 and SULTR1.2 responsible for sulfate uptake from the soil solution was compared to the intracellular contents of O-acetyl-Ser, glutathione, and sulfate in roots of plants submitted to a wide diversity of experimental conditions. SULTR1.1 and SULTR1.2 were differentially expressed and neither of the genes was regulated in accordance with the current model. The SULTR1.1 transcript level was mainly altered in response to the sulfur-related treatments. Split-root experiments show that the expression of SULTR1.1 is locally regulated in response to sulfate starvation. In contrast, accumulation of SULTR1.2 transcripts appeared to be mainly related to metabolic demand and is controlled by photoperiod. On the basis of the new molecular insights provided in this study, we suggest that the expression of the two transporters depends on different regulatory networks. We hypothesize that interplay between SULTR1.1 and SULTR1.2 transporters could be an important mechanism to regulate sulfate content in the roots

Genetic and maternal contributions to offspring viability under different environmental conditions in various salmonids

Summary : Due to anthropogenic impacts and natural fluctuations, fish usually have to cope with constantly changing and often hostile environments. Whereas adult fish have various possibilities to counteract unfavourable environmental conditions, embryos have much fewer options. Besides by their developing immune system, they are protected by the egg envelopes and several immune substances provided by their mothers. In addition to this, they may also adjust their hatching timing in reaction to various risks. However, individuals may vary in their defensive potential. This variation may be either based on their genetics and/or on differential maternal investments and may be dependent on the experienced stress. Nevertheless, in fish, the impact of such parental contributions on embryo and/or juvenile viability is still poorly investigated. The main objective of this thesis was to investigate the importance of paternal (i.e. genetic) and maternal (i.e. genetic + egg investment) contributions to offspring viability under different environmental conditions and at different life stages. In order to investigate this, we used gametes of various salmonids for in vitro fertilisation experiments based on full-factorial breeding designs. The individual studies are summarised in the following chapters: In the first chapter, we tested the effectiveness of the embryonic immune system in Lake whitefish (Coregonus palaea). Namely, we investigated paternal and maternal contributions to the embryos' tolerance to different kinds of pathogen exposure. Additionally, we tested whether an early sub-léthal exposure has a positive or a negative effect on an embryo's susceptibility to later pathogen exposures with the same pathogen. We found that pre-challenged embryos were more susceptible to future challenges. Moreover, pathogen susceptibility was dependent on maternal investments and/or the embryos' own genetics, depending on the challenge level. Chapter 2 summarises a similar study with brown trout (Salmo trutta). In addition to the previously described investigations, we analysed if genetic effects on offspring viability are mediated either by parental MHC genotypes or relatedness based on neutral microsatellite markers, and we tested if males signal their genetic quality either by their body size or their melanin-based skin colouration. We found that embryo survival was lower at higher stress levels and dependent on the embryos' genetics. Addirionally, parents with similar and/or, very common MHC genotypes had higher offspring viabilities. Finally, darker males produced more viable offspring. In the first two chapters we investigated the embryos' defensive potential based on their immune system, i.e. their pathogen tolerance. In chapter 3 we investigate whether hatching timing of Lake whitefìsh (C. palaea) is dependent on parental contributions and/or on pathogen pressure, and whether there are parental-environmental interactions. We found that whitefish embryos hatch earlier under increasing pathogen pressure. Moreover, hatching timing was affected by embryo genetics and/or maternally provided resources, but the magnitude of the effect was dependent on the pathogen. pressure. We also found a significant paternal-environmental interaction, indicating that the hatching efficiency of a certain sib group is dependent on the pathogen environment. Chapter 4 describes an analogous study with brown trout (S. trutta), with similar findings. In the former chapters, we only looked at offspring performance during the embryonic period, and only under semi-natural conditions. In chapter 5 we now test the performance and viability of embryonic and juvenile brown trout (S. trutta) under natural conditions. To measure embryo viability, we put them in brood boxes, buried them in the gravel of a natural river, and analysed survival after several months. To investigate juvenile survival and performance, wé reared embryos under different stress levels in the laboratory and subsequently released the resulting hatchlings in to a closed river section. Juvenile size and survival was then determined one year later. Additionally, we investigated if sires differ in their genetic quality, determined by embryo and juvenile survival as well as juvenile size, and if they signal their quality by either body size or melanin-based body darkness. We found hat juvenile size was dependent on genetic effects and on maternal investment, whereas this was neither the case for embryo nor for juvenile survival. Additionally, we found that offspring of darker males grew larger, and larger juveniles had also an increased survival. Finally, we found acarry-over effect of the early non-lethal challenge: exposing embryos to higher stress levels resulted in smaller juveniles. To evaluate the long-term performance of differently treated groups, mark-recapture studies are inevitable. For this purpose, effective mass-marking techniques are essential. In chapter 6 we tested the suitability of the fluorescent pigment spray marking method for the mass marking of European graylings (Thymallus thymallus), with very promising results. Our in vitro fertilisation studies on whitefish may reveal new insights on potential genetic benefits of mate choice, but the mating system of whitefish under natural conditions is still poorly investigated. In order to study this, we installed underwater cameras at the spawning place of a Coregonus suidteri population, recorded the whole mating period and subsequently analysed the recordings. Confirmations of previous findings as well as exciting new observations are listed and discussed in chapter 7. Dus aux impacts anthropogéniques et aux fluctuations naturelles, les poissons doivent faire face à des environnements en perpétuel changement. Ces changements font que les poissons doivent s'adapter à de nouvelles situations, souvent hostiles pour eux. Les adultes ont différentes possibilités d'échapper à un environnement peu favorable, ce n'est par contre pas le cas des embryons. Les embryons sont protégés d'une part par leur système immunitaire en développement, d'autre part, par la coquille de l'eeuf et différentes substances immunitaires fournies par leur mère. De plus, ils sont capables d'influencer leur propre date d'éclosion en réponse à différents facteurs de stress. Malgré tout, les individus varient dans leur capacité à se défendre. Cette variation peut être basé sur des facteurs génétiques et/ou sur des facteurs maternels, et est dépendante du stress subi. Néanmoins, chez les poissons, l'impact de telles contributions parentales sur la survie d'embryons et/ou juvéniles est peu étudié. L'objectif principal de cette thèse a été d'approfondir les connaissances sur l'importance de la contribution paternelle (c.a.d. génétique) et maternelle (c.a.d. génétique + investissement dans l'oeuf) sur la survie des jeunes dans différentes conditions expérimentales et stades de vie. Pour faire ces analyses, nous avons utilisé des gamètes de divers salmonidés issus de croisements 'full-factorial'. Les différentes expériences sont résumées dans les chapitres suivants: Dans le premier chapitre, nous avons testé l'efficacité du système immunitaire des embryons chez les corégones (Coregonus palea). Plus précisément nous avons étudié la contribution paternelle et maternelle à la tolérance des embryons à différents niveaux de stress pathogène. Nous avons aussi testé, si une première exposition non létale à un pathogène avait un effet positif ou négatif sur la susceptibilité d'un embryon a une deuxième exposition au même pathogène. Nous avons trouvé que des embryons qui avaient été exposés une première fois étaient plus sensibles au pathogène par la suite. Mais aussi que la sensibilité au pathogène était dépendante de l'investissement de la mère et/ou des gènes de l'embryon, dépendamment du niveau de stress. Le deuxième chapitre résume une étude similaire avec des truites (Salmo truffa). Nous avons examiné, si la survie des jeunes variait sous différentes intensités de stress, et si la variance observée était due aux gènes des parents. Nous avons aussi analysé si les effets génétiques sur la survie des juvéniles étaient dus au MHC (Major Histocompatibility Complex) ou au degré de parenté des parents. De plus, nous avons analysé si les mâles signalaient leur qualité génétique par la taille du corps ou par leur coloration noire, due à la mélanine. On a trouvé que la survie des embryons était plus basse quand le niveau de stress était plus haut mais que la variation restait dépendante de la génétique des embryons. De plus, les parents avec des MHC similaires et/ou communs avaient des embryons avec une meilleure survie. Par contre, des parents avec un degré de parenté plus haut produisent des embryons avec une survie plus mauvaise. Finalement nous avons montré que les mâles plus foncés ont des embryons qui survivent mieux, mais que la taille des mâles n'a pas d'influence sur la survie de ces mêmes embryons. Dans les deux premiers chapitres, nous avons étudié le potentiel de défense des embryons basé sur leur système immunitaire, c.a.d. leur tolérance aux pathogènes. Dans le troisième chapitre, nous nous intéressons à la date d'éclosion des corégones (C. palea), pour voir si elle est influencée par les parents ou par la pression des pathogènes, et si il y a une interaction entre ces deux facteurs. Nous avons trouvé que les jeunes naissent plus rapidement lorsque la pression en pathogènes augmente. La date d'éclosion est influencée par la génétique des embryons et/ou l'investissement des parents, mais c'est la magnitude des effets qui est dépendante de la pression du pathogène. Nous avons aussi trouvé une interaction entre l'effet paternel et l'environnement, ce qui indique que la rapidité d'éclosion de certains croisements est dépendante des pathogènes dans l'environnement. Le chapitre 4 décrit une étude analogue avec de truites (S. truffa), avec des résultats sitzimilaires. Dans les précédents chapitres nous nous sommes uniquement concentrés sur les performances des jeunes durant leur stade embryonnaire, et seulement dans des conditions semi naturelles. Dans le chapitre 5 nous testons la performance et la viabilité des embryons et de juvéniles de truites (S. truffa) dans des conditions naturelles. Nous avons trouvé que la taille des juvéniles était dépendante d'effets génétiques et de l'investissement maternel, mais ceci n'était ni les cas pour les survie des embryons et des juvéniles. De plus, nous avons trouvé que les jeunes des mâles plus foncés devenaient plus grands et que les grands ont un meilleur taux de survie. Finalement nous avons trouvé un 'carry-over effect' d'une première exposition non létale à un pathogène: exposer des embryons à des plus hauts niveaux de stress donnait des juvéniles plus petits. Pour évaluer la performance à long terme de groupes traités dé manières différentes, une méthode de marquage-recapture est inévitable. Pour cette raison, des techniques de marquage en masse sont nécessaires. Dans le chapitre 6, nous avons testé l'efficacité de la technique `fluorescent pigment spray marking' pour le marquage en masse de l'Ombre commun (Thymallus thymallus), avec des résultats très prometteurs. Les études de fertilisations in vitro avec les corégones nous donnent une idée du potentiel bénéfice génétique que représente la sélection d'un bon partenaire, même si le système d'accouplement des corégones en milieu naturel reste peu connu. Pour combler cette lacune, nous avons installé des caméras sous-marines autour de la frayère d'une population de corégones (C. suidteri), nous avons enregistré toute la période de reproduction et nous avons analysé les données par la suite. Ainsi, nous avons été capables de confirmer bien des résultats trouvés précédemment, mais aussi de faire de nouvelles observations. Ces résultats sont reportés dans le septième chapitre, où elles sont comparées avec des observations antérieures.

Comparison of C-reactive protein and white blood cell count with differential in neonates at risk for septicaemia.

We prospectively compared the diagnostic value of C-reactive protein (CRP) and white blood cell counts for detection of neonatal septicaemia. Sensitivity and specifity in receiver operating characteristics, and positive and negative predictive value of CRP and white blood cell count were compared in 195 critically ill preterm and term newborns clinically suspected of infection. Blood cultures were positive in 33 cases. During the first 3 days after birth CRP elevation (sensitivity 75%, specifity 86%), leukopenia (67%/90%), neutropenia (78%/80%) and immature to total neutrophil count (I/T) ratio (78%/73%) were good diagnostic parameters, as opposed to band forms with absolute count (84%/66%) or percentage (79%/71%), thrombocytopenia (65%/57%) and toxic granulations (44%/94%). Beyond 3 days of age elevated CRP (88%/87%) was the best parameter. Increased total (84%/66%) or percentage band count (79%/71%) were also useful. Leukocytosis (74%/56%), increased neutrophils (67%/65%), I/T ratio (79%/47%), thrombocytopenia (65%/57%) and toxic granulations had a low specifity. The positive predictive value of CRP was 32% before and 37% after 3 days of age, that of leukopenia was 37% in the first 3 days. CONCLUSION: During the first 3 days of life CRP, leukopenia and neutropenia were comparably good tests while after 3 days of life CRP was the best single test in early detection of neonatal septicaemia. Serial CRP estimations confirm the diagnosis, monitor the course of infection and the efficacy of antibiotic treatment.