A medium for inducing conversion of Histoplasma capsulatum var. capsulatum into its yeast-like form

Histoplasma capsulatum var. capsulatum is a dimorphic fungus that, under special conditions, converts from its more common mycelial form to a yeast-like form. Achieving this conversion, however, has been problematical for researchers. The present study tested conversion rates in ten Histoplasma capsulatum var. capsulatum strains using seven culture media, four of wich were conventional and three novel. One of our novel media, MLGema, induced complete conversion, of two strains within five days of incubation at 35 degrees centigrades, and of all strains that eventually converted by the time of the second subculturing transfer, under defined experimental conditions. MLGema is also inexpensive and easy to produce.

The feasibility of forecasting influenza epidemics in Cuba

A large influenza epidemic took place in Havana during the winter of 1988. The epidemiologic surveillance unit of the Pedro Kouri Institute of Tropical Medicine detected the begining of the epidemic wave. The Rvachev-Baroyan mathematical model of the geographic spread of an epidemic was used to forecast this epidemic under routine conditions of the public health system. The expected number of individuals who would attend outpatient services, because of influenza-like illness, was calculated and communicated to the health authorities within enough time to permit the introduction of available control measures. The approximate date of the epidemic peak, the daily expected number of individuals attending medical services, and the approximate time of the end of the epidemic wave were estimated. The prediction error was 12%. The model was sufficienty accurate to warrant its use as a pratical forecasting tool in the Cuban public health system.

Heterologous desensitization of the glucagon-like peptide-1 receptor by phorbol esters requires phosphorylation of the cytoplasmic tail at four different sites.

Glucagon-like peptide-1 stimulates glucose-induced insulin secretion by binding to a specific G protein-coupled receptor that activates the adenylyl cyclase pathway. We previously demonstrated that heterologous desensitization of the receptor by protein kinase C correlated with phosphorylation in a 33-amino acid-long segment of the receptor carboxyl-terminal cytoplasmic tail. Here, we determined that the in vivo sites of phosphorylation are four serine doublets present at positions 431/432, 441/442, 444/445, and 451/452. In vitro phosphorylation of fusion proteins containing mutant receptor C-tails, however, indicated that whereas serines at position 431/432 were good substrates for protein kinase C (PKC), serines 444/445 and 451/452 were poor substrates, and serines 441/442 were not substrates. In addition, serine 416 was phosphorylated on fusion protein but not in intact cells. This indicated that in vivo a different PKC isoform or a PKC-activated kinase may phosphorylate the receptor. The role of phosphorylation on receptor desensitization was assessed using receptor mutants expressed in COS cells or Chinese hamster lung fibroblasts. Mutation of any single serine doublet to alanines reduced the extent of phorbol 12-myristate 13-acetate-induced desensitization, whereas substitution of any combination of two serine doublets suppressed it. Our data thus show that the glucagon-like peptide-1 receptor can be phosphorylated in response to phorbol 12-myristate 13-acetate on four different sites within the cytoplasmic tail. Furthermore, phosphorylation of at least three sites was required for desensitization, although maximal desensitization was only achieved when all four sites were phosphorylated.

Linkages of dietary patterns, international trade and land use: the case of olive oil in the European Union

Within only two decades olive oil developed from a niche product which could hardly be found in food stores outside the producing regions towards an integrated component in the diets of industrial countries. This paper discusses the impacts of the promotion of the “healthy Mediterranean diet” on land use and agro-ecosystems in the producing countries. It examines the dynamics of olive oil production, trade and consumption in the EU15 in the period 1972 to 2003 and the links between dietary patterns, trade and land use. It analyses the underlying socio-economic driving forces behind the increasing spatial disconnect between production and consumption of olive oil in the EU15 and in particular in Spain, the world largest producer during the last three decades. In the observed period olive oil consumption increased 16 fold in the non-producing EU15 countries. In the geographically limited producing regions like Spain, the 5 fold increase in export production was associated with the rapid industrialization of olive production, the conversion of vast Mediterranean landscapes to olive monocultures and a range of environmental pressures. High amounts of subsidies of the European Common Agricultural Policy and feedback loops within production and consumption systems were driving the transformation of the olive oil system. Our analysis indicates the process of change was not immediately driven by increases in demand for olive oil in non-producing countries, but rather by the institutional setting of the European Union and by concerted political interventions.

Tumor antigen-specific FOXP3+ CD4 T cells identified in human metastatic melanoma: peptide vaccination results in selective expansion of Th1-like counterparts.

We have previously shown that vaccination of HLA-A2 metastatic melanoma patients with the analogue Melan-A(26-35(A27L)) peptide emulsified in a mineral oil induces ex vivo detectable specific CD8 T cells. These are further enhanced when a TLR9 agonist is codelivered in the same vaccine formulation. Interestingly, the same peptide can be efficiently recognized by HLA-DQ6-restricted CD4 T cells. We used HLA-DQ6 multimers to assess the specific CD4 T-cell response in both healthy individuals and melanoma patients. We report that the majority of melanoma patients carry high frequencies of naturally circulating HLA-DQ6-restricted Melan-A-specific CD4 T cells, a high proportion of which express FOXP3 and proliferate poorly in response to the cognate peptide. Upon vaccination, the relative frequency of multimer+ CD4 T cells did not change significantly. In contrast, we found a marked shift to FOXP3-negative CD4 T cells, accompanied by robust CD4 T-cell proliferation upon in vitro stimulation with cognate peptide. A concomitant reduction in TCR diversity was also observed. This is the first report on direct ex vivo identification of antigen-specific FOXP3+ T cells by multimer labeling in cancer patients and on the direct assessment of the impact of peptide vaccination on immunoregulatory T cells.

Like milk or wine: Does firm performance improve with age?

Our empirical literature review shows that little is known about how firm performance changes with age, presumably because of the paucity of data on firm age. For Spanish manufacturing firms, we analyse the firm performance related to firm age between 1998 and 2006. We find evidence that firms improve with age, because ageing firms are observed to have steadily increasing levels of productivity, higher profits, larger size, lower debt ratios, and higher equity ratios. Furthermore, older firms are better able to convert sales growth into subsequent growth of profits and productivity. On the other hand, we also found evidence that firm performance deteriorates with age. Older firms have lower expected growth rates of sales, profits and productivity, they have lower profitability levels (when other variables such as size are controlled for), and also that they appear to be less capable to convert employment growth into growth of sales, profits and productivity.

Genetic survey of "spinturnix sp" (Acari, Mesostigmata) and their bat hosts in Western Palearctic

SUMMARY : The coevolution between two intimately associated organisms, like host and parasite, is a widely investigated theme in evolutionary biology. Recently, the use of genetic data in the study of host-parasite systems evidences that the genetic information from some parasites can complement genetic data from their hosts and thus may help to better understand their host's evolutionary history. Phylogenetic and population genetic aspects of bat parasites have been poorly investigated. Spinturnicid mites are highly specialized ectoparasites, exclusively associated with bats and therefore represent an ideal model to extant our knowledge on bat and parasite biology and on their coevolutionary history. In this thesis, I developed several molecular markers (mitochondrial DNA) to compare the genetic patterns of Spinturnix mites with their bat hosts at different levels. The molecular co-phylogeny between Spinturnix sp. and their bat hosts suggests a partial cospeciation and the occurrence of failure to speciate events and multiple host switches. Thus, Spinturnix mites do not exactly mirror the phylogenetic pattern of their hosts, despite their intimate association. Similar roosting habits of the hosts seem to promote host switches between different species, as far as ecological conditions are favourable. The phylogeographic study of the Maghrebian bat M. punicus in the Mediterranean area confirms the presence of M. punicus in North Africa, Corsica and Sardinia and highlights that islands and mainland are genetically highly divergent. The comparison between the parasitic mite S. myoti and the Maghrebian bat suggests that the phylogeographic pattern of the mite is moulded by its host, with open water as main barrier for host and parasite dispersal. Moreover, the unique presence of a European S. myoti lineage on M. punicus from Corsica strongly suggests the former presence of mouse-eared bats (M. myotis and/or M. blythii) in Corsica. By highlighting the probable presence of a nowadays locally extinct host species, S. myoti may represent a good proxy for inferring complex evolutionary history of bat hosts. Finally, population genetic surveys of S. myoti and S. bechsteinii suggest that these mites benefit from close contacts between individuals during the mating season and/or hibernation to disperse among remote colonies. The contrasted genetic patterns of these two distinct bat-mite systems evidence that bat social structure is a determinant factor of the genetic structure of mite populations. Altogether, this PhD thesis demonstrates the usefulness of parasites to gather information about their bat hosts. In addition, my results illustrate how different ecological and biological characteristics of bat species allow the emergence of a surprising diversity in the genetic patterns of the parasites, which may contribute to the diversification and speciation of parasites. RESUME : La co-évolution entre deux organismes intimement liés, comme un parasite et son hôte, fait partie des questions largement étudiées en biologie évolutive. Récemment, l'utilisation de données génétique dans l'étude des interactions hôte-parasite a montré que l'information génétique de certains parasites peut compléter les données génétiques de l'hôte et ainsi peut éclairer l'histoire évolutive de leur hôte. Très peu études ont étudié les interactions entre les chauves-souris et leurs parasites d'un point de vue moléculaire. Les acariens du genre Spinturnix sont des ectoparasites très spécialisés exclusivement associés aux chauves-souris. Ils représentent donc un model idéal pour élargir nos connaissances tant sur l'écologie des parasites de chauves-souris que sur leur coévolution. Durant cette thèse, plusieurs marqueurs moléculaires (ADN mitochondrial) ont été développés pour ainsi comparer la distribution de la variation génétique des parasites du genre Spinturnix avec celle de leurs hôtes, et ceci à différents niveaux. Tout d'abord, la co-phylogénie moléculaire entre les espèces de Spinturnix et les leurs hôtes révèle une co-spéciation partielle ainsi que la présence d'événement de non spéciation et de transferts horizontaux. Ces parasites ne reflètent donc pas entièrement l'histoire évolutive de leurs hôtes, malgré leurs intimes associations. La cohabitation de plusieurs espèces de chauves-souris dans un même gîte permet aux parasites un transfert entre différentes espèces, atténuant ainsi leur degré de co-spéciation. Deuxièmement, l'étude phylogéographique du marin du Maghreb dans le bassin Méditerranéen confirme sa présence en Afrique du Nord, en Corse et en Sardaigne. La comparaison avec un de ses parasites S. myoti suggère que la répartition génétique de S. myoti est façonnée par celle de leurs hôtes, avec les étendues d'eau comme barrière principale tant à la dispersion de l'hôte que de son parasite. De plus, la présence unique d'une lignée européenne de ces parasites sur des marins du Maghreb de Corse suggère fortement la présence du grand ou petit marin en Corse dans le passé. En reflétant la présence potentielle à un endroit donné d'une espèce de chauve-souris actuellement disparue, S. myoti peut représenter une bonne alternative pour comprendre l'histoire évolutive complexe des chauves-souris. Finalement, l'étude des structures génétiques des populations des parasites S. myoti et S. bechsteinii suggère que les contacts corporels entre chauves-souris durant la saison de reproduction ou l'hibernation peuvent permettre la dispersion des parasites entre des colonies éloignées géographiquement. La différence de structure génétique entre ces deux associations particulières montre que la structure génétique des populations de parasites dépend fortement des traits d'histoire de vie de son hôte. Dans l'ensemble, cette thèse démontre l'importance des parasites pour amener des informations sur leurs hôtes, les chauves-souris. Elle illustre aussi comment les différences écologique et biologique des différentes espèces de chauves-souris peuvent amener une étonnante diversité de structure génétique au sein de populations de parasites, ce qui peut peut-être contribuer à la diversification et à la spéciation des parasites.

The cave-like sense organ in the antennae of Triatominae bugs

In the second segment of the antennae of haematophagous reduviids an unusual cave-like organ is found the function os which was investigated in Triatoma infestans. the morphology of the organ makes it difficult to ascribe it to a mechno- or chemoreceptive function, but shows some characteristics shared with thermoreceptors of other animals. The electrical activity of sense cells was recorded in the presence of stimuli that evoke behavioural responses in this species, i.e. warm, CO2, lactic and butyric acids at different concentrations. The three compounds tested failed to evoke a response at all concentrations assayed. Only thermal stimulation evinced a clear modification in the electrical activity of the sense cells.Both the morphological and electrophysiological findings support a thermoreceptive finding, habitat selection and circadian synchronization.

Autosomal-Recessive Posterior Microphthalmos Is Caused by Mutations in PRSS56, a Gene Encoding a Trypsin-Like Serine Protease.

Posterior microphthalmos (MCOP) is a rare isolated developmental anomaly of the eye characterized by extreme hyperopia due to short axial length. The population of the Faroe Islands shows a high prevalence of an autosomal-recessive form (arMCOP) of the disease. Based on published linkage data, we refined the position of the disease locus (MCOP6) in an interval of 250 kb in chromosome 2q37.1 in two large Faroese families. We detected three different mutations in PRSS56. Patients of the Faroese families were either homozygous for c.926G>C (p.Trp309Ser) or compound heterozygous for c.926G>C and c.526C>G (p.Arg176Gly), whereas a homozygous 1 bp duplication (c.1066dupC) was identified in five patients with arMCOP from a consanguineous Tunisian family. In one patient with MCOP from the Faroe Islands and in another one from Turkey, no PRSS56 mutation was detected, suggesting nonallelic heterogeneity of the trait. Using RT-PCR, PRSS56 transcripts were detected in samples derived from the human adult retina, cornea, sclera, and optic nerve. The expression of the mouse ortholog could be first detected in the eye at E17 and was maintained into adulthood. The predicted PRSS56 protein is a 603 amino acid long secreted trypsin-like serine peptidase. The c.1066dupC is likely to result in a functional null allele, whereas the two point mutations predict the replacement of evolutionary conserved and functionally important residues. Molecular modeling of the p.Trp309Ser mutant suggests that both the affinity and reactivity of the enzyme toward in vivo protein substrates are likely to be substantially reduced.

Tritordeum, wheat and triticale yield components under multi-local mediterranean drought conditions

The species x location interaction was of great importance in explaining the behaviour of genetic material. The study presented here shows, for the first time, the performance, under field conditions of the new tritordeum species, compared to wheat and triticale in a wide range of Mediterranean countries (Spain, Lebanon and Tunisia). The results obtained revealed that despite the diversity of environmental conditions, the main differences in yield were due to genotypes, especially to differences between species. The multi-local study with different growth conditions revealed important information about the water availability effect on yield. In the lowest yielding environments (Tunisia rainfed), Tritordeum and triticale yields were equivalent. However under better growth conditions (Spain), tritordeum yield was shown to be lower than wheat and triticale. Interestingly, when water limitation was extended during the pre-anthesis period, differences in tritordeum versus wheat-triticale yield rate were larger than when water stress occurred during anthesis. These variations were explained by the fact that kernel weight has been found as the limiting factor for yield determination in tritordeum, and a delay in the anthesis date may have been the cause for the low kernel weight and low yield under Mediterranean drought conditions. Such differences in yield between tritordeum and wheat or triticale could be explained by the fact that tritordeum is a relatively new species and far fewer resources have been devoted to its improvement when compared to wheat and triticale. Our results suggest that breeding efforts should be directed to an earlier anthesis date and a longer grain filling period. tritordeum proved to have possibilities to be grown under drought environments as a new crop, since its performance was quite close to wheat and triticale. Besides, it has qualitative added values that may improve farmers' income per unit land.

Effects of increased drought and selective thinning on growth and resprouting of two coexisting Mediterranean oaks with contrasting leaf habit (Quercus ilex and Quercus cerrioides)

According to the IPCC (2007), the Mediterranean basin is expected to suffer important changes in temperature and precipitation in the next few decades, leading the climate warmer and dryer. Therefore, it is necessary to determine the possible effects of increased drought on species with different structural and physiological traits, to be able to predict possible changes in the structure and composition of Mediterranean forests. Moreover, it will be necessary to assess whether traditional management practices can mitigate the effects of climate change on these forests. The main aim of this study has been to analyze the effects of increased drought on the mortality, growth and resprouting patterns of two co-occurring Mediterranean oak species with contrasting leaf habit (the evergreen Quercus ilex and the winter-deciduous Quercus cerrioides), and to assess the effects of selective thinning on their response to increased drought. Our results show a differential effect of increased drought between species: no differences were observed in the growth of Q. ilex while Q. cerrioides reduced its growth under increased drought conditions. Selective thinning reduced the negative effects of increased drought on tree growth, although this beneficial effect tended to decrease during the experiment. Our results show that increasing aridity in Mediterranean areas can be a constraining factor for deciduous oaks, thus potentially causing their decline in mixed forests and favouring their substitution by the evergreen congeneric species. However, as seen in this study, management can strongly encourage growth both for deciduous and evergreen species, thus reversing the effects of increased water stress on Mediterranean coppices.

Turning sunlight into stone: the oxalate-carbonate pathway in a tropical tree ecosystem.

An African oxalogenic tree, the iroko tree (Milicia excelsa), has the property to enhance carbonate precipitation in tropical oxisols, where such accumulations are not expected due to the acidic conditions in these types of soils. This uncommon process is linked to the oxalate-carbonate pathway, which increases soil pH through oxalate oxidation. In order to investigate the oxalate-carbonate pathway in the iroko system, fluxes of matter have been identified, described, and evaluated from field to microscopic scales. In the first centimeters of the soil profile, decaying of the organic matter allows the release of whewellite crystals, mainly due to the action of termites and saprophytic fungi. In addition, a concomitant flux of carbonate formed in wood tissues contributes to the carbonate flux and is identified as a direct consequence of wood feeding by termites. Nevertheless, calcite biomineralization of the tree is not a consequence of in situ oxalate consumption, but rather related to the oxalate oxidation inside the upper part of the soil. The consequence of this oxidation is the presence of carbonate ions in the soil solution pumped through the roots, leading to preferential mineralization of the roots and the trunk base. An ideal scenario for the iroko biomineralization and soil carbonate accumulation starts with oxalatization: as the iroko tree grows, the organic matter flux to the soil constitutes the litter, and an oxalate pool is formed on the forest ground. Then, wood rotting agents (mainly termites, saprophytic fungi, and bacteria) release significant amounts of oxalate crystals from decaying plant tissues. In addition, some of these agents are themselves producers of oxalate (e.g. fungi). Both processes contribute to a soil pool of "available" oxalate crystals. Oxalate consumption by oxalotrophic bacteria can then start. Carbonate and calcium ions present in the soil solution represent the end products of the oxalate-carbonate pathway. The solution is pumped through the roots, leading to carbonate precipitation. The main pools of carbon are clearly identified as the organic matter (the tree and its organic products), the oxalate crystals, and the various carbonate features. A functional model based on field observations and diagenetic investigations with δ13C signatures of the various compartments involved in the local carbon cycle is proposed. It suggests that the iroko ecosystem can act as a long-term carbon sink, as long as the calcium source is related to non-carbonate rocks. Consequently, this carbon sink, driven by the oxalate carbonate pathway around an iroko tree, constitutes a true carbon trapping ecosystem as defined by ecological theory.