Diversity, prevalence and virulence of fungal entomopathogens in colonies of the ant Formica selysi

The richness of the parasitic community associated with social insect colonies has rarely been investigated. Moreover, understanding how hosts and pathogens interact in nature is important to interpret results from laboratory experiments. Here, we assessed the diversity, prevalence and virulence of fungal entomopathogens present around and within colonies of the ant Formica selysi. We detected eight fungal species known to be entomopathogenic in soil sampled from the habitat of ants. Six of these entomopathogens were found in active nests, abandoned nests, and corpses from dump piles or live ants. A systematic search for the presence of three generalist fungal entomopathogens in ant colonies revealed a large variation in their prevalence. The most common of the three pathogens, Paecilomyces lilacinus, was detected in 44% of the colonies. Beauveria bassiana occurred in 17% of the colonies, often in association with P. lilacinus, whereas we did not detect Metarhizium brunneum (formerly M. anisopliae) in active colonies. The three fungal species caused significant mortality to experimentally challenged ants, but varied in their degree of virulence. There was a high level of genetic diversity within B. bassiana isolates, which delineated three genetic strains that also differed significantly in their virulence. Overall, our study indicates that the ants encounter a diversity of fungal entomopathogens in their natural habitat. Moreover, some generalist pathogens vary greatly in their virulence and prevalence in ant colonies, which calls for further studies on the specificity of the interactions between the ant hosts and their fungal pathogens.

The adaptative function of melanin-based colour variants

Résumé : Les mécanismes de contrôle des couleurs mélaniques chez les vertébrés sont encore discutés parmi les biologistes de l'évolution. Une hypothèse récente affirme que les effets pléiotropies du système des mélanocortines expliquent l'association fréquente entre la coloration eumélanique noire (due à la déposition d'eumélanine) et de nombreux traits physiologiques et comportementaux. De nombreuses études suggèrent, en effet, que des niveaux plus élevés des mélanocortines induisent l'assombrissement des téguments eumélaniques et affectent d'autres traits phénotypiques simultanément. Cependant, il n'est pas encore établi si ce mécanisme de pléiotropie peut s'appliquer aux colorations dues à la déposition de phaeomélanine, une autre forme commune de mélanine. Les antagonistes des mélanocortines déclenchent le phaeomélanogenèse et bloquent l'effet des mélanocortines ou ont un effet pharmacologique opposé. Nous nous proposons donc d'évaluer l'hypothèse que les effets pléiotropes des antagonistes des mélanocortines génèrent des covariations entre la coloration phaeomélanique et des aspects de la qualité individuelle. Comme prédit par cette hypothèse, nous constatons chez la chouette effraie (Tyto alba) que les traits phénotypiques (résistance au stress oxydatif et aux parasites) corrèlent positivement au degré d'expression d'une couleur eumélanique mais négativement au degré d'expression d'une coloration phaeomélanique. Puis, nous montrons chez la chouette hulotte (Strix aluco) que les associations génétiques entre la coloration phaeomélanique et la physiologie (immunité et la régulation de l'homéostasie) confèrent des avantages aux individus de différentes couleurs dans différents environnements caractérisés par l'abondance de nourriture et le niveau d'exposition aux parasites. Ainsi, nos études soutiennent l'hypothèse que les effets pléiotropes des antagonistes des mélanocortines génèrent des covariations entre les traits mélaniques et divers aspects de la qualité individuelle. Finalement, nous montrons chez le faucon crécerelle (Falco Tinnunculus) que l'expression des ornements mélaniques est sensible à la qualité de l'environnement dans lequel les individus grandissent. Ceci suggère que les gènes codant pour les mélanocortines et leurs antagonistes pourraient induire une expression des traits mélaniques dépendante de la condition de l'individu, un pattern d'expression rarement observé pour des traits généralement sous fort contrôle génétique. Summary : The information content and control mechanisms of melanin-based colour signals in vertebrates are still debated among evolutionary biologists. A recent hypothesis contends that pleiotropic effects of the melanocortin system accounts for the frequent association between black eumelanic coloration and physiological and behavioural traits. Accordingly, empirical evidence suggests that higher levels of melanocortins concurrently promote darker eumelanic integuments and affect other phenotypic traits. However, whether this mechanism may apply to signals relying on phaeomelanin, another common form of melanin pigments, remains to be established. Melanocortin antagonists trigger phaeomelanogenesis and block the effect of melanocortins or result in the opposite pharmacological effect. Therefore, we tested the hypothesis that pleiotropic effects of melanocortin antagonists and inverse agonists account for covariations between phaeomelanin-based coloration and aspects of individual quality. As predicted, we found that phenotypic traits (resistance to oxidative stress and parasites) correlated positively with a eumelanic trait and negatively with a phaeomelanic trait in the barn owl (Tyto alba). Then, we showed in the tawny owl (Strix aluco) that genetic associations between phaeomelanin-based coloration and physiology (immunity and regulation of energy homeostasis) confer benefits to differently coloured individuals under different levels of food abundance and parasite exposure. Altogether, our studies support the hypothesis that pleiotropic effects of melanocortins antagonists can indeed account for covariations between phaeomelanin-based traits and aspects of individual quality. Eventually, we show in the Eurasian kestrel (Falco Tinnunculus) that expression of melanin-based ornaments is sensitive to the environment in which individuals grow. This suggests that genes coding for melanocortins and their antagonists can mediate the condition-dependent component of melanin-based traits.

Business Cycles, Unemployment Insurance, and the Calibration of Matching Models

This paper points out an empirical puzzle that arises when an RBC economy with a job matching function is used to model unemployment. The standard model can generate sufficiently large cyclical fluctuations in unemployment, or a sufficiently small response of unemployment to labor market policies, but it cannot do both. Variable search and separation, finite UI benefit duration, efficiency wages, and capital all fail to resolve this puzzle. However, both sticky wages and match-specific productivity shocks help the model reproduce the stylized facts: both make the firm's flow of surplus more procyclical, thus making hiring more procyclical too.

Latissimus dorsi muscle-flap over Gore-Tex patch for coverage of large thoracic defects in paediatric Ewing sarcoma.

Primary rib involvement accounts for 16% of paediatric Ewing sarcoma (ES). Neo-adjuvant chemotherapy and surgical tumor resection may leave large thoracic wall defects requiring complex reconstruction in a growing individual. We report our experience in three children aged 3, 10, and 12 years, in whom single-stage resection and reconstruction were performed using a Gore-Tex Dualmesh patch, covered by a latissimus dorsi rotation flap harvested in continuity with the thoracolumbar fascia. The youngest patient also had a vertical expandable prosthetic titanium rib (VEPTR) anchored to help prevent subsequent scoliosis throughout growth.

Stable isotope ecology of Miocene large mammals from Sandelzhausen, southern Germany

The carbon, oxygen, and strontium isotope composition of enamel from teeth of large Miocene herbivorous mammals from Sandelzhausen (MN5, late Early/early Middle Miocene) in the North Alpine foreland basin, were analyzed to infer diet and habitat. The mean enamel delta(13)C value of -11.4 +/- 1.0% (n = 53) for the nine taxa analyzed (including proboscideans, cervids, suids, chalicotheres, equids, rhinocerotids) indicates a pure C(3) plant diet for all mammals. (87)Sr/(86)Sr ratios of similar to 0.710 higher than those from teeth of the western Molasse Basin (0.708-0.709) seem to indicate preferential feeding of the mammals in the northeastern Molasse Basin. The sympatric herbivores have different mean delta(13)C and delta(18)O values which support diet partitioning and/or use of different habitats within a C(3) plant ecosystem. Especially the three sympatric rhinoceroses Plesiaceratherium fahlbuschi, Lartetotherium sansaniense, and Prosantorhinus germanicus show clear partitioning of plants and/or habitats. The palaeomerycid Germanomeryx fahlbuschi was a canopy folivore in moderately closed environments whereas Metaschizotherium bavaricum (Chalicotheriidae) and P. germanicus (Rhinocerotidae) were browsers in more closed forest environments. The horse Anchitherium aurelianense was probably a more generalized feeder than assumed from its dental morphology. The forest hog Hyotherium soemmeringi has the highest delta(13)C and lowest delta(18)O value of all analyzed taxa, possibly related to a frugivorous diet. Most taxa were water-dependent browsers that record meteoric water delta(18)O values of about -5.6 +/- 0.7% Vienna Standard Mean Ocean Water (VSMOW). Using a modern-day mean annual air temperature (MAT)-delta(18)OH(2)O relation a MAT of 19.3 +/- 1.5 degrees C can be reconstructed for Sandelzhausen. A Gomphotherium subtapiroideum tusk serially sampled for delta(18)O values does not record a clear pattern of seasonality. Thus most taxa were C(3) browsers in a forested and humid floodplain environment in the Molasse Basin, which experienced a warm-temperate to subtropical climate and possibly low seasonality.

Reverse transcription quantitative real-time polymerase chain reaction reference genes in the spared nerve injury model of neuropathic pain: validation and literature search.

BACKGROUND: The reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) is a widely used, highly sensitive laboratory technique to rapidly and easily detect, identify and quantify gene expression. Reliable RT-qPCR data necessitates accurate normalization with validated control genes (reference genes) whose expression is constant in all studied conditions. This stability has to be demonstrated.We performed a literature search for studies using quantitative or semi-quantitative PCR in the rat spared nerve injury (SNI) model of neuropathic pain to verify whether any reference genes had previously been validated. We then analyzed the stability over time of 7 commonly used reference genes in the nervous system - specifically in the spinal cord dorsal horn and the dorsal root ganglion (DRG). These were: Actin beta (Actb), Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ribosomal proteins 18S (18S), L13a (RPL13a) and L29 (RPL29), hypoxanthine phosphoribosyltransferase 1 (HPRT1) and hydroxymethylbilane synthase (HMBS). We compared the candidate genes and established a stability ranking using the geNorm algorithm. Finally, we assessed the number of reference genes necessary for accurate normalization in this neuropathic pain model. RESULTS: We found GAPDH, HMBS, Actb, HPRT1 and 18S cited as reference genes in literature on studies using the SNI model. Only HPRT1 and 18S had been once previously demonstrated as stable in RT-qPCR arrays. All the genes tested in this study, using the geNorm algorithm, presented gene stability values (M-value) acceptable enough for them to qualify as potential reference genes in both DRG and spinal cord. Using the coefficient of variation, 18S failed the 50% cut-off with a value of 61% in the DRG. The two most stable genes in the dorsal horn were RPL29 and RPL13a; in the DRG they were HPRT1 and Actb. Using a 0.15 cut-off for pairwise variations we found that any pair of stable reference gene was sufficient for the normalization process. CONCLUSIONS: In the rat SNI model, we validated and ranked Actb, RPL29, RPL13a, HMBS, GAPDH, HPRT1 and 18S as good reference genes in the spinal cord. In the DRG, 18S did not fulfill stability criteria. The combination of any two stable reference genes was sufficient to provide an accurate normalization.

Epidemiological characterization of Plasmodium falciparum in the Republic of Cabo Verde: implications for potential large-scale re-emergence of malaria

Background: Malaria has come near eradication at archipelago of Cabo Verde in 1970. Infections are now only observed in Santiago, where outbreaks occur. In these islands, malaria is considered by the international community as being of limited risk and, therefore, no prophylaxis is recommended. Since the understanding of factors that determine malaria outbreaks are crucial for controlling the disease, the present study aimed to investigate if the malaria infections observed in Santiago Island are maintained in isolated foci and in asymptomatic individuals.

Large-scale evolutionary trends of Acrochordiceratidae Arthaber, 1911 (Ammonoidea, Middle Triassic) and Cope's rule

Directed evolution of life through millions of years, such as increasing adult body size, is one of the most intriguing patterns displayed by fossil lineages. Processes and causes of such evolutionary trends are still poorly understood. Ammonoids (externally shelled marine cephalopods) are well known to have experienced repetitive morphological evolutionary trends of their adult size, shell geometry and ornamentation. This study analyses the evolutionary trends of the family Acrochordiceratidae Arthaber, 1911 from the Early to Middle Triassic (251228 Ma). Exceptionally large and bed-rock-controlled collections of this ammonoid family were obtained from strata of Anisian age (Middle Triassic) in north-west Nevada and north-east British Columbia. They enable quantitative and statistical analyses of its morphological evolutionary trends. This study demonstrates that the monophyletic clade Acrochordiceratidae underwent the classical evolute to involute evolutionary trend (i.e. increasing coiling of the shell), an increase in its shell adult size (conch diameter) and an increase in the indentation of its shell suture shape. These evolutionary trends are statistically robust and seem more or less gradual. Furthermore, they are nonrandom with the sustained shift in the mean, the minimum and the maximum of studied shell characters. These results can be classically interpreted as being constrained by the persistence and common selection pressure on this mostly anagenetic lineage characterized by relatively moderate evolutionary rates. Increasing involution of ammonites is traditionally interpreted by increasing adaptation mostly in terms of improved hydrodynamics. However, this trend in ammonoid geometry can also be explained as a case of Copes rule (increasing adult body size) instead of functional explanation of coiling, because both shell diameter and shell involution are two possible paths for ammonoids to accommodate size increase.

Optimised search heuristic combining valid inequalities and tabu search

This paper presents an Optimised Search Heuristic that combines a tabu search method with the verification of violated valid inequalities. The solution delivered by the tabu search is partially destroyed by a randomised greedy procedure, and then the valid inequalities are used to guide the reconstruction of a complete solution. An application of the new method to the Job-Shop Scheduling problem is presented.