An unusual natural history of a L5-S1 spondylolisthesis presenting with a sacral insufficiency fracture.

Sacral insufficiency fractures have been described in association with conditions leading to osteoporosis. No association with spondylolisthesis has been described to date. A 60-year-old patient with known lumbosacral isthmic spondylolisthesis presented with exacerbation of symptoms initially thought to be linked to her known spinal pathology. Plain radiography, computer tomography, MRI and bone scan confirmed the presence of a recent sacral insufficiency fracture with anterior angulation. Conservative treatment resulted in improvement of symptoms after 6 months. Care should be taken when considering older patients for more aggressive treatment if they present with exacerbation of back pain and sciatica in the presence of a pre-existing spondylolisthesis. A suspicion of insufficiency fracture should be raised if risk factors exist and further investigations ordered in particular if plain radiography is normal. Lumbosacral fusion might be inappropriate in this setting.

Recent advances in the study of avian malaria: an overview with an emphasis on the distribution of Plasmodium spp in Brazil

Avian malaria parasites (Plasmodium) have a worldwide distribution except for Antarctica. They are transmitted exclusively by mosquito vectors (Diptera: Culicidae) and are of particular interest to health care research due to their phylogenetic relationship with human plasmodia and their ability to cause avian malaria, which is frequently lethal in non-adapted avian hosts. However, different features of avian Plasmodium spp, including their taxonomy and aspects of their life-history traits, need to be examined in more detail. Over the last 10 years, ecologists, evolutionary biologists and wildlife researchers have recognized the importance of studying avian malaria parasites and other related haemosporidians, which are the largest group of the order Haemosporida by number of species. These studies have included understanding the ecological, behavioral and evolutionary aspects that arise in this wildlife host-parasite system. Molecular tools have provided new and exiting opportunities for such research. This review discusses several emerging topics related to the current research of avian Plasmodium spp and some related avian haemosporidians. We also summarize some important discoveries in this field and emphasize the value of using both polymerase chain reaction-based and microscopy-based methods in parallel for wildlife studies. We will focus on the genus Plasmodium, with an emphasis on the distribution and pathogenicity of these parasites in wild birds in Brazil.

Contribution of recombination to the evolutionary history of HIV.

PURPOSE OF REVIEW: An improved understanding of how recombination affects the evolutionary history of HIV is crucial to understand its current and future evolution. The present review aims to disentangle the manifold effects of recombination on HIV by discussing its effects on the evolutionary history and the adaptive potential of HIV in the context of concepts from evolutionary genetics and genomics. RECENT FINDINGS: The increasing occurrence of secondary contacts between divergent subtype populations (during coinfection) results in increased observations of recombinants worldwide. Recombination is heterogeneous along the HIV genome. Consequences of recombination of HIV evolution are, in combination with other demographic processes, expected to either homogenize the genetic composition of HIV populations (homogenization) or provide the potential for novel adaptations (diversification). New methods in population genomics allow deep characterization of recombinant genome (the segment composition and origin) and their evolutionary trajectories. SUMMARY: HIV recombinants increase worldwide and invade geographical regions where pure subtypes were previously predominant. This trend is expected to continue in the future, as ease to travel worldwide increases opportunities for recombination between divergent HIV strains. While the effects of recombination in HIV are much researched, more effort is required to characterize current HIV recombinant composition and dynamics. This can be achieved with new population genetic and genomic methods.

Evolutionary history of almond tree domestication in the Mediterranean basin.

Genetic diversity of contemporary domesticated species is shaped by both natural and human-driven processes. However, until now, little is known about how domestication has imprinted the variation of fruit tree species. In this study, we reconstruct the recent evolutionary history of the domesticated almond tree, Prunus dulcis, around the Mediterranean basin, using a combination of nuclear and chloroplast microsatellites [i.e. simple sequence repeat (SSRs)] to investigate patterns of genetic diversity. Whereas conservative chloroplast SSRs show a widespread haplotype and rare locally distributed variants, nuclear SSRs show a pattern of isolation by distance with clines of diversity from the East to the West of the Mediterranean basin, while Bayesian genetic clustering reveals a substantial longitudinal genetic structure. Both kinds of markers thus support a single domestication event, in the eastern side of the Mediterranean basin. In addition, model-based estimation of the timing of genetic divergence among those clusters is estimated sometime during the Holocene, a result that is compatible with human-mediated dispersal of almond tree out of its centre of origin. Still, the detection of region-specific alleles suggests that gene flow from relictual wild preglacial populations (in North Africa) or from wild counterparts (in the Near East) could account for a fraction of the diversity observed.

Recent human evolution has shaped geographical differences in susceptibility to disease

Background: Searching for associations between genetic variants and complex diseases has been a very active area of research for over two decades. More than 51,000 potential associations have been studied and published, a figure that keeps increasing, especially with the recent explosion of array-based Genome-Wide Association Studies. Even if the number of true associations described so far is high, many of the putative risk variants detected so far have failed to be consistently replicated and are widely considered false positives. Here, we focus on the world-wide patterns of replicability of published association studies.Results: We report three main findings. First, contrary to previous results, genes associated to complex diseases present lower degrees of genetic differentiation among human populations than average genome-wide levels. Second, also contrary to previous results, the differences in replicability of disease associated-loci between Europeans and East Asians are highly correlated with genetic differentiation between these populations. Finally, highly replicated genes present increased levels of high-frequency derived alleles in European and Asian populations when compared to African populations. Conclusions: Our findings highlight the heterogeneous nature of the genetic etiology of complex disease, confirm the importance of the recent evolutionary history of our species in current patterns of disease susceptibility and could cast doubts on the status as false positives of some associations that have failed to replicate across populations.

La public history - histoire apliquée: la història a l'empresa o el potencial de l'arxiu històric

El present article vol posar sobre la taula les aportacions que per al camp dels arxius han suposat les idees del que es coneix en el camp de la historiografia com a public history (món anglosaxó) o histoire apliquée (França). Malgrat que, com es veurà a continuació, la irrupció d'aquesta línia no és recent, la seva repercussió a casa nostra ha estat més aviat escassa, tot i que es donen algunes de les condicions favorables per a una bona recepció.

The recent breakthroughs in the understanding of host genomics in hepatitis C.

BACKGROUND: Hepatitis C Virus (HCV) infection is spontaneously resolved in about 30% of acutely infected individuals. In those who progress to chronic hepatitis C, HCV therapy permanently eradicates infection in about 40% of cases. It has long been suspected that host genetic factors are key determinants for the control of HCV infection. DESIGN: We will review in this study four genome-wide association studies (GWAS) and two large candidate gene studies that assessed the role of host genetic variation for the natural and treatment-induced control of HCV infection. RESULTS: The studies consistently identified genetic variation in interleukin 28B (IL28B) as the strongest predictor for the control of HCV infection. Importantly, single nucleotide polymorphisms (SNPs) in IL28B strongly predicted both spontaneous and treatment-induced HCV recovery. IL28B is located on chromosome 19 and encodes interferon-λ, a type III interferon with antiviral activity, which is mediated through the JAK-STAT pathway by inducing interferon-stimulated genes. The SNPs identified in the GWAS are in high linkage disequilibrium with coding or functional non-coding SNPs that might modulate function and/or expression of IL28B. The role of the different IL28B alleles on gene expression and cytokine function has not yet been established. CONCLUSIONS: These findings provide strong genetic evidence for the influence of interferon-λ for both the natural and treatment-induced control of HCV infection, and support the further investigation of interferon-λ for the treatment of chronic hepatitis C. Furthermore, genetic testing before HCV therapy could provide important information towards an individualized HCV treatment.

History of biological warfare and bioterrorism.

Bioterrorism literally means using microorganisms or infected samples to cause terror and panic in populations. Bioterrorism had already started 14 centuries before Christ, when the Hittites sent infected rams to their enemies. However, apart from some rare well-documented events, it is often very difficult for historians and microbiologists to differentiate natural epidemics from alleged biological attacks, because: (i) little information is available for times before the advent of modern microbiology; (ii) truth may be manipulated for political reasons, especially for a hot topic such as a biological attack; and (iii) the passage of time may also have distorted the reality of the past. Nevertheless, we have tried to provide to clinical microbiologists an overview of some likely biological warfare that occurred before the 18th century and that included the intentional spread of epidemic diseases such as tularaemia, plague, malaria, smallpox, yellow fever, and leprosy. We also summarize the main events that occurred during the modern microbiology era, from World War I to the recent 'anthrax letters' that followed the World Trade Center attack of September 2001. Again, the political polemic surrounding the use of infectious agents as a weapon may distort the truth. This is nicely exemplified by the Sverdlovsk accident, which was initially attributed by the authorities to a natural foodborne outbreak, and was officially recognized as having a military cause only 13 years later.

Comparative genomics of the odorant-binding and chemosensory protein gene families across the arthropoda: origin and evolutionary history of the chemosensory system

Chemoreception is a biological process essential for the survival of animals, as it allows the recognition of important volatile cues for the detection of food, egg-laying substrates, mates or predators, among other purposes. Furthermore, its role in pheromone detection may contribute to evolutionary processes such as reproductive isolation and speciation. This key role in several vital biological processes makes chemoreception a particularly interesting system for studying the role of natural selection in molecular adaptation. Two major gene families are involved in the perireceptor events of the chemosensory system: the odorant-binding protein (OBP) and chemosensory protein (CSP) families. Here, we have conducted an exhaustive comparative genomic analysis of these gene families in twenty Arthropoda species. We show that the evolution of the OBP and CSP gene families is highly dynamic, with a high number of gains and losses of genes, pseudogenes and independent origins of subfamilies. Taken together, our data clearly support the birth-and-death model for the evolution of these gene families with an overall high gene-turnover rate. Moreover, we show that the genome organization of the two families is significantly more clustered than expected by chance and, more important, that this pattern appears to be actively maintained across the Drosophila phylogeny. Finally, we suggest the homologous nature of the OBP and CSP gene families, dating back their MRCA (most recent common ancestor) to 380¿420 Mya, and we propose a scenario for the origin and diversification of these families.

Chromosomal versus mitochondrial DNA evolution: tracking the evolutionary history of the southwestern european populations of the Sorex araneus group (Mammalia Insectivora)

The shrews of the Sorer araneus group have undergone a spectacular chromosome evolution. The karyotype of Sorer granarius is generally considered ancestral to those of Sorer coronatus and S. araneus. However, a sequence of 777 base pairs of the cytochrome b gene of the mitochondrial DNA (mtDNA) produces a quite different picture: S. granarius is closely related to the populations of S. araneus from the Pyrenees and from the northwestern Alps, whereas S. coronatus and S. araneus from Italy and the southern Alps represent two well-separated lineages. It is suggested that mtDNA and chromosomal evolution are in this case largely independant processes. Whereas mtDNA haplotypes are closely linked to the geographical history of the populations, chromosomal mutations were probably transmitted from one population to another. Available data suggest that the impressive chromosome polymorphism of this group is quite a recent phenomenon.

Predicting the mating system from phenotypic correlations between life-history and sperm quality traits in the Alpine whitefish Coregonus zugensis

The mating behavior and reproductive strategies of Alpine whitefish like Coregonus zugensis (Nusslin) are poorly understood, probably because they spawn in deep water where direct observations are difficult. In this study, we interpret life-history and sperm quality traits of fish that we caught from their spawning place. We found that males invest heavily into gonadal tissue (up to 5.6% of their body weight), which is, in comparison to other fish, consistent with external fertilization, distinct pairing and moderate to high communal spawning, or no pairing and low to moderate communal spawning. Sperm competition theory and recent experimental studies on other salmonids predict that males optimize ejaculate characteristics in relation to the costs of sperm and the level of competition they have to expect: dominant males are predicted to invest less into ejaculate quality and to have slower spermatozoa than subdominant males. We found that spermatozoa of older males are slower than those of younger males. Moreover, older males have larger breeding tubercles, a secondary sexual trait that has, in some previous studies, been found to be linked to good condition and to good genetic quality. Our results suggest that C. zugensis has age-linked reproductive strategies, that multimale spawning is common, i.e., that sperm competition plays a significant role, and that older males are on average dominant over younger males at the spawning place.

Anamnèse familiale: utile ou futile. [Family history: useful or futile?]

Family history (FH) represents an important tool in clinical practice that allows assessing an increased risk to develop certain diseases as it captures genetic and environmental factors within a family. FH was shown to be important for several conditions such as type 2 diabetes mellitus and cardiovascular diseases as it allows identifying subjects who can potentially benefit from specific diagnostic and therapeutic measures. We also show that FH remains an important tool even in this period of recent progress in molecular genetics and that it is probably underused in the clinical setting.

Interrogating eleven fast-evolving genes for signatures of recent positive selection in worldwide human populations

Different signatures of natural selection persist over varying time scales in our genome, revealing possible episodes of adaptative evolution during human history. Here, we identify genes showing signatures of ancestral positive selection in the human lineage and investigate whether some of those genes have been evolving adaptatively in extant human populations. Specifically, we compared more than 11,000 human genes with their orthologs inchimpanzee, mouse, rat and dog and applied a branch-site likelihood method to test for positive selection on the human lineage. Among the significant cases, a robust set of 11 genes were then further explored for signatures of recent positive selection using SNP data. We genotyped 223 SNPs in 39 worldwide populations from the HGDP Diversity panel and supplemented this information with available genotypes for up to 4,814 SNPs distributed along 2 Mb centered on each gene. After exploring the allele frequency spectrum, population differentiation and the maintainance of long unbroken haplotypes, we found signals of recent adaptative phenomena in only one of the 11 candidate gene regions. However, the signal ofrecent selection in this region may come from a different, neighbouring gene (CD5) ratherthan from the candidate gene itself (VPS37C). For this set of positively-selected genes in thehuman lineage, we find no indication that these genes maintained their rapid evolutionarypace among human populations. Based on these data, it therefore appears that adaptation forhuman-specific and for population-specific traits may have involved different genes.