Comparative genomics of Mortierella elongata and its bacterial endosymbiont Mycoavidus cysteinexigens.

Endosymbiosis of bacteria by eukaryotes is a defining feature of cellular evolution. In addition to well-known bacterial origins for mitochondria and chloroplasts, multiple origins of bacterial endosymbiosis are known within the cells of diverse animals, plants and fungi. Early-diverging lineages of terrestrial fungi harbor endosymbiotic bacteria belonging to the Burkholderiaceae. We sequenced the metagenome of the soil-inhabiting fungus Mortierella elongata and assembled the complete circular chromosome of its endosymbiont, Mycoavidus cysteinexigens, which we place within a lineage of endofungal symbionts that are sister clade to Burkholderia. The genome of M. elongata strain AG77 features a core set of primary metabolic pathways for degradation of simple carbohydrates and lipid biosynthesis, while the M. cysteinexigens (AG77) genome is reduced in size and function. Experiments using antibiotics to cure the endobacterium from the host demonstrate that the fungal host metabolism is highly modulated by presence/absence of M. cysteinexigens. Independent comparative phylogenomic analyses of fungal and bacterial genomes are consistent with an ancient origin for M. elongata - M. cysteinexigens symbiosis, most likely over 350 million years ago and concomitant with the terrestrialization of Earth and diversification of land fungi and plants.

MRI of acute osteomyelitis in long bones of children: Pathophysiology study.

INTRODUCTION: The classic pathophysiology of acute osteomyelitis in children described by Trueta has a metaphyseal infection as the starting point. This hypothesis was recently brought into question by Labbé's study, which suggested a periosteal origin. Thus, we wanted to study this disease's pathophysiology through early MRI examinations and to look for prognostic factors based on abnormal findings. MATERIAL AND METHODS: This was a prospective, multicentre study that included cases of long bone osteomyelitis in children who underwent an MRI examination within 7days of the start of symptoms and within 24hours of the initiation of antibiotic therapy. We also collected clinical, laboratory and treatment-related data. RESULTS: Twenty patients were included, including one with a bifocal condition. The lower limb was involved in most cases (19/21). Staphylococcus aureus was found most frequently. Metaphyseal involvement was present in all cases. No isolated periosteal involvement was found in any of the cases. No prognostic factors were identified based on the various abnormal findings on MRI. CONCLUSION: Our study supports the metaphyseal origin of acute osteomyelitis in children. LEVEL OF EVIDENCE: II.

Cell cycle timing regulation during asynchronous divisions of the early C. elegans embryo.

A fundamental question in developmental biology is how different cell lineages acquire different cell cycle durations. With its highly stereotypical asymmetric and asynchronous cell divisions, the early Caenorhabditis elegans embryo provides an ideal system to study lineage-specific cell cycle timing regulation during development, with high spatio-temporal resolution. The first embryonic division is asymmetric and generates two blastomeres of different sizes (AB>P1) and developmental potentials that divide asynchronously, with the anterior somatic blastomere AB dividing reproducibly two minutes before the posterior germline blastomere P1. The evolutionarily conserved PAR proteins (abnormal embryonic PARtitioning of cytoplasm) regulate all of the asymmetries in the early embryo including cell cycle asynchrony between AB and P1 blastomeres. Here we discuss our current understanding and open questions on the mechanism by which the PAR proteins regulate asynchronous cell divisions in the early C. elegans embryo.

Genome Sequence of the Mycorrhizal Helper Bacterium Pseudomonas fluorescens BBc6R8.

We report the draft genome sequence of the mycorrhizal helper bacterium Pseudomonas fluorescens strain BBc6R8. This is the first genome of a mycorrhizal helper bacterium. The draft genome contains 6,952,353 bp and is predicted to encode 6,317 open reading frames. Comparative genomic analyses will help to identify helper traits.

Minimally invasive treatment of displaced intra-articular calcaneal fractures using the balloon kyphoplasty technique: preliminary study.

BACKGROUND: The balloon kyphoplasty approach to the treatment of vertebral fractures can be adapted to achieve the reduction and cement stabilisation of intra-articular compression fractures at other sites, such as the calcaneus. PATIENTS AND METHOD: We studied six patients with a median follow-up of 12 months (range, 6-30 months). Fluoroscopy guidance was used to obtain optimal balloon positioning under the joint depression site. Reduction was achieved by expanding the balloon and stabilisation by injecting the cavity with resorbable tricalcium-phosphate cement in the younger patients and polymethyl-metacrylate cement in the two elderly patients with osteoporosis. No internal fixation was used. RESULTS: No intra-operative, postoperative, or delayed complications were recorded. Median hospital stay length was 4.5 days (range, 3-7 days). All the fractures healed within the usual timeframe, without loss of reduction. Median time to full weight-bearing ambulation was 52.5 days (range, 15-75 days). The functional outcomes correlated with the good anatomic results, with a median American Orthopaedic Foot and Ankle Society score of 87.0 (range, 86-97). DISCUSSION: This preliminary study shows that balloon reduction and cement fixation of intra-articular calcaneal fractures is easy to perform, reproducible, and devoid of specific complications. Good-quality reduction and stabilisation until fracture healing were achieved, and time to recovery of self-sufficiency was short, even in elderly patients with osteoporosis. These results support the use of this minimally invasive technique. LEVEL OF EVIDENCE: Level IV, retrospective study.

Progressive limitation of knee flexion secondary to an accessory quinticeps femoris muscle in a child: a case report and literature review.

We describe a symptomatic, progressive restriction of knee flexion due to an accessory quadriceps femoris in a nine-year-old girl. There was no history or findings of post-injection fibrosis, nor any obvious swelling of the affected quadriceps. At arthroscopy no intra-articular pathology was found. An accessory 'quinticeps femoris' was diagnosed by ultrasonography and MRI. Following excision of the muscle and tendon full flexion of the knee was regained and there was no recurrence of the contracture.

Distribution and localization of microsatellites in the Perigord black truffle genome and identification of new molecular markers.

The level of genetic diversity and genetic structure in the Perigord black truffle (Tuber melanosporum Vittad.) has been debated for several years, mainly due to the lack of appropriate genetic markers. Microsatellites or simple sequence repeats (SSRs) are important for the genome organisation, phenotypic diversity and are one of the most popular molecular markers. In this study, we surveyed the T. melanosporum genome (1) to characterise its SSR pattern; (2) to compare it with SSR patterns found in 48 other fungal and three oomycetes genomes and (3) to identify new polymorphic SSR markers for population genetics. The T. melanosporum genome is rich in SSRs with 22,425 SSRs with mono-nucleotides being the most frequent motifs. SSRs were found in all genomic regions although they are more frequent in non-coding regions (introns and intergenic regions). Sixty out of 135 PCR-amplified mono-, di-, tri-, tetra, penta, and hexa-nucleotides were polymorphic (44%) within black truffle populations and 27 were randomly selected and analysed on 139 T. melanosporum isolates from France, Italy and Spain. The number of alleles varied from 2 to 18 and the expected heterozygosity from 0.124 to 0.815. One hundred and thirty-two different multilocus genotypes out of the 139 T. melanosporum isolates were identified and the genotypic diversity was high (0.999). Polymorphic SSRs were found in UTR regulatory regions of fruiting bodies and ectomycorrhiza regulated genes, suggesting that they may play a role in phenotypic variation. In conclusion, SSRs developed in this study were highly polymorphic and our results showed that T. melanosporum is a species with an important genetic diversity, which is in agreement with its recently uncovered heterothallic mating system.

Effect of poplar genotypes on mycorrhizal infection and secreted enzyme activities in mycorrhizal and non-mycorrhizal roots.

The impact of ectomycorrhiza formation on the secretion of exoenzymes by the host plant and the symbiont is unknown. Thirty-eight F(1) individuals from an interspecific Populus deltoides (Bartr.)×Populus trichocarpa (Torr. & A. Gray) controlled cross were inoculated with the ectomycorrhizal fungus Laccaria bicolor. The colonization of poplar roots by L. bicolor dramatically modified their ability to secrete enzymes involved in organic matter breakdown or organic phosphorus mobilization, such as N-acetylglucosaminidase, ß-glucuronidase, cellobiohydrolase, ß-glucosidase, ß-xylosidase, laccase, and acid phosphatase. The expression of genes coding for laccase, N-acetylglucosaminidase, and acid phosphatase was studied in mycorrhizal and non-mycorrhizal root tips. Depending on the genes, their expression was regulated upon symbiosis development. Moreover, it appears that poplar laccases or phosphatases contribute poorly to ectomycorrhiza metabolic activity. Enzymes secreted by poplar roots were added to or substituted by enzymes secreted by L. bicolor. The enzymatic activities expressed in mycorrhizal roots differed significantly between the two parents, while it did not differ in non-mycorrhizal roots. Significant differences were found between poplar genotypes for all enzymatic activities measured on ectomycorrhizas except for laccases activity. In contrast, no significant differences were found between poplar genotypes for enzymatic activities of non-mycorrhizal root tips except for acid phosphatase activity. The level of enzymes secreted by the ectomycorrhizal root tips is under the genetic control of the host. Moreover, poplar heterosis was expressed through the enzymatic activities of the fungal partner.

Acute osteomyelitis in children: the pathogenesis revisited?

PURPOSE OF THE STUDY: The present study reviews our experience of acute hematogenous osteomyelitis in 450 children over a period of 20 years from 1985 to 2004 at the Nouméa Territorial Hospital in New Caledonia. The objective was to formulate a new theory of the pathogenesis of this affection and to report our research on the disparity in the pathology between temperate countries and our own tropical Pacific area. PATIENT AND METHODS: Only children with an initially normal X-ray and showing symptoms for less than one week were included in the study. Subacute osteomyelitis, infant osteoarthritis and spinal and sacroiliac joint infections were all excluded. All children were treated according to a preestablished protocol including: clinical examination; blood tests; ultrasound, to determine the presence and size of the periosteal elevation and to exclude soft tissue abscess and frequent pyomyositis. Ultrasound was used in the decision to treat with antibiotics alone or with surgery. Computed Tomography was used for deep structures assessment and medical therapy guidance Surgery was limited to open drainage of the subperiosteal abscess only. Regular follow-up of outpatients was continued until normal blood test and X-ray results were achieved. RESULTS AND DISCUSSION: Four hundred and fifty children with a diagnosis of acute hematogenous osteomyelitis were identified, giving an average incidence of 22 new cases per year (range, 12-35). This incidence was two to five times as high as found in Europe. Fifty-three percent of our cases required surgical drainage (vs. 20 % in Europe). Ethnically, 60 % of the children were Melanesian and 20 % Polynesian (both represented less than 50 % of the local population). A similar incidence, about four times as high as in the population of European descent, was reported in Polynesians by our neighbors in New Zealand. The limbs were affected in 90 % of cases, and specifically lower limbs in 70 %. Multiple osseous lesions and systemic infection were recorded in 43 children (9.5 %). Blood cultures and surgical samples were positive in 80 % of cases, and otherwise negative. All the children were successfully treated, without chronic evolution or sequelae needing secondary surgery. The predominant microorganisms isolated were Staphylococcus aureus, in 81 % of cases, none of which were methicillin-resistant, and group A Streptococcus in 7.5 % of cases. A previous study of soft-tissue S. aureus infection showed the presence of Panton-Valentine Leukocidin (PVL) genes in 89 % of cases. These very infrequent genes are responsible for leukotoxic apoptosis, producing leukocidin, causing local acute aggressiveness. A parallel study, in progress for more than a year, is focusing on detecting PVL genes in S. aureus isolated from acute osteomyelitis: in the first nine children analyzed, PVL genes were likewise detected in 89 % of the S. aureus isolated, with no methicillin resistance. Ultrasonography allowed positive diagnosis in 64 % of cases on the day of admission and 84 % by the second day. Because of this very early presence of subperiosteal abscess at the beginning of the disease, and several other issues raised in the present study, we believe that Trueta's theory of acute osteomyelitis pathogenesis does not provide any logical explanation for our anatomoclinical observations. We believe that the primary focus of infection is in the osteoperiosteal area rather than under the growth plate in the metaphyseal bone. The term of Acute Osteo-Periostitis would therefore be much more suitable. A history of blunt trauma was found in 63 % of cases in the present series, and often reported in the literature. We speculate that two forms of infection fixation may develop: a local form, where bacteria carried by the blood stream reach a subperiosteal edema or hematoma secondary to blunt trauma, which is in our opinion the most frequent cause; and a general form, where fixation occurs as single or multifocal osteoperiostitis, and multivisceral locations in severe forms of septicemia. The disparity in this pathology between temperate countries and our own tropical Pacific area is certainly due to PVL-positive S. aureus and ethnic factors. The high prevalence of Melanesian and Polynesian patients confirms that they are at high risk of musculoskeletal infection in New Caledonia as in other Pacific countries, and it is possible that these ethnic groups are genetically susceptible to PVL-positive strains. LEVEL OF EVIDENCE: Level IV. Retrospective case series.

RSK2 is a kinetochore-associated protein that participates in the spindle assembly checkpoint.

The spindle assembly checkpoint (SAC) prevents anaphase onset until all the chromosomes have successfully attached to the spindle microtubules. The MAP kinase (MAPK) is an important player in this pathway, however its exact role is not fully understood. One major target of MAPK is the p90 ribosomal protein S6 kinase (RSKs) family. In this study, we analyse whether Rsk2 could participate in the activation of the SAC. Our data indicate that this protein is localized at the kinetochores under checkpoint conditions. Moreover, it is essential for the SAC activity in Xenopus egg extracts as its depletion prevents metaphase arrest as well as the kinetochore localization of the other SAC components. We also show that this kinase might also participate in the maintenance of the SAC in mammalian cells as Rsk2 knockdown in these cells prevents the kinetochore localization of Mad1, Mad2 and CENP-E under checkpoint conditions.

Fractures of the upper transthoracic cage.

We have reviewed our experience in managing 11 patients who sustained an indirect sternal fracture in combination with an upper thoracic spinal injury between 2003 and 2006. These fractures have previously been described as 'associated' fractures, but since the upper thorax is an anatomical entity composed of the upper thoracic spine, ribs and sternum joined together, we feel that the term 'fractures of the upper transthoracic cage' is a better description. These injuries are a challenge because they are unusual and easily overlooked. They require a systematic clinical and radiological examination to identify both lesions. This high-energy trauma gives severe devastating concomitant injuries and CT with contrast and reconstruction is essential after resuscitation to confirm the presence of all the lesions. The injury level occurs principally at T4-T5 and at the manubriosternal joint. These unstable fractures need early posterior stabilisation and fusion or, if treated conservatively, a very close follow-up.

A genetic linkage map for the ectomycorrhizal fungus Laccaria bicolor and its alignment to the whole-genome sequence assemblies.

A genetic linkage map for the ectomycorrhizal basidiomycete Laccaria bicolor was constructed from 45 sib-homokaryotic haploid mycelial lines derived from the parental S238N strain progeny. For map construction, 294 simple sequence repeats (SSRs), single-nucleotide polymorphisms (SNPs), amplified fragment length polymorphisms (AFLPs) and random amplified polymorphic DNA (RAPD) markers were employed to identify and assay loci that segregated in backcross configuration. Using SNP, RAPD and SSR sequences, the L. bicolor whole-genome sequence (WGS) assemblies were aligned onto the linkage groups. A total of 37.36 Mbp of the assembled sequences was aligned to 13 linkage groups. Most mapped genetic markers used in alignment were colinear with the sequence assemblies, indicating that both the genetic map and sequence assemblies achieved high fidelity. The resulting matrix of recombination rates between all pairs of loci was used to construct an integrated linkage map using JoinMap. The final map consisted of 13 linkage groups spanning 812 centiMorgans (cM) at an average distance of 2.76 cM between markers (range 1.9-17 cM). The WGS and the present linkage map represent an initial step towards the identification and cloning of quantitative trait loci associated with development and functioning of the ectomycorrhizal symbiosis.

[Subjective experience and disability work: qualitative analysis among 17 paraplegic patients]. / Expérience subjective et travail de handicap: analyse qualitative auprès de 17 patients paraplégiques.

This paper presents a phenomenological study illustrative how paraplegia may have a serious debilitating impact on the sufferer's subjective experience. Exploratory interviews were conducted with seventeen patients and the transcripts subjected to qualitative analysis. The interpretative phenomenological analysis points to the powerful ways in which paraplegia has negative impact on patients' experience and well-being. Some of the participants describe two major approaches of their situation: dimensional (the links between disability and society, others and self) and temporal (the "disability work"). The results section gives a detailed account of these processes at work. The results are then considered in relation to relevant constructs in the literature, including grief work, illness work and identity, adaptation and acceptance.

Chfr interacts and colocalizes with TCTP to the mitotic spindle.

Chfr is a checkpoint protein that plays an important function in cell cycle progression and tumor suppression, although its exact role and regulation are unclear. Previous studies have utilized overexpression of Chfr to determine the signaling pathway of this protein in vivo. In this study, we demonstrate, by using three different antibodies against Chfr, that the endogenous and highly overexpressed ectopic Chfr protein is localized and regulated differently in cells. Endogenous and lowly expressed ectopic Chfr are cytoplasmic and localize to the spindle during mitosis. Higher expression of ectopic Chfr correlates with a shift in the localization of this protein to the nucleus/PML bodies, and with a block of cell proliferation. In addition, endogenous and lowly expressed ectopic Chfr is stable throughout the cell cycle, whereas when highly expressed, ectopic Chfr is actively degraded during S-G2/M phases in an autoubiquitination and proteasome-dependent manner. A two-hybrid screen identified TCTP as a possible Chfr-interacting partner. Biochemical analysis with the endogenous proteins confirmed this interaction and identified beta-tubulin as an additional partner for Chfr, supporting the mitotic spindle localization of Chfr. The Chfr-TCTP interaction was stable throughout the cell cycle, but it could be diminished by the complete depolymerization of the microtubules, providing a possible mechanism where Chfr could be the sensor that detects microtubule disruption and then activates the prophase checkpoint.

The genome of Laccaria bicolor provides insights into mycorrhizal symbiosis.

Mycorrhizal symbioses--the union of roots and soil fungi--are universal in terrestrial ecosystems and may have been fundamental to land colonization by plants. Boreal, temperate and montane forests all depend on ectomycorrhizae. Identification of the primary factors that regulate symbiotic development and metabolic activity will therefore open the door to understanding the role of ectomycorrhizae in plant development and physiology, allowing the full ecological significance of this symbiosis to be explored. Here we report the genome sequence of the ectomycorrhizal basidiomycete Laccaria bicolor (Fig. 1) and highlight gene sets involved in rhizosphere colonization and symbiosis. This 65-megabase genome assembly contains approximately 20,000 predicted protein-encoding genes and a very large number of transposons and repeated sequences. We detected unexpected genomic features, most notably a battery of effector-type small secreted proteins (SSPs) with unknown function, several of which are only expressed in symbiotic tissues. The most highly expressed SSP accumulates in the proliferating hyphae colonizing the host root. The ectomycorrhizae-specific SSPs probably have a decisive role in the establishment of the symbiosis. The unexpected observation that the genome of L. bicolor lacks carbohydrate-active enzymes involved in degradation of plant cell walls, but maintains the ability to degrade non-plant cell wall polysaccharides, reveals the dual saprotrophic and biotrophic lifestyle of the mycorrhizal fungus that enables it to grow within both soil and living plant roots. The predicted gene inventory of the L. bicolor genome, therefore, points to previously unknown mechanisms of symbiosis operating in biotrophic mycorrhizal fungi. The availability of this genome provides an unparalleled opportunity to develop a deeper understanding of the processes by which symbionts interact with plants within their ecosystem to perform vital functions in the carbon and nitrogen cycles that are fundamental to sustainable plant productivity.

New developmental insights from high-throughput biological analysis in Caenorhabditis elegans.

The use of Caenorhabditis elegans as a model system for understanding animal development and human disease has long been recognized as an efficient tool of discovery. Recent developments, particularly in our understanding of RNA-mediated interference and its ability to modify gene activity, have facilitated the use of C. elegans in determining gene function via high-throughput analysis. These new strategies have provided a framework that allows investigators to analyse gene function globally at the genomic level and will likely become a prototypic model for biological analysis in the post-genome era.

[Surgical management of stingray injuries. About two clinical cases]. / Prise en charge chirurgicale des plaies par raie. A propos de deux cas.

Fifty injuries by stingrays are annually examined in the New Caledonia hospital. The injuries occur most often in the lower extremity, rare puncture injuries to the thorax or abdomen can cause death. The wound is associated with envenomation. The pain is intense with oedema, cyanosis, erythema often followed by tissue necrosis. In many cases, the management of stingray wounds is inadequate and the gravity often not well appreciated. Localized morbidity and prolonged healing may occur without an effective surgical management. Wound exploration and debridement are particularly indicated after first-aid measures, such as immersion in hot water. The characteristics, treatment and prevention are discussed in connection with two cases.