Whole transcriptome sequencing and biomineralization gene architecture associated with cultured pearl quality traits in the pearl oyster, Pinctada margaritifera.

BACKGROUND: Cultured pearls are unique gems produced by living organisms, mainly molluscs of the Pinctada genus, through the biomineralization properties of pearl sac tissue. Improvement of P. margaritifera pearl quality is one of the biggest challenges that Polynesian research has faced to date. To achieve this goal, a better understanding of the complex mechanisms related to nacre and pearl formation is essential and can now be approached through the use of massive parallel sequencing technologies. The aim of this study was to use RNA-seq to compare whole transcriptome expression of pearl sacs that had producing pearls with high and low quality. For this purpose, a comprehensive reference transcriptome of P. margaritifera was built based on multi-tissue sampling (mantle, gonad, whole animal), including different living stages (juvenile, adults) and phenotypes (colour morphotypes, sex). RESULTS: Strikingly, few genes were found to be up-regulated for high quality pearls (n = 16) compared to the up-regulated genes in low quality pearls (n = 246). Biomineralization genes up-regulated in low quality pearls were specific to prismatic and prism-nacre layers. Alternative splicing was further identified in several key biomineralization genes based on a recent P. margaritifera draft genome. CONCLUSION: This study lifts the veil on the multi-level regulation of biomineralization genes associated with pearl quality determination.

Dual RNAseq highlights the kinetics of skin microbiome and fish host responsiveness to bacterial infection.

BACKGROUND: Tenacibaculum maritimum is a fish pathogen known for causing serious damage to a broad range of wild and farmed marine fish populations worldwide. The recently sequenced genome of T. maritimum strain NCIMB 2154T provided unprecedented information on the possible molecular mechanisms involved in the virulence of this species. However, little is known about the dynamic of infection in vivo, and information is lacking on both the intrinsic host response (gene expression) and its associated microbiota. Here, we applied complementary omic approaches, including dual RNAseq and 16S rRNA gene metabarcoding sequencing using Nanopore and short-read Illumina technologies to unravel the host-pathogen interplay in an experimental infection system using the tropical fish Platax orbicularis as model. RESULTS: We showed that the infection of the host is characterised by an enhancement of functions associated with antibiotic and glucans catabolism functions but a reduction of sulfate assimilation process in T. maritimum. The fish host concurrently displays a large panel of immune effectors, notably involving innate response and triggering acute inflammatory response. In addition, our results suggest that fish activate an adaptive immune response visible through the stimulation of T-helper cells, Th17, with congruent reduction of Th2 and T-regulatory cells. Fish were, however, largely sensitive to infection, and less than 25% survived after 96 hpi. These surviving fish showed no evidence of stress (cortisol levels) or significant difference in microbiome diversity compared with controls at the same sampling time. The presence of T. maritimum in resistant fish skin and the total absence of any skin lesions suggest that these fish did not escape contact with the pathogen, but rather that some mechanisms prevented pathogens entry. In resistant individuals, we detected up-regulation of specific immune-related genes differentiating resistant individuals from controls at 96 hpi, which suggests a possible genomic basis of resistance, although no genetic variation in coding regions was found. CONCLUSION: Here we focus in detail on the interplay between common fish pathogens and host immune response during experimental infection. We further highlight key actors of defence response, pathogenicity and possible genomic bases of fish resistance to T. maritimum.

[Postoperative pyoderma gangrenosum and cancer of the breast. Apropos of a case]. / Pyoderma gangrenosum post-opératoire et cancer du sein. A propos d'une observation.

Pyoderma gangrenosum (PG) consists of extensive necrotic ulceration with bluish and purplish red margins. This disease is often associated with ulcerative colitis, systemic, hematologic or rheumatic diseases. However post-surgical idiopathic PG can occur. One post-mastectomy case is reported. PG can first be suspected on clinical appearance and the lack of a specific etiology. PG is a diagnosis of exclusion that is made only after other possibilities have been ruled out. The treatment is surgical excision and systemic corticosteroids.

[Focus on skin pre-suturing. Apropos of 12 cases]. / Le point sur la pré-suture cutanée. A propos de douze cas.

Presuture is a rapid skin expansion technique performed in a 2-stage operation. On the day before the operation, a square of skin sutures is inserted along the lesion to be invaginated, under local anaesthesia. Resection with direct suture can be performed on the following day. Twelve patients presenting with extensive (3 x 3 cm to 7 x 24 cm) lesions of the lower limbs (3 congenital naevi, 7 melanomas, 2 areas of scar tissue) were treated. The scar results were excellent in 2 cases, inter-mediate in 8 cases and poor in 2 cases. The limits of this technique are the risk of malunion due to ischaemia and especially secondary enlargement of the scar.

[Postoperative pyoderma gangrenosum and cancer of the breast. Apropos of a case]. / Pyoderma gangrenosum post-operatoire et cancer du sein. A propos d'une observation.

Pyoderma gangrenosum (PG) is a extending necrotic ulceration with bluish and purplish red margins. This disease is often associated with ulcerative colitis, systemic, hematologic or rheumatic affections. However post-surgical idiopathic PG can occur. One post-mammectomy case is reported. PG can first be suspected on clinical aspect, lack of a specific etiology. PG is a diagnosis of exclusion that is made only after others possibilities are ruled out. The treatment is surgical excision and general corticotherapy.