The gill-associated microbiome is the main source of wood plant polysaccharide hydrolases and secondary metabolite gene clusters in the mangrove shipworm Neoteredo reynei

Teredinidae are a family of highly adapted wood-feeding and wood-boring bivalves, commonly known as shipworms, whose evolution is linked to the acquisition of cellulolytic gammaproteobacterial symbionts harbored in bacteriocytes within the gills. In the present work we applied metagenomics to characterize microbiomes of the gills and digestive tract of Neoteredo reynei, a mangrove-adapted shipworm species found over a large range of the Brazilian coast. Comparative metagenomics grouped the gill symbiont community of different N. reynei specimens, indicating closely related bacterial types are shared. Similarly, the intestine and digestive gland communities were related, yet were more diverse than and showed no overlap with the gill community. Annotation of assembled metagenomic contigs revealed that the gill symbiotic community of N. reynei encodes a plethora of plant cell wall polysaccharides degrading glycoside hydrolase encoding genes, and Biosynthetic Gene Clusters (BGCs). In contrast, the digestive tract microbiomes seem to play little role in wood digestion and secondary metabolites biosynthesis. Metagenome binning recovered the nearly complete genome sequences of two symbiotic Teredinibacter strains from the gills, a representative of Teredinibacter turnerae “clade I” strain, and a yet to be cultivated Teredinibacter sp. type. These Teredinibacter genomes, as well as un-binned gill-derived gammaproteobacteria contigs, also include an endo-β-1,4-xylanase/acetylxylan esterase multi-catalytic carbohydrate-active enzyme, and a trans-acyltransferase polyketide synthase (trans-AT PKS) gene cluster with the gene cassette for generating β-branching on complex polyketides. Finally, we use multivariate analyses to show that the secondary metabolome from the genomes of Teredinibacter representatives, including genomes binned from N. reynei gills’ metagenomes presented herein, stands out within the Cellvibrionaceae family by size, and enrichments for polyketide, nonribosomal peptide and hybrid BGCs. Results presented here add to the growing characterization of shipworm symbiotic microbiomes and indicate that the N. reynei gill gammaproteobacterial community is a prolific source of biotechnologically relevant enzymes for wood-digestion and bioactive compounds production.

Hemodynamics of different degrees of right heart bypass: experimental assessment

BACKGROUND

Although their assessment could be of the utmost importance to determine the surgical treatment for patients with univentricular hearts, differences in ventricular performance between partial and complete right heart bypass remain to be defined.

METHODS

Three different degrees of right heart bypass were investigated in 5 mongrel dogs: (1) superior vena cava to both pulmonary arteries shunt (SCP); (2) inferior vena cava to both pulmonary arteries shunt (ICP); and (3) both venae cavae to both pulmonary arteries shunt (BCP). Hemodynamic studies included evaluation of the cardiac index and left atrial pressure as a function of the degree of right heart bypass.

RESULTS

By maintaining the mean left atrial pressure at 5 mm Hg, cardiac indexes were 1.98 +/- 0.25, 1.67 +/- 0.29, and 1.33 +/- 0.21 L.min-1.m-2 for SCP, ICP, and BCP shunts, respectively (p = 0.001). When keeping the cardiac index constant, mean left atrial pressures were 5.2 +/- 0.8, 5.5 +/- 0.9, and 7 +/- 0.7 mm Hg for SCP, ICP, and BCP shunts, respectively (p = 0.001).

CONCLUSIONS

Increasing degrees of right heart bypass are associated with a significant decrease in ventricular performance in this experimental model.

Conventional cardiopulmonary bypass in neonates. A physiological approach--10 years of experience at Marie-Lannelongue Hospital

There is still controversy about the optimal method of venoarterial cardiopulmonary bypass (CPB) for correction of congenital heart disease in neonates and young infants. High rates of CPB-related morbidity and mortality are still reported. Since 1980, conventional CPB with double caval cannulation with right-angled cannulae has been used in the high majority of neonates at Marie-Lannelongue Hospital. The extracorporeal circuit was miniaturized to be primed with a volume as small as possible. Priming (500 ml) was done with packed red cells and fresh frozen plasma. CPB was conducted at 30% haematocrit and normal ranges of flow rate, arterial pressure, systemic vascular resistances and oxygen delivery. These normal physiological parameters were also maintained during hypothermia. During the last two years, 151 neonates below 15 days old who underwent open-heart surgery were reviewed. The overall hospital mortality was 7.24%. None of the survivors had postoperative complications related to CPB. All physiological and biological values remained within normal ranges during the postoperative course.

[Peroperative evaluation of pulmonary vascular resistance by cavo-pulmonary bypass. Value of atrio- and cavo-pulmonary diversions]

Immediate and long-term results of the Fontan procedure depend on the value of the pulmonary vascular resistance. This parameter cannot always be quantified accurately during preoperative evaluation. Cavo-pulmonary bypass using an extra corporeal circulation allowed simulation a Fontan procedure in 5 patients, and prediction of the pressure changes in the pulmonary artery and the systemic atrium according to the pulmonary to systemic resistances ratio. This technique could be valuable in border line cases for deciding on the optimal therapeutic solution.

Detoxification of the T2 fraction from a scorpion (Tityus serrulatus, Lutz and Mello) venom by iodination and some immunogenic properties of the derivatives

The iodination of the T2 fraction abolished its lethal capacity, and doses up to 30 times the LD50 were injected i.p. in mice without noticeable toxic effects. The modified fraction retained its immunological properties. Antibodies generated against the iodinated T2 fraction were also reactive toward the native T2 fraction, T1 fraction and the whole soluble venom.