Extensive diversity and rapid turnover of phage defense repertoires in cheese-associated bacterial communities.

BACKGROUND Phages are key drivers of genomic diversity in bacterial populations as they impose strong selective pressure on the evolution of bacterial defense mechanisms across closely related strains. The pan-immunity model suggests that such diversity is maintained because the effective immune system of a bacterial species is the one distributed across all strains present in the community. However, only few studies have analyzed the distribution of bacterial defense systems at the community-level, mostly focusing on CRISPR and comparing samples from complex environments. Here, we studied 2778 bacterial genomes and 188 metagenomes from cheese-associated communities, which are dominated by a few bacterial taxa and occur in relatively stable environments. RESULTS We corroborate previous laboratory findings that in cheese-associated communities nearly identical strains contain diverse and highly variable arsenals of innate and adaptive (i.e., CRISPR-Cas) immunity systems suggesting rapid turnover. CRISPR spacer abundance correlated with the abundance of matching target sequences across the metagenomes providing evidence that the identified defense repertoires are functional and under selection. While these characteristics align with the pan-immunity model, the detected CRISPR spacers only covered a subset of the phages previously identified in cheese, providing evidence that CRISPR does not enable complete immunity against all phages, and that the innate immune mechanisms may have complementary roles. CONCLUSIONS Our findings show that the evolution of bacterial defense mechanisms is a highly dynamic process and highlight that experimentally tractable, low complexity communities such as those found in cheese, can help to understand ecological and molecular processes underlying phage-defense system relationships. These findings can have implications for the design of robust synthetic communities used in biotechnology and the food industry. Video Abstract

ReACC : impact du délai de reprise d’une anticoagulation curative sur la survenue d’hémorragies, après chirurgie d’une fracture de hanche chez des patients âgés porteurs d’une ACFA non valvulaire

Introduction : L’arythmie cardiaque par fibrillation atriale (ACFA) concerne 20 à 40% des patients hospitalisés pour une fracture de l’extrémité supérieure du fémur (FESF). La gestion péri-opératoire des anticoagulants curatifs (ACC) prend en compte la balance bénéfice-risque thrombo-embolique et hémorragique. A ce jour, il n’existe pas de recommandations concernant la gestion postopératoire de l’ACC après chirurgie semi-urgente. Notre objectif principal était d’évaluer l’impact du délai de reprise d’une ACC en postopératoire d’une FESF, sur l’incidence des complications hémorragiques graves. Matériel et méthode : Il s’agissait de l’étude rétrospective, descriptive et monocentrique, d’une cohorte de patients de 75 ans et plus, porteurs d’une ACFA et hospitalisés pour une FESF dans l’unité d’Orthogériatrie du CHUGA entre le 01/01/2020 et le 31/12/2021. Le critère de jugement principal était la survenue d’une hémorragie grave après reprise de l’ACC évaluée selon 7 critères de recherche clinique. Le délai de reprise postopératoire était considéré comme précoce (J0-J3) ou tardif (J4-sortie d’hospitalisation). Les objectifs secondaires évaluaient l’impact du délai de reprise sur la survenue d’hémorragies non graves, d’événements ischémiques ou thromboemboliques veineux et d’évaluer les facteurs associés aux hémorragies graves. Résultats : Les 67 patients inclus avaient un âge médian de 88 ans [85-93]. L’ACC était reprise pour 82% des patients (55/67) et avec une médiane de 135h [96-171] après la chirurgie. Le délai de reprise était précoce pour 22% des patients (12/55) et tardif pour 78% (43/55). Après reprise de l’ACC, 36% des patients présentaient une complication hémorragique grave (20/55). La fréquence de ces hémorragies graves ne différait pas entre les groupes. Une hémorragie grave survenait aussi avant la reprise d’une ACC pour 13% des patients (7/55) et dans 8% des cas (1/12) sans reprise. Les survenues respectives des hémorragies non graves (p>0,99), des événements ischémiques (p>0,99) ou thromboemboliques veineux (p>0,99) ne différaient pas entre les groupes. Seule la prise préhospitalière d’Apixaban était associée à une plus faible survenue d’hémorragie grave (p= 0,043). Conclusion : Nous montrions que le taux d’hémorragie grave après reprise d’ACC, dans une population âgée, porteuse d’une ACFA et, hospitalisée en Orthogériatrie pour une FESF, n’était pas associé au délai de reprise de l’ACC en postopératoire. L’étude met en évidence le haut risque hémorragique de l’événement de santé étudié. Nos résultats permettent de maintenir le choix de prescription déjà préférentiel vers l’Apixaban, ici, seul facteur associé à un plus faible taux d’hémorragie grave

Embryonic development of NMRI mice: relationship between the weight, age and ossification of embryos.

The time and the order of the appearance of the ossification centres were found to be similar in C3H and NMRI mice. Bodyweight comparisons confirmed these results. Location in the right as opposed to the left uterine horn, or in the upper, middle or lower part, was not found to influence the weight of the embryo. Significant differences in the weight of embryos within the same litter were used in investigating the sequence of ossification in embryos. This should prove useful in comparative morphology and teratology

Early development of the primitive cranial vault in the chick embryo

The calcified tissues involved in the early morphogenesis of the cranial vault were studied by microradiographic analysis and histological techniques in 12 chick embryos on the 9th, 12th, and 14th days of incubation. On the 9th day, the frontal, parietal, and squamosal bones are comprised of a thin lamina of chondroid tissue deposited at a short distance from the fibers of the dura mater. Woven bone formation takes place in the calvarial mesenchyme only after the 12th day of incubation and occurs mainly on the external side of the chondroid primordium. The present data obviously indicate that the primitive desmocranium of the chick embryo, which is usually known to be formed by intramembranous ossification, consists first of chondroid tissue. This tissue represents thus the initial modality of skeletogenic differentiation within the cephalic mesenchyme of the cranial vault

Chondroid tissue in the early facial morphogenesis of the chick embryo

The calcified tissues involved in the early morphogenesis of the so-called intramembranous bones of the facial skeleton were studied by microradiographic and histological techniques in 22 chick embryos at the 9th, 12th and 14th days of incubation. On the 9th day, the bones of the upper face and palatal vault are made up of thin sheets of chondroid tissue, deposited in their respective mesenchymal condensations. Woven and lamellar bone formation subsequently takes place in each of them from the 12th day of incubation, mainly on the external side of their chondroid primordia. The same phenomena occur in the lower facial and mandibular bones. These facts indicate that the primitive facial desmocranium of the chick embryo, which is classically considered to be formed by intramembranous ossification, first consists of chondroid tissue. As in the cranial vault, this tissue thus represents the initial modality of the skeletogenic differentiation within the avian facial mesenchyme