A new encrusting interstitial marine fauna from Brazil

Abstract. This paper reports the second occurrence of a sand‐grain encrusting interstitial epifauna dominated by bryozoans and polychaetes at a site thousands of kilometers from the first described occurrence of such a fauna 20 years ago. Such faunas seem to have gone almost unrecorded in the marine ecological literature, but they are potentially geographically widespread and ecologically significant, deserving recognition and further study by benthic ecologists. Although rooted‐erect and free‐living lunulitiform bryozoans can be abundant in soft‐bottom habitats, the presence of encrusting forms was, until recently, considered to be limited to patches of hard substrata. In 1985 and 1988, a new and seemingly unique habitat for encrusting bryozoans and other organisms on single grains of shell or sand was reported from the coastal waters of Florida, USA. Here we report a second discovery of an interstitial encrusting fauna from the continental shelf off the state of São Paulo, Brazil. In addition to the cupuladriid Discoporella umbellata, several species of bryozoans (9 cheilostomes, 3 ctenostomes, and 1 cyclostome) were found encrusting on or boring into sand grains from the 4 stations examined. Four species were found exclusively on sand to gravel size grains. The most abundant colonies, with ～1300–1500 colonies m^?2, belonged to a new species of Cleidochasma. New species of Trypostega and Reginella, each with up to 200–300 colonies m^?2, were also discovered. The grain‐encrusting bryozoans were characterized by their small size, and by the fact that sexual reproduction was initiated very early in colony growth; brood chambers (for the development of embryos into larvae) occurred in colonies having only a few zooids. Colonies of boring ctenostome and cheilostome bryozoans were even more abundant than those of grain encrusting forms, being present in almost every piece of shell (～5000–5500 colonies m^?2). The fauna also included representatives of other groups of encrusting organisms, especially tubeworms (11,000–13,000 tubes m^?2). Planned work on samples from additional stations on the São Paulo shelf will no doubt yield a larger number of species from various taxa and perhaps show some overlap in sand fauna species between the Brazilian and Floridian sites. In addition to the unique species of single grain encrusters, colonies of bryozoan species characteristic of larger subtidal hard substrata were also found on sand or gravel size grains, indicating that an interstitial refuge may be available to some epifaunal taxa and suggesting that this interstitial refuge, which remains almost completely unknown to benthic ecologists, may play a large role in determining distributions of those taxa.     

In vitro interaction network of a synthetic gut bacterial community

A key challenge in microbiome research is to predict the functionality of microbial communities based on community membership and (meta)-genomic data. As central microbiota functions are determined by bacterial community networks, it is important to gain insight into the principles that govern bacteria-bacteria interactions. Here, we focused on the growth and metabolic interactions of the Oligo-Mouse-Microbiota (OMM¹²) synthetic bacterial community, which is increasingly used as a model system in gut microbiome research. Using a bottom-up approach, we uncovered the directionality of strain-strain interactions in mono- and pairwise co-culture experiments as well as in community batch culture. Metabolic network reconstruction in combination with metabolomics analysis of bacterial culture supernatants provided insights into the metabolic potential and activity of the individual community members. Thereby, we could show that the OMM¹² interaction network is shaped by both exploitative and interference competition in vitro in nutrient-rich culture media and demonstrate how community structure can be shifted by changing the nutritional environment. In particular, Enterococcus faecalis KB1 was identified as an important driver of community composition by affecting the abundance of several other consortium members in vitro. As a result, this study gives fundamental insight into key drivers and mechanistic basis of the OMM¹² interaction network in vitro, which serves as a knowledge base for future mechanistic in vivo studies.Subject terms: Microbiome, Microbial ecology     

Association of Sick Sinus Syndrome with Incident Cardiovascular Disease and Mortality: The Atherosclerosis Risk in Communities Study and Cardiovascular Health Study

Background

Sick sinus syndrome (SSS) is a common indication for pacemaker implantation. Limited information exists on the association of sick sinus syndrome (SSS) with mortality and cardiovascular disease (CVD) in the general population.

Methods

We studied 19,893 men and women age 45 and older in the Atherosclerosis Risk in Communities (ARIC) study and the Cardiovascular Health Study (CHS), two community-based cohorts, who were without a pacemaker or atrial fibrillation (AF) at baseline. Incident SSS cases were validated by review of medical charts. Incident CVD and mortality were ascertained using standardized protocols. Multivariable Cox models were used to estimate the association of incident SSS with selected outcomes.

Results

During a mean follow-up of 17 years, 213 incident SSS events were identified and validated (incidence, 0.6 events per 1,000 person-years). After adjustment for confounders, SSS incidence was associated with increased mortality (hazard ratio [HR] 1.39, 95% confidence interval [CI] 1.14–1.70), coronary heart disease (HR 1.72, 95%CI 1.11–2.66), heart failure (HR 2.87, 95%CI 2.17–3.80), stroke (HR 1.56, 95%CI 0.99–2.46), AF (HR 5.75, 95%CI 4.43–7.46), and pacemaker implantation (HR 53.7, 95%CI 42.9–67.2). After additional adjustment for other incident CVD during follow-up, SSS was no longer associated with increased mortality, coronary heart disease, or stroke, but remained associated with higher risk of heart failure (HR 2.00, 95%CI 1.51–2.66), AF (HR 4.25, 95%CI 3.28–5.51), and pacemaker implantation (HR 25.2, 95%CI 19.8–32.1).

Conclusion

Individuals who develop SSS are at increased risk of death and CVD. The mechanisms underlying these associations warrant further investigation.     

In vitro activity of 1,3-bisaryloxypropanamines against Trypanosoma cruzi-infected L929 cultures

We describe herein the antitrypanosomal activity of 20 novel 1,3-bis(aryloxy)propan-2-amine derivatives. Compounds 2, 4, 6, 12, 15, 16 and 19 were significantly active against amastigote and trypomastigote forms, with half maximal inhibitory concentrationvalues in the range of 6-18 µM. In the cytotoxicity tests against L929 cells, only compound 4 presented selectivity index value above 10, indicating low toxicity.     

Tunicamycin inhibits the initiation of DNA synthesis stimulated by prostaglandin F2α in Swiss mouse 3T3 cells

Tunicamycin, an inhibitor of the asparagine-linked protein N-glycosylation, blocks the initiation of DNA synthesis in Swiss 3T3 cells stimulated by prostaglandin F_2α alone or with insulin. This effect is exerted only when tunicamycin is added from 0 to 8 h after stimulation and it decreases the rate of entry into S phase. Blocking of labeled sugar incorporation to proteins occurs regardless of the time of PGF_2α stimulation. In contrast tunicamicin does not inhibit protein synthesis. These results suggest that N-glycoprotein synthesis early during the prereplicative phase is an important event controlling the mitogenic action of PGF_2α     

The Drosophila orthologue of xPlkk1 is not essential for Polo activation and is necessary for proper contractile ring formation

Polo-like kinases (Plks) are essential for progression through mitosis. The activity of these kinases peak during M phase and this activation has been attributed to phosphorylation. Kinases capable of activating Plks in vitro have been previously identified both in mammalian cells and in Xenopus laevis oocytes (SLK and xPlkk1, respectively), although an in vivo correlation has not been clearly established. In order to study the regulation of Polo activity, we identified and cloned a Drosophila melanogaster kinase belonging to the ste20 ser/thr family that presents a close sequence homology with xPlkk1 and SLK. We termed this kinase dPlkk and showed that dPlkk associates with and phosphorylates Polo in vitro, resulting in the activation of the latter. On the other hand, when dPlkk is depleted from S2 cells, Polo activation does not seem to be impaired, suggesting that other kinases are involved in regulating Polo activity in vivo. Additionally, we found that a percentage of dPlkk-depleted cells fail to form a proper actin ring at the end of mitosis, leading to a failure in the assembly of the cleavage furrow and to the formation of binucleated cells. The detected accumulation of dPlkk in the contractile ring late in anaphase reinforces the idea that this kinase plays a role in cytokinesis.