Hypometabolism to survive the long polar night and subsequent successful return to light in the diatom Fragilariopsis cylindrus.

Diatoms, the main eukaryotic phytoplankton of the polar marine regions, are essential for the maintenance of food chains specific to Arctic and Antarctic ecosystems, and are experiencing major disturbances under current climate change. As such, it is fundamental to understand the physiological mechanisms and associated molecular basis of their endurance during the long polar night. Here, using the polar diatom Fragilariopsis cylindrus, we report an integrative analysis combining transcriptomic, microscopic and biochemical approaches to shed light on the strategies used to survive the polar night.

Mixotrophic lifestyle of the ichthyotoxic haptophyte, Prymnesium parvum, offered different sources of phosphorus.

Many harmful algae are mixoplanktonic, i.e. they combine phototrophy and phagotrophy, and this ability may explain their ecological success, especially when environmental conditions are not optimal for autotrophic growth.

An unprecedented bloom of Lingulodinium polyedra on the French Atlantic coast during summer 2021.

At the end of July 2021, a bloom of Lingulodinium polyedra developed along the French Atlantic coast and lasted six weeks. The REPHY monitoring network and the citizen participation project PHENOMER contributed to its observation. A maximum concentration of 3,600,000 cells/L was reached on the 6th of September, a level never recorded on French coastlines.

Photoacclimation of the polar diatom Chaetoceros neogracilis at low temperature.

Polar microalgae face two major challenges: 1- growing at temperatures (-1.7 to 5°C) that limit enzyme kinetics; and 2- surviving and exploiting a wide range of irradiance. The objective of this study is to understand the adaptation of an Arctic diatom to its environment by studying its ability to acclimate to changes in light and temperature.

The possible fates of Fragilariopsis cylindrus (polar diatom) cells exposed to prolonged darkness.

At high latitudes, the polar night poses a great challenge to photosynthetic organisms that must survive up to six months without light. Numerous studies have already shed light on the physiological changes involved in the acclimation of microalgae to prolonged darkness and subsequent re-illumination. However, these studies have never considered inter-individual variability because they have mainly been conducted with bulk measurements.

Elaboration of soft porous ultrasound insulators.

A simple and easy way is proposed for the fabrication of a highly attenuating composite material for underwater acoustics. The approach involves the introduction of porous polymer beads into a polyurethane matrix. The porous beads are prepared through an emulsion-templating approach, and two different processes are used.

Diversity in Xanthophyll Cycle Pigments Content and Related Nonphotochemical Quenching (NPQ) Among Microalgae: Implications for Growth Strategy and Ecology.

Xanthophyll cycle-related nonphotochemical quenching (NPQ), which is present in most photoautotrophs, allows dissipation of excess light energy. Xanthophyll cycle-related NPQ depends principally on xanthophyll cycle pigments composition and their effective involvement in NPQ. Xanthophyll cycle-related NPQ is tightly controlled by environmental conditions in a species-/strain-specific manner.

A model for acoustic vaporization dynamics of a bubble/droplet system encapsulated within a hyperelastic shell.

Nanodroplets have great, promising medical applications such as contrast imaging, embolotherapy, or targeted drug delivery. Their functions can be mechanically activated by means of focused ultrasound inducing a phase change of the inner liquid known as the acoustic droplet vaporization (ADV) process. In this context, a four-phases (vapor + liquid + shell + surrounding environment) model of ADV is proposed.

DIEL VARIATIONS OF CARBOHYDRATES AND NEUTRAL LIPIDS IN NITROGEN-SUFFICIENT AND NITROGEN-STARVED CYCLOSTAT CULTURES OF ISOCHRYSIS SP.(1).

The goal of this study was to investigate the time response of two major carbon (C) reserves, respectively neutral lipids (NL) and total carbohydrate (TC), in the Haptophyte Isochrysis sp. growing in nitrogen (N)-sufficient or N-starved conditions and under light:dark (L:D) cycles. Experiments were carried out in a cyclostat culture system that allowed the following of the dynamics of the main cell compounds at both hourly and daily time scales.

NEUTRAL LIPID AND CARBOHYDRATE PRODUCTIVITIES AS A RESPONSE TO NITROGEN STATUS IN ISOCHRYSIS SP. (T-ISO; HAPTOPHYCEAE): STARVATION VERSUS LIMITATION(1).

Partitioning of the carbon (C) fixed during photosynthesis between neutral lipids (NL) and carbohydrates was investigated in Isochrysis sp. (Haptophyceae) in relation to its nitrogen (N) status. Using batch and nitrate-limited continuous cultures, we studied the response of these energy reserve pools to both conditions of N starvation and limitation.

Acid promoted cinnamyl ion mobility within peptide derived macrocycles.

We are developing methods that restrict the conformational mobility of peptides and related heteropolymers while simultaneously altering their properties. Our experiments occur as processes wherein a conserved, lipophilic reagent is activated in stages to form composite products with unprotected polyamides in parallel. For each starting oligomer, the goal is to create not one, but rather a collection of products.

Dexmedetomidine infusion during laparoscopic bariatric surgery: the effect on recovery outcome variables.

Background: Dexmedetomidine (Dex), an alpha(2) agonist, has well-known anesthetic and analgesic-sparing effects. We designed this prospective, randomized, double-blind, and placebo-controlled dose-ranging study to evaluate the effect of Dex on both early and late recovery after laparoscopic bariatric surgery.

Methods: Eighty consenting ASA II-III morbidly obese patients were randomly assigned to 1 of 4 treatment groups: (1) control group received a saline infusion during surgery, (2) Dex 0.

Dyotropic rearrangement facilitated proximal functionalization and oxidative removal of angular methyl groups: efficient syntheses of 23'-deoxy cephalostatin 1 analogues.

Oxidative functionalization (or removal) of a steroidal C18 methyl group is possible using a previously unknown dyotropic rearrangement of a seven-membered fused C-ring lactone to a 6-ring spiro lactone. Spiroketal equilibration led to the 23-deoxy South analogue of cephalostatin 1 (1) in only 12 steps (23% overall yield) from hecogenin acetate 4, and to strained diene South 1 analogue 30 in 11 steps (28% overall). Total synthesis of 23'-deoxy cephalostatin 1 (3) was accomplished in 16 operations from 4 (9% overall; average 86% yield per operation), and that of 16',17'-dehydro-23'-deoxy cephalostatin 1 (36) in 15 operations from 4 (8% overall; av 84%/op).