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Author(s): Shachar Hochman 1,*, Avishai Henik 1,2, Eyal Kalanthroff 3 Introduction Environmental cues trigger a set of behaviors that are essential for adaptive behavior. For example, when driving a car, [...]

Fecal microbiota transplantation (FMT) from healthy donor to patient is a treatment for microbiome-associated diseases. Although the success of FMT requires donor bacteria to engraft in the patient's gut, the forces governing engraftment in humans are unknown. Here we use an ongoing clinical experiment, the treatment of recurrent Clostridium difficile infection, to uncover the rules of engraftment in humans. We built a statistical model that predicts which bacterial species will engraft in a given host, and developed Strain Finder, a method to infer strain genotypes and track them over time. We find that engraftment can be predicted largely from the abundance and phylogeny of bacteria in the donor and the pre-FMT patient. Furthermore, donor strains within a species engraft in an all-or-nothing manner and previously undetected strains frequently colonize patients receiving FMT. We validated these findings for metabolic syndrome, suggesting that the same principles of engraftment extend to other indications.

The oocyte achieves its developmental competence through the lengthy process of folliculogenesis. It can therefore potentially be exposed to various stressors while enclosed in the follicle. Oocyte maturation relies mainly on maternal sources. These include nuclear, cytoplasmic, and molecular maturation, which involve DNA and RNA organization. Maternal transcripts are dominant through the first embryonic cleavages, up until embryonic genome activation. Thus, it is suggested that any perturbations during oocyte storage, in particular of the maternal transcripts, might lead to genetic and/or epigenetic changes, which might be further expressed in the developing embryo. The review discusses the effects of three representative stressors?environmental heat stress, endocrine-disrupting compounds (phthalates), and inflammatory stress (mastitis)?shown to be involved in reduced fertility. The review highlights the carryover response from the oocyte to the developing embryo; it includes intracellular and molecular disruptive mechanisms with an emphasis on maternal transcripts. The review provides insights into the oocyte?s cellular and molecular responses with an emphasis on the effects of various stressors on the maternal (nuclear and mitochondrial) transcripts and the association with embryonic development. A comparison between stressors might clarify, at least in part, a few open questions. For instance, (a) whether stress-induced alterations share the same mechanism and if so (b) whether this mechanism involves alterations of maternal transcripts; (c) whether stress-induced alterations in the maternal transcript are further expressed at the developing blastocyst stage, that is, after embryonic genome activation.

It is generally believed that during economic decisions, striatal neurons represent the values associated with different actions. This hypothesis is based on studies, in which the activity of striatal neurons was measured while the subject was learning to prefer the more rewarding action. Here we show that these publications are subject to at least one of two critical confounds. First, we show that even weak temporal correlations in the neuronal data may result in an erroneous identification of action-value representations. Second, we show that experiments and analyses designed to dissociate action-value representation from the representation of other decision variables cannot do so. We suggest solutions to identifying action-value representation that are not subject to these confounds. Applying one solution to previously identified action-value neurons in the basal ganglia we fail to detect action-value representations. We conclude that the claim that striatal neurons encode action-values must await new experiments and analyses.

It is generally believed that during economic decisions, striatal neurons represent the values associated with different actions. This hypothesis is based on studies, in which the activity of striatal neurons was measured while the subject was learning to prefer the more rewarding action. Here we show that these publications are subject to at least one of two critical confounds. First, we show that even weak temporal correlations in the neuronal data may result in an erroneous identification of action-value representations. Second, we show that experiments and analyses designed to dissociate action-value representation from the representation of other decision variables cannot do so. We suggest solutions to identifying action-value representation that are not subject to these confounds. Applying one solution to previously identified action-value neurons in the basal ganglia we fail to detect action-value representations. We conclude that the claim that striatal neurons encode action-values must await new experiments and analyses.

Plants do not have mineralized skeletons. Instead, each of the plant's cells has an envelope of a cellulose-based wall, which provides a mechanical support to the organism. This stiff wall enables plants to assume flexible body shapes. However, the wall interferes with proteinous muscle-like movements of cells and organs because it is too stiff to yield to forces generated by motor proteins. Nevertheless, plants move constantly. The movements rely on water translocations, which result in the swelling (or growth) of cells located strategically. Water may swell protoplasts in movements that require live cells, like tip growth, tropism, and gas exchange. Other movements are initiated by the swelling of cell walls. These occur in dead tissues that can afford drying. The hygroscopically based movement is very common in seed dispersal mechanisms. The seed that detaches from the mother plant is carried by a cellulosic device. This device was synthesized by the plant and programmed to do some mechanical work, like jumping, crawling, and sowing, in order to deliver the seed to a germination location. This nonliving device provides the seed with means to move away from its mother and siblings. The movement may utilize several types of cells, which differ in the arrangement of cell wall cellulose microfibrils. I present here three types of contracting cells that, together with stiff fiber cells resisting any contraction, create a variety of hygroscopic movements.

Single and double tubulin rings were studied under a range of conditions and during microtubule (MT) assembly and disassembly. Here, tubulin was purified from porcine brain and used without any further modifications or additives that promote ring assembly. The structure of single GDP-rich tubulin rings was determined by cryo-transmission electron microscopy and synchrotron solution X-ray scattering. The scattering curves were fitted to atomic models, using our state-of-the-art analysis software, D+ . We found that there is a critical concentration for ring formation, which increased with GTP concentration with temperature. MT assembly or disassembly, induced by changes in temperature, was analyzed by time-resolved small-angle X-ray scattering. During MT assembly, the fraction of rings and unassembled dimers simultaneously decreased. During MT disassembly, the mass fraction of dimers increased. The increase in the concentration of rings was delayed until the fraction of dimers was sufficiently high. We verified that pure dimers, eluted via size-exclusion chromatography, could also form rings. Interestingly, X-ray radiation triggered tubulin ring disassembly. The concentration of disassembled rings versus exposure time followed a first-order kinetics. The disassembly rate constant and initial concentration were determined. X-ray radiation-triggered disassembly was used to determine the concentration of rings. We confirmed that following a temperature jump, the mass fraction of rings decreased and then stabilized at a constant value during the first stage of the MT assembly kinetics. This study sheds light on the most basic assembly and disassembly conditions for in vitro single GDP-rich tubulin rings and their relation to MT kinetics.

Ice-binding proteins (IBPs) contribute to the survival of many living beings at subzero temperature by controlling the formation and growth of ice crystals. This work investigates the structural basis of the ice-binding properties of EfcIBP, obtained from Antarctic bacteria. EfcIBP is endowed with a unique combination of thermal hysteresis and ice recrystallization inhibition activity. The three-dimensional structure, solved at 0.84 Å resolution, shows that EfcIBP belongs to the IBP-1 fold family, and is organized in a right-handed ?-solenoid with a triangular cross-section that forms three protein surfaces, named A, B, and C faces. However, EfcIBP diverges from other IBP-1 fold proteins in relevant structural features including the lack of a ?capping? region on top of the ?-solenoid, and in the sequence and organization of the regions exposed to ice that, in EfcIBP, reveal the presence of threonine-rich ice-binding motifs. Docking experiments and site-directed mutagenesis pinpoint that EfcIBP binds ice crystals not only via its B face, as common to other IBPs, but also via ice-binding sites on the C face. Database Coordinates and structure factors have been deposited in the Protein Data Bank under accession number 6EIO.