The elegans of spindle assembly

The Caenorhabditis elegans one-cell embryo is a powerful system in which to study microtubule organization because this large cell assembles both meiotic and mitotic spindles within the same cytoplasm over the course of 1 h in a stereotypical manner. The fertilized oocyte assembles two consecutive acentrosomal meiotic spindles that function to reduce the replicated maternal diploid set of chromosomes to a single-copy haploid set. The resulting maternal DNA then unites with the paternal DNA to form a zygotic diploid complement, around which a centrosome-based mitotic spindle forms. The early C. elegans embryo is amenable to live-cell imaging and electron tomography, permitting a detailed structural comparison of the meiotic and mitotic modes of spindle assembly

Kepler K2 Campaign 9: II. First space-based discovery of an exoplanet using microlensing

We report on the discovery of a bound exoplanetary microlensing event from a blind search of data gathered from Campaign 9 of the Kepler K2 mission (K2C9). K2-2016-BLG-0005Lb is a densely sampled, binary caustic-crossing microlensing event with caustic entry and exit points that are resolved in the K2C9 data, enabling the lens-source relative proper motion to be measured. We have fitted a binary microlens model to the K2 dataset, and to simultaneous observations from the Optical Gravitational Lensing Experiment (OGLE-IV), Canada-France-Hawaii Telescope (CFHT), Microlensing Observations in Astrophysics (MOA-2), the Korean Microlensing Telescope Network (KMTNet), and the United Kingdom InfraRed Telescope (UKIRT). Whilst the ground-based data only sparsely sample the binary caustic, they provide a clear detection of parallax that allows us to break completely the microlensing mass-position-velocity degeneracy and measure the planet's mass directly. We find a host mass of $0.58\pm0.03 ~{\rm M}_\odot$ and a planetary mass of $1.1 \pm 0.1 ~{\rm M_J}$. The system lies at a distance of $5.2 \pm 0.2~$kpc from Earth towards the Galactic bulge. The projected physical separation of the planet from its host is found to be $4.2 \pm 0.3~$au which, for circular orbits, corresponds to $a = 4.4^{+1.9}_{-0.4}~$au and period $P = 13^{+9}_{-2}~$yr, making K2-2016-BLG-0005Lb a close Jupiter analogue. Though previous exoplanet microlensing events have included space-based data, this event is the first bound microlensing exoplanet to be discovered from space-based data. Even through a space telescope not designed for microlensing studies, this result highlights the advantages for exoplanet microlensing discovery that come from continuous, high-cadence temporal sampling that is possible from space. (Abridged).Comment: 17 pages. Submitted to MNRA

Cardiopoietic cell therapy for advanced ischemic heart failure: results at 39 weeks of the prospective, randomized, double blind, sham-controlled CHART-1 clinical trial

Cardiopoietic cells, produced through cardiogenic conditioning of patients' mesenchymal stem cells, have shown preliminary efficacy. The Congestive Heart Failure Cardiopoietic Regenerative Therapy (CHART-1) trial aimed to validate cardiopoiesis-based biotherapy in a larger heart failure cohort

Flooding of tropical forests in central Amazonia: what do the effects on the photosynthetic apparatus of trees tell us about species suitability for reforestation in extreme environments created by hydroelectric dams?

Brazil plans to construct many new hydroelectric dams in the Amazon region. The new conditions of flooding promoted by reservoirs can alter photosynthetic processes, and the study of physiological responses of trees can be used for selected suitable species to reforest these altered areas. The present study analyzed changes in pigment content and photosynthetic performance in flood-tolerant and flood-intolerant species that are common in the floodplains along the Uatumã River and on islands in the reservoir of the Balbina Hydroelectric Dam. Their photosynthetic responses were tested using chloroplast pigment content and chlorophyll a fluorescence. Flooding caused a significant reduction in pigment content in all of the three flood-intolerant species and in one of the seven flood-tolerant species studied. Flood-tolerant species were unaffected and neither a change in their chlorophyll contents nor a decrease in the efficiency of energy use in the photosynthetic process was observed. From chlorophyll a fluorescence transients (OJIP transients) was calculated the performance index (PIABS), a parameter derived from the OJIP transient by means of the JIP-test (translation of original fluorescence measurements into biophysical expressions quantifying the stepwise flow of energy through photosystem II). This parameter was a very sensitive indicator of the physiological status of trees under field and was shown to be a particularly sensitive indicator of stress tolerance in flood-intolerant species during inundation, whereas flood-tolerant species had only minor reductions in their photosynthetic performance. We suggest that tree species selection for reforestation around reservoirs can benefit from species-specific measurements of photosynthetic response using the JIP-test. © 2015, Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków