Direct cortical input modulates plasticity and spiking in CA1 pyramidal neurons

The hippocampus is necessary for the acquisition and retrieval of declarative memories. The best-characterized sensory input to the hippocampus is the perforant path projection from layer II of entorhinal cortex (EC) to the dentate gyrus. Signals are then processed sequentially in the hippocampal CA fields before returning to the cortex via CA1 pyramidal neuron spikes. There is another EC input-the temporoammonic (TA) pathway-consisting of axons from layer III EC neurons that make synaptic contacts on the distal dendrites of CA1 neurons. Here we show that this pathway modulates both the plasticity and the output of the rat hippocampal formation. Bursts of TA activity can, depending on their timing, either increase or decrease the probability of Schaffer-collateral (SC)-evoked CA1 spikes. TA bursts can also significantly reduce the magnitude of synaptic potentiation at SC-CA1 synapses. The TA-CA1 synapse itself exhibits both long-term depression (LTD) and long-term potentiation (LTP). This capacity for bi-directional plasticity can, in turn, regulate the TA modulation of CA1 activity: LTP or LTD of the TA pathway either enhances or diminishes the gating of CA1 spikes and plasticity inhibition, respectively.     

An asymptotic-giant-branch star in the progenitor system of a type Ia supernova

Stars that explode as supernovae come in two main classes. A type Ia supernova is recognized by the absence of hydrogen and the presence of elements such as silicon and sulphur in its spectrum; this class of supernova is thought to produce the majority of iron-peak elements in the Universe. They are also used as precise 'standard candles' to measure the distances to galaxies. While there is general agreement that a type Ia supernova is produced by an exploding white dwarf star, no progenitor system has ever been directly observed. Significant effort has gone into searching for circumstellar material to help discriminate between the possible kinds of progenitor systems, but no such material has hitherto been found associated with a type Ia supernova. Here we report the presence of strong hydrogen emission associated with the type Ia supernova SN2002ic, indicating the presence of large amounts of circumstellar material. We infer from this that the progenitor system contained a massive asymptotic-giant-branch star that lost several solar masses of hydrogen-rich gas before the supernova explosion.     

A thermosensory pathway controlling flowering time in Arabidopsis thaliana

Onset of flowering is controlled by environmental signals such as light and temperature. Molecular-genetic studies in Arabidopsis thaliana have focused on daily light duration, or photoperiod, and transient exposure to winter-like temperatures, or vernalization. Yet ambient growth temperature, which is strongly affected by current changes in global climate, has been largely ignored. Here, we show that genes of the autonomous pathway, previously thought only to act independently of the environment as regulators of the floral repressor FLC (ref. 1), are centrally involved in mediating the effects of ambient temperature. In contrast to wild-type plants and those mutant in other pathways, autonomous-pathway mutants flower at the same time regardless of ambient temperature. In contrast, the exaggerated temperature response of cryptochrome-2 mutants is caused by temperature-dependent redundancy with the phytochrome A photoreceptor. As with vernalization and photoperiod, ambient temperature ultimately affects expression of the floral pathway integrator FT.     

Post-mating clutch piracy in an amphibian

Female multiple mating and alternative mating systems can decrease the opportunity for sexual selection. Sperm competition is often the outcome of females mating with multiple males and has been observed in many animals, and alternative reproductive systems are widespread among species with external fertilization and parental care. Multiple paternity without associated complex behaviour related to mating or parental care is also seen in simultaneously spawning amphibians and fishes that release gametes into water. Here we report 'clutch piracy' in a montane population of the common frog Rana temporaria, a reproductive behaviour previously unknown in vertebrates with external fertilization. Males of this species clasp the females and the pair deposits one spherical clutch of eggs. No parental care is provided. 'Pirate' males search for freshly laid clutches, clasp them as they would do a female and fertilize the eggs that were left unfertilized by the 'parental' male. This behaviour does not seem to be size-dependent, and some males mate with a female and perform clutch piracy in the same season. Piracy affected 84% of the clutches and in some cases increased the proportion of eggs fertilized, providing direct fitness benefits both for the pirate males and the females. Sexual selection--probably caused by a strong male-biased sex ratio--occurs in this population, as indicated by size-assortative mating; however, clutch piracy may reduce its impact. This provides a good model to explore how alternative mating strategies can affect the intensity of sexual selection.     

Synopsis of the genus Pseudoperma Dillon and Dillon, 1946 (Coleoptera: Cerambycidae), with description of a new species

A synopsis of Pseudoperma is provided. This genus mainly differs from Onocephala and Stethoperma by the antennal tubercles well separated; antennae relatively short, in the female subequal to the body length; and scape and third antennomere subequal in length. Pseudoperma includes two species, P. chalcogramma (Bates, 1887) and P. patruelis (Breuning, 1940), both from Brazil; herein we describe one new species, Pseudoperma lingafelteri sp. nov. from Brazil (Rio de Janeiro). This species differs from its congeners mainly in having the frons and occiput covered with greyish pubescence, and the sides of the elytra with several interrupted or coalescent vittae. We provide new distribution data for Pseudoperma patruelis (Breuning, 1940) from Brazil, Minas Gerais, São Paulo and Santa Catarina, as well as illustrations and a key to the species of Pseudoperma.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:FFD274A3-3AA8-457E-A54C-4CA5AB0340AB     

CBP-mediated SMN acetylation modulates Cajal body biogenesis and the cytoplasmic targeting of SMN

The survival of motor neuron (SMN) protein plays an essential role in the biogenesis of spliceosomal snRNPs and the molecular assembly of Cajal bodies (CBs). Deletion of or mutations in the SMN1 gene cause spinal muscular atrophy (SMA) with degeneration and loss of motor neurons. Reduced SMN levels in SMA lead to deficient snRNP biogenesis with consequent splicing pathology. Here, we demonstrate that SMN is a novel and specific target of the acetyltransferase CBP (CREB-binding protein). Furthermore, we identify lysine (K) 119 as the main acetylation site in SMN. Importantly, SMN acetylation enhances its cytoplasmic localization, causes depletion of CBs, and reduces the accumulation of snRNPs in nuclear speckles. In contrast, the acetylation-deficient SMNK119R mutant promotes formation of CBs and a novel category of promyelocytic leukemia (PML) bodies enriched in this protein. Acetylation increases the half-life of SMN protein, reduces its cytoplasmic diffusion rate and modifies its interactome. Hence, SMN acetylation leads to its dysfunction, which explains the ineffectiveness of HDAC (histone deacetylases) inhibitors in SMA therapy despite their potential to increase SMN levels.     

Distribution of the meadow lizard in Europe and its realized ecological niche model

One of the most interesting but elusive members of the European herpetofauna is the meadow lizard (Darevskia praticola). It is a small, ground dwelling, predominantly forest living lacertid, for which many ecological and biological data are still missing. Moreover, at least for the western part of the species range (south-eastern Europe) its distribution and environmental associations are insufficiently known, likely due to difficulties in detection even with intensive field sampling. Here, we complemented the available literature records with our personal observations and explored the effects of environmental factors shaping the species ecological niche and distribution in Europe using the ecological niche modelling approach from Maxent software. The new records of the meadow lizard fill a gap in its known distribution. The most suitable habitats are in central and eastern Serbia, south-western Romania, and central, southern and south-western Bulgaria. Mean temperature of the coldest quarter, vegetation and slope had the strongest effect in defining the meadow lizard’s ecological niche. Niche suitability increased with the increase in forest cover and slope, while the temperature showed a bell-shaped response with a rather narrow tolerance range for temperature. Contrary to expectations, precipitation seemed to have no contribution to the species occurrence. Ecological niche model performance increased with a higher resolution of predictor variables despite the lower number of available occurrence records, although the slope variable had a greater predictive power when calculated at a lower resolution. Interestingly, high resolution vegetation variables (30 m) were able to show some level of habitat fragmentation, which likely resulted from deforestation. Overall, our results epitomize the effects of limited sampling on the biogeography inference of elusive species while having significant repercussions on conservation priorities and management of the species.