The architecture of cell differentiation in choanoflagellates and sponge choanocytes

Collar cells are ancient animal cell types which are conserved across the animal kingdom and their closest relatives, the choanoflagellates. However, little is known about their ancestry, their subcellular architecture, or how they differentiate. The choanoflagellate Salpingoeca rosetta expresses genes necessary for animal multicellularity and development and can alternate between unicellular and multicellular states making it a powerful model to investigate the origin of animal multicellularity and mechanisms underlying cell differentiation. To compare the subcellular architecture of solitary collar cells in S. rosetta with that of multicellular 'rosettes' and collar cells in sponges, we reconstructed entire cells in 3D through transmission electron microscopy on serial ultrathin sections. Structural analysis of our 3D reconstructions revealed important differences between single and colonial choanoflagellate cells, with colonial cells exhibiting a more amoeboid morphology consistent with relatively high levels of macropinocytotic activity. Comparison of multiple reconstructed rosette colonies highlighted the variable nature of cell sizes, cell-cell contact networks and colony arrangement. Importantly, we uncovered the presence of elongated cells in some rosette colonies that likely represent a distinct and differentiated cell type. Intercellular bridges within choanoflagellate colonies displayed a variety of morphologies and connected some, but not all, neighbouring cells. Reconstruction of sponge choanocytes revealed both ultrastructural commonalities and differences in comparison to choanoflagellates. Choanocytes and colonial choanoflagellates are typified by high amoeboid cell activity. In both, the number of microvilli and volumetric proportion of the Golgi apparatus are comparable, whereas choanocytes devote less of their cell volume to the nucleus and mitochondria than choanoflagellates and more of their volume to food vacuoles. Together, our comparative reconstructions uncover the architecture of cell differentiation in choanoflagellates and sponge choanocytes and constitute an important step in reconstructing the cell biology of the last common ancestor of the animal kingdom

Choanoflagellates and the ancestry of neurosecretory vesicles

Neurosecretory vesicles are highly specialized trafficking organelles that store neurotransmitters that are released at presynaptic nerve endings and are, therefore, important for animal cell–cell signalling. Despite considerable anatomical and functional diversity of neurons in animals, the protein composition of neurosecretory vesicles in bilaterians appears to be similar. This similarity points towards a common evolutionary origin. Moreover, many putative homologues of key neurosecretory vesicle proteins predate the origin of the first neurons, and some even the origin of the first animals. However, little is known about the molecular toolkit of these vesicles in non-bilaterian animals and their closest unicellular relatives, making inferences about the evolutionary origin of neurosecretory vesicles extremely difficult. By comparing 28 proteins of the core neurosecretory vesicle proteome in 13 different species, we demonstrate that most of the proteins are present in unicellular organisms. Surprisingly, we find that the vesicular membrane-associated soluble N-ethylmaleimide-sensitive factor attachment protein receptor protein synaptobrevin is localized to the vesicle-rich apical and basal pole in the choanoflagellate Salpingoeca rosetta. Our 3D vesicle reconstructions reveal that the choanoflagellates S. rosetta and Monosiga brevicollis exhibit a polarized and diverse vesicular landscape reminiscent of the polarized organization of chemical synapses that secrete the content of neurosecretory vesicles into the synaptic cleft. This study sheds light on the ancestral molecular machinery of neurosecretory vesicles and provides a framework to understand the origin and evolution of secretory cells, synapses and neurons. This article is part of the theme issue ‘Basal cognition: multicellularity, neurons and the cognitive lens’

The Botryosphaeriaceae: genera and species known from culture

In this paper we give an account of the genera and species in the Botryosphaeriaceae. We consider morphological characters alone as inadequate to define genera or identify species, given the confusion it has repeatedly introduced in the past, their variation during development, and inevitable overlap as representation grows. Thus it seems likely that all of the older taxa linked to the Botryosphaeriaceae, and for which cultures or DNA sequence data are not available, cannot be linked to the species in this family that are known from culture. Such older taxa will have to be disregarded for future use unless they are epitypified. We therefore focus this paper on the 17 genera that can now be recognised phylogenetically, which concentrates on the species that are presently known from culture. Included is a historical overview of the family, the morphological features that define the genera and species and detailed descriptions of the 17 genera and 110 species. Keys to the genera and species are also provided. Phylogenetic relationships of the genera are given in a multi-locus tree based on combined SSU, ITS, LSU, EF1-α and β-tubulin sequences. The morphological descriptions are supplemented by phylogenetic trees (ITS alone or ITS + EF1-α) for the species in each genus.We would like to thank the curators of the numerous fungaria and Biological Resource Centres cited in this paper, for making specimens and cultures available for examination over the past 15 yr, without which this study would not have been possible. Part of this work was supported by Fundação para a Ciência e a Tecnologia (Portugal) through grant PEst-OE/BIA/UI0457/2011. Artur Alves and Alan Phillips were supported by the programme Ciência 2008, co-funded by the Human Potential Operational Programme (National Strategic Reference Framework 2007–2013) and the European Social Fund (EU).publishe

A prospective randomized clinical trial of the use of fluoroscopy in obtaining femoral arterial access

There is no consensus on the utility of fluoroscopy in obtaining common femoral artery (CFA) access. Patients weighing < 136.4 kg (300 lbs) with palpable femoral pulses undergoing coronary angiography were randomized to arterial access with or without the use of fluoroscopy (using the center of the femoral head as the optimal site to enter the artery). 208 patients were enrolled with 110 randomized to the palpation group and 98 were randomized to the palpation +fluoroscopy group. Mean age (+/- SD) was 60 +/- 11 years, 61% were male, 35% had diabetes, and 40% had a body mass index (BMI) > 30 kg/m(2). Clinical characteristics and procedural factors were similar among the two groups with the exception that fewer needle passes were required and access was achieved faster in the palpation group. Arterial puncture over the femoral head occurred in 91% of the palpation group versus 95% of the palpation + fluoroscopy group (p = 0.27). Successful CFA puncture occurred in 85% of the palpation group versus 90% of the palpation + fluoroscopy group (p = 0.49). Cannulation of the external iliac artery occurred in 1 patient in each group, whereas arterial puncture distal to the CFA bifurcation occurred in 16 (15%) of the palpation group and in 9 (9%) of the palpation + fluoroscopy group (p = 0.33). In this single-center, randomized trial, the use of fluoroscopy did not increase the probability of arterial puncture over the femoral head or the rate of successful CFA cannulation