Mapping Functional Connectivity between Neuronal Ensembles with Larval Zebrafish Transgenic for a Ratiometric Calcium Indicator

The ability to map functional connectivity is necessary for the study of the flow of activity in neuronal circuits. Optical imaging of calcium indicators, including FRET- based genetically encoded indicators and extrinsic dyes, is an important adjunct to electrophysiology and is widely used to visualize neuronal activity. However, techniques for mapping functional connectivities with calcium imaging data have been lacking. We present a procedure to compute reduced functional couplings between neuronal ensembles undergoing seizure activity from ratiometric calcium imaging data in three steps: 1) calculation of calcium concentrations and neuronal firing rates from ratiometric data; 2) identification of putative neuronal populations from spatio-temporal timeseries of neural bursting activity; and then, 3) derivation of reduced connectivity matrices that represent neuronal population interactions. We apply our method to the larval zebrafish central nervous system undergoing chemoconvulsant induced seizures. These seizures generate propagating, central nervous system-wide neural activity from which population connectivities may be calculated. This automatic functional connectivity mapping procedure provides a practical and user-independent means for summarizing the flow of activity between neuronal ensembles

Taste buds are not derived from neural crest in mouse, chicken, and zebrafish

Our lineage tracing studies using multiple Cre mouse lines showed a concurrent labeling of abundant taste bud cells and the underlying connective tissue with a neural crest (NC) origin, warranting a further examination on the issue of whether there is an NC derivation of taste bud cells. In this study, we mapped NC cell lineages in three different models, Sox10-iCreER(T2)/tdT mouse, GFP(+) neural fold transplantation to GFP(−) chickens, and Sox10-Cre/GFP-RFP zebrafish model. We found that in mice, Sox10-iCreER(T2) specifically labels NC cell lineages with a single dose of tamoxifen at E7.5 and that the labeled cells were widely distributed in the connective tissue of the tongue. No labeled cells were found in taste buds or the surrounding epithelium in the postnatal mice. In the GFP(+)/GFP(−) chicken chimera model, GFP(+) cells migrated extensively to the cranial region of chicken embryos ipsilateral to the surgery side but were absent in taste buds in the base of oral cavity and palate. In zebrafish, Sox10-Cre/GFP-RFP faithfully labeled known NC-derived tissues but did not label taste buds in lower jaw or the barbel. Our data, together with previous findings in axolotl, indicate that taste buds are not derived from NC cells in rodents, birds, amphibians or teleost fish

Taste buds are not derived from neural crest in mouse, chicken, and zebrafish

Our lineage tracing studies using multiple Cre mouse lines showed a concurrent labeling of abundant taste bud cells and the underlying connective tissue with a neural crest (NC) origin, warranting a further examination on the issue of whether there is an NC derivation of taste bud cells. In this study, we mapped NC cell lineages in three different models, Sox10-iCreERT2/tdT mouse, GFP+ neural fold transplantation to GFP− chickens, and Sox10-Cre/GFP-RFP zebrafish model. We found that in mice, Sox10-iCreERT2 specifically labels NC cell lineages with a single dose of tamoxifen at E7.5 and that the labeled cells were widely distributed in the connective tissue of the tongue. No labeled cells were found in taste buds or the surrounding epithelium in the postnatal mice. In the GFP+/GFP− chicken chimera model, GFP+ cells migrated extensively to the cranial region of chicken embryos ipsilateral to the surgery side but were absent in taste buds in the base of oral cavity and palate. In zebrafish, Sox10-Cre/GFP-RFP faithfully labeled known NC-derived tissues but did not label taste buds in lower jaw or the barbel. Our data, together with previous findings in axolotl, indicate that taste buds are not derived from NC cells in rodents, birds, amphibians or teleost fish.</p

Chromosome-scale genome assembly of the brown anole (Anolis sagrei), an emerging model species

Rapid technological improvements are democratizing access to high quality, chromosome-scale genome assemblies. No longer the domain of only the most highly studied model organisms, now non-traditional and emerging model species can be genome-enabled using a combination of sequencing technologies and assembly software. Consequently, old ideas built on sparse sampling across the tree of life have recently been amended in the face of genomic data drawn from a growing number of high-quality reference genomes. Arguably the most valuable are those long-studied species for which much is already known about their biology; what many term emerging model species. Here, we report a highly complete chromosome-scale genome assembly for the brown anole, Anolis sagrei – a lizard species widely studied across a variety of disciplines and for which a high-quality reference genome was long overdue. This assembly exceeds the vast majority of existing reptile and snake genomes in contiguity (N50 = 253.6 Mb) and annotation completeness. Through the analysis of this genome and population resequence data, we examine the history of repetitive element accumulation, identify the X chromosome, and propose a hypothesis for the evolutionary history of fusions between autosomes and the X that led to the sex chromosomes of A. sagrei

Methicillin Resistance Alters the Biofilm Phenotype and Attenuates Virulence in Staphylococcus aureus Device-Associated Infections

Clinical isolates of Staphylococcus aureus can express biofilm phenotypes promoted by the major cell wall autolysin and the fibronectin-binding proteins or the icaADBC-encoded polysaccharide intercellular adhesin/poly-N-acetylglucosamine (PIA/PNAG). Biofilm production in methicillin-susceptible S. aureus (MSSA) strains is typically dependent on PIA/PNAG whereas methicillin-resistant isolates express an Atl/FnBP-mediated biofilm phenotype suggesting a relationship between susceptibility to β-lactam antibiotics and biofilm. By introducing the methicillin resistance gene mecA into the PNAG-producing laboratory strain 8325-4 we generated a heterogeneously resistant (HeR) strain, from which a homogeneous, high-level resistant (HoR) derivative was isolated following exposure to oxacillin. The HoR phenotype was associated with a R602H substitution in the DHHA1 domain of GdpP, a recently identified c-di-AMP phosphodiesterase with roles in resistance/tolerance to β-lactam antibiotics and cell envelope stress. Transcription of icaADBC and PNAG production were impaired in the 8325-4 HoR derivative, which instead produced a proteinaceous biofilm that was significantly inhibited by antibodies against the mecA-encoded penicillin binding protein 2a (PBP2a). Conversely excision of the SCCmec element in the MRSA strain BH1CC resulted in oxacillin susceptibility and reduced biofilm production, both of which were complemented by mecA alone. Transcriptional activity of the accessory gene regulator locus was also repressed in the 8325-4 HoR strain, which in turn was accompanied by reduced protease production and significantly reduced virulence in a mouse model of device infection. Thus, homogeneous methicillin resistance has the potential to affect agr- and icaADBC-mediated phenotypes, including altered biofilm expression and virulence, which together are consistent with the adaptation of healthcare-associated MRSA strains to the antibiotic-rich hospital environment in which they are frequently responsible for device-related infections in immuno-compromised patients

Accounting: A General Commentary on an Empirical Science

Many researchers have questioned the view of accounting as a science. Some maintain that it is a service activity rather than a science, yet others entertain the view that it is an art or merely a technology. While it is true that accounting provides a service and is a technology (a methodology for recording and reporting), that fact does not prevent accounting from being a science. Based upon the structure and knowledge base of the discipline, this paper presents the case for accounting as an empirical science

Pratos e mais pratos: louças domésticas, divisões culturais e limites sociais no Rio de Janeiro, século XIX

Reply to ten comments on a paper published in the last issue of this journal. The discussion follows along six main lines: History museums, identity, ideology and the category of nation; the need of material collections and their modalities: patrimonial, operational, virtual; theater versus laboratory; visitors and their ambiguities; Public History: the museum and the academy.Resposta aos comentários de dez especialistas que contribuíram no debate de texto publicado no último número desta revista. A discussão orientou-se segundo seis tópicos principais: museus históricos, identidade, ideologia e a categoria de nação; a necessidade de acervos materiais e suas modalidades: acervo patrimonial, operacional, virtual; teatro versus laboratório; o público e suas ambigüidades; História Pública: o museu e a Academia