A versatile cancer cell trapping and 1D migration assay in a microfluidic device

Highly migratory cancer cells often lead to metastasis and recurrence and are responsible for the high mortality rates in many cancers despite aggressive treatment. Recently, the migratory behavior of patient-derived glioblastoma multiforme cells on microtracks has shown potential in predicting the likelihood of recurrence, while at the same time, antimetastasis drugs have been developed which require simple yet relevant high-throughput screening systems. However, robust in vitro platforms which can reliably seed single cells and measure their migration while mimicking the physiological tumor microenvironment have not been demonstrated. In this study, we demonstrate a microfluidic device which hydrodynamically seeds single cancer cells onto stamped or femtosecond laser ablated polystyrene microtracks, promoting 1D migratory behavior due to the cells' tendency to follow topographical cues. Using time-lapse microscopy, we found that single U87 glioblastoma multiforme cells migrated more slowly on laser ablated microtracks compared to stamped microtracks of equal width and spacing (p < 0.05) and exhibited greater directional persistence on both 1D patterns compared to flat polystyrene (p < 0.05). Single-cell morphologies also differed significantly between flat and 1D patterns, with cells on 1D substrates exhibiting higher aspect ratios and less circularity (p < 0.05). This microfluidic platform could lead to automated quantification of single-cell migratory behavior due to the high predictability of hydrodynamic seeding and guided 1D migration, an important step to realizing the potential of microfluidic migration assays for drug screening and individualized medicine. Published under license by AIP Publishing

Mitocondrial COI and 16S rDNA sequences support morphological identification and biogeography of deep-sea red crabs of the genus Chaceon (Crustacea, Decapoda, Geryonidae) in the Eastern Central and South Atlantic Ocean

The geographical spreading of new fishing activities and the increasingly deeper locations of these activities have shown the worldwide distribution of gerionid crabs and new descriptions of Chaceon taxa. However, incomplete penetrance, variable expressivity, and phenotypic overlap make the morphometric identification of these species difficult. In this study, partial sequences of the cytochrome c oxidase subunit 1 (COI) and 16S mitochondrial ribosomal RNA (16S rRNA) genes have been analyzed in Chaceon species from the Eastern Central and South Atlantic and compared with sequences of species from Western Atlantic. Our results corroborate the proposed morphological species and highlight the significant separation of the Eastern Atlantic species and those from Atlantic coasts of South America for both markers (97% Bayesian posterior probability, BPP / 83% Bootstrap replicates, BT). Interestingly, Chaceon sanctaehelenae shows a closer relationship with the species of the American coast than with those from the Eastern Atlantic. On the other hand, while COI marker clearly separates Chaceon atopus and Chaceon erytheiae species (99 BPP / 91% BT), these species share haplotypes for the 16S rRNA marker, pointing to a recent speciation process. Moreover, a close relationship was observed between Chaceon maritae and Chaceon affinis (94% BPP / 77% BT). The topologies of the trees obtained indicate that the ancestor of this genus was closer related to those species from South America than to those from the Eastern Atlantic.Versión del edito

Fusion reactions of 58,64Ni+124Sn

International audience; In order to better understand the influence of transfer in sub-barrier nuclear reactions, cross sections for the system ^58,64Ni+^124Sn have been measured down to 0.5-1 mub and compared to detailed coupledchannel calculations. In agreement with a phenomenological Q-value systematics, calculations show the importance of including the coupling to the transfer channel for these heavy systems. No clear evidence of fusion hindrance is observed, probably due to the fact that the cross sections measured in this experiment are not low enough for the appearance of that phenomenon

Diversity of ferns and lycophytes in Brazil

This compilation of ferns and lycophytes in Brazil is an update of the one published in 2010 in Catálogo de Plantas e Fungos do Brasil. The methodology consisted in collecting data from regional checklists, taxonomic revisions, and selected databases. Invited specialists improved the list accessing a website housed at the Jardim Botânico do Rio de Janeiro. The results show 1,253 species: 1,111 of ferns and 142 of lycophytes. This number is 6.5% higher than the previous one (1,176 spp.). The percentage of endemic species decreased from 38.2% to 36.7%. We recognized 36 families and 133 genera (vs. 33 families, 121 genera in 2010). The 10 most diverse families are Pteridaceae (196 spp.), Dryopteridaceae (179), Polypodiaceae (164), Hymenophyllaceae (90), Thelypteridaceae (86), Aspleniaceae (78), Lycopodiaceae (64), Selaginellaceae (55), Anemiaceae (51), and Cyatheaceae (45). The three most diverse genera are still Elaphoglossum (87 spp.), Thelypteris (85), and Asplenium (74). The richest phytogeographic domain continues to be in the Atlantic Rainforest with 883 species which also has the largest number of endemic and threatened species, followed by the Amazon Rainforest (503), Cerrado (269), Pantanal (30), Caatinga (26), and Pampa (eight). Minas Gerais remains as the richest state (657 spp. vs. 580 in 2010).Esta compilação de samambaias e licófitas do Brasil é uma atualização daquela de 2010, no Catálogo de Plantas e Fungos do Brasil. A metodologia consistiu na reunião de dados de listas regionais, revisões de grupos e bancos de dados selecionados. Especialistas convidados melhoraram a lista através do acesso a um sítio da web do Jardim Botânico do Rio Janeiro. Os resultados apontam uma diversidade de 1.253 espécies, sendo 1.111 samambaias e 142 licófitas. Este número é 6,5% maior que o anterior (1.176 espécies). As espécies endêmicas decresceram de 38,2% para 36,7%. Foram reconhecidas 36 famílias e 133 gêneros (vs. 33 famílias, 121 gêneros em 2010). As dez famílias mais diversas são: Pteridaceae (196 espécies), Dryopteridaceae (179), Polypodiaceae (164), Hymenophyllaceae (90), Thelypteridaceae (86), Aspleniaceae (78), Lycopodiaceae (64), Selaginellaceae (55), Anemiaceae (51) e Cyatheaceae (45). Os três gêneros mais diversos continuam sendo Elaphoglossum (87 espécies), Thelypteris (85) e Asplenium (74). O Domínio Fitogeográfico mais rico continua sendo a Mata Atlântica (883 espécies) e também com mais espécies endêmicas e ameaçadas, seguido pela Amazônia (503 espécies), Cerrado (269), Pantanal (30), Caatinga (26) e Pampa (oito). Minas Gerais permanece como o estado com maior riqueza (657 espécies vs. 580 em 2010)

Experimental study of the astrophysically important Na 23 (α,p) Mg 26 and Na 23 (α,n) Al 26 reactions

The Na23(α,p)Mg26 and Na23(α,n)Al26 reactions are important for our understanding of the Al26 abundance in massive stars. The aim of this work is to report on a direct and simultaneous measurement of these astrophysically important reactions using an active target system. The reactions were investigated in inverse kinematics using He4 as the active target gas in the detector. We measured the excitation functions in the energy range of about 2 to 6 MeV in the center of mass. We have found that the cross sections of the Na23(α,p)Mg26 and the Na23(α,n)Al26 reactions are in good agreement with previous experiments and with statistical-model calculations. The astrophysical reaction rate of the Na23(α,n)Al26 reaction has been reevaluated and it was found to be larger than the recommended rate

γ -ray spectroscopy of astrophysically important states in Ca 39

Background: Nova explosions synthesize elements up to A≃40, and discrepancies exist between calculated and observed abundances of Ar and Ca created in the explosion. The K38(p,γ)Ca39 reaction rate has been shown to be influential on these isotopic abundances at the endpoint of nova nucleosynthesis. The energies of the three most important resonances, corresponding to Jπ=5/2+ excited states in the Ca39 nucleus above the proton separation threshold, are uncertain and one has been measured with conflicting values [Er=679(2) versus Er=701(2) keV] in previous experiments. Purpose: Reducing the uncertainties on the resonance energies would allow for a better understanding of the reaction rate. To improve these uncertainties, we searched for γ rays from the depopulation of the corresponding excited states in Ca39. Methods: We report a new measurement of these resonance energies via the observation of previously unobserved γ-ray transitions. These transitions were observed by studying the Ca40(3He,αγ)Ca39 reaction with Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies (GODDESS). The updated resonance energies were then used to calculate the K38(p,γ)Ca39 reaction rate and assess its uncertainties. Results: In total, 23 new transitions were found, including three γ-ray transitions corresponding to the three Jπ=5/2+ states of astrophysical interest at energies of 6156.2(16), 6268.8(22), and 6470.8(19) keV. These correspond to resonance energies in the K38(p,γ)Ca39 reaction of 386(2), 498(2), and 701(2) keV. Conclusions: Updated K38(p,γ)Ca39 reaction rate calculations show a reduced upper limit at nova temperatures. However, the lower-than-previously-measured energy of the 498-keV resonance and uncertainty in its resonance strength increases the upper limit of the rate close to previous estimates at 0.4 GK

New γ -ray transitions observed in Ne 19 with implications for the O 15 (α,γ) Ne 19 reaction rate

The O15(α,γ)Ne19 reaction is responsible for breakout from the hot CNO cycle in type I x-ray bursts. Understanding the properties of resonances between Ex=4 and 5 MeV in Ne19 is crucial in the calculation of this reaction rate. The spins and parities of these states are well known, with the exception of the 4.14- and 4.20-MeV states, which have adopted spin-parities of 9/2- and 7/2-, respectively. γ-ray transitions from these states were studied using triton-γ-γ coincidences from the F19(He3,tγ)Ne19 reaction measured with the GODDESS (Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies) at Argonne National Laboratory. The observed transitions from the 4.14- and 4.20-MeV states provide strong evidence that the Jπ values are actually 7/2- and 9/2-, respectively. These assignments are consistent with the values in the F19 mirror nucleus and in contrast to previously accepted assignments

Reaction rate for carbon burning in massive stars

Carbon burning is a critical phase for nucleosynthesis in massive stars. The conditions for igniting this burning stage, and the subsequent isotope composition of the resulting ashes, depend strongly on the reaction rate for C12+C12 fusion at very low energies. Results for the cross sections for this reaction are influenced by various backgrounds encountered in measurements at such energies. In this paper, we report on a new measurement of C12+C12 fusion cross sections where these backgrounds have been minimized. It is found that the astrophysical S factor exhibits a maximum around Ecm=3.5-4.0 MeV, which leads to a reduction of the previously predicted astrophysical reaction rate

Experimental study of Ar 38 +α reaction cross sections relevant to the Ca 41 abundance in the solar system

In massive stars, the Ca41(n,α)Ar38 and K41(p,α)Ar38 reactions have been identified as the key reactions governing the abundance of Ca41, which is considered as a potential chronometer for solar system formation. So far, due to experimental limitations, the Ca41(n,α)Ar38 reaction rate is solely based on statistical model calculations. In the present study, we have measured the time-inverse Ar38(α,n)Ca41 and Ar38(α,p)K41 reactions using an active target detector. The reactions were studied in inverse kinematics using a 133-MeV Ar38 beam and He4 as the active-gas target. Both excitation functions were measured simultaneously in the energy range of 6.8≤Ec.m.≤9.3 MeV. Using detailed balance the Ca41(n,α)Ar38 and K41(p,α)Ar38 reaction rates were determined, which suggested a 20% increase in the Ca41 yield from massive stars

Fusion measurements of 12C+12C at energies of astrophysical interest

The cross section of the 12C+12C fusion reaction at low energies is of paramount importance for models of stellar nucleosynthesis in different astrophysical scenarios, such as Type Ia supernovae and Xray superbursts, where this reaction is a primary route for the production of heavier elements. In a series of experiments performed at Argonne National Laboratory, using Gammasphere and an array of Silicon detectors, measurements of the fusion cross section of 12C+12C were successfully carried out with the γ and charged-particle coincidence technique in the center-of-mass energy range of 3-5 MeV. These were the first background-free fusion cross section measurements for 12C+12C at energies of astrophysical interest. Our results are consistent with previous measurements in the high-energy region; however, our lowest energy measurement indicates a fusion cross section slightly lower than those obtained with other techniques