146 research outputs found
Specific pattern of cell cycle during limb fetal myogenesis
AbstractTight regulation of cell proliferation and differentiation is required to ensure proper growth during development and post-natal life. The source and nature of signals regulating cell proliferation are not well identified in vivo. We investigated the specific pattern of proliferating cells in mouse limbs, using the Fluorescent ubiquitynation-based cell-cycle indicator (Fucci) system, which allowed the visualization of the G1, G1/S transition and S/G2/M phases of the cell cycle in red, yellow or green fluorescent colors, respectively. We also used the retroviral RCAS system to express a Fucci cassette in chick embryos. We performed a comprehensive analysis of the cell cycle state of myogenic cells in fetal limb muscles, adult myoblast primary cultures and isolated muscle fiber cultures using the Fucci transgenic mice. We found that myonuclei of terminally differentiated muscle fibers displayed Fucci red fluorescence during mouse and chick fetal development, in adult isolated muscle fiber (ex vivo) and adult myoblast (in vitro) mouse cultures. This indicated that myonuclei exited from the cell cycle in the G1 phase and are maintained in a blocked G1-like state. We also found that cycling muscle progenitors and myoblasts in G1 phase were not completely covered by the Fucci system. During mouse fetal myogenesis, Pax7+ cells labeled with the Fucci system were observed mostly in S/G2/M phases. Proliferating cells in S/G2/M phases displayed a specific pattern in mouse fetal limbs, delineating individualized muscles. In addition, we observed more Pax7+ cells in S/G2/M phases at muscle tips, compared to the middle of muscles. These results highlight a specific spatial regionalization of cycling cells at the muscle borders and muscleâtendon interface during fetal development
NĂO LINGUISTAS FAZEM LINGUĂSTICA? UMA ABORDAGEM ANTIELIMINATIVA DAS IDEIAS POPULARES
Neste artigo, Marie-Anne Paveau discorre sobre como Ă© possĂvel que nĂŁo linguistas produzam saberes linguĂsticos que podem se configurar de vĂĄrios modos possĂveis: de brincadeiras com a lĂngua a saberes empĂricos de ordem estĂ©tica/estilĂstica/literĂĄria e a uma produção vigorosa e importante de juĂzos de valor sobre o uso linguĂstico, avaliando aceitação, atitudes etc. Para a autora, que faz um panorama passando por diversas teorias dos estudos de linguagem â da sociolinguĂstica Ă anĂĄlise da conversa e Ă anĂĄlise do discurso â, o saber (linguĂstico) folk, popular, profano ou leigo â as designaçÔes serĂŁo vĂĄrias ao longo do artigo â Ă© um saber prĂĄtico e Ăștil que ajuda os locutores a manterem/transformarem a sociedade
The role of ocean and atmospheric dynamics in the marine-based collapse of the last Eurasian Ice Sheet
Information from former ice sheets may provide important context for understanding the response of todayâs ice sheets to forcing mechanisms. Here we present a reconstruction of the last deglaciation of marine sectors of the Eurasian Ice Sheet, emphasising how the retreat of the Norwegian Channel and the Barents Sea ice streams led to separation of the British-Irish and Fennoscandian ice sheets at c. 18.700 and of the Kara-Barents Sea-Svalbard and Fennoscandian ice sheets between 16.000 and 15.000 years ago. Combined with ice sheet modelling and palaeoceanographic data, our reconstruction shows that the deglaciation, from a peak volume of 20âm of sea-level rise equivalent, was mainly driven by temperature forced surface mass balance in the south, and by Nordic Seas oceanic conditions in the north. Our results highlight the nonlinearity in the response of an ice sheet to forcing and the significance of ocean-ice-atmosphere dynamics in assessing the fate of contemporary ice sheets
Characterisation of a non-pathogenic and non-protective infectious rabbit lagovirus related to RHDV
The existence of non-pathogenic RHDV strains was established when a non-lethal virus named rabbit
calicivirus (RCV) was characterised in 1996 in Italy. Since then, different RNA sequences related to RHDV have
been detected in apparently healthy domestic and wild rabbits, and recently a new lagovirus was identified in
Australia. We have characterised from seropositive healthy domestic rabbits a non-lethal lagovirus that differs
from RHDV in terms of pathogenicity, tissue tropism and capsid protein sequence. Phylogenetic analyses have
revealed that it is close to the Ashington strain and to the RCV, but distinct. We proved experimentally that it
is infectious but non-pathogenic and demonstrated that, contrary to the other described non-pathogenic
lagoviruses, it induces antibodies that do not protect against RHDV. Our results indicate the existence of a
gradient of cross-protection between circulating strains, from non-protective, partially protective to
protective strains, and highlight the extent of diversity within the genus Lagovirus
Monascus pigment production in bioreactor using a co-product of biodiesel as substrate
SARS-CoV-2 transmission via apical syncytia release from primary bronchial epithelia and infectivity restriction in children epithelia
The beta-coronavirus SARS-CoV-2 is at the origin of a persistent worldwide pandemic. SARS-CoV-2 infections initiate in the bronchi of the upper respiratory tract and are able to disseminate to the lower respiratory tract eventually causing acute severe respiratory syndrome with a high degree of mortality in the elderly. Here we use reconstituted primary bronchial epithelia from adult and children donors to follow the infection dynamic following infection with SARS-CoV-2. We show that in bronchial epithelia derived from adult donors, infections initiate in multi-ciliated cells. Then, infection rapidly spread within 24-48h throughout the whole epithelia. Within 3-4 days, large apical syncytia form between multi-ciliated cells and basal cells, which dissipate into the apical lumen. We show that these syncytia are a significant source of the released infectious dose. In stark contrast to these findings, bronchial epithelia reconstituted from children donors are intrinsically more resistant to virus infection and show active restriction of virus spread. This restriction is paired with accelerated release of IFN compared to adult donors. Taken together our findings reveal apical syncytia formation as an underappreciated source of infectious virus for either local dissemination or release into the environment. Furthermore, we provide direct evidence that children bronchial epithelia are more resistant to infection with SARS-CoV-2 providing experimental support for epidemiological observations that SARS-CoV-2 casesâ fatality is linked to age. Significance Statement Bronchial epithelia are the primary target for SARS-CoV-2 infections. Our work uses reconstituted bronchial epithelia from adults and children. We show that infection of adult epithelia with SARS-CoV-2 is rapid and results in the synchronized release of large clusters of infected cells and syncytia into the apical lumen contributing to the released infectious virus dose. Infection of children derived bronchial epithelia revealed an intrinsic resistance to infection and virus spread, probably as a result of a faster onset of interferon secretion. Thus, our data provide direct evidence for the epidemiological observation that children are less susceptible to SARS-CoV-2
Anatomia patolĂłgica da sinĂłvia de pacientes submetidos Ă liberação do tĂșnel do carpo
An Oral Recombinant Vaccine in Dogs against Echinococcus granulosus, the Causative Agent of Human Hydatid Disease: A Pilot Study
Dogs are the main source of human cystic echinococcosis. An oral vaccine would be an important contribution to control programs in endemic countries. We conducted two parallel experimental trials in Morocco and Tunisia of a new oral vaccine candidate against Echinococcus granulosus in 28 dogs. The vaccine was prepared using two recombinant proteins from adult worms, a tropomyosin (EgTrp) and a fibrillar protein similar to paramyosin (EgA31), cloned and expressed in a live attenuated strain of Salmonella enterica serovar typhimurium
Non-random, individual-specific methylation profiles are present at the sixth CTCF binding site in the human H19/IGF2 imprinting control region
Expression of imprinted genes is classically associated with differential methylation of specific CpG-rich DNA regions (DMRs). The H19/IGF2 locus is considered a paradigm for epigenetic regulation. In mice, as in humans, the essential H19 DMRâtarget of the CTCF insulatorâis located between the two genes. Here, we performed a pyrosequencing-based quantitative analysis of its CpG methylation in normal human tissues. The quantitative analysis of the methylation level in the H19 DMR revealed three unexpected discrete, individual-specific methylation states. This epigenetic polymorphism was confined to the sixth CTCF binding site while a unique median-methylated profile was found at the third CTCF binding site as well as in the H19 promoter. Monoallelic expression of H19 and IGF2 was maintained independently of the methylation status at the sixth CTCF binding site and the IGF2 DMR2 displayed a median-methylated profile in all individuals and tissues analyzed. Interestingly, the methylation profile was genetically transmitted. Transgenerational inheritance of the H19 methylation profile was compatible with a simple model involving one gene with three alleles. The existence of three individual-specific epigenotypes in the H19 DMR in a non-pathological situation means it is important to reconsider the diagnostic value and functional importance of the sixth CTCF binding site
Macrophage-infectivity potentiator of Trypanosoma cruzi (TcMIP) is a new pro-type 1 immuno-stimulating protein for neonatal human cells and vaccines in mice.
peer reviewedThis work identifies the protein "macrophage infectivity potentiator" of Trypanosoma cruzi trypomastigotes, as supporting a new property, namely a pro-type 1 immunostimulatory activity on neonatal cells. In its recombinant form (rTcMIP), this protein triggers the secretion of the chemokines CCL2 and CCL3 by human umbilical cord blood cells from healthy newborns, after 24h in vitro culture. Further stimulation for 72h results in secretion of IFN-Îł, provided cultures are supplemented with IL-2 and IL-18. rTcMIP activity is totally abolished by protease treatment and is not associated with its peptidyl-prolyl cis-trans isomerase enzymatic activity. The ability of rTcMIP to act as adjuvant was studied in vivo in neonatal mouse immunization models, using acellular diphtheria-tetanus-pertussis-vaccine (DTPa) or ovalbumin, and compared to the classical alum adjuvant. As compared to the latter, rTcMIP increases the IgG antibody response towards several antigens meanwhile skewing antibody production towards the Th-1 dependent IgG2a isotype. The amplitude of the rTcMIP adjuvant effect varied depending on the antigen and the co-presence of alum. rTcMIP did by contrast not increase the IgE response to OVA combined with alum. The discovery of the rTcMIP immunostimulatory effect on neonatal cells opens new possibilities for potential use as pro-type 1 adjuvant for neonatal vaccines. This, in turn, may facilitate the development of more efficient vaccines that can be given at birth, reducing infection associated morbidity and mortality which are the highest in the first weeks after birth
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