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Effects of pasture implantation on the termite (Isoptera) fauna in the Central Brazilian Savanna (Cerrado)

CARRIJO, Tiago F.; BRANDAO, Divino; OLIVEIRA, Danilo E. de; COSTA, Diogo A.; SANTOS, Thiago
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.1%
The advance of agricultural frontier may cause the Cerrado (Brazilian savanna) to disappear before 2030. This work focuses on measuring the impact of pasture implantation on a cerrado`s termite fauna. Termites were sampled in a cerrado sensu stricto and a pasture, originally cerrado. All species were classified as their feeder group, accumulation curves were made and Shannon-Wiener indexes and beta diversity were calculated for both areas. Cerrado was richer than pasture and species composition differed considerably, leading beta diversity to a high value. The humivorous was the most representative species, followed by grass/litter feeders, xylophagous and, less representative, the intermediates. There were more xylophagous and intermediates species on cerrado than in pasture; the grass/litter feeders were more abundant in pasture, but didn`t differed in number or species; and humivorous didn`t differed neither in richness nor in abundance. This work shows that the simplification of the habitat is indeed causing the extinction of populations that depend on some specifics resource.; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)

Impactos de peso da fêmea no último mês de gestação sobre a ocorrência de leitegadas desuniformes e influência dos parâmetros fisiológicos do leitão ao nascimento sobre seu desempenho pós-natal; Impact of sow’s weight in late gestation on the occurrence of non uniform litters and consequences of piglets physiological parameters changes at birth and postnatal performance

Panzardi, Andrea
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
POR
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25.93%
A suinocultura moderna tem se destacado pelos altos índices produtivos alcançados. Muito disso se deve à intensa tecnificação, fazendo com que as linhagens de fêmeas suínas fossem melhoradas geneticamente tornado-as hiperprolíficas. Este aumento possibilitou uma melhor produtividade e maior ganho econômico. Entretanto, houve o surgimento de problemas relacionados à desuniformidade das leitegadas, contribuindo com uma maior variabilidade de peso dentro delas. Outro fator importante e intrínseco a este, é em relação à viabilidade e vitalidade de leitões menos favorecidos, em virtude de seu baixo peso ao nascimento e possível exposição a eventos estressantes durante o parto. Em busca de possíveis explicações sobre estes problemas gerados em termos produtivos esta tese foi desenvolvida sob a forma de uma revisão literária e dois experimentos. O Trabalho 1 teve como objetivo subsidiar teoricamente a execução tanto do segundo quanto do terceiro experimento, uma vez que foram descritos os principais fatores que afetam o peso do leitão ao nascimento. Após a compilação destes dados surgiu a idéia de realizar dois experimentos complementares a este estudo inicial. O Trabalho 2 teve como objetivo avaliar o efeito de algumas variáveis medidas em leitões logo após o nascimento em relação à sua sobrevivência durante a primeira semana de vida e desenvolvimento posterior até desmame. Foram utilizados 612 leitões oriundos de 56 fêmeas de ordem de parto 3 a 5 as quais o parto foi induzido. Logo após o nascimento foram medidos os seguintes parâmetros: Frequencia cardíaca (FC)...

Ganho de peso de porcas gestantes associado ao comportamento em baias e à uniformidade da leitegada; Weight gain of pregnant sows associated with their behavior in pens and to the uniformity of piglets

Panzardi, Andrea; Mellagi, Ana Paula Gonçalves; Bierhals, Thomas; Gheller, Neimar Bonfanti; Bernardi, Mari Lourdes; Bortolozzo, Fernando Pandolfo; Wentz, Ivo
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
Relevância na Pesquisa
25.93%
O objetivo deste trabalho foi avaliar a associação do comportamento de fêmeas suínas mantidas em baias coletivas, durante a alimentação, com o ganho de peso no último mês de gestação, e determinar se a uniformidade de peso das leitegadas é influenciada pelo ganho de peso das fêmeas. As fêmeas (n = 699) foram separadas em três grupos de ordem de parto (OP): 2, 3–5 e 6–9. Cada grupo de OP foi dividido em três subgrupos com percentual de ganho de peso: baixo, médio e alto. Fêmeas de OP 6–9 tiveram mais leitões com peso menor que 1.200 g e maior coeficiente de variação desse peso, em comparação às de OP 2. O menor peso de leitões e o maior número de leitões com peso<1.200 g foram observados no subgrupo de peso baixo. Houve correlação do percentual de ganho de peso na gestação com o número de vezes que a fêmea esteve em pé no cocho (r = 0,669) e com o número de vezes que a fêmea agrediu outras fêmeas (r = 0,451). A variação do ganho de peso das fêmeas, durante o último mês de gestação, em baias coletivas é influenciada pela competição durante a alimentação, e o menor ganho de peso no último mês de gestação reduz o peso dos leitões ao nascimento; The objective of this work was to evaluate the association between the behavior of group‑housed sows during feeding time...

Characterization of Group C Rotaviruses Associated with Diarrhea Outbreaks in Feeder Pigs

Kim, Yunjeong; Chang, Kyeong-Ok; Straw, Barbara; Saif, Linda J.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /05/1999 EN
Relevância na Pesquisa
25.99%
Feces and serum specimens were collected from three farms in Michigan on which ∼50-lb (8- to 9-week-old) pigs experienced diarrhea just after placement into all-in-all-out finishing barns. The clinical signs (profuse watery diarrhea lasting about 2 weeks and no vomiting) were similar on all farms, and the morbidity rate was high (ranging from 60 to 80%) but without mortality. Eleven diarrheic fecal samples from the farms were tested for group A and C rotaviruses by immune electron microscopy (IEM) and various assays. IEM indicated that the fecal samples reacted only with antiserum against group C rotaviruses, and polyacrylamide gel electrophoresis indicated that the samples had characteristic genomic electropherotypes for group C rotavirus. Group C rotavirus was detected by cell culture immunofluorescence (CCIF) tests in nine fecal samples, but no group A rotavirus was detected by enzyme-linked immunosorbent assay or CCIF. By reverse transcription (RT)-PCR, all 11 fecal samples were positive for group C rotaviruses, with only 2 samples positive for group A rotaviruses. However, a second amplification of RT-PCR products using nested primers detected group A rotaviruses in all samples. Analysis of nucleotide and deduced amino acid sequences of the RT-PCR product (partial-length VP7) of the group C rotavirus showed 87.2 to 91% nucleotide identity and 92.6 to 95.9% amino acid identity among two strong samples from the different farms and the Cowden strain of porcine group C rotavirus. All nine convalescent-phase serum samples tested had neutralizing antibodies to the Cowden strain...

The influence of supplemental chromium and vaccines on the acute phase response of newly arrived feeder calves.

Wright, A J; Mallard, B A; Mowat, D N
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1995 EN
Relevância na Pesquisa
26.03%
The acute phase response as indicated by serum haptoglobin and total haemolytic complement activity (CH50) was measured in 72 cross-bred steer calves purchased at sales in Ontario. During the 28 day (d) trial, 18 steers were randomly assigned to each of the following groups: 1) control; 2) vaccinated (Infectious Bovine Rhinotracheitis, Parainfluenza-3, Bovine Viral Diarrhea, Bovine Respiratory Synctial Virus vaccine plus Pasteurella haemolytica vaccine); 3) supplemental chelated Cr (0.14 mg/kg); and 4) Cr plus vaccines. Haptoglobin concentrations were low at arrival, increased (P < 0.05) on day 7, and returned to near initial levels (P > 0.05) by day 14. Supplemental Cr reduced (P < 0.05) haptoglobin on day 7 when morbidity was highest. Following antibiotic treatment for respiratory disease haptoglobin was lower (P < 0.05) than during morbidity; however, during morbidity, haptoglobin concentrations were not greater in sick calves (P > 0.05) than in healthy calves. Complement activity was lowest on day 7 (P < 0.05) and peaked on day 14 (P < 0.05). Complement activity tended to be lower on day 7 for vaccine, Cr, and Cr+ vaccine groups; however, the difference from controls was not significant (P > 0.10). Complement activity did not increase on day 14 (P > 0.05) with Cr supplementation as in other treatments. Morbid calves had lower (P < 0.05) CH50 activity than healthy calves on day 14. Following antibiotic treatment...

The Effect of Acepromazine Maleate on Feeder Steers in Transit and Feedlot1

MacDonald, M. A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1964 EN
Relevância na Pesquisa
26.1%
The tranquilizer, acepromazine maleate, was evaluated using 34 yearling Hereford feeder steers. Animals injected prior to loading lost significantly less weight (29.5%) during transit from Edmonton to Winnipeg than their untreated counterparts. The weight loss difference following arrival at Macdonald College, Quebec, was not significant. During a short term feeding period the group fed ace promazine maleate gained significantly more rapidly (12.8%) than the control group. There were no significant differences in dressing percentage or carcass grade.

Mesothelial cells stimulate the anchorage-independent growth of human ovarian tumour cells.

Wilson, A. P.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em /06/1989 EN
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26.03%
Results are presented which show that mesothelial cells (MC) from ovarian cancer patients can both stimulate and inhibit the clonogenic growth of ovarian tumour cells (TC) in a dose-dependent fashion. TC lines from both non-ovarian and ovarian tumours were variable in their response to MC. Colony formation was rarely induced when the TC population was non-clonogenic and a bladder cell line showed inhibition of colony formation in the presence of MC. Primary tumour cultures from ovarian cancer patients also showed a variable response to MC. Fibroblasts from malignant, benign and non-neoplastic sources were significantly less effective in stimulating the clonogenic growth of responsive cell lines. Conditioned medium was a poor substitute for the presence of intact viable cells, and distance between feeder cell and TC was an important factor in determining the magnitude of response. A significant relationship between the feeder effect of MC and their proliferation in soft agar was observed when epidermal growth factor was used in the medium. The relevance of the findings in the context of the pattern of spread of ovarian cancer is discussed.

The scleritome of Paterimitra: an Early Cambrian stem group brachiopod from South Australia

Skovsted, Christian B.; Holmer, Lars E.; Larsson, Cecilia M.; Högström, Anette E.S.; Brock, Glenn A.; Topper, Timothy P.; Balthasar, Uwe; Stolk, Sandra Petterson; Paterson, John R.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
EN
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Early Cambrian tommotiids are problematic fossil metazoans with external organophosphatic sclerites that have been considered to be basal members of the lophophorate stem group. Tommotiids are almost exclusively known from isolated or rarely fused individual sclerites, which made previous reconstructions of the actual organism highly conjectural. However, the recent discovery of the first articulated specimens of the tommotiid Eccentrotheca revealed a tubular sclerite arrangement (scleritome) that limited the possible life habit to sessile filter feeding and thus further supported a lophophorate affinity. Here, we report the first articulated specimens of a second tommotiid taxon, Paterimitra from the Early Cambrian of the Arrowie Basin, South Australia. Articulated specimens of Paterimitra are composed of two bilaterally symmetrical sclerite types and an unresolved number of small, asymmetrical and irregular crescent-shaped sclerites that attached to the anterior margin of the symmetrical sclerites. Together, the sclerites form an open cone in which the symmetrical sclerites are joined together and form a small posterior opening near the base of the scleritome, while the irregular crescent-shaped sclerites defined a broad anterior opening. The coniform scleritome of Paterimitra is interpreted to have attached to hard substrates via a pedicle that emerged through the small posterior opening (sometimes forming a tube) and was probably a sessile filter feeder. The scleritome of Paterimitra can be derived from the tubular scleritome of Eccentrotheca by modification of basal sclerites and reduction in tube height...

A novel platform to enable the high-throughput derivation and characterization of feeder-free human iPSCs

Valamehr, Bahram; Abujarour, Ramzey; Robinson, Megan; Le, Thuy; Robbins, David; Shoemaker, Daniel; Flynn, Peter
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 06/01/2012 EN
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36.03%
Human induced pluripotent stem cells (hiPSCs) hold enormous potential, however several obstacles impede their translation to industrial and clinical applications. Here we describe a platform to efficiently generate, characterize and maintain single cell and feeder-free (FF) cultured hiPSCs by means of a small molecule cocktail media additive. Using this strategy we have developed an effective multiplex sorting and high-throughput selection platform where individual clonal hiPSC lines are readily obtained from a pool of candidate clones, expanded and thoroughly characterized. By promoting survival and self-renewal, the selected hiPSC clones can be rapidly expanded over multiple FF, single-cell passages while maintaining their pluripotency and genomic stability as demonstrated by trilineage differentiation, karyotype and copy number variation analysis. This study provides a robust platform that increases efficiency, throughput, scale and quality of hiPSC generation and facilitates the industrial and clinical use of iPSC technology.

Feeder-Free Derivation of Human Induced Pluripotent Stem Cells with Messenger RNA

Warren, Luigi; Ni, Yuhui; Wang, Jiwu; Guo, Xirong
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 14/09/2012 EN
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The therapeutic promise of induced pluripotent stem cells (iPSCs) has spurred efforts to circumvent genome alteration when reprogramming somatic cells to pluripotency. Approaches based on episomal DNA, Sendai virus, and messenger RNA (mRNA) can generate “footprint-free” iPSCs with efficiencies equaling or surpassing those attained with integrating viral vectors. The mRNA method uniquely affords unprecedented control over reprogramming factor (RF) expression while obviating a cleanup phase to purge residual traces of vector. Currently, mRNA-based reprogramming is relatively laborious due to the need to transfect daily for ~2 weeks to induce pluripotency, and requires the use of feeder cells that add complexity and variability to the procedure while introducing a route for contamination with non-human-derived biological material. We accelerated the mRNA reprogramming process through stepwise optimization of the RF cocktail and leveraged these kinetic gains to establish a feeder-free, xeno-free protocol which slashes the time, cost and effort involved in iPSC derivation.

Microfluidic isolation of highly pure embryonic stem cells using feeder-separated co-culture system

Chen, Qiushui; Wu, Jing; Zhuang, Qichen; Lin, Xuexia; Zhang, Jie; Lin, Jin-Ming
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 14/08/2013 EN
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36.23%
Engineered artificial tissues from stem cells show great potential in regenerative medicine, disease therapies and organ transplantation. To date, stem cells are typically co-cultured with inactivated feeder layers to maintain their undifferentiated state, and to ensure reliable cell purity. Herein, we propose a novel microfabricated approach for feeder-separated coculture of mouse embryonic stem (mES) cells on polydimethylsiloxane (PDMS) porous membrane-assembled 3D-microdevice. Normal mouse embryonic fibroblasts (mEFs) without inactivation were specifically co-cultured with mES cells, resulting in the formation of mES cell colonies on spatially controlled co-culture with feeder layers. An excellent undifferentiated state was confirmed by the expressions of Nanog, octamer binding protein 4 (Oct-4) and alkaline phosphatase (ALP) after 5 days culture. As a result, with the significant advantages of efficiency and simplicity, pure mES cell populations (a purity of 89.2%) from mEFs co-cultures were easily collected without any further purification or separation.

Highly efficient induction and long-term maintenance of multipotent cardiovascular progenitors from human pluripotent stem cells under defined conditions

Cao, Nan; Liang, He; Huang, Jijun; Wang, Jia; Chen, Yixiong; Chen, Zhongyan; Yang, Huang-Tian
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.03%
Cardiovascular progenitor cells (CVPCs) derived from human pluripotent stem cells (hPSCs), including human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), hold great promise for the study of cardiovascular development and cell-based therapy of heart diseases, but their applications are challenged by the difficulties in their efficient generation and stable maintenance. This study aims to develop chemically defined systems for robust generation and stable propagation of hPSC-derived CVPCs by modulating the key early developmental pathways involved in human cardiovascular specification and CVPC self-renewal. Herein we report that a combination of bone morphogenetic protein 4 (BMP4), glycogen synthase kinase 3 (GSK3) inhibitor CHIR99021 and ascorbic acid is sufficient to rapidly convert monolayer-cultured hPSCs, including hESCs and hiPSCs, into homogeneous CVPCs in a chemically defined medium under feeder- and serum-free culture conditions. These CVPCs stably self-renewed under feeder- and serum-free conditions and expanded over 107-fold when the differentiation-inducing signals from BMP, GSK3 and Activin/Nodal pathways were simultaneously eliminated. Furthermore, these CVPCs exhibited expected genome-wide molecular features of CVPCs...

Depth of origin of magma in eruptions

Becerril, Laura; Galindo, Ines; Gudmundsson, Agust; Morales, Jose Maria
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 26/09/2013 EN
Relevância na Pesquisa
26.03%
Many volcanic hazard factors - such as the likelihood and duration of an eruption, the eruption style, and the probability of its triggering large landslides or caldera collapses - relate to the depth of the magma source. Yet, the magma source depths are commonly poorly known, even in frequently erupting volcanoes such as Hekla in Iceland and Etna in Italy. Here we show how the length-thickness ratios of feeder dykes can be used to estimate the depth to the source magma chamber. Using this method, accurately measured volcanic fissures/feeder-dykes in El Hierro (Canary Islands) indicate a source depth of 11–15 km, which coincides with the main cloud of earthquake foci surrounding the magma chamber associated with the 2011–2012 eruption of El Hierro. The method can be used on widely available GPS and InSAR data to calculate the depths to the source magma chambers of active volcanoes worldwide.

A novel efficient feeder-free culture system for the derivation of human induced pluripotent stem cells

Nakagawa, Masato; Taniguchi, Yukimasa; Senda, Sho; Takizawa, Nanako; Ichisaka, Tomoko; Asano, Kanako; Morizane, Asuka; Doi, Daisuke; Takahashi, Jun; Nishizawa, Masatoshi; Yoshida, Yoshinori; Toyoda, Taro; Osafune, Kenji; Sekiguchi, Kiyotoshi; Yamanaka, Sh
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 08/01/2014 EN
Relevância na Pesquisa
36.03%
In order to apply human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) to regenerative medicine, the cells should be produced under restricted conditions conforming to GMP guidelines. Since the conventional culture system has some issues that need to be addressed to achieve this goal, we developed a novel culture system. We found that recombinant laminin-511 E8 fragments are useful matrices for maintaining hESCs and hiPSCs when used in combination with a completely xeno-free (Xf) medium, StemFit™. Using this system, hESCs and hiPSCs can be easily and stably passaged by dissociating the cells into single cells for long periods, without any karyotype abnormalities. Human iPSCs could be generated under feeder-free (Ff) and Xf culture systems from human primary fibroblasts and blood cells, and they possessed differentiation abilities. These results indicate that hiPSCs can be generated and maintained under this novel Ff and Xf culture system.

Derivation and characterization of human embryonic stem cells on human amnion epithelial cells

Lai, Dongmei; Wang, Yongwei; Sun, Jian; Chen, Yifei; Li, Ting; Wu, Yi; Guo, Lihe; Wei, Chunsheng
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 07/05/2015 EN
Relevância na Pesquisa
26.03%
Culture conditions that support the growth of undifferentiated human embryonic stem cells (hESCs) have already been established using primary human amnion epithelial cells (hAECs) as an alternative to traditional mitotically inactivated mouse embryonic fibroblasts (MEFs). In the present work, inner cell masses (ICM) were isolated from frozen embryos obtained as donations from couples undergoing in vitro fertilization (IVF) treatment and four new hESC lines were derived using hAECs as feeder cells. This feeder system was able to support continuous growth of what were, according to their domed shape and markers, undifferentiated naïve-like hESCs. Their pluripotent potential were also demonstrated by embryoid bodies developing to the expected three germ layers in vitro and the productions of teratoma in vivo. The cell lines retained their karyotypic integrity for over 35 passages. Transmission electron microscopy (TEM) indicated that these newly derived hESCs consisted mostly of undifferentiated cells with large nuclei and scanty cytoplasm. The new hESCs cultured on hAECs showed distinct undifferentiated characteristics in comparison to hESCs of the same passage maintained on MEFs. This type of optimized culture system may provide a useful platform for establishing clinical-grade hESCs and assessing the undifferentiated potential of hESCs.

Who started first? Bird species visiting novel birdfeeders

Tryjanowski, Piotr; Morelli, Federico; Skórka, Piotr; Goławski, Artur; Indykiewicz, Piotr; Pape Møller, Anders; Mitrus, Cezary; Wysocki, Dariusz; Zduniak, Piotr
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 07/07/2015 EN
Relevância na Pesquisa
26.03%
Adapting to exploit new food sources may be essential, particularly in winter, when the impact of food limitation on survival of individuals is critical. One of the most important additional sources of food for birds in human settlements is birdfeeders. At a large spatial scale, we experimentally provided birdfeeders with four different kinds of food to analyze exploitation and use of a novel food supply provided by humans. Nine species started foraging at the new birdfeeders. The species that exploited the new feeders the fastest was the great tit. Use of novel food sources was faster in urban habitats and the presence of other feeders reduced the time until a new feeder was located. Urbanization may be associated with behavioural skills, technical innovations and neophilia resulting in faster discovery of new food sources. This process is accelerated by the experience of feeder use in the vicinity, with a strong modifying effect of the number of domestic cats.

Enzyme-free Passage of Human Pluripotent Stem Cells by Controlling Divalent Cations

Ohnuma, Kiyoshi; Fujiki, Ayaka; Yanagihara, Kana; Tachikawa, Saoko; Hayashi, Yohei; Ito, Yuzuru; Onuma, Yasuko; Chan, Techuan; Michiue, Tatsuo; Furue, Miho K.; Asashima, Makoto
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 11/04/2014 EN
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26.03%
Enzymes used for passaging human pluripotent stem cells (hPSCs) digest cell surface proteins, resulting in cell damage. Moreover, cell dissociation using divalent cation-free solutions causes apoptosis. Here we report that Mg2+ and Ca2+ control cell-fibronectin and cell-cell binding of hPSCs, respectively, under feeder- and serum-free culture conditions without enzyme. The hPSCs were detached from fibronectin-, vitronectin- or laminin-coated dishes in low concentrations of Mg2+ and remained as large colonies in high concentrations of Ca2+. Using enzyme-free solutions containing Ca2+ without Mg2+, we successfully passaged hPSCs as large cell clumps that showed less damage than cells passaged using a divalent cation-free solution or dispase. Under the same conditions, the undifferentiated and early-differentiated cells could also be harvested as a cell sheet without being split off. Our enzyme-free passage of hPSCs under a serum- and feeder-free culture condition reduces cell damage and facilitates easier and safer cultures of hPSCs.

Xeno-free culture of human spermatogonial stem cells supported by human embryonic stem cell-derived fibroblast-like cells

Chen, Bin; Wang, Yu-Bin; Zhang, Zhi-Ling; Xia, Wei-Liang; Wang, Hong-Xiang; Xiang, Zu-Qiong; Hu, Kai; Han, Yin-Fa; Wang, Yi-Xin; Huang, Yi-Ran; Wang, Zheng
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
EN
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26.03%
Spermatogonial stem cells (SSCs) divide continuously to support spermatogenesis throughout postnatal life and transmit genetic information to the next generation. Here, we report the successful establishment of the method for the isolation and identification of human SSCs from testicular tissue, and to determine the culture conditions required to expand SSCs on human embryonic stem cell-derived fibroblast-like cells (hdFs). Large-scale cultures of SSCs were maintained on hdF feeder layers and expanded in the presence of a combination of cytokines and glial cell line-derived neurotrophic factor for at least 2 months. Cell surface marker analysis showed that SSCs retained high levels of alkaline phosphatase activity and stained strongly for anti-stage-specific embryonic antigen (SSEA)-1, OCT4 and CD49f. They also expressed the genes OCT4, SOX3 and STRA8 as detected by reverse transcription polymerase chain reaction (RT-PCR) analysis. These data clearly illustrate a novel approach for the growth of human SSCs using hdFs as feeder cells, potentially eliminating xenogeneic contaminants. This system provides a new opportunity for the study of the regulatory mechanism of the 'niche' that governs SSC self-renewal, and will be a valuable source of SSCs for potential clinical applications.

Use of ordinal information by fish

Petrazzini, Maria Elena Miletto; Lucon-Xiccato, Tyrone; Agrillo, Christian; Bisazza, Angelo
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 26/10/2015 EN
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26.28%
Mammals and birds can process ordinal numerical information which can be used, for instance, for recognising an object on the basis of its position in a sequence of similar objects. Recent studies have shown that teleost fish possess numerical abilities comparable to those of other vertebrates, but it is unknown if they can also learn ordinal numerical relations. Guppies (Poecilia reticulata) learned to recognise the 3rd feeder in a row of 8 identical ones even when inter-feeder distance and feeder positions were varied among trials to prevent the use of any spatial information. To assess whether guppies spontaneously use ordinal or spatial information when both are simultaneously available, fish were then trained with constant feeder positions and inter-feeder distance. In probe trials where these two sources of information were contrasted, the subjects selected the correct ordinal position significantly more often than the original spatial position, indicating that the former was preferentially encoded during training. Finally, a comparison between subjects trained on the 3rd and the 5th position revealed that guppies can also learn the latter discrimination, but the larger error rate observed in this case suggests that 5 is close to the upper limit of discrimination in guppies.

Sucessões vulcânicas, modelo de alimentação e geração de domos de lava ácidos da Formação Serra Geral na região de São Marcos-Antônio Prado (RS); Volcanic succession and feeder systems of acidic lava-domes of Serra Geral Formation in São Marcos-Antônio Prado region, South Brazil

Lima, Evandro Fernandes de; Philipp, Ruy Paulo; Rizzon, Gabriela Cioato; Waichel, Breno Leitão; Rossetti, Lucas de Magalhães May
Fonte: Universidade de São Paulo. Instituto de Geociências Publicador: Universidade de São Paulo. Instituto de Geociências
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; Formato: application/pdf
Publicado em 01/08/2012 POR
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26.15%
Na região entre São Marcos (RS) e Antônio Prado (RS), a Formação Serra Geral expõe na base uma sucessão de basaltos do tipo pahoehoe sotopostos a derrames ´a´ā. Os primeiros foram gerados por um volume de erupção baixo em um regime de fluxo fechado e colocado em uma paleotopografia plana (< 5° de declividade). A lenta perda de calor deste sistema permite que os fluxos atinjam distâncias da fonte > 100 km. Os tipos ´a´ā foram gerados por descargas dos fluxos superiores às das pahoehoe e transportados em canais abertos, em que o rápido resfriamento limita o deslocamento dos fluxos por longas distâncias da fonte. Ambos são toleíticos de baixo TiO2 e a morfologia dos derrames não pode ser explicada por variações geoquímicas. Acima destes afloram vulcanitos ácidos quimicamente compatíveis com o Grupo Palmas e Subgrupo Caxias. Recentemente, a extração de rochas ornamentais na região expôs as porções internas dos diques de alimentação deste vulcanismo. Observam-se estruturas magmáticas subverticais e verticais que em superfície abasteceram domos de lavas com características exógenas. Propõe-se um modelo para a geração destes envolvendo a ascensão diapírica de magmas ácidos que se tornam vesiculados...