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101.
102.
103.
Aurora García-Dorado 《Evolution; international journal of organic evolution》1997,51(4):1130-1139
The empirical distribution of the mean viability of mutation accumulation lines, obtained from three published experiments, was analyzed using minimum-distance estimation. In two cases (Mukai et al. 1972; Ohnishi 1977), mutations were allowed to accumulate in copies of chromosome II protected from natural selection and recombination. In the other one (Fernández and López-Fanjul 1996), they accumulated in inbred lines derived from an isogenic stock. In contrast with currently accepted hypotheses, we consistently estimated low (about 0.01) genomic viability mutation rates, λ, and a small kurtosis of the distribution of mutational effects on viability (a) in the three datasets. Minimum-distance estimates of the per-generation mean viability change due to mutation (λE[a]) were also obtained. These were very similar for both chromosomal datasets, their absolute values being about five times smaller than estimates obtained from the observed change in mean viability during the mutation process. It must be noted that, in both experiments, viability was measured relative to the Cy chromosome of a Cy/Pm stock. Thus, an unnoticed viability increase in this Cy chromosome may have resulted in overestimation of the mean viability reduction in the lines. In parallel, minimum-distance estimation of λE(a) from inbred lines data (where the selective pressure during the accumulation process was larger) was even somewhat smaller, in absolute value, and very close to the estimate obtained by comparing the mean viability of the lines with that of the control isogenic line. The evolutionary importance of these results, as well as their relevance to the solution of the mutational load paradox, is discussed. 相似文献
104.
Immunogenicity and safety assessment of the Cuban recombinant hepatitis B vaccine in healthy adults.
Zurina Cinza Estévez Arístides Aguilar Betancourt Verena Muzio González Nelvis Figueroa Baile Carmen Valenzuela Silva Francisco Hernández Bernal Eduardo Pentón Arias Aurora Delhanty Fernández Nelia Martin Olazábal Amaurys del Río Martín Lester Leal Batista Gloria Véliz Ríos Héctor Hernández Hernández Aracelis Blanco Hernández Evelyn Pérez Lugo Joel de la Torre Cruz Bertha L Batista Marchec Leovaldo Alvarez Falcón Jannet Trujillo Brito Darién Ortega León Pedro López Saura 《Biologicals》2007,35(2):115-122
Manufactures of biotechnological/biological products (including vaccines) frequently make changes to manufacturing processes of products both during development and after approval. In our case, a non-inferiority bridging study was carried out to demonstrate that changes in the production plant facilities of Cuban recombinant hepatitis B vaccine, Heberbiovac HB, did not affect the safety and immunogenicity of the vaccine. This controlled, randomized, doubled-blinded trial included 501 volunteers, aged between 20 and 64, who were given three doses of vaccine (20 microg HBsAg/mL) at month 0, 1, and 2. Four lots were evaluated (three corresponding to the new production facilities and a control one produced in the older facilities). One month after the third dose, were observed protective levels of anti-HBsAg in 97% of the subjects that concluded the study with a geometric mean antibody titer (GMT) of 931.18 IU/L. Normal values of body mass index (BMI), the younger ages, and being a female, were significantly related to a good antibody response. The vaccine was well tolerated. Pain at the injection site was the most commonly reported symptom. We conclude that Heberbiovac HB vaccine maintains its characteristics after the modifications carried out in the production plant facilities and both, lot obtained in previous facilities and in the new ones, are comparable in terms of safety and immunogenicity. 相似文献
105.
Structure of the Mouse Mammary Tumor Virus: Characterization of Bald Particles 总被引:13,自引:11,他引:2 下载免费PDF全文
The polypeptide, antigenic, and morphological structure of the mouse mammary tumor virus was studied following protease digestion of intact virions. Intact, untreated virions (rho = 1.17 g/ml) had characteristic envelope spikes, five major polypeptides, and were precipitated by antisera against gp52. Two of the major polypeptides, with molecular weights of 52,000 (gp52) and 36,000 (gp36), had carbohydrate moieties. Protease treatment resulted in spikeless, "bald" particles (rho = 1.14 g/ml), which had altered surface antigenicity and which contained neither gp52 nor gp36. These data indicated that gp52 and gp36 were on the viral envelope. Bald particles retained a 28,000 dalton polypeptide (p28) which was proposed as the major internal polypeptide. 相似文献
106.
Safety Evaluation of Transgenic Tilapia with Accelerated Growth 总被引:2,自引:0,他引:2
Isabel Guillén Jorge Berlanga Carmen M. Valenzuela Antonio Morales José Toledo Mario P. Estrada Pedro Puentes Orlando Hayes José de la Fuente 《Marine biotechnology (New York, N.Y.)》1999,1(1):2-14
Recent advances in modern marine biotechnology have permitted the generation of new strains of economically important fish
species through the transfer of growth hormone genes. These transgenic fish strains show improved growth performance and therefore
constitute a better alternative for aquaculture programs. Recently, we have obtained a transgenic tilapia line with accelerated
growth. However, before introducing this line into Cuban aquaculture, environmental and food safety assessment was required
by national authorities. Experiments were performed to evaluate the behavior of transgenic tilapia in comparison to wild tilapia
as a way to assess the environmental impact of introducing transgenic tilapia into Cuban aquaculture. Studies were also conducted
to evaluate, according to the principle of substantial equivalence, the safety of consuming transgenic tilapia as food. Behavior
studies showed that transgenic tilapia had a lower feeding motivation and dominance status than controls. Food safety assessment
indicated that tilapia growth hormone has no biological activity when administered to nonhuman primates. Furthermore, no effects
were detected in human healthy volunteers after the consumption of transgenic tilapia. These results showed, at least under
the conditions found in Cuba, no environmental implications for the introduction of this transgenic tilapia line and the safety
in the consumption of tiGH-transgenic tilapia as an alternative feeding source for humans. These results support the culture
and consumption of these transgenic tilapia.
Received: March 9, 1998; accepted June 25, 1998. 相似文献
107.
Viability and DNA Maintenance in Nonculturable Spiral Campylobacter jejuni Cells after Long-Term Exposure to Low Temperatures 总被引:3,自引:0,他引:3 下载免费PDF全文
Beatriz Lzaro Jose Crcamo Ana Audícana Ildefonso Perales Aurora Fernndez-Astorga 《Applied microbiology》1999,65(10):4677-4681
Survival of Campylobacter jejuni at 4 and 20°C was investigated by using cellular integrity, respiratory activity, two-dimensional (2D) protein profile, and intact DNA content as indicators of potential viability of nonculturable cells. Intact DNA content after 116 days, along with cellular integrity and respiring cells, was detected for up to 7 months at 4°C by pulsed-field gel electrophoresis. Most changes in 2D protein profiles involved up- or down-regulation. 相似文献
108.
Iacopo Bicci Claudia Calabrese Zoe J Golder Aurora Gomez-Duran Patrick
F Chinnery 《Nucleic acids research》2021,49(22):12757
Methylation on CpG residues is one of the most important epigenetic modifications of nuclear DNA, regulating gene expression. Methylation of mitochondrial DNA (mtDNA) has been studied using whole genome bisulfite sequencing (WGBS), but recent evidence has uncovered technical issues which introduce a potential bias during methylation quantification. Here, we validate the technical concerns of WGBS, and develop and assess the accuracy of a new protocol for mtDNA nucleotide variant-specific methylation using single-molecule Oxford Nanopore Sequencing (ONS). Our approach circumvents confounders by enriching for full-length molecules over nuclear DNA. Variant calling analysis against showed that 99.5% of homoplasmic mtDNA variants can be reliably identified providing there is adequate sequencing depth. We show that some of the mtDNA methylation signal detected by ONS is due to sequence-specific false positives introduced by the technique. The residual signal was observed across several human primary and cancer cell lines and multiple human tissues, but was always below the error threshold modelled using negative controls. We conclude that there is no evidence for CpG methylation in human mtDNA, thus resolving previous controversies. Additionally, we developed a reliable protocol to study epigenetic modifications of mtDNA at single-molecule and single-base resolution, with potential applications beyond CpG methylation. 相似文献
109.
The endothelial-specific microRNA miR-126 governs vascular integrity and angiogenesis 总被引:11,自引:0,他引:11
Wang S Aurora AB Johnson BA Qi X McAnally J Hill JA Richardson JA Bassel-Duby R Olson EN 《Developmental cell》2008,15(2):261-271
Endothelial cells play essential roles in maintenance of vascular integrity, angiogenesis, and wound repair. We show that an endothelial cell-restricted microRNA (miR-126) mediates developmental angiogenesis in vivo. Targeted deletion of miR-126 in mice causes leaky vessels, hemorrhaging, and partial embryonic lethality, due to a loss of vascular integrity and defects in endothelial cell proliferation, migration, and angiogenesis. The subset of mutant animals that survives displays defective cardiac neovascularization following myocardial infarction. The vascular abnormalities of miR-126 mutant mice resemble the consequences of diminished signaling by angiogenic growth factors, such as VEGF and FGF. Accordingly, miR-126 enhances the proangiogenic actions of VEGF and FGF and promotes blood vessel formation by repressing the expression of Spred-1, an intracellular inhibitor of angiogenic signaling. These findings have important therapeutic implications for a variety of disorders involving abnormal angiogenesis and vascular leakage. 相似文献
110.
Nitrate assimilation in Chlamydomonas 总被引:1,自引:0,他引:1