Mitochondrial genotype segregation and effects during mammalian development: Applications to biotechnology

Mitochondria are endosymbiotic organelles responsible for energy production in practically every eukaryotic cell. Their uniparental fashion of inheritance, maternally inherited in mammals, and the homogeneity of mitochondrial DNA (mtDNA) within individuals and matrilineages, are biological phenomena that remain unexplained. This paper reviews some of the recent findings on mitochondrial influences on the manner in which embryos develop and how their genotypes are inherited in mammals, with particular emphasis on the genetic bottleneck effect. Animal models carrying a mix of mtDNAs (heteroplasmic) have been produced by karyoplast and cytoplast transplantation to analyze the segregation patterns at different stages during embryogenesis, in fetuses and offspring. Comparisons performed between murine and bovine reveal interesting changes in segregation and replication of transplanted mtDNAs. We have recently obtained Bos indicus and Bos taurus fetuses and calves from embryos reconstructed using enucleated polymorphic oocytes of Bos taurus origin. These and other findings on mitochondrial biology will have important implications in determining the cytoplasmic genotype of clones and in the preservation of endangered breeds and species. (C) 1999 by Elsevier B.V.

A genômica funcional no âmbito da produção animal: estado da arte e perspectivas

Os últimos vinte anos caracterizaram-se pela proliferação de tecnologias que tornaram possível decifrar o genoma das espécies, localizar e identificar particularidades na sua seqüência, elucidar as suas funções dentro dos sistemas biológicos e, sobretudo, começar a entender os mecanismos que controlam as interações entre os genótipos e os estímulos ambientais, que são responsáveis pela diversidade fenotípica. Estes estudos sobre as bases moleculares da variabilidade fenotípica abriram uma nova abordagem científica, caracterizada pela multiplicidade das questões envolvidas, que resultou no surgimento de novas áreas de pesquisa, cujos conhecimentos estão sendo aplicados em diversos campos da biologia, inclusive na zootecnia. Tendo em vista o grande impacto que tais conhecimentos estão tendo sobre a compreensão dos fenômenos biológicos, parece ser oportuno fazer uma avaliação das potencialidades de aplicação das abordagens de Genômica Funcional em pesquisas de nutrição e alimentação de ruminantes. Nesse contexto, este artigo está focado na descrição das principais ferramentas genômicas disponíveis e na discussão sobre a viabilidade de se utilizar as informações por elas geradas em benefício da produção animal.

Critical points in logistic growth curves and treatment comparisons

Several biological phenomena have a behavior over time mathematically characterized by a strong increasing function in the early stages of development, then by a less pronounced growth, sometimes showing stability. The separation between these phases is very important to the researcher, since the maintenance of a less productive phase results in uneconomical activity. In this report we present methods of determining critical points in logistic functions that separate the early stages of growth from the asymptotic phase, with the aim of establishing a stopping critical point in the growth and on this basis determine differences in treatments. The logistic growth model is fitted to experimental data of imbibition of arariba seeds (Centrolobium tomentosum). To determine stopping critical points the following methods were used: i) accelerating growth function, ii) tangent at the inflection point, iii) segmented regression; iv) modified segmented regression; v) non-significant difference; and vi) non-significant difference by simulation. The analysis of variance of the abscissas and ordinates of the breakpoints was performed with the objective of comparing treatments and methods used to determine the critical points. The methods of segmented regression and of the tangent at the inflection point lead to early stopping points, in comparison with other methods, with proportions ordinate/asymptote lower than 0.90. The non-significant difference method by simulation had higher values of abscissas for stopping point, with an average proportion ordinate/asymptote equal to 0.986. An intermediate proportion of 0.908 was observed for the acceleration function method.

Bioethanol - Brazil, 30 years of Proálcool

Brazil, which has always been in the forefront of sugarcane production, also occupies a prominent position as the first country to produce and use biofuel in its automobile fleet. This fact is a consequence of the introduction of a program which has already turned 30 years, the Próalcool (National Alcohol Program). The oil crisis in the seventies encouraged the government to develop an alternative way to replace gasoline. Bioethanol was then born as fuel obtained from fermentation of sugarcane juice, molasses or both. In the eighties, 85% of the cars ran exclusively on alcohol. Ethanol production in that decade exceeded sugarcane production by the mills. The installed units reached in that period the capacity to produce 18 billion liters of bioethanol per season, a volume equivalent to 100 million barrels of gasoline. The fermentation process, which so far had been restricted to manufacturing sugarcane liquor (aguardente) or ethanol as a byproduct of sugarcane, takes over the spotlight in the entrepreneurial scene. As a result, processes comprising engineering concepts came up and most of the biological phenomena involved in fermentation were understood. The knowledge gathered and the units installed have granted Brazil the hold of production technology and use of a clean fuel.

Análise do desempenho da técnica de clonagem celular por micromanipulação versus diluição limitante

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ecologia populacional de Lucilia cuprina (Wiedemann, 1830) (Diptera, Calliphoridae): aspecto do desenvolvimento em diferentes densidades larvais e seus efeitos sobre os adultos resultantes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

O conceito de organismo: uma introdução à epistemologia do conhecimento biológico na formação de graduandos de biologia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Determinação de comunidades em redes biológicas integradas

To understand how biological phenomena emerge, the nonlinear interactions among the components envolved in these and the correspondent connected elements, like genes, proteins, etc., can be represented by a mathematical object called graph or network, where interacting elements are represented by edges connecting pairs of nodes. The analysis of various graph-related properties of biological networks has revealed many clues about biological processes. Among these properties, the community structure, i.e. groups of nodes densely connected among themselves, but sparsely connected to other groups, are important for identifying separable functional modules within biological systems for the comprehension of the high-level organization of the cell. Communities' detection can be performed by many algorithms, but most of them are based on the density of interactions among nodes of the same community. So far, the detection and analysis of network communities in biological networks have only been pursued for networks composed by one type of interaction (e.g. protein-protein interactions or metabolic interactions). Since a real biological network is simultaneously composed by protein-protein, metabolic and transcriptional regulatory interactions, it would be interesting to investigate how communities are organized in this type of network. For this purpose, we detected the communities in an integrated biological network of the Escherichia coli and Saccharomyces cerevisiae by using the Clique Percolation Method and we veri ed, by calculating the frequency of each type of interaction and its related entropy, if components of communities... (Complete abstract click electronic access below)

Migração e invasão celular in vitro de células humanas expressando variantes da oncoproteína LMP1 do vírus de Epstein-Barr (EBV)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Uma pesquisa didático-epistemológica na formação inicial em ciências biológicas: como a evolução forjou a grande quantidade de criaturas que habitam o nosso planeta?

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Biological effects of Ocimum gratissimum L. are due to synergic action among multiple compounds present in essential oil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

IMPORTANCE OF CONTROLLING THE STRESS IN THE VALIDATION OF BIOLOGICAL RESULTS

The stress syndrome includes ample phenomena, characterized by complex neuroendocrinological alterations. Such alterations, in the long run, give rise to important modifications in reply of different organs and tissues to diverse agonists, specially sympathicommentic. These alterations, at least partially, are part of an ''adjustment mechanism'' of the tissues. Thus this possibility of obtaining altered responses in function of stress leads to the need of special care in the prevention and control of stressogenic stimuli in the process of research. Taking cave of preventing stressogenic stimuli, it becomes possible to determine a profile of trustworthy replies, considered as standard From such reply standards, toe can know more clearly what is a ''normal'' response or what is a response ''altered'' by some factor, specially stress.

PEGylation of SPIONs by polycondensation reactions: A new strategy to improve colloidal stability in biological media

In this study, we report on a new route of PEGylation of superparamagnetic iron oxide nanoparticles (SPIONs) by polycondensation reaction with carboxylate groups. Structural and magnetic characterizations were performed by X-ray diffractometry (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM). The XRD confirmed the spinel structure with a crystallite average diameter in the range of 3.5-4.1 nm in good agreement with the average diameter obtained by TEM (4.60-4.97 nm). The TGA data indicate the presence of PEG attached onto the SPIONs' surface. The SPIONs were superparamagnetic at room temperature with saturation magnetization (M S) from 36.7 to 54.1 emu/g. The colloidal stability of citrate- and PEG-coated SPIONs was evaluated by means of dynamic light scattering measurements as a function of pH, ionic strength, and nature of dispersion media (phosphate buffer and cell culture media). Our findings demonstrated that the PEG polymer chain length plays a key role in the coagulation behavior of the Mag-PEG suspensions. The excellent colloidal stability under the extreme conditions we evaluated, such as high ionic strength, pH near the isoelectric point, and cell culture media, revealed that suspensions comprising PEG-coated SPION, with PEG of molecular weight 600 and above, present steric stabilization attributed to the polymer chains attached onto the surface of SPIONs. © 2013 Springer Science+Business Media Dordrecht.

Biological compatibility of some types of endodontic calcium hydroxide and glass ionomer cements

The purpose of this work was to evaluate the biological compatibility of the Sealapex, Apexit, Sealer 26 and Ketac Endo endodontic cements. Polyethylene tubes containing these cements were implanted in the subcutaneous tissue of 40 (forty) rats. The animals were sacrificed after 14 and 90 days. A descriptive analysis of the reactions found in the connective tissue by contact with the cements was performed. The magnitude of inflammatory infiltrate, the presence and predominance of cell types and their distribution as to the filling material and reparative phenomena, such as fibroblastic and angioblastic proliferation and formation of fibrous capsules, were subjectively measured. After 90 days, all cements presented statistically significant reduction of the inflammatory reaction, presence of a fibrous tissue capsule in contact with the opening of the tubes containing the filling materials, and reduction of fibroblastic proliferation. Angioblastic proliferation decreased only for the Sealer 26 and Ketac Endo groups. All cements tested were either partially or totally phagocyted, and the mildest inflammatory response was found for the Sealer 26 group at both evaluation periods.

Is the internal connection more efficient than external connection in mechanical, biological, and esthetical point of views? A systematic review

This systematic review aimed to evaluate if the internal connection is more efficient than the external connection and its associated influencing factors. A specific question was formulated according to the Population, Intervention, Control, and Outcome (PICO): Is internal connection more efficient than external connection in mechanical, biological, and esthetical point of views? An electronic search of the MEDLINE and the Web of Knowledge databases was performed for relevant studies published in English up to November 2013 by two independent reviewers. The keywords used in the search included a combination of dental implant and internal connection or Morse connection or external connection. Selected studies were randomized clinical trials, prospective or retrospective studies, and in vitro studies with a clear aim of investigating the internal and/or external implant connection use. From an initial screening yield of 674 articles, 64 potentially relevant articles were selected after an evaluation of their titles and abstracts. Full texts of these articles were obtained with 29 articles fulfilling the inclusion criteria. Morse taper connection has the best sealing ability. Concerning crestal bone loss, internal connections presented better results than external connections. The limitation of the present study was the absence of randomized clinical trials that investigated if the internal connection was more efficient than the external connection. The external and internal connections have different mechanical, biological, and esthetical characteristics. Besides all systems that show proper success rates and effectiveness, crestal bone level maintenance is more important around internal connections than external connections. The Morse taper connection seems to be more efficient concerning biological aspects, allowing lower bacterial leakage and bone loss in single implants, including aesthetic regions. Additionally, this connection type can be successfully indicated for fixed partial prostheses and overdenture planning, since it exhibits high mechanical stability.