Eighth Edition. Anthony J.F. Griffiths (U. of British Columbia). Susan R. Wessler ( U. of Georgia). Richard C. Lewontin (Harvard U.) William M. Gelbart (Harvard U.). Páginas de Griffiths - Introdução à Genética tronunbucambrin.cf Uploaded by Tiara Cabral . PDF FEITO PELA SSECP - UFRN - NATAL/RN. SKYSOFT SCAN . Páginas de Griffiths - Introdução à Genética tronunbucambrin.cf uploaded by. uploader avatar Tiara Cabral · A Review of Long-branch Attraction. uploaded by.
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The Genetic Approach to Biology. 2. Single-Gene Inheritance. 3. Independent Assortment of Genes. 4. Mapping Eukaryote Chromosomes by Recombination. 5. "Introduction to Genetic Analysis" is a college-level science textbook. The textbook presents in English language and is pages in length. Topics directly . Download Genetica 7ed - Griffiths-Suzuki, Et Al.
Sample information, species identification, average genetic distance, and results from the BLAST search. Amplification reactions were prepared with 0. PCR products were purified enzymatically using 0. DNA sequencing was performed on both strands using the primers mentioned above.
Data Analysis The consensus sequence for each sample was assembled and trimmed in Geneious 9. The reliability of each consensus sequence was assessed by a thorough visual inspection of the chromatograms used in the assemblies to check for sequencing errors and artifacts. Low quality regions in the chromatograms, identified as a stretch of five or more contiguous bases having high background noise and uneven spacing, were trimmed and removed before sequence assembly.
Because the assembly algorithm gives more weight to better quality reads, cases of sequence heterogeneity between strands are resolved in favor of the best quality read or, if both reads had similar quality for that position, marking it as an ambiguous base N, R, Y, etc.
We then picked at random 2—8 sequences for each species, which were aligned with the consensus sequences from the samples generated in this study using MAFFT 7. As a final quality control step, we checked the dataset for nonsense mutations and alignment gaps, as both could indicate the presence of nuclear mitochondrial translocations Numts Triant and DeWoody, The final alignment file can be downloaded as Supplementary Material File S1.
Node credibility was assessed based on 1, bootstrap replicates. Results In total, 63 samples were collected, amplified, sequenced, and compared to GenBank sequences Table 1. High quality sequences ranged between and bases. There was no sequence heterogeneity between strands involving high quality bases from two or more reads.
Overall, our analysis suggests the presence of 20 different species among the samples. Three ray species P. Based on COI sequences, all but one elasmobranch samples were identified at the species level, representing 17 formally described species.
All other species were far less common, including R. All ray species identified in the study occurred once or twice among the samples: G. The average genetic distance between each sample and representatives of its most likely candidate species determined by its clustering in the ML tree was always lower than 3. The ML tree showed cohesive clusters of conspecific sequences Figure 2. The few exceptions, which had bootstrap support values lower than 90, included S. In all cases, however, the estimated genetic distance between our samples and reference sequences were used to indicate the most likely candidate species shown in Table 1.
The complete distance matrix can be downloaded as Supplementary Material File S2. The miniature on the upper left side shows major groups, displayed in more detail in individual panels. The number of shark and ray symbols represent the number of different species identified in the study for each group. Please note that this is an unrooted tree.
Most entries were collapsed and the names were omitted for clarity. Samples from the present study are labeled according to Table 1. The most likely candidate species, together with other closely related species are shown in red. The numbers above the branches represent bootstrap percentage based on 1, replicates. Please note the different scale among panels. Other studies, based on other molecular markers, that aimed at species identification of shark filets from Northern Brazil have also shown the great number of species being trade without any taxonomic control Rodrigues-Filho et al.
Unfortunately, our DNA data does not allow us to conclude that these samples represent individuals captured in Southern Brazil.
For example, most individuals included in the final dataset did not have location information. Additionally, even if this was available, it is unclear whether COI would have enough resolution to allow unambiguous recognition of regional stocks for these species Antoniou and Magoulas, However, the fact that the vast majority of samples collected in this study were downloadd fresh is a strong indication that these specimens may have been captured off Southern Brazil or in nearby areas.
The use of the COI DNA barcode allowed us to identify all samples at the specific level even though some cases deserve further discussion. The best match for IIL26 was an undescribed or unsequenced species, Rajiformes sp.
In the case of the samples associated to Squatina, species identification was corroborated by the fact that both S. With a single exception, the species associated with the top-BLAST result also resulted in the lowest average genetic distance. The low genetic distance among Squalus species and the lack of a clear structure in the ML tree Figure 2 may indicate that DNA barcoding for this genus may be more complicated than for other genera, and may require other genetic markers.
From the taxonomic point of view, it is difficult to discriminate among Squalus species Haddad and Gadig, , which may be due to a shallow diversification time that is reflected in the low genetic distances among several species.
The inherently difficult taxonomy of the genus may favor misnomers in reference databases. In this regard, S.
However, while the entry FJ is close to S. The proportion dominant-recessive found by Mendel in that crossbreeding was an average of , that is, for example, regarding pea colors, for each three yellow peas, there was a green pea. In the second crossbreeding generation, Mendel obtains a proportion of Mendel, , p. From such conclusions, Mendel uses letters to illustrate his results. The next step Mendel took was to observe two characteristics for example, form and color of the seed at the same time, which allowed him to draw other statistic conclusions.
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According to Grifiths et al, reinterpreting Mendel at the light of contemporary genetics: 1. An hereditary factor called gene was necessary to produce pea color. Each plant has a pair of that kind of gene. Gene exists in two forms called alleles. The bar shows that the alleles are in a pair. In the meiosis, the members of a pair of genes equally separate into oocyte and spermatozoa.
Thus, one only gamete contains just one member of each pair. In fertilization, the gametes randomly merge, regardless which allele it brings emphasis in the original. The Austrian monk was not aware of the physical structure for the transmission of hereditary data. Along the end of the 19th century and the irst half of the 20th century, research on heredity was carried out, but the revolution is taking place with the discovery of the chemical structure of the genetic material.
By the discovery of the DNA deoxyribonucleic acid structure, the history of genetics was marked by the following moments: 1.
Genetica 7ed - Griffiths-Suzuki, Et Al. 2002
DNA is the genetic material. The year of is the revolutionary moment in which the North American geneticist James Watson and the British physician Francis Crick discovered the structure of DNA: They proposed a deinition for gene in chemical terms and, by doing that, they opened the path for the understanding of genic action and heredity at the molecular level [ Watson and Crick concluded that the DNA is a double helix consisting of nucleotide chromatids attached to one another.
DNA Structure — Source: www2. The chains double helixes are called ilaments and they are connected by a pair of bases A with T and G with C. Such structure allowed understanding over the following requirements of heredity: 1. The double helical structure suggests how the genetic material can deine the structure of proteins. The sequence of nucleotide pairs in the DNA may deine the sequence of amino acids in the protein speciied by that gene.
In other words, some kind of genetic code can write information in the DNA such as a sequence of nucleotides and, then, translate it into a different language of a sequence of amino acids in the protein. If the sequence of bases in the DNA speciies the sequence of amino acids, then it is possible to have a mutation due to the replacement of a kind of basis for another one in one or more positions [ Genes and, consequently, DNA are going to be the means by which hereditary characteristics are going to be transferred to individuals and later generations.
However, some recent theories and research have made the supposition that the DNA may be inluenced by the environment, allowing for some transformation, not to its structure. Those changes, which are going to be transmitted to later generations, are going to be called epigenetic mechanisms.
In the words of Michael K. Skinner, environmental Epigenetics may be described as follows: Environmental epigenetics therefore provides a molecular mechanism for the fetal basis of adult-onset disease, and will be crucial to a full understanding of disease aetiology. The interaction of epigenetic and genetic molecular events provides a more-powerful set of tools for the regulation of these processes.
The researches on the epigenetic mechanisms in the intergenerational transmission on the effects of stress have not been proved in human beings, but in animals.
The article tried to demonstrate that stress can be transmitted to other generations in humans. Animal models have demonstrated that stress-exposure can result in epigenetic alterations in the next generation, and such mechanisms have been hypothesized to underpin vulnerability to symptoms in offspring of trauma survivors YEHUDA et al, , p. One of the great problems in the scientiic literature is the fact that researchers have trouble in distinguishing what factors result from Epigenetic alterations and what factors result from childhood trauma or from life.
Besides, there are phenotypic changes in adults that manifest differently in offspring. The investigation encompassed Holocaust survivors and their irst generation offspring. Material was collected and certain symptoms were observed. FKBP5 is a protein encoder gene: Proteins are the main determiners of the biological form and function.
Those molecules inluence a lot the shape, color, size, behavior and physiology of the organisms. In other words, a protein is a chain of amino acids. Then, the same methylation was looked for in the irst offspring of holocaust to prove transmission between generations.
The research considered that Holocaust survivors were the ones locked in Nazi concentration camps and who had been tortured or seen torture, in addition to those who had to escape or hide during the war. The control group consisted of those who did not live in Europe during the Second War.
Offspring, in addition to being biological children, were those raised by their parents.
genetica basica griffiths pdf
Those who had serious diseases, psychosis, used steroids or were chemically dependent were excluded from the research. The study concluded that the same methylation changes in the FKBP5 gene happened to both Holocaust survivors and their offspring. That would be the result of Epigenetic changes.
The main inding in this study is that Holocaust survivors and their offspring have methylation changes on the same site in a functional intronic region of the FKBP5 gene, a GR binding sequence in intron 7, but in the opposite direction. To our knowledge, these results provide the irst demonstration of transmission of pre- conception stress effects resulting in epigenetic changes in both exposed parents and their offspring in adult humans.
Yet, it could be attributed to Holocaust exposure in the F0.
Yehuda et al suggest that other studies should be carried out with trauma survivors who were not pregnant yet and with people who were pregnant to check the causes of Epigenetic inluences.
They also suggest that the research is repeated with other populations that were subject to severe trauma. Animal models can provide further mechanistic understanding of how extreme stress effects mediate changes in offspring. The study ends up by suggesting that the researches should be deepened, besides saying that inding those Epigenetic marks can contribute for the prevention of problems related to intergenerational sequels.
Future studies should focus on assessing the effects of trauma at various developmental stages, as well as potential differences in maternal and paternal effects.
Additionally, the mechanism of intergenerational transmission of trauma and functional importance of site-speciicity remain to be explored. Early detection of such epigenetic marks may advance the development of preventive strategies to address the intergenerational sequelae of exposure to trauma. That means that experiences suffered by one generation can affect the future generations. The research illustrates how traumas in human beings can be transmitted to offspring through the Epigenetic heritage and not only through the social context.
Thus, as holocaust survivors are traumatized and that trauma is associated to a genetic marker, the same marker was found in their offspring and it also resulted in traumatized individuals. In the case herein, the ability to trauma is not originally in the DNA of survivors or their children, but it was associated to the marker that was connected to the DNA, which in survivors was connected to trauma experienced and, in their descendants, originated from genetic transmission.
The research detected the same Epigenetic marker in the Holocaust survivors and their children, which has not been detected in those who have not suffered the trauma of the Second World War.
Then, the transmission of the markers to the future generations would be a demonstration of how the environmental transformation of a current generation deeply interferes in the health of offspring.
However, science still has a long path ahead. It is yet not clear enough how markers are transmitted between generations and why some markers are passed on and others are not, but the research analyzed is strong evidence that an environmental experience in one generation is able to affect the behavior of the following generation.
There is still a lot to research and to understand, but it is already possible to notice that human responsibility over the environment and over living beings, may they be genetically similar or not, is stretching. It is also not possible to accept a restrictive Bioethics that only has biomedical assumptions, as if Medicine nowadays was able to do without transdisciplinarity to accomplish its main functions.
Accessed on: Mar. On the origin of Species. New York: D.
Appleton and Company, Accessed on: Nov. Rio de Janeiro: Guanabara Koogan, Experiments in Plant Hybridization Translated by William Bateson, p.
Rio de Janeiro: Lumen Juris, In the words of Michael K. A Windows program for the analysis of allozime and molecular population genetic data. As Mendel himself says, the experiment consisted in: Experience of artiicial fertilization, such as is effected with ornamental plants in order to obtain new variations in color, has led to the experiments which will here be discussed.
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Computer software distributed by the author. The inherently difficult taxonomy of the genus may favor misnomers in reference databases. DNA Structure — Source: www2.