Drafts

Food webs are conceptual models of trophic interactions of organisms. Food webs can be simple or complex and sued for a variety of purposes. Food webs are typically more complex because more species are involved. As models they are limited in that they are static, don’t account for population fluctuations, competition, facilitation, mutualisms, etc. They can be used to better understand energy flows, if we know something about interaction strengths. Robert Paine studied an intertidal food web to study the effects removing the starfish from the ecosystem so see its effect on local diversity. The starfish is a top predator that promotes species diversity by preventing competitive exclusion by the mussels. This makes it an excellent example of a keystone predator.

Another good SNP  identified is rs9264942(C;T), which has implications in HIV viral load. The viral load is the quantity of a virus in a given volume, and the set point is the viral load reached after the immune system begins to attempt to fight the virus. This genetic link to a reduced viral load means that The C/C genotype has the most significant impact, as its correlated with a 90% reduction in viral load compared to other polymorphisms, however the C/T variation identified in this individual is associated with a 60% reduction in HIV viral load. It also reportedly accounts for 6.5% of the 15% variation in the viral load set point in HIV infected individuals who are asymptomatic, and can also be associated with a reduced viral load set point in HIV. This means that should this individual contract HIV, they will likely have a lower viral load than individuals without the variation.

Of the SNPs analyzed in the Promethease report, 55.94% were good, 0.97% were bad, and 43.09% were not set. Of the good SNPs, one identified was rs7294919, which shows a fairly strong link to a reduced volume of the hippocampus. The hippocampus is a structure in the brain that is critically involved in learning and memory, particularly associated with the ability to form long-term memories. It shrinks with age, and its size is diminished in disorders such as Alzheimer’s. The decrease in hippocampal size is associated with the T allele, each copy of which is associated with a 107.8 mm3 decrease, while the C allele has a connection to a moderate increase in hippocampal volume. This individual has the C/T variation, which means that there is a less reduced hippocampal volume.

The poster is informative with three patient examples. Each example includes the age and gender of the patient as well as the tests run and the results found, both through images of the brain and corresponding graphs. Specific lines on the graphs that correspond to different regions of the brain are highlighted in the same color for easier visualization. There is no raw data and graphs are clean. Each example is located in the same region of the poster to allow for comparison across patients. However, there are no statistics on the results present. Overall, this poster is persuasive, clean, and succinct.

AT1g61610 was found to have a Zinniacysteine protease 4 (ZCP4) promoter cis-element-like sequence 1000 b.p. upstream, and the ZCP4 promoter governs tracheary element differentiation (Pyo et al. 2007). The presence of this cis-element-like sequence implicates AT1g61610 in the development of xylem, although nothing further is known to this end. Xylem are the vesicles in plants that transport water up from the roots to the leaves. The development of xylem includes lignification and secondary cell wall formation.

Early work on gene structure was carried out largely through the examination of mutations in bacteria and viruses. This research led Francis Crick to propose in 1958 that genes and proteins are colinear, that there is a direct correspondence between the nucleotide sequence of DNA and the amino acid sequence of a protein. The concept of colinearity suggests that the number of nucleotides in a gene should be proportional to the number of amino acids in the protein encoded by that gene. In a general sense, this concept is true for genes found in bacterial cells and in many viruses, although these genes are slightly longer than would be expected if colinearity were strictly applied because the mRNAs encoded by the genes contain sequences at their ends that do not specify amino acids. At first, eukaryotic genes and proteins were also assumed to be colinear, but there were hints that eukaryotic gene structure is fundamentally different. Eukaryotic cells were found to contain far more DNA than is required to encode proteins. Furthermore, many large RNA molecules observed in the nucleus were absent from the cytoplasm, suggesting that nuclear RNAs undergo some type of change before they are exported to the cytoplasm.

The ribosome is one of the most abundant molecular complexes in the cell: a single bacterial cell may contain as many as 20,000 ribosomes, and eukaryotic cells possess even more. Ribosomes typically contain about 80% of the total cellular RNA. They are complex structures, each consisting of more than 50 different proteins and RNA molecules. A functional ribosome consists of two subunits, a large ribosomal subunit, and a small ribosomal subunit, each of which consists of one or more RNA molecules and a number of proteins. The sizes of the ribosomes and their RNA components are given in Svedberg (S) units (a measure of how rapidly an object sediments in a centrifugal field). (It is important to note that S units are not additive: combining a 10S structure and a 20S structure does not necessarily produce a 30S structure because the sedimentation rate is affected by the three-dimensional structure of an object as well as by its mass). The three-dimensional structure of the bacterial ribosome has been elucidated in great detail through X-ray crystallography.

This poster includes the following sections: “Introduction,” “Methods,” “Results,” three sections of “Example Patients,” “Conclusions,” and “References & Acknowledgments.” These sections are presented in this order on three panels of the poster, reading left to right across the poster and vertically in each panel. This gives the poster a smooth flow and as a result, information regarding each section is easy to find. Within each section, the most important information is in bold and following information is presented in truncated language. Writing for the poster is in bullet point format and is direct. There are no grammatical, spelling, or typographical errors, however, conventions are slightly different as this poster is from the United Kingdom. Language is appropriate for scientific writing. In a clinical setting, this poster is structured to be as clear as possible. Images with colorful labeling aids in this process and conclusions are summarized in three short bullets.

A major extinction, the Kellwasser event marked the beginning of the last phase of the Devonian period, the Famennian faunal stage about 375-360 million years ago. A second mass extinction, the Hangenberg event, closed the Devonian period. It is still unclear as to the extent of time during these extinctions, as it is uncertain whether there were two sharp mass extinctions or a series of smaller extinctions. By the late devonian, land had been colonized by plants and insects, and the oceans were massive reefs built by corals and stromatoporoids. The extinction for the most part hit marine life. Euramerica and Gondwana were beginning to converge into what would become Pangea.