The purpose of this study was to better understand the molecular mechanisms that control hindlimb reduction or absence during vertebrate evolution. The reduction or absence of hindlimbs has evolved in many different species such as reptiles, marine mammals, fish and amphibians. However, for this study the fish species known as the threespine stickleback species was focused on. Within this species the marine stickleback has a pelvis region where as the benthic stickleback does not. In order to analyze the molecular mechanisms at hand the scientists conducting this experiment carried out genetic crosses between threespine stickleback fish with complete or missing pelvic structures. This allowed the scientists to be able to identify the general …show more content…
Through this they were able to find, as is seen in figure 1.A of the report, that one gene in particular, the Pitx1 gene was highly correlated to the pelvic spine, pelvic girdle, ascending branch and asymmetry in the Stickleback species. Thus, in other words showing that there was a tight linkage between Pitx1 and the pelvic reduction phenotype. The next step for the scientists was then to determine whether or not there were any changes in the coding region of the Pitx1 gene between the marine and benthic stickleback species. In order to do this the entire coding region and exon-intron junctions in both marine and benthic individuals were sequenced. The results, which can be seen in figure 2 of the report, showed that the coding regions of Pitx1 were the same for both stickleback species. Thus, implying that the absence or presence of the pelvic region must be controlled through regulation of the Pitx1 gene. In order to test this the scientists examined the spatial patterns of expression of Pitx1 during normal development of both marine and benthic …show more content…
The reason why I believe figure 2 to be so pertinent to the results is because it shows that there is no mutation of Pitx1 in either the benthic or marine species that affects pelvic development (figure 2). Figure 3, is pertinent to the results because it takes this one step farther and actually shows that indeed the only difference between species that have a pelvic region and have an absence of a pelvic region is due to the regulation of the Pitx1 gene. I believe that the experimental data supports the conclusion of this paper because as I previously explained the results show that there is a major chromosome region that is controlling the presence or absence of pelvic structures. The results also show that there is no actual mutation within the Pitx1 gene between the different stickleback species. Not only that but the strong directional asymmetry seen in pelvic-reduced fish and the altered pattern of Pitx1 gene expression during development also goes to support the conclusion that there is a regulatory mutation. This regulatory mutation is thus responsible for the lack of Pitx1 gene in the benthic stickleback, which results in pelvic reduction and is most likely a cis-acting regulation
This experiment designed to analyze the phylogenetic of four unknown different fish muscles samples in order to predict the type of the aquatic creature. In this study, actin and myosin proteins were analyzed on account of their fairly high and constant expression in the animal muscles. Since the actin and myosin proteins are the two major...
The background of this article gives information that is necessary to understand the experiment. The shape of the pelvic girdle is an appropriate predictor of both phylogeny and movement in terrestrial vertebrates. However, in marine vertebrates, the gravitational forces typically applied to terrestrial pelvic girdles are not there and therefore have little impact on the shape of the girdle. Pelvic girdles of fish are generally not attached to the vertebrae and primarily are used as a place for muscles to attach and supporting of the fins. The authors discuss how in many cases the pelvic girdle could be removed and not result in any complications. However, there are some marine vertebrates that are capable of bottom walking on the ocean floor with their fins. In batoids, the pelvic fins are used for walking, which is when pelvic fins move in an alternating fashion, or punting, when both pelvic fins move at the same time. There is also augmented punting; this is when the vertebrate uses both the pectoral fins and the pelvic fins to generate more thrust, this action decreases the forces on the pelvic fins during a punt. While this locomotion would
The evolution of the human species has significantly changed during the course of evolution to what is now the modern day Homo sapiens. Some of the changes that have occurred through the evolution are bipedalism, changes in body features such as brow ridges, and an increase in brain capacity.
The origin of modern day whales, a mystery that has puzzled paleontologists for years, may have just been solved with the discovery of an ankle bone. This discovery might sound simple and unimportant, but the bones of these ancient animals hold many unanswered questions and provide solid proof of origin and behavior. The relationship between whales and other animals has proven to be difficult because whales are warm-blooded, like humans, yet they live in the sea. The fact that they are warm-blooded suggests that they are related to some type of land animal. However, the questions of exactly which animal, and how whales evolved from land to water, have remained unanswered until now.
EGFP is a powerful reporter molecule for monitoring gene expression, protein localization and protein-point interaction. Through the use of EGFP, the scientists were able to see what areas of embryonic development this intergenic region of the Pitx1 was correlated with. Therefore, EGFP will be visibly expressed in areas within the intergenic region of the Pitx1 gene as well as within any of the developing embryonic regions that it is correlated with. Seeing that the only region where EGFP was consistently expressed was in the hindfin area, the scientists concluded that the non-coding region upstream of Pitx1 contained a tissue-specific enhancer for hindfin expression. Again, supporting their hypothesis that indeed Pitx1, and no other genes in the larger chromosome region, is the real cause of pelvic loss in sticklebacks. This region, which the scientists termed as “Pel” was then cloned and injected into unfertilized eggs of pelvic-reduced fish. The scientists did this in order to see if the region is a major determinant of pelvic formation in sticklebacks, which it ended up
The great debate over how the head segments of existing arthropods are aligned was largely dispelled in the late 1990s when the expression domains of Hox genes were first applied to the study of Arthropod evolution. The traditional concept that chelicerates had lost a deuto cerebral segment and that the chelicerae was innervated by the tritocerebrum was overturned when the anterior expression domain of labial, the anteriormost gene of the arthropod Hox cluster, was found to align the chelicerae with the first antenna of mandibulates (Edgecombe and Legg 2014). This alignment of the head was later confirmed by resemblances in the developing nervous systems of Limulus and crustaceans and is now widely supported by scientists. Another study that
Fox, R. 2001. Invertebrate Anatomy OnLine: Artemia Franciscana. Lander University. http://webs.lander.edu/rsfox/invertebrates/artemia.html, retrieved February 13, 2011.
Unlike other balaenopterids, M.novaenglae relies heavily on maneuverability when capturing prey and their pectoral flippers allow them to be highly maneuverable (Wiley et al. 2011). Their pectoral flippers are the longest of any cetacean which vary in length from one fourth to one third the total body length (Wiley et al. 2011). These flippers compared to other species of whale, are also highly mobile at the shoulder and possess some flexibility along the length (Wiley et al. 2011). Also, on the leading edge of the flippers, occurring early in young fetuses, are formations of 9 to 11 tubercles, which decrease in size toward the tip of the flipper (Wiley et al. 2011). The combination of the high flipper length to body ratio plus the presence of the tubercles, which prevent stall at high angles of attack, provide high lift and drag characteristics which allow humpbacks to execute sharp, high-speed turns during predation (Wiley et al. 2011).
Koopman P, Gubbay J, Vivian N, Goodfellow P, Lovell-Badge R. Male development of chromosomally female mice transgenic for Sry. Nature. 1991;351:117–121
Sharpe, Paul T. "Fish Scale Development: Hair Today, Teeth and Scales Yesterday?" Current Biology 11, no. 18 (2001): R751-752. Accessed November 28, 2015. http://www.sciencedirect.com/science/article/pii/S0960982201004389.
M Dufrasne, I. M. (2013). Journal of Animal Science. Animal Genetics , Volume 91 (12).
After researching so many things that I never even knew about reptiles, I believe I would much rather be a reptile instead of an amphibian. Reptiles were able to adapt to land while amphibians can barely even stay away from water for long periods of time. After all these years reptiles have evolved to modern day qualities and are still evolving to fit in. This paper is important to people who want to learn a little history about reptiles. It also tells what changes occurred in reptiles as they evolved.
...racterized. Thus, the characterization of transferrin protein in L. calcarifer will lead to the glycoprotein function identification in fish biology system hence give a picture of this protein’s evolution and distribution through the vertebrate species. In this study, a cDNA sequence encoding the transferrin of the Asian seabass (Lates calcarifer) was identified and analyzed using in silico approaches to predict and characterize its functions. The study of teleost fish proteins is important as there are a very limited number of sequences of this fish available in the database thus limiting the study of this group of fishes. With the ongoing efforts to identify new genes in teleost fish, it is hoped that such study will increase the number of fish genes available in public databases and consequently facilitate the community involved in fish research in their study.
Evolution is the complexity of processes by which living organisms established on earth and have been expanded and modified through theorized changes in form and function. Human evolution is the biological and cultural development of the species Homo sapiens sapiens, or human beings. Humans evolved from apes because of their similarities. This can be shown in the evidence that humans had a decrease in the size of the face and teeth that evolved. Early humans are classified in ten different types of families.
Regeneration is the ability of an organism to grow a body part that has been lost. Regeneration happens to reconstruct external parts and internal organs that are often exposed to predators or amputation. Amputation can be self-induced or traumatic and these lost parts are than complete regrown rapidly. It can also be seen as a conservative asexual process. This is because it is so close in relation to fission, or the division, and cloning processes that regeneration can be seen as a necessary and specific developmental accompaniment to asexual reproduction. It is a common and widespread natural phenomenon. It is a physiological phenomenon in echinoderms (i.e. starfish, brittlestars, etc.) common in all classes. Regeneration is found throughout the phylum of echinoderms and forms an integral part of their adaptive repertoire. Much like in asteroid regeneration not only does repair but also allows for asexual reproduction. Because echinoderms are so skilled at this process they were one of the favorite models for pioneer regenerationists of the 19th and early 20th centuries. The capability for starfish to regenerate depends on the individual; as well as how capable they are for histogenetic and morphogenetic plasticity expressions. The ability to do this self-repair not only is an advantage for the individual but it also hel...