Every student has a different mindset, or their own way of viewing challenges and setbacks. The purpose of this study was to determine the effectiveness of a specific feedback intervention on student mindset and achievement in a middle school life science course. Several tests were used to compare the data at the beginning of the school year and at the end of the school year. These tests included mindset, competency in science, attitudes about learning science, and life science content knowledge. The control group was taught by the use of lecture, note-taking, and life science activities. The experimental group was taught using the same instruction, and in addition the students participated in a mindset intervention involving specific, constructive feedback. The intervention was termed growth conferences. There were no significant differences in the pre versus post scores for mindset, competency in science, or attitude towards science. These data suggest that utilizing individual growth conferences for one semester in a middle school life science setting was not effective for creating significant changes in mindset, competency in science, attitude towards science, or life science content knowledge. The control groups GPA did decrease significantly from sixth to seventh grade, while the experimental groups GPA remained the same from sixth to seventh grade. When the gifted class data was removed from the control groups GPA there was not a significant difference from sixth to seventh grade. This indicated that the students in the control group, mainly the gifted students, needed a mindset intervention, and that the mindset intervention may have prevented the experimental groups GPA from decreasing over the year. There were also data to support that as mindset increased, so did life science content knowledge and performance. If the present study were to be repeated the intervention should be more frequent, perhaps a weekly group intervention, instead of individual conferences. This would allow for the students to experience the intervention for more time throughout one semester or a school year.

Self-regulation and self-efficacy are both necessary for students to be independent learners. During middle school, students begin to yearn for academic autonomy, but lack the ability to regulate themselves and are unreasonable about their abilities. Goals have been proven to promote the development of these two skills. The purpose of this investigation was to determine which type of performance goal most efficiently promotes the development of self-regulation. The effects of performance goal source were analyzed to determine if teacher-assigned or student assigned performance goals produce greater growth in content knowledge for seventh grade life science students. The effects of goal source on goal attainment, test-anxiety, and goal orientation were also measured. Goal source did have a significant effect on normalized learning gains (nLGs). Students with teacher-set goals consistently had higher nLGs compared to students with self-assigned goals, these differences being significant for two units. It was also found that teacher-assigned performance goals produce greater nLGs amongst white students and female students. For all four units, a positive correlation between unit goals and nLGs could be found for students with teacher-set goals, indicating that assigning students higher assigned goals produces greater gains. This relationship could not be established for students with self-assigned goals. The mean goal set by the teacher was significantly lower than the mean student-set goal for three units. In the final unit, the mean goal for both groups were not statistically different, indicating that students were beginning to grasp the concept of what is a realistic goal. Both groups experienced an increase in goal attainment over the course of study, however the rate of attainment was greater for students with teacher-set goals. Test anxiety did not significantly increase over the course of the study. An inverse relationship between test anxiety and nLGs was initially established for students with self-set goals, but not for students with teacher-assigned goals. By the end of the experiment, no relationship between anxiety and normalized learning gains could be established for either group. Additionally, it was found that anxiety was not related to goal attainment. These results demonstrate a shift in the control anxiety had over achievement through the use of goals. While there was no significant change in performance-goal orientation for either group over the course of the experiment, both groups experienced a significant drop in mastery-goal orientation by the end of the experiment, suggesting students were more interested in letter grades than truly mastering content. The findings of this study suggest that performance goals are more efficient with seventh grade science students if they are assigned. Furthermore, the use of performance goals within the classroom shows promise as a tool to develop students self-efficacy and self-regulation.

This study investigated the effect of traditional and electronic note taking on student achievement and engagement in a Louisiana high school biology classroom. Over a 20-week period, traditional students (n= 58) took notes using pencil and paper and electronic note takers (n=46) used their laptop computers. Each group of students was given identical pre and posttests covering three units and a practice End of Course exam. Normalized learning gains were compared for each unit and suggest there is no significant difference in academic achievement between the traditional note takers and the electronic note takers. An attitudinal survey was also administered and indicated that both electronic and traditional note takers preferred taking notes traditionally. Observations conducted by the teacher indicated a low occurrence of off task behavior; there were no significant differences between note taking groups. Results that were self-reported by the students show greater off task occurrences, especially within the electronic group. Teachers should carefully consider integrating technology into the note taking process. Since electronic note taking affects student engagement, but does not impact student achievement, allowing students the freedom to choose whichever method they prefer may positively impact classroom culture.

The firefly luciferase complementation assay is widely used as a bioluminescent reporter technology to detect protein-protein interactions in vitro and in vivo. Firefly luciferase oxidates its substrate, luciferin, resulting in the emission of light. A previous study suggests that the firefly luciferase complementation assay has different luminescence kinetics from full length luciferase. The mechanism behind this is still unknown. Although half of the previously published studies utilizing the firefly luciferase complementation assay consider it quantitative. To understand how the molecular reactions and the changes in the affinity of the protein pair affect experimental results, a mathematical model was constructed. This suggests that previously published studies should be considered qualitative, unless an additional experiment is performed. This new model demonstrates that the luminescence measured is not linearly correlated with the affinity of the protein pair. The model is then used to design a new experiment which allows the firefly luciferase complementation assay to be used quantitatively to detect changes of affinity.

The diversity of fishes in the Neotropics consists of nearly 6,000 species, approximately 10% of all vertebrate species on the planet. Evolutionary patterns and processes in fishes are often quite distinct from terrestrial biota, and the study of freshwater fishes can offer insight into understanding evolution and biogeography of regions. One of the major lineages of neotropical freshwater fishes, family Cichlidae, consist of over 500 species in the Neotropics but over 1,600 species overall. The aim of this study is to (1) assess diversification patterns within the family, with a focus on neotropical clades, (2) reassess phylogenetic relationships among northern Middle American cichlids and formally revise the taxonomy of this enigmatic group of fishes, and (3) assess phylogeographic structure within widespread Middle American fishes and begin exploring intrinsic capabilities that may influence our understanding of their biogeographic history. Results show that neotropical cichlids are relatively old in age and their diversity can be attributed to the age of the clade as opposed to an increase or decrease in rate of evolutionary diversification. For the northern Middle American herichthyin cichlids, a revised taxonomy of the group is offered based on robust taxonomic sampling and assessment of morphological characters to define genera. At a more exclusive taxonomic scale, phylogeographic structure is not observed for some lowland neotropical fishes in Middle America. Incorporation of physiological and behavioral data casts doubt on marine dispersal as the sole or primary mechanism of dispersal for these fishes. Overall results show the importance of an integrative approach to undertand the evolution and biogeography of freshwater fishes in the Neotropics.

In this study, the active learning technique think-pair-share was tested in an independent high school non-honors chemistry classroom to see if it was more effective than teaching techniques already being used in the chemistry classes. Two classes of tenth grade chemistry students were combined as a test group and a third class of tenth grade chemistry students acted as the control. Learning gains for pre and post-tests from three different chemistry units were analyzed and no significant difference was found between the results of the control and test groups, indicating that think-pair-share was as effective as teaching methods already in place. Power analysis indicated that results had a low chance of showing a significant difference between the learning gains for the two groups. An attitude survey given after the study was over indicated that students felt more comfortable in the classroom when cooperative learning techniques were employed.

Initiation of DNA Replication is a highly regulated process and is characterized by the conversion of inactive Mcm2-7 double hexamer around dsDNA to an active helicase consisting of Mcm2-7 single hexamer which encircles ssDNA along with Cdc45 and GINS. This transition of inactive Mcm2-7 around dsDNA to the active helicase around ssDNA involves several unknown mechanisms. Many proteins like, Sld2, Sld3, Dpb11, Mcm10, have been reported to be essential for replication initiation. Dpb11 is one of these essential proteins that functions in the initiation of DNA replication. Dpb11 binds to S-CDK phosphorylated Sld2 and Sld3 to form a ternary complex during S phase. These interactions are essential for the CDK-dependent activation of DNA replication in budding yeast. Studies have also indicated that chromosomal replication initiates by a fundamentally similar process in all eukaryotes, with Dpb11 being an evolutionary conserved protein. Our studies using purified proteins from budding yeast show that Dpb11 alone binds to Mcm2-7, and Dpb11 also competes with GINS for binding to Mcm2-7. Furthermore, Dpb11 binds directly to single-stranded DNA (ssDNA), and ssDNA inhibits Dpb11 interaction with Mcm2-7. We also found that Dpb11 can recruit Cdc45 to Mcm2-7. We identified a mutant of the BRCT4 motif of Dpb11 that remains bound to Mcm2-7 in the presence of ssDNA (dpb11-m1,m2,m3,m5), and this mutant exhibits a DNA replication defect when expressed in budding yeast cells. Expression of this mutant results in increased interaction between Dpb11 and Mcm2-7 during S phase, impaired GINS interaction with Mcm2-7 during S phase, and decreased RPA interaction with origin DNA during S phase. We propose a model wherein Dpb11 first recruits Cdc45 to Mcm2-7. Dpb11, while bound to Cdc45-Mcm2-7, can block the interaction between GINS and Mcm2-7. Upon the extrusion of ssDNA from the central channel of Mcm2-7, Dpb11 dissociates from Mcm2-7 and Dpb11 binds to ssDNA, thereby allowing GINS to bind to Cdc45-Mcm2-7. Finally, we propose that Dpb11 functions with Sld2 and Sld3 to help control the assembly of the replication fork helicase.

Graphic organizers have been used in the classroom since the late 1960s. Several studies have been published on the effects of graphic organizers on cognitive learning and yet the traditional method of teaching in the science classroom still remains strongly focused on traditional lecture and note taking. This study shows that relative to traditional methods graphic organizers maintain equivalent learning gains, but increase excitement and engagement among the students. The purpose of this study was to assess traditional lecture vs. traditional lecture with the addition of concept maps to determine if concept maps affect learning gains in the high school science classroom. The study used 86 traditional Biology students. The students were given both a pre-test and post-test on two separate units in the Biology curriculum. The first unit covered Charles Darwin and the theory of natural selection, while the second unit covered the muscular and skeletal systems. Although there was a slight increase in learning gains when concept maps were used, statistical analysis determined that this small increase was not significant for this sample size. There was a statistically significant difference in learning gains between the two units however. An attitudinal survey given at the end of the course showed that students preferred using the concept maps in addition to traditional lecture over traditional lecture alone.

The integration of reproduction and metabolism is necessary for the survival and continuation of a species. While the neural circuits controlling energy homeostasis have been well-characterized, the signals controlling the relay of nutritional information to the reproductive axis are not conclusively defined. The cichlid fish Astatotilapia burtoni is ideal for studying the neural regulation of feeding and reproduction because during their parental care phase, females undergo a two-week period of forced starvation while holding developing young in their buccal cavity. To test the hypothesis that candidate neuropeptides known to be involved in feeding and energy homeostasis in mammals show conserved distribution patterns, we performed immunohistochemistry or in situ hybridization to localize appetite-stimulating (neuropeptide Y, NPY; agouti-related protein, AgRP) and appetite-inhibiting peptides (cocaine and amphetamine-regulated transcript, CART; pro-opiomelanocortin, POMC) in the cichlid fish brain. NPY, AgRP, CART, and pomc somata were localized to the lateral tuberal nucleus (NLT), the putative homolog of the arcuate nucleus, as well as other brain regions, and fiber distributions were similar to other teleosts as well as to mammals. To test whether conserved neuropeptide-containing neurons varied with reproductive state, we also quantified neuron somata size in the NLT as a proxy for their involvement in regulating changes in energy status and reproductive condition. Our results show that gravid females had larger NPY and AgRP neurons in the NLT compared to brooding females, but brooding females had larger POMC neurons compared to gravid females. CART neuron size did not differ between the two reproductive states. Thus, larger appetite-stimulating neurons (NPY, AgRP) likely promote feeding while females are gravid, while larger POMC neurons may act as a satiety signal to inhibit food intake during mouthbrooding. Hypothalamic mRNA levels for npy, agrp, pomc-α, cart 2 and cart 4 were also measured, and while AgRP mRNA levels were higher in gravid compared to brooding females, the remaining gene products did not differ between reproductive states. Collectively, however, our data suggest a potential role for NPY, AgRP, POMC and CART in regulating food intake in A. burtoni females during varying reproductive states.

Iron-sulfur proteins comprise one of the most ubiquitous and conserved classes of proteins in biology. The diverse functions of iron-sulfur clusters in proteins range from electron transfer to redox signaling. The assembly of iron-sulfur clusters in cells requires a complex protein system and acquisition of sulfur and iron. While the sulfur source for iron-sulfur cluster assembly is well-established, the iron source remains elusive. The first part of this work provides new evidence for the hypothesis that the conserved iron-sulfur cluster assembly protein IscA may act as the iron donor for iron-sulfur cluster assembly. Iron-sulfur clusters in proteins are also vulnerable to reactive oxygen and nitrogen species. Indeed, iron-sulfur clusters in proteins can be readily destroyed by nitric oxide (NO) forming protein-bound dinitrosyl iron complexes (DNICs). The second part of this work demonstrates that iron-sulfur proteins are the major source of protein-bound DNICs found in NO-exposed cells. The results reveal new aspects of the molecular mechanism underlying NO cytotoxicity. As dysfunction of iron-sulfur clusters has been implicated in several human diseases, two human iron-sulfur proteins have been chosen for functional investigation of their iron-sulfur clusters. The first example is Rtel1, a DNA helicase that regulates telomere length. Rtel1 was predicted to contain an iron-sulfur cluster, but this was not demonstrated. The third part of this work shows that the N-terminal domain of Rtel1 indeed contains a redox active [4Fe-4S] cluster. The second example is the mitochondrial outer membrane protein mitoNEET, a recently identified target of the type II diabetes drug pioglitazone. The studies show that mitoNEET [2Fe-2S] clusters can be readily reduced by biological thiols and human glutathione reductase, and is reversibly oxidized by hydrogen peroxide, suggesting that mitoNEET may undergo redox transitions to regulate mitochondrial energy metabolism in response to oxidative stress. In summary, the research presented in this dissertation advances our understanding of how iron-sulfur clusters may be assembled and how NO modification of iron-sulfur proteins may contribute to NO cytotoxicity. The human iron-sulfur proteins Rtel1 and mitoNEET further illustrate how iron-sulfur clusters may modulate protein functions via redox transition of their iron-sulfur clusters in response to oxidative signals.