The effect of the integration of science teaching by television on the development of scientific reasoning in the fifth grade student

Thesis (Ed.D.)--Boston University

Beyond The Butcher\u27s Block: The Animal Landscapes of Eighteenth-Century Chesapeake and Lowcountry Plantations

This dissertation argues that working oxen, horses, and mules contributed to the physical and social landscapes of eighteenth-century plantations in the Chesapeake and the Lowcountry. This research embraces an animal landscape approach, exploring how humans and animals were both active agents in shaping animal husbandry strategies, social interactions, and power negotiations on plantations. This exploration utilized archaeological and historical sources, predominately faunal assemblages from Oxon Hill Manor, Maryland, Mount Vernon, Virginia, Drayton Hall, South Carolina, and Stobo Plantation, South Carolina; articulated equine skeletons from Jamestown Island, Virginia, and Yorktown, Virginia; and probate inventories from plantations within the eighteenth-century Upper Chesapeake and Lowcountry. Working oxen and equines were identified from the archaeological record through pathological and osteometric analyses. Probate inventories supplied complementary information on the number of working oxen and equines in each region and the types of labors these animals performed. In the eighteenth-century Chesapeake, laboring oxen and equines were essential to the plowing and carting required by the shift from tobacco to mixed grain production. Working livestock were husbanded in a manner which relied on producing excess grains which could then be fed to the livestock. In the eighteenth-century Lowcountry, oxen were used sporadically throughout the region to ready fields or to cart products. Horses in the Lowcountry were essential to personal transportation, as many wealthy planters frequently travelled between their multiple estates. Compared to the Chesapeake, livestock in the Lowcountry was husbanded in a more passive manner; working animals were corralled while some of the non-working livestock ranged freely in the woodlands in their natural herd structures. In both regions, interactions between humans and animals combined with the physicality of the plantations to create landscapes of domination and resistance. In the Chesapeake, planters depended on working livestock to increase their wealth and to symbolize that wealth to others. In the Lowcountry, livestock represented large landholdings, and planters used horses to symbolize their mobility and active involvement in those landholdings. In both regions, enslaved laborers relied on working livestock to increase their mobility and their standing within the enslaved community. Additionally, enslaved individuals worked with animals to subvert the social order of the day through active and passive revolt. Rather than being static members in the background of human activity, working oxen and equines actively contributed to the economic, cultural, and social spheres of eighteenth-century plantation life

Targeting of the master receptor MOM19 to mitochondria

The targeting of proteins to mitochondria involves the recognition of the precursor proteins by receptors on the mitochondrial surface followed by insertion of the precursors into the outer membrane at the general insertion site GIP. Most mitochondrial proteins analyzed so far use a mitochondrial outer membrane protein of 19 kilodaltons (MOM19) as an import receptor. The gene encoding MOM19 has now been isolated. The deduced amino acid sequence predicts that MOM19 is anchored in the outer membrane by an NH2-terminal hydrophobic sequence, while the rest of the protein forms a hydrophilic domain exposed to the cytosol. MOM19 was targeted to the mitochondria via a pathway that is independent of protease-accessible surface receptors and controlled by direct assembly of the MOM19 precursor with GIP

Import of ADP/ATP carrier into mitochondria

We have identified the yeast homologue of Neurospora crassa MOM72, the mitochondrial import receptor for the ADP/ATP carrier (AAC), by functional studies and by cDNA sequencing. Mitochondria of a yeast mutant in which the gene for MOM72 was disrupted were impaired in specific binding and import of AAC. Unexpectedly, we found a residual, yet significant import of AAC into mitochondria lacking MOM72 that occurred via the receptor MOM19. We conclude that both MOM72 and MOM19 can direct AAC into mitochondria, albeit with different efficiency. Moreover, the precursor of MOM72 apparently does not require a positively charged sequence at the extreme amino terminus for targeting to mitochondria

Identification of the mitochondrial receptor complex in Saccharomyces cerevisiae

Mitochondrial protein import involves the recognition of preproteins by receptors and their subsequent translocation across the outer membrane. In Neurospora crassa, the two import receptors, MOM19 and MOM72, were found in a complex with the general insertion protein, GIP (formed by MOM7, MOM8, MOM30 and MOM38) and MOM22. We isolated a complex out of S. cerevisiae mitochondria consisting of MOM38/ISP42, the receptor MOM72, and five new yeast proteins, the putative equivalents of N. crassa MOM7, MOM8, MOM19, MOM22 and MOM30. A receptor complex isolated out of yeast cells transformed with N. crassa MOM19 contained the N. crassa master receptor in addition to the yeast proteins. This demonstrates that the yeast complex is functional, and provides strong evidence that we also have identified the yeast MOM19

Tom40, the Pore-Forming Component of the Protein-Conducting Tom Channel in the Outer Membrane of Mitochondria

Tom40 is the main component of the preprotein translocase of the outer membrane of mitochondria (TOM complex). We have isolated Tom40 of Neurospora crassa by removing the receptor Tom22 and the small Tom components Tom6 and Tom7 from the purified TOM core complex. Tom40 is organized in a high molecular mass complex of ∼350 kD. It forms a high conductance channel. Mitochondrial presequence peptides interact specifically with Tom40 reconstituted into planar lipid membranes and decrease the ion flow through the pores in a voltage-dependent manner. The secondary structure of Tom40 comprises ∼31% β-sheet, 22% α-helix, and 47% remaining structure as determined by circular dichroism measurements and Fourier transform infrared spectroscopy. Electron microscopy of purified Tom40 revealed particles primarily with one center of stain accumulation. They presumably represent an open pore with a diameter of ∼2.5 nm, similar to the pores found in the TOM complex. Thus, Tom40 is the core element of the TOM translocase; it forms the protein-conducting channel in an oligomeric assembly

Mitochondrial Lysyl-tRNA Synthetase Independent Import of tRNA Lysine into Yeast Mitochondria

Aminoacyl tRNA synthetases play a central role in protein synthesis by charging tRNAs with amino acids. Yeast mitochondrial lysyl tRNA synthetase (Msk1), in addition to the aminoacylation of mitochondrial tRNA, also functions as a chaperone to facilitate the import of cytosolic lysyl tRNA. In this report, we show that human mitochondrial Kars (lysyl tRNA synthetase) can complement the growth defect associated with the loss of yeast Msk1 and can additionally facilitate the in vitro import of tRNA into mitochondria. Surprisingly, the import of lysyl tRNA can occur independent of Msk1 in vivo. This suggests that an alternative mechanism is present for the import of lysyl tRNA in yeast