Endosymbiosis and Eukaryotic Cell Evolution

Understanding the evolution of eukaryotic cellular complexity is one of the grand challenges of modern biology. It has now been firmly established that mitochondria and plastids, the classical membrane-bound organelles of eukaryotic cells, evolved from bacteria by endosymbiosis. In the case of mitochondria, evidence points very clearly to an endosymbiont of α-proteobacterial ancestry. The precise nature of the host cell that partnered with this endosymbiont is, however, very much an open question. And while the host for the cyanobacterial progenitor of the plastid was undoubtedly a fully-fledged eukaryote, how — and how often — plastids moved from one eukaryote to another during algal diversification is vigorously debated. In this article I frame modern views on endosymbiotic theory in a historical context, highlighting the transformative role DNA sequencing played in solving early problems in eukaryotic cell evolution, and posing key unanswered questions emerging from the age of comparative genomics

Meiotic and Mitotic Chromosomes of \u3cem\u3eFritillaria atropurpurea\u3c/em\u3e Nutt.

The purpose of this paper is to provide information concerning the number, structure, and behavior of chromosomes in the plant species Fritillaria atropurpurea. The material used for this investigation included both floral buds and root-tips from actively growing naturally occurring plants collected from populations in both Utah and Nevada, and root-tips from seed germinated in the greenhouse. The results obtained include a karyotype analysis of mitotic chromosomes, a discussion of meiosis, a discussion of B-chromosomes, and a series of photographs depicting the stages of mitosis and meiosis in this species. Fritillaria atropurpurea has a diploid chromosome number of 24, plus from zero to two B-chromosomes. Two pair of chromosomes have median centromeres while the other ten pair have sub-terminal to terminal centromeres. Two pair have secondary constrictions and satellites. The length of the chromosomes in colchicine treated material ranges from 12.64 to 19.11 microns, with a width of 2.50 microns. During meiosis, pairing is about 95% complete, and an average of 2.50 chiasmata are formed per bivalent, with no localization of chiasmata observed. There is negligible terminalization between diplotene and anaphase I. Mitosis in this species is regular

Alien Registration- Archibald, John D. (Monticello, Aroostook County)

https://digitalmaine.com/alien_docs/34222/thumbnail.jp

Municipal Crisis in Ohio

On June 26th, 1902, the supreme court of Ohio rendered three decisions which precipitated a crisis in municipal affairs in that state. For, by these decisions, the court virtually overruled a long line of precedents, and laid down a principle under which scarcely a city in the state possessed a constitutional government. In consequence, the legislature was summoned in extraordinary session to enact a new municipal code for all the cities and villages in the state. The situation was unparalleled, even in American history; and the task before the general assembly was doubtless the most important single act ofmlnicip,- 1,egislati_u that has comeibefore an American legislatur.. An -eramination of the steps leading to the present situation, an& -of the -tireasures taken to solve the difficulties should be of interest and significance

Geology and Ore Deposits of the Golden Messenger MIne, Lewis and Clark County, Helena, Montana.

The Golden Messenger Mine which is approximately twenty-three miles northeast of Helena, Montana, near York, on Trout Creek, has long presented several problems of both theoretical and practical interest