Three studies were conducted to develop pollen tests for the screening of acetyl coenzyme-A carboxylase (ACCase) target-site resistance in a biotype of johnsongrass. The assays were based on germination of johnsongrass pollen in media supplemented with clethodim. Two different methods were used to evaluate pollen germination—a visual assessment and a spectrophotometric assay. The response of pollen to the germination media was linear for 16 h. At 6 h after treatment, absorbance at 500 nm was nearly 0.5; consequently, 6 h was chosen to conduct the pollen assays using the spectrophotometer. Both assessment methods differentiated the susceptible (S) and resistant (R) biotypes. Pollen from the susceptible biotype of johnsongrass was strongly inhibited by increasing concentrations of clethodim, with a GR50 of 25.8 ± 0.6 (SE) µM and GR50 of 16.4 ± 1.7 (SE) µM clethodim by visual assessment and spectrophotometric assessment, respectively. Minimum R/S values were > 3.9 by visual assessment and > 6.1 by spectrophotometric assessment. ACCase target-site resistance is expressed in johnsongrass pollen.

The underlying mechanism of predisposition to Ascaris infection is not yet understood but host genetics are thought to play a fundamental role. We investigated the association between the Intelectin-2 gene and resistance in F2 mice derived from mouse strains known to be susceptible and resistant to infection. Ascaris larvae were isolated from murine lungs and the number of copies of the Intelectin-2 gene was determined in F2 mice. Intelectin-2 gene copy number was not significantly linked to larval burden. In a pilot experiment, the response to infection in parental mice of both sexes was observed in order to address the suitablity of female F2 mice. No overall significant sex effect was detected. However, a divergence in resistance/susceptibility status was observed between male and, female hybrid offspring. The responsiveness to Ascaris in mice is likely to be controlled by multiple genes and, despite a unique absence from the susceptible C57BL/6j strain, the Intelectin-2 gene does not play a significant role in resistance. The observed intra-strain variation in larval burden requires further investigation but we hypothesize that it stems from social/dominance hierarchies created by the presence of female mice and possibly subsequent hormonal perturbations that modify the intensity of the immune response.

During this short period began what may be termed the re-exploration of northern Canada, a scientific examination of lands that had been roughly charted by expeditions of the previous hundred years, but that were otherwise little known except to fur traders, a few missionaries, and the occasional traveller. Only now did the newly confederated Dominion of Canada begin to take a practical interest in its vast northern expansions. The government sent three scientific expeditions to Hudson Strait and Hudson Bay, and the Geological Survey of Canada began to direct its attention towards the north. One of its officers, A. P. Low, explored the length and breadth of the Quebec-Labrador peninsula virtually single-handed and, as if anticipating the Klondike gold rush, towards which the work of many prospectors in Yukon Territory was steadily leading, Dawson, McConnell and Ogilvie published detailed accounts of routes and conditions in the Northwest Territories and Yukon Territory, information that proved invaluable to both government and individuals when the rush was on.

This second instalment of our list deals mainly with the competition between the French and English for domination of the fur trade in Hudson Bay. The period has been comparatively little studied and it has been difficult to piece out accurately and succinctly from the sources available the history of this lively period.

The Franklin Search continues through this instalment of our list, the main search culminating in the discovery by M'Clintock's expedition of the record that told of the Franklin expedition's success in finding a North-west Passage, of Franklin's death, and of the abandonment of his ships. Later, C. F. Hall and Frederick Schwatka discovered more bones and relics, which, however, added little to the bare outline of that tragic drama.

This instalment of our list is dominated by the search for Sir John Franklin's missing North-west Passage expedition (see 1845–48). The search began in 1847 and continued intensively until 1854, when Dr John Rae finally found the first clues regarding the fate of the expedition. An important feature of the search was the large number of sledge expeditions, which set out from the searching ships in spring. By this means, many thousands of kilometres of new coastline were discovered in a relatively short period, mainly during the spring months of 1851 and 1853, and much of the Canadian Arctic archipelago, which was largely unknown before 1850, was added to the map. In nearly every case, the sledges were man-hauled by an officer and six or seven seamen. We are listing all of the searches for Franklin, as we listed all North-west Passage expeditions, including some that did not touch Canadian shores.

If the Treaty of Paris in 1763 secured the Hudson's Bay Company in its monopoly of Rupert's Land, it also, by the Cession of Canada, opened to British enterprise the river-and-lake routes, discovered by the French, from Montreal to the fur-rich country west of Hudson Bay. This instalment of our list covers the years of the Montreal traders' expansion into the North-west, their crossing of the Arctic watershed into the fur trader's Eldorado, the Athabasca district, their organization into the Hudson's Bay Company's formidable rival, the North West Company, and concludes with the climax of their north-westward surge, Alexander Mackenzie's arrival at the Arctic Ocean in 1789. This activity obliged the Hudson's Bay Company to change its policy of waiting for the Indians to bring their furs to posts on Hudson Bay and made them push inland to compete for furs with the pedlars from Montreal. In the meantime, the Moravians had established missions on the coast of Labrador, searches for a North-west Passage were directed away from Hudson Bay to the Pacific coast of North America, the first scientific expedition was sent to Hudson Bay, and the Indians were decimated by smallpox. Toward the end of this instalment, we begin to draw our southern boundary of “northern Canada” both westward and northward and to omit many expeditions and events of peripheral or minor importance, such as activities south of Saskatchewan River, or of regular occurrence, such as annual voyages northward from Churchill.

With this instalment, we conclude our presentation of expeditions and historical events in northern Canada. Although we end here at about 1909, we have compiled the list up to 1920, a termination date chosen because the introduction of aircraft to northern Canada at about that time brought very many more persons into the region, and the list, to be continued after that date, would have to be conducted on different principles. We have presented these instalments in Polar Record as a means of preliminary publication, hoping that such appearance would elicit corrections and additions from readers before our work is published in full, not only with the entries seen in these pages, but also with an extensive roster of the names of persons associated with the expeditions described, a list of ships, a topical and regional index, and a supporting bibliography for each entry. Discussion is now going forward with officers of the Human History Division, National Museum of Man, Ottawa, the department that has financed this work, about full publication. We should like to take this opportunity to thank the National Museum of Man for its support, to acknowledge the permission of the Governor and Committee of the Hudson's Bay Company, whose archives we have used, to include hitherto unpublished dates and facts, and to say that we have greatly enjoyed the work of compiling this list and have especially enjoyed corresponding with the many persons who have written to us about it.

In this instalment of our list, we see that the Hudson's Bay Company, under the shrewd direction of its overseas governor, George Simpson, quickly recovered from its exhausting struggle with the North West Company and, strengthened by amalgamation with its rival in 1821, began vigorously to push into unknown country both west and east. In the east, the Ungava venture was an attempt, mainly unsuccessful, to develop a fur trade in the interior of the Quebec-Labrador peninsula. And in the west, the exertions of a few hardy men opened the fur-rich country of the Liard River and its tributaries, the Peel River and the region of the Mackenzie River delta, and crossed the Rocky Mountains to the upper drainage of the Yukon River.

The following pages, the beginning of a series, are the first results of a chronological compilation of expeditions and historical events that will eventually embrace the entire Arctic and sub-Arctic area. We began work on the Canadian segment of the Northern Hemisphere in 1968, with financial support from the History Division of the National Museum of Man, a part of the National Museums of Canada in Ottawa. The History Division is allowing this form of preliminary publication of the work it has supported in the expectation of securing corrections and additions to it, thereby enhancing the usefulness and authority of the list in its final form. The Canadian list, when it is published in full, will carry bibliographical references to each expedition and event, an alphabetical roster of persons known to have participated in the expeditions listed, a roster of ships' names, and a regional and topical index.

With this instalment of our list, the Klondike gold rush reached its height and, nearly as quickly, began to decline as the miners’ interest turned to newer strikes in Alaska. The great influx of prospectors to the Klondike region led to the passage of the Yukon Act and to the extension into the area of the enforcement of Canadian laws by the North West Mounted Police. In most other respects, the important trends noticed in the previous instalment continue: the officers of the Geological Survey of Canada and other scientists continued their careful and productive surveys; missionaries extended their efforts to remoter tribes; and sportsmen ranged still farther afield in search of big game. The number of expeditions each year steadily increased, and we are having to be increasingly selective in the ones we list. It has been impossible to include individual journeys to the Klondike, even of those persons who published narratives.

During the period covered by this instalment of our list, the accomplishments of the North West Company, both in geographical exploration and in the realization of profits were great. It consolidated its position in the fur-rich Athabasca district and, with a few posts along Mackenzie River, began to draw in the furs of that immense territory. Its traders invaded not only the western part of Rupert's Land but even Hudson Bay itself. The Hudson's Bay Company rose only slowly to the challenge of its formidable rival, but, gradually, it began to adopt new policies and new techniques and to meet the North West Company on its own grounds and on its own terms. Finally, after a bitter struggle that was almost the destruction of both companies, the Hudson's Bay Company, in 1821, effectively absorbed the North West Company in a coalition that gave the older company greater strength than ever and a wider monopoly than Prince Rupert had thought of.