Trends in fish prey capture by common terns following zebra mussel invasion : do terns track fish species abundance? /

The Common Tern (Sterna hirundo) is a ground nesting colonial seabird. Terns rely primarily on small prey fishes which they obtain through plunge diving for their survival as well as the survival of their offspring during the breeding season. The zebra mussel (Dreissena polymorpha) is a small bivalve mollusk that invaded North American waters in the late 1980's. Through its suspension feeding, the zebra mussel has the ability to alter the entire aquatic ecosystem, ultimately leading to a reduction in pelagic organisms including small prey fish. The objective of the study was to determine what (if any) indirect effects the invasion of the zebra mussel has had on fish prey captured by terns. The study took place in two separate two-year periods, 1990-91 and 1995-96 on a concrete breakwall off the north shore of Lake Erie near Port Colborne, Ontario. Daily nest checks revealed clutch initiation dates, egg-laying chronology, hatching success and morphological egg characteristics (length and breadth). Behavioural observations included time each sex spent in attendance with its brood, the frequency of feeding chicks and the prey species composition and size fed to chicks as well as to females (courtship feeding). Egg sizes did not differ between study periods, nor did feeding rates to chicks, suggesting that food was not a limiting resource. Terns spent less time with their broods (more time foraging) in the 1995-96 period. However, they also had significantly larger broods and fledged more offspring. The time of each individual foraging trip decreased, suggesting that fish were easier to obtain in 1995 and 1996. Lastly, kleptoparasitism rates decreased, suggesting that the costs of foraging (time, energy) actually decreased as fewer birds adopted this strategy to compensate for what I assumed to be a lack of available food (fish). The only significant difference between the periods of 1990, 1991 and 1995, 1996 was a change in diet. Terns delivered significantly fewer rainbow smelt and more emerald shiner in 1995 and 1996. However, the average size of fish delivered did not change. Thus, there was little impact on prey captured by Common Terns in Lake Erie since the invasion of the zebra mussel.

DNA polymerase activity in trophoblast giant cells in the mouse /

In the developing mouse embryo, the diploid trophectoderm is known to undergo a diploid to giant cell transformation. These cells arise by a process of endoreduplication, characterized by replication of the entire genome without subsequent mitosis or cell division, leading to polyploidy and the formation of giant nuclei. Studies of 13.5 day rat trophoblast derived from the parietal yolk sac have indicated a relatively low rate of DNA polymerase a activity, the noinnal eukaryotic replicase, in comparison to that of DNA polymerase g. These results have suggested that endoreduplication in trophoblast giant cells may not employ the normal replicase enzyme, DNA polymerase a. In order to determine whether a 'switch' from DNA polymerase to DNA polymerase is a necessary concomitant of the diploid to giant cell transformation, two distinct populations of trophoblast giant cells, the primary giant cell derived from the mural trophectoderm and the secondary giant cell derived from the polar trophoectoderm were used. These two populations of trophoblast giant cells can be obtained from the tissue outgrowths of 3.5da blastocysts and the extraembryonic ectoderm (EX) and ectoplacental cone (EPC) of 7.5 day embryos respectively. Tissue outgrowths were treated with aphidicolin, a specific reversible inhibitor of eukaryotic DNA polymerase a, on various days after explantation. The effect of aphidicolin treatment was assessed both qualitatively, using autoradiography and quantitatively by scintillation counting and Feulgen staining. 3 DNA synthesis was measured in control and treated cultures after a Hthymidine pulse. Scintillation counts of the embryo proper revealed that DNA synthesis was consistently inhibited by greater than 907. in the presence of aphidicolin. Inhibition of DNA synthesis in the EX and EPC varied between 81-957. and 82-987. respectively, indicating that most DNA synthesis was mediated by DNA polymerase a, but that a small but significant amount of residual synthesis was indicated. A qualitative approach was then applied to determine whether the apparent residual DNA synthesis was restricted to a subpopulation of giant cells or whether all giant cells displayed a low level of DNA synthesis. Autoradiographs of the ICM of blastocysts and the embryo proper of 7.5da embryos, which acted as diploid control population, was completely inhibited regardless of duration in explant culture. In contrast, primary trophoblast giant cells derived from blastocysts and secondary giant cells derived from the EX and EPC were observed to possess some heavily labelled cells after aphidicolin treatment. These results suggest that although DNA polymerase a is the primary replicating enzyme responsible for endoreduplication in mouse trophoblast giant cells, some nonactivity is also observed. A DNA polymerase assay employing tissue lysates of outgrown 7.5da embryo, EX and EPC tissues was used to attempt to confirm the presence of higher nonactivity in tissues possessing trophoblast giant cells. Employing a series of inhibitors of DNA polymerases, it would appear that DNA polymerase a is the major polymerase active in all tissues of the 7.5da mouse embryo. The nature of the putative residual DNA synthetic activity could not be unequivically determined in this study. Therefore, these results suggest that both primary and secondary trophoblast giant cells possess and use DNA polymerase a in endoreduplicative DNA synthesis. It would appear that the high levels of DNA polymerase g activity reported in trophoblast tissue derived from the 13.5 da rat yolk sac was not a general feature of all endoreduplication.

Letter from George W. Campbell, esq., late Secretary of the Treasury, to the Chairman of the Committee appointed to inquire into the causes and particulars of the invasion of the City of Washington, and the neighboring town of Alexandria, in the month of August last. --

Laid before the House by the Chairman of the said Committee, and ordered to be printed January 2, 1815.

Letter from George W. Campbell the Chairman of the Committee appointed to inquire into the causes and particulars of the invasion of the City of Washington

Full Title: Letter from George W. Campbell, esq., late Secretary of the Treasury, to the Chairman of the Committee appointed to inquire into the causes and particulars of the invasion of the City of Washington, and the neighboring town of Alexandria, in the month of August last Laid before the House by the Chairman of the said Committee, and ordered to be printed January 2, 1815. 13th Congress, 3rd Session. House. Doc. 38. Printed by Roger C. Weightman

Broadside reporting the Fenian Invasion of Canada, June 2, 1866

The Fenians were a group intent on securing Irish independence from England. The movement had its origins in Ireland in1857, under the leadership of James Stephens, with the assistance of John O'Mahony, an American who had raised funds for the cause. The American branch of this movement was especially successful, having raised $500 000 and enlisting about 10 000 American Civil War veterans. The group split into two separate factions, one desiring an invasion of Canada and the other preferring an uprising in Ireland. It soon became apparent that an uprising in Ireland was not imminent, and a decision was made to invade Canada. In April, 1866, a raid was launched against New Brunswick. It proved unsuccessful, and another raid was attempted on June 1, 1866, this time in Ridgeway, near Fort Erie, Ontario. The Canadian militiamen were defeated, but the Fenians subsequently withdrew. A third incident occurred on June 7, this time at Missisquoi Bay in Quebec, when the Fenians crossed the border, remained there for 2 days, and withdrew. A failed uprising in Ireland in 1867 signaled the demise of the movement. The Fenian threat helped to promote a sense of union among Canadians and provided an incentive for Confederation.

Broadside reporting the Fenian Invasion of Canada, June 2, 1866

The Fenians were a group intent on securing Irish independence from England. The movement had its origins in Ireland in1857, under the leadership of James Stephens, with the assistance of John O'Mahony, an American who had raised funds for the cause. The American branch of this movement was especially successful, having raised $500 000 and enlisting about 10 000 American Civil War veterans. The group split into two separate factions, one desiring an invasion of Canada and the other preferring an uprising in Ireland. It soon became apparent that an uprising in Ireland was not imminent, and a decision was made to invade Canada. In April, 1866, a raid was launched against New Brunswick. It proved unsuccessful, and another raid was attempted on June 1, 1866, this time in Ridgeway, near Fort Erie, Ontario. The Canadian militiamen were defeated, but the Fenians subsequently withdrew. A third incident occurred on June 7, this time at Missisquoi Bay in Quebec, when the Fenians crossed the border, remained there for 2 days, and withdrew. A failed uprising in Ireland in 1867 signaled the demise of the movement. The Fenian threat helped to promote a sense of union among Canadians and provided an incentive for Confederation.

Broadside Reporting the Fenian Invasion of Canada, June 3 1866

The collection consists of 6 broadsides reporting the events of the Fenian invasion of Canada on June 2 and 3, 1866. This broadside is titled Globe Extra and is from the evening of June 3rd, 1866. Some of the headings include: "Numerous Fenian Prisoners in our Hands", "All Quiet at Sarnia!" and "Further from Montreal! Troops Leaving for the Front".

Broadside Reporting the Fenian Invasion of Canada, June 4 1866

The collection consists of 6 broadsides reporting the events of the Fenian invasion of Canada on June 2 and 3, 1866. Three of the broadsides are titled Leader Extra, two are titled Globe Extra, and the last is titled News Extra. This one is titled Leader Extra and leads with the heading "Fenian Prisoners Twenty-One of them in Toronto Jail. Also included, "Latest American Reports: Interesting News from the East".

Broadside Reporting the Fenian Invasion, June 2 1866

The collection consists of 6 broadsides reporting the events of the Fenian invasion of Canada on June 2 and 3, 1866. Three of the broadsides are titled Leader Extra, two are titled Globe Extra, and the last is titled News Extra. This one is titled Leader Extra and begins with 2nd edition and ends with 8th edition. The headings include: "First Engagement: Our Gallant Volunteers foremost in the Attack", "Victory! Victory!", "Fenian Leader Shot", Battle at Fort Erie".