Premature Sister Chromatid Separation Is Poorly Detected by the Spindle Assembly Checkpoint as a Result of System-Level Feedback

Sister chromatid cohesion, mediated by the cohesin complex, is essential for faithful mitosis. Nevertheless, evidence suggests that the surveillance mechanism that governs mitotic fidelity, the spindle assembly checkpoint (SAC), is not robust enough to halt cell division when cohesion loss occurs prematurely. The mechanism behind this poor response is not properly understood. Using developing Drosophila brains, we show that full sister chromatid separation elicits a weak checkpoint response resulting in abnormal mitotic exit after a short delay. Quantitative live-cell imaging approaches combined with mathematical modeling indicate that weak SAC activation upon cohesion loss is caused by weak signal generation. This is further attenuated by several feedback loops in the mitotic signaling network. We propose that multiple feedback loops involving cyclin-dependent kinase 1 (Cdk1) gradually impair error-correction efficiency and accelerate mitotic exit upon premature loss of cohesion. Our findings explain how cohesion defects may escape SAC surveillance.

Labor clauses in regional trade agreements and effects on labor conditions : an empirical analysis

An increasing number of bilateral or plurilateral trade agreements (or regional trade agreements: RTAs) include "labor clauses" that require or urge the signatory countries to commit to maintaining a certain level of labor standards. This paper performs an empirical analysis of the impacts of such labor clauses provided in RTAs on working conditions that laborers in the RTA signatory countries actually face, using macro-level data for a wide variety of countries. The paper first examines the texts of labor provisions in more than 220 effective RTAs and (re-)classifies "RTAs with labor clauses" according to two criteria: (i) the agreement urges or expects the signatory countries to harmonize their domestic labor standards with internationally recognized standards, and (ii) the agreement stipulates the procedures for consultations and/or dispute settlement on labor-condition issues between the signatory countries. Based on this labor-clause RTA classification, the paper estimates the impacts of RTA labor clauses on working conditions in countries with two empirical specifications using the sample covering 136 countries or economies and years from 1995 through 2011. The estimation is extended to takes into account possible lags in the labor-condition effects of labor clauses as well as to consider potential difference in the impacts for countries in different income levels. The empirical results for the four measures of labor conditions (mean monthly real earnings, mean weekly work hours per employee, fatal occupational injury rate, and the number of the ILO's Core Conventions ratified) find no evidence for possible pro-labor-condition effects of RTA labor clauses overall, which should be consistent with the view of economics literature that questions the relevance of linking trade policy with issues in the domestic labor standards.

Farm labor fact book.

Mode of access: Internet.

The migratory farm labor problem in the United States : a report, together with individual views, to the Committee on Labor and Public Welfare, United States Senate, made by its Subcommittee on Migratory Labor, pursuant to S. Res. 267 (86th Cong., 2d sess.) a resolution authorizing a study of the problems of migratory labor.

Cover title.

Migratory labor. Hearings before the Subcommittee on Migratory Labor of the Committee on Labor and Public Welfare, United States Senate, Eighty-sixth Congress, first [-second] session, on S. 1085 [and other] bills ...

Hearings held Aug. 7, 1959-July 11, 1960 in various cities.

Migratory labor : hearings before the Subcommittee on Migratory Labor of the Committee on Labor and Public Welfare, United States Senate, Eighty-seventh Congress, first session, on S. 1123 [and other] bills ...

Hearings held Apr. 12, 1961 - Aug. 17, 1962.

Labor law and practice in Colombia

Bibliography: p. 87.

Labor law and practice in Ecuador /

Cover title.

Labor law and practice in Colombia /

Cover title.

Labor legislation of Ecuador /

"This translation of the labor laws of Ecuador was made under the direction of Ethel Y. Larson, of the Bureau of Labor Statistics."

Labor legislation of Paraguay /

"This translation of the labor laws of Paraguay was made under the direction of Ethel Y. Larson, of the Bureau of Labor Statistics."

Child labor and inadequate family income; preliminary report on a study of the work and welfare of children of agricultural laborers in Hidalgo County, Texas.

Cover title.

Immigrants and the American labor market /

Includes bibliographical references.

Labor legislation of Venezuela /

"This translation of the labor laws of Venezuela was made under the direction of Ethel Y. Larson, of the Bureau of Labor Statistics."