To ensure correct meiotic chromosome segregation, sister chromatid cohesion (SCC) needs to be maintained from its establishment in prophase I oocytes before birth until continuation of meiosis into metaphase II upon oocyte maturation in the adult. Aging human oocytes suffer a steep increase in chromosome missegregation and aneuploidy, which may be caused by loss of SCC through slow deterioration of cohesin [1-3]. This hypothesis assumes cohesin expression in embryonic oocytes is sufficient to provide adequate long-term SCC. With increasing age, mouse oocytes deficient in the meiosis-specific cohesin SMC1β massively lose SCC and chiasmata [3, 4]. To test the deterioration hypothesis, we specifically and highly efficiently inactivated the mouse Smc1β gene at the primordial follicle stage shortly after birth when oocytes had just entered meiosis I dictyate arrest. In the adult, however, irrespective of oocyte age, chiasma positions and SCC are normal. Frequency and size of litters prove full fertility even in aged females. Thus, SMC1β cohesin needs only be expressed during prophase I prior to the primordial follicle stage to ensure SCC up to advanced age of mice.

Michigan is unique nationally as one of the few states that have formalized their NPDES Storm Water Phase II compliance through the use of a general permit based on watershed management planning. This special permitting approach has resulted in a large majority of Michigan's regulated Phase II communities using watershed management planning as a tool to implement their Phase II Program. To date, two hundred and thirty two communities in Michigan are using this approach. This paper is intended to guide other communities in the formation of regional watershed based Phase II groups. Options for committee formation under Michigan statutes, committee structure and organization, and funding methods are provided. A case study from Lansing, Michigan is examined to show the committee's inception, participants, legal relationships, committee structure, funding allocations, evaluation, and permit application.