The average genome size (GS) of bats, which are the only mammals capable of powered flight, is approximately 18% smaller than that of closely related mammalian orders. The low nuclear DNA content of Chiroptera is comparable to that of birds, which are also characterized by a high metabolic rate. Only a few chiropteran taxa possess notable amounts of constitutive heterochromatin. Here, we studied the karyotypes of two non-related vesper bat species with unusually high amounts of constitutive heterochromatin: Hesperoptenus doriae and Philetor brachypterus. Conventional staining methods and whole-chromosome painting with probes derived from Myotis myotis (2n = 44), showing a karyotype close to that of the presumed ancestor of Vespertilionidae, revealed Robertsonian fusions as the main type of rearrangement leading to the exceptionally reduced diploid chromosome number of 2n = 26 in both species. Moreover, both karyotypes are characterized by large blocks of pericentromeric heterochromatin composed of CMA-positive and DA-DAPI-positive segments. In H. doriae, the heterochromatin accumulation has resulted in a genome size of 3.22 pg (1C), which is 40% greater than the mean genome size for the family. For P. brachypterus, a genome size of 2.94 pg was determined, representing an increase of about 28%. Most notably, in H. doriae, the presence of additional constitutive heterochromatin correlates with an extended mitotic cell cycle duration in vitro. A reduction in diploid chromosome number to 30 or lower is discussed as a possible cause of the accumulation of pericentromeric heterochromatin in Vespertilionidae.
The International Collaboration on Cancer Reporting is a nonprofit organization whose goal is to develop evidence-based, internationally agreed-upon standardized data sets for each cancer site for use throughout the world. Providing global standardization of pathology tumor classification, staging, and other reporting elements will lead to the objective of improved patient management and enhanced epidemiologic research. Carcinomas of the oral cavity continue to represent a significant oncologic management burden, especially as changes in alcohol and tobacco use on a global scale contribute to tumor development. Separation of oral cavity carcinomas from oropharyngeal tumors is also important, as management and outcome are quite different when human papillomavirus association is taken into consideration. Topics such as tumor thickness versus depth of invasion, pattern of invasive front, extent and size of perineural invasion, and margin assessment all contribute to accurate classification and staging of tumors. This review focuses on the data set developed for Carcinomas of the Oral Cavity Histopathology Reporting Guide, with discussion of the key elements developed for inclusion.