Michael A. Goldman

Biology of the X chromosome.

The biology of the X chromosome is unique, as there are two Xs in females and only a single X in males, whereas the autosomes are present in duplicate in both sexes. The presence of only a single autosome, which can occur as a result of an error in meiotic segregation, is invariably an embryonic lethal event. Monosomy for the X chromosome is viable because of dosage compensation, a system found in all organisms with an X:Y form of sex determination, which brings about equality of expression of most X-linked genes in females and males. In mammals, the dosage compensation system involves silencing of most of the genes on one X chromosome; it is called X chromosome inactivation. In this review, we focus first on recent advances in our understanding of the molecular basis of the X inactivation mechanism. Then we consider an unusual feature of X inactivation, the mosaic nature of the female and subsequent exposure to somatic cell selection.

Comparative methylation analysis of murine transgenes that undergo or escape X-chromosome inactivation

We analyzed an X-linked metallothionein–vasopressin (MTVP) fusion transgene that undergoes X-chromosome inactivation (X inactiv ation) and an X-linked transferrin (TFN) transgene that escapes X inactivation with respect to methylation in the 5′ regulatory regions. The MTVP transgene promoter region is unmethylated when the transgene is on the active X chromosome and methylated when on the inactive X chromosome. Interestingly, the MTVP transgene is not detectably transcribed from the male X chromosome, although it is unmethylated, consistent with its availability for transcription. The TFN transgene promoter region is hypomethylated on both the active and inactive X chromosomes, consistent with its expression from both chromosomes. The TFN and MTVP transgenes have been mapped to chromosomal regions D and C, respectively, by fluorescence in situ hybridization. These observations are discussed in the context of our understanding of the role of DNA methylation in the spread and maintenance of X-chromosome inactivation.

The epigenetics of the cell

A report on the 42nd Annual Meeting of the American Society for Cell Biology, San Francisco, 14-18 December 2002.

Collectively Improving Our Teaching: Attempting Biology Department–wide Professional Development in Scientific Teaching

A collaborative professional development program that engaged nearly 90% of faculty in a biology department in more than 40 hours of training on scientific teaching was instituted. Participating instructors integrated active learning in their courses, as shown through a variety of methods, and reported positive effects on teaching and departmental community.

Cancer: the chromatin connection

The American Association for Cancer Researchs 93rd Annual Meeting was held in San Francisco, California, USA, from 6 to 10 April 2002.

Evolution rising from the grave

Reactivation of a dormant message signals the dawn of a new humanity.

Me and you and everyone we know

From the Big Bang to our early ancestors, a philosopher probes human origins and identity In the slim volume You: A Natural History, Wright State University philosopher William B. Irvine lays out some of the fundamental science behind human history, human ancestry, lifes history and origin, and the origin of our Universe in simple and engaging prose.

The price of whole-genome sequencing may be decreasing, but who will be sequenced?

AIM Since whole-genome sequencing (WGS) information can have positive and negative personal utility for individuals, we examined predictors of willingness to pay (WTP) for WGS. PATIENTS & METHODS We surveyed two independent populations: adult patients (n = 203) and college seniors (n = 980). Ordinal logistic regression models were used to characterize the relationship between predictors and WTP. RESULTS Sex, age, education, income, genomic knowledge and knowing someone who had genetic testing or having had genetic testing done personally were associated with significantly higher WTP for WGS. After controlling for income and education, males were willing to pay more for WGS than females. CONCLUSION Differences in WTP may impact equity, coverage, affordability and access, and should be anticipated by public dialog about related health policy.

Building life from the bottom up

Engineering biological systems and organisms is a costly team effort and may be incompatible with an open-source regulatory environment, finds Michael A. Goldman.

Announcement (A New American Associate Editor)

Michael A. Goldman of San Francisco State University has joined our editorial team as the successor to Barbara Hamkalo. He originally graduated from the University of Rochester (MA) and Purdue (Ph.D>) and began his post-doctoral career at Baylor College of Medicine. His speci¢c interest in X-chromosome inactivation started when he was a Senior Fellow in Medical Genetics at the University of Washington at Seattle in 1984. He has been a Professor of Biology at SFSU since 1995.