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This Week in Cell: Apr 15, 2009

Chromatin-associated proteins and histone modifications can be maintained through many rounds of transcription, but it wasn't known whether these complexes stay bound. Scientists at Harvard examined the PRC1-class Polycomb group protein complexes in an in vitro transcription experiment and found that Polycomb complexes remain bound to replicated templates. "Retention of Polycomb proteins through DNA replication may contribute to maintenance of transcriptional silencing through cell division," they say in the abstract.

Researchers looked at how unconventional polyubiquitin chains linked through K6, K11, K27, K29, or K33 participate in protein degradation through the ubiquitin system. They profiled both the entire yeast proteome and ubiquitinated proteins in wild-type and ubiquitin K11R mutant strains using mass spec and identified K11 linkage-specific substrates to be involved in endoplasmic reticulum-associated degradation, suggesting that "unconventional polyubiquitin chains are critical" in the ubiquitin-proteasome system.

In a study led by Susan Lindquist and Simon Alberti at the Whitehead Institute, researchers performed bioinformatic analysis on the S. cerevisiae proteome to look for prion proteins and identified 100 candidates. They found that 19 of them could form prions and that at least one, Mot3, "produces a bona fide prion in its natural context that increases population-level phenotypic heterogeneity."

Italian researchers used synthetic biology to test reverse-engineered systems biology networks. After building a five-gene synthetic network, they measured time series and steady-state expression data after multiple perturbations and then used this data to compare the effectiveness of sys bio modeling techniques. Reverse engineering based on differential equations and Bayesian networks correctly inferred regulatory interactions from the experimental data, they say in the abstract.

The Scan

Missed Early Cases

A retrospective analysis of blood samples suggests early SARS-CoV-2 infections may have been missed in the US, the New York Times reports.

Limited Journal Editor Diversity

A survey finds low diversity among scientific and medical journal editors, according to The Scientist.

How Much of a Threat?

Science writes that need for a provision aimed at shoring up genomic data security within a new US bill is being questioned.

PNAS Papers on Historic Helicobacter Spread, Brain Development, C. difficile RNAs

In PNAS this week: Helicobacter genetic diversity gives insight into human migrations, gene expression patterns of brain development, and more.