pHlameleons: a family of FRET-based protein sensors for quantitative pH imaging.

Intracellular pH is an important indicator for cellular metabolism and pathogenesis. pH sensing in living cells has been achieved using a number of synthetic organic dyes and genetically expressible sensor proteins, even allowing the specific targeting of intracellular organelles. Ideally, a class of genetically encodeable sensors need to cover relevant cellular pH ranges.

Less DeltamtDNA4977 than normal in various types of tumors suggests that cancer cells are essentially free of this mutation.

Levels of mtDNA(4977) deletions (DeltamtDNA(4977)) have been found to be lower in tumors than in adjacent non-tumoral tissues. In 87 cancer patients, DeltamtDNA(4977) was detected by multiplex polymerase chain reaction (PCR) amplification in 43 (49%) of the tumors and in 74 (85%) of the samples of non-tumoral tissues that were adjacent to the tumors. DeltamtDNA(4977) deletions were detected in 24% of the breast tumors, 52% of the colorectal tumors, 79% of the gastric tumors, and 40% of the head and neck tumors as compared with 77, 83, 100, and 90% of the adjacent respective non-tumoral tissues at the same DNA template dilution.

Evaluation of a method for high yield purification of largely intact mitochondrial DNA from human placentae.

We developed, and quantitatively and qualitatively evaluated an easily reproducible method for high yield purification of mitochondrial DNA (mtDNA) from human placentae by mechanical tissue disruption, differential centrifugation of mitochondria, enzymatic digestion, phenol extraction and ethanol precipitation. Average mtDNA yields were 2.5 microg/g tissue (without an RNAse treatment step) and 1.

The common mitochondrial DNA deletion deltamtDNA(4977): shedding new light to the concept of a tumor suppressor mutation.

We propose that the age-related accumulation of deltamtDNA(4977) mutations may serve a protective function against tumor-promoting effects of other somatic mutations. The evidence discussed here is consistent with the concept that deltamtDNA(4977) plays a tumor-suppressor role, thus shedding new light to the concept of a tumor suppressor mutation. This concept may help understand how a tumor-promoting mutation may be able to cause malignant transformation in cells lacking a tumor-suppressor mutation, while the same tumor-promoting mutation can be present in cells that carry a tumor-suppressor mutation, without causing cancer.