Twenty-two dogs were managed surgically for a single extrahepatic portosystemic shunt; 12 with surgical ligation and 10 with an Ameroid constrictor. Utilization of the Ameroid constrictor significantly decreased surgery time to approximately half that of the ligation technique. A decreased intraoperative and postoperative complication rate was noted with the Ameroid constrictor group. Follow-up evaluation demonstrated comparable efficacy when comparing surgical techniques. The Ameroid constrictor offered a surgical occlusion technique for management of a single extra-hepatic portosystemic shunt that was equally effective to ligation while shortening surgical time and minimizing the risks that are commonly associated with ligation of the shunting vessel.

Histone variants, present in various cell types and tissues, are known to exhibit different functions. For example, histone H3.3 and H2A.Z are both involved in gene expression regulation, whereas H2A.X is a specific variant that responds to DNA double-strand breaks. In this study, we characterized H4G, a novel hominidae-specific histone H4 variant. We found that H4G is expressed in a variety of human cell lines and exhibit tumor-stage dependent overexpression in tissues from breast cancer patients. We found that H4G localized primarily to the nucleoli of the cell nucleus. This localization was controlled by the interaction of the alpha-helix 3 of the histone fold motif with a histone chaperone, nucleophosmin 1. In addition, we found that modulating H4G expression affects rRNA expression levels, protein synthesis rates and cell-cycle progression. Our data suggest that H4G expression alters nucleolar chromatin in a way that enhances rDNA transcription in breast cancer tissues.

In 1963, Margoliash discovered the unexpected genetic equidistance result after comparing cytochrome c sequences from different species. This finding, together with the hemoglobin analyses of Zuckerkandl and Pauling in 1962, directly inspired the ad hoc molecular clock hypothesis. Unfortunately, however, many biologists have since mistakenly viewed the molecular clock as a genuine reality, which in turn inspired Kimura, King, and Jukes to propose the neutral theory of molecular evolution. Many years of studies have found numerous contradictions to the theory, and few today believe in a universal constant clock. What is being neglected, however, is that the failure of the molecular clock hypothesis has left the original equidistance result an unsolved mystery. In recent years, we fortuitously rediscovered the equidistance result, which remains unknown to nearly all researchers. Incorporating the proven virtues of existing evolutionary theories and introducing the novel concept of maximum genetic diversity, we proposed a more complete hypothesis of evolutionary genetics and reinterpreted the equidistance result and other major evolutionary phenomena. The hypothesis may rewrite molecular phylogeny and population genetics and solve major biomedical problems that challenge the existing framework of evolutionary biology. genetic equidistance, overlap feature, evolution, molecular clock, neutral theory, maximum genetic diversity hypothesis, microevolution, macroevolution Citation:Hu T B, Long M P, Yuan D J, et al. The genetic equidistance result: misreading by the molecular clock and neutral theory and reinterpretation nearly half of a century later. Sci China Life Sci, 2013Sci, , 56: 254 -261, doi: 10.1007 Among the most interesting phenomena in biology are reproduction, heredity, and evolution. Biological evolution includes both phenotypes and molecules, which are modeled by the theory of natural selection and the neutral theory, respectively. Together, the two make up the modern evolutionary theory (MET). The neutral theory was proposed by Kimura, Jukes, and King to explain the observation that molecules evolved at a steady, clock-like rate [1,2]. But is the molecular clock a genuine universal phenomenon?1 A brief history of the molecular clock hypothesis and the neutral theory: how the molecular clock replaced the genetic equidistance phenomenonGenetic distance is a measure of molecular differences between species and is represented by the percentage differ-

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Regulation of transcription elongation is one of the key mechanisms employed to control gene expression. The single-subunit mitochondrial RNA polymerase (mtRNAP) transcribes mitochondrial genes, such as those related to ATP synthesis. We investigated how mitochondrial transcription elongation factor (TEFM) enhances mtRNAP transcription elongation using a single-molecule optical-tweezers transcription assay, which follows transcription dynamics in real time and allows the separation of pause-free elongation from transcriptional pauses. We found that TEFM enhances the stall force of mtRNAP. Although TEFM does not change the pause-free elongation rate, it enhances mtRNAP transcription elongation by reducing the frequency of long-lived pauses and shortening their durations. Furthermore, we demonstrate how mtRNAP passes through the conserved sequence block II, which is the key sequence for the switch between DNA replication and transcription in mitochondria. Our findings elucidate how both TEFM and mitochondrial genomic DNA sequences directly control the transcription elongation dynamics of mtRNAP.

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Background: Numerous mathematical models and retrospective analyses have been conducted to explore the natural progression of breast cancer, but there is no precise timeline as to how long it takes breast cancer to progress from stages 0 to IV. Studying the natural history of breast cancer requires the follow-up of a large cohort of patients who received no treatment following diagnosis for a long period, but this has become unpractical in the modern era. In this study, we quantified the natural progression of breast cancer using the Surveillance, Epidemiology, and End Results (SEER) database which was collected the clinical-pathological characteristics and survival data of untreated breast cancer patients.Methods: We included 12,687 female patients who did not receive surgical treatment, radiotherapy, or chemotherapy, had complete information on tumor staging, and had only 1 primary tumor in their lifetime in our study as the untreated group. Overall survival (OS) was calculated from the date of the latest diagnosis of breast cancer to the date of death. Medium survival time (MST) was defined as the time at which 50% of the patients reached the endpoint. The medium survival time (MST) was calculated for each stage. The progression time was calculated by subtracting the MST of a higher stage from that of a lower stage, which also indicated "life loss". Estrogen receptor (ER) negative and positive patients were analyzed as two separate groups.Results: For the ER positive patients, the median progression times from stages 0 to I, I to II, II to III, and III to IV were 5.2±1.2, 4.2±0.5, 2±0.3, and 0.9±0.2 years, respectively, which were similar to those of the ER negative patients of 5.4±2.9, 4.7±1.3, 2.5±0.7, and 1.1±0.4 years (P=0.49). The survival of stage IV patients was longer in ER positive patients than ER negative patients (2.7±0.1 vs. 0.9±0.2 year, P<0.001).Conclusions: ER negative patients appear to have the same progression time as that of ER positive patients in the primary site, but had a much worse process in the metastasis site.