Sister chromatid decatenation: bridging the gaps in our knowledge

Faithful chromosome segregation is critical in preventing genome loss or damage during cell division. Failure to properly disentangle catenated sister chromatids can lead to the formation of bulky or ultrafine anaphase bridges, and ultimately genome instability. In this review we present an overview of the current state of knowledge of how sister chromatid decatenation is carried out, with particular focus on the role of TOP2A and TOPBP1 in this process.     

Complex permittivity of representative biological solutions in the 2–67 GHz range

The main purpose of this study is to provide experimental data on the complex permittivity of some biological solutions in the 2–67 GHz range at room and human body temperatures. The permittivity measurements are performed using an open‐ended coaxial probe. Permittivity spectra of several representative monomolecular solutions of proteins, amino acids, nucleic acids, and carbohydrates are analyzed and compared. Furthermore, measurements have also been performed for complex biomolecular solutions, including bovine serum albumin (BSA)–DNA–glucose mixture, culture medium, and yeast extract solution. The results demonstrate that for concentrations below 1%, the permittivity spectra of the solutions do not substantially differ from that of distilled water. Measurements carried out for 4% and 20% BSA solutions show that the presence of proteins results in a decrease in permittivity. For highly concentrated RNA solutions (3%), a slight increase in the imaginary part of the permittivity is observed below 10 GHz. Experimental data show that free water permittivity can be used for modeling of the culture medium above 10 GHz. However, at lower frequencies a substantial increase in the imaginary part of the permittivity due to ionic conductivity should be carefully taken into account. A similar increase has also been observed for the yeast extract solution in the lower frequency region of the considered spectrum. Above 10 GHz, the high concentration of proteins and other low‐permittivity components of the yeast extract solution results in a decrease in the complex permittivity compared to that of water. Obtained data are of utmost importance for millimeter‐wave dosimetry studies. Bioelectromagnetics 33:346–355, 2012. © 2011 Wiley Periodicals, Inc.     

Lipid-lowering effect of berberine in human subjects and rats

Due to serious adverse effects and the limited effectiveness of currently available pharmacological therapies for obesity, many research efforts have focused on the development of drugs from natural products. Our previous studies demonstrated that berberine, an alkaloid originally isolated from traditional Chinese herbs, prevented fat accumulation in vitro and in vivo. In this pilot study, obese human subjects (Caucasian) were given 500 mg berberine orally three times a day for twelve weeks. The efficacy and safety of berberine treatment was determined by measurements of body weight, comprehensive metabolic panel, blood lipid and hormone levels, expression levels of inflammatory factors, complete blood count, and electrocardiograph. A Sprague-Dawley rat experiment was also performed to identify the anti-obesity effects of berberine treatment. The results demonstrate that berberine treatment produced a mild weight loss (average 5 lb/subject) in obese human subjects. But more interestingly, the treatment significantly reduced blood lipid levels (23% decrease of triglyceride and 12.2% decrease of cholesterol levels) in human subjects. The lipid-lowering effect of berberine treatment has also been replicated in the rat experiment (34.7% decrease of triglyceride and 9% decrease of cholesterol level). Cortisol, calcitriol, ACTH, TSH, FT4, and SHBG levels were not significantly changed following 12 weeks of berberine treatment. However, there was interestingly, an increase in calcitriol levels seen in all human subjects following berberine treatment (mean 59.5% increase, p=0.11). Blood inflammatory factors (CRP, IL-6, TNFα, COX-2) and erythrocyte sedimentation rate (ESR) were not significantly affected by treatment with berberine. Tests of hematological, cardiovascular, liver, and kidney function following berberine treatment showed no detrimental side effects to this natural compound. Collectively, this study demonstrates that berberine is a potent lipid-lowering compound with a moderate weight loss effect, and may have a possible potential role in osteoporosis treatment/prevention.     

Quantification of porosity in Acropora pulchra (Brook 1891) using X-ray micro-computed tomography techniques

Skeletal density and porosity characteristics are key parameters for investigations into scleractinian coral growth and for assessing the effects of a range of anthropogenic influences on coral reefs. Typically, skeletal density is measured by using planar X-rays of thin slabs cut from mound-shaped colonies or, for branching forms, by using methods based on Archimedean principles. This paper describes a novel non-destructive technique based on micro-computed tomography (micro-CT) to measure porosity of branching coral skeleton. This approach incorporates methods for segmenting internal and external portions of branch and for distinguishing between skeleton and air, whilst accounting for the effects of beam hardening. Measurements were obtained from colonies of branching Acropora pulchra collected across a reef-flat transect at King Reef, central nearshore Great Barrier Reef. The results show significant variation in porosity within and among branches sampled from individual colonies, but not within a reef-flat transect. Micro-CT techniques yield comparable results to traditional methods based on Archimedean principles, but offer advantages in their suitability for a wider range of coral specimens because of the non-destructive nature of the technique and in their more rigorous control of model parameters that can bias results.     

Does serotonin influence aggression? comparing regional activity before and during social interaction

Serotonin is widely believed to exert inhibitory control over aggressive behavior and intent. In addition, a number of studies of fish, reptiles, and mammals, including the lizard Anolis carolinensis, have demonstrated that serotonergic activity is stimulated by aggressive social interaction in both dominant and subordinate males. As serotonergic activity does not appear to inhibit agonistic behavior during combative social interaction, we investigated the possibility that the negative correlation between serotonergic activity and aggression exists before aggressive behavior begins. To do this, putatively dominant and more aggressive males were determined by their speed overcoming stress (latency to feeding after capture) and their celerity to court females. Serotonergic activities before aggression are differentiated by social rank in a region-specific manner. Among aggressive males baseline serotonergic activity is lower in the septum, nucleus accumbens, striatum, medial amygdala, anterior hypothalamus, raphe, and locus ceruleus but not in the hippocampus, lateral amygdala, preoptic area, substantia nigra, or ventral tegmental area. However, in regions such as the nucleus accumbens, where low serotonergic activity may help promote aggression, agonistic behavior also stimulates the greatest rise in serotonergic activity among the most aggressive males, most likely as a result of the stress associated with social interaction.     

The role of amino acids in the amplification and quality of DNA vectors for industrial applications

In this study, we have demonstrated that the type and feeding regimen of amino acids have a significant impact on the quality as well as the quantity of DNA vectors produced. Nutrient pool and factorial design experiments were carried out in order to identify the amino acids involved in increased biomass and induction of plasmid amplification. Leucine, glycine, and histidine were responsible for increased biomass and leucine starvation in the presence of histidine was implicated in plasmid amplification. Supercoiling of the plasmid was optimized using a dual feeding strategy. As a result of this, a fed-batch fermentation strategy for the production of a 6.9 kb plasmid, pSVß, in Escherichia coli DH5α was developed. In batch fermentation, a maximum plasmid yield of 39.4 mg/L equivalent to 11.3 mg/g dry cell weight (DCW) was achieved with casein hydrolysate limitation. About 90% of plasmid was in the supercoiled (SC) form after 31 hr of fermentation but only remained so for a short period, leading to a very brief window for harvesting cells at scale. Subsequently, a fed-batch fermentation using a dual feeding strategy was employed. A mean maximum plasmid yield of 44 mg/L equivalent to 9.1 mg plasmid/g DCW was achieved. After 25 hr, 90% of plasmid was in the SC form and remained at this level for the remaining 10 hr of the fermentation, allowing adequate time for the harvesting of cells without the loss of supercoiling of product. This study emphasized that optimizing fermentation strategy and identifying the essential nutrients are beneficial for bioprocessing of plasmid DNA for therapeutic applications.     

Identification of One Novel Candidate Probiotic Lactobacillus plantarum Strain Active against Influenza Virus Infection in Mice by a Large-Scale Screening

In this study, we developed a large-scale screening of bacterial strains in order to identify novel candidate probiotics with immunomodulatory properties. For this, 158 strains, including a majority of lactic acid bacteria (LAB), were screened by two different cellular models: tumor necrosis factor alpha (TNF-α)-activated HT-29 cells and peripheral blood mononuclear cells (PBMCs). Different strains responsive to both models (pro- and anti-inflammatory strains) were selected, and their protective effects were tested in vivo in a murine model of influenza virus infection. Daily intragastric administrations during 10 days before and 10 days after viral challenge (100 PFU of influenza virus H1N1 strain A Puerto Rico/8/1934 [A/PR8/34]/mouse) of Lactobacillus plantarum CNRZ1997, one potentially proinflammatory probiotic strain, led to a significant improvement in mouse health by reducing weight loss, alleviating clinical symptoms, and inhibiting significantly virus proliferation in lungs. In conclusion, in this study, we have combined two cellular models to allow the screening of a large number of LAB for their immunomodulatory properties. Moreover, we identified a novel candidate probiotic strain, L. plantarum CNRZ1997, active against influenza virus infection in mice.     

The Chemotactic Response of Vibrio anguillarum to Fish Intestinal Mucus Is Mediated by a Combination of Multiple Mucus Components

Chemotactic motility has previously been shown to be essential for the virulence of Vibrio anguillarum in waterborne infections of fish. To investigate the mechanisms by which chemotaxis may function during infection, mucus was isolated from the intestinal and skin epithelial surfaces of rainbow trout. Chemotaxis assays revealed that V. anguillarum swims towards both types of mucus, with a higher chemotactic response being observed for intestinal mucus. Work was performed to examine the basis, in terms of mucus composition, of this chemotactic response. Intestinal mucus was analyzed by using chromatographic and mass spectrometric techniques, and the compounds identified were tested in a chemotaxis assay to determine the attractants present. A number of mucus-associated components, in particular, amino acids and carbohydrates, acted as chemoattractants for V. anguillarum. Importantly, only upon combination of these attractants into a single mixture were levels of chemotactic activity similar to those of intestinal mucus generated. A comparative analysis of skin mucus revealed its free amino acid and carbohydrate content to be considerably lower than that of the more chemotactically active intestinal mucus. To study whether host specificity exists in relation to vibrio chemotaxis towards mucus, comparisons with a human Vibrio pathogen were made. A cheR mutant of a Vibrio cholerae El Tor strain was constructed, and it was found that V. cholerae and V. anguillarum exhibit a chemotactic response to mucus from several animal sources in addition to that from the human jejunum and fish epithelium, respectively.