Identification of furfural resistant strains of Saccharomyces cerevisiae and Saccharomyces paradoxus from a collection of environmental and industrial isolates

Background Fermentation of bioethanol using lignocellulosic biomass as a raw material provides a sustainable alternative to current biofuel production methods by utilising waste food streams as raw material. Before lignocellulose can be fermented it requires physical, chemical and enzymatic treatment in order to release monosaccharides, a process that causes the chemical transformation of glucose and xylose into the cyclic aldehydes furfural and hydroxyfurfural. These furan compounds are potent inhibitors of Saccharomyces fermentation, and consequently furfural tolerant strains of Saccharomyces are required for lignocellulosic fermentation. Results This study investigated yeast tolerance to furfural and hydroxyfurfural using a collection of 71 environmental and industrial isolates of the baker’s yeast Saccharomyces cerevisiae and its closest relative Saccharomyces paradoxus. The Saccharomyces strains were initially screened for growth on media containing 100 mM glucose and 1.5 mg ml-1 furfural. Five strains were identified that showed a significant tolerance to growth in the presence of furfural and these were then screened for growth and ethanol production in the presence of increasing amounts (0.1-4 mg ml-1) of furfural. Conclusions Of the five furfural tolerant strains S. cerevisiae NCYC 3451 displayed the greatest furfural resistance, and was able to grow in the presence of up to 3.0 mg ml-1 furfural. Furthermore, ethanol production in this strain did not appear to be inhibited by furfural, with the highest ethanol yield observed at 3.0 mg ml-1 furfural. Although furfural resistance was not found to be a trait specific to any one particular lineage or population, three of the strains were isolated from environments where they might be continually exposed to low levels of furfural through the on-going natural degradation of lignocelluloses, and would therefore develop elevated levels of resistance to these furan compounds. Thus these strains represent good candidates for future studies of genetic variation relevant to understanding and manipulating furfural resistance and in the development of tolerant ethanologenic yeast strains for use in bioethanol production from lignocellulose processing

The anatomy of sartorius muscle and its implications for sarcoma radiotherapy.

PURPOSE: Controversy exists as to whether sartorius muscle is completely invested in fascia. If it is, then direct tumour involvement from soft tissue sarcoma of the anterior thigh would be unlikely and would justify omitting sartorius from the radiotherapy volume. SUBJECTS AND METHODS: Eight thighs in six cadavers were examined in the dissecting room. Using a previous case, conformal radiotherapy plans were prepared to treat the anterior compartment of the thigh including and excluding sartorius. The corridor of unirradiated normal tissue was outlined separately. RESULTS: In all cases, sartorius was enclosed within a fascial sheath of its own. In four of the six cadavers, there was clear evidence of a fascial envelope surrounding sartorius, fused to the fascia lata and medial intermuscular septum. In two, sartorius was fully ensheathed in the upper half of the thigh; in the lower half the intermuscular septum became thin, and blended with the tendinous aponeurosis on the surface of vastus medialis in an example case. By excluding sartorius, the volume of the anterior compartment was reduced by 8%, but the volume of the unirradiated normal tissue corridor increased by 134%. With sartorius included, the unirradiated corridor became very small inferiorly, only 6% of the circumference of the whole leg, compared to 27% with sartorius excluded. DISCUSSION: The anatomy suggests that sartorius could be safely omitted from the clinical target volume of anterior compartment soft tissue sarcomas. This substantially increases the size of the unirradiated normal tissue corridor, expressed as a volume and a circumference, which could give a clinical advantage by reducing normal tissue complications.Peer Reviewe

Rmi1 stimulates decatenation of double Holliday junctions during dissolution by Sgs1-Top3

double Holliday junction (dHJ) is a central intermediate of homologous recombination that can be processed to yield crossover or non-crossover recombination products. To preserve genomic integrity, cells possess mechanisms to avoid crossing over. We show that Saccharomyces cerevisiae Sgs1 and Top3 proteins are sufficient to migrate and disentangle a dHJ to produce exclusively non-crossover recombination products, in a reaction termed "dissolution." We show that Rmi1 stimulates dHJ dissolution at low Sgs1-Top3 protein concentrations, although it has no effect on the initial rate of Holliday junction (HJ) migration. Rmi1 serves to stimulate DNA decatenation, removing the last linkages between the repaired and template DNA molecules. Dissolution of a dHJ is a highly efficient and concerted alternative to nucleolytic resolution that prevents crossing over of chromosomes during recombinational DNA repair in mitotic cells and thereby contributes to genomic integrity

BLM and RMI1 alleviate RPA inhibition of topoIIIα decatenase activity

RPA is a single-stranded DNA binding protein that physically associates with the BLM complex. RPA stimulates BLM helicase activity as well as the double Holliday junction dissolution activity of the BLM-topoisomerase IIIα complex. We investigated the effect of RPA on the ssDNA decatenase activity of topoisomerase IIIα. We found that RPA and other ssDNA binding proteins inhibit decatenation by topoisomerase IIIα. Complex formation between BLM, TopoIIIα, and RMI1 ablates inhibition of decatenation by ssDNA binding proteins. Together, these data indicate that inhibition by RPA does not involve species-specific interactions between RPA and BLM-TopoIIIα-RMI1, which contrasts with RPA modulation of double Holliday junction dissolution. We propose that topoisomerase IIIα and RPA compete to bind to single-stranded regions of catenanes. Interactions with BLM and RMI1 enhance toposiomerase IIIα activity, promoting decatenation in the presence of RPA

Genetic variants in MUTYH are not associated with endometrial cancer risk

Hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome, is an autosomal dominant inherited predisposition to a number of epithelial cancers, most notably colorectal and endometrial cancer. Outside of the context of Lynch syndrome there is little evidence for an autosomal dominant or recessive condition that predisposes to endometrial cancer. Recently, genetic variants in MUTYH have been associated with a recessive form of colorectal cancer, known as MUTYH associated polyposis or MAP. MUTYH is involved in base excision repair of DNA lesions and as such a breakdown in the fidelity of this process would necessarily not be predicted to result in a specific disease. At present there is little information about the role of MUTYH in other types of cancer and only one report indicating a possible relationship with endometrial cancer

Bleeding from ruptured hepatic metastases as a cause of syncope in an octogenarian: a case report

<p>Abstract</p> <p>Introduction</p> <p>Acute hemoperitoneum as a result of hemorrhage from liver metastases is an uncommon but serious condition. The use of appropriate imaging is important in the diagnosis and can have a profound impact on subsequent management. This case is important because the presentation was of recurrent syncopal episodes with an unusual underlying cause. This case highlights the need to consider this diagnosis in the differential in patients presenting with collapse in the acute setting.</p> <p>Case presentation</p> <p>We present the case of an 85-year-old Caucasian man who was admitted following a collapse episode and was found to be persistently hypotensive despite aggressive resuscitation. An acute intra-peritoneal bleed originating from hepatic metastases from an unknown primary was identified promptly with computed tomography imaging and was subsequently managed conservatively.</p> <p>Conclusions</p> <p>This case aims to convey key teaching points: (A) the need to consider intra-abdominal hemorrhage in the differential diagnosis when assessing patients with collapse; and (B) the use of appropriate imaging such as computed tomography can facilitate a prompt diagnosis and appropriate management steps can then be taken accordingly.</p

Loss of slc39a14 causes simultaneous manganese hypersensitivity and deficiency in zebrafish

Manganese neurotoxicity is a hallmark of Hypermanganesemia with Dystonia 2, an inherited manganese transporter defect caused by mutations in SLC39A14. To identify novel potential targets of manganese neurotoxicity we performed transcriptome analysis of slc39a14-/- mutant zebrafish unexposed and exposed to MnCl2. Differentially expressed genes mapped to the central nervous system and eye, and pathway analysis suggested that calcium dyshomeostasis and activation of the unfolded protein response are key features of manganese neurotoxicity. Consistent with this interpretation, MnCl2 exposure led to decreased whole animal calcium levels, locomotor defects and changes in neuronal activity within the telencephalon and optic tectum. In accordance with reduced tectal activity, slc39a14-/- zebrafish showed changes in visual phototransduction gene expression, absence of visual background adaptation and a diminished optokinetic reflex. Finally, numerous differentially expressed genes in mutant larvae normalised upon MnCl2 treatment indicating that, in addition to neurotoxicity, manganese deficiency is present either subcellularly or in specific cells or tissues. Overall, we assembled a comprehensive set of genes that mediate manganese-systemic responses and found a highly correlated and modulated network associated with calcium dyshomeostasis and cellular stress

Screening for Developmental Neurotoxicity Using PC12 Cells: Comparisons of Organophosphates with a Carbamate, an Organochlorine, and Divalent Nickel

BACKGROUND: In light of the large number of chemicals that are potential developmental neurotoxicants, there is a need to develop rapid screening techniques. OBJECTIVES: We exposed undifferentiated and differentiating neuronotypic PC12 cells to different organophosphates (chlorpyrifos, diazinon, parathion), a carbamate (physostigmine), an organochlorine (dieldrin), and a metal (divalent nickel; Ni(2+)) and examined indices of cell replication and differentiation for both short- and long-term exposures. RESULTS: In undifferentiated cells, all the agents inhibited DNA synthesis, with the greatest effect for diazinon, but physostigmine eventually produced the largest deficits in the total number of cells after prolonged exposure. The onset of differentiation intensified the adverse effects on DNA synthesis and changed the rank order in keeping with a shift away from noncholinergic mechanisms and toward cholinergic mechanisms. Differentiation also worsened the effects of each agent on cell number after prolonged exposure, whereas cell growth was not suppressed, nor were there any effects on viability as assessed with trypan blue. Nevertheless, differentiating cells displayed signs of oxidative stress from all of the test compounds except Ni(2+), as evidenced by measurements of lipid peroxidation. Finally, all of the toxicants shifted the transmitter fate of the cells away from the cholinergic phenotype and toward the catecholaminergic phenotype. CONCLUSIONS: These studies point out the feasibility of developing cell-based screening methods that enable the detection of multiple end points that may relate to mechanisms associated with developmental neurotoxicity, revealing some common targets for disparate agents