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151.
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153.
Joel Farkas Daehwan Chung Minseok Cha Jennifer Copeland Philip Grayeski Janet Westpheling 《Journal of industrial microbiology & biotechnology》2013,40(1):41-49
Methods for efficient growth and manipulation of relatively uncharacterized bacteria facilitate their study and are essential for genetic manipulation. We report new growth media and culture techniques for Caldicellulosiruptor bescii, the most thermophilic cellulolytic bacterium known. A low osmolarity defined growth medium (LOD) was developed that avoids problems associated with precipitates that form in previously reported media allowing the monitoring of culture density by optical density at 680 nm (OD680) and more efficient DNA transformation by electroporation. This is a defined minimal medium and does not support growth when a carbon source is omitted, making it suitable for selection of nutritional markers as well as the study of biomass utilization by C. bescii. A low osmolarity complex growth medium (LOC) was developed that dramatically improves growth and culture viability during storage, making it a better medium for routine growth and passaging of C. bescii. Both media contain significantly lower solute concentration than previously published media, allowing for flexibility in developing more specialized media types while avoiding the issues of growth inhibition and cell lysis due to osmotic stress. Plating on LOD medium solidified by agar results in ~1,000-fold greater plating efficiency than previously reported and allows the isolation of discrete colonies. These new media represent a significant advance for both genetic manipulation and the study of biomass utilization in C. bescii, and may be applied broadly across the Caldicellulosiruptor genus. 相似文献
154.
Sara Violante Lodewijk IJlst Heleen te Brinke Janet Koster Isabel Tavares de Almeida Ronald J.A. Wanders Fátima V. Ventura Sander M. Houten 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2013,1831(9):1467-1474
Fatty acid β-oxidation may occur in both mitochondria and peroxisomes. While peroxisomes oxidize specific carboxylic acids such as very long-chain fatty acids, branched-chain fatty acids, bile acids, and fatty dicarboxylic acids, mitochondria oxidize long-, medium-, and short-chain fatty acids. Oxidation of long-chain substrates requires the carnitine shuttle for mitochondrial access but medium-chain fatty acid oxidation is generally considered carnitine-independent. Using control and carnitine palmitoyltransferase 2 (CPT2)- and carnitine/acylcarnitine translocase (CACT)-deficient human fibroblasts, we investigated the oxidation of lauric acid (C12:0). Measurement of the acylcarnitine profile in the extracellular medium revealed significantly elevated levels of extracellular C10- and C12-carnitine in CPT2- and CACT-deficient fibroblasts. The accumulation of C12-carnitine indicates that lauric acid also uses the carnitine shuttle to access mitochondria. Moreover, the accumulation of extracellular C10-carnitine in CPT2- and CACT-deficient cells suggests an extramitochondrial pathway for the oxidation of lauric acid. Indeed, in the absence of peroxisomes C10-carnitine is not produced, proving that this intermediate is a product of peroxisomal β-oxidation. In conclusion, when the carnitine shuttle is impaired lauric acid is partly oxidized in peroxisomes. This peroxisomal oxidation could be a compensatory mechanism to metabolize straight medium- and long-chain fatty acids, especially in cases of mitochondrial fatty acid β-oxidation deficiency or overload. 相似文献
155.
Daehwan Chung Joel Farkas Janet Westpheling 《Journal of industrial microbiology & biotechnology》2013,40(5):517-521
We show that a previously annotated hypothetical protein is the transposase of a new and active IS element, ISCahy1, widespread in Caldicellulosiruptor species. Transposition generated an 11-bp direct repeat at the insertion site in Caldicellulosiruptor hydrothermalis, suggesting a cut-and-paste mechanism. The discovery of an active insertion sequence in Caldicellulosiruptor species led to a survey of potential IS elements in the genome sequences of eight Caldicellulosiruptor species that identified several new elements, including one novel to this genus. 相似文献
156.
Elizabeth A. Sinclair Jennifer Verduin Siegfried L. Krauss Jethro Hardinge Janet Anthony Gary A. Kendrick 《Ecological Management & Restoration》2013,14(1):68-71
Seagrass meadows are in decline globally. Although numerous experimental methods have been implemented to restore meadows, few have been successful in the long term. Poor decisions on the sourcing of transplants from donor sites, including poor genetic integration and/or low genetic diversity, may impact on restoration success. However, despite evidence to suggest a positive association between genetic diversity and ecological resilience, there is usually little or no input from genetic data to inform on the genetic management of ecological restoration. Cockburn Sound has seen a 77% decline in seagrass cover since 1967. A transplant trial was conducted between 2004 and 2008 with sprigs of Posidonia australis being planted into a bare sand area. Survival was monitored annually, and in 2012, we compared genetic diversity in this transplant area with the original donor site. Genetic diversity in the restored meadow was very high and comparable to the donor site, with no genetic differentiation detected. The high level of genetic diversity and choice of site may have played an important role in the success of this restoration trial. The observed natural recruits around the site after establishment of transplants suggest that local restoration efforts may improve seafloor habitat and facilitate natural expansion of the meadow. 相似文献
157.
Janet Lee Jeong-Hwa Baek Kyu-Sil Choi Hyun-Soo Kim Hye-Young Park Geun-Hyoung Ha Ho Park Kyo-Won Lee Chang Geun Lee Dong-Yun Yang Hyo Eun Moon Sun Ha Paek Chang-Woo Lee 《Cell cycle (Georgetown, Tex.)》2013,12(3):442-451
Multipotent mesenchymal stem/stromal cells (MSCs) are capable of differentiating into a variety of cell types from different germ layers. However, the molecular and biochemical mechanisms underlying the transdifferentiation of MSCs into specific cell types still need to be elucidated. In this study, we unexpectedly found that treatment of human adipose- and bone marrow-derived MSCs with cyclin-dependent kinase (CDK) inhibitor, in particular CDK4 inhibitor, selectively led to transdifferentiation into neural cells with a high frequency. Specifically, targeted inhibition of CDK4 expression using recombinant adenovial shRNA induced the neural transdifferentiation of human MSCs. However, the inhibition of CDK4 activity attenuated the syngenic differentiation of human adipose-derived MSCs. Importantly, the forced regulation of CDK4 activity showed reciprocal reversibility between neural differentiation and dedifferentiation of human MSCs. Together, these results provide novel molecular evidence underlying the neural transdifferentiation of human MSCs; in addition, CDK4 signaling appears to act as a molecular switch from syngenic differentiation to neural transdifferentiation of human MSCs. 相似文献
158.
Background
Studies conducted in high income countries have shown that anaemia is a common medical condition among older people, but such data are scarce in Africa. The objectives of this study were to estimate the prevalence, types, risk factors and clinical correlates of anaemia in older people.Methods
Participants were aged (≥ 50) years recruited from a general population cohort from January 2012 to January 2013. Blood samples were collected for assessing hemoglobin, serum ferritin, serum vitamin B12, serum folate, C-reactive protein, malaria infection and stool samples for assessment of hookworm infection. HIV status was assessed using an algorithm for HIV rapid testing. Questionnaires were used to collect data on sociodemographic characteristics and other risk factors for anaemia.Results
In total, 1449 people participated (response rate 72.3%). The overall prevalence of anaemia was 20.3 % (95% CI 18.2-22.3%), and this was higher for males (24.1%, 95% CI=20.7-27.7%) than females (17.5%, 95% CI=15.0-20.1%). In males, the prevalence of anaemia increased rapidly with age almost doubling between 50 and 65 years (p-trend<0.001). Unexplained anaemia was responsible for more than half of all cases (59.7%). Anaemia was independently associated with infections including malaria (OR 3.49, 95% CI 1.78-6.82), HIV (OR 2.17, 1.32-3.57) heavy hookworm infection (OR 3.45, 1.73-6.91), low fruit consumption (OR 1.55, 1.05-2.29) and being unmarried (OR 1.37 , 95% CI 1.01-1.89). However, the odds of anaemia were lower among older people with elevated blood pressure (OR 0.47, 95% CI 0.29-0.77).Conclusion
Anaemia control programmes in Uganda should target older people and should include interventions to treat and control hookworms and educational programs on diets that enhance iron absorption. Clinicians should consider screening older people with HIV or malaria for anaemia. Further studies should be done on unexplained anaemia and serum ferritin levels that predict iron deficiency anaemia in older people. 相似文献159.
Nicky McCreesh Andrew Copas Janet Seeley Lisa G. Johnston Pam Sonnenberg Richard J. Hayes Simon D. W. Frost Richard G. White 《PloS one》2013,8(10)
Introduction
Respondent-driven sampling (RDS) is a variant of a link-tracing design intended for generating unbiased estimates of the composition of hidden populations that typically involves giving participants several coupons to recruit their peers into the study. RDS may generate biased estimates if coupons are distributed non-randomly or if potential recruits present for interview non-randomly. We explore if biases detected in an RDS study were due to either of these mechanisms, and propose and apply weights to reduce bias due to non-random presentation for interview.Methods
Using data from the total population, and the population to whom recruiters offered their coupons, we explored how age and socioeconomic status were associated with being offered a coupon, and, if offered a coupon, with presenting for interview. Population proportions were estimated by weighting by the assumed inverse probabilities of being offered a coupon (as in existing RDS methods), and also of presentation for interview if offered a coupon by age and socioeconomic status group.Results
Younger men were under-recruited primarily because they were less likely to be offered coupons. The under-recruitment of higher socioeconomic status men was due in part to them being less likely to present for interview. Consistent with these findings, weighting for non-random presentation for interview by age and socioeconomic status group greatly improved the estimate of the proportion of men in the lowest socioeconomic group, reducing the root-mean-squared error of RDS estimates of socioeconomic status by 38%, but had little effect on estimates for age. The weighting also improved estimates for tribe and religion (reducing root-mean-squared-errors by 19–29%), but had little effect for sexual activity or HIV status.Conclusions
Data collected from recruiters on the characteristics of men to whom they offered coupons may be used to reduce bias in RDS studies. Further evaluation of this new method is required. 相似文献160.
Yiu-fai Cheung Wei Yu Daniel Ka-leung Cheuk Frankie Wai-tsoi Cheng Janet Yee-kwan Yang Jeffrey Ping-wa Yau Karin Ka-huen Ho Chi-kong Li Rever Chak-ho Li Hui-leung Yuen Alvin Siu-cheung Ling Vivian Wing-yi Li Wai-keung Wong Kwong-cheong Tsang Godfrey Chi-fung Chan 《PloS one》2013,8(10)