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21.
Badria B El Sayed Colin A Malcolm Ahmed Babiker Elfatih M Malik Mohammed AH El Tayeb Nageeb S Saeed Abdel Hameed D Nugud Bart GJ Knols 《Malaria journal》2009,8(Z2):S3
The global malaria situation, especially in Africa, and the problems frequently encountered in chemical control of vectors such as insecticide resistance, emphasize the urgency of research, development and implementation of new vector control technologies that are applicable at regional and local levels. The successful application of the sterile insect technique (SIT) for the control of the New World screwworm Cochliomyia hominivorax and several species of fruit flies has given impetus to the use of this method for suppression or elimination of malaria vectors in some areas of Africa including Northern State of Sudan. The research and development phase of the Northern State feasibility study has been started. Sudanese stakeholders are working side-by-side with the International Atomic Energy Agency in the activities of this important phase. Several ethical, legal and social issues associated with this approach arose during this phase of the project. They need to be seriously considered and handled with care. In this paper, these issues are described, and the current and proposed activities to overcome potential hurdles to ensure success of the project are listed. 相似文献
22.
Use of the KlADH4 Promoter for Ethanol-Dependent Production of Recombinant Human Serum Albumin in Kluyveromyces lactis
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Michele Saliola Cristina Mazzoni Nicola Solimando Alessandra Cris Claudio Falcone Gerard Jung Reinhard Fleer 《Applied microbiology》1999,65(1):53-60
KlADH4 is a gene of Kluyveromyces lactis encoding a mitochondrial alcohol dehydrogenase activity which is specifically induced by ethanol. The promoter of this gene was used for the expression of heterologous proteins in K. lactis, a very promising organism which can be used as an alternative host to Saccharomyces cerevisiae due to its good secretory properties. In this paper we report the ethanol-driven expression in K. lactis of the bacterial β-glucuronidase and of the human serum albumin (HSA) genes under the control of the KlADH4 promoter. In particular, we studied the extracellular production of recombinant HSA (rHSA) with integrative and replicative vectors and obtained a significant increase in the amount of the protein with multicopy vectors, showing that no limitation of KlADH4 trans-acting factors occurred in the cells. By deletion analysis of the promoter, we identified an element (UASE) which is sufficient for the induction of KlADH4 by ethanol and, when inserted in the respective promoters, allows ethanol-dependent activation of other yeast genes, such as PGK and LAC4. We also analyzed the effect of medium composition on cell growth and protein secretion. A clear improvement in the production of the recombinant protein was achieved by shifting from batch cultures (0.3 g/liter) to fed-batch cultures (1 g/liter) with ethanol as the preferred carbon source. 相似文献
23.
Linda May Anita HJ van den Biggelaar David van Bodegom Hans J Meij Anton JM de Craen Joseph Amankwa Marijke Fr?lich Maris Kuningas Rudi GJ Westendorp 《Immunity & ageing : I & A》2009,6(1):7
Background-
The innate immune system plays an important role in the recognition and induction of protective responses against infectious pathogens, whilst there is increasing evidence for a role in mediating chronic inflammatory diseases at older age. Despite indications that environmental conditions can influence the senescence process of the adaptive immune system, it is not known whether the same holds true for the innate immune system. Therefore we studied whether age-related innate immune responses are similar or differ between populations living under very diverse environmental conditions. 相似文献24.
W Richard Mukabana Khadija Kannady G Michael Kiama Jasper N Ijumba Evan M Mathenge Ibrahim Kiche Gamba Nkwengulila Leonard Mboera Deo Mtasiwa Yoichi Yamagata Ingeborg van Schayk Bart GJ Knols Steven W Lindsay Marcia Caldas de Castro Hassan Mshinda Marcel Tanner Ulrike Fillinger Gerry F Killeen 《Malaria journal》2006,5(1):1-14
Background
Malaria imposes significant costs on households and the poor are disproportionately affected. However, cost data are often from quantitative surveys with a fixed recall period. They do not capture costs that unfold slowly over time, or seasonal variations. Few studies investigate the different pathways through which malaria contributes towards poverty. In this paper, a framework indicating the complex links between malaria, poverty and vulnerability at the household level is developed and applied using data from rural Kenya.Methods
Cross-sectional surveys in a wet and dry season provide data on treatment-seeking, cost-burdens and coping strategies (n = 294 and n = 285 households respectively). 15 case study households purposively selected from the survey and followed for one year provide in-depth qualitative information on the links between malaria, vulnerability and poverty.Results
Mean direct cost burdens were 7.1% and 5.9% of total household expenditure in the wet and dry seasons respectively. Case study data revealed no clear relationship between cost burdens and vulnerability status at the end of the year. Most important was household vulnerability status at the outset. Households reporting major malaria episodes and other shocks prior to the study descended further into poverty over the year. Wealthier households were better able to cope.Conclusion
The impacts of malaria on household economic status unfold slowly over time. Coping strategies adopted can have negative implications, influencing household ability to withstand malaria and other contingencies in future. To protect the poor and vulnerable, malaria control policies need to be integrated into development and poverty reduction programmes. 相似文献25.
The mobility of phospolipids in free-standing and supported membranes was investigated on the level of individual molecules. For the analysis of trajectories a new statistical treatment was developed that permitted us to clearly distinguish different types of diffusional motion. A freely diffusing subfraction of lipids within supported membranes was identified. Its mobility was characterized by a mean lateral diffusion constant of D(supp) = 4.6 &mgr;m(2)/s. In comparison, the mobility of lipids embedded in "free-standing" planar membranes yielded an increase in the mean diffusion constant by a factor of 4.5, D(free) = 20.6 &mgr;m(2)/s. This increase is attributed to the ultrathin (</=1 nm) lubricating water layer between membranes and glass support. 相似文献
26.
J Kindermann Y El-Ayouti GJ Samuels CP Kubicek 《Fungal genetics and biology : FG & B》1998,24(3):298-309
Sequences of the internal transcribed spacer region 1 (ITS1) of the ribosomal DNA were used to determine the phylogenetic relationships of species of Trichoderma sect. Pachybasium. To this end, 85 strains-including all the available ex-type strains-were analyzed. Parsimony analysis demonstrated that the section is nonmonophyletic, distributing the 85 strains among three main groups that were supported by bootstrap values. Group A comprises two clades (A1 and A2), with A1 including T. polysporum, T. piluliferum, and T. minutisporum, while A2 included T. hamatum, T. pubescens, and T. strigosum in addition to species previously included in sect. Trichoderma (i.e., T. viride, T. atroviride, and T. koningii). The ex-type strain of T. fasciculatum formed a separate branch basal to clade A. Clade B contained the sect. Pachybasium members T. harzianum, T. fertile, T. croceum, T. longipile, T. strictipile, T. tomentosum, T. oblongisporum, T. flavofuscum, T. spirale, and the anamorphs of Hypocrea semiorbis and H. cf. gelatinosa. Sequence differences among clades A1, A2, and B were in the same order of magnitude as between each of them and T. longibrachiatum, which was used as an outgroup in these analyses. Sequence differences within clades A1, A2, and B were considerably smaller: in some cases (i.e., T. virens and T. flavofuscum; T. strictipile and H. cf. gelatinosa), the ITS1-sequences were identical, suggesting conspecifity. In other cases (e.g., T. crassum and T. longipile; T. harzianum, T. inhamatum, T. croceum, T. fertile, and H. semiorbis; T. hamatum and T. pubescens; and T. viride, T. atroviride, and T. koningii) differences were in the range of 1-3 nt only, suggesting a very close phylogenetic relationship. The sequence of a previously described aggressive mushroom competitor group of T. harzianum strains (Th2) was strikingly different from that of the ex-type strain of T. harzianum and closely related species and is likely to be a separate species. Copyright 1998 Academic Press. 相似文献
27.
Summary A method to detect low levels of interstrand cross-links in DNA of Saccharomyces cerevisiae is described. Isopycnic ultracentrifugation of alkali-treated, unpurified Eaton press homogenates allows the detection of less than one cross-link per yeast chromosome. Efficient separation of single-and double-stranded DNA requires low cell density and addition of glycerol during homogenization. Using a yeast strain defective in excision repair, a dose dependent formation of interstrand cross-links after treatment of cells with biological doses of nitrogen mustard. Triaziquone and Chloramubil could be demonstrated. The most powerful of these alkylating agents is Triaziquone: half of the DNA molecules are shown to be cross-linked after a 12 min exposure to 9×10-9 g/ml of the drug. The cross-linking reaction continues after excessive alkylating agent is removed. After having reached a maximum the fraction continues after excessive alkylating agent is removed. After having reached a maximum the fraction of renaturable DNA decreases upon further incubation. The speed of this after-reaction depends on temperature: 48 h after the end of treatment renaturability of DNA has almost completely disappeared when cells are kept at 36° C. 相似文献
28.
Sequence of the Kluyveromyces lactis beta-galactosidase: comparison with prokaryotic enzymes and secondary structure analysis. 总被引:5,自引:0,他引:5
The LAC4 gene encoding the beta-galactosidase (beta Gal) of the yeast, Kluyveromyces lactis, was cloned on a 7.2-kb fragment by complementation of a lacZ-deficient Escherichia coli strain. The nucleotide sequence of the structural gene, with 42 bp and 583 bp of the 5'- and 3'-flanking sequences, respectively, was determined. The deduced amino acid (aa) sequence of the K. lactis beta Gal predicts a 1025-aa polypeptide with a calculated M(r) of 117618 and reveals extended sequence homologies with all the published prokaryotic beta Gal sequences. This suggests that the eukaryotic beta Gal is closely related, evolutionarily and structurally, to the prokaryotic beta Gal's. In addition, sequence similarities were observed between the highly conserved N-terminal two-thirds of the beta Gal and the entire length of the beta-glucuronidase (beta Glu) polypeptides, which suggests that beta Glu is clearly related, structurally and evolutionarily, to the N-terminal two-thirds of the beta Gal. The structural analysis of the beta Gal alignment, performed by mean secondary structure prediction, revealed that most of the invariant residues are located in turn or loop structures. The location of the invariant residues is discussed with respect to their accessibility and their possible involvement in the catalytic process. 相似文献
29.
The viscosity of an exocellular polysaccharide (EPS) produced by the bacterium Lactococcus lactis subsp. cremoris B40 was studied in aqueous solution at an ionic strength of 0.10M. First, the zero‐shear viscosity was determined as a function of the concentration. From the data in the low concentration range, the intrinsic viscosity was determined. In addition, the shear‐thinning behavior was measured at several concentrations. By combining existing theories, a new equation is proposed that describes and predicts the intrinsic viscosity and the concentration dependence of the (zero‐shear) viscosity of B40 EPS solutions from the molar mass and the hydrodynamic radius of the polysaccharide. Based on the Rouse theory, the shear‐rate dependence of the viscosity also could be described and predicted from the molecular characteristics, i.e., molar mass and radius of gyration. It is shown that these equations can be applied to all random coil polysaccharides. © 1999 John Wiley & Sons, Inc. Biopoly 50: 641–646, 1999 相似文献
30.
Nonglucosylated oligosaccharides are transferred to protein in MI8-5 Chinese hamster ovary cells 总被引:3,自引:2,他引:1
A CHO mutant MI8-5 was found to synthesize Man9-GlcNAc2-P-P-dolichol rather
than Glc3Man9GlcNAc2-P-P-dolichol as the oligosaccharide-lipid intermediate
in N-glycosylation of proteins. MI8-5 cells were incubated with labeled
mevalonate, and the prenol was found to be dolichol. The mannose-labeled
oligosaccharide released from oligosaccharide-lipid of MI8-5 cells was
analyzed by HPLC and alpha-mannosidase treatment, and the data were
consistent with a structure of Man9GlcNAc2. In addition, MI8-5 cells did
not incorporate radioactivity into oligosaccharide- lipid during an
incubation with tritiated galactose, again consistent with MI8-5 cells
synthesizing an unglucosylated oligosaccharide-lipid. MI8-5 cells had
parental levels of glucosylphosphoryldolichol synthase activity. However,
in two different assays, MI8-5 cells lacked dolichol-
P-Glc:Man9GlcNAc2-P-P-dolichol glucosyltransferase activity. MI8-5 cells
were found to synthesize glucosylated oligosaccharide after they were
transfected with Saccharomyces cerevisiae ALG 6, the gene for
dolichol-P-Glc:Man9GlcNAc2-P-P-dolichol glucosyltransferase. MI8-5 cells
were found to incorporate mannose into protein 2-fold slower than parental
cells and to approximately a 2-fold lesser extent.
相似文献