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321.
During vertebrate development, the thyroid gland undergoes a unique relocalisation from its site of induction to a distant species-specific position in the cervical mesenchyme. We have analysed thyroid morphogenesis in wild-type and mutant zebrafish and mice, and find that localisation of growing thyroid tissue along the anteroposterior axis in zebrafish is linked to the development of the ventral aorta. In grafting experiments, ectopic vascular cells influence the localisation of thyroid tissue cell non-autonomously, showing that vessels provide guidance cues in zebrafish thyroid morphogenesis. In mouse thyroid development, the midline primordium bifurcates and two lobes relocalise cranially along the bilateral pair of carotid arteries. In hedgehog-deficient mice, thyroid tissue always develops along the ectopically and asymmetrically positioned carotid arteries, suggesting that, in mice (as in zebrafish), co-developing major arteries define the position of the thyroid. The similarity between zebrafish and mouse mutant phenotypes further indicates that thyroid relocalisation involves two morphogenetic phases, and that variation in the second phase accounts for species-specific differences in thyroid morphology. Moreover, the involvement of vessels in thyroid relocalisation sheds new light on the interpretation of congenital thyroid defects in humans.  相似文献   
322.
PPAR ligands with varied subtype selectivity have been synthesized using an achiral aminomethyl dihydrocinnamate template. Several compounds in this series have demonstrated potent plasma glucose and triglyceride lowering capability in rodent models of type 2 diabetes.  相似文献   
323.
Needle‐free powder injectors using a supersonic gas jet to force powder particles into the skin are suitable devices for the reliable delivery of powdered vaccines into viable epidermis. The peculiarities of the injection mechanism lead to a more comfortable injection for the patient, but in return to an increase in the stress on the pharmaceutical formulation in comparison to conventional injections with needle and syringe. As a lot of the conceivable drugs for needle‐free powder injection, particularly protein vaccines, are very sensitive bio‐molecules with an extremely fragile molecular structure, their resilience to the potential molecule damaging processes during the actuation with the device and the preservation of their biological activity are the crucial factors. Therefore it was the central aim of this work to identify and investigate the reasons for the loss of biological activity. The imaginable responsible process steps were investigated separately and the amounts of activity loss related to them. The manufacture of the powder and the loading of the cassette containing the formulation are examined. Moreover, the effects of static pressure exposition, the stress occurring because of the particle transport through the injector device, inevitably accompanied by impacts and shear stress and the influence of the particle impact with the target, were the focus of this investigation. Furthermore, different formulations of protein in combination with pharmaceutical excipients well‐known for their protein stabilizing effects during the powder manufacture process were examined in regard to their potential suitability to protect protein against the stress occurring throughout the needle‐free injection.  相似文献   
324.
We present an extensive ancient DNA analysis of mainly Neolithic cattle bones sampled from archaeological sites along the route of Neolithic expansion, from Turkey to North-Central Europe and Britain. We place this first reasonable population sample of Neolithic cattle mitochondrial DNA sequence diversity in context to illustrate the continuity of haplotype variation patterns from the first European domestic cattle to the present. Interestingly, the dominant Central European pattern, a starburst phylogeny around the modal sequence, T3, has a Neolithic origin, and the reduced diversity within this cluster in the ancient samples accords with their shorter history of post-domestic accumulation of mutation.  相似文献   
325.
In Europe, the Neolithic transition (8,000–4,000 b.c.) from hunting and gathering to agricultural communities was one of the most important demographic events since the initial peopling of Europe by anatomically modern humans in the Upper Paleolithic (40,000 b.c.). However, the nature and speed of this transition is a matter of continuing scientific debate in archaeology, anthropology, and human population genetics. To date, inferences about the genetic make up of past populations have mostly been drawn from studies of modern-day Eurasian populations, but increasingly ancient DNA studies offer a direct view of the genetic past. We genetically characterized a population of the earliest farming culture in Central Europe, the Linear Pottery Culture (LBK; 5,500–4,900 calibrated b.c.) and used comprehensive phylogeographic and population genetic analyses to locate its origins within the broader Eurasian region, and to trace potential dispersal routes into Europe. We cloned and sequenced the mitochondrial hypervariable segment I and designed two powerful SNP multiplex PCR systems to generate new mitochondrial and Y-chromosomal data from 21 individuals from a complete LBK graveyard at Derenburg Meerenstieg II in Germany. These results considerably extend the available genetic dataset for the LBK (n = 42) and permit the first detailed genetic analysis of the earliest Neolithic culture in Central Europe (5,500–4,900 calibrated b.c.). We characterized the Neolithic mitochondrial DNA sequence diversity and geographical affinities of the early farmers using a large database of extant Western Eurasian populations (n = 23,394) and a wide range of population genetic analyses including shared haplotype analyses, principal component analyses, multidimensional scaling, geographic mapping of genetic distances, and Bayesian Serial Simcoal analyses. The results reveal that the LBK population shared an affinity with the modern-day Near East and Anatolia, supporting a major genetic input from this area during the advent of farming in Europe. However, the LBK population also showed unique genetic features including a clearly distinct distribution of mitochondrial haplogroup frequencies, confirming that major demographic events continued to take place in Europe after the early Neolithic.  相似文献   
326.
A conceptual neural fuzzy model based on adaptive-network based fuzzy inference system, ANFIS, was proposed using available input on-line and off-line operational variables for a sugar factory anaerobic wastewater treatment plant operating under unsteady state to estimate the effluent chemical oxygen demand, COD. The predictive power of the developed model was improved as a new approach by adding the phase vector and the recent values of COD up to 5–10 days, longer than overall retention time of wastewater in the system. History of last 10 days for COD effluent with two-valued phase vector in the input variable matrix including all parameters had more predictive power. History of 7 days with two-valued phase vector in the matrix comprised of only on-line variables yielded fairly well estimations. The developed ANFIS model with phase vector and history extension has been able to adequately represent the behavior of the treatment system.  相似文献   
327.
The acid alpha-mannosidase of Trypanosoma cruzi is a broad-specificity hydrolase involved in the catabolism of glycoconjugates, presumably in the digestive vacuole. We have cloned the alpha-mannosidase gene from a T.cruzi epimastigote genomic library. The alpha-mannosidase gene was determined to be single copy by Southern analysis, and similar sequences were not detected in genomic digests of either Trypanosoma brucei or Leishmania donovani. The coding region was subcloned into the Pichia pastoris expression vector pPICZ, and alpha-mannosidase activity was detected in the medium of induced cultures. The recombinant alpha- mannosidase demonstrated a pH optimum, inhibition by swainsonine, Km, and substrate specificity consistent with the characteristics of the alpha-mannosidase previously purified from T.cruzi epimastigotes. The recombinant enzyme was purified 103-fold from the culture medium of Pichia pastoris and had a native molecular mass of 359 kDa by gel filtration. A combination of SDS-PAGE, deglycosylation with endo H, and NH2-terminal sequencing indicates that the enzyme is originally synthesized as a homodimeric polypeptide that is subsequently cleaved to form a heterotetramer composed of 57 and 46 kDa subunits. A polyclonal antibody raised to the recombinant enzyme was shown to immunoprecipitate the alpha-mannosidase from T.cruzi cell extracts and will be used in future immunolocalization studies.   相似文献   
328.
Polyacrylonitrile film (PAN) surfaces were modified with chemical polymerization of conductive polyaniline (PANI) in the presence of potassium dichromate as an oxidizing agent. The conductive films were used for immobilization of uricase. The surface resistance of the conductive film in this work was found to be 0.97 kΩ/cm. The maximum amount of immobilized enzyme on conductive film containing 2.4% PANI was about 216 μg/cm2. The optimum pH for free and immobilized enzymes was observed at 7.0 and 7.5, respectively. The K m values for free and immobilized uricase were found to be 94 and 138 μM, respectively. V max values were calculated as 1.87 and 1.63 U/mg protein for the free and immobilized enzymes, respectively. Immobilized uricase exhibited ~68% of its original activity even after 2 months of storage at 4 °C while the free enzyme lost its initial activity within 4 weeks.  相似文献   
329.
330.
M Alt  B Fleckenstein  R Grassmann 《Gene》1991,102(2):265-269
The genome of Herpesvirus saimiri, a lymphotropic virus of non-human primates, was used to develop a vector system for transducing foreign genes into primary human T-cells and T-lymphoid cell lines. Recombinant viruses were obtained by homologous recombination of the viral genome with linearized plasmid DNA. The plasmid used contained a fragment of virion DNA, a hygromycin-B-resistance marker (HyR), and a multiple cloning site for the insertion of additional expression cassettes. The resulting recombinants were efficiently enriched and were plaque-purified. The virus mediating HyR and a H. saimiri strain carrying the Geneticin-resistance marker were used to infect the human T-lymphoid cell line Jurkat. Lymphocytes with a double-resistant phenotype were shown to contain the two different H. saimiri recombinants persisting as episomes at high multiplicity. The H. saimiri vector system will be suitable to study cooperating regulatory genes in T-lymphocytes.  相似文献   
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