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1.
Goats and some sheep synthesize a juvenile hemoglobin, Hb C (alpha 2 beta
C2), at birth and produce this hemoglobin exclusively during severe anemia.
Sheep that synthesize this juvenile hemoglobin are of the A haplotype.
Other sheep, belonging to a separate group, the B haplotype, do not
synthesize hemoglobin C and during anemia continue to produce their adult
hemoglobin. To understand the basis for this difference we have determined
the structural organization of the beta- globin locus of B-type sheep by
constructing and isolating overlapping genomic clones. These clones have
allowed us to establish the linkage map 5' epsilon I-epsilon II-psi beta
I-beta B-epsilon III-epsilon IV- psi beta II-beta F3' in this haplotype.
Thus, B sheep lack four genes, including the BC gene, and have only eight
genes, compared with the 12 found in the goat globin locus. The goat
beta-globin locus is as follows: 5' epsilon I-epsilon II-psi beta X-beta
C-epsilon III-epsilon IV-psi beta Z-beta A-epsilon V-epsilon VI-psi beta
Y-beta F3'. Southern blot analysis of A-type sheep reveals that these
animals have a beta- globin locus similar to that of goat, i.e., 12 globin
genes. Thus, the beta-globin locus of B-haplotype sheep resembles that of
cows and may have retained the duplicated locus of the ancestor of cows and
sheep. Alternatively, the B-sheep locus arrangement may be the result of a
deletion of a four-gene set from the triplicated locus.
相似文献
2.
Two groups of asclepains have been isolated from Asclepias syriaca L. (milk-weed) latex and a representative of each has been purified. Asclepains A3 and B5 are homogeneous proteins with molecular weights of 23 000 and 21 000, respectively. Both require a reducing and chelating agent for maximum activity and hydrolyze ester, amide and peptide bonds. The optimum pH for hydrolysis of casein is 7.5 to 8.5 for asclepain A3 and 7.0 to 7.5 for asclepain B5. Both enzymes are autolytic when active and are inhibited by p-chloromercuribenzoate, iodoacetic acid and sodium tetrathionate. Asclepains A3 and B5 each contain one titratable SH group per molecule and no bound carbohydrate. Each of the two enzymes has leucine as the N-terminal amino acid. There are notable differences in their amino acid compositions. 相似文献
3.
Gold salts and phenylbutazone selectively inhibit the synthesis of PGF2α and PGE2 respectively. Lowered production of one prostaglandin species is accompanied by an increased production of the other. Selective inhibition by these drugs was observed in the presence of adrenaline, reduced glutathione and copper sulphate under conditions when most anti-inflammatory compounds inhibited PGE2 and PGF2α syntheses equally. It is postulated that selective inhibitors may have a different mode of action
and beneficial effects may be related to the endogenous ratio of PGE to PGF required for normal function. 相似文献
4.
5.
Two silicone coatings have been evaluated for barnacle adhesion. One coating is an unfilled hydrosilation cured polydimethylsiloxane (PDMS) network, while the other is a room temperature vulcanized (RTV), filled, ethoxysiloxane cured PDMS elastomer, RTV11?. The adhesion strength of one species of barnacle, Balanus eburneus, to the hydrosilation coatings is in the range of 0.37–0.60 kg cm‐2 while the corresponding range for RTV11 is 0.64–0.90 kg cm‐2. The easier release of B. eburneus from the hydrosilation cured network compared to RTV11 is discussed in relationship to differences in bulk and surface properties. Preliminary results suggest bulk modulus may be the most important parameter in determining barnacle adhesion strength. In light or mechanical property analysis, a re‐evaluation of surface properties and chemical stability is presented. 相似文献
6.
This study documents renal biochemistry during hypothermic machine perfusion of kidneys. It is intended to demonstrate that a comprehensive evaluation of organ viability during ex-vivo preservation is needed to increase the number of organs available for transplantation and to reduce the current renal discard rate. Porcine kidneys were hypothermically machine perfused for 72 h with either Unisol-UHK or Belzer-Machine Perfusion Solution, (Belzer-MPS). Renal perfusate samples were periodically collected and biochemically analyzed. Significant differences were measured in the renal metabolic activity between the two experimental groups while similar values for traditional parameters such as renal flow rate and vascular resistance values were recorded. The effluent of UHK perfused kidneys showed strong metabolites and NH(4)(+) dynamics (P<0.05 vs. baseline), while the Belzer-MPS kidneys metabolic activity led to little or no change of the effluent biochemistry relative to baseline. 相似文献
7.
Vitreous cryopreservation maintains the function of vascular grafts 总被引:16,自引:0,他引:16
Avoidance of ice formation during cooling can be achieved by vitrification, which is defined as solidification in an amorphous glassy state that obviates ice nucleation and growth. We show that a vitrification approach to storing vascular tissue results in markedly improved tissue function compared with a standard method involving freezing. The maximum contractions achieved in vitrified vessels were >80% of fresh matched controls with similar drug sensitivities, whereas frozen vessels exhibited maximal contractions below 30% of controls and concomitant decreases in drug sensitivity. In vivo studies of vitrified vessel segments in an autologous transplant model showed no adverse effects of vitreous cryopreservation compared with fresh tissue grafts. 相似文献
8.
With the development of cell-based assays and therapies, the purity of reagents used to grow and maintain cells has become
much more important. In particular, the use of fetal calf serum for culturing cells presents a direct path for potential contamination
of cell cultures. In recent years, much research has focused on the development of serum-free culturing systems, not only
to alleviate difficulties due to availability and cost of fetal calf serum but also to prevent the transmission of potentially
fatal diseases to human patients. Additionally, methods need to be developed for long-term storage of cell stocks that also
reduce the risk of exposure to harmful diseases. As most methods employ fetal calf serum in their freezing formulations, solutions
that avoid the use of fetal calf serum while providing equivalent or better recovery of cells upon thawing would be ideal.
In this study, two vascular cell lines have been cryopreserved as adherent cell populations in two widely used cryoprotectants,
dimethyl sulfoxide and 1,2-propanediol, and two vehicle solutions, Euro-Collins and Unisol-cryoprotectant vehicle specifically
formulated for the maintenance of cell homeostasis at temperatures below 37° C. The addition of serum to these formulations
was also evaluated to determine if its presence provided any additional benefit to the cells during cryopreservation. The
results demonstrated that using vehicle solutions designed for lower temperatures produced viable cells that retained cell
population viability values up to 75% of unfrozen controls. These results also demonstrated that including serum in the formulation
provided no additional benefit to the cells and in some cases actually produced lower cell viability after cryopreservation.
In conclusion, the development of solutions designed for low-temperature storage of cells provides a viable alternative to
more conventional cryopreservation protocols and eliminates the necessity of including serum in these formulations. 相似文献
9.
Brockbank KG Campbell LH Greene ED Brockbank MC Duman JG 《In vitro cellular & developmental biology. Animal》2011,47(3):210-217
The study of mechanisms by which animals tolerate environmental extremes may provide strategies for preservation of living mammalian materials. Animals employ a variety of compounds to enhance their survival, including production of disaccharides, glycerol, and antifreeze compounds. The cryoprotectant glycerol was discovered before its role in amphibian survival. In the last decade, trehalose has made an impact on freezing and drying methods for mammalian cells. Investigation of disaccharides was stimulated by the variety of organisms that tolerate dehydration stress by accumulation of disaccharides. Several methods have been developed for the loading of trehalose into mammalian cells, including inducing membrane lipid-phase transitions, genetically engineered pores, endocytosis, and prolonged cell culture with trehalose. In contrast, the many antifreeze proteins (AFPs) identified in a variety of organisms have had little impact. The first AFPs to be discovered were found in cold water fish; their AFPs have not found a medical application. Insect AFPs function by similar mechanisms, but they are more active and recombinant AFPs may offer the best opportunity for success in medical applications. For example, in contrast to fish AFPs, transgenic organisms expressing insect AFPs exhibit reduced ice nucleation. However, we must remember that nature's survival strategies may include production of AFPs, antifreeze glycolipids, ice nucleators, polyols, disaccharides, depletion of ice nucleators, and partial desiccation in synchrony with the onset of winter. We anticipate that it is only by combining several natural low temperature survival strategies that the full potential benefits for mammalian cell survival and medical applications can be achieved. 相似文献
10.
Gibson DS Blelock S Brockbank S Curry J Healy A McAllister C Rooney ME 《Journal of proteome research》2006,5(8):1988-1995
The synovial fluid proteome in juvenile idiopathic arthritis was investigated to isolate joint-specific biomarkers that are expressed in patients displaying recurrent joint inflammation. To identify the synovial specific proteome, matched synovial fluid and plasma samples were subjected to protein separation by 2-dimension electrophoresis (2DE). Forty-three protein spots, overexpressed in the joint, were identified. Synovial fluids from children with single-event knee joint inflammation were then compared with a group with recurrent knee disease. Nine synovial specific proteins were significantly differentially expressed in the recurrent group. Proteolytic fragments of collagen X, fibrin beta-chain, and T-cell receptor alpha-region have been identified among this protein cluster. Putative biomarkers, overexpressed in the joint and differentially expressed in children with recurrent joint inflammation, have been identified. These proteins may play a significant role determining the pathological state within the chronically inflamed joint and influence disease progression in JIA. This is the first study of the synovial proteome in children. 相似文献