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111.
Four large (n > 1000) populations of Drosophila melanogaster, derived from control populations maintained on a 3 week discrete generation cycle, were subjected to selection for fast development and early reproduction. Egg to eclosion survivorship and development time and dry weight at eclosion were monitored every 10 generations. Over 70 generations of selection, development time in the selected populations decreased by approximately 36 h relative to controls, a 20% decline. The difference in male and female development time was also reduced in the selected populations. Flies from the selected populations were increasingly lighter at eclosion than controls, with the reduction in dry weight at eclosion over 70 generations of selection being approximately 45% in males and 39% in females. Larval growth rate (dry weight at eclosion/development time) was also reduced in the selected lines over 70 generations, relative to controls, by approximately 32% in males and 24% in females. However, part of this relative reduction was due to an increase in growth rate of the controls populations, presumably an expression of adaptation to conditions in our laboratory. After 50 generations of selection had elapsed, a considerable and increasing pre-adult viability cost to faster development became apparent, with viability in the selected populations being about 22% less than that of controls at generation 70 of selection. 相似文献
112.
Sezen AS Sivaramakrishnan S Hur S Rajamani R Robbins W Nelson BJ 《Journal of biomechanical engineering》2005,127(6):1030-1034
This paper introduces passive wireless telemetry based operation for high frequency acoustic sensors. The focus is on the development, fabrication, and evaluation of wireless, battery-less SAW-IDT MEMS microphones for biomedical applications. Due to the absence of batteries, the developed sensors are small and as a result of the batch manufacturing strategy are inexpensive which enables their utilization as disposable sensors. A pulse modulated surface acoustic wave interdigital transducer (SAW-IDT) based sensing strategy has been formulated. The sensing strategy relies on detecting the ac component of the acoustic pressure signal only and does not require calibration. The proposed sensing strategy has been successfully implemented on an in-house fabricated SAW-IDT sensor and a variable capacitor which mimics the impedance change of a capacitive microphone. Wireless telemetry distances of up to 5 centimeters have been achieved. A silicon MEMS microphone which will be used with the SAW-IDT device is being microfabricated and tested. The complete passive wireless sensor package will include the MEMS microphone wire-bonded on the SAW substrate and interrogated through an on-board antenna. This work on acoustic sensors breaks new ground by introducing high frequency (i.e., audio frequencies) sensor measurement utilizing SAW-IDT sensors. The developed sensors can be used for wireless monitoring of body sounds in a number of different applications, including monitoring breathing sounds in apnea patients, monitoring chest sounds after cardiac surgery, and for feedback sensing in compression (HFCC) vests used for respiratory ventilation. Another promising application is monitoring chest sounds in neonatal care units where the miniature sensors will minimize discomfort for the newborns. 相似文献
113.
Both strong directional selection and faster development are thought to destabilize development, giving rise to greater fluctuating
asymmetry (FA), although there is no strong empirical evidence supporting this assertion. We compared FA in sternopleural
bristle number in four populations ofDrosophila melanogaster successfully selected for faster development from egg to adult, and in four control populations. The fraction of perfectly
symmetric individuals was higher in the selected populations, whereas the FA levels did not differ significantly between selected
and control populations, clearly indicating that directional selection for faster development has not led to increased FA
in sternopleural bristle number in these populations. This may be because: (i) development time and FA are uncorrelated, (ii)
faster development does result in FA, but selection has favoured developmentally stable individuals that can develop fast
and still be symmetrical, or (iii) the increased fraction of symmetric individuals in the selected populations is an artifact
of reduced body size. Although we cannot discriminate among these explanations, our results suggest that the relationship
between development time, FA and fitness may be far more subtle than often thought. 相似文献
114.
Immobilized metal-ion affinity chromatography of human antibodies and their proteolytic fragments 总被引:2,自引:0,他引:2
Todorova-Balvay D Pitiot O Bourhim M Srikrishnan T Vijayalakshmi M 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2004,808(1):57-62
Immobilized metal-ion affinity chromatography (IMAC) performed with four different transition metal ions: copper(II), nickel(II), zinc(II) and cobalt(II), was used to study the adsorption properties of human polyclonal gamma-globulines (IgG), Cohn II-III fractions, and their pepsin cleaved fragments: Fab'2 and F'c. In each case, digested products showed lower affinity for metal ions, as well by decreasing pH elution as by competition with imidazole. An explanation was proposed by the presence of a histidine (His) cluster in the F'c domain of IgGs, identified by computer calculation (accessible surface area (ASA) determination) as the more probable His 433-x-His 435 sequence presented in the CH3 domain of human IgG heavy chain. As shown by IMAC and electrophoresis, F'c and undigested IgG have higher affinity for transition metal ions than Fab'2 fragments and could be then separated in one step by IMAC. When chelated Zn(II) or Co(II) are used as ligands, the Fab'2 fragment could be easily recovered under mild conditions (pH 7) in the non-retained fraction. This approach could be used as a powerful alternative to conventional protein A/G methods for the commercial preparation of non immunogen active Fab'2 fragments. 相似文献
115.
Coffinier Y Vijayalakshmi MA 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2004,808(1):51-56
In this study, we attempted a limited combinatorial approach for designing affinity ligands based on mercaptoheterocyclic components. The template, divinyl sulfone structure (DVS), which was grafted on poly(ethylene vinyl alcohol) (PEVA) hollow fiber membrane, has served for the tethering of different heterocyclic compounds as pyridine, imidazole, purine and pyrimidine rings. Their ability to adsorb specifically IgG in a salt independent manner out of pure IgG solution, mixture of IgG/albumin and human plasma was demonstrated. Mercapto methyl imidazole (MMI) has shown the best adsorption of IgG in terms of binding capacity. No subclass discrimination was observed on all tested ligands except for mercapto methyl pyrimidine where the major IgG subclass adsorbed was IgG3. MMI gave an IgG binding capacity of 100 microg/cm2 of hollow fiber membrane surface area. 相似文献
116.
Chauhan C Dash D Grover D Rajamani J Mukerji M 《Journal of biomolecular structure & dynamics》2002,20(2):253-263
Expansion of GAA repeats in the intron of the frataxin gene is involved in the autosomal recessive Friedreich's ataxia (FRDA). The GAA repeats arise from a stretch of adenine residues of an Alu element. These repeats have a size ranging from 7- 38 in the normal population, and expand to thousands in the affected individuals. The mechanism of origin of GAA repeats, their polymorphism and stability are not well understood. In this study, we have carried out an extensive analysis of GAA repeats at several loci in the humans. This analysis indicates the association of a majority of GAA repeats with the 3' end of an "A" stretch present in the Alu repeats. Further, the prevalence of GAA repeats correlates with the evolutionary age of Alu subfamilies as well as with their relative frequency in the genome. Our study on GAA repeat polymorphism at some loci in the normal population reveals that the length of the GAA repeats is determined by the relative length of the flanking A stretch. Based on these observations, a possible mechanism for origin of GAA repeats and modulatory effects of flanking sequences on repeat instability mediated by DNA triplex is proposed. 相似文献
117.
118.
H. H. Zepik S. Rajamani M.-C. Maurel D. Deamer 《Origins of life and evolution of the biosphere》2007,37(6):495-505
For cellular life to begin on the early Earth, a permeation mechanism would be required to allow polar solutes to enter a
membrane-bounded compartment. A second process - internal polymerization of peptides from amino acid – would also be an essential
step toward the first compartmented metabolic pathways leading to biosynthesis. Here we report a study of amino acid permeation
into lipid vesicles, in which thioglutamic acid penetrated lipid bilayer membranes at rates sufficient to support internal
polymerization reactions. We also investigated spontaneous non-enzymatic polymerization reactions of thioglutamic acid to
form oligopeptides. We found that oligomers up to 11mers are produced in the reaction mixture, and conclude that certain lipid
surfaces can act as catalysts in promoting an oligomerization reaction. These observations are pertinent to understanding
processes by which peptide bond synthesis could take place in primitive cellular life on the early Earth.
H. H. Zepik and S. Rajamani contributed equally to the paper. 相似文献
119.
Lavanya Joshi Meenakshi Ponnana Ramya Sivangala Lakshmi Kiran Chelluri Prathiba Nallari Sitaramaraju Penmetsa Vijayalakshmi Valluri Sumanlatha Gaddam 《PloS one》2015,10(9)
Background
Household contacts of diagnostically established tuberculosis (TB) patients are highly susceptible to disease development. It is surmised that cytokines perhaps play a synergistic and a prognostic role in the activation of the otherwise latent infection in these house hold contacts. Evaluation of the cytokines and any of their inherent polymorphisms might provide a useful diagnostic tool in evaluating the immune regulation and the progression of the disease. The cytokines thus released in a paracrine manner in serum may also provide an indirect measure of the cytokine function.Objective
The present study was aimed to evaluate the levels of TNF-α, IL-10 & IL-6 cytokines and their correlation with genotype variants amongst tuberculosis patients and their household contacts.Methods
The cytokine levels were estimated in serum by enzyme-linked immunosorbent assay (ELISA) and their polymorphisms were studied by amplification refractory mutation system polymerase chain reaction (ARMs PCR) in active pulmonary tuberculosis patients (APTB = 150), household contacts (HHC = 190), and healthy controls (HC = 150).Results
The median values of TNF-α cytokine were significantly high among APTB and HHC compared to HCs (P< 0.0001 and 0.0001). IL-6 levels also were elevated among APTB compared to HHC and HC, and a significant difference was observed between APTB and HHC at P<0.0001; APTB & HC at P< 0.04; HHC & HC at P< 0.01. The IL-10 levels were low in APTB compared to HHC and HCs and no significant difference was observed. TNF-α/IL-10 ratio was significant and indicated Th1 predominance in APTB and HHC. IL-6/IL-10 showed pronounced Th1 expression in APTB and Th2 in HHC and HC. The ROC analysis indicated that both IL-10 and IL-6 can be used to decide the risk of exposed individual to a disease. The results of multivariate analysis indicate that IL-10 (-1082) GA genotype was significantly associated with p<0.028 in APTB. No significant association was observed between genotypes, other serum cytokine levels and clinical characteristics between APTB, HHC and HCs.Conclusion
Large sample size with follow-up at different time points may further illuminate the role of IL-10 and IL-6 cytokines as a prognostic marker in house hold contacts. 相似文献120.
Anu Mary Varghese Aparna Sharma Poojashree Mishra Kalyan Vijayalakshmi Hindalahalli Chandregowda Harsha Talakad N Sathyaprabha Srinivas MM Bharath Atchayaram Nalini Phalguni Anand Alladi Trichur R Raju 《Clinical proteomics》2013,10(1):19