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Alone DP Tiwari AK Mandal L Li M Mechler BM Roy JK 《The International journal of developmental biology》2005,49(7):873-879
In an effort to identify the role of Rab11, a small GTP binding protein, during Drosophila differentiation, phenotypic manifestations associated with different alleles of Rab11 were studied. The phenotypes ranged from eye-defects, bristle abnormalities and sterility to lethality during various developmental stages. In this paper, our focus is targeted on eye defects caused by Rab11 mutations. A novel P-element insertion in the Rab11 locus, Rab11mo, displayed characteristic retinal anomalies, which could be reverted by P-element excision and expression of Rab11+ transgenes. During larval development, Rab11 is widely synthesized in photoreceptor cells and localizes to the rhabdomeres and lamina neuropil in adult eyes. Photoreceptors and associated bristles failed to be formed in homozygous clones generated in Rab11EP(3)3017 eyes. Decreased levels of Rab11 protein and increased cell death in Rab11mo third-instar larval eye-antennal discs suggest that the retinal defects originate during larval development. Our data indicate a requirement for Rab11 in ommatidial differentiation during Drosophila eye development. 相似文献
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A microsatellite-based consensus linkage map for species of Eucalyptus and a novel set of 230 microsatellite markers for the genus 总被引:1,自引:0,他引:1
Rosana PV Brondani Emlyn R Williams Claudio Brondani Dario Grattapaglia 《BMC plant biology》2006,6(1):20-16
Background
Eucalypts are the most widely planted hardwood trees in the world occupying globally more than 18 million hectares as an important source of carbon neutral renewable energy and raw material for pulp, paper and solid wood. Quantitative Trait Loci (QTLs) in Eucalyptus have been localized on pedigree-specific RAPD or AFLP maps seriously limiting the value of such QTL mapping efforts for molecular breeding. The availability of a genus-wide genetic map with transferable microsatellite markers has become a must for the effective advancement of genomic undertakings. This report describes the development of a novel set of 230 EMBRA microsatellites, the construction of the first comprehensive microsatellite-based consensus linkage map for Eucalyptus and the consolidation of existing linkage information for other microsatellites and candidate genes mapped in other species of the genus. 相似文献4.
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JB Parentes-Vieira PV Lopes-Costa CG Pires AR dos Santos JD Pereira-Filho BB da Silva 《International Seminars in Surgical Oncology : ISSO》2007,4(1):22
Background
The objective of this study was to evaluate angiogenesis according to CD34 antigen expression in estrogen receptor (ER)-positive and negative breast carcinomas.Methods
This study comprised 64 cases of infiltrating ductal carcinoma in postmenopausal women divided into two groups: Group A: ER-positive, n = 35; and Group B: ER-negative, n = 29. The anti-CD34 monoclonal antibody was used as a marker for endothelial cells. Microvessel count was carried out in 10 fields per slide using a 40× objective lens (magnification 400×). Statistical analysis of the data was performed using Student's t-test (p < 0.05).Results
The mean number of vessels stained with the anti-CD34 antibody in the estrogen receptor-positive and negative tumors was 23.51 ± 1.15 and 40.24 ± 0.42, respectively. The number of microvessels was significantly greater in the estrogen receptor-negative tumors (p < 0.001).Conclusion
ER-negative tumors have significantly greater CD34 antigen expression compared to ER-positive tumors.6.
Comparative analysis of the zeta-crystallin/quinone reductase gene in guinea pig and mouse 总被引:1,自引:0,他引:1
Gonzalez P; Hernandez-Calzadilla C; Rao PV; Rodriguez IR; Zigler JS Jr; Borras T 《Molecular biology and evolution》1994,11(2):305-315
zeta-Crystallin is a novel nicotinamide adenine dinucleotide
phosphate:quinone reductase, present at enzymatic levels in various tissues
of different species, which is highly expressed in the lens of some
hystricomorph rodents and camelids. We report here the complementary DNA
(cDNA) cloning of zeta-crystallin from liver libraries in guinea pig (Cavia
porcellus), where zeta-crystallin is highly expressed in the lens, and in
the laboratory mouse (Mus musculus), where expression in the lens occurs
only at enzymatic levels. A 5' untranslated sequence different from the one
previously reported for the guinea pig lens cDNA was found in these clones.
We also report the isolation of genomic clones including the complete
guinea pig zeta-crystallin gene and the 5' region of this gene in mouse.
These results show the presence of two promoters in the guinea pig
zeta-crystallin gene, one responsible for expression at enzymatic levels
and the other responsible for the high expression in the lens. The guinea
pig lens promoter is not present in the mouse gene. This is the first
example in which the recruitment of an enzyme as a lens crystallin can be
explained by the acquisition of an alternative lens- specific promoter.
相似文献
7.
IB Masters MM Eastburn PW Francis R Wootton PV Zimmerman RS Ware AB Chang 《Respiratory research》2005,6(1):16
Background
Flexible video bronchoscopes, in particular the Olympus BF Type 3C160, are commonly used in pediatric respiratory medicine. There is no data on the magnification and distortion effects of these bronchoscopes yet important clinical decisions are made from the images. The aim of this study was to systematically describe the magnification and distortion of flexible bronchoscope images taken at various distances from the object.Methods
Using images of known objects and processing these by digital video and computer programs both magnification and distortion scales were derived.Results
Magnification changes as a linear function between 100 mm (×1) and 10 mm (×9.55) and then as an exponential function between 10 mm and 3 mm (×40) from the object. Magnification depends on the axis of orientation of the object to the optic axis or geometrical axis of the bronchoscope. Magnification also varies across the field of view with the central magnification being 39% greater than at the periphery of the field of view at 15 mm from the object. However, in the paediatric situation the diameter of the orifices is usually less than 10 mm and thus this limits the exposure to these peripheral limits of magnification reduction. Intraclass correlations for measurements and repeatability studies between instruments are very high, r = 0.96. Distortion occurs as both barrel and geometric types but both types are heterogeneous across the field of view. Distortion of geometric type ranges up to 30% at 3 mm from the object but may be as low as 5% depending on the position of the object in relation to the optic axis.Conclusion
We conclude that the optimal working distance range is between 40 and 10 mm from the object. However the clinician should be cognisant of both variations in magnification and distortion in clinical judgements. 相似文献8.
Heat labile enterotoxin from enterotoxigenic Escherichia coli is similar to cholera toxin (CT) and is a leading cause of diarrhea in developing countries. It consists of an enzymatically active A subunit (LTA) and a carrier pentameric B subunit (LTB). In the current study, we evaluated the importance of the N-terminal region of LTB by mutation analysis. Deletion of the glutamine (ΔQ3) residue and a substitution mutation E7G in the α1 helix region led to defects in LTB protein secretion. Deletion of the proline residue (ΔP2) caused a decrease in α helicity. The ΔP2 mutant affected GM1 ganglioside receptor binding activity without affecting LTB pentamer formation. Upon refolding/reassembly, the ΔP2 mutant showed defective biological activity. The single substitution mutation (E7D) strengthened the helix, imparting structural stability and thereby improved the GM1 ganglioside receptor binding activity. Our results demonstrate the important role of N-terminal α1 helix in maintaining the structural stability and the integrity of GM1 ganglioside receptor binding activity. 相似文献
9.
Evidence for independent recruitment of zeta-crystallin/quinone reductase (CRYZ) as a crystallin in camelids and hystricomorph rodents 总被引:3,自引:2,他引:1
Zeta-crystallin/quinone reductase (CRYZ) is an NADPH oxidoreductase
expressed at very high levels in the lenses of two groups of mammals:
camelids and some hystricomorph rodents. It is also expressed at very low
levels in all other species tested. Comparative analysis of the mechanisms
mediating the high expression of this enzyme/crystallin in the lens of the
Ilama (Lama guanacoe) and the guinea pig (Cavia porcellus) provided
evidence for independent recruitment of this enzyme as a lens crystallin in
both species and allowed us to elucidate for the first time the mechanism
of lens recruitment of an enzyme- crystallin. The data presented here show
that in both species such recruitment most likely occurred through the
generation of new lens promoters from nonfunctional intron sequences by the
accumulation of point mutations and/or small deletions and insertions.
These results further support the idea that recruitment of CRYZ resulted
from an adaptive process in which the high expression of CRYZ in the lens
provides some selective advantage rather than from a purely neutral
evolutionary process.
相似文献
10.
Roll-Mecak A Alone P Cao C Dever TE Burley SK 《The Journal of biological chemistry》2004,279(11):10634-10642
The x-ray structure of the gamma-subunit of the heterotrimeric translation initiation factor eIF2 has been determined to 2.4-A resolution. eIF2 is a GTPase that delivers the initiator Met-tRNA to the P site on the small ribosomal subunit during a rate-limiting initiation step in translation. The structure of eIF2gamma closely resembles that of EF1A.GTP, consisting of an N-terminal G domain followed by two beta-barrels arranged in a closed configuration with domain II packed against the G domain in the vicinity of the Switch regions. The G domain of eIF2gamma has an unusual zinc ribbon motif, not previously found in other GTPases. Structure-based site-directed mutagenesis was used to identify two adjacent features on the surface of eIF2gamma that bind the alpha-subunit and Met-tRNA(i)(Met), respectively. These structural, biochemical, and genetic results provide new insights into eIF2 ternary complex assembly. 相似文献