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11.
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
12.
The vascular endothelial growth factor (VEGF) family: angiogenic factors in health and disease 总被引:6,自引:0,他引:6
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Vascular endothelial growth factors (VEGFs) are a family of secreted polypeptides with a highly conserved receptor-binding cystine-knot structure similar to that of the platelet-derived growth factors. VEGF-A, the founding member of the family, is highly conserved between animals as evolutionarily distant as fish and mammals. In vertebrates, VEGFs act through a family of cognate receptor kinases in endothelial cells to stimulate blood-vessel formation. VEGF-A has important roles in mammalian vascular development and in diseases involving abnormal growth of blood vessels; other VEGFs are also involved in the development of lymphatic vessels and disease-related angiogenesis. Invertebrate homologs of VEGFs and VEGF receptors have been identified in fly, nematode and jellyfish, where they function in developmental cell migration and neurogenesis. The existence of VEGF-like molecules and their receptors in simple invertebrates without a vascular system indicates that this family of growth factors emerged at a very early stage in the evolution of multicellular organisms to mediate primordial developmental functions. 相似文献
13.
Babenko O. V. Saakyan S. V. Brovkina A. F. Kozlova V. M. Strelnikov V. V. Zaletaev D. V. Nemtsova M. V. 《Molecular Biology》2002,36(4):487-492
The spectrum and frequencies of RB1 structural defects were studied in tumors and peripheral blood lymphocytes of patients with various forms of retinoblastoma. Single strand conformation polymorphism (SSCP) and heteroduplex (HA) analyses, along with direct sequencing, revealed 47 mutations, including 24 new ones. Of these, 42.5% were nonsense mutations, 15% were missense mutations, 15% affected splicing sites, and 27.5% were frameshifts resulting from microdeletions or microinsertions. Six polymorphisms were found, including three new ones located in the coding region. Microsatellite analysis with markers Rbint2, Rbint20, D13S262, and D13S284 revealed loss of heterozygosity for at least one marker in 71% tumors. 相似文献
14.
The extent of polylactosamine glycosylation of MDCK LAMP-2 is determined by its Golgi residence time 总被引:2,自引:1,他引:1
The increased polylactosamine glycosylation of LAMP-2 in MDCK cells
cultured for 1 day relative to cells cultured for 3 days has been
correlated with its slower rate of Golgi transit (Nabi and Rodriguez-
Boulan, 1993, Mol. Biol. Cell., 4, 627-635). To determine if the
differential polylactosamine glycosylation of LAMP-2 is a consequence of
glycosyltransferase expression levels, the activities of beta1- 6GlcNAc-TV,
beta1-3GlcNAc-T(i), beta1-2GlcNAc-TI, beta1, 4Gal-T, alpha2- 6sialyl-T, and
alpha2-3sialyl-T were assayed and no significant differences in the
activities of these enzymes in 1 and 3 day cell extracts were detected.
During MDCK epithelial polarization, the Golgi apparatus undergoes
morphological changes and apiconuclear Golgi networks were more evident in
3 day cells. Treatment with nocodazole disrupted Golgi networks and
generated numerous Golgi clusters in both 1 day and 3 day cells. In the
presence of nocodazole the differential migration of LAMP-2 in 1 and 3 day
MDCK cells was maintained and could be eliminated by treatment with
endo-beta-galactosidase, indicating that gross Golgi morphology did not
influence the extent of LAMP-2 polylactosamine glycosylation. Nocodazole
treatment did, however, result in the faster migration of LAMP-2 which was
not due to modification of core N-glycans as the precursor form of the
glycoprotein migrated with an identical molecular size. Following
incubation at 20 degrees C, which prevents the exit of proteins from the
trans-Golgi network, the molecular size of LAMP-2 increased to a similar
extent in both 1 and 3 day MDCK cells. Extending the time of incubation at
20 degrees C did not influence the size of LAMP-2, demonstrating that its
glycosylation is modified not by its retention within the Golgi but rather
by its equivalent slower Golgi passage at the lower temperature in both 1
and 3 day cells. An identical effect was observed in nocodazole treated
cells, demonstrating that Golgi residence time determines the extent of
LAMP-2 polylactosamine glycosylation, even in isolated Golgi clusters.
相似文献
15.
Vascular endothelial growth factors (VEGFs) are a family of secreted polypeptides with a highly conserved receptor-binding
cystine-knot structure similar to that of the platelet-derived growth factors. VEGF-A, the founding member of the family,
is highly conserved between animals as evolutionarily distant as fish and mammals. In vertebrates, VEGFs act through a family
of cognate receptor kinases in endothelial cells to stimulate blood-vessel formation. VEGF-A has important roles in mammalian
vascular development and in diseases involving abnormal growth of blood vessels; other VEGFs are also involved in the development
of lymphatic vessels and disease-related angiogenesis. Invertebrate homologs of VEGFs and VEGF receptors have been identified
in fly, nematode and jellyfish, where they function in developmental cell migration and neurogenesis. The existence of VEGF-like
molecules and their receptors in simple invertebrates without a vascular system indicates that this family of growth factors
emerged at a very early stage in the evolution of multicellular organisms to mediate primordial developmental functions. 相似文献
16.
Vasin B. L. Mal’kova S. V. Osipov M. V. Puzyrev V. N. Saakyan A. T. Starodub A. N. Fedotov S. I. Fronya A. A. Shutyak V. G. 《Plasma Physics Reports》2010,36(13):1255-1260
The optical scheme and design of a four-frequency polarizing microscope intended for simultaneous recording of plasma images
in the wavelength range 0.4–1.1 μm with the spatial resolution 12 μm in the entire spectral range are described. The effectiveness
of such a microscope in studies of plasmas produced on interaction of laser radiation with a target is demonstrated. The plasma
images are obtained at the frequencies ω0, (3/2)ω0, 2ω0, and (5/2)ω0, where ω0 corresponds to the frequency of heating radiation. The transformation coefficient that characterizes the efficiency of conversion
of heating radiation into the 2ω0, (3/2)ω0, and (5/2)ω0 harmonics generated in the plasma is determined. 相似文献
17.
Shahram?SadeghiEmail author Mohammadrezaalavian?Ghavanini Alireza?Ashraf Peyman?Jafari 《BMC neurology》2004,4(1):11
Background
central loop of the gastrocnemius-soleus H-reflex latency (Tc) that looks promising in the diagnosis of S1 radiculopathy; has been investigated in a few studies and only two of them have focused on the constitutional factors affecting it. Although leg length has been shown to contribute to the Tc, the role of age is controversial. More confusing, none of the previously performed studies have used strict criteria to rule out subclinical neuropathy, so the results could be misleading. This study has been performed to determine the influence of leg length and age on Tc among a carefully selected group of healthy volunteers. 相似文献18.
ERRATUM: Macho GA and Spears IR. 1999. Effects of Loading on the Biomechanical Behavior of Molars of Homo, Pan, and Pongo. Am J Phys Anthropol 109:211–227. The correct title of the article is given above. The word “biochemical” should be read as “biomechanical.” 相似文献
19.
Leaf-cutting ants have long been recognized to forage via complex trail systems but the nature and the ecological drivers of the different foraging strategies adopted remain a key topic. Here, we described the spatiotemporal use of belowground foraging galleries by Atta sexdens L. in the Brazilian Atlantic forest, and examined the adaptive advantages of this foraging strategy. Protium heptaphyllum adult trees (DBH?>?10?cm), seed/seedling clumps and ant gallery entrances were mapped across two 1-ha plots during two consecutive fruiting seasons (2002 and 2004). We recorded 75 ca. 40?cm deep gallery entrances beneath 26 P. heptaphyllum trees at nest distances ranging from 14 to 57?m. Furthermore, gallery abundance and galleries associated with seed/seedling clumps correlated positively with P. heptaphyllum density. Our results indicate that A. sexdens was able to set a permanent system of underground galleries targeting P. heptaphyllum trees and their seeds on the ground. Such network of galleries was spatially arranged according to both the spatial distribution and abundance of P. heptaphyllum trees in a way that most gallery entrances were disposed beneath or in close periphery of P. heptaphyllum crowns. Our findings suggest that underground trail systems shaped by fruit resources represent a foraging strategy clearly more common than existing literature on the subject would suggest. In addition, it reinforces the notion that the spatiotemporal availability of resources combined with predation risk largely influence trail configurations as well as overall foraging strategies adopted by leaf-cutting ants. 相似文献
20.
In acute experiments on nembutal-anesthetized (40 mg/kg, i.p.) albino rats, we recorded extracellularly and analyzed the background
impulse activity (BIA) of neurons of the fastigial nucleus of the cerebellum. Experiments were carried out on intact and labyrinthectomized
rats in the norm and after long-lasting (up to 15 days) influence of general vertical vibration (60 Hz, 0.4 mm, 2-h-long everyday
sessions). Distributions of the neurons according to the level of regularity of BIA, dynamics of spike trains, pattern of
histograms of interspike intervals (ISIs), and different frequency ranges of BIA were plotted; the mean frequency of this
activity and the coefficient of variation of ISIs were also calculated. Possible mechanisms of the effects of long-lasting
vibration of different durations on the BIA generated by neurons of the fastigial cerebellar nucleus in intact animals and
after switching off of labyrinth afferent inputs are discussed.
Neirofiziologiya/Neurophysiology, Vol. 38, No. 1, pp. 32–39, January–February, 2006. 相似文献