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571.
The neurofibromatosis type 2 (NF2) tumor suppressor, Merlin, is a FERM (Four point one, Ezrin, Radixin, Moesin) domain-containing protein whose loss results in defective morphogenesis and tumorigenesis in multiple tissues. Like the closely related ERM proteins (Ezrin, Radixin, and Moesin), Merlin may organize the plasma membrane by assembling membrane protein complexes and linking them to the cortical actin cytoskeleton. We previously found that Merlin is a critical mediator of contact-dependent inhibition of proliferation and is required for the establishment of stable adherens junctions (AJs) in cultured cells. Here, we delineate the molecular function of Merlin in AJ establishment in epidermal keratinocytes in?vitro and confirm that a role in AJ establishment is an essential function of Merlin in?vivo. Our studies reveal that Merlin can associate directly with α-catenin and link it to Par3, thereby providing an essential link between the AJ and the Par3 polarity complex during junctional maturation. 相似文献
572.
Debra L Fulton Yvonne Y Li Matthew R Laird Benjamin GS Horsman Fiona M Roche Fiona SL Brinkman 《BMC bioinformatics》2006,7(1):270-16
Background
Orthologs (genes that have diverged after a speciation event) tend to have similar function, and so their prediction has become an important component of comparative genomics and genome annotation. The gold standard phylogenetic analysis approach of comparing available organismal phylogeny to gene phylogeny is not easily automated for genome-wide analysis; therefore, ortholog prediction for large genome-scale datasets is typically performed using a reciprocal-best-BLAST-hits (RBH) approach. One problem with RBH is that it will incorrectly predict a paralog as an ortholog when incomplete genome sequences or gene loss is involved. In addition, there is an increasing interest in identifying orthologs most likely to have retained similar function. 相似文献573.
Consuelo Plata Patricia Meade Norma Vazquez Steven C Hebert Gerardo Gamba 《The Journal of biological chemistry》2002,277(13):11004-11012
The bumetanide-sensitive Na(+):K(+):2Cl(-) cotransporter (BSC1) is the major pathway for salt reabsorption in the apical membrane of the mammalian thick ascending limb of Henle. Three isoforms of the cotransporter, known as A, B, and F, exhibit axial expression along the thick ascending limb. We report here a functional comparison of the three isoforms from mouse kidney. When expressed in Xenopus oocytes the mBSC1-A isoform showed higher capacity of transport, with no difference in the amount of surface expression. Kinetic characterization revealed divergent affinities for the three cotransported ions. The observed EC(50) values for Na(+), K(+), and Cl(-) were 5.0 +/- 3.9, 0.96 +/- 0.16, and 22.2 +/- 4.8 mm for mBSC1-A; 3.0 +/- 0.6, 0.76 +/- 0.07, and 11.6 +/- 0.7 mm for mBSC1-B; and 20.6 +/- 7.2, 1.54 +/- 0.16, and 29.2 +/- 2.1 mm for mBSC1-F, respectively. Bumetanide sensitivity was higher in mBSC1-B compared with the mBSC1-A and mBSC1-F isoforms. All three transporters were partially inhibited by hypotonicity but to different extents. The cell swelling-induced inhibition profile was mBSC1-F > mBSC1-B > mBSC1-A. The function of the Na(+):K(+):2Cl(-) cotransporter was not affected by extracellular pH or by the addition of metolazone, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), or R(+)-[(2-n-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1-H-indenyl-5-yl)-oxy]acetic acid (DIOA) to the extracellular medium. In contrast, exposure of oocytes to HgCl(2) before the uptake period reduced the activity of the cotransporter. The effect of HgCl(2) was dose-dependent, and mBSC1-A and mBSC1-B exhibited higher affinity than mBSC1-F. Overall, the functional comparison of the murine apical renal-specific Na(+):K(+):2Cl(-) cotransporter isoforms A, B, and F reveals important functional, pharmacological, and kinetic differences, with both physiological and structural implications. 相似文献
574.
Abnormal acidification of melanoma cells induces tyrosinase retention in the early secretory pathway. 总被引:5,自引:0,他引:5
Ruth Halaban Robin S Patton Elaine Cheng Sherri Svedine E Sergio Trombetta Miriam L Wahl Stephen Ariyan Daniel N Hebert 《The Journal of biological chemistry》2002,277(17):14821-14828
In tyrosinase-positive amelanotic melanoma cells, inactive tyrosinase accumulates in the endoplasmic reticulum. Based on studies described here, we propose that aberrant vacuolar proton ATPase (V-ATPase)-mediated proton transport in melanoma cells disrupts tyrosinase trafficking through the secretory pathway. Amelanotic but not melanotic melanoma cells or normal melanocytes display elevated proton export as observed by the acidification of the extracellular medium and their ability to maintain neutral intracellular pH. Tyrosinase activity and transit through the Golgi were restored by either maintaining the melanoma cells in alkaline medium (pH 7.4-7.7) or by restricting glucose uptake. The translocation of tyrosinase out of the endoplasmic reticulum and the induction of cell pigmentation in the presence of the ionophore monensin or the specific V-ATPase inhibitors concanamycin A and bafilomycin A1 supported a role for V-ATPases in this process. Because it was previously shown that V-ATPase activity is increased in solid tumors in response to an acidified environment, the appearance of hypopigmented cells in tyrosinase-positive melanoma tumors may indicate the onset of enhanced glycolysis and extracellular acidification, conditions known to favor metastatic spread and resistance to weak base chemotherapeutic drugs. 相似文献
575.
576.
Hylton E. Molzof Michael D. Wirth James B. Burch Nitin Shivappa James R. Hebert Russell L. Johnson 《Chronobiology international》2017,34(3):337-348
The aims of this study were to 1) compare the inflammatory potential of night- and day-shift nurses’ diets with regard to time of day and work status and 2) explore how the timing of food intake during work and off-work is associated with cardiometabolic syndrome (CMS) risk factors between these two groups. Female nurses (N = 17; 8 day-shift and 9 night-shift) reported food intake over 9 days. On a middle day off of work, metabolic parameters were measured after an overnight fast. Energy/macronutrient intake and inflammatory potential of dietary intake (as assessed via the Dietary Inflammatory IndexTM) were calculated for nurses’ workdays, work nights, off-work days, and off-work nights. Work-night total food intake (grams) accounted for a significant amount of variance in CMS risk factors for night-shift nurses only. Increased total gram consumption during night-shift nurses’ work nights was associated with increased lipid levels – independent of the macronutrient composition of the food consumed. Alternatively, for night-shift nurses, work-day intake of several food parameters accounted for a significant proportion of variance in HDL cholesterol levels, with higher intake associated with higher HDL levels. For both day- and night-shift nurses, food intake during the day was more pro-inflammatory regardless of shift type or work status. Our novel approach of combining time-of-day-specific and work-day-specific analyses of dietary inflammatory factors and macronutrient composition with measurement of CMS risk factors suggests a link between meal timing and cardiometabolic health for shift-working nurses. 相似文献
577.
Among the Kerguelen Islands' demersal fish, larvae of Lepidonotothen squamifrons are dominant during the summer over the island shelf and surrounding seamounts. Distribution of larval stages from different
scientific surveys confirmed the position of the two known spawning grounds (south of the Kerguelen shelf and at the Kerguelen-Heard
bank) and may indicate other spawnings on the Skiff bank and in bays and fjords. Different larval cohorts were observed for
the shelf and the coastal zone whereas a unique one was observed for Skiff and Kerguelen-Heard seamounts. Larvae from the
spawning ground south of the Kerguelen shelf appear in early summer and show a northwards dispersal to the northeastern nearshore
zone, the Baleiniers Gulf, following the scheme of fish migration shown by Harden-Jones. Later on, larvae from the northern
inshore spawning zone occur in the same area, which presumably then avoid intraspecific competition with the previous larvae.
Larval distribution and migration strategy seemed to be in accordance with the island mass or seamount effect under a regular
current.
Accepted: 2 December 1999 相似文献
578.
Biological identifications through DNA barcodes 总被引:82,自引:0,他引:82
Hebert PD Cywinska A Ball SL deWaard JR 《Proceedings. Biological sciences / The Royal Society》2003,270(1512):313-321
Although much biological research depends upon species diagnoses, taxonomic expertise is collapsing. We are convinced that the sole prospect for a sustainable identification capability lies in the construction of systems that employ DNA sequences as taxon 'barcodes'. We establish that the mitochondrial gene cytochrome c oxidase I (COI) can serve as the core of a global bioidentification system for animals. First, we demonstrate that COI profiles, derived from the low-density sampling of higher taxonomic categories, ordinarily assign newly analysed taxa to the appropriate phylum or order. Second, we demonstrate that species-level assignments can be obtained by creating comprehensive COI profiles. A model COI profile, based upon the analysis of a single individual from each of 200 closely allied species of lepidopterans, was 100% successful in correctly identifying subsequent specimens. When fully developed, a COI identification system will provide a reliable, cost-effective and accessible solution to the current problem of species identification. Its assembly will also generate important new insights into the diversification of life and the rules of molecular evolution. 相似文献
579.
Hans Hebert ers Olofsson Monica Thelestam Elisabeth Skriver 《FEMS microbiology letters》1992,105(1-3):5-12
Abstract The 12S oligomeric form of Staphylococcus aureus α-toxin has been studied with electron microscopy after incubation of the toxin with membrane preparations or liposomes. The target material originated from human platelet. Different electron microscopic preparation techniques were used including negative staining, freeze-fracture and vitrification in liquid ethane. Analysis of micrographs with image processing methods revealed two groups of ring-like structures corresponding to α-toxin oligomers. One form measured 75 Å in diameter and had a high stain density in the central protein deficient part while the other was larger with a diameter of 100 Å and less stain accumulation in the center. The conditions under which the latter were formed suggest that this corresponds to an inactive loosely-bound form of the toxin. The high stain density in the smaller particle is consistent with the presence of a penetrating pore in this structure. 相似文献
580.
Teresa L. Dzieweczynski Kalyn R. Sullivan Lindsay M. Forrette Olivia L. Hebert 《Ethology : formerly Zeitschrift fur Tierpsychologie》2012,118(4):351-359
Consistent individual differences in behavior suggest that individuals respond in a predictable and repeatable manner in a specific situation while differing from other individuals. Male Siamese fighting fish exhibit consistent individual differences in decision‐making strategies when they encounter a receptive female and a rival male simultaneously. However, whether these differences are altered by recent experience is unknown. We examined the influence of repeated aggressive encounters on behavioral consistency and decision‐making. Males were presented with paired female–male dummies prior to any aggressive experiences to obtain a baseline measure. Next, males either won or lost three consecutive contests against rivals and then received the paired female–male dummies after each of these encounters. Overall levels of highly aggressive behaviors were affected by contest outcome, while levels of female‐directed were not. Not surprisingly, winning a fight led to an increase in male‐directed bites, an overtly aggressive behavior that only occurs after fights have escalated. Fighting a male before encountering the dummies caused males to perform more tail beats to the dummy male, perhaps as a result of increased motivation. Males exhibited similar levels of repeatability and used the same strategies when faced with conflicting stimuli regardless of fighting experience. Thus, while winning or losing a fight impacts overall aggression, it does not influence behavioral consistency. This study demonstrates that consistent individual differences and decision‐making strategies may be resistant to recent aggressive experiences, even over a period of days. 相似文献