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At least 667 records · Page 37Linked to original sources
PubMed1996

The phosphorylation state of the 110 kDa component of the yeast spindle pole body shows cell cycle dependent regulation.

The 110 kDa component of the yeast spindle pole body (SPB) encoded by the SPC110/NUF1 gene is an essential protein which is important for the generation of a functional mitotic spindle in the yeast Saccharomyces cerevisiae. Spc110p exists in a number of forms which differ in mobility upon separation by SDS-polyacrylamide gel electrophoresis. We show that this heterogeneity is due to differential phosphorylation on serine or threonine residues and that Spc110p phosphorylation varies throughout the cell cycle. Specifically, the phosphorylated form Spc110p appears as cells progress from S-phase and is coincident with the presence of preanaphase mitotic spindles. Thus phosphorylation of Spc110p occurs at the stage in the cell cycle where SPBs acquire the competence to organize a mitotic spindle and could therefore represent an important regulatory event.

Blotting, Western↗
PubMed2000

Centrosome alterations induced by formamide cause abnormal spindle pole formations.

The formation of the bipolar mitotic apparatus depends on accurate centrosome organization which is crucial for the separation of the genome during cell division. While it has been shown that mutations and overexpression of centrosome proteins (Brinkley and Goepfert, 1998; Pihan et al., 1998) can cause abnormal spindle pole formation, here we report that damages to centrosome structure caused by the chaotropic agent formamide will cause multipolar mitoses upon recovery from the effect when applied at first cell division in sea urchin eggs. Formamide was used as a chemical tool to manipulate centrosome structure and to investigate the effects on microtubule organization. When 1-1.5 m formamide was administered for 30 min at prometaphase of first cell division, microtubules were disassembled and centrosomes compacted into dense spheres around highly condensed chromatin. Upon recovery from formamide, centrosomes decompacted and attempted to form various mitotic organizations. Normal recovery (and attempts of recovery) to bipolarity was possible in five percent of cells treated with 1-1.5 m formamide for 30 min, but abnormal patterns of spindle formation were observed in all other cells, which included mono- (20%), tri (45%), and multipolar (30%) formations organized by mono-, tri-, and multipolar centrosome clusters. When cells were treated with 1.5 m formamide for 90 min, centrosomes became pulverized and fragmented and only monopolar mitotic formations were observed upon recovery. These results are highly reproducible and reveal that abnormalities in centrosome structure can lead to abnormal mitosis which is not caused by mutation or overexpression of centrosome proteins.

Animals↗
PubMed2000

Premeiotic aster as a device to anchor the germinal vesicle to the cell surface of the presumptive animal pole in starfish oocytes.

The germinal vesicle (GV) of starfish oocytes stays just beneath the oocyte cortex at the presumptive animal pole during the long period of oogenesis. We subjected oocytes to a centrifugal force field to detach the GV from the cortex. The association between the cortex and the GV persisted and withstood a small amount of centrifugal acceleration at 200 g. The GV was eventually separated from the cortex at 700 g. The amount of acceleration sufficient for the GV separation was lowered when the oocytes were pretreated with Nocodazole and was increased by Taxol pretreatment. Observation of microtubular structures with an anti-alpha-tubulin antibody revealed the presence of a complex of spots and radiating arrays as was described by J. J. Otto and T. E. Schroeder (1984, Dev. Biol. 101, 274-281) and called the premeiotic aster. Nocodazole shortened the astral arrays, and Taxol enhanced them. These observations indicate that the premeiotic aster works as a device to hold the GV in an eccentric position just beneath the oocyte cortex.

Animals↗
PubMed2002

Identification of cis elements which direct the localization of maternal mRNAs to the posterior pole of ascidian embryos.

During ascidian embryogenesis, some mRNAs show clear localization at the posterior-most region. These postplasmic mRNAs are divided into two groups (type I and type II) according to their pattern of localization. To elucidate how these localization patterns are achieved, we attempted to identify the localization elements of these mRNAs. When in vitro synthesized postplasmic mRNAs were introduced into eggs, these mRNAs showed posterior localization similar to the endogenous mRNAs. The posterior localization of these mRNAs was mediated by their 3' untranslated regions (3' UTRs), as is the case for several localized Drosophila and Xenopus mRNAs. We identified smaller fragments of the 3' UTRs of HrWnt-5 and HrPOPK-1 mRNAs (type I) and HrPet-3 mRNA (type II) that were sufficient to direct green fluorescent protein mRNA to the posterior pole. For the localization of HrWnt-5 mRNA, two UG dinucleotide repetitive elements were essential. Motifs similar to these small elements also exist within the HrPOPK-1 mRNA localization element and 3' UTR of HrZF-1 mRNA, suggesting the conservation of localization elements among type I mRNAs. In contrast, the smallest sequence that suffices for the posterior localization of HrPet-3 (a type II mRNA) has different features from those of type I mRNAs; indeed, it does not have an identifiable critical element. This difference may distinguish type II mRNAs from type I mRNAs. These findings, especially the identification of the small localization element of HrWnt-5 mRNA, provide new insights into the localization of mRNAs during ascidian embryogenesis.

3' Untranslated Regions↗
PubMedDate not supplied

The budding yeast Cdc15 localizes to the spindle pole body in a cell-cycle-dependent manner.

Exit from mitosis in the budding yeast Saccharomyces cerevisiae cell cycle is regulated by a regulatory network that involves, among other proteins, the small GTPase Tem1, the protein phosphatase Cdc14, and the protein kinases Dbf2 and Cdc15. Using a fusion to jellyfish green fluorescent protein (GFP), here we report that Cdc15 costains with the microtubular-organizing apparatus and that this localization is precluded in a mutant lacking the outer plaque of the spindle pole body (SPB). The appearance of Cdc15 in the SPB is asymmetric and cell-cycle-regulated, preferentially marking the daughter cell SPB at anaphase and eventually disappearing at cytokinesis. Overproduction of GFP-tagged Cdc15 led to an accumulation of the fusion protein in both mother and daughter cells SPBs and, transiently, in small budded cells and shmoos. The Cdc15 localization pattern was maintained in dbf2, cdc14 and anaphase-promoting complex (cdc16) mutants, suggesting that the function of these proteins is not related to the localization of Cdc15 to the SPB but rather, at least in the case of Cdc14, to its timely removal from this structure. Tem1-depleted cells kept alive by Cdc15-GFP overexpression still display a proper localization of Cdc15. The results presented here suggest that the transient cell-cycle-dependent localization of Cdc15 to the SPB plays a role in the regulation of the latest stages of the cell cycle.

Anaphase↗
PubMedDate not supplied

Calcification at the posterior pole in scleritis. A case report.

We report a case with unilateral recurrent anterior scleritis which developed sclerochoroidal calcification at the posterior pole without any overt sign of posterior scleritis during the follow-up period of nine years. We believe that subtle posterior scleral inflammation might lead to sclerochoroidal calcification which might be dystrophic in nature.

Adult↗
PubMed1981

Aminopeptidase N is a marker for the apical pole of porcine thyroid epithelial cells in vivo and in culture.

An aminopeptidase N has been detected by immunofluorescence in the apical plasma membrane of porcine thyroid cells, facing the follicular lumen. Freshly isolated cells obtained by tissue trypsinization, lose their polarity and exhibit a homogeneous enzyme distribution over the whole plasma membrane. In thyrotropin-stimulated cultured cells organized into follicles, the enzyme is localized the apical cell pole. In monolayer cells, on the other hand, the enzyme is distributed over the whole surface facing the medium. In both types of cultures fluorescence is also observed in intracytoplasmic organelles. In vivo, aminopeptidase ia a marker of the apical part of the thyroid plasma membrane, but its in vitro localization depends upon cell differentiation related to the culture conditions.

Aminopeptidases↗
PubMed1989

Higher order structure is present in the yeast nucleus: autoantibody probes demonstrate that the nucleolus lies opposite the spindle pole body.

A panel of sera from 892 autoimmune patients was screened by indirect immunofluorescence on mammalian cells. Seventy-three sera were identified that recognize the nucleolus. Three of these sera appear to stain the nucleolus in yeast, suggesting that they recognize highly conserved antigens. These three sera also immunoprecipitate mammalian U3 snRNA-containing particles, which reside in the nucleolus and have been implicated in rRNA processing. Double immunofluorescence experiments with anti-nucleolus and anti-tubulin antibodies revealed a novel form of non-random nuclear organization in yeast. The spindle pole body and the nucleolus-both of which are associated with the nuclear envelope-preferentially localize at opposite ends of the nucleus. Organization of these and other components into specific regions of the nucleus may be important for optimizing their proper function.

Autoantibodies↗
PubMed1994

The spindle pole body of yeast.

Microtubule organizing centers play an essential cellular role in nucleating microtubule assembly and establishing the microtubule array. The microtubule organizing center of yeast, the spindle pole body (SPB), shares many functions and properties with those other organisms. In recent years considerable new information has been generated concerning components associated with the SPB, and the mechanism by which it duplicates. This article reviews our current view of the cytology and molecular composition of the SPB of the budding yeast, Saccharomyces cerevisiae, and the fission yeast, Schizosaccharomyces pombe. Genetic studies in these organisms has revealed information about how the SPB duplicates and separates, and its roles during vegetative growth, mating and meiosis.

Centrosome↗
PubMed1989

Thermal changes observed before and after J.-L. Etienne's journey to the North Pole. Is central nervous system temperature preserved in hypothermia?

The thermoregulatory responses of a French doctor, Jean-Louis Etienne, were examined in a standard cold test before and after his journey to the North Pole, to investigate whether general and/or local cold adaptation had occurred. The two tests were carried out in a climatic chamber for 2 h at rest (dry bulb temperature, 1 degree C; relative humidity, 40%; wind speed, 0.8 m.s-1). After his journey, Etienne showed a general hypothermic-hypometabolic adaptation, i.e. a decrease in rectal temperature (Tre) and metabolic heat production (M), and an increased local skin temperature of the extremities. Between the two tests, a change occurred in the relationship between tympanic temperature (Tty) and M. During the post-journey cold test, Tty [as representative of the central nervous system (CNS) temperature] increased while the decrease in Tre was accelerated, probably due to a redistribution of blood volume towards the CNS. Such a mechanism would protect the central core with special reference to the CNS.

Acclimatization↗
PubMed1982

Expanding gas bubbles for the repair of tears in the posterior pole.

Expanding, long-lived intraocular perfluorocarbon gas bubbles can make possible the repair of retinal detachments with holes or tears in the posterior pole. Vitrectomy is not necessary for injecting the gas. The patient should be prone in order to bring the gas bubble to the top of the visual axis. Four perfluorocarbon gases have the appropriate coefficient of expansion to provide adequate intraocular gas volumes by displacing the fluid vitreous. Volumes of 1 to 2 cc are sufficient. Intraocular space for these amounts can be obtained either by draining subretinal fluid or by injecting 0.6 cc of C2F6 (which expands 3.3x) without draining. If the patient cannot tolerate being prone, most of the fluid vitreous can be displaced with an intraocular injection of 0.9 cc of C4F10 (which expands 5x).

Fluorocarbons↗
PubMed2003

[An avulsion (sleeve) fracture of the proximal patella pole in a child. Diagnosis, treatment and results in a patient after a fall onto the knee].

We report a case of an avulsion fracture (sleeve fracture) of the proximal pole of the patella in an 8 year old boy who fell onto his left knee. After the fracture was diagnosed, the patient under went surgery on the day of the accident. The articular cartilage and the upper fragment were reconstituted and fixed with transosseous sutures. A cast immobilisation in extension was used for 6 weeks and the patient regained full active mobility of the left knee joint after cast removal. A radiograph showed that the fracture had completely united. Diagnosis, pathomechanism and treatment strategies are discussed with reference to this rare case, and the literature is reviewed.

Accidental Falls↗
PubMed2000

Stimulation in the rostral pole of monkey superior colliculus: effects on vergence eye movements.

Recent studies have indicated that the superior colliculus (SC), traditionally considered to be saccade-related, may play a role in the coding of eye movements in both direction and depth. Similarly, it has been suggested that omnidirectional pause neurons are not only involved in the initiation of saccades, but can also modulate vergence eye movements. These new developments provide a challenge for current oculomotor models that attempt to describe saccade-vergence coordination and the neural mechanisms that may be involved. In this paper, we have attempted to study these aspects further by investigating the role of the rostral pole of the SC in the control of vergence eye movements. It is well-known that, by applying long-duration electrical stimulation to rostral sites in the monkey SC, saccadic responses can be prevented and interrupted. We have made use of these properties to extend this paradigm to eye movements that contain a substantial depth component. We found that electrical intervention in the rostral region also has a clear effect on vergence. For an eye movement to a near target, stimulation leads to a significant suppression and change in dynamics of the pure vergence response during the period of stimulation, but the depth component cannot be prevented entirely. When these paradigms are implemented for 3D refixations, the saccade is inactivated, as expected, while the vergence component is often suppressed more than in the case of the pure vergence. The data lead us to conclude that the rostral SC, presumably indirectly via connections with the pause neurons, can affect vergence control for both pure vergence and combined 3D responses. Suppression of the depth component is incomplete, in contrast to the directional movement, and is often different in magnitude for 3D refixations and pure vergence responses. The results are discussed in connection with current models for saccade-vergence interaction.

Animals↗
PubMed2005

Counterclockwise barber-pole sign on CT: SMA/SMV variance without midgut malrotation.

We report on a 10-year-old girl who presented with worsening pain and anorexia after blunt trauma to the abdomen. Contrast-enhanced CT of the abdomen was performed, and a counterclockwise rotation of the superior mesenteric vein around the superior mesenteric artery was seen. An upper gastrointestinal (UGI) series with small-bowel follow-through demonstrated a normally located duodenal-jejunal junction. This is the first case report of a counterclockwise barber-pole sign seen by CT with UGI that was negative for malrotation or volvulus.

Abdominal Pain↗
PubMed2006

Osteogenic protein-1 (BMP-7) accelerates healing of scaphoid non-union with proximal pole sclerosis.

We randomly assigned 17 patients with scaphoid non-union at the proximal pole to three treatment groups: (1) autologous iliac graft (n=6), (2) autologous iliac graft + osteogenic protein-1 (OP-1; n=6), and (3) allogenic iliac graft + OP-1 (n=5). Radiographic, scintigraphic, and clinical assessments were performed throughout the follow-up period of 24 months. OP-1 improved the performance of both autologous and allogenic bone implants and reduced radiographic healing time to 4 weeks compared with 9 weeks in group 1. Helical CT scans and scintigraphy showed that in OP-1-treated patients sclerotic bone was replaced by well-vascularised bone. The addition of OP-1 to allogenic bone implant equalised the clinical outcome with the autologous graft procedure. Consequently the harvesting of autologous graft can be avoided.

Adolescent↗
PubMedDate not supplied

Breast shape: a technique for better upper pole fullness.

The authors offer a new technique that provides a better long-term upper pole fullness to the shape of the breasts following reduction mammoplasty, thus creating an overall more satisfactory aesthetic appearance for both breasts.

Breast↗
PubMed2006

Deletion of RNQ1 gene reveals novel functional relationship between divergently transcribed Bik1p/CLIP-170 and Sfi1p in spindle pole body separation.

Spindle pole body (SPB; the microtubule organizing center in yeast) duplication is essential to form a bipolar spindle. The duplicated SPBs must then separate and migrate to opposite sides of the nucleus. We identified a novel functional relationship in SPB separation between the microtubule stabilizing protein Bik1p/CLIP-170 and the SPB half-bridge protein Sfi1p. A genetic interaction between BIK1 and SFI1 was discovered in a synthetic lethal screen using a strain deficient in the prion protein gene RNQ1. RNQ1 deletion reduced expression from the divergently transcribed BIK1, allowing us to identify genetic interactors with bik1. The sfi1-1 bik1 synthetic lethality was suppressed by over-expression of CIK1, KAR1, and PPH21. Genetic analysis indicated that the sfi1-1 bik1 synthetic lethality was unlikely related to the function of Bik1p in the dynein pathway or to defects in spindle position. Furthermore, a sfi1-1 Deltakip2 mutant was viable, suggesting that the Bik1p pool at the cytoplasmic microtubule plus-ends may not be required in sfi1-1. Microscopic examination indicated the sfi1-1 mutant was delayed in SPB duplication, SPB separation, or spindle elongation and the sfi-1 Deltabik1 double mutant arrested with duplicated but unseparated SPBs. These results suggest that Bik1p has a previously uncharacterized function in the separation of duplicated SPBs.

Alleles↗
PubMed2001

Mid-infrared trace gas detection using continuous-wave difference frequency generation in periodically poled RbTiOAsO4.

A tunable mid-infrared continuous-wave (cw) spectroscopic source in the 3.4-4.5 micrometers region is reported, based on difference frequency generation (DFG) in a quasi-phase-matched periodically poled RbTiOAsO4 (PPRTA) crystal. DFG power levels of 10 microW were generated at approximately 4 micrometers in a 20-mm long PPRTA crystal by mixing two cw single-frequency Ti:Al2O3 lasers operating near 713 nm and 871 nm, respectively, using a laser pump power of 300 mW. A quasi-phase-matched infrared wavelength-tuning bandwidth (FWHM) of ~ 12 cm-1 and a temperature tuning rate of 1.02 cm-1/degree C were achieved. Experimental details regarding the feasibility of trace gas detection based on absorption spectroscopy of CO2 in ambient air using this DFG radiation source are also described.

Aluminum Oxide↗