The DNA damage effector Chk1 kinase regulates Cdc14B nucleolar shuttling during cell cycle progression

Chk1 is a critical effector of DNA damage checkpoints necessary for the maintenance of chromosome integrity during cell cycle progression. Here we report, that Chk1 co-localized with the nucleolar marker, fibrillarin in response to radiation-induced DNA damage in human cells. Interestingly, in vitro studies using GST pull down assays identified the dual-specificity serine/threonine nucleolar phosphatase Cdc14B as a Chk1 substrate. Furthermore, Chk1, but not a kinase-dead Chk1 control, was shown to phosphorylate Cdc14B using an in vitro kinase assay. Co-immunoprecipitation experiments using exogenous Cdc14B transfected into human cells confirmed the interaction of Cdc14B and Chk1 during cell cycle. In addition, reduction of Chk1 levels via siRNA or UCN-01 treatment demonstrated that Chk1 activation following DNA damage was required for Cdc14B export from the nucleolus. These studies have revealed a novel interplay between Chk1 kinase and Cdc14B phosphatase involving radiation-induced nucleolar shuttling to facilitate error-free cell cycle progression and prevent genomic instability.

Genetic diversity of the major histocompatibility complex class II in Alaskan caribou herds

We have sampled five different herds of caribou in Alaska to ascertain their major histocompatibility complex (MHC) class II diversity, and to assess whether the herds were significantly different in their MHC class II allele profiles. We complemented the MHC results with data from nine neutral microsatellite markers. The results indicate that while the microsatellites are diverse, there are no significant differences between the herds. However, for the MHC, we have shown that there is diversity at three of the four loci studied, the different herds have significantly different MHC class II allele profiles. It is also clear that although some of the herds have overlapping ranges, they are still different for their MHC class II alleles.

Increased 18F-FDG uptake and expression of Glut1 in the EMT transformed breast cancer cells induced by TGF-beta

As carcinomas progress, the tumors may lose epithelial morphology and acquire mesenchymal characteristics typically called epithelial-mesenchymal transition (EMT), which is commonly associated with increased cell migration, enables cells to dissociate from their original tissue and form metastasis in distant organs. In addition to molecular and morphologic changes, the EMT transformed cells also showed the change of sensitivity to chemotherapeutics. In order to detect the EMT transition in vivo clinically, we detected the change of metabolism of MCF-7 cells after being induced by TGF-beta to form EMT condition by MTT and 18F-FDG uptake.

Effects of specific expression of iaaL gene in tobacco tapetum on pollen embryogenesis

The indoleacetic-acid-lysine synthetase (iaaL) gene from Pseudomonas syringae subsp. savastanoi was fused to tobacco tapetum-specific expression promoter TA29, and introduced into tobacco. The expression pattern of this chimeric gene was studied, and the endogenous indoleacetic acid (IAA) levels in different organs were assayed. The results demonstrated that TA29 promoter was only able to direct the specific expression of iaaL gene in transgenic tobacco anther, and resulted in the decrease of endogenous IAA levels in transgenic tobacco anther. No significant phenotype variation was observed among the transgenic plants at the whole plant level. However, the percentage of pollen embryogenesis was reduced to 11% when anthers of the transgenic plants were cultured on the modified hormone-free Nistch H (NH) medium, while those of both CK1 and CK2 (see sec. 1.2.2) were more than 50%; when the anthers were cultured on NH medium supplemented with 0. 2 mg/L IAA, the percentage of pollen embryogenesis restored to the same level of that of the wild type (up to 55.7%). This study demonstrates that the IAA metabolism in anther tapetum cells is of significant importance to the androgenic development in anther culture.

Study and Application of Gelled Foam for In-Depth Water Shutoff in a Fractured Oil Reservoir

Abstract

A gelled foam is comprised of water, a foaming agent (surfactant), a foaming stabilizer (polymer) and a cross-linking agent. This system with gel as the outer phase is more stable than conventional foam that uses water as the outer phase. Therefore, the gelled foam system prolongs the effective period of water shutoff. By using the Ross Foamer Device to determine its foaming and stability characters, we verify that the best foaming agent is 0.3% YG240; the stable foam agent is 0.2- 0.4% HPAM; the cross-linking agent is 0.09% sodium dichromate and 0.16% sodium sulphite and nitrogen. On the basis of bench-scale evaluations of characters on gelation time and water shutoff efficiency, the pilot test is performed on Well H1340 in the Huoshaoshan fractured reservoir. The workover program includes washing the larger fissures using a highly efficient oil displacement agent, injecting gelled foaming agent, over-displacing fluids, nitrogen and water, then shutting in the well for hardening. Field tests show that good blocking efficiency is gained in the well with a water cut decrease of 20 - 50% and oil production increase of 3.7 - 11.0 m3/day.

Introduction

At present, most oil fields in china are in a high water cut period; injection water and edge water usually breakthrough into oil wells along high permeability zones, causing oil well productivity to decline and development results of waterflooding to get worse. As conventional water shutoff techniques such as mechanical shutoff and chemical shutoff in high permeability zones associating with limited shutoff diameters and depth, the plugging effects decreased rapidly and oil recovery from waterflooding has been greatly affected. In recent years, field tests of profile control with foam have been developed, yet high permeability zones can not be plugged effectively because of a short half life and the limited blocking radius of foam agents. Thus, it is necessary to study the techniques of gelled foam for in-depth water shutoff.

Polyglycolic Acid-islet grafts improve blood glucose and insulin concentrations in rats with induced diabetes

Pancreatic islet transplantation is a promising therapeutic treatment for type 1 diabetes mellitus. In the present study, we cocultured islets with or without a polyglycolic acid (PGA) fibrous scaffold for 5 days and transplanted the PGA-islet grafts into the leg muscles of Wistar rats with streptozotocin-induced diabetes; controls were injected with saline. The results showed that the blood glucose concentrations of the group given islets embedded with the PGA scaffold were lower than those without the scaffold or controls. On the other hand, the insulin content of the PGA-islet group was higher at all 5 time points compared with the insulin contents of the other 2 groups. After transplantation, many islets in the PGA-islet grafts showed normal morphology (as seen under the scanning electron microscope) and were surrounded by red blood cells. A fibrous extracellular matrix was visible around the PGA-islet grafts. These results demonstrated that PGA-islet grafts improved blood glucose and insulin concentrations in rats with induced diabetes.

Loss of spindle assembly checkpoint-mediated inhibition of Cdc20 promotes tumorigenesis in mice

Genomic instability is a hallmark of human cancers. Spindle assembly checkpoint (SAC) is a critical cellular mechanism that prevents chromosome missegregation and therefore aneuploidy by blocking premature separation of sister chromatids. Thus, SAC, much like the DNA damage checkpoint, is essential for genome stability. In this study, we report the generation and analysis of mice carrying a Cdc20 allele in which three residues critical for the interaction with Mad2 were mutated to alanine. The mutant Cdc20 protein (AAA-Cdc20) is no longer inhibited by Mad2 in response to SAC activation, leading to the dysfunction of SAC and aneuploidy. The dysfunction could not be rescued by the additional expression of another Cdc20 inhibitor, BubR1. Furthermore, we found that Cdc20^AAA/AAA mice died at late gestation, but Cdc20^+/AAA mice were viable. Importantly, Cdc20^+/AAA mice developed spontaneous tumors at highly accelerated rates, indicating that the SAC-mediated inhibition of Cdc20 is an important tumor-suppressing mechanism.

The Relationship between Intra-Operative Ultrasonography and Pathological Grade in Cerebral Glioma

The value of intra-operative ultrasound as a tool in guiding resection of cerebral gliomas and the relationship between the appearance of brain tissue on intra-operative ultrasonography and pathological grade of cerebral glioma were investigated in 98 patients who underwent neurosurgical tumour removal. Lesions were classified according to pathological grade. Intra-operative ultrasonography orientated all the cerebral gliomas accurately and helped the neurosurgeon in assessing the tumour prior to removal. All lesions were hyperechoic compared with normal brain tissue, and the majority of lesions displayed irregular shapes and indistinct margins. Different pathological grades of glioma presented different ultrasonographic appearances. The majority of low-grade (I and II) cerebral gliomas were homogeneous, with distinct margins and clear surrounding oedema compared with adjacent brain tissue. High-grade (III and IV) cerebral gliomas mostly exhibited poorly defined borders and central necrosis, and the surrounding oedema was difficult to distinguish from the lesions. Residual tumour or haematoma were identified. In conclusion, intra-operative ultrasonography is of great value in locating and assessing the grade of cerebral glioma, and is conducive to enabling early evaluation and total removal of the lesion.

Different biological properties of circulating and bone marrow endothelial progenitor cells in acute myocardial infarction rats

BACKGROUND

Many studies have shown that endothelial progenitor cell (EPC) can enhance the neovascularization of the ischemic myocardium. Peripheral blood and bone marrow are the most convenient resources for EPC.

OBJECTIVE

The aim of the study was to investigate, in vitro and in vivo, the different biological properties between circulating EPC (CEPC) and bone marrow EPC (BM-EPC) of AMI rats.

METHODS

The proliferative, migrative, adherent and angiogenic properties were investigated in vitro. 1 x 10 (6) CEPCs, 1 x 10 (6) BM-EPCs and medium (EBM-2) were injected in the myocardium of AMI rats. Echocardiography, regional myocardial blood flow (RMBF), capillary density and Y chromosome fluorescence in situ hybridization (FISH) were performed at 4 weeks after transplantation.

RESULTS

The CEPCs had higher proliferative, migrative, adherent capabilities and lower senescent ratio, could adhere more quickly to fibronectin than BM-EPCs. CEPCs could form capillary-like structures whereas BM-EPCs did not show similar structures on Matrigel. in vivo, transplanted CEPCs and BM-EPCs were found in cardiac tissue by FISH. CEPCs treatment led to a better cardiac function, RMBF and capillary density than BM-EPCs.

CONCLUSION

Different biological properties were observed between CEPCs and BM-EPCs. Autologous CEPCs are more suitable for the AMI rat.

Thin-trimming of the scrotal reconstruction flap: long-term follow-up shows reversal of spermatogenesis arrest

OBJECTIVE

To explore a method to decrease the arrest of spermatogenesis in patients undergoing scrotum reconstruction with a flap.

METHODS

A follow-up study on a patient whose scrotum had been reconstructed with a flap revealed the arrest of spermatogenesis. The flap was trimmed thin on two occasions, and the composition of the seminal fluid was followed up.

RESULTS

The follow-up showed a decrease in the arrest of spermatogenesis after the flap was thin-trimmed.

CONCLUSIONS

Thin-trimming the reconstruction flap can decrease the degree of spermatogenesis arrest in patients who have received scrotum reconstruction by thick flap.