Development of a new sensitive immunostrip assay based on mesoporous silica and colloidal Au nanoparticles

A new competitive immunostrip assay was developed to detect human serum albumin (HSA) in urine sample with use of conjugated monoclonal antibody gold nanoparticles (mAb–AuNPs) and mobile crystalline material (MCM)-41–HSA bioconjugate. To prepare the immunostrip, the colloidal AuNPs with an average particle diameter of 20 nm, was synthesized, labeled with antibody and applied on the conjugate pad as the detection reagent. Then, HSA was attached to the MCM-41 mesoporous nanoparticles and immobilized to a nitrocellulose membrane as the test line. In the optimized investigational conditions, the immunostrip could detect HSA in a high linear range (from 1 to 200 μg/ml) and low detection limit (ng/ml). The reliability of the testing procedure was examined by performing the immunostrip test with 30 urine samples and comparing the results with those obtained via immunoturbidimetry. The immunostrip was adequately sensitive and accurate for a rapid screening of HSA in the urine. This new strategy for competitive immunostrip design can be used and developed for other antigen based immunostrip assay.     

The effect of progesterone and exogenous gonadotropin on preimplantation mouse embryo development and implantation

The aim of this study was to evaluate the effects of progesterone and ovarian stimulation on the development and implantation rate of mouse embryos. Two-cell embryos were collected from superovulated mice and cultured in the presence of different concentrations of progesterone (0, 5, 10 and 20 ng/ml). Also other mice were rendered pregnant in unstimulated, unstimulated progesterone-injected, superovulated and superovulated progesterone-injected groups to collect the blastocysts. The number of blastocysts and implantation sites were recorded on the 4th and 7th day of pregnancy, respectively. The diameter and cell number of blastocysts were analyzed in the in vitro and in vivo groups. After 120 h culture, the percentage of hatched blastocyst embryos in control and 5, 10 and 20 ng/ml progesterone-injected groups were 63.9%, 64.2%, 64.2% and 75.6% respectively. There were significant differences between the developmental rates of embryos in the presence of 20 ng/ml progesterone and the control and other concentrations of progesterone-injected groups (P< or =0.001). The in vivo blastocyst survival rate (97.68%) and implantation rate (92.06%) in the unstimulated and progesterone-injected groups were higher than in the other groups. Blastocyst cell numbers in the superovulated (128.62 +/- 1.30) and superovulated progesterone-injected groups (126.88 +/- 1.60) were significantly different from the control (P<0.001). The progesterone injection without ovarian induction improved the embryo survival and implantation rates, but after superovulation it did not ameliorate the negative effects of superovulation on the implantation rate.     

On BLM helicase in recombination-mediated telomere maintenance

Bloom syndrome (BS) is an extremely rare, autosomal recessive genetic syndrome of humans. Patients with BS are predisposed to almost all forms of cancer and also display premature aging phenotypes. These patients are diagnosed in the clinics by hyper-recombination phenotype that is manifested by high rates of sister chromatid exchange. The gene mutated in BS, designated BLM, lies on chromosome 15q26.1 and encodes a RecQ-like ATP-dependent 3′–5′ helicase, which functions in DNA double-strand break repair processes such as non-homologous end joining, homologous recombination-mediated repair, resolution of stalled replication forks and synthesis-dependent strand annealing, although its precise functions at the telomeres are speculative. Recently it has been suggested that the BLM helicase may play important roles in Telomerase-independent forms of telomere elongation or alternative lengthening of telomeres (ALT). A mechanism that although provides cells with a window of opportunity to save ends of their chromosomes, puts these Telomerase ^?/? cells under continuous stress. BLM localization within ALT-associated PML nuclear bodies in telomerase-negative immortalized cell lines and its interaction with the telomere-specific proteins strengthens that suggestion. Here, I begin by outlining features common to all RecQ helicases. I, then, survey evidences that implicate possible roles of BLM helicase in this recombination-mediated mechanism of telomere elongation.     

Arbuscular mycorrhizal fungi and biological control of Verticillium-wilted cotton plants

The interaction of arbuscular mycorrhizal fungi (Glomus etunicatum, Glomus intraradices, and Glomus versiforme) with a wilt-causing soil-borne pathogen, Verticillium dahliae, was studied in cotton. It was found that establishment by arbuscular mycorrhizal fungi reduced disease index. In diseased cotton plants colonised by G. etunicatum, the disease index was less than other diseased mycorrhizal and non-mycorrhizal ones. In diseased cotton plants, chlorophyll content was lower than others. Three Glomus species significantly increased content of sugar and protein in shoot and root. Pathogen-infected plants had higher proline concentration in shoot and root than healthy plants. On the other hand, the increased content of proline as stress sensor showed that Verticillium accelerates senescence and reduces yield. These results suggest that the beneficial effects of mycorrhiza can alleviate the pathogenesis effects of V. dahliae partly, and also there is a competitive interaction between the pathogenic and symbiotic fungi.     

Evidence that iron-overload promotes 7, 12-dimethylbenz(a)anthracene-induced skin tumorigenesis in mice

Summary

Iron overload is known to occur in West European and American populations due to the consumption of an iron-rich diet. There are also genetic disorders which lead to body iron overload. It has been shown that iron overload predisposes humans to an increased risk of cancer. In experimental animals, iron overload is known to enhance intestinal, colon, hepatic, pulmonary and mammary carcinogenesis. However, the mechanism by which iron overload enhances chemically-induced carcinogenesis is not known. In this study, we show that iron overload acts as a mild tumor promoter in mouse skin. Female albino swiss mice were given 1 mg iron/mouse parenterally for 2 weeks to induce iron overload. These animals showed a three-fold increase in cutaneous iron concentration as compared to normal mice. Tumors were initiated by topically applying 7,12-dimethylbenz(a)anthracene (DMBA). Appearance of the first tumor (latency period), percent tumor incidence and number of tumors/mouse were recorded. When compared to the control group, iron overload mice showed an increased incidence of tumors, from 25%-55% by week 20, and tumors appeared 4 weeks earlier. The number of tumors per mouse was four-fold higher in the iron overload group. The induction of cutaneous ornithine decarboxylase (ODC) activity and [³H]thymidine incorporation in cutaneous DNA were higher in iron overload groups as compared to normal control animals. Similar to other oxidant tumor promoters, iron overload enhanced cutaneous lipid peroxidation and xanthine oxidase activity and decreased catalase activity. Our results indicate that iron overload exerts a mild tumor promoting activity in mouse skin. Our data also show that oxidative stress generated by iron overload plays an important role in the augmentation of cutaneous tumorigenesis. These data may also have implications for the enhanced risk of cancer-induction following UVB exposure of human populations with iron overload.     

Diversification and evolutionary history of brush-tailed mice,Calomyscidae (Rodentia), in southwestern Asia

Organisms Diversity & Evolution - Brush-tailed mice, family Calomyscidae, are endemic to southwestern Asia and are represented by eight described species and three additional lineages. Although...     

PEST motif serine and tyrosine phosphorylation controls vascular endothelial growth factor receptor 2 stability and downregulation

The internalization and degradation of vascular endothelial growth factor receptor 2 (VEGFR-2), a potent angiogenic receptor tyrosine kinase, is a central mechanism for the regulation of the coordinated action of VEGF in angiogenesis. Here, we show that VEGFR-2 is ubiquitinated in response to VEGF, and Lys 48-linked polyubiquitination controls its degradation via the 26S proteosome. The degradation and ubiquitination of VEGFR-2 is controlled by its PEST domain, and the phosphorylation of Ser1188/Ser1191 is required for the ubiquitination of VEGFR-2. F-box-containing β-Trcp1 ubiquitin E3 ligase is recruited to S1188/S1191 VEGFR-2 and mediates the ubiquitination and degradation of VEGFR-2. The PEST domain also controls the activation of p38 mitogen-activated protein kinase (MAPK) through phospho-Y1173. The activation of p38 stabilizes VEGFR-2, and its inactivation accelerates VEGFR-2 downregulation. The VEGFR-2-mediated activation of p38 is established through the protein kinase A (PKA)/MKK6 pathway. PKA is recruited to VEGFR-2 through AKAP1/AKAP149, and its phosphorylation requires Y1173 of VEGFR-2. The study has identified a unique mechanism in which VEGFR-2 stability and degradation is modulated. The PEST domain acts as a dual modulator of VEGFR-2; the phosphorylation of S1188/S1191 controls ubiquitination and degradation via β-Trcp1, where the phosphorylation of Y1173 through PKA/p38 MAPK controls the stability of VEGFR-2.