Physical mechanisms and scaling laws of K-shell double photoionization

We report on the photon energy dependence of the K-shell double photoionization (DPI) of Mg, Al, and Si. The DPI cross sections were derived from high-resolution measurements of x-ray spectra following the radiative decay of the K-shell double vacancy states. Our data evince the relative importance of the final-state electron-electron interaction to the DPI. By comparing the double-to-single K-shell photoionization cross-section ratios for neutral atoms with convergent close-coupling calculations for He-like ions, the effect of outer shell electrons on the K-shell DPI process is assessed. Universal scaling of the DPI cross sections with the effective nuclear charge for neutral atoms is revealed.

Cytogenetic analyses of intergeneric hybrids between barley and nine species of Elymus

Wild species in the Triticeae tribe are very valuable resources for agronomic improvement in cereal crop species. Intergeneric hybrids were produced between several barley cultivars and perennial species in the genera Elymus, Thinopyrum, and Pseudoroegneria. Caryopsis formation and subsequent plantlet regeneration from embryo culture were variable depending on the hybrid combinations. Chromosome numbers and hybrid identity were confirmed by GISH analysis on the somatic cells of the hybrids. While the hybrids showed very robust vegetative growth and exceeded the parental spikes in size, their floral morphologies resembled that of the wild species. Meiotic chromosome analysis revealed that the bivalent formation frequency per cell ranged from 0.06 in Hordeum vulgare 'Betzes' x Elymus curvatus to 3.0 in Elymus humidus x H. vulgare 'Manley'. By GISH analysis on the meiocytes of the hybrid E. humidus x 'Manley', the frequency of autosyndetic bivalents exceeded the allosyndetic bivalent formation, which gave an insight into the genome constitution of E. humidus as an autoallohexploid species. Regardless of the low allosyndetic chromosome pairing between barley and E. humidus, this combination may be useful for further input, since E. humidus is known to carry many valuable genes for biotic and abiotic stress tolerance.

Application of radiation hybrid in gene mapping

Radiation hybrid (RH) mapping technique was exploited to determine chromosome locations of 26 human novel full length cDNAs recently cloned. All these cDNA clones were isolated from human cord blood CD (+) (34) cells and may be related to regulation of hematopoiesis. 23 genes were successfully mapped to chromosomal positions, while RH analyses were not possible in the remaining 3 cases. RH technique is indeed a powerful tool for mapping novel cDNA sequences due to its rapidity, precision, convenience and reproducibility.

Progesterone withdrawal up-regulates fibronectin and integrins during menstruation and repair in the rhesus macaque endometrium

BACKGROUND

Fibronectin (FN) is a component of the extracellular matrix that participates in wound healing in various tissues as an adhesive ligand for integrins (Itgs). To determine whether these molecules play similar roles during menstrual repair, we evaluated the expression and localization of FN and specific Itgs in the primate endometrium under hormonally controlled conditions.

METHODS

Ovariectomized rhesus macaques were treated for 2 weeks with estradiol (E(2)) followed by E(2) with progesterone for 2 weeks. On day 28, progesterone was withdrawn and uteri were collected during menstruation, postmenstrual repair, and the proliferative and secretory phases. Analysis was by focused microarray, real time PCR, in situ hybridization and immunocytochemistry.

RESULTS

Progesterone withdrawal induced significant elevations of FN, Itg alpha5 and Itg beta1 transcripts during menstruation as compared to day 28 (FN: P < 0.01; Itg alpha5: P < 0.05; Itg beta1: P < 0.05; real time PCR). These increases were concentrated in the glandular epithelium (FN) and stroma (Itg alpha5beta1) of the uppermost zones. Cyclic changes in Itg alpha3 occurred in the glandular epithelium.

CONCLUSIONS

Spatially and temporally restricted peaks of expression of FN and its Itg receptors are closely correllated with menstruation and postmenstrual repair in the primate endometrium.

Relative detection efficiency of back- and front-illuminated charge-coupled device cameras for X-rays between 1 keV and 18 keV

High-resolution x-ray measurements were performed with a von Hamos-type bent crystal spectrometer using for the detection of the diffracted photons either a back-illuminated charge-coupled device (CCD) camera or a front-illuminated one. For each CCD the main x-ray emission lines (e.g., Kalpha, Kbeta, Lalpha, and Lbeta) of a variety of elements were measured in order to probe the performances of the two detectors between 1 and 18 keV. From the observed x-ray lines the linearity of the energy response, the noise level, the energy resolution, and the quantum efficiency ratio of the two CCDs were determined.

Fluorescence of 2-aminopurine reveals rapid conformational changes in the RB69 DNA polymerase-primer/template complexes upon binding and incorporation of matched deoxynucleoside triphosphates

We have used 2-aminopurine (2AP) as a fluorescent probe in the template strand of a 13/20mer primer/template (D) to detect deoxynucleoside triphosphates (N)-dependent conformational changes exhibited by RB69 DNA polymerase (ED) complexes. The rates and amplitudes of fluorescence quenching depend hyperbolically on the [dTTP] when a dideoxy-primer/template (ddP/T) with 2AP as the templating base (n position) is used. No detectable fluorescence changes occur when a ddP/T with 2AP positioned 5' to the templating base (n + 1 position) is used. With a deoxy-primer/template (dP/T) with 2AP in the n position, a rapid fluorescence quenching occurs within 2 ms, followed by a second, slower fluorescence quenching with a rate constant similar to base incorporation as determined by chemical quench. With a dP/T having 2AP in the n + 1 position, there is a [dNTP]-dependent fluorescence enhancement that occurs at a rate comparable to dNMP incorporation. Collectively, the results favor a minimal kinetic scheme in which population of two distinct biochemical states of the ternary EDN complex precedes the nucleotidyl transfer reaction. Observed differences between dP/T and ddP/T ternary complexes indicate that the 3' hydroxyl group of the primer plays a critical role in determining the rate constants of transitions that lead to strong deoxynucleoside triphosphate binding prior to chemistry.

Polymorphisms of 5,10-methylenetetralydrofolate reductase (MTHFR), fruit and vegetable intake, and the risk of stomach cancer

Stomach cancer is a serious public health problem in China. 5,10-Methylenetetralydrofolate reductase (MTHFR) may be involved in both DNA methylation and DNA synthesis. Folate deficiency is associated with cancer risk that may be modulated by a genetic variation in the MTHFR gene in folate metabolism. The main goal of this study was to evaluate the association between polymorphisms of the MTHFR gene and the risk of stomach cancer. This study also explored the modification effects of fruit and vegetable intake (one of the main constituents is folate) on the risk of this disease. A population-based case-control study was conducted in Taixing, China, consisting of 206 newly diagnosed cases with primary stomach cancer and 415 healthy population controls. Polymorphisms of MTHFR C677T and A1298C were assayed by polymerase chain reaction-restricted fragment length polymorphism (PCR-RFLP) techniques. The data were analysed using the logistic regression model. No obvious association between the MTHFR A1298C polymorphism and the risk of stomach cancer was observed in this study. The frequencies of 677 C/C, C/T, and T/T were 34.5, 50.9, and 14.6%, respectively, in controls. The frequency of the MTHFR 677 wild homozygotic genotype was 25.8% in cases, which was lower than that in controls (34.5%). The adjusted odds ratio (OR) for the MTHFR 677 any T genotype was 2.05 (95% confidence interval (CI), 1.26-3.34) when compared with the C/C genotype. In the low fruit and vegetable intake group an increasing trend was observed with the T allele exposure, p = 0.0056. The adjusted ORs were 1.68 (95% CI = 0.86-3.29) for the C/T genotype and 3.58 (95% CI = 1.46-8.75) for the T/T genotype, respectively. The MTHFR 677 any T genotype was associated with an increased risk of primary stomach cancer among the Chinese population. Folate deficiency might modify the MTHFR gene polymorphism and influence the risk of stomach cancer.

Joint association of polymorphism of the FGFR4 gene and mutation TP53 gene with bladder cancer prognosis

The impact of the fibroblast growth factor receptor 4 (FGFR4) Gly388Arg polymorphism on bladder cancer is unknown. We found no clear correlations between the FGFR4 genotype and risk of bladder cancer or pathological parameters. Neither the polymorphism nor TP53 mutation status was an independent predictor of prognosis, but they might act jointly on the disease-specific survival of patients.

Only low levels of exogenous N-acetyltransferase can be achieved in transgenic mice

Therapeutic and environmental aromatic amines and hydrazines are substrates for the arylamine N-acetyltransferases (NAT). In all, 10 transgenic lines containing either the human NAT1 or NAT2 transgene were developed using multiple promoters. The presence of the transgene was confirmed by determining copy number, mRNA and enzyme activity. Despite some lines having high copy numbers of the transgene, only modest or no increases in enzymatic activity could be found in a variety of tissues. The NAT1 transgene could not be bred to homozygosity. The cytomegalovirus (CMV)-promoted NAT1 transgene increased endogenous Nat1 mRNA levels in liver and had little effect on endogenous Nat2 mRNA levels. The presence of the CMV-promoted NAT2 transgene appeared to suppress endogenous hepatic Nat2 mRNA, but did not alter Nat1 mRNA levels. The failure to achieve high expression of any of the transgenes suggests that overexpression of NAT genes may have harmful effects during development.

Numerical simulations of negative-index refraction in wedge-shaped metamaterials

A wedge-shaped structure made of split-ring resonators (SRR) and wires is numerically simulated to evaluate its refraction behavior. Four frequency bands, namely, the stop band, left-handed band, ultralow-index band, and positive-index band, are distinguished according to the refracted field distributions. Negative phase velocity inside the wedge is demonstrated in the left-handed band and the Snell's Law is conformed in terms of its refraction behaviors in different frequency bands. Our results confirmed that negative index of refraction indeed exists in such a composite metamaterial and also provided a convincing support to the results of previous Snell's Law experiments.

Haplotype diversity at fusarium head blight resistance QTLs in wheat

Fusarium head blight (FHB) reduces grain yield and quality in common and durum wheat. Host FHB resistance is an effective control measure that is achieved by stacking multiple resistance genes into a wheat line. Therefore, breeders would benefit from knowing which resistance sources carry different resistance genes. A diverse collection of FHB-resistant and -susceptible wheat lines was characterized with microsatellite markers linked to FHB resistance quantitative trait loci (QTLs) on chromosomes 2DL, 3BS (distal to the centromere), 3BSc (proximal to the centromere), 4B, 5AS and 6BS identified in wheat lines Maringa, Sumai 3 and Wuhan 1. Putative Sumai 3 QTLs were commonly observed in advanced breeding lines, whereas putative Maringa and Wuhan 1 QTLs were relatively rare. Marker data suggested the 3BS, 3BSc and 5AS QTLs in the Brazilian cv. Maringa were derived from Asian germplasm and not from Frontana or other Brazilian lines. Haplotype diversity was reduced near the 5AS QTL, which might impact the deployment of this QTL. Finally, Brazilian germplasm was not closely related to other resistance sources and might be useful for pyramiding with Asian wheat-derived FHB resistance.

Effect of antisense oligodeoxynucleotide directed to NF-kappa B-RelA on Bcl-XL mRNA in extended drug resistance leukemia cell line HL-60/E6

To explore the effect of NF-kappa B on bcl-x gene transcription in extended drug resistance leukemia cell line HL-60/E6, drug-resistant subline HL-60/E6 was derived by intermittently exposing HL-60 cells to 6 ng/ml epirubicin. Indirect immunofluorescence was used to demonstrate the location of NF-kappa B-RelA in HL-60/E6 cells. FCM analysis and RT-PCR were used to detect the efficiency of liposome-mediated ODN transfection and the change of bcl-XL mRNA levels after 5 mumol/L phosphorothioate (PS)-derivatized antisense (AS) oligodeoxynucleotide (ODN) directed to RelA was transferred into HL-60/E6 cells. The results showed that RelA remained persistently active and located at the nuclei of HL-60/E6 cells, but in the cytoplasm of HL-60 cells, the efficiency of liposome-mediated ODN transfection was significantly higher than that of null ODN (P < 0.01 in 4 h, 6 h, 12 h, 24 h). Exposure of HL-60/E6 cells to 5 mumol/L AS-PS-ODN directed to RelA led to a maximal 40% decline of bcl-XL mRNA levels within 8 h. The inhibition rate of bcl-XL mRNA was (15 +/- 1.79)%, (28 +/- 2.34)%, (40 +/- 3.47)%, (20 +/- 1.54)%, in 4 h, 6 h, 8 h, 15 h, respectively, but it was less than 15% in control group. It was concluded that NF-kappa B was involved in regulating bcl-x transcription. It was suggested that NF-kappa B was an important factor for drug resistance in leukemia cells.

Adrenoceptors, uncoupling proteins, and energy expenditure

Interest in the biology of adipose tissue has undergone a revival in recent years with the discovery of a host of genes that contribute to the regulation of satiety and metabolic rate. The catecholamines have long been known to be key modulators of adipose tissue lipolysis and the hydrolysis of triglyceride energy stores. However, more recent efforts to understand the role of individual adrenergic receptor subtypes expressed in adipocytes and their signal transduction pathways have revealed a complexity not previously appreciated. Combined with this interest in the modulation of adipocyte metabolism is a renewed focus upon brown adipose tissue and the mechanisms of whole body thermogenesis in general. The discovery of novel homologs of the brown fat uncoupling protein (UCP) such as UCP2 and UCP3 has provoked intensive study of these mitochondrial proteins and the role that they play in fuel metabolism. The story of the novel UCPs has proven to be intriguing and still incompletely understood. Here, we review the status of adipose tissue from inert storage depot to endocrine organ, interesting signal transduction pathways triggered by beta-adrenergic receptors in adipocytes, the potential of these receptors for discriminating and coordinated metabolic regulation, and current views on the role of UCP2 and UCP3 based on physiological studies and gene knockout models.