Effects of 28-homobrassinolide on nickel uptake,protein content and antioxidative defence system in <Emphasis Type="Italic">Brassica juncea</Emphasis>

The effects of 28-homobrassinolide (HBL) on nickel uptake, protein content and activities of antioxidative enzymes were determined in the seedlings of Brassica juncea L. The seeds were treated with different concentrations (0, 0.01, 1 and 100 nM) of HBL for 8 h and then sown in the Petri plates containing various concentrations (0, 25, 50 and 100 mg dm⁻³) of nickel. After 7 d, observations were made on shoot and root length, Ni uptake, protein content and activities of antioxidative enzymes (guaiacol peroxidase, catalase, glutathione reductase, ascorbate peroxidase and superoxide dismutase). The growth of seedlings was inhibited by Ni, however, less after HBL pre-treatment. The protein content and antioxidative enzyme activities were also increased by HBL treatment.     

<Emphasis Type="Italic">Chenopodium</Emphasis>: a prospective plant for phytoextraction

Leaf samples were collected from 40 accessions of Chenopodium spp. and assessed for six heavy metals (Fe, Zn, Cu, Ni, Cr and Cd) accumulation to explore the use of Chenopodium for phytoextraction of heavy metals. The results suggest that Chenopodium spp. have the ability to accumulate large quantities of heavy metals in the leaf tissues even when they are present in low concentrations in the soil. C. quinoa is a better accumulator of Ni, Cr and Cd than the rest of the species, while C. album accessions are good copper accumulators. Bioconcentration factor for chromium ranged from 0.36 (C. album “Chandanbathua”) to 6.57 (C. quinoa Ames 13719) with 13 accessions of C. quinoa scoring above the mean value. High heritability coupled with high genetic advance was recorded for Ni, Cr and Cd, which indicated a major role of additive gene action in the inheritance of these characters. Zinc showed significant positive association with iron (0.351**), nickel (0.659**), chromium (0.743**) and cadmium (0.288**). Nickel was significantly and negatively associated with copper (−0.663**), while it was positively and significantly correlated with chromium (0.682**) and cadmium (0.461**). Considering the accumulation efficiency of Chenopodium spp. with respect to heavy metals, this genus should be further explored for decontamination of metal polluted soils, with plant breeding playing an important role in evolving new plant types with higher capacity of heavy metal accumulation.     

Awake negative pressure reflex response of the genioglossus in OSA patients and normal subjects.

We hypothesized that the response of the genioglossus to negative pressure during wakefulness should be intact in obstructive sleep apnea (OSA) patients despite published evidence showing impairment of the response of palatal muscles (Mortimore IL and Douglas NJ. Am J Respir Crit Care Med 156: 867-873, 1997). Thus the response of the genioglossus to brief nasal negative pressure applications (NPAs) in early inspiration was compared between OSA patients and an age-matched group of normal subjects at two study sites (n = 11 per group in Long Beach, n = 14 per group in Boston). Subjects were studied in the sitting (Long Beach) or supine (Boston) posture, and the genioglossus electromyogram (EMGgg) was measured with an intraoral surface electrode (Long Beach) or intramuscular electrode (Boston). The response of the EMGgg was expressed as the percent change from baseline where the baseline EMGgg was the value at the onset of the NPA. In Long Beach, the EMGgg response was significantly higher in the OSA patients at a lower suction pressure of approximately 10 cmH(2)O (75.2 +/- 8.4 vs. 37.4 +/- 4.0% increase; P < 0.001) but not at a higher suction pressure of approximately 20 cmH(2)O. In Boston, the response in the OSA patients was also greater (107.2 +/- 25.9 vs. 46.3 +/- 8.3%; P < 0.05) at a suction pressure of approximately 13 cmH(2)O. We conclude that the response of the genioglossus to NPA during wakefulness is not impaired in OSA patients compared with normal subjects and is greater at low suction pressures.     

Tethering and tickling: a new role for the phosphatidylserine receptor

Several receptors are implicated in apoptotic cell (AC) uptake by phagocytic cells; however, their relative dominance in mammalian systems remains to be established. New studies shed light on the role of the phosphatidyl serine (PS) receptor (PSR). Ligation of PSR by PS on AC surfaces is considered essential for signaling uptake of ACs that are tethered to phagocytes via other receptors.     

Photoluminescent properties of novel design heteroleptic Zn(II) complexes

Three novel heteroleptic Zn(II) complexes containing 8‐hydroxy quinoline and various pyrazolone‐based derivatives were synthesized and their structures confirmed by ¹H–nuclear magnetic resonance, mass spectrometry, Fourier transform infra‐red spectroscopy, UV–vis analysis and element analysis. All three complexes showed good photoluminescence properties in the solid state and in solution in the maximum emission range from 475 to 490 nm with a quantum yield of 0.45 to 0.51. Absorption spectra revealed that the complexes possessed a maximum absorption range of 272–281 nm with a band gap of 2.59–2.68 eV. The highest occupied molecular orbital and lowest unoccupied molecular orbital of all the complexes were determine by cyclic voltammetry. All complexes displayed high thermal stability. These characteristics were assessed to find suitability for an alternative cheap light emitter for organic light‐emitting diodes.     

Correlation between gene expression profiles and protein-protein interactions within and across genomes

MOTIVATION: Function annotation of an unclassified protein on the basis of its interaction partners is well documented in the literature. Reliable predictions of interactions from other data sources such as gene expression measurements would provide a useful route to function annotation. We investigate the global relationship of protein-protein interactions with gene expression. This relationship is studied in four evolutionarily diverse species, for which substantial information regarding their interactions and expression is available: human, mouse, yeast and Escherichia coli. RESULTS: In E.coli the expression of interacting pairs is highly correlated in comparison to random pairs, while in the other three species, the correlation of expression of interacting pairs is only slightly stronger than that of random pairs. To strengthen the correlation, we developed a protocol to integrate ortholog information into the interaction and expression datasets. In all four genomes, the likelihood of predicting protein interactions from highly correlated expression data is increased using our protocol. In yeast, for example, the likelihood of predicting a true interaction, when the correlation is > 0.9, increases from 1.4 to 9.4. The improvement demonstrates that protein interactions are reflected in gene expression and the correlation between the two is strengthened by evolution information. The results establish that co-expression of interacting protein pairs is more conserved than that of random ones.     

Amide derivatives of 9,11-seco-estra-1,3,5(10)-trien-11-oic acid as modified orally active estrogen agonists with moderate antagonistic activity

Synthesis of amide derivatives of 9,11-seco-estra-1,3,5(10)-trien-11-oic acid containing alkyl and aromatic amine residues has been carried out with an aim to prepare orally active estrogen antagonists. Modification of the estradiol molecule in the form of C-seco-amide derivatives has led to their high oral absorption. Compounds 7 an n-propyl amide, 8 an n-butyl amide, and 16 a p-anisidyl amide of C-seco-estrane showed significant estrogen antagonistic activity (>20%), while, the majority of compounds possessed high estrogen agonistic activity on oral administration at 10mg/kg dose in rats.     

The dynamics of single-substrate continuous cultures: the role of ribosomes

When a chemostat is perturbed from its steady state, it displays complex dynamics. For instance, if the identity of the growth-limiting substrate is switched abruptly, the substrate concentration and cell density undergo a pronounced excursion from the steady state that can last several days. These dynamics occur because certain physiological variables respond slowly. In the literature, several physiological variables have been postulated as potential sources of the slow response. These include transport enzymes, biosynthetic enzymes, and ribosomes. We have been addressing this problem by systematically exploring the role of these variables. In previous work Shoemaker et al. (J. Theor. Biol., 222 (2003) 307-322), we studied the role of transport enzymes, and we showed that transients starting from low transport enzyme levels could be quantitatively captured by a model taking due account of transport enzyme synthesis. However, there is some experimental data indicating that slow responses occur even if the initial enzyme levels are high. Here, we analyse this data to show that in these cases, the sluggish response is most probably due to slow adjustment of the ribosome levels. To test this hypothesis, we extend our previous model by accounting for the evolution of both the transport enzyme and the ribosomes. Based on a kinetic analysis of the data in the literature, we assume that the specific protein synthesis rate is proportional to the ribosome level, and the specific ribosome synthesis rate is autocatalytic. Simulations of the model show remarkable agreement with experimentally observed steady states and the transients. Specifically, the model predictions are in good agreement with (1) the steady-state profiles of the cell density, substrate concentration, RNA, proteins, and transport enzymes, (2) the instantaneous specific substrate uptake, growth, and respiration rates in response to a continuous-to-batch shift, and (3) the transient profiles of the cell density, substrate concentration, and RNA in response to feed switches and dilution rate shifts. Time-scale analysis of the model reveals that every transient response is a combination of two fundamental (and simpler) dynamics, namely, substrate-sufficient batch dynamics and cell-sufficient fed-batch dynamics. We obtain further insight into the transient response by analysing the equations describing these fundamental dynamics. The analysis reveals that in feed switches or dilution rate shift-ups, the transport enzyme reaches a maximum before RNA achieves its maximum, and in dilution rate shift-downs the cell density reaches a maximum before RNA achieves a minimum.     

RAD51 is involved in repair of damage associated with DNA replication in mammalian cells

The RAD51 protein, a eukaryotic homologue of the Escherichia coli RecA protein, plays an important role in the repair of DNA double-strand breaks (DSBs) by homologous recombination (HR) in mammalian cells. Recent findings suggest that HR may be important in repair following replication arrest in mammalian cells. Here, we have investigated the role of RAD51 in the repair of different types of damage induced during DNA replication with etoposide, hydroxyurea or thymidine. We show that etoposide induces DSBs at newly replicated DNA more frequently than gamma-rays, and that these DSBs are different from those induced by hydroxyurea. No DSB was found following treatment with thymidine. Although these compounds appear to induce different DNA lesions during DNA replication, we show that a cell line overexpressing RAD51 is resistant to all of them, indicating that RAD51 is involved in repair of a wide range of DNA lesions during DNA replication. We observe fewer etoposide-induced DSBs in RAD51-overexpressing cells and that HR repair of etoposide-induced DSBs is faster. Finally, we show that induced long-tract HR in the hprt gene is suppressed in RAD51-overexpressing cells, although global HR appears not to be suppressed. This suggests that overexpression of RAD51 prevents long-tract HR occurring during DNA replication. We discuss our results in light of recent models suggested for HR at stalled replication forks.