A new class of proteins capable of binding transition metals

Ion uptake, transport, and sequestration are essential to meet the nutritional requirements for plant growth and development. Furthermore, regulation of these processes is critical for plants to tolerate toxic levels of ions. The examination of isoprenylated proteins encoded by Arabidopsis thaliana and Glycine max cDNAs revealed a unique family of proteins containing putative metal-binding motifs (the core sequence is M/LXCXXC). Here, we describe this new class of proteins, which are capable of being isoprenylated and binding transition metal ions. Members of this family contain consensus isoprenylation (CaaX) sites, which we demonstrate are efficiently isoprenylated in vitro. ATFP3, a representative of the Arabidopsis family, was expressed in Escherichia coli and examined for metal-binding activity in vitro. Analysis of the interaction of ATFP3 with metal-chelating columns (IMAC) suggested that it binds to Cu²⁺, Ni²⁺, or Zn²⁺. To test whether proteins with these characteristics are present in other plant species, tobacco BY2 cells were labeled in vivo with [¹⁴C]mevalonate and the resulting mevalonate-labeled proteins were tested for metal-binding activity. Several soluble, isoprenylated proteins which bound copper-IMAC columns were revealed. Consistent with a wide-spread distribution of these proteins in plants, their presence was observed in Arabidopsis, soybean, and tobacco.     

The Murine CAR Homolog Is a Receptor for Coxsackie B Viruses and Adenoviruses

Complementary DNA clones encoding the murine homolog (mCAR) of the human coxsackievirus and adenovirus receptor (CAR) were isolated. Nonpermissive CHO cells transfected with mCAR cDNA became susceptible to infection by coxsackieviruses B3 and B4 and showed increased susceptibility to adenovirus-mediated gene transfer. These results indicate that the same receptor is responsible for virus interactions with both murine and human cells. Analysis of receptor expression in human and murine tissues should be useful in defining factors governing virus tropism in vivo.     

Form and environment of Gryphaea arcuata

Gryphaea arcuata is one of the most studied fossils, but its detailed palaeoecology has been largely neglected. Specimens were collected within a short stratigraphic range (three ammonite zones) in the 'Calcaire à gryphées' of Xeuilley (Lorraine, France) dated Hettangian to Lower Sinemurian. As far as possible, they were sampled from each marly bed of the section. A biometric study and an isotopic analysis are compared in regard to organic matter measurements and palynological data, the results demonstrating a clear relationship between the shape of G. arcuata and environmental parameters. Factors responsible for the various shapes are temperature, oxygen levels on the sea floor and nutrient levels. Two main morphotypes can be related to two kinds of environment. In the first, controlled by a relatively hot and humid climate and tending towards eutrophication, the growth rate of Gryphaea was low, and the shells small, wide and thin. In the second environment, cooler than the first one and closer to the optimal living conditions of G. arcuata, the shell was large, thick and narrow, and exhibited a high growth rate.     

Cytokinin regulation of a soybean pollen allergen gene

Cytokinin treatment of suspension-cultured soybean cells stimulated the accumulation of an mRNA, called cim 1, by a factor of ca. 20 within 4 h. Induction of cim 1 mRNA accumulation occurred at benzyladenine concentrations as low as 10^-8 M. Furthermore, cim 1 mRNA accumulation was stimulated in the absence of cytokinin by staurosporine (an inhibitor of protein kinases) and inhibited in the presence of cytokinin by okadaic acid (an inhibitor of protein phosphatases 1 and 2a), suggesting that cim 1 accumulation in response to cytokinin is dependent on cytokinin-induced dephosphorylation of one or more cellular proteins. The deduced amino acid sequence of the cim 1 protein product, derived from the complete nucleotide sequence of a cim 1 cDNA, was 40% identical to that of a perennial rye grass pollen allergen cDNA (Lol Pl). This sequence also indicated that the cim 1 protein product contains a putative signal peptide followed by predominantly hydrophilic residues, consistent with the hypothesis that it is exported to the apoplast.     

Rates and equilibria at the acetylcholine receptor of electrophorus electroplaques. A study of neurally evoked postsynaptic currents and of voltage-jump relaxations

Kinetic measurements are employed to reconstruct the steady-state activation of acetylcholine [Ach] receptor channels in electrophorus electroplaques. Neurally evoked postsynaptic currents (PSCs) decay exponentially; at 15 degrees C the rate constant, α, equals 1.2 ms(-1) at 0 mV and decreases e-fold for every 86 mV as the membrane voltage is made more negative. Voltage-jump relaxations have been measured with bath-applied ACh, decamethonium, carbachol, or suberylcholine. We interpret the reciprocal relaxation time 1/τ as the sum of the rate constant α for channel closing and a first-order rate constant for channel opening. Where measureable, the opening rate increases linearly with [agonist] and does not vary with voltage. The voltage sensitivity of small steady-state conductances (e- fold for 86 mV) equals that of the closing rate α, confirming that the opening rate has little or no additional voltage sensitivity. Exposure to α-bungarotoxin irreversibly decreases the agonist-induced conductance but does not affect the relaxation kinetics. Tubocurarine reversibly reduces both the conductance and the opening rate. In the simultaneous presence of two agonist species, voltage-jump relaxations have at least two exponential components. The data are fit by a model in which (a) the channel opens as the receptor binds the second in a sequence of two agonist molecules, with a forward rate constant to 10(7) to 2x10(8) M(-1)s(-1); and (b) the channel then closes as either agonist molecule dissociates, with a voltage-dependent rate constant of 10(2) to 3x10(3)s(-1).     

Activities of Various Peptidases in the First Leaf of Wheat

In the first leaf of wheat (Triticum aestivum L. cv. Capelle) the content of soluble protein diminished to about 50% of the initial value between the 7th and the 19th day after sowing. In order to understand proteolysis in the leaves, the activities of several peptidases were measured in extracts from leaves at four different ages. The carboxypeptidase activities increased during the growth of the leaves, and then began to decrease. The activities of the alkaline peptidases increased, while that of the benzoyl-DL-arginine-p-nitroanilide (BAPA) hydrolysing enzyme decreased during the whole period studied. The “naphthylamidase” activities showed first a slow rise, but then leveled off. Two bands with naphthylamidase activity could be detected after disc electrophoresis. All the peptidases studied were present in the leaves at rather high concentrations. This indicates that they all may participate in the hydrolysis of leaf proteins into free amino acids.     

Toxicogenomics of resveratrol in rat liver

Resveratrol, a polyphenolic compound found in grape skin and peanuts has been shown to prevent many diseases including cardiovascular diseases and cancer. To better understand resveratrol's potential in vivo toxicity, we studied the dose response using cDNA stress arrays coupled with drug metabolizing enzymatic (DME) assays to investigate the expression of stress-responsive genes and Phase I and II detoxifying enzymes in rat livers. Male and female CD rats were treated with high doses of resveratrol (0.3, 1.0 and 3.0 gm/kg/day) for a period of 28 days. Total RNA from rat liver was reverse-transcribed using gene-specific primers and hybridized to stress-related cDNA arrays. Among female rats, Phase I DME genes were repressed at 0.3 and 1.0 gm/kg/day doses, while genes such as manganese superoxide dismutase, cytochrome P450 reductase, quinone oxidoreductase and thiosulfate sulfurtransferase demonstrated a dose-dependent increase in gene expression. The modulation of these liver genes may implicate the potential toxicity as observed among the rats at the highest dose level of resveratrol. Real-Time PCR was conducted on some of the Phase II DME genes and anti-oxidant genes to validate the cDNA array data. The gene expression from real-time PCR demonstrated good correlation with the cDNA array data. UGT1A genes were amongst the most robustly induced especially at the high doses of resveratrol. We next performed Phase I and Phase II enzymatic assays on cytochrome P450 2E1 (CYP2E1), cytochrome P450 1A1 (CYP1A1), NAD(P)H:quinone oxidoreductase (NQO1), glutathione S-transferase (GST) and UDP-glucuronosyl transferase (UGT). Induction of Phase II detoxifying enzymes was most pronounced at the highest dose of resveratrol. CYP1A1 activity demonstrated a decreasing trend among the 3 dose groups and CYP2E1 activity increased marginally among female rats over controls. In summary, at lower doses of resveratrol there are few significant changes in gene expression whereas the modulation of liver genes at the high dose of resveratrol may implicate the potential toxicity observed.     

Changes in the association of low birth weight with socioeconomic status in Hawaii: 1970-1990

This study examines rates of low birth weight (LBW) in the state of Hawaii and changes in the association of LBW with socioeconomic status from 1970 to 1990. The analysis is based on aggregate data for census tracts. Rates of low birth weight were calculated for each census tract. Relative socioeconomic scores were calculated from average household income and years of education. The results show that (1) there was a decrease in the rate of low birth weight infants in Hawaii; and (2) that the correlation between socioeconomic status and low birth weight was substantially reduced, though a significant correlation remains. The paper suggests likely ceiling effects, but that the progressive public health policies and expansion of access to primary health care in Hawaii during this period played a major role in reducing the rate of low birth weight infants and in decreasing socioeconomic inequality on this important health indicator.     

Changes in tissue fibronectin in elastase induced lung injury.

We studied changes in rat lung fibronectin (FN) content and synthesis after endobronchial administration of elastase. A severe hemorrhagic neutrophilic alveolitis ensued with plasma protein leakage, initial rise in tissue FN content, and sustained rise in FN synthesis. Unlike fibrotic models where initial rises in tissue FN levels are sustained, levels in this model normalized promptly. This, in the setting of increased synthesis is consistent with increased degradation. This degradation of tissue FN may result in the disruption of the lung architecture, interfere with the deposition of newly synthesized matrix and could partly explain the development of emphysema in a model where excess fibronectin synthesis is observed.     

Sixty simple sequence repeat markers for use in the Festuca–Lolium complex of grasses

So far only very few simple sequence repeat (SSR) markers developed from grass species have had their primer sequences published. To make more markers available to the scientific community, we isolated and sequenced 256 microsatellite‐containing clones from four genome libraries of a Lolium multiflorum×Festuca glaucescens F₁ hybrid following enrichment in (TC)_n, (TG)_n, or both repeats. In this work, we report the primer sequences of 60 SSRs including preliminary results of polymorphism for mapping.