Early Forest Soils and Their Role in Devonian Global Change

A paleosol in the Middle Devonian Aztec Siltstone of Victoria Land, Antarctica, is the most ancient known soil of well-drained forest ecosystems. Clay enrichment and chemical weathering of subsurface horizons in this and other Devonian forested paleosols culminate a long-term increase initiated during the Silurian. From Silurian into Devonian time, red clayey calcareous paleosols show a greater volume of roots and a concomitant decline in the density of animal burrows. These trends parallel the decline in atmospheric carbon dioxide determined from isotopic records of pedogenic carbonate in these same paleosols. The drawdown of carbon dioxide began well before the Devonian appearance of coals, large logs, and diverse terrestrial plants and animals, and it did not correlate with temporal variation in volcanic or metamorphic activity. The early Paleozoic greenhouse may have been curbed by the evolution of rhizospheres with an increased ratio of primary to secondary production and by more effective silicate weathering during Silurian time.     

Thyroid hormone action: a cell-culture system responsive to physiological concentrations of thyroid hormones

Cells from a rat pituitary tumor cell line will respond in vitro to physiological concentrations of L-thyroxine and L-triiodothyronine. The cells are grown in a cultutre medium that contains serum from a hypothyroid calf. Dose-response relationships of a vacriety of thyronine derivatives indicate that this system has a specificity of response which is similar to that observed in vitro.     

Determination of naringin in rat blood,brain, liver,and bile using microdialysis and its interaction with cyclosporin a,a p-glycoprotein modulator

To determine naringin levels in various biological fluids, we developed an in vivo microdialysis technique coupled with a microbore HPLC system to investigate the pharmacokinetics of naringin and its interaction with cyclosporin A in rat blood, brain, liver, and bile. After naringin administration, naringin was undetectable in the brain; the distribution ratios of area under the curve (AUC) of liver over that in blood (AUC(liver)/AUC(blood)) and of AUC of bile over that in blood (AUC(bile)/AUC(blood)) of naringin were 5.39 +/- 0.94 and 29.17 +/- 3.58, respectively. When cyclosporin A (20 mg/kg) was concomitantly administered with naringin (30 mg/kg), the naringin was detected in brain dialysate, but the distribution ratios of liver and bile showed no statistical difference. These results suggest that naringin was concentrated in the liver and bile by the processes of active transport. The blood-brain barrier penetration of naringin may be enhanced by P-glycoprotein inhibitor; however, the pathway of hepatobiliary excretion of naringin may not be related to the P-glycoprotein.     

Visibility Variation with Air Qualities in the Metropolitan Area in Southern Taiwan

Principal component analysis (PCA) was used to analyze variationsin visibility compared with (1) variations in meteorological variables in the period 1961 to 1998, and (2) criteria air pollutant (SO₂, CO, O₃, NO_x and PM₁₀) concentrations monitored between 1994 and 1998, in the Kaohsiungmetropolitan area. Whilst average visibility during the 1960'sexceeded 20km, it had deteriorated to 5–10 km in theperiod 1994 to 1998. PCA identified seven components witheigenvalues greater than one. The principal componentsidentified accounted for variability related to PM₁₀concentration, ozone-related pollutants, oil combustion,and traffic emissions. Furthermore, spatial and temporalvariations in PM₁₀ were consistent throughout thecity. Variation in SO₂ levels followed a similarpattern at Tsoying, Shanming, Chiankin and Chiancheng.Industrial pollution and traffic emissions, SO₂, COand NO_x, from the Hsiaokang area remained within thearea. However, similar patterns of SO₂ andNO_xat Fengshan and Jenwu indicate that industrial emissionsfrom the latter were probably transported to the former.Much of the first principal component is based onPM₁₀ variability, suggesting that, of the fivecriteria pollutants studied, PM₁₀ is the majorcontributor to visibility deterioration. It is known thatPM_2.5 concentration is more closely associated withvisibility changes than is PM₁₀. However, becausePM₁₀ and PM_2.5 are strongly associated inKaohsiung, a targeting reduction in PM₁₀ may imply areduction in visibility.     

Analysis of ambient lead concentrations around three secondary lead smelters

Ambient Pb concentrations measured over a 30 mo span around three secondary Pb smelters in the City of Winnipeg, Manitoba, Canada are statistically analyzed. The results obtained are compared with the provincial regulatory air quality guideline. The contribution of smelter emissions to high Pb levels that exceed the provincial guideline is also demonstrated. It is concluded, by inference, that the Secondary Lead Smelter National Emission Standards Regulations were effectively implemented.     

Substitution of Chaetoceros muelleri by Spirulina platensis meal in diets for Litopenaeus schmitti larvae

The nutritional response of Litopenaeus schmitti larvae to substitution of Chaetoceros muelleri by Spirulina platensis meal (SPM) was evaluated. The substitution levels (S) were 0%, 25%, 50%, 75% and 100%, dry weight basis. Final larval length (FL) ranged from 1.98 to 3.16 mm for the different substitution levels. There was a significant relationship between S and FL, described by the following quadratic equation: FL = 2.853 + 0.01598S − 0.000233S². The substitution level (S) yielding maximum FL was 34.2%. Development index (DI) values ranged from 2.84 to 3.93 and were dependent on substitution level. The corresponding equation was DI = 3.799 + 0.00945S − 0.000189S² (P < 0.01). Maximum DI was obtained at 25.0% substitution. Survival was high (82–87%) and no significant differences were found between treatments. Protein digestibility of either microalgae was high, with 92% for SPM and 94% for C. muelleri, with no significant differences between them. The results in this study indicate that an adequate balance of nutrients in relation to the requirements of the species is critical. To simultaneously improve FL and DI, a 30% substitution of C. muelleri by SPM is suggested. This is equivalent to feeding 0.15 mg larvae^− 1 day^− 1 dry weight basis of a 70% C. muelleri/30% SPM diet, representing 0.078 mg protein larvae^− 1 day^− 1, 0.026 mg lipids larvae^− 1 day^− 1 and 2.732 J larvae^− 1 day^− 1.     

Genetic Characterization of Brazilian Annual <Emphasis Type="Italic">Arachis</Emphasis> Species from Sections <Emphasis Type="Italic">Arachis</Emphasis> and <Emphasis Type="Italic">Heteranthae</Emphasis> using RAPD Markers

The genus Arachis is divided into nine taxonomic sections. Section Arachis is composed of annual and perennial species, while section Heteranthae has only annual species. The objective of this study was to investigate the genetic relationships among 15 Brazilian annual accessions from Arachis and Heteranthae using RAPD markers. Twenty-seven primers were tested, of which nine produced unique fingerprintings for all the accessions studied. A total of 88 polymorphic fragments were scored and the number of fragments per primer varied from 6 to 17 with a mean of 9.8. Two specific markers were identified for species with 2n = 18 chromosomes. The phenogram derived from the RAPD data corroborated the morphological classification. The bootstrap analysis divided the genotypes into two significant clusters. The first cluster contained all the section Arachis species, and the accessions within it were grouped based upon the presence or absence of the ‘A’ pair and the number of chromosomes. The second cluster grouped all accessions belonging to section Heteranthae.     

Quercetin and rutin reduced the bioavailability of cyclosporine from Neoral, an immunosuppressant, through activating P-glycoprotein and CYP 3A4

Quercetin and rutin are popular flavonoids in plant foods, herbs, and dietary supplements. Cyclosporine (CSP), an immunosuppressant with a narrow therapeutic window, is a substrate of P-glycoprotein (P-gp) and cytochrome P-450 3A4 (CYP3A4). This study investigated the effects of quercetin and rutin on CSP pharmacokinetics from Neoral and relevant mechanisms. Rats were orally administered Neoral with and without quercetin or rutin. The blood CSP concentration was assayed by a specific monoclonal fluorescence polarization immunoassay. The results showed that quercetin and rutin significantly decreased the C(max) of CSP by 67.8 and 63.2% and reduced the AUC(0-540) by 43.3 and 57.2%, respectively. The in vitro studies indicated that the quercetin and rutin induced the functions of P-gp and CYP3A4. In conclusion, quercetin and rutin decreased the bioavailability of CSP through activating P-gp and CYP3A. Transplant patients treated with Neoral should avoid concurrent consumption of quercetin or rutin to minimize the risk of allograft rejection.