Effects of irradiance on relative growth rates, net assimilation rates, and leaf area partitioning in cotton and three associated weeds

Cotton (Gossypium hirsutum L. var. `Stoneville 213'), velvetleaf (Abutilon theophrasti Medic.), redroot pigweed (Amaranthus retroflexus L.), and hemp sesbania (Sesbania exaltata [Raf.] Cory) were grown in a controlled environment room at 31/25 C day/night temperature and three irradiances: 90, 320, and 750 μeinsteins meter⁻² second⁻¹. From total dry weights and leaf areas determined at intervals during the first exponential phase of growth, we used mathematical growth analysis techniques to calculate net assimilation rates (NAR), relative growth rates (R_w), relative leaf area expansion rates (R_a), leaf area partition coefficients (LAP), and leaf area ratios (LAR). In all four species, R_w, R_a, and NAR decreased with decreasing growth irradiance, while LAP and LAR increased. Within each species, R_w was positively correlated with NAR but negatively correlated with LAP and LAR. In comparisons among the four species within each growth irradiance, R_w was positively correlated with LAP. We discuss the relationship between LAP and LAR and show that LAP = (R_a/R_w) (LAR).     

From dogs to frogs: how pets, laboratory animals, and wildlife aided in elucidating harmful effects arising from a hazardous dumpsite

The medical literature contains many examples of cases in which serendipitous observations have led to important findings. In the example described in this article, laboratory and field observations conducted at the Mohawk Nation Community of Akwesasne led to the important and unexpected finding that frogs once plentiful in the area were no longer observed. Laboratory tests comparing river sediments from Akwesasne to pristine sediment from Ithaca, NewYork, indicated multiple adverse health effects on developing frogs. Some of the behavioral changes observed in the laboratory were similar to those described by residents of Akwesasne before the onset of amphibian decline. The magnitude of changes paralleled frog body burden of polychlorinated biphenyls acquired from the Akwesasne sediment. The impact of these findings on the identification of a hazardous waste site and global amphibian decline are discussed.     

Introns in chloroplast protein-coding genes of land plants

Several protein-coding genes from land plant chloroplasts have been shown to contain introns. The majority of these introns resemble the fungal mitochondrial group II introns due to considerable nucleotide sequence homology at their 5 and 3 ends and they can readily be folded to form six hairpins characteristic of the predicted secondary structure of the mitochondrial group II introns. Recently it has been demonstrated that some mitochondrial group II introns are capable of self-splicing in vitro in the absence of protein co-factors. However evidence presented in this overview suggests that this is probably not the case for chloroplast introns and that trans-acting factors are almost certainly involved in their processing reactions.Abbreviations kop kilobase pairs - ORF Open Reading Frame - pre-RNA precursor ribonucleic acid     

A Simple Method for Stabilizing and Granulating Fungi

A simple method, 'Stabileze', is described for granulating fungi with water-absorbent starch, sucrose, corn oil and silica. The potential biological control fungi, Colletotrichum gloeosporioides and Fusarium oxysporum , were stabilized using this protocol. Bioassays were performed on C. gloeosporioides and showed retention of pathogenicity. Sucrose and oil were tested for their effects on the viability of F. oxysporum over time, and sucrose appears to be the most beneficial factor.     

Evaluation of an entomopathogenic fungus, Paecilomyces fumosoroseus (Wize) Brown and Smith (Deuteromycota: Hyphomycetes) obtained from Formosan subterranean termites (Isop., Rhinotermitidae)

Abstract:  An isolate of Paecilomyces fumosoroseus was obtained from Coptotermes formosanus collected in Hong Kong, and a commercially available isolate of Metarhizium anisopliae , were both tested against C. formosanus shipped live from China. Survivorship of termites treated with a suspension of 5 × 10⁵ M. anisopliae conidia/ml and kept alone declined more rapidly than for those treated at the same concentration of P. fumosoroseus conidia. At a 5 × 10⁶ conidia/ml concentration, no significant differences in terms of termite survivorship were observed between the two fungal species. However, among termites kept in groups of 10 after treatment, those sprayed with P. fumosoroseus conidia at either 5 × 10⁵ or 5 × 10⁶ conidia/ml had significantly lower survivorship than those sprayed with M. anisopliae conidia. All the cadavers of termites treated with P. fumosoroseus and kept alone sporulated and among grouped termites 29% of the cadavers sporulated. By comparison, 53% of the cadavers of termites treated with M. anisopliae and kept alone sporulated, and only 4% of the cadavers of treated termites kept in groups sporulated.     

Relationship Between Medium Salinity, Body Density, Buoyancy and Swimming in Artemia franciscana Larvae: Constraints on Water Column Use?

Body density measurements were carried out on larval Artemia franciscana that had been held for 24 h at either 33 or 100‰ after hatching. Body density was low (1.0308–1.0342 g ml⁻¹) by comparison with marine crustacean zooplankters or benthic freshwater crustaceans, and very stable, being only 0.3% higher in 100‰ than in 33‰. Vertical and horizontal swimming in 2nd instar larvae was studied at 8.5, 17, 34, 50, 100, 150 and 250‰ at 23 °C. At 8.5–50‰ downwards swimming was always significantly faster than upwards swimming, but in 100‰ downwards swimming was much slower than upwards swimming, indicating substantial positive buoyancy. At 150 and 250‰ downwards swimming was impossible. Horizontal swimming speed was unaffected by salinity over the range 8.5–100‰, but could not be studied at 150 and 250‰ as larvae could not leave the surface film. An asymptotic relationship between salinity and viscosity was found over the range 8.5–250‰. Calculations indicate a rise from 1.197 to 1.513 cp between 8.5 and 100‰, but this does not significantly impede horizontal locomotion. It appears that water column use by early stage Artemia larvae, that use a pair of 2nd antennae for rowing-type locomotion, is constrained by the increasing positive buoyancy associated with living at salinities above that corresponding to neutral buoyancy (approximately 48‰).     

Self-reported sugar-sweetened beverage intake among college students

Objective: To characterize sugar‐sweetened beverage intake of college students. Research Methods and Procedures: Undergraduates in an urban southern community campus were surveyed anonymously about sugared beverage consumption (soda, fruit drinks, energy drinks, sports drinks, sweet ice tea) in the past month. Results: Two hundred sixty‐five undergraduates responded (66% women, 46% minority, 100% of volunteers solicited). Most students (95%) reported sugared beverage intake in the past month, and 65% reported daily intake. Men were more likely than women to report daily intake (74% vs. 61%, p = 0.035). Soda was the most common sugar‐sweetened beverage. Black undergraduates reported higher sugared beverage intake than whites (p = 0.02), with 91% of blacks reporting sugar‐sweetened fruit drink intake in the past month and 50% reporting daily consumption. Mean estimated caloric intake from combined types of sugar‐sweetened beverages was significantly higher among black students than whites, 796 ± 941 vs. 397 ± 396 kcal/d (p = 0.0003); the primary source of sugar‐sweetened beverage calories among blacks was sugared fruit drinks (556 ± 918 kcal/d). Younger undergraduates reported significantly higher intake than older students (p = 0.025). Discussion: Self‐reported sugar‐sweetened beverage consumption among undergraduates is substantial and likely contributes considerable non‐nutritive calories, which may contribute to weight gain. Black undergraduates may be particularly vulnerable due to higher sugared beverage intake. Obesity prevention interventions targeting reductions in sugar‐sweetened beverages in this population merit consideration.     

Massively parallel characterization of restriction endonucleases

Restriction endonucleases are highly specific in recognizing the particular DNA sequence they act on. However, their activity is affected by sequence context, enzyme concentration and buffer composition. Changes in these factors may lead to either ineffective cleavage at the cognate restriction site or relaxed specificity allowing cleavage of degenerate ‘star’ sites. Additionally, uncharacterized restriction endonucleases and engineered variants present novel activities. Traditionally, restriction endonuclease activity is assayed on simple substrates such as plasmids and synthesized oligonucleotides. We present and use high-throughput Illumina sequencing-based strategies to assay the sequence specificity and flanking sequence preference of restriction endonucleases. The techniques use fragmented DNA from sequenced genomes to quantify restriction endonuclease cleavage on a complex genomic DNA substrate in a single reaction. By mapping millions of restriction site–flanking reads back to the Escherichia coli and Drosophila melanogaster genomes we were able to quantitatively characterize the cognate and star site activity of EcoRI and MfeI and demonstrate genome-wide decreases in star activity with engineered high-fidelity variants EcoRI-HF and MfeI-HF, as well as quantify the influence on MfeI cleavage conferred by flanking nucleotides. The methods presented are readily applicable to all type II restriction endonucleases that cleave both strands of double-stranded DNA.