Barley yellow dwarf is an aphid-transmitted virus disease caused by yellow dwarf virus (YDV) species in the family Luteoviridae. Previous partial sequencing efforts conducted in Kansas revealed that Barley yellow dwarf virus-PAS (PAS) occurs in winter wheat fields, and currently available YDV multiplex reverse-transcription PCR (RT-PCR) assays do not detect this species. To enable precise determination of YDV species for research, disease diagnostic, and plant breeding programs, this study enhanced and validated the utility of a multiplex RT-PCR protocol to discriminate six YDV species, including PAS, in archived and fresh field samples. From a representative subset of samples collected from commercial and variety trial locations across nine wheat growing regions of Kansas, PAS and Barley yellow dwarf virus-PAV (PAV) were equally prevalent in single or mixed infections, and other YDVs occurred in mixed infections with PAS and/or PAV in low numbers. The optimized multiplex assay provided robust and specific detection of YDVs and showed promise as a diagnostic tool for determining species occurrence and composition of YDVs in an intensive wheat cropping region of the United States.

Understanding the mechanisms that drive acid-base regulation in organisms is important, especially for organisms in aquatic habitats that experience rapidly fluctuating pH conditions. Previous studies have shown that carbonic anhydrases (CAs), a family of zinc metalloenzymes, are responsible for acid-base regulation in many organisms. Through the use of phylogenetic tools, this present study attempts to elucidate the evolutionary history of the α-CA superfamily, with particular interest in the emerging model aquatic organism Daphnia pulex. We provide one of the most extensive phylogenies of the evolution of α-CAs, with the inclusion of 261 amino acid sequences across taxa ranging from Cnidarians to Homo sapiens. While the phylogeny supports most of our previous understanding on the relationship of how α-CAs have evolved, we find that, contrary to expectations, amino acid conservation with bacterial α-CAs supports the supposition that extracellular α-CAs are the ancestral state of animal α-CAs. Furthermore, we show that two cytosolic and one GPI-anchored α-CA in Daphnia genus have homologs in sister taxa that are possible candidate genes to study for acid-base regulation. In addition, we provide further support for previous findings of a high rate of gene duplication within Daphnia genus, as compared with other organisms.

A laboratory microcosm experiment was conducted to examine the roles of food quantity and food quality on the competitive abilities of clones of the keystone aquatic zooplankter, Daphnia pulicaria. Using methods of resurrection ecology, clones were established by hatching dormant eggs from sediment layers of a lake (South Center, MN, U.S.A) that were separated by centuries of environmental change (nutrient enrichment). Two sets of paired clones (“modern” vs. “ancient”) were competed against each other in a 2 × 2 factorial design of high/low food quantity and high/low food quality. Experimental carbon:phosphorus (C:P) ratios were designed to mimic food quantity and food quality parameters respective to each of the two time periods from which the clones were extracted to test whether clones are competitively superior under conditions representative of the time period in which they existed. Contrary to predictions, we found that “modern” clones were able to outcompete “ancient” clones under all food treatments. We discuss potential mechanisms (i.e., mutational input, viability of long-dormant eggs, differences in phenotypic plasticity) that may have differentially impacted the performance of experimental clones. Our results should aid in deciphering microevolutionary dynamics observed in resurrection ecology studies, a powerful tool that can illuminate adaptive dynamics of organisms to environmental changes on long-term (centuries-long) temporal scales.

How can schools improve the academic performance of stu dents ? That's the question a consortium of nine Nebraska school districts are answering. The authors, who describe the con sortium's activities, point out strong administrative leadership exists where quality is achieved.

The Speech Communication Association's Task Force on Assessment and Testing commissioned a national survey of state practices in speaking and listening skill assessment. Each state was queried about its plans concerning oral communication as a basic skill, statewide curriculum development, and statewide assessment practices in speaking and listening. This article presents a summary of the findings of that survey together with recommendations and conclusions.

A 3½ year study of the intellectual performance of preschool Appalachian children subjected to an enriched day care program revealed marked improvement in the children who received enrichment. Significant gains in IQ scores during the 3 year period of enriched day care programing were shown for the 4 and 5 year old learning disadvantaged children. A control group showed an average loss of 6.45 IQ points during the year prior to public school entry. No further dećrement or increment was noted during 2 years of public school education for these subjects. The overall results of the study support the use of preschool enrichment programing for disadvantaged children on a longitudinal basis.