Transcriptome sequencing of Festulolium accessions under salt stress.

OBJECTIVES: The objective of this study was to establish transcriptome assemblies of Festulolium hybrids under salt stress, and identify genes regulated across the hybrids in response to salt stress. The development of transcriptome assemblies for Festulolium hybrids and cataloguing of genes regulated under salt stress will facilitate further downstream studies. RESULTS: Plants were grown at three salt concentrations (0.5%, 1% and 1.5%) and phenotypic and transcriptomic data was collected. Salt stress was confirmed by progressive loss of green leaves as salt concentration increased from 0 to 1.5%. We generated de-novo transcriptome assemblies for two Festulolium pabulare festucoid genotypes, for a single Festulolium braunii genotype, and a single F. pabulare loloid genotype. We also identified 1555 transcripts that were up regulated and 1264 transcripts that were down regulated in response to salt stress in the Festulolium hybrids. Some of the identified transcripts showed significant sequence similarity with genes known to be regulated during salt and other abiotic stresses.

Clade classification of monolignol biosynthesis gene family members reveals target genes to decrease lignin in Lolium perenne.

In monocots, lignin content has a strong impact on the digestibility of the cell wall fraction. Engineering lignin biosynthesis requires a profound knowledge of the role of paralogues in the multigene families that constitute the monolignol biosynthesis pathway. We applied a bioinformatics approach for genome-wide identification of candidate genes in Lolium perenne that are likely to be involved in the biosynthesis of monolignols. More specifically, we performed functional subtyping of phylogenetic clades in four multigene families: 4CL, COMT, CAD and CCR. Essential residues were considered for functional clade delineation within these families. This classification was complemented with previously published experimental evidence on gene expression, gene function and enzymatic activity in closely related crops and model species. This allowed us to assign functions to novel identified L. perenne genes, and to assess functional redundancy among paralogues. We found that two 4CL paralogues, two COMT paralogues, three CCR paralogues and one CAD gene are prime targets for genetic studies to engineer developmentally regulated lignin in this species. Based on the delineation of sequence conservation between paralogues and a first analysis of allelic diversity, we discuss possibilities to further study the roles of these paralogues in lignin biosynthesis, including expression analysis, reverse genetics and forward genetics, such as association mapping. We propose criteria to prioritise paralogues within multigene families and certain SNPs within these genes for developing genotyping assays or increasing power in association mapping studies. Although L. perenne was the target of the analyses presented here, this functional subtyping of phylogenetic clades represents a valuable tool for studies investigating monolignol biosynthesis genes in other monocot species.

Potential chlorpyrifos exposure to residents following standard crack and crevice treatment.

Multipathway exposures were evaluated for residents of houses over a 10-day period following a crack and crevice application of a chlorpyrifos-based formulation. Three multiroom houses with two adults each were treated. Air concentration, total deposition, and dislodgeable residues on horizontal surfaces were measured to assess potential respiratory, oral, and dermal exposures, respectively, in treated and untreated high activity rooms. In addition, urine samples collected from the adults were analyzed for the primary metabolite of chlorpyrifos, 3,5,6-trichloropyridinol, to determine absorbed dose. The maximum chlorpyrifos air concentration observed was 2.3 microgram/m3, with air concentrations generally decreasing to levels ranging from 0.1 to 0.3 microgram/m3 within 10 days. Carpet dislodgeable residues, used to evaluate the amount of residues potentially transferred upon contact, were less than the analytical method limit of quantitation (1.6 microgram/m2). Hard plastic balls placed in the homes on the day before application contained no detectable dislodgeable residues (<6.5 microgram/m2). Ten-day cumulative nontarget residues deposited on surfaces, as determined by deposition pads, were less than 2.3 microgram/100 cm2. Deposition samples from all living area floors collected 2 hr after application contained less than 9.9 microgram/100 cm2. Therefore, contact with household surfaces and subsequent hand-to-mouth activity are not expected to significantly contribute to overall exposure. Estimated exposures to children, based on the passive dosimetry measurements, ranged from 0.26 to 2.1% of the no observed effect level for plasma cholinesterase depression. In addition, potential exposures to the adult residents, as indicated by the urinary 3,5,6-TCP biomonitoring, did not increase as a result of the application.

Reduced locomotor activity as an acute effect of damage to superior colliculus in rats.

Rats with either electrolytic or radiofrequency lesions of the superior colliculus were tested in an open-field within 24 h of operation. They crossed significantly fewer squares and spent more time motionless then control animals, an effect that disappeared upon retesting 13 days later. Previously reported locomotor hyperactivity thus appears to be a chronic but not an acute effect of collicular damage in rats.