MOLECULAR BIOLOGY AND PHYSIOLOGY Genotypic Variation in Physiological Strategies For Attaining Cotton Lint Yield Production

ABSTRACT The quality and quantity of cotton (Gossypium hirsutum L.) lint produced are complex traits controlled by multiple processes. The physiology behind yield and quality variations is not completely understood. Objectives for this research were to document the physiological strategies diverse cotton genotypes take to achieve their yield and fiber quality. The genotypes 'DPL 444BR', 'DPL 555BR', 'FM 800BR', 'MD 9', 'MD 15-OP', 'MD 29', 'MD 51 normal', 'MD 51 okra', 'PM 1218BR', and 'ST 4892BR' were grown in the field from 2005-2008. Dry matter partitioning, leaf photosynthesis, chlorophyll concentration, root hydraulic conductance, lint yield, yield components, and fiber quality data were collected. Lint yields ranged from 1675 to 1119 kg ha -1 among the genotypes. The size of the available carbon assimilate pool generated by a genotype appeared to be related to lint yield production. Genotypes used different strategies to generate this carbon assimilate pool, i.e. through improved photosynthetic rates and/ or solar radiation interception, and then convert that carbon into lint production. Fiber quality variations, however, could not easily be explained by just variations in the plants ability to produce carbon assimilates. Beyond just the quantity of carbon assimilates, it is the manner in which the plant assembles these carbon skeletons into the cellular matrix that determines the quality of the fiber produced. These research findings can be utilized to meet the challenge of future yield and fiber quality improvements

MOLECULAR BIOLOGY AND PHYSIOLOGY Genotypic Variation in Physiological Strategies For Attaining Cotton Lint Yield Production

ABSTRACT The quality and quantity of cotton (Gossypium hirsutum L.) lint produced are complex traits controlled by multiple processes. The physiology behind yield and quality variations is not completely understood. Objectives for this research were to document the physiological strategies diverse cotton genotypes take to achieve their yield and fiber quality. The genotypes 'DPL 444BR', 'DPL 555BR', 'FM 800BR', 'MD 9', 'MD 15-OP', 'MD 29', 'MD 51 normal', 'MD 51 okra', 'PM 1218BR', and 'ST 4892BR' were grown in the field from 2005-2008. Dry matter partitioning, leaf photosynthesis, chlorophyll concentration, root hydraulic conductance, lint yield, yield components, and fiber quality data were collected. Lint yields ranged from 1675 to 1119 kg ha -1 among the genotypes. The size of the available carbon assimilate pool generated by a genotype appeared to be related to lint yield production. Genotypes used different strategies to generate this carbon assimilate pool, i.e. through improved photosynthetic rates and/ or solar radiation interception, and then convert that carbon into lint production. Fiber quality variations, however, could not easily be explained by just variations in the plants ability to produce carbon assimilates. Beyond just the quantity of carbon assimilates, it is the manner in which the plant assembles these carbon skeletons into the cellular matrix that determines the quality of the fiber produced. These research findings can be utilized to meet the challenge of future yield and fiber quality improvements

An exceptionally well-preserved skeleton of Palaeothentes from the Early Miocene of Patagonia, Argentina: new insights into the anatomy of extinct paucituberculatan marsupials

International audienc

Diurnal Variation in Urodynamics of Rat

In humans, the storage and voiding functions of the urinary bladder have a characteristic diurnal variation, with increased voiding during the day and urine storage during the night. However, in animal models, the daily functional differences in urodynamics have not been well-studied. The goal of this study was to identify key urodynamic parameters that vary between day and night. Rats were chronically instrumented with an intravesical catheter, and bladder pressure, voided volumes, and micturition frequency were measured by continuous filling cystometry during the light (inactive) or dark (active) phases of the circadian cycle. Cage activity was recorded by video during the experiment. We hypothesized that nocturnal rats entrained to a standard 12:12 light:dark cycle would show greater ambulatory activity and more frequent, smaller volume micturitions in the dark compared to the light. Rats studied during the light phase had a bladder capacity of 1.44±0.21 mL and voided every 8.2±1.2 min. Ambulatory activity was lower in the light phase, and rats slept during the recording period, awakening only to urinate. In contrast, rats studied during the dark were more active, had a lower bladder capacities (0.65±0.18 mL), and urinated more often (every 3.7±0.9 min). Average bladder pressures were not significantly different between the light and dark (13.40±2.49 and 12.19±2.85 mmHg, respectively). These results identify a day-night difference in bladder capacity and micturition frequency in chronically-instrumented nocturnal rodents that is phase-locked to the normal circadian locomotor activity rhythm of the animal. Furthermore, since it has generally been assumed that the daily hormonal regulation of renal function is a major driver of the circadian rhythm in urination, and few studies have addressed the involvement of the lower urinary tract, these results establish the bladder itself as a target for circadian regulation

SEAS: A System for SEED-Based Pathway Enrichment Analysis

Pathway enrichment analysis represents a key technique for analyzing high-throughput omic data, and it can help to link individual genes or proteins found to be differentially expressed under specific conditions to well-understood biological pathways. We present here a computational tool, SEAS, for pathway enrichment analysis over a given set of genes in a specified organism against the pathways (or subsystems) in the SEED database, a popular pathway database for bacteria. SEAS maps a given set of genes of a bacterium to pathway genes covered by SEED through gene ID and/or orthology mapping, and then calculates the statistical significance of the enrichment of each relevant SEED pathway by the mapped genes. Our evaluation of SEAS indicates that the program provides highly reliable pathway mapping results and identifies more organism-specific pathways than similar existing programs. SEAS is publicly released under the GPL license agreement and freely available at http://csbl.bmb.uga.edu/~xizeng/research/seas/

Genome-wide analysis of ivermectin response by Onchocerca volvulus reveals that genetic drift and soft selective sweeps contribute to loss of drug sensitivity

Treatment of onchocerciasis using mass ivermectin administration has reduced morbidity and transmission throughout Africa and Central/South America. Mass drug administration is likely to exert selection pressure on parasites, and phenotypic and genetic changes in several Onchocerca volvulus populations from Cameroon and Ghana-exposed to more than a decade of regular ivermectin treatment-have raised concern that sub-optimal responses to ivermectin's anti-fecundity effect are becoming more frequent and may spread.Pooled next generation sequencing (Pool-seq) was used to characterise genetic diversity within and between 108 adult female worms differing in ivermectin treatment history and response. Genome-wide analyses revealed genetic variation that significantly differentiated good responder (GR) and sub-optimal responder (SOR) parasites. These variants were not randomly distributed but clustered in ~31 quantitative trait loci (QTLs), with little overlap in putative QTL position and gene content between the two countries. Published candidate ivermectin SOR genes were largely absent in these regions; QTLs differentiating GR and SOR worms were enriched for genes in molecular pathways associated with neurotransmission, development, and stress responses. Finally, single worm genotyping demonstrated that geographic isolation and genetic change over time (in the presence of drug exposure) had a significantly greater role in shaping genetic diversity than the evolution of SOR.This study is one of the first genome-wide association analyses in a parasitic nematode, and provides insight into the genomics of ivermectin response and population structure of O. volvulus. We argue that ivermectin response is a polygenically-determined quantitative trait (QT) whereby identical or related molecular pathways but not necessarily individual genes are likely to determine the extent of ivermectin response in different parasite populations. Furthermore, we propose that genetic drift rather than genetic selection of SOR is the underlying driver of population differentiation, which has significant implications for the emergence and potential spread of SOR within and between these parasite populations