Seasonal changes in patterns of gene expression in avian song control brain regions

Photoperiod and hormonal cues drive dramatic seasonal changes in structure and function of the avian song control system. Little is known, however, about the patterns of gene expression associated with seasonal changes. Here we address this issue by altering the hormonal and photoperiodic conditions in seasonally-breeding Gambel's white-crowned sparrows and extracting RNA from the telencephalic song control nuclei HVC and RA across multiple time points that capture different stages of growth and regression. We chose HVC and RA because while both nuclei change in volume across seasons, the cellular mechanisms underlying these changes differ. We thus hypothesized that different genes would be expressed between HVC and RA. We tested this by using the extracted RNA to perform a cDNA microarray hybridization developed by the SoNG initiative. We then validated these results using qRT-PCR. We found that 363 genes varied by more than 1.5 fold (>log(2) 0.585) in expression in HVC and/or RA. Supporting our hypothesis, only 59 of these 363 genes were found to vary in both nuclei, while 132 gene expression changes were HVC specific and 172 were RA specific. We then assigned many of these genes to functional categories relevant to the different mechanisms underlying seasonal change in HVC and RA, including neurogenesis, apoptosis, cell growth, dendrite arborization and axonal growth, angiogenesis, endocrinology, growth factors, and electrophysiology. This revealed categorical differences in the kinds of genes regulated in HVC and RA. These results show that different molecular programs underlie seasonal changes in HVC and RA, and that gene expression is time specific across different reproductive conditions. Our results provide insights into the complex molecular pathways that underlie adult neural plasticity.     

Masting in whitebark pine (Pinus albicaulis) depletes stored nutrients

? In masting trees, synchronized, heavy reproductive events are thought to deplete stored resources and to impose a replenishment period before subsequent masting. However, direct evidence of resource depletion in wild, masting trees is very rare. Here, we examined the timing and magnitude (local vs individual-level) of stored nutrient depletion after a heavy mast event in Pinus albicaulis. ? In 2005, the mast year, we compared seasonal changes in leaf and sapwood nitrogen (N) and phosphorus (P) concentrations and leaf photosynthetic rates in cone-bearing branches, branches that never produced cones, and branches with experimentally removed cones. We also compared nutrient concentrations in cone branches and branches that had never had cones between 2005 and 2006, and measured tree ring width and new shoot growth during 2005. ? During the mast year, N or P depletion occurred only in tissue fractions of reproductive branches, where photosynthetic rates were reduced. However, by the end of the following year, nutrients were depleted in all branches, indicating individual-level resource depletion. New shoot and radial growth were not affected by masting. ? We provide direct evidence that mast events in wild trees deplete stored nutrients. Our results highlight the importance of evaluating reproductive costs over time and at the individual level.     

Genome-wide prediction models that incorporate de novo GWAS are a powerful new tool for tropical rice improvement

To address the multiple challenges to food security posed by global climate change, population growth and rising incomes, plant breeders are developing new crop varieties that can enhance both agricultural productivity and environmental sustainability. Current breeding practices, however, are unable to keep pace with demand. Genomic selection (GS) is a new technique that helps accelerate the rate of genetic gain in breeding by using whole-genome data to predict the breeding value of offspring. Here, we describe a new GS model that combines RR-BLUP with markers fit as fixed effects selected from the results of a genome-wide-association study (GWAS) on the RR-BLUP training data. We term this model GS + de novo GWAS. In a breeding population of tropical rice, GS + de novo GWAS outperformed six other models for a variety of traits and in multiple environments. On the basis of these results, we propose an extended, two-part breeding design that can be used to efficiently integrate novel variation into elite breeding populations, thus expanding genetic diversity and enhancing the potential for sustainable productivity gains.     

Copper ion-dependent oxy-radical mediated DNA damage from dihydroxy derivative of etoposide

The dihydroxy etoposide, a metabolite of the clinically active anticancer drug, VP-16, induced extensive DNA damage in the presence of copper ions. While superoxide dismutase was without any effect on the DNA damage, catalase and inhibitors of free hydroxyl radicals inhibited the DNA degradation, indicating that hydroxyl radicals were responsible for this drug-Cu-dependent DNA damage.     

Phylogeography and monophyly of the swordtail fish species Xiphophorus birchmanni (Cyprinodontiformes, Poeciliidae)

We used sequences of the mitochondria control region to assess the distribution of genetic variation within and among populations of the poeciliid fish species Xiphophorus birchmanni . We collected 122 X. birchmanni samples from 11 sites in three drainage systems comprising the distribution of the species. We found low levels of polymorphism among aligned sequences and low levels of genetic variation within populations but high levels of genetic differentiation among populations. Haplotypes are exclusive to three river drainages (Los Hules, Calabozo and San Pedro). Mantel tests revealed correlations between geographical (both straight-line and river distances) and genetic distance, consistent with an isolation by distance scenario, while nested clade analysis suggested allopatric fragmentation between haplotypes from two of the major drainages, and isolation by distance with restricted gene flow within those drainages. Finally, monophyly of X. birchmanni is strongly supported while the previous hypothesis of the evolutionary origin of this species from X. malinche is not.     

Functional mechanisms and histologic composition of the lingual appendage in the alligator snapping turtle,Macroclemys temmincki (Troost) (Testudines: Chelydridae)

Gross and microscopic examination of the lingual appendages of juvenile and adult alligator snapping turtles, Macroclemys temmincki, shows that it is divided into an anterior horn, a body, and a posterior horn. Lingual appendages of adults usually are more darkly pigmented than those of juveniles and melanocyte distribution is variable, resulting in a mottled appearance. The musculoskeletal components of the hyoid apparatus, presumably responsible for most of the motion displayed by the appendage, are described here. The lingual appendage is innervated by the lingual nerve which divides into three branches, two coursing rostrally into the anterior horn and one running caudally into the posterior horn. These branches ramify and end in numerous terminals within the lamina epithelialis and lamina propria. The lamina epithelialis of the distal three-fourths of the horns of the lingual appendage contain structures similar to taste buds described in other species of turtles. Goblet cells, containing acid mucopolysaccharides, are located in the stratified squamous epithelium. Blood is transported to the appendage via the lingual artery, which is a terminal branch of the external carotid artery. Numerous venous sinuses lie among the predominant bundles of connective tissue and account for approximately one-fifth of the total volume of the appendage. An engorged appendage is swollen and pinker in color. The coloration, enlargement, and wiggling movement combined with its buoyancy in water make the appendage imitate a small worm or an insect larva. The increase in melanin during ontogeny may produce a more variable pattern and may increase the number of organisms attracted by the appendage. The acid mucopolysaccharides of the globlet cells presumably may condition the nonkeratinized, stratified squamous epithelial surface of the appendage. The flexibility of the pseudoerect, active appendage keep it from being injured.     

Influence of Fullerene Acceptor on the Performance,Microstructure, and Photophysics of Low Bandgap Polymer Solar Cells

The morphology, photophysics, and device performance of solar cells based on the low bandgap polymer poly[[2,6′‐4,8‐di(5‐ethylhexylthienyl)benzo[1,2‐b;3,3‐b]dithiophene]3‐fluoro‐2[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl (PBDTTT‐EFT) (also known as PTB7‐Th) blended with different fullerene acceptors: Phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM), phenyl‐C₇₁ ‐butyric acid methyl ester (PC₇₁BM), or indene‐C₆₀ bisadduct (ICBA) are correlated. Compared to PC₇₁ BM‐based cells – which achieve a power conversion efficiency (PCE) of 9.4% – cells using ICBA achieve a higher open‐circuit voltage (V_OC) of 1.0 V albeit with a lower PCE of 7.1%. To understand the origin of this lower PCE, the morphology and photophysics have been thoroughly characterized. Hard and soft X‐ray scattering measurements reveal that the PBDTTT‐EFT:ICBA blend has a lower crystallinity, lower domain purity, and smaller domain size compared to the PBDTTT‐EFT:PC₇₁BM blend. Incomplete photoluminescence quenching is also found in the ICBA blend with transient absorption measurements showing faster recombination dynamics at short timescales. Transient photovoltage measurements highlight further differences in recombination at longer timeframes due to the more intermixed morphology of the ICBA blend. Interestingly, a mild thermal treatment improves the performance of PBDTTT‐EFT:ICBA cells which is exploited in the fabrication of a homo PBDTTT‐EFT:ICBA tandem solar cell with PCE of 9.0% and V_OC of 1.93 V.