Whole genome duplication of intra- and inter-chromosomes in the tomato genome

Whole genome duplication(WGD)events have been proven to occur in the evolutionary history of most angiosperms.Tomato is considered a model species of the Solanaceae family.In this study,we describe the details of the evolutionary process of the tomato genome by detecting collinearity blocks and dating the WGD events on the tree of life by combining two different methods:synonymous substitution rates(Ks)and phylogenetic trees.In total,593 collinearity blocks were discovered out of 12 pseudo-chromosomes constructed. It was evident that chromosome 2 had experienced an intra-chromosomal duplication event.Major inter-chromosomal duplication occurred among all the pseudo-chromosome.We calculated the Ks value of these collinearity blocks.Two peaks of Ks distribution were found,corresponding to two WGD events occurring approximately 36-82 million years ago(MYA)and 148-205 MYA.Additionally, the results of phylogenetic trees suggested that the more recent WGD event may have occurred after the divergence of the rosidasterid clade,but before the major diversification in Solanaceae.The older WGD event was shown to have occurred before the divergence of the rosid-asterid clade and after the divergence of rice-Arabidopsis(monocot-dicot).     

Drought-induced forest decline: causes, scope and implications

A large number of episodes of forest mortality associated with drought and heat stress have been detected worldwide in recent decades, suggesting that some of the world's forested ecosystems may be already responding to climate change. Here, we summarize a special session titled 'Drought-induced forest decline: causes, scope and implications' within the 12th European Ecological Federation Congress, held in ávila (Spain) from 25 to 29 September 2011. The session focused on the interacting causes and impacts of die-off episodes at the community and ecosystem levels, and highlighted recent events of drought- and heat-related tree decline, advances in understanding mechanisms and in predicting mortality events, and diverse consequences of forest decline. Talks and subsequent discussion noted a potentially important role of carbon that may be interrelated with plant hydraulics in the multi-faceted process leading to drought-induced mortality; a substantial and yet understudied capacity of many forests to cope with extreme climatic events; and the difficulty of separating climate effects from other anthropogenic changes currently shaping forest dynamics in many regions of the Earth. The need for standard protocols and multi-level monitoring programmes to track the spatio-temporal scope of forest decline globally was emphasized as critical for addressing this emerging environmental issue.     

How Drugs Interact with Transporters: SGLT1 as a Model

Drugs are transported by cotransporters with widely different turnover rates. We have examined the underlying mechanism using, as a model system, glucose and indican (indoxyl-beta-D: -glucopyranoside) transport by human Na(+)/glucose cotransporter (hSGLT1). Indican is transported by hSGLT1 at 10% of the rate for glucose but with a fivefold higher apparent affinity. We expressed wild-type hSGLT1 and mutant G507C in Xenopus oocytes and used electrical and optical methods to measure the kinetics of glucose (using nonmetabolized glucose analogue alpha-methyl-D: -glucopyranoside, alphaMDG) and indican transport, alone and together. Indican behaved as a competitive inhibitor of alphaMDG transport. To examine protein conformations, we recorded SGLT1 capacitive currents (charge movements) and fluorescence changes in response to step jumps in membrane voltage, in the presence and absence of indican and/or alphaMDG. In the absence of sugar, voltage jumps elicited capacitive SGLT currents that decayed to steady state with time constants (tau) of 3-20 ms. These transient currents were abolished in saturating alphaMDG but only slightly reduced (10%) in saturating indican. SGLT1 G507C rhodamine fluorescence intensity increased with depolarizing and decreased with hyperpolarizing voltages. Maximal fluorescence increased approximately 150% in saturating indican but decreased approximately 50% in saturating alphaMDG. Modeling indicated that the rate-limiting step for indican transport is sugar translocation, whereas for alphaMDG it is dissociation of Na(+) from the internal binding sites. The inhibitory effects of indican on alphaMDG transport are due to its higher affinity and a 100-fold lower translocation rate. Our results indicate that competition between substrates and drugs should be taken into consideration when targeting transporters as drug delivery systems.     

Intraspecific Concerted Evolution of the rDNA ITS1 in Anopheles farauti Sensu Stricto (Diptera: Culicidae) Reveals Recent Patterns of Population Structure

We examined the intraindividual variation present in the first ribosomal internal transcribed spacer (ITS1) of Anopheles farauti to determine the level of divergence among populations for this important malarial vector. We isolated 187 clones from 70 individuals and found regional variation among four internal tandem repeats. The data were partitioned prior to analysis given the presence of a paralogous ITS2 sequence, called the 5'-subrepeat, inserted in the ITS1 of most clones. A high level of homogenization and population differentiation was observed for this repeat, which indicates a higher rate of turnover relative to the adjacent 'core' region. Bayesian analysis was performed using several substitutional models on both a combined and a partitioned data set. On the whole, the ITS1 phylogeny and geographic origin of the samples appear to be congruent. Some interesting exceptions indicate the spread of variant repeats between populations and the retention of ancestral polymorphism. Our data clearly demonstrate concerted evolution at the intraspecific level despite intraindividual variation and a complex internal repeat structure from a species that occupies a continuous coastal distribution. A high rate of genomic turnover in combination with a high level of sequence divergence appears to be a major factor leading to its concerted evolution within these populations.     

Differential neurochemical consequences of an escalating dose-binge regimen followed by single-day multiple-dose methamphetamine challenges

Chronic intake of methamphetamine (METH) causes tolerance to its behavioral and subjective effects. To better mimic human patterns of drug abuse, the present study used a rodent model that took into account various facets of human drug administration and measured METH-induced effects on brain monoamine levels. Adult male Sprague–Dawley rats were injected with METH or saline according to an escalating dose schedule for 2 weeks. This was followed by a challenge regimen of either saline or one of two doses of METH (3 × 10 mg/kg every 2 h or 6 × 5 mg/kg given every hour, both given within a single day). Both challenge doses of METH caused significant degrees of depletion of dopamine in the striatum and norepinephrine and serotonin in the striatum, cortex, and hippocampus. Animals pre-treated with METH showed significant attenuation of METH-induced striatal dopamine depletion but not consistent attenuation of norepinephrine and serotonin depletion. Unexpectedly, METH pre-treated animals that received the 3 × 10 mg/kg challenge showed less increases in tympanic temperatures than saline pre-treated rats whereas METH pre-treated animals that received the 6 × 5 mg/kg METH challenge showed comparable increases in temperatures to saline pre-treated rats. Therefore, pre-treatment-induced partial protection against monoamine depletion is probably not because of attenuated METH-induced hyperthermia in those rats.     

Characterization of unisexual flower development in the endangered mahogany tree Swietenia macrophylla King. (Meliaceae)

The selection of candidate plus trees of desirable phenotypes from tropical forest trees and the rapid devastation of the natural environments in which these trees are found have created the need for a more detailed knowledge of the floral and reproductive biology of tropical tree species. In this article, the organogenic processes related to unisexual flower development in tropical mahogany, Swietenia macrophylla , are described. Mahogany inflorescences at different developmental stages were evaluated using scanning electron microscopy or optical microscopy of histological sections. The unisexual flowers of S. macrophylla are usually formed in a thyrse, in which the positions of the female and male flowers are not random. Differences between male and female flowers arise late during development. Both female and male flowers can only be structurally distinguished after stage 9, where ovule primordia development is arrested in male flowers and microspore development is aborted in female flower anthers. After this stage, male and female flowers can be distinguished by the naked eye as a result of differences in the dimensions of the gynoecium. The floral characteristics of S. macrophylla (distribution of male and female flowers within the inflorescence, and the relative number of male to female flowers) have practical implications for conservation strategies of this endangered species.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 529–535.     

Ultrasonic acoustic emissions in drought-stressed trees--more than signals from cavitation?

Ultrasonic acoustic emission (UAE) in trees is often related to collapsing water columns in the flow path as a result of tensions that are too strong (cavitation). However, in a decibel (dB) range below that associated with cavitation, a close relationship was found between UAE intensities and stem radius changes. UAE was continuously recorded on the stems of mature field-grown trees of Scots pine (Pinus sylvestris) and pubescent oak (Quercus pubescens) at a dry inner-Alpine site in Switzerland over two seasons. The averaged 20-Hz records were related to microclimatic conditions in air and soil, sap-flow rates and stem-radius fluctuations detrended for growth (Delta W). Within a low-dB range (27 +/- 1 dB), UAE regularly increased and decreased in a diurnal rhythm in parallel with DeltaW on cloudy days and at night. These low-dB emissions were interrupted by UAE abruptly switching between the low-dB range and a high-dB range (36 +/- 1 dB) on clear, sunny days, corresponding to the widely supported interpretation of UAE as sound from cavitations. It is hypothesized that the low-dB signals in drought-stressed trees are caused by respiration and/or cambial growth as these physiological activities are tissue water-content dependent and have been shown to produce courses of CO(2) efflux similar to our courses of Delta W and low-dB UAE.     

Fine root heterogeneity by branch order: exploring the discrepancy in root turnover estimates between minirhizotron and carbon isotopic methods

Fine roots constitute a large and dynamic component of the carbon cycles of terrestrial ecosystems. The reported fivefold discrepancy in turnover estimates between median longevity (ML) from minirhizotrons and mean residence time (MRT) using carbon isotopes may have global consequences. Here, a root branch order-based model and a simulated factorial experiment were used to examine four sources of error. Inherent differences between ML, a number-based measure, and MRT, a mass-based measure, and the inability of the MRT method to account for multiple replacements of rapidly cycling roots were the two sources of error that contributed more to the disparity than did the improper choice of root age distribution models and sampling bias. Sensitivity analysis showed that the rate at which root longevity increases as order increases was the most important factor influencing the disparity between ML and MRT. Assessing root populations for each branch order may substantially reduce the errors in longevity estimates of the fine root guild. Our results point to the need to acquire longevity estimates of different orders, particularly those of higher orders.     

Comparison of the cidal activity of tea tree oil and terpinen-4-ol against clinical bacterial skin isolates and human fibroblast cells

Aims: The aim of this study was to compare both the antimicrobial activity of terpinen‐4‐ol and tea tree oil (TTO) against clinical skin isolates of meticillin‐resistant Staphylococcus aureus (MRSA) and coagulase‐negative staphylococci (CoNS) and their toxicity against human fibroblast cells. Methods and Results: Antimicrobial activity was compared by using broth microdilution and quantitative in vitro time‐kill test methods. Terpinen‐4‐ol exhibited significantly greater bacteriostatic and bactericidal activity, as measured by minimum inhibitory and bactericidal concentrations, respectively, than TTO against both MRSA and CoNS isolates. Although not statistically significant, time‐kill studies also clearly showed that terpinen‐4‐ol exhibited greater antimicrobial activity than TTO. Comparison of the toxicity of terpinen‐4‐ol and TTO against human fibroblasts revealed that neither agent, at the concentrations tested, were toxic over the 24‐h test period. Conclusions: Terpinen‐4‐ol is a more potent antibacterial agent against MRSA and CoNS isolates than TTO with neither agent exhibiting toxicity to fibroblast cells at the concentrations tested. Significance and Impact of the Study: Terpinen‐4‐ol should be considered for inclusion as a single agent in products formulated for topical treatment of MRSA infection. However, further work would initially be required to ensure that resistance would not develop with the use of terpinen‐4‐ol as a single agent.