GWAS combined with QTL mapping reveals the genetic loci of leaf morphological characters in Nicotiana tabacum.

BACKGROUND: Leaf morphology plays a crucial role in photosynthetic efficiency and yield potential in crops. Cigar tobacco plants, which are derived from common tobacco (Nicotiana tabacum L.), possess special leaf characteristics including thin and delicate leaves with few visible veins, making it a good system for studying the genetic basis of leaf morphological characters. RESULTS: In this study, GWAS and QTL mapping were simultaneously performed using a natural population containing 185 accessions collected worldwide and an F2 population consisting of 240 individuals, respectively. A total of 26 QTLs related to leaf morphological traits were mapped in the F2 population at three different developmental stages, and some QTL intervals were repeatedly detected for different traits and at different developmental stages. Among the 206 significant SNPs identified in the natural population using GWAS, several associated with the leaf thickness phenotype were co-mapped via QTL mapping. By analyzing linkage disequilibrium and transcriptome data from different tissues combined with gene functional annotations, 7 candidate genes from the co-mapped region were identified as the potential causative genes associated with leaf thickness. CONCLUSIONS: These results presented a valuable cigar tobacco resource showing the genetic diversity regarding its leaf morphological traits at different developmental stages. It also provides valuable information for novel genes and molecular markers that will be useful for further functional verification and for molecular breeding of leaf morphological traits in crops in the future.

Regulation of Leaf Angle Protects Photosystem I under Fluctuating Light in Tobacco Young Leaves.

Fluctuating light is a typical light condition in nature and can cause selective photodamage to photosystem I (PSI). The sensitivity of PSI to fluctuating light is influenced by the amplitude of low/high light intensity. Tobacco mature leaves are tended to be horizontal to maximize the light absorption and photosynthesis, but young leaves are usually vertical to diminish the light absorption. Therefore, we tested the hypothesis that such regulation of the leaf angle in young leaves might protect PSI against photoinhibition under fluctuating light. We found that, upon a sudden increase in illumination, PSI was over-reduced in extreme young leaves but was oxidized in mature leaves. After fluctuating light treatment, such PSI over-reduction aggravated PSI photoinhibition in young leaves. Furthermore, the leaf angle was tightly correlated to the extent of PSI photoinhibition induced by fluctuating light. Therefore, vertical young leaves are more susceptible to PSI photoinhibition than horizontal mature leaves when exposed to the same fluctuating light. In young leaves, the vertical leaf angle decreased the light absorption and thus lowered the amplitude of low/high light intensity. Therefore, the regulation of the leaf angle was found for the first time as an important strategy used by young leaves to protect PSI against photoinhibition under fluctuating light. To our knowledge, we show here new insight into the photoprotection for PSI under fluctuating light in nature.

Intoxicación severa por Nicotiana glauca (Palán Palán) con miocardio atontado / Severe poisoning by Nicotiana glauca (Palán Palán) with stunned myocardium

Resumen Nicotiana glauca también llamada Palán Palán, es un arbusto con hojas verdes azuladas y despulidas y una flor amarilla tubular pendulante que presenta alcaloides piridínicos, como nicotina, nornicotina, anatabina y anabastina (análogo estructural de la Nicotina). Se presenta el caso clínico de una paciente de 50 años con cuadro agudo de debilidad muscular generalizada que evoluciona con paro respiratorio, tras la ingesta accidental de una cantidad desconocida de hojas de Nicotiana glauca, cultivadas en una huerta hogareña mediante técnica de hidroponía y confundidas por su conviviente con espinaca. Presentó aumento de lactato y Troponina Ultra Sensible e Hipoquinesia Global de Ventrículo Izquierdo en el ecocardiograma, compatible con Aton tamiento Miocárdico (AM), que evolucionó favorablemente. Si bien hay pocos reportes, se han informado muertes de animales y humanos, tras la ingesta accidental de Nicotiana glauca. El inicio del cuadro es rápido, con patrón bifásico, con vómitos y estímulo simpático, seguido por bloqueo ganglionar y neuromuscular, pudiendo presentar paro respiratorio, shock, convulsiones y coma. El AM es una disfunción miocárdica prolongada con retorno gradual de la actividad contráctil, posterior a un episodio breve de isquemia grave, puede ser asintomático, pudiendo presentar alteraciones en el electrocardiograma, enzimas cardíacas o ecocardiograma. Generalmente presenta pronóstico favorable, pudiendo presentar insuficiencia cardíaca ante patologías concurrentes o aumento de requerimientos de oxígeno.

Abstract Nicotiana glauca is a shrub with bluish green leaves and a pendulous tubular yellow flower. It has pyridine alkaloids, such as nicotine, nornicotine, anatabine and anabastine (structural analog of Nicotine). We present the case of a 50 years old pa- tient with acute generalized muscle weakness that evolves to respiratory arrest, after accidentally ingesting an unknown quantity of Nicotiana glauca leaves, grown in a home vegetable garden, using a hydroponic technique and confused by her cohabiting with spinach. She presented increased lactate and Ultra Sensitive Troponin and Left Ventricular Global Hypokinesia in the echo- cardiogram, compatible with Myocardial Stunned, that it evolved favorably. There are few reports, animal and human deaths have been reported following accidental ingestion of Nicotiana glauca. The onset of the symptoms is early, with a biphasic pattern, with vomiting and sympathetic stimulation, followed by ganglionic and neuromuscular blockage and may present respiratory arrest, shock, seizures and coma. Myocardial Stunned is a prolonged myocardial dysfunction with gradual return of contractile activity after a brief episode of severe ischemia, it can be asymptomatic, and it can present alterations in the electrocardiogram, cardiac enzymes or echocardiogram. Generally presents a benign prognosis, being able to present heart failure with concurrent patholo- gies or increased requirements.

Novel perspectives on stomatal impressions: Rapid and non-invasive surface characterization of plant leaves by scanning electron microscopy.

Scanning electron microscopy (SEM) is widely used to investigate the surface morphology, and physiological state of plant leaves. Conventionally used methods for sample preparation are invasive, irreversible, require skill and expensive equipment, and are time and labor consuming. This study demonstrates a method to obtain in vivo surface information of plant leaves by imaging replicas with SEM that is rapid and non-invasive. Dental putty was applied to the leaves for 5 minutes and then removed. Replicas were then imaged with SEM and compared to fresh leaves, and leaves that were processed conventionally by chemical fixation, dehydration and critical point drying. The surface structure of leaves was well preserved on the replicas. The outline of epidermal as well as guard cells could be clearly distinguished enabling determination of stomatal density. Comparison of the dimensions of guard cells revealed that replicas did not differ from fresh leaves, while conventional sample preparation induced strong shrinkage (-40% in length and -38% in width) of the cells when compared to guard cells on fresh leaves. Tilting the replicas enabled clear measurement of stomatal aperture dimensions. Summing up, the major advantages of this method are that it is inexpensive, non-toxic, simple to apply, can be performed in the field, and that results on stomatal density and in vivo stomatal dimensions in 3D can be obtained in a few minutes.

The morphological and physiological basis of delayed pollination overcoming pre-fertilization cross-incompatibility in Nicotiana.

Delayed pollination is widely used to overcome pre-fertilization incompatibility, but its regulatory mechanisms are unclear. When Nicotiana tabacum was cross-pollinated with pollen of N. alata, the incompatibility occurring in the basal 1/4 region of the style (pollinated at anthesis: 0-day-old pistil) was overcome by delayed pollination (of 6-day-old pistil), and the morphological changes and corresponding physiological basis are explored here. The structure and ultrastructure of the pistil were observed under fluorescence microscopy and transmission electron microscopy. Differentially expressed proteins were screened with a monoclonal antibody chip for Nicotiana, and protein expression and distribution were analysed by immunofluorescence. Cellulase and pectinase activities were tested using enzyme-linked immunosorbent assay kits. The style of Nicotiana is solid in the basal region and pollen tubes grow in the extracellular spaces (ECM) of the transmitting tissue (TTS) cells. Seven of the 22 identified proteins were cell wall-associated proteins and were expressed at higher levels during pistil senescence. Cellulase and pectinase activities increased. The TTS cells in the basal 1/4 region of the 0-day-old style were polygonal and tightly arranged, with narrow ECM, but these were oval or partially dissolved in the 6-day-old pistil, leading to wider ECM and richer secretions. The increased expression of cell wall proteins and enhanced enzyme activity during pistil senescence might partially be responsible for the cells becoming oval and the ECM enlarged, providing the morphological basis for delayed pollination overcoming the pre-fertilization incompatibility between N. tabacum and N. alata.

Expression of a carotenogenic gene allows faster biomass production by redesigning plant architecture and improving photosynthetic efficiency in tobacco.

Because carotenoids act as accessory pigments in photosynthesis, play a key photoprotective role and are of major nutritional importance, carotenogenesis has been a target for crop improvement. Although carotenoids are important precursors of phytohormones, previous genetic manipulations reported little if any effects on biomass production and plant development, but resulted in specific modifications in carotenoid content. Unexpectedly, the expression of the carrot lycopene ß-cyclase (DcLCYB1) in Nicotiana tabacum cv. Xanthi not only resulted in increased carotenoid accumulation, but also in altered plant architecture characterized by longer internodes, faster plant growth, early flowering and increased biomass. Here, we have challenged these transformants with a range of growth conditions to determine the robustness of their phenotype and analyze the underlying mechanisms. Transgenic DcLCYB1 lines showed increased transcript levels of key genes involved in carotenoid, chlorophyll, gibberellin (GA) and abscisic acid (ABA) biosynthesis, but also in photosynthesis-related genes. Accordingly, their carotenoid, chlorophyll, ABA and GA contents were increased. Hormone application and inhibitor experiments confirmed the key role of altered GA/ABA contents in the growth phenotype. Because the longer internodes reduce shading of mature leaves, induction of leaf senescence was delayed, and mature leaves maintained a high photosynthetic capacity. This increased total plant assimilation, as reflected in higher plant yields under both fully controlled constant and fluctuating light, and in non-controlled conditions. Furthermore, our data are a warning that engineering of isoprenoid metabolism can cause complex changes in phytohormone homeostasis and therefore plant development, which have not been sufficiently considered in previous studies.

iTRAQ-based comparative proteomic analysis reveals high temperature accelerated leaf senescence of tobacco (Nicotiana tabacum L.) during flue-curing.

Tobacco (Nicotiana tabacum) is extensively cultivated all over the world for its economic value. During curing and storage, senescence occurs, which is associated with physiological and biochemical changes in postharvest plant organs. However, the molecular mechanisms involved in accelerated senescence due to high temperatures in tobacco leaves during curing need further elaboration. We studied molecular mechanisms of senescence in tobacco leaves exposed to high temperature during curing (Fresh, 38 °C and 42 °C), revealed by isobaric tags for relative and absolute quantification (iTRAQ) for the proteomic profiles of cultivar Bi'na1. In total, 8903 proteins were identified, and 2034 (1150 up-regulated and 1074 down-regulated) differentially abundant proteins (DAPs) were obtained from tobacco leaf samples. These DAPs were mainly involved in posttranslational modification, protein turnover, energy production and conversion. Sugar- and energy-related metabolic biological processes and pathways might be critical regulators of tobacco leaves exposed to high temperature during senescence. High-temperature stress accelerated tobacco leaf senescence mainly by down-regulating photosynthesis-related pathways and degrading cellular constituents to maintain cell viability and nutrient recycling. Our findings provide a valuable inventory of novel proteins involved in senescence physiology and elucidate the protein regulatory network in postharvest organs exposed to high temperatures during flue-curing.

Overexpressing Jatropha curcas CBF2 in Nicotiana benthamiana improved plant tolerance to drought stress.

Jatropha curcas is an important bioenergy oil plant, and often planted on barren land to save the area of arable land. It is significant to improve the adaptability of J. curcas to various abiotic stresses. In the present study, we transferred a J. curcas gene, encoding a CBF2 transcription factor, into Nicotiana benthamiana. Under drought treatment, the JcCBF2 transgenic lines showed improved survival rate, leaf water retention and active oxygen scavenging capacity, but reduced photosynthesis and transpiration rate, suggesting that JcCBF2 played an important role in improving plant drought tolerance. Overexpressing JcCBF2 decreased leaf area and increased leaf thickness. To explore the possible mechanisms for the change of leaf anatomical structure, the leaves of wild-type and overexpression lines under drought stress were RNA sequenced. Genes involved in the plant hormones signal transduction were found to be enriched. Cytokinin and indole-3-acetic acid were the major plant hormones whose abundance increased. Quantitative RT-PCR analysis showed expression of NbMYB21, NbMYB86 and NbMYB44 and both abscisic acid (ABA) and jasmonic acid (JA) related genes in the overexpression lines were increased under drought stress. These results indicated that JcCBF2 was able to positively regulate plant drought response by changing the leaf anatomical structure and possibly through JA and ABA signalling pathways. Our work may help us to understand the drought tolerant mechanism.

Machine Learning Approaches to Improve Three Basic Plant Phenotyping Tasks Using Three-Dimensional Point Clouds.

Developing automated methods to efficiently process large volumes of point cloud data remains a challenge for three-dimensional (3D) plant phenotyping applications. Here, we describe the development of machine learning methods to tackle three primary challenges in plant phenotyping: lamina/stem classification, lamina counting, and stem skeletonization. For classification, we assessed and validated the accuracy of our methods on a dataset of 54 3D shoot architectures, representing multiple growth conditions and developmental time points for two Solanaceous species, tomato (Solanum lycopersicum cv 75 m82D) and Nicotiana benthamiana Using deep learning, we classified lamina versus stems with 97.8% accuracy. Critically, we also demonstrated the robustness of our method to growth conditions and species that have not been trained on, which is important in practical applications but is often untested. For lamina counting, we developed an enhanced region-growing algorithm to reduce oversegmentation; this method achieved 86.6% accuracy, outperforming prior methods developed for this problem. Finally, for stem skeletonization, we developed an enhanced tip detection technique, which ran an order of magnitude faster and generated more precise skeleton architectures than prior methods. Overall, our improvements enable higher throughput and accurate extraction of phenotypic properties from 3D point cloud data.

Nicotiana suaveolens accessions with different ploidy levels exhibit different reproductive isolation mechanisms in interspecific crosses with Nicotiana tabacum.

Reproductive isolation, including prezygotic and postzygotic barriers, is a mechanism that separates species. Many species in the Nicotiana section Suaveolentes exhibit reproductive isolation in crosses with Nicotiana tabacum. In this study, we investigated whether the chromosome numbers and ploidy levels of eight Nicotiana suaveolens accessions are related to the reproductive isolation after crosses with N. tabacum by flow cytometry and chromosome analyses. Additionally, the internal transcribed spacer (ITS) regions of the eight N. suaveolens accessions were sequenced and compared with the previously reported sequences of 22 Suaveolentes species to elucidate the phylogenetic relationships in the section Suaveolentes. We revealed that four N. suaveolens accessions comprised 64 chromosomes, while the other four accessions carried 32 chromosomes. Depending on the ploidy levels of N. suaveolens, several types of reproductive isolation were observed after crosses with N. tabacum, including decreases in the number of capsules and the germination rates of hybrid seeds, as well as hybrid lethality and abscission of enlarged ovaries at 12-17 days after pollination. A phylogenetic analysis involving ITS sequences divided the eight N. suaveolens accessions into three distinct clades. Based on the results, we confirmed that N. suaveolens accessions vary regarding ploidy levels and reproductive isolation mechanisms in crosses with N. tabacum. These accessions will be very useful for revealing and characterizing the reproductive isolation mechanisms in interspecific crosses and their relationships with ploidy levels.

Differential gene expression between the vigorous and dwarf litchi cultivars based on RNA-Seq transcriptome analysis.

Litchi (Litchi chinesis Sonn.) is the most economically significant member of Sapindaceae family, especially in sub-tropical regions. However, its tall tree body often brings many inconveniences to production management. In order to modify the tree size or growth for productivity optimization and simplifying management, it is urgent to reveal the dwarf mechanism of litchi for dwarfing rootstocks or cultivar breeding. However, to date, the mechanisms on litchi dwarfism is still poor known. In the present study, transcriptome profiling were performed on L. chinensis cv. 'Feizixiao' (FZX, vigorous cultivar) and 'Ziniangxi' (ZNX, dwarf cultivar). A total of 55,810 unigenes were obtained, and 9,190 unigenes were differentially expressed between vigorous and dwarf litchi samples. Gene functional enrichment analysis indicated that the differentially expressed unigenes (DEGs) were related to phytohormone metabolism and signal transduction, and energy metabolism pathways. In particular, GA2ox were only up-regulated in ZNX samples, indicating GA might play an important role in regulating huge difference between vigorous and dwarf litchi cultivars. In addition, the 35S::LcGA2ox transgenic tobacco plants were dwarf and had smaller leaves or branches than wild type plants. Our study provided a series of candidate genes to reveal the mechanism of litchi dwarf.

Is Polonium-210 a Good Indicator for Anthropogenic Radioactivity?

Anthropogenic radioactivity generated by nuclear or chemical events results in the liberation of quadrillions of Becquerel and tons of materials to the environment. These events include nuclear accidents, nuclear weapon experiments, and high levels of generated radioactive and chemical waste. 210Po is a high-energy α emitter that presents in the environment at extremely low concentration. It is considered as one of the highly toxic elements and is estimated to contribute about 7% of the total effective dose equivalent to humans from ingested natural internal radiation. The assessment of 210Po activity/concentration in the environment could be used as an indicator of the level of anthropogenic radioactivity. The 210Po concentration present in the most frequently sold cigarette produced in Lebanon was assayed using α spectrometry after a radiochemical separation and spontaneous deposition of Po on a copper disk. Although the geographical nature of Lebanese land is an extension of Syrian territory, the polonium activity concentration obtained is 8.8 times higher and attributable to the excessive use of phosphate fertilizers in agriculture. The individual committed effective dose was estimated to be equal to 219 ± 17 µSv/year of cigarette smoking.

Functional conservation of Arabidopsis LNG1 in tobacco relating to leaf shape change by increasing longitudinal cell elongation by overexpression.

The LONGIFOLIA1 (LNG1) gene of Arabidopsis regulates leaf shape by polar cell elongation independent of ROTUNDAFOLIA3 (ROT3). To expand our knowledge on the function of this gens in plant systems, Arabidopsis LNG1 (AtLNG1) was introduced both sense and antisense orientation under the control of 35S CaMV promoter into tobacco plants that lack AtLNG1 homolog. Resulting transgenic tobacco plants were analyzed by their phenotype, anatomy and transcript levels. AtLNG1-overexpressing tobacco lines showed increase in the leaf petiole and leaf blade compared with wild type tobacco line. The overexpressors also showed elongated palisade cells as well as epidermal cells in the leaf length direction, but no increase in cell number. Ectopic expression of AtLNG1 in tobacco plants also increased the expression of cell wall modification-related genes, such as NT_XYLOGLUCAN ENDOTRANSGLUCOSYLASE/HYDROLASE9 (NT_XTH9), NT_XTH15 and NT_XTH33, indicating that these genes appear to be target of AtLNG1. As results of molecular and cellular examination, AtLNG1 seemed to have a conserved functional role in shaping leaf morphology in both Arabidopsis and tobacco.

Downregulation of the CpSRP43 gene expression confers a truncated light-harvesting antenna (TLA) and enhances biomass and leaf-to-stem ratio in Nicotiana tabacum canopies.

MAIN CONCLUSION: Downregulation in the expression of the signal recognition particle 43 (SRP43) gene in tobacco conferred a truncated photosynthetic light-harvesting antenna (TLA property), and resulted in plants with a greater leaf-to-stem ratio, improved photosynthetic productivity and canopy biomass accumulation under high-density cultivation conditions. Evolution of sizable arrays of light-harvesting antennae in all photosynthetic systems confers a survival advantage for the organism in the wild, where sunlight is often the growth-limiting factor. In crop monocultures, however, this property is strongly counterproductive, when growth takes place under direct and excess sunlight. The large arrays of light-harvesting antennae in crop plants cause the surface of the canopies to over-absorb solar irradiance, far in excess of what is needed to saturate photosynthesis and forcing them to engage in wasteful dissipation of the excess energy. Evidence in this work showed that downregulation by RNA-interference approaches of the Nicotiana tabacum signal recognition particle 43 (SRP43), a nuclear gene encoding a chloroplast-localized component of the photosynthetic light-harvesting assembly pathway, caused a decrease in the light-harvesting antenna size of the photosystems, a corresponding increase in the photosynthetic productivity of chlorophyll in the leaves, and improved tobacco plant canopy biomass accumulation under high-density cultivation conditions. Importantly, the resulting TLA transgenic plants had a substantially greater leaf-to-stem biomass ratio, compared to those of the wild type, grown under identical agronomic conditions. The results are discussed in terms of the potential benefit that could accrue to agriculture upon application of the TLA-technology to crop plants, entailing higher density planting with plants having a greater biomass and leaf-to-stem ratio, translating into greater crop yields per plant with canopies in a novel agronomic configuration.

Organization of the TC and TE cellular T-DNA regions in Nicotiana otophora and functional analysis of three diverged TE-6b genes.

Nicotiana otophora contains Agrobacterium-derived T-DNA sequences introduced by horizontal gene transfer (Chen et al., 2014). Sixty-nine contigs were assembled into four different cellular T-DNAs (cT-DNAs) totalling 83 kb. TC and TE result from two successive transformation events, each followed by duplication, yielding two TC and two TE inserts. TC is also found in other Nicotiana species, whereas TE is unique to N. otophora. Both cT-DNA regions are partially duplicated inverted repeats. Analysis of the cT-DNA divergence patterns allowed reconstruction of the evolution of the TC and TE regions. TC and TE carry 10 intact open reading frames. Three of these are TE-6b genes, derived from a single 6b gene carried by the Agrobacterium strain which inserted TE in the N. otophora ancestor. 6b genes have so far only been found in Agrobacterium tumefaciens or Agrobacterium vitis T-DNAs and strongly modify plant growth (Chen and Otten, 2016). The TE-6b genes were expressed in Nicotiana tabacum under the constitutive 2 × 35S promoter. TE-1-6b-R and TE-2-6b led to shorter plants, dark-green leaves, a strong increase in leaf vein development and modified petiole wings. TE-1-6b-L expression led to a similar phenotype, but in addition leaves show outgrowths at the margins, flowers were modified and plants became viviparous, i.e. embryos germinated in the capsules at an early stage of their development. Embryos could be rescued by culture in vitro. The TE-6b phenotypes are very different from the earlier described 6b phenotypes and could provide new insight into the mode of action of the 6b genes.

FlowerMorphology: fully automatic flower morphometry software.

MAIN CONCLUSION: The software FlowerMorphology is designed for automatic morphometry of actinomorphic flowers. The novel complex parameters of flowers calculated by FlowerMorphology allowed us to quantitatively characterize a polyploid series of tobacco. Morphological differences of plants representing closely related lineages or mutants are mostly quantitative. Very often, there are only very fine variations in plant morphology. Therefore, accurate and high-throughput methods are needed for their quantification. In addition, new characteristics are necessary for reliable detection of subtle changes in morphology. FlowerMorphology is an all-in-one software package to automatically image and analyze five-petal actinomorphic flowers of the dicotyledonous plants. Sixteen directly measured parameters and ten calculated complex parameters of a flower allow us to characterize variations with high accuracy. The program was developed for the needs of automatic characterization of Nicotiana tabacum flowers, but is applicable to many other plants with five-petal actinomorphic flowers and can be adopted for flowers of other merosity. A genetically similar polyploid series of N. tabacum plants was used to investigate differences in flower morphology. For the first time, we could quantify the dependence between ploidy and size and form of the tobacco flowers. We found that the radius of inner petal incisions shows a persistent positive correlation with the chromosome number. In contrast, a commonly used parameter-radius of outer corolla-does not discriminate 2n and 4n plants. Other parameters show that polyploidy leads to significant aberrations in flower symmetry and are also positively correlated with chromosome number. Executables of FlowerMorphology, source code, documentation, and examples are available at the program website: https://github.com/Deyneko/FlowerMorphology .

Quantitative analysis of menthol and identification of other flavoring ingredients in capsule cigarettes marketed in Korea.

Currently, capsule cigarettes have been introduced by tobacco industries and their sales have increased exponentially. However, the capsule flavoring ingredients and their safety are still unknown. Although the contents of menthol and other ingredients directly added to cigarettes have been determined extensively, no analogous study exists for menthol-containing cigarette capsules. Basic physical properties of capsules in all 31 different capsule cigarettes commercially available in Korea were investigated, and their menthol contents were determined in this study. Other ingredients in these capsules were also qualitatively analyzed; methyl octanoate, menthone and isopulegol as well as menthol were detected in all the capsules. There is considerable variability in basic physical properties and menthol contents of cigarette capsules depending on their brand styles. The menthol contents of capsules and whole cigarettes are similar or higher than those previously reported for conventional menthol cigarettes. This is the first report on the physical properties of capsules and the fact that a wide range of menthol contents in capsule cigarettes, regardless of flavor types, allows smokers to select menthol content to their liking.

High-Resolution Laser Scanning Reveals Plant Architectures that Reflect Universal Network Design Principles.

Transport networks serve critical functions in biological and engineered systems, and yet their design requires trade-offs between competing objectives. Due to their sessile lifestyle, plants need to optimize their architecture to efficiently acquire and distribute resources while also minimizing costs in building infrastructure. To understand how plants resolve this design trade-off, we used high-precision three-dimensional laser scanning to map the architectures of tomato, tobacco, or sorghum plants grown in several environmental conditions and through multiple developmental time points, scanning in total 505 architectures from 37 plants. Using a graph-theoretic algorithm that we developed to evaluate design strategies, we find that plant architectures lie along the Pareto front between two simple length-based objectives-minimizing total branch length and minimizing nutrient transport distance-thereby conferring a selective fitness advantage for plant transport processes. The location along the Pareto front can distinguish among species and conditions, suggesting that during evolution, natural selection may employ common network design principles despite different optimization trade-offs.

Elements including metals in the atomizer and aerosol of disposable electronic cigarettes and electronic hookahs.

OBJECTIVE: Our purpose was to quantify 36 inorganic chemical elements in aerosols from disposable electronic cigarettes (ECs) and electronic hookahs (EHs), examine the effect of puffing topography on elements in aerosols, and identify the source of the elements. METHODS: Thirty-six inorganic chemical elements and their concentrations in EC/EH aerosols were determined using inductively coupled plasma optical emission spectroscopy, and their source was identified by analyzing disassembled atomizers using scanning electron microscopy and energy dispersive X-ray spectroscopy. RESULTS: Of 36 elements screened, 35 were detected in EC/EH aerosols, while only 15 were detected in conventional tobacco smoke. Some elements/metals were present in significantly higher concentrations in EC/EH aerosol than in cigarette smoke. Concentrations of particular elements/metals within EC/EH brands were sometimes variable. Aerosols generated at low and high air-flow rates produced the same pattern of elements, although the total element concentration decreased at the higher air flow rate. The relative amount of elements in the first and last 60 puffs was generally different. Silicon was the dominant element in aerosols from all EC/EH brands and in cigarette smoke. The elements appeared to come from the filament (nickel, chromium), thick wire (copper coated with silver), brass clamp (copper, zinc), solder joints (tin, lead), and wick and sheath (silicon, oxygen, calcium, magnesium, aluminum). Lead was identified in the solder and aerosol of two brands of EHs (up to 0.165 µg/10 puffs). CONCLUSION: These data show that EC/EH aerosols contain a mixture of elements, including heavy metals, with concentrations often significantly higher than in conventional cigarette smoke. While the health effects of inhaling mixtures of heated metals is currently not known, these data will be valuable in future risk assessments involving EC/EH elements/metals.

Morphogenesis and developmental ultrastructure of Nicotiana tabacum short glandular trichomes.

The anatomy and ultrastructure of the short glandular trichomes occurring on young expanding leaves of Nicotiana tabacum were investigated using light and transmission electron microscopy. The objective of the present research was to characterize the cellular changes that occur during morphogenesis of short glandular trichomes, from initiation to senescence. Ultrastructural analysis of their secretory cells revealed characteristics common to gland cells: numerous mitochondria in highly organized cytoplasm, large nuclei, and an elaborate network of endoplasmic reticulum. Initial changes in nuclear and plastidial organization were observed at a more advanced secretory stage, marking the onset of senescence. During trichome senescence, gradual reduction of the cytoplasm density occurred along with structural changes of the plastids and the tonoplast. As a result of inward blebbing of the cytoplasm into the vacuole, membrane bound vesicular structures appeared in the vacuolar space. At the late secretory stage, marked by an increase in vacuolation and extraplasmic space, degenerative changes included further fragmentation of the cytoplasm and deterioration of the tonoplast. Multimembrane myelin bodies observed in the vacuolar space were indicative of membrane digestion although plasma membrane did not appear massively degraded.