Odontoblast processes in human dentin revealed by fluorescence labeling and transmission electron microscopy

In the present undertaking, the distribution of odontoblast processes in human dentin was determined through the DiI carbocyanine dye fluorescent staining of the cell membrane, while F-actin was identified by rhodamine-phalloidin. Confocal laser scanning microscopy revealed intense labeling for both agents in inner dentin, while transmission electron microscopy (TEM) identified dentinal tubules including odontoblast processes in this area, each process being surrounded by a cell membrane and containing an abundance of filamentous structures. Electron-dense "lamina limitans" lined the dentinal tubules. Individual cell processes became narrower toward the middle area, and their overall numbers decreased as well under TEM. Labeling for F-actin was absent in both middle and outer dentin, while faint labeling for DiI was visible along the dentinal tubules as far as the dentino-enamel junction (DEJ), where it was also recognized within the tubules themselves. Under TEM, the dentinal tubules lined with electron-dense structures were, in fact, empty in the middle and outer dentin. Immediately below the DEJ, however, the tubules manifested dense concentrations of fine granular material. Our study, therefore, appears to suggest that odontoblast processes do not extend beyond the inner dentin of fully erupted human premolars.     

Influence of different etching times on dentin surface morphology

The aim of this study is to investigate the influence of different etching times on demineralized dentin surface morphology using scanning electron microscopy and qualitative line microanalysis of chemical structure. Two sample groups, consisting of 30 first premolar teeth in each group, were established. Teeth were cut at the half-distance between the enamel-dentin junction and the pulp. The first group of specimens was etched for 10 seconds and the second group for 30 seconds. 37% ortophosphoric acid was used. SEM (scanning electron microscopy) was utilized to observe the following parameters: number and diameter of dentinal tubules, dentinal and intertubular dentinal surface percentage, appearance of the dentin surface porous zone containing smear layer and demineralized residual collagen particles with dentin demineralization products in acid globules, and dissolved peritubular dentin cuff. After calculating measurements of central tendency (X,C, Mo, SD), Kolmogorov-Smirnov and Student t-test were performed to confirm the quantitative results, and the chi2-test was run to produce qualitative data. In contrast to the 10-second etching time, the increased etching time of 30 seconds resulted in the following findings: (1) an increased number of dentinal tubules (p < 0.05), (2) an increase in dentinal tubule diameter (p < 0.05), (3) an increase in dentinal tubule surface percentage (p < 0.001), (4) a decrease in intertubular dentinal surface percentage (p < 0.001), (5) appearance of dentin surface porous zone containing smear layer and demineralized residual collagen particles with dentin demineralization products in acid globules (p < 0.001), and (6) completely dissolved peritubular dentin cuff (p <0.001). Therefore, different etching times using the same phosphoric acid concentration result in different morphological changes in demineralized dentin surface. Moreover, based on a comparison with current studies, prolonged etching time causes morphological changes to dentin surface. Such changes, have, in turn, negative effects on the dentin hybridization process.     

N‐glycosylation microheterogeneity and site occupancy of an Asn‐X‐Cys sequon in plasma‐derived and recombinant protein C

Human protein C (hPC) is glycosylated at three Asn‐X‐Ser/Thr and one atypical Asn‐X‐Cys sequons. We have characterized the micro‐ and macro‐heterogeneity of plasma‐derived hPC and compared the glycosylation features with recombinant protein C (tg‐PC) produced in a transgenic pig bioreactor from two animals having approximately tenfold different expression levels. The N‐glycans of hPC are complex di‐ and tri‐sialylated structures, and we measured 78% site occupancy at Asn‐329 (the Asn‐X‐Cys sequon). The N‐glycans of tg‐PC are complex sialylated structures, but less branched and partially sialylated. The porcine mammary epithelial cells glycosylate the Asn‐X‐Cys sequon with a similar efficiency as human hepatocytes even at these high expression levels, and site occupancy at this sequon was not affected by expression level. A distinct bias for particular structures was present at each of the four glycosylation sites for both hPC and tg‐PC. Interestingly, glycans with GalNAc in the antennae were predominant at the Asn‐329 site. The N‐glycan structures found for tg‐PC are very similar to those reported for a recombinant Factor IX produced in transgenic pig milk, and similar to the endogenous milk protein lactoferrin, which may indicate that N‐glycan processing in the porcine mammary epithelial cells is more uniform than in other tissues.     

Use of Poly (Amidoamine) Dendrimer for Dentinal Tubule Occlusion: A Preliminary Study

The occlusion of dentinal tubules is an effective method to alleviate the symptoms caused by dentin hypersensitivity, a significant health problem in dentistry and daily life. The in situ mineralization within dentinal tubules is a promising treatment for dentin hypersensitivity as it induces the formation of mineral on the sensitive regions and occludes the dentinal tubules. This study was carried out to evaluate the in vitro effect of a whole generation poly(amidoamine) (PAMAM) dendrimer (G3.0) on dentinal tubule occlusion by inducing mineralization within dentinal tubules. Dentin discs were treated with PAMAM dendrimers using two methods, followed by the in vitro characterization using Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM) and Energy-Dispersive X-ray Spectroscopy (EDS). These results showed that G3.0 PAMAM dendrimers coated on dentin surface and infiltrated in dentinal tubules could induce hydroxyapatite formation and resulted in effective dentinal tubule occlusion. Moreover, crosslinked PAMAM dendrimers could induce the remineralization of demineralized dentin and thus had the potential in dentinal tubule occlusion. In this in vitro study, dentinal tubules occlusion could be achieved by using PAMAM dendrimers. This could lead to the development of a new therapeutic technique for the treatment of dentin hypersensitivity.     

Reprecipitation Phenomena Arising During the Preparation of Demineralised Sections. III. Scanning Electron Microscopic Examination of Secondary Calcium Phosphate Deposits

Sections of teeth partly demineralised in 10% formic acid were examined by X-ray diffraction, microradiography and scanning electron microscopy. In the undemineralised circumpulpal dentin, the tubules were empty, lying in a matrix containing hydroxyapatite. In the 'plume' areas of remineralisation, the tubules were filled with mineral deposits. X-ray diffraction revealed the presence of brushite and monetite in these areas. In the outer layers of dentin the tubules were empty, lying in a matrix containing some residual hydroxyapatite. These findings confirmed that the remineralisation process occurred within the dentinal tubules.     

The presence of open dentinal tubules affects the biological properties of dental pulp cells <Emphasis Type="Italic">Ex Vivo</Emphasis>

To investigate the effects of open dentinal tubules on the morphological and functional characteristics of dental pulp cells. Morphological changes in human dental pulp cells that were seeded onto dentin discs with open dentinal tubules were investigated on days 1, 2, 4, and 10 of culture using scanning electron microscopy and fluorescence microscopy. Samples collected on days 1, 3, 6, 8, and 10 of culture were evaluated for cell proliferation rate and alkaline phosphatase activity. Cultured human dental pulp cells developed a columnar or polygonal morphology and monopolar cytoplasmic processes that extended into the dentinal tubules. The cells formed a multilayer and secreted an extracellular matrix onto the cell surface. Scanning electron microscopy and fluorescence microscopy revealed polarized organization of odontoblasts. Cells seeded onto dentin discs proliferated minimally but showed high levels of ALP activity. Dental pulp cells seeded onto treated dentin discs develop an odontoblastlike phenotype, which may be a potential alternative for use in experimental research on dentinogenesis.     

α‐chymotrypsin in water–acetone and water–dimethyl sulfoxide mixtures: Effect of preferential solvation and hydration

We investigated water/organic solvent sorption and residual enzyme activity to simultaneously monitor preferential solvation/hydration of protein macromolecules in the entire range of water content at 25°C. We applied this approach to estimate protein destabilization/stabilization due to the preferential interactions of bovine pancreatic α‐chymotrypsin with water‐acetone (moderate‐strength H‐bond acceptor) and water‐DMSO (strong H‐bond acceptor) mixtures. There are three concentration regimes for the dried α‐chymotrypsin. α‐Chymotrypsin is preferentially hydrated at high water content. The residual enzyme activity values are close to 100%. At intermediate water content, the dehydrated α‐chymotrypsin has a higher affinity for acetone/DMSO than for water. Residual enzyme activity is minimal in this concentration range. The acetone/DMSO molecules are preferentially excluded from the protein surface at the lowest water content, resulting in preferential hydration. The residual catalytic activity in the water‐poor acetone is ～80%, compared with that observed after incubation in pure water. This effect is very small for the water‐poor DMSO. Two different schemes are operative for the hydrated enzyme. At high and intermediate water content, α‐chymotrypsin exhibits preferential hydration. However, at intermediate water content, in contrast to the dried enzyme, the initially hydrated α‐chymotrypsin possesses increased preferential hydration parameters. At low water content, no residual enzyme activity was observed. Preferential binding of DMSO/acetone to α‐chymotrypsin was detected. Our data clearly demonstrate that the hydrogen bond accepting ability of organic solvents and the protein hydration level constitute key factors in determining the stability of protein–water–organic solvent systems.     

Noise‐induced cochlear F‐actin depolymerization is mediated via ROCK2/p‐ERM signaling

Our previous work has suggested that traumatic noise activates Rho‐GTPase pathways in cochlear outer hair cells (OHCs), resulting in cell death and noise‐induced hearing loss (NIHL). In this study, we investigated Rho effectors, Rho‐associated kinases (ROCKs), and the targets of ROCKs, the ezrin‐radixin‐moesin (ERM) proteins, in the regulation of the cochlear actin cytoskeleton using adult CBA/J mice under conditions of noise‐induced temporary threshold shift (TTS) and permanent threshold shift (PTS) hearing loss, which result in changes to the F/G‐actin ratio. The levels of cochlear ROCK2 and p‐ERM decreased 1 h after either TTS‐ or PTS‐noise exposure. In contrast, ROCK2 and p‐ERM in OHCs decreased only after PTS‐, not after TTS‐noise exposure. Treatment with lysophosphatidic acid, an activator of the Rho pathway, resulted in significant reversal of the F/G‐actin ratio changes caused by noise exposure and attenuated OHC death and NIHL. Conversely, the down‐regulation of ROCK2 by pretreatment with ROCK2 siRNA reduced the expression of ROCK2 and p‐ERM in OHCs, exacerbated TTS to PTS, and worsened OHC loss. Additionally, pretreatment with siRNA against radixin, an ERM protein, aggravated TTS to PTS. Our results indicate that a ROCK2‐mediated ERM‐phosphorylation signaling cascade modulates noise‐induced hair cell loss and NIHL by targeting the cytoskeleton.

     

Chitosan and hydroxyapatite composite cross‐linked by dopamine has improved anisotropic hydroxyapatite growth and wet mechanical properties

Three of the major impediments to using hydroxyapatite (HAp)‐collagen composites for hard tissue repair are the difficulties in anisotropic growth of HAp, in functional collagen production, and in their cross‐linking. To solve these problems, we fabricated HAp‐based composites for hard tissue repair by using chitosan as a collagen matrix substitute, and dopamine as a replacement for aldehyde‐based cross‐linkers. In the presence of chitosan and dopamine, the HAp particles grew anisotropically in a needle shape with an aspect ratio of ～4.4. The needle‐shaped HAp particles were dispersed well in the chitosan matrix, and dopamine‐mediated cross‐linking enhanced the stiffness and reduced swelling in the presence of water. The composite is too weak for use in hard tissue repair, but could be used for curing dentin sensitivity by blocking and remineralization on dentinal tubules, and in drug‐delivery applications.     

Exploring cellular adhesion and differentiation in a micro‐/nano‐hybrid polymer scaffold

Polymer scaffolds play an important role in three dimensional (3‐D) cell culture and tissue engineering. To best mimic the archiecture of natural extracellular matrix (ECM), a nano‐fibrous and micro‐porous combined (NFMP) scaffold was fabricated by combining phase separation and particulate leaching techniques. The NFMP scaffold possesses architectural features at two levels, including the micro‐scale pores and nano‐scale fibers. To evaluate the advantages of micro/nano combination, control scaffolds with only micro‐pores or nano‐fibers were fabricated. Cell grown in NFMP and control scaffolds were characterized with respect to morphology, proliferation rate, diffentiation and adhesion. The NFMP scaffold combined the advantages of micro‐ and nano‐scale structures. The NFMP scaffold nano‐fibers promoted neural differentiation and induced “3‐D matrix adhesion”, while the NFMP scaffold micro‐pores facilitated cell infiltration. This study represents a systematic comparison of cellular activities on micro‐only, nano‐only and micro/nano combined scaffolds, and demonstrates the unique advantages of the later. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010     

Clinical assessment of non carious cervical lesion using swept‐source optical coherence tomography

Non‐carious cervical lesions (NCCLs) involve various forms of tooth loss with different etiologies. This study aimed to utilize swept‐source optical coherence tomography (SS‐OCT) at 1300 nm wavelength range in vitro and in vivo to evaluate and clarify the mechanism of NCCLs. In the in vitro phase, a dentin attenuation coefficient (μ_t) derived from the SS‐OCT signal at NCCL was compared with mineral loss obtained from transverse microradiography (TMR) to determine a μ_t threshold to discriminate demineralization of cervical dentin in vivo. In the clinical study, 242 buccal surfaces were investigated in 35 subjects. Presence and dimensions of NCCLs, cervical cracking and the degree of demineralization at the exposed cervical dentin were determined using SS‐OCT. Dentin demineralization was observed in 69% of NCCLs. SS‐OCT results confirm that dentin mineral loss and occlusal attrition were associated with larger NCCLs, and can be considered as an etiological factor in formation and progress of these lesions.

( A ) We determined the attenuation coeffcient (μ_t) threshold of SS‐OCT signal for the detection of demineralization (1.21) from in vitro study. DEM: demineralized dentin, sound: sound dentin. ( B ) Using the μ_t threshold, we observed NCCLs in vivo to detect the demineralization in cervical dentin. SS‐OCT scanning was performed along the red line. ( C ) SS‐OCT image obtained along the red line in B. In SS‐OCT, brightness of dentin beneath the NCCL was increased (arrow) compared with intact zone. The cervical dentin was slightly demineralized (μ_t: 1.25). e: enamel, d: dentin, g: gingiva.     

Hippocampal nuclear factor kappa B accounts for stress‐induced anxiety behaviors via enhancing neuronal nitric oxide synthase (nNOS)‐carboxy‐terminal PDZ ligand of nNOS‐Dexras1 coupling

Anxiety disorders are associated with a high social burden worldwide. Recently, increasing evidence suggests that nuclear factor kappa B (NF‐κB) has significant implications for psychiatric diseases, including anxiety and depressive disorders. However, the molecular mechanisms underlying the role of NF‐κB in stress‐induced anxiety behaviors are poorly understood. In this study, we show that chronic mild stress (CMS) and glucocorticoids dramatically increased the expression of NF‐κB subunits p50 and p65, phosphorylation and acetylation of p65, and the level of nuclear p65 in vivo and in vitro , implicating activation of NF‐κB signaling in chronic stress‐induced pathological processes. Using the novelty‐suppressed feeding (NSF) and elevated‐plus maze (EPM) tests, we found that treatment with pyrrolidine dithiocarbamate (PDTC; intra‐hippocampal infusion), an inhibitor of NF‐κB, rescued the CMS‐ or glucocorticoid‐induced anxiogenic behaviors in mice. Microinjection of PDTC into the hippocampus reversed CMS‐induced up‐regulation of neuronal nitric oxide synthase (nNOS), carboxy‐terminal PDZ ligand of nNOS (CAPON), and dexamethasone‐induced ras protein 1 (Dexras1) and dendritic spine loss of dentate gyrus (DG) granule cells. Moreover, over‐expression of CAPON by infusing LV‐CAPON‐L‐GFP into the hippocampus induced nNOS‐Dexras1 interaction and anxiety‐like behaviors, and inhibition of NF‐κB by PDTC reduced the LV‐CAPON‐L‐GFP‐induced increases in nNOS‐Dexras1 complex and anxiogenic‐like effects in mice. These findings indicate that hippocampal NF‐κB mediates anxiogenic behaviors, probably via regulating the association of nNOS‐CAPON‐Dexras1, and uncover a novel approach to the treatment of anxiety disorders.

     

Sorting of Clathrin‐Independent Cargo Proteins Depends on Rab35 Delivered by Clathrin‐Mediated Endocytosis

Clathrin‐mediated endocytosis (CME) and clathrin‐independent endocytosis (CIE) co‐exist in most cells but little is known about their communication and coordination. Here we show that when CME was inhibited, endocytosis by CIE continued but endosomal trafficking of CIE cargo proteins was altered. CIE cargo proteins that normally traffic directly into Arf6‐associated tubules after internalization and avoid degradation (CD44, CD98 and CD147) now trafficked to lysosomes and were degraded. The endosomal tubules were also absent and Arf6‐GTP levels were elevated. The altered trafficking, loss of the tubular endosomal network and elevated Arf6‐GTP levels caused by inhibition of CME were rescued by expression of Rab35, a Rab associated with clathrin‐coated vesicles, or its effector ACAPs, Arf6 GTPase activating proteins (GAP) that inactivate Arf6. Furthermore, siRNA knockdown of Rab35 recreated the phenotype of CME ablation on CIE cargo trafficking without altering endocytosis of transferrin. These observations suggest that Rab35 serves as a CME detector and that loss of CME, or Rab35 input, leads to elevated Arf6‐GTP and shifts the sorting of CIE cargo proteins to lysosomes and degradation.      

Animal space use: distinguishing a two‐level superposition of scale‐specific walks from scale‐free Lévy walk

How to differentiate between scale‐free space use like Lévy walk and a two‐level scale‐specific process like composite random walk (mixture of intra‐ and inter‐patch habitat movement) is surrounded by controversy. Composite random walk may under some parameter conditions appear Lévy walk‐like from the perspective of the path’s distribution of step lengths due to superabundance of very long steps relative to the expectation from a classic (single‐level) random walk. However, a more explicit focus on the qualitative differences between studying movement at a high resolution mechanistic (behavioral) level and the more coarse‐grained statistical mechanical level may contribute to resolving both this and other issues related to scaling complexity. Specifically, a re‐sampling of a composite random walk at larger time lags than the micro‐level unit time step for the simulation makes a Lévy‐look‐alike step length distribution re‐shaping towards a Brownian motion‐like pattern. Conversely, a true Levy walk maintains its scaling characteristics upon re‐sampling. This result illustrates how a confusing pattern at the mechanistic level may be resolved by changing observational scale from the micro level to the coarser statistical mechanical meso‐ or macro‐scale. The instability of the composite random walk pattern under rescaling is a consequence of influence of the central limit theorem. I propose that a coarse‐graining test – studying simulated animal paths at a coarsened temporal scale by re‐sampling a series – should be routinely performed prior to comparing theoretical results with those patterns generated from GPS data describing animal movement paths. Fixes from terrestrial mammals are often collected at hourly intervals or larger, and such a priori coarse‐grained series may thus comply better with the statistical mechanical meso‐ or macro‐level of analysis than the behavioral mechanics observed at finer resolutions typically in the range of seconds and minutes. If fixes of real animals are collected at this high frequency, coarse graining both the simulated and real series is advised in order to bring the analysis into a temporal scale domain where analytical methods from statistical mechanics can be applied.     

Growth cone neuropilin‐1 mediates collapsin‐1/sema III facilitation of antero‐ and retrograde axoplasmic transport

Collapsin‐1/SemaIII, a member of the semaphorin family, has been implicated in axonal pathfinding as a repulsive guidance cue. Cellular and molecular mechanisms by which collapsin‐1 exerts its action are not fully understood. Collapsin‐1 induces growth cone collapse via a pathway which may include neuropilin‐1, a cell‐surface collapsin‐1 binding protein, as well as intracellular CRMP‐62 and heterotrimeric G proteins. We previously identified a second action of collapsin‐1, the facilitation of antero‐ and retrograde axoplasmic transport. This response occurs via a mechanism distinct from that causing growth cone collapse. To investigate the possible involvement of neuropilin‐1 in the action of collapsin‐1 on axoplasmic transport, we produced a soluble neuropilin‐1 (sNP‐1) lacking the transmembrane and intracellular region. sNP‐1 progressively displaced the dose–response curve for collapsin‐1 to induce growth cone collapse to higher concentrations. sNP‐1 also inhibited collapsin‐1‐induced augmentation of both antero‐ and retrograde axoplasmic transport. Furthermore, an anti‐neuropilin‐1 antibody blocked the collapsin‐induced axoplasmic transport. These results together indicate that neuropilin‐1 mediates collapsin‐1 action on axoplasmic transport. To visualize collapsin‐1 binding to endogenous neuropilin‐1, we used a truncated collapsin‐1–alkaline phosphatase fusion protein (CAP‐4). CAP‐4 stains the growth cone, neurite, and cell body. However, local application of collapsin‐1 to growth cone but to neither neurite nor cell body promotes axoplasmic transport. Thus, growth cone NP‐1 mediates the facilitatory action of collapsin‐1 on antero‐ and retrograde axoplasmic transport. © 1999 John Wiley & Sons, Inc. J Neurobiol 39: 579–589, 1999     

The influence of multi‐scale environmental variables on the distribution of terricolous lichens in a fog desert

Question: How do environmental variables in a hyper‐arid fog desert influence the distribution patterns of terricolous lichens on both macro‐ and micro‐scales? Location: Namib Desert, Namibia. Methods: Sites with varying lichen species cover were sampled for environmental variables on a macro‐scale (elevation, slope degree, aspect, proximity to river channels, and fog deposition) and on a micro‐scale (soil structure and chemistry). Macro‐scale and micro‐scale variables were analysed separately for associations with lichen species cover using constrained ordination (DCCA) and unconstrained ordination (DCA). Explanatory variables that dominated the first two axes of the constrained ordinations were tested against a lichen cover gradient. Results: Elevation and proximity to river channels were the most significant drivers of lichen species cover in the macro‐scale DCCA, but results of the DCA suggest that a considerable percentage of variation in lichen species cover is unexplained by these variables. On a micro‐scale, sediment particle size explained a majority of lichen community variations, followed by soil pH. When both macro and micro‐scale variables were tested along a lichen cover gradient, soil pH was the only variable to show a significant relationship to lichen cover. Conclusion: The findings suggest that landscape variables contribute to variations in lichen species cover, but that stronger links occur between lichen growth and small‐scale variations in soil characteristics, supporting the need for multi‐scale approaches in the management of threatened biological soil crust communities and related ecosystem functions.     

Honey Buzzard Pernis apivorus nest‐site selection in relation to habitat and the distribution of Goshawks Accipiter gentilis

The selection of a suitable nest‐site is critical for successful reproduction. Species' preferences for nest‐sites have presumably evolved in relation to local habitat resources and/or interactions with other species. The importance of these two components in the nest‐site selection of the Eurasian Honey Buzzard Pernis apivorus was assessed in two study areas in eastern Austria. There was almost no difference in macro‐ and micro‐habitat features between nest‐sites and random plots, suggesting that Honey Buzzards did not base their choice of nest‐site on habitat characteristics. However, nests were placed significantly further from nests of Northern Goshawk Accipiter gentilis than would be expected if nest‐sites had been chosen at random. Furthermore, in one study area Honey Buzzards appeared to favour areas close to human settlements, perhaps indicating a mechanism to avoid Goshawks, which tend to avoid the proximity of humans. No habitat variable was significantly associated with the loss of Honey Buzzard young, but predation was higher in territories closer to breeding pairs of Goshawks at both study sites. Although Honey Buzzards are restricted to nesting in forests, their choice of nest‐site therefore appears to be largely dictated by the distribution of predators. Studies of habitat association may yield misleading results if the effects of predation risk on distribution are not considered.     

A dedicated target capture approach reveals variable genetic markers across micro‐ and macro‐evolutionary time scales in palms

Understanding the genetics of biological diversification across micro‐ and macro‐evolutionary time scales is a vibrant field of research for molecular ecologists as rapid advances in sequencing technologies promise to overcome former limitations. In palms, an emblematic, economically and ecologically important plant family with high diversity in the tropics, studies of diversification at the population and species levels are still hampered by a lack of genomic markers suitable for the genotyping of large numbers of recently diverged taxa. To fill this gap, we used a whole genome sequencing approach to develop target sequencing for molecular markers in 4,184 genome regions, including 4,051 genes and 133 non‐genic putatively neutral regions. These markers were chosen to cover a wide range of evolutionary rates allowing future studies at the family, genus, species and population levels. Special emphasis was given to the avoidance of copy number variation during marker selection. In addition, a set of 149 well‐known sequence regions previously used as phylogenetic markers by the palm biological research community were included in the target regions, to open the possibility to combine and jointly analyse already available data sets with genomic data to be produced with this new toolkit. The bait set was effective for species belonging to all three palm sub‐families tested (Arecoideae, Ceroxyloideae and Coryphoideae), with high mapping rates, specificity and efficiency. The number of high‐quality single nucleotide polymorphisms (SNPs) detected at both the sub‐family and population levels facilitates efficient analyses of genomic diversity across micro‐ and macro‐evolutionary time scales.     

Photobiological implications of melanin photoprotection after UVB‐induced tanning of human skin but not UVA‐induced tanning

Repetitive suberythemal UVA and/or UVB exposures were used to generate comparable UV‐induced tans in human skin over the course of 2 weeks. To evaluate the potential photoprotective values of those UVA‐ and/or UVB‐ induced tans and to avoid the confounding issue of residual UV‐induced DNA damage, we waited 1 week before challenging those areas with a 1.5 MED of UVA+UVB after which we measure DNA damage. The results show that the type of UV used to induce skin pigmentation affects the redistribution of melanin in the skin and/or de novo melanin synthesis. The UVA‐induced tans failed to even provide a minimal SPF of 1.5, which suggests that producing a tan with UVA‐rich sunlamps prior to a holiday or vacation is completely counterproductive.