Optoacoustic mesoscopy analysis and quantitative estimation of specific imaging metrics in Fitzpatrick skin phototypes II to V

Raster Scanning Optoacoustic Mesoscopy (RSOM) is a novel optoacoustic imaging modality that offers non‐invasive, label‐free, high resolution (~7 μm axial, ~30 μm lateral) imaging up to 1 to 2 mm below the skin, providing novel quantitative insights into skin pathophysiology. As the RSOM image contrast mechanism is based on light absorption, it is expected that the amount of melanin present in the skin will affect RSOM images. However, the effect of skin tone in the performance of RSOM has not been addressed so far. Herein, we present the efficiency of RSOM for in vivo skin imaging of human subjects with Fitzpatrick (FP) skin types between II to V. RSOM images acquired from the volar forearms of the subjects were used to derive metrics used in RSOM studies, such as total blood volume, vessel diameter and melanin signal intensity. Our study shows that the melanin signal intensity derived from the RSOM images exhibited an excellent correlation with that obtained from a clinical colorimeter for the subjects of varying FP skin types. We could successfully estimate the vessel diameter at different depths of the dermis. Furthermore, our study shows that there is a need to compensate for total blood volume calculated for subjects with higher FP skin types due to the lower signal‐to‐noise ratio in dermis, owing to strong absorption of light by melanin. This study sheds light into how RSOM can be used for studying various skin conditions in populations with different skin phenotypes.     

Phenotypic and genetic diversity in aposematic Malagasy poison frogs (genus Mantella)

Intraspecific color variation has long fascinated evolutionary biologists. In species with bright warning coloration, phenotypic diversity is particularly compelling because many factors, including natural and sexual selection, contribute to intraspecific variation. To better understand the causes of dramatic phenotypic variation in Malagasy poison frogs, we quantified genetic structure and color and pattern variation across three closely related species, Mantella aurantiaca, Mantella crocea, and Mantella milotympanum. Although our restriction site‐associated DNA (RAD) sequencing approach identified clear genetic clusters, they do not align with current species designations, which has important conservation implications for these imperiled frogs. Moreover, our results suggest that levels of intraspecific color variation within this group have been overestimated, while species diversity has been underestimated. Within major genetic clusters, we observed distinct patterns of variation including: populations that are phenotypically similar yet genetically distinct, populations where phenotypic and genetic breaks coincide, and populations that are genetically similar but have high levels of within‐population phenotypic variation. We also detected admixture between two of the major genetic clusters. Our study suggests that several mechanisms—including hybridization, selection, and drift—are contributing to phenotypic diversity. Ultimately, our work underscores the need for a reevaluation of how polymorphic and polytypic populations and species are classified, especially in aposematic organisms.     

下调TLR4对LPS诱导的支气管上皮16HBE细胞损伤的影响及其机制

目的探讨TLR4对脂多糖（LPS）诱导的支气管上皮16HBE细胞损伤的影响及其机制。 方法将3条siRNA-TLR4-1、siRNA-TLR4-2和siRNA-TLR4-3转染至16HBE细胞中,筛选出最佳的siRNA-TLR4干扰序列进行实验。实验分为对照组（未处理）、LPS组（给予50 μg/ml LPS处理）、LPS+siNC组（转染siRNA-NC后给予50 μg/ml LPS处理）和LPS+siTLR4组（分别转染设计的3条siRNA-TLR4后给予50 μg/ml LPS处理）,采用RT-PCR检测TLR4、IL-6和TNF-α mRNA的表达,MTT法检测细胞活力,流式细胞仪检测细胞凋亡率,Western Blot检测Bcl-2、Bax、Cleaved Caspase-3、NF-κB p65和IκBα蛋白的表达。多组间比较使用单因素方差分析,组间多重比较采用SNK-q,两组间比较采用独立样本t检验。 结果LPS组与LPS+siTLR4-2组TLR4 mRNA（2.05±0.12,3.28±0.15）和蛋白表达（0.38±0.03,0.77±0.05）比较,差异具有统计学意义（t?= 11.091,11.585,P均< 0.001）;LPS组与LPS+siTLR4-3组TLR4 mRNA（1.39±0.09,3.28±0.15）和蛋白表达（0.31±0.02,0.77±0.05）比较,差异具有统计学意义（t?= 20.857,12.650,P均?< 0.001）且siRNA-TLR4-3的效果最为显著。与对照组相比,LPS组、LPS+siNC组和LPS+siTLR4组细胞中IL-6 mRNA（11.42±1.05,11.38±1.34,6.22±0.35,0.97±0.06,F?= 98.803,P均< 0.01）、TNF-α mRNA（15.76±1.12,15.69±0.87,7.54±0.41,1.03±0.09,F?= 278.064,P均< 0.01）、Cleaved Caspase-3蛋白（0.75±0.06,0.77±0.05,0.38±0.03,0.13±0.02,F?= 154.851,P均< 0.01）、Bax蛋白（0.48±0.05,0.52±0.05,0.33±0.02,0.11±0.02,F?= 71.310,P均< 0.01）、NF-κBp65蛋白（0.64±0.05,0.67±0.05,0.45±0.04,0.28±0.02,F?= 56.571,P?均?< 0.01）的表达水平和细胞凋亡率[（21.36±2.85）﹪,（20.94±3.22）﹪,（13.08±1.16）?﹪,（7.25±1.28）﹪,F?= 25.685,P均< 0.01]均明显升高,而细胞活力（0.53±0.04,0.51±0.04,0.78±0.06,1.15±0.08,F?= 80.811,P均< 0.01）和Bcl-2蛋白（0.28±0.03,0.25±0.03,0.40±0.03,0.69±0.06,F?= 76.762,P均< 0.01）、IκBα蛋白（0.38±0.03,0.35±0.03,0.44±0.03,0.72±0.06,F?= 53.635,P均< 0.01）的表达水平均明显降低;与LPS组相比,LPS+siTLR4组中IL-6 mRNA、TNF-α mRNA、Cleaved Caspase-3蛋白、Bax蛋白、NF-κBp65蛋白的表达水平和细胞凋亡率均明显降低,差异有统计学意义（t = 8.138,11.937,9.553,4.825,5.140,4.661,P均< 0.01）,而细胞活力和Bcl-2蛋白、IκBα蛋白的表达水平均明显升高,差异有统计学意义（t = 6.005,4.899,3.674,P < 0.05）,而LPS组和LPS+siNC组间差异无统计学意义（P > 0.05）。 结论下调TLR4可通过抑制NF-κB通路激活抑制LPS诱导的细胞凋亡和炎症反应减轻16HBE细胞损伤。     

Inhibition of nucleolar stress response by Sirt1: A potential mechanism of acetylation‐independent regulation of p53 accumulation

The mammalian Sirt1 deacetylase is generally thought to be a nuclear protein, but some pilot studies have suggested that Sirt1 may also be involved in orchestrating nucleolar functions. Here, we show that nucleolar stress response is a ubiquitous cellular reaction that can be induced by different types of stress conditions, and Sirt1 is an endogenous suppressor of nucleolar stress response. Using stable isotope labeling by amino acids in cell culture approach, we have identified a physical interaction of between Sirt1 and the nucleolar protein nucleophosmin, and this protein–protein interaction appears to be necessary for Sirt1 inhibition on nucleolar stress, whereas the deacetylase activity of Sirt1 is not strictly required. Based on the reported prerequisite role of nucleolar stress response in stress‐induced p53 protein accumulation, we have also provided evidence suggesting that Sirt1‐mediated inhibition on nucleolar stress response may represent a novel mechanism by which Sirt1 can modulate intracellular p53 accumulation independent of lysine deacetylation. This process may represent an alternative mechanism by which Sirt1 regulates functions of the p53 pathway.     

Substituting Threonine 187 with Alanine in p27Kip1 Prevents Pituitary Tumorigenesis by Two-Hit Loss of Rb1 and Enhances Humoral Immunity in Old Age

p27Kip1 (p27) is an inhibitor of cyclin-dependent kinases. Inhibiting p27 protein degradation is an actively developing cancer therapy strategy. One focus has been to identify small molecule inhibitors to block recruitment of Thr-187-phosphorylated p27 (p27T187p) to SCF^Skp2/Cks1 ubiquitin ligase. Since phosphorylation of Thr-187 is required for this recruitment, p27T187A knockin (KI) mice were generated to determine the effects of systemically blocking interaction between p27 and Skp2/Cks1 on tumor susceptibility and other proliferation related mouse physiology. Rb1^+/− mice develop pituitary tumors with full penetrance and the tumors are invariably Rb1^−/−, modeling tumorigenesis by two-hit loss of RB1 in humans. Immunization induced humoral immunity depends on rapid B cell proliferation and clonal selection in germinal centers (GCs) and declines with age in mice and humans. Here, we show that p27T187A KI prevented pituitary tumorigenesis in Rb1^+/− mice and corrected decline in humoral immunity in older mice following immunization with sheep red blood cells (SRBC). These findings reveal physiological contexts that depend on p27 ubiquitination by SCF^Skp2-Cks1 ubiquitin ligase and therefore help forecast clinical potentials of Skp2/Cks1-p27T187p interaction inhibitors. We further show that GC B cells and T cells use different mechanisms to regulate their p27 protein levels, and propose a T helper cell exhaustion model resembling that of stem cell exhaustion to understand decline in T cell-dependent humoral immunity in older age.     

Nonneutralizing Antibodies Induced by the HIV-1 gp41 NHR Domain Gain Neutralizing Activity in the Presence of the HIV Fusion Inhibitor Enfuvirtide: a Potential Therapeutic Vaccine Strategy

A key barrier against developing preventive and therapeutic human immunodeficiency virus (HIV) vaccines is the inability of viral envelope glycoproteins to elicit broad and potent neutralizing antibodies. However, in the presence of fusion inhibitor enfuvirtide, we show that the nonneutralizing antibodies induced by the HIV type 1 (HIV-1) gp41 N-terminal heptad repeat (NHR) domain (N63) exhibit potent and broad neutralizing activity against laboratory-adapted HIV-1 strains, including the drug-resistant variants, and primary HIV-1 isolates with different subtypes, suggesting the potential of developing gp41-targeted HIV therapeutic vaccines.     

Hepatic Apolipoprotein M (ApoM) Overexpression Stimulates Formation of Larger ApoM/Sphingosine 1-Phosphate-enriched Plasma High Density Lipoprotein

Apolipoprotein M (apoM), a lipocalin family member, preferentially associates with plasma HDL and binds plasma sphingosine 1-phosphate (S1P), a signaling molecule active in immune homeostasis and endothelial barrier function. ApoM overexpression in ABCA1-expressing HEK293 cells stimulated larger nascent HDL formation, compared with cells that did not express apoM; however, the in vivo role of apoM in HDL metabolism remains poorly understood. To test whether hepatic apoM overexpression increases plasma HDL size, we generated hepatocyte-specific apoM transgenic (APOM Tg) mice, which had an ∼3–5-fold increase in plasma apoM levels compared with wild-type mice. Although HDL cholesterol concentrations were similar to wild-type mice, APOM Tg mice had larger plasma HDLs enriched in apoM, cholesteryl ester, lecithin:cholesterol acyltransferase, and S1P. Despite the presence of larger plasma HDLs in APOM Tg mice, in vivo macrophage reverse cholesterol transport capacity was similar to that in wild-type mice. APOM Tg mice had an ∼5-fold increase in plasma S1P, which was predominantly associated with larger plasma HDLs. Primary hepatocytes from APOM Tg mice generated larger nascent HDLs and displayed increased sphingolipid synthesis and S1P secretion. Inhibition of ceramide synthases in hepatocytes increased cellular S1P levels but not S1P secretion, suggesting that apoM is rate-limiting in the export of hepatocyte S1P. Our data indicate that hepatocyte-specific apoM overexpression generates larger nascent HDLs and larger plasma HDLs, which preferentially bind apoM and S1P, and stimulates S1P biosynthesis for secretion. The unique apoM/S1P-enriched plasma HDL may serve to deliver S1P to extrahepatic tissues for atheroprotection and may have other as yet unidentified functions.     

THE EVOLUTION OF BIPEDALISM IN JERBOAS (RODENTIA: DIPODOIDEA): ORIGIN IN HUMID AND FORESTED ENVIRONMENTS

Mammalian bipedalism has long been thought to have arisen in response to arid and open environments. Here, we tested whether bipedalism coevolved with environmental changes using molecular and paleontological data from the rodent superfamily Dipodoidea and statistical methods for reconstructing ancestral characteristics and past climates. Our results show that the post‐Late Miocene aridification exerted selective pressures on tooth shape, but not on leg length of bipedal jerboas. Cheek tooth crown height has increased since the Late Miocene, but the hind limb/head‐body length ratios remained stable and high despite the environmental change from humid and forested to arid and open conditions, rather than increasing from low to high as predicted by the arid‐bipedalism hypothesis. The decoupling of locomotor and dental character evolution indicates that bipedalism evolved under selective pressure different from that of dental hypsodonty in jerboas. We reconstructed the habitats of early jerboas using floral and faunal data, and the results show that the environments in which bipedalism evolved were forested. Our results suggest that bipedalism evolved as an adaptation to humid woodlands or forests for vertical jumping. Running at high speeds is likely a by‐product of selection for jumping, which became advantageous in open environments later on.