Seed rain composition responds to climate change in a subtropical forest

Recent climate change has been shown to alter aspects of forest plant demography, such as growth and mortality, but less attention has been focused on how climate change alters the reproduction of plant populations through time. We hypothesized that the plant seed production would respond to climate change, and that the response would differ according to plant life form and functional traits. We tested this hypothesis by examining climate change from 2005 to 2020 and by determining the temporal trends of seed rain and seed production from plants with different life forms (e.g., herbs, vines, trees, palms) and of tree species with different statures as well as leaf, seed and wood traits during 2014-2020. We also tested the correlation between meteorological variables and time series of seed rain using cross correlation analysis. We found increasing wetness (lower vapor pressure deficit) through time but with decreasing minimum relative humidity, which is a pattern consistent with trends seen in many other parts of the world. During the study period, seed production of shrubs and relative contribution of woody vines to total seed rain decreased, while relative contribution of palms to total seed rain and tree species with more conservative leaf traits increased their contribution to total seed rain. Overall, these trends were well explained by the trends of meteorological variables and the responses of these life forms to climate change in previous studies. Additionally, the increasingly conservative leaf traits were also consistent with shifts in traits following recovery from disturbance. Our results suggest that a trait-based approach may help to unveil trends that are not readily apparent by examining seed counts alone. The compositional change found in the seed rain may indicate future shifts in forest species composition and should be incorporated into future studies of forest modelling and projections under climate change.

Neutrophil extracellular traps and complications of liver transplantation

Many end-stage liver disease etiologies are attributed to robust inflammatory cell recruitment. Neutrophils play an important role in inflammatory infiltration and neutrophil phagocytosis, oxidative burst, and degranulation. It has also been suggested that neutrophils may release neutrophil extracellular traps (NETs) to kill pathogens. It has been proven that neutrophil infiltration within the liver contributes to an inflammatory microenvironment and immune cell activation. Growing evidence implies that NETs are involved in the progression of numerous complications of liver transplantation, including ischemia-reperfusion injury, acute rejection, thrombosis, and hepatocellular carcinoma recurrence. NETs are discussed in this comprehensive review, focusing on their effects on liver transplantation complications. Furthermore, we discuss NETs as potential targets for liver transplantation therapy.

Elevated YKL-40 serum levels may contribute to wet age-related macular degeneration via the ERK1/2 pathway

Choroidal neovascularization (CNV) is a key characteristic of wet age-related macular degeneration (AMD) that can lead to severe vision loss in the elderly. Anti-VEGF therapy is currently the premier strategy for wet AMD, but it has limited efficacy. Previous studies have shown that chitinase-3-like-1 (YKL-40) can promote microangiogenesis and inflammation, but its effect on CNV formation has not yet been studied. Here, we investigated the potential role of YKL-40 in wet AMD and the underlying mechanism(s). We report that the serum expression of YKL-40 in wet AMD patients was significantly higher than that in control patients and was positively correlated with VEGF expression, indicating that YKL-40 may participate in the development of wet AMD. In addition, YKL-40 and VEGF expression levels were observed to be increased and the ERK1/2 pathway activated in the neuroretinal (NR) and RPE/choroid tissues of mice with laser-induced CNV. The YKL-40 and phosphorylated protein levels of the ERK1/2 pathway were decreased after intravitreal injection with an anti-YKL-40 antibody, suggesting that anti-YKL-40 could inhibit the activation of the ERK1/2 pathway. These results indicate that YKL-40 may serve as a novel target for the diagnosis and treatment of wet AMD.

Moderate oxidative stress promotes epithelial-mesenchymal transition in the lens epithelial cells via the TGF-β/Smad and Wnt/β-catenin pathways

The epithelial-mesenchymal transition (EMT) plays a significant role in fibrosis and migration of lens epithelial cells (LECs), and eventually induces posterior capsule opacification (PCO). In the past, it was generally believed that the TGF-β/Smad pathway regulates lens EMT. A recent study found that attenuated glutathione level promotes LECs EMT via the Wnt/β-catenin pathway, which suggests a more complex pathogenesis of PCO. To test the hypothesis, we used the mouse cataract surgery PCO model and tested both canonical Wnt/β-catenin and TGF-β/Smad signaling pathways. The results showed that both TGF-β/Smad and Wnt/β-catenin pathways were activated during the lens capsule fibrosis. Compared with the freshly isolated posterior capsule, the expression level of phosphorylated Smad2 was highest at day3 and then slightly decreased, but the expression level of Wnt10a gradually increased from day0 to day7. It shows that these two pathways are involved in the lens epithelium's fibrotic process and may play different roles in different periods. Subsequently, we established oxidative stress-induced EMT model in primary porcine lens epithelial cells and found that both the TGF-β/Smad and Wnt/β-catenin pathways were activated. Further study suggests that block Wnt/β-catenin pathway using XAV939 alone or block TGF-β/Smad pathway using LY2109761 could partially block pLECs fibrosis, but blocking Wnt/β-catenin and TGF-β/Smad pathway using combined XAV939 and LY2109761 could completely block pLECs fibrosis. In conclusion, this study demonstrates that both TGF-β/Smad and canonical Wnt/β-catenin pathways play a significant role in regulating epithelial-mesenchymal transformation of lens epithelial cells but might be in a different stage.

Testing the competition-colonization trade-off and its correlations with functional trait variations among subtropical tree species

The competition-colonization trade-off, by which species can partition spatial niches, is a potentially important mechanism allowing the maintenance of species diversity in plant communities. We examined whether there was evidence for this trade-off among tree species in a subtropical forest and how it correlated with eight functional traits. We developed and estimated a metric for colonization ability that incorporates both fecundity and seed dispersal based on seed trap data and the sizes and distributions of adult trees. Competitive ability was estimated as survival probability under high crowding conditions based on neighborhood models. Although we found no significant relationship between colonization and competitive abilities, there was a significant negative correlation between long distance dispersal ability and competitive ability at the 5 cm size class. Colonizers had traits associated with faster growth, such as large leaves and low leaf lamina density, whereas competitors had traits associated with higher survival, such as dense wood. Our results imply that any trade-off between competition and colonization may be more determined by dispersal ability than by fecundity, suggesting that seed dispersal is an important contributor to diversity maintenance. Future work should test how competitive ability covaries with the components of colonization ability, as we did here.

Increased serum levels of soluble CD146 and vascular endothelial growth factor receptor 2 in patients with exudative age-related macular degeneration

AIM

To investigate serum levels of soluble CD146 (sCD146) and vascular endothelial growth factor receptor 2 (VEGFR2) in patients with age-related macular degeneration (AMD).

METHODS

Eighty-eight patients with exudative AMD and 45 sex- and age-matched healthy controls were enrolled in this study conducted in China. Serum samples was obtained from the patients with exudative AMD and from the controls. Serum sCD146 and VEGFR2 protein levels were measured using an enzyme-linked immunosorbent assay.

RESULTS

We found that serum sCD146 and VEGFR2 protein levels were significantly higher in the patients with exudative AMD group than in the controls (t=3.859, P<0.001 and t=3.829, P<0.001, respectively). Serum sCD146 levels were significantly higher in patients with classic choroidal neovascularization (CNV) than in those with occult CNV (t=9.899, P<0.001). There was a significant difference in the trend for exudative AMD in the highest versus lowest quartile of circulating sCD146 levels (χ ²=10.29, P=0.001). The receiver operating characteristic curve analysis showed that the area under the curve was 0.696 for sCD146 (95%CI: 0.601-0.791) with an optimum diagnostic cut-off value of 157.16 ng/mL, a sensitivity of 55.7%, and a specificity of 82.2%.

CONCLUSION

The serum sCD146 level increases and may be a biomarker for exudative AMD.

Activation of liver X receptor α protects amyloid β1-40 induced inflammatory and senescent responses in human retinal pigment epithelial cells

OBJECTIVE

To investigate whether activation of the liver X receptors (LXRs) inhibits amyloid β_1-40 (Aβ_1-40) induced inflammatory and senescent responses in human retinal pigment epithelial (RPE) cells.

MATERIALS AND METHODS

Confluent cultures of human primary RPE and ARPE-19 cells pretreated with 5 μΜ of TO901317 (TO90), a synthetic agonist of LXR, or vehicle were incubated with 1 μΜ of Aβ_1-40 or Aβ_40-1. The optimum concentrations of Aβ_1-40 and TO90 were determined by cell viability assay. Pro-inflammatory cytokines IL-6, IL-8, MCP-1 were detected by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Expression and localization of an aging protein p16INK4a (p16) were analyzed by western blotting and immunofluorescence. Expressions of LXRs and one of their target genes ATP-binding cassette transporter A1 (ABCA1) were examined by real-time PCR and western blotting. Phosphorylated transcription inhibition factor-κB-α (p-IκB-α) was assessed by western blotting.

RESULTS

A negative linear relationship between the Aβ_1-40 concentration and the cell viability was evident, indicating Aβ_1-40 decreased ARPE-19 cell viability in a dose-dependent manner. Aβ_1-40 enhanced the expression of IL-6, IL-8, MCP-1 as well as p16 in both RPE cell lines at both mRNA and protein levels, whereas TO90 counteracted the detrimental effects. TO90 upregulated the expression of LXRα and its target gene ABCA1, but it did not affect the expression of LXRβ. Meanwhile, TO90 inhibited the phosphorylation of IκB-α mediated by Aβ_1-40 stimulation.

CONCLUSION

Activation of the LXRα-ABCA1 axis may alleviate Aβ_1-40 induced inflammatory and senescent responses in RPE cells. The beneficial effect appears associated with the inhibition of the NF-κB signaling pathway.

Different relationships between temporal phylogenetic turnover and phylogenetic similarity and in two forests were detected by a new null model

BACKGROUND

Ecologists have been monitoring community dynamics with the purpose of understanding the rates and causes of community change. However, there is a lack of monitoring of community dynamics from the perspective of phylogeny.

METHODS/PRINCIPLE FINDINGS

We attempted to understand temporal phylogenetic turnover in a 50 ha tropical forest (Barro Colorado Island, BCI) and a 20 ha subtropical forest (Dinghushan in southern China, DHS). To obtain temporal phylogenetic turnover under random conditions, two null models were used. The first shuffled names of species that are widely used in community phylogenetic analyses. The second simulated demographic processes with careful consideration on the variation in dispersal ability among species and the variations in mortality both among species and among size classes. With the two models, we tested the relationships between temporal phylogenetic turnover and phylogenetic similarity at different spatial scales in the two forests. Results were more consistent with previous findings using the second null model suggesting that the second null model is more appropriate for our purposes. With the second null model, a significantly positive relationship was detected between phylogenetic turnover and phylogenetic similarity in BCI at a 10 m×10 m scale, potentially indicating phylogenetic density dependence. This relationship in DHS was significantly negative at three of five spatial scales. This could indicate abiotic filtering processes for community assembly. Using variation partitioning, we found phylogenetic similarity contributed to variation in temporal phylogenetic turnover in the DHS plot but not in BCI plot.

CONCLUSIONS/SIGNIFICANCE

The mechanisms for community assembly in BCI and DHS vary from phylogenetic perspective. Only the second null model detected this difference indicating the importance of choosing a proper null model.

Unimodal tree size distributions possibly result from relatively strong conservatism in intermediate size classes

Tree size distributions have long been of interest to ecologists and foresters because they reflect fundamental demographic processes. Previous studies have assumed that size distributions are often associated with population trends or with the degree of shade tolerance. We tested these associations for 31 tree species in a 20 ha plot in a Dinghushan south subtropical forest in China. These species varied widely in growth form and shade-tolerance. We used 2005 and 2010 census data from that plot. We found that 23 species had reversed J shaped size distributions, and eight species had unimodal size distributions in 2005. On average, modal species had lower recruitment rates than reversed J species, while showing no significant difference in mortality rates, per capita population growth rates or shade-tolerance. We compared the observed size distributions with the equilibrium distributions projected from observed size-dependent growth and mortality. We found that observed distributions generally had the same shape as predicted equilibrium distributions in both unimodal and reversed J species, but there were statistically significant, important quantitative differences between observed and projected equilibrium size distributions in most species, suggesting that these populations are not at equilibrium and that this forest is changing over time. Almost all modal species had U-shaped size-dependent mortality and/or growth functions, with turning points of both mortality and growth at intermediate size classes close to the peak in the size distribution. These results show that modal size distributions do not necessarily indicate either population decline or shade-intolerance. Instead, the modal species in our study were characterized by a life history strategy of relatively strong conservatism in an intermediate size class, leading to very low growth and mortality in that size class, and thus to a peak in the size distribution at intermediate sizes.

217 PROMOTER-SPECIFIC EXPRESSION OF THE IMPRINTED Igf2 GENE IN CATTLE

Insulin-like growth factor II (Igf2) is an imprinted gene crucial to fetal development and maternal/fetal nutrient transfer. Studies in the pig have demonstrated that this quantitative trait locus controls muscle growth, fat deposition, and heart size. Additionally, studies have shown that four splice variants transcribed from promoters (P1–P4) regulate the complex temporal and spatial expression of Igf2 in mice, humans, pigs, and horses. Cattle have a cotyledonary placenta and therefore a distinct type of maternal/fetal interaction. Here we have studied for the first time the promoter-specific expression of Igf2 in cattle, an economically valuable livestock species. Five naturally reproduced animals obtained from an abattoir were used in this study (2 mid-gestation fetuses, 1 calf, and 2 adults) of which all major internal organs were tested. Here we used RT-PCR to show that, like that of the pig and the human, the bovine Igf2 is expressed from four different promoters in a temporal and spatial manner. However, unlike for pigs and humans, we have found that transcripts from promoter P1 were present in several bovine fetal and adult tissues including the liver, heart, kidney, lung, placenta, and spleen. Promoter P2 was expressed only in mid-gestation fetal tissues including the liver, bladder, lung, and kidney. Promoter P2 was not detected in the brain. Promoter P3 was expressed ubiquitously throughout fetal and adult life; however, expression appears to be lower in the heart. Promoter P4 was expressed in all mid-gestation fetal tissues. Transcription from P4 decreased with age until transcripts were detected only in the kidney, lung, heart, and spleen. Using single-stranded conformational polymorphism polyacrylamide gel electrophoresis and a single nucleotide polymorphism in exon 10 of Igf2, we have confirmed that a loss of imprinting occurs with age from all transcripts (P1–P4) and biallelic expression is observed in most adult tissues studied. This work was funded by a grant from the USDA.

Spontaneous apoptosis in human colon tumor cell lines and the relation of wt p53 to apoptosis

OBJECTIVE

To examine spontaneous apoptosis of cultured human colon tumor cell lines in vitro and to investigate the role of wild type (wt) p53 in regulation of apoptosis induced by DNA-damaging treatment.

METHODS

A model system of human tumor progression involving three cell lines was used in this study for examination of apoptosis. They were originally established from human colon villous adenoma, including an early passage of non-tumorigenic cell line, V235E; a late passage of weakly tumorigenic cell line, V235L; and a spontaneous progressing highly tumorigenic cell line. V411. All of them maintain wt p53 expression. For identification of apoptosis, two tests were performed: 1. morphology study using acridine orange (AO)/ethidium bromide (EB) stainning by fluorescence microscopy; 2. DNA electrophoresis on agarose gel. P53 and WAF-1 (a downstream gene of p53) expressions were analysed at mRNA level using Northern blot technique. Apoptotic index of cell lines examined was measured by DNA fluorescence assay.

RESULTS

Spontaneous apoptosis was demonstrated in cell lines of all stages of progression by both morphology and DNA agarose gel electrophoresis. Apoptosis was further induced in V411 after treatment of cells with 137Cs gamma-irradiation and accompanied by increases in p53 and WAF-1 expression. In contrast, a mutant p53 bearing human colon cancer cell line, sw480, lacked spontaneous apoptosis, and upon irradiation neither induction of apoptosis nor increase expression of p53 and WAF-1 were seen.

CONCLUSIONS

Apoptosis can be maintained in some human tumor cell lines despite transformation and carcinogenesis. Wt p53 and WAF-1 products are two of the potential mediators which effect apoptosis. Additionally, since apoptosis was enhanced by irradiation in V411, but not in sw480, it suggests that wt p53 cancer cells are more sensitive to DNA-damaging treatment than mutant p53 cancer cells. These finding may have implications for cancer therapy.

Comparison of 5-mm and 6-mm Ablation Zones in Photorefractive Keratectomy for Myopia

BACKGROUND

Variation in ablation zone diameter may alter visual acuity and/or refractive effect in photorefractive keratectomy. Despite theoretical benefits of using a smaller diameter ablation zone, clinical studies suggest that a larger ablation zone may decrease problems associated with photorefractive keratectomy.

METHODS

The results of our initial 34 consecutive eyes treated with a 5-mm diameter ablation zone using a Summit Technology ExciMed UV200LA excimer laser were compared retrospectively to our initial 34 consecutive eyes treated with a 6-mm diameter ablation zone using a Summit OmniMed excimer laser. Eyes had a spherical equivalent refraction between -1.00 and -6.00 diopters (D) and astigmatism less than 1.00 D. Patients were followed for a minimum of 6 months.

RESULTS

Eyes treated with a 6-mm ablation zone had less hyperopia and a spherical equivalent refraction closer to emmetropia at 1, 2, and 3 months (P = 0.001). Eyes treated with a 6-mm ablation zone had better uncorrected visual acuity at 1 and 2 months (P = 0.001). Less subepithelial haze was noted at 2 months (P = 0.01) and 3 months (P = 0.002) in the 6-mm group. At 6 months postoperatively, 30 of 32 eyes (94%) treated with a 6-mm ablation zone had a spherical equivalent refraction within 0.50 D of emmetropia, and all 32 eyes (100%) were within 1.00 D of emmetropia; in the 5-mm ablation zone group, 28 of 34 eyes (80%) were within 0.50 D and 29 (85%) were within 1.00 D of emmetropia. Patients treated with a 6-mm ablation zone complained less of night halos and had fewer differences between night and day vision.

CONCLUSIONS

In this study of myopia of -1.00 D to -6.00 D, eyes treated with a 6-mm ablation zone achieve a more rapid visual recovery with less variation in refractive outcome and less adverse effects than those treated with a 5-mm ablation zone.