Positive relationships among aboveground biomass,tree species diversity,and urban greening management in tropical coastal city of Haikou

Within urban green spaces, tree species diversity is believed to correlate with aboveground biomass, though there is some disagreement within the literature on the strength and directionality of the relationship. Therefore, we assessed the relationship between the biodiversity of woody species and the aboveground biomass of woody plant species in the tropical, coastal city of Haikou in southern China. To accomplish this, we obtained comprehensive tree and site data through field sampling of 190 urban functional units (UFUs, or work units) corresponding to six types of land uses governmental‐institutional, industrial‐commercial, park‐recreational, residential, transport infrastructure, and undeveloped area. Based on our field data, we investigated the relationship between tree species diversity and aboveground biomass using multiple regression, which revealed significant relationships across all five types of land uses. Aboveground biomass in green spaces was also correlated with anthropogenic factors, especially time since urban development, or site age, annual maintenance frequency by human caretakers, and human population density. Among these factors, maintenance is the strongest predictor of aboveground biomass in urban green space. Therefore, this study highlights the critical role of maintenance of urban green space in promoting both aboveground biomass and woody biodiversity in urban ecosystems and, consequently, on urban ecosystem services. Our findings contribute to a deeper understanding of the ecosystem services provided by communities of woody plant species in urban areas.     

Comprehensive mutation analysis in colorectal flat adenomas

Background

Flat adenomas are a subgroup of colorectal adenomas that have been associated with a distinct biology and a more aggressive clinical behavior compared to their polypoid counterparts. In the present study, we aimed to compare the mutation spectrum of 14 cancer genes, between these two phenotypes.

Methods

A consecutive series of 106 flat and 93 polypoid adenomas was analyzed retrospectively for frequently occurring mutations in “hot spot” regions of KRAS, BRAF, PIK3CA and NRAS, as well as selected mutations in CTNNB1 (β-catenin), EGFR, FBXW7 (CDC4), PTEN, STK11, MAP2K4, SMAD4, PIK3R1 and PDGFRA using a high-throughput genotyping technique. Additionally, APC was analyzed using direct sequencing.

Results

APC mutations were more frequent in polypoid adenomas compared to flat adenomas (48.5% versus 30.3%, respectively, p = 0.02). Mutations in KRAS, BRAF, NRAS, FBXW7 and CTNNB1 showed similar frequencies in both phenotypes. Between the different subtypes of flat adenomas (0-IIa, LST-F and LST-G) no differences were observed for any of the investigated genes.

Conclusion

The lower APC mutation rate in flat adenomas compared to polypoid adenomas suggests that disruption of the Wnt-pathway may occur via different mechanisms in these two phenotypes. Furthermore, in contrast to previous observations our results in this large well-defined sample set indicate that there is no significant association between the different morphological phenotypes and mutations in key genes of the RAS-RAF-MAPK pathway.     

Inferring the biogeographic origins of inter‐continental disjunct endemics using a Bayes‐DIVA approach

The arcto‐Tertiary relictual flora is comprised of many genera that occur non‐contiguously in the temperate zones of eastern Asia, Europe, eastern North America, and western North America. Within each distributional area, species are typically endemic and may thus be widely separated from closely related species within the other areas. It is widely accepted that this common pattern of distribution resulted from of the fragmentation of a once more‐continuous arcto‐Tertiary forest. The historical biogeographic events leading to the present‐day disjunction have often been investigated using a phylogenetic approach. Limitations to these previous studies have included phylogenetic uncertainty and uncertainty in ancestral range reconstructions. However, the recently described Bayes‐DIVA method handles both types of uncertainty. Thus, we used Bayes‐DIVA analysis to reconstruct the stem lineage distributions for 185 endemic lineages from 23 disjunct genera representing 17 vascular plant families. In particular, we asked whether endemic lineages within each of the four distributional areas more often evolved from (1) widespread ancestors, (2) ancestors dispersed from other areas, or (3) endemic ancestors. We also considered which of these three biogeographic mechanisms may best explain the origins of arcto‐Tertiary disjunct endemics in the neotropics. Our results show that eastern Asian endemics more often evolved from endemic ancestors compared to endemics in Europe and eastern and western North America. Present‐day endemic lineages in the latter areas more often arose from widespread ancestors. Our results also provide anecdotal evidence for the importance of dispersal in the biogeographic origins of arcto‐Tertiary species endemic in the neotropics.     

Mouse models to unravel the role of inhaled pollutants on allergic sensitization and airway inflammation

Background

Nicotinic acetylcholine receptors (nAChR) have been identified on a variety of cells of the immune system and are generally considered to trigger anti-inflammatory events. In the present study, we determine the nAChR inventory of rat alveolar macrophages (AM), and investigate the cellular events evoked by stimulation with nicotine.

Methods

Rat AM were isolated freshly by bronchoalveolar lavage. The expression of nAChR subunits was analyzed by RT-PCR, immunohistochemistry, and Western blotting. To evaluate function of nAChR subunits, electrophysiological recordings and measurements of intracellular calcium concentration ([Ca²⁺]_i) were conducted.

Results

Positive RT-PCR results were obtained for nAChR subunits α3, α5, α9, α10, β1, and β2, with most stable expression being noted for subunits α9, α10, β1, and β2. Notably, mRNA coding for subunit α7 which is proposed to convey the nicotinic anti-inflammatory response of macrophages from other sources than the lung was not detected. RT-PCR data were supported by immunohistochemistry on AM isolated by lavage, as well as in lung tissue sections and by Western blotting. Neither whole-cell patch clamp recordings nor measurements of [Ca²⁺]_i revealed changes in membrane current in response to ACh and in [Ca²⁺]_i in response to nicotine, respectively. However, nicotine (100 μM), given 2 min prior to ATP, significantly reduced the ATP-induced rise in [Ca²⁺]_i by 30%. This effect was blocked by α-bungarotoxin and did not depend on the presence of extracellular calcium.

Conclusions

Rat AM are equipped with modulatory nAChR with properties distinct from ionotropic nAChR mediating synaptic transmission in the nervous system. Their stimulation with nicotine dampens ATP-induced Ca²⁺-release from intracellular stores. Thus, the present study identifies the first acute receptor-mediated nicotinic effect on AM with anti-inflammatory potential.     

Gene-based microsatellites for cassava (Manihot esculenta Crantz): prevalence, polymorphisms, and cross-taxa utility

Background  

Cassava (Manihot esculenta Crantz), a starchy root crop grown in tropical and subtropical climates, is the sixth most important crop in the world after wheat, rice, maize, potato and barley. The repertoire of simple sequence repeat (SSR) markers for cassava is limited and warrants a need for a larger number of polymorphic SSRs for germplasm characterization and breeding applications.     

Analysis of the meiosis in the F_1 hybrids of Longiflorum × Asiatic(LA) of lilies(Lilium) using genomic in situ hybridization

Longiflorum and Asiatic lilies of the genus Lilium of the family Liliaceae are two important groups of modern lily cultivars.One of the main trends of lily breeding is to realize introgression between these groups.With cut style pollination and embryo rescue,distant hybrids between the two groups have been obtained.However,the F1 hybrids are highly sterile or some of them could produce a small number of 2n gametes,and their BC1 progenies are usually triploids.Dutch lily breeders have selected many cultivars...     

Population genetic structure and evolutionary history of Psammochloa villosa (Trin.) Bor (Poaceae) revealed by AFLP marker

Psammochloa villosa is an ecologically important desert grass that occurs in the Inner Mongolian Plateau where it is frequently the dominant species and is involved in sand stabilization and wind breaking. We sought to generate a preliminary demographic framework for P. villosa to support the future studies of this species, its conservation, and sustainable utilization. To accomplish this, we characterized the genetic diversity and structure of 210 individuals from 43 natural populations of P. villosa using amplified fragment length polymorphism (AFLP) markers. We obtained 1,728 well‐defined amplified bands from eight pairs of primers, of which 1,654 bands (95.7%) were polymorphic. Results obtained from the AFLPs suggested effective alleles among populations of 1.32, a Nei''s standard genetic distance value of 0.206, a Shannon index of 0.332, a coefficient of gene differentiation (G _ST) of 0.469, and a gene flow parameter (Nm) of 0.576. All these values indicate that there is abundant genetic diversity in P. villosa, but limited gene flow. An analysis of molecular variance (AMOVA) showed that genetic variation mainly exists within populations (64.2%), and we found that the most genetically similar populations were often not geographically adjacent. Thus, this suggests that the mechanisms of gene flow are surprisingly complex in this species and may occur over long distances. In addition, we predicted the distribution dynamics of P. villosa based on the spatial distribution modeling and found that its range has contracted continuously since the last interglacial period. We speculate that dry, cold climates have been critical in determining the geographic distribution of P. villosa during the Quaternary period. Our study provides new insights into the population genetics and evolutionary history of P. villosa in the Inner Mongolian Plateau and provides a resource that can be used to design in situ conservation actions and prioritize sustainable utilization.     

Irreversible Renal Damage after Transient Renin-Angiotensin System Stimulation: Involvement of an AT1-Receptor Mediated Immune Response

Transient activation of the renin-angiotensin system (RAS) induces irreversible renal damage causing sustained elevation in blood pressure (BP) in Cyp1a1-Ren2 transgenic rats. In our current study we hypothesized that activation of the AT₁-receptor (AT₁R) leads to a T-cell response causing irreversible impairment of renal function and hypertension. Cyp1a1-Ren2 rats harbor a construct for activation of the RAS by indole-3-carbinol (I3C). Rats were fed a I3C diet between 4–8 weeks of age to induce hypertension. Next, I3C was withdrawn and rats were followed-up for another 12 weeks. Additional groups received losartan (20 mg/kg/day) or hydralazine (100 mg/kg/day) treatment between 4–8 weeks. Rats were placed for 24h in metabolic cages before determining BP at week 8, 12 and 20. At these ages, subsets of animals were sacrificed and the presence of kidney T-cell subpopulations was investigated by immunohistochemistry and molecular marker analysis. The development of sustained hypertension was completely prevented by losartan, whereas hydralazine only caused a partial decrease in BP. Markers of renal damage: KIM-1 and osteopontin were highly expressed in urine and kidney samples of I3C-treated rats, even until 20 weeks of age. Additionally, renal expression of regulatory-T cells (Tregs) was highly increased in I3C-treated rats, whereas the expression of T-helper 1 (Th1) cells demonstrated a strong decrease. Losartan prevented these effects completely, whereas hydralazine was unable to affect these changes. In young Cyp1a1-Ren2 rats AT₁R activation leads to induction of an immune response, causing a shift from Th1-cells to Tregs, contributing to the development of irreversible renal damage and hypertension.     

Early Life Exposure to Famine and Colorectal Cancer Risk: A Role for Epigenetic Mechanisms

Background

Exposure to energy restriction during childhood and adolescence is associated with a lower risk of developing colorectal cancer (CRC). Epigenetic dysregulation during this critical period of growth and development may be a mechanism to explain such observations. Within the Netherlands Cohort Study on diet and cancer, we investigated the association between early life energy restriction and risk of subsequent CRC characterized by the (promoter) CpG island methylation phenotype (CIMP).

Methodology/Principal Findings

Information on diet and risk factors was collected by baseline questionnaire (n = 120,856). Three indicators of exposure were assessed: place of residence during the Hunger Winter (1944–45) and World War II years (1940–44), and father''s employment status during the Economic Depression (1932–40). Methylation specific PCR (MSP) on DNA from paraffin embedded tumor tissue was performed to determine CIMP status according to the Weisenberger markers. After 7.3 years of follow-up, 603 cases and 4631 sub-cohort members were available for analysis. Cox regression was used to calculate hazard ratios (HR) and 95% confidence intervals for CIMP+ (27.7%) and CIMP- (72.3%) tumors according to the three time periods of energy restriction, adjusted for age and gender. Individuals exposed to severe famine during the Hunger Winter had a decreased risk of developing a tumor characterized by CIMP compared to those not exposed (HR 0.65, 95%CI: 0.45–0.92). Further categorizing individuals by an index of ‘0–1’ ‘2–3’ or ‘4–7’ genes methylated in the promoter region suggested that exposure to the Hunger Winter was associated with the degree of promoter hypermethylation (‘0–1 genes methylated’ HR = 1.01, 95%CI:0.74–1.37; ‘2–3 genes methylated’ HR = 0.83, 95% CI:0.61–1.15; ‘4–7 genes methylated’ HR = 0.72, 95% CI:0.49–1.04). No associations were observed with respect to the Economic Depression and WWII years.

Conclusions

This is the first study indicating that exposure to a severe, transient environmental condition during adolescence and young adulthood may result in persistent epigenetic changes that later influence CRC development.     

Assessing the maternal origin in the polyploid complex of <Emphasis Type="Italic">Camellia reticulata</Emphasis> based on the chloroplast <Emphasis Type="Italic">rpl</Emphasis>16 intron sequences: implications for camellia cross breeding

Camellia reticulata is a well-known woody ornamental species endemic to Southwest China. It represents a polyploid complex with diploids, allotetraploids, and allohexaploids. The parentage of the allotetraploids and allohexaploids has been reported by genomic in situ hybridization, but the maternal parents still remain unknown. In this study, sequences of the chloroplast rpl16 intron of 105 cultivars of C. reticulata and 7 congeneric species were used to infer the maternal origin of the allopolyploids. The results showed that (1) the allotetraploids were derived from C. pitardii as the maternal parental species and the diploid C. reticulata as the paternal parental species; (2) the allohexaploid C. reticulata was derived from the allotetraploid C. reticulata as the maternal parent and C. saluenensis as the paternal parent; and (3) the C. reticulata cultivars were derived from hexaploid C. reticulata as the maternal parents. These results indicated that C. pitardii, the allotetraploid and allohexaploid C. reticulata may serve as good potential maternal parents for the cross breeding of Camellia.