Joint-tree model and the maximum genus of graphs

The vertex v of a graph G is called a 1-critical-vertex for the maximum genus of the graph, or for simplicity called 1-critical-vertex, if G-v is a connected graph and {\deg}M(G - v) = {\deg}M(G) - 1. In this paper, through the joint-tree model, we obtained some types of 1-critical-vertex, and get the upper embeddability of the Spiral Snm

The maximum genus of graphs with diameter three

AbstractThis paper shows that if G is a simple graph with diameter three then G is up-embeddable unless G is either a Δ2-graph (Fig. 1) or a Δ3-graph (Fig. 2) with ξ(G) = 2, i.e., the maximum genus γM(G) = (β(G) − 2)/2

Vertex Splitting and Upper Embeddable Graphs

The weak minor G of a graph G is the graph obtained from G by a sequence of edge-contraction operations on G. A weak-minor-closed family of upper embeddable graphs is a set G of upper embeddable graphs that for each graph G in G, every weak minor of G is also in G. Up to now, there are few results providing the necessary and sufficient conditions for characterizing upper embeddability of graphs. In this paper, we studied the relation between the vertex splitting operation and the upper embeddability of graphs; provided not only a necessary and sufficient condition for characterizing upper embeddability of graphs, but also a way to construct weak-minor-closed family of upper embeddable graphs from the bouquet of circles; extended a result in J: Graph Theory obtained by L. Nebesk{\P}y. In addition, the algorithm complex of determining the upper embeddability of a graph can be reduced much by the results obtained in this paper

GPCR-like signaling mediated by smoothened contributes to acquired chemoresistance through activating Gli

BACKGROUND: Smoothened (Smo), which possesses a structural similarity with classic G-protein coupled receptors (GPCR), is the most important molecular target in Hedgehog (Hh) signaling system for developing anticancer drugs; however, whether Smo may transmit GPCR-like signaling to activate the canonical transcriptional factor Gli of Hh signaling system and consequently to be involved in the Gli-dependent biological events remains controversial. RESULTS: In this study, using the acquired chemoresistant cancer cell lines and their respective parental cells, we found that Smo may activate Gli through Gαi, Gβγ-JNK signaling axis, thereby promoting the Gli-dependent acquired chemoresistance. These observations were further complementarily strengthened by data obtained from chemosensitive cancer cells with artificially elevated Hh pathway activity. CONCLUSIONS: Hence, our data demonstrate that GPCR-like signaling mediated by Smo contributes to the acquired chemoresistance through activating the canonical Hh transcriptional factor Gli; therefore improving our knowledge of the nature of the signal transduction of Smo and the molecular mechanisms responsible for the acquired chemoresistance maintained by Hh pathway. Moreover, our data that JNK after activated by Smo-Gβγ signaling axis may stimulate the Gli activity and consequently promotes acquired chemoresistance expose a promising and potential target for developing anti-cancer drugs aimed at Hh pathway and for combating the acquired resistance raised by using of anti-cancer drugs targeting Smo

Evaluation of the effects of forest management strategies on carbon sequestration in evergreen broad-leaved (Phoebe bournei) plantation forests using FORECAST ecosystem model

In the context of global climate change, it is critical to study how different forest management practices affect forest carbon sequestration. This is especially important for forest managers and policy makers who will have to design and implement appropriate mitigation and adaptation strategies. Previous research has focused on coniferous plantations with rare examination of plantations of evergreen broadleaved species. Phoebe bournei (Hemsley) Yang, as one of the representative species of subtropical evergreen broadleaf forests in Asia, has a unique potential to increase forest carbon sink. In this study, field data were combined with the forest ecosystem management model FORECAST to estimate the impacts of different forest management strategies (combinations of planting densities from 1000 to 4000 trees ha-1, rotation lengths from 20 to 80 years, and different harvesting intensities: stem-only, whole-tree and complete-tree) on carbon sequestration of Phoebe bournei plantations in south-eastern China. Field and previously published data were used to calibrate the model for stand biomass pools accumulation, stand density and mortality, light response curves, photosynthetic efficiency, and data on soil nutrient pools, for three different site conditions. The results showed that the most suitable planting density to maximize carbon sequestration in Phoebe bournei plantations is 2000-3000 trees ha-1. Long rotations (80 years) are better than shorter rotations (20 or 30 years) for the long-term maintenance of site productivity, though the recommended rotation length for maximizing carbon sequestration and maintaining forest productivity is 40-60 years. As for harvesting intensity, stem-only harvesting is the most suitable strategy to manage for carbon sequestration when maintaining long-term site productivity, with whole-tree and complete-tree harvesting constituting less optimal options. Our modelling exercise indicates that Phoebe bournei plantations have great potential for carbon sequestration if they are managed under sustainable and ecologically-based strategies. Given that forests are important in the global carbon cycle, it is recommended that afforestation efforts in relevant sub-tropical regions use appropriate broad-leaved species that can help resolve ecological and socio-economic challenge

Effect of leaf phenology and morphology on the coordination between stomatal and minor vein densities

Leaf phenology (evergreen vs. deciduous) and morphology (simple vs. compound) are known to be related to water use strategies in tree species and critical adaptation to certain climatic conditions. However, the effect of these two traits and their interactions on the coordination between minor vein density (MVD) and stomatal density (SD) remains unclear. In this study, we examined the leaves of 108 tree species from plots in a primary subtropical forest in southern China, including tree species with different leaf morphologies and phenologies. We assessed nine leaf water-related functional traits for all species, including MVD, SD, leaf area (LA), minor vein thickness (MVT), and stomatal length (SL). The results showed no significant differences in mean LA and SD between either functional group (simple vs. compound and evergreen vs. deciduous). However, deciduous trees displayed a significantly higher mean MVD compared to evergreen trees. Similarly, compound-leaved trees have a higher (marginally significant) MVD than simple-leaved trees. Furthermore, we found that leaf morphology and phenology have significantly interactive effects on SL, and the compound-leafed deciduous trees exhibited the largest average SL among the four groups. There were significant correlations between the MVD and SD in all different tree groups; however, the slopes and interceptions differed within both morphology and phenology. Our results indicate that MVD, rather than SD, may be the more flexible structure for supporting the coordination between leaf water supply and demand in different leaf morphologies and phenologies. The results of the present study provide mechanistic understandings of the functional advantages of different leaf types, which may involve species fitness in community assembly and divergent responses to climate changes

Face Size and the Maximum Genus of a Graph 1. Simple Graphs

AbstractThis paper shows that a simple graph which can be cellularly embedded on some closed surface in such a way that the size of each face does not exceed 7 is upper embeddable. This settles one of two conjectures posed by Nedela and Škoviera (1990, in “Topics in Combinatorics and Graph Theory,” pp. 519–529, Physica Verlag, Heidelberg). The other conjecture will be proved in a sequel to this paper

The complete mitochondrial genome of natural hybridization of Anser albifrons and Anser fabalisthe (Anser albifrons × Anser fabalis)

Hybridization between birds in wild nature is an interesting phenomenon in the wild, but not common in waterfowl in the wild. In this study, we report the complete mtDNA of the natural hybridization bird between Anser albifrons and Anser fabalis. The complete mtDNA of the hybridization is 16,740 bp in length, contains the typical set of 37 genes, including 13 PCGs, two rRNAs, 22 tRNAs, and a 1177 bp CR. In the 13 PCGs, ATG is generally as the start codon, TAA is the most frequent stop codon, one of three, TAA, TAG, and T-, commonly observed. All tRNAs can be folded into canonical cloverleaf secondary structures except for tRNASer (AGY) and tRNALeu (CUN) missing the “DHU” arm. The new mtDNA sequence contains 12S rRNA and 16S rRNA of rRNAs, separated with tRNAval. The CR is 1177 bp in length, located between tRNAGlu and tRNAPhe. Our phylogenetic trees suggest the hybridization has a close genetic relationship among Anser species

Habitat Significantly Affect CWD Decomposition but No Home-Field Advantage of the Decomposition Found in a Subtropical Forest, China

The home-field advantage (HFA) effect has been reported to occur in coarse woody debris (CWD) and litter. It is thought that the HFA effect may be due to the specialization of decomposers in their original habitats. However, the relative contribution of microorganisms, particularly fungi and bacteria, to deadwood decomposition is unclear because of differences in their functional at-tributes and carbon requirements, and the microorganisms that drive the HFA effect of deadwood are also unclear. Here, we analysed a dataset of microbial PLFA and substrate properties collected from the soil and CWD of two subtropical trees, Cryptomeria japonica and Platycarya strobilacea, from forests dominated by one or the other of the two species, with both species present in the forests. Our results showed that habitat and tree types all significantly affected CWD respiration rates, the CWD respiration rates were significantly higher in the deciduous broadleaf forests (DBF) than in the coniferous forest (CF) regardless of tree types, but no a large HFA of CWD decomposition found (HFA index was 4.75). Most biomarkers indicated bacteria and fungi were more abundant in the DBF than in the CF, and the concentration of microbial PLFAs was higher in Platycarya strobilacea than in Cryptomeria japonica. In addition, the relative abundance of fungi and soil B/F were remarkably positively correlated with CWD respiration, indicating that fungi may be the primary decomposers of CWD. In conclusion, our work highlights the importance of interactions between the three primary drivers (environment, substrate quality and microbes) on CWD decomposition