The Kreweras complementation map is an anti-isomorphism on the lattice of noncrossing partitions. We consider an analogous operation for plane trees motivated by the molecular biology problem of RNA folding. In this context, we explicitly count the orbits of Kreweras’ map according to their length as the number of appropriate symmetry classes of trees in the plane. These new enumeration results...

The Wiener index of a graph is the sum of the distances between all pairs of vertices, it has been one of the main descriptors that correlate a chemical compound’s molecular graph with experimentally gathered data regarding the compound’s characteristics. In [1], the tree that minimizes the Wiener index among trees of given maximal degree is studied. We characterize trees that achieve the maxim...

In order to investigate the seasonal changes and the possible role of the free polyamines in the leaves and stems on the alternate bearing habit of the ‘Kinnow’ mandarin (Citrus reticulata Blanco) trees, a comparative study was conducted to analyze the levels of free polyamines  (putrescine, spermidine and spermine) in the leaves and stems tissues of “on” and &ldquo...

In this study, we report some endophytic fungi isolated from twigs of Quercus brantii in Dena region of Kohgiluyeh and Boyer-Ahmad province. The twigs were sampled from trees which had basidiocarps of the invasive basidiomycetous polypore fungus Inonotus krawtzewii on their trunk. Altogether, ca. 40 pure isolates were obtained. The ITS sequences were obtained for 16 isolates, and their phylogen...

Many methods for inferring species trees from gene trees have been developed when incongruence among gene trees is due to incomplete lineage sorting. A method called STAR (Liu et al, 2009), assigns values to nodes in gene trees based only on topological information and uses the average value of the most recent common ancestor node for each pair of taxa to construct a distance matrix which is th...

The influence of mechanical bending or flexing trees, due primarily to wind, on tree growth and development has been observed reported for hundreds years. This response was defined as the thigmomorphogenetic in 1973. In general, trees other plants is a reduction extension/height growth, increase radial increased allocation from above-ground below-ground tissues accompanied by changes biomechani...

Glutathione S-transferases (GST) detoxify many electrophilic xenobiotics, including several volatile organic compounds and pesticides. The GST activity for the conjugation of several xenobiotic substances was isolated from needles of Norway spruce (Picea abies L. Karst.) trees from a forest decline stand in the northern alps. Trees that exhibited different degrees of damage were selected from s...

In this paper, we provide a method to accelerate the power of splicing systems. We introduce the splicing systems on trees to be built as partially annealed single strands, that is a quite similar notion and a natural extension of splicing systems on strings. Trees are a common and useful data structure in computer science and have a biological counterpart such as molecular sequences with secon...