An investigation of paedomorphic secondary xylem and secondary woodiness in Xanthorhiza simplicissima, Coreopsis gigantea, and Mahonia bealei

The stem and secondary xylem anatomy of Xanthorhiza simplicissima, Coreopsis gigantea, and Mahonia bealei are described and characterized in the study. One focus of the study was to determine the degree of paedomorphosis in the secondary xylem of the three plants. Another goal was to assess their woodiness in a phylogenetic context to determine how their woodiness was derived (whether from woody or nonwoody ancestors). Quantitative measurements and observations from slides and macerations were done using light microscopy and confocal microscopy. The secondary xylem of all three species has a degree of paedomorphosis. Coreopsis gigantea has the greatest degree. It possesses vessel elements whose length either decreases or remains the same across the xylem, vessels with pseudoscalariform lateral wall pitting and simple perforation plates, raylessness, libriform fibers, and abundant xylary parenchyma. Xanthorhiza simplicissima has an intermediate degree, possessing decreasing vessel element lengths, libriform fibers, and upright ray cells. Mahonia bealei has only the paedomorphic characteristics of stable vessel element lengths and libriform fibers. Phylogenetic analysis indicates the species are secondarily woody. A major conclusion is that the degree of paedomorphosis reflects the species release from mechanical requirements

Identification of windbreaks in Kansas using object-based image analysis, GIS techniques and field survey

Windbreaks are valuable resources in conserving soils and providing crop protection in Great Plains states in the US. Currently, Kansas has no up-to date inventory of windbreaks. The goal of this project was to assist foresters with future windbreak renovation planning and reporting, by outlining a series of semi-automated digital image processing methods that rapidly identify windbreak locations. There were two specific objectives of this research. First, to develop semi-automated methods to identify the location of windbreaks in Kansas, this can be applied to other regions in Kansas and the Great Plains. We used a remote sensing technique known as object-based image analysis (OBIA) to classify windbreaks visible in the color aerial imagery of National Agriculture Imagery Program. We also combined GIS techniques and field survey to complement OBIA in generating windbreak inventory. The techniques successfully located more than 4500, windbreaks covering an approximate area of 2500, hectares in 14 Kansas counties. The second purpose of this research is to determine how well the results of the automated classification schemes match with other available windbreak data and the selected sample collected in the field. The overall accuracy of OBIA method was 58.97 %. OBIA combined with ‘heads up’ digitizing and field survey method yielded better result in identifying and locating windbreaks in the studied counties with overall accuracy of 96 %

Paedomorphosis, Secondary Woodiness, and Insular Woodiness in Plants.

The related concepts of paedomorphosis in the secondary xylem, insular woodiness, and secondary woodiness are reviewed and evaluated in order to clearly distinguish the phenomenon involved, and provide a firm foundation for future research in this area. The theory of paedomorphosis refers to the occurrence of certain juvenile xylem characteristics, such as scalariform perforation plates and lateral wall pitting, in the secondary xylem of shrubby, suffrutescent, pachycaulous, and lianoid growth forms. Paedomorphic characteristics are often found in insular woody species, a fact that has caused paedomorphosis to be associated with secondary woodiness. The anatomy of the secondary xylem in Xanthorhiza simplicissima (Ranunculaceae), Coreopsis gigantea (Asteraceae), and Mahonia bealei (Berberidaceae) is described in order to provide specific data for discussion. These species serve as test cases for the presence of paedomorphosis, and the evolution of secondary woodiness. The secondary xylem of all three species was found to have a degree of paedomorphosis, with Coreopsis having the greatest number of paedomorphic characteristics, Xanthorhiza having an intermediate number, and Mahonia possessing only a single characteristic. Plotting the occurrence of the character states woody and nonwoody on phylogenetic trees containing these taxa shows that Coreopsis is secondarily woody, while the ancestry of the other two species cannot be unambiguously established. These results must, however, be considered preliminary as the occurrence of secondary growth in many “herbaceous” plants often goes unreported. Although paedomorphosis is often associated with secondary woodiness, there are examples of paedomorphic wood in primitively woody taxa. One conclusion is that the degree of paedomorphosis may be a better indicator of the mechanical requirements of the shoot then of its evolutionary history

Injured adult motor and sensory axons regenerate into appropriate organotypic domains of neural progenitor grafts.

Neural progenitor cell (NPC) transplantation has high therapeutic potential in neurological disorders. Functional restoration may depend on the formation of reciprocal connections between host and graft. While it has been reported that axons extending out of neural grafts in the brain form contacts onto phenotypically appropriate host target regions, it is not known whether adult, injured host axons regenerating into NPC grafts also form appropriate connections. We report that spinal cord NPCs grafted into the injured adult rat spinal cord self-assemble organotypic, dorsal horn-like domains. These clusters are extensively innervated by regenerating adult host sensory axons and are avoided by corticospinal axons. Moreover, host axon regeneration into grafts increases significantly after enrichment with appropriate neuronal targets. Together, these findings demonstrate that injured adult axons retain the ability to recognize appropriate targets and avoid inappropriate targets within neural progenitor grafts, suggesting that restoration of complex circuitry after SCI may be achievable

Pausing controls branching between productive and non-productive pathways during initial transcription in bacteria

Transcription in bacteria is controlled by multiple molecular mechanisms that precisely regulate gene expression. It has been recently shown that initial RNA synthesis by the bacterial RNA polymerase (RNAP) is interrupted by pauses; however, the pausing determinants and the relationship of pausing with productive and abortive RNA synthesis remain poorly understood. Using single-molecule FRET and biochemical analysis, here we show that the pause encountered by RNAP after the synthesis of a 6-nt RNA (ITC6) renders the promoter escape strongly dependent on the NTP concentration. Mechanistically, the paused ITC6 acts as a checkpoint that directs RNAP to one of three competing pathways: productive transcription, abortive RNA release, or a new unscrunching/scrunching pathway. The cyclic unscrunching/scrunching of the promoter generates a long-lived, RNA-bound paused state; the abortive RNA release and DNA unscrunching are thus not as tightly linked as previously thought. Finally, our new model couples the pausing with the abortive and productive outcomes of initial transcription

Age, Health and Life Satisfaction Among Older Europeans

In this paper we investigate how age affects the self-reported level of life satisfaction among the elderly in Europe. By using a vignette approach, we find evidence that age influences life satisfaction through two counterbalancing channels. On the one hand, controlling for the effects of all other variables, the own perceived level of life satisfaction increases with age. On the other hand, given the same true level of life satisfaction, older respondents are more likely to rank themselves as “dissatisfied” with their life than younger individuals. Detrimental health conditions and physical limitations play a crucial role in explaining scale biases in the reporting style of older individuals