Seasonal variation in leaf chemistry of the coast live oak Quercus agrifolia and implications for the California oak moth Phryganidia californica

Summary The perennial foliage of the California coast live oak (Quercus agrifolia Nee) permits herbivores to feed on this oak species throughout the year. Patterns of herbivory for a two-year period on Q. agrifolia were observed in relation to seasonal and age-related changes in the nutritional and defensive characteristics of leaves. Nitrogen and phosphorus contents were higher in new leaves compared to mature foliage. Structural compounds (e.g., cellulose) in leaves rapidly increased with age. Concentrations of tatal phenolics (Folin-Denis) and astringency were higher in new foliage, and concentrations of condensed tannins gradually increased as the leaves matured. Peaks of herbivore damage were observed in June and in September–October, and were caused by outbreaks of the California oak moth (Phryganidia californica). P. californica, a bivoltine oak specialist, exhibited feeding preferences in June for old leaves over emerging leaves, and showed no preferences for leaf classes in September. These results suggest that P. californica is adapted to survive on nutritionally poor foliage and to circumvent quantitative defenses such as condensed tannins.     

ToolBox: Live Imaging of intracellular organelle transport in induced pluripotent stem cell‐derived neurons

Induced pluripotent stem cells (iPSCs) hold promise to revolutionize studies of intracellular transport in live human neurons and to shed new light on the role of dysfunctional transport in neurodegenerative disorders. Here, we describe an approach for live imaging of axonal and dendritic transport in iPSC‐derived cortical neurons. We use transfection and transient expression of genetically‐encoded fluorescent markers to characterize the motility of Rab‐positive vesicles, including early, late and recycling endosomes, as well as autophagosomes and mitochondria in iPSC‐derived neurons. Comparing transport parameters of these organelles with data from primary rat hippocampal neurons, we uncover remarkable similarities. In addition, we generated lysosomal‐associated membrane protein 1 (LAMP1)‐enhanced green fluorescent protein (EGFP) knock‐in iPSCs and show that knock‐in neurons can be used to study the transport of endogenously labeled vesicles, as a parallel approach to the transient overexpression of fluorescently labeled organelle markers.     

International principles and standards for native seeds in ecological restoration

The growing demand for native seeds in ecological restoration and rehabilitation, whether for mining, forest, or ecosystem restoration, has resulted in a major global industry in the sourcing, supply, and sale of native seeds. However, there are no international guidance documents for ensuring that native seeds have the same standards of quality assurance that are regular practice in the crop and horticultural industries. Using the International Principles and Standards for the Practice of Ecological Restoration as a foundation document, we provide for the first time a synthesis of general practices in the native seed supply chain to derive the Principles and Standards for Native Seeds in Ecological Restoration (“Standards”). These practices and the underpinning science provide the basis for developing quality measures and guidance statements that are adaptable at the local, biome, or national scale. Importantly, these Standards define what is considered native seed in ecological restoration and highlight the differences between native seeds versus seeds of improved genetics. Seed testing approaches are provided within a logical framework that outline the many different dormancy states in native seed that can confound restoration outcomes. A “pro‐forma” template for a production label is included as a practical tool that can be customized for local needs and to standardize reporting to end‐users on the level of seed quality and germinability to be expected in a native seed batch. These Standards are not intended to be mandatory; however, the guidance statements provide the foundation upon which regulatory approaches can be developed by constituencies and jurisdictions.     

Resprouting Ability of Dry Forest Tree Species after Disturbance Does Not Relate to Propagation Possibility by Stem and Root Cuttings

Tropical dry forest tree species are recognized for their high resprouting ability after disturbance. We tested whether species that commonly produce root and stem suckers can be propagated by large stem and root cuttings, a useful method for landscape restoration programs. We performed four experiments: (1) In a greenhouse, we tested the propagation of six species using large stem cuttings collected from early successional sites. We used the following treatments: (i) dry season collection and planting; (ii) dry season collection, storage in humid soil, and wet season planting; (iii) wet season collection and planting; and (iv) wet season collection and planting after treatment with commercial NAA auxin. (2) Stem cuttings of Myracrodruon urundeuva were planted in a pasture during the rainy season after either NAA, IBA, or no auxin treatment. (3) As a control experiment, we also planted cuttings of Spondias mombin, a species known for successfully regenerating from cuttings. (4) Root cuttings of six species were collected in recently plowed pastures and planted in the greenhouse with and without treatment with NAA auxin. No root cuttings rooted. Only M. urundeuva and Astronium fraxinifolium stem cuttings rooted. Maximum success was obtained for stem cuttings collected and planted in the dry season (23%). Only 13% of M. urundeuva had sprouted by the 15th month of the field experiment. As a result, large cuttings are not recommended for propagation of the studied species. Future studies should include development of suitable methods of root harvesting and prospection of traditional knowledge for species selection.     

Growth Response of Coyote Willow (Salix exigua) Cuttings in Relation to Alluvial Soil Texture and Water Availability

A common approach to re‐establishing cottonwood–willow habitat along regulated rivers is through installing dormant, rootless cuttings, yet there is little published information exploring floodplain characteristics that optimize growth of southwestern riparian willows planted in this manner. The goal of this project was to evaluate relationships between growth attributes of Salix exigua and soil texture and soil water availability. Monitoring plots were established in five willow swales planted with dormant S. exigua cuttings along the banks of the Middle Rio Grande in central New Mexico. Data analysis revealed significantly higher aerial cover, height, and stem density for S. exigua plants installed in plots with intermediate levels (15–25%) of fine textured soils distributed through the soil profile. Similar relationships were found in relation to soil water availability. Regression analysis of percent fines and available water at different depth increments provided limited explanation of variability in willow growth attributes at different plots. Findings indicate that S. exigua plants established from cuttings can achieve heights and aerial cover values similar to naturally established willow bars if the floodplain soil profile contains intermediate levels of fine textured soils and the maximum depth to groundwater is within 1.5 m of the ground surface. Where sites are dominated by coarse sand, S. exigua growth may be improved if maximum depth to groundwater is within 1 m of the ground surface.     

Rapid proliferation of daughter cells lacking particular chromosomes due to multipolar mitosis promotes clonal evolution in colorectal cancer cells

Aneuploidy and chromosome instability (CIN) are hallmarks of the vast majority of solid tumors. However, the origins of aneuploid cells are unknown. The aim of this study is to improve our understanding of how aneuploidy and/or CIN arise and of karyotype evolution in cancer cells. By using fluorescence in situ hybridization (FISH) on cells after long-term live cell imaging, we demonstrated that most (> 90%) of the newly generated aneuploid cells resulted from multipolar divisions. Multipolar division occurred in mononucleated and binucleated parental cells, resulting in variation of chromosome compositions in daughter cells. These karyotypes can have the same chromosome number as their mother clone or lack a copy of certain chromosomes. Interestingly, daughter cells that lost a chromosome were observed to survive and form clones with shorter cell cycle duration. In our model of cancer cell evolution, the rapid proliferation of daughter cells from multipolar mitosis promotes colonal evolution in colorectal cancer cells.     

The Slice Culture Method for Following Development of Tooth Germs In Explant Culture

Explant culture allows manipulation of developing organs at specific time points and is therefore an important method for the developmental biologist. For many organs it is difficult to access developing tissue to allow monitoring during ex vivo culture. The slice culture method allows access to tissue so that morphogenetic movements can be followed and specific cell populations can be targeted for manipulation or lineage tracing.In this paper we describe a method of slice culture that has been very successful for culture of tooth germs in a range of species. The method provides excellent access to the tooth germs, which develop at a similar rate to that observed in vivo, surrounded by the other jaw tissues. This allows tissue interactions between the tooth and surrounding tissue to be monitored. Although this paper concentrates on tooth germs, the same protocol can be applied to follow development of a number of other organs, such as salivary glands, Meckel''s cartilage, nasal glands, tongue, and ear.