The Scaling of Plant Height: A Comparison Among Major Plant Clades and Anatomical Grades

The scaling plant height h (m) with respect to stem diameterd (m) was determined for a total 610 species (mosses, n = 40;pteridophytes, n = 16; dicotyledonous herbs, n = 117; palms,n = 17; gymnosperms, n = 105; dicotyledonous trees, n = 315);axial length or mass vs. d was determined for the pteridophytePsilotum nudum ; and the scaling of critical buckling heighth_crit of gymnosperm and dicotyledonous trees was calculatedbased on the record trunk d and average Young's modulus E anddensity p of 33 wood species. The scaling exponents (based onleast squares and reduced major axis regressions;     

DIFFERENTIAL PRESERVATION OF PROTOPLASM IN FOSSIL ANGIOSPERM LEAF TISSUES

Examination of Miocene angiosperm leaf compressions from the Clarkia and Succor Creek localities of Idaho and Oregon reveals a characteristic and predictable pattern of protoplasmic deterioration. Remnants of chloroplasts are preserved in 63.9% of the 8,800 randomly selected cells, while mitochondria (18.6%) and nuclei (11.3%) are less commonly preserved. This pattern appears to be independent of the presumed environment of deposition associated with fossilization. Leaf tissues from sediments thought to be derived from shallow and deeper waters of the Miocene Clarkia lake (Chloro = 34.6%, Mito < 3%, Nuc < 1% and Chloro = 90.1%, Mito = 26%, Nuc = 4.3%, respectively) show similar patterns of ultrastructural preservation to leaves preserved in volcanic ash-fall deposits (Chloro = 80%, Mito = 45.4%, Nuc = 39.5%). Analyses of the data for the relative abundance of various organelles per cell (e.g., in living plants Chloro/Nuc = 250) in fossil tissues and referable modern taxa indicate that the chances of the observed preferential degradation of nuclei being the results of chance is <0.001. The data are interpreted to be evidence for the preferential preservation of chloroplasts and degeneration of nuclei. The pattern of protoplasmic degeneration, reconstructed from the frequencies of organelle preservation, is in contrast to that of the pattern observed in modern plant cell necrosis or senescence where nuclei are the most stable organelle and persist until the death of the cell. Preliminary data indicate that regimes of dehydration and compression may duplicate the pattern of protoplasmic degeneration observed in fossil plant cells.     

Irradiation to the immature brain attenuates neurogenesis and exacerbates subsequent hypoxic‐ischemic brain injury in the adult

Cranial radiotherapy is common in pediatric oncology. Our purpose was to investigate if irradiation (IR) to the immature brain would increase the susceptibility to hypoxic‐ischemic injury in adulthood. The left hemisphere of postnatal day 10 (P10) mice was irradiated with 8 Gy and subjected to hypoxia‐ischemia (HI) on P60. Brain injury, neurogenesis and inflammation were evaluated 30 days after HI. IR alone caused significant hemispheric tissue loss, or lack of growth (2.8 ± 0.42 mm³, p < 0.001). Tissue loss after HI (18.2 ± 5.8 mm³, p < 0.05) was synergistically increased if preceded by IR (32.0 ± 3.5 mm³, p < 0.05). Infarct volume (5.1 ± 1.6 mm³) nearly doubled if HI was preceded by IR (9.8 ± 1.2 mm³, p < 0.05). Pathological scoring revealed that IR aggravated hippocampal, cortical and striatal, but not thalamic, injury. Hippocampal neurogenesis decreased > 50% after IR but was unchanged by HI alone. The number of newly formed microglia was three times higher after IR + HI than after HI alone. In summary, IR to the immature brain produced long‐lasting changes, including decreased hippocampal neurogenesis, subsequently rendering the adult brain more susceptible to HI, resulting in larger infarcts, increased hemispheric tissue loss and more inflammation than in non‐irradiated brains.     

ELIXIR‐EXCELERATE: establishing Europe's data infrastructure for the life science research of the future

A new inter‐governmental research infrastructure, ELIXIR, aims to unify bioinformatics resources and life science data across Europe, thereby facilitating their mining and (re‐)use. Subject Categories: Computational Biology, Methods & Resources, S&S: Ethics

Creating knowledge by connecting and analysing large amounts of life science data is transforming our society, allowing us to start addressing major scientific and societal challenges, such as adaptation to climate change or pathogen outbreaks in an interconnected world. Modern biology is dependent on the generation, sharing and integrated analysis of digital data at scale. A deeper understanding of biological systems is now becoming possible thanks to breakthroughs in technologies that study life systematically at different scales, from molecules and single‐cell pathogens to complex animal or plant models and ecosystems as well as across temporal ranges spanning split‐second reactions to multi‐year clinical or agronomic trials, and beyond. The key to analyse and leverage this complex, fragmented and geographically dispersed life science data landscape is to ensure it is easy to find and reuse by researchers. This article comments on ELIXIR, an international organisation that brings together bioinformatics researchers and life science resources across Europe and integrates them into a single federated infrastructure.     

Simulation of organic shape: The roles of phenomenology and mechanism

Models adducing mechanisms of morphogenesis from observations of geometric similarity between mathematical and natural forms must be rigorously challenged by extensive direct observations of the process being modeled. © 1994 Wiley-Liss, Inc.     

Chemotaxonomy of some problematic palaeozoic plants

Chemical data are given on the remains of nine fossil genera ranging from Precambrian to Carboniferous in age (Chuaria, Sporangites, Taeniocrada, Orestovia, Parka, Protosalvinia, Spongiophyton, Solenites, Botryococcus). It is suggested that such chemical data are useful additional criteria in making taxonomic assignments in palaeontology. Analyses indicate a high level of organic chemical diversity, although the original composition has evidently been altered by temperature and pressure over a long period of time. The labile chemical constituents are retained within a more chemically inert carbon matrix, which shows a progressive alteration of the ratios of C, N, O and H with respect relative age, similar to that seen in the coalification process.The chemical composition of Sporangites specimens is more suggestive of an animal rather than a plant affinity; it is here suggested that this genus represents in part the remains of some animal egg test. Hydrolytic products of Solenites and Taeniocrada indicate the presence of aliphatic hydroxy acids suggesting the presence of cutin and suberin. The chemical compositions of Orestovia, Parka, Protosalvinia, Spongiophyton and Botryococcus are interpreted as being consistent with an algal rather than a vascular plant affinity. Evidence for extreme diagenesis of the acritarch-like Chuaria greatly limits chemotaxonomic consideration. The possible role of thermal and biotic-thermal degradation patterns seen in palaeochemistry is discussed.     

Changes in the factor of safety within the superstructure of a dicot tree

The objective of this study was to determine whether the factor of safety for mechanical stability varied among stems differing in size and age within the superstructure of a large dicot tree. Two factors of safety were selected for study: the quotient of the critical buckling height and the actual length of stems, Hcrit/L, and the quotient of the modulus of rupture (the force per unit area required to break a stem) and the working stress (the force per unit area resulting from the biomass measured distal to a stem), M_R/σ_w. These two dimensionless safety factors were determined for a total of 420 shoot segments comprising much of the aboveground biomass of a Robinia pseudoacacia (Fabaceae) tree measuring 18.7 m in height and 1347 kg in mass, and 0.46 m in diameter (40 yr old) at 1.2 m from the ground. An S-shaped trend was observed when each of the two factors of safety was plotted as a function of stem age. Each factor decreased from a local maximum for the most distal (peripheral) stems in the canopy to a local minimum value for stems ∼10 yr old; each factor increased again to another local maximum for stems 11–18 yr old, and then decreased steadily toward the base of the trunk. This trend was the result of the allometric relationships among stem diameter, length, biomass, and material properties (stiffness and strength) with respect to stem age. Although they were disproportionately more slender than their older counterparts, peripheral stems were sufficiently stiff and strong to sustain the stresses resulting from their weight and that of foliage without deflecting under these loads, yet they were sufficiently flexible to easily bend and thereby presumably provide a mechanism to reduce the drag forces acting on the entire tree. In contrast, the internally imposed mechanical forces acting on progressively older stems increased at a greater rate than the observed rate of increase in stem stiffness, strength, or diameter. The probability of mechanical failure, which must be considered from a demographic perspective (i.e., an age-dependent phenomenon), thus increased from older branches to the base of the trunk. Reports of similar allometric trends based on interspecific comparisons among diverse dicot species comply with the allometry observed for the R. pseudoacacia tree and suggest that the S-shaped trend for the factor of safety holds for stems differing in age drawn from individual trees and for the trunks of conspecifics differing in age drawn from a dense population.     

Relationships among the basal lineages of Noctuidae (Lepidoptera,Noctuoidea) based on eight gene regions

In this study, we clarify the relationships between the basal lineages in the moth family Noctuidae using DNA sequence data from eight independent gene regions. Data matrices (6.4 kbp) are analysed using parsimony and model‐based methods (maximum likelihood and Bayesian inference). Our results support the family Noctuidae as a monophyletic group in which most subfamilies have hindwing vein M2 reduced or absent. Our phylogenetic hypothesis suggests that in the Noctuidae, the plesiomorphic condition is that in which vein M2 arises about one‐third of the way up the discocellular vein between the origins of M1 and M3, mainly parallel to M3, and is of thickness similar to vein M3. Most Noctuidae lineages possess an apomorphic (derived) condition in which hindwing vein M2 is markedly reduced or totally absent, so that the cubital vein appears to be three‐branched and these lineages are hence referred to as ‘trifine’. However, Noctuidae also include a number of lineages in which vein M2 is unreduced, or only slightly reduced, and these are more problematic for morphological association with the family Noctuidae. Our results also show that the subfamily Acronictinae is not closely related to Pantheinae, but instead shows a closer association with Amphipyrinae. Among the major lineages of Noctuidae, we postulate a general trend, with numerous exceptions, in larval host plants from woody plants in the basal groups towards herb feeding in derived groups. Similarly, the major radiations of monocot‐feeding groups within the family Noctuidae are in the higher trifines. The following taxonomic changes are proposed: Thiacidinae, syn. nov., a junior synonym of Pantheinae, and Dyopsinae, stat. nov., are reinstated as a subfamily.