Increased Atmospheric SO2 Detected from Changes in Leaf Physiognomy across the Triassic–Jurassic Boundary Interval of East Greenland

The Triassic–Jurassic boundary (Tr–J; ∼201 Ma) is marked by a doubling in the concentration of atmospheric CO₂, rising temperatures, and ecosystem instability. This appears to have been driven by a major perturbation in the global carbon cycle due to massive volcanism in the Central Atlantic Magmatic Province. It is hypothesized that this volcanism also likely delivered sulphur dioxide (SO₂) to the atmosphere. The role that SO₂ may have played in leading to ecosystem instability at the time has not received much attention. To date, little direct evidence has been presented from the fossil record capable of implicating SO₂ as a cause of plant extinctions at this time. In order to address this, we performed a physiognomic leaf analysis on well-preserved fossil leaves, including Ginkgoales, bennettites, and conifers from nine plant beds that span the Tr–J boundary at Astartekløft, East Greenland. The physiognomic responses of fossil taxa were compared to the leaf size and shape variations observed in nearest living equivalent taxa exposed to simulated palaeoatmospheric treatments in controlled environment chambers. The modern taxa showed a statistically significant increase in leaf roundness when fumigated with SO₂. A similar increase in leaf roundness was also observed in the Tr–J fossil taxa immediately prior to a sudden decrease in their relative abundances at Astartekløft. This research reveals that increases in atmospheric SO₂ can likely be traced in the fossil record by analyzing physiognomic changes in fossil leaves. A pattern of relative abundance decline following increased leaf roundness for all six fossil taxa investigated supports the hypothesis that SO₂ had a significant role in Tr–J plant extinctions. This finding highlights that the role of SO₂ in plant biodiversity declines across other major geological boundaries coinciding with global scale volcanism should be further explored using leaf physiognomy.     

Patch assessment in foraging flocks of European starlings: evidence for the use of public information

A field experiment was carried out to determine whether group-foragingstarlings (Sturnus vulgaris) use public information to helpthem estimate the quality of an artificial resource patch anddepart accordingly. Three kinds of information are potentiallyavailable in a group: patch-sample information, pre-harvestinformation, and public information. These three types of informationcan be combined into four patch assessment strategies: (1) patch-samplealone; (2) patch-sample and pre-harvest; (3) patch-sample andpublic; and (4) patch-sample, pre-harvest, and public. Dependingon the foraging environment we presented to the starlings, eachassessment strategy made a unique set of predictions concerningthe patch departure decisions of pairs of birds based on differencesin their foraging success. The environment was manipulated intwo ways: by altering the variability in patch quality and bychanging compatibility, the ease with which individual birdscould simultaneously acquire both patch-sample and public information.Our observations on patch persistence and departure order demonstratethat the starlings used a combination of patch-sample and publicinformation, but not pre-harvest information, to estimate thequality of the experimental patch. Moreover, our results suggestthat starlings use public information only when it is easilyavailable and ignore it under incompatible conditions. Thisstudy provides the first evidence of public information usein a patch assessment problem.     

Activation of CD74 inhibits migration of human mesenchymal stem cells

Therapeutic administration of mesenchymal stem cells (MSCs) by systemic delivery utilizes the innate ability of the cells to home to damaged tissues, but it can be an inefficient process due to a limited knowledge of cellular cues that regulate migration and homing. Our lab recently discovered that a potent pro-inflammatory cytokine, macrophage migration inhibitory factor (MIF), inhibits MSC migration. Because MIF may act on multiple cellular targets, an activating antibody (CD74Ab) was employed in this study to examine the effect of one MIF receptor, CD74 (major histocompatibility complex class II-associated invariant chain), on MSC motility. CD74 activation inhibits in a dose-dependent manner up to 90% of in vitro migration of MSCs at 40 μg/ml CD74Ab (p?<?0.001), with consistent effects observed among three MSC donor preparations. A blocking peptide from the C-terminus of CD74 eliminates the effect of CD74Ab on MSCs. This suggests that MIF may act on MSCs, at least in part, through CD74. Late-passage MSCs exhibit less chemokinesis than those at passage 2. However, MSCs remain responsive to CD74 activation during ex vivo expansion: MSC migration is inhibited ～2-fold in the presence of 5 µg/ml CD74Ab at passage 9 vs. ～3-fold at passage 2 (p?<?0.001). Consistent with this result, there were no significant differences in CD74 expression at all tested passages or after CD74Ab exposure. Targeting CD74 to regulate migration and homing potentially may be a useful strategy to improve the efficacy of a variety of MSC therapies, including those that require ex vivo expansion.     

Life‐history constraints in grassland plant species: a growth‐defence trade‐off is the norm

Plant growth can be limited by resource acquisition and defence against consumers, leading to contrasting trade‐off possibilities. The competition‐defence hypothesis posits a trade‐off between competitive ability and defence against enemies (e.g. herbivores and pathogens). The growth‐defence hypothesis suggests that strong competitors for nutrients are also defended against enemies, at a cost to growth rate. We tested these hypotheses using observations of 706 plant populations of over 500 species before and following identical fertilisation and fencing treatments at 39 grassland sites worldwide. Strong positive covariance in species responses to both treatments provided support for a growth‐defence trade‐off: populations that increased with the removal of nutrient limitation (poor competitors) also increased following removal of consumers. This result held globally across 4 years within plant life‐history groups and within the majority of individual sites. Thus, a growth‐defence trade‐off appears to be the norm, and mechanisms maintaining grassland biodiversity may operate within this constraint.     

Evolutionary Patterns of Morphology and Behavior as Inferred from a Molecular Phylogeny of New World Emballonurid Bats (Tribe Diclidurini)

A molecular phylogeny of New World emballonurid bats based on parsimony and Bayesian analyses of loci from the three different nuclear genetic transmission pathways in mammals (autosomal, X, and Y chromosomes) is well supported and independently corroborated by each individual gene tree. This is in contrast to a single most parsimonious but poorly supported tree based on morphological data, which has only one intergeneric or higher relationship shared with the molecular phylogeny. Combining the morphological and molecular data partitions results in a tree similar to the molecular tree suggesting a high degree of homoplasy and low phylogenetic signal in the morphological data set. Behavioral data are largely incomplete and likewise produce a poorly resolved tree. Nonetheless, patterns of evolution in morphology and behavior can be investigated by using the molecular tree as a phylogenetic framework. Character optimization of the appearance of dorsal fur and preferred roosting sites maps consistently and are correlated on the phylogeny. This suggests an association of camouflage for bats with unusual appearance (two dorsal stripes in Rhynchonycteris and Saccopteryx, or pale fur in Cyttarops and Diclidurus) and roosting in exposed sites (tree trunks or under palm leaves). In contrast, the ancestral states for Old and New World emballonurids are typically uniform brown or black, and they usually roost in sheltered roosts such as caves and tree hollows. Emballonuridae is the only family of bats that has a sac-like structure in the wing propatagium, which is found in four New World genera. Mapping the wing sac character states onto the phylogeny indicates that wing sacs evolved independently within each genus and that there may be a phylogenetic predisposition for this structure. Ear orientation maps relatively consistently on the molecular phylogeny and is correlated to echolocation call parameters and foraging behavior, suggesting a phylogenetic basis for these character systems.     

Motion Noise Changes Directional Interaction between Transparently Moving Stimuli from Repulsion to Attraction

To interpret visual scenes, visual systems need to segment or integrate multiple moving features into distinct objects or surfaces. Previous studies have found that the perceived direction separation between two transparently moving random-dot stimuli is wider than the actual direction separation. This perceptual “direction repulsion” is useful for segmenting overlapping motion vectors. Here we investigate the effects of motion noise on the directional interaction between overlapping moving stimuli. Human subjects viewed two overlapping random-dot patches moving in different directions and judged the direction separation between the two motion vectors. We found that the perceived direction separation progressively changed from wide to narrow as the level of motion noise in the stimuli was increased, showing a switch from direction repulsion to attraction (i.e. smaller than the veridical direction separation). We also found that direction attraction occurred at a wider range of direction separations than direction repulsion. The normalized effects of both direction repulsion and attraction were the strongest near the direction separation of ∼25° and declined as the direction separation further increased. These results support the idea that motion noise prompts motion integration to overcome stimulus ambiguity. Our findings provide new constraints on neural models of motion transparency and segmentation.     

Detection of somaclonal variations in tissue cultured date palm (Phoenix dactylifera L.) using transposable element-based markers

Plant Cell, Tissue and Organ Culture (PCTOC) - In vitro regeneration of date palm (Phoenix dactylifera L.) plants through somatic embryogenesis leads to the generation of somaclonal variants. The...     

Proteomic Insights into Endometrial Receptivity and Embryo‐Endometrial Epithelium Interaction for Implantation Reveal Critical Determinants of Fertility

In vitro fertilization has overcome infertility issues for many couples. However, achieving implantation of a viable embryo into the maternal endometrium remains a limiting step in optimizing pregnancy success. The molecular mechanisms which characterize the transient state of endometrial receptivity, critical in enabling embryo‐endometrial interactions, and proteins which underpin adhesion at the implantation interface, are limited in humans despite these temporally regulated processes fundamental to life. Hence, failure of implantation remains the “final frontier” in infertility. A human coculture model is utilized utilizing spheroids of a trophectoderm (trophoblast stem) cell line, derived from pre‐implantation human embryos, and primary human endometrial epithelial cells, to functionally identify “fertile” versus “infertile” endometrial epithelium based on adhesion between these cell types. Quantitative proteomics identified proteins associated with human endometrial epithelial receptivity (“epithelial receptome”) and trophectoderm adhesion (“adhesome”). As validation, key “epithelial receptome” proteins (MAGT‐1/CDA/LGMN/KYNU/PC4) localized to the epithelium of receptive phase (mid‐secretory) endometrium obtained from fertile, normally cycling women but is largely absent from non‐receptive (proliferative) phase tissues. Factors involved in embryo‐epithelium interaction in successive temporal stages of endometrial receptivity and implantation are demonstrated and potential targets for improving fertility are provided, enhancing potential to become pregnant either naturally or in a clinical setting.     

Endogenous ocular lipids as potential modulators of intraocular pressure

Elevated intraocular pressure (IOP) is a risk factor in glaucoma, a group of irreversible blinding diseases. Endogenous lipids may be involved in regulation of IOP homeostasis. We present comparative fold analysis of phospholipids and sphingolipids of aqueous humour and trabecular meshwork from human control vs primary open-angle glaucoma and mouse control (normotensive) vs ocular hypertensive state. The fold analysis in control vs disease state was based on ratiometric mass spectrometric data for above classes of lipids. We standardized in vitro assays for rapid characterization of lipids undergoing significant diminishment in disease state. Evaluation of lipids using in vitro assays helped select a finite number of lipids that may potentially expand cellular interstitial space embedded in an artificial matrix or increase fluid flow across a layer of cells. These assays reduced a number of lipids for initial evaluation using a mouse model, DBA/2J with spontaneous IOP elevation. These lipids were then used in other mouse models for confirmation of IOP lowering potential of a few lipids that were found promising in previous assessments. Our results provide selected lipid molecules that can be pursued for further evaluation and studies that may provide insight into their function.