Biomechanical form and function in primate seed predators : common solutions for similar mechanical challenges?

Seed predation, as seen in a diverse range of primate species, is a specialist diet in which seeds are accessed via the breakdown of stress-resistant external protective layers. This diet is considered mechanically challenging, requiring high forces and wide gapes to successfully fracture seed casings and gain access to nutrients. It is expected that seed predators will possess anatomical features which facilitate the breakdown of large, hard items. The biomechanical function of seed predator morphology relative to other primates is not known, nor is it known if members of this group converge on the same morphologies. This study examines the masticatory morphology of a diverse range of primate seed predators by combining 1) geometric morphometrics and convergence testing, 2) biomechanical modelling and 3) direct physical testing of tooth performance.Comparisons between different seed predator masticatory morphologies demonstrate some convergence in shape, but other factors including body size, prognathism, and dental morphology appear to enable different solutions to the same mechanical problem. Smaller-bodied seed-predators primarily show adaptations for high mechanical advantage, while larger-bodied seed predators have large muscle cross-sectional area but low mechanical advantage. The dentition of some seed predators requires less force to fracture hard brittle seeds than non-seed predators. Surprisingly, some non-seed predators also possess features which are advantageous to hard food consumption, while one intensive seed predator has poor performance on nearly all measurements.This study suggests no common solution for seed predation, but instead proposes multiple morphologies capable of meeting the demands of this diet. Results presented here also highlight the need to consider the masticatory system as a whole, as both muscle force capacity and dental occlusal surface impact food breakdown. Without considering these different components of the masticatory apparatus it is not possible to fully appreciate the potential for functional equivalence in this system

Diversity of Synechococcus at the Martha\u27s Vineyard Coastal Observatory: Insights from Culture Isolations, Clone Libraries, and Flow Cytometry

The cyanobacterium Synechococcus is a ubiquitous, important phytoplankter across the world’s oceans. A high degree of genetic diversity exists within the marine group, which likely contributes to its global success. Over 20 clades with different distribution patterns have been identified. However, we do not fully understand the environmental factors that control clade distributions. These factors are likely to change seasonally, especially in dynamic coastal systems. To investigate how coastal Synechococcus assemblages change temporally, we assessed the diversity of Synechococcus at the Martha’s Vineyard Coastal Observatory (MVCO) over three annual cycles with culture-dependent and independent approaches. We further investigated the abundance of both phycoerythrin (PE)-containing and phycocyanin (PC)-only Synechococcus with a flow cytometric setup that distinguishes PC-only Synechococcus from picoeukaryotes. We found that the Synechococcus assemblage at MVCO is diverse (13 different clades identified), but dominated by clade I representatives. Many clades were only isolated during late summer and fall, suggesting more favorable conditions for isolation at this time. PC-only strains from four different clades were isolated, but these cells were only detected by flow cytometry in a few samples over the time series, suggesting they are rare at this site. Within clade I, we identified four distinct subclades. The relative abundances of each subclade varied over the seasonal cycle, and the high Synechococcus cell concentration at MVCO may be maintained by the diversity found within this clade. This study highlights the need to understand how temporal aspects of the environment affect Synechococcus community structure and cell abundance

Sixty years of Sverdrup : a retrospective of progress in the study of phytoplankton blooms

Author Posting. © The Oceanography Society, 2014. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 27, no. 1 (2014): 222–235, doi:10.5670/oceanog.2014.26.One of the most dramatic large-scale features in the ocean is the seasonal greening of the North Atlantic in spring and summer due to the accumulation of phytoplankton biomass in the surface layer. In 1953, Harald Ulrik Sverdrup hypothesized a now canonical mechanism for the development and timing of phytoplankton blooms in the North Atlantic. Over the next 60 years, Sverdrup's Critical Depth Hypothesis spurred progress in understanding of bloom dynamics and offered a valuable theoretical framework on which to build. In reviewing 60 years of literature, the authors trace the development of modern bloom initiation hypotheses, highlighting three case studies that illuminate the complexity, including both catalysts and impediments, of scientific progress in the wake of Sverdrup's hypothesis. Most notably, these cases demonstrate that the evolution of our understanding of phytoplankton blooms was paced by access not only to technology but also to concurrent insights from several disciplines. This exploration of the trajectories and successes in bloom studies highlights the need for expanding interdisciplinary collaborations to address the complexity of phytoplankton bloom dynamics

IFN-γ-producing CD4+ T cells promote experimental cerebral malaria by modulating CD8+ T cell accumulation within the brain.

It is well established that IFN-γ is required for the development of experimental cerebral malaria (ECM) during Plasmodium berghei ANKA infection of C57BL/6 mice. However, the temporal and tissue-specific cellular sources of IFN-γ during P. berghei ANKA infection have not been investigated, and it is not known whether IFN-γ production by a single cell type in isolation can induce cerebral pathology. In this study, using IFN-γ reporter mice, we show that NK cells dominate the IFN-γ response during the early stages of infection in the brain, but not in the spleen, before being replaced by CD4(+) and CD8(+) T cells. Importantly, we demonstrate that IFN-γ-producing CD4(+) T cells, but not innate or CD8(+) T cells, can promote the development of ECM in normally resistant IFN-γ(-/-) mice infected with P. berghei ANKA. Adoptively transferred wild-type CD4(+) T cells accumulate within the spleen, lung, and brain of IFN-γ(-/-) mice and induce ECM through active IFN-γ secretion, which increases the accumulation of endogenous IFN-γ(-/-) CD8(+) T cells within the brain. Depletion of endogenous IFN-γ(-/-) CD8(+) T cells abrogates the ability of wild-type CD4(+) T cells to promote ECM. Finally, we show that IFN-γ production, specifically by CD4(+) T cells, is sufficient to induce expression of CXCL9 and CXCL10 within the brain, providing a mechanistic basis for the enhanced CD8(+) T cell accumulation. To our knowledge, these observations demonstrate, for the first time, the importance of and pathways by which IFN-γ-producing CD4(+) T cells promote the development of ECM during P. berghei ANKA infection

The IDA3 adapter, required for intraflagellar transport of I1 dynein, is regulated by ciliary length

Axonemal dyneins, including inner dynein arm I1, assemble in the cytoplasm prior to transport into cilia by intraflagellar transport (IFT). How I1 dynein interacts with IFT is not understood. We take advantage of the Chlamydomonas reinhardtii ida3 mutant, which assembles the inner arm I1 dynein complex in the cytoplasm but fails to transport I1 into the cilium, resulting in I1 dynein-deficient axonemes with abnormal motility. The IDA3 gene encodes an ∼115-kDa coiled-coil protein that primarily enters the cilium during ciliary growth but is not an axonemal protein. During growth, IDA3, along with I1 dynein, is transported by anterograde IFT to the tip of the cilium. At the tip, IDA3 uncouples from IFT and diffuses within the cilium. IFT transport of IDA3 decreases as cilia lengthen and subsides once full length is achieved. IDA3 is the first example of an essential and selective IFT adapter that is regulated by ciliary length. </jats:p

Mapping the Extended HI Distribution of Three Dwarf Galaxies

We present large field HI-line emission maps obtained with the single-dish Green Bank Telescope centered on the dwarf irregular galaxies Sextans A, NGC 2366, and WLM. We do not detect the extended skirts of emission associated with the galaxies that were reported from Effelsberg observations (Huchtmeier et al. 1981). The ratio of HI at 10^19 atoms cm^-2 to optical extents of these galaxies are instead 2--3, which is normal for this type of galaxy. There is no evidence for a truncation in the HI distribution >/=10^19 atoms cm^-2.Comment: To be published in A

The Lantern Vol. 12, No. 3, June 1944

• A Peek Through a Byberry Window • Fragment • My Grudge Against the Fiction Detective • Haunting Refrain • The World and I • They Said • The Brook • By Their Fruits Ye Shall Know Them : 1944 Fogel Prize Essay • Why • Green Leaf • Night Drama • In That Same Hour • The Greeks Had a Word For It • The Call of War • The Promise of a Pearl • The Apiaryhttps://digitalcommons.ursinus.edu/lantern/1033/thumbnail.jp

Evolution of Massive Stars at Low Metallicity

This paper reports the contributions made on the occasion of the Special Session entitled "Evolution of Massive Stars at Low Metallicity” which was held on Sunday, December 9, 2007 in Kauai (USA

Development and Application of an Interdisciplinary Rapid Message Testing Model for COVID-19 in North Carolina

Introduction From the onset of the COVID-19 pandemic, public health officials have sought to develop evidence-based messages to reduce COVID-19 transmission by communicating key information to media outlets and the public. We describe the development of an interdisciplinary rapid message testing model to quickly create, test, and share messages with public health officials for use in health campaigns and policy briefings. Methods An interdisciplinary research team from the University of North Carolina at Chapel Hill assembled in March 2020 to assist the state health department in developing evidence-based messages to influence social distancing behaviors in the state. We developed and iteratively executed a rapid message testing model; the components of the 4-step model were message creation, survey development, survey administration, and analysis and presentation to health department officials. The model was executed 4 times, each during a 7-day period in April and May, and each subsequent survey included new phrasing and/or messaging informed by the previous week’s survey. A total of 917 adults from North Carolina participated in the 4 surveys. Results Survey participants rated messages focused on protecting oneself and others higher than messages focused on norms and fear-based approaches. Pairing behaviors with motivations increased participants’ desire to social distance across all themes and subgroups. For example, adding “Protect your grandmother, your neighbor with cancer, and your best friend with asthma,” to messaging received a 0.9-point higher score than the base message, “Stay 6 feet apart from others when out in public.” Practice Implications Our model to promote social distancing in North Carolina during the COVID-19 pandemic can be used for rapid, iterative message testing during public health emergencies