Major transitions in trilobite ontogeny have historically been defined based on the number and distribution of trunk segments, and articulation between the trunk and cephalon. This study documents additional morphological change across the meraspid-holaspid transition on the Ordovician phacopid trilobite Calyptaulax strasburgensis. An extensive dataset of silicified cranidia and pygidia collected from the mid-Ordovician Edinburg Formation of Virginia was subjected to a series of multivariate analyses, with a primary focus on the intersections and termini of furrows. Multivariate regression of partial warp scores demonstrates statistically significant change in allometric growth patterns over the course of development. These changes are concentrated in earlier instars, but are coincident in cranidia and pygidia. This sharp decrease in the rate of allometry, present in both tagmata, is expressed as significant breakpoints derived from a segmented regression, with the largest portion of allometric change found in the pre-breakpoint individuals. The term holeidos is proposed to describe the completion of form during trilobite development, independent of the completion of the thorax. The most dramatic change in shape during this period of ontogeny includes lateral glabellar expansion through deflection of the axial and palpebral furrows, possibly reflecting a change in the feeding habit during later development. Other morphological changes include the development of a more angular appearance to the anterior portion of the glabella, and anterior migration of the pygidial anterior margin. The appearance of these growth patterns in Calyptaulax extends the temporal range of these changes, some of which have only been documented in Devonian phacopids.

Host-specific interactions can maintain genetic and phenotypic diversity in parasites that attack multiple host species. Host diversity, in turn, may promote parasite diversity by selection for genetic divergence or plastic responses to host type. The parasitic weed purple witchweed [Striga hermonthica (Delile) Benth.] causes devastating crop losses in sub-Saharan Africa and is capable of infesting a wide range of grass hosts. Despite some evidence for host adaptation and host-by-Striga genotype interactions, little is known about intraspecific Striga genomic diversity. Here we present a study of transcriptomic diversity in populations of S. hermonthica growing on different hosts (maize [Zea mays L.] vs. grain sorghum [Sorghum bicolor (L.) Moench]). We examined gene expression variation and differences in allelic frequency in expressed genes of aboveground tissues from populations in western Nigeria parasitizing each host. Despite low levels of host-based genome-wide differentiation, we identified a set of parasite transcripts specifically associated with each host. Parasite genes in several different functional categories implicated as important in host–parasite interactions differed in expression level and allele on different hosts, including genes involved in nutrient transport, defense and pathogenesis, and plant hormone response. Overall, we provide a set of candidate transcripts that demonstrate host-specific interactions in vegetative tissues of the emerged parasite S. hermonthica. Our study shows how signals of host-specific processes can be detected aboveground, expanding the focus of host–parasite interactions beyond the haustorial connection.

We previously demonstrated that electrode architectures comprising nanoscale birnessite-like MnOx affixed to three-dimensional carbon nanofoam (CNF) scaffolds offer performance advantages when used as cathodes in rechargeable zinc-ion cells. To discern chemical and physical changes at the MnOx@CNF electrode upon deep charge/discharge in aqueous Zn2+-containing electrolytes, we deploy electroanalytical methods and ex situ characterization by microscopy, elemental analysis, x-ray photoelectron spectroscopy, x-ray diffraction, and x-ray pair distribution function analyses. Our findings verify that redox processes at the MnOx are accompanied by reversible precipitation/dissolution of crystalline zinc hydroxide sulfate (Zn4(OH)6(SO4)·xH2O), mediated by the more uniformly reactive electrode structure inherent to the CNF scaffold.

We performed a molecular and epidemiologic study of a healthcare-associated rhinovirus outbreak to better understand transmission in neonatal intensive care settings. Sequencing of the 7 outbreak strains revealed 4 distinct clades, indicating multiple sources. A single clade infected 3 patients in adjacent rooms, suggesting horizontal transmission. We observed 1 rhinovirus-associated death.

Ecophenotypic variation in populations is driven by differences in environmental variables. In marine environments, ecophenotypic variation may be caused by differences in hydrodynamic conditions, substrate type, water depth, temperature, salinity, oxygen concentration, and habitat heterogeneity, among others. Instances of ecophenotypic variation in modern and fossil settings are common, but little is known about the influences of time averaging and spatial averaging on their preservation. Here we examine the shell morphology of two adjacent populations, both live collected and death assemblages, of the infaunal, suspension-feeding, intertidal bivalve Leukoma staminea from the well-studied Argyle Creek and Argyle Lagoon locations on San Juan Island, Washington. Individuals in the low-energy lagoon are free to burrow in the fine-grained substrate, while clams in the high-energy creek are precluded from burrowing in the rocky channel. Our results demonstrate variation in size and shape between the adjacent habitats. Lagoon clams are larger, more disk-shaped, and have relatively larger siphons than their creek counterparts, which are smaller, more spherical in shape, and have a relatively shallower pallial sinus. This ecophenotypy is preserved among death assemblages, although with generally greater variation due to time averaging and shell transport. Our interpretation is that ecophenotypic variation, in this case, is induced by differing hydrodynamic regimes and substrate types, cumulatively resulting in physiological trade-offs diverting resources from feeding and respiration to stability and shell strength, all of which have the potential to be preserved in the fossil record.

OBJECTIVES/SPECIFIC AIMS: Endogenous RT (eRT) is necessary for the function of retrotransposons, elements that replicate via an RNA intermediate. One source of eRT activity is long interspersed elements (LINE). LINEs, of which there are several subgroups (L1, L2, L3), are retrotransposons that regulate cellular growth and gene expression. Given their diverse and important roles, we hypothesized that L1 elements regulate functional responses in megakaryocytes and platelets; a concept not yet examined in the field. METHODS/STUDY POPULATION: To study eRT in human platelets we used RT activity assays, PCR, and Western blot approaches. Furthermore, we used an RT-inhibitor to dissect the function of eRT, analyzed RT-dependent protein synthetic capacity, and immunoprecipitated RNA-DNA hybrids. RNA-DNA hybrids were also detected by means of ICC and automated analysis using CellProfiler software. RNA-DNA hybrids were validated by PCR and eRT regulated synthesis of target proteins was analyzed using autoradiography and Western blot techniques. Platelets from patients with HIV+ were examined in parallel. RESULTS/ANTICIPATED RESULTS: We identified that highly purified, isolated platelets from healthy subjects possess eRT activity. eRT activity was blocked with the non-nucleoside RT inhibitor nevirapine at concentrations within the therapeutic drug range. L1 elements are bicistronic, containing 2 open reading frames (ORFs), ORF1 and ORF2. Thus, we next identified that human platelets express full-length L1 mRNA containing ORF1 and ORF2. In human platelets, eRT activity was localized to L1 protein containing ribonucleo particles. Platelet eRT reverse transcribed exogenous RNAs, a process inhibited by nevirapine, acting in trans using the 3′-UTR of exogenous mRNAs as a template. To dissect the function of eRT in platelets, we next examined cytoskeletal and protein synthetic events in the presence or absence of nevirapine. Inhibition of eRT in isolated platelets led to characteristically beaded platelets in appearance, strongly resembling bone marrow proplatelets. Parallel increases in platelet reactivity were also observed. As these changes occurred over hours, not minutes, we hypothesized that inhibition of eRT would affect platelet protein synthetic events. Consistent with this, RT inhibition resulted in upregulation of global platelet protein synthesis. We validated upregulation of the synthesis of specific proteins (mitofilin, p-selectin, and L26—a component of the 60S ribosomal subunit essential for mRNA translation). RNA-DNA hybrids, noncanonical nucleic acid structures that regulate gene expression, are enriched in regions where L1 is abundant. RNA-DNA hybrids were present in platelets and expression confirmed via differential digestion of RNAs (eg, with RNase A and RNAse I). Next-generation sequencing of pulled down (eg, immunoprecipitated) platelet RNA-DNA hybrids identified numerous differentially expressed transcripts and we focused on MAP1LC3B (LC3B), a primary regulator of autophagy. Hybrid sequencing results for LC3B were validated using qPCR and we confirmed that LC3B RNA binds to L1-encoded RNA binding protein. Platelets treated with nevirapine had increased total LC3B protein expression. As RT inhibition is an important mechanism to control HIV infection, we examined platelet morphology, activation, and LC3B expression in platelets from HIV+ subjects treated with nevirapine. HIV+ patients treated with RT inhibitors had higher numbers of platelets that were beaded in appearance at baseline, increased platelet reactivity, and differential LC3B expression compared with healthy controls. DISCUSSION/SIGNIFICANCE OF IMPACT: Taken together, these results demonstrate that platelets possess eRT activity that regulates platelet morphology, platelet hyperreactivity, and protein synthetic events. We postulate that eRT activity in platelets may be a new post-transcriptional regulatory checkpoint. Moreover, our findings have implications in HIV+ patients treated with RT inhibitors, where off-target effects may contribute to platelet activation and an increased risk of thrombosis.