An efficient cre-based workflow for genomic integration and expression of large biosynthetic pathways in Eubacterium limosum.

Acetogenic Clostridia are obligate anaerobes that have emerged as promising microbes for the renewable production of biochemicals owing to their ability to efficiently metabolize sustainable single-carbon feedstocks. Additionally, Clostridia are increasingly recognized for their biosynthetic potential, with recent discoveries of diverse secondary metabolites ranging from antibiotics to pigments to modulators of the human gut microbiota. Lack of efficient methods for genomic integration and expression of large heterologous DNA constructs remains a major challenge in studying biosynthesis in Clostridia and using them for metabolic engineering applications. To overcome this problem, we harnessed chassis-independent recombinase-assisted genome engineering (CRAGE) to develop a workflow for facile integration of large gene clusters (>10 kb) into the human gut acetogen Eubacterium limosum. We then integrated a non-ribosomal peptide synthetase gene cluster from the gut anaerobe Clostridium leptum, which previously produced no detectable product in traditional heterologous hosts. Chromosomal expression in E. limosum without further optimization led to production of phevalin at 2.4 mg/L. These results further expand the molecular toolkit for a highly tractable member of the Clostridia, paving the way for sophisticated pathway engineering efforts, and highlighting the potential of E. limosum as a Clostridial chassis for exploration of anaerobic natural product biosynthesis.

Principled distillation of UK Biobank phenotype data reveals underlying structure in human variation.

Data within biobanks capture broad yet detailed indices of human variation, but biobank-wide insights can be difficult to extract due to complexity and scale. Here, using large-scale factor analysis, we distill hundreds of variables (diagnoses, assessments and survey items) into 35 latent constructs, using data from unrelated individuals with predominantly estimated European genetic ancestry in UK Biobank. These factors recapitulate known disease classifications, disentangle elements of socioeconomic status, highlight the relevance of psychiatric constructs to health and improve measurement of pro-health behaviours. We go on to demonstrate the power of this approach to clarify genetic signal, enhance discovery and identify associations between underlying phenotypic structure and health outcomes. In building a deeper understanding of ways in which constructs such as socioeconomic status, trauma, or physical activity are structured in the dataset, we emphasize the importance of considering the interwoven nature of the human phenome when evaluating public health patterns.

Partitioning of an Enzyme-Polymer Surfactant Nanocomplex into Lipid-Rich Cellular Compartments Drives In Situ Hydrolysis of Organophosphates.

Most organophosphates (OPs) are hydrophobic, and after exposure, can sequester into lipophilic regions within the body, such as adipose tissue, resulting in long term chronic effects. Consequently, there is an urgent need for therapeutic agents that can decontaminate OPs in these hydrophobic regions. Accordingly, an enzyme-polymer surfactant nanocomplex is designed and tested comprising chemically supercharged phosphotriesterase (Agrobacterium radiobacter; arPTE) electrostatically conjugated to amphiphilic polymer surfactant chains ([cat.arPTE][S-]). Experimentally-derived structural data are combined with molecular dynamics (MD) simulations to provide atomic level detail on conformational ensembles of the nanocomplex using dielectric constants relevant to aqueous and lipidic microenvironments. These show the formation of a compact admicelle pseudophase surfactant corona under aqueous conditions, which reconfigures to yield an extended conformation at a low dielectric constant, providing insight into the mechanism underpinning cell membrane binding. Significantly, it demonstrated that [cat.arPTE][S-] spontaneously binds to human mesenchymal stem cell membranes (hMSCs), resulting in on-cell OP hydrolysis. Moreover, the nanoconstruct can endocytose and partition into the intracellular fatty vacuoles of adipocytes and hydrolyze sequestered OP.

Pericapsular Nerve Group Block Did Not Reduce Post-Operative Pain or Opioid Use After Total Hip Arthroplasty.

INTRODUCTION: The pericapsular nerve group (PENG) block is a newly developed regional anesthesia technique designed to manage post-operative hip pain following a fracture or surgery while also maintaining quadriceps strength and mobility. The goal of our study was to compare post-operative pain scores and opioid usage during the post-operative period prior to discharge following total hip arthroplasty (THA) using the posterior approach between patients who received a PENG block and those who did not. METHODS: We conducted a retrospective study on patients undergoing elective, posterior approach THA at a single tertiary care academic center. The two groups included a study group (THA with PENG block in 2021; n = 66) and a control group (THA prior to PENG block implementation in 2019; n = 70). RESULTS: There were no significant differences in pain scores during post-operative minutes 0 to 59 (study group 6.8; control group 6.6; P = 0.81) or during post-operative minutes 60 to 119 (study group 6.2; control group 5.6; P = 0.40). There were no significant differences in total post-operative in-hospital morphine milliequivalent (MME) opioid consumption (study group 55.8 MMEs; control group 75.0 MMEs; P = 0.14). The study group was found to have a shorter length of stay (LOS) (study group 17.0 hours; control group 32.6 hours; P < 0.0001) and faster mobilization (study group 3.0 hours; control group 4.9 hours; P < 0.0001) than the control group. CONCLUSION: Our results show that use of the PENG block did not result in lower post-operative pain scores or opioid consumption after THA using the posterior surgical approach. The study group had a shorter LOS and time to mobilization than the control group, though this was likely due to standard hospital procedure shifting to same day discharge for THA between 2019 and 2021 due to COVID-19.

Computed tomography (CT) derived radiomics to predict post-operative disease recurrence in gastric cancer; a systematic review and meta-analysis.

INTRODUCTION: Radiomics offers the potential to predict oncological outcomes from pre-operative imaging in order to identify 'high risk' patients at increased risk of recurrence. The application of radiomics in predicting disease recurrence provides tailoring of therapeutic strategies. We aim to comprehensively assess the existing literature regarding the current role of radiomics as a predictor of disease recurrence in gastric cancer. METHODS: A systematic search was conducted in Medline, EMBASE, and Web of Science databases. Inclusion criteria encompassed retrospective and prospective studies investigating the use of radiomics to predict post-operative recurrence in ovarian cancer. Study quality was assessed using the QUADAS-2 and Radiomics Quality Score tools. RESULTS: Nine studies met the inclusion criteria, involving a total of 6,662 participants. Radiomic-based nomograms demonstrated consistent performance in predicting disease recurrence, as evidenced by satisfactory area under the receiver operating characteristic curve values (AUC range 0.72 - 1). The pooled AUCs calculated using the inverse-variance method for both the training and validation datasets were 0.819 and 0.789 respectively CONCLUSION: Our review provides good evidence supporting the role of radiomics as a predictor of post-operative disease recurrence in gastric cancer. Included studies noted good performance in predicting their primary outcome. Radiomics may enhance personalised medicine by tailoring treatment decision based on predicted prognosis.

RANO 2.0 criteria: concepts applicable to the neuroradiologist's clinical practice.

PURPOSE OF REVIEW: The Response Assessment in Neuro-Oncology (RANO) 2.0 criteria aim at improving the standardization and reliability of treatment response assessment in clinical trials studying central nervous system (CNS) gliomas. This review presents the evidence supporting RANO 2.0 updates and discusses which concepts can be applicable to the clinical practice, particularly in the clinical radiographic reads. RECENT FINDINGS: Updates in RANO 2.0 were supported by recent retrospective analyses of multicenter data from recent clinical trials. As proposed in RANO 2.0, in tumors receiving radiation therapy, the post-RT MRI scan should be used as a reference baseline for the following scans, as opposed to the pre-RT scan, and radiographic findings suggesting progression within three months after radiation therapy completion should be verified with confirmatory scans. Volumetric assessments should be considered, when available, especially for low-grade gliomas, and the evaluation of nonenhancing disease should have a marginal role in glioblastoma. However, the radiographic reads in the clinical setting also benefit from aspects that lie outside RANO 2.0 criteria, such as qualitative evaluations, patient-specific clinical considerations, and advanced imaging. SUMMARY: While RANO 2.0 criteria are meant for the standardization of the response assessment in clinical trials, some concepts have the potential to improve patients' management in the clinical practice.

Temporary mesenteric venous shunting for portal vein reconstruction: A novel technical adjunct.

Pancreatic resection not infrequently requires portal vein (PV) repair or replacement. PV reconstruction often requires bypass grafting or patch venoplasty, and these grafts and patches require time to thaw or harvest. Mesenteric ischemia and congestion with associated bowel edema may result from prolonged venous occlusion during thawing, harvesting, and reconstructing. Temporary shunting of the mesenteric venous circulation may mitigate these adverse effects. Twenty-one patients were shunted using Argyle shunts during PV reconstruction from 2010 to 2020. Reconstructions in this series consisted of aortic homograft interposition grafts (52%), bovine pericardial patches (38%), internal jugular vein interposition grafts (5%), and internal jugular patches (5%). No intraoperative complications resulted from shunt placement; technical success of PV reconstruction was 100%. Temporary venous shunting during PV reconstruction is safe, technically straightforward, and may serve to decrease the duration of venous mesenteric occlusion.

Plastic pollution and human pathogens: Towards a conceptual shift in risk management at bathing water and beach environments.

Emerging evidence indicates that micro- and macro-plastics present in water can support a diverse microbial community, including potential human pathogens (e.g., bacteria, viruses). This interaction raises important concerns surrounding the role and suitability of current bathing water regulations and associated pathogen exposure risk within beach environments. In response to this, we critically evaluated the available evidence on plastic-pathogen interactions and identified major gaps in knowledge. This review highlighted the need for a conceptual shift in risk management at public beaches recognising: (i) interconnected environmental risks, e.g., associations between microbial compliance parameters, potential pathogens and both contemporary and legacy plastic pollution; and (ii) an appreciation of risk of exposure to plastic co-pollutants for both water and waterside users. We present a decision-making framework to identify options to manage plastic-associated pathogen risks alongside short- and longer-term research priorities. This advance will help deliver improvements in managing plastic-associated pathogen risk, acknowledging that human exposure potential is not limited to only those who engage in water-based activity. We argue that adopting these recommendations will help create an integrated approach to managing and reducing human exposure to pathogens at bathing, recreational water and beach environments.

Intelligibility of Natively and Nonnatively Produced English Speech Presented in Noise to a Large Cohort of United States Service Members.

PURPOSE: A corpus of English matrix sentences produced by 60 native and nonnative speakers of English was developed as part of a multinational coalition task group. This corpus was tested on a large cohort of U.S. Service members in order to examine the effects of talker nativeness, listener nativeness, masker type, and hearing sensitivity on speech recognition performance in this population. METHOD: A total of 1,939 U.S. Service members (ages 18-68 years) completed this closed-set listening task, including 430 women and 110 nonnative English speakers. Stimuli were produced by native and nonnative speakers of English and were presented in speech-shaped noise and multitalker babble. Keyword recognition accuracy and response times were analyzed. RESULTS: General(ized) linear mixed-effects regression models found that, on the whole, speech recognition performance was lower for listeners who identified as nonnative speakers of English and when listening to speech produced by nonnative speakers of English. Talker and listener effects were more pronounced when listening in a babble masker than in a speech-shaped noise masker. Response times varied as a function of recognition score, with longest response times found for intermediate levels of performance. CONCLUSIONS: This study found additive effects of talker and listener nonnativeness when listening to speech in background noise. These effects were present in both accuracy and response time measures. No multiplicative effects of talker and listener language background were found. There was little evidence of a negative interaction between talker nonnativeness and hearing impairment, suggesting that these factors may have redundant effects on speech recognition. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.26060191.

Neuronal Ceroid Lipofuscinoses Type 7 (CLN7)- A Case Series Reporting Cross Sectional and Retrospective Clinical Data to Evaluate Validity of Standardized Tools to Assess Disease Progression, Quality of Life, and Adaptive Skills.

Background: This study evaluated the clinical characteristics of neuronal ceroid lipofuscinosis type 7 or CLN7 disease spectrum to characterize the clinical, electrophysiologic and neuroimaging phenotypes. Methods: We performed a single-center cross sectional data collection along with retrospective medical chart review in patients with a genetic diagnosis of CLN7. This study received ethical approval by the University of Texas Southwestern Medical Center Institutional Review Board. A total of 8 patients were included between the ages of 4 to 6 years. All patients had a genetic diagnosis of CLN7 with homozygous or compound heterozygous mutations in the MFSD8 gene. The information collected includes patient demographics, developmental history, neurological events including seizures and neurodevelopmental regression along with further evaluation of brain magnetic resonance imaging and electrophysiological findings. The clinical phenotype is described through cross sectional and retrospective data collection and standardized tools assessing quality of life and functional skills. Conclusions: Our findings in this cohort of CLN7 patients indicated that development is initially normal with onset of clinical symptoms as early as two years of age. Language problems were noted prior to or at the onset of seizures in all cases. Gait problems were noted prior to seizure onset in 3 of 8 patients, and at or within 6 months after the onset of seizures in 5 of 8 patients. All patients followed a progressive course of language, motor, and neurocognitive deterioration. Congruent with the medical history, our patients had significantly low scores on adaptive abilities. Natural history data such as this can be used to support future clinical trial designs.

Drosophila melanogaster Toll-9 elicits antiviral immunity against Drosophila C virus.

The Toll pathway plays a pivotal role in innate immune responses against pathogens. The evolutionary conserved pathogen recognition receptors (PRRs), including Toll like receptors (TLRs), play a crucial role in recognition of pathogen associated molecular patterns (PAMPs). The Drosophila genome encodes nine Toll receptors that are orthologous to mammalian TLRs. While mammalian TLRs directly recognize PAMPs, most Drosophila Tolls recognize the proteolytically cleaved ligand Spätzle to activate downstream signaling cascades. In this study, we demonstrated that Toll-9 is crucial for antiviral immunity against Drosophila C virus (DCV), a natural pathogen of Drosophila . A transposable element insertion in the Toll-9 gene renders the flies more susceptible to DCV. The stable expression of Toll-9 in S2 cells confers resistance against DCV infection by upregulation of the RNAi pathway. Toll-9 promotes the dephosphorylation of AKT, resulting in the induction of antiviral RNAi genes to inhibit DCV replication. Toll-9 localizes to the endosome where it binds dsRNA, suggesting its role to detect viral dsRNA. Toll-9 also induces apoptosis during DCV infection, contributing to its antiviral role. Together, this work identifies the role of Toll-9 in antiviral immunity against DCV infection through its ability to bind dsRNA and induce AKT-mediated RNAi antiviral immunity. IMPORTANCE: Insects rely on innate immunity and RNA interference (RNAi) to combat viral infections. Our study underscores the pivotal role of Drosophila Toll-9 in antiviral immunity, aligning with findings in Bombyx mori , where Toll-9 activation upregulates the RNAi component Dicer2 . We demonstrate that Drosophila Toll-9 functions as a pattern recognition receptor (PRR) for double-stranded RNA (dsRNA) during Drosophila C virus (DCV) infection, akin to mammalian TLRs. Toll-9 activation leads to the upregulation of key RNAi components, Dicer2 and Argonaute2 , and dephosphorylation of AKT triggers apoptosis via induction of proapoptotic genes Hid and Reaper . This study also reveals that Toll-9 localizes in endosomal compartments where it interacts with dsRNA. These insights enhance our understanding of Drosophila innate immune mechanisms, reflecting the evolutionary conservation of immune responses across diverse species and providing impetus for further research into the conserved roles of TLRs across the animal kingdom.

Fitting Epidemic Models to Data: A Tutorial in Memory of Fred Brauer.

Fred Brauer was an eminent mathematician who studied dynamical systems, especially differential equations. He made many contributions to mathematical epidemiology, a field that is strongly connected to data, but he always chose to avoid data analysis. Nevertheless, he recognized that fitting models to data is usually necessary when attempting to apply infectious disease transmission models to real public health problems. He was curious to know how one goes about fitting dynamical models to data, and why it can be hard. Initially in response to Fred's questions, we developed a user-friendly R package, fitode, that facilitates fitting ordinary differential equations to observed time series. Here, we use this package to provide a brief tutorial introduction to fitting compartmental epidemic models to a single observed time series. We assume that, like Fred, the reader is familiar with dynamical systems from a mathematical perspective, but has limited experience with statistical methodology or optimization techniques.

Topology Testing and Demographic Modeling Illuminate a Novel Speciation Pathway in the Greater Caribbean Sea Following the Formation of the Isthmus of Panama.

Recent genomic analyses have highlighted the prevalence of speciation with gene flow in many taxa and have underscored the importance of accounting for these reticulate evolutionary processes when constructing species trees and generating parameter estimates. This is especially important for deepening our understanding of speciation in the sea where fast moving ocean currents, expanses of deep water, and periodic episodes of sea level rise and fall act as soft and temporary allopatric barriers that facilitate both divergence and secondary contact. Under these conditions, gene flow is not expected to cease completely while contemporary distributions are expected to differ from historical ones. Here we conduct range-wide sampling for Pederson's cleaner shrimp (Ancylomenes pedersoni), a species complex from the Greater Caribbean that contains three clearly delimited mitochondrial lineages with both allopatric and sympatric distributions. Using mtDNA barcodes and a genomic ddRADseq approach, we combine classic phylogenetic analyses with extensive topology testing and demographic modeling (10 site frequency replicates x 45 evolutionary models x 50 model simulations/replicate = 22,500 simulations) to test species boundaries and reconstruct the evolutionary history of what was expected to be a simple case study. Instead, our results indicate a history of allopatric divergence, secondary contact, introgression, and endemic hybrid speciation that we hypothesize was driven by the final closure of the Isthmus of Panama and the strengthening of the Gulf Stream Current ~3.5 million years ago. The history of this species complex recovered by model-based methods that allow reticulation differs from that recovered by standard phylogenetic analyses and is unexpected given contemporary distributions. The geologically and biologically meaningful insights gained by our model selection analyses illuminate what is likely a novel pathway of species formation not previously documented that resulted from one of the most biogeographically significant events in Earth's history.

A randomized, pilot trial comparing vaginal hyaluronic acid to vaginal estrogen for the treatment of genitourinary syndrome of menopause.

OBJECTIVE: The aim of this study was to compare the efficacy of a non-hormone alternative, vaginal hyaluronic acid (HLA), to a standard-of-care therapy, vaginal estrogen, for the treatment of genitourinary syndrome of menopause (GSM). METHODS: This was a randomized, parallel arm pilot trial. Women with GSM were randomized to an HLA vaginal suppository or vaginal estrogen cream for 12 wk to compare the primary outcome, the vulvovaginal symptom questionnaire (VSQ) score. Secondary outcomes included the following: the female sexual function index (FSFI), the vaginal symptom index (VSI), visual analog scale (VAS) for dyspareunia, vaginal itching, and vaginal dryness, patient global impression of improvement (PGI-I) at follow-up, vaginal maturation index, and vaginal pH. Differences between treatment groups were estimated using the two-sided, two-sample t-test and 95% confidence intervals. RESULTS: Forty-nine women were randomized and 45 participants (vaginal estrogen = 23, vaginal HLA = 22) provided data at week 12. Baseline characteristics were similar in both groups. On the VSQ, there was no observed difference in overall scores between the HLA and vaginal estrogen groups at 12 wk (P = 0.81). Improvement was seen within both treatment groups on the VSQ after 12 wk. The VAS score, total VSI score, total FSFI score, and vaginal pH improved over time; however, improvement did not differ between study arms. Over 90% participants noted improvement on the PGI-I in both groups (P = 0.61). No treatment-related serious adverse events occurred. CONCLUSIONS: There were no clinically meaningful differences between vaginal HLA and vaginal estrogen for the treatment of GSM after 12 wk. Vaginal HLA may be a promising non-hormone therapy for GSM.

Development of a Recombineering System for the Acetogen Eubacterium limosum with Cas9 Counterselection for Markerless Genome Engineering.

Eubacterium limosum is a Clostridial acetogen that efficiently utilizes a wide range of single-carbon substrates and contributes to metabolism of health-associated compounds in the human gut microbiota. These traits have led to interest in developing it as a platform for sustainable CO2-based biofuel production to combat carbon emissions, and for exploring the importance of the microbiota in human health. However, synthetic biology and metabolic engineering in E. limosum have been hindered by the inability to rapidly make precise genomic modifications. Here, we screened a diverse library of recombinase proteins to develop a highly efficient oligonucleotide-based recombineering system based on the viral recombinase RecT. Following optimization, the system is capable of catalyzing ssDNA recombination at an efficiency of up to 2%. Addition of a Cas9 counterselection system eliminated unrecombined cells, with up to 100% of viable cells encoding the desired mutation, enabling creation of genomic point mutations in a scarless and markerless manner. We deployed this system to create a clean knockout of the extracellular polymeric substance (EPS) gene cluster, generating a strain incapable of biofilm formation. This approach is rapid and simple, not requiring laborious homology arm cloning, and can readily be retargeted to almost any genomic locus. This work overcomes a major bottleneck in E. limosum genetic engineering by enabling precise genomic modifications, and provides both a roadmap and associated recombinase plasmid library for developing similar systems in other Clostridia of interest.

Effect of Jardiance on glucose uptake into astrocytomas.

PURPOSE: SGLT2, the sodium glucose cotransporter two, is expressed in human pancreatic, prostate and brain tumors, and in a mouse cancer model SGLT2 inhibitors reduce tumor glucose uptake and growth. In this study we have measured the effect of a specific SGLT2 inhibitor, Jardiance® (Empagliflozin), on glucose uptake into astrocytomas in patients. METHODS: We have used a specific SGLT glucose tracer, α-methyl-4-[18F]fluoro-4-deoxy-α-D-glucopyranoside (Me4FDG), and Positron Emission Tomography (PET) to measure glucose uptake. Four of five patients enrolled had WHO grade IV glioblastomas, and one had a low grade WHO Grade II astrocytoma. Two dynamic brain PET scans were conducted on each patient, one before and one after treatment with a single oral dose of Jardiance, a specific SGLT2 inhibitor. As a control, we also determined the effect of oral Jardiance on renal SGLT2 activity. RESULTS: In all five patients an oral dose (25 or 100 mg) of Jardiance reduced Me4FDG tumor accumulation, highly significant inhibition in four, and inhibited SGLT2 activity in the kidney. CONCLUSIONS: These initial experiments show that SGLT2 is a functional glucose transporter in astocytomas, and Jardiance inhibited glucose uptake, a drug approved by the FDA to treat type 2 diabetes mellitus (T2DM), heart failure, and renal failure. We suggest that clinical trials be initiated to determine whether Jardiance reduces astrocytoma growth in patients.

Influence of Sonication on the Molecular Characteristics of Carbopol® and Its Rheological Behavior in Microgels.

In this work, the effect of sonication on the molecular characteristics of polyacrylic acid (Carbopol® Ultrez 10), as well as on its rheological behavior in aqueous dispersions and microgels, was analyzed for the first time by rheometry, weight-average molecular weight (Mw) measurements via static light scattering (SLS), Fourier transform infrared (FTIR) spectroscopy and confocal microscopy. For this, the precursor dispersion and the microgels containing 0.25 wt.% of Ultrez 10 were sonicated in a commercial ultrasound bath at constant power and at different times. The main rheological properties of the microgel, namely, shear modulus, yield stress and viscosity, all decreased with increasing sonication time, while the microgel's Herschel-Bulkley (H-B) behavior, without thixotropy, was preserved. Also, Mw of Ultrez 10 decreased up to almost one-third (109,212 g/mol) of its original value (300,860 g/mol) after 180 min of sonication. These results evidence a softening of the gel microstructure, which results from the reduction in the Mw of polyacrylic acid with sonication time. Separately, FTIR measurements show that sonication produces scission in the C-C links of the Carbopol® backbone, which results in chains with the same chemistry but lower molecular weight. Finally, confocal microscopy observations revealed a diminution of the size of the microsponge domains and more free solvent with sonication time, which is reflected in a less compact and softer microstructure. The present results indicate that both the microstructure and the rheological behavior of Carbopol® microgels, in particular, and complex fluids, in general, may be manipulated or tailored by systematic high-power ultrasonication.

Standardized Parts for Activation of Small GTPase Signaling in Living Cells.

Small GTPases comprise a superfamily of over 167 proteins in the human genome and are critical regulators of a variety of pathways including cell migration and proliferation. Despite the importance of these proteins in cell signaling, a standardized approach for controlling small GTPase activation within living cells is lacking. Herein, we report a split-protein-based approach to directly activate small GTPase signaling in living cells. Importantly, our fragmentation site can be applied across the small GTPase superfamily. We highlight the utility of these standardized parts by demonstrating the ability to directly modulate the activity of four different small GTPases with user-defined inputs, providing the first plug and play system for direct activation of small GTPases in living cells.

Neural progenitor-derived Apelin controls tip cell behavior and vascular patterning.

During angiogenesis, vascular tip cells guide nascent vascular sprouts to form a vascular network. Apelin, an agonist of the G protein-coupled receptor Aplnr, is enriched in vascular tip cells, and it is hypothesized that vascular-derived Apelin regulates sprouting angiogenesis. We identify an apelin-expressing neural progenitor cell population in the dorsal neural tube. Vascular tip cells exhibit directed elongation and migration toward and along the apelin-expressing neural progenitor cells. Notably, restoration of neural but not vascular apelin expression in apelin mutants remedies the angiogenic defects of mutants. By functional analyses, we show the requirement of Apelin signaling for tip cell behaviors, like filopodia formation and cell elongation. Through genetic interaction studies and analysis of transgenic activity reporters, we identify Apelin signaling as a modulator of phosphoinositide 3-kinase and extracellular signal-regulated kinase signaling in tip cells in vivo. Our results suggest a previously unidentified neurovascular cross-talk mediated by Apelin signaling that is important for tip cell function during sprouting angiogenesis.

"Modeling Diffusive Search by Non-Adaptive Sperm: Empirical and Computational Insights".

During fertilization, mammalian sperm undergo a winnowing selection process that reduces the candidate pool of potential fertilizers from ~106-1011 cells to 101-102 cells (depending on the species). Classical sperm competition theory addresses the positive or 'stabilizing' selection that acts on sperm phenotypes within populations of organisms but does not strictly address the developmental consequences of sperm traits among individual organisms that are under purifying selection during fertilization. It is the latter that is of utmost concern for improving assisted reproductive technologies (ART) because 'low fitness' sperm may be inadvertently used for fertilization during interventions that rely heavily on artificial sperm selection, such as intracytoplasmic sperm injection (ICSI). Importantly, some form of sperm selection is used in nearly all forms of ART (e.g., differential centrifugation, swim-up, or hyaluronan binding assays, etc.). To date, there is no unifying quantitative framework (i.e., theory of sperm selection) that synthesizes causal mechanisms of selection with observed natural variation in individual sperm traits. In this report, we reframe the physiological function of sperm as a collective diffusive search process and develop multi-scale computational models to explore the causal dynamics that constrain sperm 'fitness' during fertilization. Several experimentally useful concepts are developed, including a probabilistic measure of sperm 'fitness' as well as an information theoretic measure of the magnitude of sperm selection, each of which are assessed under systematic increases in microenvironmental selective pressure acting on sperm motility patterns.