The role of memory-based movements in the formation of animal home ranges.

Most animals live in spatially-constrained home ranges. The prevalence of this space-use pattern in nature suggests that general biological mechanisms are likely to be responsible for their occurrence. Individual-based models of animal movement in both theoretical and empirical settings have demonstrated that the revisitation of familiar areas through memory can lead to the formation of stable home ranges. Here, we formulate a deterministic, mechanistic home range model that includes the interplay between a bi-component memory and resource preference, and evaluate resulting patterns of space-use. We show that a bi-component memory process can lead to the formation of stable home ranges and control its size, with greater spatial memory capabilities being associated with larger home range size. The interplay between memory and resource preferences gives rise to a continuum of space-use patterns-from spatially-restricted movements into a home range that is influenced by local resource heterogeneity, to diffusive-like movements dependent on larger-scale resource distributions, such as in nomadism. Future work could take advantage of this model formulation to evaluate the role of memory in shaping individual performance in response to varying spatio-temporal resource patterns.

Efficacy of Wolbachia-based mosquito control: Predictions of a spatially discrete mathematical model.

Wolbachia is an endosymbiont bacterium present in many insect species. When Wolbachia-carrying male Aedes aegypti mosquitoes mate with non-carrier females, their embryos are not viable due to cytoplasmic incompatibility. This phenomenon has been exploited successfully for the purpose of controlling mosquito populations and the spread of mosquito-borne illnesses: Wolbachia carriers are bred and released into the environment. Because Wolbachia is not harmful to humans, this method of mosquito control is regarded as a safer alternative to pesticide spraying. In this article, we introduce a mathematical framework for exploring (i) whether a one-time release of Wolbachia carriers can elicit a sustained presence of carriers near the release site, and (ii) the extent to which spatial propagation of carriers may allow them to establish fixation in other territories. While some prior studies have formulated mosquito dispersal models using advection-reaction-diffusion PDEs, the predictive power of such models requires careful ecological mapping: advection and diffusion coefficients exhibit significant spatial dependence due to heterogeneity of resources and topography. Here, we adopt a courser-grained view, regarding the environment as a network of discrete, diffusively-coupled "habitats"-distinct zones of high mosquito density such as stagnant ponds. We extend two previously published single-habitat mosquito models to multiple habitats, and calculate rates of migration between pairs of habitats using dispersal kernels. Our primary results are quantitative estimates regarding how the success of carrier fixation in one or more habitats is determined by: the number of carriers released, sizes of habitats, distances between habitats, and the rate of migration between habitats. Besides yielding sensible and potentially useful predictions regarding the success of Wolbachia-based control, our framework applies to other approaches (e.g., gene drives) and contexts beyond the realm of insect pest control.

Direct Characterization of Buried Interfaces in 2D/3D Heterostructures Enabled by GeO2 Release Layer.

Inconsistent interface control in devices based on two-dimensional materials (2DMs) has limited technological maturation. Astounding variability of 2D/three-dimensional (2D/3D) interface properties has been reported, which has been exacerbated by the lack of direct investigations of buried interfaces commonly found in devices. Herein, we demonstrate a new process that enables the assembly and isolation of device-relevant heterostructures for buried interface characterization. This is achieved by implementing a water-soluble substrate (GeO2), which enables deposition of many materials onto the 2DM and subsequent heterostructure release by dissolving the GeO2 substrate. Here, we utilize this novel approach to compare how the chemistry, doping, and strain in monolayer MoS2 heterostructures fabricated by direct deposition vary from those fabricated by transfer techniques to show how interface properties differ with the heterostructure fabrication method. Direct deposition of thick Ni and Ti films is found to react with the monolayer MoS2. These interface reactions convert 50% of MoS2 into intermetallic species, which greatly exceeds the 10% conversion reported previously and 0% observed in transfer-fabricated heterostructures. We also measure notable differences in MoS2 carrier concentration depending on the heterostructure fabrication method. Direct deposition of thick Au, Ni, and Al2O3 films onto MoS2 increases the hole concentration by >1012 cm-2 compared to heterostructures fabricated by transferring MoS2 onto these materials. Thus, we demonstrate a universal method to fabricate 2D/3D heterostructures and expose buried interfaces for direct characterization.

Cavernous sinus haemangioma: systematic review and pooled analysis relating to a rare skull base pathology.

Cavernous sinus haemangiomas (CSHs) are rare malformations of the microcirculation arising from the cavernous sinus. A systematic review and pooled data analysis of the associated clinical features, diagnostic modalities, management, and outcomes for CSHs was done. In total, 68 articles (338 cases) were eligible for analysis based on our selection criteria. The primary outcome measures were the occurrence of (i) and (ii) symptom resolution/improvement. Categorical outcome variables were assessed by binary logistic regression at 5% significance level. With headaches (39.9%) and diplopia (36.5%) as the most common presenting symptoms reported, dynamic contrast-enhanced MRI was the most commonly used diagnostic modality and was the most definitive pre-treatment imaging modality for diagnosing CSH with a sensitivity of 89.5%. The majority of CSHs were managed with radiosurgery (47.9% of cases), 37.9% by surgical resection alone, and 14.2% by a combination of both. Compared to patients that were treated with surgical resection only, those treated solely with radiosurgery had a 100% decrease in the odds of developing post-treatment complications (adjusted OR: 0.00, 95% CI: 0.00-0.002, p < 0.001), with a 5.03 times greater odds of symptom resolution/improvement (adjusted OR: 5.03, 95% CI: 1.89-13.4, p = 0.001). Patients that underwent combined therapy had a 79% reduction in risk of developing post-treatment complications (adjusted OR: 0.21, 95% CI: 0.06-0.68, p = 0.01), with no statistically significant difference in the odds of symptom resolution/improvement, compared to those that had surgery only. In conclusion, radiosurgery offered the best outcomes with regards to symptom resolution/improvement and post-treatment complications in patients with CSH.

Phylogenomic analyses of the genus Drosophila reveals genomic signals of climate adaptation.

Many Drosophila species differ widely in their distributions and climate niches, making them excellent subjects for evolutionary genomic studies. Here, we have developed a database of high-quality assemblies for 46 Drosophila species and one closely related Zaprionus. Fifteen of the genomes were newly sequenced, and 20 were improved with additional sequencing. New or improved annotations were generated for all 47 species, assisted by new transcriptomes for 19. Phylogenomic analyses of these data resolved several previously ambiguous relationships, especially in the melanogaster species group. However, it also revealed significant phylogenetic incongruence among genes, mainly in the form of incomplete lineage sorting in the subgenus Sophophora but also including asymmetric introgression in the subgenus Drosophila. Using the phylogeny as a framework and taking into account these incongruences, we then screened the data for genome-wide signals of adaptation to different climatic niches. First, phylostratigraphy revealed relatively high rates of recent novel gene gain in three temperate pseudoobscura and five desert-adapted cactophilic mulleri subgroup species. Second, we found differing ratios of nonsynonymous to synonymous substitutions in several hundred orthologues between climate generalists and specialists, with trends for significantly higher ratios for those in tropical and lower ratios for those in temperate-continental specialists respectively than those in the climate generalists. Finally, resequencing natural populations of 13 species revealed tropics-restricted species generally had smaller population sizes, lower genome diversity and more deleterious mutations than the more widespread species. We conclude that adaptation to different climates in the genus Drosophila has been associated with large-scale and multifaceted genomic changes.

An Early Case of Fat Embolism Syndrome Occurring Following Polytrauma.

Fat embolism syndrome (FES) is a clinical entity occurring due to the presence of fat particles in the microcirculation, typically manifesting 12-72 hours after long bone trauma with respiratory distress, altered mental status, and petechial rash. Our case is that of a 17-year-old girl who suffered multiple orthopedic injuries without intracranial trauma after being a pedestrian struck by a vehicle. Despite presenting with a normal Glasgow Coma Score (GCS), within 4 hours of presentation, she was noted to have an acute mental status change to a GCS 7 with a normal computed tomography brain. Magnetic resonance imaging of the brain was suggestive of FES which, in this patient, had a rapidly progressing course with the development of severe cerebral edema and intracranial hypertension refractory to maximal medical therapy. Our patient required bilateral craniectomies for intracranial decompression and progressed over a 2-month hospital course to have subsequent cranioplasty and functional neurologic improvement. FES requires a high index of clinical suspicion in the presence of long bone fracture with unexplained altered mental status. The clinical course can be rapidly progressing with the development of intracranial hypertension which may benefit from surgical decompression with optimistic prognosis.

Pulmonary and Extra-Pulmonary Clinical Manifestations of COVID-19.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has been recently identified as the culprit of the highly infectious, outbreak named coronavirus disease 2019 (COVID-19) in China. Now declared a public health emergency, this pandemic is present in more than 200 countries with over 14 million cases and 600,000 deaths as of July 18, 2020. Primarily transmitted through the respiratory tract, the most common clinical presentations of symptomatic individuals infected with SARS-CoV-2 include fever, dyspnea, cough, fatigue, and sore throat. In advanced cases, patients may rapidly develop respiratory failure with acute respiratory distress syndrome, and even progress to death. While it is known that COVID-19 manifests similarly to the 2003 Severe Acute Respiratory Syndrome (SARS) and the 2012 Middle East Respiratory Syndrome (MERS), primarily affecting the pulmonary system, the impact of the disease extends far beyond the respiratory system and affects other organs of the body. The literature regarding the extrapulmonary manifestations (cardiovascular, renal, hepatic, gastrointestinal, ocular, dermatologic, and neurological) of COVID-19 is scant. Herein, we provide a comprehensive review of the organ-specific clinical manifestations of COVID-19, to increase awareness about the various organs affected by SARS-CoV-2 and to provide a brief insight into the similarities and differences in the clinical manifestations of COVID-19 and the earlier SARS and MERS.

The whale shark genome reveals how genomic and physiological properties scale with body size.

The endangered whale shark (Rhincodon typus) is the largest fish on Earth and a long-lived member of the ancient Elasmobranchii clade. To characterize the relationship between genome features and biological traits, we sequenced and assembled the genome of the whale shark and compared its genomic and physiological features to those of 83 animals and yeast. We examined the scaling relationships between body size, temperature, metabolic rates, and genomic features and found both general correlations across the animal kingdom and features specific to the whale shark genome. Among animals, increased lifespan is positively correlated to body size and metabolic rate. Several genomic traits also significantly correlated with body size, including intron and gene length. Our large-scale comparative genomic analysis uncovered general features of metazoan genome architecture: Guanine and cytosine (GC) content and codon adaptation index are negatively correlated, and neural connectivity genes are longer than average genes in most genomes. Focusing on the whale shark genome, we identified multiple features that significantly correlate with lifespan. Among these were very long gene length, due to introns being highly enriched in repetitive elements such as CR1-like long interspersed nuclear elements, and considerably longer neural genes of several types, including connectivity, activity, and neurodegeneration genes. The whale shark genome also has the second slowest evolutionary rate observed in vertebrates to date. Our comparative genomics approach uncovered multiple genetic features associated with body size, metabolic rate, and lifespan and showed that the whale shark is a promising model for studies of neural architecture and lifespan.

DNAJC6 Mutations Disrupt Dopamine Homeostasis in Juvenile Parkinsonism-Dystonia.

BACKGROUND: Juvenile forms of parkinsonism are rare conditions with onset of bradykinesia, tremor and rigidity before the age of 21 years. These atypical presentations commonly have a genetic aetiology, highlighting important insights into underlying pathophysiology. Genetic defects may affect key proteins of the endocytic pathway and clathrin-mediated endocytosis (CME), as in DNAJC6-related juvenile parkinsonism. OBJECTIVE: To report on a new patient cohort with juvenile-onset DNAJC6 parkinsonism-dystonia and determine the functional consequences on auxilin and dopamine homeostasis. METHODS: Twenty-five children with juvenile parkinsonism were identified from a research cohort of patients with undiagnosed pediatric movement disorders. Molecular genetic investigations included autozygosity mapping studies and whole-exome sequencing. Patient fibroblasts and CSF were analyzed for auxilin, cyclin G-associated kinase and synaptic proteins. RESULTS: We identified 6 patients harboring previously unreported, homozygous nonsense DNAJC6 mutations. All presented with neurodevelopmental delay in infancy, progressive parkinsonism, and neurological regression in childhood. 123 I-FP-CIT SPECT (DaTScan) was performed in 3 patients and demonstrated reduced or absent tracer uptake in the basal ganglia. CSF neurotransmitter analysis revealed an isolated reduction of homovanillic acid. Auxilin levels were significantly reduced in both patient fibroblasts and CSF. Cyclin G-associated kinase levels in CSF were significantly increased, whereas a number of presynaptic dopaminergic proteins were reduced. CONCLUSIONS: DNAJC6 is an emerging cause of recessive juvenile parkinsonism-dystonia. DNAJC6 encodes the cochaperone protein auxilin, involved in CME of synaptic vesicles. The observed dopamine dyshomeostasis in patients is likely to be multifactorial, secondary to auxilin deficiency and/or neurodegeneration. Increased patient CSF cyclin G-associated kinase, in tandem with reduced auxilin levels, suggests a possible compensatory role of cyclin G-associated kinase, as observed in the auxilin knockout mouse. DNAJC6 parkinsonism-dystonia should be considered as a differential diagnosis for pediatric neurotransmitter disorders associated with low homovanillic acid levels. Future research in elucidating disease pathogenesis will aid the development of better treatments for this pharmacoresistant disorder. © 2020 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Apcdd1 is a dual BMP/Wnt inhibitor in the developing nervous system and skin.

Animal development and homeostasis depend on precise temporal and spatial intercellular signaling. Components shared between signaling pathways, generally thought to decrease specificity, paradoxically can also provide a solution to pathway coordination. Here we show that the Bone Morphogenetic Protein (BMP) and Wnt signaling pathways share Apcdd1 as a common inhibitor and that Apcdd1 is a taxon-restricted gene with novel domains and signaling functions. Previously, we showed that Apcdd1 inhibits Wnt signaling (Shimomura et al., 2010), here we find that Apcdd1 potently inhibits BMP signaling in body axis formation and neural differentiation in chicken, frog, zebrafish. Furthermore, we find that Apcdd1 has an evolutionarily novel protein domain. Our results from experiments and modeling suggest that Apcdd1 may coordinate the outputs of two signaling pathways that are central to animal development and human disease.

Modeling action potential reversals in tunicate hearts.

Tunicates are small invertebrates which possess a unique ability to reverse flow in their hearts. Scientists have debated various theories regarding how and why flow reversals occur. Here we explore the electrophysiological basis for reversals by simulating action potential propagation in an idealized model of the tubelike tunicate heart. Using asymptotic formulas for action potential duration and conduction velocity, we propose tunicate-specific parameters for a two-current ionic model of the action potential. Then, using a kinematic model, we derive analytical criteria for reversals to occur. These criteria inform subsequent numerical simulations of action potential propagation in a fiber paced at both ends. In particular, we explore the role that variability of pacemaker firing rates plays in generating reversals, and we identify various favorable conditions for triggering retrograde propagation. Our analytical framework extends to other species; for instance, it can be used to model competition between the sinoatrial node and abnormal ectopic foci in human heart tissue.

Aortic Pulsatility Propagates Intracranially and Correlates with Dilated Perivascular Spaces and Small Vessel Compliance.

INTRODUCTION: To test the hypotheses that changes in the aortic pulse-wave produced by arterial stiffening are (1) propagated into cerebral small vessels, (2) associated with reduced compliance of small cerebral arterial vessels, and (3) associated with the presence of dilated perivascular spaces (PVS). METHODS: Fifteen volunteers and 19 patients with late-onset depression (LOD) were prospectively recruited, of which 6 fulfilled the criteria for treatment-resistant depression (TRD). Aortic pulse-wave velocity (PWV) was determined using Carotid-Femoral Doppler. Pulse-wave analysis (PWA) was performed using a SphygmoCor system. White-matter lesion load and PVS were scored on established MRI scales. Cerebral arterial and aqueductal cerebrospinal fluid (CSF) flow patterns were studied using quantitative phase-contrast angiography. RESULTS: Depressed patients had more PVS (P < .05) and prolongation of the width of the arterial systolic pulse-wave in the carotid arteries (P < .01). There was no significant group difference for any PWV or PWA measurement. TRD patients showed more PVS than other LOD patients (P < .05). The fractional width of the arterial systolic peak correlated significantly with augmentation index (AIx) and heart rate-corrected augmentation index (AIx75; R2 = 0.302, P < .01and R2 = 0.363, P < .01 respectively). Arterial-aqueductal delay showed a negative correlation with estimated aortic systolic pressure (PWVsys; R2 =  0.293; P < .01), AIx (R2 = -0.491; P < .01) and AIx75 (R2 = -0.310; P < .01). PVS scores correlated with AIx (R2 = 0.485; P < .01) and AIx75 (R2 = -0.292; P < .01). CONCLUSION: Our findings support the hypothesis that increased arterial pulsatility resulting from central arterial stiffness propagates directly into cerebral vessels and is associated with the development of microvascular angiopathy, characterized by dilated PVS and decreased compliance of small arterial vessels.

Colovesical Fistula As An Uncommon Presentation Of Metastatic Lung Cancer.

Colovesical fistula is an atypical communication between the colon and the bladder. The most common causes of colovesical fistula are diverticulitis, inflammatory bowel disease, lymphoma and complication from radiation therapy. Patients with colovesical fistula present with recurrent urinary tract infections (UTI), dysuria, frequency, abdominal pain, pneumaturia, faecaluria, and hematuria. We present a case of a patient with stage IV lung adenocarcinoma presented with abdominal pain, dysuria, and faecaluria who was found to have a colovesical fistula. Although colovesical fistula may be sequelae of advanced colon or bladder cancer, it is a very uncommon presentation of metastatic cancer from distant sites. Our case is the first to show that colovesical fistula may present from metastatic lung adenocarcinoma. Clinical awareness of this very unusual presentation of metastatic cancer can lead to faster diagnosis and treatment, possibly minimizing excessive use of antibiotics.

Control of the Speed of a Light-Induced Spin Transition through Mesoscale Core-Shell Architecture.

The rate of the light-induced spin transition in a coordination polymer network solid dramatically increases when included as the core in mesoscale core-shell particles. A series of photomagnetic coordination polymer core-shell heterostructures, based on the light-switchable Rb aCo b[Fe(CN)6] c· mH2O (RbCoFe-PBA) as core with the isostructural K jNi k[Cr(CN)6] l· nH2O (KNiCr-PBA) as shell, are studied using temperature-dependent powder X-ray diffraction and SQUID magnetometry. The core RbCoFe-PBA exhibits a charge transfer-induced spin transition (CTIST), which can be thermally and optically induced. When coupled to the shell, the rate of the optically induced transition from low spin to high spin increases. Isothermal relaxation from the optically induced high spin state of the core back to the low spin state and activation energies associated with the transition between these states were measured. The presence of a shell decreases the activation energy, which is associated with the elastic properties of the core. Numerical simulations using an electro-elastic model for the spin transition in core-shell particles supports the findings, demonstrating how coupling of the core to the shell changes the elastic properties of the system. The ability to tune the rate of optically induced magnetic and structural phase transitions through control of mesoscale architecture presents a new approach to the development of photoswitchable materials with tailored properties.

The Utility of FDG-PET/CT in Clinically Suspected Paraneoplastic Neurological Syndrome: A Literature Review and Retrospective Case Series.

Paraneoplastic neurological syndrome (PNS) describes a spectrum of rare, heterogeneous neurological conditions associated with an underlying malignancy. Diagnosis of PNS is inherently difficult, with frequent misdiagnosis and delay. The literature suggests an underlying immune-mediated pathophysiology, and patients are usually tested for the presence of onconeural antibodies. With direct tumor therapy being the most effective method of stabilizing patients, there is a strong emphasis on detecting underlying tumors. The sensitivity of conventional CT imaging is often inadequate in such patients. While FDG-PET imaging has already been shown to be effective at detecting these tumors, FDG-PET/CT, combining both structural and functional imaging in a single study, is a more recent technique. To study the utility of FDG-PET/CT, we conducted a systematic literature review and a retrospective study. We identified 41 patients who underwent imaging for clinically suspected PNS at the regional PET-CT and neurosciences center based at the Royal Preston Hospital between 2007 and 2014 and compared the results to conventional investigations. Five patients had FDG-PET/CT tracer avidity suspicious of malignant disease, and four of these were subsequently diagnosed with cancer. Sensitivity and specificity were calculated to be 100 and 97.3%, respectively, with positive predictive value 80% and negative predictive value 100%. This compares to a sensitivity and specificity of 50 and 100%, respectively, for CT and 50 and 89%, respectively, for onconeural antibodies. These findings are in line with previous studies and support the diagnostic accuracy of FDG-PET/CT for the detection of underlying malignancy.

Swyer-James-MacLeod syndrome with unilateral pulmonary fibrosis: a case report.

Swyer-James-MacLeod syndrome is a rare, complex disease characterized by the radiological finding of unilateral hyperlucent lung due to pulmonary oligaemia and alveolar hyperdistention as a consequence of previous obliterative bronchiolitis (bronchiolitis obliterans). Idiopathic pulmonary fibrosis is a chronic, progressive, fibrosing interstitial pneumonia of unknown cause characterized by bilateral, chronic, progressive and irreversible fibrosis limited to the lungs. We report an interesting case of Swyer-James-MacLeod syndrome affecting one lung and Idiopathic pulmonary fibrosis affecting the contralateral lung.

Synergistic photomagnetic effects in coordination polymer heterostructure particles of Hofmann-like Fe(4-phenylpyridine)2[Ni(CN)4]·0.5H2O and K0.4Ni[Cr(CN)6]0.8·nH2O.

New nanometer scale heterostructure particles of the two-dimensional Hofmann-like Fe(ii) spin-crossover network, Fe(phpy)2[Ni(CN)4]·0.5H2O {phpy = 4-phenylpyridine}, and the Prussian blue analogue K0.4Ni1.0[Cr(CN)6]0.8·nH2O (NiCr-PBA) have been developed, exhibiting synergistic photomagnetic effects, whereby the LIESST (light-induced electron spin-state trapping) effect in the Hofmann-like material induces a magnetization change in the NiCr-PBA. A variety of microscopic and spectroscopic techniques demonstrate the heterogeneous growth of the NiCr-PBA on the Hofmann seed particles and show the Hofmann compound retains its thermal and photoinduced spin transition properties in the heterostructure. The photoinduced magnetization change in the NiCr-PBA network arises from coupling of the two lattices despite dissimilar structure types. Isothermal magnetization minor hysteresis loop studies at 5 K show light absorption leads to changes in the local anisotropy of NiCr-PBA magnetic domains, providing direct evidence for a general magnetomechanical mechanism of light-switchable magnetism in coordination polymer heterostructures combining a photoactive material with a magnet.

Primary Open Angle Glaucoma is Associated with MR Biomarkers of Cerebral Small Vessel Disease.

This prospective study tests the hypotheses that: 1) glaucoma is associated with evidence of cerebral small vessel disease; 2) that imaging biomarkers of cerebral small vessel disease in POAG and NTG will show different characteristics. 12 normal controls, 7 patients with primary open angle glaucoma (POAG) and 9 patients with normal tension glaucoma (NTG) were recruited. Ophthalmological clinical assessment and MR imaging of the brain were performed. MR imaging was used to quantify white matter lesion load, frequency of dilated perivascular spaces (PVS) and abnormalities in cerebral hydrodynamics. Patients with POAG had significantly greater white matter lesion load (p < 0.05), more PVS in the centrum semiovale (p < 0.05) and had higher overall PVS scores than controls (p < 0.05). In the POAG group, optic cup-to-disc ratio (CDR) was positively correlated with deep white matter hyperintensities (R(2) = 0.928, p < 0.01). Mean deviation on the Humphrey visual field assessment was negatively correlated with deep white matter lesion load (R(2) = -0.840, p < 0.01), total white matter lesion load (R(2) = -0.928, p < 0.01) and total PVS (R(2) = -0.820, p < 0.01). MR evidence of cerebral small vessel disease is strongly associated with a diagnosis of POAG and with the severity of abnormalities in CDR and visual field.

Introducing Dimensionality to the Archetypical Mn12 Single-Molecule Magnet: a Family of [Mn12]n Chains.

The [Mn12O12(O2CR)16(L4)] family (R = various; L = terminal ligand) of clusters holds a special place in molecular magnetism; they are the most well-studied single-molecule magnets (SMMs). Targeted linkage of these SMMs has now been achieved for the first time. The resulting chain structures have been confirmed crystallographically, and the magnetic properties, up to 1.14 GPa, and high-field electron paramagnetic resonance spectra have been collected and analyzed.

Live cell imaging of cytoplasmic dynein movement in transfected embryonic rat neurons.

Live cell imaging of the movement of various membrane-bounded organelle cargos has enhanced our understanding of their function. Eukaryotic cells utilize microtubules and two classes of microtubule-based motor proteins, cytoplasmic dynein and members of the kinesin family, to deliver a variety of membrane-bounded organelles and other cargos to their appropriate locations. In order to better understand the functions and regulation of cytoplasmic dynein, we developed a method to study its location and motility in living cells. The technique takes advantage of the long thin axons of cultured hippocampal neurons. We use calcium phosphate to transfect fluorescent-tagged dynein intermediate chain (IC) subunits (DYNC1I) into cultured neurons. When the ICs are expressed at low levels, they are effective probes for the location of the cytoplasmic dynein complex in axons when living cells are imaged with fluorescence microscopy. The fluorescent subunit probes can be used to identify specific cargos of dynein complexes with different IC isoforms as well as the kinetic properties of cytoplasmic dynein.