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1.
Carbon Balance Manag ; 19(1): 32, 2024 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-39294406

RESUMO

BACKGROUND: Ecosystem models are valuable tools to make climate-related assessments of change when ground-based measurements of water and carbon fluxes are not adequately detailed to realistically capture geographic variability. The Carnegie-Ames-Stanford Approach (CASA) is one such model based on satellite observations of monthly vegetation cover to estimate net primary production (NPP) of terrestrial ecosystems. RESULTS: CASA model predictions from 2015 to 2022 for Western Europe revealed several notable high and low periods in growing season NPP totals in most countries of the region. For the total land coverage of France, Greece, Italy, Portugal, and Spain, 2018 was the year with the highest terrestrial plant growth, whereas 2017 and 2019 were the years with the highest summed NPP across the UK, Germany, and Croatia. For most of Western Europe, 2022 was the year predicted with the lowest summed plant growth. Annual precipitation in most countries of Western Europe gradually declined from a high average rate in 2018 to a low average precipitation level in 2022. CONCLUSIONS: The CASA model predicted decreased growing season NPP of between - 25 and - 60% across all of Spain, southern France, and northern Italy from 2021 to 2022, and much of that plant production loss was detected in the important cropland regions of these nations.


Annual growth of terrestrial plant cover, also known as net primary production (NPP), must be maintained and managed by societies worldwide to meet their essential needs for food and fiber. A model of global NPP that uses monthly satellite images as inputs predicted that extreme drought in the years 2020 and 2021 across Western Europe, caused by greatly diminished precipitation totals and elevated temperatures, depressed plant production by between − 25 and − 60% compared to the previous five years in France, Italy, and Spain.

2.
Proc Mach Learn Res ; 248: 489-505, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-39224857

RESUMO

Unstructured data in Electronic Health Records (EHRs) often contains critical information-complementary to imaging-that could inform radiologists' diagnoses. But the large volume of notes often associated with patients together with time constraints renders manually identifying relevant evidence practically infeasible. In this work we propose and evaluate a zero-shot strategy for using LLMs as a mechanism to efficiently retrieve and summarize unstructured evidence in patient EHR relevant to a given query. Our method entails tasking an LLM to infer whether a patient has, or is at risk of, a particular condition on the basis of associated notes; if so, we ask the model to summarize the supporting evidence. Under expert evaluation, we find that this LLM-based approach provides outputs consistently preferred to a pre-LLM information retrieval baseline. Manual evaluation is expensive, so we also propose and validate a method using an LLM to evaluate (other) LLM outputs for this task, allowing us to scale up evaluation. Our findings indicate the promise of LLMs as interfaces to EHR, but also highlight the outstanding challenge posed by "hallucinations". In this setting, however, we show that model confidence in outputs strongly correlates with faithful summaries, offering a practical means to limit confabulations.

3.
Glob Chang Biol ; 30(6): e17374, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38863181

RESUMO

In this Technical Advance, we describe a novel method to improve ecological interpretation of remotely sensed vegetation greenness measurements that involved sampling 24,395 Landsat pixels (30 m) across 639 km of Alaska's central Brooks Range. The method goes well beyond the spatial scale of traditional plot-based sampling and thereby more thoroughly relates ground-based observations to satellite measurements. Our example dataset illustrates that, along the boreal-Arctic boundary, vegetation with the greatest Landsat Normalized Difference Vegetation Index (NDVI) is taller than 1 m, woody, and deciduous; whereas vegetation with lower NDVI tends to be shorter, evergreen, or non-woody. The field methods and associated analyses advance efforts to inform satellite data with ground-based vegetation observations using field samples collected at spatial scales that closely match the resolution of remotely sensed imagery.


Assuntos
Imagens de Satélites , Tundra , Alaska , Regiões Árticas , Tecnologia de Sensoriamento Remoto/métodos , Taiga , Monitoramento Ambiental/métodos
4.
J Vis Exp ; (201)2023 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-38047558

RESUMO

Mosquitoes are effective vectors of deadly diseases and can navigate their chemical environment using chemosensory receptors expressed in their olfactory appendages. Understanding how chemosensory receptors are spatially organized in the peripheral olfactory appendages can offer insights into how odor is encoded in the mosquito olfactory system and inform new ways to combat the spread of mosquito-borne diseases. The emergence of third-generation hybridization chain reaction RNA whole-mount fluorescence in situ hybridization (HCR RNA WM-FISH) allows for spatial mapping and simultaneous expression profiling of multiple chemosensory genes. Here, we describe a stepwise approach for performing HCR RNA WM-FISH on the Anopheles mosquito antenna and maxillary palp. We investigated the sensitivity of this technique by examining the expression profile of ionotropic olfactory receptors. We asked if the HCR WM-FISH technique described was suitable for multiplexed studies by tethering RNA probes to three spectrally distinct fluorophores. Results provided evidence that HCR RNA WM-FISH is robustly sensitive to simultaneously detect multiple chemosensory genes in the antenna and maxillary palp olfactory appendages. Further investigations attest to the suitability of HCR WM-FISH for co-expression profiling of double and triple RNA targets. This technique, when applied with modifications, could be adaptable to localize genes of interest in the olfactory tissues of other insect species or in other appendages.


Assuntos
Anopheles , Receptores Odorantes , Animais , RNA/metabolismo , Hibridização in Situ Fluorescente , Mosquitos Vetores , Olfato/genética , Anopheles/genética , Receptores Odorantes/genética , Receptores Odorantes/metabolismo
5.
iScience ; 26(5): 106690, 2023 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-37182106

RESUMO

Anopheles mosquitoes, as vectors for the malaria parasite, are a global threat to human health. To find and bite a human, they utilize neurons within their sensory appendages. However, the identity and quantification of sensory appendage neurons are lacking. Here we use a neurogenetic approach to label all neurons in Anopheles coluzzii mosquitoes. We utilize the homology assisted CRISPR knock-in (HACK) approach to generate a T2A-QF2w knock-in of the synaptic gene bruchpilot. We use a membrane-targeted GFP reporter to visualize the neurons in the brain and to quantify neurons in all major chemosensory appendages (antenna, maxillary palp, labella, tarsi, and ovipositor). By comparing labeling of brp>GFP and Orco>GFP mosquitoes, we predict the extent of neurons expressing ionotropic receptors (IRs) or other chemosensory receptors. This work introduces a valuable genetic tool for the functional analysis of Anopheles mosquito neurobiology and initiates characterization of the sensory neurons that guide mosquito behavior.

6.
J Am Coll Radiol ; 20(5S): S102-S124, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-37236738

RESUMO

Vertebral compression fractures (VCFs) can have a variety of etiologies, including trauma, osteoporosis, or neoplastic infiltration. Osteoporosis related fractures are the most common cause of VCFs and have a high prevalence among all postmenopausal women with increasing incidence in similarly aged men. Trauma is the most common etiology in those >50 years of age. However, many cancers, such as breast, prostate, thyroid, and lung, have a propensity to metastasize to bone, which can lead to malignant VCFs. Indeed, the spine is third most common site of metastases after lung and liver. In addition, primary tumors of bone and lymphoproliferative diseases such as lymphoma and multiple myeloma can be the cause of malignant VCFs. Although patient clinical history could help raising suspicion for a particular disorder, the characterization of VCFs is usually referred to diagnostic imaging. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.


Assuntos
Fraturas por Compressão , Osteoporose , Fraturas da Coluna Vertebral , Masculino , Humanos , Feminino , Estados Unidos , Idoso , Fraturas da Coluna Vertebral/diagnóstico por imagem , Fraturas da Coluna Vertebral/terapia , Fraturas por Compressão/diagnóstico por imagem , Fraturas por Compressão/terapia , Osso e Ossos , Sociedades Médicas
7.
J Clin Oncol ; 41(17): 3160-3171, 2023 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-37027809

RESUMO

PURPOSE: The Response Assessment in Neuro-Oncology (RANO) criteria are widely used in high-grade glioma clinical trials. We compared the RANO criteria with updated modifications (modified RANO [mRANO] and immunotherapy RANO [iRANO] criteria) in patients with newly diagnosed glioblastoma (nGBM) and recurrent GBM (rGBM) to evaluate the performance of each set of criteria and inform the development of the planned RANO 2.0 update. MATERIALS AND METHODS: Evaluation of tumor measurements and fluid-attenuated inversion recovery (FLAIR) sequences were performed by blinded readers to determine disease progression using RANO, mRANO, iRANO, and other response assessment criteria. Spearman's correlations between progression-free survival (PFS) and overall survival (OS) were calculated. RESULTS: Five hundred twenty-six nGBM and 580 rGBM cases were included. Spearman's correlations were similar between RANO and mRANO (0.69 [95% CI, 0.62 to 0.75] v 0.67 [95% CI, 0.60 to 0.73]) in nGBM and rGBM (0.48 [95% CI, 0.40 to 0.55] v 0.50 [95% CI, 0.42 to 0.57]). In nGBM, requirement of a confirmation scan within 12 weeks of completion of radiotherapy to determine progression was associated with improved correlations. Use of the postradiation magnetic resonance imaging (MRI) as baseline scan was associated with improved correlation compared with use of the pre-radiation MRI (0.67 [95% CI, 0.60 to 0.73] v 0.53 [95% CI, 0.42 to 0.62]). Evaluation of FLAIR sequences did not improve the correlation. Among patients who received immunotherapy, Spearman's correlations were similar among RANO, mRANO, and iRANO. CONCLUSION: RANO and mRANO demonstrated similar correlations between PFS and OS. Confirmation scans were only beneficial in nGBM within 12 weeks of completion of radiotherapy, and there was a trend in favor of the use of postradiation MRI as the baseline scan in nGBM. Evaluation of FLAIR can be omitted. The iRANO criteria did not add significant benefit in patients who received immune checkpoint inhibitors.


Assuntos
Neoplasias Encefálicas , Glioblastoma , Glioma , Humanos , Glioblastoma/terapia , Glioblastoma/tratamento farmacológico , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/terapia , Glioma/tratamento farmacológico , Imageamento por Ressonância Magnética/métodos , Imunoterapia
8.
Radiol Clin North Am ; 61(3): 445-456, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36931761

RESUMO

There is constant evolution in the diagnosis and treatment of acute ischemic stroke due to advances in treatments, imaging, and outreach. Two major revolutions were the advent of intravenous thrombolysis in the 1990s and endovascular thrombectomy in 2010s. Neuroimaging approaches have also evolved with key goals-detect hemorrhage, augment thrombolysis treatment selection, detect arterial occlusion, estimate infarct core, estimate viable penumbra, and augment thrombectomy treatment selection. The ideal approach to diagnosis and treatment may differ depending on the system of care and available resources. Future directions include expanding indications for these treatments, including a shift from time-based to tissue-based selection.


Assuntos
Isquemia Encefálica , AVC Isquêmico , Acidente Vascular Cerebral , Humanos , Isquemia Encefálica/diagnóstico por imagem , Isquemia Encefálica/terapia , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/terapia , Tomografia Computadorizada por Raios X/métodos , Imageamento por Ressonância Magnética/métodos , Perfusão , Resultado do Tratamento , Imagem de Perfusão
9.
Cell Rep ; 42(2): 112101, 2023 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-36773296

RESUMO

The mosquito's antenna represents its main olfactory appendage for detecting volatile chemical cues from the environment. Whole-mount fluorescence in situ hybridization of ionotropic receptors (IRs) expressed in the antennae reveals that the antenna might be divisible into proximal and distal functional domains. The number of IR-positive cells appear stereotyped within each antennal segment (flagellomere). Highly expressed odor-tuning IRs exhibit distinct co-localization patterns with the IR coreceptors Ir8a, Ir25a, and Ir76b that might predict their functional properties. Genetic knockin and in vivo functional imaging of IR41c-expressing neurons indicate both odor-induced activation and inhibition in response to select amine compounds. Targeted mutagenesis of IR41c does not abolish behavioral responses to the amine compounds. Our study provides a comprehensive map of IR-expressing neurons in the main olfactory appendage of mosquitoes. These findings show organizing principles of Anopheles IR-expressing neurons, which might underlie their functional contribution to the detection of behaviorally relevant odors.


Assuntos
Anopheles , Malária , Receptores Odorantes , Animais , Hibridização in Situ Fluorescente , Olfato , Odorantes , Receptores Odorantes/genética
10.
Curr Opin Insect Sci ; 54: 100967, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36096415

RESUMO

Half the world's human population is at risk for mosquito-borne diseases. Mosquitoes rely mainly on their sense of smell to find a vertebrate blood host, nectar source, and a suitable oviposition site. Advances in neurogenetic tools have now aided our understanding of the receptors that mediate the detection of sensory cues that emanate from humans. Recent studies in the anthropophilic mosquito vectors, Aedes aegypti and Anopheles gambiae, have implicated the chemosensory ionotropic-receptor (IR) family in the detection of behaviorally relevant odors and uncovered functions beyond chemical sensing. Here, we highlight the multifunctional roles of the chemosensory ionotropic receptors in anthropophilic mosquito vectors and suggest future directions to improve our understanding of the IR family.


Assuntos
Aedes , Anopheles , Feminino , Humanos , Animais , Mosquitos Vetores/fisiologia , Olfato , Odorantes
11.
Cold Spring Harb Protoc ; 2022(11): Pdb.prot107918, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-35960624

RESUMO

Calcium imaging is a technique used to measure functional neuronal activities in response to stimuli. It has been used for years to study odorant-induced responses in insects (i.e., honeybees, Drosophila, and moths) and was recently introduced into mosquitoes. Traditionally, calcium imaging in mosquitoes was performed using nonspecific calcium indicator dyes to examine neuronal responses in whole insect brain regions, but the development of genetically encoded calcium indicators (GECIs) has facilitated the ability to perform functional calcium imaging on specific tissues. For example, by specifically expressing a GECI in olfactory neurons, the odor-induced responses of these neurons in peripheral organs can be examined. Calcium imaging of mosquito antennae further provides an advantageous method for simultaneously visualizing the activity of several antennal neurons in a single experiment. In this protocol, we describe a calcium imaging method to study odor-evoked responses in Anopheles coluzzii antennae expressing the calcium indicator GCaMP6f. This method requires imaging equipment (compound microscope, light sources, and camera), an odorant delivery system, and image acquisition software. The mosquito preparation is straightforward but requires practice to minimize mosquito movement during imaging. Recorded videos can be analyzed using Fiji software to generate heatmaps and activity traces for odorant-evoked responses. This protocol can also be used, with some modifications, to study other peripheral organs (such as labella, palps, and tarsi).


Assuntos
Anopheles , Animais , Anopheles/fisiologia , Cálcio , Olfato/fisiologia , Odorantes , Drosophila
12.
Cold Spring Harb Protoc ; 2022(11): Pdb.top107683, 2022 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-35960627

RESUMO

Mosquitoes transmit a multitude of diseases to humans and animals through biting and blood feeding. To locate their hosts, mosquitoes primarily use their sense of smell. Therefore, an understanding of mosquito olfaction will help develop strategies to control the diseases they transmit. A mosquito's sense of smell is determined by the response of olfactory neurons on its peripheral olfactory organs. Traditionally, mosquito olfactory neuron activity has been examined using electrophysiological techniques such as electroantennography and single sensillum recordings. Electroantennography examines if an odorant is detectable by the ensemble of all antennal neurons. In contrast, single sensillum electrophysiology allows detailed recordings of the activity of two to three neurons at a time. However, single sensillum recording of olfactory neurons is difficult, laborious, and typically allows examination of only a few neurons on the antenna. A promising new approach is to use optical imaging techniques to provide a way to visualize the global response of olfactory organs to an odor, as well as the specific responses of several olfactory neurons to that odor. In particular, calcium imaging has progressed significantly, from the use of chemical calcium indicators to the development of genetically encoded calcium sensors. These advances have opened the way to study the mode of action of known mosquito attractants and repellents as well as a way to screen potential new attractants and repellents. Here, we provide an introduction to the different types of calcium indicators and their uses for investigating the function of mosquito sensory neurons.


Assuntos
Culicidae , Olfato , Humanos , Animais , Olfato/fisiologia , Cálcio , Odorantes , Neurônios
13.
Methods Mol Biol ; 2540: 35-78, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35980572

RESUMO

Binary expression systems are useful genetic tools for experimentally labeling or manipulating the function of defined cells. The Q-system is a repressible binary expression system that consists of a transcription factor QF (and the recently improved QF2/QF2w), the inhibitor QS, a QUAS-geneX effector, and a drug that inhibits QS (quinic acid). The Q-system can be used alone or in combination with other binary expression systems, such as GAL4/UAS and LexA/LexAop. In this review chapter, we discuss the past, present, and future of the Q-system for applications in Drosophila and other organisms. We discuss the in vivo application of the Q-system for transgenic labeling, the modular nature of QF that allows chimeric or split transcriptional activators to be developed, its temporal control by quinic acid, new methods to generate QF2 reagents, intersectional expression labeling, and its recent adoption into many emerging experimental species.


Assuntos
Proteínas de Drosophila , Ácido Quínico , Animais , Animais Geneticamente Modificados , Drosophila/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Ácido Quínico/farmacologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transgenes
14.
Br J Nurs ; 31(14): S26-S35, 2022 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-35856587

RESUMO

BACKGROUND: Specialized vascular access training for medical professionals organized into vascular access teams (VATs) was shown to improve patient outcomes, clinical efficiency, and cost savings. Professional perspectives on VAT benefits, organization, challenges, and opportunities on a global scale remain inadequately explored. Using detailed perspectives, in this study, we explored the global VAT landscape, including challenges faced, clinical and clinico-economic impacts of VATs, with emphasis on underresearched facets of VAT initiation, data dissemination, and metrics or benchmarks for VAT success. METHODS: Semistructured in-depth interviews of 14 VAT professionals from 9 countries and 5 continents were used to elicit qualitative and quantitative information. RESULTS: Catheter insertions (100%) and training (86%) were the most performed VAT functions. Based on a 1-7 scale evaluating observed impacts of VATs, patient satisfaction (6.5) and institutional costs (6.2) were ranked the highest. VAT co-initiatives, advanced technology utilization (6.6), and ongoing member training (6.3) distinctly impacted VAT endeavors. Most institutions (64%) did not have routine mechanisms for recording VAT-related data; however, all participants (100%) stated the importance of sharing data to demonstrate VAT impacts. Time constraints (57%) emerged as one of the major deterrents to data collection or dissemination. The majority (64%) experienced an increased demand or workload for VAT services during the COVID-19 pandemic. CONCLUSIONS: Despite the global variances in VATs and gaps in VAT-related data, all participants unanimously endorsed the benefits of VAT programs. Evaluating the impact of VATs, disseminating VAT-related data, and forging specialized institutional partnerships for data sharing and training are potential strategies to tackle the hurdles surrounding VAT formation and sustenance.


Assuntos
COVID-19 , Pandemias , Atitude , COVID-19/epidemiologia , Humanos
15.
Semin Ultrasound CT MR ; 43(4): 280-292, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35738814

RESUMO

Dual-energy computed tomography (DECT) has developed into a robust set of techniques with increasingly validated clinical applications in neuroradiology. We review some of the most common applications in neuroimaging along with demonstrative case examples that showcase the use of this technology in intracranial hemorrhage, stroke imaging, trauma imaging, artifact reduction, and tumor characterization.


Assuntos
Neuroimagem , Tomografia Computadorizada por Raios X , Humanos , Hemorragias Intracranianas , Neuroimagem/métodos , Tomografia Computadorizada por Raios X/métodos
16.
Elife ; 112022 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-35442190

RESUMO

Drosophila melanogaster olfactory neurons have long been thought to express only one chemosensory receptor gene family. There are two main olfactory receptor gene families in Drosophila, the odorant receptors (ORs) and the ionotropic receptors (IRs). The dozens of odorant-binding receptors in each family require at least one co-receptor gene in order to function: Orco for ORs, and Ir25a, Ir8a, and Ir76b for IRs. Using a new genetic knock-in strategy, we targeted the four co-receptors representing the main chemosensory families in D. melanogaster (Orco, Ir8a, Ir76b, Ir25a). Co-receptor knock-in expression patterns were verified as accurate representations of endogenous expression. We find extensive overlap in expression among the different co-receptors. As defined by innervation into antennal lobe glomeruli, Ir25a is broadly expressed in 88% of all olfactory sensory neuron classes and is co-expressed in 82% of Orco+ neuron classes, including all neuron classes in the maxillary palp. Orco, Ir8a, and Ir76b expression patterns are also more expansive than previously assumed. Single sensillum recordings from Orco-expressing Ir25a mutant antennal and palpal neurons identify changes in olfactory responses. We also find co-expression of Orco and Ir25a in Drosophila sechellia and Anopheles coluzzii olfactory neurons. These results suggest that co-expression of chemosensory receptors is common in insect olfactory neurons. Together, our data present the first comprehensive map of chemosensory co-receptor expression and reveal their unexpected widespread co-expression in the fly olfactory system.


Assuntos
Neurônios Receptores Olfatórios , Receptores Odorantes , Animais , Células Quimiorreceptoras/metabolismo , Drosophila melanogaster/fisiologia , Neurônios Receptores Olfatórios/fisiologia , Receptores Odorantes/genética , Receptores Odorantes/metabolismo , Olfato
17.
Cell Rep ; 38(10): 110494, 2022 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-35263579

RESUMO

Mosquitoes locate and approach humans based on the activity of odorant receptors (ORs) expressed on olfactory receptor neurons (ORNs). Olfactogenetic experiments in Anopheles gambiae mosquitoes revealed that the ectopic expression of an AgOR (AgOR2) in ORNs dampened the activity of the expressing neuron. This contrasts with studies in Drosophila melanogaster in which the ectopic expression of non-native ORs in ORNs confers ectopic neuronal responses without interfering with native olfactory physiology. RNA-seq analyses comparing wild-type antennae to those ectopically expressing AgOR2 in ORNs indicated that nearly all AgOR transcripts were significantly downregulated (except for AgOR2). Additional experiments suggest that AgOR2 protein rather than mRNA mediates this downregulation. Using in situ hybridization, we find that AgOR gene choice is active into adulthood and that AgOR2 expression inhibits AgORs from turning on at this late stage. Our study shows that the ORNs of Anopheles mosquitoes (in contrast to Drosophila) are sensitive to a currently unexplored mechanism of AgOR regulation.


Assuntos
Anopheles , Malária , Receptores Odorantes , Animais , Anopheles/genética , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Expressão Gênica , Odorantes , Receptores Odorantes/genética , Receptores Odorantes/metabolismo
18.
CRISPR J ; 4(6): 836-845, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34813372

RESUMO

Cas9 and a guide RNA (gRNA) function to target specific genomic loci for generation of a double-stranded break. Catalytic dead versions of Cas9 (dCas9) no longer cause double-stranded breaks and instead can serve as molecular scaffolds to target additional enzymatic proteins to specific genomic loci. To generate mutations in selected genomic residues, dCas9 can be used for genomic base editing by fusing a cytidine deaminase (CD) to induce C > T (or G>A) mutations at targeted sites. In this study, we test base editing in Drosophila by expressing a transgenic Drosophila base editor (based on the mammalian BE2) that consists of a fusion protein of CD, dCas9, and uracil glycosylase inhibitor. We utilized transgenic lines expressing gRNAs along with pan-tissue expression of the Drosophila base editor (Actin5C-BE2) and found high rates of base editing at multiple targeted loci in the 20 bp target sequence. Highest rates of conversion of C > T were found in positions 3-9 of the gRNA-targeted site, with conversion reaching ∼100% of targeted DNA in somatic tissues. Surprisingly, the simultaneous use of two gRNAs targeting a genomic region spaced ∼50 bp apart led to mutations between the two gRNA targets, implicating a method to broaden the available sites accessible to targeting. These results indicate base editing is efficient in Drosophila, and could be used to induce point mutations at select loci.


Assuntos
Sistemas CRISPR-Cas , Edição de Genes , Animais , Sistemas CRISPR-Cas/genética , Drosophila/genética , Edição de Genes/métodos , Genoma , Mamíferos/genética , RNA Guia de Cinetoplastídeos/genética
19.
PLoS One ; 16(5): e0250381, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33989293

RESUMO

Various insect species serve as valuable model systems for investigating the cellular and molecular mechanisms by which a brain controls sophisticated behaviors. In particular, the nervous system of Drosophila melanogaster has been extensively studied, yet experiments aimed at determining the number of neurons in the Drosophila brain are surprisingly lacking. Using isotropic fractionator coupled with immunohistochemistry, we counted the total number of neuronal and non-neuronal cells in the whole brain, central brain, and optic lobe of Drosophila melanogaster. For comparison, we also counted neuronal populations in three divergent mosquito species: Aedes aegypti, Anopheles coluzzii and Culex quinquefasciatus. The average number of neurons in a whole adult brain was determined to be 199,380 ±3,400 cells in D. melanogaster, 217,910 ±6,180 cells in Ae. aegypti, 223,020 ± 4,650 cells in An. coluzzii and 225,911±7,220 cells in C. quinquefasciatus. The mean neuronal cell count in the central brain vs. optic lobes for D. melanogaster (101,140 ±3,650 vs. 107,270 ± 2,720), Ae. aegypti (109,140 ± 3,550 vs. 112,000 ± 4,280), An. coluzzii (105,130 ± 3,670 vs. 107,140 ± 3,090), and C. quinquefasciatus (108,530 ±7,990 vs. 110,670 ± 3,950) was also estimated. Each insect brain was comprised of 89% ± 2% neurons out of its total cell population. Isotropic fractionation analyses did not identify obvious sexual dimorphism in the neuronal and non-neuronal cell population of these insects. Our study provides experimental evidence for the total number of neurons in Drosophila and mosquito brains.


Assuntos
Encéfalo/citologia , Neurônios/citologia , Aedes/citologia , Animais , Anopheles/citologia , Culex/citologia , Drosophila , Feminino , Masculino , Caracteres Sexuais
20.
MicroPubl Biol ; 20212021 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-34007957

RESUMO

Drosophila melanogaster vinegar flies have two olfactory organs: the antenna and maxillary palp. Olfactory neurons in these tissues respond to odorants via odorant receptors. Insect odorant receptors are heterotetramers of two proteins: an odorant binding OrX subunit and an Odorant Receptor Co-Receptor (Orco). Mutation of Orco disrupts odorant receptor formation, and abolishes olfactory responses. Some antennal olfactory neurons in Orco mutants have been previously shown to degenerate. Here, we examine if maxillary palp olfactory neurons also degenerate in Orco mutants. We find degeneration occurs both more broadly and more rapidly in Orco mutant maxillary palp olfactory neurons than reported for antennae, with ~60% of all mutant olfactory neurons absent in maxillary palps by 7 days post eclosion. Interestingly, the subset of Orco mutant olfactory neurons that express the Or42a receptor appear resistant to degeneration. These results suggest the maxillary palp might be a suitable model for examining the molecular mechanisms underlying neurodegeneration in sensory neurons.

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