Mobilization of heavy metals from floodplain sediments of the Yellow River during redox fluctuations.

The floodplain of the Yellow River is a typical area characterized by redox fluctuations and heavy metal pollution. However, the mobilization behavior of heavy metals in floodplain sediments during redox fluctuations remains poorly understood. In this study, reductive mobilization of Fe and Mn was observed under reducing environments through reduction and dissolution, leading to the subsequent release of adsorbed As. In contrast, the mobilization of U occurred under oxic conditions, as the oxidative state of U(VI) has higher solubility. Furthermore, insignificant effects on the mobilization of Cd, Cu, Pb, and Hg were noticed during redox fluctuations, indicating higher stability of these heavy metals. Additionally, we demonstrated that carbon sources can play a key role in the mobilization of heavy metals in floodplain sediments, amplifying the reductive mobilization of Fe, Mn, As and the oxidative mobilization of U. Our findings contribute to the understanding of the biogeochemical cycling of heavy metal in floodplain sediments of the Yellow River and the factors that control this cycling.

Chemical profile and in-vitro bioactivities of three types of yellow teas processed from different tenderness of young shoots of Huoshanjinjizhong (Camellia sinensis var. sinensis).

In the present study, bud yellow tea (BYT), small-leaf yellow tea (SYT) and large-leaf yellow tea (LYT) were produced from the same local "population" variety Huoshanjinjizhong (Camellia sinensis var. sinensis), and the effects of raw material tenderness on the chemical profile and bioactivities of these teas were investigated. The results showed that 11 crucial compounds were screened by headspace solid-phase microextraction-gas chromatography-mass spectrometry from 64 volatiles in these yellow teas, among which the heterocyclic compounds showed the greatest variations. In addition, 43 key compounds including organic acids, flavan-3-ols, amino acids, saccharides, glycosides and other compounds were screened by liquid chromatography-mass spectrometry from 1781 non-volatile compounds. BYT showed the best α-glucosidase inhibitory activity and antioxidant capacity among the selected yellow teas, which might be contributed by the higher content of galloylated catechins. These findings provided a better understanding of the chemical profile and bioactivities of yellow teas.

Seasonal and spatial variations of dissolved inorganic nitrogen exchange between the Yellow Sea and the East China Sea and the influencing factors.

Nutrient exchange with the East China Sea plays an important role in primary production in the Yellow Sea. Owing to lack of simultaneous observations, the spatiotemporal nutrient exchanges across the boundary between the Yellow Sea and East China Sea (Section YE) remain unclear. In this study, a three-dimensional physical-biogeochemical coupled model was used to determine the flux of dissolved inorganic nitrogen (DIN) across Section YE. The results showed that DIN was transported from the East China Sea to the Yellow Sea throughout the year and was highest in summer, accounting for 38 % of the total annual amount. Seasonal variations in the DIN flux were attributed to seasonal variations in the ocean currents across Section YE. In the Yellow Sea, the annual amount of DIN from lateral boundaries was larger than the river input and was comparable to the atmospheric deposition.

Physics and chemistry of nitrogen dioxide (NO2) adsorption on gallium nitride (GaN) surface and its interaction with the yellow-luminescence-associated surface state.

Surface states have been a longstanding and sometimes underestimated problem in gallium nitride (GaN) based devices. The instability caused by surface-charge-trapping in GaN-based transistors is practically the same problem faced by the inventors of the silicon (Si) field effect transistors more than half a century ago. Although in Si this problem was eventually solved by oxygen and hydrogen-based passivation, in GaN, such breakthrough has yet to be made. Apparently, some of this surface charge originates in molecules adsorbed on its surface. Here, it is shown that the charge density associated with the GaN yellow band desorbs upon mild heat treatment in vacuum and re-adsorbs on exposure to the air. Selective exposure of GaN to nitrogen dioxide (NO2) reproduces this surface charge to its original distribution, as does exposure to air. Residual gas analysis of the gases desorbed during heat treatment shows a large concentration of nitric oxide (NO). These observations suggest that selective adsorption of NO2 is responsible for the surface charge that deleteriously affects the electrical properties of GaN. The physics and chemistry of this NO2 adsorption, reported here, may open a new path in the search for passivation to improve GaN device reliability.

Palliative Subcutaneous Needle Drainage for a Rare Cause of Refractory Lymphedema: Yellow Nail Syndrome.

Yellow nail syndrome (YNS) presents a therapeutic challenge due to its elusive etiology and lack of effective treatments. We present a case of a 77-year-old female with YNS-associated lymphedema who experienced significant symptomatic relief with subcutaneous drainage therapy, a novel intervention not previously described in YNS. Despite prior failed conventional therapies, she achieved remarkable weight loss, improved mobility, and stable biochemical parameters. Subcutaneous drainage therapy, though traditionally utilized in cancer-associated lymphedema, demonstrates promise as an alternative palliative treatment for refractory cases of lymphedema to improve quality of life.

Novel Donor-Acceptor Based 4-Nitrophenol Luminophores as a Yellow-Orange Fluorescent Material for Optoelectronic Applications.

A new category of 4-nitrophenol (4-NP) luminophores, infused with varying amounts of Pyrene (Py), was synthesized using the standard solid-state reaction method to investigate novel luminophores that emit at longer wavelengths. Their optical and electrochemical properties were analyzed using fluorimetry and cyclic voltammetry techniques. The fluorescence spectrum of Py-doped 4-NP displayed a broad fluorescence band with a peak at 599 nm for a Py concentration of 1 × 10- 3 mol, indicating exciplex formation between 4-NP and Py in the excited state. The electrochemical data revealed that the energy levels of the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) for the synthesized luminophores ranged from - 5.72 to -5.73 eV and - 3.01 to -3.08 eV, respectively. Thermal stability was evaluated through TGA analysis. The XRD confirmed the synthesis of a homogeneous material. The SEM images showed crystal sizes of approximately 115 nm. This thorough investigation indicates the potential of these newly synthesized yellow-orange fluorescent luminophores for optoelectronic applications.

Addition of Cryoprotectant DMSO Reduces Damage to Spermatozoa of Yellow Catfish (Pelteobagrus fulvidraco) during Cryopreservation: Ultrastructural Damage, Oxidative Damage and DNA Damage.

Spermatozoa cryopreservation protocols have been established for yellow catfish (Pelteobagrus fulvidraco), but cryopreservation can still cause cellular damage and affect spermatozoa viability and fertility. Therefore, the aim of this paper was to evaluate the effects of adding or not adding cryoprotectants during low-temperature storage on the ultrastructural damage, oxidative damage, and DNA damage of thawed yellow catfish spermatozoa. The mixed semen of three male yellow catfish was divided into a fresh spermatozoa group, a frozen spermatozoa group (DMSO+) with a cryoprotectant (10% DMSO), and a frozen spermatozoa group without a cryoprotectant (DMSO-). Ultrastructural of the spermatozoa after thawing were observed under an electron microscope and the spermatozoa were assayed for SOD, MDA, and T-AOC enzyme activities, as well as for DNA integrity. In terms of movement parameters, compared with DMSO-, the addition of DMSO has significantly improved sperm motility, curve line velocity (VCL), and straight line velocity (VSL). The ultrastructural results showed that although thawed spermatozoa exhibited increased damage than fresh spermatozoa, 10% DMSO effectively reduced the damage to the plasma membrane, mitochondria, and flagellum of spermatozoa by cryopreservation, and most of the spermatozoa were preserved with intact structure. The results of oxidative damage showed that compared with frozen spermatozoa, 10% DMSO significantly increased the activities of SOD and T-AOC enzymes and clearly reduced the activity of the MDA enzyme. The antioxidant capacity of spermatozoa was improved, lipid peroxidation was reduced, and the oxidative damage caused by cryopreservation was mitigated. The DNA integrity of spermatozoa showed that 10% DMSO clearly reduced the DNA fragmentation rate. In conclusion, 10% DMSO can effectively reduce the ultrastructural damage, oxidative damage, and DNA damage of yellow catfish spermatozoa during cryopreservation; it can also further optimize the cryopreservation protocol for yellow catfish spermatozoa. Meanwhile, it also provides a theoretical basis for the future optimization of the cryopreservation protocols.

Comparative Analysis of the Potential Adaptability of Tibetan Dzo and Yellow Cattle Based on Blood Indices, Metabolites, and Fecal Microbiota.

This study aimed to investigate the differences in environmental adaptability between dzo and Tibetan yellow cattle by using corresponding assay kits to analyze blood indices, utilizing mass spectrometry for blood metabolite profiling, and performing 16S rDNA sequencing of fecal microbiota. Forty female cattle were randomly divided into a dzomo (female dzo) group (MG, n = 20) and a Tibetan-yellow-cattle group (HG, n = 20). After 150 days of uniform feeding, six cattle from each group were randomly picked for jugular blood sampling and collection of fecal microorganisms. The results showed that the serum albumin, creatinine, total protein, superoxide dismutase, IgG, and IgM concentrations in the MG group were higher (p < 0.05), whereas the serum triglyceride concentration was lower, compared to the HG group (p < 0.05). The higher level of phospholipids containing long-chain polyunsaturated fatty acids (PUFAs) (PC (18:5e/2:0), PC (20:5e/2:0), LPC 18:2, LPC 20:5) observed in the serum of the dzo suggests that they have an advantage in adapting to the challenging conditions of the plateau environment. The fecal microbiota analysis showed that Akkermansia was significantly enriched in the MG group; this might be the key bacterial genus leading to the strong adaptability of dzo. Our findings indicated the dzo's superior adaptation to the Tibetan Plateau's harsh environment.

Effect of Near-Freezing Storage Combined with High-Voltage Electric Fields on the Freshness of Large Yellow Croaker.

Seafood is highly perishable after being caught, making effective preservation technology essential. A few studies have explored the mechanisms of near-freezing storage combined with high-voltage electric fields for seafood preservation. This study uses near-freezing storage at -1 °C in conjunction with three high-voltage electric fields (5 kV/m, 8 kV/m, and 16 kV/m) to store large yellow croakers for 21 days and assesses their quality through sensory evaluation, pH values, malondialdehyde, total volatile basic nitrogen, and total viable counts. The results indicate that high-voltage electric fields effectively inhibit endogenous enzyme activity and microbial growth while reducing lipid oxidation in large yellow croakers. The preservation effect is optimal at an electric field strength of 16 kV/m, extending their shelf life by 9 days. These findings offer valuable theoretical and data-driven insights for applying near-freezing storage and electric field preservation technology in cross-regional fish transportation.

Developing a Microsatellite Polymerase Chain Reaction System for Small Yellow Croaker (Larimichthys polyactis) and Its Application in Parentage Assignment.

(1) Background: The small yellow croaker, an economically important fish in East Asia, has been subjected to population declines due to overfishing and environmental pressures. The development of effective breeding programs is considered crucial for the species, and accurate parentage assignment is deemed essential for such programs. (2) Methods: The assembled reference genome of the small yellow croaker was utilized to select highly polymorphic microsatellite markers. A multiplex PCR system was optimized for the simultaneous amplification of these markers. The system's accuracy was validated using controlled mating pairs and subsequently applied to a group mating scenario. (3) Results: The developed multiplex PCR system demonstrated high accuracy in assigning offspring to their parents in both the controlled and group mating scenarios. (4) Conclusions: The system is presented as a valuable tool for pedigree management, selective breeding, and conservation efforts for the small yellow croaker, facilitating sustainable aquaculture practices and genetic improvement.

Conjunctive BSA-Seq and BSR-Seq to Map the Genes of Yellow Leaf Mutations in Hot Peppers (Capsicum annuum L.).

Yellow leaf mutations have been widely used to study the chloroplast structures, the pigment synthesis, the photosynthesis mechanisms and the chlorophyll biosynthesis pathways across various species. For this study, a spontaneous mutant with the yellow leaf color named 96-140YBM was employed to explore the primary genetic elements that lead to the variations in the leaf color of hot peppers. To identify the pathways and genes associated with yellow leaf phenotypes, we applied sequencing-based Bulked Segregant Analysis (BSA-Seq) combined with BSR-Seq. We identified 4167 differentially expressed genes (DEGs) in the mutant pool compared with the wild-type pool. The results indicated that DEGs were involved in zeatin biosynthesis, plant hormone signal transduction, signal transduction mechanisms, post-translational modification and protein turnover. A total of 437 candidates were identified by the BSA-Seq, while the BSR-Seq pinpointed four candidate regions in chromosomes 8 and 9, containing 222 candidate genes. Additionally, the combination of BSA-Seq and BSR-Seq showed that there were 113 overlapping candidate genes between the two methods, among which 8 common candidates have been previously reported to be related to the development of chloroplasts, the photomorphogenesis and chlorophyll formation of plant chloroplasts and chlorophyll biogenesis. qRT-PCR analysis of the 8 common candidates showed higher expression levels in the mutant pool compared with the wild-type pool. Among the overlapping candidates, the DEG analysis showed that the CaKAS2 and CaMPH2 genes were down-regulated in the mutant pool compared to the wild type, suggesting that these genes may be key contributors to the yellow leaf phenotype of 96-140YBM. This research will deepen our understanding of the genetic basis of leaf color formation and provide valuable information for the breeding of hot peppers with diverse leaf colors.

Next generation yellow fever vaccine induces an equivalent immune and transcriptomic profile to the current vaccine: observations from a phase I randomised clinical trial.

BACKGROUND: Yellow fever (YF), a mosquito-borne acute viral haemorrhagic illness, is endemic to many tropical and subtropical areas of Africa and Central and South America. Vaccination remains the most effective prevention strategy; however, as repeated outbreaks have exhausted vaccine stockpiles, there is a need for improved YF vaccines to meet global demand. A live-attenuated YF vaccine candidate (referred to as vYF) cloned from a YF-17D vaccine (YF-VAX®) sub-strain, adapted for growth in Vero cells cultured in serum-free media, is in clinical development. We report the innate and adaptive immune responses and the transcriptome profile of selected genes induced by vYF. METHODS: Healthy adults aged 18-60 years were randomised at a 1:1:1:1 ratio to receive one dose of vYF at 4, 5 or 6 Log CCID50 or YF-VAX (reference vaccine), administered subcutaneously in the upper arm (ClinicalTrials.gov identifier: NCT04142086). Blood/serum samples were obtained at scheduled time points through 180 days (D180) post-vaccination. The surrogate endpoints assessed were: serum cytokine/chemokine concentrations, measured by bead-based Multiplex assay; peripheral blood vYF-specific IgG and IgM memory B cell frequencies, measured by FluoroSpot assay; and expression of genes involved in the immune response to YF-17D vaccination by RT-qPCR. FINDINGS: There was no increase in any of the cytokine/chemokine concentrations assessed through D14 following vaccination with vYF or YF-VAX, except for a slight increase in IP-10 (CXCL10) levels. The gene expression profiles and kinetics following vaccination with vYF and YF-VAX were similar, inclusive of innate (antiviral responses [type-1 interferon, IFN signal transduction; interferon-stimulated genes], activated dendritic cells, viral sensing pattern recognition receptors) and adaptive (cell division in stimulated CD4+ T cells, B cell and antibody) immune signatures, which peaked at D7 and D14, respectively. Increases in vYF-specific IgG and IgM memory B cell frequencies at D28 and D180 were similar across the study groups. INTERPRETATION: vYF-induced strong innate and adaptive immune responses comparable to those induced by YF-VAX, with similar transcriptomic and kinetic profiles observed. FUNDING: Sanofi.

Effect of brine concentration on the quality of salted large yellow croaker during processing and refrigeration.

This study aimed to evaluate the effect of brine concentrations (4%, 8%, 12%, 16%) on the quality of salted large yellow croakers. During the wet salting processing, increased salinity inhibited myogenic fibers swelling and extracellular space expansion, and resulted in lower water content and higher salt content of salted large yellow croaker products. During refrigeration of salted large yellow croakers at 4 °C for 24 days, SDS-PAGE patterns showed that high salinity slowed down the degradation of proteins, which was further confirmed by changes in free amino acids (FAAs) and biogenic amine contents. The increases in K value, total volatile basic nitrogen (TVB-N) content, total viable counts (TVC) and the deterioration in sensory were delayed by increasing salinity. Notably, high salinity enhanced malondialdehyde (MDA) accumulation. The results suggested that high salinity inhibited tissue structure destruction, microbial growth, protein degradation and freshness reduction, but accelerated lipid oxidation of salted large yellow croakers. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-024-01573-5.

The Discovery of a Citrus Yellow Vein Clearing Virus Hacienda Heights Isolate Diversifies the Geological Origins of the Virus in California, United States.

The citrus yellow vein clearing virus (CYVCV) is an emerging threat to the U.S. citrus industry. Reports from China shows it cause significant reductions in fruit yield and growth, particularly in lemon trees. In 2022, CYVCV was detected in a wide range of citrus cultivars in localized urban properties in Tulare, California. In 2024, a CYVCV-infected lemon tree was detected in Hacienda Heights in Los Angeles County, California, geographically separated from the Tulare foci. Through long-read sequencing technology, the whole-genome sequence of a CYVCV isolate from Hacienda Heights (designated as CYVCV-CA-HH1, Accession number PP840891.1) was obtained. Sequence alignments and neighbornet analysis strongly suggested that the CYVCV-CA-HH1 isolate has a different origin than the Tulare CYVCV (CYVCV CA-TL) isolates. The CYVCV CA-TL isolates were grouped with those from South Asia (India and Pakistan) and the Middle East (Türkiye), while the CYVCV-CA-HH1 isolate was grouped with isolates from East Asia (China and South Korea). Maximum likelihood phylogenetic analysis further supports this finding, showing that the CYVCV-CA-HH1 isolate shares the most recent common ancestor with a South Korean lineage, which derives from Chinese isolates. Together, our data suggest a diverse geological origin of CYVCV isolates in California.

Comparison of the natural and surfactant-modified zeolites in the adsorption efficiency of sunset yellow food dye from aqueous solutions.

The removal of Sunset Yellow (E110) on natural zeolite and zeolite modified with the cationic surfactant cetyl pyridinium chloride (CPC) was studied using the adsorption method. The structural characteristics of the surfactant-modified zeolite (SMZ-CPC) were investigated using X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) analysis, and the scanning electron microscopy (SEM) images. The effect of different parameters on the adsorption process, such as equilibration time and amount of adsorbent at 298 K, were determined using UV-Vis spectroscopy. The maximum dye removal percentage on SMZ-CPC was obtained with 0.08 g of adsorbent in 30 min. The results show that the zeolite modified with CPC surfactant (SMZ) has a higher adsorption capacity for Sunset Yellow than the unmodified zeolite (natural form). The experimental adsorption data were nonlinearly analyzed using isotherm equations such as Langmuir, Freundlich, Temkin, Langmuir-Freundlich (or Sips), and Extended Langmuir (EL). The experimental data were better fitted with the Sips isotherm. The adsorption kinetic data were analyzed using eight models in nonlinear forms: the pseudo-first-order (PFO), pseudo-second-order (PSO), integrated kinetic Langmuir (IKL), Elovich, intraparticle diffusion (IPD), mixed order rate equation (MOE), fractal-like pseudo-first-order (FL-PFO) and fractal-like pseudo-second-order (FL-PSO). According to the results of the coefficient of determination (R2), Elovich kinetic model well expressed E110 adsorption onto SMZ-CPC. Most of the dye removal takes place in less than 5 min and the maximum adsorption capacity is 5.06 mg/g. The results of this study show that zeolite modified with cationic surfactant is an effective adsorbent for removal anionic dyes from an aqueous solution.

Development and validation of RT-LAMP for detecting yellow fever virus in non-human primates samples from Brazil.

Monitoring yellow fever in non-human primates (NHPs) is an early warning system for sylvatic yellow fever outbreaks, aiding in preventing human cases. However, current diagnostic tests for this disease, primarily relying on RT-qPCR, are complex and costly. Therefore, there is a critical need for simpler and more cost-effective methods to detect yellow fever virus (YFV) infection in NHPs, enabling early identification of viral circulation. In this study, an RT-LAMP assay for detecting YFV in NHP samples was developed and validated. Two sets of RT-LAMP primers targeting the YFV NS5 and E genes were designed and tested together with a third primer set to the NS1 locus using NHP tissue samples from Southern Brazil. The results were visualized by colorimetry and compared to the RT-qPCR test. Standardization and validation of the RT-LAMP assay demonstrated 100% sensitivity and specificity compared to RT-qPCR, with a detection limit of 12 PFU/mL. Additionally, the cross-reactivity test with other flaviviruses confirmed a specificity of 100%. Our newly developed RT-LAMP diagnostic test for YFV in NHP samples will significantly contribute to yellow fever monitoring efforts, providing a simpler and more accessible method for viral early detection. This advancement holds promise for enhancing surveillance and ultimately preventing the spread of yellow fever.

An Overview of Aspergillus Species Associated with Plant Diseases.

The genus Aspergillus contains several species that are important plant pathogens. Plant pathogenic Aspergillus spp. affect agricultural crops in the field as well as after harvest, often associated with corn ear rot, cotton boll rot, peanut yellow mold, black mold of onion and garlic, fruit rot on grapes, pomegranates, olives, citrus, and apples. Coffee berries and coffee beans as well as tree nuts are also frequently infected by Aspergillus spp. Some of the plant pathogenic Aspergillus spp. are also mycotoxigenic, produced mycotoxin in the plant tissues leading to contamination of agricultural products. Over the years, reports of plant diseases caused by Aspergillus in various crops have increased, suggesting they are commonly encountered plant pathogens. This review focuses on agricultural crops or cultivated plants infected by Aspergillus spp. The compilation of plant pathogenic Aspergillus spp. provides information to mycologists, particularly those involved in plant pathology and crop protection, with updated information on plant diseases caused by various species of Aspergillus. The updated information also includes the locality or location, province, state and the country. The knowledge on the prevalence and geographic distribution of plant pathogenic Aspergillus spp. is beneficial in the application of crop protection.

Assessing the impact of human activities on ecosystem asset dynamics in the Yellow River Basin from 2001 to 2020.

The intensification of human activities in the Yellow River Basin has significantly altered its ecosystems, challenging the sustainability of the region's ecosystem assets. This study constructs an ecosystem asset index for the period from 2001 to 2020, integrating it with human footprint maps to analyze the temporal and spatial dynamics of ecosystem assets and human activities within the basin, as well as their interrelationships. Our findings reveal significant improvement of ecosystem assets, mainly attributed to the conversion of farmland back into natural habitats, resulting in a 15,994 km2 increase in ecological land use. Notably, 45.88% of the basin has experienced concurrent growth in both human activities and ecosystem assets, with ecosystem assets expanding at a faster rate (22.61%) than human activities (17.25%). Areas with high-quality ecosystem assets are expanding, in contrast to areas with intense human activities, which are facing increased fragmentation. Despite a global escalation in threats from human activities to ecosystem assets, the local threat level within the Yellow River Basin has slightly diminished, indicating a trend towards stabilization. Results highlight the critical importance of integrating spatial and quality considerations into restoration efforts to enhance the overall condition of ecosystem assets, especially under increasing human pressures. Our work assesses the impact of human activities on the dynamics of ecosystem assets in the Yellow River Basin from 2001 to 2020, offering valuable insights for quality development in the region, may provide a scientific basis for general watershed ecological protection and sustainable management in a region heavily influenced by human activity but on a path to recovery.

Insect cell production of chimeric virus-like particles based on human immunodeficiency virus GAG proteins and yellow fever virus envelope protein.

The yellow fever virus (YFV) is a single stranded RNA virus belonging to the genus Orthoflavivirus that is capable of zoonotic transmissions that infect nonhuman and human primates. It is endemic in Brazil with recurrent epidemics of the disease, and it is transmitted through mosquitoes. The detection and immunization against YFV and other flaviviruses are fundamental for the management of the impacts of the disease in human environments. In an ongoing effort to develop new approaches for diagnostics and immunizations, we expressed VLPs displaying the yellow fever virus envelope protein (YFE) using recombinant baculovirus in insect cells. By co-expressing HIV-1 Pr55Gag protein (GAG) together with YFE we were able to generate chimeric VLPs containing a GAG core together with an envelope containing the YFE protein. The YFE and the chimeric GAG-YFE VLPs have potential as vaccine candidates and as reagents for serological assays in the detection of these viruses in human sera.

A bioassay that yields quantifiable symptoms of cucurbit yellow vine disease caused by Serratia marcescens.

Cucurbit yellow vine disease (CYVD), which is caused by the gram-negative bacterium Serratia marcescens and transmitted by squash bugs (Anasa tristis DeGeer), is a devastating disease of cucurbit crops that is emerging rapidly in the eastern half of the U.S. The lack of a robust pathogenicity assay for CYVD in the laboratory has hampered functional tests using genomic sequences to investigate the biology of this phytopathogen. In this study we developed and validated a bioassay that yielded consistent and quantifiable CYVD symptoms on squash in the lab. We compared inoculation by wounding with a multipronged floral pin frog to inoculation by injection in which a needle was moved in and out of the stem multiple times in each of multiple piercings to mimic the feeding behavior of squash bugs. We found that inoculation by needle injection of ≥108 CFU/ml of S. marcescens into the stem of squash (Cucurbita pepo) plants at the cotyledon growth stage reproducibly induced CYVD symptoms, whereas injecting 106 or 107 CFU/ml did not. Additionally, we found that S. marcescens induced symptoms on all of the squash cultivars tested, and induced symptoms that have not been previously reported, including stem elongation and leaf cupping. In short, through our injection approach of mimicking the natural process of S. marcescens transmission by squash bug feeding, we obtained robust and quantifiable CYVD symptoms. This laboratory bioassay provides a crucial tool for investigating the biology and pathology of this emerging pathogen and for plant breeding screens aimed at combatting CYVD.