Simple fluorochromic detection of chromium with ascorbic acid functionalized luminescent Bio-MOF-1.

The bioaccumulation of various heavy metals in the environment and agriculture is posing serious hazards to human health. Hexavalent chromium is one of the most encountered heavy metal pollutants. The routine monitoring of Cr(VI) via simple methods assumes great analytical significance in sectors like environmental safety, food quality, etc. This study reports a novel biocompatible and luminescent metal-organic framework (ascorbic acid functionalized Bio-MOF-1) based "Turn-on" nanoprobe for rapid and sensitive optical detection of Cr(VI). Bio-MOF-1 has been synthesized, functionalized with ascorbic acid (AA), and then comprehensively characterized for its key material properties. The presence of Cr(VI) results in the photoluminescence recovery of Bio-MOF-1/AA. Using the above approach, Cr(VI) is detected over a wide concentration range of 0.02 to 20 ng mL-1, with the limit of detection being 0.01 ng mL-1. The nanoprobe is capable of detecting Cr(VI) in real water as well as in some spiked food samples. Hence, the ascorbic acid functionalized Bio-MOF-1 nanoprobe is established as a potential on-field detection tool for Cr(VI).

Beyond the Eyes: Clinico-Radiological Correlation of Bilateral Complete Horizontal Gaze Palsy in Moebius Syndrome.

Moebius syndrome is a rare disease characterized by unilateral or bilateral facial nerve palsies with/without other cranial nerve palsy. It manifests clinically with facial muscle weakness and/or ophthalmoplegia and can be associated with other physical anomalies such as various limb deformities and orofacial malformation. Herein, we have described the clinical and radiological features of Moebius syndrome in a 9-year-old female child who presented with left-side facial palsy and bilateral complete horizontal gaze palsy.

A multifunctional recyclable adsorbent based on engineered MIL-125 (Ti) magnetic mesoporous composite for the effective removal of pathogens.

The elimination of pathogenic bacteria from water sources is currently crucial for obtaining drinkable water. Therefore, the development of platforms with the ability to interact with pathogens and remove them is a potential future tool for medicine, food and water safety. In this work, we have grafted a layer of NH2-MIL-125 (Ti) on Fe3O4@SiO2 magnetic nanospheres for the removal of multiple pathogenic bacteria from water. The synthesized Fe3O4@SiO2@NH2-MIL-125 (Ti) nano adsorbent was characterized by FE-SEM, HR-TEM, FT-IR, XRD, BET surface analysis, magnetization tests, respectively, which illustrated its well-defined core-shell structure and magnetic behaviour. The prepared magnetic-MOF composite sorbent was attractive towards capturing a wide range of pathogens (S. typhimurium, S. aureus, E. coli, P. aeruginosa and K. pneumoniae) under experimental conditions. Influence factors such as adsorbent dosage, bacterial concentration, pH and incubation time were optimized for enhanced bacterial capture. The application of an external magnetic field removed Fe3O4@SiO2@NH2-MIL-125 (Ti) nano adsorbent from the solution along with sweeping the attached pathogenic bacteria. The non-specific removal efficiency of S. typhimurium for magnetic MOF composite was 96.58%, while it was only 46.81% with Fe3O4@SiO2 particles. For specific removal, 97.58% of S. typhimurium could be removed selectively from a mixture with monoclonal anti- Salmonella antibody conjugated magnetic MOF at a lower concentration of 1.0 mg/mL. The developed nano adsorbent may find great potential in microbiology applications and water remediation.

Post-Vaccination/Post-COVID Immune-Mediated Demyelination of the Brain and Spinal Cord: A Novel Neuroimaging Finding.

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), which not only produces respiratory symptoms but is known to involve almost every system, and its neuroinvasive properties have been well demonstrated throughout the pandemic. Also, to combat the pandemic, there was rapid development and induction of various vaccination drives, following which many adverse events following immunization (AEFIs) have been reported, which include neurological complications as well. Method: We present a series of three cases, post vaccination, with and without a history of COVID illness that showed remarkably similar findings on magnetic resonance imaging (MRI). Result: A 38-year-old male presented with complaints of weakness of the bilateral lower limbs with sensory loss and bladder disturbance a day after receiving his first dose of ChadOx1 nCoV-19 (COVISHIELD) vaccine. A 50-year-old male with hypothyroidism characterized by autoimmune thyroiditis and impaired glucose tolerance experienced difficulty in walking 11.5 weeks after being administered with COVID vaccine (COVAXIN). A 38-year-old male presented with subacute onset progressive symmetric quadriparesis 2 months after their first dose of a COVID vaccine. The patient also had sensory ataxia, and his vibration sensation was impaired below C7. All three patients had typical pattern of involvement of the brain and spine on MRI with signal changes in bilateral corticospinal tracts, trigeminal tracts in the brain, and both lateral and posterior columns in the spine. Conclusion: This pattern of brain and spine involvement on MRI is a novel finding and is likely a result of post-vaccination/post-COVID immune-mediated demyelination.

Carbon Dots Conjugated Antibody as an Effective FRET-Based Biosensor for Progesterone Hormone Screening.

In this work, carbon dots (CDs) were synthesized by a one-step hydrothermal method using citric acid and ethylene diamine, and covalently functionalized with antibodies for the sensing of progesterone hormone. The structural and morphological analysis reveals that the synthesized CDs are of average size (diameter 8-10 nm) and the surface functionalities are confirmed by XPS, XRD and FT-IR. Further graphene oxide (GO) is used as a quencher due to the fluorescence resonance energy transfer (FRET) mechanism, whereas the presence of the analyte progesterone turns on the fluorescence because of displacement of GO from the surface of CDs effectively inhibiting FRET efficiency due to the increased distance between donor and acceptor moieties. The linear curve is obtained with different progesterone concentrations with 13.8 nM detection limits (R2 = 0.974). The proposed optical method demonstrated high selectivity performance in the presence of structurally resembling interfering compounds. The PL intensity increased linearly with the increased progesterone concentration range (10-900 nM) under the optimal experimental parameters. The developed level-free immunosensor has emerged as a potential platform for simplified progesterone analysis due to the high selectivity performance and good recovery in different samples of spiked water.

Megalencephaly-Capillary Malformation-Polymicrogyria Syndrome (MCAP): A Rare Dynamic Genetic Disorder.

Megalencephaly-capillary malformation-polymicrogyria syndrome (MCAP) is an uncommon malformation syndrome, characterized by primary megalencephaly, capillary malformations of the midline face and body, or distal limb anomalies such as syndactyly and polymicrogyria. Herein, we report a young male child, who presented with complaints of increasing head size, delay in speech, and one episode of focal seizure with distinctive morphological and neuroradiological manifestations which led to the diagnosis of MCAP. We have also reviewed recently published literature and the various diagnostic criteria proposed by authors to achieve the early clinical diagnosis of these patients in the outpatient department.

An electrochemical biosensing platform for progesterone hormone detection using magnetic graphene oxide.

In recent times, graphene and its derivatives have turned out to be emerging nanomaterials as transducers to promote electron transport in the field of biosensing using electrochemical techniques. In electrochemical biosensing strategies, key factors such as signal amplification, stability, and sensitivity are necessary for attaining improved sensor performance. In the present work, we synthesized magnetic nanocomposites of graphene oxide and employed them as an electrode material for the loading of bio receptors. The increased surface area with high electric conductance enhanced the sensor's response. The immobilization of progesterone (PGN) antibodies on the modified electrode-sensing surface led to a hindered electron transport that decreased the current response. The developed electrochemical immunosensor assembled successfully in a stepwise process using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studies along with the electrochemical impedance spectroscopy (EIS) analysis. The current response decreased linearly with the increased progesterone (PGN) concentration range of 0.01 pM-1000 nM with excellent detection limits of 0.15 pM (DPV) and 0.17 pM (CV) under optimal experimental conditions. The label-free electrochemical immunosensor has shown a promising platform for rapid and direct analysis of PGN due to its high sensitivity, selectivity, stability, and repeatability in water samples.

A co-fumigation strategy utilizing reduced rates of phosphine (PH3 ) and sulfuryl fluoride (SF) to control strongly resistant rusty grain beetle, Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae).

BACKGROUND: Managing resistance to phosphine (PH3 ) in rusty grain beetle, Cryptolestes ferrugineus, is challenging, as strongly resistant insects of this species require very high concentrations over lengthy exposure periods (>10 days). Recently, approaches that enhance the efficacy of PH3 have gained momentum to control this pest, especially co-fumigations. In this study, efficacy of co-fumigating PH3 with another commercially available fumigant, sulfuryl fluoride (SF), has been evaluated against adults and eggs of two PH3 -resistant strains of C. ferrugineus. Concentrations of the mixture, representing lower than current application rates of both fumigants, were tested towards its field use. RESULTS: Co-fumigation of PH3 with SF was achieved in two patterns: over a continuous exposure period of 168 h simultaneously and sequentially over two periods of 78 h, in which insects were exposed to SF first followed by PH3 with 12 h aeration in-between. Results of simultaneous fumigations identified two effective co-fumigation rates, SF 185 + PH3 168 g hm-3 and SF 370 + PH3 84 g hm-3 that yielded complete control of adults and eggs. These two rates also were equally effective when they were applied sequentially and produced consistent results. Irrespective of application methods, concentrations of both PH3 and SF failed individually in achieving complete mortality of either adults or eggs or both. CONCLUSION: Our results confirmed that a co-fumigation strategy involving half the current standard rate of PH3 (84 g hm-3 ) with one-fourth of the current maximal registered rate of SF (370 g hm-3 ) can provide effective control of strongly PH3 -resistant C. ferrugineus.

Phenotypic and molecular analyses in rice weevil, Sitophilus oryzae (Linneaus) (Coleoptera: Curculionidae): identification of a super kdr mutation, T929I, conferring resistance to deltamethrin.

BACKGROUND: The rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) is a cosmopolitan pest of stored cereal grains and other commodities globally. Infestations caused by S. oryzae makes grains unsuitable for consumption, processing, and export. Deltamethrin, a synthetic pyrethroid insecticide, is widely used in major grain storages in India as a prophylactic treatment to control this pest. However, recurrent use of this insecticide had led to genetic resistance in S. oryzae, questioning its ongoing use at the current recommended concentration. RESULTS: Dose response analysis of resistant (Delta-R) and susceptible (Lab-S) strains of S. oryzae collected from grain storages across southern India, revealed that Delta-R was 134-fold more resistant than the Lab-S at median lethal concentration (LC50 ). A concentration of 180 ppm over 48 h effectively discriminated 16 resistant field populations from Lab-S with per cent resistance ranging from 8.72% to 75.86%. Exposing all the resistant populations to 1000 ppm over 48 h identified 12 populations with strongly resistant individuals and confirmed the existence of two distinct resistance phenotypes, 'weak' and 'strong' in S. oryzae. Furthermore, sequence analysis of the voltage-gated sodium channel (vgsc) gene in Delta-R identified a single target site mutation, T929I conferring resistance in S. oryzae. CAPS (Cleaved Amplified Polymorphic Sequence) marker analysis of this allele confirmed that frequency of resistance is high (up to 0.96) supporting the results of phenotypic analysis. CONCLUSION: Both phenotype and molecular marker analyses clearly demonstrated that deltamethrin at 180 and 1000 ppm can be used to discriminate weakly and strongly resistant populations in S. oryzae, respectively. Resistance diagnostics based on the mutation, T929I, supports our phenotypic data and indicates that resistance to deltamethrin in S. oryzae is prevalent in southern parts of India, stressing the need to identify a synergist or suitable alternatives. © 2021 Society of Chemical Industry.

Transcriptomic analysis of s-methoprene resistance in the lesser grain borer, Rhyzopertha dominica, and evaluation of piperonyl butoxide as a resistance breaker.

BACKGROUND: The lesser grain borer, Rhyzopertha dominica is a serious pest of stored grains. Fumigation and contact insecticides play a major role in managing this pest globally. While insects are developing genetic resistance to chemicals, hormonal analogues such as s-methoprene play a key role in reducing general pest pressure as well as managing pest populations that are resistant to fumigants and neurotoxic contact insecticides. However, resistance to s-methoprene has been reported in R. dominica with some reports showing a remarkable high resistance, questioning the use of this compound and other related analogues in grain protection. The current study attempts to identify possible molecular mechanisms that contribute in resistance to s-methoprene in R. dominica. RESULTS: Transcriptome analysis of resistant and susceptible strains of this pest species identified a set of differentially expressed genes related to cytochrome P450s, indicating their potential role in resistance to s-methoprene. Laboratory bioassays were performed with s-methoprene treated wheat grains in presence and absence of piperonyl butoxide (PBO), a cytochrome P450 inhibitor. The results indicate that PBO, when applied alone, at least at the concentration tested here, had no effect on R. dominica adult emergence, but has a clear synergistic effect to s-methoprene. The number of produced progeny decreased in presence of the inhibitor, especially in the resistant strain. In addition, we also identified CYP complement (CYPome) of R. dominica, annotated and analysed phylogenetically, to understand the evolutionary relationships with other species. CONCLUSIONS: The information generated in current study suggest that PBO can effectively be used to break resistance to s-methoprene in R. dominica.

Unique genetic variants in dihydrolipoamide dehydrogenase (dld) gene confer strong resistance to phosphine in the rusty grain beetle, Cryptolestes ferrugineus (Stephens).

The rusty grain beetle, Cryptolestes ferrugineus, a major pest of stored commodities, has developed very high levels (>1000×) of resistance to the fumigant phosphine. Resistance in this species is remarkably stronger than reported in any other stored product pests demanding the need to understand the molecular basis of this trait. Previous genetic studies in other grain insect pests identified specific variants in two major genes, rph1 and rph2 in conferring the strong resistance trait. However, in C. ferrugineus, although the gene, rph1 was identified as cytochrome-b5-fatty acid desaturase, the rph2 gene has not been reported so far. We tested the candidate gene for rph2, dihydrolipoamide dehydrogenase (dld) using the recently published transcriptome of C. ferrugineus and identified three variants, L73N and A355G + D360H, a haplotype, conferring resistance in this species. Our sequence analysis in resistant strain and phosphine selected resistant survivors indicates that these variants occur either alone as a homozygote or a mixture of heterozygotes (i.e complex heterozygotes) both conferring strong resistance. We also found that one of the three variants, possibly L73N expressing "dominant" trait at low frequency in resistant insects. Comparison of dld sequences between Australian and Chinese resistant strain of this species confirmed that the identified variants are highly conserved. Our fitness analysis indicated that resistant insects may not incur significant biological costs in the absence of phosphine selection for 19 generations. Thus, we propose that the observed high levels of resistance in C. ferrugineus could be primarily due to the characteristics of three unique variants, L73N and A355G + D360H within dld.

Synergism Between Phosphine (PH3) and Carbon Dioxide (CO2): Implications for Managing PH3 Resistance in Rusty Grain Beetle (Laemophloeidae: Coleoptera).

Strong resistance to phosphine (PH3) in the rusty grain beetle, Cryptolestes ferrugineus (Stephens) (Laemophloeidae: Coleoptera) poses a serious risk to stored-grain biosecurity. Resistant populations hold risk of surviving in PH3 fumigation, particularly in storage structure that limits achieving very high concentrations of PH3, demanding the need for alternative fumigation strategies. Cofumigation with PH3 and carbon dioxide (CO2) is one alternative approach that has the potential to be used widely. CO2 fumigation of adults of strongly PH3-resistant reference strain of C. ferrugineus, for 48 h, showed that the effective concentration (LC50) of CO2 was 30.99%. This 30% level of CO2 in combination with PH3 decreased the LC50 of PH3 from 6.7 mg/liter to 0.84 mg/liter, an eightfold increase in PH3 efficacy relative to PH3 fumigation in normal air. The LC99.9 decreased from 16.2 mg/liter to 5.8 mg/liter, a 2.8-fold increase in PH3 efficacy. Comparison of mortality response data of PH3 alone and the PH3 + CO2 mixture confirmed that CO2 enhances the toxicity of PH3 synergistically in addition to exerting its own toxicity. These results were validated against three independently field-derived strains of strongly resistant C. ferrugineus that confirmed that observed enhancement in toxicity with the PH3 + CO2 mixture was consistent, irrespective of differences in resistance phenotypes and inherent tolerance levels. Results of the current study provide further opportunities to develop new commercially viable strategy to control strongly PH3-resistant C. ferrugineus.

The Gene Introgression Approach and the Potential Cost of Genes that Confer Strong Phosphine Resistance in Red Flour Beetle (Coleoptera: Tenebrionidae).

Resistance in pest insects to the grain fumigant phosphine (PH3) poses a threat to trade and food security. The possible pleiotropic effects of PH3 resistance on development and reproduction were investigated in the red flour beetle, Tribolium castaneum (Herbst), by introgressing two genes known to be major contributors to strong resistance (tc_rph1 and tc_rph2) into a susceptible background. The tc_rph2 allele was the G135S variant, whereas the identity of tc_rph1 allele was unknown but could have been one of the three known variants (L119W, V123F, or S349G). The introgressed resistant strain was 288× more resistant than the susceptible strain, based on mortality after a 20 h fumigation with PH3. Molecular screening confirmed that the introgressed strain was homozygous for the resistance genes, but was otherwise indistinguishable from the susceptible strain based on screening with 12 neutral DNA markers. We found no differences of consequence in developmental time between the susceptible and introgressed resistant strains. Similarly, the number of F1 adults produced by these strains was more or less equal, as was the weight of individual F1 adults. The conclusions remained the same regardless of whether the experiments were conducted on a flour-based medium or wheat. Thus, we found no evidence that being fully strongly PH3 resistant (i.e., homozygous for tc_rph1 and tc_rph2) has major consequences in terms of development or reproduction in T. castaneum.

Resistance to the Fumigant Phosphine and Its Management in Insect Pests of Stored Products: A Global Perspective.

Development of resistance in major grain insect pest species to the key fumigant phosphine (hydrogen phosphide) across the globe has put the viability and sustainability of phosphine in jeopardy. The resistance problem has been aggravated over the past two decades, due mostly to the lack of suitable alternatives matching the major attributes of phosphine, including its low price, ease of application, proven effectiveness against a broad pest spectrum, compatibility with most storage conditions, and international acceptance as a residue-free treatment. In this review, we critically analyze the published literature in the area of phosphine resistance with special emphasis on the methods available for detection of resistance, the genetic basis of resistance development, key management strategies, and research gaps that need to be addressed.

High-dose strategies for managing phosphine-resistant populations of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae).

BACKGROUND: Rhyzopertha dominica is a serious pest of stored grains and many populations have resistance to the fumigant phosphine. Some populations contain beetles with a 'strong resistance' phenotype. Recent work found the LC50 values for two strong-resistant populations recently studied in North America, Belle Glade and Minneapolis were 100- and 595-fold higher, respectively, compared to LC50 of a lab-susceptible strain. Populations with 'weak-resistant' phenotypes had LC50 values 5- to 10-fold that of a susceptible strain. The work reported below aimed to determine the minimum phosphine concentrations and number of days of exposure needed to effectively control all life stages of representative weak- and strong-resistant strains, and then to recommend the treatment conditions needed to control strongly phosphine-resistant R. dominica in pest populations. RESULTS: A dose-mortality assay estimated that phosphine fumigation over 48 h using 730-870 ppm at 25° C would control adults of both strongly resistant R. dominica populations. Fumigations with mixed life stage cultures found 200 ppm killed all susceptible and weak-resistant beetles in 2 days, but the strong-resistant Minneapolis and Belle Glade strains had substantial survivors at 200 ppm. Furthermore, the Belle Glade strain had beetles that survived 1000 ppm in 2-day fumigations. The strong-resistant Belle Glade strain needed nearly 10 days at over 400 ppm to have acceptable levels of control. CONCLUSION: This study recommends protocols to manage strongly resistant R. dominica populations provided that a minimum phosphine concentration of 400 ppm be maintained at 25° C or higher for up to 10 days. © 2019 Society of Chemical Industry.

Development of a Quick Knockdown Test for Diagnosing Resistance to Phosphine in Sitophilus oryzae (Coleoptera: Curculionidae), a Major Pest of Stored Products.

A key component in the management of resistance to fumigant phosphine in stored products pests is their early detection and implementation of control strategies. Currently, resistance testing involves exposing adults to a specific discriminating concentration over a fixed time period (20-48 h). Although it is widely adopted, this test takes significant time for assay preparation (up to 4 wk) as well as diagnosis (1-2 wk). To address these lacunae, we have established a 'quick knockdown test' using a key grain insect pest, rice weevil, Sitophilus oryzae (L.). Susceptible, weakly and strongly phosphine-resistant reference strains were exposed to a threshold concentration of phosphine over short exposure periods (min to h). The time to knockdown (KT) responses to phosphine were characterized at 2 (1,440 ppm) and 5 mg/liter (3,600 ppm). The time to 99.9% KT (KT99.9) at 2 mg/liter was 12.52 min for the susceptible adults, compared with 167.9 and 1,510 min in the case of weakly and strongly resistant phenotypes, respectively. As anticipated, increasing the concentration of phosphine to 5 mg/liter halved the KT99.9 (81.57 min) to separate weakly and strongly resistant populations than it was required at 2 mg/liter. We validated the KT99.9 value for the 5 mg/liter against field-derived populations of S. oryzae. The results were aligned with the existing Food and Agriculture Organization approach, confirming that the proposed 'quick test' is a reliable tool to rapidly diagnose resistance in this species.

Evaluation of Knockdown Bioassay Methods to Assess Phosphine Resistance in the Red Flour Beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae).

Resistance to the fumigant phosphine in Tribolium castaneum occurs worldwide. This study evaluated tests based on adult knockdown time, the time for a beetle to become immobile, when exposed to a high concentration of phosphine. We recorded knockdown times of beetles that remained completely still for 30 s when exposed to 3000 ppm of phosphine in a large, gas-tight glass tube. Beetles were used from 12 populations, of which six were 'susceptible' to phosphine, three were 'weakly resistant', and three were 'strongly resistant'. Knockdown times were determined for single beetles, as well as for groups of ten beetles for which the time to knockdown for either five beetles (KT50) or ten beetles (KT100) were recorded. Similar knockdown times occurred across susceptible and resistant populations. However, the KT100 tests generated conservative times for diagnosing strong vs. weak resistance. The strong resistant populations were all over 100 min with KT100, compared to 60 min or less for susceptible and weak resistant populations. Special tests on single beetles revealed higher knockdown times in insects that were deliberately disturbed compared to those without any disturbances. Work reported here suggests a knockdown test conducted on beetles in a matter of minutes or hours could help classify phosphine resistance status prior to decisions on phosphine fumigation.