Zhang Y et al. (2021) Foods "Construction and Application of EGCG-Loaded Lysozyme/Pectin Nanoparticles for Enhancing the Resistance of Nematodes to Heat and Oxidation Stresses."

Tian J, Cui H, Li B, Zhang Y, Lin L

[Foods, 2021]

Novel nanoparticles (NPs) were constructed with lysozyme (LY) and pectin (Ps) through self-assembly, which were used as a carrier to encapsulate epigallocatechin-3-gallate (EGCG). The binding of EGCG and LY is a static quenching process. Hydrogen bonds might play a major role in the formation of NPs, which has also been verified by a lower binding constant of EGCG with LY/Ps NPs. Meanwhile, EGCG could lead to conformational and microenvironmental changes of LY, resulting in more folding of LY secondary structures. In addition, attaching Ps to LY might inhibit LY aggregation induced by addition of free EGCG. At the LY/Ps mass ratio of 1:1, the constructed LY/Ps NPs had a high EGCG-loading capacity without a significant change in mean particle size, thus, our NPs could be used as an effective nanocarrier for loading EGCG. In vivo, compared with free EGCG, EGCG loaded onto LY/Ps NPs significantly increased <i>Caenorhabditis elegans</i>' (<i>C. elegans</i>) resistance to heat stress and oxidative injury and prolonged their lifespan. This study provides theoretical basis and reference for constructing nanoactive substance carriers so as to improve the resistance of organisms to heat stress and oxidative damage and to increase their survival rate and extend their lifespan under environment stresses.

Steciuk M et al. (2014) G3 (Bethesda) "Regulation of synaptic transmission at the Caenorhabditis elegans M4 neuromuscular junction by an antagonistic relationship between two calcium channels."

You YJ, Steciuk M, Cheong MC, Waite C, Avery L

[G3 (Bethesda), 2014]

In wild-type Caenorhabditis elegans, the synapse from motor neuron M4 to pharyngeal terminal bulb (TB) muscles is silent, and the muscles are instead excited by gap junction connections from adjacent muscles. An eat-5 innexin mutant lacking this electrical connection has few TB contractions and is unable to grow well on certain foods. We showed previously that this defect can be overcome by activation of the M4 TB synapse. To identify genes that negatively regulate synaptic transmission, we isolated new suppressors of eat-5. To our surprise, these suppressors included null mutations in NPQR-type calcium channel subunit genes unc-2 and unc-36. Our results are consistent with the hypothesis that Ca(2+) entry through the NPQR-type channel inhibits synaptic transmission by activating the calcium-activated K(+) channel SLO-1, thus antagonizing the EGL-19 L-type calcium channel.

Neto MF et al. (2016) J Clin Tuberc Other Mycobact Dis "The nematode Caenorhabditis elegans displays a chemotaxis behavior to tuberculosis-specific odorants."

Voisine C, Marsili J, Nguyen QH, McFall SM, Neto MF

[J Clin Tuberc Other Mycobact Dis, 2016]

A simple, affordable diagnostic test for pulmonary tuberculosis (TB) is urgently needed to improve detection of active <i>Mycobacterium tuberculosis.</i> Recently, it has been suggested that animal behavior can be used as a biosensor to signal the presence of human disease. For example, the giant African pouched rats can detect tuberculosis by sniffing sputum specimens while trained honeybees respond to three of the volatile organic compounds (VOCs) detected in the breath of TB positive patients by proboscis extension. However, both rats and honeybees require animal housing facilities and professional trainers, which are outside the scope of most disease testing facilities. Here, we report that the innate olfactory behavioral response of the roundworm nematode <i>Caenorhabditis elegans</i> can be used to detect the TB-specific VOCs methyl <i>p</i>-anisate, methyl nicotinate, methyl phenylacetate and <i>o</i>-phenylanisole, in chemotaxis assays. Dauer larvae, a long-lived stress resistant alternative development state of <i>C. elegans</i> in which the animals can survive for extended periods of time in dry conditions with no food, were also demonstrated to detect the VOCs. We propose that exposing naive dauer larvae to TB-related VOCs and recording their response in this behavioral assay could lead to the development of a new method for TB diagnostics using breath as the sample type.

Asencio C et al. (2012) Cell "Coordination of kinase and phosphatase activities by Lem4 enables nuclear envelope reassembly during mitosis."

Wallenfang MR, Mall M, Ly-Hartig TB, Gorjanacz M, Santarella-Mellwig R, Mattaj IW, Asencio C, Davidson IF

[Cell, 2012]

Mitosis in metazoa requires nuclear envelope (NE) disassembly and reassembly. NE disassembly is driven by multiple phosphorylation events. Mitotic phosphorylation of the protein BAF reduces its affinity for chromatin and the LEM family of inner nuclear membrane proteins; loss of this BAF-mediated chromatin-NE link contributes to NE disassembly. BAF must reassociate with chromatin and LEM proteins at mitotic exit to reform the NE; however, how its dephosphorylation is regulated is unknown. Here, we show that the C. elegans protein LEM-4L and its human ortholog Lem4 (also called ANKLE2) are both required for BAF dephosphorylation. They act in part by inhibiting BAF's mitotic kinase, VRK-1, in vivo and in vitro. In addition, Lem4/LEM-4L interacts with PP2A and is required for it to dephosphorylate BAF during mitotic exit. By coordinating VRK-1- and PP2A-mediated signaling on BAF, Lem4/LEM-4L controls postmitotic NE formation in a function conserved from worms to humans.

Bossinger O et al. (1992) Dev Biol "Cell-cell communication in the embryo of Caenorhabditis elegans."

Schierenberg E, Bossinger O

[Dev Biol, 1992]

We have investigated the pattern of cell-cell communication in embryos of the free-living soil nematode Caenorhabditis elegans. For this, we have established a method for microinjection of tracer dyes into individual blastomeres. After iontophoresis of fluorescent dyes of different molecular weights (Lucifer yellow, LY, M(r) 457; rhodamine-labeled dextran, RD, M(r) 4000), we can visualize intercellular communication pathways. The dye-spread of LY, indicating communication via gap junctions, becomes first visible in the late 2-cell stage. From the 4-cell stage onward all cells appear to be well coupled by communication channels, which allow the free diffusion of LY. In contrast, RD remains restricted to the injected cell and its descendants. After the primordial germcell P4 has been generated in the 24-cell stage, dye-spread of LY into this cell and its somatic sister D is delayed. However, the restricted dye-coupling of D is only temporary. After a brief period it joins the somatic compartment. With the beginning of the morphogenesis phase the two existing germline cells (the daughters of P4) are completely uncoupled from the soma, while the latter still forms a single dye-coupling compartment. Only during the second half of embryogenesis different separate somatic communication compartments are established. We followed the pattern of intercellular communication in the alimentary tract and found a progressive restriction into smaller dye-coupling units. Our data are compared to those found in other systems and discussed with respect to cellular determination and differentiation.

Bossinger O et al. (1996) Dev Biol "Early embryonic induction in C. elegans can be inhibited with polysulfated hydrocarbon dyes."

Schierenberg E, Bossinger O

[Dev Biol, 1996]

During embryogenesis of Caenorhabditis elegans cellular interactions are necessary to determine the fate of blastomeres. In one of these interactions, taking place in the 4-cell stage, the germline cell P2 induces longitudinal orientation of the cleavage spindle in the neighboring EMS cell, its asymmetric division, and the establishment of a gut lineage. Application of several polysulfated hydrocarbon dyes (e.g., trypan blue, TB) in the 1- to 4-cell stages inhibits induction of the gut precursor cell. However, dye application from the late 4-cell stage onward does not interfere with gut induction, supporting the earlier finding of a short time window for this interaction. We also tested the effect of TB on the induction of pharyngeal muscle cells by the MS blastomere, which appears to involve a surface receptor-ligand interaction. We found that this process is inhibited as well. These and additional data indicate that polysulfated hydrocarbon dyes are suitable tools to generally interfere with cell-cell interactions in the nematode embryo.

Hans S et al. (2020) Microb Pathog "Rec A disruption unveils cross talk between DNA repair and membrane damage, efflux pump activity, biofilm formation in Mycobacterium smegmatis."

Hameed S, Hans S, Purkait D, Bansal M, Fatima Z, Nandan S

[Microb Pathog, 2020]

Tuberculosis (TB) caused by Mycobacterium tuberculosis (MTB) has emerged in recent decades as one of the leading causes of mortality worldwide. The burden of TB is alarmingly high, with one third affected global population as reported by WHO. Short-course treatment with an antibiotic is a powerful weapon to treat infection of susceptible MTB strain, however; MTB has developed resistance to anti-TB drugs, which is an escalating global health crisis. Thus there is urgent need to identify new drug targets. RecA is a 38 kilodalton protein required for the repair and maintenance of DNA and regulation of the SOS response. The objective of this study is to understand the effect of disruption of RecA gene (deletion mutant disA from previous study) in a surrogate model for MTB, Mycobacterium smegmatis. This study demonstrated that disruption of RecA causes enhanced susceptibility towards rifampicin and generation of ROS leading to lipid peroxidation and impaired membrane homeostasis as depicted by altered cell membrane permeability and efflux pump activity. Mass spectrometry based lipidomic analysis revealed decreased mycolic acid moieties, phosphatidylinositol mannosides (PIM), Phthiocerol dimycocerosate (DIM). Furthermore, biofilm formation was considerably reduced. Additionally, we have validated all the disrupted phenotypes by RT-PCR which showed a good correlation with the biochemical assays. Lastly, RecA mutant displayed reduced infectivity in Caenorhabditis elegans illustrating its vulnerability as antimycobacterial target. Together, present study establishes a link between DNA repair, drug efflux and biofilm formation and validates RecA as an effective drug target. Intricate studies are needed to further understand and exploit this therapeutic opportunity.

Pal R et al. (2019) 3 Biotech "Understanding lipidomic basis of iron limitation induced chemosensitization of drug-resistant Mycobacterium tuberculosis."

Kumar P, Singh S, Fatima Z, Hameed S, Pal R

[3 Biotech, 2019]

Under limited micronutrients condition, <i>Mycobacterium tuberculosis</i> (MTB) has to struggle for acquisition of the limited micronutrients available in the host. One such crucial micronutrient that MTB requires for the growth and sustenance is iron. The present study aimed to sequester the iron supply of MTB to control drug resistance in MTB. We found that iron restriction renders hypersensitivity to multidrug-resistant MTB strains against first-line anti-TB drugs. To decipher the effect of iron restriction on possible mechanisms of chemosensitization and altered cellular circuitry governing drug resistance and virulence of MTB, we explored MTB cellular architecture. We could identify non-intact cell envelope, tampered MTB morphology and diminished mycolic acid under iron restricted MDR-MTB cells. Deeper exploration unraveled altered lipidome profile observed through conventional TLC and advanced mass spectrometry-based LC-ESI-MS techniques. Lipidome analysis not only depicted profound alterations of various lipid classes which are crucial for pathogenecity but also exposed leads such as indispensability of iron to sustain metabolic, genotoxic and oxidative stresses. Furthermore, iron deprivation led to inhibited biofilm formation and capacity of MTB to adhere buccal epithelial cells. Lastly, we demonstrated enhanced survival of <i>Mycobacterium-</i>infected <i>Caenorhabditis elegans</i> model under iron limitation. The present study offers evidence and proposes alteration of lipidome profile and affected virulence traits upon iron chelation. Taken together, iron deprivation could be a potential strategy to rescue MDR and enhance the effectiveness of existing anti-TB drugs.

Koyiloth M et al. (2020) Eur Biophys J "Molecular cloning and biochemical characterization of the phospholipid scramblase SCRM-1 from Caenorhabditis elegans."

Koyiloth M, Gummadi SN

[Eur Biophys J, 2020]

In this study, the SCRM-1 gene from Caenorhabditis elegans was cloned and overexpressed in E. coli to study the biochemical properties of scramblase. This is the first report showing that this scramblase from C. elegans possesses a Ca²⁺-dependent and head group-independent scramblase activity. The SCRM-1 of C.elegans possesses functional domains including a single EF-hand-like Ca²⁺ binding domain, as human scramblases do. A point mutation in the EF-hand-like Ca²⁺ binding motif results in loss of scramblase activity. Other biochemical assays like carbocyanine staining, Tb³⁺ luminescence, Tryptophan fluorescence, and CD spectroscopy strongly proved the role of the EF-hand motif for functional activity. The increase in protein size in solution upon incubating with Ca²⁺ shows ligand-dependent oligomerization and conformational changes.

Bossinger O et al. (1992) Development "Transfer and tissue-specific accumulation of cytoplasmic components in embryos of Caenorhabditis elegans and Rhabditis dolichura: in vivo analysis with a low-cost signal enhancement device"

Schierenberg E, Bossinger O

[Development, 1992]

The pattern of autofluorescence in the two free-living soil nematodes Rahbditis dolichura and Caenorhabditis elegans has been compared. In C. elegans, during later embryogenesis the prospective gut cells develop a typical bluish autofluorescence as seen under UV illumination, whil in Rh. dolichura a strong autofluorescence is already present in the unfertilized egg. Using a new, low-cost signal enhancement device, we have been able to follow in vivo the dramatic change in the pattern of autofluorescence during embryogenesis of Rh. dolichura. Autofluorescent material accumulates progressively in the gut promordium and disappears completely from all other cells. To investigate whether such an accumulation of cytoplasmic components also takes place in the C. elegans embryo, we labeled the cytoplasm of the egg with the fluorescing tracer dyes Lucifer Yellow (LY) or Rhaodamie 6G (R6G). While LY appears to bind to yolk and progressively accumulates in the developing gut primordium, R6G does not show any such binding and remains equally distributed over all cells. Measurements in early and late stages indicate a significant increase in the volume of the gut cells during embryogenesis, while the embryo as a whole does not grow. Moreover, in cleavage-blocked 2-cell stages after development overnight, a reversal of cell size relationship to the benefit of the gut precursor takes place. In summary, our observations suggest a previously unknown massive transfer of yolk components in the nematode embryo from non-gut cells into lysosomes of the gut primordium, where they are futher metabolized during postembryonic development.