Unveiling the Slippery Secrets of Saliva: Effector Proteins of Phloem-Feeding Insects

Phloem-feeding insects include many important agricultural pests that cause crop damage globally, either through feeding-related damage or upon transmission of viruses and microbes that cause plant diseases. With genetic crop resistances being limited to most of these pests, control relies on insecticides, which are costly and damaging to the environment and to which insects can develop resistance. Like other plant parasites, phloem-feeding insects deliver effectors inside their host plants to promote susceptibility, most likely by a combination of suppressing immunity and promoting nutrient availability. The recent emergence of the effector paradigm in plant-insect interactions is highlighted by increasing availability of effector repertoires for a range of species and a broadening of our knowledge concerning effector functions. Here, we focus on recent progress made toward identification of effector repertoires from phloem-feeding insects and developments in effector biology that will advance functional characterization studies. Importantly, identification of effector activities from herbivorous insects promises to provide new avenues toward development of crop protection strategies. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

A Distinct Phylogenetic Cluster of Indian Severe Acute Respiratory Syndrome Coronavirus 2 Isolates

BACKGROUND

From an isolated epidemic, coronavirus disease 2019 has now emerged as a global pandemic. The availability of genomes in the public domain after the epidemic provides a unique opportunity to understand the evolution and spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus across the globe.

METHODS

We performed whole-genome sequencing of 303 Indian isolates, and we analyzed them in the context of publicly available data from India.

RESULTS

We describe a distinct phylogenetic cluster (Clade I/A3i) of SARS-CoV-2 genomes from India, which encompasses 22% of all genomes deposited in the public domain from India. Globally, approximately 2% of genomes, which to date could not be mapped to any distinct known cluster, fall within this clade.

CONCLUSIONS

The cluster is characterized by a core set of 4 genetic variants and has a nucleotide substitution rate of 1.1 × 10-3 variants per site per year, which is lower than the prevalent A2a cluster. Epidemiological assessments suggest that the common ancestor emerged at the end of January 2020 and possibly resulted in an outbreak followed by countrywide spread. To the best of our knowledge, this is the first comprehensive study characterizing this cluster of SARS-CoV-2 in India.

How Harmful Can Herbal Remedies Be? A Case of Severe Acute Tubulointerstitial Nephritis

Acute interstitial nephritis (AIN) is a condition in which acute kidney injury (AKI) is characterized by the histological finding of interstitial inflammation. Hyponidd is an ayurvedic drug containing Momordica charantia, Gymnema sylvestre, Swertia chirata, etc., used for the treatment of Type 2 diabetes mellitus (DM) and polycystic ovarian disease as an insulin sensitizer. There are no case reports of AIN caused by this drug yet. We report a biopsy-proven case of AKI due to severe AIN associated with the use of hyponidd tablet in a 60-year-old male with DM and hypertension. As these types of various indigenous compounds are used as home remedies in our country, awareness about the possible adverse effects of these agents among physicians is very important in the early diagnosis and management.

The biochemical womb of schizophrenia: A review

The conclusive identification of specific etiological factors or pathogenic processes in the illness of schizophrenia has remained elusive despite great technological progress. The convergence of state-of-art scientific studies in molecular genetics, molecular neuropathophysiology, in vivo brain imaging and psychopharmacology, however, indicates that we may be coming much closer to understanding the genesis of schizophrenia. In near future, the diagnosis and assessment of schizophrenia using biochemical markers may become a "dream come true" for the medical community as well as for the general population. An understanding of the biochemistry/ visa vis pathophysiology of schizophrenia is essential to the discovery of preventive measures and therapeutic intervention.

Hemopexin in the human retina: protection of the retina against heme-mediated toxicity

The existence of the blood-retinal barrier means that proteins that protect the retina from damage by reactive oxygen species must either be made locally or specifically transported across the barrier cells; however, such transepithelial transport does not seem to occur. Among the circulatory proteins that protect against iron-catalyzed production of free radicals are apo-transferrin, which binds ferric iron and has previously been shown to be made by cells of the neural retina (Davis and Hunt, 1993, J. Cell Physiol., 156:280-285), and the extracellular antioxidant, apo-hemopexin, which binds free heme (iron-protoporphyrin IX). Since hemorrhage and heme release can be important contributing factors in retinal disease, evidence of a hemopexin-based retinal protection system was sought. The human retina has been shown to contain apo-hemopexin which is probably synthesized locally since its mRNA can be detected in retinal tissue dissected from human donor eyes. It is likely that the retina contains a mechanism for the degradation of hemopexin-bound heme since the blood-retinal barrier also precludes the exit of heme-hemopexin from the retina. Retinal pigment epithelial cells have been found to bind and internalize heme-hemopexin in a temperature-dependent, saturable, and specific manner, analogous to the receptor-mediated endocytic system of hepatoma cells. Moreover, the binding of heme-hemopexin to the cells stimulates the expression of heme oxygenase-1, metallothionein-1, and ferritin.

Sin, a stage-specific repressor of cellular differentiation

Sin is a Bacillus subtilis DNA-binding protein which is essential for competence, motility, and autolysin production but also, if expressed on a multicopy plasmid, is inhibitory to sporulation and alkaline protease synthesis. We have now examined the physiological role of Sin in sporulation and found that this protein specifically represses three stage II sporulation genes (spoIIA, spoIIE, and spoIIG) but not the earlier-acting stage 0 sporulation genes. sin loss-of-function mutations cause higher expression of stage II genes and result in a higher frequency of sporulation, in general. Sin binds to the upstream promoter region of spoIIA in vitro and may thus gate entry into sporulation by directly repressing the transcription of stage II genes. In vivo levels of Sin increase rather than decrease at the time of stage II gene induction, suggesting that posttranslational modification may play a role in downregulation of negative Sin function.

The role of negative control in sporulation

Negative controls play an important role in the regulation of differentiation in many organisms. Sporulation in Bacillus subtilis is also regulated by DNA-binding proteins which exert a repressive effect on genes which are essential for this process. AbrB represses spo0H, coding for sigma H. One of the earliest events in the initiation of sporulation is the lifting of this repression so that more sigma H can be made. As part of an RNA polymerase holoenzyme, this positive transcription factor is responsible for the elevated synthesis of sufficient phosphorylated Spo0A to activate the expression of several stage II genes. Sin, another DNA-binding protein, represses the same genes, spoIIA, spoIIE and spoIIG, that are activated by Spo0A. Thus sporulation is controlled at the two earliest stages by at least two repressors. Sin and AbrB are repressors of other late growth functions but are essential for competence development. Sin is also a positive regulator for motility and autolysin production. These results suggest that AbrB and Sin act as developmental switches, enabling cells at the beginning of stationary growth to choose different developmental fates.

The physicochemical properties of the galactose-specific lectin from Momordica charantia

A lectin has been isolated from Momordica charantia seeds and purified to homogeneity by affinity adsorption on a cross-linked arabinogalactan column and subsequent elution with 0.1 M lactose. In sedimentation velocity experiments an S20,W(O) degrees value of 6.5 S was obtained for the native lectin and 2.7 S for its subunits obtained by dissociation with 0.1% sodium dodecyl sulphate in the presence of 0.1% 2-mercaptoethanol. This lectin has a molecular weight of 120 000, is tetrameric in nature with two pairs of non-identical subunits of molecular weights 28 000 and 30 000. It is a glycoprotein containing 10% hexoses (2% glucose and 8% mannose) and 2.5% hexosamine, all glucosamine. It has two binding sites per molecule and has Ka values of 4.1 X 10(4) M-1 and 1.8 X 10(4) M-1 at 5 degrees C and 25 degrees C respectively for p-nitrophenyl beta-D-galactopyranoside with delta H degrees and delta S degrees values of --28.3 kJ mol-1 and --12.3J mol-1 K-1 respectively. Hemagglutinating activity of M. charantia lectin is inhibited by galactose and other carbohydrates containing the galactopyranosyl residue. From the chemical modification studies tryptophan and tyrosine residues are found to be important for the carbohydrate binding activity of M. charantia lectin.

Binding of 4-methylumbelliferyl beta-D-galactopyranoside to Momordica charantia lectin: fluorescence-quenching studies

The binding of 4-methylumbelliferyl beta-D-galactopyranoside (MeUmb-Galp), to Mormordica charantia lectin was studied by equilibrium dialysis and quenching of ligand fluorescence. The fluorescence of MeUmb-Galp decreases as a function of solvent polarity. On binding to M. charantia lectin, its fluorescence was nearly 100% quenched, showing that the binding of the glycoside takes place in hydrophobic environment. The binding of the fluorescent sugar was saccharide-specific as evidenced by reversal of MeUmb-Galp fluorescence quenching by lactose. The association constant is independent of the experimental method used and at 25 degrees C the value is (1.96 +/- 0.05) X 10(4) M-1. The number of binding sites as determined by equilibrium dialysis and fluorescence quenching agree very well with each other; n being equal to 1.98 +/- 0.02. The Ka value for the glycoside was also determined by competition studies employing reversal of fluorescence quenching of MeUmb-Galp by lactose. The value of ka obtained for lactose is 1.21 X 10(4) M-1 at 30 degrees C. The internal consistency of the association constant and number of binding site values at low and high saturation indicates the absence of additional subsite on M. charantia lectin. The thermodynamic parameters do not differ greatly with change in temperature; the values of - delta H degrees and - delta S degrees are equal to 30 +/- 9.63 kJ mol-1 and 21 +/- 0.3 J mol-1 K-1 respectively in the range of 15--35 degrees C indicting that the binding of M. charantia lectin to saccharide is exothermic in nature.

Effect of ruthenium on nitrogen fixation by some nitrogen fixers

The effect of ruthenium chloride in the culture media on the nitrogen-fixing ability of the three nitrogen fixers (unidentified species of Azotobacter, designated here as D3, B3, and B), isolated from Allahabad soil, was studied. It was observed that the nitrogen-fixing ability of the organisms is much increased in presence of 25-75 micro M concentration of ruthenium chloride in the culture media, while sugar consumption remains more or less steady. Also, if mg nitrogen fixed/g carbon consumed in two culture media with successive increasing concentrations of ruthenium chloride is compared by calculating the difference in increase of the amount of nitrogen fixed and carbon consumed in these two culture media, it was observed that high amounts of nitrogen are fixed by B3 and B between 25-50 micro M, and between 50-75 micro M concentration of ruthenium chloride by D3.