Some properties of glutamine synthetase from the nitrifying bacterium Nitrosomonas europaea

Nitrosomonas europaea oxidizes ammonia to nitrite, thereby deriving energy for growth. Glutamate dehydrogenase (NADP+) (EC 1.4.1.4) is the main route for the incorporation of ammonia into glutamic acid, because glutamate synthase (NADPH)(EC 1.4.1.13) was not detected in cell-free extracts of N. europaea. Some properties of a partially purified glutamine synthetase (EC 6.3.1.2) have been determined, namely the effects of pH and metal ions, substrate requirements, Km and Ki values, based on biosynthetic and gamma-glutamyltransferase (EC 2.3.2.2) assays. The molecular weight of the enzyme preparation was approximately 440 000. The gamma-glutamyltransferase activity was markedly inhibited by alanine, lysine, glutamic acid, aspartic acid and serine and to a lesser extent by glycine, asparagine, arginine and histidine. Except for tryptophan and cystine, the gamma-glutamyltransferase activity was inhibited to a greater extent by these amino acids than was the biosynthetic activity. Different pairs of amino acids in various combinations resulted in a cumulative inhibition of enzyme activity determined by either method. Of the various nucleotides tested, the gamma-glutamlytransferase activity of the enzyme was inhibited to a greater extent by di- and triphosphate nucleotides--IDP, CDP, UDP, ITP, CTP, TTP and ATP (except GDP and GTP) than by monophosphate nucleotides except AMP. Saturating concentrations of pyruvate, oxalate, oxaloacetate and alpha-ketoglutarate depressed enzyme activity. Various combinations of amino acids with adenine nucleotides exerted cumulative inhibitory effects on the transferase activity.     

A panel of polymorphic microsatellite markers in Himalayan monal Lophophorus impejanus developed by cross-species amplification and their applicability in other Galliformes

Isolation and development of new microsatellite markers for any species is still labour-intensive and requires substantial inputs of time, money and expertise. Therefore, cross-species microsatellite amplification can be an effective way in obtaining microsatellite loci for closely related taxa in bird species. We have reported microsatellite loci for Himalayan monal for the first time. Fifteen microsatellite markers developed for chicken were cross-amplified in Himalayan monal. All the tested 15 microsatellite markers were polymorphic, with mean (± s.e.) allelic number of 4 ± 1.51, ranging 2–7 per locus. The observed heterozygosity in the population ranged between 0.285 and 0.714, with mean (± s.e.) of 0.499 ± 0.125, indicating considerable genetic variation in this population. While 12 loci conformed to Hardy–Weinberg equilibrium (P > 0.05), 3 loci, i.e. MCW0295, MCW0081, MCW0330 deviated from it (P < 0.05). No evidence for linkage disequilibrium was observed among pair of loci. Our study show that these 15 microsatellites loci could be employed in population genetic studies for Himalayan monal and their applicability in Jungle Bush Quail, Grey francolin and Kalij pheasant.

     

Dodecameric structure of a small heat shock protein from Mycobacterium marinum M

Small heat shock proteins (sHSPs) are ATP-independent molecular chaperones present ubiquitously in all kingdoms of life. Their low molecular weight subunits associate to form higher order structures. Under conditions of stress, sHSPs prevent aggregation of substrate proteins by undergoing rapid changes in their conformation or stoichiometry. Polydispersity and dynamic nature of these proteins have made structural investigations through crystallography a daunting task. In pathogens like Mycobacteria, sHSPs are immuno-dominant antigens, enabling survival of the pathogen within the host and contributing to disease persistence. We characterized sHSPs from Mycobacterium marinum M and determined the crystal structure of one of these. The protein crystallized in three different conditions as dodecamers, with dimers arranged in a tetrahedral fashion to form a closed cage-like architecture. Interestingly, we found a pentapeptide bound to the dodecamers revealing one of the modes of sHSP-substrate interaction. Further, we have observed that ATP inhibits the chaperoning activity of the protein.     

Phospholipase C Delta 3 inhibits apoptosis and promotes proliferation,migration, and invasion of thyroid cancer cells via Hippo pathway

In recent decades,the incidence of thyroid cancer (TC) has rapidly increased,leading us to explore the complex underlying mechanisms.We identified the gene Phos...     

Conceptual model of low-cost improvised bubble continuous positive airway pressure device for adults and its potential use in the COVID-19 pandemic

Low-cost improvised continuous positive airway pressure (CPAP) device is safe and efficacious in neonatal respiratory distress. There is a great necessity for similar device in adults, and this has been especially made apparent by the recent Coronavirus Disease 2019 (COVID-19) pandemic, which is unmasking the deficiencies of healthcare system in several low-resource countries. We propose a simplified and inexpensive model of improvised CPAP in adults using locally available resources including aquarium air pumps and a novel pressure release mechanism. Although the safety and efficacy of improvised CPAP in adults are not established, the conceptual model we propose has the potential to serve as a lifesaving technology in many low-resource settings during this ongoing pandemic and thus calls for expedited research.     

Immunobiology of Lipopolysaccharide (LPS) and LPS-Derived Immunoconjugates Vaccinate Mice against Salmonella typhimurium

The immunobiology of lipopolysaccharide (LPS) of Salmonella typhimurium LT2–71 was studied in its native, modified and conjugated states using mice as the experimental model. An alkali-treated detoxified fraction of LPS (D-LPS) was found to be not only non-toxic but also equally immunogenic, like LPS. In addition D-LPS alone or conjugated with enterotoxin or hemolysin was also non-pyrogenic and non-indurogenic. The immunoprophylactic activity of D-LPS conjugates to a 100 ID₅₀ challenge dose of S. typhimurium was also higher than that of detoxified LPS or native LPS.     

δ-Opioid Receptor and Somatostatin Receptor-4 Heterodimerization: Possible Implications in Modulation of Pain Associated Signaling

Pain relief is the principal action of opioids. Somatostatin (SST), a growth hormone inhibitory peptide is also known to alleviate pain even in cases when opioids fail. Recent studies have shown that mice are prone to sustained pain and devoid of analgesic effect in the absence of somatostatin receptor 4 (SSTR4). In the present study, using brain slices, cultured neurons and HEK-293 cells, we showed that SSTR4 and δ-Opioid receptor (δOR) exist in a heteromeric complex and function in synergistic manner. SSTR4 and δOR co-expressed in cortical/striatal brain regions and spinal cord. Using cultured neuronal cells, we describe the heterogeneous complex formation of SSTR4 and δOR at neuronal cell body and processes. Cotransfected cells display inhibition of cAMP/PKA and co-activation of SSTR4 and δOR oppose receptor trafficking induced by individual receptor activation. Furthermore, downstream signaling pathways either associated with withdrawal or pain relief are modulated synergistically with a predominant role of SSTR4. Inhibition of cAMP/PKA and activation of ERK1/2 are the possible cellular adaptations to prevent withdrawal induced by chronic morphine use. Our results reveal direct intra-membrane interaction between SSTR4 and δOR and provide insights for the molecular mechanism for the anti-nociceptive property of SST in combination with opioids as a potential therapeutic approach to avoid undesirable withdrawal symptoms.     

Evaluation of FKBP and DHFR based destabilizing domains in Saccharomyces cerevisiae

Two orthogonal destabilizing domains have been developed based on mutants of human FKBP12 as well as bacterial DHFR and these engineered domains have been used to control protein concentration in a variety of contexts in vitro and in vivo. FKBP12 based destabilizing domains cannot be rescued in the yeast Saccharomyces cerevisiae; ecDHFR based destabilizing domains are not degraded as efficiently in S. cerevisiae as in mammalian cells or Plasmodium, but provide a starting point for the development of domains with increased signal-to-noise in S. cerevisiae.     

Photosynthetic and biochemical characterization of pigments and UV-absorbing compounds in <Emphasis Type="Italic">Phormidium tenue</Emphasis> due to UV-B radiation

We report the effect of UV-B radiation (0.8 ± 0.1 mW cm⁻²) and UV-B radiation supplemented with low-intensity PAR (∼80 μmol photons m⁻² s⁻¹) on the photosynthesis, photosynthetic pigments, phosphoglycolipids, oxidative damage, enzymatic antioxidants, and UV-absorbing compounds in Phormidium tenue, a marine cyanobacterium. UV-B radiation resulted in a decline in photosynthesis and photosynthetic pigments leading to lower biomass. P. tenue synthesized UV-absorbing compounds like mycosporine-like amino acids (MAAs) and scytonemin in response to UV-B radiation. Quantity of MAAs and scytonemin was higher when UV-B was supplemented with low-level PAR. UV-B treatment also resulted in quantitative changes in phosphoglycolipids of the membrane. The UV-B treatment resulted in a slight increase in the level of peroxidation of cell membrane and very little increase in the activity of superoxide dismutase (SOD). Results indicate that UV-B affected photosynthesis and that the main protective system was the synthesis of MAAs and scytonemin-like compounds rather than antioxidant enzymes such as SOD.     

High frequencies of de novo CNVs in bipolar disorder and schizophrenia

While it is known that rare copy-number variants (CNVs) contribute to risk for some neuropsychiatric disorders, the role of CNVs in bipolar disorder is unclear. Here, we reasoned that a contribution of CNVs to mood disorders might be most evident for de novo mutations. We performed a genome-wide analysis of de novo CNVs in a cohort of 788 trios. Diagnoses of offspring included bipolar disorder (n?= 185), schizophrenia (n?= 177), and healthy controls (n?= 426). Frequencies of de novo CNVs were significantly higher in bipolar disorder as compared with controls (OR?= 4.8 [1.4,16.0], p?= 0.009). De novo CNVs were particularly enriched among cases with an age at onset younger than 18 (OR?= 6.3 [1.7,22.6], p?= 0.006). We also confirmed a significant enrichment of de novo CNVs in schizophrenia (OR?= 5.0 [1.5,16.8], p?= 0.007). Our results suggest that rare spontaneous mutations are an important contributor to risk for bipolar disorder and other major neuropsychiatric diseases.