General features in the stoichiometry and stability of ionophore A23187-cation complexes in homogeneous solution

Existing literature describing the stoichiometry and stability of complexes between A23187 and divalent cations in solution has been extended to include additional transition series cations, the heavy-metal cations Cd2+ and Pb2+, plus seven lanthanide series trivalent cations. Stability constants of 1:1 complexes between the ionophore and the divalent cations vary by 6.2 orders of magnitude between Cu2+ and Ba2+ which are the strongest and weakest complexes, respectively. Considering alkaline-earth and first-series transition cations together, the pattern of stability constants obeys the extended Irving-Williams series as is seen with many nonionophorous liganding agents. Cd2+ and Pb2+ are bound with an affinity similar to those of Mn2+ and Zn2+, whereas the lanthanides are bound with little selectivity and slightly higher stability. Titration of the ionophore in the 10(-5) M concentration range with di- and trivalent cations gives rise first to complexes of stoichiometry MA2 and subsequently to MA as the metal concentration is increased. The second stepwise stability constants for formation of the MA2 species exceeds the first constant by approximately 10-fold. With lanthanides, heavy metals, and transition-metal cations, OH-, at near physiological concentrations, competes significantly with free ionophore for binding to the 1:1 complexes. This competition is not apparent when Ca2+ or Mg2+ are the central cations. Possible implications of the 1:1 complex selectivity pattern, the ionophore-hydroxide competitive binding equilibria, and potential ternary complexes involving 1:1 ionophore:cation complexes and other anions present in biological systems are discussed with respect to the ionophore's transport selectivity and biological actions.     

Suppression of bioactive luteinizing hormone and testosterone by a progesterone antagonist ZK 98.734 in adult male common marmosets, Callithrix jacchus

The effects of a progesterone antagonist ZK 98.734 on release of bioactive luteinizing hormone (LH) and testosterone were studied in adult male common marmosets by using the following experimental protocols: (1) the blocking of the nocturnal rise in testosterone levels by ZK 98.734, (2) the pharmacodynamic effects of ZK 98.734 on testosterone and LH levels, (3) the reversal of ZK 98.734-induced decrease in testosterone by treatment with human chorionic gonadotropin (hCG), and (4) the blocking of estradiol-induced positive feedback release of LH by ZK 98.734. Sixteen adult male common marmosets were used for different experiments after resting them for at least 4 wk between experiments. Testosterone and bioactive LH levels were measured by specific radioimmunoassay and in vitro bioassay methods, respectively. Treatment (i.m.) of male common marmosets (n = 6/group) with ZK 98.734 (1 mg or 5 mg/day) at 1700 h for 3 consecutive days significantly (p less than 0.05) suppressed the nocturnal (2200 h) rise in testosterone levels. The effects of the two doses were not dose-related; however, the decrease on the first day of treatment was more pronounced with the 5-mg dose than with the 1-mg dose. Diurnal rhythms were restored during the post-treatment period. Similarly, treatment with ZK 98.734 (5 mg, n = 8/group) at 1000 h caused a decrease in testosterone and LH levels. The levels were significantly (p less than 0.05) lower at 3 and 6 h after treatment compared to pretreatment levels.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serum hormone levels in women undergoing abortion with intra-amniotic,extra-amniotic or intra-muscular administration of 15(S)15-methyl-prostaglandin F2α

The serum levels of estradiol-17β, progesterone and HPL have been estimated by specific radioimmunoassay in thirty women undergoing abortion with 15-methyl-PGF_2α given by intra-amniotic, extra-amniotic or intra-muscular route. A significant decline in the levels of these hormones was observed in 27 cases in which the pregnancy was terminated. However, in the remaining three cases, 15-methyl-PGF_2α was found to be unsuccesful, and no significant change in the hormone levels was evident. The decline in these hormones was more marked by intra-muscular route, than that observed by the other routes. The pattern of estradiol-17β decline was more consistent when compared with progesterone and HPL. The levels of progesterone and HPL, in a few cases, rather showed an increase in the initial hours of 15-methyl-PGF_2α administration before the decline began and this pattern was more prominent on extra-amniotic administration. In general, the decline in the hormone levels was slower in cases which took longer time for abortion than cases with shorter induction-abortion time (IAT).The decline in estradiol-17β levels was about 65 percent at six hour of intra-muscular administration of 15-methyl-PGF_2α, whereas the corresponding fall with intra-amniotic and extra-amniotic routes was 29 and 22 percent, respectively. However, the net drop in its levels during IAT was not significantly different (range 70 to 80 percent) by the three routes. About 38 percent fall in progesterone levels was observed at six hour of intra-muscular administration whereas, by intra-amniotic the fall was 19 percent. The net decline in progesterone levels, during IAT, was in the range of 46 to 60 percent by the three routes. Similarly, intra-muscular 15-methyl-PGF_2α evoked a sharper decline in HPL levels as compared with other routes. The total decline during IAT was 58 to 66 percent. The results, thus indicated that the abortion with 15-methyl-PGF_2α was associated with a fall in the serum hormone levels, which could be resultant effect of alterations in the hormone production by the foeto-placental unit. This along with the uterine contractions may play a significant role in the abortifacient action of 15-methyl-PGF_2α.     

Arthrobacter pokkalii sp nov,a Novel Plant Associated Actinobacterium with Plant Beneficial Properties,Isolated from Saline Tolerant Pokkali Rice,Kerala, India

A novel yellow colony-forming bacterium, strain P3B162^T was isolated from the pokkali rice rhizosphere from Kerala, India, as part of a project study aimed at isolating plant growth beneficial rhizobacteria from saline tolerant pokkali rice and functionally evaluate their abilities to promote plant growth under saline conditions. The novel strain P3B162^T possesses plant growth beneficial traits such as positive growth on 1-aminocyclopropane-1-carboxylic acid (ACC), production of indole acetic acid (IAA) and siderophore. In addition, it also showed important phenotypic characters such as ability to form biofilm and utilization of various components of plant root exudates (sugars, amino acids and organic acids), clearly indicating its lifestyle as a plant rhizosphere associated bacterium. Taxonomically, the novel strain P3B162^T was affiliated to the genus Arthrobacter based on the collective results of phenotypic, genotypic and chemotaxonomic analyses. Moreover, molecular analysis using 16S rRNA gene showed Arthrobacter globiformis NBRC 12137^T, Arthrobacter pascens DSM 20545^T and Arthrobacter liuii DSXY973^T as the closely related phylogenetic neighbours, showing more than 98% 16S rRNA similarity values, whereas the recA gene analysis displayed Arthrobacter liuii JCM 19864^T as the nearest neighbour with 94.7% sequence similarity and only 91.7% to Arthrobacter globiformis LMG 3813^T and 88.7% to Arthrobacter pascens LMG 16255^T. However, the DNA-DNA hybridization values between strain P3B162^T, Arthrobacter globiformis LMG 3813^T, Arthrobacter pascens LMG 16255^T and Arthrobacter liuii JCM 19864^T was below 50%. In addition, the novel strain P3B162^T can be distinguished from its closely related type strains by several phenotypic characters such as colony pigment, tolerance to NaCl, motility, reduction of nitrate, hydrolysis of DNA, acid from sucrose, cell wall sugars and cell wall peptidoglycan structure. In conclusion, the combined results of this study support the classification of strain P3B162^T as a novel Arthrobacter species and we propose Arthrobacter pokkalii sp.nov.as its name. The type strain is P3B162^T (= KCTC 29498^T = MTCC 12358^T).     

Biology and comparative predation efficacy of three heteropteran species recorded as predators ofBemisia tabaci in Maharashtra

Two mirids,Deraeocoris sp. andCampylomma nicolasi Reuter and one lygaeid,Geocoris ochropterus Fieber were found preying onB. tabaci (Gennadius) for the first time in Maharashtra State of India during 1987–88. Their biology and predation capacity onB. tabaci were studied in detail under laboratory conditions. The nymphal stage ofDeraeocoris sp. passed through 6 instars, whereas 5 instars in case of the remaining species.G. ochropterus, Deraeocoris sp. andC. nicolasi consumed on an average 482.5, 275.3 and 128.8 nymphs of 57.3, 25.5 and 20.6 days, respectively. On the basis of consumption rate per day,Deraeocoris sp. proved to be a superior predator. Part of Ph. D. Thesis submitted to Marathwada Agricultural University, Parbhani 431402, India.     

A Comprehensive Review of Animal Models for Coronaviruses: SARS-CoV-2, SARS-CoV,and MERS-CoV

The recent outbreak of coronavirus disease(COVID-19) caused by the novel severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) has already affected a large population of the world. SARS-CoV-2 belongs to the same family of severe acute respiratory syndrome coronavirus(SARS-CoV) and Middle East respiratory syndrome coronavirus(MERSCoV). COVID-19 has a complex pathology involving severe acute respiratory infection, hyper-immune response, and coagulopathy. At present, there is no therapeutic drug or vaccine approved for the disease. There is an urgent need for an ideal animal model that can reflect clinical symptoms and underlying etiopathogenesis similar to COVID-19 patients which can be further used for evaluation of underlying mechanisms, potential vaccines, and therapeutic strategies. The current review provides a paramount insight into the available animal models of SARS-CoV-2, SARS-CoV, and MERS-CoV for the management of the diseases.     

Aggregation properties of cold-active lipase produced by a psychrotolerant strain of Pseudomonas palleroniana (GBPI_508)

Abstract

The present study aims to exploit microbial potential from colder region to produce lipase enzyme stable at low temperatures. A newly isolated bacterium GBPI_508 from Himalayan environment, was investigated for the production of cold-active lipase emphasizing on its aggregation properties. Plate based assays followed by quantitative production of enzyme was estimated under different culture conditions. Further characterization of partially purified enzyme was done for molecular weight determination and activity and stability under varying conditions of pH, temperature, and in presence of organic solvents, inhibitors, and metal ions. The psychrotolerant bacterium was identified as Pseudomonas palleroniana following 16S rRNA gene sequencing. Maximum lipase production by GBPI_508 was recorded in 7?days at 25?°C utilizing yeast extract as nitrogen source and olive oil as substrate in the lipase production medium. Triton X-100 (1%) in the medium as emulsifier significantly enhanced the lipase production. Lipase produced by bacterium showed aggregation which was confirmed by dynamic light scattering and native PAGE. SDS-PAGE followed by zymogram analysis of partially purified enzyme showed two active bands of ～50?kDa and ～54?kDa. Optimum activity of partially purified enzymatic preparation was recorded at 40?°C while the activity remained nearly consistent from pH 7.0 to 12.0, whereas, maximum stability was recorded at pH values 7.0 and 11.0 at 25?°C. Interestingly, lipase in the partially purified fraction retained 60% enzyme activity at 10?°C. Medium chain pNP ester (C10) was the most preferred substrate for the lipase of GBPI_508. The lipase possessed >50% residual activity when incubated with different organic solvents (25% v/v) except toluene and dichloromethane which inhibited the activity below 50%. Partially purified enzyme was also stable in the presence of metal ions and inhibitors. The study suggests applicability of GBPI_508 lipase in low temperature conditions such as cold-active detergent formulations and cold bioremediation.     

Role of Arabidopsis BBX proteins in light signaling

Journal of Plant Biochemistry and Biotechnology - Light regulates numerous aspects of plant growth and development like seed germination, seedling de-etiolation, pigment accumulation, cotyledon...