The nature of dendritic cells of the epidermis of the white guinea pig.

The melanocytes, the intermediate cells of Billingham and Medawar and the Langerhans' cells of the epidermis of the white guinea pig were found to be positive to Bielschowsky's silver and Gomori's acetylcholinesterase reactions. The melanocytes were full of Nissl substance. On these evidences, supported by other morphological and histochemical characteristics, the dendritic cells of the epidermis were considered to be nervous structures.     

The two pathways for oxygen exchange by actomyosin and myofibrils and their dependence on temperature

At an intermediate stage in the hydrolysis of MgATP by actomyosin there is an exchange of oxygen between water and the terminal phosphoryl group of MgATP, tightly bound to the myosin active site. This intermediate oxygen exchange results from the reversible hydrolysis of the bound MgATP. The rate of the exchange cycle (hydrolysis and the reverse) is assumed to be determined by the rate of reverse hydrolysis; and the average time available for exchange is determined by the post-exchange reaction that immediately follows the cycle. Past analytical studies of the exchange, using actomyosin mixtures and myofibrils at room temperature, have revealed two pathways for hydrolysis, operating at a comparable flux but differing greatly in the extent of exchange they support. It is shown here that these pathways also appear over a range of temperatures from 5 to 30 degrees C and that temperature had little effect on their relative fluxes. At each temperature, the flux ratio (%) for the low exchange pathway: high exchange pathway was near 50:50 for actomyosin mixtures and 60:40 for myofibrils. Apparently, the rate-limiting steps that determine the fluxes of the two pathways have a similar temperature dependence. However, the analysis indicates that one or both of the steps that determine the extent of exchange (reverse-hydrolysis and/or the post-exchange reaction) shows a different temperature dependence for the two pathways. We interpret this to reflect a difference in the temperature dependence of the post-exchange reaction, which we propose is exceedingly fast and independent of actin concentration along the low exchange route, but slow and dependent on the actin concentration along the high exchange route. Thus at all temperatures over a broad range of actin concentration there are two pathways of comparable flux that differ primarily in the time available for exchange.     

Fast Fourier infrared spectroscopy to characterize the biochemical composition in diatoms

Diatoms are photosynthetic unicellular microalgae and are nature’s hidden source of several biosynthetic metabolites with their use in biofuel, food and drug industries. They mainly contain various lipids, sterols, isoprenoids and toxins with their use in apoptotic, fertility controlling and cancer drugs. Chemical studies on diatoms are limited due to various limitations such as variation of nutrients, contaminants and change in seasonal factors in the environment. To overcome these limitations, we obtained axenic cultures of 12 fresh-water diatom strains on the 22nd day of inoculation having a dry weight of 1 mg each and performed their Fourier transform infrared (FTIR) study for the detection of functional groups responsible for their chemical moiety. The spectral mapping showed a varied level of polyunsaturated fatty acids, amides, amines, ketone bodies and esters for their applications in various pharmacological, food and biofuel industries in the exponential phase of their growth in f/2 media. The FTIR study of the 12 diatom strains showed various similarities in the form of some common peak patterns ranging from 3000 to 3600 cm^?1 for ν_O–H absorption. The symmetric stretching vibration frequency of Diadesmis confervaceae (V2) type species showed different behaviour than others in the spectral region starting from 1600 to 1700 cm^?1. The absorption between 1500 and 1575 cm^?1 reflects the presence of the –N–H group. Infrared (IR) absorptions falling between 1600 and 1700 cm^?1 reflect the presence of amide’s ν_C=O in all species. Placoneis elginensis (V8) type species showed an additional absorption band which is centred around 1735–1750 cm^?1 which perhaps reflects the presence of ester’s ν_C=O. Diadesmis confervaceae (V2), Nitzschia palea (V4), Placoneis elginensis (V8), Nitzschia palea var. debilis (V6), Nitzschia inconspicua (V10), Gomphonema parvulum (V11) and Sellaphora (V12) showed distinct structural features with important key functionalities that can make them essential drug markers in the pharmaceutical industry.     

Structure-based screening and molecular dynamics simulations offer novel natural compounds as potential inhibitors of Mycobacterium tuberculosis isocitrate lyase

Mycobacterium tuberculosis is the etiological agent of tuberculosis in humans and is responsible for more than two million deaths annually. M. tuberculosis isocitrate lyase (MtbICL) catalyzes the first step in the glyoxylate cycle, plays a pivotal role in the persistence of M. tuberculosis, which acts as a potential target for an anti-tubercular drug. To identify the potential anti-tuberculosis compound, we conducted a structure-based virtual screening of natural compounds from the ZINC database (n = 1,67,748) against the MtbICL structure. The ligands were docked against MtbICL in three sequential docking modes that resulted in 340 ligands having better docking score. These compounds were evaluated for Lipinski and ADMET prediction, and 27 compounds were found to fit well with re-docking studies. After refinement by molecular docking and drug-likeness analyses, three potential inhibitors (ZINC1306071, ZINC2111081, and ZINC2134917) were identified. These three ligands and the reference compounds were further subjected to molecular dynamics simulation and binding energy analyses to compare the dynamic structure of protein after ligand binding and the stability of the MtbICL and bound complexes. The binding free energy analyses were calculated to validate and capture the intermolecular interactions. The results suggested that the three compounds had a negative binding energy with ?96.462, ?143.549, and ?122.526 kJ mol^?1 for compounds with IDs ZINC1306071, ZINC2111081, and ZINC2134917, respectively. These lead compounds displayed substantial pharmacological and structural properties to be drug candidates. We concluded that ZINC2111081 has a great potential to inhibit MtbICL and would add to the drug discovery process against tuberculosis.     

Differentially Expressed Peroxidases from <Emphasis Type="Italic">Artemisia annua</Emphasis> and Their Responses to Various Abiotic Stresses

Artemisia annua is well-known for producing the antimalarial phytomolecule, artemisinin. The role of peroxidases has been hypothesized in artemisinin metabolism owing to the presence of an –O–O– linkage in this sesquiterpene lactone. Earlier, using a microarray, we identified differentially expressed genes, including peroxidases, in plant growth stages having contrasting artemisinin content. Here, three peroxidases—Aa547, having higher expression in low-artemisinin stage, and Aa540 and Aa528, having higher expression in high artemisinin stage, which could be associated with trichomes on the basis of their approximate gene expression pattern inferred from EST counts in UniGene—were selected for full-length cloning, tissue-specific expression profiling, and in silico analyses. The upstream genomic region of Aa547 was cloned and various cis-regulatory elements were identified. All the three candidates were predicted to be class III plant peroxidases. Further, this study aimed to check the responsiveness of the logically selected peroxidase genes to various abiotic stress factors. Taking cues from previous reports and the regulatory elements observed in the Aa547 promoter, hydration, salinity, temperature, salicylic acid, hydrogen peroxide, and methyl jasmonate, were selected to study their effect on the expression of the peroxidase genes through qRT-PCR. The peroxidases were found to be highly sensitive to the various factors but differed in their responses. Broadly, except for responses to high temperature and salicylic acid, the response of Aa547 to various factors was distinct from that of Aa540 and Aa528, which was in line with its distinctness from the other two peroxidases, considering the in planta artemisinin content and predicted structural features.     

Differential susceptibility in some sorghum (Sorghum vulgar) genotypes to zinc deficiency in soil

Summary Nine genotypes of sorghum were screened for their relative susceptibility to zinc deficiency in soil. All the varieties were highly responsive to zinc application, but behaved differently under zinc stress conditions in respect of dry-matter production, zinc concentration and uptake. The varieties, JS-263, 29/1, JS-20 and Son 127×SL-245 and CSH-1 were relatively more susceptible to zinc deficiency than 3677×6352, Son 3×SL 209, CSH-3 and 2077×1151. re]19730102     

NADPH oxidase but not myeloperoxidase protects lymphopenic mice from spontaneous infections

The adaptive immune system plays an important role in host defense against invading micro-organisms. Yet, mice deficient in T- and B-cells are surprisingly healthy and develop few spontaneous infections when raised under specific pathogen-free conditions (SPF). The objective of this study was to ascertain what role phagocyte-associated NADPH oxidase or myeloperoxidase (MPO) plays in host defense in mice lacking both T- and B-cells. To do this, we generated lymphopenic mice deficient in either NADPH oxidase or MPO by crossing gp91(phox)-deficient (gp91 ko) or MPO ko mice with mice deficient in recombinase activating gene-1 (RAG ko). We found that neither gp91 ko, MPO ko mice nor lymphocyte-deficient RAG ko mice developed spontaneous infections when raised under SPF conditions and all mice had life spans similar to wild-type (WT) animals. In contrast, gp91xRAG double-deficient (DKO) but not MPOxRAG DKO mice developed spontaneous multi-organ bacterial and fungal infections early in life and lived only a few months. Infections in the gp91xRAG DKO mice were characterized by granulomatous inflammation of the skin, liver, heart, brain, kidney, and lung. Addition of antibiotics to the drinking water attenuated the spontaneous infections and increased survival of the mice. Oyster glycogen-elicited polymorphonuclear neutrophils (PMNs) and macrophages obtained from gp91 ko and gp91xRAG DKO mice had no detectable NADPH oxidase activity whereas WT, RAG ko, and MPOxRAG DKO PMNs and macrophages produced large and similar amounts of superoxide in response to phorbol myristate acetate. The enhanced mortality of the gp91xRAG DKO mice was not due to defects in inflammatory cell recruitment or NO synthase activity (iNOS) as total numbers of elicited PMNs and macrophages as well as PMN- and macrophage-derived production of nitric oxide-derived metabolites in these mice were similar and not reduced when compared to that of WT mice. Taken together, our data suggest that that NADPH oxidase but not MPO (nor iNOS) is required for host defense in lymphopenic mice and that lymphocytes and NADPH oxidase may compensate for each other's deficiency in providing resistance to spontaneous bacterial infections.