Intramammary Immunization of Pregnant Mice with Staphylococcal Protein A Reduces the Post-Challenge Mammary Gland Bacterial Load but Not Pathology

Protein A, encoded by the spa gene, is one of the major immune evading MSCRAMM of S. aureus, demonstrated to be prevalent in a significant percentage of clinical bovine mastitis isolates in Australia. Given its’ reported significance in biofilm formation and the superior performance of S. aureus biofilm versus planktonic vaccine in the mouse mastitis model, it was of interest to determine the immunogenicity and protective potential of Protein A as a potential vaccine candidate against bovine mastitis using the mouse mastitis model. Pregnant Balb/c mice were immunised with Protein A emulsified in an alum-based adjuvant by subcutaneous (s/c) or intramammary (i/mam) routes. While humoral immune response of mice post-immunization were determined using indirect ELISA, cell-mediated immune response was assessed by estimation of interferon-gamma (IFN-γ) produced by protein A-stimulated splenocyte supernatants. Protective potential of Protein A against experimental mastitis was determined by challenge of immunized versus sham-vaccinated mice by i/mam route, based upon manifestation of clinical symptoms, total bacterial load and histopathological damage to mammary glands. Significantly (p<0.05) higher levels of IgG1 isotype were produced in mice immunized by the s/c route. In contrast, significantly higher levels of the antibody isotype IgG2a were produced in mice immunized by the i/mam route (p<0.05). There was significant reduction (p<0.05) in bacterial loads of the mammary glands of mice immunized by Protein A regardless of the route of immunization, with medium level of clinical symptoms observed up to day 3 post-challenge. However, Protein A vaccine failed to protect immunized mice post-challenge with biofilm producing encapsulated S. aureus via i/mam route, regardless of the route of immunization, as measured by the level of mammary tissue damage. It was concluded that, Protein A in its’ native state was apparently not a suitable candidate for inclusion in a cell-free vaccine formulation against mastitis.     

Myxinidin, A Novel Antimicrobial Peptide from the Epidermal Mucus of Hagfish, Myxine glutinosa L.

Fish epidermal mucus contains innate immune components that provide a first line of defense against various infectious pathogens. This study reports the bioassay-guided fractionation and characterization of a novel antimicrobial peptide, myxinidin, from the acidic epidermal mucus extract of hagfish (Myxine glutinosa L.). Edman sequencing and mass spectrometry revealed that myxinidin consists of 12 amino acids and has a molecular mass of 1,327.68 Da. Myxinidin showed activity against a broad range of bacteria and yeast pathogens at minimum bactericidal concentration (MBC) ranging from 1.0 to 10.0 μg/mL. Screened pathogens, Salmonella enterica serovar Typhimurium C610, Escherichia coli D31, Aeromonas salmonicida A449, Yersinia ruckeri 96-4, and Listonella anguillarum 02-11 were found to be highly sensitive to myxinidin at the MBC of 1.0–2.5 μg/mL; Staphylococcus epidermis C621 and yeast (Candida albicans C627) had an MBC of 10.0 μg/mL. The antimicrobial activity of myxinidin was found to be two to 16 times more active than a potent fish-derived antimicrobial peptide, pleurocidin (NRC-17), against most of the screened pathogens. The microbicidal activity of myxinidin was retained in the presence of sodium chloride (NaCl) at concentrations up to 0.3 M and had no hemolytic activity against mammalian red blood cells. These results suggest that myxinidin may have potential applications in fish and human therapeutics.     

A novel composition for the culture of human adipose stem cells which includes complement C3

Adipose tissue is an easily accessible and abundant source of stem cells. Adipose stem cells (ASCs) are currently being researched as treatment options for repair and regeneration of damaged tissues. The standard culture conditions used for expansion of ASCs contain fetal bovine serum (FBS) which is undefined, could transmit known and unknown adventitious agents, and may cause adverse immune reactions. We have described a novel culture condition which excludes the use of FBS and characterised the resulting culture. Human ASCs were cultured in the novel culture medium, which included complement protein C3. These cultures, called C-ASCs, were compared with ASCs cultured in medium supplemented with FBS. Analysis of ASCs for surface marker profile, proliferation characteristics and differentiation potential indicated that the C-ASCs were similar to ASCs cultured in medium containing FBS. Using a specific inhibitor, we show that C3 is required for the survival of C-ASCs. This novel composition lends itself to being developed into a defined condition for the routine culture of ASCs for basic and clinical applications.     

The dynamics of interconverting D- and E-forms of the HIV-1 integrase N-terminal domain

The N-terminal domain (NTD) of HIV-1 integrase adopts two inter-converting forms (D- and E-) due to their specific coordination of a Zn²⁺ ion by an HHCC motif. Mutational studies on NTD have suggested the importance of conformational transition in regulating the functions of tetramers and dimers of HIV-1 integrase. This study explores the stability and dynamics of native NTD forms and the conformational transition between D- and E-forms using molecular dynamics simulations elucidating their role in regulation of viral and host DNA integration. Simulation of native forms of NTD revealed stable dynamics. Transition studies between D- and E-forms using conventional molecular dynamics simulations for 50 ns partially revealed conformational change towards the target during D- to -E simulation (the extension of α1-helix), which failed in the E- to -D simulation. This could be attributed to the existence of the D-form (?1,945.907 kCal/mol) in higher energy than the E-form (?2,002.383 kCal/mol). The conformational transition pathway between these two states was explored using targeted molecular dynamics simulations. Analysis of the targeted molecular dynamics trajectories revealed conformations closer to the experimentally-reported intermediate form of an NTD during the transition phase. The role of Met22 in stabilizing the E-form was studied by simulating the E-form with Met22Ala mutation, revealing a highly dynamic α1-helix as compared to the native form. The present study reveals the significant role of the Zn²⁺ ion-coordinated HHCC motif and its interaction with Met22 as the basis for understanding the biological implications of D- and E-forms of the NTD in regulating integration reaction.     

Insertion-deletions burden in copy number polymorphisms of the Tibetan population

BACKGROUND:

Many studies have been conducted to identify either insertions-deletions (inDels) or copy number variations (CNVs) in humans, but few studies have been conducted to identify both of these forms coexisting in the same region.

AIMS AND OBJECTIVES:

To map the functionally significant sites within human genes that are likely to influence human traits and diseases.

MATERIALS AND METHODS:

In this report, we describe an inDel map in the 1051 Tibetan CNV regions obtained through CNV genotyping using Affymetrix Genome-wide single nucleotide polymorphism 6.0 chip. InDel polymorphisms in these copy number polymorphism regions were identified with a computational approach using the 2500 deoxyribonucleic acid sequences obtained from the 1000 Genome Project.

RESULTS:

The study identified a total of 95935 inDels that range from 1 bp to several bps in length which were found scattered across regulatory regions, exons and in introns of genes underlying the CNVs. A study on the distribution of inDels revealed that the majority of inDels were found in coding regions of the genome than the noncoding, while within the genes, inDels in intron regions were more followed by exonic regions and finally the regulatory regions.

CONCLUSION:

Study of inDels in CNV regions contribute to the enhanced understanding of the role played by the two variations and their collective influence on the genome. Further, a collection of these inDel genetic markers will aid in genetic mapping, further understanding of the phenotypic variability, identification of disease genes and in detecting novel CNVs.     

PPAR’s and Diosgenin a chemico biological insight in NIDDM

Diosgenin a steroidal saponin found widely in nature is reported to contain several biological activities in recent years. The present work elaborates the modulation of the lipid and antioxidant profile by Diosgenin in diabetic condition. Type 2 diabetes was induced in experimental animals by feeding high fat diet (HFD) for 8 weeks followed by streptozotocin (STZ) injection (sub-diabetogenic dose; 35 mg/kg body weight). Diosgenin administered orally at two doses (40 and 80 mg/kg body weight) for 14 days reduced hyperglycemia, hypercholesterolemia and hypertriglyceridemia (p < 0.001). Oxidative stress a crucial marker of diabetes and obesity associated complications was analyzed and noteworthy changes were observed. Improved levels of the antioxidant enzymes SOD and GPx and a minimized level of lipid peroxidation were also observed in Diosgenin treated rats. Further, analyzing the lipid accumulation by Oil Red O staining in 3T3-L1 preadipocytes confirmed its adipogenic activity which was influenced by PPAR γ and PPAR α. This was also substantiated through docking studies of Diosgenin with the PPARs. Altogether, Diosgenin a phytochemical of natural origin is found to mitigate diabetes induced oxidative stress and dyslipidemia which is crucial in cardio-metabolic risks by modulating the PPARs.     

Molecular recognition of the substrate diphosphate group governs product diversity in trichodiene synthase mutants

The X-ray crystal structures of Y305F trichodiene synthase and its complex with coproduct inorganic pyrophosphate (PP(i)) and of Y305F and D100E trichodiene synthases in ternary complexes with PP(i) and aza analogues of the bisabolyl carbocation intermediate are reported. The Y305F substitution in the basic D(302)RRYR motif does not cause large changes in the overall structure in comparison with the wild-type enzyme in either the uncomplexed enzyme or its complex with PP(i). However, the loss of the Y305F-PP(i) hydrogen bond appears to be compensated by a very slight shift in the position of the side chain of R304. The putative bisabolyl carbocation mimic, R-azabisabolene, binds in a conformation and orientation that does not appear to mimic that of the actual carbocation intermediate, suggesting that the avid inhibition by R- and S-azabisabolenes arises more from favorable electrostatic interactions with PP(i) rather than any special resemblance to a reaction intermediate. Greater enclosed active-site volumes result from the Y305F and D100E mutations that appear to confer greater variability in ligand-binding conformations and orientations, which results in the formation of aberrant cyclization products. Because the binding conformations and orientations of R-azabisabolene to Y305F and D100E trichodiene synthases do not correspond to binding conformations required for product formation and because the binding conformations and orientations of diverse substrate and carbocation analogues to other cyclases such as 5-epi-aristolochene synthase and bornyl diphosphate synthase generally do not correspond to catalytically productive complexes, we conclude that the formation of transient carbocation intermediates in terpene cyclization reactions is generally under kinetic rather than thermodynamic control.     

Synthesis,optimization, and characterization of biogenic manganese oxide (BioMnOx) by bacterial isolates from mangrove soils with sorbents property towards different toxic metals

BioMetals - Manganese oxidizing bacteria, Bacillus mycoides and Bacillus subtilis were isolated from mangrove soils and optimized for the removal of Mn(II) with simultaneous production of biogenic...