Biomedical subjects

Neetu Dahiya

Publications and source records attributed to Neetu Dahiya.

5 recordsLinked to original sources

PubMed2006

Immunogenicity study of recombinant human sperm-associated antigen 9 in bonnet macaque (Macaca radiata).

BACKGROUND: The human sperm-associated antigen 9 (hSPAG9) is of special interest attributing to the findings indicating that SPAG9 is an acrosomal molecule. SPAG9 is not only restricted to acrosomal compartment but also persists in equatorial segment post-acrosome reaction, which is a key location in sperm-egg interaction. METHODS AND RESULTS: Immunogenicity studies in macaques were carried out with recombinant hSPAG9 (rhSPAG9) adsorbed on alum, which resulted in high titres of anti-rhSPAG9 antibodies as determined by enzyme-linked immunosorbent assay (ELISA). Immunoblotting analysis employing anti-rhSPAG9 antibodies generated in monkeys indicated that antibodies specifically reacted with native SPAG9 from macaque and human sperm and rhSPAG9 protein. Furthermore, indirect immunofluorescence experiments demonstrated SPAG9 localization in the acrosomal compartment of macaque and human sperm. In addition, monkey antibodies against rhSPAG9 significantly inhibited the human spermatozoa adherence or penetration in zona-free hamster oocytes. CONCLUSION: These results demonstrate that rhSPAG9 adsorbed on alum is highly immunogenic in subhuman primate model and therefore represents a suitable sperm-based vaccine immunogen for fertility trials in macaque.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Biotechnological aspects of chitinolytic enzymes: a review.

Chitin and chitinases (EC 3.2.1.14) have an immense potential. Chitinolytic enzymes have wide-ranging applications such as preparation of pharmaceutically important chitooligosaccharides and N-acetyl D-glucosamine, preparation of single-cell protein, isolation of protoplasts from fungi and yeast, control of pathogenic fungi, treatment of chitinous waste, and control of malaria transmission. In this review, we discuss the occurrence and structure of chitin, the types and sources of chitinases, their mode of action, chitinase production, as well as molecular cloning and protein engineering of chitinases and their biotechnological applications.

Acetylglucosamine↗

PubMed2005

Small interference RNA-mediated knockdown of sperm associated antigen 9 having structural homology with c-Jun N-terminal kinase-interacting protein.

Recently, we reported a novel testis-specific sperm associated antigen 9 (SPAG9) protein, a new member of the JNK-interacting protein family, having a functional role in sperm-egg fusion [N. Jagadish, R. Rana, R. Selvi, D. Mishra, M. Garg, S. Yadav, J.C. Herr, K. Okumura, A. Hasegawa, K. Koyama, A. Suri, Biochem. J. 389 (2005) 73-82]. NCBI Blast searches revealed SPAG9 nucleotide sequence similarities with ESTs of various cancerous tissues. In the present study, we compared the efficiency of two independent SPAG9 specific small interfering RNA (siRNA) constructs, BS/U6/spag9 and BS/U6/spag9-I, to ablate the SPAG9 expression in mammalian cells. A positive correlation between the ratio of target gene versus siRNA and the suppression of SPAG9 expression was observed. Further, the cotransfection of BS/U6/spag9 with pcDNA-SPAG9 and pFlag-CMV2-JNK-3 resulted in specific suppression of SPAG9 without affecting JNK-3 expression. The present investigation will eventually extend the application of SPAG9 siRNA in in vivo targeting experiments that aim to define the SPAG9 functional genomics in tumor and reproductive biology.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Chitinase production in solid-state fermentation by Enterobacter sp. NRG4 using statistical experimental design.

The optimization of nutrient levels for chitinase production by Enterobacter sp. NRG4 in solid-state fermentation conditions (SSF) was carried out using response surface methodology (RSM) based on central composite design (CCD). The design was employed by selecting wheat bran-to-flake chitin ratio, moisture level, inoculum size, and incubation time as model factors. The results of first-order factorial design experiments showed that all four independent variables have significant effects on chitinase production. The optimum concentrations for chitinase production were wheat bran-to-flake chitin ratio, 1; moisture level, 80%; inoculum size, 2.6 mL; and incubation time, 168 h. Using this statistical optimization method, chitinase production was found to increase from 616 U . g(-1) dry weight of solid substrate to 1475 U . g(-1) dry weight of solid substrate.

Chitin↗

PubMed2005

Properties of a thermostable extracellular lipase from Bacillus megaterium AKG-1.

An extracellular lipase isolated from Bacillus megaterium AKG-1 had an optimum activity at 55 degrees C/pH 7.0. It retained 100% activity at 50 degrees C for 30 min with a half life of 30 min at 70 degrees C. A 20-70% increase in lipase activity was observed in presence of acetone (20% v/v), DMSO (20% v/v) and isopropanol (10% v/v). The enzyme activity was 92, 98 and 107% after 24 h, on treatment with 10% (v/v) acetone, benzene and isopropanol respectively. Deoxycholic acid, sodium deoxycholate, lithocholic acid, rhamnolipid, Brij 52 and cholic acid stimulated the lipase activity by 76, 36, 24, 24, 23.6 and 13%, respectively. Addition of reducing agents like sodium sulphite, sodium metabisulphite and L-cysteine-HCl, at 10 mM concentration stimulated lipase activity by 127, 146 and 150% respectively. The lipase appeared to show enantioselectivity in hydrolyzing racemic 3-acetoxy-beta-lactam as it hydrolyzed only the (+) enantiomer.

Bacillus megaterium↗