Kinetics of deactivation for thermostable DNA polymerase enzymes

Summary The kinetics of thermal deactivation for thermostable DNA polymerase enzymes were investigated by using the experimental data published elsewhere (Nielson et al. 1996. Strategies. 9, 7–8). The order of deactivation (a) and the deactivation rate constants (k _d) were determined for different Taq DNA polymerase enzymes and were found to be of first order.     

Potentiation of bleomycin-induced chromosome aberrations by the radioprotector reduced glutathione

In this study we investigated whether the radioprotector reduced glutathione (GSH) can reduce the frequency of chromosome aberrations induced by the radiomimetic antitumour drug bleomycin (BLM) in muntjac lymphocytes in vitro. Our results demonstrate that, instead of yielding any protection, the presence of GSH potentiates the clastogenic action of BLM. A significant enhancement in the frequency of rearrangements and deletions was observed and the number of aberrations per metaphase was also enhanced. We suggest that this potentiation may be due to GSH acting as a reducing agent in reactivating oxidised BLM.     

Detection of Two Membrane Polypeptides Induced by Abscisic Acid and Cold Acclimation: Possible Role in Freezing Tolerance

Membrane proteins labeled in vivo from cold-acclimated and ABA-treatedalfalfa seedlings of two cultivars differing in cold-tolerancehave been compared by SDS polyacrylamide gel electrophoresisand fluorography. Results thus obtained indicate that severalqualitative changes occur in the membrane protein-profile specificallyin response to cold acclimation or ABA treatment. While somepolypeptides disappear from the non-acclimated protein patterns,others specifically appear in response to acclimation. Separationby two-dimensional gel electrophoresis and fluorography hasconfirmed the above and has enabled us to detect two proteinsof Mr 42 kDa and 120 kDa that are induced by both acclimationand ABA treatment in the freezing tolerant cultivar. (Received November 30, 1987; Accepted February 22, 1988)     

Characterization of a glycoprotein isolated from a continuous tumor-cell line of human lung carcinoma

A glycoprotein with a molecular weight of 62 000 has been isolated from a tumor-cell line, A549, and purified to homogeneity by gel chromatography. The glycoprotein contained sialic acid, galactose, mannose, N-acetylglucosamine and a relatively high amount of glutamic acid and proline. The data indicated that the overall composition of this glycoprotein was different from that of the glycoprotein of Mr 62 000 isolated from lung lavage of patients with alveolar proteinosis. The glycoprotein did not react with the antiserum raised against glycoprotein of Mr 62 000 isolated from lung lavage of patients with alveolar proteinosis.     

Trichophyton simii infection in man and animals

Nine human infections due toT. simii comprising of tinea corporis (6), tinea cruris (2) and tinea capitis (1) have been reported. Human cases were having lesions typically of zoophilic contracted infections. Lesions in dogs were on nose and upper lip and were circular. All the strains showed typical and identical macro and microscopie morphology. Three isolates studied by Stockdale were negative (2) and positive (1) strains. One studied here was negative. Possible epidemiology is discussed.     

Passage number of cancer cell lines: Importance,intricacies, and way-forward

Cancer cell lines play a crucial role as invaluable models in cancer research, facilitating the examination of cancer progression as well as the advancement of diagnostics and treatments. While they may not perfectly replicate the original tumor, they generally exhibit similar characteristics. Low-passage cancer cell lines are generally preferred due to their closer resemblance to the original tumor, as long-term culturing can alter the genetic and molecular profiles of a cell line thereby highlighting the importance of monitoring the passage number (PN). Variations in proliferation, migration, gene expression, and drug sensitivity can be linked to PN differences. PN can also influence DNA methylation levels, metabolic profiles, and the expression of genes/or proteins in cancer cell lines. When conducting research on cancer cell lines, it is crucial for researchers to carefully select the appropriate PN to maintain consistency and reliability of results. Moreover, to ensure dependability and replicability, scientists ought to actively track the growth, migration, and gene/or protein profiles of cancer cell lines at specific PNs. This approach enables the identification of the most suitable range of PNs for experiments, guaranteeing consistent and precise results. Additionally, such efforts serve to minimize disparities and uphold the integrity of research. In this review, we have laid out recommendations for laboratories to overcome these PN discrepancies when working with cancer cell lines.     

Aquo-pentamine Co(III) complexes as models for carbonic anhydrase

The hydrolysis of 4-nitrophenyl acetate by metal complexes Co(en)2(imH)H2O3+, Co(en)2(bzmH)H2O3+, and Co(en)2(imCH3)H2O3+ (imH = imidazole, bzmH = benzimodazole, imCH3 = methyl imidazole) has been investigated in the pH range 5.4-8.9. The small difference in nucleophilic reactivity in the pH range 5.4-6.7 is assumed to be due to hydrogen bonding abilities of the imidazole and substituted imidazole ligands and small pKa differences (k2(imH) = 2.2 X 10(-2) M-1 sec-1, k2(bzmH) = 5.68 X 10(-2) M-1 sec-1, k2(imCH3) = 1.35 X 10(-2) M-1 sec-1, 40 degrees C, 1 = 0.3 NaClO4, pKa(imH) = 6.2, pKa(imCH3) = 6.2 and pKa(bzmH) = 5.9). In the pH range 7.8-8.9, the differences in nucleophilic reactivity (k3(imH) = 85.5 X 10(-2) M-1 sec-1, k3(bzmH) = 33.4 X 10(-2) M-1 sec-1, 40 degrees C, I = 0.3 NaClO4) are reconciled with a significant steric factor outweighing the acidity of the benzimidazole complex. In the pH region 6.7-7.7, the deviation from linearity is presumably due to both hydroxo and imido ligands functioning as nucleophiles, the latter being about 40 times stronger than the former.     

Human T cell responses to purified pollen allergens of the grass, Lolium perenne. Analysis of relationship between structural homology and T cell recognition.

The in vitro proliferative response to purified allergens of the grass, Lolium perenne pollens was studied using PBMC from individuals allergic to grass pollens and Ag-specific T cell lines and T cell clones derived from them. The PBMC from all 10 subjects studied showed a strong response to Lol p I and most of them (8 of 10) also responded to Lol p III. Although Lol p II induced a moderate response in 4 of 10 individuals, it did not induce any response in others at all the Ag concentrations tested. However, one of the subjects (JH) responded to, besides Lol p I, both Lol p II and Lol p III equally well. Analysis of Ag-specific T cell lines and clones derived from three individuals showed varied pattern of reactivity to the Lol p allergens. Some of the Lol p III-specific T cell lines and clones were also stimulated by Lol p I and similarly, some of the Lol p I-specific T cell clones (derived from four other subjects) were stimulated by Lol p III; thus showing a two-way cross-reactivity between those T cells. In both cases, the cross-reactivity to Lol p II, when observed, was lower than that seen with Lol p I and Lol p III. Comparison of amino acid sequences of the three Lol p proteins revealed a significant level of structural similarity among them, including several segments of identical sequences. Although one of the synthetic peptides of Lol p III sharing appreciable sequence homology with other proteins stimulated PBMC from two subjects, three other peptides did not. Nevertheless, these studies indicated the possible existence of cross-reactive T cell epitope(s) among the grass pollen allergens. Based on these results, the relationship between amino acid sequence homology among the Lol p proteins and their recognition by T cells is discussed.     

A new species of the genus Cirrhimuraena (Anguilliformes: Ophichthidae) from the Bay of Bengal,India

A new species of the genus Cirrhimuraena (Anguilliformes: Ophichthidae), Cirrhimuraena indica sp. nov., is described based on eight specimens collected from the Paradip (Odisha) and Petuaghat harbours (West Bengal) along the Bay of Bengal. The species is distinct in having the upper jaw fringed with 16–17 cirri before posterior nostril and 4–5 in between the anterior and posterior nostrils on the side; dorsal fin originates above the level of gill opening, predorsal length is 9.3–10.9 in total length; the head is relatively large, the length is 9.3–9.8 in total length; no infraorbital pores are observed between the nostrils; teeth are numerous, small, conical and in bands on each jaw; pores are present before the gill opening 10–11 and before anus 47–48; pectoral-fin length is 2.4–2.8 in head length; predorsal vertebrae are 8–10, pre-anal vertebrae 43–47 and total vertebrae 164–169. In the maximum likelihood tree analysis for COI gene, the new species belongs to the same clade as the other congener of Cirrhimuraena chinensis and is separated from the species morphologically and genetically.