Browsing by Author "Pinky Tripathi"

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Essence of keratin in lips and associated structures of a freshwater fish Puntius sophore in relation to its feeding ecology: Histochemistry and scanning electron microscope investigation
(Elsevier Ltd, 2010) Pinky Tripathi; Ajay Kumar Mittal
Morphological specializations in the lips and associated structures of Puntius sophore were examined by scanning electron microscopy and histochemically. The upper lip (UL), in P. sophore, is associated with the horny upper jaw sheath (HUJS) on its ventral side and with the rostral cap (RC) on its dorsal side through a thin and extensive fold of skin (FSUR). The lower lip (LL) is greatly enlarged, conspicuous and associated with horny lower jaw sheath (HLJS) on the dorsal side and ventrally continues with ventral head skin (VHS). On the lateral sides there is a thin and extensive fold of skin (FSLS) between the lower lip and VHS. In contrast to the mucogenic epithelia of the UL, LL, the RC and fold of skins, the horny jaw sheaths are keratinized in nature and surface epithelial cells are characteristically modified into unculi. The UL and the LL are equipped with epithelial cells (EC), mucous cells (MC) and taste buds (TB) while in addition to these cells club cells (CC) are also present in the RC. Keratin found in unculi is an extremely strong protein which is tough and insoluble, they form the hard but un-mineralized structures. Keratin in unculi could be regarded as an adaptation for browsing or scraping food materials from the substrate as the fish grubs about the bottom. The elaboration of mucus is considered to lubricate the surface and protect the epithelia from abrasions. Taste buds are associated to locate and select palatable food and to trigger a 'pick-up' reflex. © 2010 Elsevier Ltd.
Purification and biochemical characterisation of a novel protease streblin
(2011) Pinky Tripathi; Ritu Tomar; Medicherla V. Jagannadham
A serine protease, streblin, was purified 4.6-fold with 75% recovery from the latex of a plant, Streblus asper. This is the first report of identification and purification of a serine protease from the genus Streblus of the Moraceae family. Streblin, has a molecular mass of 64 kDa and the extinction coefficient (ε{lunate}2801%) is 5.29. Streblin is a basic protein with pI value of 9.2 that acts optimally at pH 9.0; such optimum activity at high pH has not been reported for most of the isolated plant serine proteases and the enzyme is stable over a wide range of pH (3.0-12.5). The enzyme is also thermostable, retaining complete activity at 15-85 °C and acts optimally at 65 °C. Furthermore, it is highly stable in the presence of various denaturants in which SDS resistance is the most striking property of the purified enzyme. Streblin strongly coagulated skimmed milk. Easy availability of the latex, simple purification procedures, high stability of streblin against pH, or autodigestion, and under various conditions make the enzyme a good system for exploring the biophysical chemistry of proteases. In addition to its high milk-clotting ability, it could be used in the cheese industry, as well as other food and biotechnological industries. © 2010 Elsevier Ltd.
Scanning electron microscopy of the operculum of Garra lamta (Hamilton) (Cyprinidae:Cypriniformes), an Indian hill stream fish
(2010) Swati Mittal; Usha Kumari; Pinky Tripathi; Ajay Kumar Mittal
The surface architecture of the epidermis on the outer surface of the operculum (OE) and the epithelium on the inner surface of the operculum (EISO) of Garra lamta was examined by scanning electron microscopy. The surface appeared smooth on the OE and wavy on the EISO. A wavy epithelium is considered to facilitate an increase in its stretchability, during the expansion of the branchial chamber. The OE and the EISO were covered by a mosaic pavement of epithelial cells with characteristic patterns of microridges and microbridges. Interspersed between the epithelial cells were mucous goblet cell pores, which were not significantly different in number in the OE and the EISO. Nevertheless, their surface area in the EISO was significantly higher than in the OE. This could be an adaptation to secrete higher amounts of mucus on the EISO for keeping the branchial chamber lining clean, avoiding clogging, the increased slipperiness reducing friction from water flow and increased efficiency in protecting against microbial attachments. Rounded bulges on the OE and the EISO were associated with mucous goblet cells. The absence of the taste buds in the EISO, in contrast to the OE, suggests that their function in the branchial chamber may not be of much significance in this fish. Breeding tubercles on the OE are believed to facilitate better contact between the male and female during breeding. © CSIRO 2010.
Stability and unfolding studies on alkaline denatured state (Ip) of pepsin
(2009) Monu Pande; N.K. Prasanna Kumari; Vikash Kumar Dubey; Pinky Tripathi; M.V. Jagannadham
Pepsin exists as alkaline denatured state (Ip) in pH range 8-10, where the N-terminal domain of the protein is mostly unfolded while the C-terminal domain is intact. The effects of fluorinated (TFE) and non-fluorinated (methanol) organic solvents on this partially unfolded state (Ip) of pepsin were investigated using various spectroscopic methods. Both, fluorinated (TFE) and non-fluorinated (methanol) organic solvents induce secondary structure (α-helix) after a critical concentration. The Ip state of pepsin unfolds in cooperative manner but the transition was found to be non-cooperative in the presence of 40% methanol or TFE. The differences in the unfolding of the protein in the presence and the absence of these organic solvents were interpreted. Our results indicate that unfolding transitions in Ip state are mostly dominated by unfolding of C-terminal domain because the N-terminal domain is largely unstructured in this state. The organic solvents (TFE and methanol) induce more secondary structure in N-terminal domain and make it another unfolding entity with different stability compare to C-terminal resulting into sequential unfolding of the domain. © 2009 Elsevier Ltd. All rights reserved.