Defying the Stereotype: Non-Canonical Roles of the Peptide Hormones Guanylin and Uroguanylin

The peptide hormones uroguanylin and guanylin have been traditionally thought to be mediators of fluid–ion homeostasis in the vertebrate intestine. They serve as ligands for receptor guanylyl cyclase C (GC-C), and both receptor and ligands are expressed predominantly in the intestine. Ligand binding to GC-C results in increased cyclic GMP production in the cell which governs downstream signaling. In the last decade, a significant amount of research has unraveled novel functions for this class of peptide hormones, in addition to their action as intestinal secretagogues. An additional receptor for uroguanylin, receptor guanylyl cyclase D, has also been identified. Thus, unconventional roles of these peptides in regulating renal filtration, olfaction, reproduction, and cell proliferation have begun to be elucidated in detail. These varied effects suggest that these peptide hormones act in an autocrine, paracrine as well as endocrine manner to regulate diverse cellular processes

A non-surgical approach for male germ cell mediated gene transmission through transgenesis

Microinjection of foreign DNA in male pronucleus by in-vitro embryo manipulation is difficult but remains the method of choice for generating transgenic animals. Other procedures, including retroviral and embryonic stem cell mediated transgenesis are equally complicated and have limitations. Although our previously reported technique of testicular transgenesis circumvented several limitations, it involved many steps, including surgery and hemicastration, which carried risk of infection and impotency. We improved this technique further, into a two step non-surgical electroporation procedure, for making transgenic mice. In this approach, transgene was delivered inside both testes by injection and modified parameters of electroporation were used for in-vivo gene integration in germ cells. Using variety of constructs, germ cell integration of the gene and its transmission in progeny was confirmed by PCR, slot blot and immunohistochemical analysis. This improved technique is efficient, requires substantially less time and can be easily adopted by various biomedical researchers

The Form of Even Perfect Numbers-- an Independent Derivation

Here, I present my own, independently pursued derivation of the general form of even perfect numbers

On the Similarity of the Psyches of Two Apparently Unrelated Peoples as Evidenced from a Similarity in Their Languages

I have noted a few instances of similarity between the languages Bengali and English and I have concluded from this that there must be a similarity in the psyches of the people who speak Bengali and those who speak English, who are apparently unrelated. I feel that this idea can be extrapolated to suggest that there is a similarity in the psyches of all the people of the world

A New Way of Representing and Storing Information

I have proposed here a new scheme of representing information which is that any physical quantity with a specific identity can be considered to uniquely represent a distinct piece of information (a piece of information different from the one that the physical quantity itself conveys which is that of its identity). Doing so is expected to bring advantage to storing information

A Study on Electrostatics and Its Hazards

This project presents a study on electrostatics and its hazards

Suggesting a Reliable Method of Calculating Charge Collection Efficiency in Charge-transfer Measurement for Brush Discharges

Induced charge errors lead to underestimation of transferred charge in brush discharges when the measurement is done using fast-response unshielded probes. The discrepancy observed between the values of charge-collection efficiency for different charge-transfer thresholds obtained theoretically by Walmsley [2] and those obtained experimentally by Chowdhury et al [3] necessitates figuring out ways to improve the mathematical model used by Walmsley. A close perusal of the said work by Walmsley [2] has pointed out an error therein– in the use of the equation reff = KD. I propose here a way to get rid of this error, and in doing so, I propose a method of calculating the charge-collection efficiency in charge-transfer measurement for brush discharges more reliable than that used by Walmsley [2]

Receptor guanylyl cyclase C (GC-C): regulation and signal transduction

Receptor guanylyl cyclase C (GC-C) is the target for the gastrointestinal hormones, guanylin, and uroguanylin as well as the bacterial heat-stable enterotoxins. The major site of expression of GC-C is in the gastrointestinal tract, although this receptor and its ligands play a role in ion secretion in other tissues as well. GC-C shares the domain organization seen in other members of the family of receptor guanylyl cyclases, though subtle differences highlight some of the unique features of GC-C. Gene knock outs in mice for GC-C or its ligands do not lead to embryonic lethality, but modulate responses of these mice to stable toxin peptides, dietary intake of salts, and development and differentiation of intestinal cells. It is clear that there is much to learn in future about the role of this evolutionarily conserved receptor, and its properties in intestinal and extra-intestinal tissues