Bejoy Narayan Mahavidyalaya

Abstract Background: The saccus vasculosus (SV) is a highly vascular organ situated on the ventral surface of the diencephalon, adjacent to the pituitary gland. It has a restricted distribution and occurs exclusively in certain gnathostome fishes. Objective: This study investigated the cellular organization of the SV in Clupisoma garua (Siluriformes: Ailiidae) using light and electron microscopes. Materials and Methods: Sexually mature specimens of C. garua were collected from the Bhagirathi–Hooghly River, a branch of the Ganges. The SV was examined using standard histological staining, as well as scanning electron microscopy and transmission electron microscopy, to characterize its detailed structural composition. Results: C. garua possessed a moderately developed SV characterized by numerous folds that form villus-like projections. The organ enclosed a large central cavity lined by a single stratified neuroepithelium composed of specialized coronet cells (CCs) and supporting cells, with CCs being more abundant. Both cell types rested on a basement membrane in close association with vascular elements. The CCs displayed basally located nuclei and distinct apical globular protrusions. The highly branched cavity, containing abundant secretory material, communicated with the third ventricle of the brain. Conclusion: The secretory and sensory roles of the SV were correlated with the functional significance of this organ in C. garua .

In this paper, we introduce the zero-divisor associate graph Gamma D(R) over a finite commutative ring R. It is a simple undirected graph whose vertex set consists of all non-zero elements of R, and two vertices a, b are adjacent if and only if there exist non-zero zero-divisors z1, z2 in R such that az1 = bz2. We determine the necessary and sufficient conditions for connectedness and completeness of Gamma D(R) for a unitary commutative ring R. The chromatic number of Gamma D(R) is also studied. Next, we characterize the rings R for which Gamma D(R) becomes a line graph of some graph. Finally, we give the complete list of graphs with at most 15 vertices which are realizable as Gamma D(R), characterizing the associated ring R in each case.

The saccus vasculosus is a specialized ependymal organ, found exclusively in osteichthyes and chondrichthyes, and is located on the ventral surface of the diencephalon, posterior to the hypophysis. The structural details of the of saccus vasculosus of Piaractus brachypomus (Characiformes: Serrasalmidae: Colossomatinae) were studied using both light and electron microscopy. The saccus vasculosus was a highly vascularized structure, consisting of numerous loculi lined with stratified epithelium that contained characteristic coronet cells and supporting cells. Both cell types rested on a basement membrane, beneath which lay the vascular elements. The coronet cells exhibited distinct basal and apical regions. The spherical nucleus was situated in the basal part, whereas the apical cytoplasm formed a globular extension that protruded into the luminal cavity. The supporting cells were fewer in number and considerably smaller than the coronet cells, with nuclei positioned at the basal region. Unlike the coronet cells, they lacked apical protrusions. Abundant secretory material was observed within the lumen of the loculi, confirming the secretory nature of the saccus vasculosus. In addition, the contact of coronet cells with nerve terminals suggested a sensory function. The various cell types of the saccus vasculosus in P. brachypomus were correlated with their possible physiological roles and functional significance.

The mini review focuses on the work carried out in our laboratory over the last two and a half decades to unravel various facets of photoinduced processes, viz. photoinduced electron transfer (PET), excited state proton transfer, energy transfer etc., using fluorescence spectroscopy and imaging. We have demonstrated that PET is manifested by formation of exciplex and that its parent spin state is authenticated by observing steady-state fluorescence in presence of magnetic field, which is quite a non-conventional set -up. It is observed that dielectric constant of the medium governs the magnetic field effect. We have synthesized and explored fluorophores which act as sensors for hydrogen bonds and protic media. Our group has studied the protonation equilibrium of Acridine, which is a good fluorophore in various confined media and observed the perturbation of this equilibrium in presence of DNA bases using steady-state and time-resolved fluorescence techniques. Excimer formation of 9-Aminoacridine Hydrochloride Hydrate (9AA), another strong fluorophore, has been investigated in several solvent matrices and photoinduced interactions of 9AA with amines and viologens are studied. Further, we have utilized fluorescence upconversion technique to segregate direct and diffusion-controlled electron transfer within picosecondfemtosecond time domain. Then attempts have been made to study DNA-ligand and protein-ligand interactions comprehensively, utilizing different techniques of fluorescence spectroscopy. Furthermore, we have synthesized fluorescent carbon dots and have made an endeavor to find their fruitful biological significance. We have also synthesized riboflavin (Rf)-gold nano-assemblies (RfS@AuNPs) by covalently attaching thiolated Rf to gold nanoparticles (AuNPs) and have observed that these RfS@AuNPs accumulate in the nucleus of cancer cells, leading to plasma membrane blebbing and binucleated apoptotic bodies, consistent with activation of apoptosis. Finally, some very recent examples as well as the future prospect of fluorescence spectroscopy have been discussed.

The review focuses on photoinduced electron transfer (PET) reactions between small molecules and various kinds of chemical and biological systems using a weak external magnetic field (MF). Laser flash photolysis is a competent tool to characterize the intermediates which are formed due to PET. A weak MF, very close to the hyperfine interaction of the system, has the potential to inhibit or enhance reaction channels for singlet and triplet states, which eventually effects the product distribution. At first, well-documented examples of PET involving small molecules like derivatives of phenazines, carbazoles and acridines with classical electron donors in varying homogeneous and heterogeneous media have been discussed and the influence of a weak MF on the dynamics of PET is highlighted. Secondly, utilization of magnetic field effect (MFE) to probe PET in protein pockets has been described. Thirdly, an extensive discussion on PET involving nucleobases, nucleosides, nucleotides and nucleic acids and subsequent MFE on such reactions has been reported. Next, MFE has been exploited to study PET involving nanomaterials. Finally, some very recent studies of MFE have been discussed. Thus, this review is an attempt to unravel various aspects of PET in a large number of systems of varying dimensions by means of several facets MFE like B1/2 parameter, its capability to authenticate the initial spin state and distance dependence property.