Microenvironmental variability and species diversity in treefall gaps in a sub-tropical broadleaved forest

Microenvironmental variability and species diversity in gaps and forest understorey were studied to assess the role of treefall gaps in maintaining composition and patchy distribution in a broad-leaved sub-tropical climax forest, Mawphlang, Meghalaya, India. Photon flux density was higher in gaps than in the surrounding understorey. Relative humidity was low and the litter layer was relatively thin in gaps throughout the year. Soil moisture and photon flux density in the gaps significantly varied between seasons and gaps of different sizes. Relative humidity significantly varied between seasons but difference among gaps was insignificant. Among-gap and among-season variations in soil and air temperature were insignificant.The number of tree species in the gaps was positively correlated with gap area, and tree species abundance showed higher equitability in larger than in smaller gaps. In gaps, -diversity was highest for herbs and lowest for shrubs. -diversity was highest for shrubs and lowest for tree seedlings. -diversity of tree seedlings was higher in the gaps than in the forest understorey. Conversely, -diversity was higher in the understorey than in the gaps. Low species similarity for tree seedlings among the gaps could be an effect of patchy distribution of parent tree species in the forest. Thus a significant change in light and moisture regimes along the gap size gradient played an important role in influencing the composition and abundance of shade tolerant and intolerant tree species in gaps on one hand, and affected the overall species diversity of the forest, on the other.     

Prokaryotic Expression of Ovis aries Conglutinin Encoding Neck and Carbohydrate Recognition Domain and its Functional Characterization

Conglutinin, a soluble pattern recognition receptor of innate immune system in bovines is known for its potential defensive activity against microorganisms either by direct agglutination in the presence of calcium or by acting as opsonin. In the present study, sheep (Ovis aries) conglutinin encoding neck and carbohydrate recognition domain (rSCGN) was expressed in the E coli BL21 expression host. The recombinant conglutinin revealed molecular weight of 27 kDa in SDS PAGE and also in western blotting using antibuffalo conglutinin polyclonal serum. The protein was characterized further for its functional activity in various assays. In ELISA based sugar and LPS binding assay, the rSCGN revealed its high binding activity toward N-acetyl glucosamine and E. coli LPS in the presence and the absence of calcium ions, respectively. Hemagglutination of chicken red blood cells caused by Newcastle disease virus was not inhibited in the presence of rSCGN as it lacked complete collagenous region present in the native protein. In virus neutralization test, the recombinant protein was found to reduce multiplication of bovine herpes virus-1 propagated in MDBK cells. This prokaryotically expressed 27 kDa recombinant sheep conglutinin can serve as antigen in future studies to develop sandwich ELISA for assessing the level of native conglutinin in sheep serum.     

Analysis of in vitro migration patterns of human spermatozoa by a petri dish-based horizontal column.

Spermatozoa are required to travel a considerable distance in vivo to meet the oocyte at the fertilization site. However, none of the existing in vitro tests critically evaluates migration of sperm to assess their potential of reaching the oocyte. On the other hand, an in vivo model is not suitable for this type of study because of ethical and technical constraints. In the present study we utilized a horizontal column technique to analyze sperm migration. Migratory characteristics of fresh, unwashed semen sperm and sperm undergoing various treatments were examined in vitro using a Petri dish-based horizontal fluid column. The procedure involved loading a sperm sample into the column and determining sperm concentration, motility, and viability at different column segments for different migration durations (6, 12, 24, 48, and 72 h). All sperm samples produced an exponential migration pattern in all durations of migration. Propagation along the column edge, tendency to exit from the column, and hiding in the blind pouches were some of the important characteristic features exhibited by the migratory sperm. Variations in migration patterns were documented among semen donors, between fresh and frozen semen, and between washed and unwashed sperm. Prolonged postejaculation time diminished migratory potential. The recovery of sperm in the column end was independent of seminal variables with the exception of oligozoospermia. These observations suggest that the Petri dish-based horizontal column is effective for analyzing sperm migration characteristics for prolonged periods. The potential of this migration assay in predicting the in vivo potential of spermatozoa to reach the fertilization site will be worth exploring.     

Antimicrobial activity of metal based nanoparticles against microbes associated with diseases in aquaculture

The emergence of diseases and mortalities in aquaculture and development of antibiotics resistance in aquatic microbes, has renewed a great interest towards alternative methods of prevention and control of diseases. Nanoparticles have enormous potential in controlling human and animal pathogens and have scope of application in aquaculture. The present investigation was carried out to find out suitable nanoparticles having antimicrobial effect against aquatic microbes. Different commercial as well as laboratory synthesized metal and metal oxide nanoparticles were screened for their antimicrobial activities against a wide range of bacterial and fungal agents including certain freshwater cyanobacteria. Among different nanoparticles, synthesized copper oxide (CuO), zinc oxide (ZnO), silver (Ag) and silver doped titanium dioxide (Ag–TiO₂) showed broad spectrum antibacterial activity. On the contrary, nanoparticles like Zn and ZnO showed antifungal activity against fungi like Penicillium and Mucor species. Since CuO, ZnO and Ag nanoparticles showed higher antimicrobial activity, they may be explored for aquaculture use.     

Transport of liposomal and albumin loaded curcumin to living cells: an absorption and fluorescence spectroscopic study

Curcumin, a lipid soluble antioxidant, exhibits solvent and medium sensitive absorption and fluorescence properties. Using such changes, the average binding constants of curcumin to phosphatidylcholine (PC) liposomes and human serum albumin (HSA) were estimated to be 2.5 x 10(4) M(-1) and 6.1 x 10(4) M(-1) respectively. From the studies on temperature dependent fluorescence anisotropy of liposomal curcumin and its fluorescence quenching by acrylamide and iodide, it was concluded that curcumin is located in the gel phase of the liposomes. Similarly from the studies on quenching of tryptophan fluorescence in HSA by curcumin, it was found to be in the same domain as that of tryptophan. Both liposomal and HSA vehicles were examined for the transfer of curcumin to spleen lymphocyte cells, EL4 lymphoma cell line and compared with aqueous DMSO vehicles. From these studies it was found that liposomal vehicle is capable of loading more curcumin in to cells than HSA or aqueous-DMSO, and lymphoma cells show preferential uptake of curcumin to lymphocytes. The fluorescence of curcumin in EL4 lymphoma cells was found to be significantly higher as compared to the lymphocytes. The present study demonstrates a simple and quantitative method of estimation of curcumin delivered to cells by different vehicles using absorption and fluorescence spectroscopy.     

Unusual complexation of Cu(I) by pyrimidine/pyridine-pyrazole derived ligands exploiting the molecular function of 2-mercapto-4,6-dimethylpyrimidine - Syntheses, crystal structures and electrochemistry

Reaction of 2 equiv. amount of copper(II) chloride dihydrate with 2 equiv. of methyl-5-methyl-1-(4,6-dimethyl-2-pyrimidyl)pyrazole-3-carboxylate (DpymPzC) in presence of 1 equiv. of 2-mercapto-4,6-dimethylpyrimidine (DpymtH) at pH ∼ 6 afforded the tricoordinated copper(I) complex [Cu(DpymPzC)Cl] (1). The same reaction with copper(II) perchlorate hexahydrate, as the metal salt under the same equivalent ratio at pH ∼ 6 formed the tetracoordinated copper(I) complex [Cu(DpymPzC)₂]ClO₄ (2). In both the cases, the role of DpymtH is nothing but only to reduce the copper(II) salt in situ finally forming the copper(I) complex. On the other hand, the direct reaction between the copper(I) thiocyanate and DpymPzC in 2:2 equiv. ratio produced a tricoordinated copper(I) complex [Cu(DpymPzC)SCN] (3). In a similar reaction of 2 equiv. amount of copper(II) chloride dihydrate with 2 equiv. amount of ethyl-5-methyl-1-(2-pyridyl)pyrazole-3-carboxylate (PyPzC) in presence of 1 equiv. of DpymtH at pH ∼ 6, an intense red coloured microcrystalline compound (4) was obtained. In contrast, 1 equiv. of PyPzC and 2 equiv. of DpymtH on reaction with 1 equiv. of copper(II) chloride dihydrate at pH ∼ 6 produced a novel tetranuclear mixed coordinated [Cu₄(DpymtH)₄Cl₄] complex (5). Here DpymtH plays dual role - a reducing agent for the copper(II) salt followed by a chelating ligand towards copper(I) so formed in situ. Among the above species, 1, 2 and 5 are crystallographically characterized. In 1, the central copper atom is in distorted triangular planar geometry with N₂Cl chromophore whereas in 2, the same is in distorted tetrahedral geometry with N₄ chromophore. Notably, the extent of distortion from the ideal geometry is more in 2. In 5, which is in chair conformation, out of four copper atoms, two being in S₂Cl chromophore are tricoordinated and the remaining two are tetracoordinated with NS₂Cl chromophore. The metal centers are bridged through DpymtH in its ‘thione’ form. Interestingly, the chelation (in part) results in formation of the highly stable four-membered two chelate rings around the two tetracoordinated copper atoms in 5. The two copper centers along the long arm of the chair are separated through a distance of 5.190 Å while those in the short arm are at a length of 3.629 Å. The electronic, IR spectra and electrochemistry of the complexes 1, 2 and 5 have also been investigated.     

In vitro plant regeneration from cotyledonary nodes of Withania somnifera (L.) Dunal and assessment of clonal fidelity using RAPD and ISSR markers

An efficient large-scale clonal propagation protocol has been described for Withania somnifera (L.) Dunal, a valuable medicinal plant, using cotyledonary nodes derived from axenic seedlings. Murashige and Skoog’s (Physiol Plant 15:473–497, 1962) (MS) medium supplemented with 1.0 mg l^?1 N ⁶-benzyladenine (BA) was found to be optimum for production of multiple shoots (100 % shoot proliferation frequency and 16.93 shoots per explant). Successive shoot cultures were established by repeatedly sub-culturing the original cotyledonary node on a fresh medium after each harvest of newly formed shoots. Multiple shoot proliferation was also achieved from nodal segments derived from in vitro raised shoots on MS medium augmented with 1.0 mg l^?1 BA. Regenerated shoots were best rooted (95.2 %, 38.7 roots per shoot) in half-strength MS medium supplemented with 1.0 mg l^?1 indole-3-butyric acid. The plantlets were successfully acclimated and established in soil. Random amplified polymorphic DNA and inter-simple sequence repeats analysis revealed a homogeneous amplification profile for all micropropagated plants analyzed validating the genetic fidelity of the in vitro regenerated plants.