Impact of climate change on Indian forests: a dynamic vegetation modeling approach

We make an assessment of the impact of projected climate change on forest ecosystems in India. This assessment is based on climate projections of the Regional Climate Model of the Hadley Centre (HadRM3) and the dynamic global vegetation model IBIS for A2 and B2 scenarios. According to the model projections, 39% of forest grids are likely to undergo vegetation type change under the A2 scenario and 34% under the B2 scenario by the end of this century. However, in many forest dominant states such as Chattisgarh, Karnataka and Andhra Pradesh up to 73%, 67% and 62% of forested grids are projected to undergo change. Net Primary Productivity (NPP) is projected to increase by 68.8% and 51.2% under the A2 and B2 scenarios, respectively, and soil organic carbon (SOC) by 37.5% for A2 and 30.2% for B2 scenario. Based on the dynamic global vegetation modeling, we present a forest vulnerability index for India which is based on the observed datasets of forest density, forest biodiversity as well as model predicted vegetation type shift estimates for forested grids. The vulnerability index suggests that upper Himalayas, northern and central parts of Western Ghats and parts of central India are most vulnerable to projected impacts of climate change, while Northeastern forests are more resilient. Thus our study points to the need for developing and implementing adaptation strategies to reduce vulnerability of forests to projected climate change.

Breast cancer and human papillomavirus infection: No evidence of HPV etiology of breast cancer in Indian women

Background: Two clinically relevant high-risk HPV (HR-HPV) types 16 and 18 are etiologically associated with the development of cervical carcinoma and are also reported to be present in many other carcinomas in extra-genital organ sites. Presence of HPV has been reported in breast carcinoma which is the second most common cancer in India and is showing a fast rising trend in urban population. The two early genes E6 and E7 of HPV type 16 have been shown to immortalize breast epithelial cells in vitro, but the role of HPV infection in breast carcinogenesis is highly controversial. Present study has therefore been undertaken to analyze the prevalence of HPV infection in both breast cancer tissues and blood samples from a large number of Indian women with breast cancer from different geographic regions. Methods: The presence of all mucosal HPVs and the most common high-risk HPV types 16 and 18 DNA was detected by two different PCR methods - (i) conventional PCR assays using consensus primers (MY09/11, or GP5 +/GP6+) or HPV16 E6/E7 primers and (ii) highly sensitive Real-Time PCR. A total of 228 biopsies and corresponding 142 blood samples collected prospectively from 252 patients from four different regions of India with significant socio-cultural, ethnic and demographic variations were tested. Results: All biopsies and blood samples of breast cancer patients tested by PCR methods did not show positivity for HPV DNA sequences in conventional PCRs either by MY09/11 or by GP5+/GP6+/HPV16 E6/E7 primers. Further testing of these samples by real time PCR also failed to detect HPV DNA sequences. Conclusions: Lack of detection of HPV DNA either in the tumor or in the blood DNA of breast cancer patients by both conventional and real time PCR does not support a role of genital HPV in the pathogenesis of breast cancer in Indian women.

Effect of blocking oestrogen synthesis with a new generation aromatase inhibitor CGS 16949A on follicular maturation induced by pregnant mare serum gonadotrophin in the immature rat

While the endocrine role of oestrogen is well established, its function in follicular maturation as an autocrine or paracrine regulator is less well understood. This study was designed to delineate the requirement of oestrogen for follicular development in immature rats. Exogenous gonadotrophin (25 IU pregnant mare serum gonadotrophin (PMSG) per rat) was administered to 21- to 23-day old female rats to induce follicular growth and development. In the experimental animals, synthesis of oestrogen was blocked by implanting an Alzet pump containing the aromatase inhibitor (AI) CGS 16949A (fadrozole hydrochloride; 50 mu g/rat per day). The treatment resulted in blockade of the PMSG induced increase in both serum and intrafollicular oestrogen (>95%), thus leading to an inhibition in uterine weight increment. Compared with the controls, ovarian weight increased markedly in both the PMSG (295%)- and PMSG+AI (216%)-primed animals. There was no significant difference in either the proliferative capabilities of the ovarian granulosa cells or their responsiveness to human chorionic gonadotrophin (hCG; 200 pg/ml) and ovine FSH (20 ng/ml) between the PMSG- and PMSG+AI-treated groups. Histological examination of the ovary, however, indicated a decrease in the number of healthy antral follicles in the Al-treated group compared with the PMSG-primed animals but both the groups showed a percentage increase over the controls (PMSG, 225; PMSG+AI, 158). The responsiveness of the animals to an ovulatory dose of hCG was drastically reduced (>80% inhibition of ovulation) in the oestrogen-deprived animals; this could be overriden by exogenous administration of oestrogen. In conclusion, although blocking oestrogen synthesis in the PMSG-primed rat does not seem to alter the functional properties of the isolated granulosa cells in vitro there appears to be an effect on the number of follicles which complete maturation and are able to ovulate in vivo.

Effect of mutations on the p53 IRES RNA structure Implications for de-regulation of the synthesis of p53 isoforms

Earlier we have demonstrated the presence of internal ribosome entry site (IRES) within tumor suppressor p53 mRNA. Here we have mapped the putative secondary structure of p53-IRES RNA using information from chemical probing and nuclease mapping experiments. Additionally, the secondary structure of the IRES element of the wild-type RNA was compared with cancer-derived silent mutant p53 RNAs. These mutations might result in the conformational alterations of p53-IRES RNAs. The results also indicate decreased IRES activities of the mutants as compared to wild-type RNA. Further, it was observed that some of the cytoplasmic trans-acting factors, critical for enhancing IRES function, were unable to bind mutant RNAs as efficiently as to wild-type. Our results suggest that hnRNP C1/C2 binds to p53-IRES and siRNA mediated partial silencing of hnRNP C1/C2 showed appreciable decrease in IRES function and consequent decrease in the level of the corresponding p53 isoform. Interestingly mutant p53 IRES showed lesser binding with hnRNP C1/C2 protein. Finally, upon doxorubicin treatment, the mutant RNAs were unable to show enhanced p53 synthesis to similar extent compared to wild type. Taken together, these observations suggest that mutations occurring in the p53 IRES might have profound implications for de-regulation of its expression and activity.

Observation of asymmetry in U�I characteristics of contacts of the form metal 1�superconductor�metal 2

During experiments carried out to find out a suitable contact metal for electronic components based on high-T(c) superconductor films (Y-Ba-Cu-O), it is observed that there is an asymmetry in the U-I characteristics if the two contacts are made of different metals. The asymmetry is more pronounced if one of the contact metals is aluminium. The asymmetry is lowest if one of the contact metals is silver and the other gold.

Photolabeling of the EcoP15 DNA methyltransferase with S-adenosyl-l-methionine

Radioactivity from S-adenosyl-L-[methyl-H-3] methionine ([methyl-H-3]AdoMet) was bound to the EcoP15 DNA methyltransferase (M.EcoP15) following short-wave ultraviolet (UV) irradiation. The labeled protein was subjected to polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE), and detected by fluorography and autoradiography. Labeling was found to be dependent on the concentration of AdoMet and time of UV irradiation. The photolabeling by [methyl-H-3]AdoMet was specific and blocked by S-adenosyl-L-homocysteine (AdoHcy) and sinefungin which are known to function as competitive inhibitors. Limited digestion of the M EcoP15-AdoMet adduct by Staphylococcus aureus protease V8 generated three peptides of approx. 50, 32 and 30 kDa; Interestingly, only the 30-kDa peptide fragment contained radioactivity, as detected by SDS-PAGE, followed by fluorography and autoradiography. Further, sequencing of a few amino acids at the N-terminus of these peptides showed that the 30-kDa fragment was the N-terminal portion of M.EcoP15, These results suggest that photolabeling is at the AdoMet-binding site and that the N-terminal half of M.EcoP15 may be involved in substrate binding.

Primary structure of sesbania mosaic virus coat protein: its implications to the assembly and architecture of the virus

Sesbania mosaic virus (SMV) is a plant virus that infects Sesbania grandiflora plants in Andhra Pradesh, India. The amino acid sequence of the coat protein of SMV was determined using purified peptides generated by cleavage with trypsin, chymotrypsin, V8 protease and clostripain. The 230 residues so far determined were compared to the corresponding residues of southern bean mosaic virus (SBMV), the type member of sobemoviruses. The overall identity between the sequences is 61.7%. The amino terminal 64 residues, which constitute an independent domain (R-domain) known to interact with RNA, are conserved to a lower extent (52.5%). Comparison of the positively charged residues in this domain suggests that the RNA-protein interactions are considerably weaker in SMV. The residues that constitute the major domain of the coat protein, the surface domain (S-domain, residues 65-260), are better conserved (66.5%). The positively charged residues of this domain that face the nucleic acid are well conserved. The longest conserved stretch of residues (131-142) corresponds to the loop involved in intersubunit interactions between subunits related by the quasi 3-fold symmetry. A unique cation binding site located on the quasi 3-fold axis contributes to the stability of SMV. These differences are reflected in the increased stability of the SMV coat protein and its ability to be reconstituted with RNA at pH 7.5. A major epitope was identified using monoclonal antibodies to SMV in the segment 201-223 which contains an exposed helix in the capsid structure. This region is highly conserved between SMV and SBMV (70%) suggesting that it could represent the site of an important function such as vector recognition.

Soft-chemical synthesis of new non-linear optical materials, K0.5M0.5Ti0.5OPO4(M = Nb, Ta),related to KTiOPO4

Soft-chemical oxidation of KTiOPO4-like KM(0.5)(V)Ti(0.5)(III)OPO(4) (M = Nb, Ta) using chlorine in CHCl3 is accompanied by partial deintercalation of potassium, yielding K(0.5)MV(0.5)Ti(0.5)(IV)OPO(4) compounds which are new non-linear optical materials that exhibit efficient second-harmonic generation of 1064 nm radiation, as does KTiOPO4.

Sintering of beta titanium: Role of dislocation pipe diffusion

Sintering of titanium in its high temperature beta phase was studied by isothermal dilatometry. The sintering shrinkage y did not follow the normal time exponent type of behaviour, instead being described by the equation y = Kt(m)/[1-(A+Bt)(2)], where m = 1.93 +/- 0.07, with an activation energy of 62-90 kJ mol(-1). A detailed analysis of these results, based on the 'anomalous' diffusion behaviour reported for beta titanium, is carried out. It is shown that the generation of a high density of dislocations during the alpha --> beta phase transformation, coupled with sluggish recovery at the sintering necks, enables sintering mass transport by pipe diffusion through dislocation cores from sources of matter within the particles to become dominant.

Theoretical Analysis of the Electromotive Force of a Cell Incorporating a Composition Gradient Solid Electrolyte

New composition gradient solid electrolytes have been designed for application in high temperature solid-state galvanic sensors and in thermodynamic measurements. The functionally gradient electrolyte consists of a solid solution between two or more ionic conductors with a common ion and gradual variation in composition of the other ionic species. Unequal rates of migration of the ions, caused by the presence of the concentration gradient, may result in the development of space charge, manifesting as diffusion potential. Presented is a theoretical analysis of the EMF of cells incorporating gradient solid electrolytes. An analytical expression is derived for diffusion potential, using the thermodynamics of irreversible processes, for different types of concentration gradients and boundary conditions at the electrode/electrolyte interfaces. The diffusion potential of an isothermal cell incorporating these gradient electrolytes becomes negligible if there is only one mobile ion and the transport numbers of the relatively immobile polyionic species and electrons approach zero. The analysis of the EMF of a nonisothermal cell incorporating a composition gradient solid electrolyte indicates that the cell EMF can be expressed in terms of the thermodynamic parameters at the electrodes and the Seebeck coefficient of the gradient electrolyte under standard conditions when the transport number of one of the ions approaches unity.

Symplectic integration of nonlinear Hamiltonian systems

There exist several standard numerical methods for integrating ordinary differential equations. However, if one is interested in integration of Hamiltonian systems, these methods can lead to wrong results. This is due to the fact that these methods do not explicitly preserve the so-called 'symplectic condition' (that needs to be satisfied for Hamiltonian systems) at every integration step. In this paper, we look at various methods for integration that preserve the symplectic condition.

Mechanically activated synthesis of nanocrystalline powders of ferroelectric bismuth vanadate

Mechanical milling of a stoichiometric mixture of Bi2O3 and V2O5 yielded nanosized powders of bismuth vanadate, Bi2VO5.5 (BN). Structural evolution of the desired BiV phase, through an intermediate product (BiVO4), was monitored by subjecting the powders, ball milled for various durations to X-ray powder diffraction (XRD), differential thermal analysis (DTA), and transmission electron microscopic (TEM) studies. XRD studies indicate that the relative amount of the BiV phase present in the ball-milled mixture increases with increase in milling time and its formation reaches completion within 54 h of milling. Assynthesized powders were found to stabilize in the high-temperature tetragonal (gamma) phase. DTA analyses of the powders milled for various durations suggest that the BN phase-formation temperature decreases with increase in milling time. The nanometric size (30 nm) of the crystallites in the final product was confirmed by TEM and XRD studies. TEM studies clearly demonstrate the growth of BiV on Bi2O3 crystallites. (C) 1999 Academic Press.

System Dy-Fe-O: thermodynamic properties of ternary oxides using Calvet calorimetry and solid-state electrochemical cell

The enthalpy increments and the standard molar Gibbs energies of formation-of DyFeO3(s) and Dy3Fe5O12(s) have been measured using a Calvet micro-calorimeter and a solid oxide galvanic cell, respectively. A co-operative phase transition, related to anti-ferromagnetic to paramagnetic transformation, is apparent. from the heat capacity data for DyFeO3 at similar to 648 K. A similar type of phase transition has been observed for Dy3Fe5O12 at similar to 560 K which is related to ferrimagnetic to paramagnetic transformation. Enthalpy increment data for DyFeO3(s) and Dy3Fe5O12(s), except in the vicinity of the second-order transition, can be represented by the following polynomial expressions:{H(0)m(T) - H(0)m(298.15 K)) (Jmol(-1)) (+/-1.1%) = -52754 + 142.9 x (T (K)) + 2.48 x 10(-3) x (T (K))(2) + 2.951 x 10(6) x (T (K))(-1); (298.15 less than or equal to T (K) less than or equal to 1000) for DyFeO3(s), and {H(0)m(T) - H(0)m(298.15 K)} (Jmol(-1)) (+/-1.2%) = -191048 + 545.0 x (T - (K)) + 2.0 x 10(-5) x (T (K))(2) + 8.513 x 10(6) x (T (K))(-1); (208.15 less than or equal to T (K) less than or equal to 1000)for Dy3Fe5O12(s). The reversible emfs of the solid-state electrochemical cells: (-)Pt/{DyFeO3(s) + Dy2O3(s) + Fe(s)}/YDT/CSZ//{Fe(s) + Fe0.95O(s)}/Pt(+) and (-)Pt/{Fe(s) + Fe0.95O(s)}//CSZ//{DyFeO3(s) + Dy3Fe5O12(s) + Fe3O4(s)}/Pt(+), were measured in the temperature range from 1021 to 1250 K and 1035 to 1250 K, respectively. The standard Gibbs energies of formation of solid DyFeO3 and Dy3Fe5O12 calculated by the least squares regression analysis of the data obtained in the present study, and data for Fe0.95O and Dy2O3 from the literature, are given by Delta(f)G(0)m(DyFeO3,s)(kJmol(-1))(+/-3.2)= -1339.9 + 0.2473 x (T(K)); (1021 less than or equal to T (K) less than or equal to 1548)and D(f)G(0)m(Dy3Fe5O12,s) (kJmol(-1)) (+/-3.5) = -4850.4 + 0.9846 x (T (K)); (1035 less than or equal to T (K) less than or equal to 1250) The uncertainty estimates for Delta(f)G(0)m include the standard deviation in the emf and uncertainty in the data taken from the literature. Based on the thermodynamic information, oxygen potential diagram and chemical potential diagrams for the system Dy-Fe-O were developed at 1250 K. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.