Shape Controlled Plasmonic Sn Doped CdO Colloidal Nanocrystals: A Synthetic Route to Maximize the Figure of Merit of Transparent Conducting Oxide.

The synthesis of different anisotropic shaped (eight different shapes) Sn4+ doped CdO (Sn:CdO) colloidal nanocrystals (NCs) by precise tuning of precursor reactivity and proper choice of capping agent is reported. In all these systems, formation of Sn:CdO quantum dots (QDs) of 2-3 nm is identified at very early stage of reaction. The colloidally stable QDs act as a continuous source for the formation of primary nanoparticles that can be transformed selectively into specific type of nanoparticle morphology. The specific facet stabilization of fcc (face centered cubic)CdO is predicted by particular choice of ligand. Fine tuning of plasmonic absorbance band can be achieved by variation of Sn4+ doping concentration. Different anisotropic Sn:CdO NCs exhibit interesting shape dependent plasmonic absorbance features in NIR region. High quality crack free uniform dense thin film has been deposited on glass substrate to make high quality transparent conducting oxide (TCO) coatings. figure of merit of TCO can be maximized as high as 0.523 Ω-1 with conductivity of 43 600 S cm-1 and visible transmittance of ≈85% which is much higher than commercially available tin doped indium oxide and other transparent electrodes.

Excitation dependent multicolor emission and photoconductivity of Mn, Cu doped In2S3 monodisperse quantum dots.

Indium sulphide (In2S3) quantum dots (QDs) of average size 6 ± 2 nm and hexagonal nanoplatelets of average size 37 ± 4 nm have been synthesized from indium myristate and indium diethyl dithiocarbamate precursors respectively. The absorbance and emission band was tuned with variation of nanocrytal size from very small in the strong confinement regime to very large in the weak confinement regime. The blue emission and its shifting with size has been explained with the donor-acceptor recombination process. The 3d element doping (Mn(2+) and Cu(2+)) is found to be effective for formation of new emission bands at higher wavelengths. The characteristic peaks of Mn(2+) and Cu(2+) and the modification of In(3+) peaks in the x-ray photoelectric spectrum (XPS) confirm the incorporation of Mn(2+) and Cu(2+) into the In2S3 matrix. The simulation of the electron paramagnetic resonance signal indicates the coexistence of isotropic and axial symmetry for In and S vacancies. Moreover, the majority of Mn(2+) ions and sulphur vacancies (VS ) reside on the surface of nanocrystals. The quantum confinement effect leads to an enhancement of band gap up to 3.65 eV in QDs. The formation of Mn 3d levels between conduction band edge and shallow donor states is evidenced from a systematic variation of emission spectra with the excitation wavelength. In2S3 QDs have been established as efficient sensitizers to Mn and Cu emission centers. Fast and slow components of photoluminescence (PL) decay dynamics in Mn and Cu doped QDs are interpreted in terms of surface and bulk recombination processes. Fast and stable photodetctors with high photocurrent gain are fabricated with Mn and Cu doped QDs and are found to be faster than pure In2S3. The fastest response time in Cu doped QDs is an indication of the most suitable system for photodetector devices.

Enhanced photophysical properties of plasmonic magnetic metal-alloyed semiconductor heterostructure nanocrystals: a case study for the Ag@Ni/Zn1-xMgxO system.

Understanding the effect of homovalent cation alloying in wide band gap ZnO and the formation of metal-semiconductor heterostructures is very important for maximisation of the photophysical properties of ZnO. Nearly monodisperse ZnO nanopyramid and Mg alloyed ZnO nanostructures have been successfully synthesized by one pot decomposition of metal stearate by using oleylamine both as activating and capping agent. The solid solubility of Mg(ii) ions in ZnO is limited to ∼30% without phase segregation. An interesting morphology change is found on increasing Mg alloying: from nanopyramids to self-assembled nanoflowers. The morphology change is explained by the oriented attachment process. The introduction of Mg into the ZnO matrix increases the band gap of the materials and also generates new zinc interstitial (Zni) and oxygen vacancy related defects. Plasmonic magnetic Ag@Ni core-shell (Ag as core and Ni as shell) nanocrystals are used as a seed material to synthesize Ag@Ni/Zn1-xMgxO complex heterostructures. Epitaxial growth is established between Ag(111) and ZnO(110) planes in the heterostructure. An epitaxial metal-semiconductor interface is very crucial for complete electron-hole (e-h) separation and enhancement of the exciton lifetime. The alloyed semiconductor-metal heterostructure is observed to be highly photocatalytically active for dye degradation as well as photodetection. Incorporation of magnetic Ni(0) makes the photocatalyst superparamagnetic at room temperature which is found to be helpful for catalyst regeneration.

Carrier concentration dependent optical and electrical properties of Ga doped ZnO hexagonal nanocrystals.

Colloidal trivalent gallium (Ga) doped zinc oxide (ZnO) hexagonal nanocrystals have been prepared to introduce more carrier concentration into the wide band gap of ZnO. The dopant (Ga) modifies the morphology and size of ZnO nanocrystals. Low content of Ga enhances the optical band gap of ZnO due to excess carrier concentration in the conduction band of ZnO. The interaction among free carriers arising from higher concentration of Ga gives rise to narrowing of the band gap. Surface plasmon resonance absorption appears in the infrared region due to excessive carrier concentration. A broad emission band consists of blue, yellow and green colors associated with different native defects of ZnO. Intrinsic defects and extrinsic dopant Ga control the defect related emission spectrum in the visible region. Replacement of Zn by Ga induces a room temperature metallic state in a degenerate semiconductor. Cationic disorder leads to metal-semiconductor transition at low temperature strongly dependent on the concentration of Ga. Pure semiconducting behavior up to about 80 K is observed for the highest amount of Ga. Temperature dependent metal-semiconductor transition has been interpreted by localization of charge carriers due to disorder arising from random Ga substitution.

BI-69A11 enhances susceptibility of colon cancer cells to mda-7/IL-24-induced growth inhibition by targeting Akt.

BACKGROUND: Akt and its downstream signalling pathways contribute to the aetiology and progression of colorectal carcinoma (CRC). Targeting the Akt pathway is an attractive strategy but few chemotherapeutic drugs have been used to treat CRC with only limited success. BI-69A11, a small molecule inhibitor of Akt, efficiently inhibits growth in melanoma cells. Melanoma differentiation associated gene-7 (mda-7)/interleukin-24 promotes cancer-selective apoptosis when delivered by a tropism-modified replication incompetent adenovirus (Ad.5/3-mda-7). However, Ad.5/3-mda-7 displays diminished antitumour efficacy in several CRC cell lines, which correlates with the expression of K-RAS. METHODS: The individual and combinatorial effect of BI-69A11 and Ad.5/3-mda-7 in vitro was studied by cell viability, cell cycle, apoptosis and invasion assays in HT29 and HCT116 cells containing wild type or mutant K-ras, respectively. In vivo HT29 tumour xenografts were used to test the efficacy of the combination treatment. RESULTS: BI-69A11 inhibited growth and induced apoptosis in CRC. However, combinatorial treatment was more effective compared with single treatment. This combination showed profound antitumour and anti angiogenic effects in vitro and in vivo by downregulating Akt activity. CONCLUSIONS: BI-69A11 enhances the antitumour efficacy of Ad.5/3-mda-7 on CRC overexpressing K-RAS by inducing apoptosis and regulating Akt activity thereby warranting further evaluation in treating CRC.

Macro-anatomical variation of the olfactory apparatus in some Indian teleosts with special reference to their ecological habitat.

The anatomy of the peripheral olfactory apparatus (i.e. olfactory lamellae, olfactorychambers, accessory nasal sacs, olfactory nerve tracts, olfactory bulbs and brain) of some teleosts, viz. Pseudapocryptes lanceolatus (Bloch and Schneider, 1801) - an air breathing mudskipper, Lepidocephalichthys guntea (Hamilton, 1822) - a freshwater scavenger fish and Mastacembelus armatus (Lacepède, 1800) - a freshwater potamodromous fish, has been studied in relation to their specific ecological habitat. Live, adult, sex-independent fish species were collected from the local markets of West Bengal, India, and acclimatised with the laboratory conditions (for 72 h at 32°C). The specimens were anaesthetised by MS-222 (dose: 100-200 mg/L). Olfactory apparatuses were dissected out and fixed inaqueous Bouin's solution. The macro- and microstructures (using haematoxylin and eosin) of the olfactory apparatuses were examined under binocular light microscope (LM) and trinocular LM (Primo Star; Carl Zeiss Microscpy, GmbH, Germany) respectively. P. lanceolatus possesses unilamellar olfactory apparatus at therounded snout, whereas L. guntea shows small rosette with 18 to 24 lamellae oneither side of the elliptical snout. Elongated olfactory rosette (number of lamellae ranges from 60 to 76) is present at the pointed snout of M. armatus. Morpho-anatomical variation in snout structure of the respective species is an indicative of divergence in ecological habitat, but variation in olfactory apparatus is significant for species-specific differentiation. Pseudostratified olfactory neuroepithelial components (i.e. sensory receptor cell, supporting cell and basal cell) show striking similarities amongst these species. Therefore comparative anatomical changes of the snout and olfactory apparatus are not only representing ecological habitat based on interspecific variation, but may also indicate the phylogenetic relation amongst said species.

Interfacial magnetism and exchange coupling in BiFeO3-CuO nanocomposite.

Ferromagnetic BiFeO3 nanocrystals of average size 9 nm were used to form a composite with antiferromagnetic CuO nanosheets, with the composition (x)BiFeO3/(100-x)CuO, x = 0, 20, 40, 50, 60, 80 and 100. The dispersion of BiFeO3 nanocrystals into the CuO matrix was confirmed by x-ray diffraction and transmission electron microscopy. The ferromagnetic ordering as observed in pure BiFeO3 occurs mainly due to the reduction in the particle size as compared to the wavelength (62 nm) of the spiral modulated spin structure of the bulk BiFeO3. Surface spin disorder of BiFeO3 nanocrystals gives rise to an exponential behavior of magnetization with temperature. Strong magnetic exchange coupling between the BiFeO3 nanocrystal and the CuO matrix induces an interfacial superparamagnetic phase with a blocking temperature of about 80 K. Zero field and field cooled magnetizations are analyzed by a ferromagnetic core and disordered spin shell model. The temperature dependence of the calculated saturation magnetization exhibits three magnetic contributions in three temperature regimes. The BiFeO3/CuO nanocomposites reveal an exchange bias effect below 170 K. The maximum exchange bias field HEB is 1841 Oe for x = 50 at 5 K under field cooling of 50 kOe. The exchange bias coupling results in an increase of coercivity of 1934 Oe at 5 K. Blocked spins within an interfacial region give rise to a remarkable exchange bias effect in the nanocomposite due to strong magnetic exchange coupling between the BiFeO3 nanocrystals and the CuO nanosheets.

ZnO nanowire arrays: synthesis, optical and field emission properties.

Nanowire arrays of zinc oxide were synthesized on zinc foil by a simple thermal evaporation process. Morphologies and sizes of the synthesized nanostructures were varied by varying the reaction time and the surface roughness of the substrate. Self-catalytic liquid-solid mechanism was proposed for the growth of nanowires. ZnO nanostructures exhibited a strong UV emission at approximately 382 nm attributed to the band edge emission along with a defect related broad green emission at approximately 513 nm. These nanowire arrays exhibits good field emission property.

Synthesis of ZnO nanoparticles by solvothermal method and their ammonia sensing properties.

ZnO nanoparticles were prepared by a simple solvothermal route by using a ethylene glycol (EG)-ethanol (E) solvent system. The shape and size of ZnO nanoparticles were tuned by changing the volume composition of the solvents and the synthesis temperature. Phase purity was confirmed by X-ray diffraction (XRD) and crystal size was determined by transmission electron microscopy (TEM). Ellipsoidal and spherical nanoparticles were obtained by varying the volume ratio of the solvents. Mostly spherical nanoparticles with average diameter of 4 nm was synthesized with higher volume fraction of EG at a lower synthesis temperature. The blueshift of room-temperature photoluminescence measurement from free exciton transition are observed for the smallest nanoparticle size that is ascribed to the quantum confinement effect. The ammonia gas sensing characteristics of the smallest diameter nanoparticles showed better sensitivity at a relatively lower temperature than that of large diameter particles.

Tuning of the spin gap transition of spin dimer compound Ba(3)Mn(2)O(8) by doping with La and V.

We have successfully synthesized the coupled spin dimer systems La(x)Ba(3-x)Mn(2)O(8) (x = 0, 0.2, 0.5, 1) and Ba(3)Mn(2-y)V(y)O(8) (y = 0.5, 1.0, 2.0). The magnetic properties have been investigated as a function of magnetic field and temperature down to 2 K. The susceptibility increases and the intradimer spin exchange interaction decreases with increase of La concentration. The most important finding in higher La doped systems reveals hysteresis in magnetization as a function of magnetic field. The substitution of La (x = 0.5, 1.0) for Ba induces ferromagnetism due to the formation of a mixed valence state of Mn and enhancement of the inter-bilayer ferromagnetic interaction. The replacement of Mn by non-magnetic V destroys the spin gap. La and V doping significantly affect the magnetic properties of the quantum antiferromagnetic compound Ba(3)Mn(2)O(8).

Exchange bias effect in a finite site disordered canted antiferromagnet.

We report the temperature and magnetic field dependent magnetic properties of the single-phase polycrystalline La0.8Sr0.2Cr0.7Ru0.3O3 sample to explore the intrinsic magnetic phases of the sample. Our combined temperature and field dependent magnetization studies reveal the formation of ferromagnetic (FM) cluster-glass in the antiferromagnetic (AFM) matrix of host LaCrO3. Interestingly, the as-studied sample exhibits both zero-field-cooled (horizontal shift) and field-cooled (vertical shift) exchange bias effects and, in both cases, magnitude of exchange bias field continuously increases with the decrease of temperature. Our successive hysteresis loop measurements completely ruled out the effect of any minor hysteresis loop and thus, establishes this vertical shift as conventional field-cooled exchange bias (CEB) effect, originating from the uncompensated spins of randomly substituted canted AFM spin structure. A significantly larger value of CEB field (7.5 kOe) at 5 K is achieved for a cooling field of 50 kOe, not usually observed in conventional FM/AFM interfacial exchange-bias systems.

Human chorionic gonadotropin hormone prevents wasting syndrome and death in HIV-1 transgenic mice.

At birth, transgenic mice, homozygous for the HIV-1 provirus pNL4-3, deleted in gag/pol, are normal in appearance and weight. Within several days after birth, the pups develop a syndrome characterized by dry, scaly, hyperkeratotic skin, growth failure, and death. The possibility that the homozygous embryos are being protected during gestation by a maternal factor led us to treat the newborn animals with various pregnancy-related hormones including human chorionic gonadotropin (hCG), estrogen, progesterone, and dexamethasone. Treatment with hCG prevented death, led to normal growth, and markedly reduced skin lesions. In contrast to the skin of the untreated homozygous pups, which expressed high levels of HIV mRNA and proteins (i.e., gp120 and Nef), the skin of the hCG-treated pups showed a marked reduction in both HIV mRNA and proteins. Discontinuation of hCG resulted in the reappearance of HIV transcripts and proteins, skin lesions, and growth failure resulting in death. In addition, HIV transcripts and proteins were reduced significantly in heterozygous mothers during pregnancy, but reappeared after parturition. Similarly, hCG treatment resulted in a decrease of HIV proteins in the skin of nonpregnant heterozygous transgenic mice. These findings suggest that the inhibiting effect of hCG on HIV expression may be clinically useful in the treatment of HIV infections, and may be responsible, during pregnancy, for the low transmission of HIV from infected mothers to their offspring.

Electrical conductivity and optical properties of polyaniline intercalated graphite oxide nanocomposites.

Layered graphite oxide is used as host material for the synthesis of conducting polymer intercalated nanocomposites. Powder X-ray diffraction, Fourier transform infrared, and UV-VIS absorption spectra indicate the formation of polyaniline within the interlamellar spaces of graphite oxide. The red shift of UV-VIS absorption associated with graphite oxide is found. The direct current (dc) conductivity increases by about three orders of magnitude compare with pristine graphite oxide. The temperature dependence dc conductivity of the nanocomposite follows Mott's three-dimensional variable range hopping. The alternating current (ac) conductivity suggests correlated barrier hopping of conduction process. The conductivity relaxation time varies in the range of 10(-5)-10(-7) Sec.

Large dielectric constant in zirconia polypyrrole hybrid nanocomposites.

Zirconia nanoparticles have been synthesized by a novel two-reverse emulsion technique and combined with polypyrrole (PPY) to form ZrO2-PPY nanocomposites. Complex impedance and dielectric permittivity of ZrO2-PPY nanocomposite have been investigated as a function of frequency and temperature for different compositions. The composite samples are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy. The composites reveal ordered semiconducting behaviour. Polypyrrole is the major component in electrical transport process of the samples. A very large dielectric constant of about 12,000 at room temperature has been observed. The colossal dielectric constant is mainly dominated by interfacial polarization due to Maxwell-Wagner relaxation effect. Two completely separate groups of dielectric relaxation have been observed. The low frequency dielectric relaxation arises from surface defect states of zirconia nanoparticles. The broad peak at high frequency is due to Maxwell-Wagner type polarization.

Effect of Gd and Cr substitution on the structural, electronic and magnetic phases of SrRuO3: a case study of doping and chemical phase separation.

We explore the crystal structure, electrical resistivity and magnetic behavior of the compositional series (SrRuO3)[Formula: see text] (GdCrO3) x (where [Formula: see text]), which resides between orthorhombic ferromagnetic (FM) metal SrRuO3 ([Formula: see text] K) and orthorhombic antiferromagnetic (AFM) insulator GdCrO3 ([Formula: see text] K). Crystal structure analysis reveals that complete solid solution exists only up to [Formula: see text], above which chemical phase separation of two/three phases occurs, and persists up to [Formula: see text]. X-ray photoelectron spectroscopy measurement also corroborates the existence of [Formula: see text] for the intermediate composition [Formula: see text], which reinforces the astonishing scheelite-type GdCrO4 formation (at ambient pressure) for [Formula: see text] compositions. Electrical resistivity measurements affirm the temperature driven metal to insulator (M-I) transition for [Formula: see text] and [Formula: see text] samples. Low temperature insulating state in these samples is interpreted by electron-electron interaction of weak disordered systems. Precise analysis of temperature dependent resistivity for [Formula: see text] samples (which have insulating ground state) dictate that the transport phenomenon is mainly associated with Arrhenius-type charge conduction, Mott's variable range hopping, short-range and long-range Coulomb interaction mediated hopping processes, due to the high degree of randomness. Interruption of magnetic Ru-O-Ru interaction by Ru-O-Cr and Cr-O-Cr interactions lowers the FM transition temperature (T C), and thereby introduces Griffiths phase in phase separated samples. Furthermore, we believe that a sharp rise in magnetization at low temperature for [Formula: see text] samples is due to the formation of AFM GdCrO4 phase. Prominent thermal hysteresis in temperature dependent magnetization curves for [Formula: see text], and appearance of spin-reorientation transition for [Formula: see text] are the distinct indications for transformation into canted AFM GdCrO3 oxide at higher x. The effective magnetic moment ([Formula: see text]) continuously increases with the incorporation of higher moment elements (Gd and Cr); while coercive field (H C) exhibits an abrupt variation as a function of x at the onset of phase separation.

High dielectric permittivity in silica-polyaniline nanocomposites.

Complex impedance and dielectric permittivity of wide band gap silica-conducting polyaniline nanocomposite have been investigated as a function of frequency and temperature at different compositions. Grain and grain boundary contributions are observed in impedance spectra. The results are interpreted in terms of two series connected equivalent circuit. The large dielectric permittivity approximately 7500 is found. Large value of permittivity is well described by Maxwell-Wagner polarization. Broad and asymmetric dielectric spectra are analyzed by Havriliak-Negami relaxation function.

Giant dielectric constant in titania nanoparticles embedded in conducting polymer matrix.

Complex impedance and dielectric permittivity of titania-polypyrrole nanocomposites have been investigated as a function of frequency and temperature at different compositions. A very large dielectric constant of about 13,000 at room temperature has been observed. The colossal dielectric constant is mainly dominated by interfacial polarization due to Maxwell-Wagner relaxation effect. Two completely separate groups of dielectric relaxation have been observed. The low frequency dielectric relaxation arises from surface defect states of titania nanoparticles. The broad peak at high frequency region is attributed to Maxwell-Wagner type polarization originating from the inhomogeneous property of nanocomposite. An abrupt change in grain boundary conductivity and dielectric relaxation associated with titania was observed at around 150 K. Anomalous behavior in conductivity and dielectric relaxation is qualitatively explained by band tail structure of titania nanoparticle.

Evolution of magnetic properties and exchange interactions in Ru doped YbCrO3.

Magnetic properties of YbCr1-x Ru x O3 as a function of temperature and magnetic field have been investigated to explore the intriguing magnetic phenomena in rare-earth orthochromites. A quantitative analysis of x-ray photoelectron spectroscopy confirms the mixed valence state (Yb(3+) and Yb(2+)) of Yb ions for the highest doped sample. Field-cooled magnetization reveals a broad peak around 75 K and then becomes zero at about 20-24 K, due to the antiparallel coupling between Cr(3+) and Yb(3+) moments. An increase of the Ru(4+) ion concentration leads to a slight increase of compensation temperature T comp from 20 to 24 K, but the Néel temperature remains constant. A larger value of the magnetic moment of Yb ions gives rise to negative magnetization at low temperature. An external magnetic field significantly modifies the temperature dependent magnetization. Simulation of temperature dependent magnetization data, below T N, based on the three (two) magnetic sub-lattice model predicts stronger intra-sublattice exchange interaction than that of inter-sublattice. Thermal hysteresis and Arrot plots suggest first order magnetic phase transition. Random substitution of Ru(4+) ion reduces the magnetic relaxation time. Weak ferromagnetic component in canted antiferromagnetic system and negative internal magnetic field cause zero-field-cooled exchange bias effect. Large magnetocrystalline anisotropy associated with Ru creates high coercivity in the Ru doped sample. A maximum value of magnetocaloric effect is found around the antiferromagnetic ordering of Yb(3+) ions. Antiferromagnetic transition at about 120 K and temperature induced magnetization reversal lead to normal and inverse magnetocaloric effects in the same material.

Glucocorticoid effects on gastric peroxidase activity.

The peroxidase activity in rat gastric mucosa is inhibited after administration of glucocorticoids. The synthetic steroid dexamethasone is more potent than the naturally occurring steroids, such as cortisone or corticosterone. Almost complete inhibition of the enzyme occurs after 24 h with a single dose of 100 micrograms dexamethasone/120 g body weight. Other mitochondrial enzyme activities, like monoamine oxidase, succinic dehydrogenase and Mg2+-ATPase, remain unaltered under the same experimental condition. Submaxillary peroxidase and thyroid peroxidase activity are not inhibited by dexamethasone. Gastric peroxidase activity is increased 200-250% on the 6th day after adrenalectomy. This effect is blocked by the administration of dexamethasone. In fact, the enzyme becomes more sensitive to dexamethasone after adrenalectomy, since it is inhibited by more than 90% at the dose of 25 micrograms/120 g body weight. The inhibition by dexamethasone in normal animals is reversible. The enzyme is also inhibited after the administration of a single dose of ACTH. The apparent Km of the enzyme for H2O2 is not altered after dexamethasone treatment or after adrenalectomy. The increase in enzyme activity following adrenalectomy is not blocked by actinomycin D or by alpha-amanitin, but is prevented by puromycin or cycloheximide. After administration of dexamethasone, the iodide concentration process in the gastric mucosa is not affected, but the organification of iodide is significantly diminished.

Metallothionein mRNA stability in chicken and mouse cells.

Northern blot analysis revealed that metallothionein (MT) mRNAs accumulate after inhibition of protein synthesis with cycloheximide (CHX) in primary cultures of chick embryo hepatocytes and fibroblasts, as well as in an established mouse hepatoma cell line. Inhibition of RNA synthesis with actinomycin D (AMD) led to rapid loss of MT mRNAs in these cells, whereas CHX dramatically retarded the rate of MT mRNA decay (t1/2 greater than 24 h). These results suggest that CHX causes MT mRNA accumulation primarily by increasing stability of MT mRNA. Thus, changes in MT mRNA turn-over rates may play an important role in regulating the accumulation of MT mRNA. The half-lives of MT mRNAs in chicken and mouse cells were determined by oligodeoxyribonucleotide excess solution hybridization with RNA samples extracted after different periods of exposure to AMD. The half-life of chicken MT (cMT) mRNA in uninduced chicken embryo hepatocytes was 3.6 h. Induction of cMT mRNA by pretreatment of these cells with zinc (Zn) prior to exposure to AMD, did not alter the half-life of cMT mRNA significantly. In contrast, cadmium (Cd) induction led to a 2.5-fold increase in the stability of this mRNA. In uninduced chicken embryo fibroblasts, cMT mRNA levels were too low to allow accurate determination of half-life using the methods employed here. However, the half-life of this mRNA in Zn-induced chicken embryo fibroblasts was 6.2 h, whereas it was 9.3 h in Cd-induced cells. Thus, the turn-over rate of cMT mRNA after Cd-induction is very similar in chick embryo fibroblasts and hepatocytes. These data suggest that the accumulation of MT mRNA in chicken cells may reflect, in part, metal-specific effects on MT mRNA stability. The half-lives of mouse MT-I and MT-II (mMT-I and mMT-II) mRNAs in uninduced BNL hepatoma cells were identical (9.2 h), and were not effectively altered after induction by metals (Zn, Cd) or interleukin-1 beta (IL-1 beta). However, mMT mRNAs in pachytene spermatocytes and round spermatids, freshly isolated from the adult testes, were 2.2- to 4.5-fold more stable than in hepatoma cells. These results suggest that cell-type specific accumulation of mMT mRNAs may be regulated, in part, by mRNA stability.