Different Degrees Of Association Research Articles

Dilatational properties of soy globulin adsorbed films at the air–water interface from acidic solutions

In this paper we present surface dilatational properties of soy globulins (β-conglycinin, glycinin, and reduced glycinin with 10 mM of dithiothreitol (DTT)) adsorbed on the air–water interface, as a function of adsorption time. The surface rheological parameters (surface dilatational modulus, E, its elastic and viscous components, and phase angle) were measured as a function of protein concentration (ranging from 1 to 1 × 10 −3%, wt/wt) at pH 2.0 and 5.0. We found that the surface dilatational modulus, E, increases with time, θ. This phenomenon has been related to protein adsorption, unfolding, and/or protein–protein interactions (at long-term adsorption). The dilatational properties of the adsorbed films depend on the molecular structure of the protein, the pH, and on the protein concentration in the aqueous phase. Soy globulins are adsorbed at the air–water interface with different degrees of association at different concentrations in the bulk phase and at different aqueous phase pH.

Analysis of human papillomavirus type-16 variants in Italian women with cervical intraepithelial neoplasia and cervical cancer.

Human papillomavirus type 16 (HPV-16) classes (E, AA, As, Af1, Af2) and their variants have different geographic distribution and different degrees of association with cervical lesions. This study was designed to examine HPV-16 variants among Italian women and their prevalence in case patients (affected by invasive cervical carcinoma or cervical intraepithelial neoplasia grade 2-3 and cervical intraepithelial neoplasia grade 1), versus control subjects with normal cervical epithelium (controls). A total of 90 HPV-16 positive cervical samples from women of Italian Caucasian descent have been tested, including 36 invasive cervical carcinomas, 21 with cervical intraepithelial neoplasias grade 2-3, 17 with cervical intraepithelial neoplasia grade 1 and 16 controls. HPV-16 was detected with an E6/E7 gene-specific polymerase chain reaction, and variant HPV-16 classes and subclasses were identified by direct nucleotide sequencing of the region coding for the E6 and the E7 oncoproteins, the MY09/11-amplified highly conserved L1 region, and the long control region (LCR). Among the 90 HPV-16 samples, nine viral variants have been identified belonging to the European (Ep-T350 and E-G350) and non-European (AA and Af-1) branches. The E-G350 is the prevalent variant in all analyzed different disease stages being present in 55.5% of ICC, 52.4% of cervical intraepithelial neoplasias 2-3, 47.1% of cervical intraepithelial neoplasia grade 1, and 50.0% of control samples. The non-European variants AA and Af1, rarely detected in control samples, represent 33.3% of all HPV-16 infections in invasive cervical carcinoma (with a peak of 19.4% and 13.9%, respectively), showing a statistically significant increase in frequency in more advanced lesions (chi(2) trend = 7.2; P < 0.05). The prevalence of HPV-16 Ep-T350, however, is higher in controls (43.7%) and in of cervical intraepithelial neoplasia grade 1 (41.2%) than in cervical intraepithelial neoplasia grade 2-3 (28.6%) and in invasive cervical carcinoma (11.1%) cases strongly suggesting lack of progression for pre-neoplastic lesions associated with such variant. The increased frequency of non-European variants in invasive lesions suggests that they are more oncogenic than European variants. This could have implications for future diagnostic and therapeutic strategies.

Spezifische IgE-Werte gegen Aero- und Nahrungsmittelallergene im Vergleich: Dr. Fooke ALLERG-O-LIQ und Pharmacia CAP-System

Two in vitro assays for the detection of allergen-specific IgE (sIgE) were compared reestimating sera with sIgE to common inhalants (birch t3, timothy g6, mugwort w6, cat dander el, dog dander e5, housdust mite D. pter. dl) and food allergens (FA) (hen's egg fl, cow's milk f2, wheat flour f4, soy bean f14, hazelnut f17, apple f49). Quantitative values (kU/l) of both systems were associated to different degrees depending on the allergen: allergen/n t3/48, g6/47, w6/39, e1/40, e5/42, d1/39. Spearman's rho 0.95***, 0.9***, 0.82***, 0.9***, 0.82***, 0.85***, allergen/n f1/37 f2/38 f4/68 f14/52f17/40 f49/40. Spearman's rho 0.84***, 0.6***, 0.6***, 0.31*, 0.68***, 0.82***, *** p < 0.001; * p < 0.05. Values to inhalants (t3, g6, el, e5) were scattered moderately around an ideal regression line (diagonal between x-and y-axis). In contrast, sIgE-levels to FA (f2, f4, f14, fl7) showed stronger discrepancies between both systems. Similarly, different degrees of association and spreading, depending on the individual allergen, were found comparing semiquantitative classes (0 - 6) of both systems. Taken together, values of sIgE to inhalants detected by different in vitro methods are stronger associated than sIgE to FA; IgE-values to allergens with one dominant major allergen (i.e. t3, el) seem to be more concordant than complex allergen mixtures (i.e. dl); identical units (kU/l) can not garantee equivalent IgE results. The data presented do not allow estimates of the real IgE concentrations or judgement on superiority of one of the tests over the other. The study is restricted to compare both methods analytically, since the diagnostic concordance could not be calculated due to a lack of corresponding clinical data. Despite these limitations, comparative sIgE studies are necessary and helpful to define the concordance of IgE values detected by different immunoassays. They also set the basis for subsequent improvement of allergens used in test systems detecting specific IgE.

Wedged between bottom‐up and top‐down processes: aphids on tansy

Abstract. 1. Many species of aphids exploit a single host‐plant species and have to cope with changing environmental conditions. They often vary greatly in abundance even when feeding on the same host. In a field experiment, the bottom‐up (plant quality/patch type frequency) and top‐down (ant attendance/predation) effects on the abundance of four species of aphids feeding on tansy (Tanacetum vulgare) were tested using a full factorial design. In addition, a model was used to examine these patch characteristics for their relative effects on the population dynamics and abundance of different aphid species.2. Aphid numbers changed significantly depending on the quality of the host plant and the presence/absence of attending ants. The obligate myrmecophile,Metopeurum fuscoviride, was abundant on high‐quality plants, while on poor quality plants or on plants without attending ants these aphids did not survive until the end of the experiment. The facultative myrmecophiles,Aphis fabaeandBrachycaudus cardui, and the unattended aphid species,Macrosiphoniella tanacetaria, all reached similar peak population densities, butM. tanacetariadid best in poor quality patches.3. Natural enemies reduced aphid numbers, but those species feeding on high‐quality plants survived longer than those on poor‐quality plants, which existed only for a short period of time, especially when associated with ants. Losses due to migration of winged morphs and mortality caused by parasitoids were insignificant.4. Varying the frequency of different patch types in a model indicates that different degrees of associations with ants are favoured in different environments. If the proportion of high‐quality patches in a habitat is large, obligate myrmecophiles do best. On increasing the number of poor‐quality patches, unattended species become more abundant.5. The results suggest that, in spite of large species specific differences in growth rates, degree of myrmecophily or life cycle features, the temporal and spatial variability in top‐down and bottom‐up forces differentially affects aphid species and allows the simultaneous exploitation of a shared host‐plant species.

Epidemiology of concomitant infections due to Loa loa, Mansonella perstans, and Onchocerca volvulus in rain forest villages of Cameroon.

An epidemiological survey was conducted in 16 remote villages of the rain forest of southern Cameroon to ascertain the prevalence and intensity of three species of filariae: Loa loa, Onchocerca volvulus, and Mansonella perstans. We examined 1458 individuals for blood-dwelling microfilariae and 1255 of these were also for the presence of palpable nodules. All the villages surveyed were found highly endemic for onchocerciasis and mansonellosis with prevalence ranging from 28.44% to 87.17% for O. volvulus and 52.48% to 100% for M. perstans. The intensities of infection were also found high for M. perstans with arithmetic means of microfilaremia ranging from 280.94 to 4947.57 mf/ml. The loiasis prevalence was relatively low with value from 2.22% to 19.23%. Males were found more infected than females for the three species of filariae, and the prevalence and intensities of microfilaremia vary differently in males and females at different ages. The three species of filariae displayed different degrees of association in the inhabitants with a low prevalence of co-occurrence between L. loa/O. volvulus and between L. loa/M. perstans. In contrast, there was a high prevalence of co-occurrence between M. perstans and O. volvulus. The implications of the co-occurrence of the three species of filariae in the populations of these remote villages on the intervention programs based on mass treatment with mectizan are discussed.

Solid-state structure and solution behaviour of hypervalent organoantimony halides containing 2-(Me2NCH2)C6H4? moieties

Hypervalent antimony(III) halides of the type R2SbX [X = Cl (1), Br (2), I (3)] and RSbX2 [X = Cl (4), Br (5), I (6)] [R = 2-(Me2NCH2)C6H4] have been prepared. Their dynamic solution behavior was investigated by 1H and 13C NMR spectroscopy. The structures of compounds 2–6 were determined by single-crystal X-ray diffraction and the observed trends in the degree of intramolecular coordination of the N atom of the pending CH2NMe2 arm are discussed. Compounds 2 and 3 are monomeric and exhibit distorted square-pyramidal (C,N)2SbX cores. The molecular structure of the adduct R2SbI·HI (3·HI) indicates the strong coordination of one of the N atoms to antimony. The second pendant arm is twisted away from the metal center, its N atom being protonated and thus converted into an ammonium group. The molecules of 4–6 contain a pseudo-trigonal bipyramidal geometry around the antimony atom, with the N atom strongly coordinated trans to a halogen atom. Different degrees of association through asymmetric Sb–X⋯Sb bridges [overall distorted square-pyramidal (C,N)SbX3 cores] were found in the crystal of the dichloride 4 (polymeric chains) and dibromide 5 and diiodide 6 (centrosymmetric dimers), respectively. In an attempt to obtain [R3SbI]I3 by addition of I2 to R3Sb in 2 ∶ 1 molar ratio, deep red-brown crystals of the new ionic species [R3SbOH]+[I3]− (7) have been isolated. Crystals of 7 are built up from [R3SbOH]+ cations and linear non-symmetric [I3]− anions.

Association of ants with juvenile Ogyris amaryllis amaryllis Hewitson (Lepidoptera: Lycaenidae) in south-eastern Queensland

The life history of the mistletoe-feeding butterfly Ogyris amaryllis is commonly thought to involve an obligate association with ants. The distribution of eggs of subspecies O. a. meridionalis Bethune-Baker, which occurs over much of the Australian interior, is strongly associated with Iridomyrmex ants. This study examined the level and frequency of ant association exhibited by larvae and pupae of O. a. amaryllis, which occurs in coastal areas of eastern Australia. The distribution of juveniles was compared with that of ants at the scale of sites, mistletoe host trees, and larval sheltering locations. A significant positive association between larvae and ants was detected, although this association was weak and non-specific, indicating that O. a. amaryllis is facultatively myrmecophilous. Observed ant attendance of larvae was uncommon (5.6%). Available evidence suggests that either plasticity exists in the degree of myrmecophily of O. amaryllis, with different degrees of association expressed under different ecological circumstances, or different degrees of myrmecophily are characteristic of subspecific status.

He(I) Photoelectron Spectroscopy and Electronic Structure of Alkyllithium Clusters

The electronic structure of some alkyllithium clusters has been investigated by He(I) photoelectron spectroscopy. Two distinct types of spectra have been observed. This is explained by the different degree of association of the compounds in the gas phase, as determined by the steric demand of the alkyl substituent. From the analysis of the spectra it can be concluded that isopropyl- (i-PrLi), sec-butyl- (s-BuLi), and tert-butyllithium (t-BuLi) form only tetramers, while ethyl- (EtLi), n-propyl- (n-PrLi), n-butyl- (n-BuLi), and isobutyllithium (i-BuLi) are mixtures of tetrameric and hexameric clusters in the gas phase. This observation is in accord with former mass spectrometric investigations [Plavšić, D.; Srzić, D.; Klasinc, L. J. Phys. Chem. 1986, 90, 2075; Berkowitz, J.; Bafus, D. A.; Brown, T. L. J. Phys. Chem. 1961, 65, 1380]. The band shapes and intensities are interpreted by large geometry changes taking place during the ionization as a consequence of Jahn−Teller distortion of the ionic clusters and the change of electrostatic interactions. The nature and extent of the distortion is examined by ab initio quantum chemical calculations. The effect of the substituents and the degree of association on the electronic structure is also clarified.

NMR and Quantum-Chemical Study on the Structure of Ester Enolate−Aluminum Alkyl Complexes as Models of the Active Center in the Anionic Polymerization of Methacrylates in Toluene

6Li and 13C NMR on ethyl α-lithioisobutyrate (EiBLi) and quantum-chemical (DFT) calculations on methyl α-lithioisobutyrate (MiBLi) were used to elucidate the structure of the active center in the anionic polymerization of methacrylates in the presence of triethylaluminum (AlEt3) in toluene. This study reveals ester enolate/aluminum alkyl complexes with different degrees of association, (MiBLi·AlEt3)n (n = 1, 2, 4), and different stoichiometries, MiBLi·xAlEt3 (x = 1, 2). In the presence of methyl pivalate (MPiv), which is taken as a model compound for the monomer and polymer, complexes such as (MiBLi·MPiv·AlEt3)n (n = 1, 2) are formed. These complexes can dissociate into MiBLi·2AlEt3 and MPiv·AlEt3 when AlEt3 is used in excess.

Ant attendance in aphids: why different degrees of myrmecophily?

Summary1. Aphids show a range of associations with ants from nonattendance to obligate myrmecophily.Aphis fabae cirsiiacanthoidesis facultatively associated with ants, whileSymydobius oblongusis an obligate myrmecophile. The selection pressures that have shaped these associations are unknown.2. The consequences for these aphids of their different degrees of associations with ants were determined, in terms of costs and benefits to individuals and colonies in laboratory and field experiments. In the laboratory, individuals ofA. f. cirsiiacanthoidesperformed worse and those ofSymydobius oblongusperformed better when attended by the antLasius nigerthan when unattended. For example, when ant‐attended,A. f. cirsiiacanthoidesdeveloped more slowly, were smaller, and invested less in gonads, whereasS. oblongusdeveloped more quickly, were larger, and invested more in gonads. In addition, the ant regulated the population size ofS. oblongusto an average of 50–70 individuals per birch sapling by removing aphids, but did not regulate the population size ofA. f. cirsiiacanthoides.3. Under field conditions, ant‐attended colonies of bothA. f. cirsiiacanthoides and S. oblongusachieved higher peak numbers and lasted longer, and ant‐attended colonies ofA. f. cirsiiacanthoidesproduced more alate dispersers than unattended colonies.4. The implications of divergent selection pressures for the development of myrmecophily in aphids are discussed.

How Fe 3+ binds anthracycline antitumour compounds : The myth and the reality of a chemical sphinx

The interaction of Fe 3+ with several anthracycline antitumour antibiotics has been reinvestigated. Absorption and circular dichroism (CD) measurements were carried out (i) in aqueous solution and (ii) in semi-aqueous MeOH to avoid the stacking of the anthracycline molecules. The Fe 3+ binding to anthracycline was dependent on the metal-to-ligand molar ratio, antibiotic concentration, ionic strength, and pH. The formation of two major Fe 3+–anthracycline complexes, I and II, was observed for all the drugs. These species differed in their coordination modes to the anthracycline ligands. Complex I was a monomeric species, where Fe 3+ was bound to the anthracycline through the {C(11)–O −; C(12)O} chelating site. In complex II, Fe 3+ was also bound through the {C(5)O; C(6)–O −} coordination site. Thus, the antibiotic ligand was acting as a bridge between two metal ions, forming oligomeric (or polymeric) structures. The different degree of association of the anthracyclines could be responsible for the reactivity of the metal ion. In fact, complexes I and II could constitute mononuclear, binuclear or polynuclear Fe 3+ species depending on the competitive kinetics of both coordination and hydrolysis of the metal ion.

SIZE EXCLUSION CHROMATOGRAPHY OF LIGNINS USING LITHIUM CHLORIDE/N,N-DIMETHYLACETAMIDE AS MOBILE PHASE. I. DISSOLVED AND RESIDUAL BIRCH KRAFT LIGNINS

The molecular weight distributions (MWDs) of dissolved and residual lignins from different delignification phases during flow-through kraft cooking of birch have been studied. The fundamental characteristics of the isolated lignin samples were evaluated and the lignins were characterised by size exclusion chromatography using lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) not used for isolated lignin samples before. The MWDs of underivatized and acetylated samples were compared with the MWDs of acetylated samples obtained by using tetrahydrofuran (THF) as mobile phase in a similar chromatographic system. The results indicate that removal of pulp lignin during the initial phase of kraft cooking of birch is restricted partly because of the large size of the lignin polymer. However, at the end of the cook no such restrictions remain. The apparently larger molecular size obtained with the LiCl/DMAc-system compared to the THF-system, may be due to interactions between the polystyrene standards and column matrix in combination with a more extensive conformation of the lignin polymer and/or a higher degree of swelling of the polystyrene-divinylbenzene matrix. Although differently accentuated, the residual lignin samples show a bimodal MWD in both solvents. Possible explanations for this phenomenon may be due to structural heterogeneity in the residual lignin, different molecular conformation due to the polarity of the solvent and/or different degrees of associations between lignin fragments in the two solvents.

Different concentrations of Mg++ ions affect nuclear matrix protein distribution during thermal stabilization of isolated nuclei.

The nuclear matrix, a proteinaceous network believed to be a scaffolding structure determining higher-order organization of chromatin, is usually prepared from intact nuclei by a series of extraction steps. In most cell types investigated the nuclear matrix does not spontaneously resist these treatments but must be stabilized before the application of extracting agents. Incubation of isolated nuclei at 37C or 42C in buffers containing Mg++ has been widely employed as stabilizing agent. We have previously demonstrated that heat treatment induces changes in the distribution of three nuclear scaffold proteins in nuclei prepared in the absence of Mg++ ions. We studied whether different concentrations of Mg++ (2.0-5 mM) affect the spatial distribution of nuclear matrix proteins in nuclei isolated from K562 erythroleukemia cells and stabilized by heat at either 37C or 42C. Five proteins were studied, two of which were RNA metabolism-related proteins (a 105-kD component of splicing complexes and an RNP component), one a 126-kD constituent of a class of nuclear bodies, and two were components of the inner matrix network. The localization of proteins was determined by immunofluorescent staining and confocal scanning laser microscope. Mg++ induced significant changes of antigen distribution even at the lowest concentration employed, and these modifications were enhanced in parallel with increase in the concentration of the divalent cation. The different sensitivity to heat stabilization and Mg++ of these nuclear proteins might reflect a different degree of association with the nuclear scaffold and can be closely related to their functional or structural role.

Contrasting histories of three gene regions associated with In(3L)Payne of Drosophila melanogaster.

In the present report, we studied nucleotide variation in three gene regions of Drosophila melanogaster, spanning > 5 kb and showing different degrees of association with the cosmopolitan inversion In(3L)Payne. The analysis of sequence variation in the regions surrounding the breakpoints and the heat shock 83 (Hsp83) gene locus, located close to the distal breakpoint, revealed the absence of shared polymorphisms and the presence of a number of fixed differences between arrangements, indicating absence of genetic exchange. In contrast, for the esterase-6 gene region, located in the center of the inversion, we observed the presence of shared polymorphisms between arrangements suggesting genetic exchange. In the regions close to the breakpoints, the common St arrangement is 10 times more polymorphic than inverted chromosomes. We propose that the lack of recombination between arrangements in these regions coupled with genetic hitchhiking is the best explanation for the low heterozygosity observed in inverted lines. Using the data for the breakpoints, we estimate that this inversion polymorphism is around 0.36 million yr old. Although it is widely accepted that inversions are examples of balanced polymorphisms, none of the current neutrality tests including our Monte Carlo simulations showed significant departure from neutral expectations.

Transmission of Cervical Human Papillomavirus Infection by Sexual Activity: Differences between Low and High Oncogenic Risk Types

Not all studies have proven that cervical human papillomavirus (HPV) infection is a sexually acquired condition. Determinants of HPV infection were analyzed in a survey of 718 asymptomatic women in northeastern Brazil. HPV DNA was detected and typed by polymerase chain reaction. HPV types were classified into low- and high-risk groups on the basis of their association with cervical carcinomas. Overall HPV prevalence (18.3%) was moderately associated with age at first intercourse (P = .111, trend) and number of lifetime sex partners (P = .005, trend). However, separate analyses by risk revealed different degrees of association with sexual activity. Except for a positive association with multiple partners among women < 40 years old (P = .034, trend), infection with low-risk types (9.7%) was not correlated with sexual behavior. On the other hand, infection with high-risk HPV types (11.6%) was strongly and independently associated with both multiple partners (P = .009, trend) and age at first intercourse (P = .007, trend) in all age groups.

The assessment of sequential response organization in schizophrenic and control subjects

1.A novel analysis is introduced for the sequential organization of behavioral elements derived from the ergodic theory of nonlinear dynamical systems and statistical mechanics of physical systems. 2. This analysis yields the fluctuation spectrum of local dynamical entropies, S ( h), which quantifies the contributions of subsequences with different degrees of association between elements to the overall observed behavior. In addition, ( q-dependent order parameter functions assess the relationship between the degree of association between consecutive behavioral elements and qualitative aspects of the subsequences. 3. A binary choice task paradigm is used to extract thought-contingent responses in order to determine the organisation of sequences of behavioral actions. 4. A group a schizophrenic patients and controls was tested with a binary choice task paradigm to determine the sequential organization of their responses. 5.The results indicate that the overall response sequences of both schizophrenics and controls are non-random. In addition, clear differences in qualitative aspects between response subsequences with different degrees of association are revealed. Finally, significant fluctuations within individual subjects were found between highly predictable and highly unpredictable response subsequences. 6.These results are discussed with respect to dysregulations in behavioral organization that could not be assessed previously and may provide new insights into the behavioral effects of the underlying dysregulated neural circuitry.

Soil structure and carbon cycling

Samples from the surface horizons of six virgin soils were collected and separated into density fractions. Based on the spatial distribution of organic materials within the mineral matrix of soil, the soil organic matter (SOM) contained in various density fractions was classified as: (a) free particulate OM, (b) occluded particulate OM, and (c) colloidal or clay-associated OM. The compositional differences noted among these three components of SOM were used to describe the changes that OM undergoes during decomposition when it enters the soil, is enveloped in aggregates and eventually is incorporated into microbial biomass and metabolites and associated with clay minerals. The occluded organic materials, released as a result of aggregate disruption, were in various stages of decomposition and had different degrees of association with mineral particles. Changes in the degree of association of occluded organic materials and mineral particles with decomposition are discussed and form the basis of a model which illustrates the simultaneous dynamics of microaggregates and their organic cores. This model indicates a major role for carbohydrate-rich plant debris in formation and stabilization of microaggregates.

Temporal variation in aerosol composition at summit, Greenland, summer 1989

At a high altitude site at Summit, Greenland, aerosol sulfur, chlorine, and potassium were found to occur mainly during sporadic high concentration episodes, lasting less than 24 h, over a much lowwer background level. Particle size resolved time sequence sampling was performed by automated two-stage streaker and high sensitivity elemental analysis by proton induced X-ray emission, PIXE, with a detection limit of 9 ng m −3. In a series of 165 4-h samples during one summer month in 1989, peak concentrations in the fine <2 μm diameter fraction were sometimes coincident and sometimes not, indicating different degrees of association of those elements in air masses passing over the site. Most of the S, Cl, and K was measured during the short high concentration episodes. This finding could not have been made by using a long time average sampling strategy.

Chromatin and microtubule morphology during the first cell cycle in bovine zygotes

Chromatin and microtubule configurations during the first cell cycle of bovine zygotes were analyzed by DNA staining and microtubule immunolocalization using an IVM/IVF system and oocytes matured and fertilized in vivo, in order to investigate the origin of the active centrosome and to characterize the nuclear and the cytoplasmic changes following bovine fertilization. Our results suggest that the paternal centrosome is active during early zygotic development, forming a conspicuous sperm aster soon after fertilization. We also report that polyspermy in bovine eggs, leads to the formation of numerous sperm asters with different degrees of association with the chromatin. The maternal structures in both monospermic and polyspermic zygotes can be lost or degenerate. Consequently, these cells may resume the first cell cycle as androgenotes, very often with several types of mitotic activity taking place in different regions of the cell cytoplasm at the same time. As indicated by a comparison of monospermic and polyspermic fertilization rates to rates of development, it is possible that some androgenetic embryos cleave and develop to the blastocyst stage.

Calcium-activated currents in cultured neurones from rat dorsal root ganglia.

1. Voltage-activated Ca2+ currents and caffeine (1 to 10 mM) were used to increase intracellular Ca2+ in rat cultured dorsal root ganglia (DRG) neurones. Elevation of intracellular Ca2+ resulted in activation of inward currents which were attenuated by increasing the Ca2+ buffering capacity of cells by raising the concentration of EGTA in the patch solution to 10 mM. Low and high voltage-activated Ca2+ currents gave rise to Cl- tail currents in cells loaded with CsCl patch solution. Outward Ca2+ channel currents activated at very depolarized potentials (Vc + 60 mV to + 100 mV) also activated Cl- tail currents, which were enhanced when extracellular Ca2+ was elevated from 2 mM to 4 mM. 2. The Ca(2+)-activated Cl- tail currents were identified by estimation of tail current reversal potential by use of a double pulse protocol and by sensitivity to the Cl- channel blocker 5-nitro 2-(3-phenyl-propylamino) benzoic acid (NPPB) applied at a concentration of 10 microM. 3. Cells loaded with Cs acetate patch solution and bathed in medium containing 4 mM Ca2+ also had prolonged Ca(2+)-dependent tail currents, however these smaller tail currents were insensitive to NPPB. Release of Ca2+ from intracellular stores by caffeine gave rise to sustained inward currents in cells loaded with Cs acetate. Both Ca(2+)-activated tail currents and caffeine-induced inward currents recorded from cells loaded with Cs acetate were attenuated by Tris based recording media, and had reversal potentials positive to 0 mV suggesting activity of Ca(2+)-activated cation channels.4. Our data may reflect (a) different degrees of association between Ca2+-activated channels with voltage-gated Ca2+ channels, (b) distinct relationships between channels and intracellular Ca2" stores and Ca2+ homeostatic mechanisms, (c) regulation of Ca2+-activated channels by second messengers, and (d) varying channel sensitivity to Ca2 , in the cell body of DRG neurones.