Single string based global optimizer for geometry optimization in strongly coupled finite clusters: An adaptive mutation-driven strategy.

We propose and implement a simple adaptive heuristic to optimize the geometries of clusters of point charges or ions with the ability to find the global minimum energy configurations. The approach uses random mutations of a single string encoding the geometry and accepts moves that decrease the energy. Mutation probability and mutation intensity are allowed to evolve adaptively on the basis of continuous evaluation of past explorations. The resulting algorithm has been called Completely Adaptive Random Mutation Hill Climbing method. We have implemented this method to search through the complex potential energy landscapes of parabolically confined 3D classical Coulomb clusters of hundreds or thousands of charges--usually found in high frequency discharge plasmas. The energy per particle (EN∕N) and its first and second differences, structural features, distribution of the oscillation frequencies of normal modes, etc., are analyzed as functions of confinement strength and the number of charges in the system. Certain magic numbers are identified. In order to test the feasibility of the algorithm in cluster geometry optimization on more complex energy landscapes, we have applied the algorithm for optimizing the geometries of MgO clusters, described by Coulomb-Born-Mayer potential and finding global minimum of some Lennard-Jones clusters. The convergence behavior of the algorithm compares favorably with those of other existing global optimizers.

Spectral response of 4-methyl-2,6-dicarbomethoxyphenol, an excited-state intramolecular proton-transfer probe in cyclohexane-ethanol mixtures: signatures of medium microheterogeneity.

In this paper, we explore the role of microscopic heterogeneity of the medium on the spectral response of an excited-state proton-transfer (ESIPT) probe, namely, 4-methyl-2,6-dicarbomethoxyphenol (CMOH) using steady-state and time-resolved emission spectroscopy. The mixtures of two solvents with widely different properties, viz., cyclohexane, a nonpolar, and ethanol, a polar protic solvent, were used as microheterogeneous media for spectroscopic studies. Dual fluorescence (normal and tautomer fluorescence) is observed in the nonpolar solvent (cyclohexane), while only a single peak is observed in the protic solvent, ethanol. The spectral responses of CMOH in the binary mixtures have been found to be dependent on the solvent composition and excitation wavelength. The emission spectral properties of CMOH in the cyclohexane-ethanol mixture have been seen to be superposition of spectral properties in their bulk counterparts, indicating the presence of microscopic heterogeneity in the system. A zwitterionic species of CMOH appears to have been detected in binary solvent mixtures with higher ethanol content only through low-energy excitations. The species is converted into an anionic species as excitation energy increases. Density functional theory calculations indicate that two intramolecularly hydrogen bonded rotamers of CMOH have a small energy difference. The formation of a hydrogen bonded 1:1 molecular cluster of CMOH with ethanol has been investigated in the ground state at the same level of theory. Our findings are expected to shed light on the mechanism of many acid-base reactions occurring in microscopically inhomogeneous media that often mimic many biologically relevant processes.

Coulomb explosion in dicationic noble gas clusters: a genetic algorithm-based approach to critical size estimation for the suppression of Coulomb explosion and prediction of dissociation channels.

We present a genetic algorithm based investigation of structural fragmentation in dicationic noble gas clusters, Ar(n)(+2), Kr(n)(+2), and Xe(n)(+2), where n denotes the size of the cluster. Dications are predicted to be stable above a threshold size of the cluster when positive charges are assumed to remain localized on two noble gas atoms and the Lennard-Jones potential along with bare Coulomb and ion-induced dipole interactions are taken into account for describing the potential energy surface. Our cutoff values are close to those obtained experimentally [P. Scheier and T. D. Mark, J. Chem. Phys. 11, 3056 (1987)] and theoretically [J. G. Gay and B. J. Berne, Phys. Rev. Lett. 49, 194 (1982)]. When the charges are allowed to be equally distributed over four noble gas atoms in the cluster and the nonpolarization interaction terms are allowed to remain unchanged, our method successfully identifies the size threshold for stability as well as the nature of the channels of dissociation as function of cluster size. In Ar(n)(2+), for example, fissionlike fragmentation is predicted for n=55 while for n=43, the predicted outcome is nonfission fragmentation in complete agreement with earlier work [Golberg et al., J. Chem. Phys. 100, 8277 (1994)].

Blending Determinism with Evolutionary Computing: Applications to the Calculation of the Molecular Electronic Structure of Polythiophene.

A density matrix based soft-computing solution to the quantum mechanical problem of computing the molecular electronic structure of fairly long polythiophene (PT) chains is proposed. The soft-computing solution is based on a "random mutation hill climbing" scheme which is modified by blending it with a deterministic method based on a trial single-particle density matrix [P((0))(R)] for the guessed structural parameters (R), which is allowed to evolve under a unitary transformation generated by the Hamiltonian H(R). The Hamiltonian itself changes as the geometrical parameters (R) defining the polythiophene chain undergo mutation. The scale (λ) of the transformation is optimized by making the energy [E(λ)] stationary with respect to λ. The robustness and the performance levels of variants of the algorithm are analyzed and compared with those of other derivative free methods. The method is further tested successfully with optimization of the geometry of bipolaron-doped long PT chains.

Spectral signatures of intramolecular charge transfer process in beta-enaminones: a combined experimental and theoretical analysis.

In this paper, we present spectroscopic signatures of intramolecular charge transfer (ICT) and effects of solvent on the ICT process in 3-(phenylamino)-2-cyclohexen-1-one (PACO), a member of the well-known molecular family, the beta-enaminones. The dual fluorescence in the steady state emission spectra of the molecule in polar solvents indicates the occurrence of ICT, which is further supported by time-resolved studies, using time correlated single photon counting technique with picosecond resolution. To understand the nature of the charge transfer, pH dependent studies of the probe in water were performed, where a quenching of fluorescence was observed even in the presence of very low concentrations of acids. Solvent induced fluorescence quenching was observed in ethanol and methanol. The ICT process was also investigated by quantum chemical calculations. To understand the role of solvents in the ICT process, we have theoretically studied the macroscopic and microscopic solvation of the probe in water. The absorption spectra of the molecule in the gas phase as well as in water were simulated using time dependent density functional theory with cc-pVTZ basis set and self-consistent reaction field theory that models macroscopic solvation. The possibility of microscopic solvation in water was probed theoretically and the formation of 1:3 molecular clusters by PACO with water molecules has been confirmed. Our findings could have a bearing on pH sensing applications of the probe.

A search for lowest energy structures of ZnS quantum dots: Genetic algorithm tight-binding study.

The lowest energy structures of ZnS quantum dots of different sizes have been determined by an unbiased search using genetic algorithm (GA) coupled with the density-functional tight-binding method. The GA search converges to a rather new ringlike configurations of ZnS quantum dots. We have studied the structural, electronic, and optical properties of these ringlike clusters and compared these properties with those of other reported structures of ZnS quantum dots, namely, hollow, zinc-blende, wurtzite, and rocksalt structures.

Toxic effect of environmental acid-stress on the sperm of a hill-stream fish Devario aequipinnatus: a scanning electron microscopic evaluation.

Environmental stress due to acidic pH of water was found to be one of the major factors leading to toxic effects on the sperm of a hill-stream fish Devario aequipinnatus of Meghalaya, India. The Scanning Electron Microscopy of the transverse section of testes of the fish collected from its natural habitat with acidic pH (5.6-6.0) showed that the sperms were clumped together and their tails were either absent or were of extremely small length. The acrosome and midpiece were also not well differentiated. When the fingerlings from the natural habitat were reared to maturity in aquarium with water from natural habitat after changing the pH to alkaline range (8.0-8.2), the clumping of the sperm was not observed. The sperm tail was found to be well-developed along with well-differentiated acrosome and midpiece. Since the only change in the water quality parameters of the experimental aquarium as compared to those of the natural habitat was the pH, it is evident that the abnormal features of the sperm observed in fish from natural habitat is mainly because of environmental acid stress.

Scanning electron microscopic studies on surface microstructural features of some tissues of epizootic ulcerative syndrome-affected Puntius ticto (Hamilton, 1822) from Southern Assam of India.

Epizootic ulcerative syndrome (EUS)-affected Puntius ticto exhibited a number of abnormalities in scale, gill, skin, and muscle at surface microstructural level. Lepidontal damage including breakage of individual lepidonts and complete loss of lepidontal assembly was evident in the scale. Disturbances in the gill included fusion of gill-lamella, distortion of lamellar surface, damage of primary and secondary gill lamella as well as breakage of gill racker. The skin of EUS-affected Puntius ticto showed breakage of epidermal cell boundary, distortion, and loss of alignment of cells including lesions at places. Loss of alignment of muscles along with breakage and distortion of individual fibers was also evident. The similarities of these abnormalities in EUS-affected Puntius ticto with those of pesticide and other pollutant toxicity reported in some fish is discussed with the help of relevant literature.

Effect of surfactant-perturbed nanocaging on the ground and excited state proton transfer reaction.

The effect of mixed cyclodextrin-surfactant systems on the ground and excited state proton transfer reactions of 4-methyl-2,6-diformylphenol (MFOH) in aqueous solution has been investigated by steady state and time-resolved fluorescence spectroscopy. It has been found that micellar media perturbs the solvation of MFOH and facilitates nanocaging. In the presence of micelle, MFOH preferentially resides in the interfacial region. Depending on the local pH due to compartmentalization of reaction media, normal or anionic form of MFOH dominates. Encapsulation of the probe within the cyclodextrin nanocavity enhances the shorter lifetime component of MFOH unexpectedly, which has been explained on the basis of reduced solvation and reduced dipolar effect due to confinement.

Stimulation of salmon calcitonin on secretion of 17beta-estradiol by the ovarian follicles of common carp, Cyprinus carpio.

The effects of salmon calcitonin (sCT) on the secretion of 17beta-estradiol (E(2)) were examined in female common carp, Cyprinus carpio. Vitellogenic stage fish adapted to high-Ca water were i.p. injected with vehicle, sCT, human chorionic gonadotropin (hCG), or hCG plus sCT. To determine whether ovarian follicles are equipped with CT receptors, a CT binding assay was conducted. In the in vitro experiments, vitellogenic follicles were incubated with stimulators and inhibitors. Administration of sCT increased the basal and hCG-stimulated E(2) release in vivo and in vitro. Binding characteristics of [(125)I]sCT to plasma membrane preparation of carp ovarian follicles showed saturability with high-affinity (K(d)=48.48 pmol/l and B(max)=1.2 pmol/mg protein). To clarify the mechanism of E(2) production by sCT, in vitro effect of sCT and hCG on aromatase activity (conversion of testosterone to E(2)) and cytochrome P450 aromatase (P450arom) gene expression in carp ovarian follicles were investigated. Salmon CT-stimulated both aromatase activity and P450arom gene expression in ovarian follicles of carp. sCT-stimulated E(2) release by the ovarian follicles in vitro was augmented in the presence of dibutyryl cAMP. Inhibitor of protein kinase A (PKA), SQ 22536 inhibited sCT-stimulated steroid production in a dose-dependent manner. Specific inhibitor of protein kinase C (PKC), NPC-15437 dihydrochloride had no inhibitory effects on sCT-induced E(2) release. The present study indicates that sCT binds specifically to carp ovary and stimulates E(2) production by increasing the activity of cytochrome P450 aromatase and P450arom gene expression. The results further suggest that stimulatory action of sCT on E(2) production is mediated through cAMP pathway.

Instability and pattern formation in reaction-diffusion systems: a higher order analysis.

We analyze the condition for instability and pattern formation in reaction-diffusion systems beyond the usual linear regime. The approach is based on taking into account perturbations of higher orders. Our analysis reveals that nonlinearity present in the system can be instrumental in determining the stability of a system, even to the extent of destabilizing one in a linearly stable parameter regime. The analysis is also successful to account for the observed effect of additive noise in modifying the instability threshold of a system. The analytical study is corroborated by numerical simulation in a standard reaction-diffusion system.

In vitro effects of insulin-like growth factors and insulin on oocyte maturation and maturation-inducing steroid production in ovarian follicles of common carp, Cyprinus carpio.

In vitro germinal vesicle breakdown (GVBD) in Cyprinus carpio oocytes was induced by recombinant human insulin-like growth factor-I and -II (IGF-I and IGF-II) and bovine insulin (b-insulin). Treatment of postvitellogenic ovarian follicles with IGF-I and b-insulin increased concentration of maturation-inducing hormone (MIH), 17alpha,20beta-dihydroxy-4-pregnane-3-one (DHP) in the medium. IGF-I and IGF-II both and b-insulin induced GVBD in denuded oocytes. IGF-I analogue R3 IGF-I was more potent than IGF-I in inducing GVBD of postvitellogenic follicles suggesting that ovarian IGF binding proteins may inhibit IGF-I action. Vitellogenic follicles, which were immature for oocytes to complete GVBD in response to DHP or HCG, underwent GVBD by IGF-I, not by b-insulin. IGF-I was also able to stimulate DHP production in such follicles. Addition of DHP and HCG to the culture of vitellogenic follicles containing IGF-I or b-insulin did neither potentiate the stimulation of GVBD induced by IGF-I nor initiate the same in response to b-insulin. Incubation of postvitellogenic follicles with trilostane (3beta-HSD inhibitor) had no inhibitory effects on IGF-I- and b-insulin-induced GVBD but attenuated the same under HCG stimulation. Trilostane, however, strongly inhibited DHP production induced by all these effectors. Induction of GVBD by IGF-I and b-insulin was not altered in the presence of actinomycin D. However, it significantly blocked the HCG-induced GVBD. Cycloheximide was shown to inhibit the induction of GVBD and DHP production by IGF-I, b-insulin and HCG. Both actinomycin D and cycloheximide were found to inhibit DHP production stimulated by all the three effectors. Collectively, these observations indicate that IGF-I and b-insulin can induce GVBD via MIH- and transcription-independent pathway. Incubation of the follicles with gap junction uncouplers, 1-heptanol or 1-octanol, had no effect on IGF-I- and b-insulin-induced GVBD, but attenuated the same induced by HCG. These uncouplers, however, inhibited DHP production induced by IGF-I, b-insulin and HCG. This result suggests that both IGF-I and b-insulin can induce oocyte maturation without coupled gap junction between oocytes and granulosa cells, while homologous gap junctions are required for DHP production. Inhibitors of phosphatidylinositol-3 kinase (PI-3 kinase), wortmannin and LY294002 inhibited GVBD by IGF-I and b-insulin. These two inhibitors also attenuated HCG-induced GVBD. These data suggest that PI-3 kinase activity is required for IGF-I, b-insulin and HCG induction of GVBD in C. carpio.

The effects of calcitonin on plasma calcium levels and bone metabolism in the fresh water teleost Channa punctatus.

Administration of salmon calcitonin (sCT) caused significant reduction in total and ultrafiltrable plasma calcium content in the plasma of a fresh water female teleost Channa punctatus. A time-bound analysis on the effect of sCT showed a highly significant short duration reduction in total and ultrafiltrable plasma calcium content in fish kept in normal tap water and low-calcium water and a moderate hypocalcemia in fish kept in high-calcium water. Sexually immature adult fish showed a greater response than the sexually mature ones. Using tartrate-resistant acid phosphatase (TRACP) and alkaline phosphatase (ALP) activities in plasma and hydroxyproline (HYP) excretion in urine, the effect of sCT on the inhibition of bone calcium resorption were examined. In both sexually mature and immature adult fish, kept in normal tap water, sCT significantly suppressed TRACP and ALP activities in plasma and excretion of HYP in urine within 2-6 h with a maximum at 4 h after injection. Salmon CT treatment to sexually immature adult fish caused significant increase in skeletal bone calcium concentration. Taken together, all this information indicates that CT in a fresh water female teleost is an effective regulator of plasma calcium levels, and its action, at least in part, operates through inhibition of bone calcium resorption.

Interaction between methyl glyoxal and ascorbic acid: experimental and theoretical aspects.

The absorption spectral change of methyl glyoxal (MG) due to the interaction with ascorbic acid (AA or Vitamin C) has been investigated using steady-state spectroscopic technique. A plausible explanation for the spectral change has been discussed on the basis of hydrogen bonding interaction between the two interacting species. The equilibrium constant for the complex formation due to hydrogen bonding interaction between MG and AA has been obtained from absorption spectral changes. Ab inito calculations with DFT B3LYP/6/31G (d,p) basis sets have been used to find out the molecular structure of the hydrogen bonded complex. The O...H distance found in the O-H...O hydrogen bond turns out to be quite short (1.974 A) which is in conformity with the large value of the equilibrium constant determined experimentally.

Inhibition of whole body Ca2+ uptake in fresh water teleosts, Channa punctatus and Cyprinus carpio in response to salmon calcitonin.

In many fish, ultimobranchial-derived calcitonin (CT) has been shown to be a potent hypocalcemic regulator. But an equal number of studies failed to show any correlation between CT and plasma calcium levels. Again, in fish, where CT has been shown to function as a hypocalcemic hormone, the way this is brought about is not well known. While the regulatory role of many hormones e.g., stanniocalcin, pituitary-derived prolactin and cortisol on gill calcium (Ca2+) transport (GCAT) has been well established, very few studies have been done to examine the effects of CT on GCAT in fish. In the present study we examined the effects of synthetic salmon calcitonin (sCT) in vivo on GCAT in two distinctly different species of fresh water teleost, Channa punctatus (partially air breathing) and Cyprinus carpio (fully gill breathing). Whole body calcium uptake, a measure of GCAT, was lower in the partial air breathing fish. We found that salmon CT had significant inhibitory effect on GCAT in both the fish species, kept either in normal tap water or low-calcium water. Fish, kept in high-calcium water, showed little response. In parallel studies we also observed that inhibition of GCAT was correlated with simultaneous changes in plasma calcium levels in response to exogenous administration of sCT. The present findings therefore suggest that CT in fresh water teleosts regulate its hypocalcemic action through inhibition of GCAT.

Seasonal changes in plasma steroid levels in Indian major carp Labeo rohita: influence of homologous pituitary extract on steroid production and development of oocyte maturational competence.

Circannual variations in plasma levels of testosterone (T), 17beta-estradiol (E(2)), and 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (DHP) as well as seasonal fluctuations in ovarian steroid synthetic potential were observed in Indian major carp, Labeo rohita. A study was also conducted to examine the mechanism of the development of gonadotropin-induced maturational competence in oocytes of this fish. The present study recorded the lowest values of plasma E(2) and T in L. rohita during the period from October to January. A mild increase in the levels of these steroids observed in February was followed by their rapid rise reaching peak values in April, when the ovary contained mostly the vitellogenic follicles. In the month of May, as the postvitellogenic follicles predominated in the ovary, there was a decline in plasma concentrations of both T and E(2). Low levels of these steroids in plasma remained until January, except a small elevation detectable during June and July (spawning stage). DHP was not detected in the plasma of this fish collected during the period from August to March. Existence of DHP was first recorded in blood in the month of April (vitellogenic stage) and it quickly reached the peak value in May (postvitellogenic stage), followed by a sudden decline in the month of June. Under stimulation of fish pituitary extract (FPE), as a source of gonadotropin, in vitro production of E(2) and T by the vitellogenic follicles was shown to be highest compared to their production rate in other stages, while the postvitellogenic follicles recorded the highest rate of DHP synthesis. Acquisition of oocyte maturational competence (OMC) was shown to develop either by priming the vitellogenic stage fish with a single dose of FPE or by in vitro addition of FPE in culture. In vitro treatment of trilostane, an inhibitor of 3beta-HSD, blocked the FPE-stimulated steroid production but not the development of OMC. Presence of cycloheximide and actinomycin D in the incubation was shown to inhibit FPE-induced development of OMC, indicating the requirement of de novo protein synthesis for this process.

Ubiquitination of Lyn-kinase in rat basophilic leukemia RBL-2H3 cells.

Receptor-mediated signal transduction pathways of cells involved in allergy and inflammations are extremely significant. Lyn is a member of the Src family of non-receptor protein tyrosine kinases and is associated with a number of cell surface receptors, including the B-cell antigen receptor and immunoglobulin E receptor (FcepsilonRI). Lyn is necessary for FcepsilonRI-mediated mast cell activation. To investigate how the level of Lyn is maintained in mast cell activation, it was studied whether Lyn binds to ubiquitin and is ubiquitinated for proteasomal degradation in cells. In the yeast two hybrid system, Lyn specifically interacted with ubiquitin in vivo. Furthermore, Lyn bound to ubiquitin-conjugated Sepharose beads in vitro and was efficiently competed by soluble ubiquitin. Pulse-chase experiments indicated intracellular degradation of Lyn was associated with the generation of a high molecular weight complex in the presence of proteasome-specific inhibitor, lactacystin. This high molecular weight complex cross-reacted with anti-Lyn and anti-ubiquitin demonstrating the ubiquitination Lyn. Overexpression of Lyn and ubiquitin in COS 7.2 cells also resulted in the ubiquitination of Lyn in the presence of lactacystin, supporting the ubiquitination of Lyn by a proteasome specific pathway.

Identification of maturation-inducing steroid in a freshwater perch Anabas testudineus and differential responses of intact follicles and denuded oocytes to cyclic AMP in oocyte maturation.

Postvitellogenic follicles of freshwater perch Anabas testudineus incubated with [(3)H]pregnenolone as exogenous precursor produced several metabolites, including 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (DHP) and 5 beta-pregnane-3 alpha, 17 alpha,20 beta-triol (5 beta-3 alpha,17 alpha,20 beta-P). These were identified by chromatography, microchemical reactions, and crystallization to constant specific activity. Following stimulation with fish (perch) pituitary extract (FPE) there was significant high production of DHP and 5 beta-3 alpha,17 alpha,20 beta-P, concomitant with a high percentage of germinal vesicle breakdown (GVBD). Inhibitor of steroidogenesis (trilostane) and inhibitors of protein synthesis (cycloheximide and actinomycin-D) completely blocked FPE-induced pregnenolone metabolism and oocyte maturation. The effectiveness of various C(21) steroids in inducing GVBD was examined. Results indicate that DHP was the most potent inducer of GVBD than other structurally related C(21) steroids. In intact follicles, FPE-stimulated production of DHP was shown to be mediated through the adenylate cyclase-cAMP pathway. Addition of IBMX or forskolin, which increases the endogenous cAMP level, as well as directly supplementing dbcAMP to the incubation medium, had no inhibitory effect on DHP-induced GVBD in the intact follicles. But all these agents were shown to inhibit GVBD in fully denuded oocytes. This study provides evidence that DHP, produced by postvitellogenic follicles through the adenylate cyclase-cAMP pathway, is the maturation-inducing steroid in freshwater perch and that the role played by cAMP in the induction of GVBD in intact follicles is different from that in the denuded oocytes. J. Exp. Zool. 287:294-303, 2000.

Both adhesion to immobilized vitronectin and FcepsilonRI cross-linking cause enhanced focal adhesion kinase phosphorylation in murine mast cells.

Murine mast cells adhere spontaneously to plate-bound vitronectin (VNPB) via alphav-containing integrins, and this adhesive interaction results in an augmented interleukin-3 (IL-3)-dependent mast-cell proliferation. In this report we demonstrate that the activation of murine mast cells through alphav-integrin, as well as through the high affinity immunoglobulin E (IgE) receptor (FcepsilonRI), results in enhanced tyrosine phosphorylation of focal adhesion kinase (FAK), a cytoplasmic protein tyrosine kinase involved in mitogenic and oncogenic signal transduction. While mast cell adhesion to VNPB resulted in enhanced FAK phosphorylation, treatment with soluble vitronectin (VNSOL) failed to do so. Spontaneous mast cell adhesion to entactin (EN) did not induce tyrosine phosphorylation of FAK, demonstrating that not all adhesive interactions lead to the same sequence of biochemical events. Because FAK has intrinsic tyrosine kinase activity, we examined whether activating mast cells via alphav-integrins, or via FcepsilonRI-cross-linking stimulated the in vitro kinase activity of FAK. Both pathways were found independently to activate FAK in mast cells and together appeared additive. Protein kinase C depletion in mast cells and calcium depletion in the medium caused decreased tyrosine phosphorylation of FAK, indicating that optimal tyrosine phosphorylation of FAK is regulated by both pathways. These data are consistent with the conclusion that the tyrosine phosphorylation of FAK represents at least one example of a point of convergence in the intracellular tyrosine phosphorylation cascades induced by alphav integrin-and FcepsilonRI-mediated signal transduction pathways in mast cells.

Influence of fowl uropygial gland and its secretory lipid components on the growth of skin surface fungi of fowl.

Fungal species, which were shown to colonize consistently on the skin surface of the breast region of adult (1 year old) white leghorn fowl, were identified as Aspergillus sydowii, A. tamarii, A. rugulosus and Absidia corymbifera. Of these, A. sydowii and A. tamarii were the dominant forms. Two species of fungi, namely, Aspergillus niger and Scopulariopsis brevicaulis were shown to be present in the cultures of the scrubbings from breast skin surface after 60 days of captivity of the fowls. Extirpation of the uropygial gland resulted in encouragement of the in vitro population growth of all species of fungi except that of A. rugulosus. The effect was found to be very conspicuous for A. sydowii and A. tamarii, particularly after 60 days of gland removal. Addition of total lipids and the wax diester component of free-flowing uropygial secretion as 0.2% suspension in Sabouraud's agar medium of individual fungal isolates caused marked suppression of the population growth of A. sydowii, A. tamarii, Absidia corymbifera and to some extent of S. brevicaulis. Other components of secretory lipids, such as wax alcohols (2,3-alkane-diols), wax acids, triglycerides and hydrocarbons (including squalene) when supplemented separately to culture medium of individual fungi at identical concentration, were also shown to cause inhibition of the growth of most of fungal species at different degrees.