Interaction between the tachinid parasite,Sturmiopsis inferens and granulosis virus in the sugarcane shoot borer,Chilo infuscatellus [Lep.: Crambidae]

Competition between granulosis virus (GV) and the larval parasite,Sturmiopsis inferens Tns. (Tachinidae: Diptera), was studied in 3^rd — and 4^th — instar larvae of the sugarcane shoot borer,Chilo infuscatellus Snellen (Crambidae: Lepidoptera), under laboratory conditions. Mortality due to GV infection and parasitization was 76.8 and 47.6 per cent, respectively, when they were tested separately. But when hosts were infected simultaneously with microfeeding of GV and larval parasite, a significantly low parasitism (5.5%) was obtained compared to 74.8 per cent mortality by GV infection. When the larvae were microfed with the GV 6 days after inoculation with parasitic maggots, mortality due to the virus was reduced significantly to 20.5 per cent, but when the maggot inoculation was preceded by virus microfeeding 6 days before, parasitization was unsuccessful, while 75% of larvae died of virus. Results obtained from field — collected larvae also showed that significantly more parasite puparia were recovered from healthy larvae than from virus — infected larvae. Similar differences in parasitization were not obtained in the case of healthy or virus — infected pupae.      

Use of Iodo-Gen and Iodine-125 to label the outer membrane proteins of whole cells of Neisseria gonorrhoeae

The outer membrane proteins of Neisseria gonorrhoeae are specifically labeled by use of 1,3,4,6-tetrachloro-3α,6α-diphenyl glycoluril (Iodo-Gen) and ¹²⁵I under the conditions described in this report. Use of this procedure with whole cells of N. gonorrhoeae produces a clear labeling pattern which can be visualized by electrophoretic separation of the proteins, followed by autoradiography. Electrophoretograms reveal some 70 polypeptide bands, while autoradiograms reveal only 5 or 6 labeled bands. The labeled polypeptide bands correspond to isolated outer membrane proteins, the most intensely labeled of which is the principal outer membrane protein. The method described in this report is both specific and gentle, as well as rapid and convenient.     

A Comparison of the Efficacy of Nuclear Polyhedrosis and Granulosis Viruses in Spray and Bait Formulations for the Control of Agrotis segetum (Lepidoptera: Noctuidae) in Maize

Agrotis segetum nuclear polyhedrosis virus (AsNPV) and granulosis virus (AsGV), propagated in laboratory cultures of A. segetum in England and A. ipsilon in Spain, respectively, were applied to plots of maize plants at the one‐ to four‐leaf stage of growth. Plots were arranged in a 6 x 6 Latin square design and infested with second‐instar A. segetum larvae (the common cutworm). Each virus was applied in separate treatments by two application methods; as an aqueous spray containing 0.1% Agral as a wetting agent, and as a bran bait. The NPV was applied at a rate of 4 X 10¹² polyhedra/ha, and the GV at 4 X 10¹³ granules/ha. Soil and plants were sampled for larvae on three occasions following virus treatment: 24 h, 4 days and 11 days. The larvae were reared on diet in the laboratory, until death or pupation, to examine the rate and level of viral infection. Infection data showed 87.5% and 91% NPV infection and 12.5% and 55% GV infection in spray and bait treatments, respectively, in larvae sampled 24 h after treatment. In larvae sampled 4 days after treatment, the results were 78% and 100% NPV infection, and 13% and 6% GV infection. A total of only six larvae were retrieved on day 11. In both treatments larvae infected with AsNPV died significantly more rapidly and at an earlier instar than those infected with AsGV, indicating that AsNPV appears to have better potential as a control agent for A. segetum.     

Decreased regulatory T‐cells and CD4+/CD8+ ratio correlate with disease onset and progression in patients with generalized vitiligo

The aim of present study was to evaluate CD4⁺/CD8⁺ ratio and CD4⁺CD25^hiFoxP3⁺ Tregs in GV patients with reference to their effect on disease onset and progression. Flow cytometry was used for determination of CD4⁺/CD8⁺ ratio and Tregs in 82 patients and 50 controls. CD8⁺ T‐cell counts were significantly higher in GV patients as compared with controls (p = 0.003). Active GV patients showed higher CD8⁺ T‐cell counts compared with stable GV patients (p = 0.001). The CD4⁺/CD8⁺ ratio decreased significantly in patients as compared with controls (p = 0.001). Moreover, the ratio in active GV patients significantly lowered as compared with stable GV patients (p = 0.002). Significant decrease in Treg cell percentage and counts in GV patients was observed compared with controls (p = 0.009, p = 0.008) with significant reduction in FoxP3 expression (p = 0.024). Treg cell percentage and counts were significantly decreased in active GV patients compared with stable GV patients (p = 0.007, p = 0.002). Our results suggest that an imbalance of CD4⁺/CD8⁺ ratio and natural Tregs in frequency and function might be involved in the T‐cell mediated pathogenesis of GV and its progression.     

Production and field evaluation of codling moth granulosis virus for control of Cydia pomonella in the United Kingdom

Codling moth granulosis virus (Cp GV) was produced in larvae of Cydia pomonella reared on artificial diet. The average yield of virus (9 × 10⁹capsules/larva) was increased by raising the larvae on diet containing methoprene, a juvenile hormone analogue. In field trials in 1978 and 1979, one or two high-volume applications of Cp GV at 7 × 10¹⁰ capsules/litre achieved reductions in numbers of mature larvae and damaged fruit that were little different from those obtained by two applications of azinphos-methyl. A field trial in 1980 showed that at concentrations of Cp GV ≥ 6 × 10⁸ capsules/litre, damaged diminished slowly with increasing virus concentration. Following virus application in 1980, Cp GV infectivity was reduced by half in 3 days, but some activity persisted at least 4–8 wk after spraying. The results indicate that codling moth GV is an effective control agent particularly in reducing numbers of larvae and the more severe forms of fruit damage.     

In vitro and in vivo survival of frozen-thawed bovine oocytes after IVF,nuclear transfer,and parthenogenetic activation

Cryopreservation of bovine oocytes would be beneficial both for nuclear transfer and for preservation efforts. The overall objective of this study was to evaluate the viability as well as the cryodamage to the nucleus vs. cytoplasm of bovine oocytes following freezing-thawing of oocytes at immature (GV) and matured (MII) stages using in vitro fertilization (IVF), parthenogenetic activation, or nuclear transfer assays. Oocytes were collected from slaughterhouse ovaries. Oocytes at the GV, MII, or MII but enucleated (MIIe) stages were cryopreserved in 5% (v/v) ethylene glycol; 6% (v/v) 1,2-propanediol; and 0.1-M sucrose in PBS supplemented with 20% (v/v) fetal bovine serum. Frozen-thawed oocytes were subjected to IVF, parthenogenetic activation, or nuclear transfer assays. Significantly fewer GV oocytes survived (i.e., remained morphologically intact during freezing-thawing) than did MII oocytes (47% vs. 84%). Subsequent development of the surviving frozen-thawed GV and MII oocytes was not different (58% and 60% cleavage development; 7% and 12% blastocyst development at Day 9, respectively, P > 0.05). Parthenogenetic activation of frozen-thawed oocytes resulted in significantly lower rates of blastocyst development for the GV than the MII oocyte groups (1% vs. 14%). Nuclear transfer with cytoplasts derived from frozen-thawed GV, MII, MIIe, and fresh-MII control oocytes resulted in 5%, 16%, 14%, and 17% blastocyst development, respectively. However, results of preliminary embryo transfer trials showed that fewer pregnancies were produced from cloned embryos derived from frozen oocytes or cytoplasts (9%, n = 11 embryos) than from fresh ones (19%, n = 21 embryos). Transfer of embryos derived by IVF from cryopreserved GV and MII oocytes also resulted in term development of calves. Our results showed that both GV and MII oocytes could survive freezing and were capable of developing into offspring following IVF or nuclear transfer. However, blastocyst development of frozen-thawed oocytes remains poorer than that of fresh oocytes, and our nuclear transfer assay suggests that this poorer development was likely caused by cryodamage to the oocyte cytoplasm as well as to the nucleus. Mol. Reprod. Dev. 51:281–286, 1998. © 1998 Wiley-Liss, Inc.     

Under-replication of intron+ rDNA cistrons in polyploid nurse cell nuclei of Calliphora erythrocephala

We have examined the possibility that the intron-containing (intron⁺) rDNA cistrons of Dipteran flies are active in the germ-line derived polyploid nurse cell nuclei of the ovarian follicles. Using the organism, Calliphora erythrocephala, we describe here a procedure which yields very pure nurse cell nuclei and compare the intron-free (intron^–) and intron⁺ rDNA cistron contents of nurse cell nuclei prepared by this procedure to those of 2–18 h embryo nuclei and 3 day pupal nuclei. DNA from three preparations of each nuclear type was examined and the intron^– and intron⁺ cistron contents quantitated using a Southern transfer procedure. The number of intron^– and intron⁺ rDNA cistrons per haploid genome in the presumed diploid 2–18 h embryo DNA was first established, and then the intron^– and intron⁺ cistron contents of nurse cell nuclear DNA and 3 day pupal DNA were determined relative to these values.The intron^– cistron content of nurse cell nuclear DNA was indistinguishable from that of embryonic DNA but the intron⁺ cistrons showed an 8-fold under-replication relative to the presumed diploid DNA. A slight under-representation of the intron^– cistrons and 3-fold under-replication of the intron⁺ cistrons were demonstrated for 3 day pupal DNA. These findings strongly suggest that intron⁺ rDNA cistrons are non-functional in nurse cell nuclei and substantiate the generality of this implication for the whole organism during early pupal life.     

Protein synthesis in neurons and glial cells of the developing rat brain: an in vivo study

Abstract— A technique for the isolation of pure neuronal perikarya and intact glial cells from cerebral cortex has been developed for routine use. The yield of neuronal perikarya and glial cells was greater from highly immature (5–10 days) rat cerebral cortex than from the cortex of older rats (18–43 days). The perikarya/glia yield ratio decreased with age indicating that, as the glial population matured, the procedure succeeded in isolating a gradually smaller proportion of the existing neurons. The perikarya/glia ratio was highest for the 5-day-old cortex in which no mature glial cells could be identified. After a 10-min pulse in vivo of intrathecally injected [¹⁴C]phenylalanine, the specific radioactivity of the neuronal proteins was higher than that of the glial proteins in the 5-, 10- and 18-day-old rat but was lower in the 43-day-old rat. The values for absolute specific radioactivity of the ¹⁴C-labelled proteins in both cell types were greater, the younger the brain. The ¹⁴C-labelling of neuronal and glial proteins in the 18-day-old rat was assessed in vivo as a function of time by determining the incorporation of [¹⁴C]phenylalanine into such proteins at 5, 10, 20 and 45 min after administration of the amino acid. The rate of incorporation of [¹⁴C]phenylalanine into the glial cells was faster than into the neurons since higher specific radioactivities of the glial proteins could be achieved at earlier times. Also, a biphasic pattern of ¹⁴C-labelling of the glial proteins was noted, suggesting, perhaps, a sequential involvement of the oligodendrocytes and astrocytes. Homogenates of prelabelled neuronal perikarya were fractionated into the nuclear, mitochondrial microsomal and soluble cell sap fractions. In the 18-day-old cerebral cortex, the proteins of the microsomal fraction exhibited the highest specific radioactivity at the end of 10 min, whereas by 20 min proteins of the mitochondrial fraction were most highly labelled. The specific radioactivity of the nuclear proteins increased over the entire 45-min experimental period. On the contrary, the proteins of the soluble cell sap, in which the specific radioactivity was at all times by far the lowest, were maximally labelled by 5 min. Examination of the labelling of the neuronal subcellular fractions as a function of age revealed that at 10 min after administration of [¹⁴C]phenylalanine, the specific radioactivities of all ¹⁴C-labelled proteins were highest in the youngest (5-day-old) neurons. The proteins of the microsomal fraction were most rapidly labelled at all ages. During this interval the proteins of the soluble cell sap were only moderately labelled in the 5-day-old neurons and were totally unlabelled in the 43-day-old neurons, indicating age-dependent differences in the rate of utilization of the amino acid precursor by the neurons.     

Susceptibility of Phthorimaea operculella Zeller (Lepidoptera; Gelechiidae) to its granulovirus PoGV with larval age

1 Granulovirus PoGV is a strong candidate to substitute for chemical insecticides in integrated pest management (IPM) of the potato tuber moth Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae). Generally, susceptibility to baculoviruses decreases with increasing larval age. For effective field applications, knowledge of the age‐related change in susceptibility is crucial. 2 The relative susceptibility of various instars of P. operculella larvae to PoGV was studied by leaf‐disc bioassays in the laboratory at 26 °C incubation temperature. The LC₅₀ increased from 4 × 10⁶ granules/mL for neonate larvae to 1.2 × 10⁷, 1.1 × 10⁸, 4.4 × 10⁸, and 4.2 × 10⁹ granules/mL, signifying resistance ratios of 3, 29, 110, and 1051, for 5, 6, 7, and 9‐day‐old larvae, respectively. 3 The relationship between log‐LC₅₀ values and log‐larval weight was significantly linear. A logistic function described significantly the relation between larval weights and physiological age measured in degree‐days (DD > 13.4 °C). Both functions allowed prediction of the activity ratio of PoGV for different larval ages by using temperature summation to express physiological age. 4 PoGV was found to be highly active against P. operculella larvae up to a physiological age of approximately 50 DD (>13.4 °C) (i.e. the first third of the total larval development time). Thereafter, the virus rapidly lost its activity against older larvae. Prospects for applying this knowledge in the field are discussed.     

Cell cycle-related transfer of proteins between the nucleus and cytoplasm of Physarum polycephalum

The proteins of wild-type and polyploid plasmodia of P. polycephalum were prelabelled with [³H]leucine and [¹⁴C]leucine. The two types of plasmodia were then fused for 2 h. Following fusion the nuclei were isolated and the smaller wild-type cell nuclei separated from the larger polyploid cell nuclei. The proteins were isolated from the recipient cell nuclei and the recipient nuclear proteins extracted. Ratios of ³H/¹⁴C in the various nuclear protein fractions show that during fusion differential transfer of labelled preformed proteins from the donor cell into the recipient cell nucleus occurs. The quantity of proteins transferred varies among the different fractions and with the phase of the cell cycle. Isotopic dilution experiments indicate that these differences in protein transfer are, in part, due to a high rate of synthesis and turnover of the nuclear proteins.     

Affinity chromatography of estrogen- and progesterone-binding proteins of human uterus

The purification of estrogen- and progesterone-binding proteins of human uterus by employing affinity resins coupled with steroid-bovine serum albumin conjugates, led to the isolation of preparations with estrogen- and progesterone-binding sites havingK _d values in the range of 0.96 to 1.20 × 10^-9 M. These were different from theK _d values of 10^-10 M and 10^-8 M obtained for two types of binding sites present in the crude cytosolic and nuclear fractions. The purified proteins sedimented on sucrose gradient withS values in the range of 3.6–4.4. The cytosolic and nuclear estrogen- and progesterone-binding proteins, thus purified, showed differences in specificity of binding to the hormone. While the cytoplasmic proteins were more specific in their binding to estradiol or progesterone, the nuclear proteins bound Cortisol with equal or moderate affnity. These results demonstrate the presence of distinct physiological forms of estrogen- and progesterone-binding proteins in the cytoplasm and nucleus, thus pointing to the importance of both these compartments in hormone action.     

Properties of a 110000 molecular weight protein in rat liver hnRNP particles

Particles carrying heterogeneous nuclear RNA (30–40 S-particles) were isolated from rat liver nuclei and the particle proteins separated by sodium dodecylsulfate gel electrophoresis. Some properties of a 110000 molecular weight component (P 110/103) were studied in detail: (i) P 110/103 was labeled to a 4–5 times higher specific activity than the major particle proteins in the presence of [¹⁴C]-amino acidsin vivo. (ii) In nuclei incubated with [³H]- or [³²P]-nicotinamide adenine dinucleotide P 110/103 was labeled presumably by ADP-ribosylation. (iii) A protein with the same molecular weight as P 110/103 and isolated from the nuclear extract by affinity chromatography was phosphorylated in vitro.Abbreviations hnRNA heterogeneous nuclear RNA - hnRNP and mRNP ribonucleoproteins which contain hnRNA respectively mRNA     

Transfection and transformation of Agrobacterium tumefaciens.

Summary The freeze thaw transfection procedure of Dityatkin et al. (1972) was adapted for the transfection and transformation of A. tumefaciens. Transfection of the strains B6S3 and B6-6 with DNA of the temperate phage PS8cc186 yielded a maximum frequency of 2 10^-7 transfectants per total recipient population. In transformation of the strain GV3100 with the P type plasmid RP4 a maximum frequency of 3.5 10^-7 transformants per total recipient population was obtained. Agrobacterium Ti-plasmids were introduced in the strain GV3100 with a maximal efficiency of 4.5 10^-8. These experiments provide further evidence that the Ti-plasmid is responsible for the oncogenic properties of A tumefaciens and for its capacity to induce opine synthesis in Crown-gall plant cells.     

Specific immunological response against the granulosis virus of the codling moth (Cydia pomonella) in woodmice (Apodemus sylvaticus): field observations

Antibodies specific to the granulosis virus (GV) of the codling moth (Cydia pomonella) were detected by indirect ELISA in sera of woodmice (Apodemus sylvaticus) trapped in an apple orchard sprayed by tractor-drawn mist blower with 2 × 10¹³ virus granules C. pomonella GV/ha. Such antibodies were absent from sera of mice trapped before virus had been applied. Virus antigens were detected by double antibody sandwich ELISA on the ground in and around the orchard and also in the faeces of woodmice inhabiting the orchard, but did not persist from one year to another. Some, but not all, of the samples containing virus antigens were found to be infective.     

Application of a novel radioimmunoassay to identify baculovirus structural proteins that share interspecies antigenic determinants

Immunological comparisons were made of baculovirus structural proteins by using a modification of the radioimmunological techniques described by Renart et al. (Proc. Natl. Acad. Sci. U.S.A. 76: 3116-3120, 1979) and Towbin et al. (Proc. Natl. Acad. Sci. U.S.A. 76: 4350-4354, 1979). Viral proteins were electrophoresed in polyacrylamide gels, transferred to nitrocellulose, and incubated with viral antisera, and the antibodies were detected with ¹²⁵I-labeled Staphylococcus aureus protein A. Antisera were prepared to purified and intact virions from five baculoviruses: Autographa californica, Porthetria dispar, Trichoplusia ni, and Heliothis zea nuclear polyhedrosis viruses (NPVs) and T. ni granulosis virus (GV). These antisera were tested against the virion structural polypeptides of 17 different species of baculoviruses. Specific multiple-nucleocapsid NPV (MNPV), single-nucleocapsid NPV (SNPV), and GV virion polypeptides were shown to have similar antigenic determinants and thus be immunologically related. The molecular weights of the virion polypeptides with cross-reacting antigenic determinants were identified. Antisera prepared to purified A. californica and H. zea MNPV polyhedrin (the occlusion body protein from NPVs) recognized antigenic determinants on all the polyhedrins and granulins (occlusion body protein from GVs) that were tested. No immunological relationship was detected between A. californica MNPV polyhedrin and any of the A. californica MNPV virion structural polypeptides present on either the virus isolated from occlusion bodies or A. californica MNPV extracellular virus from infected-cell cultures.     

An improved method to determine the biological activity (LC50) of the granulovirus PoGV in its host Phthorimaea operculella

Granulovirus (PoGV) is a promising candidate to substitute for chemical insecticides in integrated pest management (IPM) of the potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae). A procedure to assess pathogenicity (LC₅₀) and its standardization is crucial for research into the use of pathogens as biocontrol agents. In the present study, an egg‐dip bioassay method was developed and its precision tested in a series of six bioassays over a time period of 18 months. Bioassays were carried out at 25 °C incubation temperature. The probit model as a statistical analysis method for the interpretation of concentration responses proved better than the exponential model. LC₅₀ values ranged from 2.3 × 10⁶ to 10⁷ granules ml^?1 with a mean of 5 × 10⁶ granules ml^?1 and regression slopes varied between 0.73 and 1.05 with a mean of 0.84. LC₅₀ values and slopes displayed no significant differences according to their 95% confidence limits. The rate of harvested infected larvae showed a linear increase with increasing concentration on a log‐log scale. The mean natural mortality was 15% (SE ± 1.8%) and can be considered as a main factor producing variability among bioassays. The advantages of this bioassay method and its application in PoGV research are discussed.     

<Emphasis Type="Italic">Le</Emphasis>RALF,a plant peptide that regulates root growth and development,specifically binds to 25 and 120 kDa cell surface membrane proteins of <Emphasis Type="Italic">Lycopersicon peruvianum</Emphasis>

A photoaffinity analog of tomato leaf RALF peptide (LeRALF), ¹²⁵I-azido-LeRALF, bound saturably to tomato suspension cultured cells in the dark in a classical receptor binding assay. Classical kinetic analyses revealed that the analog interacted with a single binding site on the surface of the cells with a K_D of 0.8×10^–9 M, typical of known peptide hormone–receptor interactions in both plants and animals. The ¹²⁵I-azido-LeRALF, when exposed to UVB light in the presence of the cells, strongly labeled only two proteins of 25 kDa and 120 kDa, with the 25 kDa protein being more strongly labeled than the 120 kDa protein. The cell-surface localization of the interaction was indicated, as suramin, a known inhibitor of peptide–receptor interactions, and native LeRALF peptide competed with ¹²⁵I-azido-LeRALF labeling of both proteins. Two biologically inactive LeRALF analogs were not competitors. Incubation of ¹²⁵I-azido-LeRALF with suspension cultured cells in the dark, where it was fully active, could subsequently be totally dissociated from cells by acid washes, indicating that it was interacting at the cell surface and was not internalized. The ¹²⁵I-azido-LeRALF-labeled 25 kDa and 120 kDa proteins could not be solubilized from cell membranes by methods that release peripheral proteins, indicating that they are integral membrane components. The cumulative kinetic and biochemical evidence strongly indicates that the two proteins may be components of a LeRALF receptor complex.     

The isolation of functional pole cells from theDrosophila melanogaster maternal effect mutantmat(3)1

Summary A procedure for pole cell isolation has been developed that takes advantage of theDrosophila melanogaster maternal effect mutantmat(3) 1. Embryos derived from homozygousmat(3)1 mothers form exclusively pole cells. By outcrossing we could substantially increase the expressivity of the original mutant stock. We further introduced theTM8 balancer chromosome, which carries the dominant temperature sensitive mutationDTS-4. This allows the accumulation of large homozygousmat(3) 1 fly populations by eliminating the heterozygous flies at the restrictive temperature.Early embryos were mechanically fragmented and the cells were isolated by means of metrizamide step gradients. The isolated cells were demonstrated to exhibit the various ultrastructural and histochemical characteristics of pole cells. The isolated cells were transplanted into genetically marked host embryos. The germ line mosaics that were obtained indicate that the isolated cells represent functional pole cells.Proteins synthesized by the isolated pole cells during short term in vitro labelling with³⁵S-methionine were compared to the proteins synthesized by blastoderm cells fromOregon-R embryos. At least one protein could be demonstrated in the pole cell samples that is not synthesized byOregon-R blastoderm cells.The method allows a fast and gentle isolation of highly enriched pole cell populations which are a prerequisite for the biochemical analysis of germ cell determination and differentiation.     

Persistence of gentian violet and leucogentian violet in channel catfish (ictalurus punctatus) muscle after water-borne exposure

Gentian violet is a triphenylmethane dye that is an antifungal/antiparastic agent. GV is similar to malachite green that has been used in the aquaculture industry for treatment or prevention of external fungal and parasitic infections in fish and fish eggs although it (MG) is not approved for this use. For these reasons, GV’s potential for misuse by the aquaculture industry is high. The uptake and depletion of gentian violet (GV) were determined in channel catfish (Ictalurus punctatus) after water-borne exposure (100 ng ml⁻¹, 1 h) under simulated aquaculture farming conditions. Leucogentian violet (LGV) was rapidly formed, concentrated in the muscle tissue, and very slowly eliminated from muscle tissue. An isocratic (60% acetonitrile–40% water; 0.05 M ammonium acetate buffer, pH 4.5) HPLC system consisting of a 5 μm LC–CN 250×4.6 mm I.D. column, a 20×2.0 mm I.D. PbO₂ oxidative post-column, and a UV–VIS detector set at 588 nm were used to determine uptake and depletion of tissue residues of GV and LGV with time. GV was rapidly depleted and converted to its major metabolite, LGV, which was detected out to 79 days. Therefore, LGV is the appropriate target analyte for monitoring exposure of channel catfish to GV.     

The Effect of Gentian Violet on Virulent Properties of <Emphasis Type="Italic">Candida albicans</Emphasis>

The aim of this study was to evaluate the effect of gentian violet (GV) on phospholipase activity, proteinase activity and germ tube formation rate of Candida albicans. Both 12 phospholipase-positive and 12 proteinase-positive C. albicans isolates with Pz values ≤0.89 were obtained. A yeast suspension (1–3 × 10⁷ cfu/ml) of each isolate was prepared. After a brief exposure (60 min) to sub-therapeutic concentrations (0.5 or 2 μg/ml) of GV, Pz value of phospholipase, Pz value of proteinase and germ tube formation rate were determined. Phospholipase activity, proteinase activity and germ tube formation rate in two groups exposed to GV were significantly lower than those in the group unexposed (P < 0.05). The results of this study indicated that sub-therapeutic concentrations of GV may lead to reduction in phospholipase activity, proteinase activity and germ tube formation, and then may suppress virulence and pathogenicity of C. albicans.