Parasitic load of the Pacific mackerel, Scomber japonicus (Pisces: Scombridae) from Northwestern Baja California, Mexico.

Globally, the exploitation of small pelagic fish, like Pacific mackerel is of great importance due to food industry demand. However, there are few studies regarding its parasites load and there are no in this geographic zone. This study aimed to assess the parasitic composition, some temporal changes (during spring and summer) in abundance, prevalence and intensity of infection parasitic of the Pacific mackerel (Scomber japonicus) from Todos Santos Bay, Baja California, Mexico. The parasite fauna of the Pacific mackerel consisted of 1930 parasites (1413 in spring and 517 in summer) distributed in the follow taxa: an Tetraphyllidea (Cestoda), Kuhnia scombri (Monogenea), Didymozoidae (Digenea), Anisakis sp. (Nematoda), Rhadinorhynchus sp. (Acanthocephala) and Caligus pelamydis (Copepoda). The nematodes parasite were the most abundant both in spring with a mean abundance of 27.6 parasites and in summer 8.2 parasites compared with the other taxa like Cestoda, Monogenea, Digenea, Acanthocephala and Copepoda (P = 0.003). The mean intensity of the nematodes in spring and summer was 28.1 and 13.4, respectively. The nematodes prevalence was 90 % in spring and 60 % in summer. In general, the parasite load is more abundant in spring than summer. In summer, absence of taxa as Cestoda and Copepoda were registered. Nematode larvae were present in the fish guts mesentery and inside of the stomach, pyloric caeca, intestine. Also the nematodes were found in the liver, muscle and gonads. The most affected organ by nematodes was the intestine mesentery. The most predominant parasite of this study has been Anisakis sp. during spring.

Multicentre determination of rezafungin (CD101) susceptibility of Candida species by the EUCAST method.

OBJECTIVES: Rezafungin (CD101) is a new long-acting echinocandin allowing weekly dosing, currently undergoing phase-II clinical trials for invasive candidiasis. The aim of this study was to assess rezafungin's in vitro activity against the most frequent Candida species following the EUCAST methodology. METHODS: The susceptibility of 2018 clinical Candida isolates was determined at four European laboratories. In parallel, six control strains were repeatedly tested. Wild-type upper limits (WT-ULs), defined as the MIC value where the wild-type distribution ends, were determined following the principles for EUCAST ECOFF-setting. RESULTS: The lowest rezafungin MICs (geometric MIC (GM-MIC), MIC range (mg/L)) were observed for C. albicans (0.016, 0.002-0.125) and the highest for C. parapsilosis (1.657, 0.063->4). MICs for the remaining species were in between these values (GM-MICs 0.048-0.055). Visual and statistical WT-ULs were identical for C. glabrata (0.125), C. krusei (0.125), C. parapsilosis (4), and C. tropicalis (0.25). If adopting these WT-ULs for classification into WT and non-WT populations, 1/413 C. glabrata, 1/402 C. krusei, 1/398 C. parapsilosis, and 1/402 C. tropicalis isolates were categorized as non-WT, all of which derived from Laboratory 1. For C. albicans unexplained laboratory variation was observed (WT-UL: 0.063-0.125 in Laboratories 1 and 2 versus 0.016 in Laboratories 3 and 4). A similar systematic difference was observed comparing the MICs for the three C. albicans QC strains, specifically, obtained in Laboratories 1and 2 with those in Laboratories 3 and 4. DISCUSSION: Rezafungin displayed species-specific activity similar to other echinocandins. Interlaboratory variation was observed for the most susceptible species C. albicans clinical and QC strains, an observation that warrants further investigation.

Impact of fluconazole susceptibility on the outcome of patients with candidaemia: data from a population-based surveillance.

OBJECTIVES: The clinical correlation of fluconazole antifungal susceptibility testing (AST) for Candida isolates and its integration with pharmacokinetics/pharmacodynamics (PK/PD) parameters is unclear. We analysed the impact of fluconazole minimum inhibitory concentration (MIC) values, 24-hour area under the concentration-time curve (AUC24) and AUC24/MIC ratio on the outcome of candidemic patients. METHODS: We included 257 episodes of candidaemia treated with fluconazole monotherapy for ≥72 hours from a population-based surveillance conducted in 29 hospitals (CANDIPOP Project). AST was centrally performed by European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) microdilution methods. Primary outcome was clinical failure (30-day mortality and/or persistent candidaemia for ≥72 hours from initiation of therapy). Secondary outcomes included early (3-7 days) and late (3-30 days) mortality. RESULTS: Rates of clinical failure, early and late mortality among evaluable episodes were 32.3% (80/248), 3.1% (8/257) and 23.4% (59/248). There was no relationship between fluconazole MIC values or PK/PD parameters and clinical failure. Although MIC values ≥2 mg/L by EUCAST (positive predictive value 32.1%, negative predictive value 68.7%) and ≥0.5 mg/L by CLSI (positive predictive value 34.8%, negative predictive value 74.4%) appeared to be optimal for predicting clinical failure, no significant associations remained after multivariate adjustment (odds ratio 1.67; 95% confidence interval 0.48-5.79; p 0.423). Lack of association was consistent for alternative thresholds (including proposed clinical breakpoints). The only association found for secondary outcomes was between an AUC24/MIC ratio >400 h by CLSI and early mortality (odds ratio 0.18; 95% confidence interval 0.04-0.98; p 0.026). CONCLUSIONS: High fluconazole MIC values did not negatively impact outcome of patients with candidaemia treated with fluconazole. No effect of PK/PD targets on the risk of clinical failure was found.

Evaluation of the possible influence of trailing and paradoxical effects on the clinical outcome of patients with candidemia.

OBJECTIVE: Paradoxical growth (PG) and trailing effect (TE) are frequently observed during antifungal susceptibility testing (AFST). These two phenomena interfere with the determination of the minimal inhibitory concentration (MIC). The aim of this study was to assess the clinical impact of TE and PG. METHODS: We analysed the frequency of TE and PG of 690 Candida isolates collected from a population-based study performed in Spain (CANDIPOP) and correlated the results with clinical outcome of the patients. RESULTS: Around 70% (484/690) of the isolates exhibited TE to azoles. Candida tropicalis showed the highest presence of TE (39/53 isolates exhibited residual growth >25% of control). No TE was seen in most of the isolates from the psilosis complex. PG was mainly associated with echinocandins. In patients treated with fluconazole within the first 48 hours after blood sampling (n = 221), the presence of TE to azoles tended to be associated with lower 30-day mortality (odds ratio (OR) 0.55, 95% confidence interval (CI) 0.25-1.00) but not with clinical failure (OR 0.85, 95% CI 0.45-1.54). In the subgroup of 117 patients treated with echinocandins, the presence of PG was not associated with patient's response to antifungal treatment (OR for 30-day mortality 1.63, 95% CI 0.76-4.03; OR for clinical failure 1.17, 95% CI 0.53-2.70). CONCLUSIONS: TE or PG are widely expressed among Candida spp., although they do not seem to influence clinical outcome.

Risk allelic load in Th2 and Th3 cytokines genes as biomarker of susceptibility to HPV-16 positive cervical cancer: a case control study.

BACKGROUND: Alterations in the host cellular immune response allow persistent infections with High-Risk Human Papillomavirus (HR-HPV) and development of premalignant cervical lesions and cervical cancer (CC). Variations of immunosuppressive cytokine levels in cervix are associated with the natural history of CC. To assess the potential role of genetic host immunity and cytokines serum levels in the risk of developing CC, we conducted a case-control study paired by age. METHODS: Peripheral blood samples from patients with CC (n = 200) and hospital controls (n = 200), were used to evaluate nine biallelic SNPs of six cytokine genes of the adaptive immune system by allelic discrimination and cytokines serum levels by ELISA. RESULTS: After analyzing the SNP association by multivariate logistic regression adjusted by age, CC history and smoking history, three Th2 cytokines (IL-4, IL-6 and IL-10) and one Th3 (TGFB1) cytokine were significantly associated with CC. Individuals with at least one copy of the following risk alleles: T of SNP (-590C > T IL-4), C of SNP (-573G > C IL-6), A of SNP (-592C > A IL-10), T of SNP (-819C > T IL-10) and T of SNP (-509C > T TGFB1), had an adjusted odds ratio (OR) of 2.08 (95 % CI 1.475-2.934, p = 0.0001), an OR of 1.70 (95 % CI 1.208-2.404, p = 0.002), an OR of 1.87 (95 % CI 1.332-2.630, p = 0.0001), an OR of 1.67 (95 % CI 1.192-2.353, p = 0.003) and an OR of 1.91 (95 % CI 1.354-2.701, p = 0.0001), respectively, for CC. The burden of carrying two or more of these risk alleles was found to have an additive effect on the risk of CC (p trend = 0.0001). Finally, the serum levels of Th2 and Th3 cytokines were higher in CC cases than the controls; whereas IFNG levels, a Th1 cytokine, were higher in controls than CC cases. CONCLUSION: The significant associations of five SNPs with CC indicate that these polymorphisms are potential candidates for predicting the risk of development of CC, representing a risk allelic load for CC and can be used as a biomarker of susceptibility to this disease.

A simple prediction score for estimating the risk of candidaemia caused by fluconazole non-susceptible strains.

We aimed to develop a simple prediction score to identify fluconazole non-susceptible (Flu-NS) candidaemia using simple clinical criteria. A derivation cohort was extracted from the CANDIPOP study, a prospective, multicentre, population-based surveillance programme on candidaemia conducted in 29 hospitals in Spain from April 2010 to May 2011. The score was validated with an external, multicentre cohort of adults with candidaemia in six tertiary hospitals in three countries. The prediction score was based on three variables selected by a logistic regression model together with the severity of disease. In total, 617 and 297 cases of candidaemia were included in the derivation and validation cohorts, respectively; of these, 134 (21.7%) and 57 (19.2%) were caused by Flu-NS strains. Factors independently associated with Flu-NS were transplant recipient status (adjusted odds ratio (AOR) 2.13; 95% CI 1.01-4.55; p 0.047), hospitalization in a unit with a high prevalence (≥ 15%) of Flu-NS strains (7.53; 4.68-12.10; p < 0.001), and previous azole therapy for at least 3 days (2.04; 1.16-3.62; p 0.014). The area under the receiver operating characteristics curve (AUC) was 0.76 (0.72-0.81), and using 2 points as the Flu-NS prediction score cut-off gave a sensitivity of 82.1%, a specificity of 65.6%, and a negative predictive value of 93%. The AUC in the validation cohort was 0.72 (95% CI 0.65-0.79). Hence, the Flu-NS prediction score helped to exclude Flu-NS Candida strains. This could improve the selection of empirical treatments for candidaemia in the future.

Emerging Trichosporon asahii in elderly patients: epidemiological and molecular analysis by the DiversiLab system.

Trichosporon asahii has been recognized as an emerging opportunistic agent for invasive infections, mainly in immunocompromised patients. Urinary tract infections by this pathogen may also occur, especially in patients with urinary obstruction or those undergoing vesical catheterization and antibiotic treatment. Many outbreaks of Trichosporon spp. have been detected after urinary catheter manipulations. We report the molecular-epidemiological characterization of T. asahii in our institution using the DiversiLab system for the molecular strain typing and compare three different methods for susceptibility testing. Our results present T. asahii as an emergent pathogen in elderly patients with urinary drainage devices that can be adequately treated with triazoles, with voriconazole being the most active. Broth dilution and Vitek 2 had good concordance, while Etest showed more discrepancies. In addition, the DiversiLab system for clonal strain typing may be a useful tool for fast and accurate management of nosocomial outbreaks.

Epidemiology and predictive factors for early and late mortality in Candida bloodstream infections: a population-based surveillance in Spain.

A prospective, multicentre, population-based surveillance programme for Candida bloodstream infections was implemented in five metropolitan areas of Spain to determine its incidence and the prevalence of antifungal resistance, and to identify predictors of death. Between May 2010 and April 2011, Candida isolates were centralized to a reference laboratory for species identification by DNA sequencing and for susceptibility testing by EUCAST reference procedure. Prognostic factors associated with early (0-7 days) and late (8-30 days) death were analysed using logistic regression modelling. We detected 773 episodes: annual incidence of 8.1 cases/100 000 inhabitants, 0.89/1000 admissions and 1.36/10 000 patient-days. Highest incidence was found in infants younger than 1 year (96.4/100 000 inhabitants). Candida albicans was the predominant species (45.4%), followed by Candida parapsilosis (24.9%), Candida glabrata (13.4%) and Candida tropicalis (7.7%). Overall, 79% of Candida isolates were susceptible to fluconazole. Cumulative mortality at 7 and 30 days after the first episode of candidaemia was 12.8% and 30.6%, respectively. Multivariate analysis showed that therapeutic measures within the first 48 h may improve early mortality: antifungal treatment (OR 0.51, 95% CI 0.27-0.95) and central venous catheter removal (OR 0.43, 95% CI 0.21-0.87). Predictors of late death included host factors (e.g. patients' comorbid status and signs of organ dysfunction), primary source (OR 1.63, 95% CI 1.03-2.61), and severe sepsis or septic shock (OR 1.77, 95% CI 1.05-3.00). In Spain, the proportion of Candida isolates non-susceptible to fluconazole is higher than in previous reports. Early mortality may be improved with strict adherence to guidelines.

Candida tropicalis antifungal cross-resistance is related to different azole target (Erg11p) modifications.

Candida tropicalis ranks between third and fourth among Candida species most commonly isolated from clinical specimens. Invasive candidiasis and candidemia are treated with amphotericin B or echinocandins as first-line therapy, with extended-spectrum triazoles as acceptable alternatives. Candida tropicalis is usually susceptible to all antifungal agents, although several azole drug-resistant clinical isolates are being reported. However, C. tropicalis resistant to amphotericin B is uncommon, and only a few strains have reliably demonstrated a high level of resistance to this agent. The resistance mechanisms operating in C. tropicalis strains isolated from clinical samples showing resistance to azole drugs alone or with amphotericin B cross-resistance were elucidated. Antifungal drug resistance was related to mutations of the azole target (Erg11p) with or without alterations of the ergosterol biosynthesis pathway. The antifungal drug resistance shown in vitro correlated very well with the results obtained in vivo using the model host Galleria mellonella. Using this panel of strains, the G. mellonella model system was validated as a simple, nonmammalian minihost model that can be used to study in vitro-in vivo correlation of antifungals in C. tropicalis. The development in C. tropicalis of antifungal drug resistance with different mechanisms during antifungal treatment has potential clinical impact and deserves specific prospective studies.

Molecular Mechanism and Potential Targets for Blocking HPV-Induced Lesion Development.

Persistent infection with high-risk HPV is the etiologic agent associated with the development of cervical cancer (CC) development. However, environmental, social, epidemiological, genetic, and host factors may have a joint influence on the risk of disease progression. Cervical lesions caused by HPV infection can be removed naturally by the host immune response and only a small percentage may progress to cancer; thus, the immune response is essential for the control of precursor lesions and CC. We present a review of recent research on the molecular mechanisms that allow HPV-infected cells to evade immune surveillance and potential targets of molecular therapy to inhibit tumor immune escape.

Influence of ß-glucan on innate immunity and resistance of Lutjanus guttatus to an experimental infection of dactylogyrid monogeneans.

The present study investigated the effect of ß-1,3/1,6-glucan on growth, haematology, innate immunity and resistance against dactylogyrids on the spotted rose snapper (Lutjanus guttatus). Fish were fed during 5 weeks with commercial diet (control group) and same diet supplemented with three levels of ß-glucans (0·05%, 0·1% and 0·5%/kg feed). The results showed that at concentrations of 0·05% and 0·1%, fish growth was enhanced, and in weeks 2 and 4, an increase in cellular responses such as percentage of monocytes, neutrophils, respiratory burst activity and nitric oxide activity was observed. In diet with 0·5%ß-glucans, changes were registered at the end of the experiment. At week 2, 0·05%ß-glucans showed the best response to most of the analysed parameters. In a second trial, diet with 0·05%ß-glucans was chosen to prove its effect on the resistance of infected fish with monogeneans. The results showed that fish reduce significantly the number of dactylogyrids, and parameters such as WBC, percentage of lymphocytes, neutrophils and eosinophils were increased. In addition, WBC and percentage of thrombocytes increased in the control (+). The ß-glucans have the potential to be use in diet formulations of the spotted rose snapper and to limit the adverse effects of dactylogyrids.

Hematological characteristics of the spotted rose snapper Lutjanus guttatus (Steindachner, 1869) healthy and naturally infected by dactylogyrid monogeneans.

The aim of the present study was to obtain a basic knowledge of the hematology in order to determine changes in blood parameters of the spotted rose snapper Lutjanus guttatus. The morphological features of blood cells were described according to the observations made by light microscopy of Wright-Giemsa-stained blood films. The reference intervals and the mean value were determined for each hematological parameter evaluated in healthy fish and data were compared to those of naturally infected, with dactylogyrid monogeneans fish. Infected fish showed a prevalence of 100% and a mean intensity of 246.6 parasites per fish. Mean values of HCT, WBC, thrombocytes percentage and eosinophils percentage were significantly higher (P<0.05) in the infected fish. In addition, lymphocytes percentage and total protein were significantly lower (P<0.05) in the infected fish compared to healthy fish. Only total WBC count, lymphocytes percentage and eosinophils percentage in infected fish were outside reference interval. The hematology of the spotted rose snapper of this study might serve as a basis for future studies and diagnosis. Changes observed in blood parameters in infected fish suggest that the immune system of L. guttatus was affected by the presence of the parasites.

IL-10 expression is regulated by HPV E2 protein in cervical cancer cells.

It has been found that certain cytokines (IL-4, IL-10 and TGF-ß1) are highly expressed locally in biopsies from patients with premalignant lesions and cervical cancer, and may induce a local immune-suppression state. In particular, IL-10 is highly expressed in tumor cells and its expression is directly proportional to the development of HPV-positive cervical cancer, suggesting an important role of HPV proteins in the expression of IL-10. In fact, we demonstrated that E6 and E7 HPV proteins regulate TGF-ß1 gene expression in cervical cancer cells. Here, we found by band shifting analysis that the HPV E2 protein binds to the regulatory region of the human IL-10 gene (-2054 nt) and induces high promoter activity in epithelial cells. Additionally, cervical cancer cells transfected to express the HPV E2 protein induce elevated levels of IL-10 mRNA in human papillomavirus-infected cells. The elevated expression of IL-10 may allow for virus persistency, the transformation of cervical epithelial cells, and consequently cancer development.

Frequency of voriconazole resistance in vitro among Spanish clinical isolates of Candida spp. According to breakpoints established by the Antifungal Subcommittee of the European Committee on Antimicrobial Susceptibility Testing.

A total of 4,226 Spanish clinical isolates of Candida spp. were analyzed to assess resistance to voriconazole according to breakpoints established by the European Committee for Antimicrobial Susceptibility Testing (where susceptibility [S] to voriconazole corresponds to a MIC of ≤ 0.12 mg/liter). Resistance was uncommon among Candida albicans (5%), C. parapsilosis (1.2%), and C. tropicalis (11%) isolates. Voriconazole MICs of >0.12 mg/liter were more frequent among Candida glabrata and C. krusei isolates. A significant percentage of voriconazole-resistant strains came from oropharyngeal infections and exhibited high MICs of other azoles.

In vitro activity of antifungals against Zygomycetes.

To date, no reference standard for therapy for zygomycosis has been established because there are insufficient clinical data with which to make such a judgement. Knowledge of the species responsible for the infection and its antifungal susceptibility profile has become increasingly important in the management of patients. Amphotericin B is the most active drug against all the species involved, followed by posaconazole, whereas voriconazole has no activity. Echinocandins are completely inactive in vitro, but may be an interesting option when used in combination with other drugs.

HPV 16 E2 protein induces apoptosis in human and murine HPV 16 transformed epithelial cells and has antitumoral effects in vivo.

OBJECTIVE: Our aims were to examine the ability of the human papillomaviruse (HPV) 16 E2 protein to induce apoptosis in a murine HPV-transformed cell line, and to evaluate its antitumor properties on HPV-associated tumors in vivo in immunocompetent mice. METHODS: HPV-transformed murine BMK-16/myc cells and human SiHa cells were transfected with the HPV 16 E2 gene to examine the effects of the E2 protein on cell growth and on the E6 and E7 oncogenes as well as DNA fragmentation and activation of the extrinsic pathway of apoptosis. Finally, to test the antitumor effect of the E2 protein on an experimental mouse tumor model, we generated a recombinant adenovirus expressing the E2 protein. RESULTS: The E2 protein inhibited the growth of SiHa and BMK-16/myc cell lines, and repressed the E6 and E7 oncogenes. Moreover, the E2 protein induced DNA fragmentation and apoptosis through activation of caspases 8 and 3 in BMK-16/myc cells. On the other hand, E2 also showed antitumor effects in vivo. CONCLUSIONS: Our findings indicate that E2 exerts pro-apoptotic activity in a murine HPV-transformed cell line as well as an antitumor effect in vivo.

In vitro susceptibility of Cryptococcus gattii clinical isolates.

The data available in the literature concerning Cryptococcus gattii in vitro antifungal susceptibility are contradictory. We have analyzed the activity of eight antifungal agents against 23 C. gattii clinical isolates and compared the susceptibility profiles with those of C. neoformans. MIC analysis (mg/L) revealed that C. gattii isolates were more susceptible to amphotericin B and flucytosine than were C. neoformans isolates. Fluconazole and other azole compounds showed high MIC values for C. gattii. Posaconazole displayed good activity. Further studies are required to ascertain the predictive value of the in vitro data presented here.

El paradigma inmune Th1-Th2: un vínculo entre obesidad, aterosclerosis y diabetes mellitus / The Th1-Th2 immune paradigm: a link among obesity, atherosclerosis and diabetes mellitus

Recientemente ha llamado la atención la asociación entre inflamación crónica de baja intensidad --evidenciada como elevación de la proteína C reactiva (PCR)-- y obesidad, aterosclerosis y diabetes mellitus. Hay evidencia de que esta asociación se debe a una desregulación de la respuesta inmune de linfocitos T cooperadores tipos 1 y 2, orientada hacia un perfil proinflamatorio, con aumento en la producción de interleucina (IL) 6 y de otras citocinas, como el factor de necrosis tumoral alfa, la IL-1-ß y el interferón-gamma. Esta desregulación de la respuesta inmune tiene un papel fisiopatológico crucial en la obesidad, la enfermedad aterosclerótica y la diabetes mellitus. Asimismo, podría ser el origen de las anomalías observadas en el síndrome metabólico, como la resistencia a la insulina, la hiperglucemia y la dislipidemia, debido a los efectos de las citocinas involucradas sobre el metabolismo. El conocimiento de estos mecanismos proporcionará un mejor entendimiento de la fisiopatología de las enfermedades crónicas degenerativas y puede ser la base para el planteamiento de nuevas estrategias preventivas y terapéuticas (AU)

An association between elevated C-reactive protein related to low-intensity chronic inflammation and chronic disease (obesity, atherosclerosis and diabetes mellitus) has been the focus of recent attention. A growing body of knowledge indicates that this association is due to disregulation of the Th1-Th2 immune response, with increased production of proinflammatory cytokines TNF-*, IL1-ß, IFN-* and IL-6. Such an abnormality plays a key physiopathologic role in the development of obesity, atherosclerosis and diabetes mellitus. Moreover, this proinflammatory disregulation of the immune response can lead to the insulin resistance, hyperglycemia and dyslipidemia that characterize the metabolic syndrome due to the metabolic effects of the cytokines involved. The study of these mechanisms will promote better understanding of the physiopathology of chronic diseases and could be useful for the development of new preventive and therapeutic strategies (AU)

Radiological studies reveal radial differences in the architecture of the polysaccharide capsule of Cryptococcus neoformans.

The polysaccharide capsule of the pathogenic fungus Cryptococcus neoformans is an important virulence factor, but relatively little is known about its architecture. We applied a combination of radiological, chemical, and serological methods to investigate the structure of this polysaccharide capsule. Exposure of C. neoformans cells to gamma radiation, dimethyl sulfoxide, or radiolabeled monoclonal antibody removed a significant part of the capsule. Short intervals of gamma irradiation removed the outer portion of the cryptococcal capsule without killing cells, which could subsequently repair their capsules. Survival analysis of irradiated wild-type, acapsular mutant, and complemented mutant strains demonstrated that the capsule contributed to radioprotection and had a linear attenuation coefficient higher than that of lead. The capsule portions remaining after dimethyl sulfoxide or gamma radiation treatment were comparable in size, 65 to 66 microm3, and retained immunoreactivity for a monoclonal antibody to glucuronoxylomannan. Simultaneous or sequential treatment of the cells with dimethyl sulfoxide and radiation removed the remaining capsule so that it was not visible by light microscopy. The capsule could be protected against radiation by either of the free radical scavengers ascorbic acid and sorbitol. Sugar composition analysis of polysaccharide removed from the outer and inner parts of the capsule revealed significant differences in glucuronic acid and xylose molar ratios, implying differences in the chemical structure of the constituent polysaccharides. Our results provide compelling evidence for the existence of two zones in the C. neoformans capsule that differ in susceptibility to dimethyl sulfoxide and radiation and, possibly, in packing and composition.

Elements from the cAMP signaling pathway are involved in the control of expression of the yeast gluconeogenic gene FBP1.

cAMP represses the transcription of some Saccharomyces cerevisiae genes sensitive to catabolite repression. The effect of cAMP on the expression of FBP1, encoding fructose-1,6-bisphosphatase (FbPase), has been further investigated. In yeast cells shifted to a derepressing medium, synthesis of FbPase was delayed if the strong decrease in intracellular cAMP, which occurs during the shift, was prevented. A similar delay occurred in a RAS2val19 strain, while in a tpk1w strain, with weak protein kinase A activity, induction of FbPase occurred earlier than in a TPK1 strain. In the tpk1w strain, proteins which bind the UAS1 element of FBP1 were present during growth on glucose but they were only weakly operative. Expression of CAT8 and SIP4, encoding proteins which bind the UAS2 element, was blocked by a high concentration of cAMP, but catabolite repression of these genes was not much relieved in a tpk1w strain. We conclude that in S. cerevisiae, as reported for Schizosaccharomyces pombe, control of FBP1 requires both cAMP-dependent and independent pathways; however, the mechanisms operating in the two yeasts are different.