Fungal Secondary Metabolism

Definition: Fungal secondary metabolites (SMs) comprise a vast collection of compounds expendable for these organisms under laboratory conditions. They exhibit enormous chemical diversity, and usu- ally belong to four major families: terpenoids, polyketides, non-ribosomal peptides, or a combination of the last two. Their functions are very diverse and are normally associated with a greater fitness of the producing fungi in their environment, which often compete with other microorganisms or interact with host plants. Many SMs have beneficial applications, e.g., as antibiotics or medical drugs, but others, known as mycotoxins, are harmful to health

Identification and regulation of fusA, The polyketide synthase gene responsible for fusarin production in Fusarium fujikuroi

Fusarins are a class of mycotoxins of the polyketide family produced by different Fusarium species, including the gibberellin- producing fungus Fusarium fujikuroi. Based on sequence comparisons between polyketide synthase (PKS) enzymes for fusarin production in other Fusarium strains, we have identified the F. fujikuroi orthologue, called fusA. The participation of fusA in fusarin biosynthesis was demonstrated by targeted mutagenesis. Fusarin production is transiently stimulated by nitrogen avail- ability in this fungus, a regulation paralleled by the fusA mRNA levels in the cell. Illumination of the cultures results in a reduc- tion of the fusarin content, an effect partially explained by a high sensitivity of these compounds to light. Mutants of the fusA gene exhibit no external phenotypic alterations, including morphology and conidiation, except for a lack of the characteristic yellow and/or orange pigmentation of fusarins. Moreover, the fusA mutants are less efficient than the wild type at degrading cel- lophane on agar cultures, a trait associated with pathogenesis functions in Fusarium oxysporum. The fusA mutants, however, are not affected in their capacities to grow on plant tissues

Evaluación objetiva de la conducción del sonido por vía ósea con potenciales evocados auditivos

The objective evaluation of sound conduction through the bone in children has been a subject little reported in the literature. The interpretation of its result, determining the difference with the airway, makes it possible to obtain the air-bone gap, an important variable for making the differential diagnosis of hearing loss. The characterization of bone thresholds using the Brainstem Auditory Evoked Potentials as a method, either with the click stimulus or short tones, has been a topic with little diffusion in clinical audiology, because the response obtained presents changes in morphology and is difficult to recognize, requiring great expertise to identify it at intensities close to the threshold. The Steady-State Auditory Evoked Potentials constitute an appropriate alternative for the evaluation of the bone route, due to the use of modulated tones as stimuli; which are not affected when passing through the bone transducer and because the response is detected automatically, which reduces the bias introduced by the evaluator when visually identifying the electrophysiological thresholdLa evaluación objetiva de la conducción del sonido por vía ósea en el niño ha sido un tema poco reportado en la literatura. La interpretación de su resultado determinando la diferencia con la vía aérea, hace posible obtener la brecha aéreo-ósea, variable importante para realizar el diagnóstico diferencial de las pérdidas auditivas. La caracterización de los umbrales óseos utilizando como método los Potenciales Evocados Auditivos de Tallo Cerebral, ya sea con el estímulo a click ó los tonos breves, ha sido un tópico con poca difusión en la audiología clínica, debido a que la respuesta que se obtiene presenta cambios en la morfología y es difícil de reconocer, requiriéndose gran experticidad para identifi carla en intensidades cercanas al umbral. Los Potenciales Evocados Auditivos de Estado Estable, constituyen una alternativa apropiada para la evaluación de la vía ósea, debido a utiliza como estímulo los tonos modulados; los cuales no se afectan al pasar por el transductor óseo y a que la respuesta se detecta en forma automática, lo que reduce el sesgo que introduce el evaluador al identificar visualmente el umbral electrofisiológico

A novel lncRNA as a positive regulator of carotenoid biosynthesis in Fusarium

The fungi Fusarium oxysporum and Fusarium fujikuroi produce carotenoids, lipophilic terpenoid pigments of biotechnological interest, with xanthophyll neurosporaxanthin as the main end product. Their carotenoid biosynthesis is activated by light and negatively regulated by the RING-finger protein CarS. Global transcriptomic analysis identified in both species a putative 1-kb lncRNA that we call carP, referred to as Fo-carP and Ff-carP in each species, upstream to the gene carS and transcribed from the same DNA strand. Fo-carP and Ff-carP are poorly transcribed, but their RNA levels increase in carS mutants. The deletion of Fo-carP or Ff-carP in the respective species results in albino phenotypes, with strong reductions in mRNA levels of structural genes for carotenoid biosynthesis and higher mRNA content of the carS gene, which could explain the low accumulation of carotenoids. Upon alignment, Fo-carP and Ff-carP show 75-80% identity, with short insertions or deletions resulting in a lack of coincident ORFs. Moreover, none of the ORFs found in their sequences have indications of possible coding functions. We conclude that Fo-carP and Ff-carP are regulatory lncRNAs necessary for the active expression of the carotenoid genes in Fusarium through an unknown molecular mechanism, probably related to the control of carS function or expressio

Potenciales evocados auditivos de estado estable en recien nacidos: diferencias en la conduccion oseo-aerea a las frecuencias de 500 y 2000 Hz

Introduction: Auditory Steady State Evoked Responses (ASSR) constitute a valid method for the objective evaluation of hearing. The detection of responses in newborns based on stimulation by air and bone is a subject little published in the literature, constituting an interesting topic for the proposal of this technique as a tool for hearing screening. Objective: To determine the differences in hearing thresholds with ASSR in newborns at frequencies of 500 and 2000 Hz, presenting stimuli by air and bone. Material and Method: A group of 15 newborns was evaluated with ASSR until obtaining the electrophysiological threshold at the frequencies of 500 and 2000 Hz, stimulating the airway and bone independently. Results: A significant difference is obtained in the auditory response thresholds as a function of the stimulation pathway and frequency. In bone conduction, responses were obtained at a lower intensity (24 ± 7) at 500 Hz, compared with the results obtained for the air conduction (46 ± 6) at the same frequency. For 2000 Hz there was an opposite effect with a higher detection for the air conduction, obtaining a mean threshold value (30 ± 8) lower than the result for the bone conduction (41 ± 6). Conclusions: The results obtained allow us to conclude that the best frequency for the exploration of the airway in newborns is 2000 Hz and for the bone route 500 Hz.Introducción: Los Potenciales Evocados Auditivos de Estado Estable (PEAee) constituyen un método válido para la evaluación objetiva de la audición. La detección de las respuestas en recién nacidos en función de la estimulación por vía aérea y ósea es un tema poco publicado en la literatura, constituyendo un tópico interesante para la propuesta de esta técnica como herramienta para el cribado auditivo. Objetivo: Determinar las diferencias de los umbrales auditivos con los PEAee en los recién nacidos a las frecuencias de 500 y 2000 Hz, presentando los estímulos por vía aérea y ósea. Material y Método: Se evaluó un grupo de 15 recién nacidos con los PEAee hasta obtener el umbral electrofisiológico a las frecuencias de 500 y 2000 Hz estimulando la vía aérea y ósea de forma independiente. Resultados: Se obtiene una diferencia significativa en los umbrales de la respuesta auditiva en función de la vía de estimulación y la frecuencia. En la conducción ósea se obtuvieron respuestas a menor intensidad (24±7) en 500 Hz, comparado con los resultados obtenidos para la vía aérea (46±6) a la misma frecuencia. Para los 2000 Hz hubo un efecto opuesto con una mayor detección para la vía aérea obteniéndose un valor medio de umbral (30±8) inferior al resultado de la vía ósea (41±6). Conclusiones: Los resultados obtenidos permiten concluir que la mejor frecuencia para la exploración de la vía aérea en los recién nacidos es 2000 Hz y para la vía ósea 500 Hz

Comparative transcriptomic analysis unveils interactions between the regulatory CarS protein and light response in Fusarium

Background The orange pigmentation of the agar cultures of many Fusarium species is due to the production of carotenoids, terpenoid pigments whose synthesis is stimulated by light. The genes of the carotenoid pathway and their regulation have been investigated in detail in Fusarium fujikuroi. In this and other Fusarium species, such as F. oxysporum, deep-pigmented mutants affected in the gene carS, which encodes a protein of the RING-finger family, overproduce carotenoids irrespective of light. The induction of carotenogenesis by light and its deregulation in carS mutants are achieved on the transcription of the structural genes of the pathway. We have carried out global RNA-seq transcriptomics analyses to investigate the relationship between the regulatory role of CarS and the control by light in these fungi. Results The absence of a functional carS gene or the illumination exert wide effects on the transcriptome of F. fujikuroi, with predominance of genes activated over repressed and a greater functional diversity in the case of genes induced by light. The number of the latter decreases drastically in a carS mutant (1.1% vs. 4.8% in the wild-type), indicating that the deregulation produced by the carS mutation affects the light response of many genes. Moreover, approximately 27% of the genes activated at least 2-fold by light or by the carS mutation are coincident, raising to 40% for an 8-fold activation threshold. As expected, the genes with the highest changes under both regulatory conditions include those involved in carotenoid metabolism. In addition, light and CarS strongly influence the expression of some genes associated with stress responses, including three genes with catalase domains, consistent with roles in the control of oxidative stress. The effects of the CarS mutation or light in the transcriptome of F. oxysporum were partially coincident with those of F. fujikuroi, indicating the conservation of the objectives of their regulatory mechanisms. Conclusions The CarS RING finger protein down-regulates many genes whose expression is up-regulated by light in wild strains of the two investigated Fusarium species, indicating a regulatory interplay between the mechanism of action of the CarS protein and the control by light.España, Ministerio de Economía y Competitividad, project BIO2015–69613-REspaña, Junta de Andalucía project CTS-6638 CTS-66

Relation between CarS expression and activation of carotenogenesis by stress in Fusarium fujikuroi

Fusarium fujikuroi, a model organism for secondary metabolism in fungi, produces carotenoids, terpenoid pigments with antioxidant activity. Previous results indicate that carotenoid synthesis in F. fujikuroi is stimulated by light or by different stress conditions and downregulated by a RING finger protein encoded by carS gene. Here, we have analyzed the effects of three stressors, nitrogen scarcity, heat shock, and oxidative stress. We compared them with the effect of light in the wild type, a carS mutant that overproduces carotenoids, and its complemented strain. The assayed stressors increase the synthesis of carotenoids in the three strains, but mRNA levels of structural genes of carotenogenesis, carRA and carB, are only enhanced in the presence of a functional carS gene. In the wild-type strain, the four conditions affect in different manners the mRNA levels of carS: greater in the presence of light, without significant changes in nitrogen starvation, and with patent decreases after heat shock or oxidative stress, suggesting different activation mechanisms. The spores of the carS mutant are more resistant to H2O2 than those of the wild type; however, the mutant shows a greater H2O2 sensitivity at the growth level, which may be due to the participation of CarS in the regulation of genes with catalase domains, formerly described. A possible mechanism of regulation by heat stress has been found in the alternative splicing of the intron of the carS gene, located close to its 3′ end, giving rise to the formation of a shorter protein. This action could explain the inducing effect of the heat shock, but not of the other inducing conditions, which may involve other mechanisms of action on the CarS regulator, either transcriptionally or post-transcriptionally.Ministerio de Economía y Competitividad BIO 2015–69613-RMinisterio de Ciencia e Innovación RTI 2018-101902-B-I00Junta de Andalucía P10-CTS-6638, P20-0124

Carotenoid Cleavage Oxygenases from Microbes and Photosynthetic Organisms: Features and Functions

Apocarotenoids are carotenoid-derived compounds widespread in all major taxonomic groups, where they play important roles in different physiological processes. In addition, apocarotenoids include compounds with high economic value in food and cosmetics industries. Apocarotenoid biosynthesis starts with the action of carotenoid cleavage dioxygenases (CCDs), a family of non-heme iron enzymes that catalyze the oxidative cleavage of carbon–carbon double bonds in carotenoid backbones through a similar molecular mechanism, generating aldehyde or ketone groups in the cleaving ends. From the identification of the first CCD enzyme in plants, an increasing number of CCDs have been identified in many other species, including microorganisms, proving to be a ubiquitously distributed and evolutionarily conserved enzymatic family. This review focuses on CCDs from plants, algae, fungi, and bacteria, describing recent progress in their functions and regulatory mechanisms in relation to the different roles played by the apocarotenoids in these organisms.Ministerio de Ciencia y Tecnología AGL2015-70218, BIO2013-44239-R, AGL2012-34573, BIO2012-39716 y BIO2009-11131Junta de Andalucía P07-CVI-02813 y CTS-6638Generalitat Valenciana PROMETEOII/2014/02

Aproximación del Estado del Arte sobre: Importancia del valor patrimonial de sitios arqueológicos

El análisis del estado de arte que se realizó es acerca de la importancia y reconocimiento del valor patrimonial de sitios arqueológicos. El estudio tiene como finalidad generar investigación a partir de los vacíos cognoscitivos identificados, para presentar una propuesta de tema de tesis sobre la puesta en valor del sitio arqueológico ciudad perdida en las brisas Nueva Segovia. Producto de la revisión bibliográfica, se puede apreciar el porqué de la importancia histórica del patrimonio arqueológico para cimentar una identidad cultural como nación y también la problemática generada por el desaprovechamiento del potencial de desarrollo del sitio en cuestión