Effects of temperature and nutrients on growth and toxicity of Alexandrium affine from southeastern Gulf of California.

An Alexandrium affine strain (AAJQ-1) from San José Island, Gulf of California was characterized for growth and toxicology. Fivefold of f/2 + Se cultures were incubated for 34 days in a temperature gradient (21-29 °C). Aliquots were collected every third day for cell counting, toxin determination, and nutrient analyses. In this study ELISA method was used to evaluate the PSP toxin production due to the lower detection limit than the HPLC method. The highest cell density (6724 cells mL-1) and growth rate (0.22 day-1) were obtained at 27 °C and they were related to temperature in all treatments. Cell density showed negative correlation with nitrate at temperatures ≥23 °C, and with orthophosphate 27 °C, furthermore, these correlations promote the toxin production (0.05-0.45 fmol STX cell-1); beyond that nitrite at high temperature seems to promote toxin production, which has not been sufficiently documented.

Growth and paralytic shellfish poisoning toxin production by a Mexican dinoflagellate strain of Alexandrium tamiyavanichii Balech (1994) under different nutrient conditions.

Alexandrium tamiyavanichii is a marine dinoflagellate known to produce Paralytic Shellfish Poisoning (PSP) toxin. Thus, a strain was isolated from La Paz Bay, Baja California Sur, Mexico and used to explore whether stress conditions, such as phosphorus limitation (PL) and nitrogen enrichment (NE) modulate population growth and PSP toxin production in the GSe medium. Growth kinetics showed that the PL treatment produced a 3.4-fold increase in cell density versus control at day 30 of the culture cycle. The highest PSP concentration was found in the control culture (309 fmol cell-1) on day 21. Saxitoxin (STX) was the main analog in all the treatments (> 40 % mol). In conclusion, PL and NE treatments promoted growth kinetics in the species studied but did not affect the PSP toxin production. For the first time, the present research describes A. tamiyavanichii high toxicity strain isolated from Mexican coasts relative to the South-Atlantic strains.

Contrasting nutrient distributions during dry and rainy seasons in coastal waters of the southern Gulf of Mexico driven by the Grijalva-Usumacinta River discharges.

Globally, nutrient river discharges drive water quality of coastal ecosystems, and excess nutrients can cause eutrophication impacts. The Grijalva-Usumacinta River System (GURS) discharges in the southern Gulf of Mexico (SGoM) and it is the second largest riverine input to the Gulf. To study how contrasting GURS freshwater flow between rainy and dry seasons affects nutrients concentrations in the receiving coastal ecosystem, we evaluated nutrient variability in the water column during both seasons. High inorganic nutrients and total phosphate outline the rivers discharge plumes during rainy season, and were significantly higher than during the dry season throughout the study area, suggesting contrasting seasonal nutrient discharge of the GURS to coastal waters. On average the GURS discharged 141,123 t N yr-1 6893 t P yr-1 and 928,904 t Si yr-1 to SGoM. These results contribute with a nutrient baseline in the SGoM that could be useful for GURS decision-makers.

Absence of hypoxia events in the adjacent coastal waters of Grijalva-Usumacinta river, Southern Gulf of Mexico.

Globally, oxygen concentration in many coastal areas is depleting. River nutrient discharges may produce hypoxia events. The Southern Gulf of Mexico receives the discharges of the Grijalva-Usumacinta River System, the second largest in the Gulf of Mexico. To evaluate the influence of river discharges on dissolved oxygen concentrations in the receiving coastal ecosystem, we studied the variation of physicochemical variables in the water column. During the dry season, the influence of the river waters to the coastal area is scarce, but during the rainy season the river plume reached ~9 km offshore. The lowest concentration of dissolved oxygen (3.6 mg L-1) was observed within the river plume. We concluded that, in the studied area, hypoxia events (oxygen concentrations ≤ 2 mg L-1) would occur during the rainy season, low winds and in deeper waters (>80 m depth).

Salud pública y pruebas diagnósticas del COVID-19: caso Venezuela / Public health and diagnostics tests for SARS-COVID-2 infection: The venezuela case

La salud pública mundial presenta en la actualidad un reto de grandes dimensiones para realizar las funciones esenciales del Siglo XXI, "el diagnóstico temprano y el tratamiento preventivo de las enfermedades"; por lo tanto la OMS considera que para conocer la magnitud de la epidemia COVID-19 es básico contar con suficientes pruebas diagnósticas en cantidad y calidad. En Venezuela, el Ministerio de la Salud comunica que se han realizado más de 80.484 pruebas por millón de habitantes (marzo-diciembre 2020), las más altas de la región; sin embargo, las pruebas diagnósticas de PCR y Prueba de antígenos, no alcanzan a 1.488,8 (105) y 11,9 (105) respectivamente, muy bajas. Se revisan las pruebas más usadas para detección de genoma, antígenos y serología, mediante pruebas de tiempo y rápidas, ambulatorias o de estricto manejo en laboratorio(AU)

Global public health currently presents a major challenge in performing the essential functions of the 21st century, "early diagnosis and preventive treatment of diseases", so WHO believes that sufficient diagnostic evidence in quantity and quality is essential to understand the scale of the COVID-19 epidemic. In Venezuela, the Ministry of Health reports that more than 80,484 tests per million inhabitants (march-december 2020) have been carried out; however, diagnostic tests of PCR and Antigen Test, do not reach 14,888 (106) and 110 (106) respectively, which is very low compared to neighboring countries. The most commonly used tests for genome, antigen and serology are reviewed(AU)

Historical observations of algal blooms in Mazatlan Bay, Sinaloa, Mexico (1979-2014).

A 35-year record of algal blooms in Mazatlan Bay is reviewed in order to register bloom-forming species and their seasonal presence, duration, degree of toxicity and environmental impact. A total of 202 algal blooms have been recorded and 25 dominant species identified: 6 toxic, 5 harmful and 14 harmless species. A harmless species, Myrionecta rubra, tended to decrease in frequency, while toxic species Gymnodinium catenatum and Margalefidinium polykrikoides showed a clear trend towards an increase in frequency. The number of discoloration days attributable to blooms was highly variable in each year, but a decadal analysis revealed a tendency to increase. The monthly distribution of algal blooms for decades showed two peaks of high frequency, the larger from February to May and the smaller from September to November. The duration of blooms varied from a few days to more than three months; the ephemeral blooms were the most frequent, but in the last decade, the frequency of the longer-lasting blooms has increased. An absence of blooms in 1983-4 and 1992-3 coincided with strong El Niño events, but this pattern was not consistent in subsequent El Niño years. Years with more or fewer discolorations days appear to be associated with cold or warm phases of the Pacific Decadal Oscillation.

Identification and genome analysis of tomato chlorotic spot virus and dsRNA viruses from coinfected vegetables in the Dominican Republic by high-throughput sequencing.

The Tomato chlorotic spot virus (TCSV) was first reported in the 1980s, having its occurrence limited to Brazil and Argentina. Due to an apparent mild severity in the past, molecular studies concerning TCSV were neglected. However, TCSV has disseminated over the USA and Caribbean countries. In Dominican Republic TCSV has been recently reported on important cultivated crops such as pepper and beans. In this work, we provide the first complete genome of a TCSV isolate from symptomatic plants in Dominican Republic, which was obtained by high-throughput sequencing. In addition, three dsRNA viruses from different virus families were identified coinfecting these plants Bell pepper endornavirus (BPEV), Southern tomato virus (STV) and Pepper cryptic virus 2 (PCV-2). Phylogenetic analysis showed that the Dominican Republic TCSV isolate has a close relationship with other TCSV isolates and a reassortant isolate between TCSV and Groundnut ringspot virus (GRSV), all found in USA. BPEV, STV and PCV-2 isolates from Dominican Republic were close related to corresponding American isolates. The possible biological implications of these virus-mixed infections are discussed.

Environmental forcing on the flux of organic-walled dinoflagellate cysts in recent sediments from a subtropical lagoon in the Gulf of California.

To evaluate the relationship of changes in organic-walled dinoflagellate cyst (dinocyst) fluxes to sediments with environmental variables (air and sea surface temperatures, El Niño conditions, rainfall, and terrigenous index), cyst assemblages were analyzed in a 210Pb-dated sediment core (~100years) from the pristine San José Lagoon (San José Island, SW Gulf of California). The dinocyst abundance ranged from 3784 to 25,108cystsg-1 and fluxes were of the order of 103-104cystscm-2yr-1. Lingulodinium machaerophorum, Polysphaeridium zoharyi and Spiniferites taxa accounted for 96% of the total dinocyst assemblages, and the abundances of these species increased towards the core surface. P. zoharyi fluxes increased from about 1965 onwards. Redundancy analyses, showed that mean minimum air temperature and terrigenous index were the key factors governing dinocyst fluxes. In this study, dinocyst fluxes of dominant taxa had responded to changes in climate-dependent environmental variables during the past ~20years; this may also be the case in other subtropical coastal lagoons.

[Harmful algal blooms produced by Pyrodinium bahamense in Oaxaca, Mexico (2009-2010)]. / Florecimientos algales nocivos producidos por Pyrodinium bahamense en Oaxaca, México (2009-2010).

OBJECTIVE: Pyrodinium bahamense monitoring in water and their toxins in rock oyster Striostrea prismatica in Santiago Astata and Puerto Escondido Oaxaca was performed from September 2009 to July 2010. MATERIALS AND METHODS: Pyrodinium bahamense abundance in water, and concentration and toxic profile of paralytic shellfish toxins were analyzed monthly in soft tissue of mollusk in composite samples in high performance liquid chromatography. RESULTS: High abundance of Pyrodinium bahamense was found in Santiago Astata on December, February, April and June; and in Puerto Escondido on April and June. The concentrations of the paralyzing toxin that exceeded the regulatory limit for human consumption of mollusks (800 µg STX eq. kg⁻¹) were presented in Santiago Astata on November, December, January, February and June; and in Puerto Escondido on December and June. CONCLUSIONS: For several months there was risk to public health due to the presence of paralytic shellfish toxins above the regulatory limit in oysters from the study area.

Florecimientos algales nocivos producidos por Pyrodinium bahamense en Oaxaca, México (2009-2010) / Harmful algal blooms produced by Pyrodinium bahamense in Oaxaca, Mexico (2009-2010)

Objetivo. Monitorear el dinoflagelado Pyrodinium bahamense y sus toxinas en ostión de roca Striostrea prismatica en Santiago Astata y en Puerto Escondido, Oaxaca, de septiembre de 2009 a junio de 2010. Material y métodos. Se analizó mensualmente la abundancia de Pyrodinium bahamense mediante el método de Sedgewick-Rafter y la concentración de toxinas paralizantes y perfil tóxico en tejido blando del molusco en muestras compuestas de cada zona por el método de cromatografía líquida de alta resolución. Resultados. Se encontró alta abundancia de Pyrodinium bahamense en Santiago Astata en diciembre, febrero, abril y junio, y en Puerto Escondido en abril y junio. Los niveles de toxinas paralizantes fueron superiores al límite permisible para consumo humano en Santiago Astata en noviembre, diciembre, enero, febrero y junio; en la zona de Puerto Escondido, en diciembre y junio. Conclusiones. Estos niveles de toxinas representaron riesgo para la salud pública en la zona de estudio.

Objective. Pyrodinium bahamense monitoring in water and their toxins in rock oyster Striostrea prismatica in Santiago Astata and Puerto Escondido Oaxaca was performed from September 2009 to July 2010. Materials and methods. Pyrodinium bahamense abundance in water, and concentration and toxic profile of paralytic shellfish toxins were analyzed monthly in soft tissue of mollusk in composite samples in high performance liquid chromatography. Results. High abundance of Pyrodinium bahamense was found in Santiago Astata on December, February, April and June; and in Puerto Escondido on April and June. The concentrations of the paralyzing toxin that exceeded the regulatory limit for human consumption of mollusks (800 µg STX eq. kg-1) were presented in Santiago Astata on November, December, January, February and June; and in Puerto Escondido on December and June. Conclusions. For several months there was risk to public health due to the presence of paralytic shellfish toxins above the regulatory limit in oysters from the study area.

Double-blind, randomised clinical assay to evaluate the efficacy of probiotics in preterm newborns weighing less than 1500 g in the prevention of necrotising enterocolitis.

BACKGROUND: A randomised, double-blind clinical trial was undertaken in order to assess the effectiveness of probiotics in the prevention of necrotising enterocolitis (NEC) in newborns weighing <1500 g. METHODS: We studied a group of 150 patients who were randomised in two groups after parental consent was obtained, to receive either a daily feeding supplementation with a multispecies probiotic (Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus casei, Lactobacillus plantarum, Bifidobacteruim infantis, Streptococcus thermophillus) 1 g per day plus their regular feedings or to receive their regular feedings with nothing added (control group), over the period of January 2007 through June 2010. Clinicians in care of the infants were blinded to the group assignment. RESULTS: The primary outcome was the development of NEC. Both groups were comparable, with no differences during hospitalisation, including the type of nutrition received. Blood cultures obtained from cases that developed sepsis did not reveal lactobacillus or Bifidobacteria growth. No differences were detected in terms of NEC risk reduction (RR: 0.54, 95% CI 0.21 to 1.39) although we did observe a clear trend in the reduction of NEC frequency in the studied cases: 6 (8%) versus 12 (16%) in the control group. When the combined risk of NEC or death was calculated as a post hoc analysis, we found a significantly lower risk (RR: 0.39, 95% CI 0.17 to 0.87) for the study group. CONCLUSIONS: Probiotics may offer potential benefits for premature infants and are a promising strategy in the reduction of the risk of NEC in preterm newborns.

Accumulation, biotransformation, histopathology and paralysis in the Pacific calico scallop Argopecten ventricosus by the paralyzing toxins of the dinoflagellate Gymnodinium catenatum.

The dinoflagellate Gymnodinium catenatum produces paralyzing shellfish poisons that are consumed and accumulated by bivalves. We performed short-term feeding experiments to examine ingestion, accumulation, biotransformation, histopathology, and paralysis in the juvenile Pacific calico scallop Argopecten ventricosus that consume this dinoflagellate. Depletion of algal cells was measured in closed systems. Histopathological preparations were microscopically analyzed. Paralysis was observed and the time of recovery recorded. Accumulation and possible biotransformation of toxins were measured by HPLC analysis. Feeding activity in treated scallops showed that scallops produced pseudofeces, ingestion rates decreased at 8 h; approximately 60% of the scallops were paralyzed and melanin production and hemocyte aggregation were observed in several tissues at 15 h. HPLC analysis showed that the only toxins present in the dinoflagellates and scallops were the N-sulfo-carbamoyl toxins (C1, C2); after hydrolysis, the carbamate toxins (epimers GTX2/3) were present. C1 and C2 toxins were most common in the mantle, followed by the digestive gland and stomach-complex, adductor muscle, kidney and rectum group, and finally, gills. Toxin profiles in scallop tissue were similar to the dinoflagellate; biotransformations were not present in the scallops in this short-term feeding experiment.

Cadmium, copper, lead and zinc in cultured oysters under two contrasting climatic conditions in coastal lagoons from SE Gulf of California, Mexico.

In order to determine the metal concentrations in cultured oysters from four coastal lagoons from SE Gulf of California, several individuals of Crassostrea gigas and C. corteziensis were collected and their cadmium, copper, lead and zinc levels were measured by atomic absorption spectrometry after acid digestion. The concentration of metals in oyster soft tissue was Zn > Cu > Cd > Pb. In two lagoons, Cd concentrations (10.1-13.5 µg g(-1) dw) exceeded the maximum level allowed according to the Official Mexican Standard (NOM-031-SSA1-1993), which is equivalent to the WHO recommended Cd levels in organisms used for human consumption.

Toxic effect of the harmful dinoflagellate Cochlodinium polykrikoides on the spotted rose snapper Lutjanus guttatus.

The dinoflagellate Cochlodinium polykrikoides isolated from Bahía de La Paz, Gulf of California, showed an important short-term toxic effect on the spotted rose snapper Lutjanus guttatus. This microalga was able to decrease fish liver catalase activity and lipid peroxidation. Fish exposed to live dinoflagellates developed an abnormal mucus secretion on the gills that was directly related to algal cell concentration. Hepatic catalase inhibition and an increase in mucus secretion on the gills occurred when fish were exposed to 2 x 10(6) cells L(-1) of C. polykrikoides. Lipid peroxidation was significantly different at 4 x 10(6) cells L(-1) and the hepatosomatic index decreased at 3 x 10(6) cells L(-1). Our results suggest that oxidative stress contributes, at least in part, to the ichthyotoxic effect of C. polykrikoides from the Gulf of California.

Hemolytic activity and fatty acids composition in the ichthyotoxic dinoflagellate Cochlodinium polykrikoides isolated from Bahía de La Paz, Gulf of California.

The hemolytic activity of the dinoflagellate Cochlodinium polykrikoides from Bahía de La Paz, Gulf of California was investigated as part of the ichthyotoxic mechanism of this microalga. Two different kinds of erythrocytes, fish and human, were tested for the hemolytic assay. Since fatty acids have been associated with hemolytic activity in C. polykrikoides, the composition of fatty acids of this dinoflagellate was also analyzed. The concentration of C. polykrikoides causing 50% hemolysis (HE(50)) was 4.88 and 5.27x10(6) cellsL(-1), for fish and human erythrocytes, respectively. According to the standard curve of saponin, an equivalence between the hemolytic activity of saponin and the dinoflagellate concentration was found with 1mug saponinmL(-1) equivalent to 1x10(6) cellsL(-1) of C. polykrikoides. The polyunsaturated fatty acids: hexadecaenoic (16:0), docosahexaenoic (22:6 n3) and octadecapentaenoic (18:5 n3) were found in an abundance of approximately 62% of total fatty acids.

Toxic and harmful marine phytoplankton and microalgae (HABs) in Mexican Coasts.

Harmful Algal Blooms (HABs) are becoming an increasing problem to human health and environment (including effects on natural and cultured resources, tourism and ecosystems) all over the world. In Mexico a number of human fatalities and important economic losses have occurred in the last 30 years because of these events. There are about 70 species of planktonic and non-planktonic microalgae considered harmful in Mexican coasts. The most important toxin-producing species are the dinoflagellates Gymnodinium catenatum and Pyrodinium bahamense var. compressum, in the Mexican Pacific, and Karenia brevis in the Gulf of Mexico, and consequently the poisonings documented in Mexico are Paralytic Shellfish Poisoning (PSP) and Neurotoxic Shellfish Poisoning (NSP). Although there is evidence that Amnesic Shellfish Poisoning (ASP), Diarrhetic Shellfish Poisoning (DSP) and Ciguatera Fish Poisoning (CFP) also occur in Mexico, these problems are reported less frequently. The type of phytoplankton and epiphytic microalgae, their toxins and harmful effects as well as current methodology used to study these phenomena are presented in this paper. As an experienced group of workers, we include descriptions of monitoring and mitigation programs, our proposals for collaborative projects and perspectives on future research.

Grazing of heterotrophic dinoflagellate Noctiluca scintillans (Mcartney) Kofoid on Gymnodinium catenatum Graham.

A dinoflagellate bloom ("red tide" event) dominated by the toxic Gymnodinium catenatum Graham (Gymnodiniales, Dinophyceae; 99.7%) and the noxious Noctiluca scintillans (Mcartney) Kofoid (Noctilucaceae, Dinophyceae; 0.3%) was observed in Bahia de Mazatlán Bay, México, on 24-26 January 2000. Photographic and microscopic analysis of samples during such an event, allowed us to collect evidence of a marked The particularity of grazing of G. catrenatum by by N. scintillans cells, suggesting a mechanism of "biocontrol" between these species that may contribute to attenuate a potentially toxic phenomenon under natural conditions.

Caracterización de la expresión y función sigM de un factor sigma ECF en micobacterias / Characterization of the expression and function sigM of an ECF sigma factor in mycobacteriums

La supervivencia del bacilo Micobacteria tuberculosis dentro del macrófago depende de su capacidad de responder al stress oxidativa, y los factores sigma, subfamilia ECF, probablemente tienen un rol importante. Investigamos un factor sigma, sigM, cuyos gen se encuentran cerca del origen de replicación. Tanto en M.smegmatis como en M.bovis BCG, la expresión del gen esta inducida en temperaturas altas y en fase estacionaria. Cepas de M.smegmatis sin una copia activa de sigM muestran un defecto en la supervivencia en el stress oxidativo y también en la inducción de la actividad de thioredoxina reductasa, que reduce puentes disulfuricos formado en stress oxidativo. Estos datos sugieren que SigM regula los tioredoxinas y constituye parte de unas respuestas protectivas muy complejos de la bacteria

Interleukinas y embarazo: una realidad cuestionada / Interleukines and pregnancy: a questioned reality

Se revisa la literatura relacionada con el papel que juegan las Interlukinas (ILs) en el embarazo puntualizándose que en el mecanismo de trabajo de parto espontáneo están involucradas estas substancias, las cuales actúan como disparadores de la cascada ácido araquidónico/prostaglandina; este mismo proceso puede activarse por lipopolisacárdios bacterianos implicados en la etiología del parto pretérmino. Normalmente la producción y actividad de la IL-2 esta inhibida para que el embarazo siga un curso normal, si esto no sucede se tendrían problemas de aborto de repetición, la IL-3 conjuntamente con factores estimuladore de crecimiento (FECs) permite el adecuado crecimiento del producto de la gestación si esto se altera habría retardo en el crecimiento intrauterino; a,bas interleukinas actúan a nivel de la interfase materno fetal. Por lo anterior es importante que el ginecoloobstetra tenga una información básica relacionada con ILs y su relación con el embarazo normal y complicado