Sergio Alvarez Hernández

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• MS EXPERIMENTAL BIOLOGY
• Professor at Metropolitan Autonomous University

The striped mullet Mugil cephalus is a species of high commercial value with a spawning season that spans from autumn to winter in coastal areas of the northern Gulf of Mexico. The objec- tive of this project was to study an annual cycle of monthly stages of M. cephalus sexual maturity in two southern Gulf of Mexico localities during 2018, to compa...

Background: Organic agriculture is based on the optimal use of natural resources, which helps to increase the biological activity of the soil naturally without using chemical compounds that can alter the soil, crops and aquifers. Some macroalgae have the potential to be used as bio-stimulants or soil conditioners. Goals: evaluate the potential of m...

Antecedentes. Las microalgas y cianobacterias son fuente potencial de nuevas aplicaciones con actividad biológica. En nuestro país la investigación de aplicaciones de estos organismos es incipiente aún. Objetivo. Probar el potencial de algunas especies de microalgas y cianobacterias como aglutinantes de eritrocitos (presencia de lectinas) y bacteri...

The toxic effect of cadmium, chromium, copper, mercury, manganese, nickel and lead on adult Acanthocyclops americanus copepods was evaluated to determine the sensitivity of this species to these metals. Toxicity tests were carried out to determine the LC50, after which bioassays were carried out with environmentally relevant sublethal concentration...

Macroalgae synthesize molecules that may be toxic to other organisms. These molecules are synthesized as a defense strategy against herbivores. It has been proven that the synthesis process is directed by several physiological, chemical and even spatial-temporal variables. The purpose of this study was to determine whether the complexity of the hab...

Harmful algal blooms (HABs) have recently attracted the attention of local people, authorities, and scientists. This is because of the important and negative consequences they have on the environment, economy, and health. One aspect of this interest is the possibility of knowing the mechanisms that trigger this phenomenon and therefore being able t...

Mexico has long littorals that receive great amounts of marine algae that are wasted despite being potentially useful as growth promoters without the inconveniences of agrochemicals. Some macroalgae have been used with excellent results as soil conditioners and fertilisers in agriculture. In this study nine macroalgae from the coasts of Veracruz (G...

Oreochromis niloticus has been introduced worldwide into freshwater reservoirs and represents an alternative food for local populations. Two annual marks on fish scales have been reported for fish in these environments, one of them is allocated to reproduction, while the other is thought to be formed following low temperatures, a reduction in oxyge...

The effectiveness of discrimination of phenotypic stocks was compared between otolith and scale shapes for Mugil curema specimens collected at five different locations in the Gulf of Mexico and two locations along the Pacific coast during two consecutive years. Geometric morphometric methods were used to determine the discrimination among locations...

Sulfate-reducing bacteria (SRB) and methanogenic archaea (MA) share common niches in coastal sediments during the terminal phases of the anaerobic mineralization of organic matter. The purpose of this study was to analyze the spatial - temporal variation of SRB and MA in the sediments of a tropical coastal lagoon with ephemeral inlet (La Mancha, Ve...

diversidad, microalgas, dulceacuicolas.

In Chantuto-Panzacola coastal system, located in the “La Encrucijada” Biosphere Reserve microbio- logical quality and pollution by polycyclic aromatic hydrocarbons () in sediments were analyzed. e physicochemical variable like temperature, salinity, pH, and dissolve oxygen were characteristics from tropical coastal environments. In the dry seaso...

The relative growth of Cherax quadricarinatus (Von Martens, 1868) males and females under laboratory conditions was analysed using eight somatic measurements. The allometry of each measurement was estimated in relation to total length. The morphometrics were analysed using the original values, as well as normalized data from each group. Two multiva...

One of the most exceptional and multifunctional habitats for cryptic and epibenthic fauna has been established in the costal zones of Magdalena Bay conforming an interesting interaction between rhodoliths and marine sponges. These function primarily as refuges, where the rhodolith beds (red coralline algae) grow in association with a high biodivers...

Seventy-three species of macroalgae from the Mexican Pacific, Atlantic and Caribbean coast were screened for ichtyotoxic activity. Ethanolic, acetonic and aqueous extracts were prepared and tested against the fish Carassius auratus. The extracts were classified on the basis of their effects as: toxic if the fish died in two hours or less; moderatel...

Some microalgae are economically important in Mexico and the world because they can be potentially toxic. Algal explosive population growths are named harmful algal blooms and are frequently recorded in Mexico. The authors set up potentially toxic microalgae cultures from the Gulf of Mexico (Garrapatas tideland, Barberena river, Carpintero lagoon i...

A phylogenetic analysis of the Prorocentrum species is presented, that includes the sequences of the large and small ribosomal RNA subunits from 19 cultures from 13 of the 20 species reported in the Pacific coast of Mexico; the results showed that P. micans, P. gracile and P. mexicanum were the closest of species, that planktonic may be more recent...

A phylogenetic analysis of the Prorocentrum species is presented, that includes the sequences of the large and small ribosomal RNA subunits from 19 cultures from 13 of the 20 species reported in the Pacific coast of Mexico; the results showed that P. micans, P. gracile and P. mexicanum were the closest of species, that planktonic may be more recent...

The coagulation disorders have increased in the last decades and no new substances had been discovered that could regulate this illness. This fact makes the discovery of new anticoagulant substances a priority issue in research. Forty nine seaweed species collected off shore of several localities of Gulf of Mexico and Mexican Caribbean sea were scr...

The coagulation disorders have increased in the last decades and no new substances had been discovered that could regulate this illness. This fact makes the discovery of new anticoagulant substances a priority issue in research. Forty nine seaweed species collected off shore of several localities of Gulf of Mexico and Mexican Caribbean sea were scr...

A phylogenetic model for the selection of commercial resources using the cladistic method is proposed. The group selected as an example was the marine agarophyte red algal genus Gracilaria Greville. We suggest the use of the cladistic principle of evolutionary transformational series in order to test the quality of agars instead of the assay-herror...

Resumen Se utilizó Giraffina, una lectina aislada de Codium giraffa (Chlorophyta), para separar dos variedades y un híbrido de tilapias del género Oreochromis: O. niloticus (variedad roja y Stirling) y rocky mountain, hibrido producto de O. aureus x O. niloticus. Se obtuvo la sangre de las tilapias por medio de punción cardíaca y los ensayos de agl...

In order to separate two strains of tilapia Oreochromis) of O. niloticus (red and stirling strains) and rocky mountain hybrid (O. aureus x O. niloticus) the lectin giraffine isolated from Codium giraffa (Chlorophyta) was used. Fish blood was obtained by cardiac puncture and prepared as a 2 % suspension in phosphate buffer 100 mM, pH 7.2. At all cas...

Some species of the genus Gracilaria Greville (Gracilariales, Rhodophyta) are the main source of agar. For that reason, the taxonomic study of the taxon has become relevant for many scholars. In order to bring the Mexican floristics knowledge of the genus into the state-of-the-art about it, we have initiated the needed monography. The character def...

The presence or absence of secondary metabolites in algae has been long discussed. There are several hypotheses to explain the synthesis of secondary metabolites in algae as a response to herbivory pressure, competence or predation. In this work we made a screening test of chlorophyte and rhodophyte species collected in different sites of the Carib...

A lectin from the alga Codium giraffa, reported as an endemic species of Mexico, was purified by a combina-tion of ammonium sulfate fractionation, affinity and anion exchange chromatographies. Giraffine, as we called this lectin, shares some characteristics with other lectins isolated from the same genus. It is a monomeric protein with a relative m...

Liquid sheep and cow manures were tested as alternative culture media for the growth of three species of Chlorella (Chlorophyta), and the efficiency of each was compared with that of the Bold-Basal medium. The efficiency of the three media was tested considering the cell density, the chlorophyll concentration and the nutritional value of the cultur...

Las Icetinas son proteínas o glicoproteínas que unen selectivamente azúcares. La inhibición del efecto aglutinante se ha utilizado como criterio de detección para estas moléculas. Se realizaron pruebas de aglutinación con eritrocitos humanos de los tipos O, A y B positivos probando como aglutinantes extractos de 44 muestras algales que correspondie...