Biological responses of shoal flounder (Syacium gunteri) to toxic environmental pollutants from the southern Gulf of Mexico.

The Gulf of Mexico (GoM) is exposed to a diversity of contaminants, such as hydrocarbons and heavy metal(oid)s, either from natural sources or as a result of uncontrolled coastal urbanisation and industrialisation. To determine the effect of these contaminants on the marine biota along the Mexican GoM, the biological responses of the shoal flounder Syacium gunteri, naturally exposed, were studied. The study area included all the Mexican GoM, which was divided into three areas: West-southwest (WSW), South-southwest (SSW) and South-southeast (SSE). The biological responses included the global DNA methylation levels, the expression of biomarker genes related to contaminants (cytochrome P450 1A, glutathione S-transferase, glutathione reductase, glutathione peroxidase, catalase, and vitellogenin), histopathological lesions and PAH metabolites in bile (hydroxynaphthalene, hydroxyphenanthrene, hydroxypyrene and Benzo[a]pyrene). The correlation between the biological responses and the concentration of contaminants (hydrocarbons and metal(oid)s), present in both sediments and organisms, were studied. The shoal flounders in WSW and SSW areas presented higher DNA hypomethylation, less antioxidative response and biotransformation gene expression and a higher concentration of PAH metabolites in bile than SSE area; those responses were associated with total hydrocarbons and metals such as chromium (Cr). SSE biological responses were mainly associated with the presence of metals, such as cadmium (Cd) and copper (Cu), in the tissue of shoal flounders. The results obtained on the physiological response of the shoal flounder can be used as part of a permanent active environmental surveillance program to watch the ecosystem health of the Mexican GoM.

Partial mRNA Sequences of the Biomarkers CYP1A, GST, CAT, GR, SOD, GPx, VTG and p53 in Flatfish Syacium gunteri from Gulf of Mexico.

The present study reports partial sequences of a group of genes used as exposure and effect biomarkers of organic contaminants and/or heavy metals in Syacium gunteri. In order to isolate these sequences, cDNA was used to amplify fragments between 200 and 800 bp, which were then cloned and sequenced. The sequences presented high percentages of identity with genes involved in the metabolism of xenobiotic biotransformation (cytochrome P4501A and glutathione S-transferase), oxidative stress (catalase, glutathione reductase, glutathione peroxidase and superoxide dismutase), reproductive system (vitellogenin) and with the tumor suppressor protein p53 reported in the GenBank database. Subsequently, from the deduced sequence of amino acids of each fragment, their tridimensional structure was predicted, using homologous proteins from the Protein Data Base. This study generates an important base of molecular biomarkers for the monitoring of environmental health in the Gulf of Mexico.

A quantitative PCR approach for determining the ribosomal DNA copy number in the genome of Agave tequila Weber

Background: Agave tequilana has a great economic importance in Mexico in order to produce alcoholic beverages and bioenergy. However, in this species the structure and organization of the rDNAs in the genome are limited, and it represents an obstacle both in their genetic research and improvement as well. rDNA copy number variations per eukaryotic genome have been considered as a source of genetic rearrangements. In this study, the copy number of 18S and 5S rDNAs in the A. tequilana genome was estimated, and an absolute quantitative qPCR assay and genome size was used. In addition, an association between the rDNAs copy number and physical mapping was performed to confirm our results. Results: The analysis were successfully applied to determine copy number of 18S and 5S rDNAs in A. tequilana genome, showing high reproducibility with coefficient of variation (CV) values of 0.014-0.0129%, respectively. A variation of 51 times in the copy number the 18s regarding 5s rDNA was found, thus contributing to genome size of 1.47 and 8.38 x 10-3%, respectively. Similarly, data show a linear relationship (R [2] = 0.992) between rDNA copy number and the detected signals for each of the loci by FISH. The comparison of the rDNA copy number of agave showed differential relationship with other organisms and it may be due to evolutionary ecology.Conclusions: Results show that the proposed method a) can correctly detect the rDNA copy number, b) could be used as species-specific markers and c) might help in understanding the genetic diversity, genome organization and evolution of this species.

Diets containing sea cucumber (Isostichopus badionotus) meals are hypocholesterolemic in young rats.

Sea cucumber is widely consumed as a putative functional food. It contains many biologically-active substances, but only limited research on its properties in vivo has been done. The effects of different meals containing Isostichopus badionotus, a sea cucumber from southeast Mexico, on growth performance and body lipid profile in young rats were analyzed. Sea cucumber body wall was either lyophilized, cooked (100 °C, 1 h in water) and lyophilized, or oven-dried (70 °C for 12 h). It was then ground and incorporated into cholesterol-containing diets. I. badionotus meals supported growth and improved lipid profile in rats. In particular, serum cholesterol, low density lipoproteins, triglycerides concentration and atherogenic index values were greatly reduced by some I. badionotus containing diets. Liver total lipids, triglycerides and cholesterol were also reduced. Cooking or heat-treatment of the meals lowered but did not abolish their hypolipidemic potency. Gene expression analysis of several key genes involved in cholesterol and lipid metabolism in liver showed that diets containing I. badionotus repressed the induction of key genes associated with dyslipidemia exerted by cholesterol supplementation. Consumption of I. badionotus from the Yucatan Peninsula is beneficial for dyslipidemia, although biological effect is clearly dependent on preparation method.

Pharmaceutical applications of the benzylisoquinoline alkaloids from Argemone mexicana L.

Argemone mexicana L. (Papaveraceae), accumulates benzylisoquinoline alkaloids, (BIA) derived from tyrosine. Although it was originated in the western region of the USA-Mexico border, it has spread to tropical and subtropical areas around the world. Today, it is used to treat different ailments, given to its antimicrobial, antiparasitic, antimalarial, pesticide, cytotoxic and neurological properties. These effects are related to the presence of different types of BIA's, such as benzophenanthridines (sanguinarine, chelerythrine), protoberberines (berberine) and protopines (protopine, allocryptopine). This review covers the historical medicinal uses of A. mexicana, as well as its current applications. The chemical bases of such effects are discussed in relation to the occurrence of the different types of alkaloids. The biochemical process involved in the synthesis of these types of alkaloids is also described.

Establishment of a sanguinarine-producing cell suspension culture of Argemone mexicana L (Papaveraceae): induction of alkaloid accumulation.

A protocol for the induction of a cell suspension culture of Argemone mexicana is described. This suspension has been kept for over 3 years producing sanguinarine, a benzophenanthridine-type alkaloid. Sanguinarine levels can be increased by exposing these cultures to yeast or fungal elicitation.

The sequential exposure to jasmonate, salicylic acid and yeast extract promotes sanguinarine accumulation in Argemone mexicana cell cultures.

The effects of the sequential application of methyl jasmonate (MeJa), salicylic acid (SA) and yeast extract (YE) to Argemone mexicana cell cultures were compared to either the sole application of each elicitor, or to the three-partite mixture. The highest sanguinarine accumulation occurred using the sequential treatment (ninefold over unexposed control cultures), followed by the single application of YE (fivefold). The elicitor mixture produced less sanguinarine than sole exposure to YE but higher than MeJa alone. SA did not produce any effect. Transcripts corresponding to tyrosine decarboxylase and berberine bridge enzyme accumulated in treated cells, but did not correlate with alkaloid accumulation. Discrete epifluorescence foci, surrounding the nucleus and scattered throughout the cytoplasm of elicited cells, suggested the presence of alkaloid-accumulating vesicles which could participate in a mechanism to avoid sanguinarine toxicity.

Fusarium oxysporum homogenates and jasmonate induce limited sanguinarine accumulation in Argemone mexicana cell cultures.

In vitro cultures of Argemone mexicana (Papaveraceae) were induced from leaves of mature plants. Sanguinarine, a benzophenanthridine, was the main alkaloid in the cultures, even in the absence of inducers of secondary metabolism. The accumulation of this metabolite was increased by adding methyl jasmonate and fungal elicitors, although in a limited fashion in comparison to other sanguinarine-producing species. Evidence of a transport mechanism, which may be related to the magnitude of the response, was obtained based on the fluorescent properties of bezophenathridines in the elicited cultures.

Isolation of functional total RNA from Argemone mexicana tissues

RNA extraction from recalcitrant plant tissues is frequently complicated by the presence of secondary metabolites, polysaccharides and polyphenols. These compounds may co precipitate with RNA, often rendering it unsuitable for either cDNA synthesis or hybridization in northern blot analyses and therefore, interfering with the gene analysis expression in such tissues. We have developed an efficient RNA extraction method from A. mexicana tissues. The procedure includes the use of polyvinylpolypyrrolidone (PVPP), to remove secondary metabolites, proteins and polyphenols, and a two-step precipitation with LiCl, to eliminate polysaccharides, and thus increasing RNA yield. The quality of the resulting RNA was evaluated spectrophotometrically and by agarose gel electrophoresis. Moreover, the RNA obtained by this method, could be used directly for both RT-PCR and northern blot analysis, without any further purification.