Mario Alberto Burgos-Aceves

Estrogen regulation of gene expression in the teleost fish immune system.

Elucidating the mechanisms of estrogens-induced immunomodulation in teleost fish is of great importance due to the observed worldwide continuing decrease in pristine environments. However, little is know about the immunotoxicological consequences of exposure to these chemicals in fish, or of the mechanisms through which these effects are mediated. In this review, we summarize the results showing estrogens (natural or synthetic) acting through estrogen receptors and regulating specific target genes, also through microRNAs (miRNAs), leading to modulation of the immune functioning. The identification and characterization of miRNAs will provide new opportunities for functional genome research on teleost immune system and can also be useful when screening for novel molecule biomarkers for environmental pollution.

An approach to the study of the immunity functions of bivalve haemocytes: Physiology and molecular aspects

The Mediterranean mussel Mytilus galloprovincialis is an ecologically and economically important species. It has been used in programs of monitoring of pollution, since it is sessile organism that is capable of accumulating pollutants in tissues through filter feeding. Due to an increase of pollutants in the environment, marine mussels present physiological alterations that compromise their innate immune system, which can latter lead to opportunistic diseases. The haemocytes are the cells in charge of the immune response in the Mediterranean mussel and in other mollusks. In this review, we summarize the physiological and genetic response capacity of these immune cells to the presence of xenobiotics, pathogens and the interplay. The identification of the basic mechanisms of immunity and their modulation in mussels can give important information for the possible utilization of this species as an invertebrate model for studies on innate immunity, future immunotoxicological studies, and predict changes in the community for the future.

A potential microRNA regulation of immune-related genes in invertebrate haemocytes

Bivalve mollusks have been employed as sentinel organisms in environmental health programs due to their sedentary lifestyle, filter-feeding behavior and their ability to accumulate pathogens or toxin molecules inside tissues. Endocrine disrupting chemicals (EDCs) can be up taken and bioaccumulated, and due to sensibility of mollusks to these EDCs, being able to cause immune alterations. Recently, microRNAs (miRNAs) were shown to be involved in modulation and buffering developmental processes against the effects of environmental alterations and pathogenic microorganisms. Moreover, it is suggested that this miRNAs are incorporated into the estrogen-controlled immune network, regulating mechanism of immune gene expression at the posttranscriptional level, modulating immune responses as phagocytosis, redox reaction and apoptosis in bivalve haemocytes. Thus, miRNAs can be used as biomarkers that specifically elucidate immunotoxic effects caused by exogenous biotic or abiotic factors, and can act as useful tools in integrated monitoring environmental health programs. In this review, we aim to describe the investigations that have been carried out on miRNAs in bivalve mollusks, especially those associated with immune responses against infectious agents and xenobiotic exposure.

Estrogen repression of microRNA as a potential cause of cancer

MicroRNAs (miRNAs) are endogenous small molecules that regulate gene expression and have been implicated in the pathogenesis of many human diseases, including cancer. This review describes the results that show a global repression in miRNA expression in various tumors and cancer cell lines. Intriguingly, recent discoveries have shown a widespread downregulation of miRNA after exposure to the steroid hormone estrogen. The integration of the results suggests that estrogen-dependent repression of miRNA is a potential cause of cancer.

Description of peripheral blood cells and differential blood analysis of captive female and male leopard grouper Mycteroperca rosacea as an approach for diagnosing diseases

The peripheral blood cells and differential blood profile of captive female and male leopard grouper Mycteropercarosacea are described for aquacultural purposes. Basophilic, polychromatic, and orthochromic erythroblasts were observed as immature erythrocytes that develop into mature erythrocytes. Young erythrocytes were not evident, and bi-lobed erythrocytes were extremely scarce. Types of leukocytes included lymphocytes; three types of granulocytes (basophiles, eosinophiles, and neutrophiles); monocytes; and a specialized amoeboid-like macrophage in the blood, which has not been previously described in fish-blood literature. Thrombocytes were commonly observed. There was significantly higher erythropoiesis in males. Granulocytes and lymphocytes of females were significantly higher than males, whereas monocytes and thrombocytes were not.

A potential role for estrogen in cigarette smoke-induced microRNA alterations and lung cancer

Alteration in the expression of microRNAs (miRNAs) is associated with oncogenesis and cancer progression. In this review we aim to suggest that elevated levels of estrogens and their metabolites inside the lungs as a result of cigarette smoke exposure can cause widespread repression of miRNA and contribute to lung tumor development. Anti-estrogenic compounds, such as the components of cruciferous vegetables, can attenuate this effect and potentially reduce the risk of lung cancer (LC) among smokers.

Estrogen Repression of MicroRNAs Is Associated with High Guanine Content in the Terminal Loop Sequences of Their Precursors

Widespread microRNA (miRNA) repression is a phenomenon observed in mammals after exposure to cigarette smoke and in many types of cancer. A comprehensive reduction in miRNA expression after treatment with the hormone estrogen has also previously been described. Here, we reveal a conserved association of miRNA downregulation after estrogen exposure in zebrafish, mouse, and human breast cancer cell line, with a high guanine content in the terminal loop sequences of their precursors, and offer a possible link between estrogen-related miRNA-adducts formation and carcinogenesis. We also show common gene expression patterns shared by breast cancer tumors and estrogen-treated zebrafish, suggesting that this organism can be used as a powerful model system for the study of human breast cancer.

BIOCHEMICAL AND HISTOCHEMICAL CHANGES ASSOCIATED WITH GONAD DEVELOPMENT OF THE CORTEZ GEODUCK, PANOPEA GLOBOSA (DALL 1898), FROM THE GULF OF CALIFORNIA, MEXICO

ABSTRACT Thirty adult organisms of Panopea globosa, an endemic geoduck species from Baja California, Mexico, were collected monthly during a maturation cycle (October through January). Histological and semiquantitative histochemical changes (total lipids and carbohydrates) were assessed in gonad tissue during the maturation process. Biochemical quantification of proteins, lipids, carbohydrates, vitellogenin, and vitellin was performed on hemolymph and gonad tissues of all specimens. The theoretical diameter of oocytes was also estimated from their surface area, measured in histological sections of gonads. Five distinct gonadal stages were identified in both male and female geoducks, with previtellogenic (PVt)/early spermatogenic (ES) gonads being observed in October. Spawning took place in December/January when the temperature reached a plateau of ∼18.5°C. Oocyte diameter varied between 25.5 µm(PVt stage) and 74.8 µm during the late vitellogenic stage (LVt). The percent of lipids and carbohydrates evaluated histochemically in females closely mirrored the gonadal stages, as well as the diameter. Quantitative changes in proteins, lipids, and carbohydrates in the hemolymph did not show a clear temporal pattern, yet the level of vitellogenin increased from 16.4 (PVt stage)—47.8 µg/mL (LVt stage) and correlated with the oocyte diameter. The weightspecific content of proteins, lipids, and carbohydrates in the gonads was significantly greater during PVt and ES than the other gonadal stages, and remained relatively constant thereafter. Vitellin content mirrored the evolution of each maturation stage and correlated significantly with oocyte diameter. Vitellogenin or vitellin can be used as a reliable quantitative index of gender and degree of gonadic maturity in females. Hemolymph can be obtained readily from the pericardial cavity without affecting the performance of the organism significantly, which further makes vitellogenin a valuable, nonlethal marker for this genus.

Leukophilia during maturation of the leopard grouper Mycteroperca rosacea

Abstract In spring, peripheral blood of mature-ripe female leopard groupers showed leukophilia after an increase of lymphocytes and thrombocytes, followed by a differential increase of monocytes and granulocytes. In mature-ripe males, granulophilia and thrombophilia were evident. Leukocytes were distinguishable in some ovarian blood vessels where post-ovulatory follicles were present. These observations suggest coordination of endocrine-immune activity, where, after one spawning event, leukocytes infiltrate the gonad tissue from the peripheral blood to aid with immune surveillance and phagocyte activity, while a feedback of sex steroids and vitellogenesis occurs in preparation for the next spawning. An abundance of leukocytes may also aid in gonad reabsorption during post-spawning. Leukophilia coincided with high plasma concentrations of oestradiol and testosterone, which together with leukocytes, decreased greatly in immature-active groupers in summer. Blood cell counts, erythroblasts, and haematocrit of mature-ripe groupers in spring were significantly lower than immature-active groupers in summer, suggesting mild anorexia induced by reproductive behaviour.

Validation of an enzyme‐linked immunosorbent assay for measuring vitellogenin in california halibut (Paralichthys californicus)

Vitellogenin (VTG) is the major protein present in the plasma of females undergoing oogenesis. In males, the VTG gene normally is suppressed; however, synthesis of VTG can be induced by exposure to xenoestrogenic compounds. In the present study, an enzyme-linked immunosorbent assay was developed and validated to evaluate VTG levels in the California halibut (Paralichthys californicus). Vitellogenin and lipovitellin (LV) were identified in the plasma of 17 beta-estradiol-induced females and in the ovaries of wild females, to our knowledge for the first time. Purified VTG from the plasma of induced females was obtained, and polyclonal antibodies against the LV of mature female ovaries was prepared and their specificity assessed by Western blot analysis. At Bahia Magdalena, Baja California Sur, Mexico, quantitative measurements of VTG in the plasma of female specimens were made during one reproductive cycle.