2 research outputs found
Determination and Occurrence of Retinoids in a Eutrophic Lake (Taihu Lake, China): Cyanobacteria Blooms Produce Teratogenic Retinal
Besides retinoic acids (RAs), some retinoids such as
retinal (RAL)
and retinol (ROH), which are considered as RA precursors in vertebrates,
are also reported to be teratogenic agents. In this study we investigated
four RA precursors including RAL, ROH, retinyl palmitate, and β-carotene
in the eutrophic Taihu Lake, China, by developing a sensitive analytical
method. RAL and β-carotene were widely detected in natural cyanobacteria
blooms and lake water. Intracellular concentrations of RAL and β-carotene
in blooms were 9.4 to 6.9 × 10<sup>3</sup> and 3.4 to 1.8 ×
10<sup>5</sup> ng L<sup>–1</sup>, respectively, and their concentrations
in lake water were up to 1.4 × 10 ng L<sup>–1</sup> (RAL)
and 9.8 × 10<sup>2</sup> ng L<sup>–1</sup> (β-carotene).
The good correlation between intracellular concentrations of RAL and
RAs implied that RAL was involved in the production of RAs by cyanobacteria
blooms. Further examination of 39 cyanobacteria and algae species
revealed that most species could produce RAL and β-carotene.
The greatest amount of RAL was found in <i>Chlamydomonas</i> sp. (FACHB-715; 1.9 × 10<sup>3</sup> ng g<sup>–1</sup> dry weight). As the main cyanobacteria in Taihu Lake, many <i>Microcystis</i> species could produce high amounts of RAL and
were thought to greatly contribute to the production of RAL measured
in the blooms. Productions of RAL and β-carotene by cyanobacteria
were associated with species, origin location, and growth stage. The
results in this study present the existence of a potential risk to
aquatic animals living in a eutrophic environment from a high concentration
of RAL in cyanobacteria blooms and also provide a clue for further
investigating the mechanism underlying the biosynthetic pathway of
RAs in cyanobacteria and algae
Biosensor Medaka for Monitoring Intersex Caused by Estrogenic Chemicals
Estrogenic
chemicals can induce intersex in fish species leading
to disturbance of spermatogenesis and impairment of reproductive success.
To overcome the shortcomings of conventional histopathological observation
on intersex (low sensitivity, relatively poor accuracy, long experimental
periods, as well as laborious and time-consuming), we generated a
pMOSP1-EGFP transgenic medaka fish model. In this transgenic fish,
the green fluorescence protein (GFP) reporter gene was derived by
the regulatory elements of the OSP1 gene, which is a specific and
sensitive molecular biomarker for indicating intersex occurrence in
male medaka fish exposed to estrogenic chemicals. The transgenic GFP
was faithfully expressed in ovaries and in testes with intersex, perfectly
mimicking the expression pattern of endogenous OSP1. In intersex testis,
the diameters of primary oocytes which could be distinguished by GFP
fluorescence observation were as small as 10 μm, lower than
that (more than 20 μm) which is observable by histopathology.
Using the novel transgenic medaka fish, intersex was observed after
90-day exposure to 0.75 ng/L 17α-ethinyloestradiol (EE<sub>2</sub>) (0–90 dph), but only at concentrations of at least 1.38
ng/L EE<sub>2</sub> by histopathology. An effectiveness of a short-term
in vivo assay for screening estrogenic chemicals that can monitor
intersex appearance at early sex developmental stage (about 30 dph)
in male medaka fish was also demonstrated by assessing the intersex
induction of EE<sub>2</sub>, 17β-estradiol and 4-nonylphenol.
This newly developed assay provides an enhanced ability for screening
and testing estrogenic chemicals with the potential to induce intersex
and studying their biological impacts