Hypostomus affinis

Hey, guys!

I'm here to introduce one of the catfishes which is part of our project, the Hypostomus affinis. In Brazil, their popular name can be Cascudo, Acari or Boi-de-Guará. It is a benthic fish and it feeds organic materials, participating in the pre-stage mineralization of organic material in the substrate.

The reproduction of these fish occurs between November and February. This species has a low fertility rate, but strong parental care with its offsprings. The ones we found here in Rio de Janeiro, at the Guandu river, reaches 30 cm in adulthood. The genus Hypostomus is widely distributed in South America. Occurrence of H. affinis are described in several regions of Brazil, but it is probably another case of cryptic species. Species of this genus are an important food source in the Amazon and Pantanal wetlands, besides being economically important in the ornamental aquarium trade.

The video below contains disturbing images, if you are a sensitive person, better not watch it. It describes (in Portuguese) how to clean this fish to be eaten.

That is all for now! Till next time! By the way, none of us have tried this fish (at least yet).

Thioredoxin Superfamily

Hey you !

Are you ready to learn a bit more about a gene superfamily?

Today we will talk about Thioredoxins (TRX), that is class of small proteins characterized for a short sequence of four amino acids (Cys–Xxx–Xxx–Cys)* at their active site. TRX were identified in 1964 in bacterium Escherichia coli, and ever since it has been widely studied. 

Thioredoxins are important molecules involved mainly in the control of cellular reduction/oxidation (redox) balance. Therefore, they are related to oxidative stress and different types of cancer cases, usually showing an elevated expression. The two cysteines (Cys) residues presents in the conserved active site sequence work as an intracellular reductase by a dithiol/disulfide exchange and are responsible for their redox activity. TRX also is associated with others biological processes as gene expression and signal transduction in all organisms.

In our analysis Pterygoplichthys transcriptome, we found 3 differents types of TXN (TMX, TXN and TXNDC) but they have practically the same functions. The basic difference is the local where are expressed and found in cell. The most abundant of those types in the transcriptome of Pterygoplichthys was TXNDC, with 13 distinct transcripts.

Got interested in Thioredoxins? Learn more with this nice review: Multiple catalytically active thioredoxin folds: a winning strategy for many functions .

*Cys - amino acid cysteine

Xxx - some amino acid

A little about Loricariidae...

Hey guys,

I'm here to write about the Loricariidae family, that is part of the Siluriformes order. In Brazil, fish of this family are known as Cascudo and are characterised by having bony plates covering their bodies, a ventral mouth with papillae on the lips and body characteristically depressed.

Photo from a great paper from our colleague Nathan Lujan.
http://www.biomedcentral.com/1471-2148/12/124

This fish family has wide distribution in the neotropics and a great ecological importance, as they have a crucial role in nutrient cycling in neotropical aquatic ecosystems. In addition, they also have great socioeconomic importance. They are important food source for Amazonian communities and, with its exotic beauty, internationally used for ornamental purposes, as aquarium fish. However, this often represent a threat to these species due to overexploitation and international fish traffic of endangered species. In fact, the international trade of those and other Brazilian fish species are regulated by IBAMA, our environmental agency.

Now you all know a little more about those cute fish which we work. In others posts in this blog, we'll talk about some species that are part of our project. I hope you like this publication, till next post!

Nuclear receptors

Today we will talk about one of the gene superfamilies that we are working; the Nuclear Receptors (NRs).

The NRs are transcription factors, which act as a translator of environmental stimuli to the molecular language of the cells. They function as receptors of hormones and others endogenous and exogenous molecules like vitamin D and several pollutants. By interacting with regulatory regions of target genes to perform its various functions in homeostasis, playing important roles in the regulation of cell growth, development, basic metabolism of metazoans. The NRs have the ability to directly bind to DNA and regulate gene expression of other genes.

All nuclear receptors share a similar organisation classified in six homolog regions, but just two of these regions are very conserved: the DNA-binding domain (DBD) (region C) and the ligand-binding domain (LBD) (region E). The most conserved is the region C that contain two zinc fingers that binds to specific sequences of DNA. These zinc fingers are used to find the P-box that characterises this region and confers specificity to a target region of  the DNA.
Region E is also conserved, but has more aminoacids changes than region C, therefore is classified as a moderately conserved sequence.

http://en.wikipedia.org/wiki/Nuclear_receptor

In our first analyzed transcriptome, the Pterygoplichthys anisitsi, we found 13 different transcripts (mRNA) of NRs and we had succeed in the identification of the domains C and E in all these mRNA. Sure things; we accomplished this after reading tons of papers to learn about the Nuclear Receptors. So, we will continue working hard for more posts like this.

I hope you enjoyed. See you soon!