Effects of the juçara fruit (Euterpe edulis Martius) pulp and lyophilized extract on NRF2, KEAP1, SOD1, and GPX2 expression in human colorectal cancer cell lines

We investigated the effects of the juçara fruit (Euterpe edulis Martius) pulp and lyophilized extract on the expression of cytoprotective genes nuclear factor erythroid 2 (NF-E2)-related factor 2 (NRF2), kelch-like ECH-associated protein 1 (KEAP1), superoxide dismutase (SOD1), and glutathione peroxidase (GPX2) in human colorectal cancer cell lines (HT-29 and Caco-2). Cells were cultured for 24 h in Dulbecco's Modified Eagle's Medium containing juçara fruit pulp (5, 10, or 50 mg/mL) or lyophilized extract (0.05, 0.1, or 0.5 mg/mL), and gene expression was quantified using real-time quantitative reverse transcription polymerase chain reaction. All studied genes showed significant variation in gene expression among different concentrations of pulp or lyophilized extract. Overall, the expression of the selected genes decreased in both cell lines following exposure to the pulp or lyophilized extract in a dose-dependent manner for most of the concentrations studied. In summary, our study showed that the compounds in juçara fruit inhibited the expression of cytoprotective genes associated with the antioxidant response and that, although not cytotoxic at the concentrations studied, they could potentially block the activation of the NRF2/KEAP1 pathway.

Myriapod haemocyanin: the first three-dimensional reconstruction of Scolopendra subspinipes and preliminary structural analysis of S. viridicornis

Haemocyanins (Hcs) are copper-containing, respiratory proteins that occur in the haemolymph of many arthropod species. Here, we report the presence of Hcs in the chilopode Myriapoda, demonstrating that these proteins are more widespread among the Arthropoda than previously thought. The analysis of transcriptome of S. subspinipes subpinipes reveals the presence of two distinct subunits of Hc, where the signal peptide is present, and six of prophenoloxidase (PPO), where the signal peptide is absent, in the 75 kDa range. Size exclusion chromatography profiles indicate different quaternary organization for Hc of both species, which was corroborated by TEM analysis: S. viridicornis Hc is a 6 × 6-mer and S. subspinipes Hc is a 3 × 6-mer, which resembles the half-structure of the 6 × 6-mer but also includes the presence of phenoloxidases, since the 1 × 6-mer quaternary organization is commonly associated with hexamers of PPO. Studies with Chelicerata showed that PPO activity are exclusively associated with the Hcs. This study indicates that Scolopendra may have different proteins playing oxygen transport (Hc) and PO function, both following the hexameric oligomerization observed in Hcs.

Rondonin an antifungal peptide from spider (Acanthoscurria rondoniae) haemolymph

Antimicrobial activities were detected in the haemolymph of the spider Acanthoscurrria rondoniae. A novel antifungal peptide, rondonin, was purified by reverse phase high performance liquid chromatography (RP-HPLC). Rondonin has an amino acid sequence of IIIQYEGHKH and a molecular mass of 1236.776 Da. This peptide has identity to a C-terminal fragment of the "d" subunit of haemocyanin from the spiders Eurypelma californicum and Acanthoscurria gomesiana. A synthetic peptide mimicking rondonin had identical characteristics to those of the isolated material, confirming its sequence. The synthetic peptide was active only against fungus. These data led us to conclude that the antifungal activity detected in the plasma of these spiders is the result of enzymatic processing of a protein that delivers oxygen in the haemolymph of many chelicerate. Several studies have suggested that haemocyanins are involved in the arthropod immune system, and the activity of this haemocyanin fragment reinforces this idea.

Spidroins from the Brazilian spider Nephilengys cruentata (Araneae: Nephilidae)

Spiders produce up to six different kinds of silk, each one for a specific biological function. Spider silks are also known for their unique mechanical properties. The possibility of producing new materials with similar properties motivated research on these silk proteins (spidroins). Using expression sequence tags, we identified four spidroins produced by major ampullate, minor ampullate, flagelliform and tubuliform silk glands from the Brazilian spider Nephilengys cruentata (Araneae: Nephilidae). The new protein sequences showed substantial similarity to other spidroins previously described, with high content of alanine and glycine due to the presence of the highly repetitive motifs (polyAla, (GA)n, (GGX)n, (GPGGX)n). Similarities among sequences were also observed between the different spidroins with the exception of tubuliform spidroin, which presents a unique complex amino acid sequence with high amounts of serine and low amounts of glycine.

The Musca domestica larval hexamerin is composed of multiple, similar polypeptides

The Musca domestica larval hexamerin (MdHex-L) is a hexameric glycoprotein with an apparent native molecular weight of 500 kDa. Seven different cDNAs that encode MdHex-L subunits were cloned and sequenced. Furthermore, amino acid sequences of isolated subunits were determined by the Edman degradation method and compared to the conceptual translation products derived from the cloned cDNAs. The obtained data indicate the existence of multiple forms of MdHex-L subunits and that these multiple forms may be grouped into three categories according to their percentages of nucleotide sequence identity.

Isolation and characterization of gomesin, an 18-residue cysteine-rich defense peptide from the spider Acanthoscurria gomesiana hemocytes with sequence similarities to horseshoe crab antimicrobial peptides of the tachyplesin family

We have purified a small size antimicrobial peptide, named gomesin, from the hemocytes of the unchallenged tarantula spider Acanthoscurria gomesiana. Gomesin has a molecular mass of 2270.4 Da, with 18 amino acids, including a pyroglutamic acid as the N terminus, a C-terminal arginine alpha-amide, and four cysteine residues forming two disulfide bridges. This peptide shows marked sequence similarities to antimicrobial peptides from other arthropods such as tachyplesin and polyphemusin from horseshoe crabs and androctonin from scorpions. Interestingly, it also shows sequence similarities to protegrins, antimicrobial peptides from porcine leukocytes. Gomesin strongly affects bacterial growth, as well as the development of filamentous fungi and yeast. In addition, we showed that gomesin affects the viability of the parasite Leishmania amazonensis.