Dynamic evolutionary pattern of α2-macroglobulin in a model organism, the zebrafish (Danio rerio)

Cloning, distribution and primary immune characteristics of amphioxus alpha-2 macroglobulin

Alpha-2 macroglobulin (α(2)M), a broad-spectrum protease inhibitor, exists widely in vertebrates and invertebrates, but little information is available to date regarding α(2)M in amphioxus, an animal bridging from invertebrates to vertebrates. Here we first show that the full α(2)M cDNA of Branchiostoma japonicum (Bjα(2)m) contained 5545 bp with an open reading frame of 4593 bp encoding signal sequence of 16 amino acid residues and a mature protein of 1514 residues. The calculated molecular mass and pI of mature Bjα(2)M were 164.2 kDa and 4.6 respectively. Bjα(2)m was mainly expressed in the hepatic caecum and hind-gut in a tissue-specific manner, contrasting to the primary expression of α(2)M in vertebrate liver. Following challenge with lipopolysaccharide (LPS), Bjα(2)m expression was significantly up-regulated (7-folds) at 8 h and then declined to the base line at 16 h. Taken together, it is suggested that Bjα(2)M is an immune-relevant molecule possibly involved in the acute phase response via the digestive organs.

Analysis of expressed sequence tags from the placenta of the live-bearing fish Poeciliopsis (Poeciliidae)

Matrotrophic fish in the genus Poeciliopsis (Poeciliidae) have a placenta-like structure used in postfertilization maternal provisioning of the developing embryo. To understand better the structure and function of the Poeciliopsis placenta, we derived cDNA libraries from the maternal follicular placenta of 2 matrotrophic Poeciliopsis sister species, P. turneri and P. presidionis. These species inherited their placenta from a common ancestor and represent one of 3 independent origins of placentas in Poeciliopsis. Expressed sequence tags (ESTs) were generated and putative function was determined using BLASTX homology searches and Gene Ontology (GO) annotation. Reverse transcription-polymerase chain reaction was used to verify placenta tissue expression of a putative candidate gene, alpha-2 macroglobulin. In total, 1956 (71.5% of the total submitted ESTs) and 924 (71.0% of the total submitted ESTs) unique transcripts were identified for the P. turneri and P. presidionis placenta, respectively. Homology search and GO annotation revealed putative genes whose products may be involved in specific transport functions of the maternal follicle. These putative genes are excellent candidates for future research on the evolution of the placenta. We discuss our results in light of the parent-offspring conflict theory of placental evolution and in terms of the Poeciliid placenta structure and function.

Design and performance of a turbot (Scophthalmus maximus) oligo-microarray based on ESTs from immune tissues

An expressed sequence tag database from immune tissues was used to design the first high-density turbot (Scophthalmus maximus) oligo-microarray with the aim of identifying candidate genes for tolerance to pathogens. Specific oligonucleotides (60 mers) were successfully designed for 2,716 out of 3,482 unique sequences of the database. An Agilent custom oligo-microarray 8 x 15 k (five replicates/gene; eight microarrays/slide) was constructed. The performance of the microarray and the sources of variation along microarray analysis were examined on spleen pools of controls and Aeromonas salmonicida-challenged fish at 3 days postinfection. Only 48 out of 2,716 probes did not show signal of hybridization on the 32 microarrays employed, thus demonstrating the consistency of the bioinformatic applications of our database. An asymmetric hierarchical design was employed to ascertain the noise associated with biological and technical (RNA extraction, labeling, hybridization, slide, and dye bias) factors using 1C and 2C labeling approaches. The high correlation coefficient between replicates at most factors tested demonstrated the high reproducibility of the signal. An analysis of random-effects variance revealed that technical variation was mostly negligible, and biological variation represented the main factor, even using pooled samples. One-color approach performed at least as well as 2C, suggesting their usefulness due to its higher design flexibility and lower cost. A relevant proportion of genes turn out to be differentially labeled depending on fluorophore, which alerts for the likely need of swapping replication in 2C experiments. A set of differentially expressed genes and enriched functions related to immune/defense response were detected at 3 days postchallenging.

Identification of protein components of egg masses indicates parental investment in immunoprotection of offspring by Biomphalaria glabrata (gastropoda, mollusca)

The macromolecules contributed by the freshwater gastropod Biomphalaria glabrata, intermediate host of Schistosoma mansoni, to developing offspring inside egg masses are poorly known. SDS-PAGE fractionated egg mass fluids (EMF) of M line and BB02 B. glabrata were analyzed by MALDI-TOF (MS and tandem MS). A MASCOT database was assembled with EST data from B. glabrata and other molluscs to aid in sequence characterization. Of approximately 20 major EMF polypeptides, 16 were identified as defense-related, including protease inhibitors, a hemocyanin-like factor and tyrosinase (each with possible phenoloxidase activity), extracellular Cu-Zn SOD, two categories of C-type lectins, Gram-negative bacteria-binding protein (GNBP), aplysianin/achacin-like protein, as well as versions of lipopolysaccharide binding protein/bacterial permeability-increasing proteins (LBP/BPI) that differed from those previously described from hemocytes. Along with two sequences that were encoded by "unknown" ESTs, EMF also yielded a compound containing a vWF domain that is likely involved in defense and a polypeptide with homology to the Aplysia pheromone temptin. Further study of B. glabrata pheromones is warranted as these could be useful in efforts to control these schistosome-transmitting snails. Several of the EMF polypeptides were contained in the albumen gland, the organ that produces most EMF. Thus, parental investment of B. glabrata in immunoprotection of its offspring is indicated to be considerable.

Proteomic analysis of sera of asymptomatic, early-stage patients with Wilson's disease

Wilson's disease (WD) is characterized by excessive accumulation of intracellular copper in liver and extrahepatic tissues, leading to significant oxidative stress and tissue damage. To date, several diagnostic biomarkers for WD such as serum ceruloplasmin, serum or urine copper levels and copper content in liver have been identified. However, these biomarkers may not be convincing for the diagnosis in some WD patients. To identify additional novel diagnostic biomarkers, we compared the serum protein profiles of asymptomatic childhood WD patients (n=20), without neurologic manifestation or liver cirrhosis, with normal controls (n=13). Fourteen spots, five up-regulated and nine down-regulated (>2-fold), were differentially expressed in WD patients in comparison to normal control on 2-DE. Among them, three spots were down-regulated in both male and female WD. MS/MS analysis revealed that the three spots were complement component C3, complement factor B and alpha-2 macroglobulin. By comparative proteome analysis, complement component C3, complement factor B and alpha-2 macroglobulin, which are related to oxidative stress and inflammation, turned out to be good candidates for novel diagnostic biomarkers for early stages of WD.