100-kDa Band Research Articles

Construction, expression and characterisation of a single chain variable fragment in the Escherichia coli periplasmic that recognise MCF-7 breast cancer cell line.

A functional single-chain fragment variable (scFv) recognizing the MCF-7 breast cancer carcinoma cell line was constructed from the C3A8 hybridoma using phage display technology. This study was conducted to evaluate the binding activity of scFv antibody recognise MCF-7 breast cancer cells carcinoma, the scfv antibody constructed and expressed in Escherichia coli periplasmic. The scFv coding sequence was cloned in frame with the pIII phage coat protein. The signal sequence included in the C terminus directed the expression of the scFv in the Escherichia coli periplasm. Following several rounds of biopanning, colonies that expressed a scFv that recognized MCF-7 cells in Western blots, ELISAs, and flow cytometry test were isolated. A 750-bp scFv gene was successfully isolated. Cloning and two rounds of biopanning isolated the candidate with the highest activity (clone B7), as screened by ELISA. Following poly-acrylamide gel electrophoresis (SDS-PAGE) of the purified product, a 32-kDa band was observed. A similar-sized band was observed following Western blot analysis with an E tag-specific antibody. Binding reactivity of scFv antibody with MCF cells was determined using indirect ELISA and compared with monoclonal antibodies' reactivity. Also, flow cytometry was useful in further characterization to the binding reactivity of scFv antibody with MCF-7 cells. The recombinant antibody technology used in this study is a rapid and effective approach that will aid in the development of the next generation of immunodiagnostic reagents.

Characterization of a monoclonal antibody capable of reliably quantifying expression of Human Copper Transporter 1 (hCTR1)

Human copper transporter 1 (hCTR1) is the high-affinity copper influx transporter in mammalian cells that also mediates the influx of cisplatin. Loss of hCTR1 expression has been implicated in the development of resistance to this cancer chemotherapeutic agent. It has turned out to be very difficult to develop antibodies to hCTR1 and polyclonal antibodies produced by different laboratories have yielded conflicting results. We have characterized a newly-available rabbit monoclonal antibody that reacts with an epitope on the N-terminal end of hCTR1 that now permits rigorous identification and quantification of hCTR1 using Western blot analysis. Postnuclear membrane (PNM) preparations made from cells engineered to express high levels of myc-tagged hCTR1, and cells in which the expression of hCTR1 was knocked down, were used to characterize the antibody. The identity of the bands detected was confirmed by immunoprecipitation, surface biotinylation and deglycosylation of myc-tagged hCTR1. Despite the specificity expected of a monoclonal antibody, the anti-hCTR1 detected a variety of bands in whole cell lysates (WCL), which made it difficult to quantify hCTR1. This problem was overcome by isolating post-nuclear membranes and using these for further analysis. Three bands were identified using this antibody in PNM preparations that migrated at 28, 33–35 and 62–64kDa. Multiple lines of evidence presented here suggest that the 33–35 and 62–64kDa bands are hCTR1 whereas the 28kDa band is a cross-reacting protein of unknown identify. The 33–35kDa band is consistent with the expected MW of the glycosylated hCTR1 monomer. This analysis now permits rigorous identification and quantification of hCTR1.

Evaluation of recombinant fusion protein comprising dog zona pellucida glycoprotein-3 and Izumo and individual fragments as immunogens for contraception

Vaccines based on gamete specific proteins have been proposed for fertility inhibition. In the present study, immunogenicity and contraceptive potential of E. coli-expressed recombinant fusion protein TT-KK-ZP3-GGG-Iz, comprising promiscuous T cell epitope of tetanus toxoid (TT) followed by dilysin linker (KK), a fragment of dog zona pellucida glycoprotein-3 (ZP3), triglycine spacer (GGG) and a fragment of dog Izumo (Iz) without any affinity tag has been evaluated in female FvB/J mice. In addition, recombinant TT-KK-ZP3 and Izumo linked to the promiscuous T cell epitope of bovine RNase (bRNase-KK-Iz) and their physical mixture were also used. SDS-PAGE and immunoblot studies revealed ∼32kDa band corresponding to TT-KK-ZP3-GGG-Iz, ∼22kDa band of TT-KK-ZP3 and ∼11kDa band of bRNase-KK-Iz. Groups of mice immunized with the above recombinant proteins led to the generation of high antibody titres against the respective proteins. Immunization with recombinant TT-KK-ZP3-GGG-Iz generated higher antibody titre as compared to mice immunized with physical mixture of TT-KK-ZP3 and bRNase-KK-Iz. Antibodies against TT-KK-ZP3-GGG-Iz and TT-KK-ZP3 recognized mouse and dog ZP and those against TT-KK-ZP3-GGG-Iz and bRNase-KK-Iz recognized mouse and dog acrosome-reacted sperm in an indirect immunofluorescence assay. Immune sera from groups of mice immunized with the above recombinant proteins led to a significant reduction in mouse in vitro fertilization. Mating studies revealed significant reduction in fertility as compared to adjuvant control group. Highest infertility was observed in group of mice immunized with TT-KK-ZP3 followed by TT-KK-ZP3-GGG-Iz. Infertility was associated with the antibody titres against ZP3, whereas no association in the inhibition of fertility and antibody titres against Izumo was observed. In conclusion, these studies revealed the contraceptive potential of ZP3, which could not be further enhanced by the inclusion of Izumo.

Rainbow trout (Oncorhynchus mykiss) contain two calnexin genes which encode distinct proteins

Calnexin (IP90/P88) is an integral membrane protein of the endoplasmic reticulum that binds newly synthesized N-linked glycoproteins during their folding in the ER including MHC class I molecule. This manuscript reports the identification of two unique cDNA clones of calnexin in rainbow trout. Both encode putative mature proteins of 579 and 592 aa respectively in addition to a 24 aa signal peptide. Sequence analysis revealed that only one of the two cDNA clones encodes a putative ER retention signal, K/QEDDL, followed by a serine phosphorylation site conserved with mammalian homologs. Amino acid sequence alignment illustrated conservation of the calnexin luminal domain, which consists of a globular and a P domain, in both copies. Southern blotting revealed that there are at least two copies of the calnexin gene in the trout genome and northern blotting showed a wide tissue distribution of an estimated 3kbp calnexin transcript with an additional minor transcript of 2.3kbp expressed only in head kidney, spleen PBLs and strongly in RTS11. Importantly, the smaller transcript was predominantly upregulated in RTS11 after a 24h treatment with the calcium ionophore A23187. In western blots, calnexin was detected primarily as a 120kDa protein and upon A23187 treatment; a 100kDa band was most prominently expressed. These results suggest that in salmonids there are two differentiated versions of the calnexin gene which encode proteins that may have diverged to perform unique biological functions.

Comparative binding of Cry1Ab and Cry1F Bacillus thuringiensis toxins to brush border membrane proteins from Ostrinia nubilalis, Ostrinia furnacalis and Diatraea saccharalis (Lepidoptera: Crambidae) midgut tissue

The European (Ostrinia nubilalis Hübner) and Asian corn borers (Ostrinia furnacalis Guenée) are closely related and display similar sensitivity to Cry1 toxins. In this study, we compared the binding patterns of Cry1Ab and Cry1F toxins between both Ostrinia spp., as well as the expression of putative cadherin- and aminopeptidase-N (APN)-like protein receptors. Additionally, cDNA sequences of these putative toxin receptors from both Ostrinia species were compared. Ligand blots for both species indicated a similar binding pattern for Cry1Ab with the strongest immunoreactive band at 260kDa in both species. In addition, similar expression of the putative cadherin- and APN-like protein receptors were observed at 260 and 135kDa, respectively. A high degree of similarity (98% amino acid sequence identity) of cDNA sequences for both putative receptor sequences was observed. The Cry1F ligand blot revealed that O. furnacalis and O. nubilalis BBMV exhibited slightly different binding patterns, with strong binding to putative proteins at 150 and 140kDa, respectively. Both proteins appeared to also bind Cry1Ab, although the signal intensity was much reduced with Cry1Ab. O. furnacalis showed an additional but weaker band at 210kDa relative to the 150kDa band. Diatraea saccharalis (Fabricius), which was used as an outgroup species, exhibited different binding patterns than either Ostrinia species, with both Cry1Ab and Cry1F toxins binding to a 210kDa protein. These results support the previous experiments indicating that O. nubilalis and O. furnacalis share similar patterns of susceptibility to Cry toxins.

A Hemagglutinin from Northeast Red Beans with Immunomodulatory Activity and Anti-proliferative and Apoptosis-inducing Activities Toward Tumor Cells

A 64-kDa hemagglutinin from a Phaseolus vulgaris cultivar, the northeast red bean, was purified by a protocol composed of three chromatographic steps involving affinity chromatography on Affi-gel blue gel, cation exchange chromatography on SP-Sepharose and FPLC-gel filtration on Superdex 75. The purified hemagglutinin appeared as a single 32-kDa band in SDS-PAGE indicating its dimeric nature. The N-terminal amino acid sequence of the hemagglutinin resembled the sequences of lectins and hemagglutinins from a number of Phaseolus species. The hemagglutinin manifested moderate thermostability and pH stability. It retained full activity up to 65 °C and in the pH range 2-12. It did not interact with simple sugars such as glucose, mannose and galactose. The hemagglutinin exerted immunostimulatory effects by upregulating the expression of cytokines like interferon-γ and tumor necrosis factor-α. It also exhibited antiproliferative activity on a number of tumor cells including MCF7 (breast cancer), HepG2 (liver cancer), CNE1 and CNE2 (nasopharyngeal cancer) cells, with stronger activity toward MCF7 and CNE1 cells. The hemagglutinin induced phophatidylserine externalization, mitochondrial depolarization and DNA condensation in MCF7 cells, indicating initiation of apoptosis. However, at high hemagglutinin concentrations, severe damage to the MCF7 cells was detected.

Immunoprotection of mice against Schistosomiasis mansoni using solubilized membrane antigens.

BackgroundSchistosomiasis continues to be one of the most prevalent parasitic diseases in the world. Despite the existence of a highly effective antischistosome drug, the disease is spreading into new areas, and national control programs do not arrive to complete their tasks particularly in low endemic areas. The availability of a vaccine could represent an additional component to chemotherapy. Experimental vaccination studies are however necessary to identify parasite molecules that would serve as vaccine candidates. In the present work, C57BL/6 female mice were subcutaneously immunized with an n-butanol extract of the adult worm particulate membranous fraction (AWBE) and its protective effect against a S. mansoni challenge infection was evaluated.Methodology and FindingsWater-saturated n-butanol release into the aqueous phase a set of membrane-associated (glyco)proteins that are variably recognized by antibodies in schistosome-infected patients; among the previously identified AWBE antigens there is Alkaline Phosphatase (SmAP) which has been associated with resistance to the infection in mice. As compared to control, a significantly lower number of perfuse parasites was obtained in the immunized/challenged mouse group (P<0.05, t test); and consequently, a lower number of eggs and granulomas (with reduced sizes), overall decreasing pathology. Immunized mice produced high levels of sera anti-AWBE IgG recognizing antigens of ∼190-, 130-, 98-, 47-, 28-23, 14-, and 9-kDa. The ∼130-kDa band (the AP dimer) exhibited in situ SmAP activity after addition of AP substrate and the activity was not apparently inhibited by host antibodies. A preliminary proteomic analysis of the 25-, 27-, and 28-kDa bands in the immunodominant 28–23 kDa region suggested that they are composed of actin.ConclusionsImmunization with AWBE induced the production of specific antibodies to various adult worm membrane molecules (including AP) and a partial (43%) protection against a challenging S. mansoni infection by mechanism(s) that still has to be elucidated.

Calreticulin negatively regulates the surface expression of Cav1.3 L-type calcium channel

BackgroundThe neuroendocrine Cav1.3 L-type Ca channels have been recently found in the Human fetal heart and shown to play a vital role in Ca entry from the sarcolemma into the cell and in Ca homeostasis. Calreticulin, a Ca binding endoplasmic reticulum (ER) resident protein, has been recently shown to translocate to the cell surface where its role and function are just emerging. Here, we demonstrated a novel mechanism of Cav1.3 and calreticulin interaction resulting in downregulation of Cav1.3 channel densities in native Human fetal cardiac cells and Human Embryonic Kidney cell lines (tsA201). Methods and resultsCell surface and cytoplasmic staining of calreticulin was demonstrated first in cultured human fetal cardiomyocytes (HFC), gestational age 18–24weeks, using confocal microscopy thereby establishing that calreticulin is present at the cell surface in HFC. Co-immunoprecipitation from HFC using anti-Cav1.3 Ca channel antibody, and probing with anti-calreticulin antibody revealed a 46kDa band corresponding to calreticulin suggesting that Cav1.3 Ca channel and calreticulin co-assemble in a macromolecular complex. Co-expression of Cav1.3 and calreticulin in tsA201 cells resulted in a decrease in surface expression of Cav1.3 Ca channels. These findings were consistent with the electrophysiological studies showing that co-transfection of Cav1.3 Ca channel and calreticulin resulted in 55% reduction of Cav1.3 Ca current densities recorded from tsA201 cells. ConclusionsThe results show the first evidence that calreticulin: (1) is localized outside the ER on the cell surface of HFC; (2) coimmunoprecipitates with Cav1.3 L-type Ca channel; (3) negatively regulates Cav1.3 surface expression thus resulting in decreased Cav1.3 Ca current densities. The data demonstrate a novel mechanism of modulation of Cav1.3 Ca channel by calreticulin, which may be involved in pathological settings such as autoimmune associated congenital heart block where Cav1.3 Ca channels are downregulated.

OP0140 Circulating Carboxy-Terminal Type X Collagen Fragments (C-Col10), a Measure of Skeletal Hypertrophy, are Elevated in Patients with Osteoarthritis and Ankylosing Spondylitis

BackgroundAnkylosing Spondylitis (AS) is a chronic inflammatory disease of the spine and sacroiliac joints, whereas osteoarthritis (OA) is generally considered as a non-inflammatory condition of the synovial joints, predominantly knee...

Immunization of Rabbits with NematodeAscaris lumbricoidesAntigens Induces Antibodies Cross-Reactive to House Dust MiteDermatophagoides farinaeAntigens

There are controversial reports on the relationship between helminthic infection and allergic diseases. Although IgE cross-reactivity between nematode Ascaris antigens and house dust-mite allergens in allergic patients have been reported, whether Ascaris or the mite is the primary sensitizer remains unknown. Here we found that immunization of naïve animals with Ascaris lumbricoides (Al) antigens induced production of antibodies cross-reactive to mite antigens from Dermatophagoides farinae (Df). Sera from Bangladeshi children showed IgE reactivity to Ascaris and mite extracts. IgG from rabbits immunized with Al extract exhibited reactivity to Df antigens. Treatment of the anti-Al antibody with Df antigen-coupled beads eliminated the reactivity to Df antigens. In immunoblot analysis, an approximately 100-kDa Df band was the most reactive to anti-Al IgG. The present study is the first step towards the establishment of animal models to study the relationship between Ascaris infection and mite-induced allergic diseases.

The Collagen-binding Integrin α2β1 Is a Novel Interaction Partner of the Trimeresurus flavoviridis Venom Protein Flavocetin-A

Many snake venoms are known for their antithrombotic activity. They contain components that specifically target different platelet-activating receptors such as the collagen-binding integrin α2β1 and the von Willebrand factor receptor GPIb. In a search for an α2β1 integrin-blocking component from the venom of the habu snake (Trimeresurus flavoviridis), we employed two independent purification protocols. First, we used the integrin α2A domain, a major collagen-binding domain, as bait for affinity purification of an α2β1 integrin-binding toxin from the crude venom. Second, in parallel, we used classical protein separation protocols and tested for α2β1 integrin-inhibiting capabilities by ELISA. Using both approaches, we identified flavocetin-A as an inhibitor of α2β1 integrin. Hitherto, flavocetin-A has been reported as a GPIb inhibitor. However, flavocetin-A inhibited collagen-induced platelet aggregation even after GPIb was blocked with other inhibitors. Moreover, flavocetin-A antagonized α2β1 integrin-mediated adhesion and migration of HT1080 human fibrosarcoma cells, which lack any GPIb, on collagen. Protein chemical analyses proved that flavocetin-A binds to α2β1 integrin and its α2A domain with high affinity and in a cooperative manner, which most likely is due to its quaternary structure. Kinetic measurements confirmed the formation of a strong complex between integrin and flavocetin-A, which dissociates very slowly. This study proves that flavocetin-A, which has long been known as a GPIb inhibitor, efficiently targets α2β1 integrin and thus blocks collagen-induced platelet activation. Moreover, our findings suggest that the separation of GPIb- and α2β1 integrin-blocking members within the C-type lectin-related protein family is less strict than previously assumed.

Isolation of a Glucosamine Binding Leguminous Lectin with Mitogenic Activity towards Splenocytes and Anti-Proliferative Activity towards Tumor Cells

A dimeric 64-kDa glucosamine-specific lectin was purified from seeds of Phaseolus vulgaris cv. “brown kidney bean.” The simple 2-step purification protocol involved affinity chromatography on Affi-gel blue gel and gel filtration by FPLC on Superdex 75. The lectin was absorbed on Affi-gel blue gel and desorbed using 1M NaCl in the starting buffer. Gel filtration on Superdex 75 yielded a major absorbance peak that gave a single 32-kDa band in SDS-PAGE. Hemagglutinating activity was completely preserved when the ambient temperature was in the range of 20°C–60°C. However, drastic reduction of the activity occurred at temperatures above 65°C. Full hemagglutinating activity of the lectin was observed at an ambient pH of 3 to 12. About 50% activity remained at pH 0–2, and only residual activity was observed at pH 13–14. Hemagglutinating activity of the lectin was inhibited by glucosamine. The brown kidney bean lectin elicited maximum mitogenic activity toward murine splenocytes at 2.5 µM. The mitogenic activity was nearly completely eliminated in the presence of 250 mM glucosamine. The lectin also increased mRNA expression of the cytokines IL-2, TNF-α and IFN-γ. The lectin exhibited antiproliferative activity toward human breast cancer (MCF7) cells, hepatoma (HepG2) cells and nasopharyngeal carcinoma (CNE1 and CNE2) cells with IC50 of 5.12 µM, 32.85 µM, 3.12 µM and 40.12 µM respectively after treatment for 24 hours. Flow cytometry with Annexin V and propidum iodide staining indicated apoptosis of MCF7 cells. Hoechst 33342 staining also indicated formation of apoptotic bodies in MCF7 cells after exposure to brown kidney bean lectin. Western blotting revealed that the lectin-induced apoptosis involved ER stress and unfolded protein response.

PURIFICATION AND CHARACTERIZATION OF SOY COTYLEDON β-GLUCOSIDASE

ABSTRACT β-Glucosidase F42 of soy cotyledons was purified by ammonium sulfate fractionation, ion-exchange chromatography (CM-Sephadex-C-50, Sigma, St. Louis, MO) and gel filtration (Sephadex G-100, Sigma). The enzyme was purified 111.8-fold relative to its concentration in the crude extract. It had an apparent molecular mass of 53 kDa in gel filtration experiments and produced a 33-kDa band in sodium dodecyl sulfate–polyacrylamide gel electrophoresis, suggesting that it is dimeric. The purified β-glucosidase F42 was characterized as a glycoprotein after the identification of fucose, galactosamine and glucosamine by high-pressure anion-exchange chromatography–pulsed amperometric detector. Its highest activity was observed at pH 5.0 and 45C, and it was stable for up to 4 days at 25C. The Km of the enzyme was 0.12 mM p-nitrophenyl-β-d-glucopyranoside. β-Glucosidase F42 showed specificity for different substrates, and its activity was inhibited by 1 mM HgCl2, 10 mM glucono-δ-lactone or 150 mM glucose and increased by 10 mM MnCl2. PRACTICAL APPLICATIONS β-Glucosidase is an enzyme that hydrolyzes β-glucosidic bonds to liberate glucose and hydrolyzes isoflavones to release aglycones. Soy aglycones have been broadly investigated because of their biological activity in the prevention and treatment of some chronic diseases. Soy β-glucosidase can be used in the food industry to alter soy isoflavones for the production of functional foods that are rich in aglycone isoflavones. Therefore, it was an established method of purification of the enzyme that has great biotechnological potential.

Purification and partial characterization of glyceraldehyde-3-phosphate dehydrogenase from the ciliate &amp;lt;italic&amp;gt;Tetrahymena thermophila&amp;lt;/italic&amp;gt;

In the present study, we purified the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) which is involved in cellular energy production and has important housekeeping functions, from the ciliate Tetrahymena thermophila using a three-step procedure. The enzyme was purified ~68 folds by ammonium sulfate precipitation, followed by two steps of column chromatography (DEAE-cellulose and Mono-S). The purified enzyme is a homotetramer with a molecular weight of ~120 kDa. Isoelectric focusing analysis showed the presence of only one basic GAPDH isoform with an isoelectric point of 8.8. Western blot analysis showed a single 32-kDa band corresponding to the enzyme subunit using a monospecific polyclonal antibody against the T. thermophila GAPDH. The maximum of enzyme activity occurred at pH 8.0 and at 30-35°C. The apparent K(m) values for both NAD(+) and D-glyceraldehyde-3-phosphate were 0.102 ± 0.012 and 0.360 ± 0.018 mM, respectively. The maximal velocity (V(max)) was 39.40 ± 2.95 U/mg. The T. thermophila GAPDH is inhibited by oxidative and nitrosative stress reagents.

The cholangiocyte marker, BD. 1, forms a stable complex with CLIP170 and shares an identity with eIF3a, a multifunctional subunit of the eIF3 initiation complex

We have previously described the generation of a monoclonal antibody recognizing a novel cholangiocyte marker, designated BD.1, that is expressed by fetal and adult rat cholangiocytes but not hepatocytes or the hepatic progenitor cells known as oval cells. In the present report, we have undertaken a comprehensive examination of BD.1 expressed by long-term cultures of bile duct epithelial cells (BDEC) and prostate epithelial cells (PEC). We show that with continued passage, the levels of BD.1 expressed by BDEC and PEC drop significantly, a decrease that is temporally associated with transition from a diploid to an aneuploid karyotype. Cell cycle analysis revealed cell cycle dependent expression of BD.1 characterized by decreased BD.1 levels within the first 10h after release from serum starvation followed by reacquisition as cells entered S phase. MAb BD.1 recognized a 170kDa protein in Western blots and showed strong reactivity with a 170kDa band in blots prepared from phosphoproteins isolated by metal affinity chromatography. Analysis by mass spectrometry of tryptic peptides generated from BD.1 purified by continuous elution electrophoresis identified the plus end microtubule‐binding protein, CLIP170, in the fraction reactive with MAb BD.1. Double immunofluorescence with MAb BD.1 and a MAb specific for CLIP170 showed that both were reactive with intrahepatic bile ducts. However, overexpression or siRNA knockdown of CLIP170 in 293T cells did not significantly alter BD.1 levels, indicating that CLIP170 and BD.1 were distinct, co-migrating proteins. Immunoprecipitation analysis with MAb BD.1 and anti-CLIP170 antibodies showed that under microtubule depolymerizing conditions the two proteins could be co-precipitated with both antibodies, leading us to conclude they were capable of forming stable complexes. Two different protocols were devised to enrich for the CLIP170 binding protein recognized by MAb BD.1. Analysis of tryptic peptides by LC-ESI-MS/MS identified BD.1 as eIF3a, the largest subunit of the elongation initiation factor 3 (eIF3) complex. This identity was confirmed by the simultaneous knockdown of both BD.1 and eIF3a by eIF3a-specific siRNAs and by the strong reactivity of MAb BD.1 with the 170kDa protein immunoprecipitated with the anti-eIF3a antibody, 5H10. Based on these findings, we concluded that the BD.1 antigen was identical to eIF3a, a multifunctional subunit of the eIf3 complex shown here to associate with microtubules through its interactions with CLIP170.

Identification of a 2-cys peroxiredoxin as a tetramethyl benzidine-hydrogen peroxide stained protein from the thylakoids of the extreme halophyte Arthrocnemum macrostachyum L.

Tetramethylbenzidine-H(2)O(2) staining of SDS-polyacrylamide gel is a widely used method for the specific detection of proteins with heme-dependent peroxidase activity. When this method was used with thylakoids from the halophytic plant Arthrocnemum macrostachyum, besides the cytochrome f and cytochrome b6 proteins usually found in higher plants and cyanobacteria, at least four additional bands were detected. One of them, a 46-kDa protein, was shown to be an extrinsic protein, and identified by mass spectrometry and immunoblotting as a 2-cys peroxiredoxin. Peroxidase activity was insensitive to oxidizing agents such as trans-4,4-diydroxy-1,2-dithiane or hydrogen peroxide, but was inhibited by treatment of thylakoids with reducing agents such as dithiothreitol or mercaptoethanol. By immunoblotting, it was shown that loss of peroxidase activity was paralleled by disappearance of the 46-kDa band, which was converted to a 23-kDa immunoreactive form. A dimer/monomer relationship between the two proteins is suggested, with the dimeric form likely being a heme-binding protein. This possibility was further supported by anionic exchange chromatography and de novo sequencing of tryptic fragments of the protein and sequence comparison, as most of the residues previously implicated in heme binding in 2-cys peroxiredoxin from Rattus norvegicus were conserved in A. macrostachyum. The amount of this protein was modulated by environmental conditions, and increased when salt concentration in the growth medium was higher or lower than the optimal one.

Pre-freezing and post-thawing quality of boar sperm for distinct portions of the ejaculate and as a function of protein bands present in seminal plasma

This study evaluated pre-freezing and post-thawing boar sperm quality in distinct portions of the ejaculates and identified protein bands potentially related to boar sperm tolerance to freezing. The sperm-rich portion of the ejaculate was fractioned in: the first 10mL (P1); and its remaining volume (P2). Those portions were frozen and the bands present in both portions were evaluated by one-dimensional electrophoresis. Inter- and intra-boar ANOVA evaluated how the presence of bands related to pre-freezing and post-thawing sperm motility and membrane integrity and to post-thawing acrosome integrity. Post-thawing sperm motility, membrane integrity and acrosome integrity were greater for P1 than for P2 (P<0.05). The presence of the 19kDa band was associated with improved pre-freezing sperm motility and membrane integrity, but with reduced post-thawing acrosome integrity (P<0.05). The presence of the 44kDa band was associated with reduced post-thawing sperm motility and acrosome integrity (P<0.05). Post-thawing acrosome integrity was enhanced when the 80kDa band were present (P<0.05). Reduced pre-freezing sperm membrane integrity and post-thawing sperm motility were associated to the presence of the 100kDa band (P<0.05). The presence of the 18kDa band in P2 was associated with reduction in both post-thawing sperm motility and membrane integrity (P<0.05), but such an effect was not observed in P1 (P>0.05). Thus, sperm from P1 presented greater tolerance to freezing than sperm from P2 and the 18, 19, 44, 65, 80 and 100kDa bands may be potential markers for boar sperm tolerance to cryopreservation.

Effects of two monoclonal antibodies, MLS128 against Tn-antigen and 1H7 against insulin-like growth factor-I receptor, on the growth of colon cancer cells

MLS128 is an anti-carbohydrate monoclonal antibody (mAb) that binds three or two consecutive Tn-antigens. MLS128 bound 110-210 kDa glycoproteins (GPs) and inhibited the growth of LS180 and HT29 colon and MCF-7 breast cancer cells. One possible mechanism of MLS128's inhibition of growth may be via insulin-like growth factor-I receptor (IGF-IR) down-regulation (Morita et al. BioScience Trends. 2009; 3:32-37). The current study examined the role of IGF-IR signaling in the growth of colon cancer cells and its possible interaction with MLS128-induced inhibition of cell growth in LS180, LS174T, and HT29 human colon cancer cells treated with MLS128 or anti-IGF-IR 1H7. Both MLS128 and 1H7 treatment significantly inhibited the growth of colon cancer cells. All three colon cancer cell lines expressed IGF-IR. Their growth was in part IGF-I dependent, but inhibition by MLS128 was independent of IGF-IR signaling. All of the colon cancer cell lines expressed an 110kDa GP for MLS128 binding, but MCF-7 cells expressed MLS128-detectable bands with higher molecular masses. 1H7 treatments caused down-regulation of IGF-IR but did not affect 110kDa GP levels. MLS128 treatments resulted in partial disappearance of the 110kDa band but did not affect IGF-IR levels. Western blotting analyses of colon and breast cancer cell lysates revealed that colon and breast cancer cells differed significantly in patterns of expression of growth-related molecules while colon cancer cells were similar but distinctive. In conclusion, MLS128 inhibited the growth of colon cancer cells by binding to the 110kDa GP receptor. Inhibition of growth by MLS128 did not appear to affect IGF-IR signaling and instead only affected other growth signaling pathways.

Identification and immunolocalisation of melatonin MT1 and MT2 receptors in Rasa Aragonesa ram spermatozoa

The reproductive seasonality of sheep suggests that melatonin receptors may be present in ram spermatozoa. The present study confirms the presence of melatonin MT(1) and MT(2) receptors. The MT(1) receptor was detected using immunocytochemistry, with four sperm subpopulations identified based on the following labelling patterns: (1) one small subpopulation with labelling over the entire head and tail; (2) one of two main subpopulations that exhibited reactivity at the equatorial, post-acrosomal, neck and tail regions; (3) another main subpopulation with equatorial and tail labelling only; and (4) a subpopulation in which staining was detected only in the tail. Immunocytochemistry revealed the presence of the melatonin MT(2) receptor, with intense staining on the acrosome, post-acrosomal region and neck and tail regions of all cells, but not in the equatorial region. Western blot identification of ram protein extracts revealed a 39-kDa band compatible with both MT(1) and MT(2) receptors, a 75-kDa band compatible with MT(1)/MT(2) heterodimerisation, a 32-kDa band compatible with MT(1) receptor activation and a double band of 45-55 kDa that is compatible with MT(2) receptor homodimerisation or heterodimerisation with other G-proteins. In conclusion, we provide evidence of the presence of MT(1) and MT(2) receptors in ram spermatozoa, although the biochemical pathway triggered by these receptors and their function in terms of fertility remains to be elucidated.

Identification of Human Fumarylacetoacetate Hydrolase Domain-containing Protein 1 (FAHD1) as a Novel Mitochondrial Acylpyruvase

The human fumarylacetoacetate hydrolase (FAH) domain-containing protein 1 (FAHD1) is part of the FAH protein superfamily, but its enzymatic function is unknown. In the quest for a putative enzymatic function of FAHD1, we found that FAHD1 exhibits acylpyruvase activity, demonstrated by the hydrolysis of acetylpyruvate and fumarylpyruvate in vitro, whereas several structurally related compounds were not hydrolyzed as efficiently. Conserved amino acids Asp-102 and Arg-106 of FAHD1 were found important for its catalytic activity, and Mg(2+) was required for maximal enzyme activity. FAHD1 was found expressed in all tested murine tissues, with highest expression in liver and kidney. FAHD1 was also found in several human cell lines, where it localized to mitochondria. In summary, the current work identified mammalian FAHD1 as a novel mitochondrial enzyme with acylpyruvate hydrolase activity.