Molecular isolation and characterization of a novel occlusion body protein gene from Penaeus monodon nucleopolyhedrovirus

The full-length of the occlusion body (OB) protein gene of Penaeus monodon nucleopolyhedrovirus (PemoNPV) was successfully isolated. The OB gene sequence contained an open reading frame (ORF) of 1359 nucleotides encoding a protein of 452 amino acid residues with a predicted molecular mass of 50.6 kDa. A putative late promoter element, TAAG, was identified 72 nt upstream of the translation start site. The amino acid sequences of tryptic digested peptides of PemoNPV OB protein obtained from LC-MS analysis matched quite well with various regions of deduced amino acid sequences. Recombinant PemoNPV OB proteins specifically reacted with monoclonal antibodies to PemoNPV OB protein. After comparison with nucleotide database, the PemoNPV OB ORF demonstrated 67% identity to an uncharacterized ORF of a baculovirus pathogenic for Penaeus vannamei. However, comparison against protein databases revealed no significant homology to other known proteins. To our knowledge, this PemoNPV OB gene is the first isolated and characterized gene of nucleopolyhedrovirus from shrimp.

Preferential suppression of yellow head virus (YHV) envelope protein gp116 in shrimp that survive challenge with YHV

The DNA sequence that encodes the first 406 amino acid residues at the N-terminus of yellow head virus (YHV) protein gp116, namely N/2 gp116deltaTM, and the DNA sequence that encodes the next 392 amino acid residues at the C-terminus of gp116 (without the transmembrane region), namely C/2 gp116deltaTM, were cloned into pGEX-6P-1 plasmid and expressed in E. coli. Both recombinant proteins were expressed, purified by SDS-PAGE and used to immunize mice. The mouse anti-recombinant N/2 gp116 and C/2 gp116 antisera bound specifically to both the recombinant proteins and to natural gp116 protein in YHV-infected haemolymph as shown by Western blotting and in tissues as shown by immunohistochemistry. Immunohistochemical localization of YHV using anti-gp116 antiserum or monoclonal antibodies specific to gp116 (V3-2B), gp64 (Y18) and p20 (Y19) revealed similar immunoreactivity patterns for all these reagents in muscle and mandibular tissue in shrimp showing gross signs of yellow head disease. However, in gill, hepatopancreas, lymphoid organ and thoracic ganglion tissues from experimental YHV-infected shrimp (Penaeus vannamei and Palaemon serrifer) that did not show signs of disease, immunoreactivity to gp116 was reduced or absent while that for gp64 and p20 remained intense. Thus, some shrimp species were able to selectively inhibit the synthesis of gp116 in a manner that was associated with absence of gross signs of disease.

Specific monoclonal antibodies raised against Taura syndrome virus (TSV) capsid protein VP3 detect TSV in single and dual infections with white spot syndrome virus (WSSV)

The gene sequence encoding VP3 capsid protein of Taura syndrome virus (TSV) was cloned into pGEX-6P-1 expression vector and transformed into Escherichia coli BL21. After induction, recombinant GST-VP3 (rVP3) fusion protein was obtained and further purified by electro-elution before use in immunizing Swiss mice for production of monoclonal antibodies (MAb). One MAb specific to glutathione-S-transferase (GST) and 6 MAb specific to VP3 were selected using dot blotting and Western blotting. MAb specific to VP3 could be used to detect natural TSV infections in farmed whiteleg shrimp Penaeus vannamei by dot blotting and Western blotting, without cross reaction to shrimp tissues or other shrimp viruses, such as white spot syndrome virus (WSSV), yellow head virus (YHV), monodon baculovirus (MBV) and hepatopancreatic parvovirus (HPV). These MAb were also used together with those specific for WSSV to successfully detect TSV and WSSV in dual infections in farmed P. vannamei.

A convenient immunochromatographic test strip for rapid diagnosis of yellow head virus infection in shrimp

A simple yellow head virus (YHV) "strip test" was developed using monoclonal antibody Y19 (against the p20 structural protein) conjugated with colloidal gold as the detector antibody. Rabbit anti-recombinant p20 (rp20) protein antibody was used as a capture antibody at the test line (T) and goat anti-mouse IgG antibody (GAM) was used as the capture antibody at the control line (C). The ready-to-use strip was housed in a plastic case for convenient application and stored in the desiccated plastic bag. A sample volume of 100 microl of either haemolymph or gill or appendage homogenates in application buffer was applied to the sample chamber at one end of the strip and allowed to flow by chromatography through the nitrocellulose membrane to the other end. In test samples containing YHV, the virus would bind to colloidal gold conjugated monoclonal antibody and the resulting complex would be captured by the rabbit anti-rp20 antibody at the test line to give a reddish-purple band. Any unbound monoclonal antibody conjugated with colloidal gold moved across the test line to be captured by the GAM to form a band at the control line (C). In the sample without YHV or below the limit of detection for the kit, only the control line was demonstrated. This method was about 500 times less sensitive than that of one-step RT-PCR, but slightly more sensitive than dot blotting. Therefore, it could be used for primary screening of individual shrimp or pooled shrimp samples to confirm high levels of YHV infection or YHV disease outbreaks. This kit can be used to detect gill associated virus (GAV) infection as well since the monoclonal antibody used in this kit cross-reacted well with GAV. The beneficial features of this kit are that simple, convenient, and rapid results that can be obtained without the requirement of sophisticated tools or special skills.

A simple and rapid immunochromatographic test strip for detection of white spot syndrome virus (WSSV) of shrimp

A simple strip-test kit for white spot syndrome virus (WSSV) detection was developed using monoclonal antibody W29 (against the VP28 structural protein) conjugated with colloidal gold as the detector antibody. A rabbit anti-recombinant VP28F118 (rVP28) protein antibody in combination with a W28 monoclonal antibody was used as the capture complex at the test line (T), and goat anti-mouse IgG antibody (GAM) was used as the capture antibody at the control line (C). For evidence, the ready-to-use strip was kept in a plastic case and stored in a desiccated plastic bag. A sample volume of 100 microl gill homogenate in application buffer was applied to the sample chamber at one end of the strip and allowed to flow by chromatography through the nitrocellulose membrane to the other end. In test samples containing WSSV, the virus bound to the monoclonal antibody conjugated with colloidal gold and the resulting complex was captured by the antibodies at T to give a reddish-purple band. Any unbound monoclonal antibody conjugated with colloidal gold moved across T to be captured by the GAM and formed a band at C. In samples without WSSV or with WSSV below the limit of detection of the kit, only the band at C was seen. This method was 4 times less sensitive than dot blotting, and about 2 000 000 times less sensitive than 1-step PCR. Nonetheless, it could be used to screen individual shrimp or pooled shrimp samples to confirm high levels of WSSV infection or WSSV disease outbreaks. The beneficial features of this kit are that simple, convenient and quick results can be obtained without the requirement of sophisticated tools or special skills.

Development of monoclonal antibodies for simple identification of Vibrio alginolyticus

AIMS

The present study was aimed to produce monoclonal antibodies (MAbs) for simple and specific identification of Vibrio alginolyticus infection in shrimp.

METHODS AND RESULTS

Mice were immunized with heat killed V. alginolyticus four times at 2-week intervals. The best response mouse was used for spleen donor in hybridoma production. Screening of hybridoma clones producing desired antibodies was performed by dot blotting against V. alginolyticus and other bacterial species, Western blotting and immunohistochemistry of infected shrimp tissues. Four groups of MAbs were obtained; the first group of MAbs demonstrated their limited specificity only to V. alginolyticus used for immunization, while the second and the third groups recognized all three isolates of V. alginolyticus used for testing. The fourth group of MAbs bound to all three isolates of V. alginolyticus and also recognized Vibrio parahaemolyticus, Vibrio harveyi, Vibrio fluvialis and Vibrio vulnificus but did not bind to Vibrio mimicus, Vibrio cholerae, Vibrio penaeicida and other bacterial species tested. MAbs in groups 1, 2 and 3 were able to use for the detection of bacterial infection in the tissues by means of immunohistochemistry.

CONCLUSIONS

MAbs specific to V. alginolyticus was produced. These MAbs can be used for specific identification of the bacteria by simple 'dot blotting' method and immunohistochemistry.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrated an immunological tool that can be used for simple and accurate identification of V. alginolyticus as well as for the diagnosis of V. alginolyticus infection in animals. This immunological tool can replace costly and laborious biochemical tests.

Polyclonal antibodies specific for VP1 and VP3 capsid proteins of Taura syndrome virus (TSV) produced via gene cloning and expression

Capsid protein genes VP1 and VP3 of Taura syndrome virus (TSV) were cloned into pGEX-6P-1 expression vector and transformed into Escherichia coli BL21. After induction, recombinant VP1 (rVP1) and recombinant VP3 (rVP3) were produced, purified by SDS-PAGE and used for immunization of Swiss mice for antisera production. Anti-rVP1 and anti-rVP3 antisera showed specific immunoreactivities to rVP1 and rVP3 proteins, respectively, by Western blot assay and also yielded good results for detection of TSV in various shrimp tissues by immunohistochemistry. This is the first step towards our target of preparing monoclonal antibodies specific to rVP1 and rVP3 for use in simple immuno-diagnostic test kits for TSV detection and identification.

Development of a polyclonal antibody specific to VP19 envelope protein of white spot syndrome virus (WSSV) using a recombinant protein preparation

The VP19 gene encoding a structural envelope protein of white spot syndrome virus was cloned into an expression vector and introduced into E. coli. The objective was to produce a recombinant VP19 structural protein. After induction, the recombinant VP19 protein (rVP19) was produced, purified by SDS-PAGE and used for immunization of Swiss mice for polyclonal antibody production. The mouse anti rVP19 antiserum had specific immunoreactivity to the viral antigen in WSSV infected Penaeus monodon as verified by immunohistochemistry and Western blot. The production of monoclonal antibodies against this rVP19 may be useful in order to combine with anti-VP28 monoclonal antibodies for enhancing the sensitivity of various WSSV serological assays.

Generation of monoclonal antibodies specific to Hepatopancreatic parvovirus (HPV) from Penaeus monodon

Hepatopancreatic parvovirus (HPV) was isolated from the hepatopancreas (HP) of slow growth Penaeus monodon by urografin gradient centrifugation. The presence of HPV in the fraction was monitored by PCR and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Only 1 major 54 kDa protein band was observed in the strong PCR-positive fractions used to immunize mice for monoclonal antibody production. After cell fusion, the first step in selecting specific antibodies was performed by dot-blot assay with purified HPV viral particles. The second screening step was carried out using Western blots of purified HPV proteins and immunohistochemistry of HPV-infected HP tissue. Four monoclonal antibodies were isolated; these bound to the 54 kDa protein in Western blots and to intranuclear inclusion bodies in tubule epithelial cells of HPV-infected prawn tissue by immunohistochemistry. None of the antibodies showed cross-reactivity either to uninfected shrimp tissue or to other shrimp viruses tested. These reagents have potential for use in developing a highly sensitive immunoassay such as sandwich ELISA or a convenient kit for detection of HPV infection.

Differences in susceptibility of palaemonid shrimp species to yellow head virus (YHV) infection

Five species of palaemonid shrimp, Macrobrachium rosenbergii, M. lanchesteri, M. sintangense, Palaemon styliferus and P. serrifer, were collected from Penaeus monodon farming areas in Thailand. Some of each species were artificially infected with yellow head virus (YHV) by injection and then monitored by RT-PCR and by immunohistochemistry using monoclonal antibodies specific to 116 kDa, 64 kDa, and 20 kDa proteins of YHV. Natural YHV infections were not detected in any of the shrimp examined. In YHV injection experiments, a high proportion of P. serrifer, P. styliferus and M. sintangense exhibited mild to moderate YHV infections at 3 d post-injection. The severity of infection was reduced in shrimp that survived to 10 and 30 d post-injection. Using immunohistochemistry and RT-PCR, a small proportion of M. lanchesteri showed very mild YHV infections at Day 3 but no infections at Days 10 and 30. No YHV infections resulted in M. rosenbergii. The evidence suggested that M. sintangense, P. styliferus and P. serrifer are susceptible to YHV and carry it for some time. In contrast, M, rosenbergii and M. lanchesteri appear to resist YHV infection and eliminate YHV efficiently. Because they display a range of responses to YHV, palaemonid shrimp may serve as a good model for studying YHV defense mechanisms in shrimp.

Monoclonal antibodies specific to haemocytes of black tiger prawn Penaeus monodon

Monoclonal antibodies specific to haemocytes of Penaeus monodon were generated from a mouse immunized with a mixture of SDS-treated and formalin-fixed haemocytes. Hybridoma clones were selected by immunohistochemistry against fixed haemocytes, heart, lymphoid organ, and haemopoietic tissue, and Western blot against haemocyte extract and haemolymph. Sixteen monoclonal antibodies specific to haemocytes were obtained and could be divided into six groups according to their binding capacities to various haemocyte proteins in Western blot analyses, 102, 43, approximately 20, 61, 175 and approximately 230 kDa, and their differences in recognition of haemocyte sub-populations. The first group of antibodies strongly recognized a small subset of semi-granulocytes (SG) and hyalinocytes (H) but occasionally stained lightly a very small population of granulocytes (G). The antibodies also bound to a group of cells in haemopoietic tissue as well as cells located at the inner layers of the tubules in the lymphoid organ but not in the spheroid. The second group of antibodies strongly bound to a large sub-population of G and SG with coarse granules but did not bind to most of the H. This group of antibodies also cross-reacted with cells in the outer layer of the tubules in the lymphoid organ. The third group of antibodies recognized all G and only a small portion of SG. The fourth, fifth and sixth groups bound to sub-populations of G, SG and H in similar proportions. None of the antibodies showed any cross-reactivity to other components in haemolymph. The common antigens recognized by the first and the second groups of antibodies in the haemopoietic tissue and the lymphoid organ may reflect relationships among these organs in the development of the sub-populations of G and SG. Haemopoietic tissue may be the site for haemocyte production and the lymphoid organ may be the site for further differentiation of at least two different lines of haemocytes.

Production of monoclonal antibodies for detection of Vibrio harveyi

Monoclonal antibodies (MAbs) against Vibrio harveyi were produced from mice immunized with heat-killed and SDS-mercaptoethanol-treated highly virulent V. harveyi 639. Fifteen MAbs were selected and sorted into 6 groups according to their specificity to various proteins of apparent molecular weight ranging from 8 to 49 kDa. Some antibodies were used for detection of V. harveyi at concentrations as low as 10(4) CFU ml(-1) using immunodot blots. Most of the selected MAbs did not show cross-reactivity to other Vibrio species and other gram-negative bacteria tested. Only 1 MAb (VH39-4E) showed slight cross-reactivity to Aeromonas hydrophila. Another MAb (VH24-8H) bound lightly to V. harveyi 1526 but strongly to V. harveyi 639, allowing rapid differentiation. Two of the MAb groups were used to localize V. harveyi in tissues of infected black tiger shrimp Penaeus monodon by immunohistochemistry. This study demonstrates the versatility of a highly specific immunological tool for the detection of V. harveyi in aquaculture and opens the way for further development of convenient test kits.

Immunolocalization of allatostatin-like neuropeptides and their putative receptor in eyestalks of the tiger prawn, Penaeus monodon

Allatostatin (AST)-like immunoreactivity (IR) was localized in the eyestalk of Penaeus monodon by immunohistochemistry using four anti-AST antibodies. Depending on the antisera, AST-like immunoreactivity was detected in neuronal bodies of the lamina ganglionalis, cell bodies anterior to the medulla externa and cell bodies on the anterior and posterior of the medulla terminalis. Neuronal processes in neuropiles of the medulla externa, medulla terminalis, sinus gland and nerve fibers in the optic nerve were also recognized. No IR in cell bodies or in nerve fibers was found in the medulla interna. Strong AST-like immunoreactivity was found in hundreds of cells of the X organ. The localization of AST-like peptides suggests that they function as neurotransmitters and/or neuromodulators. Antiserum to the Drosophila AST receptor (Dar-2) recognized a single protein in P. monodon eyestalk protein extracts that was identical in size to that found in Drosophila protein extracts. Using this antiserum the putative P. monodon AST receptor was localized to the sinus gland in both juvenile and adult eyestalks. To our knowledge this is the first demonstration of a neuropeptide receptor localized to the crustacean sinus gland. This suggests that ASTs may function directly on the sinus gland as a neuromodulator. In juvenile eyestalks, the putative AST receptor was also localized to neuronal X organ cells of the medulla terminalis in males but not in females. The significance of this sex-specific receptor localization is unclear but emphasizes that ASTs function within the nervous system of the eyestalk.

Four novel PYFs: members of NPY/PP peptide superfamily from the eyestalk of the giant tiger prawn Penaeus monodon

An immunocytochemical method was used for localization of pancreatic polypeptide (PP) immunoreactive substances in the eyestalk of Penaeus monodon using anti-C-terminal hexapeptide of PP (anti-PP6) antiserum. Approximately 200 neuronal cell bodies were recognized in the ganglia between the medulla interna (MI) and medulla terminalis (MT) and surrounding MT in conjunction with the neuronal processes in medulla externa (ME), MI, MT and sinus gland. About half of the PP immunoreactive neurons were also recognized by a combination of three monoclonal antibodies raised against FMRFamide-like peptides. Isolation of the PP immunoreactive substances from the eyestalk was performed using 7500 eyestalks extracted in methanol/acetic acid/water (90/1/9) followed by five to six steps of RP-HPLC separation. Dot-ELISA with anti-PP6 antiserum was used to monitor PP-like substances in various fractions during the purification processes. Four new sequences of one hexapeptide; RARPRFamide, and three nonapeptides; YSQVSRPRFamide, YAIAGRPRFamide and YSLRARPRFamide were identified, and named as Pem-PYF1-4 due to their structural similarity to the PYF found in squid Loligo vulgaris. Each of the new peptides shares four to seven common residues with the C-terminus of the squid PYF and with the NPFs found in other invertebrates. The NPY/PP superfamily as well as the FMRFamide peptide family may be present throughout vertebrates and invertebrates.

Differential expression of CMG peptide and crustacean hyperglycemic hormones (CHHs) in the eyestalk of the giant tiger prawn Penaeus monodon

Mouse antiserum against C-terminal amide of Pem-CMG (a peptide in the family of CHH/MIH/GIH) penta-deca peptide (RPRQRNQYRAALQRLamide=CMG-15) was generated and used for localization of the peptide in tissue and extract of the eyestalk of Penaeus monodon by means of immunohistochemistry and dot-ELISA in comparison with anti-T+ antiserum (T+=YANAVQTVamide : the putative C-terminal amide of crustacean hyperglycemic hormone (CHH) of Macrobrachium rosenbergii). The anti-CMG-15 antiserum did not show cross-reactivity to T+ peptide by dot-ELISA and vice versa for anti-T+ antiserum. In dot-ELISA of eyestalk extract of P. monodon after one step separation by RP-HPLC, anti-CMG-15 antiserum recognized different peptide fractions (F38-39) from those recognized by anti-T+ antiserum (F19, 40-41 and 47-51). Most of the T+ immunoreactive fractions (except F19) show higher hyperglycemic activity than the CMG immunoreactive fractions. In immunohistochemical localization, anti-CMG antiserum recognized only 2-3 neurons in medulla terminalis X-organ complex (MTXO) with long processes terminated in the sinus gland. The CMG-immunoreactive neurons were clearly distinct from CHH containing neurons situated in the same area. This evidence confirms the existing of CMG peptide which may play distinct roles from CHHs in hormonal regulation in P. monodon.

Monoclonal antibodies specific to yellow-head virus (YHV) of Penaeus monodon

Monoclonal antibodies specific to 22, 67 and 135 kDa proteins of yellow-head virus (YHV) were produced from a mouse immunized with partially purified YHV isolated from the haemolymph of experimentally YHV-infected Penaeus monodon. Four groups of monoclonal antibodies were identified. One group of antibodies bound only to native protein of YHV while the others were specific to 135, 67 and 22 kDa proteins in both native and denatured forms. All antibodies could be used to detect YHV infection by means of dot blot and immunohistochemistry. However, antibodies specific to the 22 kDa protein gave the best immunohistochemistry results in terms of intensity and sharpness of staining.

Seven novel FMRFamide-like neuropeptide sequences from the eyestalk of the giant tiger prawn Penaeus monodon

FMRFamide-like immunoreactivity (FLI) was localized in the eyestalk of Penaeus monodon by immunohistochemistry using a combination of three anti-FMRFamide-like peptide (FLPs) monoclonal antibodies. Approximately 3000 small neuronal cell bodies in the lamina ganglionalis; 100 medium to large size at the ganglion between the medulla interna and the medulla terminalis; and 250 medium size around the medulla terminalis were stained intensely. The neuronal processes in neuropils of the medulla externa, medulla interna, medulla terminalis, sinus gland and some nerve fibers in the optic nerve were also recognized. The small cell bodies, approximately 1500 cells, anterior to the medulla externa were stained inconsistently and the neuronal processes were not observed from these cells. Isolation of FLPs from 9000 eyestalks was performed using methanol/acetic/water (90:1:9) extraction. After the extract was partially purified using C18 cartridges, it was further purified by five to seven steps of RP-HPLC using three kinds of columns: C18; C8; and cyano, and three solvent systems: acetonitrile/trifluoro acetic acid; aceonitrile/heptafluoro butyric acid; and acetonitrile/triethyl ammonium acetate. Dot-ELISA using the combination of the same antibodies was used to monitor FLPs in the fractions during purification processes. Seven new sequences of FLPs were identified which can be divided into four subgroups according to the primary structure of the C-terminus: (1) GDRNFLRFamide; (2) AYSNLNYLRFamide; (3) AQPSMRLRFamide, SQPSMRLRFamide, SMPSLRLRFamide and DGRTPALRLRFamide; and (4) GYRKPPFNGSIFamide. These data indicate the high complexity of this peptide family in which multiple forms are usually exist.

Three more novel FMRFamide-like neuropeptide sequences from the eyestalk of the giant freshwater prawn Macrobrachium rosenbergii

In addition to five FMRFamide-like peptides (FLPs) previously isolated from the eyestalk of the giant freshwater prawn Macrobrachium rosenbergii (16), three more new FLPs (Mar-FLP6-8) were identified from minor immunoreactive fractions of 5,000 eyestalk extracted in methanol/acetic acid/water: DGGRNFLRFamide, GYGDRNFLRFamide and VSHNNFLRFamide. These three peptides share 5-6 common residues at the C-terminus with Mar-FLP1,2 and 3. This evidence reveals that the structural diversity and complexity of the FLP family in M. rosenbergii are similar to that found in other invertebrate species.

Development of a monoclonal antibody specific to yellow head virus (YHV) from Penaeus monodon

A monoclonal antibody specific to yellow head virus (YHV) was produced from a mouse immunized with gill extracts prepared from laboratory-reared Penaeus monodon dually infected with YHV and white spot syndrome virus (WSSV). One clone designated V3-2B specifically bound to native and SDS-treated viral specific antigens. Immunocytochemical studies of infected gills revealed viral specific immunoreactivities in the cytoplasm of gill tissue and in haemocytes. No antibody binding was observed in gills from non-infected shrimp. In addition, immunocytochemical examination of tissues from shrimp experimentally infected with YHV gave a positive reaction, while tissues from uninfected control shrimp or shrimp experimentally infected with WSSV did not. Western blot analysis indicated that the antibody reacted with a protein of approximately 135 kD that was present only in shrimp infected with YHV. In dot-blot indirect immunoperoxidase assays, the antibody was able to detect viral associated antigen in diluted haemolymph up to 1:50 dilution and in an ammonium sulfate precipitate of haemolymph up to 1:1000 dilution. The results suggested that this antibody might be useful for development of effective diagnostic techniques for both heavy and mild YHV infections in shrimp.

Immunochemical analysis and immunocytochemical localization of crustacean hyperglycemic hormone from the eyestalk of Macrobrachium rosenbergii

Heptapeptide (YANAVQV-NH2 = T-) and octapeptide (YANAVQTV-NH2 = T+), the putative C-terminus of crustacean hyperglycemic hormone (CHH) from the eyestalk of the giant freshwater prawn Macrobrachium rosenbergii, was synthesized by solid phase peptide synthesis and conjugated to bovine serum albumin, then used for immunization in swiss mice. Specificity of the antisera against both peptides was determined by indirect immunoperoxidase ELISA. The best response of antiserum against each peptide was used to determine the presence of the natural CHH in the eyestalk extract after separation by one step of RP-HPLC using dot-ELISA. The peptide immunoreactive substances were found in fraction 30 using anti-T- antiserum and in fraction 38 using anti-T+ antiserum. However, the CHH activity was found only in fractions 37-39. Immunocytochemical localization of peptide immunoreactive substances in the eyestalk of M. rosenbergii using the anti-T- antiserum did not show any specific staining. In contrast, the anti-T+ antiserum revealed specific staining on a group of 24 +/- 5 neurons in medulla terminalis ganglionic x-organ and their processes through the sinus gland. Similar results were also obtained using the eyestalk of another species, the giant tiger prawn Penaeus monodon, in which 34 +/- 4 neuronal cells were recognized. These results strongly indicate that the anti-T+ antibody can bind to the natural CHH while the anti-T- antibody can not; therefore, this isoform of CHH in M. rosenbergii should consist of 72 residues and threonine is predicted to be present at position 71.

Purification and characterization of an isoform of crustacean hyperglycemic hormone from the eyestalk of Macrobrachium rosenbergii

Isolation of the crustacean hyperglycemic hormone (CHH) from the eyestalk of the giant freshwater prawn Macrobrachium rosenbergii was performed using 5,000 ground eye-stalks extracted in methanol-acetic acid-water (90:1:9). After the extract was partially purified using C18 cartridges, it was further purified by eight steps of RP-HPLC using four kinds of columns: C18, C8, cyano and phenyl, and three solvent systems: acetonitrile (ACN)/trifluoroacetic acid, ACN/heptafluoroacetic acid and ACN/triethylammonium acetate. The bioassay of CHH during purification was done by injection of eluate fractions into eyestalk-ablated prawns and determination of the ability of the fractions to elevate glucose in the haemolymph. A complete amino acid sequence analysis was performed on one isoform of CHH (Mar-CHH-1), consisting of 71 residues. The sequence of Mar-CHH-1 shows considerable similarity (45-68%) to CHHs reported in other crustaceans. It is expected that there might be more than one isoform of CHH in M. rosenbergii.