Mg2+ binding triggers rearrangement of the IM30 ring structure, resulting in augmented exposure of hydrophobic surfaces competent for membrane binding.

The "inner membrane-associated protein of 30 kDa" (IM30), also known as "vesicle-inducing protein in plastids 1" (Vipp1), is found in the majority of photosynthetic organisms that use oxygen as an energy source, and its occurrence appears to be coupled to the existence of thylakoid membranes in cyanobacteria and chloroplasts. IM30 is most likely involved in thylakoid membrane biogenesis and/or maintenance, and has recently been shown to function as a membrane fusion protein in presence of Mg2+ However, the precise role of Mg2+ in this process and its impact on the structure and function of IM30 remains unknown. Here, we show that Mg2+ binds directly to IM30 with a binding affinity of ∼1 mm Mg2+ binding compacts the IM30 structure coupled with an increase in the thermodynamic stability of the proteins' secondary, tertiary, and quaternary structures. Furthermore, the structural alterations trigger IM30 double ring formation in vitro because of increased exposure of hydrophobic surface regions. However, in vivo Mg2+-triggered exposure of hydrophobic surface regions most likely modulates membrane binding and induces membrane fusion.

A simple method to estimate the isoelectric point of modified Tomato bushy stunt virus (TBSV) particles.

We present a simple method to estimate the isoelectric point (pI) of Tomato Bushy Stunt particles. We demonstrate that the combination of agarose gels with different pH buffers can be used to electrophorese the virus particles and their migration patterns can be compared. This method allows us to estimate the pI of the virus particles (wild type, wt, and genetically modified particles) and to monitor the effect of the pI of modified peptide side chains of the viral capsid subunit on the pI of the whole virus particle.

The tegument protein pp65 of human cytomegalovirus acts as an optional scaffold protein that optimizes protein uploading into viral particles.

UNLABELLED: The mechanisms that lead to the tegumentation of herpesviral particles are only poorly defined. The phosphoprotein 65 (pp65) is the most abundant constituent of the virion tegument of human cytomegalovirus (HCMV). It is, however, nonessential for virion formation. This seeming discrepancy has not met with a satisfactory explanation regarding the role of pp65 in HCMV particle morphogenesis. Here, we addressed the question of how the overall tegument composition of the HCMV virion depended on pp65 and how the lack of pp65 influenced the packaging of particular tegument proteins. To investigate this, we analyzed the proteomes of pp65-positive (pp65pos) and pp65-negative (pp65neg) virions by label-free quantitative mass spectrometry and determined the relative abundances of tegument proteins. Surprisingly, only pUL35 was elevated in pp65neg virions. As the abundance of pUL35 in the HCMV tegument is low, it is unlikely that it replaced pp65 as a structural component in pp65neg virions. A subset of proteins, including the third most abundant tegument protein, pUL25, as well as pUL43, pUL45, and pUL71, were reduced in pp65neg or pp65low virions, indicating that the packaging of these proteins was related to pp65. The levels of tegument components, like pp28 and the capsid-associated tegument proteins pp150, pUL48, and pUL47, were unaffected by the lack of pp65. Our analyses demonstrate that deletion of pp65 is not compensated for by other viral proteins in the process of virion tegumentation. The results are concordant with a model of pp65 serving as an optional scaffold protein that facilitates protein upload into the outer tegument of HCMV particles. IMPORTANCE: The assembly of the tegument of herpesviruses is only poorly understood. Particular proteins, like HCMV pp65, are abundant tegument constituents. pp65 is thus considered to play a major role in tegument assembly in the process of virion morphogenesis. We show here that deletion of the pp65 gene leads to reduced packaging of a subset of viral proteins, indicating that pp65 acts as an optional scaffold protein mediating protein upload into the tegument.

Long-term clinical and molecular remissions in patients with mantle cell lymphoma following high-dose therapy and autologous stem cell transplantation.

Long-term clinical and molecular remissions in patients with mantle cell lymphoma (MCL) following high-dose therapy (HDT) and autologous stem cell transplantation (ASCT) have been evaluated in only a few studies. Thirty-six patients with MCL received ASCT in our institution (27 patients undergoing first-line therapy, 8 patients undergoing second-line therapy, and 1 patient undergoing third-line therapy). In the case of long-term remission (≥5 years; n = 8), peripheral blood was tested for minimal residual disease (MRD) by t(11; 14) polymerase chain reaction (PCR) and immunoglobulin heavy-chain (IGH) PCR at the last follow-up. Ten-year overall survival (OS), progression-free survival (PFS), and freedom from progression (FFP) after first-line ASCT were 42 %, 43 %, and 54 %; after second-line ASCT, these were all 0 %. Four-year OS, PFS, and FFP for the first-line cohort were 75 %, 48 %, and 61 %, respectively. Four-year OS, PFS, and FFP after second-line ASCT were 55 %, 30 %, and 30 %, respectively. Treatment-related mortality (3 months after ASCT) was 0 %. The only prognostic factor for OS, PFS, and FFP was treatment line (p = 0.011, p = 0.046, and p = 0.023, respectively). No relapses occurred after 5 years following ASCT. So far, eight patients developed sustained long-term clinical and molecular complete remissions of up to 14.6 years following ASCT in the first treatment line. Sustained long-term clinical and molecular remissions can be achieved following ASCT in the first treatment line and apparently less frequent in the second treatment line.

MicroRNA expression and JAK2 allele burden in bone marrow trephine biopsies of polycythemia vera, essential thrombocythemia and early primary myelofibrosis.

BACKGROUND/AIMS: MicroRNAs (miRNAs) play an important role in cellular differentiation and cancer pathogenesis. However, their role in promoting the malignant phenotype of myeloproliferative diseases and their importance for differential diagnosis of early-stage chronic myeloproliferative diseases (CMPDs) remains widely obscure. METHODS: In this study, we systematically evaluated the differential expression of miRNAs previously described to be associated with myelopoiesis and myeloproliferative pathogenesis by quantitative RT-PCR in polycythemia vera, essential thrombocythemia, early primary myelofibrosis (PMF) and normal hematopoiesis. Our goal was to establish certain miRNAs as potential markers for CMPDs to facilitate the differentiation between these diseases and to further investigate molecular differences between the subtypes of myeloproliferative neoplasia. RESULTS: An aberrant expression of miRNAs 10a and 150 could be demonstrated for essential thrombocythemia and PMF as well as for polycythemia vera and PMF, respectively. The expression of miR-150 could further be shown to correlate with both JAK2 allele burden and peripheral blood counts. CONCLUSION: Thus, the miRNAs investigated in this study seem to be potential marker oncomiRs in the differential diagnosis of CMPDs and possibly hold potential for the elucidation of a JAK2-independent mechanism of pathogenesis.

Screening of platelet concentrates for bacterial contamination: spectrum of bacteria detected, proportion of transfused units, and clinical follow-up.

Screening of platelet concentrates (PCs) for bacterial contamination with cultivation methods is carried out as a routine procedure in some countries. The aim is to prevent the transfusion of contaminated PCs. The German Evaluation of Regular Monitoring Study Group conducted a prospective multicenter study on 52,243 PCs to investigate the prevalence of bacteria (BacT/ALERT, bioMerieux). This study describes the detected bacterial spectrum, the proportion of PCs with a positive test result that had been transfused, and the results of the clinical follow-up. One hundred thirteen (67%) of 169 potentially or confirmed positive units had already been transfused at the time of the first positive signal. The transfusion of units contaminated by Staphylococcus aureus, Serratia marcescens, and 73% of the units contaminated with Staphylococcus epidermidis, Staphylococcus capitis, or Staphylococcus saccharolyticus was prevented. In contrast, 85% of units with Propionibacterium acnes were transfused. A clonal relationship of the isolates from the pooled PCs and from the associated red blood cell concentrates was found in all investigated cases. The follow-up revealed six febrile reactions to culture-positive PCs not classified as transfusion reaction (TRs) by treating physicians. This demonstrates the importance of hemovigilance. Serious septic reactions due to Klebsiella pneumoniae in two units of one apheresis PC that had tested false-negative were reported; one had a fatal outcome. Culture systems reduce the risk of transfusion of contaminated PCs but cannot guarantee sterility. Physicians must be aware of bacterial contamination of PCs as a potential cause of TRs and must report all adverse events.

Molluscan mega-hemocyanin: an ancient oxygen carrier tuned by a ~550 kDa polypeptide.

BACKGROUND: The allosteric respiratory protein hemocyanin occurs in gastropods as tubular di-, tri- and multimers of a 35 x 18 nm, ring-like decamer with a collar complex at one opening. The decamer comprises five subunit dimers. The subunit, a 400 kDa polypeptide, is a concatenation of eight paralogous functional units. Their exact topology within the quaternary structure has recently been solved by 3D electron microscopy, providing a molecular model of an entire didecamer (two conjoined decamers). Here we study keyhole limpet hemocyanin (KLH2) tridecamers to unravel the exact association mode of the third decamer. Moreover, we introduce and describe a more complex type of hemocyanin tridecamer discovered in fresh/brackish-water cerithioid snails (Leptoxis, Melanoides, Terebralia). RESULTS: The "typical" KLH2 tridecamer is partially hollow, whereas the cerithioid tridecamer is almost completely filled with material; it was therefore termed "mega-hemocyanin". In both types, the staggering angle between adjoining decamers is 36 degrees . The cerithioid tridecamer comprises two typical decamers based on the canonical 400 kDa subunit, flanking a central "mega-decamer" composed of ten unique ~550 kDa subunits. The additional ~150 kDa per subunit substantially enlarge the internal collar complex. Preliminary oxygen binding measurements indicate a moderate hemocyanin oxygen affinity in Leptoxis (p50 ~9 mmHg), and a very high affinity in Melanoides (~3 mmHg) and Terebralia (~2 mmHg). Species-specific and individual variation in the proportions of the two subunit types was also observed, leading to differences in the oligomeric states found in the hemolymph. CONCLUSIONS: In cerithioid hemocyanin tridecamers ("mega-hemocyanin") the collar complex of the central decamer is substantially enlarged and modified. The preliminary O2 binding curves indicate that there are species-specific functional differences in the cerithioid mega-hemocyanins which might reflect different physiological tolerances of these gill-breathing animals. The observed differential expression of the two subunit types of mega-hemocyanin might allow individual respiratory acclimatization. We hypothesize that mega-hemocyanin is a key character supporting the adaptive radiation and invasive capacity of cerithioid snails.

Molecular mass of macromolecules and subunits and the quaternary structure of hemoglobin from the microcrustacean Daphnia magna.

The molecular masses of macromolecules and subunits of the extracellular hemoglobin from the fresh-water crustacean Daphnia magna were determined by analytical ultracentrifugation, multiangle laser light scattering and electrospray ionization mass spectrometry. The hemoglobins from hypoxia-incubated, hemoglobin-rich and normoxia-incubated, hemoglobin-poor Daphnia magna were analyzed separately. The sedimentation coefficient of the macromolecule was 17.4 +/- 0.1 S, and its molecular mass was 583 kDa (hemoglobin-rich animals) determined by AUC and 590.4 +/- 11.1 kDa (hemoglobin-rich animals) and 597.5 +/- 49 kDa (hemoglobin-poor animals), respectively, determined by multiangle laser light scattering. Measurements of the hemoglobin subunit mass of hemoglobin-rich animals by electrospray ionization mass spectrometry revealed a significant peak at 36.482 +/- 0.0015 kDa, i.e. 37.715 kDa including two heme groups. The hemoglobin subunits are modified by O-linked glycosylation in the pre-A segments of domains 1. No evidence for phosphorylation of hemoglobin subunits was found. The subunit migration behavior during SDS/PAGE was shown to be influenced by the buffer system used (Tris versus phosphate). The subunit mass heterogeneity found using Tris buffering can be explained by glycosylation of hemoglobin subunits. Based on molecular mass information, Daphnia magna hemoglobin is demonstrated to consist of 16 subunits. The quaternary structure of the Daphnia magna hemoglobin macromolecule was assessed by three-dimensional reconstructions via single-particle analysis based on negatively stained electron microscopic specimens. It turned out to be much more complex than hitherto proposed: it displays D4 symmetry with a diameter of approximately 12 nm and a height of about 8 nm.

TP53 mutations are frequent events in double-hit B-cell lymphomas with MYC and BCL2 but not MYC and BCL6 translocations.

Double-hit lymphomas (DHL) with MYC and either BCL2 or BCL6 rearrangements are rare neoplasms with an aggressive clinical presentation and grim prognosis. Moreover, molecular characterization of DHL remains insufficient, and especially the role of TP53 pathway disruption is unknown. We employed a next-generation sequencing approach to investigate the mutational status of TP53 in DHL and correlated genomic data with immunohistochemical reactivity for p53. We identified TP53 mutations in MYC+/BCL2+ lymphomas at a frequency intermediate between diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma. Remarkably, TP53 mutations were particularly scarce in MYC+/BCL6+ lymphomas. Our findings indicate a significant difference between these two types of DHL at a molecular level with pathogenetic implications, as arguably, TP53 mutations inhibiting p53 mediated promotion of apoptosis pose a synergistic advantage in clonal evolution of cells with malignantly enforced overexpression of BCL2. Immunohistochemical staining appears to be a sensitive surrogate of TP53 mutation status with moderate specificity.

3D reconstruction of the hemocyanin subunit dimer from the chiton Acanthochiton fascicularis.

Procedures are presented for the purification of the subunit dimer from Acanthochiton fasicularis hemocyanin. Electron microscopy of negatively stained specimens revealed a uniform population of macromolecules possessing the characteristic "boat shape". A 3D reconstruction from this EM data generated a approximately 3 nm resolution model that correlates well with earlier data of the purported subunit dimer, extracted from the 3D reconstruction of the didecamer of Haliotis tuberculata hemocyanin type 1.

[Late infectious complications after high-dose therapy and autologous blood stem cell transplantation]. / Späte infektiöse Komplikationen nach Hochdosistherapie und autologer Blutstammzelltransplantation.

AIM: Only a few data on frequency and character of late infectious complications after high-dose therapy (HDT) and autologous blood stem cell transplantation (ASCT) have been published. This prospective study was carried out to identify potential predictive factors for late infections (occurring after discharge following HDT) and to clarify the usefulness of prophylactic measures. PATIENTS AND METHODS: Clinical data of 192 consecutive patients treated with HDT and ASCT in a single hospital were analyzed on late infectious complications. After discharge following HDT, the 166 evaluable patients (84 with hematologic malignancies, 82 with solid tumors) had been examined and interviewed on infections every 4-12 weeks after ASCT. For Pneumocystis carinii prophylaxis, inhalation with pentamidine or oral cotrimoxazole was used for 3-4 months following ASCT. RESULTS: In the first 6 months following ASCT (after discharge) we saw on average one infectious episode per patient (median, range 0-6), usually light infections (mostly banal upper airway infections). 17 patients had to be treated in hospital for infectious (15 of whom with hematologic malignancies), three of whom (only with hematologic malignancies) died in spite of intensive care as a result of pneumonias due to opportunistic causative agents (mainly Pneumocystis carinii [PcP]). In the second half of the year after ASCT, five patients (with hematologic malignancies) had to be hospitalized due to infections. No further infection-related death occurred. Early documented infections (pneumonia, bacteremia or Clostridium difficile colitis) were associated with an increased risk for late serious infections. Zoster occurred in 18% of patients within 12 months, more frequently after increased pretreatment (25% vs. 11% after less pretreatment), most frequently in patients with relapsed lymphomas (32%). CONCLUSIONS: Significant late infectious complications after ASCT are uncommon. Patients with hematologic malignancies have a significantly increased risk of more serious infections and should be observed carefully. For risk patients with hematologic malignancies and possibly solid tumors, a strict PcP prophylaxis is required. Patients with relapsed lymphomas could possibly be treated preventively against zoster with low-dose aciclovir to reduce the extent of zoster disease. Each patient should be informed carefully that early signs of zoster require an effective zoster treatment as soon as possible.

Acetylcholine-binding protein in the hemolymph of the planorbid snail Biomphalaria glabrata is a pentagonal dodecahedron (60 subunits).

Nicotinic acetylcholine receptors (nAChR) play important neurophysiological roles and are of considerable medical relevance. They have been studied extensively, greatly facilitated by the gastropod acetylcholine-binding proteins (AChBP) which represent soluble structural and functional homologues of the ligand-binding domain of nAChR. All these proteins are ring-like pentamers. Here we report that AChBP exists in the hemolymph of the planorbid snail Biomphalaria glabrata (vector of the schistosomiasis parasite) as a regular pentagonal dodecahedron, 22 nm in diameter (12 pentamers, 60 active sites). We sequenced and recombinantly expressed two ∼25 kDa polypeptides (BgAChBP1 and BgAChBP2) with a specific active site, N-glycan site and disulfide bridge variation. We also provide the exon/intron structures. Recombinant BgAChBP1 formed pentamers and dodecahedra, recombinant BgAChBP2 formed pentamers and probably disulfide-bridged di-pentamers, but not dodecahedra. Three-dimensional electron cryo-microscopy (3D-EM) yielded a 3D reconstruction of the dodecahedron with a resolution of 6 Å. Homology models of the pentamers docked to the 6 Å structure revealed opportunities for chemical bonding at the inter-pentamer interfaces. Definition of the ligand-binding pocket and the gating C-loop in the 6 Å structure suggests that 3D-EM might lead to the identification of functional states in the BgAChBP dodecahedron.

Characterization of hemocyanin from the peacock mantis shrimp Odontodactylus scyllarus (Malacostraca: Hoplocarida).

Hemocyanin is the blue respiratory protein of many arthropod species. While its structure, evolution, and physiological function have been studied in detail in Decapoda, there is little information on hemocyanins from other crustacean taxa. Here, we have investigated the hemocyanin of the peacock mantis shrimp Odontodactylus scyllarus, which belongs to the Stomatopoda (Hoplocarida). O. scyllarus hemocyanin forms a dodecamer (2 × 6-mer), which is composed of at least four distinct subunit types. We obtained the full-length cDNA sequences of three hemocyanin subunits, while a fourth cDNA was incomplete at its 5' end. The complete full-length cDNAs of O. scyllarus hemocyanin translate into polypeptides of 650-662 amino acids, which include signal peptides of 16 or 17 amino acids. The predicted molecular masses of 73.1-75.1 kDa correspond well with the main hemolymph proteins detected by SDS-PAGE and Western blotting using various anti-hemocyanin antibodies. Phylogenetic analyses show that O. scyllarus hemocyanins belong to the ß-type of malacostracan hemocyanin subunits, which diverged from the other subunits before the radiation of the malacostracan subclasses around 520 million years ago. Molecular clock analysis revealed an ancient and complex pattern of hemocyanin subunit evolution in Malacostraca and also allowed dating divergence times of malacostracan taxa.

10-A cryoEM structure and molecular model of the Myriapod (Scutigera) 6x6mer hemocyanin: understanding a giant oxygen transport protein.

Oxygen transport in Myriapoda is maintained by a unique 6x6mer hemocyanin, that is, 36 subunits arranged as six hexamers (1x6mers). In the sluggish diplopod Spirostreptus, the 1x6mers seem to operate as almost or fully independent allosteric units (h approximately 1.3; P(50) approximately 5 torr), whereas in the swift centipede Scutigera, they intensively cooperate allosterically (h approximately 10; P(50) approximately 50 torr). Here, we show the chemomechanical basis of this differential behavior as deduced from hybrid 6x6mer structures, obtained by single-particle cryo-electron microscopy of the Scutigera 6x6mer (10.0 A resolution according to the 0.5 criterion) and docking of homology-modeled subunits from Scutigera and two diplopods, Spirostreptus and Polydesmus. The Scutigera 6x6mer hemocyanin is a trigonal antiprism assembled from six smaller trigonal antiprisms (1x6mers), thereby exhibiting D3 point group symmetry. It can be described as two staggered 3x6mers or three oblique 2x6mers. Topologically, the 6x6mer is subdivided into six subunit zones, thereby exhibiting a mantle (24 subunits) and a core (12 subunits). The six hexamers are linked by 21 bridges, subdivided into five types: two within each 3x6mer and three between both 3x6mers. The molecular models of the 6x6mer reveal intriguing amino acid appositions at these inter-hexamer interfaces. Besides opportunities for salt bridges, we found pairs of carboxylate residues for possible bridging via a Ca(2+) or Mg(2+) ion. Moreover, we detected histidine clusters, notably in Scutigera, allowing us to advance hypotheses as to how the hexamers are allosterically coupled in centipede hemocyanin and why they act more independently in diplopod hemocyanin.

Bacterial contamination of platelet concentrates: results of a prospective multicenter study comparing pooled whole blood-derived platelets and apheresis platelets.

BACKGROUND: The GERMS Group initiated a prospective multicenter study to assess prevalence and nature of bacterial contamination of pooled buffy-coat platelet concentrates (PPCs) and apheresis platelet concentrates (APCs) by routine screening with a bacterial culture system. STUDY DESIGN AND METHODS: In nine centers overall, 52,243 platelet (PLT) concentrates (15,198 APCs, 37,045 PPCs) were analyzed by aerobic and anaerobic cultures (BacT/ALERT, bioMérieux). RESULTS: In 135 PLT concentrates (PCs; 0.26%), bacteria could be identified in the first culture (0.4% for APCs vs. 0.2% for PPCs; p < 0.001). In 37 (0.07%) of these PC units, the same bacteria strain could be identified in a second culture from the sample bag and/or the PC unit. The rate of confirmed-positive units did not differ significantly between APC (0.09%; 1/1169) and PPC units (0.06%; 1/1544). Bacteria from skin flora (Propionibacterium acnes, Staphylococcus epidermidis) were the most prevalent contaminants. Median times to first positive culture from start of incubation were 0.7 and 3.7 days in aerobic and anaerobic cultures for confirmed-positive units. With a "negative-to-date" issue strategy, most PC units (55%) had already been issued by time of the first positive culture. CONCLUSION: The rate of confirmed bacterial contamination of PC units was low. Nevertheless, clinicians must be aware of this risk. The risk of bacterial contamination does not warrant universal preference of APCs. It must be questioned whether routine bacterial screening by a culture method can sufficiently prevent contaminated products from being transfused due to the delay until a positive signal in the culture system and due to false-negative results.

Red blood with blue-blood ancestry: intriguing structure of a snail hemoglobin.

The phylogenetic enigma of snail hemoglobin, its isolated occurrence in a single gastropod family, the Planorbidae, and the lack of sequence data, stimulated the present study. We present here the complete cDNA and predicted amino acid sequence of two hemoglobin polypeptides from the planorbid Biomphalaria glabrata (intermediate host snail for the human parasite Schistosoma mansoni). Both isoforms contain 13 different, cysteine-free globin domains, plus a small N-terminal nonglobin "plug" domain with three cysteines for subunit dimerization (total M(r) approximately 238 kDa). We also identified the native hemoglobin molecule and present here a preliminary 3D reconstruction from electron microscopical images (3 nm resolution); it suggests a 3 x 2-mer quaternary structure (M(r) approximately 1.43 MDa). Moreover, we identified a previously undescribed rosette-like hemolymph protein that has been mistaken for hemoglobin. We also detected expression of an incomplete hemocyanin as trace component. The combined data show that B. glabrata hemoglobin evolved from pulmonate myoglobin, possibly to replace a less-efficient hemocyanin, and reveals a surprisingly simple evolutionary mechanism to create a high molecular mass respiratory protein from 78 similar globin domains.

cDNA sequence, protein structure, and evolution of the single hemocyanin from Aplysia californica, an opisthobranch gastropod.

By protein immunobiochemistry and cDNA sequencing, we have found only a single hemocyanin polypeptide in an opisthobranch gastropod, the sea hare Aplysia californica, which contrasts with previously studied prosobranch gastropods, which express two distinct isoforms of this extracellular respiratory protein. We have cloned and sequenced the cDNA encoding the complete polypeptide of Aplysia californica hemocyanin (AcH). The cDNA comprises 11,433 bp, encompassing a 5'UTR of 77 bp, a 3'UTR of 1057 bp, and an open reading frame for a signal peptide of 20 amino acids plus a polypeptide of 3412 amino acids (Mr ca. 387 kDa). This polypeptide is the subunit of the cylindrical native hemocyanin (Mr ca. 8 MDa). It comprises eight different functional units (FUs: a, b, c, d, e, f, g, h) that have been identified immunobiochemically after limited proteolysis of AcH purified from the hemolymph. Each FU shows a highly conserved copper-A and copper-B site for reversible oxygen binding. FU AcH-h carries a specific C-terminal extension of ca. 100 amino acids that include two cysteines that may be utilized for disulfide bridge formation. Potential N-glycosylation sites are present in six FUs but lacking in AcH-b and AcH-c. On the basis of multiple sequence alignments, phylogenetic trees and a statistically firm molecular clock were calculated. The latter suggests that the last common ancestor of Haliotis and Aplysia lived 373+/-47 million years ago, in convincing agreement with fossil records from the early Devonian. However, the gene duplication yielding the two distinct hemocyanin isoforms found today in Haliotis tuberculata occurred 343+/-43 million years ago.