Haliotis Rufescens Research Articles

A note on the n-stage growth model. Overview

In this paper we study the one-sided Hausdorff approximation of the generalized cut function by sigmoidal general n-stage growth model.В For some conditions of the reaction constants, the model has a certain right of existence insofar as the theory of sigmoidal functions is well developed.В The estimates of the value of the best Hausdorff approximation obtained in this article can be used in practice as one possible additional criterions in ''saturation'' and ''lag-time'' study. We examine the small data for modeling the growth of red abalone (Haliotis Rufescens) in Northern California.В Numerical examples are presented usingВ CAS MATHEMATICA.

Factors Affecting Gastropod Larval Development and Performance: A Systematic Review

The goal of this article was to use a systematic review of studies on the larval stages of gastropods reared to metamorphosis to determine whether there are general patterns for the effects of temperature, rearing density, and food availability on larval development and performance among species, major taxa, and modes of development. Most studies did not include sufficient metadata to be included in many of the analyses. For all analyses, there were differences among major groups of taxa in terms of response to the considered variables. Increased temperature was frequently correlated with decreased development time and increased growth but often not for the same taxa. Increased larval density was generally correlated with increased development time, but again, the patterns were not consistent across taxa. The most consistent pattern was the positive correlation between per capita food availability and larval growth. In all but two cases, patterns for the most studied species, Crepidula fornicata, were opposite those of other caenogastropods. This indicates that caution should be used when drawing general patterns among species based on studies of C. fornicata. Among lecithotrophs, the vetigastropod Haliotis rufescens was the most studied. In this case, patterns found for this species were similar to those for all other vetigastropods; however, few species outside the genus Haliotis have been studied. Increased temperature was associated with reduced survivorship and, in the most studied clade, the Vetigastropoda, reduced time to metamorphosis, which suggests that there may be an energetic cost to more rapid development or physiological mechanisms for coping with heat stress. Curiously, increased larval density was associated with increased survivorship for lecithotrophs. In several cases, however, there were too few studies, or the studies that were found did not provide enough metadata to be included in analyses. Although some patterns emerged from existing research on gastropod larvae, studies on a more diverse set of species that report all metadata are required for cross-study comparisons, which are crucial for drawing robust general conclusions.

Prehistoric Shellfish Utilization and Settlement Systems on Western Santa Cruz Island

Archaeologists generally have not taken advantage of the distinctive characteristics of assemblages of shellfish remains from prehistoric sites to gain information about movement of people between sites within their territory. I attempt to demonstrate this potential through analysis of shell assemblages obtained through small-scale test excavation at 2 archaeological sites in the interior of Santa Cruz Island: CA-SCRI-796 in the western sector of the island and CA-SCRI-758 at an upland location in the central sector. An aspect of the data analysis focused on strata containing an abundance of red abalone shells, dating sometime between 3700 and 3350 cal BC at CA-SCRI-796 and sometime between 4900 and 4325 cal BC at CA-SCRI-758. Also considered are assemblages from later strata at CA-SCRI-758, dating between 2600 and 1600 cal BC. Alternative hypotheses to account for the differences between the sites in proportions of shellfish taxa represented are the following: differences in proportional abundances of taxa at the localities where site inhabitants collected shellfish, changes over time in the character of shellfish communities, different distances of the sites from sources of shellfish, and variation in the intensity of shellfish collecting. The first alternative appears to account for most of the differences between assemblages, thus providing information about the geographic extent of settlement systems.

Cloning and molecular characterization of two ferritins from red abalone Haliotis rufescens and their expressions in response to bacterial challenge at juvenile and adult life stages

Ferritins are ubiquitous proteins with a pivotal role in iron storage and homeostasis, and in host defense responses during infection by pathogens in several organisms, including mollusks. In this study, we characterized two ferritin homologues in the red abalone Haliotis rufescens, a species of economic importance for Chile, USA and Mexico. Two ferritin subunits (Hrfer1 and Hrfer2) were cloned. Hrfer1 cDNA is an 807 bp clone containing a 516 bp open reading frame (ORF) that corresponds to a novel ferritin subunit in H. rufescens. Hrfer2 cDNA is an 868 bp clone containing a 516 bp ORF that corresponds to a previously reported ferritin subunit, but in this study 5′- and 3′-UTR sequences were additionally found. We detected a putative Iron Responsive Element (IRE) in the 5′-UTR sequence, suggesting a posttranscriptional regulation of Hrfer2 translation by iron. The deduced protein sequences of both cDNAs possessed the motifs and domains required in functional ferritin subunits. Expression patterns of both ferritins in different tissues, during different developmental stages, and in response to bacterial (Vibrio splendidus) exposure were examined. Both Hrfer1 and Hrfer2 are most expressed in digestive gland and gonad. Hrfer1 mRNA levels increased about 34-fold along with larval developmental process, attaining the highest level in the creeping post-larvae. Exogenous feeding is initiated at the creeping larva stage; thus, the increase of Hrfer1 may suggest and immunity-related role upon exposure to bacteria. Highest Hrfer2 expression levels were detected at trochophore stage; which may be related with early shell formation. Upon challenge with, the bacteria an early mild induction of Hrfer2 (2 h post-challenge), followed by a stronger induction of Hrfer1 at 15 h post-challenge, was observed in haemocytes from adult abalones. While maximal upregulation of both genes in the whole individual occurred at 24 h post-challenge, in juveniles. A significant increase in ferritin protein levels from 6 h to 24 h post-challenge was also detected. Our results suggest an involvement of Hrfer1 and Hrfer2, and of ferritin proteins in the immune response of H. rufescens to bacterial infection.

Acceptability of silage from brown seaweed (lessonia trabeculata) by the red abalone (haliotis rufescens) in experimental conditions

El valor nutricional durante la preparacion y conservacion de los ensilados sigue siendo de gran interes para el consumo humano y animal. El objetivo del estudio fue demostrar si el abalon rojo ( Haliotis rufescens ) consume el ensilado de alga parda ( Lessonia trabeculata ) en condiciones experimentales, en el Centro Acuicola de Morro Sama-Tacna FONDEPES, durante los anos 2017 y 2018. Se experimento con el grupo control (alga fresca) y dos tipos de ensilado, tratamientos: T1 (ensilado 0% en base seca) y T2 (ensilado 35% en base seca) durante 62 dias; determinandose en el alga fresca el contenido de proteinas, grasas, hidratos de carbono y energia, no se observo diferencias estadisticamente significativas (p<0.05) entre los tratamientos, excepto para el contenido de grasas. En los tratamientos, se observo la aceptacion del alimento durante 10 dias y se estimo el consumo del alimento, las tallas y pesos que fueron estadisticamente similares. Se concluyo que: los abalones consumen el ensilado y que los mayores porcentajes de la composicion bromatologica correspondio al T2, su consumo para la ganancia de peso y talla de Haliotis rufescens donde probablemente, estas variables aumenten cuando exista mayor porcentaje del ensilado con base en materia seca o mayores dias de consumo. El analisis microbiologico demostro que los ensilados son aptos para el consumo de la especie. ABSTRACT The nutritional value during the preparation and conservation of the silage is still of great interest for human and animal consumption. The objective of the study was to demonstrate if the Red abalone ( Haliotis rufescens ) consumes the silage of Brown seaweed ( Lessonia trabeculata ) under experimental conditions, on the Morro Sama-Tacna FONDEPES aquaculture Centre, during the years 2017 and 2018. We experimented with the control group (fresh seaweed) and two types of silage, treatments: T1 (silage 0% on dry basis) and T2 (silage 35% on dry basis) for 62 days; determining the content of proteins, fats, carbohydrates and energy in the fresh seaweed, no statistically significant difference (p < 0.05) were observed between the treatments, except for the fat content. Treatments, food acceptance was observed during 10 days and food consumption, sizes and weights were estimated with statistically similar. It was concluded that the abalone eat silage and the highest percentages of bromatological composition corresponded to T2, its consumption to gain weight and height of Haliotis rufescens where probably these variables increase when there is a higher percentage of silage based on dry matter or more days of consumption. Microbiological analysis showed that the silages are suitable for the consumption of the species. Key words: silage algal, drying, food science, biomass.

Laser imaging polarimetry of nacre.

Nacre is a complex biomaterial made of aragonite-tablet bricks and organic mortar that is considerably resilient against breakage. Nacre has been studied with a wide range of laboratory techniques, leading to understanding key fundamentals and informing the creation of bio-inspired materials. In this article, we present an optical polarimetric technique to investigate nacre, taking advantage of the translucence and birefringence of its microcomponents. We focus our study on 3 classes of mollusks that have nacreous shells: bivalve (Pinctada fucata), gastropod (Haliotis asinina and Haliotis rufescens) and cephalopod (Nautilus pompilius). We sent polarized light from a laser through thin samples of nacre and did imaging polarimetry of the transmitted light. We observed clear distinctions between the structures of bivalve and gastropod, due to the spatial variation of their birefringence. The patterns for cephalopod were more similar to bivalve than gastropod. Bleaching of the samples disrupted the transmitted light. Subsequent refilling of the bivalve and gastropod nacre samples with oil produced optical patterns similar to those of unbleached samples. In cephalopod samples, we found that bleaching produced irreversible changes in the optical pattern.

Differing responses of red abalone (Haliotis rufescens) and white abalone (H. sorenseni) to infection with phage-associated Candidatus Xenohaliotis californiensis.

The Rickettsiales-like prokaryote and causative agent of Withering Syndrome (WS)—Candidatus Xenohaliotis californiensis (Ca. Xc)—decimated black abalone populations along the Pacific coast of North America. White abalone—Haliotis sorenseni—are also susceptible to WS and have become nearly extinct in the wild due to overfishing in the 1970s. Candidatus Xenohaliotis californiensis proliferates within epithelial cells of the abalone gastrointestinal tract and causes clinical signs of starvation. In 2012, evidence of a putative bacteriophage associated with Ca. Xc in red abalone—Haliotis rufescens—was described. Recently, histologic examination of animals with Ca. Xc infection in California abalone populations universally appear to have the phage-containing inclusions. In this study, we investigated the current virulence of Ca. Xc in red abalone and white abalone at different environmental temperatures. Using a comparative experimental design, we observed differences over time between the two abalone species in mortality, body condition, and bacterial load by quantitative real time PCR (qPCR). By day 251, all white abalone exposed to the current variant of Ca. Xc held in the warm water (18.5 °C) treatment died, while red abalone exposed to the same conditions had a mortality rate of only 10%, despite a relatively heavy bacterial burden as determined by qPCR of posterior esophagus tissue and histological assessment at the termination of the experiment. These data support the current status of Ca. Xc as less virulent in red abalone, and may provide correlative evidence of a protective phage interaction. However, white abalone appear to remain highly susceptible to this disease. These findings have important implications for implementation of a white abalone recovery program, particularly with respect to the thermal regimes of locations where captively-reared individuals will be outplanted.

In-depth proteomic analyses of Haliotis laevigata (greenlip abalone) nacre and prismatic organic shell matrix

BackgroundThe shells of various Haliotis species have served as models of invertebrate biomineralization and physical shell properties for more than 20 years. A focus of this research has been the nacreous inner layer of the shell with its conspicuous arrangement of aragonite platelets, resembling in cross-section a brick-and-mortar wall. In comparison, the outer, less stable, calcitic prismatic layer has received much less attention. One of the first molluscan shell proteins to be characterized at the molecular level was Lustrin A, a component of the nacreous organic matrix of Haliotis rufescens. This was soon followed by the C-type lectin perlucin and the growth factor-binding perlustrin, both isolated from H. laevigata nacre, and the crystal growth-modulating AP7 and AP24, isolated from H. rufescens nacre. Mass spectrometry-based proteomics was subsequently applied to to Haliotis biomineralization research with the analysis of the H. asinina shell matrix and yielded 14 different shell-associated proteins. That study was the most comprehensive for a Haliotis species to date.MethodsThe shell proteomes of nacre and prismatic layer of the marine gastropod Haliotis laevigata were analyzed combining mass spectrometry-based proteomics and next generation sequencing.ResultsWe identified 297 proteins from the nacreous shell layer and 350 proteins from the prismatic shell layer from the green lip abalone H. laevigata. Considering the overlap between the two sets we identified a total of 448 proteins. Fifty-one nacre proteins and 43 prismatic layer proteins were defined as major proteins based on their abundance at more than 0.2% of the total. The remaining proteins occurred at low abundance and may not play any significant role in shell fabrication. The overlap of major proteins between the two shell layers was 17, amounting to a total of 77 major proteins.ConclusionsThe H. laevigata shell proteome shares moderate sequence similarity at the protein level with other gastropod, bivalve and more distantly related invertebrate biomineralising proteomes. Features conserved in H. laevigata and other molluscan shell proteomes include short repetitive sequences of low complexity predicted to lack intrinsic three-dimensional structure, and domains such as tyrosinase, chitin-binding, and carbonic anhydrase. This catalogue of H. laevigata shell proteins represents the most comprehensive for a haliotid and should support future efforts to elucidate the molecular mechanisms of shell assembly.

Gene structure and domain architecture in the biomineralizing protein Lustrin A from the abalone Haliotis rufescens

Among the proteins that play a role in molluscan biomineralization, Lustrin A was the first to be investigated and it remains the most-well studied. It is composed of many repetitive domains, which appear to be present in all members of the family Haliotidae. For the first time we have sequenced the complete gene (34,093 bp), coding for the cDNA of Haliotis rufescens Lustrin A, using long PCRs and cloning. It encompasses 34 exons and 33 introns, including 10 minisatellite-rich regions present in eight of these introns. The corresponding glycine and serine-rich (GS) domain and the C-terminus-WAP domain are well delimited by phase 1 introns, while phase 0 introns separate the Cysteine-rich domains. Within these domains, the Hr_Lustrin gene contains 10 phase 1 introns. No codon bias was detected in the nucleotide composition. We discuss the observe intron specificity together with the absence of exons corresponding to putative spacer regions or basic domains. We also compared H. rufescens Lustrin A with the H. tuberculata Lustrin A gene partial sequence.

Genetic Selection For Fast-Growing Traits Among Haliotis Rufescens Mollusks

Genetic Selection For Fast-Growing Traits Among Haliotis Rufescens Mollusks

Heritability of energy intake and allocation and their correlated responses to selection on growth traits in cultured juvenile and adult red abalone Haliotis rufescens

Increasing abalone growth rates and their physiological efficiency in the use of energy through selective breeding could improve abalone production. High potential responses to selection for growth traits have been estimated in several abalone species; however, the genetic bases underlying individual differences in physiological performance are unknown. The aims of this study were to estimate the heritable variation of physiological traits associated with energy intake and allocation for the red abalone Haliotis rufescens; and the potential correlated responses to selection between growth and physiological traits at three developmental stages. Growth traits (shell length and width, and total mass) and physiological traits [energy intake, standard metabolic rate (SMR), and energy losses by ammonia excretion and feces] were measured in individuals belonging to 60 full-sib families in 2-years old juveniles, 3-y old young adults, and 4-y old near-harvest adult (n = 500–380 individuals/age; total n = 1300). Food intake showed significant h2 in juveniles and young adults (0.37 and 0.14, respectively); but near zero h2 in near-harvest adults. Variation in energy required for SMR showed low but significant h2 (0.13) in young and near-harvest adults. Variation in energy lost through ammonia excretion showed significant h2 in juveniles (0.33) and in near-harvest adults (0.14). Heritability for variation in the energy losses through feces was not significant. Heritabilities for growth traits were all moderate to high and significant for young and pre-harvest adults, but were not significant for juveniles. At the young adult stage, food intake was negatively and highly genetically correlated with each of the growth traits (−0.70 to −0.85); and at the near-harvest adult stage both SMR and ammonia excretion showed high-negative genetic correlations with each growth trait (−0.88 to −1.00). Thus, estimated correlated response to selection indicated that if selection was exerted for higher growth (choosing 5% best individuals), we would be indirectly selecting for abalones with lower food intake (correlated responses of −11 to −15%); or lower metabolic demands of (−14 to −24%), if the selection was applied to young or near-harvest adults, respectively. In turn, shell length could be enhanced up to 18% per generation. These results suggest that higher growth in red abalone is genetically associated with a more efficient use of food and a lower metabolic demand. The possibility to reduce food intake or metabolic demands by selecting for faster growing abalones would be a very positive development for the sustainability of this culture.

Monomorphic pathogens: The case of Candidatus Xenohaliotis californiensis from abalone in California, USA and Baja California, Mexico.

Withering syndrome (WS) is a chronic wasting disease affecting abalone species attributed to the pathogen Candidatus Xenohaliotis californiensis (CXc). Wild populations of blue (Haliotis fulgens) and yellow (H. corrugata) abalone have experienced unusual mortality rates since 2009 off the peninsula of Baja California and WS has been hypothesized as a possible cause. Currently, little information is available about the genetic diversity of CXc and particularly the possible existence of strains differing in pathogenicity. In a recent phylogenetic analysis, we characterized five coding genes from this rickettsial pathogen. Here, we analyze those genes and two additional intergenic non-coding regions following multi-locus sequence typing (MLST) and multi-spacer typing (MST) approaches to assess the genetic variability of CXc and its relationship with blue, yellow and red (H. rufescens) abalone. Moreover, we used 16S rRNA pyrosequencing reads from gut microbiomes of blue and yellow abalone to complete the genetic characterization of this prokaryote. The presence of CXc was investigated in more than 150 abalone of the three species; furthermore, a total of 385 DNA sequences and 7117 16S rRNA reads from Candidatus Xenohaliotis californiensis were used to evaluate its population genetic structure. Our findings suggest the absence of polymorphism in the DNA sequences of analyzed loci and the presence of a single lineage of CXc infecting abalone from California (USA) and Baja California (Mexico). We posit that the absence of genetic variably in this marine rickettsia may be the result of evolutionary and ecological processes.

Assessment of oxytetracycline baths as therapeutic treatment for the control of the agent of withering syndrome (WS) in red abalone (Haliotis rufescens).

Withering Syndrome (WS) is a lethal disease that affects abalone species in both wild and farmed populations. This infection, caused by the rickettsial-like intracellular organism (RLO) Candidatus Xenohaliotis californiensis, can severely impair the normal development of affected animals, and ultimately, their survival. The most common line of action against the WS has been the use of antibiotics, specifically oxytetracycline (OTC), administered via intramuscular injection and per os via medicated feed. In the present study, we have assessed the effectiveness of OTC baths as therapeutic treatment for the control of the WS agent in H. rufescens. Clinical signs of infection were monitored for 11 months in treated juveniles, in addition to feed consumption rate, growth patterns and gonad development. Abalones were asymptomatic until the end of the experiment, when a small number of non-treated animals exhibited clinical signs of infection. Gonad maturity was not observed. OTC treated animals grew significantly less than their non-treated counterparts, being 4.3% shorter and 13.6% lighter at the end of the experiment. They also displayed negative allometry, i.e. for the same shell length, they were lighter than non-treated groups. Furthermore, the weight of muscle and soft tissues in OTC treated animals was lighter than in the other groups, while no differences were found in shell weight. The feed consumption rate was the same for all groups, thus the observed growth patterns cannot be attributed to a decreased feed intake. One possible explanation is that antibiotic treatment may have impacted gut microflora, thus preventing efficient nutrient digestion and absorption and, indirectly, reducing growth. Prevalence of RLOs causing WS (WS-RLO) and the variant form (RLOv), infected with a bacteriophague and non virulent, were significantly lower in the OTC-treated group than in the other groups. Similar results were observed for the mean intensity of RLOv, while for WS-RLO, the intensity in the OTC-treated group was higher, although not statistically significant, than the rest of the groups. These observations may be the consequence of an increased bacterial sensitivity to OTC effects associated with the phage infection or faster reproduction of WS-RLOs than RLOv after OTC treatment. Our results let us infer that the prophylactic use of OTC in abalone to avoid the negative effects of WS on abalone farms could have an undesired negative effect on the biological control exerted by the phage on the bacteria after OTC treatment.

Temporal and spatial patterns in behavioral responses of marine predators to a sudden influx of abalone prey (Haliotis rufescens)

Predator–prey interactions exist on a variety of spatial and temporal scales; one of the earliest measurable responses to changes in these interactions is behavior. We examined the behavior of southern California kelp forest predators in response to a concentrated increase in the abundance of abalone during a restoration stocking experiment. We tested three hypotheses: (1) kelp forest predator density will increase following abalone stocking, (2) variations in predator characteristics will create an unequal impact on abalone, and (3) predation intensity will be greatest early in the experiment. Octopus discovered and exploited the influx of prey within the first week following stocking; their densities surged and then returned to pre-stocking levels after 2 months. This was not observed with any other predator. Damage from crustacean, fish, and octopus predation was observed on the recovered abalone shells, but were not correlated with predator densities. A larger percentage of recovered small shells had evidence of crustacean and fish predation, indicating there may be size-specific impacts of predators on abalone. Our results demonstrate that restoration stocking experiments can quantitatively test the predatory community’s response to reintroductions, as well as predation risk of newly stocked prey species when exposed to a diverse suite of predators.

Solution structure of sperm lysin yields novel insights into molecular dynamics of rapid protein evolution

Protein evolution is driven by the sum of different physiochemical and genetic processes that usually results in strong purifying selection to maintain biochemical functions. However, proteins that are part of systems under arms race dynamics often evolve at unparalleled rates that can produce atypical biochemical properties. In the marine mollusk abalone, lysin and vitelline envelope receptor for lysin (VERL) are a pair of rapidly coevolving proteins that are essential for species-specific interactions between sperm and egg. Despite extensive biochemical characterization of lysin-including crystal structures of multiple orthologs-it was unclear how sites under positive selection may facilitate recognition of VERL. Using a combination of targeted mutagenesis and multidimensional NMR, we present a high-definition solution structure of sperm lysin from red abalone (Haliotis rufescens). Unapparent from the crystallography data, multiple NMR-based analyses conducted in solution reveal clustering of the N and C termini to form a nexus of 13 positively selected sites that constitute a VERL binding interface. Evolutionary rate was found to be a significant predictor of backbone flexibility, which may be critical for lysin bioactivity and/or accelerated evolution. Flexible, rapidly evolving segments that constitute the VERL binding interface were also the most distorted regions of the crystal structure relative to what was observed in solution. While lysin has been the subject of extensive biochemical and evolutionary analyses for more than 30 years, this study highlights the enhanced insights gained from applying NMR approaches to rapidly evolving proteins.

Complete genome sequence of a phage hyperparasite of Candidatus Xenohaliotis californiensis (Rickettsiales) – a pathogen of Haliotis spp (Gasteropoda)

Bacteriophages are recognized as major mortality agents of microbes, among them intracellular marine rickettsiales-like bacteria. Recently, a phage hyperparasite of Candidatus Xenohaliotis californiensis (CXc) has been described. This bacterium is considered the causal agent of Withering Syndrome (WS) which is a chronic and potentially lethal disease of abalone species from California, USA and the peninsula of Baja California, Mexico. This hyperparasite which infects CXc could be used as a biocontrol agent for WS. Therefore, it is necessary to obtain genomic information to characterize this phage. In this study, the first complete genome sequence of a novel phage, Xenohaliotis phage (pCXc) was determined. The complete genome of pCXc from red abalone (Haliotis rufescens) is 35,728 bp, while the complete genome of pCXc from yellow abalone (Haliotis corrugata) is 35,736 bp. Both phage genomes consist of double-stranded DNA with a G+C content of 38.9%. In both genomes 33 open reading frames (ORFs) were predicted. Only 10 ORFs encode proteins that have identifiable functional homologues. These 10 ORFs were classified by function, including structural, DNA replication, DNA packaging, nucleotide transport and metabolism, life cycle regulation, recombination and repair, and additional functions. A PCR method for the specific detection of pCXc was developed. This information will help to understand a new group of phages that infect intracellular marine rickettsiales-like bacteria in mollusks.

Convective Drying of Osmo-Treated Abalone (Haliotis rufescens) Slices: Diffusion, Modeling, and Quality Features

The focus of this research was based on the application of an osmotic pretreatment (15% NaCl) for drying abalone slices, and it evaluates the influence of hot-air drying temperature (40–80°C) on the product quality. In addition, the mass transfer kinetics of salt and water was also studied. The optimal time of the osmotic treatment was established until reaching a pseudo equilibrium state of the water and salt content (290 min). The water effective diffusivity values during drying ranged from 3.76 to 4.75 × 10−9 m2/s for three selected temperatures (40, 60, and 80°C). In addition, experimental data were fitted by Weibull distribution model. The modified Weibull model provided good fitting of experimental data according to applied statistical tests. Regarding the evaluated quality parameters, the color of the surface showed a change more significant at high temperature (80°C), whereas the nonenzymatic browning and texture showed a decrease during drying process mainly due to changes in protein matrix and rehydration rates, respectively. In particular, working at 60°C resulted in dried samples with the highest quality parameters.

Withering syndrome susceptibility of northeastern Pacific abalones: A complex relationship with phylogeny and thermal experience.

Population declines in wild and cultured abalones (Haliotis spp.) due to a bacterial disease called withering syndrome (WS) have been documented along the northeastern Pacific Ocean. However, observed differences in species susceptibility to the disease are not well understood. Here, we examined the susceptibility of three temperate abalone species, the cool water (4-14 °C) pinto or northern abalone (Haliotis kamtschatkana), the intermediate water (8-18 °C) red abalone (H. rufescens), and the warm water (12-23 °C) pink abalone (H. corrugata), to experimental WS infection at temperatures facilitating disease proliferation. Mortality data paired with histological and molecular detection of the WS pathogen confirmed that these abalone species exhibit different levels of susceptibility to infection and resistance to WS development ranging from high susceptibility and low resistance in pinto abalone to moderate/low susceptibility and resistance in red and pink abalones. The temperature associated with WS induced mortalities also varied among species: pinto abalone died at the lowest experimental temperature (17.32 ± 0.09 °C), while red abalone died at an intermediate temperature (17.96 ± 0.16 °C), and pink abalone required the highest temperature (18.84 ± 0.16 °C). When data from the current and previous studies were examined, susceptibility to WS was inversely related to phylogenetic distance from white abalone (H. sorenseni), which had the highest susceptibility and lowest resistance of all abalone species tested prior to the current study. These results provide further evidence that an abalone's thermal optima and phylogenetic relationship can determine its susceptibility to WS; species with cool water evolutionary histories are most susceptible to WS and the most susceptible species appear to be closely related. Differences among the thermal ranges of abalone species have broad implications for WS disease dynamics and highlight the importance of understanding the mechanisms governing the abalone-WS relationship in order to properly manage declining abalone populations.

Effect of drying process assisted by high-pressure impregnation on protein quality and digestibility in red abalone (Haliotis rufescens).

Abalone (Haliotis spp.) is an exotic seafood product recognized as a protein source of high biological value. Traditional methods used to preserve foods such as drying technology can affect their nutritional quality (protein quality and digestibility). A 28-day rat feeding study was conducted to evaluate the effects of the drying process assisted by high-pressure impregnation (HPI) (350, 450, and 500MPa×5min) on chemical proximate and amino acid compositions and nutritional parameters, such as protein efficiency ratio (PER), true digestibility (TD), net protein ratio, and protein digestibility corrected amino acid score (PDCAAS) of dried abalone. The HPI-assisted drying process ensured excellent protein quality based on PER values, regardless of the pressure level. At 350 and 500MPa, the HPI-assisted drying process had no negative effect on TD and PDCAAS then, based on nutritional parameters analysed, we recommend HPI-assisted drying process at 350MPa×5min as the best process condition to dry abalone. Variations in nutritional parameters compared to casein protein were observed; nevertheless, the high protein quality and digestibility of HPI-assisted dried abalones were maintained to satisfy the metabolic demands of human beings.

First insight into the heritable variation of the resistance to infection with the bacteria causing the withering syndrome disease in Haliotis rufescens abalone.

Withering syndrome disease has experienced worldwide spread in the last decade. This fatal disease for abalone is produced by a rickettsia-like organism (WS-RLO), the bacterium "Candidatus Xenohaliotis californiensis". To evaluate the potential of the red abalone (Haliotis rufescens) to improve its resistance to infection by WS-RLO, the additive genetic component in the variation of this trait was estimated. For this, the variation in infection intensity with WS-RLOs and WS-RLOv (phage-infected RLOs) was analyzed in 56 families of full-sibs maintained for three years in a host-parasite cohabitation aquaculture system. A WS-RLO prevalence of 65% was observed in the analysed population; and from the total WS-RLO inclusions 60% were hyperparasited with the phage (WS-RLOv). The decrease in the food ingestion rate was the sole negative effect associated with increasing WS-RLO intensity of infection, suggesting that the high level of WS-RLOv load may have diminished the symptoms of WS disease in the analyzed abalones. The estimated heritabilities were moderate to mid, but significant, varying from 0.21 to 0.23 and 0.36 for WS-RLO and WS-RLOv infections, respectively. This suggests that variation in resistance to infection with WS-RLO may respond to selection in the evaluated red abalone population. Estimated response to selection (G) for the level of infection by WS-RLO indicated that if the 10% of red abalone with the lowest infection level is selected as broodstock, a 90% reduction in the intensity of infection in the progeny can be expected, even with the lowest estimation of heritability (h2=0.21). This strong response would be also due to the large phenotypic variance of this trait. Strong positive correlations, both phenotypic and genotypic, were observed between infection intensities with WS-RLO and WS-RLOv, indicating that selection to increase resistance to one of the types of RLOs will affect resistance in the other in the same direction. This is the first study that demonstrates the existence of additive genetic variation for resistance to WS-RLO in abalone. Consequently, it is possible to increase the resistance to WS-RLO in H. rufescens by selective breeding, which can be an economically attractive and environmentally friendly manner to reduce mortalities and growth effects caused by WS in abalone farms.