Immune response of the Almaco jack (Seriola rivoliana) against the infestation with Neobenedenia sp. in three cultivated temperatures

The Almaco jack (Seriola rivoliana) is a marine fish maintained in mariculture systems and frequently infested by monogenean parasites like Neobenedenia sp. Severe infestations can lead to high mortalities and economic losses for farmers. This study evaluated the effects of temperature on the immune response on Almaco jack infested with Neobenedenia sp. We exposed infested fishes at temperatures of 20 °C, 24 °C, and 30 °C for 20 days and took samples of different tissues at the beginning of the experiment, and after 3 and 20 days. The tissues considered were the skin, thymus, cephalic kidney, and spleen to evaluate the relative gene expression of different genes: Hsp70, IgM, IL-1β, IL-10, and MyD88. Our results showed an increase in IL-1β gene expression in the skin after 20 days of infestation but no significant effect of temperature on gene expression, despite increases in infestation rates with temperature. Therefore, relative genetic expression was controlled by the number of parasites and the days post-infestation. These results show that the parasite infestation induced a local response in the skin, but that temperature has an indirect effect on the immune system of Almaco jack.

Growth and paralytic shellfish poisoning toxin production by a Mexican dinoflagellate strain of Alexandrium tamiyavanichii Balech (1994) under different nutrient conditions

Alexandrium tamiyavanichii is a marine dinoflagellate known to produce Paralytic Shellfish Poisoning (PSP) toxin. Thus, a strain was isolated from La Paz Bay, Baja California Sur, Mexico and used to explore whether stress conditions, such as phosphorus limitation (PL) and nitrogen enrichment (NE) modulate population growth and PSP toxin production in the GSe medium. Growth kinetics showed that the PL treatment produced a 3.4-fold increase in cell density versus control at day 30 of the culture cycle. The highest PSP concentration was found in the control culture (309 fmol cell-1) on day 21. Saxitoxin (STX) was the main analog in all the treatments (> 40 % mol). In conclusion, PL and NE treatments promoted growth kinetics in the species studied but did not affect the PSP toxin production. For the first time, the present research describes A. tamiyavanichii high toxicity strain isolated from Mexican coasts relative to the South-Atlantic strains.

Bell Peppers (Capsicum annum L.) Losses and Wastes: Source for Food and Pharmaceutical Applications

Currently, the high added-value compounds contained in plant by-products and wastes offer a wide spectrum of opportunities for their reuse and valorization, contributing to the circular economy. The bell pepper (Capsicum annum L.) is an exotic vegetable with high nutritional value that, after processing, leaves wastes (peel, seeds, and leaves) that represent desirable raw material for obtaining phytochemical compounds. This review summarizes and discusses the relevant information on the phytochemical profile of bell peppers and their related biological properties as an alternative to revalorize losses and wastes from bell peppers for their application in the food and pharmaceutical industries. Bell pepper fruits, seeds, and leaves contain bioactive compounds (phenols, flavonoids, carotenoids, tocopherol, and pectic polysaccharides) that exhibit antioxidant, antibacterial, antifungal, immunosuppressive and immunostimulant properties, and antidiabetic, antitumoral and neuroprotective activities, and have a potential use as functional food additives. In this context, the revalorization of food waste is positioned as a technological and innovative research area with beneficial effects for the population, the economy, and the environment. Further studies are required to guarantee the safety use of these compounds and to understand their mechanisms of action.

Antibacterial effect of acetic acid during an outbreak of carbapenem-resistant Acinetobacter baumannii in an ICU (II)

INTRODUCTION

Acetic acid (AA) has been commonly used in medicine as an antiseptic agent for the past 6000 years. This study evaluated the antibacterial effect of AA during an outbreak in an intensive care unit (ICU) facility in Baja California Sur, México.

METHODOLOGY

Thirty-five environmental samples were collected, subsequently, disinfection with AA (4%) was performed, and two days later the same areas were sampled inside the ICU facility. Carbapenem-resistant A. baumannii (CRAB) was detected with loop-mediated isothermal amplification assay (Garciglia-Mercado et al. companion paper), targeting blaOXA-23-like, blaOXA-24-like, blaOXA-51-like, blaOXA-58-like, blaIMP and blaVIM genes. CRAB isolates before and after disinfection were compared by PFGE.

RESULTS

Eighteen (54.5%) and five (14.3%) of thirty-five environmental samples were identified as Acinetobacter baumannii before and after disinfection, respectively, showing a significant decrease of 85.7% (p < 0.05) both by Loop-mediated isothermal amplification (LAMP) and polymerase chain reaction (PCR). Furthermore, the presence of blaOXA-23-like and blaOXA-58-like genes significantly decreased (p < 0.05) both by LAMP and PCR methods. PFGE genotype showed high similarity among CRAB isolates before and after disinfection, suggesting wide clonal dissemination in the ICU facility.

CONCLUSIONS

This study demonstrated the novel application of AA with the LAMP assays developed for detecting CRAB. AA promises to be a cheap and efficacious disinfectant alternative to both developed and especially developing countries, preventing the spread of this organism in the environment and to other susceptible patients in health care settings.

In vitro Evaluation of Programmed Cell Death in the Immune System of Pacific Oyster Crassostrea gigas by the Effect of Marine Toxins

Programmed cell death (PCD) is an essential process for the immune system's development and homeostasis, enabling the remotion of infected or unnecessary cells. There are several PCD's types, depending on the molecular mechanisms, such as non-inflammatory or pro-inflammatory. Hemocytes are the main component of cellular immunity in bivalve mollusks. Numerous infectious microorganisms produce toxins that impair hemocytes functions, but there is little knowledge on the role of PCD in these cells. This study aims to evaluate in vitro whether marine toxins induce a particular type of PCD in hemocytes of the bivalve mollusk Crassostrea gigas during 4 h at 25°C. Hemocytes were incubated with two types of marine toxins: non-proteinaceous toxins from microalgae (saxitoxin, STX; gonyautoxins 2 and 3, GTX2/3; okadaic acid/dynophysistoxin-1, OA/DTX-1; brevetoxins 2 and 3, PbTx-2,-3; brevetoxin 2, PbTx-2), and proteinaceous extracts from bacteria (Vibrio parahaemolyticus, Vp; V. campbellii, Vc). Also, we used the apoptosis inducers, staurosporine (STP), and camptothecin (CPT). STP, CPT, STX, and GTX 2/3, provoked high hemocyte mortality characterized by apoptosis hallmarks such as phosphatidylserine translocation into the outer leaflet of the cell membrane, exacerbated chromatin condensation, DNA oligonucleosomal fragments, and variation in gene expression levels of apoptotic caspases 2, 3, 7, and 8. The mixture of PbTx-2,-3 also showed many apoptosis features; however, they did not show apoptotic DNA oligonucleosomal fragments. Likewise, PbTx-2, OA/DTX-1, and proteinaceous extracts from bacteria Vp, and Vc, induced a minor degree of cell death with high gene expression of the pro-inflammatory initiator caspase-1, which could indicate a process of pyroptosis-like PCD. Hemocytes could carry out both PCD types simultaneously. Therefore, marine toxins trigger PCD's signaling pathways in C. gigas hemocytes, depending on the toxin's nature, which appears to be highly conserved both structurally and functionally.

Predictive Model for the Effect of Environmental Conditions on the Postharvest Development of Colletotrichum gloeosporioides Strains Isolated from Papaya (Carica papaya L.)

ABSTRACT

Colletotrichum species are the most important postharvest spoilage fungi of papaya fruit. The objective of this research was to evaluate the effect of temperature and relative humidity on growth rate and time for growth to become visible of five strains of Colletotrichum gloeosporioides isolated from papaya fruit in a complex medium. As a primary model, the radial growth rates were estimated using the Baranyi and Roberts model in papaya agar. The Solver MS Excel function was used to obtain the time to visible mycelium (tv). Secondary models obtained with the Rosso et al. cardinal model of inflection were applied to describe the effect of temperature on the growth rate (μ). The Arrhenius-Davey model was used to model tv. The obtained models seem to be satisfactory for describing both μ and tv. The relative humidity had an effect on μ and tv for all tested C. gloeosporioides isolates, but no model accurately described the behavior of the fungus. External validation of models was performed with papaya fruit. Growth models were developed with the same models used in vitro. The bias and the accuracy factors as indices for performance evaluation of predictive models in food microbiology as a function of temperature and RH were 1.22 and 1.33, respectively, for μ and 1.18 and 1.62, respectively, for tv, indicating accurate predictions. The supply chain of papaya is complex and requires constant conditions, and poor conditions can result in damage to the fruit. Knowledge of the behavior of C. gloeosporioides on papaya fruit and application of the developed models in the supply chain will help to establish transport control strategies to combat these fungi. This research has contributed to development of the first models of growth for C. gloeosporioides in Mexico.

HIGHLIGHTS

Litopenaeus vannamei oxygen consumption and HSP gene expression at cyclic conditions of hyperthermia and hypoxia

Although Litopenaeus vannamei is a widely studied species, the information on how the organisms respond to natural daily variations of environmental conditions such as temperature and dissolved oxygen, and how such conditions alter the physiological responses, is scarce. In the present work, the strategies used by shrimps to cope with temperature and dissolved oxygen fluctuations during 24 days were investigated through the evaluation of oxygen consumption and heat shock proteins (HSP) gene expression. During daily fluctuations, no change in oxygen consumption in the short-term, but a significant increase in the long-term during hyperthermia conditions was registered, whereas a significant decrease during hypoxia was observed during all the bioassay. On the other hand, HSP70 and HSP90 gene expression increased in gills under thermal stress but was down-regulated under hypoxia, in both the short- and the long-term. This study highlights that to counteract environmental variations of temperature and dissolved oxygen, the shrimps use molecular compensatory mechanisms (HSP gene expression) that are different to those used under constant hypoxic conditions, suggesting that hypoxia can compromise physiological cytoprotection.

Development of a LAMP method for detection of carbapenem-resistant Acinetobacter baumannii during a hospital outbreak

INTRODUCTION

Carbapenem-resistant A. baumannii (CRAB) represents a public health threat increasing worldwide. We assess the suitability of a loop-mediated isothermal amplification (LAMP) method for on-site screening of CRAB in a hospital facility.

METHODOLOGY

A set of six primers were designed for recognizing eight distinct sequences on six targets: blaOXA-23-like, blaOXA-24-like, blaOXA-51-like, blaOXA-58-like, blaIMP, and blaVIM. A LAMP method was developed, optimized and evaluated for the identification of CRAB in thirty-three environmental samples from an outbreak in an Intensive Care Unit (ICU) facility.

RESULTS

The sensitivity of the LAMP assay for the detection of A. baumannii was ten-fold higher than the PCR assay (1.0 ng.µL-1). The LAMP assays showed a higher detection rate for CRAB samples and robust diagnosis performance in comparison to a conventional PCR, with clinical sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 100% for blaOXA-23-like, blaOXA-51-like and blaVIM.

CONCLUSIONS

The developed LAMP assays are powerful tools that can be useful in on-site screening of CRAB causing local outbreaks in clinics and hospitals facilities where costs and equipment restraints are imperative.

Effect of a Synbiotic Mix on Intestinal Structural Changes, and Salmonella Typhimurium and Clostridium Perfringens Colonization in Broiler Chickens

Synbiotics can prevent gastrointestinal infections in broilers. This work studies the effect of a Synbiotic on broilers. One-day-old male broilers were divided into groups: Control; Synbiotic; Synbiotic + S. Typhimurium; Synbiotic + C. perfringens; Synbiotic + S. Typhimurium + C. perfringens; S. Typhimurium; C. perfringens; and S. Typhimurium + C. perfringens. Histopathological analysis revealed that the Synbiotic promoted longer villi, less deep crypts, and better villi-crypt ratio. Broilers treated with the Synbiotic, infected with pathogens or not, had healthier mucosa. In groups infected with pathogens, the frequency and intensity of histopathologic lesions were lessened often in groups treated with the Synbiotic. The Synbiotic group had higher lactic acid bacteria counts than the Control group on day 39, and the isolation frequency of S. Typhimurium was lower (p < 0.05) in the Synbiotic-treated groups. On day 18, mucosa, villi, villi-crypt ratio, crypt, and feed intake were influenced by Enterobacteriaceae. However, on day 39 (end of the trial), those parameters were influenced by lactic acid bacteria. The Synbiotic influenced morphological modifications in the duodenal mucosa, which in turn gave the broilers the ability to resist infections caused by S. Typhimurium and C. perfringens, by inhibiting their growth and decreasing the intensity and frequency of histopathological injuries.

Debaryomyces hansenii CBS 8339 β-glucan enhances immune responses and down-stream gene signaling pathways in goat peripheral blood leukocytes

Debaryomyces hansenii-derived β-glucan has shown immunostimulant effect on aquaculture species and recently on goat peripheral blood leukocytes. Moreover, the marine yeast D. hansenii CBS 8339 has demonstrated to enhance fish immune response. Nonetheless, the associated immune signaling pathways induced by β-glucan from this marine yeast have not been characterized yet. This study described the effects of β-glucan from D. hansenii CBS 8339 against challenge with Escherichia coli and activation of possible mechanisms on goat peripheral blood leukocytes. The proton nuclear magnetic resonance spectra showed that D. hansenii had β-(1,3)(1,6)-glucan. The phagocytic ability enhanced after E. coli challenge, and nitric oxide production increased before and after challenge in leukocytes stimulated with D. hansenii β-glucan. In addition, an early gene expression stimulation was found related to β-glucan recognition by TLR2 and Dectin-1 receptors, intracellular regulation by Syk, TRAF6, MyD88 and transcription factor NFκB, and effector functions of pro-inflammatory cytokine, such as IL-1β and TNF-α. Interestingly, simulation with D. hansenii-derived β-glucan increased leukocyte viability after E. coli challenge. In conclusion, β-glucan from D. hansenii CBS 8339 reduced cytotoxic effects of E. coli and modulated signaling pathways and innate immune response in goat peripheral blood leukocytes.

Characterization of nuclear factor of activated T-cells-c3 (NFATc3) and gene expression of upstream-downstream signaling molecules in response to immunostimulants in Pacific red snapper cells

The nuclear factor of activated T cells (NFAT) proteins have crucial roles in the development and function of the immune system since they not only regulate activation of T cells but are also involved in the control of thymocyte development and T-cell differentiation. In this study, NFATc3 was characterized from the Pacific red snapper, Lutjanus peru. LpNFAtc3, which contains an open reading of 3300 bp frame coding for a protein of 1100 aa with a predicted molecular weight of 118.52 kDa. The predicted protein showed a conserved NFAT family structure with signature motifs and domains, sharing high identity (up to 76%) compared to other fish sequences. NFATc3 gene expression was analyzed by real time-PCR in head-kidney cells (leukocytes and lymphocytes) following yeast, zymosan and Vibrio parahaemolyticus stimulation along with the expression of upstream (ILF2, ILF3 and CaN) and downstream (CD3, TCRβ, IL-6 and IL-12) molecules. This study revealed a broad expression of NFATc3 with a relative strong expression in intestine and lymphocytes. The expression of NFATc3 was differentially up-regulated after stimulation with yeast in head-kidney leukocytes and after bacterial infection in lymphocytes at 24 h. Interestingly, the yeast and zymosan were able to activate ILF2, ILF3 and CaN mRNA gene expression in both kinds of cells. On the other hand, NFAT downstream genes such as CD3, TCRβ, IL-6 and IL-12 were significantly up-regulated in leukocytes stimulated with yeast or zymosan at 12 h; however in lymphocytes, this up-regulation was detected when cells reacted to V. parahaemolyticus stimuli at 24 h. Stimulating Pacific red snapper leukocytes with immunostimulants as yeast significantly up-regulated the expression of NFATc3, and up- and down-stream molecular genes and NFATc3 lymphocytes expression were potentially involved in responses to invasion of bacterial pathogens in an early immune response.

Molecular characterization and expression analyses of toll like receptor-5 induced by Vibrio parahaemolyticus antigens in Pacific red snapper

Toll-like receptor 5 (TLR5) is a member of TLRs family responsible for the bacterial flagellin recognition in vertebrates. Herein, the TLR5M gene structure of Pacific red snapper (Lutjanus peru) was characterized. The full-length cDNA of LpTLR5M comprises an open reading frame (ORF) of 2715 bp, encoding a polypeptide of 904 amino acids including 9 LRRs (residues 119-562) and one LRR-CT domain (residues 593-646) at the extracellular region, and a TIR domain (residues 710-904) in the cytoplasmic region. The amino acid sequence in L. peru TLR5 showed high identity (66-69%) with TLR5 from Paralichthys olivaceus and Scophthalmus maximus. Quantitative real-time PCR (qPCR) analysis demonstrated the constitutive expression of LpTLR5M mRNA in all the examined tissues, with higher levels in intestine, liver, and head-kidney. Furthermore, expression of LpTLR5M and five cytokine genes was also investigated 24 h and one week post-stimulation in fish intraperitoneally injected with ToxA, live V. parahaemolyticus (Vp) or V. parahaemolyticus Lysate antigens. TLR5M was significantly induced in fish infected with Vp. The pro-inflammatory cytokines IL-6, IL8 and IL-12 were significantly up-regulated in head-kidney in fish stimulated with Vp, while in intestine upregulation was observed following ToxA or Lysate injection. In contrast, IL-17 mRNA was significantly up-regulated in the intestine from fish infected with live Vp at 24 h post-injection. The results indicate that Lysate and Vp antigens can induce an immune response via TLR5M and that cytokines have an important role in the defense mechanisms against V. parahaemolyticus.

Growth Modeling of Aspergillus niger Strains Isolated from Citrus Fruit as a Function of Temperature on a Synthetic Medium from Lime (Citrus latifolia T.) Pericarp

Molds are responsible for postharvest spoilage of citrus fruits. The objective of this study was to evaluate the effect of temperature on growth rate and the time to visible growth of Aspergillus niger strains isolated from citrus fruits. The growth of these strains was studied on agar lime medium (AL) at different temperatures, and growth rate was estimated using the Baranyi and Roberts model (Int. J. Food Microbiol. 23:277-294, 1994). The Rosso et al. cardinal model with inflexion (L. Rosso, J. R. Lobry, S. Bajard, and J. P. Flandrois, J. Theor. Biol. 162:447-463, 1993) was used as a secondary model to describe the effect of temperature on growth rate and the lag phase. We hypothesized that the same model could be used to calculate the time for the mycelium to become visible (t_v) by substituting the lag phase (1/λ and 1/λ_opt) with the time to visible colony (1/t_v-opt and 1/t_v), respectively, in the Rosso et al.

MODEL

High variability was observed at suboptimal conditions. Extremes of temperature of growth for A. niger seem to have a normal variability. For the growth rate and time t_v, the model was satisfactorily compared with results of previous studies. An external validation was performed in lime fruits; the bias and accuracy factors were 1.3 and 1.5, respectively, for growth rate and 0.24 and 3.72, respectively, for the appearance time. The discrepancy may be due to the influence of external factors. A. niger grows significantly more slowly on lime fruit than in culture medium, probably because the nutrients are more easily available in medium than in fruits, where the peel consistency may be a physical barrier. These findings will help researchers understand the postharvest behavior of mold on lime fruits, host-pathogen interactions, and environmental conditions infecting fruit and also help them develop guidelines for future work in the field of predictive mycology to improve models for control of postharvest fungi.

Evaluation of ToxA and Vibrio parahaemolyticus lysate on humoral immune response and immune-related genes in Pacific red snapper

Immunogenicity of ToxA and Vibrio parahaemolyticus lysate was evaluated in a double immunostimulation scheme in Pacific red snapper after V. parahaemolyticus infection. Three groups of Pacific red snapper were intraperitonealy (i.p.) injected with phosphate-buffered saline (PBS group), ToxA of V. parahaemolyticus (ToxA-Vp group) or V. parahaemolyticus lysate (lysate-Vp group) (first injection, day 1; second injection, day 7). Fish were subsequently infected with live V. parahaemolyticus. Humoral immune parameters in skin mucus and serum were evaluated on days 1, 7, 8 and 14 days post-immunostimulation and 7 days post-infection. Moreover expression of immune-related genes was quantified by real time PCR in head-kidney leukocytes, spleen, liver, and intestine. The ToxA-Vp-treated group showed a higher anti-protease and catalase activity in skin mucus when compared with the PBS group. Measurements of SOD and CAT activities showed an increment in both activities a day after the second boost with ToxA-Vp or lysate-Vp. Interestingly, IgM levels in mucus and transcripts were enhanced followed the ToxA-Vp treatment even after challenge. Furthermore, IL-1β was strongly expressed in all analyzed cell or tissues followed ToxA-Vp or Vp-lysate treatments. Finally, SOD and CAT gene expression was up-regulated in fish immunostimulated with either treatment ToxA-Vp or lysate-Vp, mainly after infection in head-kidney leukocytes and intestine. This is the first study where the effects of ToxA from V. parahaemolyticus in the immune system of Pacific red snapper was evaluated. These results suggest that ToxA-Vp would positively affect humoral immune response and up-regulate expression of genes involved in the immune system function; and could help in the control of V. parahaemolyticus infection in Pacific red snapper Lutjanus peru, an economic important fish in Mexico.

Injected phage-displayed-VP28 vaccine reduces shrimp Litopenaeus vannamei mortality by white spot syndrome virus infection

White spot syndrome virus (WSSV) is the most important viral pathogen for the global shrimp industry causing mass mortalities with huge economic losses. Recombinant phages are capable of expressing foreign peptides on viral coat surface and act as antigenic peptide carriers bearing a phage-displayed vaccine. In this study, the full-length VP28 protein of WSSV, widely known as potential vaccine against infection in shrimp, was successfully cloned and expressed on M13 filamentous phage. The functionality and efficacy of this vaccine immunogen was demonstrated through immunoassay and in vivo challenge studies. In ELISA assay phage-displayed VP28 was bind to Litopenaeus vannamei immobilized hemocyte in contrast to wild-type M13 phage. Shrimps were injected with 2 × 10(10) cfu animal(-1) single dose of VP28-M13 and M13 once and 48 h later intramuscularly challenged with WSSV to test the efficacy of the vaccine against the infection. All dead challenged shrimps were PCR WSSV-positive. The accumulative mortality of the vaccinated and challenged shrimp groups was significantly lower (36.67%) than the unvaccinated group (66.67%). Individual phenoloxidase and superoxide dismutase activity was assayed on 8 and 48 h post-vaccination. No significant difference was found in those immunological parameters among groups at any sampled time evaluated. For the first time, phage display technology was used to express a recombinant vaccine for shrimp. The highest percentage of relative survival in vaccinated shrimp (RPS = 44.99%) suggest that the recombinant phage can be used successfully to display and deliver VP28 for farmed marine crustaceans.

Humoral immune response and TLR9 gene expression in Pacific red snapper (Lutjanus peru) experimentally exposed to Aeromonas veronii

Aquaculture production of Pacific red snapper Lutjanus peru is growing rapidly in Mexico, especially in Gulf of California. As it is a relatively new aquaculture species there are few reports evaluating its immune response to pathogens. The Gram-negative bacteria Aeromonas veronii is a heterogeneous organism that causes the disease known as motile aeromonad septicemia, which is responsible for serious economic loss in seabream culture due to bacterial infections. For the purpose of this study, juvenile Pacific red snapper specimens were intraperitoneally injected with low doses of A. veronii (1 × 10(6) CFU ml(-1)). Changes in humoral immune parameters (total protein, myeloperoxidase, lisozyme and antiprotease activities and IgM levels), as well as superoxide dismutase and catalase activities, and TLR9 gene expression were evaluated 24 and 48 h after injection. Overall, the results showed an enhanced in humoral immune parameters and SOD and CAT activities in fish infected with A. veronii compared with control group at 24 or 48 h. By real time PCR assays, the basal mRNA transcripts of TLR9 showed that were highly expressed in intestine and leucocytes compared to skin, head kidney, liver and gill. Then, the mRNA expression levels of TLR9 in head kidney, skin, liver and intestine were analyzed in non-infected and experimentally infected fish 24 and 48 h after injection. A. veronii up-regulated the expression of TLR9 at 24 or 48 h of exposure in all samples analyzed except in liver. Interestingly, intestine produced the greatest increase in transcript levels upon exposure (48 h) to A. veronii. Taken together, our results suggest that low doses of A. veronii infection inducing humoral immune system and TLR9 immune gene in Pacific red snapper that can be useful in the health control of this species.

Single or combined effects of Lactobacillus sakei and inulin on growth, non-specific immunity and IgM expression in leopard grouper (Mycteroperca rosacea)

The aim of this study was to evaluate the single or combined effects of Lactobacillus sakei with inulin suitable for immunological in vivo studies in farmed fish. By in vitro assays, L. sakei strain 5-4 showed antibacterial activities against all assayed fish pathogens (except the Vibrio harveyi strain CAIM-1793). L. sakei was able to survive at high fish bile concentrations. Fermentation of the agave inulin resulted in a large increase in number of lactobacilli. For the in vivo study, fish were fed for 8 weeks four practical diets: control diet (control), L. sakei 5-4 (10(7) CFU/g), inulin (1% or 10 g/kg) and L. sakei + inulin (10(7) CFU/g + 10 g/kg). The weight gain showed clearly the synergistic effect of L. sakei 5-4 and inulin at 6 and 8 weeks of treatments. Leopard grouper fed with L. sakei alone or combined with inulin have significantly increased the assayed physiological and humoral immune parameters. By real-time PCR assays, the mRNA transcripts of immunoglobulin M (IgM) were found to be higher expressed in intestine, head kidney, mucus, gill, spleen and skin. Moreover, mRNA expression levels of IgM in head kidney and anterior intestine were measured by real-time PCR. L. sakei 5-4 and L. sakei + inulin supplemented diet up-regulated the expression of IgM at week 4 and 8 in intestine and head kidney, respectively. These results support the idea that the L. sakei 5-4 alone or combined with agave inulin improved growth performance and stimulates the immune system of leopard grouper.

Apoptosis of hemocytes from lions-paw scallop Nodipecten subnodosus induced with paralyzing shellfish poison from Gymnodinium catenatum

The toxic dinoflagellate Gymnodinium catenatum produces paralyzing shellfish poisons (PSPs) that are consumed and accumulated by bivalves. Previously, we recorded a decrease in hemocytes 24h after injection of PSPs (gonyautoxin 2/3 epimers, GTX2/3) in the adductor muscle in the lions-paw scallop Nodipecten subnodosus. In this work, qualitative and quantitative analyses, in in vivo and in vitro experiments, revealed that the lower count of hemocytes results from cells undergoing typical apoptosis when exposed to GTX 2/3 epimers. This includes visible morphological alterations of the cytoplasmic membrane, damage to the nuclear membrane, condensation of chromatin, DNA fragmentation, and release of DNA fragments into the cytoplasm. Induction of apoptosis was accompanied by phosphatidylserine exposure to the outer cell membrane and activation of cysteine-aspartic proteases, caspase 3 and caspase 8. Addition of an inhibitor of caspase to the medium suppressed activation in hemocytes exposed to the toxins, suggesting that cell death was induced by a caspase-dependent apoptotic pathway. The results are important for future investigation of the scallop's immune system and should provide new insights into apoptotic processes in immune cells of scallops exposed to PSPs.

In vitro and in vivo effects of neem tree (Azadirachta indica A. Juss) products on larvae of the sheep nose bot fly (Oestrus ovis L. Díptera: Oestridae)

Two studies were carried out in order to test the effects of neem tree extracts (Azadirachta indica A. Juss) on sheep bot fly larvae (Oestrus ovis L. Diptera: Oestridae). First, aqueous extracts from neem seeds (ASNE) at 0, 5 y 10% (w/v) concentrations were tested on larval mortality in vitro. In a second study, the effect of oral administration with neem seed meal (0, 100 y 200mg/kg) and neem leaves (1% of diet) on number of larvae found at necropsy and larval development was evaluated in experimentally O. ovis-infected sheep. Results in Experiment 1 showed a significant (P<0.05) effect of ASNE on time to L1 mortality in a dosis-dependent manner. In Experiment 2, oral administration of seeds or leaves did not affect the number of larvae found at necropsy of the sheep, but interfered with larval development and there was a tendency to reduce larval weight at the end of the infection period (55d).

Germination and ROS detoxification in bell pepper (Capsicum annuum L.) under NaCl stress and treatment with microalgae extracts

We evaluated the salt tolerance of hybrids of pepper (Capsicum annuum L.) during germination. Treatments were applied at 0, 25, and 50 mM NaCl with preparations of supplemental extracts of the microalgae Dunaliella salina and Phaeodactylum tricornutum to determine the percentage germination rate as well as measured indicators of oxidative stress caused by the salt treatments during seed germination. We found that root growth was favorably influenced by the microalgae leading to increased germination rate. Tissues were analyzed in terms of superoxide radical production, lipid peroxidation, and activity of antioxidant enzymes viz. superoxide dismutase, catalase, and glutathione peroxidase. Our results suggest that application of microalgae extracts significantly reduced (p < 0.05) superoxide radical production, as well as lower lipid peroxidation in comparison to plants without extracts of microalgae. The antioxidant enzymes increased in the presence of microalgae showing a significant difference (p < 0.05). The results suggest differences in oxidative metabolism in response to the magnitude of salt stress and concentrations of microalgae help mitigate salt stress in plants during the germination process.

Accumulation, biotransformation, histopathology and paralysis in the Pacific calico scallop Argopecten ventricosus by the paralyzing toxins of the dinoflagellate Gymnodinium catenatum

The dinoflagellate Gymnodinium catenatum produces paralyzing shellfish poisons that are consumed and accumulated by bivalves. We performed short-term feeding experiments to examine ingestion, accumulation, biotransformation, histopathology, and paralysis in the juvenile Pacific calico scallop Argopecten ventricosus that consume this dinoflagellate. Depletion of algal cells was measured in closed systems. Histopathological preparations were microscopically analyzed. Paralysis was observed and the time of recovery recorded. Accumulation and possible biotransformation of toxins were measured by HPLC analysis. Feeding activity in treated scallops showed that scallops produced pseudofeces, ingestion rates decreased at 8 h; approximately 60% of the scallops were paralyzed and melanin production and hemocyte aggregation were observed in several tissues at 15 h. HPLC analysis showed that the only toxins present in the dinoflagellates and scallops were the N-sulfo-carbamoyl toxins (C1, C2); after hydrolysis, the carbamate toxins (epimers GTX2/3) were present. C1 and C2 toxins were most common in the mantle, followed by the digestive gland and stomach-complex, adductor muscle, kidney and rectum group, and finally, gills. Toxin profiles in scallop tissue were similar to the dinoflagellate; biotransformations were not present in the scallops in this short-term feeding experiment.

Efecto de Debaryomyces hansenii en la respuesta antioxidante de juveniles de camarón blanco Litopenaeus vannamei

RESUMENObjetivo. Determinar la respuesta antioxidante [actividad de superóxido dismutasa (SOD) y catalasa (CAT)] así como la cuenta total de hemocitos (CTH) y el contenido de proteínas (CP) en camarones (Litopenaeus vannamei) expuestos a diferentes dosis y cepas de la levadura Debaryomyces hansenii (DH5, DH6, LL1), y un inmunoestimulante comercial (LAM). Materiales y métodos. Las levaduras fueron cultivadas y suministradas diariamente en concentraciones diferentes (104 – 106 UFC/mL) directamente a los tanques de cultivo de los camarones (8 ± 0.2 g) mientras que LAM fue aplicado una vez a la semana (0.5 mg/L). Los organismos fueron mantenidos bajo condiciones de laboratorio (28°C, 35%, 80% de recambio diario de agua, dieta comercial para camarón ad libitum). Los tratamientos fueron distribuidos por duplicado y los resultados evaluados a los 15 días con un análisis de varianza y una prueba de Tukey. Resultados. Se registró un CTH significativo (p<0.05) en los tratamientos con DH6 y LL1 (106 UFC/mL) comparada con el control, mientras que las cepas DH5 y DH6 revelaron un incremento significativo (p<0.05) de CP con la dosis de 104 UFC/mL. Los camarones tratados con LAM incrementaron significativamente (p<0.05) los valores de SOD y CAT. Conclusiones. Los resultados obtenidos demuestran que D. hansenii incrementa la respuesta antioxidante y CTH en camarones.

Genomic organization and tissue-specific expression of hepcidin in the pacific mutton hamlet, Alphestes immaculatus (Breder, 1936)

Hepcidin is a cysteine-rich peptide involved in iron metabolism, inflammatory response and as antimicrobial peptide. Despite the fact that hepcidins have been identified in several fish species, only few have been completely characterized. This study, described the identification and complete molecular characterization of the hepcidin antimicrobial peptide 1 (HAMP1) gene of Alphestes immaculatus. Moreover, its specific expression level at both basal and lipopolysaccharide (LPS)-induced conditions in different tissues was also determined by real-time PCR. Results showed that the HAMP1gene consists of three exons and two introns encoding a preprohepcidin composed of 90 aa (24 aa for signal peptide, 40 aa for prodomain and 26 aa for mature peptide). The promoter region analysis revealed a TATA box sequence and several putative transcription factor binding sites. A comparative analysis showed CEBPα, CEBPβ, NF-kB, HNF3, GATA-1 and c-Rel as the most common found in fishes. The mature peptide possesses a pI of 8.34, which is the average among fish hepcidin. In addition, the structural modeling showed a hairpin structure with four putative disulfide bonds. A phylogenetic analysis revealed that this hepcidin gene is a HAMP1 class, and is clustered into the same group with the Serranid fish Epinephelus moara and the Antarctic fish Lycodichthys dearborni. Finally, the relative expression levels showed high basal values in liver and muscle, whereas in LPS-induced fish the relative expression tendency changed, with the highest values in spleen and head kidney tissues. This study describes the completely characterized HAMP1 gene of A. immaculatus and their patterns of expression level at different conditions and in different tissues, showing by first time muscle hepcidin expression could be relevant in the immune response in fish.

Sheep and goat immune responses to nose bot infestation: a review

Oestrus ovis L. (Diptera: Oestridae) is a cosmopolitan agent of myiasis in sheep and goats. The parasitic phase begins after adult females deposit first-stage larvae (L1) into the nostrils of hosts; these larvae develop into L2 and L3 in the nasal and sinus horn cavities. Sneezing and nasal discharges are the major clinical signs in infected animals. The pathogenesis of O. ovis infection is caused by: (a) the trauma resulting from the mechanical action of spines and hooks during larval movement on mucosal membranes, and, more importantly, (b) an allergenic reaction provoked by molecules excreted/secreted by larvae, of which salivary antigens are those mainly recognized by the host's immune system. The recruitment of immune reactive cells increases gradually from the nasal to sinus cavities in infected hosts. Mast cells, eosinophils, macrophages and lymphocytes are always more numerous in infected than non-infected animals. Humoral (antibody) systemic response of immunoglobulin G (IgG) usually reaches seroconversion 2-4 weeks post-first infection and the highest levels are observed during the development of L2 and L3 larvae. Local antibody responses include specific IgG, which has been found to negatively correlate with larval survival and development. Hypersensitivity reaction, immunomodulation, immunization trials and mixed infections of O. ovis and helminths are discussed.

[Effect of probiotic bacteria on survival and growth of Cortez oyster larvae, Crassostrea corteziensis (Bivalvia: Ostreidae)]

Disease control problems have major constraints in aquaculture production, and the use of probiotics in larviculture is a valid alternative to antibiotics. This study analyzed the effect of probiotic bacteria on survival and final size of Cortez oyster larvae Crassostrea corteziensis. Two different probiotic concentrations were evaluated, 1 x 10(4) and 1 x 10(5) CFU/ml of Lactic acid bacteria (strain NS61) isolated from Nodipecten subnodosus, and bacilli isolated from the white leg shrimp, Litopenaeus vannamei (Pseudomonas aeruginosa, strain YC58) and C. corteziensis (Burkholderia cepacia, strain Y021). Bacteria were added directly into culture tanks, starting the bioassays from veliger to pediveliger stages as follows: (1) Control, without probiotics; (2) lactic acid bacteria (Lb); (3) bacilli mix (Mb) in a proportion 1:1. Results showed a higher larval survival with Lb and Mb at a dose of 1 x 10(4) CFU/ml compared to the control group. Larvae exposed to Mb at 1 x 10(5) CFU/ml showed higher survival than Lb and control. Larval final size was not significantly increased with the tested probiotics, but larvae treated with Lb at 1 x 10(5) CFU/ml showed less survival rate than those treated at 1 x 10(4) CFU/ml. This study showed the beneficial effect of these probiotics, added individually or mixed in C. corteziensis larvae culture.

Lactobacillus fermentum BCS87 expresses mucus- and mucin-binding proteins on the cell surface

AIMS

To identify and characterize adhesion-associated proteins in the potential probiotic Lactobacillus fermentum BCS87.

METHODS AND RESULTS

Protein suspensions obtained from the treatment of Lact. fermentum BCS87 with 1 mol 1(-1) LiCl were analysed by Western blotting using HRP-labelled porcine mucus and mucin. Two adhesion-associated proteins with relative molecular weight of 29 and 32 kDa were identified. The N-terminal and internal peptides of the 32 kDa protein (32-Mmubp) were sequenced, and the corresponding gene (32-mmub) was found by inverse polymerase chain reaction. The complete nucleotide sequence of 32-mmub revealed an open reading frame of 903 bp encoding a primary protein of 300 amino acids and a mature protein of 272 residues. A basic local alignment search showed 47-99% identity to solute-binding components of ATP binding cassette transporter proteins in Lactobacillus, Streptococcus and Clostridium. An OpuAC-conserved domain was identified and phylogenetic relationship analysis confirmed that 32-Mmubp belongs to the OpuAC family.

CONCLUSIONS

Adhesion of Lact. fermentum BCS87 appeared to be mediated by two surface-associated proteins. 32-Mmubp is a component of ABC transporter system that also functions as an adhesin.

SIGNIFICANCE AND IMPACT OF THE STUDY

Characterization of 32-Mmubp and 32-mmub will contribute to understanding the host-bacteria interactions of Lact. fermentum with the intestinal tract of pigs.

The role of heparan sulfate on adhesion of 47 and 51 kDa outer membrane proteins ofHelicobacter pylorito gastric cancer cellsThis study was done in memory of the late Dr. Roberto Carlos Vazquez-Juarez

Helicobacter pylori is a common gastrointestinal pathogenic bacterium in humans and the usual preference for the stomach’s outer membrane proteins (OMPs) are antigens involved in the adhesion process. Through SDS–PAGE and blotting analyses, using horseradish peroxidase-labeled heparan sulfate (HRP-HS) as a probe, we identified H. pylori OMPs with affinity for heparan sulfate (OMP-HS). Biotin–streptavidin bacterial-adhesion assay was used to evaluate participation of OMP-HS in the adhesion of H. pylori to semi-confluent HeLa S3 and Kato III cell monolayers. The results provide evidence that induction of antibodies against 2 OMP-HSs (HSBP-47 and HSBP-51) could reduce binding of H. pylori to both cell lines and induce detachment of cell-bound bacteria from infected cultured cells.

Superoxide dismutase activity in juvenile Litopenaeus vannamei and Nodipecten subnodosus exposed to the toxic dinoflagellate Prorocentrum lima

The toxic effect of the dinoflagellate Prorocentrum lima on juvenile American whiteleg shrimp Litopenaeus vannamei and giant lion-paw scallop Nodipecten subnodosus was evaluated. Organisms were exposed to three densities (500, 2000, or 5000 cells mL(-1)), superoxide dismutase activity and soluble protein in the hepatopancreas and muscle were determined at 1, 6, 24 and 48 h after challenge. Shrimp exposed at 5000 cells mL(-1) significantly increased SOD activity in the hepatopancreas at 1 h post-challenge, whereas enzymatic activity in muscle significantly increased at 24 h at all densities. Scallops exposed to 500 and 2000 cells mL(-1) showed significant SOD activity increase in hepatopancreas at 24 and 12 h, respectively. Mortality at 48 h was 100% in scallops exposed to 5000 cells mL(-1). Shrimp showed higher levels of SOD activity than scallops. Soluble protein content in the shrimp hepatopancreas was significantly higher at densities of 500 and 2000 cells mL(-1) at 6 and 1 h, respectively. Soluble protein content in the scallop hepatopancreas was higher than control values at 1 h after challenge. In this study, 500 cells mL(-1) was enough to trigger SOD activity in two benthic species exposed to the toxic dinoflagellate P. lima.

IgG antibody response against salivary gland antigens from Oestrus ovis L. larvae (Diptera: Oestridae) in experimentally and naturally infected goats

The aims of this study were to analyze the systemic IgG responses against third-instar salivary gland (L3SG) antigens by ELISA in Oestrus ovis experimentally infected kids (EIK) and in naturally exposed adult goats (NEG). Firstly, kids (n=4 per group) were assigned to receive intranasally 0, 12, 24, 36, and 48 first-instars in experimental infections. Blood samples were taken from EIK at Days 0, 14, 42 and 67 post-infection. At necropsy (Day 67), larval number and developmental instars were recorded. In an epidemiological study, blood serum samples were collected from 448 grazing NEG (n=20 flocks) in Baja California Sur, Mexico. Results showed that larval establishment rate was similar in EIK groups. Systemic IgG response reached the threshold after Day 42, but humoral response was not statistically different among EIK groups receiving experimental infections. In NEG, all surveyed flocks (100%) showed specific systemic IgG antibodies to L3SG antigens and the overall goat oestrosis prevalence was 59.2%. In conclusion, larval L3SG antigens were effective in detection of specific systemic IgG antibodies against O. ovis infected kids and goats by ELISA.

Effects of the toxic dinoflagellate, Gymnodinium catenatum on hydrolytic and antioxidant enzymes, in tissues of the giant lions-paw scallop Nodipecten subnodosus

This study documents effects of the toxic dinoflagellate Gymnodinium catenatum, a producer of paralytic shellfish poison, on juvenile farmed (5.9+/-0.39 cm) giant lions-paw scallop Nodipecten subnodosus. Scallops were fed bloom concentrations of toxic dinoflagellate G. catenatum for 7 h. The effect of the toxic dinoflagellate in different tissues was determined by analysis of antioxidant enzymes (catalase, superoxide dismutase, gluthathione peroxidase), thiobarbituric acid reactive substances (lipid peroxidation), and hydrolytic enzymes (proteases, glycosidases, phosphatases, lipases, and esterases). Histopathological photos record the effects of the toxic dinoflagellate in various tissues. The results show that juvenile lions-paw scallops produce pseudo-feces, partially close their shell, increase melanization, and aggregate hemocytes. Several enzymes were affected and could serve as biological markers. In general, the adductor muscle was not affected. In the digestive gland, some enzymes could be the result of defensive and digestive processes. Gills and mantle tissue were markedly affected because these sites respond first to toxic dinoflagellates, leading to the idea that proteolytic cascades could be involved.

Proteolytic activity in salivary gland products of sheep bot fly (Oestrus ovis) larvae

This study identified and characterized hydrolytic enzymes in salivary gland products of Oestrus ovis larvae. Third instars were collected from the heads of slaughtered goats. Salivary glands were extracted, their products obtained by centrifugation and the enzymatic profile determined. Optimum pH, temperature of maximum proteolytic activity, thermal stability, and resistance of salivary gland products were determined on collagen and subclasses of proteases were identified using protease inhibitors. Zymograms were used to determine the molecular weight of proteases. Antigenic protein bands were revealed by immunoblotting using sera obtained from experimentally infested goats. Seven positive enzymatic activities were detected in salivary gland products: acid phosphatase, naphthol-AS-BI-phosphohydrolase, esterase (C4), esterase lipase (C8), leucine arylamidase, alpha-glucosidase and N-acetyl-beta-glucosaminidase. Optimum pH for proteolytic activity was 8.0; proteolytic activity increased with temperature (10-50 degrees C) then drastically decreased at 60 degrees C. Proteases in O. ovis salivary gland products belong to the serine subclass. In Zymograms, bands of proteolytic activity were detected in the 20-63 kDa range; the immunoblot showed three antigenic bands, one of them related to a protease band (63 kDa). Serine proteases in O. ovis salivary gland products are most likely involved in larval nutrition and host immuno-modulation.

Sexual comparisons in immune ability, survival and parasite intensity in two damselfly species

Recent evolutionary studies have suggested that females have a more robust immune system than males. Using two damselfly species (Hetaerina americana and Argia tezpi), we tested if females produced higher immune responses (as phenoloxidase and hydrolytic enzymes), had a higher survival (using a nylon implant inserted in the abdomen and measuring survival after 24h) and fewer parasites (gregarines and water mites) than males. We also tested whether immune differences should emerge in different body areas (thorax vs. abdomen) within each sex with the prediction that only females will differ with the abdomen having a higher immune response than their thorax since the former area, for ecological and physiological reasons, may be a target zone for increased immune investment. Animals were adults of approximately the same age. In both species, females were more immunocompetent than males, but only in H. americana females were immune responses greater in the abdomen than in the thorax. However, there were no differences in survival and parasite intensity or the probability of being parasitised between the sexes in either of the two species. Thus, this study lends partial support to the principle that females are better at defending than males despite the null difference in parasitism and survival.

Seasonal seawater temperature as the major determinant for populations of culturable bacteria in the sediments of an intact mangrove in an arid region

Mangroves are highly productive marine ecosystems where bacteria (culturable and non-culturable) actively participate in biomineralization of organic matter and biotransformation of minerals. This study explores spatial and seasonal fluctuations of culturable heterotrophic bacteria and Vibrio spp. in the sediments of an intact mangrove ecosystem and determines the dominant environmental factors that govern these fluctuations. Sediment samples were collected monthly from three stations in the mangroves of Laguna de Balandra, Baja California Sur, Mexico, through an annual cycle. Physicochemical parameters included seawater temperature, salinity, and concentration of dissolved oxygen. Viable counts of culturable heterotrophic bacteria and Vibrio spp. were made. In one sample (March 2003), nutrient concentrations (ammonium, nitrites, nitrates, and phosphates), organic matter, pH and sediment texture were also determined. General cluster analyses, analysis of variance of specific variables, and several principal component analyses demonstrated that seawater temperature is the principal determinant of seasonal distribution of culturable heterotrophic bacteria and Vibrio spp. in mangrove sediments. Soil texture, concentration of nutrients, and organic matter concentration contribute to heterogenicity to a lesser extent. A large spatial variation in bacterial populations was observed over short distances ( approximately 1 m) in sampling areas within the same site. These analyses show that the culturable bacterial distribution in sediments of mangroves has high spatial and temporal heterogeneity.

Pathogenicity of Vibrio penaeicida for white shrimp Litopenaeus vannamei: a cysteine protease-like exotoxin as a virulence factor

The pathogenicity of Vibrio penaeicida Strains KH-1 and AM101, their culture-free supernatant (CFS), and their protein fraction obtained by 40% of ammonium sulfate precipitation (PFs40) were assessed in experimental challenges against juvenile Litopenaeus vannamei. Live Vibrio cells, CFS, and PFs40 from the AM101 strain produced a significantly higher mortality (p < 0.05) compared to the KH-1 strain. Toxicity and median lethal doses (LD50) of Fast Protein Liquid Chromatography (FPLC) products were evaluated on L. vannamei. The first FPLC fraction sample (A) from PFs40 of the AM101 strain displayed LD50 values of 1.68 and 5.61 microg protein ind.(-1), respectively. The second FPLC process from Fraction A showed a peak (A1) also with toxic effects to shrimp. PFs40, Fraction A, and Peak A1 showed a 38.5 kDa molecular band (SDS-PAGE), with activity on a gelatin protease zymogram. The lethal effect of PFs40 and Fraction A was inhibited by Proteinase K, CuCl2, E-64, and heat (60 and 100 degrees C) treatments, but was not inhibited by EDTA-Na2, aprotinin, and soy trypsin treatments. These results and the zymogram inhibition test suggest the presence of a cysteine protease-like proteinaceous exotoxin as a dominant protease, secreted by V. penaeicida Strain AM101.

The major Aeromonas veronii outer membrane protein: gene cloning and sequence analysis

The gene encoding the major outer membrane protein (OMP) from Aeromonas veronii, Omp38, was cloned and characterized. Sequence analysis revealed an open reading frame of 1,047 nucleotides coding for a primary protein of 349 amino acids with a 20-amino-acid signal peptide at the N-terminal and the consensus sequence Ala-X-Ala (Ala-Asn-Ala) as the signal peptidase I recognition site. The mature protein is composed of 329 amino acids with a calculated molecular mass of 36,327 Da. The degree of identity of the deduced Omp38 amino acid sequence to porins from enteric bacteria (OmpF, PhoE, and OmpC) was only 30%. Nevertheless, Omp38 possesses typical features of Gram-negative porins, including acidic pI, high glycine and low proline content, no cysteine residues, and a carboxy-terminal Phe. On the basis of PhoE-OmpF three-dimensional structure and the Kyte-Doolittle hydrophobicity analysis, it seems likely that Omp38 secondary structure consists of 16 antiparallel beta-strands and 8 loops. Phylogenetic analyses among Omp38 and related porins from Gram-negative bacteria originate well-defined clusters that agree with the taxonomy of the corresponding organisms.

Evaluation of DNA vaccination of spotted sand bass (Paralabrax maculatofasciatus) with two major outer-membrane protein-encoding genes from Aeromonas veronii

Genes encoding two major outer membrane proteins (OMPs) of the bacterial pathogen Aeromonas veronii, Omp38 and Omp48, were used to construct DNA vaccines. The protective effect of such vaccines against motile aeromonad septicaemia was evaluated in spotted sand bass (Paralabrax maculatofasciatus), an endemic species of the Mexican Northwest Pacific coast and a potential resource for the aquaculture industry. Weak protein expression, as determined by immunoblotting, was observed after transfection of eukaryotic cells with the DNA vaccines. Fish immunized with a single intramuscular injection of 20 microg of the omp38 and omp48 DNA vaccines showed slightly, but significantly elevated serum antibody levels 4 and 6 weeks after vaccination, compared to fish vaccinated with the control plasmid pcDNA3.1. Spotted sand bass vaccinated with the omp38 and omp48 DNA vaccines and challenged with A. veronii by intraperitoneal route recorded a relative percent survival (RPS) between 50 and 60%. Histopathological signs of motile aeromonad septicaemia were observed in around 40% of omp38 and omp48-vaccinated fish and 80% of pcDNA3.1-vaccinated control fish. The results indicate that P. maculatofasciatus vaccinated with a single dose of DNA plasmids encoding the major OMPs from A. veronii shows partial protection against infection and mortality by A. veronii experimental infection.

Neither gastric topological distribution nor principle virulence genes of Helicobacter pylori contributes to clinical outcomes

AIM: Studies on Helicobacter pylori (H pylori) and gastrodu- odenal diseases have focused mainly on the distal sites of the stomach, but relationship with the gastric cardia is lacking. The aim of this study is to determine if the gastric topology and genotypic distribution of H pylori were associated with different upper gastrointestinal pathologies in a multi-ethnic Asian population.

METHODS: Gastric biopsies from the cardia, body/corpus and antrum were endoscoped from a total of 155 patients with dyspepsia and/or reflux symptoms, with informed consent. H pylori isolates obtained were tested for the presence of 26kDa, ureC, cagA, vacA, iceA1, iceA2 and babA2 genes using PCR while DNA fingerprints were generated using random amplification polymorphic DNA (RAPD).

RESULTS: H pylori was present in 51/155 (33%) of patients studied. Of these, 16, 15 and 20 were isolated from patients with peptic ulcer diseases, gastroesophageal reflux diseases and non-ulcer dyspepsia, respectively. Of the H pylori positive patients, 75% (38/51) had H pylori in all three gastric sites. The prevalence of various genes in the H pylori isolates was shown to be similar irrespective of their colonization sites as well as among the same site of different patients. The RAPD profiles of H pylori isolates from different gastric sites were highly similar among intra-patients but varied greatly between different patients.

CONCLUSION: Topographic colonization of H pylori and the virulence genes harboured by these isolates have no direct bearing to the clinical state of the patients. In multi-ethnic Singapore, the stomach of each patient is colonized by a predominant strain of H pylori, irrespective of the clinical diagnosis.

Adhesive properties of a LamB-like outer-membrane protein and its contribution to Aeromonas veronii adhesion

AIMS

To identify and characterize nonfimbrial proteins from Aeromonas veronii involved in the attachment to epithelial cells in vitro.

METHODS AND RESULTS

Two Aer. veronii mucin- and lactoferrin-binding proteins with molecular masses of 37 and 48 kDa were identified by Western blot analysis. According to its N-terminal amino acid sequence, the 48-kDa protein was identified as Omp48, an outer-membrane protein similar to LamB of Escherichia coli. LamB is a well-known porin involved in maltose transport across the outer membrane in E. coli. In a microtitre plate assay, Omp48 bound to the immobilized extracellular matrix proteins collagen and fibronectin, and the mucin- and lactoferrin-binding activity was confirmed. Adhesion of Omp48 to mucin, lactoferrin and collagen was diminished by preincubation with homologous glycoproteins or other carbohydrates, suggesting a putative Omp48 lectin-like binding domain. Anti-Omp48 antiserum significantly inhibited the Aer. veronii adhesion to confluent HeLa cell monolayers and pretreatment of cells with purified Omp48 elicited competitive inhibition of adhesion. Similarly, cross-inhibition of Aer. hydrophila and Aer. caviae adhesion was achieved with the same treatments, indicating the existence of a conserved surface protein among these species.

CONCLUSIONS

Taken together, these data indicate that Omp48 is involved in Aer. veronii adhesion to epithelial cells and might be an alternative adhesion factor of this micro-organism.

SIGNIFICANCE AND IMPACT OF THE STUDY

The adhesive potential of Aeromonas spp. is correlated with pathogenicity; however, the adhesion mechanism is complex and not well understood. This study provides evidence of a putative adhesion factor that might be contributing to pathogenicity of Aer. veronii and could be used for vaccine development.

Effectiveness ofCyanothece spp. andCyanospira capsulata exocellular polysaccharides as antiadhesive agents for blocking attachment ofHelicobacter pylori to human gastric cells

The effect of cyanobacterial polysaccharides (from Cyanothece spp. and Cyanospira capsulata) on the binding of Helicobacter pylori to gastric epithelial cells was evaluated. The antiadhesive action on Kato III and HeLa S3 human gastric cell lines was established.

Molecular cloning, sequencing and characterization of omp48, the gene encoding for an antigenic outer membrane protein from Aeromonas veronii

AIMS

To clone, sequence and characterize the gene encoding the Omp48, a major outer membrane protein from Aeromonas veronii.

METHODS AND RESULTS

A genomic library of Aer. veronii was constructed and screened to detect omp48 gene sequences, but no positive clones were identified, even under low stringency conditions. The cloned gene probably was toxic to the host Escherichia coli strain, so the cloning of omp48 was achieved by inverse PCR. The nucleotide sequence of omp48 consisted of an open reading frame of 1278 base pairs. The predicted primary protein is composed of 426 amino acids, with a 25-amino-acid signal peptide and common Ala-X-Ala cleavage site. The mature protein is composed of 401 amino acids with a molecular mass of 44,256 Da.

CONCLUSIONS

The omp48 gene from Aer. veronii was cloned, sequenced and characterized in detail. BLAST analysis of Omp48 protein showed sequence similarity (over 50%) to the LamB porin family from other pathogenic Gram-negative bacteria.

SIGNIFICANCE AND IMPACT OF THE STUDY

Bacterial diseases are a major economic problem for the fish farming industry. Outer membrane proteins are potentially important vaccine components. The characterization of omp48 gene will allow further investigation of the potential of Omp48 as recombinant or DNA vaccine component to prevent Aer. veronii and related species infections in reared fish.

Superoxide dismutase as modulator of immune function in American white shrimp (Litopenaeus vannamei)

The immunomodulatory action of superoxide dismutase (SOD) and its possible use as an indicator of immune responses in American white shrimp (Litopenaeus vannamei) were studied. Juvenile shrimp were immersed in aerated beta-glucan and sulfated polysaccharide solutions for 6 h. SOD activity in haemocytes and muscle was quantified to evaluate whether beta-glucan and sulfated polysaccharide induce immunostimulatory activity. Haemocytes and muscle showed similar increased levels of SOD activity (1.5- and 1.4-fold that of control, respectively). Total haemocyte count decreased within the first 24 h after challenge with immunostimulants, but total haemocyte count and total soluble haemocyte protein increased over normal values after 48-120 h. Single immunostimulation with beta-glucan and sulfated polysaccharide is sufficient to generate an increase in the antioxidant activity of L. vannamei SOD.

1,3-beta-D glucan binding protein (BGBP) from the white shrimp, Penaeus vannamei, is also a heparin binding protein

Shrimp BGBP was purified as a 100 kDa glycoprotein by affinity chromatography using immobilised heparin. BGBP bound simple carbohydrates, glycosaminoglycans like heparin sulphate and glycoproteins, but it was unable to agglutinate erythrocytes. Using an ELISA-based microplate assay, it was shown that simple carbohydrates such as n-glucose and D-mannose are competitive inhibitors of heparin sulphate binding to BGBP. Based on these properties BGBP is considered as a new type of heparin binding protein.

Purification and characterization of a surface protein from Lactobacillus fermentum 104R that binds to porcine small intestinal mucus and gastric mucin

An adhesion-promoting protein involved in the binding of Lactobacillus fermentum strain 104R to small intestinal mucus from piglets and to partially purified gastric mucin was isolated and characterized. Spent culture supernatant fluid and bacterial cell wall extracts were fractionated by ammonium sulfate precipitation and gel filtration. The active fraction was purified by affinity chromatography. The adhesion-promoting protein was detected in the fractions by adhesion inhibition and dot blot assays and visualized by polyacrylamide gel electrophoresis (PAGE), sodium dodecyl sulfate-PAGE, and Western blotting with horseradish peroxidase-labeled mucus and mucin. The active fraction was characterized by estimating the relative molecular weight and by assessing the presence of carbohydrates in, and heat sensitivity of, the active region of the adhesion-promoting protein. The purified protein was digested with porcine trypsin, and the peptides were purified in a SMART system. The peptides were tested for adhesion to horseradish peroxidase-labeled mucin by using the dot blot adhesion assay. Peptides which bound mucin were sequenced. It was shown that the purified adhesion-promoting protein on the cell surface of L. fermentum 104R is extractable with 1 M LiCl and low concentrations of lysozyme but not with 0.2 M glycine. The protein could be released to the culture supernatant fluid after 24 h of growth and had affinity for both small intestinal mucus and gastric mucin. In the native state this protein was variable in size, and it had a molecular mass of 29 kDa when denatured. The denatured protein did not contain carbohydrate moieties and was not heat sensitive. Alignment of amino acids of the adhering peptides with sequences deposited in the EMBL data library showed poor homology with previously published sequences. The protein represents an important molecule for development of probiotics.

Generation of superoxide anion and SOD activity in haemocytes and muscle of American white shrimp (Litopenaeus vannamei) as a response to beta-glucan and sulphated polysaccharide

Juvenile American white shrimp (Litopenaeus vannamei) were immersed in aerated beta-glucan and sulphated polysaccharide solutions for 1, 3 and 6 h. Superoxide anion and SOD activity in haemocytes and muscle were investigated to evaluate whether beta-glucan and sulphated polysaccharide induce any immunostimulatory activity. Haemocytes and muscle showed different levels of superoxide anion generation and SOD activity (2.0 and 14 times that of control, respectively) when shrimp were immersed for 6 h in aerated sea water containing beta-glucan and sulphated polysaccharide. Total haemocyte count (THC) decreased within the first 24 h after challenge with immunostimulants, but THC and total soluble haemocyte protein increased over normal values after 48-120 h. Single immunostimulation with beta-glucan and sulphated polysaccharide is capable of generating an increase in the respiratory burst of L. vannamei haemocytes.