The frequency and strength of extreme events are increasing due to climate change. These events have the potential to cause mass mortalities and recruitment failure in very short time scales. Here, ...we explored three relevant basic questions using green abalone: how the lethal levels of environmental variables (i.e. temperature, oxygen, and pH) change trough time, what the short-term synergistic effects of stressors are, and what the metabolic responses and recovery capacity are at this timescale. We observed that very short-term events are less likely to cause mass mortalities than events lasting for several days, that the relative importance of hyperthermia, hypoxia, and combined effects change through time, and that the respiration rate increased under hyperthermia and decreased under hypoxia and the combined effects, while hemocyanin concentration increased under hypoxia and decreased under hyperthermia and combined effects. Independently of the stressor, green abalone re-established their respiratory rate after the stress.
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 × 106 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.
•Low doses of Aeromonas veronii enhanced humoral immune responses.•TLR9 mRNA basal transcript levels are higher in intestine and leucocytes.•Intestine produces the greatest increase in TLR9 transcript levels upon exposure to A. veronii.
The present study was done in order to identify the fungus invading some of the supralittoral ponds used for shrimp aquaculture in the CIBNOR facilities in La Paz, Baja California Sur (BCS), México ...during the summer season. From the walls and bottoms of the ponds, two strains of Geotrichum spp. were isolated and morphologically identified. Fungal adhesion towards hemocytes and primary cultures of various white shrimp (Litopeneaus vannamei) tissues (gill, tegument, and gut) was analyzed to determine infectivity. Extracellular protease, lipase, and amylase activity were evaluated as virulence factors. Survival of shrimp postlarvae (PL8) exposed to fungal culture supernatant or to their filaments was also investigated. The results showed that shrimp tegument cells and hemocytes were very susceptible to Geotrichum spp. invasion, and that this fungus provokes great mortality of post-larvae. Hence, Geotrichum spp. could be considered an opportunistic pathogen that might represent a serious health risk to shrimp in culture.
The protective effects of two probiotic mixtures was studied using the fingerprints of the bacterial community of Litopenaeus vannamei juveniles exposed to probiotics and challenged with Vibrio ...parahaemolyticus CAIM 170. Fingerprints were constructed using 16S rRNA gene and the PCR-SSCP (Single strand conformation polymorphism) technique, and the probiotics used were an experimental Bacillus mixture (Bacillus tequilensis YC5-2 + B. endophyticus C2-2 and YC3-B) and the commercial probiotic Alibio. The DNA for PCR-SSCP analyses was extracted directly from the guts of shrimps treated for 20 days with the probiotics and injected with 2.5×105 CFU g-1 of V. parahaemolyticus one week after suspension of the probiotic treatment. Untreated shrimps served as positive (injected with V. parahaemolyticus) and negative (not injected) controls Analysis of the bacterial community carried out after inoculation and 12 and 48 h later confirmed that V. parahaemolyticus was present in shrimps of the positive control , but not in the negative control or treated with the probiotic mixtures. A significant difference in the diversity of the bacterial community was observed between times after infection. The band patterns in 0-12 h were clustered into a different group from that determined after 48 h, and suggested that during bacterial infection the guts of whiteleg shrimp were dominated by gamma proteobacteria represented by Vibrio sp. and Photobacterium sp. Our results indicate that the experimental and the commercial mixtures are suitable to modulate the bacterial community of L. vannamei and could be used as a probiotic to control vibriosis in juvenile shrimp.
The purpose of this study was to characterize the TLR21 gene from yellowtail (Seriola lalandi) and its functional activity using TLR agonist stimulation and Aeromonas antigens. The TLR21 nucleotide ...sequence from yellowtail was obtained using the whole-genome shotgun sequencing method and bioinformatics tools. Basal TLR21 gene expression was analyzed in several tissues. Subsequently, the gene expression of TLR21 and cytokines IL-1β and TNF-α was evaluated in TLR agonist (CpG-ODN2006, LPS, and Poly I:C) exposing head kidney leucocytes, which were then subjected to Aeromonas antigen stimulation. The yellowtail full-length cDNA sequence of SlTLR21 was 3615 bp (980 aa) showing a high degree of similarity with the counterparts of other fish species and sharing the common structural architecture of the TLR family, including LRR domains, one C-terminal LRR region, and a TIR domain. Gene expression studies revealed the constitutive expression of TLR21 mRNA in all the analyzed tissues; the highest levels were observed in spleen and head kidney where they play an important role in the fish immune system. Transcripts of TLR21 and the downstream IL-1β and TNF-α cytokine genes were most strongly up-regulated after exposure to the TLR agonists following Aeromonas antigen stimulation, suggesting they are involved in immune response. The results indicated that TLR agonists, in combination with Aeromonas antigens in head kidney leucocytes, synergistically enhance TLR21 and cytokines in yellowtail.
•TLR21gene was identified and characterized in Seriola lalandi.•TLR21 was up-regulated after TLR agonists plus Aeromonas antigens stimulation.•Both IL-1β and TNF-α were strongly enhanced after TLR agonists and Aeromonas antigens stimulation.
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
) 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.
Two trials were conducted to determine the efficacy of fish fed live yeast Debaryomyces hansenii strain CBS 8339 on immune and antioxidant systems in leopard grouper Mycteroperca rosacea infected ...with Aeromonas hydrophila. Juveniles (12±0.5 g) were fed with a control diet or a D. hansenii‐supplemented diet (106 colony‐forming units per gram) for 5 weeks. The live weight of fish was registered on a weekly basis. After 4 weeks, fish from each treatment were immunocompromised with pathogenic A. hydrophila and further fed for 1 week in order to evaluate the effect on immunological and antioxidant parameters. Generally, the results showed enhanced growth performance in fish fed the diet containing yeast compared with the control. Addition of live yeast had no significant effect on the immunological parameters after 4 weeks of feeding. However, post infection with A. hydrophila fish fed the yeast‐supplemented diet resulted in a significant increase in the levels of plasmatic immunoglobulin M. Superoxide dismutase and catalase (CAT) activities were significantly higher in the yeast group. In this fish, CAT and heat shock protein 70 genes were up‐regulated before and after infection of A. hydrophila. The present study is the first one reporting that yeast (D. hansenii) can enhance immunity and resistance against A. hydrophila.
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.
•Structural characterization of D. hansenii CBS 8339 glucan revealed (1–3)-β-D-glucan.•D. hansenii β-glucan reduced cytotoxic effects caused by E. coli in goat leukocytes.•β-glucan enhanced phagocytic ability after E. coli challenge.•β-glucan immunostimulation increased NO production before and after challenge.•D. hansenii β-glucan modulated receptor, regulator and effector gene expressions in goat leukocytes.
El ostión de placer u ostra del Cortés (Crassostrea corteziensis) se considera como una especie con potencial para ser cultivada en gran escala. Sin embargo, al igual que en otros bivalvos, la alta ...mortalidad que se presenta durante la etapa larvaria y juvenil, es el principal problema que limita el desarrollo del cultivo en el laboratorio. Un método que está ganando aceptación en la acuicultura es el uso de bacterias probióticas para controlar patógenos microbianos. Este estudio analiza el efecto de estas bacterias en la supervivencia y talla final de larvas de ostión de placer Crassostrea corteziensis. Se utilizó una cepa de bacterias ácido lácticas (cepa NS61) aisladas N. subnodosus, así como de bacilos aislados de L. vannamei (Pseudomonas aeruginosa, cepa YC58) y de C. corteziensis (Burkholderia cepacia, cepa Y021). Las cepas se evaluaron por inmersión en cultivos larvarios de C. corteziensis a dos concentraciones diferentes, hasta completar el estadio pediveliger. Los organismos se trataron con bacterias ácido lácticas (Lb), una mezcla de bacilos (Lb) en proporción 1:1 y un grupo control. La concentración de 1 x 10.sup.4 UFC/ml registró una mayor supervivencia con Lb y Mb respecto al grupo control. La supervivencia con Mb a una concentración de 1 x 10.sup.5 UFC/ml fue mayor que la del grupo control y del grupo tratado con Lb. Los resultados mostraron que las larvas de C. corteziensis tratadas con probióticos no incrementaron significativamente su talla respecto a las larvas del grupo control. Mientras que las tratadas con Lb a la concentración mayor, 1 x 10.sup.5 UFC/ml, mostraron una disminución de la supervivencia respecto a las tratadas con 1 x 10.sup.4 UFC/ml. Este estudio demostró el efecto benéfico de cepas probióticas utilizadas individualmente o en mezcla en el cultivo larvario de C. corteziensis. Palabras clave: Bacterias probióticas, larvas, Crassostrea cortezienzis, supervivencia, crecimiento. 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.sup.4 and 1 x 10.sup.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.sup.4 CFU/ml compared to the control group. Larvae exposed to Mb at 1 x 10.sup.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.sup.5 CFU/ml showed less survival rate than those treated at 1 x 10.sup.4 CFU/ml. This study showed the beneficial effect of these probiotics, added individually or mixed in C. corteziensis larvae culture. Rev. Biol. Trop. 59 (1): 183-191. Epub 2011 March 01. Key words: probiotic bacteria, larvae, Crassostrea corteziensis, survival, growth.
The aim of this study was to characterize the natural infection by Eimeria spp. in goat kids, and to describe some pathophysiological responses to eimerosis in kids under intensive rearing conditions ...in B.C.S, Mexico. Nineteen adult crossbred does naturally infected with mixed Eimeria spp. and 20 Anglo Nubian x Creole crossbred kids were used. Oocyst per gram of feces (OPG) and identification of Eimeria species were determined in does (during the pre-kidding and post-kidding periods) and kids. Clinical signs, hematocrit, hemoglobin and alkaline phosphatase activity in blood serum were evaluated. OPG (mean±SD) was significantly higher (P<0.05) in pre-kidding (9,478±7,599) than in post-kidding (5,313±2,909) period. Oocyst elimination in feces began at age 59±9 days in kids. Eimerian species identified were E. arloingi, E. jolchijevi, E. ninakohlyakimovae, E. hirci, E. christenseni and E. alijevi. Kids were humanely sacrificed to evaluate pathological lesions. Intestinal lesions and lesion severity showed differences in duodenum, jejunum, ileum, cecum and colon, being more severe in duodenum. In conclusion, OPG increased during the late pregnancy in does which favored a doe-kid transmission mechanism. Our results support the notion of Eimeria reproduction rhythms during the late pregnancy period in goats, and this reproduction contribute to vertical transmission of Eimeria to the newborn. However, coccidian outbreaks are developed and clinically observed only when stressing factors such as when weaning occur. Coccidia had devastating effects on the intestine of kids, which might cause long-term permanent malabsortion consequences. Â
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