ABSTRACT
Life-history traits such as spawning migrations and timing of reproduction are adaptations to specific environmental constraints and seasonal cycles in many organisms' annual routines. In this study we analyse how offspring fitness constrains spawning phenology in a large migratory apex predator, the Atlantic bluefin tuna. The reproductive schedule of Atlantic bluefin tuna varies between spawning sites, suggesting plasticity to local environmental conditions. Generally, temperature is considered to be the main constraint on tuna spawning phenology. We combine evidence from long-term field data, temperature-controlled rearing experiments on eggs and larvae, and a model of egg fitness, and show that Atlantic bluefin tuna do not spawn to optimize egg and larval temperature exposure. The timing of spawning leads to temperature exposure considerably lower than optimal at all spawning grounds across the Atlantic Ocean. The early spawning is constrained by thermal inhibition of egg hatching and larval growth rates, but some other factors must prevent later spawning. Matching offspring with ocean productivity and the prey peak might be an important driver for bluefin tuna spawning phenology. This finding is important for predictions of reproductive timing in future climate warming scenarios for bluefin tuna.
Subject(s)
Animal Migration/physiology , Global Warming , Reproduction/physiology , Temperature , Tuna/physiology , Animals , Atlantic Ocean , Chlorophyll , Female , Larva/growth & development , Ovum/growth & development , Seasons , Time Factors , ZooplanktonABSTRACT
The cDNA sequences of vitellogenin receptor proteins (VgR(+) and VgR(-)), containing or lacking the O-linked sugar domain, were determined in Atlantic bluefin tuna (Thunnus thynnus L.). VgR(-) gene expression in the ovary was compared in captive-reared and wild Atlantic bluefin tuna during the reproductive cycle. Gonad samples from adult fish were sampled from 2008 to 2010 from stocks reared in captivity at different commercial fattening operations in the Mediterranean Sea and from wild individuals caught either by traditional tuna traps during their migration towards the spawning grounds in the Mediterranean Sea or by the long-line artisanal fishery. In addition, juvenile male and female Atlantic bluefin tuna were sampled from a farming facility, to obtain baseline information and pre-adulthood amounts of VgR(-). The total length of VgR(+) cDNA was 4006 nucleotides (nt) and that of VgR(-) was 3946 nt. Relative amounts of VgR(-) were greater in juvenile females and in those adults having only previtellogenic oocytes (119 ± 55 and 146 ± 26 folds more than juvenile males, respectively). Amounts of VgR(-) were less in individuals with yolked oocytes (ripening stage, May-June) and increased after spawning in July (92 ± 20 and 113 ± 13 folds more than juvenile males in ripening and post-spawning fish, respectively). These data suggest that regulation of VgR(-) is not under oestrogen control. During the ripening period, greater VgR(-) gene expression was observed in wild fish than in fish reared in captivity, possibly because of (a) differences in water temperature exposure and/or energy storage, and/or (b) an inadequate diet in reared Atlantic bluefin tuna.
Subject(s)
Egg Proteins/biosynthesis , Ovary/physiology , Receptors, Cell Surface/biosynthesis , Tuna/metabolism , Amino Acid Sequence , Animals , Base Sequence , Egg Proteins/genetics , Female , Gene Expression Regulation , Histocytochemistry/veterinary , Male , Mediterranean Sea , Molecular Sequence Data , Oocytes/physiology , Ovary/metabolism , RNA/chemistry , RNA/genetics , Receptors, Cell Surface/genetics , Reverse Transcriptase Polymerase Chain Reaction/veterinary , Seasons , Sequence Alignment , Sequence Analysis, DNA , Tuna/geneticsABSTRACT
A controlled-release implant loaded with GnRH agonist (GnRHa) was used to induce spawning in Atlantic bluefin tuna (Thunnus thynnus) during two consecutive reproductive seasons. The fish were implanted underwater and sampled between days 2 and 8 after treatment. At the time of GnRHa treatment, females were in full vitellogenesis and males in spermiation. There was a rapid burst of pituitary luteinizing hormone (LH) release at day 2 after treatment in GnRHa-treated fish, and circulating LH remained elevated up to day 8 after treatment. In contrast, control fish had significantly lower levels in the plasma, but higher LH content in the pituitary, as observed in many other cultured fishes that fail to undergo oocyte maturation, ovulation and spawning unless induced by an exogenous GnRHa. Plasma testosterone (T) and 17ß-estradiol (E(2)) were elevated in response to the GnRHa treatment in females, while 11-ketotestosterone (11-KT) but not T was elevated in males. Even though oocyte maturation and ovulation did occur in GnRHa-induced fish, no significant elevations in 17,20ß-dihydroxy-4-pregnen-3-one (17,20ß-P) or 17,20ß,21-trihydroxy-4-pregnen-3-one (20ß-S), in either the free, conjugated or 5ß-reduced,3α-hydroxylated forms was observed in fish sampled within 6 days after treatment. Interestingly, a significant peak in plasma free 17,20ß-P levels occurred in both males and females at day 8 after treatment. Histological sections of the ovaries in these females contained oocytes at the migrating germinal vesicle stage, suggesting the role of this hormone as a maturation-inducing steroid in Atlantic bluefin tuna. In conclusion, the GnRHa implants activated effectively the reproductive endocrine axis in captive Atlantic bluefin tuna broodstocks, through stimulation of sustained elevations in plasma LH, which in turn evoked the synthesis and secretion of the relevant sex steroids leading to gamete maturation and release.
Subject(s)
Endocrine System/physiology , Gonadotropin-Releasing Hormone/agonists , Reproduction/physiology , Sexual Maturation/physiology , Tuna/physiology , Animals , Endocrine System/drug effects , Female , Gonadotropin-Releasing Hormone/pharmacology , Luteinizing Hormone/metabolism , Male , Ovulation/drug effects , Ovulation/physiology , Reproduction/drug effects , Seasons , Testosterone/metabolismABSTRACT
The sequence of vitellogenin A (VgA) and vitellogenin B (VgB) cDNAs in Atlantic bluefin tuna (Thunnus thynnus L.) were determined, and vitellogenin expression levels in the liver and oocyte yolk accumulation were compared in wild and captive-reared individuals. Liver and ovary samples were taken from 31 individuals reared experimentally in three commercial Atlantic bluefin tuna fattening sites in the Mediterranean Sea and from 33 wild individuals caught by commercial traps during the fish's migration towards their Mediterranean spawning grounds. The total length of VgA cDNA was 5585 nucleotides and that of VgB was 5267 nucleotides. The identity and similarity between deduced amino acid sequences of VgA and VgB were 60% and 78%, respectively. The Atlantic bluefin tuna VgA and VgB amino acid sequences have high similarities with those of other teleost fishes. Relative levels of VgA and VgB mRNAs were low in April, increased significantly during the reproductive period in May and June, and declined in July. There was a trend towards higher relative levels of VgA and VgB mRNAs in captive fish compared to wild individuals during the reproductive period. The surface occupied by eosinophilic yolk granules in fully vitellogenic oocytes, as well as the frequency of oocytes in late vitellogenesis, was significantly higher in captive compared to wild individuals. The study suggests that the experimental conditions under which Atlantic bluefin tuna individuals were reared allowed the occurrence of normal vitellogenesis, based on gene expression of VgA and VgB in the liver and yolk accumulation in the oocytes. The higher yolk accumulation and frequency of vitellogenic oocytes observed in the ovaries of captive fish suggest that improvements in feeding practices may result in an improved vitellogenic process.
Subject(s)
Egg Yolk/metabolism , Liver/metabolism , Oocytes/metabolism , Tuna/genetics , Vitellogenins/genetics , Animals , Animals, Wild/genetics , Animals, Wild/metabolism , Aquaculture , Cloning, Molecular , Female , Gene Expression , Tuna/metabolism , Vitellogenins/biosynthesis , Vitellogenins/metabolismABSTRACT
The effects of administration of gonadotropin-releasing hormone agonist (GnRHa) on proliferation and apoptosis of male germ cells were evaluated on Atlantic bluefin tuna (Thunnus thynnus L.) reared in captivity. Fish (n=19) were treated with a sustained-release delivery system loaded with GnRHa during the natural spawning season of 2004 and 2005 (June-July). Untreated Control fish (n=17) and adult wild spawners were used for comparison. Fish were sacrificed 2-8 d after GnRHa implantation and body weight and gonad weight were recorded, and gonads and blood were taken. Germ cell proliferation and apoptosis were evaluated through the immunohistochemical detection of proliferating cell nuclear antigen (PCNA) and the terminal deoxynucleotidyl transferase-mediated d'UTP nick end labelling (TUNEL) method, respectively. Plasma 11 ketotestosterone (11-KT) levels were measured using an ELISA method. Mean gonado-somatic index and seminiferous lobule diameter did not differ between GnRHa-treated and Control fish, and were significantly lower in captive-reared individuals than in wild spawners. Significant increases in 11-KT plasma levels and spermatogonial mitosis, along with a reduction of germ cell apoptosis were demonstrated in GnRHa-treated fish compared to Controls. The results suggest that GnRHa administration was effective in enhancing germ cell proliferation and reducing apoptosis in captive males through the stimulation of luteinizing hormone (LH) release and testicular 11-KT production.
Subject(s)
Apoptosis/drug effects , Cell Proliferation/drug effects , Gonadotropin-Releasing Hormone/agonists , Spermatozoa/drug effects , Tuna/physiology , Animals , Animals, Wild , Drug Implants , Fisheries , Germ Cells/drug effects , Gonadotropin-Releasing Hormone/administration & dosage , Gonadotropin-Releasing Hormone/pharmacology , Male , Spermatozoa/physiology , Testosterone/analogs & derivatives , Testosterone/blood , Tuna/bloodABSTRACT
Liposarcoma is a malignant tumor that has an embryologic origin from mesodermal tissue depending on fatty tissue. Although liposarcoma is only 0.1% of all human neoplasms, it is the most common histology subtype of retroperitoneal soft tissue sarcomas. This tumor grows slowly. Diffuse abdominal pain is its most frequent symptom and abdominal mass is the most common sign. Aggressive surgical treatment is basic to get a complete resection and a local disease control. This objective is difficult because of the large tumor size it gets in the retroperitoneal location and the multiorgan involvement that require the resection of a high percentage of contiguous organs. We report a case of a giant retroperitoneal liposarcoma presenting like continuous left hemiabdominal pain because of the visceral compression. The right kidney was involved and suffering from renal vessel enlargement without renal function. There is a high probability of microscopic residual disease and a good follow-up of the patients is necessary as well as an adjuvant radiation therapy in some cases.
Subject(s)
Liposarcoma/pathology , Retroperitoneal Neoplasms/pathology , Abdominal Pain/etiology , Calcinosis/diagnosis , Calcinosis/pathology , Female , Humans , Infarction/etiology , Kidney/blood supply , Liposarcoma/diagnosis , Liposarcoma/surgery , Magnetic Resonance Imaging , Middle Aged , Physical Examination , Retroperitoneal Neoplasms/diagnosis , Retroperitoneal Neoplasms/surgery , Tomography, X-Ray ComputedABSTRACT
Los cuadros de dolor abdominal en la población infectada por el virus de la inmunodeficiencia humana (VIH) son frecuentes, debido a las enfermedades asociadas a este virus, por lo que a menudo se producen errores y retrasos en el diagnóstico y tratamiento de la apendicitis aguda, incrementándose la tasa de complicaciones. En este trabajo se describe un caso de fístula apendicocutánea en un paciente infectado por el VIH al que no se le diagnosticó una apendicitis aguda (AU)
Subject(s)
Appendicitis/diagnosis , Appendicitis/complications , Appendicitis/therapy , Fistula/complications , HIV Infections/diagnosis , HIV Infections/complications , HIV Infections/therapyABSTRACT
Introducción. Los pacientes con tumores sólidos avanzados desarrollan frecuentemente anemia. El mecanismo más importante en la patogenia de la anemia es el descenso de la eritropoyesis. Ésta puede ser debida a un descenso de la síntesis de eritropoyetina, una menor actividad de ésta sobre la médula ósea o una respuesta disminuida de la médula ósea a la eritropoyetina. El objetivo de este estudio es analizar la tasa de eritropoyetina en pacientes con cáncer colorrectal poco avanzado, comparándola con un grupo control. Pacientes y métodos. Hemos estudiado a 20 pacientes con cáncer colorrectal, que fueron diagnosticados por estudio radiológico y/o endoscópico con biopsia, y a un grupo control de 20 sujetos sanos. Tras el diagnóstico se determinaron los siguientes parámetros séricos: hemoglobina, hematócrito, hematíes y eritropoyetina. El análisis estadístico se realizó con el test de la t de Student y las correlaciones entre las variables con el test de Pearson (r). Resultados. Los parámetros hematológicos fueron inferiores en el grupo del cáncer colorrectal, aunque se hallaban dentro de la normalidad. La tasa de eritropoyetina en este grupo se encontraba significativamente aumentada (p < 0,01), existiendo una correlación entre la eritropoyetina y la hemoglobina (r = 0,59; p < 0,01), y entre la eritropoyetina y el hematócri-to (r = 0,61; p < 0,01).Conclusiones. Las concentraciones de eritropoyetina están muy elevadas en los pacientes con cáncer colorrectal, a pesar de no presentar una anemia evidente, pudiendo deberse este incremento a otras causas (factores tumorales, citocinas, etc.) (AU)
Subject(s)
Adult , Female , Male , Middle Aged , Humans , Erythropoietin/therapeutic use , Hemoglobins/analysis , Hematocrit/methods , Colonic Neoplasms/surgery , Colonic Neoplasms/drug therapy , Colonic Neoplasms/complications , Colonic Neoplasms/diagnosis , Hematologic Tests , Cytokines/therapeutic use , Anemia/drug therapy , Anemia/etiology , Anemia/epidemiologyABSTRACT
1. 4-Aminopyridine and 3,4-diaminopyridine produced concentration-dependent contraction on guinea-pig isolated ileum incubated in Tyrode solution. The EC30 values were 1.14 x 10(-4) and 1.39 x 10(-4) M, respectively. 2. Calcium channel blockers such as verapamil, diltiazem, nifedipine, flunarizine, and lanthanum chloride antagonized the contracting effect induced by 4-aminopyridine and 3,4-diaminopyridine in guinea-pig isolated ileum. 3. Diazoxide and atropine sulphate behaved similarly as antagonists of the contracting effect induced by 4-aminopyridine and 3,4-diaminopyridine in guinea-pig isolated ileum. 4. It is concluded that the aminopyridines exert their effects through the release of acetylcholine from parasympathetic nerve terminals.
Subject(s)
4-Aminopyridine/analogs & derivatives , 4-Aminopyridine/pharmacology , Ileum/drug effects , Muscle, Smooth/drug effects , Potassium Channels/drug effects , 4-Aminopyridine/antagonists & inhibitors , Acetylcholine/metabolism , Amifampridine , Animals , Atropine/pharmacology , Calcium Channel Blockers/pharmacology , Diazoxide/pharmacology , Diltiazem/pharmacology , Dose-Response Relationship, Drug , Drug Interactions , Female , Flunarizine/pharmacology , Guinea Pigs , Ileum/metabolism , In Vitro Techniques , Lanthanum/pharmacology , Male , Muscle Contraction/drug effects , Nifedipine/pharmacology , Parasympathetic Nervous System/drug effects , Parasympathetic Nervous System/metabolism , Parasympatholytics/pharmacology , Vasodilator Agents/pharmacology , Verapamil/pharmacologyABSTRACT
1. Adrenergic and cholinergic mechanisms seem to be involved in the pathogenesis of stress ulcers. 2. In this study, gastric ulcers were induced in rats by immobilization and cold. Prior intraperitoneal administration of both anticholinergic (atropine) as well as alpha-blocking medication (phenoxybenzamine) produced a very significant decrease in stress ulcers. 3. Additionally, using the technique of continuous intravenous perfusion in rats, acetylcholine was shown to have a gastric ulcerogenic effect, in contrast to noradrenaline. 4. It is concluded that acetylcholine is the peripheral mediator in stress ulcers, while noradrenaline intervenes at the encephalic level in stress ulcer pathogenesis.
Subject(s)
Acetylcholine/metabolism , Norepinephrine/metabolism , Stomach Ulcer/etiology , Stress, Physiological/complications , Animals , Female , Rats , Rats, Wistar , Stomach Ulcer/metabolismABSTRACT
The purpose of the present report is to study the effects of antidepressants such as trimipramine, amitriptyline, maprotiline and mianserin on severe gastric mucosal lesions produced by ethanol in comparison with cimetidine (H2-antihistamine) and dexchlorepheniramine (H2-antihistamine). The percentage of macroscopic mucosal lesions caused by alcohol affects 15% of the mucosal area. But pretreated with cimetidine the affected area was 9.18%, with dexchlorepheniramine 5.01%, with trimipramine 14.46%, with amitripytline 7.94%, with maprotiline 3.8%, and with mianserin 4.07%. Microscopic evaluation reveals that ethanol produces destruction of glandular cells and injures medial and basal layers. All drugs used previously to ethanol produce a decrease of microscopical lesions. A direct relation was found between micro and macroscopical lesions in rats treated with maprotiline, mianserin and dexchlorepheniramine.
