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Pattern of sea bass oocyte development after ovarian stimulation by LHRHa (1992)

Alvariño, J. M. R. ; Carrillo, M. ; Zanuy, S. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Journal of fish biology 41 (1992), S. 0

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ISSN: 1095-8649

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: The cyclic pattern of oocyte development in the sea bass, Dicentrarchus labrax L., was studied after induction of spawning by two injections, 24 h apart, of a luteinizing hormone releasing-hormone analog (LHRHa) administered at the end of vitellogenesis. The first difference in the developmental stage of the ovary and in the size-frequency distribution of oocytes between the LHRHa treated group and the control group, was detected 32 h after the first injection, the LHRHa group showing a higher proportion of the 900 μm diameter oocyte class (maturing oocytes) (P〈0.01). At 48 h LHRHa-treated females showed an increase in the 1000 and 1100 μm classes (maturing oocyte and ovulated eggs) (P〈0.01) and at 72 h these females exhibited a bimodal pattern, reaching the highest proportions in the 1100 (27.4%) and the 600 (14.7%) μm classes (ovulated eggs and advanced vitellogenic oocytes, respectively). Bimodal distributions were present in 80% of the LHRHa-treated females. Once oocyte final maturation was triggered by LHRHa the time needed for ovulation was about 48 h and the interval between consecutive ovulations and spawnings seemed to be 48–72 h.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1095-8649.1992.tb02723.x

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Changes in plasma glucagon and insulin associated with fasting in sea bass (Dicentrarchus labrax) (1991)

Gutiérrez, J. ; Pérez, J. ; Navarro, I. ; [et al.]

Springer

Fish physiology and biochemistry 9 (1991), S. 107-112

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ISSN: 1573-5168

Keywords: fasting ; Dicentrarchus labrax ; insulin ; glucagon ; glucose ; liver ; Muscle ; glycogen ; protein

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Juvenile sea bass (Dicentrarchus labrax) were fasted for 22 days and changes in plasma insulin, glucagon and glucose levels, as well as glycogen and protein content in liver and muscle were analyzed. Glucagon increased initially on the 4th day of fasting. The glucagon/insulin ratio (G/I) increased from a value of 0.11±0.02 (24h of fasting) to 0.21±0.05 (4th day of fasting). Thereafter, both glucagon and insulin levels decreased and remained at low concentrations until the 22nd day of fasting. Plasma glucose levels fell at the beginning of fasting, stabilized between the 4th and 8th day, and gradually declined during the rest of the experiment. There was a body weight loss of 15% and a significant decrease in both the hepatosomatic index and mesenteric fat. The decrease in the percentage of muscle proteins was not significant, while liver glycogen content showed a sharp decline.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02265126

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Distribution of salmon gonadotrophin releasing-hormone in the brain and pituitary of the sea bass (Dicentrarchus labrax) (1991)

Kah, O. ; Zanuy, S. ; Mañanos, E. ; [et al.]

Springer

Cell & tissue research 266 (1991), S. 129-136

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ISSN: 1432-0878

Keywords: Gonadotrophin-releasing hormone ; Neuroendocrine control of reproduction ; GnRH immunocytochemistry ; GnRH immunoenzymoassay ; Teleost reproduction ; Dicentrarchus labrax (Teleostei)

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary The distribution of salmon gonadotrophin-releasing hormone (sGnRH) was studied in the brain and pituitary of two-year-old immature sea bass (Dicentrarchus labrax) by means of an enzymoimmunoassay (EIA) for sGnRH and immunocytochemistry. The EIA for sGnRH is a competitive assay using a tracer made of sGnRH coupled to acetylcholinesterase from an electric eel. The separation of free and bound tracer is achieved by coating the plates with mouse anti-rabbit IgG monoclonal antibodies. Displacement curves generated by sGnRH and extracts from pituitary and different brain regions showed a good parallelism allowing the assay to be used for sGnRH measurements in this species. Although all parts of the brain contained measurable levels of sGnRH, the highest concentrations were found in the pituitary, the olfactory bulbs and the telencephalon. These data were confirmed by immunocytochemistry. Cell bodies were found in the olfactory bulbs, ventral telencephalon, preoptic region and mediobasal hypothalamus. Immunoreactive fibers could be observed in all parts of the brain including the optic tectum, the cerebellum (corpus and valvula), the vagal lobe, the medulla oblongata and the rostral spinal cord. In most cases, these fibers do not form well defined bundles; however, there was clearly a continuum of immunoreactive fibers, extending from the olfactory bulbs to the pituitary, and along which all the cell bodies described above were located. In the ventral telencephalon and the preoptic region, clear pictures of varicose positive fibers contacting immunoreactive perikarya could be observed. These data indicate that sGnRH is most likely an endogenous peptide in the brain of the sea bass, although the presence of other forms of GnRH cannot be excluded at this point. This study also demonstrates that the general organization of the GnRH systems in the sea bass is highly similar to what has been described in most freshwater teleost species, and provides basis for further studies on the neuroendocrine control of gonadotrophin release in this commercially important species.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00678719

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Ab initio study of the ground and excited states of HCP and its isomer HPC (1993)

Goldstein, Elisheva ; Jin, Suqian ; Carrillo, M. Robyn ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Computational Chemistry 14 (1993), S. 186-194

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ISSN: 0192-8651

Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Computer Science

Notes: The potential energy surface of HCP converting to HPC in its ground electronic state has been investigated with ab initio methods at levels up to MP2/6-311G**//MP4/6-311G** as well as TZV + + ** CASSCF. All geometries are fully optimized and compare favorably to previous theoretical and experimental values. The HCP molecule is predicted to be 85.4 kcal/mol lower in energy than its linear isomer at the-MP2/6-31G*//MP2/6-31G* level. The energy barrier for hydrogen rearrangement is found to be merely 2.3 kcal from the HPC end. CASSCF studies were initiated to clarify the low barrier and lent support to a flat surface as HPC converts to stable, linear HCP at the TZV + + ** level. CASSCF also predicts that HPC is unstable with respect to bending. Harmonic vibrational frequencies for HCP results in 5% accuracy or better. A bent triplet is found to be the lowest excited state using the CASSCF method. © 1993 John Wiley & Sons, Inc.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jcc.540140206

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