Prediction of nitrogen mineralization in organically fertilized growing media for soil-less production     

Patrice Cannavo  Sylvie Recous  Matthieu Valé  Sophie Bresch  Mohammed Benbrahim  René Guénon 《植物养料与土壤学杂志》2023,186(5):532-542

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Molecular analysis of the sex chromosomes of the platyfish Xiphophorus maculatus: Towards the identification of a new type of master sexual regulator in vertebrates     

ASTRID BÖHNE  Christina SCHULTHEIS  Delphine GALIANA‐ARNOUX  Alexander FROSCHAUER  Qingchun ZHOU  Cornelia SCHMIDT  Yvonne SELZ  Catherine OZOUF‐COSTAZ  Agnès DETTAI  Béatrice SEGURENS  Arnaud COULOUX  Sylvie BERNARD‐SAMAIN  Valérie BARBE  Stefan CHILMONCZYK  Frédéric BRUNET  Amandine DARRAS  Marta TOMASZKIEWICZ  Marie SEMON  Manfred SCHARTL  Jean‐Nicolas VOLFF 《Integrative zoology》2009,4(3):277-284

In contrast to mammals and birds, fish display an amazing diversity of genetic sex determination systems, with frequent changes during evolution possibly associated with the emergence of new sex chromosomes and sex‐determining genes. To better understand the molecular and evolutionary mechanisms driving this diversity, several fish models are studied in parallel. Besides the medaka (Oryzias latipes Temminck and Schlegel, 1846) for which the master sex‐determination gene has been identified, one of the most advanced models for studying sex determination is the Southern platyfish (Xiphophorus maculatus, Günther 1966). Xiphophorus maculatus belongs to the Poeciliids, a family of live‐bearing freshwater fish, including platyfish, swordtails and guppies that perfectly illustrates the diversity of genetic sex‐determination mechanisms observed in teleosts. For X. maculatus, bacterial artificial chromosome contigs covering the sex‐determination region of the X and Y sex chromosomes have been constructed. Initial molecular analysis demonstrated that the sex‐determination region is very unstable and frequently undergoes duplications, deletions, inversions and other rearrangements. Eleven gene candidates linked to the master sex‐determining gene have been identified, some of them corresponding to pseudogenes. All putative genes are present on both the X and the Y chromosomes, suggesting a poor degree of differentiation and a young evolutionary age for platyfish sex chromosomes. When compared with other fish and tetrapod genomes, syntenies were detected only with autosomes. This observation supports an independent origin of sex chromosomes, not only in different vertebrate lineages but also between different fish species.  相似文献   

Growth performance and bone mineralization of large Nile tilapia (Oreochromis niloticus) fed graded levels of available phosphorus     

Christiano Rodrigues Schamber  Wilson Rogério Boscolo  Maria Raquel Marçal Natali  Mariana Michelato  Valéria Rossetto Barriviera Furuya  Wilson Massamitu Furuya 《Aquaculture International》2014,22(5):1711-1721

The effect of graded levels of dietary available phosphorus (AP) on large Nile tilapia (145.87 ± 9.51 g) performance, feed efficiency, body composition and mineral retention in vertebrae was evaluated. All male fish were distributed into three replicates in fiberglass aquaria (800 L each; 12 fish per tank) for 87 days and hand fed to pelletized diets three times a day until apparent satiation. Diets with approximately 302 g kg^?1 of digestible protein and 15.2 kJ g^?1 of digestible energy with graded levels of dibasic phosphate yield AP levels of 2.39, 4.17, 6.12 and 8.91 g kg^?1. At the end of the trial, feed intake, hepatosomatic index, fillet yield, whole body moisture and crude protein of fish fed 2.39–8.91 g kg^?1 of AP diets were not significantly different. The supplementation of 6.12 and 8.91 g kg^?1 of AP resulted in significantly increased weight gain, whole body ash and calcium. Whole body crude lipids significantly decreased with increasing AP from 6.12 to 8.91 g kg^?1. However, concentration of zinc in the vertebrae was not affected by dietary treatments. The magnesium contents of the fish vertebrae were lower in fish fed lower dietary AP level. No effects of the dietary AP on apparent digestibility coefficients of energy and nutrients were observed. The study indicated that the dietary AP level of at least 6.12 g kg^?1 satisfies the needs for growth performance, body composition and bone mineralization of large Nile tilapia.  相似文献