Adaptive capacity of female rabbits submitted to a change in breeding practices

[EN] The aim of this study was to test the consequences of a change in breeding practices on 219 multiparous rabbit does over 2 reproductive cycles (5th and 6th insemination). Three rabbit breeding systems were defined I: intensive, S: semi-intensive and E: extensive), which varied for the females in terms of reproductive rhythm (RR: 35, 42 and 49 d, respectively) and age at first insemination (20.6, 19.6 and 16.6 wk, respectively), and for kits in terms of age at weaning (32, 35 and 30 d, respectively) and age at slaughter (63, 70 and 70 d, respectively). Females were submitted to one of the 3 systems from the 1st to the 4th artificial insemination (AI), and to another system from the 5th to the 6th AI, before returning to the initial system at the 7th AI. Consequently, they were allocated to 4 groups: I-S-I, S-I-S, S-E-S and E-S-E. Because of poor reproductive performance in the I system and despite a high growth of kits before weaning due to a more energetic diet for does, a sudden change from an I system to an S system significantly increased productivity at 28 d, from 3.37 to 5.04 kg/AI. Conversely, in the S and E systems, the females were not very sensitive to an intensification (groups S-I-S and E-S-E) or an extensification (S-E-S) of the breeding system, leading to similar productivity at 63 d (14.4 and 14.3 kg/AI, 14.4 and 13.5 kg/AI, 16.5 and 16.2 kg/AI, respectively, for groups S-I-S, E-S-E and S-E-S). The consequences of a return to the initial system deserve to be tested over a longer period.This work was supported by the CAS DAR (Cunipalm n° 9023) and by the French rabbit Interprofessional Association (CLIPP).Theau.clément, M.; Galliot, P.; Souchet, C.; Bignon, L.; Fortun-Lamothe, L. (2016). Adaptive capacity of female rabbits submitted to a change in breeding practices. World Rabbit Science. 24(4):267-273. https://doi.org/10.4995/wrs.2016.5155SWORD267273244Blanc F., Dumont B., Brunschwig G., Bocquier F., Agabriel J. 2010. Extensive ruminant farming systems highlight animal coping processes based on robustness, flexibility and plasticity. In: Robustesse, rusticité, flexibilité, plasticité, résilience, les nouveaux critères de qualité des animaux et des systèmes d'élevage. Sauvant D., Perez J.M. (Eds). Dossier INRA Prod. Anim., 23, 65-80.Maertens, L., Perez, J.M., Villamide, M., Cervera, C., Gidenne, T., Xiccato, G., 2002. Nutritive value of raw materials for rabbits: EGRAN tables 2002. World Rabbit Sci., 10: 157-166.Theau-Clément M., Boiti C., Mercier P., Falières J. 2000. Description of the ovarian status and fertilising ability of primiparous rabbit does at different lactation stage, In Proc.: 7th World Rabbit Congress, 4-7 July 2000, Valencia, Spain, Vol A: 259-266

CELL WALL INVERTASE 4 is required for nectar production in Arabidopsis

To date, no genes have been reported to directly affect the de novo production of floral nectar. In an effort to identify genes involved in nectar production, the Affymetrix® ATH1 GeneChip was previously used to examine global gene expression profiles in Arabidopsis thaliana nectaries. One of the genes displaying highly enriched expression in nectaries was CELL WALL INVERTASE 4 (AtCWINV4, At2g36190), which encodes an enzyme that putatively catalyses the hydrolysis of sucrose into glucose and fructose. RT-PCR was used to confirm the nectary-enriched expression of AtCWINV4, as well as an orthologue from Brassica rapa. To probe biological function, two independent Arabidopsis cwinv4 T-DNA mutants were isolated. Unlike wild-type plants, cwinv4 lines did not produce nectar. While overall nectary morphology appeared to be normal, cwinv4 flowers accumulated higher than normal levels of starch in the receptacle, but not within the nectaries themselves. Conversely, wild-type, but not cwinv4, nectarial stomata stained intensely for starch. Cell wall extracts prepared from mutant flowers displayed greatly reduced invertase activity when compared with wild-type plants, and cwinv4 flowers also accumulated significantly lower levels of total soluble sugar. Cumulatively, these results implicate CWINV4 as an absolutely required factor for nectar production in the Brassicaceae, specifically by maintaining constant sink status within nectaries, thus allowing them to accumulate the sugars necessary for nectar production. In addition, CWINV4 is probably responsible for the hexose-rich composition observed for many Brassicaceae nectars

Diversity, Phylogeny and Expression Patterns of Pou and Six Homeodomain Transcription Factors in Hydrozoan Jellyfish Craspedacusta sowerbyi

Formation of all metazoan bodies is controlled by a group of selector genes including homeobox genes, highly conserved across the entire animal kingdom. The homeobox genes from Pou and Six classes are key members of the regulation cascades determining development of sensory organs, nervous system, gonads and muscles. Besides using common bilaterian models, more attention has recently been targeted at the identification and characterization of these genes within the basal metazoan phyla. Cnidaria as a diploblastic sister group to bilateria with simple and yet specialized organs are suitable models for studies on the sensory organ origin and the associated role of homeobox genes. In this work, Pou and Six homeobox genes, together with a broad range of other sensory-specific transcription factors, were identified in the transcriptome of hydrozoan jellyfish Craspedacusta sowerbyi. Phylogenetic analyses of Pou and Six proteins revealed cnidarian-specific sequence motifs and contributed to the classification of individual factors. The majority of the Craspedacusta sowerbyi Pou and Six homeobox genes are predominantly expressed in statocysts, manubrium and nerve ring, the tissues with sensory and nervous activities. The described diversity and expression patterns of Pou and Six factors in hydrozoan jellyfish highlight their evolutionarily conserved functions. This study extends the knowledge of the cnidarian genome complexity and shows that the transcriptome of hydrozoan jellyfish is generally rich in homeodomain transcription factors employed in the regulation of sensory and nervous functions

Changing Hydrozoan Bauplans by Silencing Hox-Like Genes

Regulatory genes of the Antp class have been a major factor for the invention and radiation of animal bauplans. One of the most diverse animal phyla are the Cnidaria, which are close to the root of metazoan life and which often appear in two distinct generations and a remarkable variety of body forms. Hox-like genes have been known to be involved in axial patterning in the Cnidaria and have been suspected to play roles in the genetic control of many of the observed bauplan changes. Unfortunately RNAi mediated gene silencing studies have not been satisfactory for marine invertebrate organisms thus far. No direct evidence supporting Hox-like gene induced bauplan changes in cnidarians have been documented as of yet. Herein, we report a protocol for RNAi transfection of marine invertebrates and demonstrate that knock downs of Hox-like genes in Cnidaria create substantial bauplan alterations, including the formation of multiple oral poles (“heads”) by Cnox-2 and Cnox-3 inhibition, deformation of the main body axis by Cnox-5 inhibition and duplication of tentacles by Cnox-1 inhibition. All phenotypes observed in the course of the RNAi studies were identical to those obtained by morpholino antisense oligo experiments and are reminiscent of macroevolutionary bauplan changes. The reported protocol will allow routine RNAi studies in marine invertebrates to be established

Defining the tipping point. A complex cellular life/death balance in corals in response to stress

Apoptotic cell death has been implicated in coral bleaching but the molecules involved and the mechanisms by which apoptosis is regulated are only now being identified. In contrast the mechanisms underlying apoptosis in higher animals are relatively well understood. To better understand the response of corals to thermal stress, the expression of coral homologs of six key regulators of apoptosis was studied in Acropora aspera under conditions simulating those of a mass bleaching event. Significant changes in expression were detected between the daily minimum and maximum temperatures. Maximum daily temperatures from as low as 3°C below the bleaching threshold resulted in significant changes in both pro- and anti-apoptotic gene expression. The results suggest that the control of apoptosis is highly complex in this eukaryote-eukaryote endosymbiosis and that apoptotic cell death cascades potentially play key roles tipping the cellular life/death balance during environmental stress prior to the onset of coral bleaching