S Milla

Publications (7)16.6 Total impact

• Article: Effects of partial or total fish meal replacement by agricultural by-product diets on gonad maturation, sex steroids and vitellogenin dynamics of African catfish (Clarias gariepinus).

  L Nyina-Wamwiza, P S Defreyne, L Ngendahayo, S Milla, S N M Mandiki, P Kestemont
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  ABSTRACT: The establishment of the first sexual maturation was characterized in African catfish (Clarias gariepinus) in order to study the efficiency of replacement of fish meal (FM) by diets composed of local vegetable ingredients. Four diets were formulated containing decreasing levels of FM (50-0% for diet 1 to diet 4) and increasing proportions of vegetable ingredients (50-100%). Gonadosomatic index (GSI), diameter and percentages of developmental stages of oocytes, plasma sex steroids and vitellogenin dynamics were investigated from February to June using one-year-old fish. Fish were individually tagged, and 12 individuals from each diet were investigated monthly. Replacement of FM with plant ingredients did not affect the GSI neither in males, nor in females. All males were spermiating, and no abnormal gonads were found. In females, GSI and percentages of advanced stages of oocytes decreased during the dry season, indicating seasonal changes in gonad development. Moreover, oocytes were in late exogenous vitellogenesis, but no final maturation stages were observed, whatever the diet. Higher plasma levels of E2 in females and of androgens (T and 11-KT) in both sexes were observed in fish fed diet 4 than in those receiving diet 1 depending on the season. Levels of plasma E2 and ALP (indicator for vitellogenin) in males did not differ among treatments and seasons suggesting no phytoestrogenic activity. The results showed that total replacement of FM by vegetable diets composed of groundnut oilcakes, bean and sunflower meals has no deleterious effect on the onset of sexual maturation in African catfish but, may stimulate the sex steroid production and in turns may potentially exert some positive actions on reproductive success.
  Fish Physiology and Biochemistry 03/2012; 38(5):1287-98. · 1.53 Impact Factor
• Article: Partial and total fish meal replacement by agricultural products in the diets improve sperm quality in African catfish (Clarias gariepinus).

  L Nyina-Wamwiza, S Milla, M-A Pierrard, E Rurangwa, S N M Mandiki, K J W Van Look, P Kestemont
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  ABSTRACT: This study investigated the long-term effects of total and partial replacement of dietary fish meal (FM) by a mixture of agricultural products on sperm quality of African catfish Clarias gariepinus. Four isonitrogenous and isoenergetic diets were formulated containing graded levels of either 50% FM and maize meal (diet 1); 25% FM mixed with crude sunflower oil cake (SFOC) and bean meal (BM) (diet 2); 12.5% FM mixed with sunflower oil cake, BM and ground nut oil cake (GOC) (diet 3) and 0% FM mixed with de-hulled sunflower oil cake (SFOCD), BM and ground nut oil cake (diet 4). Gonadosomatic index (GSI), sperm quality, plasma sex steroids (11-keto testosterone [11-KT]; testosterone [T]; estradiol-17beta [E2]) were evaluated on 10 to 24 fish fed on each diet. Sperm quality was assessed using computer-assisted sperm analysis (CASA). Total replacement of fish meal by plant products markedly increased sperm volume, spermatocrit, spermatozoa integrity, and sperm motility. Fish fed diet 3 (12.5% fish meal) provided intermediate results on sperm quality whereas the lowest values were obtained in fish fed diets 1 and 2. In fish fed 0% fish meal (diet 4), androgen levels were higher and estrogen levels were lower than in fish fed fish meal diets. Based on dietary lipid and fatty acid analyses, these results suggest a positive impact of short chain n-6 fatty acids on androgen synthesis and sperm quality. In conclusion, a combination of ground nut oil cake, bean meal and sunflower oil cake (preferably when the sunflower is dehulled) in African catfish diet improves the sperm quality.
  Theriogenology 01/2012; 77(1):184-94. · 1.96 Impact Factor
• Article: Physiological and proteomic evidences that domestication process differentially modulates the immune status of juvenile Eurasian perch (Perca fluviatilis) under chronic confinement stress.

  J Douxfils, C Mathieu, S N M Mandiki, S Milla, E Henrotte, N Wang, M Vandecan, M Dieu, N Dauchot, L-M Pigneur, X Li, C Rougeot, C Mélard, F Silvestre, K Van Doninck, M Raes, P Kestemont
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  ABSTRACT: The current study aimed to evaluate the influence of domestication process on the stress response and subsequent immune modulation in Eurasian perch juveniles (Perca fluviatilis) submitted to chronic confinement. Briefly, F1 and F4 generations were confined into small-size tanks and sampled 7 and 55 days after stocking. Cortisol and glucose levels as well as lysozyme activity and immunoglobulin level were evaluated in the serum. Spleen Somatic Index and spleen ROS production were also measured. A proteomic analysis was performed on serum sampled on day 7. Finally, both generations were genetically characterized using a microsatellite approach. Globally, results revealed that chronic confinement did not elicit a typical stress response but resulted in a prolonged immune stimulation. Proteomic results suggested that domestication process influenced the immune status of perch submitted to chronic confinement as the F1 confined fish displayed lower abundance of C3 complement component, transferrin and Apolipoprotein E. Microsatellite data showed a strong genetic drift as well as reduced genetic diversity, allelic number and heterozygosity along with domestication process. The present work is the first to report that fish under domestication can develop an immune response, assessed by a combined approach, following recurrent challenges imposed by captive environment despite a reduced genetic variation.
  Fish &amp Shellfish Immunology 12/2011; 31(6):1113-21. · 3.32 Impact Factor
• Article: Does domestication process affect stress response in juvenile Eurasian perch Perca fluviatilis?

  J Douxfils, S N M Mandiki, G Marotte, N Wang, F Silvestre, S Milla, E Henrotte, M Vandecan, C Rougeot, C Mélard, P Kestemont
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  ABSTRACT: The objective was to evaluate the impact of domestication process on the physiological stress response of cultured Eurasian perch confronted to a chronic stress situation. Briefly, F1 and F4 juveniles were submitted to chronic confinement and investigated on days 5, 15 and 30. Capture and 15min-anesthesia were imposed on fish to assess the effect of preceding confinement on acute stress response. On day 30, the fish were finally challenged with Aeromonas hydrophila and sampled after 5 and 10 days for immune parameter measurements. Cortisol and glucose levels were not affected by confinement but increased significantly after acute stressor exposure. Moreover, cortisol rise following capture and anesthesia was higher in F1 confined-fish, suggesting that they have previously been affected by chronic confinement. A higher HSP70 level was also observed on day 30 in F1 confined-juveniles. During bacterial challenge, regardless of confinement level, F4 juveniles displayed higher lysozyme activity and agglutination response than F1 which may indicate a higher immune capacity in domesticated fish. In conclusion, chronic confinement stressor induced few physiological responses but may increase the responsiveness to other aquacultural stressors. Domestication process also seems to improve chronic stress resistance, growth as well as the immune status of the fish.
  Comparative biochemistry and physiology. Part A, Molecular & integrative physiology 02/2011; 159(1):92-9. · 2.20 Impact Factor
• Article: Arachidonic acid induces production of 17,20β-dihydroxy-4-pregnen-3-one (DHP) via a putative PGE2 receptor in fish follicles from the Eurasian perch.

  E Henrotte, S Milla, S N M Mandiki, P Kestemont
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  ABSTRACT: The effects of docosahexaenoic, eicosaenoic and arachidonic acids (DHA, EPA and ARA, respectively) on sex-steroid and prostaglandin (PG) production were investigated in Eurasian perch (Perca fluviatilis) follicles using an in- vitro incubation technique. Only ARA was able to induce the production of 17,20β-dihydroxy-4-pregnen-3-one (DHP), the hormone produced by vitellogenic follicles undergoing final meiotic maturation, as well as the production of PGE2 and PGF2α by the follicles. This work also investigated, using a preliminary pharmacological approach, the presence of a functional PGE2-like receptor in fish follicles. Exogenous PGE2 and butaprost (specific agonist of the EP2 receptor) stimulated DHP production. A second experiment assayed the cyclic adenosine monophosphate (cAMP) production by the follicles after 24 h of incubation with the agonist and antagonist of the EP2 receptor. As observed in mammals, we concluded that the cAMP produced in response to PGE2 was probably mediated by an intracellular mechanism via a PGE2-like receptor. This is the first pharmacological indication of this type of receptors in fish follicles. This study also indicates that ARA, and its derivatives, PGE2 and PGF2α, may act on final follicle maturation in Eurasian perch.
  Lipids 02/2011; 46(2):179-87. · 2.13 Impact Factor
• Article: Ovarian steroidogenesis inhibition by constant photothermal conditions is caused by a lack of gonadotropin stimulation in Eurasian perch.

  S Milla, S N M Mandiki, P Hubermont, C Rougeot, C Mélard, P Kestemont
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  ABSTRACT: In fish, the reasons for the inhibition of reproduction by constant photothermal conditions of rearing are far from clear. In an in vivo experiment, two groups of females reared under natural (4-28 degrees C) or constant photothermal conditions (20-22 degrees C, photoperiod 12/12) were investigated for gonad development, sex-steroids (testosterone-T, 17-beta-estradiol-E2 and 11 Keto-Testosterone-11KT) dynamics and brain aromatase activity in January, February and March. Two days before each sampling date, a group of females reared under constant conditions was injected with HCG (Human Chorionic Gonadotropin: 100 UI/kg) and evaluated for the same parameters. In addition, in vitro ovarian steroidogenesis capacity for each female was determined with or without stimulation by HCG and/or IGF-1 (Insulin-like Growth Factor-1). The results indicate that vitellogenesis stage is the limit ovarian stage never reached in females submitted to constant photothermal conditions. This was associated with gonadogenesis delay and low levels of circulating sex-steroids (T, E2 and 11KT). Nevertheless, HCG injections partly counteracted the plasma steroid deprivation, indicating that ovaries from fish reared under constant photothermal conditions suffer from a lack of gonadotropin stimulation, maybe caused by plasma LH suppression. Such finding was confirmed by the in vitro ovary incubation test. HCG and IGF-1 treatments induced broad testosterone and 17-beta-estradiol elevations and the exposure to constant photothermal conditions, in some cases, decreased that response to HCG. In conclusion, we show that the inhibition of reproductive cycle in Eurasian perch females by constant photothermal conditions of rearing may be related to lower sex-steroid levels and to an inhibition of ovarian regulation by gonadotropins (at least LH), probably stopping gonadogenesis before vitellogenesis stage.
  General and Comparative Endocrinology 05/2009; 163(3):242-50. · 3.27 Impact Factor
• Source

  Available from: Syaghalirwa N M Mandiki

  Article: Corticosteroids: Friends or foes of teleost fish reproduction?

  S Milla, N Wang, S N M Mandiki, P Kestemont
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  ABSTRACT: Reproduction in vertebrates is controlled by the Hypothalamus-Pituitary-Gonad axis and the main hormone actions have been extensively described. Still, despite the scattered information in fish, accumulating evidence strongly indicates that corticosteroids play essential roles in reproductive mechanisms. An integrative approach is important for understanding these implications. Animal husbandry and physiological studies at molecular to organismal levels have revealed that these corticosteroids are regulators of fish reproductive processes. But their involvements appear strongly contrasted. Indeed, for both sexes, corticosteroids present either deleterious or positive effects on fish reproduction. In this review, the authors will attempt to gather and clarify the available information about these physiological involvements. The authors will also suggest future ways to prospect corticosteroid roles in fish reproduction.
  Comparative biochemistry and physiology. Part A, Molecular & integrative physiology 03/2009; 153(3):242-51. · 2.20 Impact Factor