61 research outputs found

    Examining the Effectiveness of Probiotic Therapy for Improving Growth Performance of Triploid Chinook Salmon (Oncorhynchus Tshawytscha) in Aquaculture Using a Behavioural Genomics Approach

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    With an increasing human population, there has been increased production of fish to meet nutritional needs. Commercial aquaculture accounts for a significant portion of seafood production with salmonids being the major farmed finfish in Canada. To obtain greater biomass from aquaculture with minimal drawbacks (e.g., compromised flesh quality), triploidization has been implemented, altering ploidy from 2N to 3N, to induce sterility and promote energy investment towards somatic growth. Triploid individuals experience transcriptional and behavioural changes resulting in disease, mortalities, and reduced growth. Probiotic therapies (live microorganisms) have been recommended to potentially overcome drawbacks of triploidy and improve mass due to the purported benefits to the host. Through a behavioural genomics approach, I examined neural transcriptional profiles (i.e., relating to neural functions, stress response, appetite/metabolism, and growth) and combined these with behavioural profiles via behavioural assays (i.e., open field, novel object, predator, and mirror tests) in hatchery-reared juvenile Chinook salmon (Oncorhynchus tshawytscha). Siblings from 15 families were placed in four treatment groups: 2N-regular feed, 2N-probiotic feed, 3N-regular feed, and 3N-probiotic feed to determine mechanisms driving differential growth. I found no universal effects of treatments on growth. While triploid individuals had reduced mass, growth was influenced by transcription, including interactions between a bold/aggressive behavioural profile and Shh gene transcription. Probiotic therapy (i.e., Lactobacillus, Bifidobacterium, and Lactococcus) had no direct impact on mass, but increased mass when coupled with high gene transcription of p53. Through behavioural genomics, I uncovered important relationships and interactions that remain to be further described

    AN INVESTIGATION OF THE ROLE OF AMYGDALAR CIRCUITS IN THE PRODUCTION OF SOCIAL BEHAVIOR

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    Adaptive social behaviors allow animals to survive, thrive, and successfully reproduce. These behaviors, including mating, parenting, affiliation, and aggression, can be stereotyped in response to specific stimuli but often display sex-specific, and interoceptive-dependent variations in their execution. A conserved set of brain regions collectively known as the social behavior network (SBN) interprets sensory information about social cues and generates an appropriate behavioral response. In this dissertation I present 5 chapters. Chapter 1 introduces historical research focusing on the neural circuits that drive social behavior and the potential impact of environmental factors on the activity of these circuits. Chapter 2 describes a new technique that uses magnetohydrodynamic-based tissue clearing to investigate intact neural circuits rapidly and efficiently. Chapter 3 uses this approach to interrogate the synaptic connections of a primary hub for social sensory integration, the medial amygdala (MeA). I focused on neurons in the MeA that express an enzyme that plays an important role in the development of sex-specific social behaviors: aromatase and identified the sources of synaptic input to this population. These inputs included regions involved in maintaining metabolic homeostasis, production of socio-sexual behaviors, fear/anxiety, parenting, and aggressive behaviors –suggesting an expanded view of social behavior production. I demonstrate that the brain regions involved in the production of social behavior have broad access to internal physiological and external environmental information. Chapter 4, demonstrates the impact of external environmental factors on the behaviors produced in response to a social stimulus, as well as, on the early sensory representation of these stimuli in the AOB. Predator presence influences an animals’ responses to conspecific stimuli even when not presented concurrently. This effect was observed in males and females and in response to male and female stimuli, demonstrating a generalizable impact of environmental conditions on the sensory representation of social stimuli. Chapter 5 summarizes these findings in a broader context, arguing for an expanded role for the SBN in integrating internal and external environmental information with sensory perceptions of social stimuli to produce appropriate behavioral response for not only a specific social stimulus, but a specific environmental context

    CANNIBALISM PERFORMANCE OF ASIAN REDTAIL CATFISH (Hemibagrus nemurus) FED RATION SUPPLEMENTED WITH DIFFERENT DOSES OF 17α-METHYLTESTOSTERONE

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    One of the obstacles in Asian redtail catfish hatchery is the high cannibalism incidence. Cannibalism is associated with aggressive behavior caused by hormonal metabolism especially of testosterone. The purpose of this study was to evaluate the effect of testosterone administration on the cannibalism incidence in the Asian redtail catfish juveniles.  The experiment was conducted by rearing fish with initial length of 4.09±0.19 cm in 16 of 20 L aquariums with a density of 2 fish L-1. The experiment was designed with a completely randomized design with 4 treatments which were different level of 17α-methyltestosterone supplementation in feed, i.e., 0 mg kg-1 feed (A) as control, 7.5 mg kg-1 feed (B), 15 mg kg-1 feed (C), and 30 mg kg-1 feed (D). Each treatment has 4 replications. Fish fed experimental diet (40% protein) 4 times a day to satiation for 30 days. The parameters observed were type and index of cannibalism, aggressive behavior, survival rate, normal mortality, growth performance, hormones concentrations (estradiol, testosterone, and cortisol), and water quality. The results showed that cannibalism type II (the fish eaten completely or missing) and cannibalism index increased with the increasing doses of testosterone administration in the feed with the highest cannibalism incidence was 40.63%. The highest survival rate was found in treatment B (73.75±2.50%) and was not significantly different from the control treatment (69.38±2.39%). No differences in testosterone concentration and in the growth performance among the treatments.  However, there was a trend of decrease in the estradiol concentration of Asian redtail catfish juveniles fed ration supplemented with the increasing doses of 17α-methyltestosterone. Based on the results obtained in this research, estradiol changed in the body's plasma, it appears that there was a role for plasma estradiol concentration in controlling cannibalism of Asian redtail catfish juveniles. It concluded that the testosterone administration affected the cannibalism incidence in the Asian redtail Catfish.

    An Investigation Into the Origin and Molecular Mechanism of Species-Specific Craniofacial Sexual Dimorphism in Lake Malawi Cichlids

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    Explaining the underlying source that generates the phenotypic diversity ubiquitous in nature has been a major goal of biologists since the time of Darwin. In addition to the phenotypic variation that exists between different species, another potent source of morphological diversity is found within a species, in the form of phenotypic differences that are specific to males and females, termed sexual dimorphism. The largest craniofacial bone, the mandible, exhibits such extreme sexual dimorphism that it may be used to forensically determine sex. This dimorphism occurs in most of the craniofacial complex and contributes to sex-biased disease frequencies, such as a higher prevalence of temporomandibular joint (TMJ) disorders in females and higher rates of cleft lip and/or palate in males. The developmental timing of these male-female differences, and the molecular mechanisms that facilitate them, are unknown. Lake Malawi cichlids are an attractive model system for studying craniofacial development, due to their recent adaptive radiation which has produced several species with a range of diverse craniofacial phenotypes. To understand the evolutionary and developmental influences that drive species-specific craniofacial sexual dimorphism, we quantified the degree of sexual dimorphism in the lateral and ventral mandible, as well as the lateral and ventral overall head shape in five cichlid species, using geometric morphometrics. We observed sexual dimorphism in all but the ventral mandible, and these sex differences were species-specific. We also determined the serum and gonad concentration of estradiol and progesterone in two cichlid species for the first time and found that they were sexually dimorphic and occurred in species-specific patterns. Finally, we manipulated estradiol and hormone signaling in embryos at various developmental stages and quantified their phenotypic effects with geometric morphometrics. We discovered that estradiol affects the development of the craniofacial skeleton during the windows of bone and cartilage progenitor cell migration, while progesterone affects development at later stages, mainly during early chondrogenesis. Taken together, we were able to gain a further understanding of how sex hormone signaling in early craniofacial development translates into species-specific sexual dimorphism, and these results allow us insight into the potential evolutionary pressures driving these phenotypic differences between males and females

    PENGARUH SUPLEMENTASI TRIPTOFAN MELALUI PAKAN TERHADAP KANIBALISME DAN KONSENTRASI HORMON STEROID BENIH IKAN BAUNG (Hemibagrus nemurus)

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    Perilaku kanibal pada benih ikan baung (Hemibagrus nemurus) menjadi permasalahan pada pembenihannya. Salah satu pendekatan yang sudah dilakukan untuk mengendalikan kanibalisme pada ikan adalah pemberian triptofan.  Penelitian ini bertujuan untuk mengetahui pengaruh triptofan terhadap kejadian kanibalisme dan kandungan konsentrasi hormon steroid pada benih ikan baung. Panjang awal benih yang digunakan adalah 4,98±0,1 cm yang dipelihara di dalam akuarium berkapasitas 20 L dengan kepadatan 3 ekor per L.  Selama penelitian, benih ikan baung diberi pakan komersial (40% protein) yang disuplementasi triptofan dengan konsentrasi berbeda, yaitu tanpa suplementasi triptofan (A), suplementasi triptofan 0,25% (B), suplementasi triptofan 0,50% (C), suplementasi triptofan 0,75% (D), dan suplementasi triptofan 1% (E). Setiap perlakuan terdiri dari tiga kali ulangan. Pakan diberikan empat kali sehari secara satiasi. Parameter yang diamati adalah tipe kanibal, indeks kanibal, kematian normal, sintasan, performa pertumbuhan serta konsentrasi hormon (estradiol, testosteron, dan kortisol). Hasil penelitian menunjukkan bahwa pemberian pakan yang diperkaya triptofan memberikan penurunan kejadian kanibal dan peningkatan sintasan benih ikan baung. Pemberian triptofan juga menurunkan kandungan estradiol tubuh, dan penurunan ini ada kaitannya dengan penurunan kejadian kanibalisme. Performa pertumbuhan benih ikan baung meningkat dengan pemberian pakan yang ditambahkan triptofan.  Hasil penelitian ini menunjukkan bahwa suplementasi 0,50–0,75% triptofan pada pakan efektif menurunkan kejadian kanibalisme pada benih ikan baung.The cannibal behavior of Asian redtail catfish (Hemibagrus nemurus) is a problem in the hatchery. One approach that has been used to control cannibalism in fish is the use of tryptophan. This study aimed to determine the effect of tryptophan on the incidence of cannibalism and the content of steroid hormones in Asian redtail catfish juveniles. The study was conducted using the fish with a body length of 4.98±0.14 cm reared in aquariums with a water volume of 20 L with a density of 3 fish per L. Fish were given commercial feed (40% protein) supplemented with tryptophan with different concentrations, namely without tryptophan supplementation (A), tryptophan supplementation 0.25% (B), tryptophan supplementation 0.5% (C), tryptophan supplementation 0.75% (D), and tryptophan supplementation 1% (E). Each treatment consisted of three replications. Feed were given four times a day at satiation level. Parameters observed were cannibal type, cannibal index, normal mortality, survival rate, growth performance, and hormone concentration (estradiol, testosterone, and cortisol). The results showed that giving tryptophan through feed decreased the incidence of cannibalism and increased the survival of Asian redtail catfish juveniles. The addition of tryptophan to the feed decreased the concentration of estradiol in the body of fish and it is associated with a decrease in the incidence of cannibalism, thereby improving survival.  Furthermore, the supplementation of tryptophan also increased growth performance. The results of this study showed that supplementation of 0.50-0.75% tryptophan in feed was effective in reducing the incidence of cannibals in Asian redtail catfish juveniles

    Effects of 11-KT and Prolactin on Gene Expression, Parental Care Behaviour and Immune Response in Male Bluegill Sunfish.

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    Parental care is very critical for reproduction in species that provide it. Hormones such as prolactin and androgens play a crucial role in parenting and reproductive behaviours. In mammals and birds, prolactin’s role in parental care is well-established; it stimulates milk production and stimulates attachment to newborns by its release in the preoptic area of the hypothalamus (POA), among other functions. Androgens, on the other hand, are commonly associated with male secondary sex characteristics, territoriality, and aggressiveness in mammals and birds. There are similar reports of prolactin and androgen effects in fish, but there are fewer studies. I investigated if an androgen and prolactin have any similar effect on a paternal fish. Bluegill sunfish (Lepomis macrochirus) parental males build nests and wait for females to visit and lay eggs. The males exhibit aggressive behaviours toward any fish that comes close to the nest rim and also provide nurturing behaviours. In order to test the behavioural effects of androgens and prolactin, I artificially manipulated hormone concentrations using silastic implants: an androgen (11-ketotestosterone [11-KT]), an androgen antagonist (flutamide), prolactin, a prolactin-release inhibitor (bromocriptine), or castor oil (placebo). I found that prolactin increased the number of nurturing behaviours such as fanning the eggs, and 11-KT increased aggressive behaviours such as biting a nest intruder. I also found that there was a trade-off between these behaviours. My results support the behavioural effects of both hormones in fish. In order to test how the hypothalamus is involved in these reproductive behaviours, I also analyzed gene expression in the mesencephalon and diencephalon on a subset of these fish (control, 11-KT and prolactin), but there were no differences between the treatments. I discuss the possible reasons for obtaining a null result. It is possible that these two areas of the brain do not respond differentially to 11-KT and prolactin. Finally, I addressed the immunocompetence handicap hypothesis (ICHH), which posits a trade-off between aggressive behaviours, and thus androgen concentration, and the immune response. My results in bluegill do not support the ICHH, as there was no decrease in any measured immune responses to the androgen (11-KT). I also found that prolactin did not increase the immune response as it does in some other fish, birds and mammals. This work adds bluegill to the group of fish species in which prolactin and 11-KT have an effect on behaviours and weakens support for the ICHH, at least in fish

    Mutation of brain aromatase disrupts spawning behavior and reproductive health in female zebrafish

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    Aromatase (Cyp19a1) is the steroidogenic enzyme that converts androgens into bioactive estrogens, and hence is in a pivotal position to mediate reproduction and sexual behavior. In teleosts, there are two aromatase paralogs: cyp19a1a that is highly expressed in granulosa and Leydig cells in the gonads with critical function in sexual differentiation of the ovary, and cyp19a1b that is highly expressed in radial glial cells in the brain with unknown roles in reproduction. Cyp19a1-/- mutant zebrafish lines were used to investigate the importance of the cyp19a1 paralogs for spawning behavior and offspring survival and early development. Mutation of cyp19a1b was found to increase the latency to the first oviposition in females. Mutation of cyp19a1b in females also increased the number of eggs spawned; however, significantly more progeny died during early development resulting in no net increase in female fecundity. This finding suggests a higher metabolic cost of reproduction in cyp19a1b-/- mutant females. In males, the combined mutation of both cyp19a1 paralogs resulted in significantly lower progeny survival rates, indicating a critical function of cyp19a1 during early larval development. These data establish the specific importance of cyp19a1b for female spawning behavior and the importance of the cyp19a1 paralogs for early larval survival

    EVALUASI TEPUNG KEDELAI SEBAGAI SUMBER FITOESTROGEN DALAM PAKAN TERHADAP TINGKAT KANIBALISME BENIH IKAN LELE (Clarias sp.)

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    Beberapa upaya yang dilakukan untuk menanggulangi adanya kanibalisme pada ikan adalah dengan pemberian hormon sintesis estradiol-17β dan pemberian asam amino triptofan (bahan baku biosintesis serotonin) dalam pakan. Tujuan penelitian ini adalah untuk mengevaluasi pengaruh pemberian tepung kedelai terhadap tingkat kanibalisme benih ikan lele. Tiga dosis perlakuan penambahan tepung kedelai yaitu: 0 (Kontrol), 50 (TK50), dan 100 g kg-1 pakan (TK100). Terdapat dua perlakuan kontrol yaitu penambahan hormon menggunakan 17α-metiltestosteron 30 mg kg-1 pakan (MT) dan estradiol-17β 50 mg kg-1 pakan (E2). Penelitian ini menggunakan benih ikan lele berukuran 2,90 ± 0,41 cm dengan padat tebar 2000 ekor m-2. Pemeliharaan dilakukan selama 30 hari dengan pemberian pakan dilakukan tiga kali sehari (07.00, 12.00, dan 18.00). Metode yang digunakan dalam penelitian ini adalah rancangan acak lengkap dengan menggunakan lima perlakuan yang masing masing diulang sebanyak tiga kali. Hasil dari penelitian ini menunjukkan bahwa penambahan TK100 pada pakan dapat meningkatkan tingkat kelangsungan hidup, menekan adanya kanibalisme serta ikan yang berpotensi kanibal (P<0,05). Hasil dari kinerja pertumbuhan menunjukkan bahwa nilai laju bobot mutlak, laju panjang mutlak, laju panjang spesifik, dan koefisien keragaman panjang memiliki hasil yang berbeda nyata antarperlakuan (P<0,05) dan perlakuan laju bobot spesifik tidak berbeda nyata (P>0,05). Penambahan tepung kedelai dalam pakan mampu menekan adanya kanibalisme pada benih ikan lele sebesar 21,21%. Penurunan kanibalisme tersebut sejalan dengan adanya peningkatan kelangsungan hidup pada benih. Suplementasi tepung kedelai dalam pakan dapat menjadi alternatif solusi untuk penurunan tingkat kanibalisme pada pemeliharaan benih ikan lele.Several attempts have been made to reduce cannibalism in fish by supplementing the synthetic hormone estradiol-17β and amino acid tryptophan (raw material for serotonin biosynthesis) in feed. This study aimed to evaluate the effect of soybean meal on the level of cannibalism of catfish fingerlings. Three treatment doses of the supplementation of soybean meal were 0 (Control), 50 (TK50), and 100 g kg-1 feed (TK100). There were two control treatments, with the addition of hormones using 17α-methyltestosterone 30 mg kg-1 feed (MT) and estradiol-17β 50 mg kg-1 feed (E2). This study used catfish fingerlings measuring 2.90 ± 0.41 cm with a stocking density of 2000 m-2. The experiment was conducted for 30 days, thrice daily feeding (07.00, 12.00, and 18.00). The experiment was arranged in a completely randomized design using five treatments with triplicates. The results show that TK100 produced an increased survival rate and suppressed cannibalism level and potentially cannibalistic fish (P<0.05). The growth performance results show that the total weight rate, relative length rate, specific length rate, and length variation coefficient of catfish fingerlings were significantly different among the treatments (P<0.05). However,  the specific weight rate of catfish fish fingerlings was not significantly different among the treatments (P>0.05). The supplementation of soybean meal in feed suppresses cannibalism in the catfish seeds by 21.21%. The decrease in cannibalism was strongly correlated with the increase in the fingerlings’ survival rate. Supplementing soybean meal in feed can be an alternative solution to reduce cannibalism in catfish seed rearing

    Aspectos moleculares da diferenciação sexual em tambaqui (Colossoma macropomum): identificação de vias não convencionais em uma espécie neotropical.

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    Os peixes exibem uma grande variedade de mecanismos de determinação sexual e diferenciação sexual, que são tópicos de grande interesse científico e também relevância para o setor produtivo, quando a exploração de um sexo é mais vantajosa em espécies de importância econômica. O tambaqui Colossoma macropomum é uma espécie neotropical de destaque na aquicultura nativa brasileira, e seu mecanismo genético de determinação sexual ainda não foi propriamente identificado e caracterizado, apesar dos esforços utilizando-se de tecnologias ômicas como sequenciamento do genoma de machos e fêmeas, e também transcriptomas de juvenis durante a fase sexualmente indiferenciada. Buscando ampliar os conhecimentos científicos sobre os mecanismos envolvidos no processo de diferenciação sexual do tambaqui, esta tese teve como principal objetivo identificar e avaliar, por análises in silico e in vivo, os mecanismos moleculares envolvidos neste processo, principalmente os relacionados a hormônios esteróides e seus precursores, bem como os ácidos graxos.Tese (Doutorado em Ciência Animal e Recursos Pesqueiros) - Universidade Federal do Amazonas, Manaus

    Phylogenomic and expression analysis of Colossoma macropomum cyp19a1a and cyp19a1b and their non-classical role in tambaqui sex differentiation.

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    The genes coding for Cytochrome P450 aromatase (cyp19a1a and cyp19a1b) and estrogen (E2) receptors (esr1, esr2a and esr2b) play a conserved role in ovarian differentiation and development among teleosts. Classically, the "gonad form" of aromatase, coded by the cyp19a1a, is responsible for the ovarian differentiation in genetic females via ligation and activation of the Esr, which mediates the endocrine and exocrine signaling to allow or block the establishment of the feminine phenotype. However, in neotropical species, studies on the molecular and endocrine processes involved in gonad differentiation as well as on the effects of sex modulators are recent and scarce. In this study, we combined in silico analysis, real-time quantitative PCR (qPCR) assay and quantification of E2 plasma levels of differentiating tambaqui (Colossoma macropomum) to unveil the roles of the paralogs cypa19a1a and cyp19a1b during sex differentiation
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