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Department of Animal Sciences
The Robert H. Smith Faculty
of Agricultural, Food & Environment

The Hebrew University of Jerusalem.

Herzl 229, Rehovot 7610001, Israel
Phone: +972-(0)8-9489119;
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Lim, C. H. ; Soga, T. ; Levavi-Sivan, B. ; Parhar, I. S. Chronic Social Defeat Stress Up-Regulates Spexin in the Brain of Nile Tilapia (Oreochromis niloticus). SCIENTIFIC REPORTS 2020, 10.Abstract
Spexin (SPX), a neuropeptide evolutionarily conserved from fish to mammals, is widely distributed in the brain and peripheral tissues and associated with various physiological functions. Recently SPX has been suggested to be involved in neurological mechanism of stress. The current study investigates the involvement of SPX in chronic social defeat stress, using male teleost, the Nile tilapia (Oreochromis niloticus) as an animal model due to its distinct social hierarchy of dominant and subordinate relationship. The tilapia genome has SPX1a and SPX1b but has no SPX2. In the Nile tilapia, we localized SPX1a and SPX1b in the brain using in-situ hybridization. Next, using qPCR we examined gene expression of SPX1a and SPX1b in chronically stress (socially defeated) fish. SPX1a expressing cells were localized in the semicircular torus of the midbrain region and SPX1b expressing cells in the telencephalon. Chronically stress fish showed elevated plasma cortisol levels; with an upregulation of SPX1a and SPX1b gene expression in the brain compared to non-stress (control) fish. Since social defeat is a source of stress, the upregulated SPX mRNA levels during social defeat suggests SPX as a potentially inhibitory neuropeptide capable of causing detrimental changes in behaviour and physiology.
Etzion, T. ; Zmora, N. ; Zohar, Y. ; Levavi-Sivan, B. ; Golan, M. ; Gothilf, Y. Ectopic over expression of kiss1 may compensate for the loss of kiss2. GENERAL AND COMPARATIVE ENDOCRINOLOGY 2020, 295.Abstract
Kisspeptin (KISS) is a neuropeptide which plays a central role in the regulation of the hypothalamic-pituitary-gonadal axis, and is essential for sexual maturation and fertility in mammals. Unlike mammals, which possess only one KISS gene, two paralogous genes, kiss1 and kiss2, have been identified in zebrafish and other non-mammalian vertebrates. Previous studies suggest that Kiss2, but not Kiss1, is the reproduction relevant form amongst the two. To better understand the role of each of these isoforms in reproduction, a loss of function approach was applied. Two genetic manipulation techniques-clustered regularly interspaced short palindromic repeats (CRISPR) and transcription activator-like effector nucleases (TALEN)-were used to generate kiss1 and kiss2 knockout (KO) zebrafish lines, respectively. Examination of these KO lines showed that reproductive capability was not impaired, confirming earlier observations. Further analysis revealed that KO of kiss2 caused a significant increase in expression levels of kiss1, kiss2r and tac3a, while KO of kiss1 had no effect on the expression of any of the examined genes. In situ hybridization analysis revealed that kiss1 mRNA is expressed only in the habenula in wild type brains, while in kiss2 KO fish, kiss1 mRNA-expressing cells were identified also in the ventral telencephalon, the ventral part of the entopeduncular nucleus, and the dorsal and ventral hypothalamus. Interestingly, these regions are known to express kiss2r, and the ventral hypothalamus normally expresses kiss2. These results suggest that a compensatory mechanism, involving ectopic kiss1 expression, takes place in the kiss2 KO fish, which may substitute for Kiss2 activity.
Xu, P. ; David, L. ; Martinez, P. ; Yue, G. H. Editorial: Genetic Dissection of Important Traits in Aquaculture: Genome-Scale Tools Development, Trait Localization and Regulatory Mechanism Exploration. FRONTIERS IN GENETICS 2020, 11.
Moles, G. ; Hausken, K. ; Carrillo, M. ; Zanuy, S. ; Levavi-Sivan, B. ; Gomez, A. Generation and use of recombinant gonadotropins in fish. GENERAL AND COMPARATIVE ENDOCRINOLOGY 2020, 299.Abstract
Understanding the differential roles of the pituitary gonadotropins Fsh and Lh in gonad maturation is crucial for a successful manipulation of the reproductive process in fish, and requires species-specific tools and appropriate active hormones. With the increasing availability of fish cDNAs coding for gonadotropin subunits, the production of recombinant hormones in heterologous systems has gradually substituted the approach of isolating native hormones. These recombinant hormones can be continually produced without depending on the fish as starting material and no cross-contamination with other pituitary glycoproteins is assured. Recombinant gonadotropins should be produced in eukaryotic cells, which have glycosylation capacity, but this post-translational modification varies greatly depending on the cell system, influencing hormone activity and stability. The production of recombinant gonadotropin beta-subunits to be used as antigens for antibody production has allowed the development of immunoassays for quantification of gonadotropins in some fish species. The administration in vivo of dimeric homologous recombinant gonadotropins has been used in basic studies and as a biotechnological approach to induce gametogenesis. In addition, gene-based therapies using somatic transfer of the gonadotropin genes have been tested as an alternative for hormone delivery in vivo. In summary, the use of homologous hormonal treatments can open new strategies in aquaculture to solve reproductive problems or develop out-of-season breeding programs.
Neori, A. ; Bronfman, Y. ; van Rijn, J. ; Guttman, L. ; Krupnik, N. ; Shpigel, M. ; Samocha, T. M. ; Davis, D. A. ; Qiu, X. ; Abelin, P. ; et al. The suitability of Ulva fasciata, Ulva compressa, and Hypnea musciformis for production in an outdoor spray cultivation system, with respect to biomass yield and protein content. JOURNAL OF APPLIED PHYCOLOGY 2020, 32, 3183-3197.Abstract
Land-based seaweed ponds can produce 500-700 t of fresh weight (FW) ha(-1) year(-1), but their profitability can be cut by the cost of pond construction, including ground leveling, infrastructure cost, and water agitation. A potentially cost-effective, land-based seaweed culture approach where seaweed grow on substrates by spray culture has been examined. We measured the yield and biomass quality of three intertidal cultivable seaweeds, Ulva fasciata, Ulva compressa, and Hypnea musciformis, in spray (known elsewhere also as film or drip culture) and pond culture approaches, varying surface inclination and nutrient loading. These technical details are necessary for the evaluation of the approach and for upscaling. The best yield (up to 84 g FW m(-2) day(-1), 44-84% of yield in ponds) and quality (protein content and additional parameters) of spray-grown U. fasciata was obtained on 6 degrees-inclined trays with highly fertilized water. The highest protein content (24.5%), but with reduced yield, was obtained on 80 degrees-inclined trays. H. musciformis and U. compressa, apparently thanks to their stringy morphologies, yielded in spray culture up to 286 g FW m(-2) day(-1) and 172 g FW m(-2) day(-1), respectively. The overall quality and resilience of spray-grown algae profited from nutrient enrichment, and the best yields were achieved with enrichment of 10 g N and 1 g P m(-2) day(-1) in H. musciformis and 15 g N and 1.5 g P m(-2) day(-1) in both Ulva species. Biomass growth occurred in layers, which visibly differed in color and consistency. A thin bleached top thalli layer protected the biomass below from dehydration and bleaching and allowed there a high photosynthetic rate. A spray culture of Ulva sp. on seawater-sprayed cement tiles, with minimal maintenance, yielded up to 50 g FW m(-2) of tile day(-1). Economically, spray culture appears to be particularly suitable to the stringy algae.
Thoennes, M. ; Vogt, M. ; Steinborn, K. ; Hausken, K. N. ; Levavi-Sivan, B. ; Froschauer, A. ; Pfennig, F. Anex vivoApproach to Study Hormonal Control of Spermatogenesis in the TeleostOreochromis niloticus. FRONTIERS IN ENDOCRINOLOGY 2020, 11.Abstract
As the male reproductive organ, the main task of the testis is the production of fertile, haploid spermatozoa. This process, named spermatogenesis, starts with spermatogonial stem cells, which undergo a species-specific number of mitotic divisions until starting meiosis and further morphological maturation. The pituitary gonadotropins, luteinizing hormone, and follicle stimulating hormone, are indispensable for vertebrate spermatogenesis, but we are still far from fully understanding the complex regulatory networks involved in this process. Therefore, we developed anex vivotestis cultivation system which allows evaluating the occurring changes in histology and gene expression. The experimental circulatory flow-through setup described in this work provides the possibility to study the function of the male tilapia gonads on a cellular and transcriptional level for at least 7 days. After 1 week of culture, tilapia testis slices kept their structure and all stages of spermatogenesis could be detected histologically. Without pituitary extract (tilPE) however, fibrotic structures appeared, whereas addition of tilPE preserved spermatogenic cysts and somatic interstitium completely. We could show that tilPE has a stimulatory effect on spermatogonia proliferation in our culture system. In the presence of tilPE or hCG, the gene expression of steroidogenesis related genes (cyp11b2andstAR2) were notably increased. Other testicular genes likepiwil1, amh, ordmrt1were not expressed differentially in the presence or absence of gonadotropins or gonadotropin containing tilPE. We established a suitable system for studying tilapia spermatogenesisex vivowith promise for future applications.
Barzilai-Tutsch, H. ; Genin, O. ; Pines, M. ; Halevy, O. Early pathological signs in young dysf(-/-) mice are improved by halofuginone. NEUROMUSCULAR DISORDERS 2020, 30, 472-482.Abstract
Dysferlinopathies are a non-lethal group of late-onset muscular dystrophies. Here, we evaluated the fusion ability of primary myoblasts from young dysf(-/-) mice and the muscle histopathology prior to, and during early stages of disease onset. The ability of primary myoblasts of 5-week-old dysf(-/-) mice to form large myotubes was delayed compared to their wild-type counterparts, as evaluated by scanning electron microscopy. However, their fusion activity, as reflected by the presence of actin filaments connecting several cells, was enhanced by the antifibrotic drug halofuginone. Early dystrophic signs were already apparent in 4-week-old dysf(-/-) mice; their collagen level was double that in wild-type mice and continued to rise until 5 months of age. Continuous treatment with halofuginone from 4 weeks to 5 months of age reduced muscle fibrosis in a phosphorylated-Smad3 inhibition-related manner. Halofuginone also enhanced myofiber hypertrophy, reduced the percentage of centrally nucleated myofibers, and increased muscle performance. Together, the data suggest an inhibitory effect of halofuginone on the muscle histopathology at very early stages of dysferlinopathy, and enhancement of muscle performance. These results offer new opportunities for early pharmaceutical treatment in dysferlinopathies with favorable outcomes at later stages of life. (C) 2020 Elsevier B.V. All rights reserved.
Arav, A. ; Barak, Y. ; Komsky-Elbaz, A. ; Reches, D. ; Kalo, D. ; Roth, Z. ; Natan, Y. ; Patrizio, P. Easy, efficient and safe sperm separation for IUI and IVF. HUMAN REPRODUCTION 2020, 35, 147-148.
Atre, I. ; Mizrahi, N. ; Yebra-Pimentel, E. S. ; Hausken, K. ; Yom-Din, S. ; Hurvitz, A. ; Dirks, R. ; Degani, G. ; Levavi-Sivan, B. Molecular characterization of two Russian sturgeon gonadotropin receptors: Cloning, expression analysis, and functional activity. GENERAL AND COMPARATIVE ENDOCRINOLOGY 2020, 298.Abstract
Sturgeons are being used in aquaculture because wild populations are now endangered due to overfishing for caviar. A challenge in working with sturgeon as an aquacultured species is its long and slow reproductive development. Reproduction is a hormonally regulated process that involves hierarchical signaling between the brain, pituitary gland, and gonads. In an effort to better understand the hormonal regulation of sturgeon reproduction, we have cloned the Russian sturgeon (st), Acipenser gueldenstaedtii, luteinizing hormone receptor (stLHR) and follicle stimulating hormone receptor (stFSHR) and measured their expression from previtellogenic to mature ovarian follicles. Sturgeon LHR and FSHR expression was elevated in early-vitellogenic and mature follicles compared with pre-vitellogenic and mid-vitellogenic follicles, and only LHR expression increased during late-vitellogenesis. Recombinant sturgeon FSH and LH both activated sturgeon LHR and FSHR in a cAMP reporter assay. Further molecular characterization of these receptors was accomplished by in silica modeling and cAMP reporter assays using heterologous recombinant gonadotropins from human and piscine species. There was no apparent trend in heterologous LH and/or FSH activation of the sturgeon LHR or FSHR. These data suggest that permissive activation of LHR and FSHR are a consequence of some yet undetermined biological characteristic(s) of different piscine species.
Argov-Argaman, N. ; Cohen-Zinder, M. ; Leibovich, H. ; Yishay, M. ; Eitam, H. ; Agmon, R. ; Hadaya, O. ; Mesilati-Stahy, R. ; Miron, J. ; Shabtay, A. Dietary pomegranate peel improves milk quality of lactating ewes: Emphasis on milk fat globule membrane properties and antioxidative traits. FOOD CHEMISTRY 2020, 313.Abstract
Concentrated pomegranate peel extract (CPE) was supplemented to ewes, and milk yield and fat content-fatty acid (FA) and phospholipid (PL) composition-were monitored. CPE-fed ewes had higher milk yield, and fat, protein and lactose contents than controls. Milk PL content-20% higher in the CPE-supplemented group-was regulated by treatment and not by total fat content; milk phosphatidylethanolamine and phosphatidylcholine increased by 22 and 26%, respectively, in CPE-supplemented vs. control ewes. Milk saturated FA concentration was higher, and total polyunsaturated and monounsaturated FA content lower in the CPE vs. control group, regardless of milk total fat content. CPE supplementation increased milk antioxidant capacity, suggesting antioxidant transfer from dietary source to milk, increasing stability and nutritive value. Our study provides first evidence for milk quality improvement in terms of antioxidants and PL enrichment without compromising total milk fat, suggesting strategies to improve dairy animals' milk composition without compromising total production.
Kalo, D. ; Komsky-Elbaz, A. ; Roth, Z. Effect of environmental contaminants, alone or in a mixture, on the quality of bovine spermatozoa. ANIMAL REPRODUCTION SCIENCE 2020, 220.
Gumulka, M. ; Hrabia, A. ; Avital-Cohen, N. ; Andres, K. ; Rozenboim, I. The effect of parachlorophenylalanine treatment on the activity of gonadal and lactotrophic axes in native Polish crested chickens stimulated to broodiness. POULTRY SCIENCE 2020, 99, 2708-2717.Abstract
Brooding behavior, a common characteristic of native breeds of the domestic chicken, is marked by elevated prolactin (PRL) levels, which is necessary for incubation and connected with changes in hypothalamic- pituitary-gonadal axis activity. Evidence indicates the serotoninergic system is a potent modulator of PRL secretion. The objective of this study is to investigate whether blocking serotonin synthesis with parachlorophenylalanine (PCPA) prevents incubation behavior in native Polish crested chickens. In addition, we examined the effect of PCPA on the gene expression of the gonadal and lactotrophic axes. Birds were stimulated to broodiness by artificial eggs in nests. At 34 wk of age (April: spring period), the hens were divided into 2 groups (14 hens in each group): control and PCPA-treated (50 mg/kg BW) group. After 5 wk of treatment, the artificial eggs were removed from the nests. Egg production, incubation activity, and levels of plasma ovarian steroids progesterone (P4), testosterone (T), estradiol (E2), and PRL were examined. At the end of the experiment (45 wk of age, June: summer period), ovarian characteristics and mRNA gene expression of gonadal (gonadotropin-releasing hormone [GnRH] I, luteinizing hormone [LH] ss, follicle-stimulating hormone [FSH] ss) and lactotrophic (vasoactive intestinal peptide [VIP], PRL) axes were measured by quantitative real-time PCR. Incubation activity was observed in the hens of both groups but with lower frequency in PCPA-treated birds. Moreover, the PCPA group had a higher cumulative egg production than the controls. During the first six and 8 wk of the experiment, levels of P4 and E2, respectively, were similar in both groups, but all concentrations increased in the PCPA-treated hens after this period. In addition, increased GnRH-I, LH ss, and FSH ss and decreased VIP mRNA expression was observed in the PCPA group compared with the controls. There were no differences in PRL mRNA expression, the PRL level, and ovarian morphometry between the 2 groups. These results indicate that blockage of serotonin synthesis by PCPA does not effectively prevent incubation in native Polish crested chickens. However, treatment with PCPA increased gonadal axis activity and improved reproductive performance.
Yablonka-Reuveni, Z. ; Stockdale, F. ; Nudel, U. ; Israeli, D. ; Blau, H. M. ; Shainberg, A. ; Neuman, S. ; Kessler-Icekson, G. ; Krull, E. M. ; Paterson, B. ; et al. Farewell to Professor David Yaffe - A pillar of the myogenesis field. EUROPEAN JOURNAL OF TRANSLATIONAL MYOLOGY 2020, 30.Abstract
It is with great sadness that we have learned about the passing of Professor David Yaffe (1929-2020, Israel). Yehi Zichro Baruch - May his memory be a blessing. David was a man of family, science and nature. A native of Israel, David grew up in the historic years that preceded the birth of the State of Israel. He was a member of the group that established Kibbutz Revivim in the Negev desert, and in 1948 participated in Israel's War of Independence. David and Ruth eventually joined Kibbutz Givat Brenner by Rehovot, permitting David to be both a kibbutz member and a life-long researcher at the Weizmann Institute of Science, where David received his PhD in 1959. David returned to the Institute after his postdoc at Stanford. Here, after several years of researching a number of tissues as models for studying the process of differentiation, David entered the myogenesis field and stayed with it to his last day. With his dedication to the field of myogenesis and his commitment to furthering the understanding of the People and the Land of Israel throughout the international scientific community, David organized the first ever myogenesis meeting that took place in Shoresh, Israel in 1975. This was followed by the 1980 myogenesis meeting at the same place and many more outstanding meetings, all of which brought together myogenesis, nature and scenery. Herein, through the preparation and publication of this current manuscript, we are meeting once again at a ``David Yaffe myogenesis meeting''. Some of us have been members of the Yaffe lab, some of us have known David as his national and international colleagues in the myology field. One of our contributors has also known (and communicates here) about David Yaffe's earlier years as a kibbutznick in the Negev. Our collective reflections are a tribute to Professor David Yaffe. We are fortunate that the European Journal of Translational Myology has provided us with tremendous input and a platform for holding this 2020 distance meeting ``Farwell to Professor David Yaffe - A Pillar of the Myogenesis Field''.
Hadaya, O. ; Landau, S. Y. ; Glasser, T. ; Muklada, H. ; Deutch, T. ; Shemesh, M. ; Argov-Argaman, N. Producing pasture-like milk from goats in confinement. LIVESTOCK SCIENCE 2020, 236.Abstract
We have previously shown that grazing in East-Mediterranean brushlands is associated with improved milk quality. However, grazing exposes animals to predation, heat stress, and parasites, and imposes labor constraint. In order to verify the hypothesis that feeding the tannin-rich browse species lentisk (Pistacia lentiscus L.) to confined dairy goats could serve as proxy to grazing in improving milk composition, 30 Damascus goats were assigned to 3 treatments for 3 weeks: goats were grazing for 4 h daily in Mediterranean brushland (treatment P) or were fed indoors with vetch hay without (H), or with (HPIS) lentisk foliage. Milk yield and dry matter intake were not affected by treatment. HPIS milk was richer in protein and milk-fat content than H milk. H milk had highest urea concentration, smallest milk-fat globules and highest phospholipid content (milk-fat basis). Curd firmness was 39 and 50% higher in the HPIS group, compared with P and H, respectively. HPIS milk had 39 and 90% higher n-3 fatty acids concentration than P and H, respectively. This study suggests that access to P. lentiscus intensifies the effect of grazing in Mediterranean woodland on milk composition. Thus, we present a nutritional strategy that not only retains the exceptional nutritional values and productivity of pasture feeding, but also participates in a profitable and sustainable agriculture with an emphasis on intensive ruminant animal-production systems.
Cohen, Y. ; Hausken, K. ; Bonfil, Y. ; Gutnick, M. ; Levavi-Sivan, B. Spexin and a Novel Cichlid-Specific Spexin Paralog Both Inhibit FSH and LH Through a Specific Galanin Receptor (Galr2b) in Tilapia. FRONTIERS IN ENDOCRINOLOGY 2020, 11.Abstract
Spexin (SPX) is a 14 amino acid peptide hormone that has pleiotropic functions across vertebrates, one of which is involvement in the brain-pituitary-gonad axis of fish. SPX(1) has been identified in each class of vertebrates, and a second SPX (named SPX2) has been found in some non-mammalian species. We have cloned two spexin paralogs, designated as Spx1a and Spx1b, from Nile tilapia (Oreochromis niloticus) that have varying tissue distribution patterns. Spx1b is a novel peptide only identified in cichlid fish, and is more closely related to Spx1 than Spx2 homologs as supported by phylogenetic, synteny, and functional analyses. Kisspeptin, Spx, and galanin (Gal) peptides and their corresponding kiss receptors and Gal receptors (Galrs), respectively, are evolutionarily related. Cloning of six tilapia Galrs (Galr1a, Galr1b, Galr2a, Galr2b, Galr type 1, and Galr type 2) and subsequent in vitro second-messenger reporter assays for G alpha(s), G alpha(q), and G alpha(i) suggests that Gal and Spx activate Galr1a/Galr2a and Galr2b, respectively. A decrease in plasma follicle stimulating hormone and luteinizing hormone concentrations was observed with injections of Spx1a or Spx1b in vivo. Additionally, application of Spx1a and Spx1b to pituitary slices decreased the firing rate of LH cells, suggesting that the peptides can act directly at the level of the pituitary. These data collectively suggest an inhibitory mechanism of action against the secretion of gonadotropins for a traditional and a novel spexin paralog in cichlid species.
Szymanska, M. ; Manthe, S. ; Shrestha, K. ; Girsh, E. ; Harlev, A. ; Meidan, R. The cAMP pathway promotes sirtuin-1 expression in human granulosa-lutein cells. REPRODUCTIVE BIOLOGY 2020, 20, 273-281.Abstract
Sirtuin-1 (SIRT1), a NAD+-dependent deacetylase, is present in the ovarian granulosa cells (GCs) of various species. This study examined the regulation of SIRT1 expression in human granulosa-lutein cells (hGLCs). Two different, structurally unrelated SIRT1 activators, SRT2104 and resveratrol, dose- and time-dependently enhanced SIRT1 (similar to 2- and 1.5-fold increase at 50 mu mol/L for mRNA and protein levels, respectively), whereas EX-527, an inhibitor of SIRT1 deacetylase activity, significantly suppressed SIRT1 protein induced by these activators. Transfecting cells with SIRT1 siRNA molecules efficiently silenced SIRT1 (similar to 70 % decrease in 48 h post-transfection). Furthermore, the stimulatory effects of SRT2104 on SIRT1 expression observed in non-transfected or in scrambled siRNA-transfected cells were diminished with SIRT1 silencing. The findings described above imply that SIRT1 autoregulates its own expression. Interestingly, SRT2104 elevated cAMP accumulation (1.4-fold) in the culture media of hGLCs which was further augmented in the presence of hCG (2.2-fold); these effects were evident after 12 h of incubation. This additive effect of hCG and SRT2104 on cAMP accumulation may explain the incremental outcome observed on SIRT1 expression (similar to 3-fold increase from basal level and similar to 1.6-fold stimulation for each compound alone) with these two compounds. SIRT1 knockdown diminished SIRT1 induced by forskolin, providing additional evidence that cAMP promotes SIRT1. These findings imply that by activating adenylyl cyclase (hCG or forskolin) and inhibiting phosphodiesterases (SIRT1 activators), these two signals converge to produce an incremental, positive feedback loop on SIRT1 expression. Such a mechanism highlights the importance of maintaining high SIRT1 levels in human luteinized GCs.
Wintner, O. ; Srebnik, N. ; Kalo, D. ; Roth, Z. ; Buxboim, A. In Situ Mechanical Characterization Predicts the Developmental Potential of Oocytes and Embryos. REPRODUCTIVE SCIENCES 2020, 27, 279A.
Halevy, O. Timing Is Everything-The High Sensitivity of Avian Satellite Cells to Thermal Conditions During Embryonic and Posthatch Periods. FRONTIERS IN PHYSIOLOGY 2020, 11.Abstract
Myofiber formation is essentially complete at hatch, but myofiber hypertrophy increases posthatch through the assimilation of satellite cell nuclei into myofibers. Satellite cell proliferation and differentiation occur during the early growth phase, which in meat-type poultry terminates at around 8 days posthatch. Thus, any factor that affects the accumulation of satellite cells during late-term embryogenesis or early posthatch will dictate long-term muscle growth. This review will focus on the intimate relationship between thermal conditions during chick embryogenesis and the early posthatch period, and satellite cell myogenesis and pectoralis growth and development. Satellite cells are highly sensitive to temperature changes, particularly when those changes occur during crucial periods of their myogenic activity. Therefore, timing, temperature, and duration of thermal treatments have a great impact on satellite cell activity and fate, affecting muscle development and growth in the long run. Short and mild thermal manipulations during embryogenesis or thermal conditioning in the early posthatch period promote myogenic cell proliferation and differentiation, and have long-term promotive effects on muscle growth. However, chronic heat stress during the first 2 weeks of life has adverse effects on these parameters and may lead to muscle myopathies.
Reicher, N. ; Epstein, T. ; Gravitz, D. ; Cahaner, A. ; Rademacher, M. ; Braun, U. ; Uni, Z. From broiler breeder hen feed to the egg and embryo: The molecular effects of guanidinoacetate supplementation on creatine transport and synthesis. POULTRY SCIENCE 2020, 99, 3574-3582.Abstract
Supplementation of broiler breeder hens with beneficial additives bears great potential for affecting nutrient deposition into the fertile egg. Guanidinoacetate (GAA) is the endogenous precursor of creatine that is used as a feed additive for improving cellular energy metabolism in animal nutrition. In the present study, we have investigated whether GAA supplementation in broiler breeder feed affects creatine deposition into the hatching egg and molecular mechanisms of creatine transport and synthesis within hens and their progeny. For this, broiler breeder hens of 47 wk of age were supplemented with 0.15% GAA for 15 wk, and samples from their tissues, hatching eggs and progeny were compared with those of control, nonsupplemented hens. A significant increase in creatine content was found within the yolk and albumen of hatching eggs obtained from the GAA group, compared with the control group. The GAA group exhibited a significant increased creatine transporter gene expression compared with the control group in their small intestines and oviduct. In GAA group progeny, a significant decrease in creatine transporter expression at embryonic day 19 and day of hatch was found, compared with control group progeny. At the day of hatch, creatine synthesis genes (arginine glycine amidinotransferase and guanidinoacetate N-methyltransferase) exhibited significant decrease in expression in the GAA group progeny compared with control group progeny. These results indicate that GAA supplementation in broiler breeder feed increases its absorbance and deposition into hatching eggs, subsequently affecting GAA and creatine absorbance and synthesis within broiler progeny.
Tadmor-Levi, R. ; David, L. ; Golani, D. Indication of cryptic taxa within the flat needlefish, Ablennes hians based on analysis of the cytochrome oxidase I region on a wide range of samples. MARINE BIOLOGY RESEARCH 2020, 16, 474-479.Abstract
We analysed the genetic structure with respect to geographic distribution of the flat needlefish, Ablennes hians, previously considered as having a circumtropical distribution. Cytochrome oxidase I (COI) barcode region sequences were constructed for a specimen from the Mediterranean, and a specimen from Japan. The sequences of the studied specimens were compared with 18 barcodes of this species from Barcode of Life Datasystems (BOLD). The results revealed that genetic distances between groups of specimens from different geographic regions can be as high as 10.9%, and in most comparisons were above the widely accepted threshold level of within-species variation. This suggests the occurrence of several cryptic taxa within the Ablennes hians complex.