Honors & Awards


  • Gruss Lipper Postdoctoral Fellowship for Biomedical Research, The EGL Charitable Foundation (2021-2023)
  • Rothschild Postdoctoral Fellowship, Yad Hanadiv Foundation (2021-2022)
  • Vaadia-BARD Postdoctoral Fellowship, US-Israel Binational Agricultural Research and Development Fund (2021-2022)
  • Stanford School of Medicine Dean's Postdoctoral Fellowship, Stanford School of Medicine (2021)
  • Emergency Postdoctoral Fellowships for Israeli Researchers in Israel, Israel Academy of Sciences and Humanities (2020-2022)

Professional Education


  • PhD, Ben-Gurion University of the Negev, Life Sciences - Physiology and Endocrinology (2019)
  • MSc (Summa Cum Laude), Ben-Gurion University of the Negev, Life Sciences (2016)
  • BSc (Summa Cum Laude), Ben-Gurion University of the Negev, Marine Biology and Biotechnology (2014)

Stanford Advisors


Patents


  • Tom Levy, Rivka Manor, Amir Sagi. " Patent International Application No. PCT/IL2018/051046 Sex-linked genomic marker for crayfish and uses thereof", Sep 17, 2018

All Publications


  • Botryllus schlosseri as a Unique Colonial Chordate Model for the Study and Modulation of Innate Immune Activity. Marine drugs Goldstein, O., Mandujano-Tinoco, E. A., Levy, T., Talice, S., Raveh, T., Gershoni-Yahalom, O., Voskoboynik, A., Rosental, B. 2021; 19 (8)

    Abstract

    Understanding the mechanisms that sustain immunological nonreactivity is essential for maintaining tissue in syngeneic and allogeneic settings, such as transplantation and pregnancy tolerance. While most transplantation rejections occur due to the adaptive immune response, the proinflammatory response of innate immunity is necessary for the activation of adaptive immunity. Botryllus schlosseri, a colonial tunicate, which is the nearest invertebrate group to the vertebrates, is devoid of T- and B-cell-based adaptive immunity. It has unique characteristics that make it a valuable model system for studying innate immunity mechanisms: (i) a natural allogeneic transplantation phenomenon that results in either fusion or rejection; (ii) whole animal regeneration and noninflammatory resorption on a weekly basis; (iii) allogeneic resorption which is comparable to human chronic rejection. Recent studies in B. schlosseri have led to the recognition of a molecular and cellular framework underlying the innate immunity loss of tolerance to allogeneic tissues. Additionally, B. schlosseri was developed as a model for studying hematopoietic stem cell (HSC) transplantation, and it provides further insights into the similarities between the HSC niches of human and B. schlosseri. In this review, we discuss why studying the molecular and cellular pathways that direct successful innate immune tolerance in B. schlosseri can provide novel insights into and potential modulations of these immune processes in humans.

    View details for DOI 10.3390/md19080454

    View details for PubMedID 34436293

  • Two Homogametic Genotypes - One Crayfish: On the Consequences of Intersexuality. iScience Levy, T., Ventura, T., De Leo, G., Grinshpan, N., Abu Abayed, F. A., Manor, R., Savaya, A., Sklarz, M. Y., Chalifa-Caspi, V., Mishmar, D., Sagi, A. 2020; 23 (11): 101652

    Abstract

    In the Australian redclaw crayfish, Cherax quadricarinatus (WZ/ZZ system), intersexuals, although exhibiting both male and female gonopores, are functional males bearing a female genotype (WZ males). Therefore, the occurrence of the unusual homogametic WW females in nature is plausible. We developed W/Z genomic sex markers and used them to investigate the genotypic structure of experimental and native C.quadricarinatus populations in Australia. We discovered, for the first time, the natural occurrence of WW females in crustacean populations. By modeling population dynamics, we found that intersexuals contribute to the growth rate of crayfish populations in the short term. Given the vastly fragmented C.quadricarinatus habitat, which is characterized by drought-flood cycles, we speculate that intersexuals contribute to the fitness of this species since they lead to occasional increment in the population growth rate which potentially supports crayfish population restoration and establishment under extinction threats or colonization events.

    View details for DOI 10.1016/j.isci.2020.101652

    View details for PubMedID 33103088

  • From sporadic single genes to a broader transcriptomic approach: Insights into the formation of the biomineralized exoskeleton in decapod crustaceans JOURNAL OF STRUCTURAL BIOLOGY Shaked, S. A., Abehsera, S., Levy, T., Chalifa-Caspi, V., Sagi, A. 2020; 212 (2): 107612

    Abstract

    One fundamental character common to pancrustaceans (Crustacea and Hexapoda) is a mineralized rigid exoskeleton whose principal organic components are chitin and proteins. In contrast to traditional research in the field that has been devoted to the structural and physicochemical aspects of biomineralization, the present study explores transcriptomic aspects of biomineralization as a first step towards adding a complementary molecular layer to this field. The rigidity of the exoskeleton in pancrustaceans dictates essential molt cycles enabling morphological changes and growth. Thus, formation and mineralization of the exoskeleton are concomitant to the timeline of the molt cycle. Skeletal proteinaceous toolkit elements have been discovered in previous studies using innovative molt-related binary gene expression patterns derived from transcriptomic libraries representing the major stages comprising the molt cycle of the decapod crustacean Cherax quadricarinatus. Here, we revisited some prominent exoskeleton-related structural proteins encoding and, using the above molt-related binary pattern methodology, enlarged the transcriptomic database of C. quadricarinatus. The latter was done by establishing a new transcriptomic library of the cuticle forming epithelium and molar tooth at four different molt stages (i.e., inter-molt, early pre-molt, late pre-molt and post-molt) and incorporating it to a previous transcriptome derived from the gastroliths and mandible. The wider multigenic approach facilitated by the newly expanded transcriptomic database not only revisited single genes of the molecular toolkit, but also provided both scattered and specific information that broaden the overview of proteins and gene clusters which are involved in the construction and biomineralization of the exoskeleton in decapod crustaceans.

    View details for DOI 10.1016/j.jsb.2020.107612

    View details for Web of Science ID 000579373100009

    View details for PubMedID 32896659

  • The IAG-Switch and Further Transcriptomic Insights Into Sexual Differentiation of a Protandric Shrimp FRONTIERS IN MARINE SCIENCE Levy, T., Tamone, S. L., Manor, R., Aflalo, E. D., Sklarz, M. Y., Chalifa-Caspi, V., Sagi, A. 2020; 7
  • The "IAG-Switch"-A Key Controlling Element in Decapod Crustacean Sex Differentiation FRONTIERS IN ENDOCRINOLOGY Levy, T., Sagi, A. 2020; 11: 651

    Abstract

    The androgenic gland (AG)-a unique crustacean endocrine organ that secretes factors such as the insulin-like androgenic gland (IAG) hormone-is a key player in crustacean sex differentiation processes. IAG expression induces masculinization, while the absence of the AG or a deficiency in IAG expression results in feminization. Therefore, by virtue of its universal role as a master regulator of crustacean sexual development, the IAG hormone may be regarded as the sexual "IAG-switch." The switch functions within an endocrine axis governed by neuropeptides secreted from the eyestalks, and interacts downstream with specific insulin receptors at its target organs. In recent years, IAG hormones have been found-and sequenced-in dozens of decapod crustacean species, including crabs, prawns, crayfish and shrimps, bearing different types of reproductive strategies-from gonochorism, through hermaphroditism and intersexuality, to parthenogenesis. The IAG-switch has thus been the focus of efforts to manipulate sex developmental processes in crustaceans. Most sex manipulations were performed using AG ablation or knock-down of the IAG gene in males in order to sex reverse them into "neo-females," or using AG implantation/injecting AG extracts or cells into females to produce "neo-males." These manipulations have highlighted the striking crustacean sexual plasticity in different species and have permitted the manifestation of either maleness or femaleness without altering the genotype of the animals. Furthermore, these sex manipulations have not only facilitated fundamental studies of crustacean sexual mechanisms, but have also enabled the development of the first IAG-switch-based monosex population biotechnologies, primarily for aquaculture but also for pest control. Here, we review the crustacean IAG-switch, a unique crustacean endocrine mechanism, from the early discoveries of the AG and the IAG hormone to recent IAG-switch-based manipulations. Moreover, we discuss this unique early pancrustacean insulin-based sexual differentiation control mechanism in contrast to the extensively studied mechanisms in vertebrates, which are based on sex steroids.

    View details for DOI 10.3389/fendo.2020.00651

    View details for Web of Science ID 000574636700001

    View details for PubMedID 33013714

    View details for PubMedCentralID PMC7511715

  • Ovarian development pattern and vitellogenesis of ridgetail white prawn, Exopalaemon carinicauda CELL AND TISSUE RESEARCH Wang, L., Guo, Q., Levy, T., Chen, T., Wu, X. 2020; 382 (2): 367–79

    Abstract

    The ridgetail white prawn Exopalaemon carinicauda has the potential to be used as a model organism in crustacean research because it has a transparent body, available draft genome, and short life cycle. However, their ovarian development pattern remains unclear under laboratory culture conditions. This study investigated the changes of ovarian external feature, ovarian histology, gonadosomatic index (GSI), and hepatosomatic index (HSI), as well as the expression and localization of vitellogenin in the ovary and the hepatopancreas during the first ovarian development cycle of E. carinicauda under laboratory-reared condition. The results demonstrated that (1) the first ovarian development cycle of E. carinicauda could be divided into 5 different stages in which the ovary changes its color from white to yellow during the vitellogenesis process in parallel with increasing GSI. (2) After pubertal molt, most females reached ovarian stage II while the females reached stage V after premating molt. (3) During the ovarian development, GSI increased smoothly and HSI relatively stable during the period of stages I to IV, while GSI increased but HSI decreased significantly from stages IV to V. (4) In situ hybridization (ISH) revealed that EcVg was slightly expressed in the oocyte cytoplasm of previtellogenic oocytes. The positive signal was mainly detected in hepatopancreatic fibrillar cells, and a strong signal was found in the hepatopancreas at stage IV. Moreover, the expression level of EcVg-mRNA in the hepatopancreas is stage-specific, and the hepatopancreas contributes majority of vitellin precursor protein to support the ovarian development of E. carinicauda.

    View details for DOI 10.1007/s00441-020-03223-8

    View details for Web of Science ID 000540993700004

    View details for PubMedID 32556723

  • The IAG gene in the invasive crayfish Procambarus clarkii - towards sex manipulations for biocontrol and aquaculture MANAGEMENT OF BIOLOGICAL INVASIONS Savaya, A., De Leo, G., Aalto, E., Levy, T., Rosen, O., Manor, R., Aflalo, E. D., Tricarico, E., Sagi, A. 2020; 11 (2): 237–58
  • The protandric life history of the Northern spot shrimp Pandalus platyceros: molecular insights and implications for fishery management SCIENTIFIC REPORTS Levy, T., Tamone, S. L., Manor, R., Bower, E. D., Sagi, A. 2020; 10 (1): 1287

    Abstract

    The Northern spot shrimp, Pandalus platyceros, a protandric hermaphrodite of commercial importance in North America, is the primary target species for shrimp fisheries within Southeast Alaska. Fishery data obtained from the Alaska Department of Fish and Game indicate that spot shrimp populations have been declining significantly over the past 25 years. We collected spot shrimps in Southeast Alaska and measured reproductive-related morphological, gonadal and molecular changes during the entire life history. The appendix masculina, a major sexual morphological indicator, is indicative of the reproductive phase of the animal, lengthening during maturation from juvenile to the male phase and then gradually shortening throughout the transitional stages until its complete disappearance upon transformation to a female. This morphological change occurs in parallel with the degeneration of testicular tissue in the ovotestis and enhanced ovarian vitellogenesis. Moreover, we obtained the entire mRNA sequence of the yolk protein precursor, vitellogenin, and monitored its transcript levels throughout the entire shrimp life-cycle. Vitellogenin transcript levels in the hepatopancreas increased in the early transitional stage until reaching a peak prior to extruding eggs. Such transcriptomic analyses, coupled with a comprehensive description of the gonad, external sex characters and timing of the reproductive life history of spot shrimps contribute to a better understanding of the hermaphroditic reproduction process in the cold Southeast Alaskan waters. This knowledge can contribute to a revision of current conservation efforts to maintain wild populations sustainable for both commercial and ecological considerations.

    View details for DOI 10.1038/s41598-020-58262-6

    View details for Web of Science ID 000562860600010

    View details for PubMedID 31992795

    View details for PubMedCentralID PMC6987223

  • Three generations of prawns without the Z chromosome: Viable WW Macrobrachium rosenbergii all-female populations in polyculture with Oreochromis niloticus AQUACULTURE Molcho, J., Levy, T., Benet, A., Naor, A., Savaya, A., Manor, R., Abramov, A., Aflalo, E. D., Shechter, A., Sagi, A. 2020; 515
  • Production of WW males lacking the masculine Z chromosome and mining the Macrobrachium rosenbergii genome for sex-chromosomes SCIENTIFIC REPORTS Levy, T., Rosen, O., Manor, R., Dotan, S., Azulay, D., Abramov, A., Sklarz, M. Y., Chalifa-Caspi, V., Baruch, K., Shechter, A., Sagi, A. 2019; 9: 12408

    Abstract

    The cultivation of monosex populations is common in animal husbandry. However, preselecting the desired gender remains a major biotechnological and ethical challenge. To achieve an efficient biotechnology for all-female aquaculture in the economically important prawn (Macrobrachium rosenbergii), we achieved - for the first time - WW males using androgenic gland cells transplantation which caused full sex-reversal of WW females to functional males. Crossing the WW males with WW females yielded all-female progeny lacking the Z chromosome. We now have the ability to manipulate - by non-genomic means - all possible genotype combinations (ZZ, WZ and WW) to retain either male or female phenotypes and hence to produce monosex populations of either gender. This calls for a study of the genomic basis underlying this striking sexual plasticity, questioning the content of the W and Z chromosomes. Here, we report on the sequencing of a high-quality genome exhibiting distinguishable paternal and maternal sequences. This assembly covers ~ 87.5% of the genome and yielded a remarkable N50 value of ~ 20 × 106 bp. Genomic sex markers were used to initiate the identification and validation of parts of the W and Z chromosomes for the first time in arthropods.

    View details for DOI 10.1038/s41598-019-47509-6

    View details for Web of Science ID 000482709400019

    View details for PubMedID 31455815

    View details for PubMedCentralID PMC6712010

  • Sex Control in Cultured Decapod Crustaceans SEX CONTROL IN AQUACULTURE, VOLS I AND II Levy, T., Aflalo, E. D., Sagi, A., Wang, H. P., Piferrer, F., Chen, S. L. 2019: 691–704
  • The gene encoding the insulin-like androgenic gland hormone in an all-female parthenogenetic crayfish PLOS ONE Levy, T., Rosen, O., Simons, O., Alkalay, A., Sagi, A. 2017; 12 (12): e0189982

    Abstract

    Male sexual differentiation in crustaceans is controlled by the androgenic gland (AG), a unique male endocrine organ that, in decapods, is located at the base of the 5th pereiopod. In these animals, the insulin-like androgenic gland hormone (IAG) is the major factor secreted from the AG to induce masculinization and maintain male characteristics. It has, however, recently been proposed that this hormone also plays a role in growth and ovarian development in females. In this study, we tested such a possibility by searching for the IAG gene in the marbled crayfish, a parthenogenetic animal that reproduces asexually to form an all-female genetic clone. Based on the phylogenetic relationship between the marbled crayfish and Procambarus fallax, a gonochoristic species of the same North American Cambaridae family, we searched for the IAG gene in the marbled crayfish and then fully sequenced it. The open reading frame of the gene was found to be completely identical in the two species, and their introns shared over 94% identity. It was also found that, in addition to its expression at the base of the 5th pereiopod and in the testes of male P. fallax crayfish, IAG was expressed in the muscle tissue of P. fallax males and females and even of the parthenogenetic marbled crayfish. These findings provide new insight into possible functions of IAG, in addition to its role as a masculinization-inducing factor, and also constitute the basis for a discussion of the evolutionary relationship between the above two species.

    View details for DOI 10.1371/journal.pone.0189982

    View details for Web of Science ID 000418564200078

    View details for PubMedID 29261765

    View details for PubMedCentralID PMC5738133

  • All-female monosex culture in the freshwater prawn Macrobrachium rosenbergii - A comparative large-scale field study AQUACULTURE Levy, T., Rosen, O., Eilam, B., Azulay, D., Zohar, I., Aflalo, E. D., Benet, A., Naor, A., Shechter, A., Sagi, A. 2017; 479: 857–62
  • A Single Injection of Hypertrophied Androgenic Gland Cells Produces All-Female Aquaculture MARINE BIOTECHNOLOGY Levy, T., Rosen, O., Eilam, B., Azulay, D., Aflalo, E. D., Manor, R., Shechter, A., Sagi, A. 2016; 18 (5): 554–63

    Abstract

    Monosex culture, common in animal husbandry, enables gender-specific management. Here, production of all-female prawns (Macrobrachium rosenbergii) was achieved by a novel biotechnology comprising three steps: (a) A single injection of suspended hypertrophied androgenic gland cells caused fully functional sex reversal of females into "neo-males" bearing the WZ genotype; (b) crossing neo-males with normal females (WZ) yielded genomically validated WW females; and (c) WW females crossed with normal males (ZZ) yielded all-female progeny. This is the first sustainable biotechnology for large-scale all-female crustacean aquaculture. The approach is particularly suited to species in which females are superior to males and offers seedstock protection, thereby ensuring a quality seed supply. Our technology will thus revolutionize not only the structure of the crustacean aquaculture industry but can also be applied to other sectors. Finally, the production of viable and reproducible females lacking the Z chromosome questions its role, with respect to sexuality.

    View details for DOI 10.1007/s10126-016-9717-5

    View details for Web of Science ID 000388831000003

    View details for PubMedID 27650072

  • Identification and Characterization of an Insulin-Like Receptor Involved in Crustacean Reproduction ENDOCRINOLOGY Sharabi, O., Manor, R., Weil, S., Aflalo, E. D., Lezer, Y., Levy, T., Aizen, J., Ventura, T., Mather, P. B., Khalaila, I., Sagi, A. 2016; 157 (2): 928–41

    Abstract

    Sexual differentiation and maintenance of masculinity in crustaceans has been suggested as being regulated by a single androgenic gland (AG) insulin-like peptide (IAG). However, downstream elements involved in the signaling cascade remain unknown. Here we identified and characterized a gene encoding an insulin-like receptor in the prawn Macrobrachium rosenbergii (Mr-IR), the first such gene detected in a decapod crustacean. In mining for IRs and other insulin signaling-related genes, we constructed a comprehensive M. rosenbergii transcriptomic library from multiple sources. In parallel we sequenced the complete Mr-IR cDNA, confirmed in the wide transcriptomic library. Mr-IR expression was detected in most tissues in both males and females, including the AG and gonads. To study Mr-IR function, we performed long-term RNA interference (RNAi) silencing in young male prawns. Although having no effect on growth, Mr-IR silencing advanced the appearance of a male-specific secondary trait. The most noted effects of Mr-IR silencing were hypertrophy of the AG and the associated increased production of Mr-IAG, with an unusual abundance of immature sperm cells being seen in the distal sperm duct. A ligand blot assay using de novo recombinant Mr-IAG confirmed the existence of a ligand-receptor interaction. Whereas these results suggest a role for Mr-IR in the regulation of the AG, we did not see any sexual shift after silencing of Mr-IR, as occurred when the ligand-encoding Mr-IAG gene was silenced. This suggests that sexual differentiation in crustaceans involve more than a single Mr-IAG receptor, emphasizing the complexity of sexual differentiation and maintenance.

    View details for DOI 10.1210/en.2015-1391

    View details for Web of Science ID 000369965900043

    View details for PubMedID 26677879