Лукьянов Сергей Анатольевич

Научные интересы

Основные научные интересы С. А. Лукьянова лежат в области анализа структуры и функции геномов эукариот.

Премии и заслуги

С. А. Лукьянов является лауреатом премии Президиума РАН им. академика Ю. А. Овчинникова за выдающиеся работы в области физико-химической биологии и биотехнологии за 2006 год за работу «Флуоресцентные белки: поиск, исследование и применение в биотехнологии», премий Международной академической издательской компании «Наука» за лучшую публикацию в издаваемых ею журналах за 1996 и г., победителем конкурсов журнала Биоорганическая Химия на лучшую статью года за 1996, 1997 и г., лауреатом программы «Выдающиеся ученые, молодые доктора и кандидаты наук» и конкурса на присуждение Государственных научных стипендий для ученых.

Основные научные результаты

Методы, разработанные на основе открытого С. А. Лукьяновым эффекта селективной супрессии полимеразной цепной реакции, а также методы с использованием дуплекс-специфической нуклеазы, выделенной в лаборатории С. А. Лукьянова в сотрудничестве с лабораторией морской биохимии Тихоокеанского института биоорганической химии (зав. лабораторией д. б. н. Рассказов В. А.), активно используется в настоящее время в российских и зарубежных лабораториях. Работы, посвященные исследованию флуоресцентных белков, получили мировое признание и перевели на качественно новый уровень технологии прижизненного мечения.

Избранные публикации

  1. Shagina I., Bogdanova E., Mamedov I., Lebedev Y., Lukyanov S., Shagin D. (2010). Normalization of genomic DNA using duplex-specific nuclease. BioTechniques 48 (6), 351–355 [+]

    An application of duplex-specific nuclease (DSN) normalization technology to whole-genome shotgun sequencing of genomes with a large proportion of repetitive DNA is described. The method uses a thermostable DSN from the Kamchatka crab that specifically hydrolyzes dsDNA. In model experiments on human genomic DNA, we demonstrated that DSN normalization of double-stranded DNA formed during C0t analysis is effective against abundant repetitive sequences with high sequence identity, while retaining highly divergent repeats and coding regions at baseline levels. Thus, DSN normalization applied to C0t analysis can be used to eliminate evolutionarily young repetitive elements from genomic DNA before sequencing, and should prove invaluable in studies of large eukaryotic genomes, such as those of higher plants.

  2. Bogdanov A.M., Bogdanova E.A., Chudakov D.M., Gorodnicheva T.V., Lukyanov S., Lukyanov K.A. (2009). Cell culture medium affects GFP photostability: a solution. Nat. Methods 6 (12), 859–60
  3. Bogdanov A.M., Mishin A.S., Yampolsky I.V., Belousov V.V., Chudakov D.M., Subach F.V., Verkhusha V.V., Lukyanov S., Lukyanov K.A. (2009). Green fluorescent proteins are light-induced electron donors. Nat. Chem. Biol.  (5), 459–461 [+]

    Proteins of the green fluorescent protein (GFP) family are well known owing to their unique biochemistry and extensive use as in vivo markers. We discovered that GFPs of diverse origins can act as light-induced electron donors in photochemical reactions with various electron acceptors, including biologically relevant ones. Moreover, via green-to-red GFP photoconversion, this process can be observed in living cells without additional treatment.

  4. Shcherbo D., Murphy C.S., Ermakova G.V., Solovieva E.A., Chepurnykh T.V., Shcheglov A.S., Verkhusha V.V., Pletnev V.Z., Hazelwood K.L., Roche P.M., Lukyanov S., Zaraisky A.G., Davidson M.W., Chudakov D.M. (2009). Far-red fluorescent tags for protein imaging in living tissues. Biochem. J. 418 (3), 567–74 [+]

    Разработан яркий, мономерный, фотостабильный, pH-стабильный, дальне-красный флуоресцентый белок mKate2. Белок mKate2 хорошо показал себя в качестве метки во фьюзах с рядом белков, как в культуре клеток, так и в трансгенных лягушках Xenopus laevis (совместно с лабораторией Молекулярных основ эмбриогенеза ИБХ РАН).

  5. Shcherbo D., Merzlyak E.M., Chepurnykh T.V., Fradkov A.F., Ermakova G.V., Solovieva E.A., Lukyanov K.A., Bogdanova E.A., Zaraisky A.G., Lukyanov S., Chudakov D.M. (2007). Bright far-red fluorescent protein for whole-body imaging. Nat. Methods 4 (9), 741–6 [+]

    Разработан новый флуоресцентный белок Katushka, обладающий флуоресценцией в дальне-красной области спектра, которая является предпочтительной для анализа сигнала внутри тканей животных. Katushka в десять раз ярче, чем созданные ранее дальне-красные флуоресцентные белки и характеризуется высокой скоростью созревания, высокой рН-стабильностью и фотостабильностью. Это делает новый белок идеальным инструментом для прижизненного мечения клеток внутри целых организмов. Создан мономерный вариант белка Katushka, названный mKate, для исследования внутриклеточной локализации белков.

  6. Merzlyak E.M., Goedhart J., Shcherbo D., Bulina M.E., Shcheglov A.S., Fradkov A.F., Gaintzeva A., Lukyanov K.A., Lukyanov S., Gadella T.W., Chudakov D.M. (2007). Bright monomeric red fluorescent protein with an extended fluorescence lifetime. Nat. Methods 4 (7), 555–7 [+]

    Fluorescent proteins have become extremely popular tools for in vivo imaging and especially for the study of localization, motility and interaction of proteins in living cells. Here we report TagRFP, a monomeric red fluorescent protein, which is characterized by high brightness, complete chromophore maturation, prolonged fluorescence lifetime and high pH-stability. These properties make TagRFP an excellent tag for protein localization studies and fluorescence resonance energy transfer (FRET) applications.

  7. Chudakov D.M., Lukyanov S., Lukyanov K.A. (2007). Using photoactivatable fluorescent protein Dendra2 to track protein movement. BioTechniques 42 (5), 553, 555, 557 passim [+]

    Photoactivatable fluorescent proteins are capable of dramatic changes in fluorescent properties in response to specific light irradiation. For example, they can be converted from cyan to green, or from green to red, or from nonfluorescent to a brightly fluorescent state. Several types of such proteins were developed recently, and some of them are already becoming popular tools to study protein mobility. Here we provide detailed recommendations on application of the monomeric green-to-red photoconvertible fluorescent protein Dendra2 for protein tracking in living cultured cells.

  8. Chudakov D.M., Chepurnykh T.V., Belousov V.V., Lukyanov S., Lukyanov K.A. (2006). Fast and precise protein tracking using repeated reversible photoactivation. Traffic 7 (10), 1304–10 [+]

    Photoactivatable fluorescent proteins opened principally novel possibilities to study proteins' movement pathways. In particular, reversibly photoactivatable proteins enable multiple tracking experiments in a long-drawn work with a single cell. Here we report 'protein rivers tracking' technique based on repeated identical rounds of photoactivation and subsequent images averaging, which results in dramatic increase of imaging resolution for fast protein movement events.

  9. Belousov V.V., Fradkov A.F., Lukyanov K.A., Staroverov D.B., Shakhbazov K.S., Terskikh A.V., Lukyanov S. (2006). Genetically encoded fluorescent indicator for intracellular hydrogen peroxide. Nat. Methods 3 (4), 281–6 [+]

    Разработан уникальный флуоресцентный сенсор HyPer для прижизненного мониторинга колебаний концентрации одного из важнейших регуляторов биологических процессов — перекиси водорода. Имеющий белковую природу, HyPer может быть экспрессирован в клетках или направлен в определенный клеточный компартмент. Благодаря высокой специфичности и чувствительности, HyPer может быть использован для отслеживания колебаний концентрации перекиси водорода на уровне единственной клетки или клеточной органеллы.

  10. Gurskaya N.G., Verkhusha V.V., Shcheglov A.S., Staroverov D.B., Chepurnykh T.V., Fradkov A.F., Lukyanov S., Lukyanov K.A. (2006). Engineering of a monomeric green-to-red photoactivatable fluorescent protein induced by blue light. Nat. Biotechnol. 24 (4), 461–5 [+]

    Разработан новый мономерный флуоресцентный белок Dendra, способный к необратимой фотоконверсии из зеленой флуоресцентной формы в красную. Белок Dendra обладает высокой яркостью флуоресценции и может быть активирован как ультрафиолетовым, так и синим светом.

  11. Bulina M.E., Lukyanov K.A., Britanova O.V., Onichtchouk D., Lukyanov S., Chudakov D.M. (2006). Chromophore-assisted light inactivation (CALI) using the phototoxic fluorescent protein KillerRed. Nat Protoc 1 (2), 947–53 [+]

    The phototoxic red fluorescent GFP-like protein KillerRed has recently been described. The phototoxicity of KillerRed exceeds that of EGFP by at least 1,000-fold, making it the first fully genetically encoded photosensitizer. KillerRed opens up new possibilities for precise light-induced cell killing and target protein inactivation. Because KillerRed is encoded by a gene, it can be expressed in a spatially and temporally regulated manner, under a chosen promoter, and fused with the desired protein of interest or localization signal. Here we provide a protocol for target protein inactivation in cell culture using KillerRed. As KillerRed is a new tool, the protocol focuses on aspects that will allow users to maximize the potential of this protein, guiding the design of chimeric constructs, recommended control experiments and preferred illumination parameters. The protocol, which describes target protein visualization and subsequent inactivation, is a 2- or 3-d procedure.

  12. Bulina M.E., Chudakov D.M., Britanova O.V., Yanushevich Y.G., Staroverov D.B., Chepurnykh T.V., Merzlyak E.M., Shkrob M.A., Lukyanov S., Lukyanov K.A. (2006). A genetically encoded photosensitizer. Nat. Biotechnol. 24 (1), 95–9 [+]

    Photosensitizers are chromophores that generate reactive oxygen species (ROS) upon light irradiation. They are used for inactivation of specific proteins by chromophore-assisted light inactivation (CALI) and for light-induced cell killing in photodynamic therapy. Here we report a genetically encoded photosensitizer, which we call KillerRed, developed from the hydrozoan chromoprotein anm2CP, a homolog of green fluorescent protein (GFP). KillerRed generates ROS upon irradiation with green light. Whereas known photosensitizers must be added to living systems exogenously, KillerRed is fully genetically encoded. We demonstrate the utility of KillerRed for light-induced killing of Escherichia coli and eukaryotic cells and for inactivating fusions to beta-galactosidase and phospholipase Cdelta1 pleckstrin homology domain.

  13. Lukyanov K.A., Chudakov D.M., Fradkov A.F., Labas Y.A., Matz M.V., Lukyanov S. (2006). Discovery and properties of GFP-like proteins from nonbioluminescent anthozoa. Methods Biochem Anal 47, 121–38
  14. Shkrob M.A., Yanushevich Y.G., Chudakov D.M., Gurskaya N.G., Labas Y.A., Poponov S.Y., Mudrik N.N., Lukyanov S., Lukyanov K.A. (2005). Far-red fluorescent proteins evolved from a blue chromoprotein from Actinia equina. Biochem. J. 392 (Pt 3), 649–54 [+]

    Proteins of the GFP (green fluorescent protein) family demonstrate a great spectral and phylogenetic diversity. However, there is still an intense demand for red-shifted GFP-like proteins in both basic and applied science. To obtain GFP-like chromoproteins with red-shifted absorption, we performed a broad search in blue-coloured Anthozoa species. We revealed specimens of Actinia equina (beadlet anemone) exhibiting a bright blue circle band at the edge of the basal disc. A novel blue chromoprotein, aeCP597, with an absorption maximum at 597 nm determining the coloration of the anemone basal disk was cloned. AeCP597 carries a chromophore chemically identical with that of the well-studied DsRed (red fluorescent protein from Discosoma sp.). Thus a strong 42-nm bathochromic shift of aeCP597 absorption compared with DsRed is determined by peculiarities of chromophore environment. Site-directed and random mutagenesis of aeCP597 resulted in far-red fluorescent mutants with emission maxima at up to 663 nm. The most bright and stable mutant AQ143 possessed excitation and emission maxima at 595 and 655 nm respectively. Thus aeCP597 and its fluorescent mutants set a new record of red-shifted absorption and emission maxima among GFP-like proteins.

  15. Chudakov D.M., Lukyanov S., Lukyanov K.A. (2005). Fluorescent proteins as a toolkit for in vivo imaging. Trends Biotechnol. 23 (12), 605–13 [+]

    Green fluorescent protein (GFP) from the jellyfish Aequorea victoria, and its mutant variants, are the only fully genetically encoded fluorescent probes available and they have proved to be excellent tools for labeling living specimens. Since 1999, numerous GFP homologues have been discovered in Anthozoa, Hydrozoa and Copepoda species, demonstrating the broad evolutionary and spectral diversity of this protein family. Mutagenic studies gave rise to diversified and optimized variants of fluorescent proteins, which have never been encountered in nature. This article gives an overview of the GFP-like proteins developed to date and their most common applications to study living specimens using fluorescence microscopy.

  16. Lukyanov K.A., Chudakov D.M., Lukyanov S., Verkhusha V.V. (2005). Innovation: Photoactivatable fluorescent proteins. Nat. Rev. Mol. Cell Biol. 6 (11), 885–91 [+]

    The fluorescence characteristics of photoactivatable proteins can be controlled by irradiating them with light of a specific wavelength, intensity and duration. This provides unique possibilities for the optical labelling and tracking of living cells, organelles and intracellular molecules in a spatio-temporal manner. Here, we discuss the properties of the available photoactivatable fluorescent proteins and their potential applications.

  17. Chudakov D.M., Verkhusha V.V., Staroverov D.B., Souslova E.A., Lukyanov S., Lukyanov K.A. (2004). Photoswitchable cyan fluorescent protein for protein tracking. Nat. Biotechnol. 22 (11), 1435–9 [+]

    In recent years diverse photolabeling techniques using green fluorescent protein (GFP)-like proteins have been reported, including photoactivatable PA-GFP, photoactivatable protein Kaede, the DsRed 'greening' technique and kindling fluorescent proteins. So far, only PA-GFP, which is monomeric and gives 100-fold fluorescence contrast, could be applied for protein tracking. Here we describe a dual-color monomeric protein, photoswitchable cyan fluorescent protein (PS-CFP). PS-CFP is capable of efficient photoconversion from cyan to green, changing both its excitation and emission spectra in response to 405-nm light irradiation. Complete photoactivation of PS-CFP results in a 1,500-fold increase in the green-to-cyan fluorescence ratio, making it the highest-contrast monomeric photoactivatable fluorescent protein described to date. We used PS-CFP as a photoswitchable tag to study trafficking of human dopamine transporter in living cells. At moderate excitation intensities, PS-CFP can be used as a pH-stable cyan label for protein tagging and fluorescence resonance energy transfer applications.

  18. Bulina M.E., Lukyanov K.A., Yampolsky I.V., Chudakov D.M., Staroverov D.B., Shcheglov A.S., Gurskaya N.G., Lukyanov S. (2004). New class of blue animal pigments based on Frizzled and Kringle protein domains. J. Biol. Chem. 279 (42), 43367–70 [+]

    The nature of coloration in many marine animals remains poorly investigated. Here we studied the blue pigment of a scyfoid jellyfish Rhizostoma pulmo and determined it to be a soluble extracellular 30-kDa chromoprotein with a complex absorption spectrum peaking at 420, 588, and 624 nm. Furthermore, we cloned the corresponding cDNA and confirmed its identity by immunoblotting and mass spectrometry experiments. The chromoprotein, named rpulFKz1, consists of two domains, a Frizzled cysteine-rich domain and a Kringle domain, inserted into one another. Generally, Frizzleds are members of a basic Wnt signal transduction pathway investigated intensely with regard to development and cancerogenesis. Kringles are autonomous structural domains found throughout the blood clotting and fibrinolytic proteins. Neither Frizzled and Kringle domains association with any type of coloration nor Kringle intrusion into Frizzled sequence was ever observed. Thus, rpulFKz1 represents a new class of animal pigments, whose chromogenic group remains undetermined. The striking homology between a chromoprotein and members of the signal transduction pathway provides a novel node in the evolution track of growth factor-mediated morphogenesis compounds.

  19. Verkhusha V.V., Chudakov D.M., Gurskaya N.G., Lukyanov S., Lukyanov K.A. (2004). Common pathway for the red chromophore formation in fluorescent proteins and chromoproteins. Chem. Biol. 11 (6), 845–54 [+]

    The mechanism of the chromophore maturation in members of the green fluorescent protein (GFP) family such as DsRed and other red fluorescent and chromoproteins was analyzed. The analysis indicates that the red chromophore results from a chemical transformation of the protonated form of the GFP-like chromophore, not from the anionic form, which appears to be a dead-end product. The data suggest a rational strategy to achieve the complete red chromophore maturation utilizing substitutions to favor the formation of the neutral phenol in GFP-like chromophore. Our approach to detect the neutral chromophore form expands the application of fluorescent timer proteins to faster promoter activities and more spectrally distinguishable fluorescent colors. Light sensitivity found in the DsRed neutral form, resulting in its instant transformation to the mature red chromophore, could be exploited to accelerate the fluorescence acquisition.

  20. Chudakov D.M., Feofanov A.V., Mudrik N.N., Lukyanov S., Lukyanov K.A. (2003). Chromophore environment provides clue to "kindling fluorescent protein" riddle. J. Biol. Chem. 278 (9), 7215–9 [+]

    asCP, the unique green fluorescent protein-like nonfluorescent chromoprotein from the sea anemone Anemonia sulcata, becomes fluorescent ("kindles") upon green light irradiation, with maximum emission at 595 nm. The kindled protein then relaxes to a nonfluorescent state or can be "quenched" instantly by blue light irradiation. In this work, we used asCP mutants to investigate the mechanism underlying kindling. Using site-directed mutagenesis we showed that amino acids spatially surrounding Tyr(66) in the chromophore are crucial for kindling. We propose a model of the kindling mechanism, in which the key event is chromophore turning or cis-trans isomerization. Using site-directed mutagenesis we also managed to transfer the kindling property to the two other coral chromoproteins. Remarkably, most kindling mutants were capable of both reversible and irreversible kindling. Also, we obtained novel variants that kindled upon blue light irradiation. The diversity of photoactivated fluorescent proteins that can be developed by site-directed mutagenesis is promising for biotechnological needs.

  21. Chudakov D.M., Belousov V.V., Zaraisky A.G., Novoselov V.V., Staroverov D.B., Zorov D.B., Lukyanov S., Lukyanov K.A. (2003). Kindling fluorescent proteins for precise in vivo photolabeling. Nat. Biotechnol. 21 (2), 191–4 [+]

    Photobleaching of green fluorescent protein (GFP) is a widely used approach for tracking the movement of subcellular structures and intracellular proteins. Although photobleaching is a powerful technique, it does not allow direct tracking of an object's movement and velocity within a living cell. Direct tracking becomes possible only with the introduction of a photoactivated fluorescent marker. A number of previous studies have reported optically induced changes in the emission spectra of fluorescent proteins. However, the ideal photoactivated fluorescent marker should be a nonfluorescent tag capable of "switching on" (i.e., becoming fluorescent) in response to irradiation by light of a particular wavelength, intensity, and duration. In this report, we generated a mutant of Anemonia sulcata chromoprotein asCP. The mutant protein is capable of unique irreversible photoconversion from the nonfluorescent to a stable bright-red fluorescent form ("kindling"). This "kindling fluorescent protein" (KFP1) can be used for precise in vivo photolabeling to track the movements of cells, organelles, and proteins. We used KFP1 for in vivo cell labeling in mRNA microinjection assays to monitor Xenopus laevis embryo development and to track mitochondrial movement in mammalian cells.

  22. Shagin D.A., Rebrikov D.V., Kozhemyako V.B., Altshuler I.M., Shcheglov A.S., Zhulidov P.A., Bogdanova E.A., Staroverov D.B., Rasskazov V.A., Lukyanov S. (2002). A novel method for SNP detection using a new duplex-specific nuclease from crab hepatopancreas. Genome Res. 12 (12), 1935–42 [+]

    Охарактеризован новый фермент — дуплекс-специфическая нуклеаза (ДСН) из гепатопанкреаса камчатского краба. ДСН обладает высокой специфичностью к двухцепочечной ДНК при отсутствии гидролитической активности по отношению к одноцепочечной ДНК и РНК и стабильность в широком диапазоне температур. Благодаря уникальной комбинации свойств ДСН является идеальным инструментом для удаления двухцепочечной ДНК из сложных смесей нуклеиновых кислот.

  23. Terskikh A., Fradkov A., Ermakova G., Zaraisky A., Tan P., Kajava A.V., Zhao X., Lukyanov S., Matz M., Kim S., Weissman I., Siebert P. (2000). "Fluorescent timer": protein that changes color with time. Science 290 (5496), 1585–8 [+]

    We generated a mutant of the red fluorescent protein drFP583. The mutant (E5) changes its fluorescence from green to red over time. The rate of color conversion is independent of protein concentration and therefore can be used to trace time-dependent expression. We used in vivo labeling with E5 to measure expression from the heat shock-dependent promoter in Caenorhabditis elegans and from the Otx-2 promoter in developing Xenopus embryos. Thus, E5 is a "fluorescent timer" that can be used to monitor both activation and down-regulation of target promoters on the whole-organism scale.

  24. Matz M.V., Fradkov A.F., Labas Y.A., Savitsky A.P., Zaraisky A.G., Markelov M.L., Lukyanov S.A. (1999). Fluorescent proteins from nonbioluminescent Anthozoa species. Nat. Biotechnol. 17 (10), 969–73 [+]

    Открыты новые флуоресцентные белки из коралловых полипов класса Anthozoa с разными цветами флуоресценции от сине-зеленого до красного. Выявление флуоресцентных и окрашенных GFP-подобных белков у неспособных к биолюминесценции коралловых полипов опровергло распространенное мнение, что такие белки функционируют только в составе биолюминисцентных систем и прояснило природу разнообразной флуоресцентной окраски коралловых рифов — явления, которое на протяжении многих лет не находило правильного объяснения.

  25. Kazanskaya O.V., Severtzova E.A., Barth K.A., Ermakova G.V., Lukyanov S.A., Benyumov A.O., Pannese M., Boncinelli E., Wilson S.W., Zaraisky A.G. (1997). Anf: a novel class of vertebrate homeobox genes expressed at the anterior end of the main embryonic axis. Gene 200 (1-2), 25–34 [+]

    Five novel genes homologous to the homeobox-containing genes Xanf-1 and Xanf-2 of Xenopus and Hesx-1/Rpx of mouse have been identified as a result of a PCR survey of cDNA in sturgeon, zebrafish, newt, chicken and human. Comparative analysis of the homeodomain primary structure of these genes revealed that they belong to a novel class of homeobox genes, which we name Anf. All genes of this class investigated so far have similar patterns of expression during early embryogenesis, characterized by maximal transcript levels being present at the anterior extremity of the main embryonic body axis. The data obtained also suggest that, despite considerable high structural divergence between their homeodomains, all known Anf genes may be orthologues, and thus represent one of the most quickly evolving classes of vertebrate homeobox genes.

  26. Zaraisky A.G., Ecochard V., Kazanskaya O.V., Lukyanov S.A., Fesenko I.V., Duprat A.M. (1995). The homeobox-containing gene XANF-1 may control development of the Spemann organizer. Development 121 (11), 3839–47 [+]

    At the beginning of gastrulation the homeobox-containing gene, XANF-1, is expressed at a low level throughout the animal hemisphere of Xenopus laevis embryos, with a local maximum of expression in the region of the dorsal blastopore lip. By the end of gastrulation expression ceases everywhere except in the most anterior part of the neurectoderm. We have investigated the functions of this gene by microinjecting XANF-1 mRNA in the blastomeres of the 32-cell stage embryo and have observed the following effects. First, microinjections of the mRNA in the animal blastomeres and the blastomeres of the marginal zone elicited massive migration of cells to the interior of the embryo at the early gastrula stage. Second, overexpression of XANF-1 in the ventral marginal zone (VMZ) resulted in the appearance of an additional centre of gastrulation movements and the formation of a secondary axis. In addition we showed that synthetic XANF-1 mRNA was able to cause dorsal-type differentiation in VMZ explants extirpated from the microinjected embryos at the beginning of gastrulation. These results suggest that XANF-1 may control the main functions of cells of the Spemann organizer.

  27. Zaraisky A.G., Lukyanov S.A., Vasiliev O.L., Smirnov Y.V., Belyavsky A.V., Kazanskaya O.V. (1992). A novel homeobox gene expressed in the anterior neural plate of the Xenopus embryo. Dev. Biol. 152 (2), 373–82 [+]

    To obtain gene sequences controlling the early steps of amphibian neurogenesis, we have performed differential screening of a subtractive cDNA library prepared by a novel PCR-based method from a single presumptive neural plate of a Xenopus laevis late-gastrula embryo. As a result we have isolated a fragment of a novel homeobox gene (named XANF-1, for Xenopus anterior neural folds). This gene is expressed predominantly in the anterior part of the developing nervous system. Such preferential localization of XANF-1 mRNA is established from its initially homogenous distribution in ectoderm of early gastrula. This change in the expression pattern is conditioned by a differential influence of various mesoderm regions on ectoderm: anterior mesoderm activates XANF-1 expression in the overlying ectoderm, whereas posterior axial and ventral mesoderm areas inhibit it. The data obtained demonstrate for the first time that selection of genes for specific expression in the CNS of the early vertebrate embryo is affected not only by chordamesoderm (a neural inductor) but also by ventral mesoderm.