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Biomedical subjects

V V Novoselov

Publications and source records attributed to V V Novoselov.

5 recordsLinked to original sources
PubMed2003

Expression zones of three novel genes abut the developing anterior neural plate of Xenopus embryo.

We identified three novel genes that were expressed within the anterior non-neural ectoderm of Xenopus early neurula embryos. The expression of these genes was observed in the different areas complementary to the expression zone of a homeodomain gene Xanf-1 in the anterior neural plate. One of these genes, a Ras-like GTP-ase Ras-dva, marked the anterior placodal ectoderm area; a second, an Agr family homologous gene, XAgr2, was expressed in the anterior-most ectoderm in the cement gland primordium, and a third, novel gene Nlo was expressed in the lateral neural folds. The genes were transiently expressed in the developing cement and hatching gland primordia, and repressed in the mature cement and hatching glands. XAgr2 and Nlo were also expressed in the otic vesicles, and Ras-dva was expressed in the dorso-lateral column of the neural tube.

Amino Acid Sequence↗
PubMed1997

Studies in developmental cytomechanic.

One of the most promising trends in modern developmental and cell biology, recently defined as < >, or < >, is directed towards revealing the role of mechanical stresses, chemomechanical transduction and active stress responses of cells antissues of developing embryos. We review here the results obtained in this field by our research group and compare them with those from other labs. Our studies relate to the buds of hydroid polypes and to amphibian embryos. We describe the space-temporal patterns of mechanical stresses in these species, analyze their morphogenetical role and the tissue responses to the experimental modulations of stress patterns. In hydroid polypes we explore also the molecular events involved in mechanochemical coupling. A model, linking the passive mechanical stresses with the active stress-responses of embryonic tissues is suggested. We consider these investigations as a first approach to a developing embryo as to an < >.

Animals↗
PubMed1990

Effects of relaxation of mechanical tensions upon the early morphogenesis of Xenopus laevis embryos.

In Xenopus laevis embryos at the early gastrula stage, circumferential tensions of embryonic ectoderm were relaxed by making sagittal or transversal slits in the ventral parts of embryos and inserting into surgical cuts the sectors of homologous tissue from same-stage embryos. Changes in tensile patterns were controlled by measuring cell surface angles. Immediate decreases in surface cell wall tension as related to transversal wall tension were registered. Within minutes of the operation, the lobopodial activity of the inner ectodermal surface increased. The subsequent gastrulation movements were disturbed, germ layers partially mixed and archenteron reduced. The areas of extensive cell columnarization in the ectoderm of operated embryos were less regularly arranged and were extended much more ventrally than in intact embryos. Ventro-dorsal migration and latero-medial intercalation of mesodermal cells also were suppressed. As the operated embryos developed, we observed increases in the total amount of neural tissue, associated sometimes with duplication and even triplication of neural tubes, duplication of otic vesicles, partial fusion of axial rudiments, suppression of mesodermal segmentation and branching or bending of notochord. In the gravest cases the antero-posterior embryo polarity was disturbed. In some cases we observed the formation of axial rudiments in ventral implants. The role of tensions in determining the patterns of morphogenetic cell movements and in establishing the morphological order of normal development is discussed.

Age Factors↗
PubMedDate not supplied

[A comparative analysis of notochord formation in amphibian embryos].

We studied the origin, structure, and development of the notochord in Pleurodeles waltlii (Urodela) and Xenopus laevis (Anura) embryos. The notochord rudiment is formed in both species at the early gastrula stage as a cluster of polarized chorda-mesoderm cells located along the sagittal plane of the embryo. In Pl. waltlii the notochord rudiment is separated from the gastrocoele roof as a result of contraction of apical cell surfaces. The contraction wave spreads forward and backward along craniocaudal axis, i.e., segregation of the notochord rudiment progresses in two directions simultaneously. Similar process takes place in X. laevis embryos; however, propagation of the contraction wave in the anterior part of the body somewhat differs from that in the posterior part. While the "anterior" contraction wave resembles that in Pl. waltlii embryos, progression of the wave in the posterior part of the body is distinguished by a closer association of the notochord rudiment with ectoderm and the presence of its delamination boundaries with the somite mesoderm.

Amphibians↗