Phylogeography of Witefish (Coregonus lavaretus L.) of North-West Russia

The reasons of genetic heterogeneity of Siberian whitefish Coregonus lavaretus pidschian in the Anabar river

Ecological genetics ◽

10.17816/ecogen15320-26 ◽

2017 ◽

Vol 15 (3) ◽

pp. 20-26

Author(s):

Dmitry S. Sendek ◽

Eugenie V. Ivanov

Keyword(s):

Genetic Heterogeneity ◽

River System ◽

Coregonus Lavaretus ◽

Population Genetic Study ◽

North West ◽

Siberian Whitefish ◽

Anabar River ◽

Environmental Measures ◽

Phylogenetic Lineages ◽

Ecological Forms

Background. A population genetic study of Siberian whitefish or pidschian Coregonus lavaretus pidschian Gmelin of the Anabar River (North-West Yakutia) has been done to study genetic structure of the species within a river system and for revealing its phylogeographic relations. Materials and Methods. Five samples of pidschian from different parts of the river were analyzed for 30 isozyme loci. Results and Discussion. The results has demonstrated a significant genetic heterogeneity of the species sampled from lower and middle reaches of the river (0.001 < DN< 0.056). The most likely reason for genetic differentiation of the species within the river system is a colonization of the watershed by independent phylogenetic lineages of whitefish. At present the phylogenetic lineages in Anabar River are presented by sympatric ecological forms of the species – eastern-siberian whitefish and glacial-plains whitefish – which maintain their reproductive isolation. The relationships of ecological forms of whitefish dwelling the Anabar River with other populations of the species in Siberia, and possible ways of penetration of discrete phylogenetic lineages of pidschian in the basin of studied river are discussed. Conclusions. A genetic heterogeneity of whitefish from Anabar River should be taken into account while creating adequate intraspecific taxonomy and considered in conducting fisheries and environmental measures.

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Electron Microscopic Examination of a Transplantable Rat Mammary Carcinoma

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100099842 ◽

1968 ◽

Vol 26 ◽

pp. 20-21

Author(s):

S. Shirahama ◽

G. C. Engle ◽

R. M. Dutcher

Keyword(s):

Electron Microscope ◽

Osmium Tetroxide ◽

Electron Microscopic Examination ◽

Undifferentiated Carcinoma ◽

Uranyl Acetate ◽

Sprague Dawley ◽

Electron Microscopic ◽

North West ◽

X Irradiation ◽

Tissue Specimens

A transplantable carcinoma was established in North West Sprague Dawley (NWSD) rats by use of X-irradiation by Engle and Spencer. The tumor was passaged through 63 generations over a period of 32 months. The original tumor, an adenocarcinoma, changed into an undifferentiated carcinoma following the 19th transplant. The tumor grew well in NWSD rats of either sex at various ages. It was invariably fatal, causing death of the host within 15 to 35 days following transplantation.Tumor, thymus, spleen, and plasma from 7 rats receiving transplants of tumor at 3 to 9 weeks of age were examined with an electron microscope at intervals of 8, 15, 22 and 30 days after transplantation. Four normal control rats of the same age were also examined. The tissues were fixed in glutaraldehyde, postfixed in osmium tetroxide and embedded in Epon. The plasma was separated from heparanized blood and processed as previously described for the tissue specimens. Sections were stained with uranyl acetate followed by lead citrate and examined with an RCA EMU-3G electron microscope.

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SEM and TEM observations of sperm development in the testis of the freshwater fish Oreochromis mossambicus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100157838 ◽

1990 ◽

Vol 48 (3) ◽

pp. 58-59

Author(s):

Daryl A. Cornish ◽

George L. Smit

Keyword(s):

Morphological Characteristics ◽

Oreochromis Mossambicus ◽

Breeding Cycle ◽

Limited Information ◽

North West ◽

The North ◽

Sem And Tem ◽

Sperm Development ◽

Ultrastructural Characteristics ◽

The University

Oreochromis mossambicus is currently receiving much attention as a candidater species for aquaculture programs within Southern Africa. This has stimulated interest in its breeding cycle as well as the morphological characteristics of the gonads. Limited information is available on SEM and TEM observations of the male gonads. It is known that the testis of O. mossambicus is a paired, intra-abdominal structure of the lobular type, although further details of its characteristics are not known. Current investigations have shown that spermatids reach full maturity some two months after the female becomes gravid. Throughout the year, the testes contain spermatids at various stages of development although spermiogenesis appears to be maximal during November when spawning occurs. This paper describes the morphological and ultrastructural characteristics of the testes and spermatids.Specimens of this fish were collected at Syferkuil Dam, 8 km north- west of the University of the North over a twelve month period, sacrificed and the testes excised.

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