SEX DIFFERENTIATION IN THE PACIFIC SALMON ONCORHYNCHUS KETA (WALBAUM)

1953 ◽  
Vol 31 (2) ◽  
pp. 73-79 ◽  
Author(s):  
J. G. Robertson
Keyword(s):  
Germ Cells ◽  
Chum Salmon ◽  
Pacific Salmon ◽  
Sex Differentiation ◽  
Primordial Germ Cells ◽  
The Other ◽  
Oncorhynchus Keta ◽  
Progressive Development ◽  
The Pacific ◽  
Female Phase

The differentiation of the gonad is described in chum salmon embryos and alevins. Contrary to classical findings in teleosts, sex differentiation in the chum salmon proceeds in the male or female direction without an intermediate female phase. From an initially indifferent gonad there is a progressive development of one sex or the other. The organ forms as a fold from the splanchnic mesoderm and, at the time of first appearance, contains primordial germ cells. These enlarge to form the definitive germ cells which, after a series of divisions, form smaller oogonia or spermatogonia. Oogonia are followed by primary and secondary (growing) oocytes, the appearance of which is the criterion of sex distinction. Spermatogonia continue to multiply but do not undergo growth in the alevin. The ovary develops an open endovarial canal and is supported by a prominent mesovarium. The testis remains small and, in the alevin, develops no ducts. It is suspended by a mesorchium.

Sex differentiation of germ cells in the teleost, Oryzias latipes, during normal embryonic development

Development ◽  
1972 ◽  
Vol 28 (2) ◽  
pp. 385-395
Author(s):  
Noriyuki Satoh ◽  
Nobuo Egami
Keyword(s):  
Germ Cells ◽  
Meiotic Prophase ◽  
Sex Differentiation ◽  
Primordial Germ Cells ◽  
Oryzias Latipes ◽  
The Other ◽  
Histological Structure ◽  
The Mean ◽  
Further Development ◽  
Normal Embryonic Development

Mitotic and meiotic activities of germ cells during early development in the medaka, Oryzias latipes, are dealt with in this report. Primordial germ cells were obviously distinguishable from somatic cells 3 days after fertilization and began to proliferate about 7 days after fertilization. The mean number of primordial germ cells increased during a period of 7–10 days after fertilization, reaching about 90 immediately before hatching. Newly hatched fry could be classified into two types according to the number and the nucleic activity of germ cells in the gonadal rudiment. One type consisted of fry containing about 100 germ cells and no cells in the meiotic prophase. In the other type of fry the number of germ cells increased by mitotic divisions and some of the cells began to enter into the meiotic prophase. During the course of further development the fry of the former type differentiated into males and the latter into females. Therefore it can be concluded that the morphological sex differentiation of germ cells occurs at the time of hatching. However, no sexual differences in the histological structure of somatic elements in the gonad are observable at that time.

scholarly journals Genome assembly, transcriptome and SNP database for chum salmon (Oncorhynchus keta)

2021 ◽  
Author(s):  
Eric B Rondeau ◽  
Kris A. Christensen ◽  
Dionne Sakhrani ◽  
Carlo A Biagi ◽  
Mike Wetklo ◽  
...  
Keyword(s):  
British Columbia ◽  
Linkage Group ◽  
Genome Assembly ◽  
Chum Salmon ◽  
Pacific Salmon ◽  
Gene Annotation ◽  
Oncorhynchus Keta ◽  
Specific Level ◽  
Genome Wide ◽  
The Pacific

Chum salmon (Oncorhynchus keta) is the species with the widest geographic range of the anadromous Pacific salmonids,. Chum salmon is the second largest of the Pacific salmon, behind Chinook salmon, and considered the most plentiful Pacific salmon by overall biomass. This species is of significant commercial and economic importance: on average the commercial chum salmon fishery has the second highest processed value of the Pacific salmon within British Columbia. The aim of this work was to establish genomic baseline resources for this species. Our first step to accomplish this goal was to generate a chum salmon reference genome assembly from a doubled-haploid chum salmon. Gene annotation of this genome was facilitated by an extensive RNA-seq database we were able to create from multiple tissues. Range-wide resequencing of chum salmon genomes allowed us to categorize genome-wide geographic variation, which in turn reinforced the idea that genetic differentiation was best described on a regional, rather than at a stock-specific, level. Within British Columbia, chum salmon regional groupings were described at the conservation unit (CU) level, and there may be substructure within particular CUs. Genome wide associations of phenotypic sex to SNP genetic markers identified two clear peaks, a very strong peak on Linkage Group 15, and another on Linkage Group 3. With these new resources, we were better able to characterize the sex-determining region and gain further insights into sex determination in chum salmon and the general biology of this species.

Rationalizing the Irrational: A Case Study in User Group Participation in Pacific Salmon Management

1987 ◽  
Vol 44 (10) ◽  
pp. 1796-1805 ◽  
Author(s):  
Ray Hilborn ◽  
Wilf Luedke
Keyword(s):  
Chum Salmon ◽  
Pacific Salmon ◽  
Political Activity ◽  
Oncorhynchus Keta ◽  
Recent Attempt ◽  
Decision Making Process ◽  
User Group ◽  
Salmon Fisheries ◽  
Insight Into

Acrimony between industry and government managers is commonplace in the management of many Pacific salmon fisheries. A case study of the chum salmon (Oncorhynchus keta) fisheries in southern British Columbia provides insight into the prevailing distrust between fishermen and managers. A recent attempt to bring planned management into what had often been an irrational and highly political activity is described. A management system called the "clockwork" provides all fishermen an opportunity for greater understanding of the management rationale and greater input into the decision-making process. The results of this attempt and implications for achieving management goals are discussed.

scholarly journals 171 NORMAL REPROGRAMMING OF IMPRINTING IN PARTHENOGENETIC FEMALE GERM CELLS

2005 ◽  
Vol 17 (2) ◽  
pp. 236
Author(s):  
T. Horii ◽  
Y. Nagao ◽  
M. Kimura ◽  
I. Hatada
Keyword(s):  
Germ Cells ◽  
Restriction Analysis ◽  
Primordial Germ Cells ◽  
Fluorescent Microscopy ◽  
Embryonic Stem ◽  
Postnatal Growth ◽  
The Other ◽  
Imprinted Genes ◽  
Host Embryo ◽  
Parthenogenetic Embryos

Mammalian parthenotes cannot develop normally to term. Mouse parthenogenetic embryos die by Day 10 of gestation. On the other hand, viable parthenogenetic chimeras were produced by normal host embryos, although parthenogenetic cells were observed in a limited number of tissues and organs and, even in these instances, their contribution was substantially reduced. This can be explained by the aberrant expressions of imprinted genes in parthenogenetic cells. In female mice, erasure of imprints occurs around the time that primordial germ cells enter the gonad, and establishment of imprints occurs in the postnatal growth phase of oogenesis. In this study, we investigated whether aberrant imprints in parthenogenetic embryonic stem (PgES) cells can be erased through the germline. Diploid parthenogenetic embryos were produced by activation of (CBA × C57BL/6-EGFP) F1 mouse superovulated unfertilized oocytes by exposure to Sr2+ and cytochalasin B. Ten parthenogenetic blastocysts were plated and three PgES cell lines were isolated. Chimeras were made by injecting 10–15 PgES cells into ICR(CD-1) mouse blastocysts. Chimeras and chimeric tissues were detected by fluorescent microscopy. In all, 173 chimeric blastocysts were transferred to 9 recipient females, and 101 live pups containing 9 female and 21 male chimeras were born. No significant growth retardation was apparent in PgES chimeras, irrespective of their degree of chimerism. In 5 male chimeras killed at 1 day postpartum (dpp), PgES cells showed a restricted tissue contribution. The contribution to lung, liver, and intestine was considerably lower than in the other tissues such as brain, heart, spleen, and kidney. PgES derived or host embryo derived non-growing oocytes were isolated from dissociated ovaries of female chimeras at 1 dpp under fluorescent microscopy. Methylation imprints in non-growing oocytes were analyzed for maternally methylated imprinted genes Peg1, Snrpn, and Igf2r by the combined bisulfite restriction analysis (COBRA). In normal oocytes, imprints are expected to be erased and these genes are unmethylated at this stage. We observed that these genes were unmethylated in both PgES derived and host embryo derived non-growing oocytes. These results suggest that aberrant imprints in PgES cells can also be erased normally through the germline.

scholarly journals Gametogenesis of the Pacific salmon. 3. Comparative analysis of the state of gonads in juvenile Pacific salmon due to fertility formation

2019 ◽  
Vol 323 (4) ◽  
pp. 429-441
Author(s):  
O.V. Zelennikov
Keyword(s):  
Comparative Analysis ◽  
Mitotic Activity ◽  
Fresh Water ◽  
Fish Species ◽  
Germ Cells ◽  
Pacific Salmon ◽  
Juvenile Fish ◽  
Pink Salmon ◽  
The Pacific ◽  
Juvenile Pacific Salmon

The ovarian condition was studied in juveniles of six species of the Pacific salmon of different ages, taken for research at four hatcheries, as well as captured in lakes and rivers in the Sakhalin Province and Kamchatka Territory. The formation of the older generation of germ cells, consisting of previellogenic oocytes, in females of the Pacific salmon ends at the age of 0+, in pink salmon, with a mass of about 0.2–0.3 g, in other species, with a mass of about 1–2 g. In all species, the replenishment of this generation ceases during the habitat of juvenile fish in fresh water. After the formation of the older generation of germ cells is completed and its number reaches a certain level characteristic of each fish species, two oogenesis processes, that are not externally related to each other, continue to be carried out in the ovaries. The first process is the growth of the older generation oocytes, which develop relatively synchronously, varying 1.5–2 times in diameter. The second process is the mitotic reproduction of the gonies, their entry into meiosis, and subsequent resorption at the stage of pachytene and early diplotene. The mitotic activity of the gonies is minimal in females of the pink salmon, and, in fact, it is not detected in the fish caught in the coast. In females of other species, a decrease in both mitotic activity and initiation of new meiotic cycles does not occur during the entire period of their habitat in fresh water.

scholarly journals XY oocytes of sex-reversed females with a Sry mutation deviate from the normal developmental process beyond the mitotic stage†

2018 ◽  
Vol 100 (3) ◽  
pp. 697-710 ◽  
Author(s):  
Akihiko Sakashita ◽  
Takuya Wakai ◽  
Yukiko Kawabata ◽  
Chiaki Nishimura ◽  
Yusuke Sotomaru ◽  
...  
Keyword(s):  
Germ Cells ◽  
Developmental Process ◽  
Sex Differentiation ◽  
Primordial Germ Cells ◽  
Primordial Follicle ◽  
Genetic Ablation ◽  
Female Mice ◽  
Meiotic Progression ◽  
Molecular Etiology ◽  
Mitotic Proliferation

Abstract The fertility of sex-reversed XY female mice is severely impaired by a massive loss of oocytes and failure of meiotic progression. This phenomenon remains an outstanding mystery. We sought to determine the molecular etiology of XY oocyte dysfunction by generating sex-reversed females that bear genetic ablation of Sry, a vital sex determination gene, on an inbred C57BL/6 background. These mutant mice, termed XYsry− mutants, showed severe attrition of germ cells during fetal development, resulting in the depletion of ovarian germ cells prior to sexual maturation. Comprehensive transcriptome analyses of primordial germ cells (PGCs) and postnatal oocytes demonstrated that XYsry− females had deviated significantly from normal developmental processes during the stages of mitotic proliferation. The impaired proliferation of XYsry− PGCs was associated with aberrant β-catenin signaling and the excessive expression of transposable elements. Upon entry to the meiotic stage, XYsry− oocytes demonstrated extensive defects, including the impairment of crossover formation, the failure of primordial follicle maintenance, and no capacity for embryo development. Together, these results suggest potential molecular causes for germ cell disruption in sex-reversed female mice, thereby providing insights into disorders of sex differentiation in humans, such as “Swyer syndrome,” in which patients with an XY karyotype present as typical females and are infertile.

scholarly journals Response of the Sea Louse Lepeophtheirus salmonis Infestation Levels on Juvenile Wild Pink, Oncorhynchus gorbuscha, and Chum, O. keta, Salmon to Arrival of Parasitized Wild Adult Pink Salmon

2006 ◽  
Vol 120 (2) ◽  
pp. 199
Author(s):  
Alexandra Morton ◽  
Rob Williams
Keyword(s):  
Chum Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Primary Source ◽  
Sea Lice ◽  
Oncorhynchus Gorbuscha ◽  
Oncorhynchus Keta ◽  
Lepeophtheirus Salmonis ◽  
Louse Infestation ◽  
Age Cohorts

Recent recurring infestations of Sea Lice, Lepeophtheirus salmonis, on juvenile Pacific salmon (Oncorhynchus spp.) and subsequent annual declines of these stocks have made it imperative to identify the source of Sea Lice. While several studies now identify farm salmon populations as sources of Sea Louse larvae, it is unclear to what extent wild salmonid hosts also contribute Sea Lice. We measured Sea Louse numbers on adult Pink Salmon (Oncorhynchus gorbuscha) migrating inshore. We also measured Sea Louse numbers on wild juvenile Pink and Chum salmon (Oncorhynchus keta) migrating to sea before the adults returned, and as the two age cohorts mingled. Adult Pink Salmon carried an average of 9.89 (SE 0.90) gravid lice per fish, and thus were capable of infecting the adjacent juveniles. Salinity and temperature remained favourable to Sea Louse reproduction throughout the study. However, all accepted measures of Sea Louse infestation failed to show significant increase on the juvenile salmon, either in overall abundance of Sea Lice or of the initial infective-stage juvenile lice, while the adult wild salmon were present in the study area. This study suggests that even during periods of peak interaction, wild adult salmon are not the primary source of the recent and unprecedented infestations of Sea Lice on juvenile Pacific Pink and Chum salmon in the inshore waters of British Columbia.

Sign in / Sign up

Export Citation Format

Share Document