26.4. Hypoxia alters sex hormones, sex ratio and favors a male-dominated population in fish

Shang, E.; Yu, Richard Man Kit; Wu, Rudolf S.S.

doi:10.1016/j.cbpa.2007.06.294

Cited by 2 publications

(2 citation statements)

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“…Another environmental factor that is known to have an effect on zebrafish sex ratio is oxygen level [92] . It was found that under hypoxic conditions there was a reduction of estrogen synthesis leading to an increase of androgen to estrogen ratio which favors male development [93] . However, the decreased oxygen level had only limited effect on the sex ratio of zebrafish leading to higher percentage of males (12.5% differences) [92] .…”

Section: Discussionmentioning

confidence: 99%

Polygenic Sex Determination System in Zebrafish

et al. 2012

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BackgroundDespite the popularity of zebrafish as a research model, its sex determination (SD) mechanism is still unknown. Most cytogenetic studies failed to find dimorphic sex chromosomes and no primary sex determining switch has been identified even though the assembly of zebrafish genome sequence is near to completion and a high resolution genetic map is available. Recent publications suggest that environmental factors within the natural range have minimal impact on sex ratios of zebrafish populations. The primary aim of this study is to find out more about how sex is determined in zebrafish.Methodology/Principal FindingsUsing classical breeding experiments, we found that sex ratios across families were wide ranging (4.8% to 97.3% males). On the other hand, repeated single pair crossings produced broods of very similar sex ratios, indicating that parental genotypes have a role in the sex ratio of the offspring. Variation among family sex ratios was reduced after selection for breeding pairs with predominantly male or female offspring, another indication that zebrafish sex is regulated genetically. Further examinations by a PCR-based “blind assay" and array comparative genomic hybridization both failed to find universal sex-linked differences between the male and female genomes. Together with the ability to increase the sex bias of lines by selective breeding, these data suggest that zebrafish is unlikely to utilize a chromosomal sex determination (CSD) system.Conclusions/SignificanceTaken together, our study suggests that zebrafish sex is genetically determined with limited, secondary influences from the environment. As we have not found any sign for CSD in the species, we propose that the zebrafish has a polygenic sex determination system.

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Section: Discussionmentioning

confidence: 99%

Polygenic Sex Determination System in Zebrafish

et al. 2012

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“…In many situations stable oscillations, chaotic fluctuations, or even population extinction can be the likely outcome when a sex ratio is perturbed (Caswell and Weeks 1986). One relationship found by Shang et al (2007) was that hypoxic conditions favored sex ratios dominated by male populations. The lack of dissolved oxygen is a prevalent problem in the West Branch (TP Simon [unpublished data]).…”

Section: Sex Ratio Evolutionary Stable Strategiesmentioning

confidence: 97%

Deformity, Erosion, Lesion, and Tumor Occurrence, Fluctuating Asymmetry, and Population Parameters for Bluntnose Minnow (Pimephales notatus) as Indicators of Recovering Water Quality in a Great Lakes Area of Concern, USA

Simon

Burskey

2016

Arch Environ Contam Toxicol

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The Grand Calumet River is an industrial river and a Great Lakes Area of Concern in southwestern Lake Michigan, USA. Recovery end points require well-formulated designs to assess the use of occurrence of internal and external anomalies, fluctuating asymmetry, and population indicators to determine recovery from the water-quality Beneficial Use Impairments of fish tumors and deformities. A paired-watershed approach using three reaches within the study area was sampled weekly and separated into near- and far-field reaches, whereas the Little Calumet River, Indiana Dunes National Lakeshore, served as a control. Field-collected Pimephales notatus were inspected for occurrence of deformities, erosion, lesion, and tumor (DELT) anomalies, measured for body symmetry, and dissected to ascertain sex and the condition of internal organs. Morphometric measurements (p ≤ 0.000), internal organ conditions (p = 0.001), and sex ratios of the fish (p = 0.001) were significantly different between the control and P. notatus test populations. The near-field individuals had the highest incidence of DELT occurrence (70 %) followed by the far-field reaches at Roxana Marsh (45 %) and Kennedy Avenue (41.9 %). Morphometric analysis showed significant differences between body size and shape and age class structure between populations. No test-reach individual lived to reach age >2 years. Gonads and livers from Grand Calumet individuals were found to be blackened, ruptured, and decreased in thickness. None of the fish from test study reaches displayed sexual structure in a 1:1 ratio. High sediment-contaminant concentrations for polycyclic aromatic hydrocarbon metals in the Grand Calumet River correlated (r (2) = 0.998) with decreased population fitness and decreased individual reproductive health.

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26.4. Hypoxia alters sex hormones, sex ratio and favors a male-dominated population in fish

Cited by 2 publications

References 0 publications

Polygenic Sex Determination System in Zebrafish

Polygenic Sex Determination System in Zebrafish

Deformity, Erosion, Lesion, and Tumor Occurrence, Fluctuating Asymmetry, and Population Parameters for Bluntnose Minnow (Pimephales notatus) as Indicators of Recovering Water Quality in a Great Lakes Area of Concern, USA

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