scholarly journals Mitotic instability in triploid and tetraploid one-year-old eastern oyster, Crassostrea virginica, assessed by cytogenetic and flow cytometry techniques

Genome ◽  
2018 ◽  
Vol 61 (2) ◽  
pp. 79-89 ◽  
Author(s):  
Joana Teixeira de Sousa ◽  
Standish K. Allen ◽  
Brittany M. Wolfe ◽  
Jessica Moss Small
Keyword(s):  
Flow Cytometry ◽  
Crassostrea Virginica ◽  
Chromosome Instability ◽  
Eastern Oyster ◽  
Chromosome Loss ◽  
Brood Stock ◽  
Oyster Aquaculture ◽  
Mitotic Instability ◽  
Significant Difference ◽  
One Year

For commercial oyster aquaculture, triploidy has significant advantages. To produce triploids, the principal technology uses diploid × tetraploid crosses. The development of tetraploid brood stock for this purpose has been successful, but as more is understood about tetraploids, it seems clear that chromosome instability is a principal feature in oysters. This paper is a continuation of work to investigate chromosome instability in polyploid Crassostrea virginica. We established families between tetraploids—apparently stable (non-mosaic) and unstable (mosaic)—and normal reference diploids, creating triploid groups, as well as tetraploids between mosaic and non-mosaic tetraploids. Chromosome loss was about the same for triploid juveniles produced from either mosaic or non-mosaic tetraploids or from either male or female tetraploids. However, there was a statistically significant difference in chromosome loss in tetraploid juveniles produced from mosaic versus non-mosaic parents, with mosaics producing more unstable progeny. These results confirm that chromosome instability, as manifested in mosaic tetraploids, is of little concern for producing triploids, but it is clearly problematic for tetraploid breeding. Concordance between the results from cytogenetics and flow cytometry was also tested for the first time in oysters, by assessing the ploidy of individuals using both techniques. Results between the two were non-concordant.

scholarly journals Aneuploid progeny of the American oyster, Crassostrea virginica, produced by tetraploid × diploid crosses: another example of chromosome instability in polyploid oysters

Genome ◽  
2016 ◽  
Vol 59 (5) ◽  
pp. 327-338 ◽  
Author(s):  
Joana Teixeira de Sousa ◽  
Standish K. Allen ◽  
Haley Baker ◽  
Joseph L. Matt
Keyword(s):  
Crassostrea Virginica ◽  
Chromosome Instability ◽  
Eastern Oyster ◽  
Commercial Production ◽  
Chromosome Loss ◽  
Chromosome Counts ◽  
Cell Stage ◽  
Regular Feature ◽  
Diploid Female ◽  
Diploid Control

The commercial production of triploids, and the creation of tetraploid broodstock to support it, has become an important technique in aquaculture of the eastern oyster, Crassostrea virginica. Tetraploids are produced by cytogenetic manipulation of embryos and have been shown to undergo chromosome loss (to become a mosaic) with unknown consequences for breeding. Our objective was to determine the extent of aneuploidy in triploid progeny produced from both mosaic and non-mosaic tetraploids. Six families of triploids were produced using a single diploid female and crossed with three mosaic and non-mosaic tetraploid male oysters. A second set of crosses was performed with the reciprocals. Chromosome counts of the resultant embryos were tallied at 2–4 cell stage and as 6-hour(h)-old embryos. A significant level of aneuploidy was observed in 6-h-old embryos. For crosses using tetraploid males, aneuploidy ranged from 53% to 77% of observed metaphases, compared to 36% in the diploid control. For crosses using tetraploid females, 51%–71% of metaphases were aneuploidy versus 53% in the diploid control. We conclude that somatic chromosome loss may be a regular feature of early development in triploids, and perhaps polyploid oysters in general. Other aspects of chromosome loss in polyploid oysters are also discussed.

GENETICS OF GROWTH RATE IN OYSTERS AND ITS IMPLICATIONS FOR AQUACULTURE

1981 ◽  
Vol 23 (1) ◽  
pp. 119-130 ◽  
Author(s):  
Shiva M. Singh ◽  
E. Zouros
Keyword(s):  
Growth Rate ◽  
Crassostrea Virginica ◽  
Genetic Improvement ◽  
Large Scale ◽  
Genetic Manipulation ◽  
Limiting Factor ◽  
Oyster Aquaculture ◽  
Two Samples ◽  
One Year ◽  
Two Populations

Two samples of one-year-old American oysters (Crassostrea virginica Gmelin) obtained from the same inlet two years apart and grown under identical conditions were analyzed for their weight distribution and electrophoretic profiles at several enzyme loci. Although growth in the two years was significantly different, the electrophoretic profiles of the two populations were remarkably similar. On both occasions heterozygosity was positively correlated with mean weight and negatively correlated with the coefficient of variation. In general there was a deficiency of heterozygotes. This deficiency was more pronounced in the slow-growers than in the fast-growers. These observations suggest that growth rate (a limiting factor in current oyster aquaculture) can be improved by genetic manipulation. Use of large scale electrophoretic survey in providing guidelines for genetic improvement are discussed.

scholarly journals Statistical Analysis of GLCM Texture Features and Microstructures in SEM Images of Crassostrea virginica Exposed to Atrazine

10.29007/59bk ◽  
2019 ◽  
Author(s):  
Abia Khan ◽  
Kavery Nivana Theethira Poonacha ◽  
Adrian Britt ◽  
Benjamin McSweeney ◽  
Nicolette Santos ◽  
...  
Keyword(s):  
Crassostrea Virginica ◽  
Statistical Significance ◽  
Texture Features ◽  
Oyster Shell ◽  
Marine Species ◽  
Eastern Oyster ◽  
T Test ◽  
Sem Images ◽  
Significant Difference ◽  
High Concentrations

The Eastern oyster, Crassostrea virginica, influences a range of economic and ecological systems. The effects of agricultural runoffs, such as the herbicide atrazine, on marine species, has not been well documented. To analyze the effect of atrazine, the oyster shell surface was analyzed. The shell protects the internal organs from predators. The shells of adult oysters are also required in the spawning of new oysters. This study analyzed the effects of atrazine on oyster shells using Scanning Electron Microscopy (SEM). SEM images were taken of juvenile oysters exposed to three different concentrations of atrazine (30, 10, 3 μg/L) to determine if there is a statistical significance in microstructure frequencies and GLCM texture features of three regions of the shell. Using a multivariate t-test, a significant difference was found in the texture features of the edge regions of the shells treated with 30μg/L and 0 μg/L of atrazine. The same t-test found a significant difference in microstructures near the edge regions for shells treated with 10μg/L and 0 μg/L of atrazine. These results provide computational strategies to distinguish shells treated with high concentrations of atrazine. Future work will tie evidence collected from imaging analysis into transcriptome data to illustrate the genetic impacts of atrazine exposure.

scholarly journals Regulation of sperm motility in Eastern oyster (Crassostrea virginica) spawning naturally in seawater with low salinity

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0243569
Author(s):  
Zoe G. Nichols ◽  
Scott Rikard ◽  
Sayyed Mohammad Hadi Alavi ◽  
William C. Walton ◽  
Ian A. E. Butts
Keyword(s):  
Crassostrea Virginica ◽  
Sperm Motility ◽  
Eastern Oyster ◽  
Fertilization Success ◽  
Channel Blockers ◽  
Physiological Mechanisms ◽  
Ambient Seawater ◽  
Low Salinity ◽  
Oyster Aquaculture ◽  
Term Storage

Oyster aquaculture is expanding worldwide, where many farms rely on seed produced by artificial spawning. As sperm motility and velocity are key determinants for fertilization success, understanding the regulation of sperm motility and identifying optimal environmental conditions can increase fertility and seed production. In the present study, we investigated the physiological mechanisms regulating sperm motility in Eastern oyster,Crassostrea virginica. Sperm motility was activated in ambient seawater with salinity 4–32 PSU with highest motility and velocity observed at 12–24 PSU. In artificial seawater (ASW) with salinity of 20 PSU, sperm motility was activated at pH 6.5–10.5 with the highest motility and velocity recorded at pH 7.5–10.0. Sperm motility was inhibited or totally suppressed in Na+, K+, Ca2+, and Mg2+-free ASW at 20 PSU. Applications of K+(500 μM glybenclamide and 10–50 mM 4-aminopyridine), Ca2+(1–50 μM mibefradil and 10–200 μM verapamil), or Na+(0.2–2.0 mM amiloride) channel blockers into ASW at 20 PSU inhibited or suppressed sperm motility and velocity. Chelating extracellular Ca2+ions by 3.0 and 3.5 mM EGTA resulted in a significant reduction and full suppression of sperm motility by 4 to 6 min post-activation. These results suggest that extracellular K+, Ca2+, and Na+ions are involved in regulation of ionic-dependent sperm motility in Eastern oyster. A comparison with other bivalve species typically spawning at higher salinities or in full-strength seawater shows that ionic regulation of sperm motility is physiologically conserved in bivalves. Elucidating sperm regulation inC.virginicahas implications to develop artificial reproduction, sperm short-term storage, or cryopreservation protocols, and to better predict how changes in the ocean will impact oyster spawning dynamics.

Risk of venous thromboembolism following surgical treatment of superficial venous incompetence

VASA ◽  
2017 ◽  
Vol 46 (6) ◽  
pp. 484-489 ◽  
Author(s):  
Tom Barker ◽  
Felicity Evison ◽  
Ruth Benson ◽  
Alok Tiwari
Keyword(s):  
Venous Thromboembolism ◽  
Varicose Vein ◽  
Lower Incidence ◽  
Varicose Veins ◽  
Secondary Data ◽  
Foam Sclerotherapy ◽  
Increased Risk ◽  
Significant Difference ◽  
Chi Squared ◽  
One Year

Abstract. Background: The invasive management of varicose veins has a known risk of post-operative deep venous thrombosis and subsequent pulmonary embolism. The aim of this study was to evaluate absolute and relative risk of venous thromboembolism (VTE) following commonly used varicose vein procedures. Patients and methods: A retrospective analysis of secondary data using Hospital Episode Statistics database was performed for all varicose vein procedures performed between 2003 and 2013 and all readmissions for VTE in the same patients within 30 days, 90 days, and one year. Comparison of the incidence of VTEs between procedures was performed using a Pearson’s Chi-squared test. Results: In total, 261,169 varicose vein procedures were performed during the period studied. There were 686 VTEs recorded at 30 days (0.26 % incidence), 884 at 90 days (0.34 % incidence), and 1,246 at one year (0.48 % incidence). The VTE incidence for different procedures was between 0.15–0.35 % at 30 days, 0.26–0.50 % at 90 days, and 0.46–0.58 % at one year. At 30 days there was a significantly lower incidence of VTEs for foam sclerotherapy compared to other procedures (p = 0.01). There was no difference in VTE incidence between procedures at 90 days (p = 0.13) or one year (p = 0.16). Conclusions: Patients undergoing varicose vein procedures have a small but appreciable increased risk of VTE compared to the general population, with the effect persisting at one year. Foam sclerotherapy had a lower incidence of VTE compared to other procedures at 30 days, but this effect did not persist at 90 days or at one year. There was no other significant difference in the incidence of VTE between open, endovenous, and foam sclerotherapy treatments.

Levels of Prothrombin Fragment F1+2 in Patients with Hyperhomocysteinemia and a History of Venous Thromboembolism

1997 ◽  
Vol 78 (05) ◽  
pp. 1327-1331 ◽  
Author(s):  
Paul A Kyrle ◽  
Andreas Stümpflen ◽  
Mirko Hirschl ◽  
Christine Bialonczyk ◽  
Kurt Herkner ◽  
...  
Keyword(s):  
Venous Thromboembolism ◽  
Thrombin Generation ◽  
Oral Anticoagulant Therapy ◽  
Oral Anticoagulants ◽  
Control Group ◽  
Prothrombin Fragment ◽  
Hemostatic System ◽  
Significant Difference ◽  
System Activation ◽  
One Year

SummaryIncreased thrombin generation occurs in many individuals with inherited defects in the antithrombin or protein C anticoagulant pathways and is also seen in patients with thrombosis without a defined clotting abnormality. Hyperhomocysteinemia (H-HC) is an important risk factor of venous thromboembolism (VTE). We prospectively followed 48 patients with H-HC (median age 62 years, range 26-83; 18 males) and 183 patients (median age 50 years, range 18-85; 83 males) without H-HC for a period of up to one year. Prothrombin fragment Fl+2 (Fl+2) was determined in the patient’s plasma as a measure of thrombin generation during and at several time points after discontinuation of secondary thromboprophylaxis with oral anticoagulants. While on anticoagulants, patients with H-HC had significantly higher Fl+2 levels than patients without H-HC (mean 0.52 ± 0.49 nmol/1, median 0.4, range 0.2-2.8, versus 0.36 ± 0.2 nmol/1, median 0.3, range 0.1-2.1; p = 0.02). Three weeks and 3,6,9 and 12 months after discontinuation of oral anticoagulants, up to 20% of the patients with H-HC and 5 to 6% without H-HC had higher Fl+2 levels than a corresponding age- and sex-matched control group. 16% of the patients with H-HC and 4% of the patients without H-HC had either Fl+2 levels above the upper limit of normal controls at least at 2 occasions or (an) elevated Fl+2 level(s) followed by recurrent VTE. No statistical significant difference in the Fl+2 levels was seen between patients with and without H-HC. We conclude that a permanent hemostatic system activation is detectable in a proportion of patients with H-HC after discontinuation of oral anticoagulant therapy following VTE. Furthermore, secondary thromboprophylaxis with conventional doses of oral anticoagulants may not be sufficient to suppress hemostatic system activation in patients with H-HC.

Effects of resuspension of eastern oyster Crassostrea virginica biodeposits on phytoplankton community structure

2020 ◽  
Vol 640 ◽  
pp. 79-105
Author(s):  
ET Porter ◽  
E Robins ◽  
S Davis ◽  
R Lacouture ◽  
JC Cornwell
Keyword(s):  
Water Quality ◽  
Community Structure ◽  
Crassostrea Virginica ◽  
Skeletonema Costatum ◽  
Eastern Oyster ◽  
Energy Dissipation Rate ◽  
Negative Effects ◽  
Cell Densities ◽  
Sediment Bottom ◽  
Nitrite Nitrate

Anthropogenic disturbances in the Chesapeake Bay (USA) have depleted eastern oyster Crassostrea virginica abundance and altered the estuary’s environment and water quality. Efforts to rehabilitate oyster populations are underway; however, the effect of oyster biodeposits on water quality and plankton community structure are not clear. In July 2017, we used 6 shear turbulence resuspension mesocosms (STURMs) to determine differences in plankton composition with and without the daily addition of oyster biodeposits to a muddy sediment bottom. STURM systems had a volume-weighted root mean square turbulent velocity of 1.08 cm s-1, energy dissipation rate of ~0.08 cm2 s-3, and bottom shear stress of ~0.36-0.51 Pa during mixing-on periods during 4 wk of tidal resuspension. Phytoplankton increased their chlorophyll a content in their cells in response to low light in tanks with biodeposits. The diatom Skeletonema costatum bloomed and had significantly longer chains in tanks without biodeposits. These tanks also had significantly lower concentrations of total suspended solids, zooplankton carbon, and nitrite +nitrate, and higher phytoplankton carbon concentrations. Results suggest that the absence of biodeposit resuspension initiates nitrogen uptake for diatom reproduction, increasing the cell densities of S. costatum. The low abundance of the zooplankton population in non-biodeposit tanks suggests an inability of zooplankton to graze on S. costatum and negative effects of S. costatum on zooplankton. A high abundance of the copepod Acartia tonsa in biodeposit tanks may have reduced S. costatum chain length. Oyster biodeposit addition and resuspension efficiently transferred phytoplankton carbon to zooplankton carbon, thus supporting the food web in the estuary.

Comparative Study between Endoscopic Aided Septoplasty with Two Handed Technique using Endoholder and Conventional Septoplasty

2020 ◽  
Vol 16 (3) ◽  
Author(s):  
Apar Pokharel ◽  
Naganawalachullu Jaya Prakash Mayya ◽  
Nabin Gautam
Keyword(s):  
Comparative Study ◽  
Nasal Septum ◽  
Deviated Nasal Septum ◽  
Endoscopic Septoplasty ◽  
Septal Surgery ◽  
Significant Difference ◽  
Common Causes ◽  
Prospective Comparative Study ◽  
Evolutionary Step ◽  
One Year

Introduction: Deviated nasal septum is one of the most common causes for the nasal obstruction. The objective of this study is to compare the surgical outcomes in patients undergoing conventional septoplasty and endoscopic septoplasty in the management of deviated nasal septum. Methods:  Prospective comparative study was conducted on 60 patients who presented to the Department of ENT, College of Medical sciences, during a period of one year. The severity of the symptoms was subjectively assessed using NOSE score and objectively assessed using modified Gertner plate. Results: There was significant improvement in functional outcome like NOSE Score and area over the Gertner plate among patients who underwent endoscopic septoplasty. Significant difference in incidence of post-operative nasal synechae and haemorrhage was seen in conventional group compared to endoscopic group. Conclusions: Endoscopic surgery is an evolutionary step towards solving the problems related to deviated nasal septum. It is safe, effective and conservative, alternative to conventional septal surgery.

EVALUTING THE EFFECTS OF EARLY INTERVENTION PROGRAM FOR CHILDREN WITH DEVELOPMENTAL DISABILITIES IN COMMUNITY

2011 ◽  
pp. 70-76
Author(s):  
Keyword(s):  
Social Cognition ◽  
Early Intervention ◽  
Developmental Delay ◽  
Intervention Program ◽  
Language Skills ◽  
Early Intervention Program ◽  
Self Help ◽  
Home Based ◽  
Significant Difference ◽  
One Year

Objectives: To evualate the effects of early intervention program after one year for 33 disabled children in Hue city in 2010. Objects and Methods: Conduct with practical work and assessment on developing levels at different skills of the children with developmental delay under 6 years old who are the objects of the program. Results: With the Portage checklist used as a tool for implementing the intervention at the community and assessing developing skills on Social, Cognition, Motor, Self-help and Language skills for children with developmental delay, there still exists significant difference (p ≤ 0.05) at developing level of all areas in the first assessment (January, 2010) and the second assessment (December, 2010) after 12 months. In comparison among skills of different types of disabilities, there is significant difference of p ≤ 0.05 of social, cognition and language skills in the first assessment and of social, cognition, motor and language skills in the second assessment. Conclusion: Home-based Early Intervention Program for children with developmental delay has achieved lots of progress in improving development skills of the children and enhancing the parents’ abilities in supporting their children at home.

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