High genetic diversity of bivalve transmissible neoplasia in the blue mussel Mytilus trossulus Gould from the subarctic Sea of Okhotsk

There are increasing findings of the bivalve transmissible neoplasia derived from the Pacific mussel Mytilus trossulus (MtrBTN) in populations of different Mytilus species worldwide. The Subarctic is an area where this disease has not yet been sought despite the fact that Mytilus spp. are widespread there, and M. trossulus itself is a boreal species. We used cytological and histological techniques to diagnose disseminated neoplasia in a sample of M. trossulus from Magadan in the subarctic Sea of Okhotsk. Neoplasia was identified in 11 of 214 mussels studied. Using mtDNA COI sequencing, we revealed genotypes identical or nearly identical to known MtrBTN ones in the hemolymph of most of the diseased mussels. Both MtrBTN evolutionary lineages have been identified, the widespread MtrBTN2, and MtrBTN1, so far only known from M. trossulus in British Columbia on the other side of the Pacific from Magadan. In addition, MtrBTN2 was represented by two common diverged mtDNA haplolineages. These conclusions have been confirmed for selected cancerous mussels by molecular cloning of COI and additional nuclear and mtDNA genes. On the background of high genetic diversity, different cancers were similar in terms of ploidy (range 4.0 - 5.8n) and nuclear to cell ratio. Our study provides the first description of neoplasia and MtrBTN in mussels from the Sea of Okhotsk and from the Subarctic, of both MtrBTN1 and MtrBTN2 in the same mussel population, and the first direct comparison between these transmissible cancers.

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Native versus invasive crab effluent effects on byssal thread production in the mussel, Mytilus trossulus (Gould, 1950)

The Arbutus Review ◽

10.18357/tar91201818384 ◽

2018 ◽

Vol 9 (1) ◽

pp. 20-31

Author(s):

Rachel Rickaby ◽

Jeanine Sinclair

Keyword(s):

Blue Mussel ◽

Carcinus Maenas ◽

Control Group ◽

Mytilus Trossulus ◽

Byssal Thread ◽

The Pacific ◽

Significant Difference ◽

The Mean ◽

And Control ◽

Mussel Mytilus Trossulus

Mussels have evolved many adaptations to protect themselves, including the production of byssal threads. These are strong, proteinaceous fibres that mussels secrete to adhere themselves to rocks, preventing detachment by waves and predators. These byssal threads may be strengthened if mussels can recognize potential threats, such as native crabs, as their populations have a long history of coevolution. Unfortunately, the introduction of invasive predators poses a challenge for prey, which may not be capable of recognizing them. In this study, byssal thread production in the Pacific blue mussel (Mytilus trossulus ) was observed when exposed to effluent from the native red rock crab (Cancer productus) or the invasive European Green crab (Carcinus maenas). M. trossulus were placed in closed systems with effluent from either C. productus , C. maenas or control (no predator), over a 24-hour time period. Final measurements of number, length and diameter of byssal threads were recorded. M. trossulus exposed to effluent from C. productus produced byssal threads at a statistically significantly faster rate than in the control group over the first 7.5 hours. M. trossulus exposed to effluent from C. maenas produced byssal threads at a statistically significantly faster rate than both the C. productus and control groups. However, after 24 hours, there was no statistically significant difference between the mean number of byssal threads for any treatment. Additionally, we found no statistically significant difference between the mean diameter of byssal threads produced or length of byssal threads produced for any treatment.

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CULTIVATION OF THE PACIFIC MUSSEL MYTILUS TROSSULUS (BIVALVIA: MYTILIDAE) IN MONO-AND POLYCULTURE IN THE NORTHERN PART OF THE SEA OF OKHOTSK

Fisheries ◽

10.37663/0131-6184-2020-6-108-110 ◽

2020 ◽

Vol 2020 (6) ◽

pp. 108-110

Author(s):

Viacheslav Zharnikov ◽

Andrey Smirnov

Keyword(s):

Growth Rate ◽

Sea Of Okhotsk ◽

Age Groups ◽

Maximum Growth ◽

Size Group ◽

Mytilus Trossulus ◽

The Sea Of Okhotsk ◽

The Pacific ◽

Size Groups ◽

Mussel Mytilus Trossulus

The growth of various size groups of mussels in the Veselaya Bay of the tauyskaya Bay, grown in mono - and polyculture in suspended cages in the sea, was analyzed. The maximum growth was observed in mussels of the size group 10-20 mm at the age of 2 years. Shellfish grew more slowly at the age of 3-5 years. The growth rate of mollusks of all size groups in the polyculture was higher than in the monoculture. The percentage of elimination of mussels of all age groups in the polyculture was significantly lower. The forecast of growth of mussels of various size groups in poly - and monoculture in suspended cages in the first, second and third growth seasons in Veselaya Bay is made. The efficiency of cultivation of mussels in the Northern part of the sea of Okhotsk together with other edible mollusks: makoma and Miya is shown.

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Comparison of age-length and growth-increment general growth models of the Schnute type in the Pacific Blue Mussel, Mytilus trossulus Gould

Journal of Experimental Marine Biology and Ecology ◽

10.1016/s0022-0981(01)00292-1 ◽

2001 ◽

Vol 262 (2) ◽

pp. 155-176 ◽

Cited By ~ 11

Author(s):

J Millstein ◽

C.E O'Clair

Keyword(s):

Blue Mussel ◽

Growth Models ◽

Growth Increment ◽

Mytilus Trossulus ◽

General Growth ◽

The Pacific ◽

Mussel Mytilus Trossulus

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Overt and Concealed Genetic Loads Revealed by QTL Mapping of Genotype-dependent Viability in the Pacific Oyster Crassostrea gigas

Genetics ◽

10.1093/genetics/iyab165 ◽

2021 ◽

Author(s):

Xiaoshen Yin ◽

Dennis Hedgecock

Keyword(s):

Genetic Diversity ◽

Crassostrea Gigas ◽

Pacific Oyster ◽

Genetic Load ◽

High Density ◽

High Genetic Diversity ◽

High Fecundity ◽

Recessive Mutations ◽

Genotype Frequencies ◽

The Pacific

Abstract Understanding the genetic bases of inbreeding depression, heterosis, and genetic load is integral to understanding how genetic diversity is maintained in natural populations. The Pacific oyster Crassostrea gigas, like many long-lived plants, has high fecundity and high early mortality (type-III survivorship), manifesting a large, overt, genetic load; the oyster harbors an even greater concealed genetic load revealed by inbreeding. Here, we map viability QTL (vQTL) in six interrelated F2 oyster families, using high-density linkage maps of single nucleotide polymorphisms generated by genotyping-by-sequencing (GBS) methods. Altogether, we detect 70 vQTL and provisionally infer 89 causal mutations, 11 to 20 per family. Genetic mortality caused by independent (unlinked) vQTL ranges from 94.2% to 97.8% across families, consistent with previous reports. High-density maps provide better resolution of genetic mechanisms, however. Models of one causal mutation present in both identical-by-descent (IBD) homozygotes and heterozygotes fit genotype frequencies at 37 vQTL; consistent with the mutation-selection balance theory of genetic load, 20 are highly deleterious, completely recessive mutations and 17 are less deleterious, partially dominant mutations. Another 22 vQTL require pairs of recessive or partially dominant causal mutations, half showing selection against recessive mutations linked in repulsion, producing pseudo-overdominance. Only eight vQTL appear to support the overdominance theory of genetic load, with deficiencies of both IBD homozygotes, but at least four of these are likely caused by pseudo-overdominance. Evidence for epistasis is absent. A high mutation rate, random genetic drift, and pseudo-overdominance may explain both the oyster’s extremely high genetic diversity and a high genetic load maintained primarily by mutation-selection balance.

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Study on the growth rates of mollusks in hanging culture in Possjet Bay (Sea of Japan)

Бюллетень Дальневосточного малакологического общества ◽

10.24866/1560-8425/2020-24/67-81 ◽

2020 ◽

Vol 24 (1/2) ◽

pp. 67-81

Author(s):

Nina I. Grigoryeva

Keyword(s):

Growth Rate ◽

Sea Of Japan ◽

Growth Rates ◽

Crassostrea Gigas ◽

Blue Mussel ◽

Peter The Great Bay ◽

Mytilus Trossulus ◽

Mizuhopecten Yessoensis ◽

Yesso Scallop ◽

Mussel Mytilus Trossulus

Исследована скорость роста культивируемых моллюсков подвесного выращивания в зал. Посьета (зал. Петра Великого, Японское море) за 1970–2011 гг. Приведены ростовые характеристики приморского гребешка (Mizuhopecten yessoensis (Jay, 1857)), тихоокеанской мидии (Mytilus trossulus Gould, 1850) и тихоокеанской (гигантской) устрицы (Crassostrea gigas (Thunberg, 1793)) в течение первых трех лет развития. Методами энтропийного анализа исследованы сроки достижения личинками и спатом определенных размеров. Выявлены временные интервалы и рассчитана вероятность наступления этих сроков. Обсуждается влияние техники культивирования на скорость роста. Ключевые слова: скорость роста, личинки, спат, приморский гребешок Mizuhopecten yessoensis, тихоокеанская мидия Mytilus trossulus, тихоокеанская устрица Crassostrea gigas, залив Посьета, Японское море. The growth rates of cultivated mollusks were studied in Possjet Bay (Peter the Great Bay, Sea of Japan) during 1970–2011. The growth characteristics were presented for the Yesso scallop (Mizuhopecten yessoensis (Jay, 1857)), the blue mussel (Mytilus trossulus Gould, 1850), and the Pacific (giant) oyster (Crassostrea gigas (Thunberg, 1793)) during the first three years of life. The average amount of time of the larvae and spat reaching certain sizes was determined using the method of entropy analysis. The time intervals were identified and the probability of these intervals to happen were also calculated. The influence of the cultivation techniques on the growth rate is discussed. Key words: growth rate, larvae, spat, Yesso scallop Mizuhopecten yessoensis, blue mussel Mytilus trossulus, Pacific oyster Crassostrea gigas, Possjet Bay, Sea of Japan.

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