A Possible Constraint to High-Density Culture of Male Common Snapping Turtles Chelydra serpentina at Consistently Warm Temperatures

A northern population of snapping turtles (Chelydra serpentina) centred around Lake Sasajewun in the Wildlife Research Area in Algonquin Park, Ontario, has been studied and individually marked since 1972. From 1972 to 1985, annual mortality and survivorship of adult females had been estimated at 1 and 96.6%, respectively, and only six dead turtles were found. Lake Sasajewun's population of C. serpentina was estimated in 1978–1979 and 1984–1985 at 38 and 47 adults, respectively. From 1976 to 1987, total number of nests found in the study area remained fairly constant and there were no significant changes in mean clutch size, mean clutch mass, or mean egg mass. On the main nest site, recruitment from 1976 to 1987 was 1.15 (1.8%) new females per year. From 1987 to 1989, we found 34 dead adult snapping turtles in the Wildlife Research Area. Observations of freshly dead animals indicated that most were killed by otters (Lutra canadensis) during the turtles' winter hibernation. A few uninjured turtles also died of septicemia in early spring shortly after emerging from hibernation. The estimated number of adults in Lake Sasajewun was 31 in 1988–1989, and the minimum number of adult residents known to be alive in the lake dropped from 47 in 1986 to 16 in 1989. In 1986 and 1987, annual adult female survivorship was estimated at 80 and 55%, respectively, and estimated numbers of nesting females declined from 82 in 1986 to 71 and 55 in 1987 and 1988, respectively. The actual number of nests found declined by 38 and 20% over the same periods. Although no significant differences occurred in mean egg mass or mean clutch size between 1987 and 1989 and earlier years, the mean clutch mass in 1988 was larger than in 1977 or 1978. This difference appeared to be due to a gradual increase in the mean age and body size of breeding females rather than to density-dependent changes. Recruitment into the adult breeding female population in 1987–1989 remained less than two individuals per year. Hatchling survival and number of juveniles were low throughout the study. Our observations support the view that populations of species with high, stochastic juvenile mortality and long adult life spans may be decimated quickly by increased mortality of adult animals, particularly if numbers of juveniles and immigrants are low. Recovery of such populations should be very slow because of a lack of effective density-dependent response in reproduction and recruitment.

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High Density Culture of Immuno-Magnetically Separated Human Mammary Luminal Cells

Intercellular Signalling in the Mammary Gland ◽

10.1007/978-1-4615-1973-7_11 ◽

1995 ◽

pp. 75-76

Author(s):

Catherine Clarke ◽

Paul Monaghan ◽

Michael J. O’Hare

Keyword(s):

High Density ◽

High Density Culture ◽

Luminal Cells

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YAP Promotes Cell Proliferation and Stemness Maintenance of Porcine Muscle Stem Cells under High-Density Condition

Cells ◽

10.3390/cells10113069 ◽

2021 ◽

Vol 10 (11) ◽

pp. 3069

Author(s):

Zheng Liu ◽

Ling Lin ◽

Haozhe Zhu ◽

Zhongyuan Wu ◽

Xi Ding ◽

...

Keyword(s):

Stem Cells ◽

Cell Proliferation ◽

Large Scale ◽

High Density ◽

Meat Production ◽

Density Condition ◽

High Density Culture ◽

Differentiation Potential ◽

Muscle Stem Cells ◽

Cultured Meat

Muscle stem cells (MuSCs) isolated ex vivo are essential original cells to produce cultured meat. Currently, one of the main obstacles for cultured meat production derives from the limited capacity of large-scale amplification of MuSCs, especially under high-density culture condition. Here, we show that at higher cell densities, proliferation and differentiation capacities of porcine MuSCs are impaired. We investigate the roles of Hippo-YAP signaling, which is important regulators in response to cell contact inhibition. Interestingly, abundant but not functional YAP proteins are accumulated in MuSCs seeded at high density. When treated with lysophosphatidic acid (LPA), the activator of YAP, porcine MuSCs exhibit increased proliferation and elevated differentiation potential compared with control cells. Moreover, constitutively active YAP with deactivated phosphorylation sites, but not intact YAP, promotes cell proliferation and stemness maintenance of MuSCs. Together, we reveal a potential molecular target that enables massive MuSCs expansion for large-scale cultured meat production under high-density condition.

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Hyper-intensive farming white shrimp Litopenaeus vannamei (Decapoda: Penaeidae) in a seawater tank under semi-controlled conditions

UNED Research Journal ◽

10.22458/urj.v5i1.249 ◽

2013 ◽

Vol 5 (1) ◽

pp. 69-74

Author(s):

A. A. Ortega-Salas ◽

L. A. Rendón M.

Keyword(s):

Litopenaeus Vannamei ◽

Maximum Likelihood Method ◽

High Density ◽

White Shrimp ◽

Likelihood Method ◽

Food Conversion ◽

High Density Culture ◽

Intensive Farming ◽

Controlled Conditions ◽

Commercial Size

Shrimp development to a commercial size in high density culture saves food and avoids predators and disease. Our study was conducted to calculate the growth of white shrimp Litopenaeus vannamei by hyper-intensive cultivation under semi-controlled conditions. We seeded at a density of 550 shrimp per m3 during the first cycle and 400 shrimp per m3 in the second cycle in an outdoor tank of 6m3or 6m2 covered with mesh, constant aeration. The shrimp were fed Artemia franciscana during the first two weeks and camaronina pellets (35% protein) as required, in food baskets, aftterwards. The temperature ranged from 22,3 to 31,3°C, pH 7,5-8,7, oxygen 4,26±1,43. The tanks are siphoned of debris every other day, and water was replaced according to a program. The food conversion ratio (FCR) was 1:1,3. The shrimp were measured weekly to calculate growth with the Bertalanffy model. Survival in the first cycle was 95,8 ( 97,9% for the second cycle). Population parameters (maximum likelihood method) for the first cycle were k=0,0301, L∞ =322,16 and t0 =-0,8852; second cycle: k=0,0203, L∞ =294,42 and t0 =-5,3771. There was rapid growth during the first 10 weeks. Biomass was 27kg for the first cycle (second: 16kg). KEY WORDSGrowth, high density, survival, biomass, semi-controlled conditions.

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