Nucleolar Cycle and Its Correlation with Chromatoid Bodies in the Tilapia rendalli (Teleostei, Cichlidae) Spermatogenesis

2010 ◽  
Vol 293 (5) ◽  
pp. 900-910 ◽  
Author(s):  
Rita Luiza Peruquetti ◽  
Sebastião Roberto Taboga ◽  
Maria Tercília Vilela De Azeredo-Oliveira
Keyword(s):  
Tilapia Rendalli ◽  
Chromatoid Bodies ◽  
Nucleolar Cycle

Commercial-scale aquaculture of tilapia species in Zambia.

2020 ◽  
Author(s):  
Douglas Flynn
Keyword(s):  
Oreochromis Niloticus ◽  
Inorganic Compound ◽  
Chicken Manure ◽  
Green Water ◽  
Commercial Scale ◽  
Tilapia Rendalli ◽  
Productive System ◽  
Dominant Fish ◽  
Initial Scheme

Abstract This case study describes the piloting and subsequent commercialization of an integrated pig and fish operation in Zambia. The initial scheme began in October 1981 using indigenous Zambian species including Oreochromis andersonii, Oreochromis macrochir and Tilapia rendalli. Different fertilization techniques were trialled, including organic (chicken manure) and inorganic (compound) fertilisers, and different integration systems were tested; ducks over fish and pigs over fish. Over the 29 years the project has been running, the variety of methods originally trialled have been refined to the extremely productive system in place today. Oreochromis niloticus is the dominant fish species produced, and members of the Clarias genus used as the main predator. The hatchery has been intensified (and now incorporates mono-sexing), aeration systems have been implemented in grow-out ponds and a green-water floating fish pellet has been developed. Yields have increased from an initial average of 2.5 to 3 tons/ha to present yields of over 11 tons/ha. The initial five hectare project has grown to over 45 ha of water producing over 600 tons of fish a year, and a stable herd of 200 sows producing in excess of 4100 slaughter stock per annum.

The nucleolar cycle in man

1977 ◽  
Vol 25 (1) ◽  
pp. 103-110
Author(s):  
M. Anastassova-Kristeva
Keyword(s):  
Gene Expression ◽  
Mitotic Division ◽  
Tissue Cultures ◽  
Nucleolar Number ◽  
Satellite Chromosomes ◽  
Nucleolar Cycle ◽  
Group D ◽  
Secondary Constrictions ◽  
Nucleolus Organizers

Tissue cultures of human embryonal kidney and ovary were examined. In the nuclei of both tissues, one to ten nucleoli have been found. The maximum number of nucleoli is connected with the gene expression of rDNA of the 10 nucleolus organizers of chromosome pairs Nos. 13, 14, 15, 21 and 22, which have secondary constrictions and are the satellite chromosomes in man. The small percentage of cells with 10, 9 and 8 nucleoli is attributed to the rapid association of 3 of the homologous acrocentrics (perhaps of group D). Two of the satellite (SAT) pairs probably associate later after mitosis. The process of fusion is dynamic, resulting in one interphase nucleous—a manifestation of the association of all SAT chromosomes. Dissociation of the nucleolus occurs upon entering prophase, due to the condensation of the chromosomes and retreat of rDNA to the respective secondary constrictions. As a result, the nucleolar number increases again. The pattern of the nucleolar kinetics within the course of one mitotic division is described.

A case study of GK Aqua Farms in Chikwawa district, Malawi.

2020 ◽  
Author(s):  
Priscilla M Longwe ◽  
Jeremiah Kang'ombe ◽  
Emmanuel K. W. Kaunda
Keyword(s):  
Common Carp ◽  
Wholesale Price ◽  
Production Cycle ◽  
Integrated Aquaculture ◽  
Distribution Strategy ◽  
Tilapia Rendalli ◽  
One Year ◽  
Gross Margins ◽  
Agriculture Systems

Abstract This study was carried out to record the experiences of Gopi Krishna (GK) Aqua Farms, with special reference to feeding/fertilization methods, the production cycle and the farm's marketing/distribution strategy. GK Aqua Farms is situated in Chikwawa District, which is in the southern region of Malawi. 19 ha (47 acres) of its land is under water, about 12 ha (30 acres) of which is in an enclosed, fenced area, and the remaining 7 ha (17 acres) in an open, unfenced area. Since GK Aqua Farms started practicing on a commercial scale in November 2004, the business has promoted aquaculture within Malawi and has demonstrated its potential profitability by attaining gross margins of over K3 million (approximately US $21,430) after just one year. The farm raises three species of fish in a polyculture system; common carp (Cyprinus carpio), Tilapia rendalli and Oreochromis siranus. The fish are sold in Chikwawa District as well as in the neighbouring city of Blantyre. The fish are fed artificial diets and are stocked in ponds that are mainly fertilized with livestock manure. Partial harvests are carried out throughout the year, depending on consumer demand, with a complete harvest once a year. The fish are sold at a farm gate price of K400/kg (US $3/kg) for common carp and K250/kg (US $1.8/kg) for tilapia species and at a wholesale price of K500 (US $3.6/kg) for common carp and K300 (US $2.1/kg) for both tilapia species. Since it took over the farm in 2004, GK Aqua Farms has had a continuous rise in production from 4.2 tonnes per year in 2004 to 29.5 tonnes per year in 2008 with an expectation of similar increases over the next few years. The farm faces several problems including pests, inefficient feed supply and low sales during summer. The farm, however, does not operate any integrated aquaculture-agriculture systems.

Sign in / Sign up

Export Citation Format

Share Document