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Trends Genet,
1999]
The genome sequence of the free-living nematode Caenorhabiditis elegans is nearly complete, with resolution of the final difficult regions expected over the next few months. This will represent the first genome of a multicellular organism to be sequenced to completion. The genome is approximately 97 Mb in total, and encodes more than 19 099 proteins, considerably more than expected before sequencing began. The sequencing project - a collaboration between the Genome Sequencing Center in St Louis and the Sanger Centre in Hinxton - has lasted eight years, with the majority of the sequence generated in the past four years. Analysis of the genome sequence is just beginning and represents an effort that will undoubtedly last more than another decade. However, some interesting findings are already apparent, indicating that the scope of the project, the approach taken, and the usefulness of having the genetic blueprint for this small organism have been well worth the effort.
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Hist Philos Life Sci,
2000]
The transformation of embryology to developmental biology has been linked to the introduction of experimental approaches from molecular genetics to the study of development. This paper pursues this theme by analyzing the tools molecular biologists, moving from phage and bacterial genetics to the study of development in higher organisms, brought to their new field of investigations. The paper focuses on Sydney Brenner's move from molecular genetics to developmental biology. His attempt to turn the nematode worm Caenorhabditis elegans into a new tool for the study of development included a vast and ever expanding mapping program. Worm workers themselves did not distinguish sharply between mapping on the cellular, chromosomal or molecular level. Mapping, the paper argues, or more generally 'analytical/comparative' next to 'experimentalist' approaches (Pickstone) were not only part and parcel of Brenner's strategy to 'molecularize' the study of development, but also played a crucial role in 'classical' molecular biology.
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Philos Trans R Soc Lond B Biol Sci,
2015]
The article 'Structure of the nervous system of the nematode Caenorhabditis elegans' (aka 'The mind of a worm') by White et al., published for the first time the complete set of synaptic connections in the nervous system of an animal. The work was carried out as part of a programme to begin to understand how genes determine the structure of a nervous system and how a nervous system creates behaviour. It became a major stimulus to the field of C. elegans research, which has since contributed insights into all areas of biology. Twenty-six years elapsed before developments, notably more powerful computers, made new studies of this kind possible. It is hoped that one day knowledge of synaptic structure, the connectome, together with results of many other investigations, will lead to an understanding of the human brain. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society.
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Ecol Dis,
1983]
Medical records concerning filarial diseases in Ceylon date from the account of Davy[1], though there are hints as to the more obvious manifestations in the old chronicles of the country, too. A first survey was conducted in 1912/1913 concentrating on urban areas, followed by a second survey in the 1930s with emphasis on the rural parts. The results displayed a remarkable distribution pattern: Wuchereria bancrofti, the so-called "urban type", concentrated in Galle and Matara towns, whereas Brugia malayi, the "rural type", widespread along the southwest coast from Matara to Negombo, plus isolated pockets in the northwest, central north, east and south. The survey of the 1930s lead to the supposition that the occurrence of B. malayi must have something to do with the distribution of certain water plants, a suspicion later on confirmed in that Pistia stratiotes in particular--but other water plants as well--are essential for the survival of the vector (Taeniorhynchus (Mansonia) uniformis) during its early (submersed) stages of development. A determined effort to remove the water plants from tanks etc. reduced the rural type with encouraging results. At the same time, a combination of factors, in particular the war-time sojourn of masses of troops from Africa, already infected by filarial diseases, in the southwestern coastal areas triggered off an unexpected spread of the urban type out of its early "bridge-heads" in Galle and Matara towns to invade the southwest coastal areas, and, later on, supported by increased population mobility, to advance further inland too. At present, there is no remedy within sight to give some hope to come to grips with this problem as the vector, Culex pipiens fatigans, is ubiquitous and finds suitable breeding grounds practically everywhere. Research into the history of filarial diseases in Ceylon points as far as B. malayi is concerned, to an invasion by a Malayan army under the Kalinga kings during the days of close relations between Ceylon and southeast Asia, i.e. during the 12th and 13th centuries, and as far as W. bancrofti is concerned, a Chinese army, invading the southern coast in the early 15th century, is made responsible. Filarial diseases in Ceylon present a particular interesting case of geomedical research; but inspite of encouraging results in fighting the rural type, i.e. B. malayi, the urban type, W. bancrofti, seems to remain a problem of public health in the island for the forseeable future.