Lysosomes are found in the cytoplasm of all eucaryotic cells except mature red blood cells. The matrix of the organelle is separated from the surrounding cytoplasm by a trilaminar unit membrane and contains a variety of acid hydrolytic enzymes. Morphologically primary (recently formed from the Golgi-complex) are distinguished from secondary lysosomes. The latter type is formed after fusion of a vacuole with a primary lysosome and is ultrastructurally extremely heterogeneous due to the large variety of substrates (macro molecules ) incorporated in the matrix of the organelle. The acid hydrolases of lysosomes are divided into the following five groups: phosphatases, nucleases, polysaccharide- and glycosaminoglycans (GAG)-liydrolases, proteases and lipases.
{"title":"Physiology and pathophysiology of cell organelles","authors":"J. Theron, N. Claasen, N. Lizamore","doi":"10.4102/satnt.v17i1.686","DOIUrl":"https://doi.org/10.4102/satnt.v17i1.686","url":null,"abstract":"Lysosomes are found in the cytoplasm of all eucaryotic cells except mature red blood cells. The matrix of the organelle is separated from the surrounding cytoplasm by a trilaminar unit membrane and contains a variety of acid hydrolytic enzymes. Morphologically primary (recently formed from the Golgi-complex) are distinguished from secondary lysosomes. The latter type is formed after fusion of a vacuole with a primary lysosome and is ultrastructurally extremely heterogeneous due to the large variety of substrates (macro molecules ) incorporated in the matrix of the organelle. The acid hydrolases of lysosomes are divided into the following five groups: phosphatases, nucleases, polysaccharide- and glycosaminoglycans (GAG)-liydrolases, proteases and lipases.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70512915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Against the background of a changing environment in which market factors and greater world trade and competitiveness are increasingly becoming the only criteria for success, a framework for the analysis of world competitiveness is initially developed. This is followed by a discussion on the growth of productivity in agriculture, as well as an exposition of the role of agricultural research. Thirdly, price factors and the terms of trade are discussed, followed by a summary of policy implications.
{"title":"World competitiveness and agriculture","authors":"J. Zyl","doi":"10.4102/SATNT.V16I1.658","DOIUrl":"https://doi.org/10.4102/SATNT.V16I1.658","url":null,"abstract":"Against the background of a changing environment in which market factors and greater world trade and competitiveness are increasingly becoming the only criteria for success, a framework for the analysis of world competitiveness is initially developed. This is followed by a discussion on the growth of productivity in agriculture, as well as an exposition of the role of agricultural research. Thirdly, price factors and the terms of trade are discussed, followed by a summary of policy implications.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70512861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper provides an overview of the use of machine vision in agriculture. Agriculture is practised in a more natural environment than most industrial undertakings, implying that agricultural automation requires robotic systems with well developed sensory abilities. For such systems, machine vision is an essential component. In this paper examples are used to show that the use of machine vision is already widespread in agriculture, and that there are many more potential applications for this technology. It is also indicated that machine vision in agriculture does not only hold potential financial advantages, but that it can also contribute to improved quality of life for agricultural workers, and even for farm animals.
{"title":"Machine vision in agriculture","authors":"J. Gouws","doi":"10.4102/satnt.v15i4.649","DOIUrl":"https://doi.org/10.4102/satnt.v15i4.649","url":null,"abstract":"This paper provides an overview of the use of machine vision in agriculture. Agriculture is practised in a more natural environment than most industrial undertakings, implying that agricultural automation requires robotic systems with well developed sensory abilities. For such systems, machine vision is an essential component. In this paper examples are used to show that the use of machine vision is already widespread in agriculture, and that there are many more potential applications for this technology. It is also indicated that machine vision in agriculture does not only hold potential financial advantages, but that it can also contribute to improved quality of life for agricultural workers, and even for farm animals.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70512661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
First generation cohorts of 25 specimens each of parental populations of Biomphalaria pfeifferi from four different localities, were each exposed to three Schistosoma mansoni miracidia per snail at an age of four weeks. The effect on survival was evaluated by calculating the weekly per capita mortality rates and the mean life-expectancy of the exposed snails. No significant differences could be demonstrated between the per capita mortality rates of F₁ cohorts of the two parental strains originating from localities in endemic bilharzia areas. Likewise there were no significant differences in this respect as far as F₁ cohorts of the two strains originating from localities in non-endemic bilharzia areas were concerned.
{"title":"The effect of exposure to miracidia of Schistosoma mansoni on mortality rates of cohorts of four geographical strains of Biomphalaria pfeifferi","authors":"K. Kock","doi":"10.4102/SATNT.V14I1.600","DOIUrl":"https://doi.org/10.4102/SATNT.V14I1.600","url":null,"abstract":"First generation cohorts of 25 specimens each of parental populations of Biomphalaria pfeifferi from four different localities, were each exposed to three Schistosoma mansoni miracidia per snail at an age of four weeks. The effect on survival was evaluated by calculating the weekly per capita mortality rates and the mean life-expectancy of the exposed snails. No significant differences could be demonstrated between the per capita mortality rates of F₁ cohorts of the two parental strains originating from localities in endemic bilharzia areas. Likewise there were no significant differences in this respect as far as F₁ cohorts of the two strains originating from localities in non-endemic bilharzia areas were concerned.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70512639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Increasing doses of 0,05, 0,1, 0,15 and 0,2 mg/kg of rDNA hirudin, a new anti-coagulant, were given subcutaneously to 20 volunteers (5 per dose) in order to investigate the tolerance and pharmacokinetics of the compound and its effects on coagulation. Hirudin was tolerated very well, the elimination half-life after subcutaneous injections is about 2 hours, about 40% of a given dose is excreted through the kidneys, and an excellent linear relationship was found between the area under the plasma concentration time curve and the dose. Hirudin increased partial thromboplastin time in a dose-related fashion.
{"title":"The clinical pharmacology of hirudin - a new anti-coagulant","authors":"Meyer Bh, F. Muller, H. Luus, N. Rey","doi":"10.4102/SATNT.V11I2.526","DOIUrl":"https://doi.org/10.4102/SATNT.V11I2.526","url":null,"abstract":"Increasing doses of 0,05, 0,1, 0,15 and 0,2 mg/kg of rDNA hirudin, a new anti-coagulant, were given subcutaneously to 20 volunteers (5 per dose) in order to investigate the tolerance and pharmacokinetics of the compound and its effects on coagulation. Hirudin was tolerated very well, the elimination half-life after subcutaneous injections is about 2 hours, about 40% of a given dose is excreted through the kidneys, and an excellent linear relationship was found between the area under the plasma concentration time curve and the dose. Hirudin increased partial thromboplastin time in a dose-related fashion.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1992-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70513023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kommunikasie is ’n terrein waarop tegnologiese ontwikkelings oor die jare heen ’n baie belangrike inslag gehad het en steeds het. Namate die tegnologie op hierdie terrein ontwikkel, word al hoe meer ekonomiese en ander menslike bedrywighede daardeur bevoordeel. In dieselfde mate word hierdie bedrywighede ook al meer afhangklik van die vlak van tegnologie wat in kommunikasie gebruik word. Dit bring mee dat lande (en ondernemings) wat nie tred hou met die tegnologiese ontwikkelings nie, al hoe meer uitgesluit sal raak van die voordele, en selfs mettertyd van effektiewe deelname aan sulke bedrywighede.
{"title":"Technology and communication","authors":"J. B. Clark","doi":"10.4102/SATNT.V11I1.519","DOIUrl":"https://doi.org/10.4102/SATNT.V11I1.519","url":null,"abstract":"Kommunikasie is ’n terrein waarop tegnologiese ontwikkelings oor die jare heen ’n baie belangrike inslag gehad het en steeds het. Namate die tegnologie op hierdie terrein ontwikkel, word al hoe meer ekonomiese en ander menslike bedrywighede daardeur bevoordeel. In dieselfde mate word hierdie bedrywighede ook al meer afhangklik van die vlak van tegnologie wat in kommunikasie gebruik word. Dit bring mee dat lande (en ondernemings) wat nie tred hou met die tegnologiese ontwikkelings nie, al hoe meer uitgesluit sal raak van die voordele, en selfs mettertyd van effektiewe deelname aan sulke bedrywighede.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1992-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70512838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The alkyne metathesis reaction is a direct result of the known and intensively studied alkene or olefin metathesis reaction. Unfortunately this reaction was never studied as intensively as the alkene metathesis reaction, mainly because of a lack of active catalytic systems. In the alkyn metathesis reaction the carbon-carbon triple bonds are broken and rearranged to give a redistribution of alkylidyne groups.
{"title":"The metathesis of alkynes","authors":"H. Vosloo, J. Plessis","doi":"10.4102/SATNT.V10I2.490","DOIUrl":"https://doi.org/10.4102/SATNT.V10I2.490","url":null,"abstract":"The alkyne metathesis reaction is a direct result of the known and intensively studied alkene or olefin metathesis reaction. Unfortunately this reaction was never studied as intensively as the alkene metathesis reaction, mainly because of a lack of active catalytic systems. In the alkyn metathesis reaction the carbon-carbon triple bonds are broken and rearranged to give a redistribution of alkylidyne groups.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1991-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70512781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Die resultate van vloeistofinsluitselstudies van die Proterosoiese gesteentes van die Noordwes-Kaap toon aan dat vlugtige bestanddele wat deelgeneem het aan die belangrikste laat - tot natektoniese geologiese prosesse in die Namakwa - mobiele gordel, eiesoortige kenmerke besit. Daar is ’n bree vloeistof-stamverwantskap wat teenwoordig is op verskillende struktuurterreine ten spyte van moontlik kontrasterende vroee TD-(temperatuur-druk)-geskiedenisse.
{"title":"Regional microthermometric data base for the Proterozoic rocks of the Northwestern Cape Province","authors":"A. E. Schoch, E. Klatt, D. Elsmere","doi":"10.4102/SATNT.V9I4.471","DOIUrl":"https://doi.org/10.4102/SATNT.V9I4.471","url":null,"abstract":"Die resultate van vloeistofinsluitselstudies van die Proterosoiese gesteentes van die Noordwes-Kaap toon aan dat vlugtige bestanddele wat deelgeneem het aan die belangrikste laat - tot natektoniese geologiese prosesse in die Namakwa - mobiele gordel, eiesoortige kenmerke besit. Daar is ’n bree vloeistof-stamverwantskap wat teenwoordig is op verskillende struktuurterreine ten spyte van moontlik kontrasterende vroee TD-(temperatuur-druk)-geskiedenisse.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70518310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The peat mould, Chromelosporium fulvum (Link) McGinty, Hennebert and Korf is a cosmopolitan fungus commonly occurring in greenhouses and on mushroom beds. In South Africa, however, this fungus remains relatively poorly known. In this paper the sometimes conflicting literature concerning the role of the peat mould in the mushroom industry is reviewed. Various aspects, including the characteristics and detrimental effects of the fungus on mushroom beds, as well as control measures, are discussed.
{"title":"Chromelosporium fulvum in the mushroom industry: a review","authors":"J. Coetzee","doi":"10.4102/SATNT.V9I3.460","DOIUrl":"https://doi.org/10.4102/SATNT.V9I3.460","url":null,"abstract":"The peat mould, Chromelosporium fulvum (Link) McGinty, Hennebert and Korf is a cosmopolitan fungus commonly occurring in greenhouses and on mushroom beds. In South Africa, however, this fungus remains relatively poorly known. In this paper the sometimes conflicting literature concerning the role of the peat mould in the mushroom industry is reviewed. Various aspects, including the characteristics and detrimental effects of the fungus on mushroom beds, as well as control measures, are discussed.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70518252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Die histologie en ultrastruktuur van die hepatopankreas van die bloukurper Oreochromis mossambicus word beskryf. ’n Dun bindweefselkapsel omring die lewer. Die hepatosietrangskikking vertoon as lobules, met die koorde van hepatosiete wat vanaf ’n sentrale vene uitradieer en met mekaar anastomaseer. Indiwiduele lewerlohules vertoon nie duidelike grense nie, maar enkele duidelike triades word wel in die lewer van O. mossambicus aangetref. Die hepatosiete bevat ’n enkele ronde kern met ’n duidelike nukleolus en die growwe endoplasmiese retikula kom in twee of meer rye om die kerne en teen die selgrense van die hepatosiete voor. Die ander sitoplasmiese organelle kom verspreid in die hepatosietsitoplasma voor. Die eksokriene pankreasselle is om die portale venes gesetel. Die kerne van hierdie selle is rond en is hasaal in die kubies- tot silindervormige selle gelee. ’n Goedontwikkelde growwe endoplasmiese retikulum — vesikuler, tubuler en sirkuler in vorm — en sektretoriese granules wat apikaal in die sel gelee is, kom voor.
{"title":"Die histologie en ultrastruktuur van die hepatopankreas van die bloukurper Oreochromis mossambicus","authors":"Marianne Nel, J. H. Swanepoel, H. J. Geyer","doi":"10.4102/SATNT.V9I1.432","DOIUrl":"https://doi.org/10.4102/SATNT.V9I1.432","url":null,"abstract":"Die histologie en ultrastruktuur van die hepatopankreas van die bloukurper Oreochromis mossambicus word beskryf. ’n Dun bindweefselkapsel omring die lewer. Die hepatosietrangskikking vertoon as lobules, met die koorde van hepatosiete wat vanaf ’n sentrale vene uitradieer en met mekaar anastomaseer. Indiwiduele lewerlohules vertoon nie duidelike grense nie, maar enkele duidelike triades word wel in die lewer van O. mossambicus aangetref. Die hepatosiete bevat ’n enkele ronde kern met ’n duidelike nukleolus en die growwe endoplasmiese retikula kom in twee of meer rye om die kerne en teen die selgrense van die hepatosiete voor. Die ander sitoplasmiese organelle kom verspreid in die hepatosietsitoplasma voor. Die eksokriene pankreasselle is om die portale venes gesetel. Die kerne van hierdie selle is rond en is hasaal in die kubies- tot silindervormige selle gelee. ’n Goedontwikkelde growwe endoplasmiese retikulum — vesikuler, tubuler en sirkuler in vorm — en sektretoriese granules wat apikaal in die sel gelee is, kom voor.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70518176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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