The histochemical patterns of leucine naphthylamidase (LNAase) and alkaline phosphatase (AP) activity have been studied in the developing alimentary tracts of embryos (20 mm. - 200 mm.) of the skate Raja binoculata Girard. The enzyme(s) LNAase was found only in the spiral valve mucosae possessing elongated adult-like villi. The activity level increases with the growth of the embryo. The enzyme(s) is probably not related to differentiative events of the spiral valve but rather a manifestation of a particular stage of functional differentiation. Several possible physiological functions of the enzyme(s) are discussed. The enzyme AP had a more general distribution. It was found in many differentiating regions of the digestive tract. Activity levels which were generally high in undifferentiated mesenchymal tissue, decreased with further differentiation in some tissues. In other regions where AP remained in the adult, the enzyme accumulated with advancing differentiation. The significance of AP in the various localizations is discussed. AP isozyme patterns during alimentary tract development were studied using polyacrylamide gel electrophoresis. These data were correlated with the histochemical localization of the enzyme activity. It appears that new molecular forms of AP arise during gut differentiation. The relationship between AP and differentiation is discussed and AP is related to specific function where applicable. / Science, Faculty of / Zoology, Department of / Graduate

Thèse de doctorat : Zoologie : Faculté des sciences de Paris : 1847. / Titre provenant de l'écran-titre.

The systematics of the Rajidae (skates) of southern Africa are revised, with a view to clearing up the confusion which now exists, and to forming a reliable basis for future biological studies. To date, some 150 - 160 species have been described for the genus Raja alone. The existing confusion probably results from the sexual dimorphism which occurs within the species and variation in form with growth. Modern methods advocate the use of characters, other than external features, the most reliable being the clasper anatomy, neurocranial structure and vertebral count, and these principles have been applied in the present revision.

Thesis (M.Sc.). / Written for the Dept. of Kinesiology and Physical Education. Title from title page of PDF (viewed 2008/07/24). Includes bibliographical references.

Members of the family Rajidae are common components of the demersal trawl fishery, contributing around 1% to the total catch. However, apart from a single species all South African rajids are currently discarded. With demands for new protein sources ever-increasing, it is possible that currently underutilised species, such as the skates will be utilized to a greater extent. Raja wallacei and R.pullopunctata are common trawler by-catch species, ranging along most of the South African coast. The current study allred to further knowledge on the population biology of both species through age and growth, reproductive and feeding studies. The study also allred to assess whether any of the South African skate species show the potential for utilization as a food source. Band counts of vertebral centra were used to determine growth parameters and generate growth curves for males and females of both species. Growth was significantly different between the sexes. In both cases, females grew slower than males but reached a greater asymptotic disc width. As with other elasmobranchs, R.wallacei and R.pullopunctata are long-lived and slow growing. As with all other skates, the study species are oviparous laying large, yolked eggs in tough, leathery cases on the sea bed. The onset of maturity occurs at a large size (approximately 400mm disc width (10-11 years of age) for R.wallacei and 600mm disc width (12-13 years of age) for Rpullopunctata) and is very rapid. The oldest R.wallacei and R.pullopunctata observed were 16 and 18 years of age, respectively. No distinct breeding season was determined and no nursery areas were observed. A large proportion of individuals, especially R.pullopunctata was immature. Both species fed primarily on crustaceans and teleosts with an ontogenetic shift in diet from mysids, amphipods, isopods and bregmatocerids to larger Gnathophis sp., Mursia cristimanus and carid shrimps. Large discrepancies were seen in the diet of animals spatially, temporally and between research and commercially-caught animals. Disc-width frequency data was limited but suggested that both species show preference for depths of 100-300m. Size distribution did not appear to be affected by depth, although the data set was limited. A paucity of large individuals in the catch may indicate that stocks are suffering from growth overfishing by trawling operations. Historical and observer data showed that although skates are common components of the by-catch, the potential for greater use is limited. The biscuit skate, R.straeleni, on the west coast is the only species that could be better utilized. If skates are treated as a single group the potential is increased but this causes problems in assessing stocks.

No description available.

The purpose of this study was to determine the physiological response of an in-line submaximal skate on two surfaces using two wheel types and two bearing types. The variables measured were V0$ sb2$ and HR. Ten male varsity hockey players volunteered as subjects. The subjects, after being assigned one of two wheel types with varying durometers, skated the submaximal test twice for each surface (concrete and asphalt) using a different type of bearing (precision and semi-precision) each time. These results were compared to a similar on-ice submaximal skating test session. / Results revealed no significant difference between in-line skating with wheels of 78 and 82 Shore A durometers (p $<$.05) with both V0$ sb2$ and HR as markers. A significant difference was found between in-line skating with precision and semi-precision bearings with V0$ sb2$ as a marker (p $<$.05), however, not with HR as a marker (p = 0.31). On-ice skating was significantly different from in-line skating on concrete and asphalt surfaces for both physiological markers. In-line skating on asphalt and concrete surfaces resulted in similar physiological responses. It was concluded that hockey players training with in-line skates obtain the same training benefits using either wheel durometers, but will have greater oxygen costs when training with semi-precision bearings than training with precision bearings.

No description available.

Analisaram-se as proporções de Rioraja agassizi, Atlantoraja cyclophora, A. platana e A. castelnaui na categoria “raias-emplastros", nos desmbarques de 11 embarcações da pesca comercial, de arrasto duplo de portas e de parelhas, totalizando 358 lances realizados em 20 viagens. Elas atuaram entre as isóbatas de 10 e 430 m e entre os paralelos 23° S (Estado do Rio de Janeiro) e 31° S (Estado do Rio Grande do Sul), de 1995 a 1997 e de 2001 a 2003. Entre as espécies estudadas, A. cyclophora foi a mais freqüente nos lances realizados entre 60 e 265 m de profundidade, com ampla distribuição entre 23° 30’ S e 27°20’ S. As análises das pescarias sugerem que a profundidade e a latitude, entre outras variáveis, foram importantes apenas na captura de A. cyclophora. As carcaças foram desembarcadas em três tipos de cortes, a partir dos quais o peso corporal foi estimado. Também foram avaliadas as estruturas populacionais das quatro espécies. Os estimadores dos parâmetros de crescimento, largura de disco (LD) de primeira maturação sexual e taxa de mortalidade natural (M) foram calculados para machos e fêmeas, respectivamente: R. agassizi LD&#61605; = 289 mm e 425 mm; K= 0,142 e 0,078 ano-1; t0= -1,653 e -1,811 anos; LD50 = 270 e 330 mm, M = 0,061 e 0,052 ano-1; A. cyclophora LD&#61605; = 478 e 518 mm; K= 0,077 e 0,073 ano-1; t0= -4,518 e -4,485 anos; LD50 = 355 e 415 mm, M = 0,085 e 0,085 ano-1; A. platana LD&#61605; = 733 e 823 mm; K= 0,057 e 0,052 ano-1; t0= -1,267 e -1,225 anos; LD50 = 500 e 550 mm, M = 0,061 e 0,021 ano-1; A. castelnaui LD&#61605; = 794 e 1004 mm; K= 0,066 e 0,046 ano-1; t0= -1,978 e -2,235 anos; LD50 = 670 e 740 mm, M = 0,069 e 0,047 ano-1. Em alguns anos, o modelo relativo de rendimento-por-recruta resultou em valores próximos ou superiores aos pontos de referência biológica para machos de R. agassizi, e fêmeas de A. platana e de A. castelnaui. As taxas de explotação e mortalidade por pesca de A. cyclophora foram crescentes entre 2001 e 2003. / The proportions of the skates Rioraja agassizi, Atlantoraja cyclophora, A. platana and A. castelnaui landed by commercial fishing boats were analyzed. Data were collected from 358 hauls of 20 trips made by 11 double-otter trawlers and pair-trawlers. Fisheries were carried out between 10 and 430 m deep and from 23° S (State of Rio de Janeiro) to 31° S (State of Rio Grande do Sul) between 1995-1997 and 2001-2003. A. cyclophora was the most frequent in all hauls between 60 and 265 m deep among the studied species, with a wide distribution between 23°30’ S and 27°20’ S. The analyses of the fisheries suggested that depth and latitude, along with other variables, have importance only for A. cyclophora catches. The skates carcasses were landed in three types of cuts from which the body weight was estimated. The population structures of the four species were also evaluated. The growth parameters estimates, the disc width (DW) at first sexual maturation and the instantaneous natural mortality rate (M) for males and females were, respectively: R. agassizi: DW&#61605; = 289 mm and 425 mm; K= 0,142 and 0,078 year-1; t0 = -1,653 and -1,811 years; DW50 = 270 and 330 mm, M = 0,061 and 0,052 year-1; A. cyclophora: DW&#61605; = 478 and 518 mm; K= 0,077 and 0,073 year-1; t0= -4,518 and -4,485 years; DW50 = 355 and 415 mm, M = 0,085 and 0,085 year-1; A. platana: DW&#61605; = 733 and 823 mm; K= 0,057 and 0,052 year-1; t0= -1,267 and -1,225 years; DW50 = 500 and 550 mm, M = 0,061 and 0,021 year-1; A. castelnaui: DW&#61605; = 794 and 1004 mm; K= 0,066 and 0,046 year-1; t0 = -1,978 and -2,235 years; DW50 = 670 and 740 mm, M = 0,069 and 0,047 year-1. In some years, the relative yield-per-recruit model resulted values similar or higher than the biological reference points estimated for males of R. agassizi and females of A. platana and A. castelnaui. The exploitation ratio and the instantaneous fishery mortality rate for A. cyclophora increased between 2001 and 2003.

Analisaram-se as proporções de Rioraja agassizi, Atlantoraja cyclophora, A. platana e A. castelnaui na categoria “raias-emplastros”, nos desmbarques de 11 embarcações da pesca comercial, de arrasto duplo de portas e de parelhas, totalizando 358 lances realizados em 20 viagens. Elas atuaram entre as isóbatas de 10 e 430 m e entre os paralelos 23° S (Estado do Rio de Janeiro) e 31° S (Estado do Rio Grande do Sul), de 1995 a 1997 e de 2001 a 2003. Entre as espécies estudadas, A. cyclophora foi a mais freqüente nos lances realizados entre 60 e 265 m de profundidade, com ampla distribuição entre 23° 30’ S e 27°20’ S. As análises das pescarias sugerem que a profundidade e a latitude, entre outras variáveis, foram importantes apenas na captura de A. cyclophora. As carcaças foram desembarcadas em três tipos de cortes, a partir dos quais o peso corporal foi estimado. Também foram avaliadas as estruturas populacionais das quatro espécies. Os estimadores dos parâmetros de crescimento, largura de disco (LD) de primeira maturação sexual e taxa de mortalidade natural (M) foram calculados para machos e fêmeas, respectivamente: R. agassizi LD&#61605; = 289 mm e 425 mm; K= 0,142 e 0,078 ano-1; t0= -1,653 e -1,811 anos; LD50 = 270 e 330 mm, M = 0,061 e 0,052 ano-1; A. cyclophora LD&#61605; = 478 e 518 mm; K= 0,077 e 0,073 ano-1; t0= -4,518 e -4,485 anos; LD50 = 355 e 415 mm, M = 0,085 e 0,085 ano-1; A. platana LD&#61605; = 733 e 823 mm; K= 0,057 e 0,052 ano-1; t0= -1,267 e -1,225 anos; LD50 = 500 e 550 mm, M = 0,061 e 0,021 ano-1; A. castelnaui LD&#61605; = 794 e 1004 mm; K= 0,066 e 0,046 ano-1; t0= -1,978 e -2,235 anos; LD50 = 670 e 740 mm, M = 0,069 e 0,047 ano-1. Em alguns anos, o modelo relativo de rendimento-por-recruta resultou em valores próximos ou superiores aos pontos de referência biológica para machos de R. agassizi, e fêmeas de A. platana e de A. castelnaui. As taxas de explotação e mortalidade por pesca de A. cyclophora foram crescentes entre 2001 e 2003. / The proportions of the skates Rioraja agassizi, Atlantoraja cyclophora, A. platana and A. castelnaui landed by commercial fishing boats were analyzed. Data were collected from 358 hauls of 20 trips made by 11 double-otter trawlers and pair-trawlers. Fisheries were carried out between 10 and 430 m deep and from 23° S (State of Rio de Janeiro) to 31° S (State of Rio Grande do Sul) between 1995-1997 and 2001-2003. A. cyclophora was the most frequent in all hauls between 60 and 265 m deep among the studied species, with a wide distribution between 23°30’ S and 27°20’ S. The analyses of the fisheries suggested that depth and latitude, along with other variables, have importance only for A. cyclophora catches. The skates carcasses were landed in three types of cuts from which the body weight was estimated. The population structures of the four species were also evaluated. The growth parameters estimates, the disc width (DW) at first sexual maturation and the instantaneous natural mortality rate (M) for males and females were, respectively: R. agassizi: DW&#61605; = 289 mm and 425 mm; K= 0,142 and 0,078 year-1; t0 = -1,653 and -1,811 years; DW50 = 270 and 330 mm, M = 0,061 and 0,052 year-1; A. cyclophora: DW&#61605; = 478 and 518 mm; K= 0,077 and 0,073 year-1; t0= -4,518 and -4,485 years; DW50 = 355 and 415 mm, M = 0,085 and 0,085 year-1; A. platana: DW&#61605; = 733 and 823 mm; K= 0,057 and 0,052 year-1; t0= -1,267 and -1,225 years; DW50 = 500 and 550 mm, M = 0,061 and 0,021 year-1; A. castelnaui: DW&#61605; = 794 and 1004 mm; K= 0,066 and 0,046 year-1; t0 = -1,978 and -2,235 years; DW50 = 670 and 740 mm, M = 0,069 and 0,047 year-1. In some years, the relative yield-per-recruit model resulted values similar or higher than the biological reference points estimated for males of R. agassizi and females of A. platana and A. castelnaui. The exploitation ratio and the instantaneous fishery mortality rate for A. cyclophora increased between 2001 and 2003.