Da Rocha Perini V.,Pontifcia University Catolica Of Minas Gerais |
Sato Y.,Estacao de Hidrobiologia e Piscicultura de Tres Marias |
Rizzo E.,Federal University of Minas Gerais |
Bazzoli N.,Pontifcia University Catolica Of Minas Gerais
Zygote | Year: 2010
The black armoured catfish Rhinelepis aspera is an important commercial species found in the So Francisco River (Brazil) that has great potential for pisciculture. This paper presents, for the first time, information on the embryogenesis and larval development of this species. The breeder fish were subjected to spawning induction with crude carp pituitary extract. Eggs were kept in incubators at 24C and embryogenesis was observed with a stereomicroscope until hatching. Ovary fragments, samples of recently extruded oocytes and larvae were fixed in Bouin's solution and subjected to routine histology techniques. Recently extruded oocytes were also analyzed with a scanning electron microscope (SEM). Females (80%) had a positive response to hypophysation. Oocyte extrusion was performed at 8 h and 30 min after the second hormone injection and the fertilization rate achieved 72.4 8.8%. Recently extruded oocytes had a mean diameter of 1360.80 40.87 m and presented a conspicuous jelly coat covering the zona pellucida. Histochemical reactions indicated the presence of neutral glycoproteins in the yolk globules and in the zona pellucida. These reactions also indicated the presence of neutral glycoproteins and carboxylated acid glycoconjugates in the follicular cells and the jelly coat. These compounds form mucosubstances that can be related to the adhesiveness of the eggs. Under the SEM the oocytes presented a micropyle disc and a thick jelly coat over their surface. The closure of the blastopore occurred 9 h and 40 min after fertilization and embryogenesis was completed at 45 h and 50 min after fertilization, when the embryos were incubated at 24C. The total absorption of the yolk sac occurred during the fifth day indicating the need for an exogenous food supply. These results provide essential information for the successful breeding and management of the promising R. aspera. Copyright © 2009 Cambridge University Press.
Teixeira C.P.,Castelo Branco University |
Passos L.,CAPES Foundation |
Goulart V.D.L.R.,Pontifcia University Catolica Of Minas Gerais |
Hirsch A.,Pontifcia University Catolica Of Minas Gerais |
And 4 more authors.
Wildlife Research | Year: 2015
Context Reptiles, especially snakes, can cause a fear reaction in the public and are, therefore, a good model to examine human-wildlife conflicts. Human city dwellers often respond to the presence of snakes or other reptiles by calling out the responsible agency for animal control, which has to mediate the situation. Aims To determine how the temporal and spatial occurrence of human-reptile conflicts were associated with environmental conditions and socio-economic factors in a large Brazilian city (Belo Horizonte). Methods The callout reports of the Environmental Police of Belo Horizonte, Brazil, over a 7-year period from 2002 to 2008 to mediate reptile conflicts were analysed. Densities of callouts were determined by kernel-density estimator and matched with the vegetation cover and land use, to determine how the environment affected reptile callout distribution. The study area was divided into nine regions with different socio-economic and demographic characteristics to evaluate the possible effects of human factors in the conflict. Key results Reptile callouts were almost exclusively about snakes or freshwater turtles, despite a large population of wild lizards. In general, the difference in callout distribution of snakes and freshwater turtles was the result of different attitudes from city dwellers on the basis of socio-economic characteristics. Snakes were less frequent as urbanisation increased, whereas freshwater turtles were associated with water or open areas. Significantly, more conflicts occurred during the rainy season. People in areas of high per capita income used the Environmental Police as mediators more often than did those in poorer areas, but callouts were not related to human population density. Conclusions Habitat type and climate were significantly predictive of human-reptile conflicts. Human populations with higher salaries and education levels tended to resolve their conflicts with reptiles using official mediators whether the reptile was venomous or not. Implications The environmental and climatic data show that it is possible to predict when and where human-reptile conflicts are most likely. Thus, official mediators can use this information for targeted education programs. Such education programs should emphasise, at all levels of society, how to deal with such conflicts sensibly, so as to ensure the best outcomes for people and reptiles.