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National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Cambarellinae: Trpaslíci ve světě račích spermií?
 TOMAN, Jan
Recently, the ultrastructure of crayfish spermatozoa has become an increasingly studied topic. Up to now, the ultrastructure has been studied and defined in about fifteen species of freshwater species from all four crayfish families, however it has not yet been studied in a group of dwarf crayfish (subfamily Cambarellinae). Present work aimed to describe the spermatozoa ultrastructure of two dwarf crayfish species, specifically the Orange dwarf crayfish Cambarellus patzcuarensis and the Texas dwarf crayfish C. texanus. These species were then compared with the species already studied using morphological traits and biometric data. The ultrastructure of their spermatozoa shows commonly known patterns that include the acrosome and subacrosome in the front and the nucleus on the opposite side of the cell . Furthermore, radial arms typical for the superfamily Astacoidea that wrap around the nucleus and the whole cell enclosed by the extracellular capsule. The results show that the size of the acrosomes of Parastacidae membres is the smallest, while the crayfish of the Astacidae family show the largest acrosome. The current study points out a medium-sized acrosome of dwarf crayfish and Cambaridae in general, although they are located at the lower margin of this family with the Brazos crayfish being close to representatives of the Parastacidae. In conclusion, it is important to say that the combination of the morphological traits and biometric data of sperm acrosomes allows distinguishing individual crayfish groups to a large extent. This study may help to identify other species that have not been studied so far and could be a valuable basis for subsequent research of the ultrastructure and biometrics of crayfish spermatozoa.
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Rak mexický {Cambarellus patzcuarensis} - přehledová studie
TOMAN, Jan
Indigenous crayfish are increasingly threatened by their non-indigenous counterparts, which species are often more tolerant and adaptable. In case of North American species, they are also chronic carries of crayfish plague, a disease mostly lethal to crayfish of non-North American origin. In this bachelor thesis entitled "Mexican dwarf crayfish (Cambarellus patzcuarensis) - an overview", there is a summary containing available information about the Mexican dwarf crayfish, while main, so far unknown biological features of this species, are defined. Nowadays, this crayfish is one of the most bred and sold crayfish within the pet trade. However, its introductions can lead to unwanted alterations in newly occupied ecosystems. This overview of the available information on the Mexican dwarf crayfish and the definition of so far insufficiently known aspects of its biology can serve as a valuable basis for follow-up studies.
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